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排序方式: 共有1631条查询结果,搜索用时 15 毫秒
931.
932.
Recombinant human bone morphogenetic protein (rhBMP-2) was examined for its in vitro effects on biochemical markers representing osteoblast phenotype. Primary cultures of fetal rat calvarial osteoblasts were used in this study. The results indicated that rhBMP-2 stimulated alkaline phosphatase activity, parathyroid hormone (PTH)-induced cyclic AMP production, and collagen biosynthesis in a dose-dependent manner in confluent cultures. The percent collagen synthesis also increased in a dose-dependent manner. Alkaline phosphatase activity was stimulated in a time-dependent manner by rhBMP-2 that reached its maximum 5 days after initiation. Cycloheximide (2 micrograms/ml) inhibited rhBMP-2-stimulated alkaline phosphatase indicating de novo protein synthesis of the enzyme. Transforming growth factor-beta 1 (TGF-beta 1)-induced inhibition of alkaline phosphatase activity observed in confluent primary cultures was completely abolished by rhBMP-2 at a concentration that was 43 times greater than the TGF-beta 1 concentration. Also, rhBMP-2 produced a small stimulation of alkaline phosphatase activity in cells grown in the absence of ascorbic acid; however, the effect was greatly enhanced in cells cultivated in the presence of ascorbic acid (50 micrograms/ml). In view of the potentiating effect of ascorbic acid on rhBMP-2-induced stimulation of alkaline phosphatase, we speculate that ascorbic acid could amplify the osteoinductive effects of rhBMP-2 and thereby augment the efficacy of the BMP when used as bone repair material in vivo. rhBMP-2 (4.3-86 ng/ml) did not exhibit mitogenic effects on cultured osteoblasts. These data suggest that rhBMP-2 has the ability to induce expression of various markers associated with the osteoblast phenotype in primary cultures of fetal rat calvarial osteoblasts. In addition, we speculate that TGF-beta 1 may play a regulatory role in BMP-induced bone formation and ascorbic acid may potentiate the effects of rhBMP-2 in vivo. 相似文献
933.
Previous studies have reported inhibition of A431 squamous carcinoma cell growth by nanomolar concentrations of epidermal growth factor (EGF), a potent mitogen for cells of epithelial origin. In this study, we examined potential mechanisms through which inhibition of keratinocyte growth mediated by EGF might occur by analysing components of the cell cycle regulatory machinery in A431, HN6 and HN30 keratinocytes in the presence of growth inhibitory or growth stimulatory doses of EGF. Treatment of cells with 25 pM EGF produced an increase in [3H]thymidine incorporation in A431, HN6 and HN30 cells, with respect to control cultures. Exposure to 2.5 nM EGF reduced [3H]thymidine incorporation in A431 cells and HN6 cells to 11% and 70% of control levels, respectively, whereas HN30 cells continued to proliferate in the presence of EGF. [3H]thymidine incorporation assays carried out over 24 h revealed repression of DNA synthesis in A431 cells after 12 h exposure to 2.5 nM EGF compared to untreated cells. Flow cytometry studies demonstrated accumulation of cells in G0/G1 after addition of 2.5 nM, but not 25 pM EGF. Western blot analysis revealed elevation of p21 (WAF1/CIP1/SDI1) protein levels in A431 and HN6 cells under growth-inhibitory conditions. Stimulatory doses of EGF did not induce p21 in these cells. Northern blot hybridization demonstrated elevated levels of p21 mRNA within 4 h of exposure of A431 cells to 2.5 nM EGF, which remained elevated above basal levels at 24 h. In vitro kinase assays demonstrated temporal differences in CDK2 and CDK6 activities which were related to EGF concentration. Immunocomplex Western blotting demonstrated increased association of p21 with CDK2 and CDK6 in A431 cells treated with 2.5 nm EGF. Furthermore, temporal alterations in the association of PCNA with p21 and with CDK6 were observed. The data indicate that p21 is a likely mediator of EGF-induced growth-inhibition, probably through mechanisms involving sequestration of PCNA and inhibition of CDK activity. 相似文献
934.
WA Prütz 《Canadian Metallurgical Quarterly》1993,18(3):159-165
Apolipoprotein E (Apo E) is a component of VLDL and HDL and plays a significant role in the regulation of cholesterol concentration. An improvement in isoelectric focusing for Apo E phenotyping is presented: the plasma Apo E was dissociated from lipoproteins by the use of Tween 20; the optimal concentration of type V neuraminidase was determined (1 U/ml); up to 48 samples were analyzed per plate and revealed by immunoblotting. Using this method, we have determined Apo E phenotypes and estimated their association with total cholesterol and Apo B levels in 498 healthy blood donors in Paris (France). The relative frequencies of Apo E alleles epsilon 2, epsilon 3 and epsilon 4 in this population were 0.079, 0.801 and 0.120, respectively. The association between Apo E phenotypes and concentration of Apo B-containing lipoproteins was confirmed (Apo B (g/l): E4/E3 subjects, 1.10 +/- 0.29; E3/E2 subjects, 0.93 +/- 0.22; both significantly different from E3/E3 subjects, 0.99 +/- 0.28). Total cholesterol (mmol/l): E4/E3 subjects, 5.43 +/- 1.15; E3/E2 subjects, 4.79 +/- 0.83; both significantly different from E3/E3 subjects, 5.03 +/- 1.11. 相似文献
935.
PJ Dahlberg WA Agger JR Singer WR Yutuc KL Newcomer A Schaper BL Rooney 《Canadian Metallurgical Quarterly》1995,16(9):506-511
OBJECTIVE: To determine if an attachable silver-impregnated cuff is effective in reducing subclavian hemodialysis catheter-related infections. DESIGN: Prospective, randomized, nonblinded study. SETTING: Community teaching hospital. PATIENTS: One hundred one acute and chronic renal failure patients requiring subclavian venipuncture and catheterization. After randomization, 47 patients underwent subclavian catheterization with a silver-impregnated cuff (Ag-CC), and 54 patients had routine catheter (RC) placements. MEASUREMENTS: Multiple presumed predictor variables for catheter-related infections, exit site infection rate, bacteremia rates, and semiquantitative cultures of all catheters. 相似文献
936.
AR Koch DP Vogelaers JM Decruyenaere B Callens A Verstraete WA Buylaert 《Canadian Metallurgical Quarterly》1995,33(3):253-256
Although poisoning with calcium channel blocking agents is frequent, to our knowledge no cases involving amlodipine have been published. We describe here a case of amlodipine intoxication, in which protracted hypotension did not respond to vasopressor therapy alone. After the addition of continuous calcium chloride and glucagon infusion, blood pressure was restored and vasopressor therapy could be tapered off substantially. When calcium and glucagon were interrupted because of severe hypercalcemia and hyperglycemia, the patient developed irreversible hypotension and died. Either glucagon or calcium or both, and to some extent vasopressors, seem to have constituted effective treatment of hypotension in this case. 相似文献
937.
The occlusal status of children in 6 schools for the handicapped was determined using the Occlusal Index (O.I.) of Summers (1966). Two dentists examined 381 children who had not previously received orthodontic treatment. An additional questionnaire investigating treatment interests and habits was also completed for each child. The study showed that 74,5 per cent required treatment, 10,5 per cent had good occlusions and 15 per cent had slight malocclusions where treatment was not considered essential. The mean O.I. was 7,92 +/- 4,33. Schools with mainly cerebral and mentally disabled children had a slightly higher O.I. but the difference in values was not statistically significant. The analysis also showed that 40,6 per cent of children were interested in receiving orthodontic treatment, but only 0,5 per cent were planning to seek it. There is a need for orthodontic treatment amongst disabled children and this should be taken into account in future oral health care planning. 相似文献
938.
Hallerman-Streiff syndrome is a rare congenital anomaly characterized by a peculiar bird facies, mandibular and maxillary hypoplasia, dyscephaly, cataracts, microphtalmia, hypotrichosis, skin atrophy, and short stature. Dental abnormalities are present in 80 percent of the cases and include malocclusion, crowding, severe caries, supernumerary and neonatal teeth, enamel hypoplasia, hypodontia, premature eruption of primary dentition, agenesis of permanent teeth, and anterior displacement or absence of condyles. Very few cases have been described in the dental literature. The predisposition to severe caries, together with other problems, makes it imperative that young patients be started in a strong prevention program as early as possible. This is a case report of a five-year-eleven-month-old white male who presented for a dental examination at The Children's Hospital in Denver, CO. The findings and recommendations for treatment are discussed. 相似文献
939.
Type II regulatory subunits are not required for the anchoring-dependent modulation of Ca2+ channel activity by cAMP-dependent protein kinase 总被引:1,自引:0,他引:1
KA Burton BD Johnson ZE Hausken RE Westenbroek RL Idzerda T Scheuer JD Scott WA Catterall GS McKnight 《Canadian Metallurgical Quarterly》1997,94(20):11067-11072
Preferential phosphorylation of specific proteins by cAMP-dependent protein kinase (PKA) may be mediated in part by the anchoring of PKA to a family of A-kinase anchor proteins (AKAPs) positioned in close proximity to target proteins. This interaction is thought to depend on binding of the type II regulatory (RII) subunits to AKAPs and is essential for PKA-dependent modulation of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid/kainate receptor, the L-type Ca2+ channel, and the KCa channel. We hypothesized that the targeted disruption of the gene for the ubiquitously expressed RIIalpha subunit would reveal those tissues and signaling events that require anchored PKA. RIIalpha knockout mice appear normal and healthy. In adult skeletal muscle, RIalpha protein levels increased to partially compensate for the loss of RIIalpha. Nonetheless, a reduction in both catalytic (C) subunit protein levels and total kinase activity was observed. Surprisingly, the anchored PKA-dependent potentiation of the L-type Ca2+ channel in RIIalpha knockout skeletal muscle was unchanged compared with wild type although it was more sensitive to inhibitors of PKA-AKAP interactions. The C subunit colocalized with the L-type Ca2+ channel in transverse tubules in wild-type skeletal muscle and retained this localization in knockout muscle. The RIalpha subunit was shown to bind AKAPs, although with a 500-fold lower affinity than the RIIalpha subunit. The potentiation of the L-type Ca2+ channel in RIIalpha knockout mouse skeletal muscle suggests that, despite a lower affinity for AKAP binding, RIalpha is capable of physiologically relevant anchoring interactions. 相似文献
940.
We evaluated 30 consecutive patients and 48 age- and sex-matched controls to explore the possibility of a pathogenic contribution by plasma endothelin-1 in the cardiac expression of systemic sclerosis. Venous plasma endothelin-1 was measured by radio-immunoassay and left ventricular function by echocardiography. The patient group had elevated plasma endothelin-1 (2.6 +/- 0.2 vs. 1.8 +/- 0.1 pmol/1, P < 0.001), but endothelin-1 was not related to age, heart rate, blood pressure, total peripheral resistance, disease duration or systemic sclerosis score. Endothelin-1 was related to left ventricular hypertrophy in terms of septal thickness (r = 0.33, P < 0.01) and left ventricular mass index (r = 0.32, P < 0.01). Plasma endothelin-1 was further related to measures indicating reduced left ventricular filling; left atrial emptying index (r = -0.50, P < 0.0005), the first third filling fraction (r = -0.31, P < 0.05) and the time velocity integral of Doppler early/late filling velocity (r = -0.40, P < 0.001). Furthermore, circulating endothelin-1 was related to impaired left ventricular contractility as estimated by pre-ejection period/left ventricular ejection time (r = 0.32, P < 0.01) and end-systolic wall stress/volume index (r = -0.30, P < 0.05). We conclude that plasma endothelin-1 is elevated in relation to the degree of left ventricular hypertrophy, diastolic dysfunction and impaired contractility in systemic sclerosis. It may be of pathogenic importance to the cardiac involvement in systemic sclerosis which is not mediated via an increase in systemic blood pressure. It is not yet clear whether our findings are exclusive to systemic sclerosis patients or represent a generalized phenomenon in patients with impaired left ventricular function. 相似文献