Sex-dependent difference in the relationship between adipose-tissue cholesterol efflux and estradiol concentrations in young healthy humans.

BACKGROUND: Impaired adipose tissue function and lower levels of high density lipoprotein cholesterol (HDL-C) have been implicated in the development of vascular dementia, and metabolic diseases such as hypertension, atherosclerosis, type 2 diabetes (T2D) and metabolic syndrome. Interestingly, both the substrate fluxes in adipose tissue and HDL-C concentration differ between men and women. Moreover, adipose tissue cholesterol efflux has been implicated in modulation of HDL-C levels. Thus, we aimed to determine if the association between serum estradiol levels and adipose tissue cholesterol efflux is sex-dependent. METHOD: We evaluated the serum estradiol levels and adipose tissue cholesterol efflux in young healthy men (n=5) and women (n=3). Adipose tissue cholesterol efflux was determined using subcutaneous microdialysis probes. Linear regression analyses were used to determine the relationship between the parameters, p<0.05 was considered as statistically significant. RESULTS: Our data demonstrated that serum estradiol levels directly associated with adipose tissue cholesterol efflux; however, the relationships may be sex-dependent. We discussed our results in the context of currently available data regarding sex-dependent variability in adipose tissue function and HDL-C metabolism as a potential contributor to higher rates of vascular dementia in men. Further research is required to understand the sex-dependent and -independent variabilities in adipose tissue metabolism to determine novel targets for interventions to prevent the development of vascular dementia.

Acute myocardial infarction and pulmonary embolism in a young man with pernicious anemia-induced severe hyperhomocysteinemia.

A 27 year-old man who presented to the hospital with progressive lower extremity weakness, developed an acute ST elevation myocardial infarction on his second hospital day. Primary angioplasty to the left anterior descending coronary artery was performed. Due to persistent dyspnea, the patient underwent a diagnostic chest computed tomography which confirmed multiple small pulmonary emboli. Laboratory analysis revealed a megaloblastic anemia with a reduced vitamin B12 level and positive titers for antibodies against intrinsic factor, establishing a diagnosis of pernicious anemia. Screening for hypercoaguable markers documented an isolated severely elevated homocysteine levels (105 mumol/l). No other significant risk factors for coronary artery disease including a family history of premature atherosclerosis were identified. This case illustrates the importance of testing for hyperhomocysteinemia as part of a workup for atherothrombotic disease, especially in patients without other significant risk factors. The severity of hyperhomocysteinemia found in our patient is unusual for patients with vitamin B12 malabsorption and raises the question of whether the widely practiced folic acid fortification in the United States may mask or even worsen vitamin B12 deficiency over time, leading to more severe cases of vitamin B12 deficiency and hyperhomocysteinemia than seen in the past.