An intrinsic circadian clock of the pancreas is required for normal insulin release and glucose homeostasis in mice

Aims/hypothesis  

Loss of circadian clocks from all tissues causes defective glucose homeostasis as well as loss of feeding and activity rhythms. Little is known about peripheral tissue clocks, so we tested the hypothesis that an intrinsic circadian clock of the pancreas is important for glucose homeostasis.     

Estrogen signaling and disruption of androgen metabolism in acquired androgen-independence during cadmium carcinogenesis in human prostate epithelial cells

BACKGROUND: Lethal prostate cancers often become androgen-independent due to androgen receptor (AR) overexpression. The role of cadmium in prostate tumor progression was determined. METHODS: Control and cadmium-transformed prostate epithelial cells (CTPE) were compared for steroid-induced proliferation, steroid receptor expression, and androgen metabolism. RESULTS: CTPE cells showed rapid proliferation in complete medium and sustained proliferation in steroid-reduced medium. Androgens stimulated significantly less cell proliferation and AR-related genes expression in CTPE cells. 5alpha-Dihydrotestosterone increased PSA expression more effectively in control cells. Flutamide reduced 5alpha-dihydrotestosterone-stimulated growth less effectively in CTPE cells compared to control. CTPE cells showed decreased p27 expression. Estrogen receptors were overexpressed and estradiol markedly stimulated proliferation in CTPE cells. In CTPE cells 5alpha-aromatase was markedly increased, while 5alpha-reductase was decreased. CONCLUSIONS: Cadmium-induced malignant transformation stimulates androgen independence, unrelated to AR expression or activity. Increased estrogen receptor and 5alpha-aromatase expression suggest estrogen signaling may be critical to this process.     

Interaction of angiotensin-converting enzyme and apolipoprotein E gene polymorphisms in ischemic stroke involving large-vessel disease

A relationship between apolipoprotein E (Apo E) genotype and angiotensin-converting enzyme (ACE) insertion-deletion (Ins-Del) mutation and stroke was suggested. We investigated the association of Apo E4 and ACE Ins/Del genotypes with stroke risk and changes in serum lipids in 228 consecutive Tunisian stroke patients, and 323 age-and gender-matched controls. Comparable frequencies of ACE Ins/Del alleles were seen between patients and controls. The prevalence of Apo ε3 allele and Apo E3/E3 were lower (P < 0.001), while the frequency of Apo ε4 allele and ε4-containing genotypes (E3/E4 and E4/E4) were elevated (P < 0.001) among patients. Higher proportion of Apo E4-carrying + ACE Del/Del positive cases were seen in young (<50 years) patients (P = 0.012), and was associated with large vessel stroke (P = 0.035). Mean serum cholesterol, LDL, HDL, and triglycerides were comparable between E4-containing and no E4-containing and ACE Del/Del-positive patients. Apo E4 and ACE Del/Del genotype combination substantially increase stroke risk, supporting the notion that interactions of multiple gene variants influence stroke pathogenesis.     

Initial development of a questionnaire evaluating perceived benefits and barriers to pediatric clinical trials participation

ObjectiveTo evaluate perceived benefits and barriers to pediatric clinical trials participation to improve decision-making and enhance recruitment and retention among minority youth with chronic health conditions (sickle cell disease, asthma) and their caregivers.MethodsA questionnaire was developed based on the social ecological model using input from medical experts and community-based public health organizations. Parallel caregiver, adolescent/young adult (AYA; 16–39 years old), and child (8–15 years old) versions were field tested. Patients and caregivers completed the questionnaire, which included demographic items, perceived life stress and social desirability measures.ResultsExploratory factor analysis rendered a four-factor solution for the caregiver version (direct treatment benefit, mistrust of research/researchers, trust in healthcare team to engage in safe research, and opportunity cost) and the AYA version (mistrust/no direct benefit, safety, direct treatment benefit/practical considerations, and social support for research). Factor structures differed for SCD and asthma caregivers; results were equivocal for the child version. Summated subscales were not significantly associated with patient demographics or social desirability, but significant correlations with perceived life stress and prior participation in research were identified.ConclusionsWhile the factor structure should be confirmed with larger samples, findings indicate potential benefit, perceived harm due to mistrust of researchers, and logistics are primary factors in decision-making about participation in pediatric clinical trials. By addressing these benefits/barriers through adjustments to recruitment and informed consent procedures, researchers may address misperceptions of research, improve decision-making, and increase recruitment and retention particularly for ethnic minority children with chronic health conditions.     

Factor V Leiden, prothrombin 20210G>A, MTHFR 677C>T and 1298A>C, and homocysteinemia in Tunisian blood donors

Specific genetic conditions are known to be associated with high risk of venous thromboembolism. This genetic basis varies widely between ethnic groups. We investigated the distribution of four inherited polymorphisms in 113 unselected Tunisian blood donors by using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. The allele frequencies of Factor V Leiden (FVL), prothrombin 20210G>A, methylenetetrahydrofolate reductase (MTHFR) 677C>T, and MTHFR 1298A>C mutations were 3, 0.9, 30, and 31%, respectively. The MTHFR 677C>T polymorphism was influenced by age. Twenty-nine of the 113 blood donors demonstrated more than one genetic markers. Hyperhomocysteinemia was found in 12 subjects, and it was statistically associated to the MTHFR 677TT genotype. Principal component analysis allowed disclosing the resemblance between Mediterranean populations. Our findings may be helpful for population genetics study, and provide epidemiologic database for further studies in thrombosis field among Tunisians.