Fasting plasma glucose is not sufficient to detect ongoing glucose intolerance after pregnancy complicated by gestational diabetes

AIMS

Women who develop diabetes during pregnancy are at significant risk of developing Type 2 diabetes later in life, and "should be offered blood glucose testing ... to exclude persisting hyperglycaemia" after delivery. New UK guidelines now recommend that this is done by measurement of fasting blood glucose, rather than an oral glucose tolerance test (OGTT). Our study aims to establish whether assessment by fasting blood glucose gives equivalent results to an OGTT.

METHODS

Retrospective data were obtained from four centres in the West Midlands, UK, who performed a postnatal OGTT on 470 women during a 12-month period. All centres used a 75 g, 2-h protocol.

RESULTS

28 of 470 (6.0%) women had diabetes mellitus after testing of fasting plasma glucose. After OGTT, 70 women (14.9%) were found to have impaired glucose tolerance (IGT), and 10 further cases of diabetes were detected (overall prevalence of DM 8.1%). Of the 400 women with normal fasting plasma glucose. After OGTT, 70 women (14.9%) were found to have impaired glucose tolerance (IGT), and 10 further cases of diabetes were detected (overall prevalence of DM 8.1%). Of the 400 women with normal fasting plasma glucose (< or = 6.0 mmol/l), 55 were found to have impaired glucose tolerance and 4 had overt diabetes. In all, 26% of women with diabetes were missed by FPG.

CONCLUSION

Fasting plasma glucose alone does not allow detection of IGT, and misses a substantial proportion of women with Type 2 diabetes. Recognition of ongoing IGT or DM is important in identifying women who may benefit from lifestyle modification, and who may need early intervention in subsequent pregnancies. Our results suggest that OGTT should be the investigation of choice in the postnatal assessment of women who have had GDM.

Sinus arrest and moderate hyperkalemia

Hyperkalemia, especially if severe, is a frequent cause of cardiac rhythm pathologies. Sinus arrest of sudden onset is more likely to occur when the potassium level is very high (e.g. > 8 mmol/l) but in concomitance with negative chronotropic drugs it may occur even in presence of a moderate hyperkalemia. This case report highlights the fact that these kinds of drugs, especially in combination, are probably to be avoided in patients at risk of developing hyperkalemia (e.g. diabetics, renal failure, etc.), even of moderate degree, considering this life-threatening cardiac complication.

Lymphoblastic leukemia/lymphoma in mice overexpressing the Mer (MerTK) receptor tyrosine kinase

Mer (MerTK) is a receptor tyrosine kinase important in platelet aggregation, as well as macrophage cytokine secretion and clearance of apoptotic cells. Mer is not normally expressed in thymocytes or lymphocytes; however, ectopic Mer RNA transcript and protein expression is found in a subset of acute lymphoblastic leukemia cell lines and patient samples, suggesting a role in leukemogenesis. To investigate the oncogenic potential of Mer in vivo, we created a transgenic mouse line (Mer(Tg)) that expresses Mer in the hematopoietic lineage under control of the Vav promoter. Ectopic expression and activation of the transgenic Mer protein was demonstrated in lymphocytes and thymocytes of the Mer(Tg) mice. At 12-24 months of age, greater than 55% of the Mer(Tg) mice, compared to 12% of the wild type, developed adenopathy, hepatosplenomegaly, and circulating lymphoblasts. Histopathological analysis and flow cytometry were consistent with T-cell lymphoblastic leukemia/lymphoma. Mer may contribute to leukemogenesis by activation of Akt and ERK1/2 anti-apoptotic signals, which were upregulated in Mer(Tg) mice. Additionally, a significant survival advantage was noted in Mer(Tg) lymphocytes compared to wild-type lymphocytes after dexamethasone treatment. These data suggest that Mer plays a cooperative role in leukemogenesis and may be an effective target for biologically based leukemia/lymphoma therapy.

An open label comparative study of glimepiride versus repaglinide in type 2 diabetes mellitus Muslim subjects during the month of Ramadan

This study was conducted to compare the treatment efficacy between a prandial glucose regulator, repaglinide and a new sulphonylurea, glimepiride in Muslim Type 2 diabetic patients who practice Ramadan fasting. Forty-one patients, previously treated with a sulphonylurea or metformin, were divided to receive either repaglinide (n=20, preprandially three-times daily) or glimepiride (n=21, preprandially once daily) 3 months before the month of Ramadan. During Ramadan, patients modified their eating pattern to two meals daily, and the triple doses of repaglinide were redistributed to two preprandial doses. Four point blood glucose monitoring were performed weekly during the month of Ramadan and the subsequent month. Measurements of the 4-point blood glucose were significantly lower in the glimepiride group compared to the repaglinide group both during and after Ramadan. The glycaemic excursion was better in the morning for the repaglinide group and better in the afternoon and evening for the glimepiride group during the Ramadan period. There was no statistically significant difference in the incidence of hypoglycaemia between the two groups during and after Ramadan. There was no difference in the glycaemic excursion post-Ramadan. The longer duration of action of glimepiride may offer an advantage over repaglinide during the 13.5 hours of fast in Ramadan for diabetic patients.

Association of simple anthropometric measures of obesity with visceral fat and the metabolic syndrome in male Caucasian and Indo-Asian subjects

AIMS

The aims of this study were first, to investigate the relationship between simple anthropometric measures of obesity with visceral fat as assessed by a single slice magnetic resonance imaging (MRI)-scan in patients attending a hospital clinic. Second, to determine which anthropometric measure best relates to the adverse metabolic profile of the metabolic syndrome.

METHODS

Forty-one male subjects [body mass index (BMI): 30.2 + 5.8 kg/m(2), age: 50.3 + 13.6 years] were studied by MRI-scan to measure visceral fat at L4/L5 level and to investigate its relationship with simple anthropometric measures. Second, we studied 83 male subjects to determine which anthropometric measure best predicts the metabolic complications (using the ATPIII criteria) of obesity in the setting of a hospital clinic.

RESULTS

Waist circumference was the best anthropometric measurement that correlated with MRI-visceral fat mass assessed at L4/L5 in 41 subjects who had an MRI scan (P = 0.0001, r(2) = 0.36, beta = 0.56) amongst variables which also included age, BMI, sagittal diameter, diabetes and ethnicity. Stepwise multiple regression analysis showed sagittal diameter (P = 0.001, r(2) = 0.4, beta = 0.406), age (P = 0.003, beta = 0.271) and waist circumference (P = 0.012, beta = 0.297) were the best predictors of the adverse metabolic profile of the metabolic syndrome in all 83 male subjects amongst BMI, waist-hip ratio (WHR), ethnicity and diabetes-related factors.

CONCLUSIONS

Waist circumference is a simple anthropometric parameter that best correlates with single slice MRI-scan, but sagittal diameter (measured using abdominal calipers) better predicts the adverse metabolic profile of the metabolic syndrome. Although there is considerable variation in abdominal fat topography between ethnic groups, and also within populations, sagittal diameter assessment is a technique that is simple and best predicts the metabolic syndrome.

11beta-hydroxysteroid dehydrogenase type 1 activity in lean and obese males with type 2 diabetes mellitus

Glucocorticoids play an important role in the pathogenesis of obesity and insulin resistance. Impaired conversion of cortisone (E) to cortisol (F) by the type 1 isoenzyme of 11beta-hydroxysteroid dehydrogenase (11beta-HSD) in obesity may represent a protective mechanism preventing ongoing weight gain and glucose intolerance. We have studied glucocorticoid metabolism in 33 male subjects with type 2 diabetes mellitus [age, 44.2 +/- 13 yr; body mass index (BMI), 31.1 +/- 7.5 kg/m(2) (mean +/- sd)] and 38 normal controls (age, 41.4 +/- 14 yr; BMI, 38.2 +/- 12.8 kg/m(2)). Circulating F:E ratios were elevated in the diabetic group and correlated with serum cholesterol and homeostasis model assessment-S. There was no difference in 11beta-HSD1 activity between diabetic subjects and controls. In addition, 11beta-HSD1 activity was unaffected by BMI in diabetic subjects. However, in control subjects, increasing BMI was associated with a reduction in the urinary tetrahydrocortisol+5alpha-tetrahydrocortisol:tetrahydrocortisone ratio (P < 0.05) indicative of impaired 11beta-HSD1 activity. The degree of inhibition correlated tightly with visceral fat mass. Changes in 11beta-HSD1 activity could not be explained by circulating levels of adipocytokines. Impaired E to F metabolism in obesity may help preserve insulin sensitivity and prevent diabetes mellitus. Failure to down-regulate 11beta-HSD1 activity in patients with diabetes may potentiate dyslipidemia, insulin resistance, and obesity. Inhibition of 11beta-HSD1 may therefore represent a therapeutic strategy in patients with type 2 diabetes mellitus and obesity.

Bacterial Canker (Clavibacter michiganensis subsp. michiganensis) of Tomato in Commercial Seed Produced in Indonesia

In 2002, Clavibacter michiganensis subsp. michiganensis (Smith) Davis, the causal organism of bacterial canker of tomato (Lycopersicon esculentum), was isolated from two of six commercial asymptomatic tomato seed lots produced on Java in Indonesia. C. michiganensis subsp. michiganensis has not been reported in Indonesia previously. Methods based on the protocol of the International Seed Health Initiative were used to extract and identify the presence of C. michiganensis subsp. michiganensis in tomato seed. C. michiganensis subsp. michiganensis was isolated with dilution plating on the semiselective media D2ANX and mSCM. The identity of the colonies was confirmed by immunofluorescence microscopy, polymerase chain reaction (2), fatty methyl ester analysis, enzyme-linked immunosorbent assay based on monoclonal antibody 103 (1), and a pathogenicity test in which three replicate tomato plants were stem inoculated with 10⁸ cells ml^-1. Within 2 weeks, stripes on stems developed that split and exposed reddish brown cavities (stem cankers). The presence of C. michiganensis subsp. michiganensis poses a direct threat on tomato production, which is one of five economically most important vegetable crops in Indonesia. References: (1) A. Alvarez et al. Phytopathology 83:1405, 1993. (2) M. S. Santos et al. Seed Sci. Technol. 25:581, 1997.

Tumor necrosis factor-alpha regulates insulin-like growth factor-1 and insulin-like growth factor binding protein-3 expression in vascular smooth muscle

BACKGROUND

Inflammatory mediators such as tumor necrosis factor-alpha (TNF-alpha), interleukin 1beta (IL-1beta), IL-6, and interferon gamma (IFN-gamma) may change coronary plaque integrity by altering vascular smooth muscle cell (VSMC) survival and modifying the extracellular matrix. Insulin-like growth factor-1 (IGF-1) prevents apoptosis, promotes matrix formation, and can decrease TNF-alpha or IL-1beta--induced proteoglycan degradation.

METHODS AND RESULTS

To determine the effects of cytokines on the IGF-1 system, rat aortic VSMCs were exposed to TNF-alpha (10 to 500 ng/mL), IL-1beta (20 pg to 10 ng/mL), IL-6 (100 pg to 15 ng/mL), or IFN-gamma (10 to 600 U/mL). IL-1beta, IL-6, and IFN-gamma did not regulate IGF-1, IGF-1 receptor (R), or IGF binding proteins (IGFBPs). However, TNF-alpha markedly decreased IGF-1 mRNA (85% reduction at 24 hours) and increased IGFBP-3 mRNA and protein (300% increase at 24 hours). These changes were blocked by actinomycin D, consistent with a transcriptional mechanism. Experiments using TNF binding protein-1 indicated that these effects were not attributable to secretion of an autocrine factor. Anti--IGFBP-3 antibodies increased VSMC DNA synthesis 3-fold. In addition, apoptosis induced by TNF-alpha, IFN-gamma, and Fas ligand was markedly reduced by desamino-(1-3)-IGF-1.

CONCLUSIONS

TNF-alpha, a cytokine that is upregulated in atherosclerotic plaques, reduces IGF-1 and increases IGFBP-3 in VSMCs, likely leading to a reduction in bioactive IGF-1. Because IGF-1 is important for growth and survival of VSMCs, its downregulation by TNF-alpha possibly plays a crucial role in acute and chronic coronary syndromes by decreasing VSMC viability and promoting plaque instability.

Treatment of a saphenous vein graft to right ventricle fistula with a PTFE-covered stent: a case report

This report demonstrates the use of a covered stent for the correction of a fistula from a saphenous vein graft to the right ventricle. The use of this stent resulted in complete obliteration of the fistulous tract and restoration of flow into the sequential limb of the graft.

Decreased expression of insulin-like growth factor-1 and apoptosis of vascular smooth muscle cells in human atherosclerotic plaque

Insulin-like growth factor-1 (IGF-1) plays an important role in migration, cell cycle progression and survival of vascular smooth muscle cells (VSMC). We investigated the specific localization of IGF-1 and its receptor (IGF-1R) and their association with apoptosis and the expression of apoptosis-related proteins in early and advanced atherosclerotic lesions. Human atherosclerotic plaques (n=23) from patients undergoing aortic, carotid or femoral arterial surgery were studied. Immunohistochemistry and in situ hybridization revealed significantly higher expression of IGF-1 and IGF-1R in the media than in the intima of early atherosclerotic lesions (P<0.01). Medial VSMC positive for BAX, a proapoptotic protein of the B-cell CLL/lymphoma 2 (BCL2) family, showed colocalization of IGF-1. Apoptosis, as detected by DNA in situ terminal deoxynucleotidyl transferase end labeling (TUNEL), was not present in these early lesions. In advanced atherosclerotic plaques, the expression of IGF-1 and IGF-1R was significantly lower in the intimal regions with macrophage infiltration than in those without macrophage infiltration or than in the media (P<0.01). Furthermore, IGF-1 and IGF-1R immunoreactivity was markedly lower in intimal TUNEL-positive VSMC compared with intimal BAX-positive and medial VSMC (P<0.01). We conclude that IGF-1 and IGF-1R expression are reduced in the deep intima of early atherosclerotic lesions and in areas of advanced plaques with macrophage infiltration. Since IGF-1 is a potent survival factor for VSMC, poor expression of IGF-1 and IGF-1R in intimal regions with macrophage infiltration would likely contribute to triggering VSMC apoptosis potentially leading to plaque weakening, plaque rupture and acute coronary events.

Site-specific regulation of oestrogen receptor-alpha and -beta by oestradiol in human adipose tissue

AIM

To examine the expression of oestrogen receptors alpha and beta (ERalpha and ERbeta) and their regulation by 17beta-oestradiol (E2) in stromal cells and adipocytes from human subcutaneous (s.c.) and omental (o.m.) adipose tissue.

METHODS

Subcutaneous and o.m. abdominal adipose tissues were obtained from 10 women (mean age 63.5 +/- 4.8 years; mean weight 75.6 +/- 6.7 kg) undergoing elective or cosmetic surgery. Immunohistochemistry and RT-PCR analysis were used to detect the presence of ERalpha and ERbeta. The regulation of ERalpha and ERbeta by E(2) (10(-7) M to 10(-9) M) was examined using Western immunoblotting analysis in both s.c. and o.m. stromal cells and mature adipocytes cultured in serum-free, phenol red-free medium.

RESULTS

Immunostaining of s.c. and o.m. adipose tissue showed that the ER subtypes were localized predominantly within the nucleus. Western analysis demonstrated that E2 treatments differentially altered ERalpha and ERbeta expression in s.c. and o.m. adipocytes. In s.c. and o.m. stromal cells, E(2) (10(-8) M) produced a significant up regulation relative to control of 66 kDa ERalpha (s.c.:1.87 +/- 0.22; o.m.:1.97 +/- 0.17; p < 0.05) and 60 kDa ERbeta (s.c.:1.66 +/- 0.3; o.m.: 1.68 +/- 0.16; p < 0.05). In s.c. adipocytes, however, ERalpha expression significantly decreased with E(2) 10(-8) M relative to control while ERbeta expression increased (ERalpha 0.58 +/- 0.06, ERbeta: 1.47 +/- 0.11; p < 0.05). In o.m. adipocytes, the inhibition of ERalpha with E(2) was not observed (ERalpha 1.86 +/- 0.36, ERbeta:1.03 +/- 0.15, p < 0.05)

CONCLUSIONS

ERalpha and ERbeta are expressed but differentially regulated by E(2) in s.c. and o.m. adipocytes and stromal cells. The upregulation of ERbeta by E(2) suggests that E(2) maintains the expression of these receptors. The feed-back inhibition of ERalpha expression by E(2) in s.c. but not o.m. adipocytes observed in vitro is consistent with the data from ERalpha knock out mice where s.c. fat is increased. Selective ER modulators may have different effects in different adipose sites.

Immobilization and stabilization of invertase on Cajanus cajan lectin support

Use of lectins as ligands for the immobilization and stabilization of glycoenzymes has immense application in enzyme research and industry. But their widespread use could be limited by the high cost of their production. In the present study preparation of a novel and inexpensive lectin support for use in the immobilization of glycoenzymes containing mannose or glucose residues in their carbohydrate moiety has been described. Cajanus cajan lectin (CCL) coupled covalently to cyanogen bromide activated Seralose 4B could readily bind enzymes such as invertase, glucoamylase and glucose oxidase. The immobilized and glutaraldehyde crosslinked preparations of invertase exhibited high resistance to inactivation upon exposure to enhanced temperature, pH, denaturants and proteolysis. Binding of invertase to CCL-Seralose was however found to be readily reversible in the presence of 1.0 M methyl alpha-D mannopyranoside. In a laboratory scale column reactor the CCL-Seralose bound invertase was stable for a month and retained more than 80% of its initial activity even after 60 days of storage at 4 degrees C. CCL-Seralose bound invertase exhibited marked stability towards temperature, pH changes and denaturants suggesting its potential to be used as an excellent support for the immobilization of other glycoenzymes as well.

Angiotensin II induces skeletal muscle wasting through enhanced protein degradation and down-regulates autocrine insulin-like growth factor I

We previously showed that angiotensin II (ang II) infusion in the rat produces cachexia and decreases circulating insulin-like growth factor I (IGF-I). The weight loss derives from an anorexigenic response and a catabolic effect of ang II. In these experiments we assessed potential catabolic mechanisms and the involvement of the IGF-I system in these responses to ang II. Ang II infusion caused a significant decrease in body weight compared with that of pair-fed control rats. Kidney and left ventricular weights were significantly increased by ang II, whereas fat tissue was unchanged. Skeletal muscle mass was significantly decreased in the ang II-infused rats, and a reduction in lean muscle mass was a major reason for their overall loss of body weight. In skeletal muscles, ang II did not significantly decrease protein synthesis, but overall protein breakdown was accelerated; inhibiting lysosomal and calcium-activated proteases did not reduce the ang II-induced increase in muscle proteolysis. Circulating IGF-I levels were 33% lower in ang II rats vs. control rats, and this difference was reflected in lower IGF-I messenger RNA levels in the liver. Moreover, IGF-I, IGF-binding protein-3, and IGF-binding protein-5 messenger RNAs in the gastrocnemius were significantly reduced. To investigate whether the reduced circulating IGF-I accounts for the loss in muscle mass, we increased circulating IGF-I by coinfusing ang II and IGF-I, but this did not prevent muscle loss. Our data suggest that ang II causes a loss in skeletal muscle mass by enhancing protein degradation probably via its inhibitory effect on the autocrine IGF-I system.

Rapid polyubiquitination and proteasomal degradation of a mutant form of NAD(P)H:quinone oxidoreductase 1

The NAD(P)H:quinone oxidoreductase 1 (NQO1)*2 polymorphism is characterized by a single proline-to-serine amino acid substitution. Cell lines and tissues from organisms genotyped as homozygous for the NQO1*2 polymorphism are deficient in NQO1 activity. In studies with cells homozygous for the wild-type allele and cells homozygous for the mutant NQO1*2 allele, no difference in the half-life of NQO1 mRNA transcripts was observed. Similarly, in vitro transcription/translation studies showed that both wild-type and mutant NQO1 coding regions were transcribed and translated into full-length protein with equal efficiency. Protein turnover studies in NQO1 wild-type and mutant cell lines demonstrated that the half-life of wild-type NQO1 was greater than 18 h, whereas the half-life of mutant NQO1 was 1.2 h. Incubation of NQO1 mutant cell lines with proteasome inhibitors increased the amount of immunoreactive NQO1 protein, suggesting that mutant protein may be degraded via the proteasome pathway. Additional studies were performed using purified recombinant NQO1 wild-type and mutant proteins incubated in a rabbit reticulocyte lysate system. In these studies, no degradation of wild-type NQO1 protein was observed; however, mutant NQO1 protein was completely degraded in 2 h. Degradation of mutant NQO1 was inhibited by proteasome inhibitors and was ATP-dependent. Mutant NQO1 incubated in rabbit reticulocyte lysate with MG132 resulted in the accumulation of proteins with increased molecular masses that were immunoreactive for both NQO1 and ubiquitin. These data suggest that wild-type NQO1 persists in cells whereas mutant NQO1 is rapidly degraded via ubiquitination and proteasome degradation.

NAD(P)H:quinone oxidoreductase 1 (NQO1): chemoprotection, bioactivation, gene regulation and genetic polymorphisms

NAD(P)H:quinone oxidoreductase 1 (NQO1) is an obligate two-electron reductase that is involved in chemoprotection and can also bioactivate certain antitumor quinones. This review focuses on detoxification reactions catalyzed by NQO1 and its role in antioxidant defense via the generation of antioxidant forms of ubiquinone and vitamin E. Bioactivation reactions catalyzed by NQO1 are also summarized and the development of new antitumor agents for the therapy of solid tumors with marked NQO1 content is reviewed. NQO1 gene regulation and the role of the antioxidant response element and the xenobiotic response element in transcriptional regulation is summarized. An overview of genetic polymorphisms in NQO1 is presented and biological significance for chemoprotection, cancer susceptibility and antitumor drug action is discussed.

Demonstration of functional requirement of polypyrimidine tract-binding protein by SELEX RNA during hepatitis C virus internal ribosome entry site-mediated translation initiation

Polypyrimidine tract-binding protein (PTB) has been previously shown to physically interact with the hepatitis C virus (HCV) RNA genome at its 5'- and 3'-noncoding regions. Using high affinity SELEX RNA molecules, we present evidence for the functional requirement of PTB during HCV internal ribosome entry site (IRES)-controlled translation initiation. This study was carried out in rabbit reticulocyte translation lysates in which the HCV IRES-driven reporter RNA was introduced along with the PTB-specific SELEX RNA molecules. The SELEX RNAs specifically inhibited the HCV IRES function in the context of mono- and dicistronic mRNAs. The cap-dependent translation of a reporter (chloramphenicol acetyltransferase) RNA or naturally capped brome mosaic virus RNA, however, was not affected by the presence of SELEX during in vitro translation assays. The SELEX-mediated inhibition of the HCV IRES is shown to be relieved by the addition of recombinant human PTB in an add-back experiment. The in vivo requirement of PTB was further confirmed by cotransfection of Huh7 cells with reporter RNA and PTB-specific SELEX RNA. The HCV IRES activity was inhibited by the SELEX RNA in these cells, but not by an unrelated control RNA. Together, these results demonstrate the functional requirement of cellular PTB in HCV translation and further support the feasible use of SELEX RNA strategy in demonstrating the functional relevance of cellular protein(s) in complex biological processes.

Five French (5 Fr) guiding catheters for percutaneous coronary angioplasty and stent placement: An initial feasibility study

Thirty patients were treated with percutaneous coronary intervention (PCI) using a 5 Fr guiding catheter. A recently developed, mechanically advantaged hand injector was used to deliver contrast and achieved excellent visualization through the 5 Fr system. Stent sizes ranged from 2.25 to 4.00 mm in diameter and from 8 to 24 mm in length. All primary lesions were successfully treated. The average contrast use was 70 cc per case. There were no major complications and only one minor femoral hematoma. In selected patients, a balloon angioplasty and stent placement can be performed safely and successfully with 5 Fr guiding catheters using currently available products. This technique creates a smaller arterial puncture site, which may obviate the need for a closure device and allow early and safe ambulation. With 5 Fr systems, it appears that contrast usage is reduced, thereby potentially decreasing cost and morbidity. Cathet. Cardiovasc. Intervent. 51:352-357, 2000.

Gender differences in the regulation of P450 aromatase expression and activity in human adipose tissue

OBJECTIVE

To investigate the hormonal regulation of P450 aromatase activity (responsible for the conversion of C19 androgens to C18 oestrogens) in human adipose tissue from men and pre- and post-menopausal women.

SUBJECTS

Subcutaneous abdominal adipose tissue was obtained from 19 subjects: six pre-menopausal females (mean age 41.8+/-(s.e.m.) 2.5; mean weight 76.01+/-5.6 kg), eight post-menopausal females (mean age 59.9+/-2.0; mean weight 63.5+/-2.6 kg), and five males (mean age 35.8+/-8.8; mean weight 78.5+/-7.8 kg) undergoing elective or cosmetic surgery.

MEASUREMENTS

Cell viability and cell size were determined using staining techniques. RT-PCR was used to confirm the presence of aromatase. The regulation of aromatase activity was characterized using androstenedione as a substrate in a tritiated water release assay. Aromatase activity was analysed in abdominal subcutaneous stromal cells (ASC) and mature adipocytes (AD) cultured in serum-free medium with cortisol (10-6-10-7 M), insulin (500 nM) or a combination of both.

RESULTS

In ASC aromatase activity increased in females from 14.5+/-1.7 to 29. 3+/-2.6 pmol/mg/h (n=14, P<0.05) and to 25.2+/-2.1 pmol/mg/h with cortisol (10-7 M) and insulin, respectively (P<0.05). In males ASC basal aromatase activity (20.5+/-4.2 pmol/mg/h; n=5) was inhibited by cortisol (10-7 M) alone (12.3+/-1.8 pmol/mg/h) and in combination with insulin (6.6+/-1.2 pmol/mg/h; men vs women, P<0.005). Aromatase activity in mature adipocytes was stimulated by cortisol plus insulin (P<0.05) with no gender-specific differences. Treatment of ASC from both pre- and post-menopausal females with cortisol alone (10-6 M; 10-7 M) or in combination with insulin demonstrated significantly different aromatase regulation compared with male aromatase stromal cell regulation (P<0.05); however there were no differences in aromatase regulation between pre- and post-menopausal females either in stromal cells or adipocytes.

CONCLUSION

This study shows intrinsic gender differences in the regulation of aromatase, suggesting that differential enzyme regulation may affect sex steroid metabolism to alter the pattern of fat distribution between the sexes.