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91.
Effects of Clodronate on Cortical and Trabecular Bone in Ovariectomized Rats on a Low Calcium Diet 总被引:5,自引:0,他引:5
T. S. Kaastad O. Reikerås J. E. Madsen S. Narum J. H. Strømme K. J. Obrant L. Nordsletten 《Calcified tissue international》1997,61(2):158-164
The aim of this study was to evaluate the contribution of a low calcium diet to the cortical and trabecular osteoporosis
seen in ovariectomized rats after 7 weeks on a low calcium diet and to investigate the effects of the bisphosphonate clodronate
on this development of osteoporosis. Thirty-six mature, female Wistar rats were randomized into four groups: Ovx−B (bisphosphonate)
and Ovx−C (control) were ovariectomized, and Sham−Ca (low calcium) and Sham+Ca (normal calcium) were sham operated. The first
three groups were fed a low calcium diet (0.01%) and Sham+Ca normal rat chow (Ca 1.1%). The Ovx−B received 10 mg/kg s.c. clodronate
daily for nine weeks, and Ovx−C, Sham−Ca, and Sham+Ca received the same volumes of saline. Bone mineral turnover measured
as 85Sr-uptake was increased in all low calcium groups compared to Sham+Ca. The Sham+Ca femora had higher dry weight and ash weight
than the other groups, and Ovx−C had higher dry weight compared with Ovx−B and Sham−Ca. Calcium content was lower in both
Ovx groups compared to both Sham groups. Magnesium was lower in all groups compared to Sham+Ca and higher in Ovx−B compared
with Ovx−C. In the femoral shaft, Sham+Ca had significantly higher ultimate bending moment, energy absorption, and deflection
compared to the other three groups. Ultimate bending moment was higher in Sham−Ca than in Ovx−C. Stiffness was increased in
both Sham+Ca and Ovx−B compared to Ovx−C. The maximum stress in the femoral midshaft was higher in Sham+Ca than in the other
groups, and higher in Ovx−B than in Ovx−C. Histomorphometry showed increased medullary area in all low calcium groups compared
to Sham+Ca and larger cortical area in Sham+Ca and Ovx−B compared to Ovx−C. Compared to Sham+Ca the trabecular bone volume
was decreased to 30% in Sham−Ca and to 9% in Ovx−C, but was unchanged in Ovx−B. The low calcium diet generally increased bone
mineral turnover and reduced the tibial bone volume. Femoral changes led to a reduction of cortical fracture strength and
maximal stress. Ovariectomy in addition to a low calcium diet reduced femoral strength even more. Daily injections of clodronate
to ovariectomized rats on a low calcium diet increased femoral shaft stiffness and maximum stress, and clodronate preserved
both trabecular and cortical tibial bone volume completely.
Received: 11 June 1996 / Accepted: 5 March 1997 相似文献
92.
用乙二醇法诱导大鼠产生草酸钙结石,用45~Ca示踪测定法了解中草药复方制剂(PESM)对草酸钙结石形成的抑制作用。结果显示,实验组肾脏放射性强度明显减少(实验组3.47±3.52cpm/mg,对照组10.89±14.24cpm/mg)。干肾重量明显下降(实验组306.0±47.0mg,对照组343.1±59.4mg),说明PESM能明显抑制肾脏草酸钙结石的形成。 相似文献
93.
Rat spinal dorsal horn neurons in slice preparations perfused with Ringer solution containing 0.5-1 microM TTX and/or 10-20 mM tetraethylammonium at 29 degrees C, were studied by using a single microelectrode voltage-clamp technique. Slow persistent inward currents were recorded during depolarizing voltage commands to membrane potentials positive to about -40 mV. The inward current was depressed by removing external Ca, or by adding 0.1-0.2 mM Cd, 5 mM Co or 0.1 mM verapamil, and was increased by adding Ba or Bay-K 8644. Substance P (SP) augmented a persistent slow inward Ca-sensitive current in a dose-dependent manner. It is suggested that this effect may be instrumental in generating the SP-evoked slow depolarization, increase in membrane excitability, and the 'bursting' behavior in the immature rat dorsal horn neurons. In addition, in some neurons SP reduced the M-like current, which effect may contribute to, but not explain, generation of the SP-induced slow depolarization. 相似文献
94.
Richard V. Jackson A. Jane Jackson Jeffrey E. Grice Rodney D. Vella 《Clinical and experimental pharmacology & physiology》1989,16(4):257-261
1. The present study investigated the effect of prior administration of nifedipine on AVP-induced ACTH release in seven normal volunteers. Three protocols were used: 20 mg oral nifedipine; 0.14 pressor units intramuscular (i.m.) per kg bodyweight aqueous AVP; oral nifedipine plus i.m. AVP 90 min later. Plasma ACTH and cortisol were measured at intervals for 2.5 h during each test. 2. The mean peak plasma ACTH and cortisol levels and the mean peak changes from basal in these levels were significantly lower in the nifedipine/AVP test than in the AVP alone test. The integrated area under the cortisol time curve was significantly lower for the nifedipine/AVP test than that for the AVP test alone. Nifedipine alone caused no changes in ACTH or cortisol. 3. Acute administration of oral nifedipine caused an inhibition of AVP-stimulated ACTH and cortisol release in normal humans. This effect may be due to blockade of plasma membrane calcium channels normally activated during AVP stimulation of pituitary corticotrophs. 相似文献
95.
M. R. Clements † 《Journal of human nutrition and dietetics》1989,2(2):105-116
A large body of work relating to the occurrence of rickets in UK Asians is reviewed. Several theories of the aetiology of this condition are shown to be untenable: it is not exclusively a function of sunlight deprivation or of darker pigmentation; nor is it simply due to phytate-induced losses of calcium from the gut. Asian rickets, however, is associated with a high consumption of cereals, and experiments with rats have suggested a mechanism. In the absence of adequate vitamin D from sunlight, the low-calcium, high cereal intake of the UK Asian population may induce a state of mild secondary hyperparathyroidism which enhances the destruction of vitamin D and leads to a progressive reduction in vitamin D status and, ultimately, to the development of clinical rickets. 相似文献
96.
High-protein Weight-loss Diets: Are They Safe and Do They Work? A Review of the Experimental and Epidemiologic Data 总被引:6,自引:0,他引:6
Julie Eisenstein M.D. Susan B. Roberts Ph.D. Gerard Dallal Ph.D. Edward Saltzman M.D. 《Nutrition reviews》2002,60(7):189-200
Recommendations for increased consumption of protein are among the most common approaches of popular or fad diets. This review summarizes the effects of dietary protein on satiety, energy intake, thermogenesis, and weight loss, as well as its effect on a variety of health outcomes in adults. In short-term studies, dietary protein modulates energy intake via the sensation of satiety and increases total energy expenditure by increasing the thermic effect of feeding. Whereas these effects did not contribute to weight and fat loss in those studies in which energy intake was fixed, one ad libitum study does suggest that a high-protein diet results in a greater decrease in energy intake, and therefore greater weight and fat loss. In terms of safety, there is little long-term information on the health effects of high-protein diets. From the available data, however, it is evident that the consumption of protein greater than two to three times the U.S. Recommended Daily Allowance contributes to urinary calcium loss and may, in the long term, predispose to bone loss. Caution with these diets is recommended in those individuals who may be predisposed to nephrolithiasis or kidney disease, and particularly in those with diabetes mellitus. 相似文献
97.
Natural history of parathyroid function and calcium metabolism after kidney transplantation: a single-centre study. 总被引:10,自引:4,他引:6
Pieter Evenepoel Kathleen Claes Dirk Kuypers Bart Maes Bert Bammens Yves Vanrenterghem 《Nephrology, dialysis, transplantation》2004,19(5):1281-1287
BACKGROUND: The natural history of parathyroid function after successful renal transplantation (RT) and the factors predisposing to persistent hyperparathyroidism (HPT) are not well established. A better knowledge of these data may be helpful in the development of algorithms for optimal surveillance and treatment of HPT after successful RT. Our aim was to evaluate the post-transplant natural history of parathyroid function and calcium metabolism in patients with a functional renal graft and to identify risk factors for persistent HPT. METHODS: Charts of 1165 allograft kidney recipients transplanted between 1989 and 2000 were reviewed. Patients with an intact parathyroid hormone (iPTH) level available at the time of transplantation were identified. The charts of the latter patients were checked for a variety of demographic and clinical data, and all determinations of the iPTH concentration available since transplantation were recorded. Serum levels of calcium, phosphorus, alkaline phosphatases and creatinine, concurrently determined, were also registered. RESULTS: After an initial fall, iPTH levels showed a slow but steady decline towards the upper normal limit. The prevalence of persistent HPT, defined as an iPTH level > or =2.5 times the upper normal limit or the need for parathyroidectomy following transplantation, remained stable at approximately 17% up to 4 years after transplantation. Patients with persistent HPT had significantly elevated serum levels of iPTH, calcium and phosphorus at the time of RT, and had spent a longer time on dialysis. Post-transplant iPTH levels correlated significantly with transplant kidney function. CONCLUSION: Kidney transplant recipients with a high iPTH and calcium x phosphate product at the time of transplantation are at risk for persistent HPT especially when renal function is suboptimal. Therapy for persistent HPT, if considered, should be initiated 3 months post-transplantation since further spontaneous improvement of parathyroid function thereafter is limited. 相似文献
98.
S. Y. Wong E. M. Lau W. W. Lau† & H. S. Lynn 《Journal of human nutrition and dietetics》2004,17(4):359-364
To determine the feasibility of increasing the calcium, protein and calorie intake of osteoporotic fracture patients by repeated dietary counselling delivered by a dietitian, a randomized controlled trial was conducted. Among 189 patients presenting with osteoporotic fractures to an Orthopaedics and Traumatology Department of a large regional hospital, 98 patients were randomized to the intervention group and 91 were randomized to the control group (with usual care). Intervention group received three sessions of dietary counselling with tailored made recommendations over a period of 4 months, while the control group only received dietary assessment and pamphlets on the prevention of osteoporosis. Almost all subjects in both intervention and control groups had calcium intake below the recommended level of 1000 mg at baseline. Half and 60% of subjects in both groups had total energy and protein intake below recommended levels respectively. The mean weights of control and intervention groups at baseline were 51.5 and 50.9 kg respectively, while the body mass index (BMI) were 22.6 (kg m(-2)) and 22.6 (kg m(-2)) respectively. After dietary intervention, significant increase of intake was seen in calcium intake (P = 0.0095 by t-test) in the intervention group. No significant increase was seen in protein or calorie intake. No significant change was observed in the body weight or BMI although there was a positive trend in the intervention group for all these parameters. We concluded that there was general malnutrition in Chinese elderly who presented with osteoporotic fractures. Dietary calcium could be increased by repeated professional dietary counselling. Future studies with longer duration and more objective clinical outcomes will be helpful to further demonstrate the long-term effects of dietary intervention on osteoporosis and other chronic diseases. 相似文献
99.
[目的]研究大豆蛋白对肾损害大鼠钙平衡的影响。[方法]选择3月龄断乳雄性SD大鼠40只.按体质量从小到大排序,采用完全随机化原则分为4组。每组10只。标准饲料对照组:喂食含有14%酪蛋白饲料;大豆蛋白饲料组:喂食含有14%大豆分离蛋白饲料;混合饲料1组:喂食含有7%酪蛋白加7%大豆分离蛋白饲料;混合饲料2组:喂食含有7%酪蛋白加14%大豆分离蛋白饲料。实验期用腺嘌呤灌胃共21d,建立肾损害大鼠模型,各组大鼠喂养相应饲料6周,测饲料消耗量、24h尿蛋白、尿钙、钙表观吸收率、储留钙量。[结果]4组实验大鼠饲料摄入量1d~30d无统计学差异,大豆蛋白饲料组和混合饲料1组实验结束时与另外两组相比,尿钙排泄量低,钙表观吸收率和储留钙量高,差异有统计学意义(P〈0.05)。[结论]蛋白质含量水平在14%条件下,含大豆蛋白的两种饲料对肾损害大鼠钙吸收、钙排泄的影响无统计学差异,有利于促进钙吸收,减少钙排泄。 相似文献
100.
汉防己甲素抑制三种神经递质引起的新生大鼠脑细胞内游离钙的升高 总被引:1,自引:0,他引:1
《中国药理学通报》1995,(3)
应用Pura-2技术测定游离新生大鼠脑[Ca2+]i浓度的技术、研究了Tet对静息脑[Ca2+]i和3种递质引起的脑[Ca2]i变化的影响。Tet(1,10和20μmol·L-1)对静息脑[Ca2+]i无明显影响。Tet(10μmol·L-1)可降低L-Gln(0.1、1.0和10μmol·L-1)引起的脑(Ca2+)i的升高。在Hank's液Ca2+为1.3mmol·L-1时,Tet10μmol·L-1可降低His(50和100μmol·L-1)和5-HT(0.1、1.0、10和100μmol·L-1)引起的脑[Ca2+]i的升高。但不能降低Hank's液无Ca2+时His和5-HT引起的脑[Ca2+]i的升高。研究表明Tet可阻滞L-Gin、His和5-HT受体调控的钙通道。但对His和5-HT引起的细胞内贮存钙的释放并无明显影响。Tet的这种降低脑[Ca2+]i的作用可能是其治疗脑缺血性疾病的机理之一。P<0.01在Tet10μmol·L-1作用下,相同浓度的细胞外液钙和His(0、50和100μmol·L-1),脑[Ca2+]i分别是221±5、245±5和302±6nmol·L-1。增加了11.8? 相似文献