The response of creatine kinase specific activity in rat pituitary to estrogenic compounds and vitamin d less-calcemic analogs.

We examined the response of rat female pituitary at different metabolic stages to treatments with estrogenic compounds and vitamin D analogs. Immature or ovariectomized (Ovx) female rats responded by increased creatine kinase specific activity (CK) to estradiol-17beta (E(2)), genistein (G), daidzein (D), biochainin A (BA), quecertin (Qu), carboxy- G (cG), carboxy- BA (cBA), and raloxifene (Ral). The response was inhibited when Ral was injected together with the estrogens. CK was increased when hormones were injected daily into Ovx rats for 4 different time periods. Pretreatment with the less-calcemic vitamin D analogs JK 1624 F(2)-2 (JKF) or QW 1624 F(2)-2 (QW) followed by estrogenic injection resulted in increased response and sensitivity to E(2) and loss of inhibition of E(2) by Ral. CK was also increased by feeding with E(2) or licorice or its components dose- and time- dependent in immature or Ovxrats. Diabetic female rats did not respond to increased doses of E(2). In conclusion, rat female pituitary is estrogens-responsive organ, suggesting to considerits response for HRT in postmenopausal women for both beneficial and hazardous aspects.

Promotion of angiogenesis by low energy laser irradiation.

The effect of low energy laser (He-Ne) irradiation (LELI) on the process of angiogenesis in the infarcted rat heart and in the chick chorioallantoic membrane (CAM), as well as the proliferation of endothelial cells in tissue culture, was investigated. Formation of new blood vessels in the infarcted rat heart was monitored by counting proliferating endothelial cells in blood vessels. In the CAM model, defined areas were laser-irradiated or nonirradiated and blood vessel density was recorded in each site in the CAM at various time intervals. Laser irradiation caused a 3.1-fold significant increase in newly formed blood vessels 6 days post infarction, as compared with nonirradiated rats. In the CAM model, a slight inhibition of angiogenesis up to 2 days post irradiation and a significant enhancement of angiogenesis in the laser-irradiated foci as compared with control nonirradiated spots were evident. The LELI caused a 1.8-fold significant increase in the rate of proliferation in endothelial cells in culture over nonirradiated cells. It is concluded that LELI can promote the proliferation of endothelial cells in culture, which may partially explain the augmentation of angiogenesis in the CAM model and in the infarcted heart. These results may have clinical significance by offering therapeutic options to ameliorate angiogenesis in ischemic conditions.

Reversal of corticosteroid-induced diabetes mellitus with supplemental chromium.

AIMS: To determine if the stress of corticosteroid treatment increases chromium (Cr) losses and if corticosteroid-induced diabetes (steroid diabetes) can be reversed by supplemental chromium. METHODS: The effects of corticosteroid treatment on chromium losses of 13 patients 2 days prior to steroid administration and the first 3 days following treatment were determined. Since steroid-induced diabetes was associated with increased chromium losses and insufficient dietary chromium is associated with glucose intolerance and diabetes, we treated three patients with steroid-induced diabetes with 600 microg per day of chromium as chromium picolinate. RESULTS: Urinary chromium losses following corticosteroid treatment increased from 155+/-28 ng/d before corticosteroid treatment to 244+/-33 ng/d in the first 3 days following treatment. Chromium supplementation of patients with steroid-induced diabetes resulted in decreases in fasting blood glucose values from greater than 13.9 mmol/l (250 mg/dl) to less than 8.3 mmol/l (150 mg/dl). Hypoglycaemic drugs were also reduced 50% in all patients when given supplemental chromium. CONCLUSIONS: These data demonstrate that corticosteroid treatment increases chromium losses and that steroid-induced diabetes can be reversed by chromium supplementation. Follow-up, double-blind studies are needed to confirm these observations.

Effects of insulin and glucose tolerance factor (GTF) on growth of Saccharomyces cerevisiae.

Addition of mammalian insulin to Saccharomyces cerevisiae enhanced the growth of the cells in several glucose concentrations. The enhancement of growth was dependent on insulin concentrations. Morphological changes were also observed depending on the presence of insulin: the cells were almost round, whereas elongated forms appeared under depletion of the hormone. The effect of insulin was very similar to the increase in yeast growth observed by the addition of GTF (glucose tolerance factor) to the medium. Our findings support the view of a common mechanism regulating metabolic and growth processes in lower and higher organisms.

Effects of insulin and glucose tolerance factor on glucose uptake by yeast cells.

Addition of mammalian insulin or glucose tolerance factor (GTF), to Saccharomyces cerevisiae ATCC 7752, increased 2-deoxyglucose uptake by yeast cells. The enhancement was dose-dependent, and also dependent on preincubation of the cells with glucose, prior to the addition of the hormone. The effect of insulin on glucose uptake by the yeast was very similar to the effect of GTF on these cells. Insulin and GTF increased also the growth of yeast cells, while denatured insulin or glucagon failed to act. Our findings support the view that both insulin and GTF might regulate carbohydrate metabolism in microorganisms.

Glucose tolerance factor reduces blood glucose and free fatty acids levels in diabetic rats.

Effect of Glucose Tolerance Factor (GTF) extracted from commercially available yeast extract powder was examined on streptozotocin diabetic rats. Different doses of GTF preparation were injected into diabetic rats, with no addition of exogenous insulin. Within two hours there was a significant decrease both in blood glucose and free fatty acids (FFA) levels in the diabetic animals, indicating an anti-diabetic potential of GTF.

Effects of increased doses of 1,25 dihydroxyvitamin D3 on matrix and DNA synthesis in condylar cartilage of suckling mice.

The in vivo effects of high doses of 1,25(OH)2D3 were studied in condylar cartilage of suckling mice. Seven-day-old animals were treated with 20 ng of the hormone for 7 consecutive days. Biochemical assays on collagen content and synthesis were complemented by structural studies using light and electron microscopy. Indirect immunofluorescent methods were used for the localization of type I and II collagens and for fibronectin. This study revealed that the protein content of the condyle decreased substantially following the administration of the hormone. Protein synthesis increased in hormone-treated animals during the first 4 days but was significantly inhibited thereafter. Collagen synthesis, however, was inhibited instantaneously, followed by a decrease in the percentage of cold hydroxyproline of the total protein. Hormone-treated condyles showed a marked decrease in the distribution of type I collagen, no apparent change in the distribution of type II collagen, but an enhanced reactivity for fibronectin especially around hypertrophic chondrocytes. SDS-gel electrophoresis of collagen chains suggested that the hormone did not induce a significant change in the ratios of type I and II collagen chains, yet additional peaks became evident in 1,25(OH)2D3-treated specimens. The decrease in collagen synthesis was accompanied by ultrastructural changes in the appearance of the extracellular collagen bundles. They later appeared as a dense meshwork of collagen fibrils, a feature that was lacking in control tissues. The changes in collagen fibrillogenesis could be explained by our in vitro studies indicating a marked depression of 35S-sulfate incorporation secondary to treatment with 1,25(OH)2D3. The hormone was also found to suppress the incorporation of 3H-thymidine, hence it may be concluded that 1,25(OH)2D3, when used in high concentrations, possesses an inhibitory effect upon both the proliferative activity of the cartilage progenitor cells as well as upon the metabolic activity of the condylar cells as related to collagen and glycosaminoglycans synthesis.

Structural and histochemical study of the effect of 1,25-dihydroxyvitamin D3 on long-bone growth center in suckling mice.

The in vivo effects of 1 alpha,25-dihydroxyvitamin D3 [1,25(OH)2D3] on cellular structure and response, matrix metachromasia and mineralization have been studied in the epiphysis and growth plate of humeri in normal neonatal mice. A relatively low dose of the metabolite, 50 ng/kg body weight, significantly increased the overall size of humeral growth plate, the zone of proliferating cells and that of hypertrophic chondrocytes. The response of the tissue to the metabolite changed with the increase in dose administered so that it was only the zone of proliferation that still showed increases in size in comparison to untreated controls. 1,25 (OH)2D3 led to an increase in the metachromatic reaction of the cartilage matrix in the chondroblastic zone, and to marked increase in matrix mineralization in the hypertrophic zone. Qualitative changes were also noted in the structure of chondroblasts and hypertrophic chondrocytes. 1,25(OH)2D3 affected the osteoblastic and osteocytic populations of cells along the metaphysis and diaphysis of the humerus. High doses of 1,25(OH)2D3 brought about distinct atrophic changes in the above cells. Chondrocytes in the epiphysis were found to synthesize type I collagen and fibronectin. These findings indicate that excessive doses of 1,25(OH)2D3 in an intact growing animal affect the normal differentiative pathway of prechondroblasts and thereby affect long bone development.

Structural study on the effect of 24,25-dihydroxyvitamin D3 on epiphyseal growth plate in suckling mice.

The in vivo effects of 24,25(OH)2D3 on cellular structure and organization, matrix metachromasia and mineralization were studied in epiphyseal growth plate of normal neonatal mice. A relatively low dose of the metabolite, 40 ng/kg body weight, significantly increased the overall size of humeral growth plate and the zone of cellular proliferation. By and large, the tissue's response to the metabolite did not change with the increase in dose administered except for a decrease in the number of chondroblasts. 24,25(OH)2D3 led to significant increases in the metachromatic reaction of the cartilaginous matrix, but appeared to depress the mineralization process. Qualitative structural changes were noted in chondroblasts and hypertrophic chondrocytes. 24,25(OH)2D3 affected the osteoblastic and osteocytic populations of cells in the metaphysis and diaphysis of the humerus. High doses of 24,25(OH)2D3 brought about distinct atrophic changes in the above cells. These findings indicate that excessive doses of 24,25(OH)2D3 in an intact animal may lead to retardative effects upon bone growth.

Studies on hormonal regulation of the growth of the craniofacial skeleton: III. Effects of 24,25 (OH)2D3 on cartilage growth in the mandibular condyle of suckling mice.

This study examined the influence of 24,25 (OH)2D3, an active metabolite of vitamin D, on the growth and development of cartilage cells in condylar cartilage of suckling mice. It became evident that when the hormone was administered even at high doses, it did not significantly affect the incorporation of [3H]thymidine, but led to a marked decrease in the number of both chondroblasts and hypertrophic chondrocytes. At the same time, condyle of hormone-treated mice reached an increase in the number of mesenchymelike cells within the chondroprogenitor zone. High values of correlation were noted between the overall dimensions of the condylar cartilage and those of the chondroblastic and hypertrophic zones. The hormone also significantly reduced the degree of matrix metachromasia (indicative of proteoglycan content) and concomitantly altered the mineralization pattern of the cartilaginous matrix. This study indicates that in young animals increased doses of 24,25(OH)2D3 do not affect the proliferative activity of chondroprogenitor cells yet possess an inhibitory effect upon the capacity of the latter cells to differentiate into chondroblasts. The hormone also seems to affect the already differentiated cells--chondroblasts and hypertrophic chondrocytes--both structurally as well as metabolically. In so doing, this metabolite of vitamin D affects the normal process of endochondral bone formation in one of the mandible's main growth sites. Thus, in the developing animal, elevated concentrations of 24,25(OH)2D3 may impair the growing mandible's ability to achieve its normal size and shape.

The effect of 1,25-dihydroxyvitamin D3 on cartilage growth in neonatal mice.

The in vivo effects of 1,25(OH)2D3 on cell proliferation, tissue organization and matrix mineralization have been studied in condylar cartilage of neonatal mice. A relatively low dose of the metabolite, 50 ng/kg body weight, significantly reduced the incorporation of [3H]thymidine as well as the number of chondroblasts. The cartilage as a whole underwent a marked derangement in its organization, as many fibroblastlike cells appeared to occupy the zone of progenitor cells. There was a high degree of correlation observed between the effects of 1,25(OH)2D3 upon [3H]thymidine incorporation and the size of the condylar zone of chondroblasts. With increasing doses, enhanced mineralization was noted in the cartilaginous matrix, along with cartilage cell degeneration. These findings indicate that 1,25(OH)2D3 possesses an inhibitory effect upon both the proliferative activity of prechondroblasts and upon the capacity of those cells to differentiate into chondroblasts.

Chromium in biological systems, I. Some observations on glucose tolerance factor in yeast.

Glucose tolerance factor (GTF) has been isolated from a commercially available yeast extract powder, by a simple procedure under mild conditions. This cationic yellow material enhances considerably CO2 production in several yeast strains, after a lag time which can be eliminated by preincubation with glucose. The enhancement of CO2 production by GTF is not specific for glucose, and its effect on galactose raises the possibility that it influences the transport of the sugar to the cells. The ineffectiveness of GTF on cell free extract and the results of a Michaelis plot for CO2 production support this hypothesis.