Tertiary structure and energy coupling in Ca2+-pump system

Europium luminescence from europium bound to sarcoplasmic reticulum (Ca²⁺ Mg²⁺)-ATPase indicates that there are two high affinity calcium binding sites. Furthermore, the two calcium ions at the binding sites are highly coordinated by the protein as the number of H₂O molecules surrounding the Ca²⁺ ions are 3 and 0.5. In the presence of ATP, calcium ions are occluded even further down to 2 and zero H2O molecules, respectively. The Ca²⁺ - Ca²⁺ intersite distance is estimated to be 8–9 Å and the average distance from the Ca²⁺ sites to CrATP is about 18 Å.Digestion of the (Ca²⁺ + Mg²⁺)-ATPase at the T₂ site (Arg 198) causes uncoupling of Ca²⁺-transport from ATPase activity while calcium occlusion due to E₁-P formation remains unchanged. Further tryptic digestion beyond T₂ and in the presence of ATP diminishes Ca²⁺ occlusion to zero while 50% of the ATPase hydrolytic activity remains. Tryptic digestion beyond T₂ and in the absence of ATP diminishes ATPase hydrolytic activity to 50% of normal while Ca²⁺ occlusion remains intact. These data are consistent with a mechanism in which the functional enzyme must be in the dimeric form for occlusion and calcium uptake to occur, but each monomer can hydrolyze ATP.     

An automated framework to quantify areas of regional ischemia in retinal vascular diseases with OCT angiography

In this observational and cross‐sectional study, capillary nonperfusion (CNP) and vascular changes in branch retinal vein occlusion (BRVO, sample size [n] = 26) and choroidal neovascularization (CNV, n = 29) were evaluated. Subjects underwent imaging using Optical coherence tomography angiography (Angiovue OCTA, RTVue XR, Optovue Inc., Fremont, California). Local fractal analysis was applied to the OCTA images of superficial, deep and choriocapillaris layer. CNP area (BRVO eyes) and vascular parameters were computed using local fractal‐based method. Sensitivity and specificity of vascular parameters were assessed with receiver operating characteristics curve. Automated CNP area showed excellent agreement with manually quantified CNP areas in both superficial (intraclass coefficient [ICC] = 0.96) and deep (ICC = 0.96) layers. BRVO eyes showed significantly altered (P < .05) vascular parameters in both superficial and deep layer as compared to normal eyes (n = 30). CNVM eyes had significantly higher capillary free zones (P < .001) as compared to normal eyes. In normal vs BRVO eyes, vessel density and spacing between the large vessels had similar area under the curve (AUC) (P > .05) in both superficial (0.97 and 0.97, respectively) and deep layer (0.99 and 0.98, respectively). Further, capillary free zones showed high AUC (0.92) in differentiating CNV eyes from normal eyes.      

Quetiapine attenuates spatial memory impairment and hippocampal neurodegeneration induced by bilateral common carotid artery occlusion in mice

Quetiapine, a new atypical antipsychotic drug, has beneficial effects on cognitive impairment and neuropathological changes in treating chronic neurodegenerative diseases. Our previous studies have demonstrated that quetiapine may have neuroprotective properties. In the present study, we investigated the effects of a 2-week pre-administration of quetiapine (10 mg/kg/day, i.p.) on spatial memory impairment and hippocampal neurodegeneration induced by 60-minute bilateral common carotid artery occlusion (CCAO). Following a 7-day recovery phase from CCAO, the spatial memory of the mice was tested using a modified water maze test. After the behavioural test, the mice were sacrificed and brain sections were stained with NeuN (a neuron-specific soluble nuclear antigen), cresyl violet (Nissl), and Fluoro-Jade B. CCAO significantly induced spatial memory impairment and caused neurodegeneration in the hilus of hippocampus, while quetiapine significantly attenuated these changes. This is the first study showing that quetiapine significantly attenuates CCAO-induced spatial memory impairment and this improvement parallels the alleviative effects of quetiapine on CCAO-induced neurodegeneration in the hilus of hippocampus. The results suggest that quetiapine may have defending effects on the impairments induced by cerebral ischemia, which enhances our understanding about the mechanisms of quetiapine.     

Protective effect of cerebrocrast on rat brain ischaemia induced by occlusion of both common carotid arteries

Diabetes mellitus is accompanied by several cardiovascular complications including atherosclerosis, cerebral ischaemia and stroke. We examined the neuroprotective effect of a 1,4-dihydropyridine derivative cerebrocrast (C, a new antidiabetic agent, synthesized in the Latvian Institute of Organic Synthesis) on the level of ATP in the brain, and on changes of the EEG and ECG, as well as blood pressure parameters in anaesthetized Wistar male rats before and during 10-min occlusion of both common carotid arteries. Cerebrocrast was administered i.v. at doses of 1.0 and 10 microg/kg in the v. femoralis 20 min prior to ischaemia. After 10-min ischaemia animals were decapitated and the brain was immediately frozen in liquid nitrogen and subsequently used for analysis of changes of ATP contention. Cerebrocrast, administered at doses of 1.0 and 10 microg/kg 20 min prior to occlusion of both common carotid arteries, completely prevented a fall in the ATP content of brain compared with the control rats. In control rats the content of ATP in brain during ischaemia decreased from 2.77 +/- 0.22 (basal level) to 1.74 +/- 0.20 micromol/g as a result of ischaemia. By administration of cerebrocrast 20 min before occlusion of the arteries, the content of ATP in the brain remained at the level of preischaemia (1.0 microg/kg C + ischaemia 2.82 +/- 0.36; 10 microg/kg C + ischaemia 2.42 +/- 0.22 micromol/g). Analysis of EEG parameters both before and during 10 min of occlusion showed that at a C dose of 1.0 microg/kg before occlusion produced a regular alpha rhythm during ischaemia and prevented cerebral bioelectric activity from significant changes. The depression of basal rhythm was observed at a C dose of 10 microg/kg during ischaemia in two rats out of six as well as an increase in the ECG ST segment above the isoelectric line. Blood pressure was decreased by about 10-20 mm Hg. We propose that pretreatment of rats with cerebrocrast at doses of 1.0 or 10 microg/kg 20 min prior to ischaemia can prevent ischaemic damage of rat brain, maintain necessary energy consumption, promote ATP production in brain cells, and prevent significant changes in EEG and ECG parameters. These properties are important in diabetes mellitus and its evoked cardiovascular complications as stroke, ischaemia, etc.     

P2X4 receptors expressed on microglial cells in post-ischemic inflammation of brain ischemic injury

Post-ischemic inflammation is an essential step in the progression of brain ischemia injury. P2X4 receptors are the predominant purinergic P2X receptor subtypes expressed on immune and neural cells. The subtype traffic between intracellular compartments and the plasma membrane form protein interactions with each other to regulate ATP-dependent signaling. The P2X4 receptors expressed on microglial cells have been reported to be involved in the inflammatory response of many central nervous system diseases. However, the mechanism that activates microglial cells and the role of P2X4 receptor expressed in microglial cells in the ischemic brain remains to be clarified. Here we provide a review for understanding and exploring converging lines of evidence for involvement of P2X4 receptors expressed on microglial cells in the post-ischemic inflammation in the brain ischemic injury.     

常压氧与高压氧对成年大鼠脑缺血再灌注损伤后 微血管新生影响的比较

目的:研究常压氧与高压氧对成年大鼠脑缺血再灌注损伤后微血管新生影响的差异。方法:将成年SD雄性大鼠随机分为三组:假手术组(SS组)、常压氧治疗组(NBO组)、高压氧治疗组(HBO组),每组又随机分为3、7、10天三个亚组。采用线栓法对NBO组和HBO组大鼠进行大脑中动脉栓塞(MCAO),缺血1.5小时后拔出栓子再灌注,NBO组进行常压氧治疗,HBO组进行高压氧治疗。大鼠分别在3、7、10天麻醉处死,取脑组织切片,血管内皮生长因子(VEGF)、VEGF受体-1(FLT-1)和CD34免疫组化染色,光镜观察取图和统计分析。结果:NBO各组与SS各组相比,VEGF、FLT-1和CD34阳性细胞数目均明显增多(P<0.05);HBO各组与NBO各组比较,7天、10天组VEGF、FLT-1和CD34阳性细胞数目均显著增多(P<0.05)。结论:HBO治疗较NBO治疗对成年大鼠微血管的新生更有促进作用。     

The utility of far‐infrared illumination in oxygenation dynamics as measured with near‐infrared spectroscopy

Near‐infrared spectroscopy (NIRS) is a noninvasive method for measuring the oxygenation in muscle and other tissues in vivo. For quantitative NIRS measurement of oxygenation dynamics, the vessel‐occlusion test was usually applied as physiological intervention. There are several drawbacks of the vessel‐occlusion method that include skin contact, uncomfortable and microcirculation block of patients. Thus, we propose the far‐infrared (FIR) illumination as a new physiological intervention method in this paper. Our preliminary result shows a linear correlation of oxygenation dynamic signals between FIR illumination and arterial‐occlusion test (AOT) that implies the FIR illumination could be applied for hemodynamic response measurement in clinical diagnosis. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The long road to understanding the baculovirus P10 protein

The baculovirus P 10 protein has always represented a mystery in the feld of insect virology. Like the baculovirus polyhedrin protein it is expressed at high levels very late in infection. Homologues of the Autographa californica nucleopolyhedrovirus plO gene are conserved in all Alphabaculoviruses and in other viruses of lepidopteran hosts yet is completely dispensable for virus replication and transmission. P10 is a microtubule interacting protein whose expression has been associated with the formation of a variety of complex and extensive cytoplasmic and nuclear structures. P10 has been associated with a number of roles during infection ranging from the formation of virus occlusion bodies, to affecting the rate of cellular and/or nuclear lysis during the final stages of the virus replication cycle. In this article we review recent work aimed at understanding the role of this enigmatic protein, putting them into context with recent advances in understanding of protein structure and function. We look back at a number of historical studies and observations, reanalysing their conclusions based on recent data and our own observations. The role of the P 10 protein during baculovirus replication remains elusive, however, novel avenues of investigation have been identified that will, we are sure, eventually lead to an understanding of this protein.