Citations

Caveolar endocytosis is an important mechanism for the uptake of certain pathogens and toxins and also plays a role in the internalization of some plasma membrane (PM) lipids and proteins. However, the regulation of caveolar endocytosis is not well understood. We previously demonstrated that caveolar endocytosis and β1-integrin signaling are stimulated by exogenous glycosphingolipids (GSLs). In this study, we show that a synthetic GSL with nonnatural stereochemistry, β-d-lactosyl-N-octanoyl-l-threo-sphingosine, (1) selectively inhibits caveolar endocytosis and SV40 virus infection, (2) blocks the clustering of lipids and proteins into GSLs and cholesterol-enriched microdomains (rafts) at the PM, and (3) inhibits β1-integrin activation and downstream signaling. Finally, we show that small interfering RNA knockdown of β1 integrin in human skin fibroblasts blocks caveolar endocytosis and the stimulation of signaling by a GSL with natural stereochemistry. These experiments identify a new compound that can interfere with biological processes by inhibiting microdomain formation and also identify β1 integrin as a potential mediator of signaling by GSLs.

Background— Data supporting the prognostic significance of high-sensitivity C-reactive protein (hs-CRP) are derived largely from individuals with no overt coronary artery disease or from patients with acute coronary syndromes. In contrast, the ability of hs-CRP to predict outcomes in patients with stable coronary artery disease and the prognostic significance of the Centers for Disease Control/American Heart Association hs-CRP cut points in such a population remain relatively unexplored. Methods and Results— We measured hs-CRP in 3771 patients with stable coronary artery disease from the Prevention of Events With Angiotensin-Converting Enzyme Inhibition (PEACE) trial, a randomized placebo-controlled trial of the angiotensin-converting enzyme inhibitor trandolapril. Patients were followed up for a median of 4.8 years for cardiovascular death, myocardial infarction, or stroke, as well as new heart failure and diabetes. After adjustment for baseline characteristics and treatments, higher hs-CRP levels, even >1 mg/L, were associated with a significantly greater risk of cardiovascular death, myocardial infarction, or stroke (hs-CRP 1 to 3 mg/L: adjusted hazard ratio, 1.39; 95% CI, 1.06 to 1.81; P =0.016; hs-CRP >3 mg/L: adjusted hazard ratio, 1.52; 95% CI, 1.15 to 2.02; P =0.003). Similarly, elevated hs-CRP levels were an independent predictor of new heart failure (adjusted P <0.001 for trend) and new diabetes (adjusted P <0.001 for trend). There were no significant interactions between hs-CRP levels and the effects of trandolapril on any of the above outcomes. Conclusions— In stable coronary artery disease, an elevated hs-CRP level, even >1 mg/L, is a significant predictor of adverse cardiovascular events independently of baseline characteristics and treatments. An elevated hs-CRP does not appear to identify patients with stable coronary artery disease and preserved ejection fraction who derive particular benefit from angiotensin-converting enzyme inhibition.

Abstract Rationale Computed tomography (CT) scanning of the lung may reduce phenotypic heterogeneity in defining subjects with chronic obstructive pulmonary disease (COPD), and allow identification of genetic determinants of emphysema severity and distribution. Objectives We sought to identify genes associated with CT scan distribution of emphysema in individuals without α1-antitrypsin deficiency but with severe COPD. Methods We evaluated baseline CT densitometry phenotypes in 282 individuals with emphysema enrolled in the Genetics Ancillary Study of the National Emphysema Treatment Trial, and used regression models to identify genetic variants associated with emphysema distribution. Measurements and Main Results Emphysema distribution was assessed by two methods—assessment by radiologists and by computerized density mask quantitation, using a threshold of −950 Hounsfield units. A total of 77 polymorphisms in 20 candidate genes were analyzed for association with distribution of emphysema. GSTP1, EPHX1, and MMP1 polymorphisms were associated with the densitometric, apical-predominant distribution of emphysema (p value range = 0.001–0.050). When an apical-predominant phenotype was defined by the radiologist scoring method, GSTP1 and EPHX1 single-nucleotide polymorphisms were found to be significantly associated. In a case–control analysis of COPD susceptibility limited to cases with densitometric upper-lobe–predominant cases, the EPHX1 His139Arg single-nucleotide polymorphism was associated with COPD (p = 0.005). Conclusions Apical and basal emphysematous destruction appears to be influenced by different genes. Polymorphisms in the xenobiotic enzymes, GSTP1 and EPHX1, are associated with apical-predominant emphysema. Altered detoxification of cigarette smoke metabolites may contribute to emphysema distribution, and these findings may lead to further insight into genetic determinants of emphysema.

Abstract In the current study, we examined a panel of serially passaged glioblastoma xenografts, in the context of an intracranial tumor therapy response model, to identify associations between glioblastoma molecular characteristics and tumor sensitivity to the epidermal growth factor receptor (EGFR) kinase inhibitor erlotinib. From an initial evaluation of 11 distinct glioblastoma xenografts, two erlotinib-sensitive tumors were identified, each having amplified EGFR and expressing wild-type PTEN. One of these tumors expressed truncated EGFRvIII, whereas the other expressed full-length EGFR. Subsequent cDNA sequence analysis revealed the latter tumor as expressing an EGFR sequence variant with arginine, rather than leucine, at amino acid position 62; this was the only EGFR sequence variant identified among the 11 xenografts, other than the aforementioned vIII sequence variant. EGFR cDNAs were then examined from 12 more xenografts to determine whether additional missense sequence alterations were evident, and this analysis revealed one such case, expressing threonine, rather than alanine, at amino acid position 289 of the extracellular domain. This glioblastoma was also amplified for EGFR, but did not display significant erlotinib sensitivity, presumably due to its lacking PTEN expression. In total, our study identified two erlotinib-sensitive glioblastoma xenografts, with the common molecular characteristics shared by each being the expression of wild-type PTEN in combination with the expression of amplified and aberrant EGFR. [Mol Cancer Ther 2007;6(3):1167–74]

Using the Minnesota Multiphasic Personality Inventory (MMPI), this study investigated preoperative and postoperative emotional and personality adjustment of temporal lobectomy patients from two major epilepsy surgery centers. Temporal lobectomy patients were included only if they were without evidence of lesional pathology on magnetic resonance imaging (MRI; other than evidence of mesial temporal sclerosis), were left-hemisphere language-dominant, and had Wide Range Achievement Test-Revised (WRAT-R) reading achievement standard scores of 70 or higher. The MMPI was completed by 175 patients before and after a temporal lobectomy. There were no significant preoperative differences on any MMPI scale between right temporal (n = 79) and left temporal (n = 96) lobectomy patients. Analysis of MMPI data from one of the surgical centers revealed significant effects for postoperative seizure control. Minimal effects of laterality of seizure onset on preoperative or postoperative psychological adjustment were found. Adequacy of preoperative psychological adjustment and postoperative seizure control have a greater impact on preoperative to postoperative psychological adjustment than side of seizure onset.

Lipolysis of adipose tissue triglycerides releases glycerol. Twenty-four volunteers, of whom 6 were obese and 13 were women, received a primed-constant infusion of 2H5-glycerol for 120 min during postabsorptive steady-state conditions. Arterial, abdominal venous, and interstitial (microdialysis) samples were taken, and a four-compartment model was applied to assess subcutaneous abdominal adipose tissue glycerol kinetics. Adipose tissue blood flow was measured using 133Xe washout. Venous glycerol concentrations (median 230 μmol/l [interquartile range 210–268]) were consistently greater than those of arterial blood (69.1 μmol/l [56.5–85.5]), while glycerol isotopic enrichments (tracer-to-tracee ratio) were greater in arterial blood (8.34% [7.44–10.1]) than venous blood (2.34% [1.71–2.69], P &lt; 0.01). Microdialysate glycerol enrichment was 1.44% (1.11–1.79), indicating incomplete permeability of glycerol between capillary blood and interstitium. Calculated interstitial glycerol concentrations were between 270 μmol/l (256–350) and 332 μmol/l (281–371) (examining different boundary conditions). The calculated capillary diffusion capacity (ps) was between 2.21 ml · 100 g tissue−1 · min−1 (1.31–3.13) and 3.09 ml · 100 g tissue−1 · min−1 (1.52–4.90) and correlated inversely with adiposity (Rs ≤ −0.45, P &lt; 0.05). Our results support previous estimates of interstitial glycerol concentration within adipose tissue and reveal capillary diffusion capacity is reduced in obesity.

Insulin resistance increases and muscle oxidative capacity decreases during aging, but lifestyle changes—especially physical activity—may reverse these trends. Here we report the effect of a 16-week aerobic exercise program (n = 65) or control activity (n = 37) performed by men and women aged 21–87 years on insulin sensitivity and muscle mitochondria. Insulin sensitivity, measured by intravenous glucose tolerance test, decreased with age (r = −0.32) and was related to abdominal fat content (r = −0.65). Exercise increased peak oxygen uptake (Vo2peak; 10%), activity of muscle mitochondrial enzymes (citrate synthase and cytochrome c oxidase, 45–76%) and mRNA levels of mitochondrial genes (COX4, ND4, both 66%) and genes involved in mitochondrial biogenesis (PGC-1α, 55%; NRF-1, 15%; TFAM, 85%). Exercise also increased muscle GLUT4 mRNA and protein (30–52%) and reduced abdominal fat (5%) and plasma triglycerides (25%). None of these changes were affected by age. In contrast, insulin sensitivity improved in younger people but not in middle-aged or older groups. Thus, the muscle mitochondrial response to 4 months of aerobic exercise training was similar in all age-groups, although the older people did not have an improvement in insulin sensitivity.

The major predisposing genetic component in type 1 diabetes maps to the major histocompatibility complex locus in both mice and humans. To verify the HLA class II association with disease pathogenesis, we adopted the transgenic approach. Expression of HLA-DQ8, the molecule showing the strongest association with human type 1 diabetes, in the diabetes-predisposing milieu of NOD mice in the absence of the endogenous class II molecule I-Ag7 did not render susceptibility to type 1 diabetes. To study if providing a local proinflammatory environment would lead to diabetes in these mice, Aβo.NOD.DQ8 were bred with C57BL/6 mice expressing tumor necrosis factor (TNF)-α in the β-cells of the islets of Langerhans. Surprisingly, although diabetes was evident in the F1 intercross expressing rat insulin promoter (RIP)-TNF, offspring lacking either endogenous or transgenic class II molecules developed accelerated diabetes with high frequency in both sexes. Moreover, expression of any functional class II molecule seemed to confer significant protection from diabetes in this model. Thus, neonatal expression of TNF-α in an islet-specific manner bypassed the requirement of CD4+ T-cells and resulted in diabetes that could be mediated by CD8+ T-cells. We also show for the first time that diabetes in NOD.RIP-TNF mice can occur independent of inheritance of NOD-derived idd1.