Four monoclonal antibodies (MAb) specific for the Gtype isoenzyme of rat pyruvate kinase (GPK) were produced and characterized. They detect at least two different epitopes of the isoenzyme, as shown in interference binding assay and Western blot analysis after peptide mapping. The MAb were used in immunohistology to demonstrate the GPK isoenzyme in paraffin-embedded normal rat tissues. GPK was found only in hepatocytes, kidney proximal tubules, islet cells of pancreas, and epithelial cells of the villi of small intestine. The content of GPK in hepatocytes was often lower in the periportal areas as compared with the periveneous zone. In kidneys a dearcut difference in GPK content and distribution existed between male and female rats. Male animals possessed more GPK in the kidney cortex than females. The GPK content in the inner cortical zone (straight proximal tubules) was higher than in the outer cortical zone (convoluted proximal tubules) in kidneys of males. In contrast, female rats displayed less GPK in the inner than in the outer cortical zone of the kidneys. Only some of them exhibited the same amount of the isoenzyme in both parts of the kidney proximal tubules. (J Histochem Cytochem 40665473, 1992)

Objective: Human resistin has been stated to influence preadipocyte cell numbers and to stimulate adipocyte triglyceride lipolysis in vivo and in vitro. However, its role in human obesity remains unclear. Design: Cross-sectional study for comparisons of lean and obese subjects, and subsequent longitudinal 4-month weight loss intervention study in obese subjects. Subjects: Healthy subjects, lean (n ¼ 20, BMIo25) and overweight (n ¼ 43, BMIX25). Measurements: Serum resistin, body weight, body fat, waist-to-hip ratio, as well as markers of insulin resistance and lipid metabolism at baseline and after 4 months of intervention. Results: Serum resistin was positively correlated to HOMA-IR (partial r ¼ 0.288; P ¼ 0.055), serum fructosamines (partial r ¼ 0.280; P ¼ 0.062), serum NEFA (partial r ¼ 0.276; P ¼ 0.066) and negatively to age (partial r ¼ À0.349; P ¼ 0.019) and serum apolipoprotein A-1 (partial r ¼ À0.363; P ¼ 0.014). During the intervention, serum resistin increased significantly (Po0.001). The increase was inversely related to changes in waist-to-hip ratio (P ¼ 0.025) and positively to serum apolipoprotein B (P ¼ 0.011). In males only, the increase in resistin during weight loss was predicted by total serum cholesterol at baseline (r ¼ 0.703, P ¼ 0.007). No relation was observed between changes in resistin and changes in HOMA-IR. Conclusion: The present study indicates an association between serum resistin and markers of abdominal fat distribution as well as the regulation of lipid metabolism. However, human resistin is unlikely to play an independent role in the regulation of glucose metabolism.

Background/Aim: Skinfold-based equations are widely used to evaluate body fat (BF), but over-/underestimation is often reported. We evaluate the capacity of improved skinfold-based equations to estimate BF changes during weight reduction and compare them against well-established equations. Methods: Overweight adults (n = 44) participated in a 4-month weight reduction intervention. Dual-energy X-ray absorptiometry (DXA) and anthropometric measurements were taken at baseline and after intervention. The BF% was calculated using García, Peterson, and Durnin and Womersley (DW) equations. Results: Baseline and postintervention BF% measured by DXA correlated highest with BF% predicted according to García (r = 0.934 and r = 0.948, respectively), followed by Peterson (r = 0.941 and r = 0.932, respectively) and DW (r = 0.557 and r = 0.402, respectively); only a slight systematic error in overestimating the BF% was observed in estimates according to García (r = 0.147 and r = 0.104, respectively; p < 0.001), while increasing errors occurred using the Peterson (r = 0.624 and r = 0.712, respectively; p < 0.001) and DW (r = 0.767 and r = 0.769, respectively; p < 0.001) equations. Moderate correlations between BF changes (kg) measured by DXA and predicted by DW (r = 0.7211), Peterson (r = 0.697), and García (r = 0.645) were observed. Conclusion: Improved skinfold equations cannot accurately measure changes in BF after weight reduction.

The effect of di(2-ethylhexyl)phthalate (DEHP) on diethylnitrosamine (DEN)-initiated preneoplastic liver lesions with expression of gamma-glutamyltranspeptidase (GGTase) and loss of adenosine triphosphatase (ATPase) as well as alterations of hepatic carbohydrate metabolism in male and female Sprague-Dawley rats have been investigated. Two treatment schedules have been compared with respect to their sensitivity by the histochemical demonstration of preneoplastic islands and by the biochemical determination of alterations in enzyme activities of liver homogenates and of serum, the last indicating hepatotoxicity. For initiation, a single dose of DEN was given, followed by treatment with various doses of DEHP given three times weekly by gavage for 7 or 11 consecutive weeks. As histochemical enzyme markers, the expression of positive GGTase as well as the deficiency in ATPase were used for identification of liver foci. The weanling female rats (protocol A) were found to be more sensitive to the carcinogenic effect of DEN in view of foci incidence than the mature male rats which underwent partial hepatectomy prior to DEN application. The administration of 200 mg DEHP/kg body wt increased the incidence of ATPase-deficient foci in both male and female rats; however, concentrations of 1000 and 2000 mg DEHP/kg decreased the incidence of liver foci. The number of foci with expression of GGTase was only slightly increased in female rats following a DEHP concentration of 50 mg/kg, and 200 mg/kg body wt. DEHP alone did not induce preneoplastic lesions that could be identified by these two markers. Biochemical investigations indicate that DEHP alters the metabolic pattern in liver. An increase of the NADP-linked enzymes glucose-6-phosphate dehydrogenase (G6PDH), malic enzyme, extra-mitochondrial ICDH as well as an enhancement of NAD-dependent alpha-G3PDH and lactate dehydrogenase were found following DEHP administration. On the other hand the glycolytic enzymes pyruvate kinase (PK) and enolase as well as the gluconeogenetic enzyme fructose-1,6-bisphosphatase (FBPase) were significantly reduced. In protocol B (male rats) the reactions of PK, FBPase and malic enzyme were more altered after DEHP exposure than in protocol A, while the activity of G6PDH was more increased in protocol A. Most enzymes being involved in the carbohydrate metabolism are influenced by DEHP in a dose-dependent manner. There was no increase in serum FBPase activity in both male and female rats after DEHP treatment but a reduction of glutamate-oxalate-transaminase and glutamate-pyruvate-transaminase activities was observed.(ABSTRACT TRUNCATED AT 400 WORDS)