Evaluation of filling materials in membrane‐protected bone defects. A comparative histomorphometric study in the mandible of miniature pigs.

In recent years, bone grafts and bone substitutes have been increasingly utilized underneath barrier membranes to optimize the treatment outcome of bone reconstructive therapy for defects in the alveolar process. In the present study, 4 different filling materials were evaluated in bone defects of similar dimensions in the mandible of miniature pigs. Blood clots and autografts were used as controls. The defects were covered with barrier membranes and allowed to heal for 4, 12 or 24 weeks. Histologic examination demonstrated that bone repair progressed through a programmed sequence of maturation steps closely resembling the pattern of bone development and growth regardless of whether bone grafts or substitutes were present or not. Histomorphometric analysis showed that autologous bone grafts (autografts) had the best osteoconductive properties during the initial healing period, with 39% of newly formed bone inside the membrane-covered defects at 4 weeks of healing. In addition, 87% of the graft surfaces were already covered by bone at this time. Both values were significantly higher for autografts than for the 4 alternative bone fillers (P < or = 0.05). At 12 weeks, these differences were no longer apparent, with all 5 filling materials showing similar values. Among the tested bone substitutes, tricalcium phosphate (TCP) showed a significantly higher percentage of bone fill at 24 weeks of healing. It can be concluded that sites filled with autografts clearly demonstrated the best results underneath barrier membranes in the early phase of healing. As far as degradation and substitution are concerned, TCP showed the most promising results. This filler, however, needs to be tested further in a more demanding animal model. Less favorable results were obtained for coral-derived hydroxyapatite granules and for demineralized freeze-dried bone allografts.     

抑制剂对酪氨酸酶影响的初步研究

采用酶动力学及聚丙烯酰胺凝胶电泳方法研究了ＮａＨＳＯ３、ＮａＮ３、ＫＳＣＮ、ＤＤＣ对酪氨酸酶的抑制作用。ＮａＨＳＯ３、ＮａＮ３、ＫＳＣＮ为非竞争性抑制作用，随着抑制剂浓度增加，酶活性逐渐减弱。当ＮａＨＳＯ３、ＮａＮ３、ＫＳＣＮ的浓度分别达到１．２ｍｍｏｌ／Ｌ１２。５ｍｍｏｌ／Ｌ１２．５ｍｍｏｌ／Ｌ时，酶活性的抑制率为１００％、５０％、２４％。ＤＤＣ对酪氨酸酶的抑制作用为竞争性抑制作用，其浓度达４ｍｍｏｌ／Ｌ时，酶活性１００％受到抑制。     

肾脏疾病患者治疗前后血浆内皮素水平动态变化及其意义

目的 为了探讨肾脏疾病患者血浆内皮素水平与肾脏疾病病情程度的关系,为肾脏疾病治疗效果的评价提供依据.方法 采用放射免疫分析(RIA)观察了77例肾脏疾病患者治疗前后血浆内皮素水平的动态变化,并与60例正常对照组比较.结果 正常对照组血浆内皮素浓度为43.1±15.2ng/L,肾脏疾病患者治疗前血浆内皮素水平为161±83.8ng/L,治疗后为97.4±52.7ng/L,均高于正常对照组(P值均<0.001).肾脏疾病治疗后内皮素水平明显下降(P<0.001),与BUN,Cr水平的下降具有一定的相关性(相关系过分别为0.54,0.55).结论血浆内皮素水平随着肾脏疾病严重程度的增加而升高,血浆内皮素水平可作为肾脏疾病治疗效果评定的指标之一     

示波极谱滴定法测定盐酸苯海拉明苯妥英钠及其制剂含量

采用示波极谱滴定法测定了盐酸苯海拉明、苯妥英钠及其制剂含量,所得结果均达到药典标准,与非水滴定法或提取后分光光度法比较,本法具有快速、准确、简单、操作方便、免用有机溶剂的优点。     

-2-Hydroxyglutaric acid inhibits mitochondrial creatine kinase activity from cerebellum of developing rats

L-2-Hydroxyglutaric acid (LGA) is the biochemical hallmark of patients affected by the neurometabolic disorder known as L-2-hydroxyglutaric aciduria (LHGA). Although this disorder is predominantly characterized by severe neurological findings and pronounced cerebellum atrophy, the neurotoxic mechanisms of brain injury are virtually unknown. In the present study, we investigated the effect of LGA, at 0.25-5mM concentrations, on total creatine kinase (tCK) activity from cerebellum, cerebral cortex, cardiac muscle and skeletal muscle homogenates of 30-day-old Wistar rats. CK activity was measured also in the cytosolic (Cy-CK) and mitochondrial (Mi-CK) fractions from cerebellum. We verified that tCK activity was significantly inhibited by LGA in the cerebellum, but not in cerebral cortex, cardiac muscle and skeletal muscle. Furthermore, CK activity from the mitochondrial fraction was inhibited by LGA, whereas that from the cytosolic fraction of cerebellum was not affected by the acid. Kinetic studies revealed that the inhibitory effect of LGA on Mi-CK was non-competitive in relation to phosphocreatine. Finally, we verified that the inhibitory effect of LGA on tCK was fully prevented by pre-incubation of the homogenates with reduced glutathione (GSH), suggesting that this inhibition is possibly mediated by oxidation of essential thiol groups of the enzyme. Considering the importance of creatine kinase activity for energy homeostasis, our results suggest that the selective inhibition of this enzyme activity by increased levels of LGA could be possibly related to the cerebellar degeneration characteristically found in patients affected by L-2-hydroxyglutaric aciduria.     

Phosphate end dialysis value : a misleading parameter of hemodialysis efficiency

Despite low end dialysis serum phosphate levels (P_e) the control of phosphate retention remains often unsatisfactory in dialyzed patients. In order to assess the value of P_e in dialyzed children as an indicator of dialytic phosphate removal, we studied serum phosphate kinetics over the period of dialysis and post dialysis and compared these with urea kinetics. A multicenter study was conducted in the 21 French pediatric hemodialysis units and included 144 children under 15 years of age. Blood urea and phosphate concentrations were measured at the beginning, at 45 min later, at the end of dialysis, and 30 min post dialysis. At 60 min and at 360 min post dialysis measurements were made only for a subgroup of 12 children. From the serum levels, reduction ratios for urea (URR) and phosphate (PRR) and post dialysis rebound for urea (PDUR) and phosphate (PDPR) were calculated. URR (over the dialysis session, 72%±9%) was higher than PRR (47%±12%). Moreover, urea removal continued throughout the dialysis period, while most of the reduction in phosphate occurred in the initial dialysis period. Post dialysis urea rebound was limited to the 60th min post dialysis, whereas post dialysis phosphate rebound occurred until the 360th min post dialysis; by this time the serum phosphate levels had almost reached the predialysis levels. In summary, serum phosphate kinetics over dialysis and post dialysis periods in children appear to be misleading for the quantification of phosphate removal, i. e., phosphate clearance is a poor indicator of dialytic phosphate removal. Received September 21, 1995; received in revised form and accepted June 11, 1996     

高碘摄入对SD大鼠钠/碘同向转运体蛋白表达影响的免疫组化研究

目的:动态观察长期高碘摄入对SD大鼠甲状腺细胞钠/碘同向转运体(NIS)蛋白表达的影响.方法:SD大鼠分别饲以去离子水及不同碘浓度的碘化钾水,给碘后1 d及1,2,4,8周处死.测定尿碘、组织碘含量,免疫组织化学方法观察甲状腺细胞NIS蛋白表达水平.结果:高碘摄入可引起甲状腺滤泡细胞膜表面NIS蛋白表达的下降.短期较低浓度的高碘摄入对NiS蛋白的表达无明显影响,而较高浓度的碘摄入则引起NIS蛋白表达的明显减少;长期高碘摄入对NIS蛋白表达的抑制作用,可在机体自我调节机制作用下得以部分恢复,但NIS蛋白表达仍处较低水平.结论:高碘摄入可导致甲状腺细胞表面NIS蛋白表达下降,随摄碘浓度的增加抑制作用增强;不同浓度的碘摄入对NIS蛋白表达的抑制作用表达时间不同.     

高危出血患者应用吉派林抗凝血液透析疗效观察

目的：观察危重型肾功能衰竭合并高危出血患者选择抗凝药物进行血液透析治疗的效果。方法：应用吉派林(低分子肝素钠)作为抗凝剂进行血液透析。结果：129例病人进行血液透析386次，均没有出血发生。结论：吉派林在高危出血患者血液透析中使用方便，安全，效果良好。     

Relative weight of glucose, insulin and parathyroid hormone in the urinary loss of phosphate by chronically diabetic rats

This report deals with the relationships between glucose (G) and insulin on the tubular transport of phosphate (P) in chronically diabetic rats with high plasma levels of parathyroid hormone (PTH). Alloxan-induced diabetes leads to phosphorus depletion of the soft tissues. This phenomenon appears associated with weight loss and negative P balances caused by the increased urinary P excretion. Administration of 2 IU of insulin/100 g body weight (bw) to diabetic rats normalized their P balance and body weight. The effect of parathyroid function on the P metabolism of diabetic rats was investigated with balance experiments. Diabetic rats, intact or thyroparathyroidectomized (TPTX), have a greater urinary excretion of P than their controls. However, in control rats, the ratio intact:TPTX for urinary P is 1.0:0.76, showing the antiphosphaturic effect of parathyroid ablation. For diabetic animals, on the other hand, the ratio is 1.0:1.44. The simultaneous deficit of insulin and PTH thus quadruples the urinary P loss, instead of compensating for each other. The contribution of insulin deficit and hyperglycemia to the defect in tubular reabsorption (TRP) was investigated with clearance experiments (done on anesthetized, perfused rats). Five experimental groups were used: Controls (C), diabetics (D), controls+glucose (C+G), diabetics+insulin (D+I) and diabetics+insulin+glucose (D+I+G). All experimental groups showed a linear relationship between the TRP of P and G. The regression equation for C is significantly different (F=40.1, P<0.001) from that of D animals. The slope value measure the number of μmoles of P per μmol of G reabsorbed. For C and D rats, the ratio P:G approximates 1:4 and 1:20, respectively. The increase in P:G ratios represents the competition between both substrates for tubular resorption. Glycemias up to 11 mM (C and D+I) exist concurrent with the P:G ratio 1:4. Glycemias above 25 mM (D, C+G and D+I+G) produce a P:G ratio of 1:20. Fractional excretion of P (FEP) increased significantly in untreated, chronically diabetic rats (0.47± 0.12 vs controls=0.05±0.01, P<0.001). After a single intramuscular injection of insulin, the FEP decreased as a function of insulin levels. To normalize the FEP of diabetic rats in short-term experiments, insulin had to be administered in doses that produce plasma insulin levels 25 times greater than normal. The general information afforded by the present experiments shows that in untreated, chronically diabetic rats, insulin deficit plays an indirect role. The absence of PTH enhances the effect of hyperglycemia. The latter and the concurrent tubular overload of glucose are the cause of hyperphosphaturia in these animals. Received: 10 September 1996 / Accepted in revised form: 18 April 1997     

Fmoc/solid-phase synthesis of Tyr(P)-containing peptides through t-butyl phosphate protection

The synthesis is of Tyr(P)-containing peptides by the use of Fmoc-Tyr(PO₃Me₂)-OH in Fmoc/solid phase synthesis is complicated since, firstly, piperidine causes cleavage of the methyl group from the -Tyr(PO₃ Me₂)-residue during peptide synthesis and, secondly, harsh conditions are needed for its final cleavage. A very simple method for the synthesis of Tyr(P)-containing peptides using t-butyl phosphate protection is described. The protected phosphotyrosine derivative, Fmoc-Tyr(PO₃^tBu₂)-OH was prepared in high yield from Fmoc-Tyr-OH by a one-step procedure which employed di-t-butyl N,N-diethyl-phosphoramidite as the phosphorylation reagent. The use of this derivative in Fmoc/solid phase peptide synthesis is demonstrated by the preparation of the Tyr(P)-containing peptides, Ala-Glu-Tyr(P)-Ser-Ala and Ser-Ser-Ser-Tyr(P)-Tyr(P).