Plasma leptin level and its relationship with body composition in hemodialysis patients

Leptin is a newly found hormone secreted by adipocytes that regulates food intake, thermogenesis, and body fat. We measured plasma leptin levels in 103 patients with chronic renal failure treated by hemodialysis and 167 age- and gender-matched healthy control subjects to examine the impact of renal failure on plasma leptin levels and the influence of leptin on body composition measured by dual-energy X-ray absorptiometry. Hemodialysis patients showed a significant decrease in both body fat mass and lean body mass compared with those of the control subjects. Plasma leptin was significantly elevated in the hemodialysis group over the controls. In both groups, leptin was higher in female than male subjects, and it correlated positively with percent body fat. The subjects were divided into six categories according to percent body fat, and plasma leptin levels were compared between the two groups in the same category. Leptin of hemodialysis patients was significantly higher than that of the control subjects in the percent body fat categories of 30 or greater, whereas there was no statistically significant difference in leptin concentrations in the lower percent body fat categories. This was also true in the comparison in each gender, and leptin levels in female subjects showed a more remarkable difference between the hemodialysis and control groups in obese categories. Multiple regression analysis in all subjects indicated that plasma leptin levels were independently affected by percent body fat, plasma insulin concentration, gender, and renal failure. The positive impact of renal failure on leptin remained significant in the subjects with percent body fat of 30 or greater in the multiple regression model, whereas it was no longer significant in the remaining lean subjects. In multiple regression analysis of factors affecting fat mass index and lean mass index, leptin level was selectively associated with fat mass index, but not with lean mass index, regardless of percent body fat ranges. These results indicate that renal failure is an important factor affecting plasma leptin levels, especially in obese female subjects, and that hyperleptinemia was closely related to fat mass but not to lean body mass in hemodialysis patients.     

“Vinylogs” and “Acetylenylogs” of β-Adrenergic Agents

Vinylogous (Groups III and V ) and acetylenologous (Group IV ) analogs of the classical β-adrenergic agents — stimulants and blockers — were prepared in order to evaluate the effect of degree of saturation, position of unsaturation and rigidity of the chain linking the aromatic ring and the amino containing functional group on biological activity. Derivatives from Group III , which represent 4-aryl-3-butenyl-2-ol-amine analogs of Group II , retained β₁-adrenoceptor antagonist activity albeit substantially less potent (50–200-fold) than that possessed by their aryloxy counterparts. Consistent with the SAR for Group II compounds, substitution at position 2 of the aromatic ring yielded the most potent antagonists ( 5a, 5d, 5g ), with K_B's ranging from 73–93 nM while 3,4-dichloro substitution ( 5e ) markedly reduced antagonist potency (K_B = 2,400 nM). Agonist activity was also noted for 5b and 5d , suggesting that these compounds may be best classified as partial agonists. Representatives from Groups IV and V were inactive as antagonists at the β₁-adrenoceptor confirming the importance of the spatial relationship between the hydroxyl and the amino nitrogen.     

SPARC, an extracellular matrix glycoprotein containing the follistatin module, is expressed by astrocytes in synaptic enriched regions of the adult brain

Although extracellular matrix (ECM) glycoproteins play important roles in neural development, their levels are generally believed to decrease in the adult brain. Immunohistochemical analysis indicates that the anti-adhesive ECM glycoprotein SPARC/osteonectin, which contains a follistatin ‘module’, is expressed in the adult rabbit nervous system. In the cerebellum, SPARC is present in Bergmann glia, with a strong signal along their radial fibres. SPARC, while enriched in membrane fractions, is not a transmembrane protein. In the hippocampus, colocalization of SPARC is observed in cells which express the astrocytic marker GFAP. The expression of SPARC by a subset of astrocytes, particularly in synaptic enriched areas, suggests a continuing role for the ECM in the adult brain.     

An analysis of astrocytic cell lines with different abilities to promote axon growth

The adult mammalian central nervous system (CNS) lacks the capacity to support axonal regeneration. There is increasing evidence to suggest that astrocytes, the major glial population in the CNS, may possess both axon-growth promoting and axon-growth inhibitory properties and the latter may contribute to the poor regenerative capacity of the CNS. In order to examine the molecular differences between axon-growth permissive and axon-growth inhibitory astrocytes, a panel of astrocyte cell lines exhibiting a range of axon-growth promoting properties was generated and analysed. No clear correlation was found between the axon-growth promoting properties of these astrocyte cell lines with: (i) the expression of known neurite-outgrowth promoting molecules such as laminin, fibronectin andN-cadherin; (ii) the expression of known inhibitory molecules such tenascin and chondroitin sulphate proteoglycan; (iii) plasminogen activator and plasminogen activator inhibitor activity; and (iv) growth cone collapsing activity. EM studies on aggregates formed from astrocyte cell lines, however, revealed the presence of an abundance of extracellular matrix material associated with the more inhibitory astrocyte cell lines. When matrix deposited by astrocyte cell lines was assessed for axon-growth promoting activity, matrix from permissive lines was found to be a good substrate, whereas matrix from the inhibitory astrocyte lines was a poor substrate for neuritic growth. Our findings, taken together, suggest that the functional differences between the permissive and the inhibitory astrocyte cell lines reside largely with the ECM.     

A mild form of captopril-induced pemphigus

We describe a mild form of drug-induced pemphigus in a woman with essential arterial hypertension treated with captopril. Complete recovery was observed three weeks after the therapy had been discontinued.     

缺氧缺血性脑病新生鼠补钙前后脑细胞,红细胞内外钙的变化

为了观察一般剂量补钙对缺氧缺血性脑病（ＨＩＥ）脑细胞和红细胞内外钙变化的影响，以探讨ＨＩＥ时补钙是否增加脑细胞钙超载，用ＨＩＥ新生动物模型进行了实验研究，结果表明：（１）缺氧缺血时红细胞、脑细胞及脑组织出现钙积聚；（２）补钙后，血浆总钙浓度明显升高，而脑细胞、脑组织及红细胞钙积聚并未加重；（３）血浆总钙浓度与脑细胞或红细胞胞浆游离钙离子浓度无相关关系。提示：（１）ＨＩＥ时钙内流可能是全身性的；（２）对ＨＩＥ并低钙血症患儿吸氧后一般剂量补钙可能是安全的。     

Family relationships and the development of social competence in adolescence

Abstract Resilient adolescents are notable for their social competence, which enables them to form and maintain close relationships. The evidence is that adolescents' social competence is derived from their experience of close relationships within their family. On the basis of structured interviews, adolescents' working models of attachments can be categorized into secure, dismissive, or pre-occupied. These attachment styles are associated with very divergent beliefs about the self and others, with differing patterns of emotion regulation and with differing risk profiles for maladjustment. Parenting styles and family relationships appear to have considerable influence on attachment behaviour. Further evidence for the importance of the family comes from research on ego development. Family level behavioural patterns have been discerned from family research interviews which are associated with stagnation or advancement in ego development during adolescence. Though the results suggest causal connections, the direction of effects is far from clear. Longitudinal research underpins the importance of childhood temperament as a contributing factor to the quality of the family environment that the child and then adolescent experiences.     

DNA-Methylierung von monohalogenierten Methanen in F-344 Ratten

Monohalogenated methanes (methyl chloride, methyl bromide and methyl iodide) are mutagenic and carcinogenic. The possible mechanism of these effects, DNA methylation, was studied. DNA adducts from orgnas of F344 rats exposed to these chemicals were separated and identified with high performance liquid chromatography (HPLC) and gaschro-matography/massspectrometry (GC/ MS). DNA adducts, 7-methylguanine (7-MeG) and O⁶-Methylguanine(0⁸-MeG), incorporation of¹⁴C into de novo synthesis of nucleobases could be observed in enzymatic DNA hydrolysates by HPLC and determination of the radioactivity in the fractions. The formation of DNA add,ue,ts in the studied organs was only quantitatively different. The formation of O⁶-MeG was further pioved by analysing the acidic hydrolysates using HPLC with non-radioactive O⁶MeG as internal standard. 7-MeG and 3-MeA were identified with GC/MS analysis.