Long-term effects of physiologic concentrations of dexamethasone on human bone-derived cells

Bone cells derived from human trabecular explants display osteoblastic features. We examined the modulation of alkaline phosphatase activity and cAMP production as the result of exposing trabecular explants to physiologic concentrations of dexamethasone for 4 weeks during cellular outgrowth and subculture. Cells treated with dexamethasone were observed to grow generally more slowly than control cells. Cells appeared larger and more polygonal, and staining for alkaline phosphatase was more intense in the dexamethasone-exposed cultures. There was a progressive increase in cellular PTH responsiveness with increasing duration of exposure of cells to dexamethasone. Cells grown for 6 weeks in 3 x 10(-8) M dexamethasone had a 10-fold increase in PTH-stimulated cyclic AMP accumulation. Dexamethasone-treated cells also had a significantly increased alkaline phosphatase activity. 1,25-(OH)2D3-stimulated alkaline phosphatase activity was increased approximately 20-fold. cAMP responses were significantly increased to PTH (21.7-fold), PGE1 (2.67-fold), and forskolin (4.81-fold), but not to cholera toxin. Dexamethasone-treated cells also had a mean decrease in 1,25-(OH)2D3-stimulated osteocalcin production to 26.2% of control values (p less than 0.001). Hydrocortisone treatment gave rise to similar effects but of smaller magnitude than those of dexamethasone. Testosterone did not have a significant effect on alkaline phosphatase activity or cAMP production. Skin fibroblasts showed a significant enhancement of alkaline phosphatase activity in response to dexamethasone, but of a much smaller magnitude than in bone cells. The phenotypic changes induced by long-term culture in dexamethasone are consistent with the promotion of a more differentiated osteoblastic phenotype.     

番荔枝开花生物学与人工授粉研究

对三年生番荔枝（Ancnona squamosa L.)实生树的开花生物学和人工授粉进行了研究并发现；番荔枝的花有两荔异熟现象，人工授粉能提高座果率，简便而有效的方法是用毛笔直接从树上花药自然裂开的花上聚花粉并立即授在花药没裂开的花上，授粉后两周的座果率达87．9％，授 在花药裂开的花上，座果率为5．3％，与对照照座果率4．4％没有区别，说明花药裂开柱头容受性完全消失，花药裂开时间与品种特有关，目前，广东栽培的番荔枝分为花药早上裂开和傍开两种类型，这两种类型的不同品种之间授粉也能提高座果率，授粉后两周的座果率为83．3％。说明花裂开关12h柱头容受性仍完全正常。     

Desferrithiocin is an effective iron chelator in vivo and in vitro but ferrithiocin is toxic

The efficacy and toxicity of the siderophore desferrithiocin (DFT), which has shown potential application in iron chelation therapy, were assessed in vivo and in vitro. DFT was evaluated in vivo in two ways: firstly, by measuring the effect of a single dose of DFT (10-100 mg/kg) on 59Fe excretion in iron-loaded rats labelled with 59Fe; and secondly, by examining the effect of the daily oral administration for 2 weeks of DFT (10-25 mg/kg/d) on the growing rat. DFT and its ferric complex, ferrithiocin (FT), were assessed in vitro from their effects on transferrin and iron uptake and mobilization from rat hepatocytes in culture using transferrin doubly labelled with 125I and 59Fe. Both oral and subcutaneous DFT were highly effective in promoting iron excretion in vivo, but showed evidence of toxicity after oral administration for 2 weeks at 25 mg/kg/d. In addition, DFT was much more effective than desferrioxamine or pyridoxal isonicotinyl hydrazone in reducing hepatocyte iron in vitro. However, FT was cytotoxic, causing membrane disruption and release of intracellular aspartate aminotransferase. It was concluded that DFT should not be considered for chronic iron chelation therapy without extensive further evaluation.     

Electrophysiological properties of neurons in the rostral ventrolateral medulla of normotensive and spontaneously hypertensive rats

Single unit activities were recorded from the rostral ventrolateral medulla (RVL) of pentobarbital-anesthetized normotensive Wistar Kyoto rats (WKY) and spontaneously hypertensive rats (SHR). Throughout the recording period, arterial blood pressures of WKY (mean arterial pressure, MAP = 103.1 mm Hg) and SHR (MAP = 159.2 mm Hg) remained stable at the respective basal levels. The units recorded in this study were all spontaneously active and cardiac-locked. Two types of discharge patterns, namely single and double discharges, were identified. These single and double discharge units were found to distribute randomly in RVL. In WKY, 92.6% of RVL neurons exhibited single discharges whereas in SHR, the majority (57%) of RVL neurons exhibited double discharges. The mean firing rate of single discharge units in RVL of SHR was significantly higher than that of WKY, whereas the mean firing rate of double discharge units in WKY was similar to that of SHR. About half of the units studied were also tested for antidromic collision; all units tested could be antidromically activated from the intermediolateral column (IML) of the thoracic spinal cord and the lowest threshold sites were consistently localized within IML. In both groups of rats, the axonal conduction velocity of RVL neurons showed a bimodal distribution viz. the fast and slow conducting axons. The mean conduction velocities of each of these two groups of neurons in WKY and SHR were similar. Most of the double discharge units in WKY and SHR belonged to the fast conducting type.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effects of aerobic conditioning and/or caloric restriction in overweight men and women

The purpose of this study was to compare the effects of exercise and/or caloric restriction for 12 wk on body composition, maximal aerobic power (VO2max), and serum lipids and lipoproteins in overweight individuals. Forty-eight males and 48 females (means age = 36.6 yr), 120-140% of ideal body weight, were randomly assigned to groups (N = 12 each) of diet-exercise (DE), diet (D), exercise (E), and sedentary control (C). The dietary regimen consisted of 1,200 kcal X d-1, while exercise consisted of 5 d X wk-1 of 30 min of walk/running. For the males, body weight (BW) and fat weight loss in the DE group (-11.8 and 23%, respectively) were significantly greater than in the D group (-9.1 and -18%), with both groups significantly greater than for E and C. In the females, BW and fat weight loss for DE (-10.4 and -24%) were significantly greater than for D (-7.8 and -20%), with both groups significantly greater than E and C. Both DE and D males and females had a decrease in fat-free weight of -4.5 and -2.4%, respectively. In both sexes, the increase in VO2max-BW (ml X kg -1 X min-1) in DE (25%) was significantly greater than for E (15%), D (11%), and C (0%), with differences between E and D nonsignificant. However, increases in absolute VO2max (1 X min-1) and VO2max-fat-free weight (ml X kg-1 X min-1) were similar (P greater than 0.05) for DE and E (14%) but significantly greater compared to D and C (2%).(ABSTRACT TRUNCATED AT 250 WORDS)     

运动性疲劳中医肾虚证的辨证分型及其诊断标准

目的：阐明运动性疲劳中医肾虚证的主要证候及辨证标准。 方法：于2003-07／2004-01选择湖南省水上运动训练基地的皮划赛艇运动员和省体工大队的田径运动员共199名为研究对象。将中医辨证理论方法与流行病学调研疗法有机结合，统一诊断标准和资料处理方法，分析肾虚各证候构成比，进行聚类分析，观察单一症状出现频次、症状组合出现频次。 结果：纳入受试对象199名，均进入结果分析。①肾虚常见证候有腰脊酸痛，头晕目眩，精神疲倦，四肢乏力，胫膝酸软，气短自汗，五心烦热，口干少津，畏寒肢冷，小便清长，夜尿频多，少寐多梦。②肾虚各证候构成比：肾气虚（51．26％）、肾阴阳两虚（37.69％）、肾阳虚（6.53％）、肾阴虚（4．52％）。③聚类分析：第一类为腰脊酸痛，精神疲倦，四肢乏力，气短自汗；第二类为头晕目眩，胫膝酸软，畏寒肢冷，小便清长，夜尿频多；第三类为五心烦热，口干少津；第四类为少寐多梦。④参与组合频次大于50％的症状主要是：精神疲倦、四肢乏力、腰脊酸痛、头晕目眩、气短，这5个症状也是单个症状频次大于80％的。 结论：运动性疲劳中医肾虚证的常见证候为肾气虚、肾阴阳两虚、肾阳虚、肾阴虚。而肾气虚是运：动性疲劳中医肾虚的主要证候。精神疲倦、四肢乏力、腰脊酸痛、头晕目眩、气短这5个症状可以作为运动性疲劳肾气虚辨证标准中的主要症状。     

复方珍珠口服液的临床研究

复方珍珠口服液由珍珠、黄精、枸杞子、何首乌、熟地黄等多种补益中药材组成,提取制备而成的口服液,经临床144例验证表明,该口服液具有滋补肝肾、养血活颜、延缓衰老的功能。对肝肾两虚、头晕眼花、健忘、夜尿、病后体弱,高胆固醇、高血压症有较好的疗效;其中治疗肾虚证总有效率为95.83％,治疗高血压症总有效率为80.9％,治疗高胆固醇总有效率为71.47％。