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Vitamin D metabolites can prevent estrogen depletion-induced bone loss in ovariectomized (OVX) rats. Our aim was to compare
the bone-protective effects of 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3), 1α,25-dihydroxyvitamin D2 (1,25(OH)2D2), 1α-hydroxyvitamin D3 (1α(OH)D3), and 1α-hydroxyvitamin D2 (1α(OH)D2) in OVX rats. 1α(OH)D3 and 1α(OH)D2 are thought to be activated in the liver to form 1,25(OH)2D3 and 1,25(OH)2D2, respectively. Forty-four 12-week-old female Fischer-344 rats were either OVX or sham-operated (SHAM). Groups of OVX rats
(n = 7 each) received vehicle alone, 1,25(OH)2D3, 1,25(OH)2D2, 1α(OH)D3, or 1α(OH)D2, starting 2 weeks after surgery. All vitamin D metabolites were administered orally at a dose of 15 ng/day/rat. Urine and
blood samples were collected 6, 9, 12, and 16 weeks after surgery. Serum samples were analyzed for total calcium and phosphate.
Calcium, phosphate, creatinine, and free collagen cross-links (ELISA) were determined in urine. After tetracycline double
labeling, the rats were sacrificed 16 weeks postsurgery, and the proximal tibiae and the first lumbar vertebrae were processed
undecalcified for static and dynamic bone histomorphometry. 1,25(OH)2D3 and, to a slightly lesser extent, 1,25(OH)2D2 elevated vertebral cancellous bone mass in OVX rats to a level beyond that observed in SHAM animals, and both compounds increased
serum calcium and urinary calcium excretion to similar extents. 1α(OH)D3 and 1α(OH)D2 resulted in a 64% and 84%, respectively, inhibition of ovariectomy-induced vertebral cancellous bone loss. In the proximal
tibial metaphysis, all vitamin D metabolites tested could only partially prevent post-OVX trabecular bone loss, with a tendency
for 1α(OH)D3 to be the least active compound. The effects of 1α(OH)D3 and 1α(OH)D2 on calcium homeostasis differed markedly, however. The mean increase in urinary calcium excretion over the whole experiment
was fivefold for 1α(OH)D3, whereas the corresponding increase for 1α(OH)D2 was only twofold. We conclude that, compared with 1α(OH)D3, 1α(OH)D2 combined at least equal or higher bone-protective activity in OVX rats with distinctly less pronounced effects on calcium
homeostasis. This effect was not due to a differential action of the corresponding main activation products, 1,25(OH)2D3 and 1,25(OH)2D2.
Received: 2 May 1996 / Accepted: 18 October 1996 相似文献
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Prior studies have shown that pneumothorax is one of the more difficult entities to diagnose with digitized radiography. This study was designed to test whether increasing resolution from 1.25 to 2.5 line pairs per millimeter (lp/mm) and image processing (edge enhancement from unsharp masking) would increase accuracy and confidence in the diagnosis of pneumothorax, as well as normal cases and other forms of lung disease. Conventional radiographs were digitized with use of a laser reader and then reformatted as film hard copy. Eleven observers read 35 cases reformatted in three different ways (1.25 lp/mm, 2.5 lp/mm, 1.25 lp/mm unsharp mask). The images with finer resolution (2.5 lp/mm) and unsharp mask images were superior to those with coarser resolution (1.25 lp/mm) for the diagnosis of pneumothorax. There was no difference in diagnostic accuracy for normal patients. For abnormalities other than pneumothorax, the unsharp mask images were significantly worse. Confidence in the diagnosis of pneumothorax and other abnormalities was highest with the finest resolution (2.5 lp/mm). 相似文献
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导数光谱系数倍率法测定多组分体系感冒清胶囊中盐酸吗啉胍的含量 总被引:1,自引:0,他引:1
This paper provides a basic principle and experimental technique of derivative signal multiplier spectrophotometry in multicomponent mixture. A microcomputer was used to process the spectral data measured on a manual spectrophotometer (UV-7520) for the determination of moroxydine hydrochloride in Gan Mao Qing capsules. Quantitative analysis of multicomponent mixture can be done without sample separation. The selection of optimal wavelength pairs is performed through the program with a computer. The method needs no special spectrophotometer and is simple, rapid and easy to operate. The mean recovery was 99.98 +/- 0.53% (n = 12). 相似文献
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Application of reflectance spectroscopy to the estimation of uric acid, urea and glucose: an evaluation of the Ames Seralyzer 下载免费PDF全文
An original approach to the measurement of analytes in clinical chemistry has now become available, in which dry reagent strip technology is linked to measurement by reflectance spectroscopy. The present studies have evaluated the performance of the first of these test systems—for uric acid, urea and glucose, in serum—by comparison with conventional liquid chemistry methods. Satisfactory performance in terms of both precision and accuracy was obtained for all three test systems, the current “state-of-the-art” performance criteria being met; the Seralyzer system proved reliable and easy to use in the hands of trained operators. It should find a place as a “Stat” analyser in the laboratory, in specified wards and in Health Centres. 相似文献
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Permeation of human ovarian tissue with cryoprotective agents in preparation for cryopreservation 总被引:18,自引:10,他引:18
Newton H; Fisher J; Arnold JR; Pegg DE; Faddy MJ; Gosden RG 《Human reproduction (Oxford, England)》1998,13(2):376-380
The recent improvements in the treatment of cancer by chemo- and
radiotherapy have led to a significant increase in the survival rates of
patients with malignant disease, but at the expense of distressing side
effects. One major problem, especially for younger patients, is that
aggressive therapy destroys a significant proportion of the follicular
population, which can result in either temporary or permanent infertility.
Freeze-banking pieces of ovarian cortex prior to treatment is one strategy
for preserving fecundity. When the patient is in remission, fertility
could, theoretically, be restored by autografting the thawed tissue at the
orthotopic site or by growing isolated follicles to maturity in vitro.
Recent studies have found good follicular survival in frozen-thawed human
ovarian tissue but to optimize the process an effective cryopreservation
method needs to be developed. An essential part of such a technique is to
permeate the tissue with a cryoprotectant to minimize ice formation and the
extent of this equilibration is an important determinant of post-thaw
cellular survival. In the current study, we have investigated the diffusion
of four cryoprotective agents into human tissue at both 4 degrees C and 37
degrees C. We have also studied the effect of adding different
concentrations of the non penetrating cryoprotective agent, sucrose, to the
freezing media using the release of lactate dehydrogenase as a measure of
its protective effect. At 4 degrees C propylene glycol and glycerol
penetrated the tissue significantly slower than either ethylene glycol or
dimethyl sulphoxide. At the higher temperature of 37 degrees C all four
cryoprotectants penetrated at a faster rate, however concern about enhanced
toxicity prevents the use of these conditions in practice. Thus, the
results suggest that the best method of preparing tissue for freezing is
exposure for 30 min to 1.5 M solutions of ethylene glycol or dimethyl
sulphoxide at 4 degrees C; this achieved a mean tissue concentration that
was almost 80% that of the bathing solution. We also report that the
addition of low concentrations of sucrose to the freezing medium does not
have a significant protective effect against freezing injury.
相似文献