Horse haemoglobin phenotyping by agarose gel isoelectric focusing comparison of Thoroughbreds with other Equidae

By using isoelectric focusing in thin agarose slab gels 1049 Thoroughbred, 82 Nooitgedachter, 45 Percheron and 244 horses of other breeds were examined. The numbers of other Equidae tested were 107 donkeys, 50 mules, 4 common zebras (Equus burchelli boehmi) and 8 mountain zebras (Equus zebra hartmannae). Phenotypic data are presented for all tested animals and gene frequencies are calculated for the horses.     

Deletion of Glutathione Peroxidase-2 Inhibits Azoxymethane-Induced Colon Cancer Development

The selenoprotein glutathione peroxidase-2 (GPx2) appears to have a dual role in carcinogenesis. While it protected mice from colon cancer in a model of inflammation-triggered carcinogenesis (azoxymethane and dextran sodium sulfate treatment), it promoted growth of xenografted tumor cells. Therefore, we analyzed the effect of GPx2 in a mouse model mimicking sporadic colorectal cancer (azoxymethane-treatment only). GPx2-knockout (KO) and wild-type (WT) mice were adjusted to an either marginally deficient (−Se), adequate (+Se), or supranutritional (++Se) selenium status and were treated six times with azoxymethane (AOM) to induce tumor development. In the −Se and ++Se groups, the number of tumors was significantly lower in GPx2-KO than in respective WT mice. On the +Se diet, the number of dysplastic crypts was reduced in GPx2-KO mice. This may be explained by more basal and AOM-induced apoptotic cell death in GPx2-KO mice that eliminates damaged or pre-malignant epithelial cells. In WT dysplastic crypts GPx2 was up-regulated in comparison to normal crypts which might be an attempt to suppress apoptosis. In contrast, in the +Se groups tumor numbers were similar in both genotypes but tumor size was larger in GPx2-KO mice. The latter was associated with an inflammatory and tumor-promoting environment as obvious from infiltrated inflammatory cells in the intestinal mucosa of GPx2-KO mice even without any treatment and characterized as low-grade inflammation. In WT mice the number of tumors tended to be lowest in +Se compared to −Se and ++Se feeding indicating that selenium might delay tumorigenesis only in the adequate status. In conclusion, the role of GPx2 and presumably also of selenium depends on the cancer stage and obviously on the involvement of inflammation.     

A Thr94Ala mutation in human liver fatty acid-binding protein contributes to reduced hepatic glycogenolysis and blunted elevation of plasma glucose levels in lipid-exposed subjects

Liver fatty acid-binding protein (L-FABP) is a highly conserved key factor in lipid metabolism. Amino acid replacements in L-FABP might alter its function and thereby affect glucose metabolism in lipid-exposed subjects, as indicated by studies in L-FABP knockout mice. Amino acid replacements in L-FABP were investigated in a cohort of 1,453 Caucasian subjects. Endogenous glucose production (EGP), gluconeogenesis, and glycogenolysis were measured in healthy carriers of the only common Thr(94)-to-Ala amino acid replacement (Ala/Ala(94)) vs. age-, sex-, and BMI-matched wild-type (Thr/Thr(94)) controls at baseline and after 320-min lipid/heparin-somatostatin-insulin-glucagon clamps (n = 18). Whole body glucose disposal was further investigated (subset; n = 13) using euglycemic-hyperinsulinemic clamps without and with lipid/heparin infusion. In the entire cohort, the only common Ala/Ala(94) mutation was significantly associated with reduced body weight, which is in agreement with a previous report. In lipid-exposed, individually matched subjects there was a genotype vs. lipid-treatment interaction for EGP (P = 0.009) driven mainly by reduced glycogenolysis in Ala/Ala(94) carriers (0.46 +/- 0.05 vs. 0.59 +/- 0.05 mgxkg(-1)xmin(-1), P = 0.013). The lipid-induced elevation of plasma glucose levels was smaller in Ala/Ala(94) carriers compared with wild types (P < 0.0001). Whole body glucose disposal was not different between lipid-exposed L-FABP genotypes. In summary, the Ala/Ala(94)-mutation contributed significantly to reduced glycogenolysis and less severe hyperglycemia in lipid-exposed humans and was further associated with reduced body weight in a large cohort. Data clearly show that investigation of L-FABP phenotypes in the basal overnight-fasted state yielded incomplete information, and a challenge test was essential to detect phenotypical differences in glucose metabolism between L-FABP genotypes.     

Quantifying the improvement of surrogate indices of hepatic insulin resistance using complex measurement techniques

We evaluated the ability of simple and complex surrogate-indices to identify individuals from an overweight/obese cohort with hepatic insulin-resistance (HEP-IR). Five indices, one previously defined and four newly generated through step-wise linear regression, were created against a single-cohort sample of 77 extensively characterised participants with the metabolic syndrome (age 55.6 ± 1.0 years, BMI 31.5 ± 0.4 kg/m(2); 30 males). HEP-IR was defined by measuring endogenous-glucose-production (EGP) with [6-6(2)H(2)] glucose during fasting and euglycemic-hyperinsulinemic clamps and expressed as EGP*fasting plasma insulin. Complex measures were incorporated into the model, including various non-standard biomarkers and the measurement of body-fat distribution and liver-fat, to further improve the predictive capability of the index. Validation was performed against a data set of the same subjects after an isoenergetic dietary intervention (4 arms, diets varying in protein and fiber content versus control). All five indices produced comparable prediction of HEP-IR, explaining 39-56% of the variance, depending on regression variable combination. The validation of the regression equations showed little variation between the different proposed indices (r(2) = 27-32%) on a matched dataset. New complex indices encompassing advanced measurement techniques offered an improved correlation (r = 0.75, P<0.001). However, when validated against the alternative dataset all indices performed comparably with the standard homeostasis model assessment for insulin resistance (HOMA-IR) (r = 0.54, P<0.001). Thus, simple estimates of HEP-IR performed comparable to more complex indices and could be an efficient and cost effective approach in large epidemiological investigations.     

Fatty acids differentially modify the expression of urokinase type plasminogen activator receptor in monocytes

The urokinase plasminogen activator system with its receptor uPAR contributes to the migratory potential of macrophages, a key event in atherosclerosis. We here investigated whether free fatty acids (FFA) modify the expression for uPAR in the PMA-differentiated human monocyte/macrophage-like cell line U937. Two hundred micromolar palmitate induced a threefold increase of the uPAR mRNA expression. Although the mono- and polyunsaturated fatty acids oleate and linoleate also stimulated uPAR expression, oleate had a significantly lower effect than palmitate. The observed effects were time and dose dependent. Inhibition of PKC-and ERK-pathways resulted in a strong down-regulation of basal uPAR expression whereas the FFA induced up-regulation remained unchanged. In contrast, FFA induced uPAR up-regulation was abolished by the specific inhibition of p38 MAPK. In conclusion we demonstrate that uPAR expression in human monocytes/macrophages is differentially stimulated by FFA. These effects are partially mediated by the p38 MAP-kinase signaling pathway.     

Biochemical polymorphisms in South African freshwater fish. Isoenzyme patterns in fish of the families Cyprinidae and Salmonidae

Isoenzyme patterns were studied in local populations of the carp (Cyprinus carpio) and the bream (Sarotherodon mossambicus) of the Cyprinid family, and in the trout (Salmo giardneri) of the family Salmonidae. Homogenates of heart muscle extracts were used in the identification of PGI, NADP-IDH, PGM and 6-PGD. Polymorphisms found and gene frequencies obtained are discussed separately for each enzyme and species or population. In the bream, variation was found only at the PGI locus. In the carp only the PGM locus was polymorphic whereas both PGM and IDH showed variation in the trout. The variation at the PGM locus in the trout cannot support the three locus model suggested elsewhere and clearly indicates a single locus for the monomeric enzyme. The large variety of NADP-IDH types in trout not only illucidates the complexity of this locus but confirms a disomic mode of inheritance. Genetic differences in the trout populations could be related to possible advantages for management purposes.