Expression of stanniocalcin in the epithelium of human choroid plexus

Stanniocalcin (STC) is a 28 kD glycoprotein hormone originally found in bony fish in which it regulates calcium/phosphate homeostasis and protects against hypercalcemia. The recently characterized mammalian STC shows about 70% homology with fish STC. The epithelial cells of proximal tubuli in human and rat kidney and brain neurons have been found to express STC. Here we show that the epithelium of the choroid plexus, already at 16 weeks of fetal age, and of plexus papillomas, synthesize and express STC. Our findings suggest that STC may be of importance for the distribution of calcium and phosphate between the cerebrospinal fluid and blood.     

Inhibition of the protein kinase A alters the degradation of the high-affinity phosphate transporter Pho84 in Saccharomyces cerevisiae

In Saccharomyces cerevisiae, nutrient sensing is the major factor controlling cell growth and proliferation. It has been shown that phosphate signalling involves the activation of the protein kinase A (PKA) in response to an elevation of external phosphate when cells have experienced a severe phosphate limitation. Addition of phosphate or its non-metabolized analogue, methylphosphonate (MP), to cells grown under phosphate limitation triggers degradation of the Pho84 phosphate transporter and represses the acidic phosphatase activity. In this study we have shown that of the five inorganic phosphate transporters (Pho84, Pho87, Pho89, Pho90, Pho91) of the plasma membrane, only Pho84 is required for the MP recognition and repression of the acidic phosphatase activity. By use of the PKA inhibitor H89, we demonstrate that down-regulation and degradation of the Pho84 transporter, in response to an elevation of external phosphate, is delayed by the inhibition of PKA. In contrast, down-regulation of the acidic phosphatase is under these conditions not affected by the PKA inhibition. Altogether, these observations suggest that the PKA signalling pathway plays a role in conveying the signal for the down-regulation and degradation of the Pho84 transporter in the vacuolar compartment in response to altered phosphate availability in the external environment.     

Serum calcium and phosphate changes in thyroidectomized dogs

The thyroid glands were removed from dogs without interfering with the superior parathyroid glands. Levels of serum calcium, phosphate, and specific gravity were measured subsequently for 24 hours, and these values were compared with values obtained from a control group of dogs in which a mock operation was done. Immediately after thyroidectomy, the level of phosphate was greater than the calcium level. The phosphate level remained high longer after thyroidectomy than did the calcium level. The relationship between the increase in phosphate level and the initial serum phosphate value in each animal indicated normal variations in calcitonin levels in different animals.Mayo Clinic and Mayo Foundation: Section of Surgical Research. This investigation was supported in part by Research Grant AM-8658 from the National Institutes of Health, Public Health Service.     

磷酸二丁酯的毛细管柱气相色谱分析

目的 发展适合于作业场所空气中磷酸二丁酯（DBP）的测定方法。方法将DBP以硅烷化试剂BSTFA衍生后，在弹性石英毛细管柱上分析，研究定量测定的条件。结果DB-FFAP柱在氮气恒压50kPa，柱初始温度120℃，10℃／min速率升温到180℃，尾吹40ml／min，进样口（INJ）和检测器（FPD）温度为240℃的气相色谱条件下，在0．1～10．0μg范围DBP的含量与其峰面积线性良好，相关系数在0．995以上，最低检测限0．061μg／ml，样品测定的回收率95％～103％，重复测定的RSD在4％～6％之间。结论该方法适用于作业场所空气中DBP的测定。     

氨酚待因片（Ⅱ）处方工艺研究及溶出度考察

目的：筛选优化氨酚待因片（Ⅱ）的处方工艺。方法：通过处方设计筛选填充剂、粘合剂和崩解剂,以湿法制粒制备氨酚待因片（Ⅱ）,以市售制剂在不同介质中的溶出曲线为指标,确定处方工艺。结果：采用优化处方工艺制备的氨酚待因片（Ⅱ）的溶出行为与市售制剂基本一致。结论：处方工艺合理,达到设计要求。     

慢性肾功能不全患者血清甲状旁腺素、钙、磷之间的关系

为了解慢性肾功能不全患者血清中钙、磷、甲状旁腺素（PTH）水平变化,藉以推测继发性甲状腺腺亢进的原因,观察了92例不同阶段段功能不全患者的血清、钙、磷、PTH水平。结果显示,PTH与内生肌酐清除（Ccr)呈负相关（P＜0．05）,与血清磷水平呈正相关（P＜0．05）,与血清钙水平无相关必.性肾功能不全早期,随着Ccr降低,PTH逐渐升高,但血磷、血钙水平并无显著改变,慢性肾功能不全后期（肾功能衰竭期）血磷水平才明显升高,血钙水羡明显降低。     

An ultrastructural investigation of tissue-engineered pulp constructs implanted within endodontically treated teeth

BACKGROUND: The authors conducted an ultrastructural scanning electron microscopic (SEM) investigation of tissue-engineered pulp constructs implanted within endodontically treated teeth. METHODS: Stem cells from human exfoliated deciduous teeth were seeded on a synthetic open-cell D,D-L,L-polylactic acid scaffold with or without the addition of bone morphogenic protein-2 and transforming growth factor beta1 to create pulp tissue constructs. The pulp constructs were implanted into 105 extracted human premolar teeth with a single root canal that had been cleaned and shaped by using rotary instrumentation in a crown-down manner to ISO size no. 35. RESULTS: An ultrastructural examination of the SEM micrographs at x2,000 magnification revealed cell adherence within all of the pulp constructs, with little difference between the scaffold types or with the addition of growth factors. CONCLUSIONS: These results support the proof-of-concept that it is possible to implant tissue-engineered pulp constructs into teeth after cleaning and shaping. CLINICAL IMPLICATIONS: Future regenerative endodontic treatment may involve the cleaning and shaping of root canals followed by the implantation of vital dental pulp tissue constructs created in the laboratory.     

Biofilm plaque and hydrodynamic effects on mass transfer, fluoride delivery and caries

BACKGROUND: The biofilm concept of dental plaque now is widely accepted in the dental clinic, particularly with respect to its importance to oral hygiene. A number of reviews have focused on the microbial ecology of biofilm with regard to oral health; however, there has been less focus on how the interaction of biofilms and hydrodynamics with mass transfer (the movement of molecules and particulates) and physiological processes may relate to caries. TYPES OF STUDIES REVIEWED: The authors reviewed reports in the microbiology and dental literature addressing microbiological, engineering and clinical aspects of biofilms with respect to mass transport and microbial physiology, with an emphasis on fluoride ions (F(-)). CONCLUSIONS: and Practical Implications. These data illustrate how dental plaque biofilms may affect the delivery of cariogenic agents, such as sucrose, or anticariogenic agents, such as F(-), into and out of the biofilm, with subsequent consequences for the development of physio-chemical microenvironments at the tooth surface. Increasing the flow rate in an overlying fluid (such as saliva or mouthrinse) increases transport from the fluid into and through biofilms. Increasing the delivery of anticariogenic agents such as F(-) into the plaque biofilm, by generating strong fluid flows, may be a useful strategy for enhancing the anticaries effects of F(-) in areas of the mouth where complete biofilm removal is not possible with routine daily cleaning techniques.     

结核分枝杆菌phoS2基因在大肠埃希菌中的高效表达及其产物抗原性分析

目的在大肠埃希菌中高效表达结核杆菌phoS2,通过免疫印迹反应初步鉴定重组蛋白的抗原性和特异性。方法采用DNA重组技术构建结核分枝杆菌phoS2抗原表达载体,用双酶切和PCR等方法鉴定转化子,重组质粒转化大肠埃希菌,诱导表达phoS2;用SDS-PAGE初步鉴定其表达量;将表达产物进行纯化;重组蛋白用Western blot分析其抗原性和特异性。结果phoS2基因在大肠埃希菌中得到高效表达,表达量占全菌蛋白的40％以上;重组蛋白与结核病患者血清标本呈强阳性反应,与健康人血清标本呈阴性反应。结论重组phoS2蛋白在大肠埃希菌中主要以包涵体形式表达,有很好的抗原特异性和免疫原性,对结核病诊断有潜在的应用价值。