Sex-related differences in the insulin resistance syndrome

A comparison of the NCEP-ATPIII, IDF and AHA/NHLBI metabolic syndrome definitions with relation to early carotid atherosclerosis in subjects with hypercholesterolemia or at risk of CVD: evidence for sex-specific differences

The metabolic syndrome is associated with increased risk of cardiovascular disease. However, the association between metabolic syndrome and atherosclerosis in hypercholesterolemic patients remains unknown. We examined the association between carotid atherosclerosis and metabolic syndrome definitions using the NCEP-ATPIII, International Diabetes Federation (IDF) and American Heart Association/National Heart, Lung, and Blood Institute (AHA/NHLBI) definitions in 1782 subjects at risk of cardiovascular disease including 926 with hypercholesterolemia (LDL cholesterol > or =160 mg/dL; mean=203 mg/dL). Irrespective of definition, carotid intima-media thickness was significantly higher in both men and women diagnosed with the MetS compared to those without MetS. This relationship persists in males with hypercholesterolemia, independently of LDL cholesterol level. Regression analyses, both unadjusted and adjusted for traditional risk factors, indicate that in males the AHA/NHLBI definition, and in females the IDF definition are the strongest predictors of carotid atherosclerosis. These results highlight important gender differences that exist in the current clinical definitions of the metabolic syndrome, with regards to predicting early atherosclerotic lesions. In addition, this study shows that in males with hypercholesterolemia, MetS is independently associated with increased atherosclerosis, supporting screening for MetS among people at risk of CVD.

Scribble is essential for olfactory behavior in Drosophila melanogaster

The ability to discriminate and respond to chemical signals from the environment is an almost universal prerequisite for survival. Here, we report that the scaffold protein Scribble is essential for odor-guided behavior in Drosophila. Previously, we identified a P-element insert line with generalized sexually dimorphic smell impairment, smi97B. We found that the transposon in this line is located between the predicted promoter region and the transcription initiation site of scrib. A deficiency in this region, Df(3R)Tl-X, and two scrib null alleles fail to complement the smell-impaired phenotype of smi97B. Wild-type behavior is restored by precise excision of the P element, scrib mRNA levels correspond with mutant and wild-type phenotypes, and introduction of a full-length scrib transgene in the smi97B mutant rescues the olfactory deficit. Expression of Scrib is widespread in olfactory organs and the central nervous system. Finally, alternative splicing of scrib generates transcripts that differ in the number of leucine-rich repeats and PDZ domains.

Relationship among hyperinsulinemia, insulin resistance, and hypertension is dependent on sex

Hyperinsulinemia and insulin resistance have been linked to hypertension; however, the influence of sex on this relationship has not been well studied. The purpose of this experiment was to compare the effects of chronic insulin treatment on insulin sensitivity and blood pressure in male and female rats. Male and female Wistar rats were treated with insulin (2 U/day) via subcutaneous sustained release implants for 5 wk. Systolic blood pressure was measured via the tail-cuff method before and after treatment, and insulin sensitivity was assessed with an oral glucose tolerance test. The insulin sensitivity of female rats was 4.5-fold greater than male rats. Chronic insulin treatment impaired insulin sensitivity in both sexes; however, this occurred to a greater degree in male rats. Blood pressure increased in male rats treated with insulin only. The results demonstrate that hyperinsulinemia and insulin resistance are associated with hypertension in male rats only. Therefore, the link between these conditions appears to depend on sex.

Connections between obesity and dyslipidaemia

The importance of the obesity-lipid connection has suffered from the traditional reductionism view of science. Excess body weight has rarely been deemed an independent risk factor for coronary heart disease, directing physicians to target therapies towards the risk factors that excess body weight modifies (e.g. raising HDL, lowering blood pressure) instead of targeting the cause. The efforts of Adult Treatment Panel III to define and identify the metabolic syndrome as a secondary target may spur practitioners to revisit the need for weight management in patients with lipid disorders.