Question: Individuals with diabetes and acute coronary syndrome have a higher short-term and long-term likelihood of bleeding incidents.

Platelet Glycoprotein IIb/IIIa Inhibitors: A Lifesaving Strategy for Diabetic Patients with Non-ST-Segment Elevation Acute Coronary Syndromes. Diabetes mellitus is a crucial factor contributing to adverse outcomes in patients experiencing acute coronary syndromes (ACS). Given the potential for heightened platelet aggregation in diabetic patients, we sought to determine if they might gain additional advantages from platelet glycoprotein (GP) IIb/IIIa receptor blockers. We conducted a meta-analysis focusing on diabetic patients enrolled in six major platelet GP IIb/IIIa inhibitor trials: PRISM, PRISM-PLUS, PARAGON A, PARAGON B, PURSUIT, and GUSTO IV. Among the 6,458 diabetic patients analyzed, the application of platelet GP IIb/IIIa inhibitors was linked to a substantial reduction in mortality rates at 30 days, dropping from 6.2% to 4.6% (OR 0.74; 95% CI 0.59 to 0.92; P=0.007). In contrast, there was no observed survival benefit in the 23,072 non-diabetic patients (3.0% versus 3.0%). The diabetic status in relation to the impact of platelet GP IIb/IIIa inhibition was found to be statistically significant (P=0.036). Among the 1,279 diabetic patients who underwent percutaneous coronary intervention (PCI) during their hospitalization, the use of these drugs was correlated with a mortality decrease at 30 days from 4.0% to 1.2% (OR 0.30; 95% CI 0.14 to 0.69; P=0.002). This meta-analysis, which encompasses the full spectrum of large-scale trial data on intravenous platelet GP IIb/IIIa inhibitors for non-ST-segment-elevation ACS, indicates that these agents might significantly lower mortality at 30 days in diabetic patients. Although not derived from a randomized study, the survival advantage appears to be more pronounced in patients undergoing PCI. Therefore, the use of platelet GP IIb/IIIa inhibitors should be highly recommended for diabetic patients with ACS.

ContextSeveral novel risk factors for atherosclerosis have recently been proposed, but few comparative data exist to guide clinical use of these emerging biomarkers. ObjectiveTo compare the predictive value of 11 lipid and nonlipid biomarkers as risk factors for development of symptomatic peripheral arterial disease (PAD).Design, Setting, and ParticipantsNested case-control study using plasma samples collected at baseline from a prospective cohort of 14 916 initially healthy US male physicians aged 40 to 84 years, of whom 140 subsequently developed symptomatic PAD (cases); 140 age- and smoking status–matched men who remained free of vascular disease during an average 9-year follow-up period were randomly selected as controls. Main Outcome MeasureIncident PAD, as determined by baseline total cholesterol, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), total cholesterol–HDL-C ratio, triglycerides, homocysteine, C-reactive protein (CRP), lipoprotein(a), fibrinogen, and apolipoproteins (apo) A-I and B-100.ResultsIn univariate analyses, plasma levels of total cholesterol (P<.001), LDL-C (P = .001), triglycerides (P = .001), apo B-100 (P = .001), fibrinogen (P = .02), CRP (P = .006), and the total cholesterol–HDL-C ratio (P<.001) were all significantly higher at baseline among men who subsequently developed PAD compared with those who did not, while levels of HDL-C (P = .009) and apo A-I (P = .05) were lower. Nonsignificant baseline elevations of lipoprotein(a) (P = .40) and homocysteine (P = .90) were observed. In multivariable analyses, the total cholesterol–HDL-C ratio was the strongest lipid predictor of risk (relative risk [RR] for those in the highest vs lowest quartile, 3.9; 95% confidence interval [CI], 1.7-8.6), while CRP was the strongest nonlipid predictor (RR for the highest vs lowest quartile, 2.8; 95% CI, 1.3-5.9). In assessing joint effects, addition of CRP to standard lipid screening significantly improved risk prediction models based on lipid screening alone (P<.001).ConclusionsOf 11 atherothrombotic biomarkers assessed at baseline, the total cholesterol–HDL-C ratio and CRP were the strongest independent predictors of development of peripheral arterial disease. C-reactive protein provided additive prognostic information over standard lipid measures.

CONTEXT While it is established that management strategies and outcomes differ by gender for many diseases, its effect on infection has not been adequately studied. OBJECTIVE To investigate the role of gender among hospitalized patients treated for infection. DESIGN Observational cohort study conducted during a 26-month period from December 1996 through January 1999. SETTING University-affiliated hospital. PARTICIPANTS A total of 892 patients in the surgical units of the hospital with 1470 consecutive infectious episodes (782 in men and 688 in women). MAIN OUTCOME MEASURES Mortality during hospitalization by gender for infection episodes overall and for specific infectious sites, including lung, peritoneum, bloodstream, catheter, urine, surgical site, and skin/soft tissue. RESULTS Among all infections, there was no significant difference in mortality based on gender (men, 11.1% vs women, 14.2%; P = .07). After logistic regression analysis, factors independently associated with mortality included higher APACHE (Acute Physiology and Chronic Health Evaluation) II score, older age, malignancy, blood transfusion, and diagnosis of infection more than 7 days after admission, but not gender (female odds ratio [OR] for death, 1.32; 95% confidence interval [CI], 0.90-1.94; P = .16). Mortality was higher in women for lung (men, 18% vs women, 34%; P = .002) and soft tissue (men, 2% vs women, 10%; P < or = .05) infection; for other infectious sites, mortality did not differ by gender. Factors associated with mortality due to pneumonia by logistic regression included higher APACHE II score, malignancy, diabetes mellitus, diagnosis of infection more than 7 days after admission, older age, transplantation, and female gender (OR for death, 2.25; 95% CI, 1.17-4.32; P = .02). CONCLUSIONS Although gender may not be predictive of mortality among all infections, women appear to be at increased risk for death from hospital-acquired pneumonia, even after controlling for other comorbidities.

OBJECTIVE To determine the effects of smoking, plasma lipids, lipoproteins, apolipoproteins, and fibrinogen on the patency of saphenous vein femoropopliteal bypass grafts at one year. DESIGN Prospective study of patients with saphenous vein femoropopliteal bypass grafts entered into a multicentre trial. SETTING Surgical wards, outpatient clinics, and home visits coordinated by two tertiary referral centres in London and Birmingham. PATIENTS 157 Patients (mean age 66.6 (SD 8.2) years), 113 with patent grafts and 44 with occluded grafts one year after bypass. MAIN OUTCOME MEASURE Cumulative percentage patency at one year. RESULTS Markers for smoking (blood carboxyhaemoglobin concentration (p less than 0.05) and plasma thiocyanate concentration (p less than 0.01) and plasma concentrations of fibrinogen (p less than 0.001) and apolipoproteins AI (p less than 0.04) and (a) (p less than 0.05) were significantly higher in patients with occluded grafts. Serum cholesterol concentrations were significantly higher in patients with grafts that remained patent one year after bypass (p less than 0.005). Analysis of the smoking markers indicated that a quarter of patients (40) were untruthful in their claims to have stopped smoking. Based on smoking markers, patency of grafts in smokers was significantly lower at one year by life table analysis than in non-smokers (63% v 84%, p less than 0.02). Patency was significantly higher by life table analysis in patients with a plasma fibrinogen concentration below the median than in those with a concentration above (90% v 57%, p less than 0.0002). Surprisingly, increased plasma low density lipoprotein cholesterol concentration was significantly associated with improved patency at one year (85%) at values above the median compared with patency (only 68%) at values in the lower half of the range (p less than 0.02). CONCLUSIONS Plasma fibrinogen concentration was the most important variable predicting graft occlusion, followed by smoking markers. A more forceful approach is needed to stop patients smoking; therapeutic measures to improve patency of vein grafts should focus on decreasing plasma fibrinogen concentration rather than serum cholesterol concentration.

BACKGROUND Type 1 diabetes results from T-cell-mediated destruction of β cells. Findings from preclinical studies and pilot clinical trials suggest that antithymocyte globulin (ATG) might be effective for reducing this autoimmune response. We assessed the safety and efficacy of rabbit ATG in preserving islet function in participants with recent-onset type 1 diabetes, and report here our 12-month results. METHODS For this phase 2, randomised, placebo-controlled, clinical trial, we enrolled patients with recent-onset type 1 diabetes, aged 12-35 years, and with a peak C-peptide of 0.4 nM or greater on mixed meal tolerance test from 11 sites in the USA. We used a computer generated randomisation sequence to randomly assign patients (2:1, with permuted-blocks of size three or six and stratified by study site) to receive either 6.5 mg/kg ATG or placebo over a course of four days. All participants were masked and initially managed by an unmasked drug management team, which managed all aspects of the study until month 3. Thereafter, to maintain masking for diabetes management throughout the remainder of the study, participants received diabetes management from an independent, masked study physician and nurse educator. The primary endpoint was the baseline-adjusted change in 2-h area under the curve C-peptide response to mixed meal tolerance test from baseline to 12 months. Analyses were by intention to treat. This is a planned interim analysis of an on-going trial that will run for 24 months of follow-up. This study is registered with ClinicalTrials.gov, number NCT00515099. FINDINGS Between Sept 10, 2007, and June 1, 2011, we screened 154 individuals, randomly allocating 38 to ATG and 20 to placebo. We recorded no between-group difference in the primary endpoint: participants in the ATG group had a mean change in C-peptide area under the curve of -0.195 pmol/mL (95% CI -0.292 to -0.098) and those in the placebo group had a mean change of -0.239 pmol/mL (-0.361 to -0.118) in the placebo group (p=0.591). All except one participant in the ATG group had both cytokine release syndrome and serum sickness, which was associated with a transient rise in interleukin-6 and acute-phase proteins. Acute T cell depletion occurred in the ATG group, with slow reconstitution over 12 months. However, effector memory T cells were not depleted, and the ratio of regulatory to effector memory T cells declined in the first 6 months and stabilised thereafter. ATG-treated patients had 159 grade 3-4 adverse events, many associated with T-cell depletion, compared with 13 in the placebo group, but we detected no between-group difference in incidence of infectious diseases. INTERPRETATION Our findings suggest that a brief course of ATG does not result in preservation of β-cell function 12 months later in patients with new-onset type 1 diabetes. Generalised T-cell depletion in the absence of specific depletion of effector memory T cells and preservation of regulatory T cells seems to be an ineffective treatment for type 1 diabetes.

BACKGROUND Patients considered for arterial surgery, have been shown to have a high incidence of coexistent cardiac, vascular and other diseases, affecting operative risk and survival. We developed a systematic workup strategy for detecting these coexistent diseases in our vascular surgical patients, mainly based on non-invasive diagnostic techniques. METHODS We evaluated 200 consecutive patients, admitted to the department of vascular surgery in an academic teaching hospital, in order to establish the total incidence of relevant concomitant disorders, the extent to which this screening yielded previously unknown diagnostic information, and the impact on short-term (one year) survival. RESULTS Coronary artery disease was present in 46% of the patients; 22% had active ischaemia, newly diagnosed in 5.5%. Impaired cardiac function was found in 37%: severely impaired in 12%, newly diagnosed in 27%. Carotid artery disease was present in 32%: critical stenoses were found in 9%; new diagnoses in 29.9%. Aortic aneurysms were present in 7%, newly diagnosed in 5%. Severe renal artery stenosis was present in 5%, newly diagnosed in 3.5%. Sixteen % of the patients had chronic obstructive pulmonary disease, newly diagnosed in 3.5%, and 4.5% had unexpected disorders, which were all new diagnoses. Overall, new diagnoses were reached in 64.5% of the population, affecting therapeutic strategy immediately in 21% of the patients. The presence of coronary artery disease and of cardiac failure were clearly related to one year survival. CONCLUSIONS We conclude that a systematic screening strategy, mainly based on noninvasive techniques, can detect the presence of concomitant diseases in the vascular surgical patient. Most important seem the newly diagnosed diseases altering surgical management in one out of every five patients; they also have important implications for patient prognosis.

AIMS Trabecular bone score (TBS) is a surrogate indicator of bone microarchitecture. The presenent study sought to examine the association between type 2 diabetes (T2D) and trabecular bone score (TBS) in adult Vietnamese men and women. METHODS The study was part of the Vietnam Osteoporosis Study, in which 2702 women and 1398 men aged ≥30 yrs were recruited from the general community in Ho Chi Minh City. HbA1c levels were measured by the ADAMS™ A1c HA-8160 (Arkray, Kyoto, Japan), and classified into 3 groups: normal if HbA1c <5.7%; pre-diabetes (5.7 to 6.4%); and diabetes (>6.4%). TBS was evaluated by iNsight Software, version 2.1 (Medimaps, Merignac, France) on lumbar spine BMD scan (Hologic Horizon). Differences in TBS between diabetic status were analyzed by the multivariable regression model with adjustment for age and body mass index. RESULTS The prevalence of pre-diabetes and diabetes in men and women was 30.2% and 8.3%, respectively. In women, TBS was lower in pre-diabetes (-0.02; P<0.001) and diabetes (-0.02; P<0.001) compared with normal individuals. In men, there was no statistically significant difference in TBS between diabetic status. Moreover, TBS was significantly inversely correlated with HbA1c levels in women (P = 0.01), but not in men (P = 0.89). CONCLUSION Women, but not men, with type 2 diabetes and pre-diabetes have lower TBS than individuals without diabetes. These data suggest that diabetes and prediabetes are associated with deterioration of bone microarchitecture.

CONTEXT Trabecular bone score (TBS) is a novel texture index that evaluates the pixel gray-level variations in lumbar spine dual-energy X-ray absorptiometry images and is related to bone microarchitecture independent of bone mineral density (BMD). OBJECTIVE We investigated lumbar spine TBS as an indicator for skeletal deterioration in diabetes. DESIGN AND SETTING Cross-sectional data were collected from subjects participating in an ongoing prospective, community-based, cohort study from 2009 to 2010. PARTICIPANTS We included 1229 men and 1529 postmenopausal women older than 50 years in the Ansung cohort. OUTCOME MEASURES Biochemical parameters, lumbar spine TBS, and BMD from dual-energy X-ray absorptiometry images were measured. RESULTS Lumbar spine TBS was lower in men with diabetes than in nondiabetic men (1.287 ± 0.005 vs 1.316 ± 0.003, P < .001), whereas lumbar spine BMD was higher in men with diabetes (1.135 ± 0.010 vs 1.088 ± 0.006 g/cm(2)). Lumbar spine TBS was lower in women with diabetes than in nondiabetic women only in an unadjusted model (1.333 ± 0.004 vs 1.353 ± 0.003). However, women younger than 65 years (n = 707) with diabetes had a lower TBS than those without diabetes, even after adjusted for covariates (P < .001). Diabetes was not associated with BMD at femur sites in both genders. TBS was negatively correlated with glycated hemoglobin, fasting plasma glucose, fasting insulin, and homeostasis model assessment for insulin resistance but not with homeostasis model assessment for β-cell function in both genders. CONCLUSIONS The inverse association between lumbar spine TBS and insulin resistance may make it an indicator for determining skeletal deterioration in diabetic patients who have high BMD.

INTRODUCTION Induction of an inflammatory response is thought to have a significant role in the complications that follow cardiopulmonary bypass (CPB). The statin drugs are increasingly being recognized as having potent anti-inflammatory effects and hence have potential to influence an important mechanism of injury in CPB, although there is no current confirmation that this is indeed the case. Our objective was to systematically review if pre-operative prophylactic statin therapy, compared with placebo or standard of care, can decrease the inflammatory response in people undergoing heart surgery with CPB. METHODS We performed a systematic and comprehensive literature search for all randomized controlled trials (RCTs) of open heart surgery with CPB in adults or children who received prophylactic statin treatment prior to CPB, with reported outcomes which included markers of inflammation. Two authors independently identified eligible studies, extracted data, and assessed study quality using standardized instruments. Weighted mean difference (WMD) was the primary summary statistic with data pooled using a random effects model. Descriptive analysis was used when data could not be pooled. RESULTS Eight RCTs were included in the review, with the number of trials for each inflammatory outcome being even more limited. Pooled data demonstrated benefit with the use of statin to attenuate the post-CPB increase in interleukins 6 and 8 (IL-6, IL-8), peak high sensitivity C-reactive protein (hsCRP), and tumor necrosis factor-alpha (TNF-alpha) post-CPB (WMD [95% confidence interval (CI)] -23.5 pg/ml [-36.6 to -10.5]; -23.4 pg/ml [-35.8 to -11.0]; -15.3 mg/L [CI -26.9 to -3.7]; -2.10 pg/ml [-3.83 to -0.37] respectively). Very limited RCT evidence suggests that prophylactic statin therapy may also decrease adhesion molecules following CPB including neutrophil CD11b and soluble P (sP)-selectin. CONCLUSIONS Although the RCT evidence may suggest a reduction in post-CPB inflammation by statin therapy, the evidence is not definitive due to significant limitations. Several of the trials were not methodologically rigorous and statin intervention was highly variable in this small number of studies. This systematic review demonstrates that there is a significant gap that exists in the current literature in regards to the potential anti-inflammatory effect of statin therapy prior to CPB.

The allocation of hypoglycaemic symptoms to autonomie or neuroglycopenic groups tends to occur on an a priori basis. In view of the practical need for clear symptom markers of hypoglycaemia more scientific approaches must be pursued. Substantial evidence is presented from two large scale studies we performed which support a three factor model of hypoglycaemic symptomatology, based on the statistical associations discovered among symptoms reported by diabetic patients. Study 1 involved 295 insulin-treated outpatients and found that 11 key hypoglycaemic symptoms segregated into three clear factors: autonomie (sweating, palpitation, shaking and hunger) neuroglycopenic (confusion, drowsiness, odd behaviour, speech difficulty and incoordination), and malaise (nausea and headache). The three factors were validated on a separate group of 303 insulin-treated diabetic out-patients. Confirmatory factor analyses showed that the three factor model was the optimal model for explaining symptom covariance in each group. A multi-sample confirmatory factor analysis tested the rigorous assumptions that the relative loadings of symptoms on factors across groups were equal, and that the residual variance for each symptom was identical across groups. These assumptions were successful, indicating that the three factor model was replicated in detail across these two large samples. It is suggested that the results indicate valid groupings of symptoms that may be used in future research and in clinical practice.

AIMS The aim of this study was to compare the effects of calorie-restricted vegetarian and conventional diabetic diets alone and in combination with exercise on insulin resistance, visceral fat and oxidative stress markers in subjects with Type 2 diabetes. METHODS A 24-week, randomized, open, parallel design was used. Seventy-four patients with Type 2 diabetes were randomly assigned to either the experimental group (n = 37), which received a vegetarian diet, or the control group (n = 37), which received a conventional diabetic diet. Both diets were isocaloric, calorie restricted (-500 kcal/day). All meals during the study were provided. The second 12 weeks of the diet were combined with aerobic exercise. Participants were examined at baseline, 12 weeks and 24 weeks. Primary outcomes were: insulin sensitivity measured by hyperinsulinaemic isoglycaemic clamp; volume of visceral and subcutaneous fat measured by magnetic resonance imaging; and oxidative stress measured by thiobarbituric acid reactive substances. Analyses were by intention to treat. RESULTS Forty-three per cent of participants in the experimental group and 5% of participants in the control group reduced diabetes medication (P < 0.001). Body weight decreased more in the experimental group than in the control group [-6.2 kg (95% CI -6.6 to -5.3) vs. -3.2 kg (95% CI -3.7 to -2.5); interaction group × time P = 0.001]. An increase in insulin sensitivity was significantly greater in the experimental group than in the control group [30% (95% CI 24.5-39) vs. 20% (95% CI 14-25), P = 0.04]. A reduction in both visceral and subcutaneous fat was greater in the experimental group than in the control group (P = 0.007 and P = 0.02, respectively). Plasma adiponectin increased (P = 0.02) and leptin decreased (P = 0.02) in the experimental group, with no change in the control group. Vitamin C, superoxide dismutase and reduced glutathione increased in the experimental group (P = 0.002, P < 0.001 and P = 0.02, respectively). Differences between groups were greater after the addition of exercise training. Changes in insulin sensitivity and enzymatic oxidative stress markers correlated with changes in visceral fat. CONCLUSIONS A calorie-restricted vegetarian diet had greater capacity to improve insulin sensitivity compared with a conventional diabetic diet over 24 weeks. The greater loss of visceral fat and improvements in plasma concentrations of adipokines and oxidative stress markers with this diet may be responsible for the reduction of insulin resistance. The addition of exercise training further augmented the improved outcomes with the vegetarian diet.


Question: Individuals with diabetes who have acute coronary syndrome have a higher short-term and long-term likelihood of bleeding incidents.

Long-term Prognostic Impact of Diabetes in Patients with Unstable Angina and Non-ST-Elevation Myocardial Infarction: Insights from the OASIS Registry.
CONTEXT Despite being a frequent cause for admission to coronary care units, the long-term outcome for patients diagnosed with unstable coronary artery disease, particularly those with diabetes mellitus, remains unclear. Given the heightened morbidity and mortality rates associated with acute myocardial infarction in diabetic patients, understanding their prognosis is critical. DESIGN, SETTING, AND PARTICIPANTS A retrospective analysis was conducted on data from the Organization to Assess Strategies for Ischemic Syndromes (OASIS) registry, encompassing 8,013 patients across six countries. The study aimed to evaluate the two-year prognosis of diabetic and non-diabetic patients admitted with unstable angina or non-ST-elevation myocardial infarction. RESULTS Out of the total population, 21% (1,718 patients) were diabetic. Diabetic patients underwent coronary bypass surgery more frequently than their non-diabetic counterparts (23% vs. 20%, p<0.001), yet rates of catheterization and angioplasty were comparable. Diabetes was identified as an independent predictor for mortality (Relative Risk [RR] 1.57, 95% CI 1.38-1.81, p<0.001), and also for cardiovascular death, new myocardial infarction, stroke, and new onset of congestive heart failure. Notably, diabetic women faced a higher risk than men (RR 1.98, 95% CI 1.60-2.44 for women vs. RR 1.28, 95% CI 1.06-1.56 for men). Interestingly, diabetic patients without a history of cardiovascular disease had similar event rates for all outcomes to non-diabetic patients with prior vascular disease. CONCLUSIONS Hospitalization for unstable angina or non-ST-elevation myocardial infarction is associated with a high two-year morbidity and mortality, particularly pronounced in diabetic patients. Diabetic patients without prior cardiovascular disease exhibit the same long-term outcomes as non-diabetic patients with established cardiovascular disease following hospitalization for unstable coronary artery disease.

The allocation of hypoglycaemic symptoms to autonomie or neuroglycopenic groups tends to occur on an a priori basis. In view of the practical need for clear symptom markers of hypoglycaemia more scientific approaches must be pursued. Substantial evidence is presented from two large scale studies we performed which support a three factor model of hypoglycaemic symptomatology, based on the statistical associations discovered among symptoms reported by diabetic patients. Study 1 involved 295 insulin-treated outpatients and found that 11 key hypoglycaemic symptoms segregated into three clear factors: autonomie (sweating, palpitation, shaking and hunger) neuroglycopenic (confusion, drowsiness, odd behaviour, speech difficulty and incoordination), and malaise (nausea and headache). The three factors were validated on a separate group of 303 insulin-treated diabetic out-patients. Confirmatory factor analyses showed that the three factor model was the optimal model for explaining symptom covariance in each group. A multi-sample confirmatory factor analysis tested the rigorous assumptions that the relative loadings of symptoms on factors across groups were equal, and that the residual variance for each symptom was identical across groups. These assumptions were successful, indicating that the three factor model was replicated in detail across these two large samples. It is suggested that the results indicate valid groupings of symptoms that may be used in future research and in clinical practice.

BACKGROUND The Digitalis Investigation Group trial reported that treatment with digoxin did not decrease overall mortality among patients with heart failure and depressed left ventricular systolic function, although it did reduce hospitalizations slightly. Even though the epidemiologic features, causes, and prognosis of heart failure vary between men and women, sex-based differences in the effect of digoxin were not evaluated. METHODS We conducted a post hoc subgroup analysis to assess whether there were sex-based differences in the effect of digoxin therapy among the 6800 patients in the Digitalis Investigation Group study. The presence of an interaction between sex and digoxin therapy with respect to the primary end point of death from any cause was evaluated with the use of Mantel-Haenszel tests of heterogeneity and a multivariable Cox proportional-hazards model, adjusted for demographic and clinical variables. RESULTS There was an absolute difference of 5.8 percent (95 percent confidence interval, 0.5 to 11.1) between men and women in the effect of digoxin on the rate of death from any cause (P=0.034 for the interaction). Specifically, women who were randomly assigned to digoxin had a higher rate of death than women who were randomly assigned to placebo (33.1 percent vs. 28.9 percent; absolute difference, 4.2 percent, 95 percent confidence interval, -0.5 to 8.8). In contrast, the rate of death was similar among men randomly assigned to digoxin and men randomly assigned to placebo (35.2 percent vs. 36.9 percent; absolute difference, -1.6 percent; 95 percent confidence interval, -4.2 to 1.0). In the multivariable analysis, digoxin was associated with a significantly higher risk of death among women (adjusted hazard ratio for the comparison with placebo, 1.23; 95 percent confidence interval, 1.02 to 1.47), but it had no significant effect among men (adjusted hazard ratio, 0.93; 95 percent confidence interval, 0.85 to 1.02; P=0.014 for the interaction). CONCLUSIONS The effect of digoxin therapy differs between men and women. Digoxin therapy is associated with an increased risk of death from any cause among women, but not men, with heart failure and depressed left ventricular systolic function.

AIMS/HYPOTHESIS We assessed the association between congenital malformations and maternal hyperglycemia in pregnant women with pregestational (type 1 or type 2) diabetes and investigated if the rate of congenital malformations was similar in women with near-normal glycemic control compared to the background population. We also assessed the association between congenital malformations and maternal hyperglycemia in pregnant women with pregestational diabetes with special focus on women with near-normal HbA1c in early pregnancy. MATERIALS AND METHODS This is a literature review based on an electronic literature search of the databases PubMed, Cochrane, Embase and Web of Science conducted in July 2017 using the search terms diabetes, pregnancy, HbA1c or glycemic control and congenital anomaly or congenital anomaly. We included original papers in English published after 1997 with data on congenital malformations and HbA1c in at least 250 women with pregestational diabetes. RESULTS Nine papers with in total 6225 women with type 1 diabetes and 2334 women with type 2 diabetes were included. The prevalence of congenital malformations was 6.4% in women with type 1 diabetes and 4.3% in women with type 2 diabetes and for the combined group of women with pregestational diabetes, the relative risk compared to the background population was 3.2. In women with HbA1c < 53 mmol/mol (7.0%) in early pregnancy or HbA1c 53-64 mmol/mol (7.0-8.0%) the prevalence of congenital malformations was 4.3 and 3.7%, respectively, with a relative risk of 2.2 and 1.9, respectively. CONCLUSIONS In pregnant women with pregestational diabetes the prevalence of congenital abnormalities was threefold higher in women with pregestational diabetes compared to the background population. However, HbA1c below 53 mmol/mol (7.0%) in early pregnancy was also associated with a two times increased risk of congenital malformations compared to the background population.

IMPORTANCE Among nontraditional cardiovascular risk factors, recent influenzalike infection is associated with fatal and nonfatal atherothrombotic events. OBJECTIVES To determine if influenza vaccination is associated with prevention of cardiovascular events. DATA SOURCES AND STUDY SELECTION A systematic review and meta-analysis of MEDLINE (1946-August 2013), EMBASE (1947-August 2013), and the Cochrane Library Central Register of Controlled Trials (inception-August 2013) for randomized clinical trials (RCTs) comparing influenza vaccine vs placebo or control in patients at high risk of cardiovascular disease, reporting cardiovascular outcomes either as efficacy or safety events. DATA EXTRACTION AND SYNTHESIS Two investigators extracted data independently on trial design, baseline characteristics, outcomes, and safety events from published manuscripts and unpublished supplemental data. High-quality studies were considered those that described an appropriate method of randomization, allocation concealment, blinding, and completeness of follow-up. MAIN OUTCOMES AND MEASURES Random-effects Mantel-Haenszel risk ratios (RRs) and 95% CIs were derived for composite cardiovascular events, cardiovascular mortality, all-cause mortality, and individual cardiovascular events. Analyses were stratified by subgroups of patients with and without a history of acute coronary syndrome (ACS) within 1 year of randomization. RESULTS Five published and 1 unpublished randomized clinical trials of 6735 patients (mean age, 67 years; 51.3% women; 36.2% with a cardiac history; mean follow-up time, 7.9 months) were included. Influenza vaccine was associated with a lower risk of composite cardiovascular events (2.9% vs 4.7%; RR, 0.64 [95% CI, 0.48-0.86], P = .003) in published trials. A treatment interaction was detected between patients with (RR, 0.45 [95% CI, 0.32-0.63]) and without (RR, 0.94 [95% CI, 0.55-1.61]) recent ACS (P for interaction = .02). Results were similar with the addition of unpublished data. CONCLUSIONS AND RELEVANCE In a meta-analysis of RCTs, the use of influenza vaccine was associated with a lower risk of major adverse cardiovascular events. The greatest treatment effect was seen among the highest-risk patients with more active coronary disease. A large, adequately powered, multicenter trial is warranted to address these findings and assess individual cardiovascular end points.

BACKGROUND In the assessment of severity in community acquired pneumonia (CAP), the modified British Thoracic Society (mBTS) rule identifies patients with severe pneumonia but not patients who might be suitable for home management. A multicentre study was conducted to derive and validate a practical severity assessment model for stratifying adults hospitalised with CAP into different management groups. METHODS Data from three prospective studies of CAP conducted in the UK, New Zealand, and the Netherlands were combined. A derivation cohort comprising 80% of the data was used to develop the model. Prognostic variables were identified using multiple logistic regression with 30 day mortality as the outcome measure. The final model was tested against the validation cohort. RESULTS 1068 patients were studied (mean age 64 years, 51.5% male, 30 day mortality 9%). Age >/=65 years (OR 3.5, 95% CI 1.6 to 8.0) and albumin <30 g/dl (OR 4.7, 95% CI 2.5 to 8.7) were independently associated with mortality over and above the mBTS rule (OR 5.2, 95% CI 2.7 to 10). A six point score, one point for each of Confusion, Urea >7 mmol/l, Respiratory rate >/=30/min, low systolic(<90 mm Hg) or diastolic (</=60 mm Hg) Blood pressure), age >/=65 years (CURB-65 score) based on information available at initial hospital assessment, enabled patients to be stratified according to increasing risk of mortality: score 0, 0.7%; score 1, 3.2%; score 2, 3%; score 3, 17%; score 4, 41.5% and score 5, 57%. The validation cohort confirmed a similar pattern. CONCLUSIONS A simple six point score based on confusion, urea, respiratory rate, blood pressure, and age can be used to stratify patients with CAP into different management groups.

BACKGROUND Few data have evaluated physician adherence to cardiovascular disease (CVD) prevention guidelines according to physician specialty or patient characteristics, particularly gender. METHODS AND RESULTS An online study of 500 randomly selected physicians (300 primary care physicians, 100 obstetricians/gynecologists, and 100 cardiologists) used a standardized questionnaire to assess awareness of, adoption of, and barriers to national CVD prevention guidelines by specialty. An experimental case study design tested physician accuracy and determinants of CVD risk level assignment and application of guidelines among high-, intermediate-, or low-risk patients. Intermediate-risk women, as assessed by the Framingham risk score, were significantly more likely to be assigned to a lower-risk category by primary care physicians than men with identical risk profiles (P<0.0001), and trends were similar for obstetricians/gynecologists and cardiologists. Assignment of risk level significantly predicted recommendations for lifestyle and preventive pharmacotherapy. After adjustment for risk assignment, the impact of patient gender on preventive care was not significant except for less aspirin (P<0.01) and more weight management recommended (P<0.04) for intermediate-risk women. Physicians did not rate themselves as very effective in their ability to help patients prevent CVD. Fewer than 1 in 5 physicians knew that more women than men die each year from CVD. CONCLUSIONS Perception of risk was the primary factor associated with CVD preventive recommendations. Gender disparities in recommendations for preventive therapy were explained largely by the lower perceived risk despite similar calculated risk for women versus men. Educational interventions for physicians are needed to improve the quality of CVD preventive care and lower morbidity and mortality from CVD for men and women.

BACKGROUND Deep vein thrombosis (DVT) and pulmonary embolism are common after stroke. In small trials of patients undergoing surgery, graduated compression stockings (GCS) reduce the risk of DVT. National stroke guidelines extrapolating from these trials recommend their use in patients with stroke despite insufficient evidence. We assessed the effectiveness of thigh-length GCS to reduce DVT after stroke. METHODS In this outcome-blinded, randomised controlled trial, 2518 patients who were admitted to hospital within 1 week of an acute stroke and who were immobile were enrolled from 64 centres in the UK, Italy, and Australia. Patients were allocated via a central randomisation system to routine care plus thigh-length GCS (n=1256) or to routine care plus avoidance of GCS (n=1262). A technician who was blinded to treatment allocation undertook compression Doppler ultrasound of both legs at about 7-10 days and, when practical, again at 25-30 days after enrolment. The primary outcome was the occurrence of symptomatic or asymptomatic DVT in the popliteal or femoral veins. Analyses were by intention to treat. This study is registered, number ISRCTN28163533. FINDINGS All patients were included in the analyses. The primary outcome occurred in 126 (10.0%) patients allocated to thigh-length GCS and in 133 (10.5%) allocated to avoid GCS, resulting in a non-significant absolute reduction in risk of 0.5% (95% CI -1.9% to 2.9%). Skin breaks, ulcers, blisters, and skin necrosis were significantly more common in patients allocated to GCS than in those allocated to avoid their use (64 [5%] vs 16 [1%]; odds ratio 4.18, 95% CI 2.40-7.27). INTERPRETATION These data do not lend support to the use of thigh-length GCS in patients admitted to hospital with acute stroke. National guidelines for stroke might need to be revised on the basis of these results. FUNDING Medical Research Council (UK), Chief Scientist Office of Scottish Government, Chest Heart and Stroke Scotland, Tyco Healthcare (Covidien) USA, and UK Stroke Research Network.

BACKGROUND Corin is a transmembrane protease that processes natriuretic peptides in the heart. Like many membrane proteins, corin is shed from the cell surface. METHODS AND RESULTS In this study, we obtained plasma samples from healthy controls and patients with heart failure (HF) and acute myocardial infarction. Soluble corin levels in plasma were measured by an ELISA method. In healthy adults (n=198), plasma corin levels were 690 pg/mL (SD, 260 pg/mL). The corin levels did not differ significantly among different age groups. In patients with HF (n=291), plasma corin levels were significantly lower compared with that of healthy controls (365 pg/mL [SD, 259]; P<0.001). The reduction in plasma corin levels seemed to correlate with the severity of HF. In patients of New York Heart Association classes II, III, and IV, plasma corin levels were 450 pg/mL (SD, 281 pg/mL; n=69), 377 pg/mL (SD, 270 pg/mL; n=132), and 282 pg/mL (SD, 194 pg/mL; n=90), respectively (P<0.001 class II vs class IV; P<0.05 class III vs class IV). In contrast, plasma corin levels in patients with acute myocardial infarction (n=73) were similar to that of healthy controls (678 pg/mL [SD, 285 pg/mL]; P>0.05). CONCLUSIONS Soluble corin was detected in human plasma. Plasma corin levels were reduced significantly in patients with HF but not in those with acute myocardial infarction. Our results indicate that corin deficiency may contribute to the pathogenesis of HF and that plasma corin may be used as a biomarker in the diagnosis of HF.

OBJECTIVE To measure whether the benefits of a single education and self management structured programme for people with newly diagnosed type 2 diabetes mellitus are sustained at three years. DESIGN Three year follow-up of a multicentre cluster randomised controlled trial in primary care, with randomisation at practice level. SETTING 207 general practices in 13 primary care sites in the United Kingdom. PARTICIPANTS 731 of the 824 participants included in the original trial were eligible for follow-up. Biomedical data were collected on 604 (82.6%) and questionnaire data on 513 (70.1%) participants. INTERVENTION A structured group education programme for six hours delivered in the community by two trained healthcare professional educators compared with usual care. MAIN OUTCOME MEASURES The primary outcome was glycated haemoglobin (HbA(1c)) levels. The secondary outcomes were blood pressure, weight, blood lipid levels, smoking status, physical activity, quality of life, beliefs about illness, depression, emotional impact of diabetes, and drug use at three years. RESULTS HbA(1c) levels at three years had decreased in both groups. After adjusting for baseline and cluster the difference was not significant (difference -0.02, 95% confidence interval -0.22 to 0.17). The groups did not differ for the other biomedical and lifestyle outcomes and drug use. The significant benefits in the intervention group across four out of five health beliefs seen at 12 months were sustained at three years (P<0.01). Depression scores and quality of life did not differ at three years. CONCLUSION A single programme for people with newly diagnosed type 2 diabetes mellitus showed no difference in biomedical or lifestyle outcomes at three years although there were sustained improvements in some illness beliefs. TRIAL REGISTRATION Current Controlled Trials ISRCTN17844016.

OBJECTIVE To determine if preoperative statin treatment is associated with a reduction in systemic inflammatory response (SIR) and myocardial damage markers following cardiac surgery with cardiopulmonary bypass (CPB). METHODS We study a prospective cohort of 138 patients who underwent coronary and valvular surgery with CPB. We differentiate two study groups: patients with (group A, n=72) or without (group B, n=66) statins. Plasma levels of pro-inflammatory interleukins (tumour necrosis factor-alpha (TNF-alpha), interleukin (IL)-6, IL-8 and IL-2R), creatine phosphokinase (CPK), CPK-MB and troponin I were measured before and 1, 6, 24 and >72 h after surgery. RESULTS The baseline, operative and postoperative morbidity and mortality characteristics were similar for both the groups. Group A had significantly lower postoperative levels of IL-6 than group B at 6h (68.8+/-5 pg ml(-1) vs 108.9+/-108 pg ml(-1), p=0.01), 24h (71.7+/-7 pg ml(-1) vs 110.4+/-106 pg ml(-1), p=0.01) and before hospital discharge (21.6+/-12 pg ml(-1) vs 32.8+/-27 pg ml(-1), p=0.005), as well as significantly lower average IL-6 levels in the first 24h following surgery (71.8+/-5 pgml(-1) vs 112.8+/-82 pg ml(-1), p=0.002). The postoperative CPK-MB at 24h (19.7+/-23 ng ml(-1) vs 33.1+/-32 ng ml(-1), p=0.02) and troponin I levels at the end of the intervention (2.2+/-2.2 ng ml(-1) vs 3.3+/-3.1 ng ml(-1), p=0.03) and at 24h (4.1+/-3.5 ng ml(-1) vs 6.6+/-8 ng ml(-1), p=0.04) were also significantly lower in the group treated with statins prior to surgery. CONCLUSIONS Preoperative treatment with statins is associated with a lower biochemical parameters of SIR and myocardial damage following cardiac surgery with CPB, regardless of it being coronary bypass grafting (CABG) or valvular surgery.


Question: Differentiation between the initiator and elongation tRNAs is reliant on the translation initiation factor IF3.

Dynamic Roles of IF3 and tRNA in Bacterial Translation Initiation

In the intricate process of bacterial translation initiation, the three initiation factors (IFs 1-3) play pivotal roles in the precise selection of the initiator tRNA and the correct start codon within the P site of the 30S ribosomal subunit. This study presents a series of 11 high-resolution cryo-electron microscopy (cryoEM) images, capturing the complex formed by the bacterial 30S subunit in conjunction with the initiator tRNA, mRNA, and the IFs 1-3, at various stages along the initiation pathway. The findings reveal that IF1 acts as a critical anchor for both IF2 and IF3, significantly enhancing their respective functions. IF2, in turn, maintains a domain in an elongated conformation, which is essential for the binding of the formylmethionyl moiety to tRNA. Throughout the process, IF3 and tRNA undergo significant conformational shifts to facilitate the proper positioning of formylmethionyl-tRNA (fMet-tRNA(fMet)) within the P site for accurate start codon recognition, underscoring the importance of dynamic interactions in the initiation of translation.

A yeast strain lacking Met4p, the primary transcriptional regulator of the sulfur assimilation pathway, cannot synthesize methionine. This apparently simple auxotroph did not grow well in rich media containing excess methionine, forming small colonies on yeast extract/peptone/dextrose plates. Faster-growing large colonies were abundant when overnight cultures were plated, suggesting that spontaneous suppressors of the growth defect arise with high frequency. To identify the suppressor mutations, we used genome-wide single-nucleotide polymorphism and standard genetic analyses. The most common suppressors were loss-of-function mutations in OPI1, encoding a transcriptional repressor of phospholipid metabolism. Using a new system that allows rapid and specific degradation of Met4p, we could study the dynamic expression of all genes following loss of Met4p. Experiments using this system with and without Opi1p showed that Met4 activates and Opi1p represses genes that maintain levels of S-adenosylmethionine (SAM), the substrate for most methyltransferase reactions. Cells lacking Met4p grow normally when either SAM is added to the media or one of the SAM synthetase genes is overexpressed. SAM is used as a methyl donor in three Opi1p-regulated reactions to create the abundant membrane phospholipid, phosphatidylcholine. Our results show that rapidly growing cells require significant methylation, likely for the biosynthesis of phospholipids.

Many forms of long-lasting behavioral and synaptic plasticity require the synthesis of new proteins. For example, long-term potentiation (LTP) that endures for more than an hour requires both transcription and translation. The signal-transduction mechanisms that couple synaptic events to protein translational machinery during long-lasting synaptic plasticity, however, are not well understood. One signaling pathway that is stimulated by growth factors and results in the translation of specific mRNAs includes the rapamycin-sensitive kinase mammalian target of rapamycin (mTOR, also known as FRAP and RAFT-1). Several components of this translational signaling pathway, including mTOR, eukaryotic initiation factor-4E-binding proteins 1 and 2, and eukaryotic initiation factor-4E, are present in the rat hippocampus as shown by Western blot analysis, and these proteins are detected in the cell bodies and dendrites in the hippocampal slices by immunostaining studies. In cultured hippocampal neurons, these proteins are present in dendrites and are often found near the presynaptic protein, synapsin I. At synaptic sites, their distribution completely overlaps with a postsynaptic protein, PSD-95. These observations suggest the postsynaptic localization of these proteins. Disruption of mTOR signaling by rapamycin results in a reduction of late-phase LTP expression induced by high-frequency stimulation; the early phase of LTP is unaffected. Rapamycin also blocks the synaptic potentiation induced by brain-derived neurotrophic factor in hippocampal slices. These results demonstrate an essential role for rapamycin-sensitive signaling in the expression of two forms of synaptic plasticity that require new protein synthesis. The localization of this translational signaling pathway at postsynaptic sites may provide a mechanism that controls local protein synthesis at potentiated synapses.

We have used NMR spectroscopy to determine the solution structure of protein AAH26994.1 from Mus musculus and propose that it represents the first three-dimensional structure of a ubiquitin-related modifier 1 (Urm1) protein. Amino acid sequence comparisons indicate that AAH26994.1 belongs to the Urm1 family of ubiquitin-like modifier proteins. The best characterized member of this family has been shown to be involved in nutrient sensing, invasive growth, and budding in yeast. Proteins in this family have only a weak sequence similarity to ubiquitin, and the structure of AAH26994.1 showed a much closer resemblance to MoaD subunits of molybdopterin synthases (known structures are of three bacterial MoaD proteins with 14%-26% sequence identity to AAH26994.1). The structures of AAH26994.1 and the MoaD proteins each contain the signature ubiquitin secondary structure fold, but all differ from ubiquitin largely in regions outside of this fold. This structural similarity bolsters the hypothesis that ubiquitin and ubiquitin-related proteins evolved from a protein-based sulfide donor system of the molybdopterin synthase type.

Recent studies indicate that many introns, as well as the complex spliceosomal mechanism to remove them, were present early in eukaryotic evolution. This study examines intron and exon characteristics from annotations of whole genomes to investigate the intron recognition mechanism. Exon definition uses the exon as the unit of recognition, placing length constraints on the exon but not on the intron (allowing it a greater range of lengths). In contrast, intron definition uses the intron itself as the unit of recognition and thus removes constraints on internal exon length forced by the use of an exon definition mechanism. Thus, intron and exon lengths within a genome can reflect the constraints imposed by its splicing. This study shows that it is possible firstly to recover valid intron and exon information from genome annotation. We then compare internal intron and exon information from a range of eukaryotic genomes and investigate possible evolutionary length constraints on introns and exons and how they can impact on the intron recognition mechanism. Results indicate that exon definition-based mechanisms may predominate in vertebrates although the exact system in fish is expected to show some differences with the better characterized system from mammals. We also raise the possibility that the last common ancestor of plants and animals contained some type of exon definition and that this mechanism was replaced in some genes and lineages by intron definition, possibly as a result of intron loss and/or intron shortening.

Emerging data suggest that microRNAs (miRNAs) are instrumental in a variety of stress responses in addition to their more recognized role in development. Surprisingly, miRNAs, which normally suppress expression of target transcripts, may become activators of expression during stress. This might be partially explained by new interactions of miRNA/Argonaute complexes with RNA-binding proteins that relocate from different subcellular compartments during stress.

The 5'-exonuclease Rat1 degrades pre-rRNA spacer fragments and processes the 5'-ends of the 5.8S and 25S rRNAs. UV crosslinking revealed multiple Rat1-binding sites across the pre-rRNA, consistent with its known functions. The major 5.8S 5'-end is generated by Rat1 digestion of the internal transcribed spacer 1 (ITS1) spacer from cleavage site A(3). Processing from A(3) requires the 'A(3)-cluster' proteins, including Cic1, Erb1, Nop7, Nop12 and Nop15, which show interdependent pre-rRNA binding. Surprisingly, A(3)-cluster factors were not crosslinked close to site A(3), but bound sites around the 5.8S 3'- and 25S 5'-regions, which are base paired in mature ribosomes, and in the ITS2 spacer that separates these rRNAs. In contrast, Nop4, a protein required for endonucleolytic cleavage in ITS1, binds the pre-rRNA near the 5'-end of 5.8S. ITS2 was reported to undergo structural remodelling. In vivo chemical probing indicates that A(3)-cluster binding is required for this reorganization, potentially regulating the timing of processing. We predict that Nop4 and the A(3) cluster establish long-range interactions between the 5.8S and 25S rRNAs, which are subsequently maintained by ribosomal protein binding.

Drug resistance-associated mutations in HIV-1 reverse transcriptase (RT) can affect the balance between polymerase and ribonuclease H (RNase H) activities of the enzyme. We have recently demonstrated that the N348I mutation in the connection domain causes selective dissociation from RNase H-competent complexes, whereas the functional integrity of the polymerase-competent complex remains largely unaffected. N348I has been associated with resistance to the non-nucleoside RT inhibitor (NNRTI), nevirapine; however, a possible mechanism that links changes in RNase H activity to changes in NNRTI susceptibility remains to be established. To address this problem, we consider recent findings suggesting that NNRTIs may affect the orientation of RT on its nucleic acid substrate and increase RNase H activity. Here we demonstrate that RNase H-mediated primer removal is indeed more efficient in the presence of NNRTIs; however, the N348I mutant enzyme is able to counteract this effect. Efavirenz, a tight binding inhibitor, restricts the influence of the mutation. These findings provide strong evidence to suggest that N348I can thwart the inhibitory effects of nevirapine during initiation of (+)-strand DNA synthesis, which provides a novel mechanism for resistance. The data are in agreement with clinical data, which demonstrate a stronger effect of N348I on susceptibility to nevirapine as compared with efavirenz.

We describe methods for obtaining a quantitative description of RNA processing at high resolution in budding yeast. As a model gene expression system, we constructed tetON (for induction studies) and tetOFF (for repression, derepression, and RNA degradation studies) yeast strains with a series of reporter genes integrated in the genome under the control of a tetO7 promoter. Reverse transcription and quantitative real-time-PCR (RT-qPCR) methods were adapted to allow the determination of mRNA abundance as the average number of copies per cell in a population. Fluorescence in situ hybridization (FISH) measurements of transcript numbers in individual cells validated the RT-qPCR approach for the average copy-number determination despite the broad distribution of transcript levels within a population of cells. In addition, RT-qPCR was used to distinguish the products of the different steps in splicing of the reporter transcripts, and methods were developed to map and quantify 3'-end cleavage and polyadenylation. This system permits pre-mRNA production, splicing, 3'-end maturation and degradation to be quantitatively monitored with unprecedented kinetic detail, suitable for mathematical modeling. Using this approach, we demonstrate that reporter transcripts are spliced prior to their 3'-end cleavage and polyadenylation, that is, cotranscriptionally.

Trypanosoma brucei causes human African trypanosomiasis and regularly switches its major surface antigen, VSG, in the bloodstream of its mammalian host to evade the host immune response. VSGs are expressed exclusively from subtelomeric loci, and we have previously shown that telomere proteins TbTIF2 and TbRAP1 play important roles in VSG switching and VSG silencing regulation, respectively. We now discover that the telomere duplex DNA-binding factor, TbTRF, also plays a critical role in VSG switching regulation, as a transient depletion of TbTRF leads to significantly more VSG switching events. We solved the NMR structure of the DNA-binding Myb domain of TbTRF, which folds into a canonical helix-loop-helix structure that is conserved to the Myb domains of mammalian TRF proteins. The TbTRF Myb domain tolerates well the bulky J base in T. brucei telomere DNA, and the DNA-binding affinity of TbTRF is not affected by the presence of J both in vitro and in vivo. In addition, we find that point mutations in TbTRF Myb that significantly reduced its in vivo telomere DNA-binding affinity also led to significantly increased VSG switching frequencies, indicating that the telomere DNA-binding activity is critical for TbTRF's role in VSG switching regulation.

Very often, the positions of flexible domains within macromolecules as well as within macromolecular complexes cannot be determined by standard structural biology methods. To overcome this problem, we developed a method that uses probabilistic data analysis to combine single-molecule measurements with X-ray crystallography data. The method determines not only the most likely position of a fluorescent dye molecule attached to the domain but also the complete three-dimensional probability distribution depicting the experimental uncertainty. With this approach, single-pair fluorescence resonance energy transfer measurements can now be used as a quantitative tool for investigating the position and dynamics of flexible domains within macromolecular complexes. We applied this method to find the position of the 5′ end of the nascent RNA exiting transcription elongation complexes of yeast (Saccharomyces cerevisiae) RNA polymerase II and studied the influence of transcription factor IIB on the position of the RNA.


Question: Downregulation and mislocalization of Scribble inhibits cell transformation and the development of mammary tumors.

Altered Expression and Localization of Scribble Contribute to Mammary Carcinogenesis and Uncover the Significance of Cell Polarity in Tumor Development.
The deregulation of cell polarity proteins, including Scribble, has been implicated in the promotion of neoplastic growth in Drosophila by stimulating uncontrolled cell proliferation. However, the specific function of polarity proteins during mammalian tumorigenesis remains less explored. Our findings reveal that the depletion of Scribble in mammary epithelial cells leads to a disruption of cellular polarity, impairs three-dimensional morphogenesis, suppresses apoptosis, and triggers dysplasia in vivo, which can eventually evolve into tumors over an extended period. Interestingly, Scribble loss synergizes with oncogenes like c-myc to induce epithelial cell transformation and tumor formation in vivo by suppressing the activation of an apoptotic pathway. Similar to depletion, the mislocalization of Scribble from cell-cell junctions was also sufficient to drive cell transformation. Notably, both downregulation and mislocalization of Scribble are observed in spontaneous mammary tumors in both mice and humans. These results underscore the tumor-suppressive role of Scribble in breast tissue and highlight the significance of polarity pathway deregulation in promoting dysplasia and neoplasia in mammals by disrupting tissue architecture and inhibiting programmed cell death.

Weeble mutant mice have severe locomotor instability and significant neuronal loss in the cerebellum and in the hippocampal CA1 field. Genetic mapping was used to localize the mutation to the gene encoding inositol polyphosphate 4-phosphatase type I (Inpp4a), where a single nucleotide deletion results in a likely null allele. The substrates of INPP4A are intermediates in a pathway affecting intracellular Ca(2+) release but are also involved in cell cycle regulation through binding the Akt protooncogene; dysfunction in either may account for the neuronal loss of weeble mice. Although other mutations in phosphoinositide enzymes are associated with synaptic defects without neuronal loss, weeble shows that Inpp4a is critical for the survival of a subset of neurons during postnatal development in mice.

The canonical Wnt signaling pathway is of paramount importance in development and disease. An emergent question is whether the upstream cascade of the canonical Wnt pathway has physiologically relevant roles beyond β-catenin-mediated transcription, which is difficult to study due to the pervasive role of this protein. Here, we show that transcriptionally silent spermatozoa respond to Wnt signals released from the epididymis and that mice mutant for the Wnt regulator Cyclin Y-like 1 are male sterile due to immotile and malformed spermatozoa. Post-transcriptional Wnt signaling impacts spermatozoa through GSK3 by (1) reducing global protein poly-ubiquitination to maintain protein homeostasis; (2) inhibiting septin 4 phosphorylation to establish a membrane diffusion barrier in the sperm tail; and (3) inhibiting protein phosphatase 1 to initiate sperm motility. The results indicate that Wnt signaling orchestrates a rich post-transcriptional sperm maturation program and invite revisiting transcription-independent Wnt signaling in somatic cells as well.

The ubiquitin-binding protein Hrs and endosomal sorting complex required for transport (ESCRT)-I and ESCRT-III are involved in sorting endocytosed and ubiquitinated receptors to lysosomes for degradation and efficient termination of signaling. In this study, we have investigated the role of the ESCRT-II subunit Vps22/EAP30 in degradative protein sorting of ubiquitinated receptors. Vps22 transiently expressed in HeLa cells was detected in endosomes containing endocytosed epidermal growth factor receptors (EGFRs) as well as Hrs and ESCRT-I and ESCRT-III. Depletion of Vps22 by small interfering RNA, which was accompanied by decreased levels of other ESCRT-II subunits, greatly reduced degradation of EGFR and its ligand EGF as well as the chemokine receptor CXCR4. EGFR accumulated on the limiting membranes of early endosomes and aberrantly small multivesicular bodies in Vps22-depleted cells. Phosphorylation and nuclear translocation of extracellular-signal-regulated kinase1/2 downstream of the EGF-activated receptor were sustained by depletion of Hrs or the ESCRT-I subunit Tsg101. In contrast, this was not the case when Vps22 was depleted. These results indicate an important role for Vps22 in ligand-induced EGFR and CXCR4 turnover and suggest that termination of EGF signaling occurs prior to ESCRT-II engagement.

WAVE2 belongs to a family of proteins that mediates actin reorganization by relaying signals from Rac to the Arp2/3 complex, resulting in lamellipodia protrusion. WAVE2 displays Arp2/3-dependent actin nucleation activity in vitro, and does not bind directly to Rac. Instead, it forms macromolecular complexes that have been reported to exert both positive and negative modes of regulation. How these complexes are assembled, localized and activated in vivo remains to be established. Here we use tandem mass spectrometry to identify an Abi1-based complex containing WAVE2, Nap1 (Nck-associated protein) and PIR121. Abi1 interacts directly with the WHD domain of WAVE2, increases WAVE2 actin polymerization activity and mediates the assembly of a WAVE2–Abi1–Nap1–PIR121 complex. The WAVE2–Abi1–Nap1–PIR121 complex is as active as the WAVE2–Abi1 sub-complex in stimulating Arp2/3, and after Rac activation it is re-localized to the leading edge of ruffles in vivo. Consistently, inhibition of Abi1 by RNA interference (RNAi) abrogates Rac-dependent lamellipodia protrusion. Thus, Abi1 orchestrates the proper assembly of the WAVE2 complex and mediates its activation at the leading edge in vivo.

The midbody is a singular organelle formed between daughter cells during cytokinesis and required for their final separation. Midbodies persist in cells long after division as midbody derivatives (MBds), but their fate is unclear. Here we show that MBds are inherited asymmetrically by the daughter cell with the older centrosome. They selectively accumulate in stem cells, induced pluripotent stem cells and potential cancer ‘stem cells’ in vivo and in vitro. MBd loss accompanies stem-cell differentiation, and involves autophagic degradation mediated by binding of the autophagic receptor NBR1 to the midbody protein CEP55. Differentiating cells and normal dividing cells do not accumulate MBds and possess high autophagic activity. Stem cells and cancer cells accumulate MBds by evading autophagosome encapsulation and exhibit low autophagic activity. MBd enrichment enhances reprogramming to induced pluripotent stem cells and increases the in vitro tumorigenicity of cancer cells. These results indicate unexpected roles for MBds in stem cells and cancer ‘stem cells’.

Tumor metastasis is the primary cause of death of cancer patients. Understanding the molecular mechanisms underlying tumor metastasis will provide potential drug targets. We report here that Orai1 and STIM1, both of which are involved in store-operated calcium entry, are essential for breast tumor cell migration in vitro and tumor metastasis in mice. Reduction of Orai1 or STIM1 by RNA interference in highly metastatic human breast cancer cells or treatment with a pharmacological inhibitor of store-operated calcium channels decreased tumor metastasis in animal models. Our data demonstrate a role for Orai1 and STIM1 in tumor metastasis and suggest store-operated calcium entry channels as potential cancer therapeutic targets.

Vascular disease progression is associated with marked changes in vascular smooth muscle cell (SMC) phenotype and function. SMC contractile gene expression and, thus differentiation, is under direct transcriptional control by the transcription factor, serum response factor (SRF); however, the mechanisms dynamically regulating SMC phenotype are not fully defined. Here we report that the lipid and protein phosphatase, PTEN, has a novel role in the nucleus by functioning as an indispensible regulator with SRF to maintain the differentiated SM phenotype. PTEN interacts with the N-terminal domain of SRF and PTEN-SRF interaction promotes SRF binding to essential promoter elements in SM-specific genes. Factors inducing phenotypic switching promote loss of nuclear PTEN through nucleo-cytoplasmic translocation resulting in reduced myogenically active SRF, but enhanced SRF activity on target genes involved in proliferation. Overall decreased expression of PTEN was observed in intimal SMCs of human atherosclerotic lesions underlying the potential clinical importance of these findings.

How instructive cues present on the cell surface have their precise effects on the actin cytoskeleton is poorly understood. Semaphorins are one of the largest families of these instructive cues and are widely studied for their effects on cell movement, navigation, angiogenesis, immunology and cancer. Semaphorins/collapsins were characterized in part on the basis of their ability to drastically alter actin cytoskeletal dynamics in neuronal processes, but despite considerable progress in the identification of semaphorin receptors and their signalling pathways, the molecules linking them to the precise control of cytoskeletal elements remain unknown. Recently, highly unusual proteins of the Mical family of enzymes have been found to associate with the cytoplasmic portion of plexins, which are large cell-surface semaphorin receptors, and to mediate axon guidance, synaptogenesis, dendritic pruning and other cell morphological changes. Mical enzymes perform reduction–oxidation (redox) enzymatic reactions and also contain domains found in proteins that regulate cell morphology. However, nothing is known of the role of Mical or its redox activity in mediating morphological changes. Here we report that Mical directly links semaphorins and their plexin receptors to the precise control of actin filament (F-actin) dynamics. We found that Mical is both necessary and sufficient for semaphorin–plexin-mediated F-actin reorganization in vivo. Likewise, we purified Mical protein and found that it directly binds F-actin and disassembles both individual and bundled actin filaments. We also found that Mical utilizes its redox activity to alter F-actin dynamics in vivo and in vitro, indicating a previously unknown role for specific redox signalling events in actin cytoskeletal regulation. Mical therefore is a novel F-actin-disassembly factor that provides a molecular conduit through which actin reorganization—a hallmark of cell morphological changes including axon navigation—can be precisely achieved spatiotemporally in response to semaphorins.

L3mbtl2 has been implicated in transcriptional repression and chromatin compaction but its biological function has not been defined. Here we show that disruption of L3mbtl2 results in embryonic lethality with failure of gastrulation. This correlates with compromised proliferation and abnormal differentiation of L3mbtl2(-/-) embryonic stem (ES) cells. L3mbtl2 regulates genes by recruiting a Polycomb Repressive Complex1 (PRC1)-related complex, resembling the previously described E2F6-complex, and including G9A, Hdac1, and Ring1b. The presence of L3mbtl2 at target genes is associated with H3K9 dimethylation, low histone acetylation, and H2AK119 ubiquitination, but the latter is neither dependent on L3mbtl2 nor sufficient for repression. Genome-wide studies revealed that the L3mbtl2-dependent complex predominantly regulates genes not bound by canonical PRC1 and PRC2. However, some developmental regulators are repressed by the combined activity of all three complexes. Together, we have uncovered a highly selective, essential role for an atypical PRC1-family complex in ES cells and early development.

BACKGROUND & AIMS Hepatic stellate cell activation is a wound-healing response to liver injury. However, continued activation of stellate cells during chronic liver damage causes excessive matrix deposition and the formation of pathological scar tissue leading to fibrosis and ultimately cirrhosis. The importance of sustained stellate cell activation for this pathological process is well recognized, and several signalling pathways that can promote stellate cell activation have been identified, such as the TGFβ-, PDGF-, and LPS-dependent pathways. However, the mechanisms that trigger and drive the early steps in activation are not well understood. METHODS AND RESULTS We identified the Hippo pathway and its effector YAP as a key pathway that controls stellate cell activation. YAP is a transcriptional co-activator and we found that it drives the earliest changes in gene expression during stellate cell activation. Activation of stellate cells in vivo by CCl4 administration to mice or activation in vitro caused rapid activation of YAP as revealed by its nuclear translocation and by the induction of YAP target genes. YAP was also activated in stellate cells of human fibrotic livers as evidenced by its nuclear localization. Importantly, knockdown of YAP expression or pharmacological inhibition of YAP prevented hepatic stellate cell activation in vitro and pharmacological inhibition of YAP impeded fibrogenesis in mice. CONCLUSIONS YAP activation is a critical driver of hepatic stellate cell activation and inhibition of YAP presents a novel approach for the treatment of liver fibrosis.


Question: In the initial early antibody reaction, activated B cells move towards the inner-and outer paracortical regions where oxysterol buildup is produced by stromal cells.

Navigating the Lymphoid Landscape: B-cell Migration Patterns in the Initiation of T-dependent Antibody Reactions. Effective humoral immunity relies on B cells' ability to encounter antigens, engage with helper T cells, undergo proliferation, and differentiate into plasma cells capable of producing low- or high-affinity antibodies, depending on whether they form germinal centers (GCs). Intriguingly, each phase of this complex process is spatially organized within specific subregions of lymphoid tissue, associated with distinct stromal cell types. B cells must traverse these microenvironments with precision and speed to mount a successful immune response. The chemokine CXCL13 is pivotal in directing B cells to follicles, while T-zone chemokines steer activated B cells to the T-cell zones. Sphingosine-1-phosphate (S1P) not only facilitates cell exit from the tissue but also influences the positioning of marginal-zone B cells in the spleen. Emerging research has shed light on the orphan receptor EBV-induced molecule 2 (EBI2; GPR183), which guides activated B cells to inter and outer follicular areas, and the downregulation of this receptor is critical for the assembly of GCs. In this article, we delve into the latest insights on the roles of chemokines, S1P, and EBI2 in orchestrating the migratory dynamics that are foundational to humoral immune reactions.

BACKGROUND Saphenous vein graft (VG) failure occurs more frequently compared with arterial grafts, and graft thrombosis represents the main cause of early occlusion. Because CD40-CD40L pathway CD40 represents a culprit link between local inflammation and coagulation cascade, we investigate the role of CD40 and its soluble ligand (sCD40L) in the immediate in vitro response of VG to arterial pressures, and the potential effects of Simvastatin (Merck Sharp&Dohme, White-house Station, NJ) supplementation. METHODS Samples of saphenous vein and of internal mammary artery (IMA) were obtained from sixteen patients without history of statin therapy. Segments underwent pulsatile pressure distension and culture with or without supplementation of Simvastatin. CD40 and sCD40L were assessed in tissue lysate and in culture supernatant, respectively. sCD40L serum concentrations were also measured. RESULTS During the course of the experiment, the CD40 expression was significantly lower in IMA samples compared with both distended and not distended VG. Pressure distension up-regulated the production of CD40 in VG segments after 24 and 48 h. Statin supplementation significantly reduced the expression of CD40 in both venous (P < 0.001) and arterial samples (P < 0.001). This effect of Simvastatin was not affected by the treatment with L-NAME, but it was reversed by the addition of mevalonic acid. Mean sCD40L content in culture supernatants increased over time, suggesting that not only platelets but also the vessel wall is a source of CD40 and sCD40L. CONCLUSIONS Simvastatin treatment modulates endothelial CD40-sCD40L in both venous and arterial grafts, and therefore may represent a useful tool in the pharmacological prevention of graft failure.

3BNC117 is a broad and potent neutralizing antibody to HIV-1 that targets the CD4 binding site on the viral envelope spike. When administered passively, this antibody can prevent infection in animal models and suppress viremia in HIV-1–infected individuals. Here we report that HIV-1 immunotherapy with a single injection of 3BNC117 affects host antibody responses in viremic individuals. In comparison to untreated controls that showed little change in their neutralizing activity over a 6-month period, 3BNC117 infusion significantly improved neutralizing responses to heterologous tier 2 viruses in nearly all study participants. We conclude that 3BNC117-mediated immunotherapy enhances host humoral immunity to HIV-1.

Sterol transport between the endoplasmic reticulum (ER) and plasma membrane (PM) occurs by nonvesicular mechanisms requiring sterol transport proteins (STPs). Here we examine the idea that transport is enhanced at membrane contact sites where the ER is closely apposed to the PM. We conclude that sterol desorption from the membrane, rather than STP-mediated diffusion, is rate limiting in the cellular context, so there is no apparent kinetic benefit to having STP-mediated sterol transfer occur at contact sites. Contact sites may instead compartmentalize lipid synthesis or transport machinery, providing opportunities for regulation.

Aire-expressing medullary thymic epithelial cells (mTECs) play a key role in preventing autoimmunity by expressing tissue-restricted antigens to help purge the emerging T cell receptor repertoire of self-reactive specificities. Here we demonstrate a novel role for a CD4+3− inducer cell population, previously linked to development of organized secondary lymphoid structures and maintenance of T cell memory in the functional regulation of Aire-mediated promiscuous gene expression in the thymus. CD4+3− cells are closely associated with mTECs in adult thymus, and in fetal thymus their appearance is temporally linked with the appearance of Aire+ mTECs. We show that RANKL signals from this cell promote the maturation of RANK-expressing CD80−Aire− mTEC progenitors into CD80+Aire+ mTECs, and that transplantation of RANK-deficient thymic stroma into immunodeficient hosts induces autoimmunity. Collectively, our data reveal cellular and molecular mechanisms leading to the generation of Aire+ mTECs and highlight a previously unrecognized role for CD4+3−RANKL+ inducer cells in intrathymic self-tolerance.

BACKGROUND Steroidogenic acute regulatory (StAR) protein related lipid transfer (START) domains are small globular modules that form a cavity where lipids and lipid hormones bind. These domains can transport ligands to facilitate lipid exchange between biological membranes, and they have been postulated to modulate the activity of other domains of the protein in response to ligand binding. More than a dozen human genes encode START domains, and several of them are implicated in a disease. PRINCIPAL FINDINGS We report crystal structures of the human STARD1, STARD5, STARD13 and STARD14 lipid transfer domains. These represent four of the six functional classes of START domains. SIGNIFICANCE Sequence alignments based on these and previously reported crystal structures define the structural determinants of human START domains, both those related to structural framework and those involved in ligand specificity. ENHANCED VERSION This article can also be viewed as an enhanced version in which the text of the article is integrated with interactive 3D representations and animated transitions. Please note that a web plugin is required to access this enhanced functionality. Instructions for the installation and use of the web plugin are available in Text S1.

Chemokine-like receptor 1 (CMKLR1), also known as ChemR23, and chemokine (C-C motif) receptor-like 2 (CCRL2) are 7-transmembrane receptors that were cloned in the late 1990s based on their homology to known G-protein-coupled receptors. They were previously orphan receptors without any known biological roles; however, recent studies identified ligands for these receptors and their functions have begun to be unveiled. The plasma protein-derived chemoattractant chemerin is a ligand for CMKLR1 and activation of CMKLR1 with chemerin induces the migration of macrophages and dendritic cells (DCs) in vitro, suggesting a proinflammatory role. However, in vivo studies using CMKLR-deficient mice suggest an anti-inflammatory role for this receptor, possibly due to the recruitment of tolerogenic plasmacytoid DCs. Chemerin/CMKLR1 interaction also promotes adipogenesis and angiogenesis. The anti-inflammatory lipid mediator, resolving E1, is another CMKLR1 ligand and it inhibits leukocyte infiltration and proinflammatory gene expression. These divergent results suggest that CMKLR1 is a multifunctional receptor. The chemokine CCL5 and CCL19 are reported to bind to CCRL2. Like Duffy antigen for chemokine receptor (DARC), D6 and CCX-CKR, CCRL2 does not signal, but it constitutively recycles, potentially reducing local concentration of CCL5 and CCL19 and subsequent immune responses. Surprisingly, chemerin, a ligand for CMKLR1, is a ligand for CCRL2. CCRL2 binds chemerin and increases local chemerin concentration to efficiently present it to CMKLR1 on nearby cells, providing a link between CCRL2 and CMKLR1. Although these findings suggest an anti-inflammatory role, a recent study using CCRL2-deficient mice indicates a proinflammatory role; thus, CCRL2 may also be multifunctional. Further studies using CMKLR1- or CCRL2-deficient mice are needed to further define the role of these receptors in immune responses and other cellular processes.

The complex repertoire of immune receptors generated by B and T cells enables recognition of diverse threats to the host organism. In this work, we show that massively parallel DNA sequencing of rearranged immune receptor loci can provide direct detection and tracking of immune diversity and expanded clonal lymphocyte populations in physiological and pathological contexts. DNA was isolated from blood and tissue samples, a series of redundant primers was used to amplify diverse DNA rearrangements, and the resulting mixtures of barcoded amplicons were sequenced using long-read ultra deep sequencing. Individual DNA molecules were then characterized on the basis of DNA segments that had been joined to make a functional (or nonfunctional) immune effector. Current experimental designs can accommodate up to 150 samples in a single sequence run, with the depth of sequencing sufficient to identify stable and dynamic aspects of the immune repertoire in both normal and diseased circumstances. These data provide a high-resolution picture of immune spectra in normal individuals and in patients with hematological malignancies, illuminating, in the latter case, both the initial behavior of clonal tumor populations and the later suppression or re-emergence of such populations after treatment.

RATIONALE Hemizygous deficiency of the transcription factor Krüppel-like factor 2 (KLF2) has been shown previously to augment atherosclerosis in hypercholesterolemic mice. However, the cell type responsible for the increased atherosclerosis due to KLF2 deficiency has not been identified. This study examined the consequence of myeloid cell-specific KLF2 inactivation in atherosclerosis. METHODS AND RESULTS Cell-specific knockout mice were generated by Cre/loxP recombination. Macrophages isolated from myeloid-specific Klf2 knockout (myeKlf2(-/-)) mice were similar to myeKlf2(+/+) macrophages in response to activation, polarization, and lipid accumulation. However, in comparison to myeKlf2(+/+) macrophages, myeKlf2(-/-) macrophages adhered more robustly to endothelial cells. Neutrophils from myeKlf2(-/-) mice also adhered more robustly to endothelial cells, and fewer myeKlf2(-/-) neutrophils survived in culture over a 24-hour period in comparison with myeKlf2(+/+) neutrophils. When myeKlf2(-/-) mice were mated to Ldlr(-/-) mice and then fed a high fat and high cholesterol diet, significant increase in atherosclerosis was observed in the myeKlf2(-/-)Ldlr(-/-) mice compared with myeKlf2(+/+)Ldlr(-/-) littermates. The increased atherosclerosis in myeKlf2(-/-)Ldlr(-/-) mice was associated with elevated presence of neutrophils and macrophages, with corresponding increase of myeloperoxidase as well as chlorinated and nitrosylated tyrosine epitopes in their lesion areas compared with myeKlf2(+/+)Ldlr(-/-) mice. CONCLUSIONS This study documents a role for myeloid KLF2 expression in modulating atherosclerosis. The increased neutrophil accumulation and atherosclerosis progression with myeloid-specific KLF2 deficiency also underscores the importance of neutrophils in promoting vascular oxidative stress and atherosclerosis. Collectively, these results suggest that elevating KLF2 expression may be a novel strategy for prevention and treatment of atherosclerosis.

Recognition of antigen by T cells requires the formation of a specialized junction between the T cell and the antigen-presenting cell. This junction is generated by the recruitment and the exclusion of specific proteins from the contact area. The mechanisms that regulate these events are unknown. Here we demonstrate that ligand engagement of the adhesion molecule, CD2, initiates a process of protein segregation, CD2 clustering, and cytoskeletal polarization. Although protein segregation was not dependent on the cytoplasmic domain of CD2, CD2 clustering and cytoskeletal polarization required an interaction of the CD2 cytoplasmic domain with a novel SH3-containing protein. This novel protein, called CD2AP, is likely to facilitate receptor patterning in the contact area by linking specific adhesion receptors to the cytoskeleton.

The HIV-1 protein Nef enhances viral pathogenicity and accelerates disease progression in vivo. Nef potentiates T cell activation by an unknown mechanism, probably by optimizing the intracellular environment for HIV replication. Using a new T cell reporter system, we have found that Nef more than doubles the number of cells expressing the transcription factors NF-kappaB and NFAT after TCR stimulation. This Nef-induced priming of TCR signaling pathways occurred independently of calcium signaling and involved a very proximal step before protein kinase C activation. Engagement of the TCR by MHC-bound Ag triggers the formation of the immunological synapse by recruiting detergent-resistant membrane microdomains, termed lipid rafts. Approximately 5-10% of the total cellular pool of Nef is localized within lipid rafts. Using confocal and real-time microscopy, we found that Nef in lipid rafts was recruited into the immunological synapse within minutes after Ab engagement of the TCR/CD3 and CD28 receptors. This recruitment was dependent on the N-terminal domain of Nef encompassing its myristoylation. Nef did not increase the number of cell surface lipid rafts or immunological synapses. Recently, studies have shown a specific interaction of Nef with an active subpopulation of p21-activated kinase-2 found only in the lipid rafts. Thus, the corecruitment of Nef and key cellular partners (e.g., activated p21-activated kinase-2) into the immunological synapse may underlie the increased frequency of cells expressing transcriptionally active forms of NF-kappaB and NFAT and the resultant changes in T cell activation.