The cell cycle: a new entry in the field of Ca2+ signaling

Ca²⁺ signaling plays a crucial role in virtually all cellular processes, from the origin of new life at fertilization to the end of life when cells die. Both the influx of external Ca²⁺ through Ca²⁺-permeable channels and its release from intracellular stores are essential to the signaling function. Intracellular Ca²⁺ is influenced by mitogenic factors which control the entry and progression of the cell cycle; this is a strong indication for a role of Ca²⁺ in the control of the cycle, but surprisingly, the possibility of such a role has only been paid scant attention in the literature. Substantial progress has nevertheless been made in recent years in relating Ca²⁺ and the principal decoder of its information, calmodulin, to the modulation of various cycle steps. The aim of this review is to critically discuss the evidence for a role of Ca²⁺ in the cell cycle and to discuss Ca²⁺-dependent pathways regulating cell growth and differentiation. Received 2 March 2005; received after revision 9 May 2005; accepted 24 May 2005     

中华绒螯蟹感光细胞细胞器中的钙离子

用焦锑酸钙沉淀方法对中华绒螯蟹复眼感光细胞的钙离子在亚细胞水平上的分布进行了观察，结果发现细胞的膜下储泡囊、线粒体、多囊体和色素颗粒等细胞器都有焦锑酸钙的沉淀，当感光细胞处于暗适应时细胞器中焦锑酸钙沉淀的量明显多于光适应时细胞中的量，改变细胞外的钙离子浓度也会影响到这些细胞器中钙离子储存量．实验表明，膜下储泡囊、线粒体、多囊体，色素颗粒等储存的钙离子一起参与造成了感光细胞的光适应．     

Influence of PPCA inhibitor on CaCO3 scale surface deposition and bulk precipitation at elevated temperature

Scale formation is a serious and costly problem encountered in the oil and gas industry. Polyphosphinocarboxylic acid (PPCA) is a common commercial organic scale inhibitor used in the oil and gas industry which is normally referred to a nucleation inhibitor. In this paper, the effect of PPCA on calcium carbonate scale is studied systematically and some new insights into the mechanisms of PPCA inhibition are given. Traditionally, the studies of scale formation and inhibition have focused on bulk precipitation or surface deposition. Few studies have focused on the difference between surface deposition and bulk precipitation processes. In this paper, the effect of PPCA inhibitor on calcium carbonate scale formation is studied both in the bulk solution and on the metal surface in supersaturated scale formation solutions which represent typical waters encountered in oil and gas production. It is clear that PPCA inhibits both bulk precipitation and surface deposition but to a different degree. At 4 ppm PPCA, the inhibition efficiency of surface deposition is greater than the inhibition efficiency of bulk precipitation. It is assumed that the inhibitor film formed on the metal surface at the highest concentration of PPCA (4 ppm) prevent the adsorption of scale crystals on the metal surface. In addition, PPCA suppresses aragonite and calcite crystal formation and results in the least stable vaterite crystal dominating the scale.     

磷酸氢钙生产中一步脱氟工艺的研究

详细讨论了磷酸氢钙生产中的脱氟工艺条件.由文献的两步脱氟改进为一步脱氟,氟残留量完全符合国家标准,而且产率相当理想,平均为63%,在实验室及工厂化生产中都取得了很好的结果.     

钙制剂的化学活性和生物学活性

用电化学方法研究了钙制剂的化学活性,通过钙在大鼠肠内吸收特性的研究,证明了化学活性和生物学活性的一致性。两者对钙剂评价结果完全一致。实验结果表明,活性钙具有出色的离子化百分率,其活性远远高于其它钙制剂。不同工艺生产的活性钙,其活性基本相同。和传统的“代谢法”相比,本方法不仅具有快速、准确等特点,而且不必通过人体或动物实验,就可以得到满意的结果。     

Evidence for suppression of Na-dependent Ca2+ efflux from rat brain synaptosomes by ovarian steroids in vivo

Summary The possibility that intracellular Ca²⁺, which mediates neurotransmitter release, regulation of membrane permeability, microtubule polymerization and axonal transport, is influenced by gonadal steroids via a Na–Ca exchange mechanism was examined. The resting Ca²⁺ uptake into synaptosomes was measured using crude synaptosomal pellets (P₂ fraction), isolated from the brain stem, mesencephalic reticular formation (MRF), nucleus caudatus (NC) and the hippocampus of intact, long-term ovariectomized (OVX) and OVX plus progesterone (P) or estradiol-17 benzoate (EB) treated adult female rats. Irrespective of the brain structure investigated, the uptake was 1) markedly increased in synaptosomes from OVX animals in comparison to intact controls, and 2) reduced to near control values in synaptosomes from OVX rats treated s.c. with a single dose of 2 mg P or 5 g EB. Since Ca²⁺ influx into synaptosomes was shown earlier to depend on external sodium concentration, which was the same in all experiments described in this work, the results obtained indicate that ovarian steroids modulate basal synaptic activity in the rat brain by suppressing Na-dependent Ca²⁺ efflux from the nerve cell.     

球形催化剂中钙的测定

本文利用钙离子选择性电极的高选择性，建立了在大量Ｆｅ￣（３＋）存在下测定钙的新分析方法。该法仪器简单、操作方便、快速，电极响应范围为Ｃａ￣（２＋）浓度在１．００Ｘ１０￣（－４）～１．００Ｘ１０￣（－２）ｍｏｌ．Ｌ￣（－１）之间，检测限为８．０Ｘ１０￣（－７）ｍｏｌ．Ｌ￣（－１）。对球形催化剂中钙的测定，回收率为８６．ｏ％～８９．ｏ％，ＲＳＤ为０．９０９％和１．０３％     

蚯蚓钙结合蛋白的分离纯化及性质的研究

以赤子爱胜蚓为材料分离纯化了钙调素，并得到一种新的钙结合蛋白经ＳＤＳ－ＰＡＧＥ，ＰＡＧＥ和等电聚焦电泳鉴定，这两种蛋白均表现为一。ＣａＭ分子量为１８．９ｋＤ，ＮＣＢＰ为１６ｋＤ，等电点分别为３．６和４．３，两种蛋白具有不同的肽谱。     

燃煤沸腾炉高温脱硫剂的试验研究

论述了新型硅酸钙脱硫剂的成分筛选及其在沸腾炉内的变工况试验结果。试验表明,硅酸钙脱硫剂的最佳脱硫温度为950℃左右,与高硫无烟煤在沸腾床内的最佳燃烧温度(950—1000℃)相吻合;在Ca/S摩尔比小于2.0时,脱硫效率可达95%。