Impaired body calcium metabolism with low bone density and compensatory colonic calcium absorption in cecectomized rats

An earlier study reported that cecal calcium absorption contributes less than 10% of total calcium absorbed by the intestine, although the cecum has the highest calcium transport rate compared with other intestinal segments. Thus, the physiological significance of the cecum pertaining to body calcium metabolism remains elusive. Herein, a 4-wk calcium balance study in cecectomized rats revealed an increase in fecal calcium loss with marked decreases in fractional calcium absorption and urinary calcium excretion only in the early days post-operation, suggesting the presence of a compensatory mechanism to minimize intestinal calcium wasting. Further investigation in cecectomized rats showed that active calcium transport was enhanced in the proximal colon but not in the small intestine, whereas passive calcium transport along the whole intestine was unaltered. Since apical exposure to calcium-sensing receptor (CaSR) agonists similarly increased proximal colonic calcium transport, activation of apical CaSR in colonic epithelial cells could have been involved in this hyperabsorption. Calcium transporter genes, i.e., TRPV6 and calbindin-D(9k), were also upregulated in proximal colonic epithelial cells. Surprisingly, elevated serum parathyroid hormone levels and hyperphosphatemia were evident in cecectomized rats despite normal plasma calcium levels, suggesting that colonic compensation alone might be insufficient to maintain normocalcemia. Thus, massive bone loss occurred in both cortical and trabecular sites, including lumbar vertebrae, femora, and tibiae. The presence of compensatory colonic calcium hyperabsorption with pervasive osteopenia in cecectomized rats therefore corroborates that the cecum is extremely crucial for body calcium homeostasis.     

白藜芦醇对成年期追赶生长大鼠体成分的影响及机制

目的:观察白藜芦醇对成年期追赶生长大鼠体成分的影响及可能机制。方法:8周龄雄性 SD 大鼠分为6组(共2个时间点),即4周时间点3组:正常饮食4周 (NC4)组、热卡限制4周(R4)组,热卡限制同时白藜芦醇治疗(R4E)组;12周时间点3组:正常饮食12周(NC12)组,追赶生长(CUG)组,追赶生长白藜芦醇治疗(CUGE)组。每组含6只大鼠,白藜芦醇用生理盐水配制成一定浓度悬浊液,按100 mg/(kg·d)剂量予实验动物灌胃治疗。实验第4周、12周检测体重、躯干和全身的肌肉及脂肪含量、躯干与全身脂肪比例,实验第12周检测骨骼肌与附睾脂肪组织SIRT1的表达,附睾脂肪组织PPARγ的表达。结果:与NC12组相比,CUG组躯干及全身的脂肪含量、躯干与全身脂肪比例、附睾脂肪组织PPARγ的表达均明显升高(P＜0.05),肌肉含量、骨骼肌与附睾脂肪组织SIRT1的表达显著降低(P＜0.05或P＜0.01);与CUG组相比,经白藜芦醇干预后的CUGE组全身的脂肪含量、躯干与全身脂肪比例、附睾脂肪组织PPARγ的表达均明显降低(P＜0.05),肌肉含量、骨骼肌与附睾脂肪组织SIRT1的表达较CUG组显著提高(P＜0.05)。结论:白藜芦醇降低成年期追赶生长大鼠体脂含量,增加肌肉含量,改善腹部脂肪堆积,其机制可能与增加骨骼肌及内脏脂肪组织SIRT1表达,抑制内脏脂肪PPARγ的表达有关。     

Effect of alcohols on the structure and function of D-amino-acid oxidase.

The absorption spectrum of D-amino-acid oxidase (D-amino-acid:oxygen oxidoreductase (deaminating), EC 1.4.3.3) was significantly perturbed by various alcohols; typical fine structures were observed in the visible absorption bands, accompanied by blue shifts of the peaks. Both fluorescence intensity and fluorescence polarization were increased upon the addition of alcohols, indicating that the coenzyme is not liberated from the apoenzyme but the hydrophobicity of the environment of the enzyme-bound flavin is increased. Upon the addition of alcohols, the circular dichroism of the enzyme was markedly modified in the visible and near-ultraviolet regions, while that of the apoenzyme in the near- and far-ultraviolet regions was scarcely modified, indicating a change in the interaction between the flavin coenzyme and protein. Both the apparent maximal velocity and the apparent Michaelis constant of the enzyme were increased by the addition of alcohols. The presence of alcohols tends to dissociate the dimer of this enzyme into the monomer, but the dissociation does not fully explain the increase in the maximal velocity of the enzyme by alcohols, because the increase in the maximal velocity caused by alcohols is larger than that expected from the dissociation. Since the rate of formation of the purple intermediate was decreased by alcohols in both the dimer and the monomer, the increase in the maximal velocity could be ascribed to an increase in the rate of dissociation of the enzyme-product complex. This increase could be ascribed to the protein conformational change, which is probably provoked by combination of alcohols with the enzyme at a locus other than that for substrate binding.     

Effect of hemorrhagic shock on gut barrier function and expression of stress-related genes in normal and gnotobiotic mice

We sought to determine whether gut-derived microbial factors influence the hepatic or intestinal inflammatory response to hemorrhagic shock and resuscitation (HS/R). Conventional and gnotobiotic mice contaminated with a defined microbiota without gram-negative bacteria were subjected to either a sham procedure or HS/R. Tissue samples were obtained 4 h later for assessing ileal mucosal permeability to FITC dextran and hepatic and ileal mucosal steady-state IL-6, inducible nitric oxide synthase (iNOS), cyclooxygenase (COX)-2, and TNF mRNA levels. Whereas HS/R significantly increased ileal mucosal permeability in conventional mice, this effect was not apparent in gnotobiotic animals. HS/R markedly increased hepatic mRNA levels for several proinflammatory genes in both conventional and gnotobiotic mice. HS/R increased ileal mucosal IL-6 and COX-2 mRNA expression in conventional but not gnotobiotic mice. If gnotobiotic mice were contaminated with Escherichia coli C25, HS/R increased ileal mucosal permeability and upregulated expression of IL-6 and COX-2. These data support the view that the hepatic inflammatory response to HS/R is largely independent of the presence of potentially pathogenic gram-negative bacteria colonizing the gut, whereas the local mucosal response to HS/R is profoundly influenced by the microbial ecology within the lumen during and shortly after the period of hemorrhage.     

Hypothalamic amenorrhea in runners of normal body composition

Three amenorrheic runners of normal body weight, in whom organic disease had been excluded, were found to exhibit: (1) normal body composition, (2) low baseline concentrations of serum LH and normal concentrations of FSH, (3) normal to hyper-responsiveness of LH and FSH to GnRH testing, and (4) normal and possibly increased frequency of LH pulsations. In one of the 3 runners, the administration of naloxone was followed by a pronounced increase in the amplitude of the LH pulsations.     

Effect of dietary restriction and/or exercise on 23-h metabolic rate and body composition in female rats.

This study examined the effects of three levels of dietary intake [ad libitum fed (AL), moderately severe (MSR), and severe restriction (SR)] and two levels of exercise [cage confinement (CC) and exercise training (E)] on 23-h resting metabolic rate (RMR) and body composition in 47 female Sprague-Dawley rats. At the end of the 9-wk study, the MSR and SR groups weighed approximately 81 and 61%, respectively, of the AL-CC group. RMR was depressed for the MSR and SR groups compared with the AL-CC group. This was true whether expressed on an absolute (ml/min) or relative (ml.min-1.kg-0.75) basis. On a relative basis, which accounts for changes caused by weight loss alone, the RMR decreased by approximately 12 and 19%, respectively, for the MSR and SR groups compared with the AL-CC group. Although E resulted in significant differences in fat mass, percent fat, percent water, and heart mass between the AL groups, there were no significant differences between E and CC groups at either the MSR or SR level of dietary intake for any of the variables measured (i.e., body composition, muscle mass, RMR). Thus E does not appear to affect the composition of lost weight or RMR during diet-induced weight loss for female rats of normal weight.     

Effect of polyethylene glycol and sugar alcohols on soybean somatic embryo germination and conversion

The effect of different vitamins and inorganic micronutrients on callus growth and the induction and proliferation of somatic embryos from young mature, fully expanded leaves of chilli pepper (Capsicum annuum L.) was investigated. Explants were cultured on a solid Murashige and Skoog (MS) medium supplemented with 8% (w/v) sucrose, 12.9 M 6-benzyladenine, 9 M 2,4-dichlorophenoxyacetic acid and 0.5 mg l^–1 thiamin.HCl in various combinations of eleven different vitamins. Alternatively, explants were cultured onto a solid medium containing MS macro- and micronutrients except for the salts of Mn, Zn, I, Cu and Co which were added at either the standard MS concentration or at a tenfold increased (Cu, Co) or decreased (Mn, Zn, I) concentration. The results indicated that somatic embryogenesis from pepper leaves is favoured by the addition of nicotinic acid to the culture medium and the increase of copper concentration (an average induction of 70.2 globular embryos/mm² of explant surface, 9.2% higher than control), without reducing embryo maturation and germination.     

Effect of long-term somatotropin treatment on body composition and life span in aging obese Zucker rats

The objective of this work was to test the hypothesis that a somatotropin (STH)-induced reduction in body fat would prolong the life span of the obese Zucker rat. Two experiments were conducted. In the first experiment, male and female, lean and obese Zucker rats were treated with STH (0 or 2 mg/d bovine STH) for 4 weeks, beginning at 7 months of age. Across phenotypes, STH treatment increased the growth rate by 159%, muscle weights by 14%, and circulating insulin-like growth factor (IGF)-1 by 23%, and decreased carcass fat by 21% (P < 0.05). The second experiment was a longevity trial to determine whether these changes in body composition would increase the life span of the obese rat. Beginning at 7 months of age, individually housed, male and female, lean and obese rats were assigned to daily STH treatments (0 or 2 mg/d). Rats were monitored daily, and sick or moribund rats were euthanized and necropsied to determine existing pathologies. The average life span of the lean rats was 661 days and was unaffected by STH treatment (639 days, NS) or gender. Average life span of the vehicle-injected obese rats (435 days) was less than that of the lean group (P < 0.001). STH treatment of the obese rats resulted in a further reduction of life span (349 days, P < 0.02). The predominant pathology observed across the treatment groups was renal disease, characterized by progressive glomerulonephropathy. Thus, although exogenous STH was able to reduce carcass lipid and to increase lean tissue mass in obese rats, there was no improvement in longevity. In contrast to the hypothesis, STH actually reduced the life span of the obese rat. It is likely that STH treatment accelerated the development of progressive glomerulonephropathy in the obese rat.     

Effects of nicotine on body weight, food consumption and body composition in male rats

The present study examined the effects of nicotine administration and cessation on body weight, food consumption, and body composition in rats. Administration of nicotine was associated with attenuated body weight gains and cessation was associated with accelerated body weight gains. Changes in fat composition paralleled changes in body weight, whereas changes in body water and protein did not. These results suggest that nicotine administration decreases body weight through its effects on fat stores in the body. After cessation of nicotine, body fat rapidly approached levels of control animals.     

Effects of soybean agglutinin on body composition and organ weights in rats

An experiment was conducted to assess the effect of soybean agglutinin dosage level on growth, body composition, plasma lipids, glucose, urea nitrogen content and aminotransferase activities in rats. Male and female rats (n=60) weaned at 19 d were given a dose of 0, 3.5, 7.0, 10.5, or 14.0 mg soybean agglutinin by gastric infusion once daily for 10 days. With increasing doses of soybean agglutinin, body weight, lipid content of carcass, spleen and kidneys relative dry weights decreased, while small intestine and pancreatic weight, the contents of urea nitrogen and triglyceride, and the activities of aspartate aminotransferase linearly increased in plasma. Though soybean agglutinin decreased plasma insulin content, changes in plasma glucose content due to soybean agglutinin were not detected. It is suggested that dietary soybean agglutinin may affect the secretion of other hormones besides insulin, which modulate blood glucose reserves. In conclusion, consumption of soybean agglutinin resulted in a depletion of lipid and an overgrowth of small intestine and pancreas in rats. Meanwhile, poor growth of spleen and kidneys was observed in the soybean agglutinin-fed rats.     

Effect of sequential bleeding on body weight gain in rats.

Monthly withdrawal of a total of 1.25--2.0 ml of blood from young, mature, inbred Fischer 344 rats produced no noticeable effects on common hematologic parameters, but it did cause a decrease in the rate of body weight gain. The difference in body weight between rats bled and not bled was evident 3 weeks after the study began, and the difference persisted throughout the 23-week study.     

蜜蜂肠道菌群结构功能研究进展

在长期的共同进化中,肠道菌群与其宿主形成了紧密的联系,为宿主提供了许多有益的作用。作为一种社会性昆虫,蜜蜂的生活习性为其肠道菌群提供了良好而稳定的传播途径,因此,蜜蜂与其肠道菌群形成了一种紧密的互惠互利共生关系。近年来,随着对蜜蜂肠道菌群了解的不断加深,对蜜蜂肠道菌群功能的研究也不断深入,大量研究表明蜜蜂的肠道菌群在宿主食物的消化代谢、宿主免疫的激活和抵抗致病菌、调节宿主生理等方面都有着重要的作用,同时破坏肠道菌群的稳定对蜜蜂的健康有着明显的负面影响。本文对近年来西方蜜蜂肠道菌群功能研究进行了总结,旨在为进一步深入探索蜜蜂肠道菌群与其宿主的相互作用及在养蜂生产上应用肠道菌群防控疾病提供参考。     

Influence of red pepper and capsaicin on body composition and lipogenesis in rats

Inclusion of red pepper or its active principle ‘capsaicin’ in the diet led to a lowering of total lipids, particularly triglycerides in the liver. The total body fat was lowered in animals fed red pepper or capsaicin but not in animals fed paprika powder which had negligible capsaicin content. Hyperlipogensis and hypertriglyceridemia caused by fructose feeding were significantly were decreased in capsaicin-fed animals. Activities of the key lipogenic enzymes were reduced as reflected by decreased lipogenesis.     

Pharmacological properties of imidazole. 2. Action on the normal body temperature regulation in rats

Rats injected intraperitoneally with imidazole (100 to 400 mg/kg) showed a progressive dose-dependent decrease in rectal temperature. A decrease of 6$\text{°}$C occurred when the imidazole-treated animals were placed in a 4$\text{°}$C environment. In a 23$\text{°}$C environment, the rectal temperature declined about 2$\text{°}$C. The results show that imidazole induces a decline in body temperature in non-febrile rats, possibly due to an action on hipothalamic calcium levels.     

Determination of monosaccharides and sugar alcohols in tissues from diabetic rats by high-performance liquid chromatography with pulsed amperometric detection.

A sensitive and simple high-performance liquid chromatographic method has been developed to determine the concentration of monosaccharides and sugar alcohols in animal tissues. Five neutral monosaccharides (D-glucose, D-galactose, D-mannose, D-fructose, and D-ribose) and three neutral sugar alcohols (myo-inositol, glycerol, and D-sorbitol) predominate in the renal cortices and sciatic nerves of rats. These monosaccharides and sugar alcohols were extracted with distilled water, purified by deproteinization with ethanol, a Sep-Pak C18 cartridge, and columns of Dowex 50W-X8 and Amberlite CG-400, then separated on Ca2+ and Pb2+ cation-exchange columns, eluted with deionized distilled water at 80 degrees C, and detected using integrated pulsed amperometry. About 10 pmol of each sugar was detectable with a signal-to-noise ratio of 10:1. D-Glucose, D-fructose, D-sorbitol, and D-mannose were higher in both the renal and sciatic tissues of diabetic rats than in those of normal animals. D-Ribose and glycerol were higher in the renal cortex of diabetic animals.