乳牛钙、磷代谢障碍性疾病的诊断:用X线拍片法作掌骨皮髓宽度比测定

对两组临床健康的黑白花乳牛35头(1组19头、2组16头)作右掌骨侧位X线拍片,测其掌骨中部皮髓宽度比。其结果是,1、2两组皮髓宽度比平均值分别为1.56±0.174和1.0257±0.1556。两组之间相差0.1303,经t检验差异显著(P<0.05)。2组16头乳牛中有6头乳牛的皮髓宽度比低于1.0,占2组乳牛总数的37.5％。追寻其原因;主要是两组饲喂的日粮有所不同,特别是钙、磷比例差异极大。1组钙、磷比例为1.5:1,二组为1:12。据此,作者认为用X线拍片法作掌骨皮髓宽度比的测定,不仅能作为诊断钙、磷代谢障碍性疾病的一个可靠指标,且可作为生产上预测钙、磷代谢障碍的手段。     

偏最小二乘分光光度法同时测定牛乳中的钙和镁

以偶氮安替比林Ⅲ(简称ApⅢ)为显色剂，在生物酸度pH=7．3下，用偏最小二秉分光光度法研究了在实验条件下吸收光谱严重重叠时，实验模型的预报能力，并同时测定了牛奶中的钙、镁离子。结果表明，方法的准确度较好，结果令人满意。     

分光光度法同时分析环境水样中钙镁含量

本文将计算数学与分光光度法相结合,采用酸性铬蓝K为显色剂在氨性条件下(pH10)对水样中的钙、镁含量进行了测定,用反推矩阵计算法计算钙、镁各自浓度,方法简单有效.     

三元络合物在络合滴定中的应用──石灰石中钙镁的联合测定

本文研究了用乙酰丙酮掩蔽镁，以二甲酚橙──化十四烧基呲啶（简称ＸＯ—ＴＰＢ，以下同）作指示剂，在ｐＨ＝１０．５氨性缓冲溶液中，用ＥＤＴＡ联合测定钙镁的条件     

体外ELF电磁场对肝细胞Ca2+生理浓度变化的影响

研究了ELF电磁场对细胞游离Ca2 浓度的影响。分别通过(a)从单个肝细胞内钙离子振荡的动力学模型出发,以细胞膜上IP3受体浓度作为作用因子的数值计算和(b)ELF电磁场对细胞作用的实验结果分析电磁场对细胞游离Ca2 浓度的影响。结果表明:钙振荡的周期与IP3受体的浓度成非线性关系,外加ELF电磁场影响胞内钙振荡的周期和胞浆Ca2 浓度:强度为53v/m、频率为16Hz、45Hz和频率为16Hz、强度为80v/m的电磁波可使细胞胞浆Ca2 浓度上升明显,有显著统计学意义,强度为53v/m、频率为32Hz和60Hz和频率为16Hz、强度为26v/m的电磁波作用后细胞胞浆Ca2 浓度上升不明显,无统计学意义。     

Doping inorganic ions to regulate bioactivity of Ca –P coating on bioabsorbable high purity magnesium

Performance of biomaterials was strongly affected by their surface properties and could be designed artificially to meet specific biomedical requirements. In this study, F(F), Si O2 4(Si), or HCO 3(C)-doped Ca–P coatings were fabricated by biomimetic deposition on the surface of biodegradable high-purity magnesium(HP Mg). The crystalline phases, morphologies and compositions of Ca–P coatings had been characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM) and energy-dispersive spectroscopy(EDS). The biomineralization and corrosion resistance of doped Ca–P coatings had also been investigated. The results showed that the Ca–P coating with or without doped elements mainly contained the plate-like dicalcium phosphate dehydrate(DCPD) phase. The doped F, Si, or C changed the surface morphology of Ca–P coatings after mineralization. Doped F enhanced the mineralization of Ca–P coating, and doped Si retarded the mineralization of Ca–P coating.However, H2 evolution of HP Mg discs with different Ca–P coatings was close to 0.4–0.7 ml/cm2 after two-week immersion. That meant that the corrosion resistance of the Ca–P coatings with different or without doped elements did not change significantly.     

A dynamic model of calcium signaling in mast cells and LTC4 release induced by mechanical stimuli

Mast cells （MCs） play an important role in theimmune system. It is known that mechanical stimuli caninduce intracellular Ca2＋ signal and release a variety ofmediators, including leukotriene C4 （LTC4）, leading toother cellular and physiological changes. In this paper, wepresent a mathematical model to explore signalling path-ways in MCs, by including cellular mechanisms for intra-cellular Ca2＋ increase and LTC4 release in response tomechanical stimuli, thapsigargin （TG, SERCA pumpinhibitor）, and LTC4 stimuli. We show that （i） mechanicalstimuli activate mechano-sensitive ion channels and induceinward ion fluxes and Ca2＋ entry which increases intra-cellular Ca2＋ concentration and releases LTC4; （ii） TGinhibits SERCA pumps, empties the internal Ca2＋ stores,which activates Ca2＋ release-activated Ca2＋ channels andresults in sustained intracellular Ca2＋ increase; and （iii）LTC4 activates receptors on MCs surface and increasesintracellular Ca2＋ concentration. Our results are consistentwith experimental observations, and furthermore, they alsoreveal that mechanical stimuli can increase intracellularCa2＋ even when LTC4 release is blocked, which suggests afeed forward loop involved in LTC4 production. This studymay facilitate our understanding of the mechanotransduc-tion process in MCs and provide a useful modeling tool forquantitatively analyzing immune mechanisms involvingMCs.     

Calcium carbonate nanoparticles promote osteogenesis compared to adipogenesis in human bone-marrow mesenchymal stem cells

Rhombohedron-like and fusiform calcium carbonate nanoparticles were fabricated using a new method. Their geometry was controlled by varying the mixing speed and ratio of ethanol versus water in reaction system. The calcium carbonate nanoparticles(CCNPs) have slight effect on viability of human bone-marrow mesenchymal stem cells(hBMSCs) with dose-dependent and shape-dependent, but they can significantly promote osteogenic differentiation of hBMSCs in vitro by 10–37% increase of alkaline phosphatase(ALP) activity, 9–36% growth of collagen secretion and 1.13–1.83 folds upregulation of osteogenesis-related genes, even at lower dose ranges(5–20 μg/ml). The efficacity of promoting osteogenesis depends on the shape and dose of CCNPs. Furthermore,adipogenesis was inhibited by less accumulation of lipid droplets, lower triglyceride(TG) secretion and downregulation of adipogenesis-related genes. These findings improve the understanding of effects CCNPs on hBMSCs fate towards osteoblasts or adipocytes and have meaningful impact for combining use of CCNPs and hBMSCs in tissue engineering and regenerative medicine fields.     

饲料中的钙磷含量与河蟹生长的关系

在水族箱中用体重２９－３３ｇ的中华绒螯蟹蟹种对配合饲料中适宜的钙磷含量进行了研究。磷分设３个水平：１．２％,１．７％和２．２％;钙分设３个水平;１．５％,２．２％和２．９％。水体中钙含量为４０．５ｍｇ／Ｌ,磷为０．０４ｍｇ／Ｌ。试验全期２７ｄ,以蟹体生长、生长比率（ＳＧＲ）、蛋白质效率（ＰＥＲ）和饲料系数（ＦＣＲ）作为试验指标。结果表明,饲料中适宜的钙磷含量分别为２．９％和１．７％,钙磷比为１．７     

火焰原子吸收光谱法测定Mn_3O_4产品中钙镁含量

用盐酸加热溶解四氧化三锰样品 ,加入镧盐和锶盐混合释放剂 ,消除 70 %左右基体锰的干扰 ,直接测定其中钙、镁含量 ,样品加标回收率为 96 8%～ 98 2 % ,相对标准偏差为 2 4%～ 3 2 % .