Abstract 410: Link Between Hypertension and Insulin Resistance in South Asians: Implications for Prevention of Cardiovascular Complications

Background: The coexistence of hypertension (HTN) and insulin resistance (IR) substantially increases cardiovascular risk (CVR) and diabetes (DM) perhaps by endothelial dysfunction from low-grade chronic inflammation and oxidative stress. South Asian immigrants in United States (SA-USA) have a high salt consumption, IR, and salt sensitivity. The triglyceride (TG)/ HDL ratio is a known correlate of IR with ratios ≥3.5 associated with high risk. It is unknown whether SA-USA have a coexistence of HTN, IR, and DM resulting in high CVR.

Methods: We reviewed the clinical history and Vertical Auto Profile technology (VAP) + lipid panel utilizing ultracentrifugation to directly measure lipid sub-fractions, for 348 participants (42% women) of the South Asian Cardiovascular Registry. Prevalent DM and Pre-DM were defined as HbA1c ≥ 6.5 and 5.7-6.4, respectively.

Results: Of the 348 participants, mean age 55.3 years, 128 had HTN and were stratified into clinical risk groups based on fasting TG (mg/dL) levels: TG<150 (n=69), TG 150-199 (n=24), TG 200-499 (n=32), TG>500 (n=3). The corresponding TG/HDL ratios were: 1.7, 3.5, 6.2, and 20.4, respectively; the median TG (mg/dL) levels were: 100, 182, 268, and 572, respectively; the median LDL (mg/dL) levels were: 113, 144, 133, 102, respectively; the rates of DM were: 13%, 17%, 38%, and 67%; and the rates of Pre-DM/DM were: 62%, 63%, 78%, and 67%, respectively. Relative Risk for DM with TG/HDL≥ 3.5 was 3.6 (46 % had TG/HDL ≥ 3.5).

Conclusions: South Asian immigrants participating in a community registry have: 1) A high rate of coexistence of HTN and IR portending a very high relative risk of diabetes. 2) A discordance of LDL levels and IR in patients with HTN. As IR gets higher, the relative risk of diabetes goes up but LDL levels decline.

Clinical Implications: South Asian immigrants in the United States have a diet that is very high in salt, simple carbohydrates, and saturated fat. Many are vegetarian with no consumption of fish. Public health efforts to help reduce risk of CVD in South Asian immigrants should focus on low salt diet, with consumption of multigrain complex carbohydrates, poly-unsaturated fatty acids, omega-3 fatty acids, and lifestyle changes to reduce metabolic syndrome, diabetes, and hypertension.

Estrogen increases hepatic lipase levels in inbred strains of mice: a possible mechanism for estrogen-dependent lowering of high density lipoprotein

We have shown mouse to be an useful animal model for studies on the estrogen-mediated synthesis and secretion of lipoproteins since, unlike in rats, low density lipoprotein receptors are not upregulated in mice. This results into the elevation of plasma levels of apolipoprotein (apo) B and apoE, and lowering of apoA-1-containing particles. The mechanisms of apoB and apoE elevation by estrogen have been elucidated, but the mechanism of lowering of plasma levels of HDL is still not known. Among other factors, apoA-I, cholesterol ester transfer protein (CETP), scavenger receptor B1 (SR-B1), and hepatic lipase are potential candidates that modulate plasma levels of HDL. Since estrogen treatment increased hepatic apoA-I mRNA and apoA-I synthesis, and mouse express undetectable levels of CETP, we tested the hypothesis that estradiol-mediated lowering of HDL in mice may occur through modulation of hepatic lipase (HL). Four mouse strains (C57L, C57BL, BALB, C3H) were administered supraphysiological doses of estradiol, and plasma levels of HDL as well as HL mRNA were quantitated. In all 4 strains estradiol decreased plasma levels of HDL by 30%, and increased HL mRNA 2-3 fold. In a separate experiment groups of male C57BL mouse were castrated or sham-operated, and low and high doses of estradiol administered. We found 1.4-2.5 fold elevation of HL mRNA with concomitant lowering of HDL levels. Ten other mouse strains examined also showed estradiol-induced elevation of HL mRNA, but the extent of elevation was found to be strain-specific. Based on these studies, we conclude that hepatic lipase is an important determinant of plasma levels of HDL and that HL mRNA is modulated by estrogen which in turn may participate in the lowering of plasma levels of HDL.

Primary renal angiosarcoma: a case report and review of the literature

Primary renal angiosarcoma is very rare. To our knowledge, only 15 cases have been reported to date. A 77-year-old Japanese man with a unilateral kidney presented with massive hematuria followed by renal failure. A renal tumor was suspected and a left nephrectomy was performed. The histopathological diagnosis was angiosarcoma of the kidney. A hemorrhagic tumor measuring 10 x 5 cm and clotted blood was found in the medullary area. The atypical tumor cells had a sinusoidal and solid appearance, and showed immunohistochemically positive reactions for some of the endothelial markers. The patient died about 21 months after the nephrectomy and the autopsy revealed massive metastases to the liver and retroperitoneum. One of the differential diagnoses of the case was angiomyolipoma, because the tumor cells were relatively bland in their histological appearance with entrapped fat cells in the pelvic area. Fifteen case reports with titles that included the term 'hemangiosarcoma/angiosarcoma', 'hemangioendothelioma/endothelioma' or 'vascular sarcoma' of the kidney were reviewed and compared to the present case.

A histopathologic and immunohistochemical study of small nodules of renal angiomyolipoma: a comparison of small nodules with angiomyolipoma

Small mesenchymal nodules (SNs) are observed in some cases of renal angiomyolipoma (AML), with or without tuberous sclerosis. They are composed of blood vessels and/or nonvascular smooth muscle cells (SMCs) and/or fat cells. We examined 20 cases of AML, performed detailed histopathologic and immunohistochemical studies of SNs, verified the histologic relationship between SNs and AMLs, and compared the SNs of the tuberous/nontuberous sclerosis groups. Seventy-seven SNs were observed in five cases of AML. The SNs were 0.11 mm to 20.0 mm in diameter. The location of small-sized SNs in the kidney was variable; almost all of the SNs larger than 3.25 mm were in the renal capsule. The small-sized SNs contained mainly epithelioid-type nonvascular SMCs. Blood vessels and fat cells were not observed in the small-sized SNs but appeared gradually in the large-sized SNs. Almost all of the SNs were rounded lesions, and no fusion was observed between the SNs. Nonvascular SMCs of all of the SNs and AMLs were positive for vimentin, alpha-SM actin, and S-100 protein. The SNs less than 1.13 mm in diameter were negative for HMB-45; the nonvascular SMCs of AMLs and of SNs greater than 1.13 mm in diameter were positive for HMB-45. Nonvascular SMCs of SNs and AMLs showed a neurogenic phenotype. The SNs of the nontuberous sclerosis group contained only SMC components, whereas the same-size SNs of the tuberous sclerosis group contained SMCs, fat cells, and blood vessels. The SNs of the nontuberous sclerosis group may not increase in size or may grow slowly. Some of the SNs of patients with tuberous sclerosis grow to become AML. Although the SNs in patients with nontuberous sclerosis do not contain any blood vessels or fat cells, their SMCs show the histologic and immunohistochemical characteristics of AMLs; this indicates that SNs are the "buds" of AML.

Infantile digital fibromatosis: a study of the development and regression of cytoplasmic inclusion bodies

An 8-yr-old Japanese boy developed infantile digital fibromatosis in the right ring finger with recurrence and another lesion in the right middle finger. Histologic investigation of the tumor disclosed that the size and frequency of inclusion bodies were inversely proportional to the degree of fibrosis. Electron microscopic study revealed a variety of stages in the development of inclusion bodies, ranging from small, dense aggregates of filaments into bundles with dense bodies traversing the cytoplasm to typical inclusion bodies that also contained cytoplasmic organelles. In areas of dense fibrosis, the cytoplasm of the tumor cells showed areas of constriction and compression by adjacent bundles of collagen. The tendency for a decrease in the number of inclusion bodies in these areas necessitated a differential diagnosis from other fibrous or fibro-histiocytic lesions. Our findings suggest that the tumor may undergo a decrease in the numbers of inclusion bodies and spontaneously may become fibrotic with time. Thus, even as a form of fibromatosis featuring both recurrence and multiple lesions, it may not have a consistently aggressive nature. These findings support the concept that infantile digital fibromatosis should be managed by limited excision rather than by immediate aggressive surgical treatment.