Na+ channel expression and neuronal function in the Na+/H+ exchanger 1 null mutant mouse

Mice lacking Na(+)/H(+) exchanger 1 (NHE1) suffer from recurrent seizures and die early postnatally. Although the mechanisms for seizures are not well established, our previous electrophysiological work has shown that neuronal excitability and Na(+) current density are increased in hippocampal CA1 neurons of these mutant mice. However, it is unknown whether this increased density is related to altered expression or functional regulation of Na(+) channels. In this work, we asked three questions: is the increased excitability limited to CA1 neurons, is the increased Na(+) current density related to an increased Na(+) channel expression, and, if so, which Na(+) channel subtype(s) is upregulated? Using neurophysiological, autoradiographic, and immunoblotting techniques, we showed that both CA1 and cortical neurons have an increase in membrane excitability and Na(+) current density; Na(+) channel density is selectively upregulated in the hippocampus and cortex (P < 0.05); and Na(+) channel subtype I is significantly increased in the hippocampus and Na(+) channel subtype II is increased in the cortex. Our results demonstrate that mice lacking NHE1 upregulate their Na(+) channel expression in the hippocampal and cortical regions selectively; this leads to an increase in Na(+) current density and membrane excitability. We speculate that neuronal overexcitability due to Na(+) channel upregulation in the hippocampus and cortex forms the basis of epileptic seizures in NHE1 mutant mice.     

The myogenic response in isolated rat cerebrovascular arteries: vessel model

We develop an integrated model of isolated rat arterial resistance vessel (RV), which can simulate its major property of myogenic response. The vascular smooth muscle cell is an important component of the wall of this vessel, and serves as a vasomotor organ providing the active tension generation that underlies the myogenic response of the wall to stretch. In the previous study, we focused on the development of a smooth muscle cell model that can mimic the strain-sensing and force-generating features of the myogenic mechanism. In the current model, we embed this cell model in a larger vessel wall configuration, and couple the time course of cellular contractile activation to macroscopic changes in vessel diameter. The integrated model is used to mimic published pressure-vessel diameter data obtained from isolated RVs that are mounted in a hydraulic test apparatus. The model provides biophysically based insights into the myogenic mechanism as it responds to changes in transmural pressure, in the presence and absence of Ca2+ blockers applied to the bathing fluid.It mimics measured data very well and provides a model that is able to link events at subcellular level to macroscopic changes in vessel diameter. The model initiates a mechanistic approach to investigate myogenic response, which has not been taken previously by any other models.     

不同结合状态硫酸软骨素多糖链对体外二维三维培养背根节神经突起生长影响研究

目的构建鸡胚背根节细胞3D生长模型,观察CSPG对不同浓度的琼脂糖水溶胶培养基对鸡胚背根节神经突起生长的影响。方法①利用多肽缩合剂1’1羰基二咪唑介导CS-B长链与琼脂糖凝胶共价结合。②分别配制0.5%、0.75%、1%、1.25%、1.5%的SeaPrep琼脂糖凝胶溶液和共价结合了CS-B多糖长链的琼脂糖凝胶溶液。取孵育9~10天后鸡胚背根节加入上述凝胶溶液加培养液培养。③培养24小时之后在24 h、48 h7、2 h、96 h进行观察拍照。观察各时间点神经突起生长情况。结果①鸡胚背根节神经突起在1.25%的琼脂糖凝胶溶液中开始呈3D生长,在小于1%的琼脂糖溶液中只能2D生长。②在同一时间点,呈2D生长的背根节突起和呈3D生长的背根节突起在突起长度方面没有统计学差异(P>0.05)。③3D生长的DRG神经突起在共价结合了CS-B的琼脂糖凝胶中生长长度明显短于普通琼脂糖水凝胶(P<0.05),并且可观察到部分突起长出短而直的成束突起。但是对于呈2D生长的DRG突起长度在两种培养基中却未见差异(P>0.05)。结论鸡胚背根节神经元周围突起生长长度在3D培养中与在2D培养中有没有明显的差异。硫酸软骨素能够有效抑制呈3D生长的神经节突起生长,并且影响到神经突起的生长方式。但是在2D培养基中,未能看到上述的抑制作用。     

尺动脉腕背支升支皮瓣的应用解剖学研究

目的　为临床应用尺动脉腕背支升支皮瓣修复手部创面 ,提高治疗效果提供解剖学基础。方法　用新鲜成人男性上肢标本 1 6侧 ,采用显微解剖学技术 ,对尺动脉腕背支升支的起始、走行、分支及分布进行解剖学观察和测量。结果　尺动脉腕背支起始于尺动脉的尺侧 ,距豌豆骨上方 4 2 .6 0± 8.2 0mm ,起始处外径1 .4 6± 0 .32mm ,长 1 1 .4 6± 8.2 0mm。尺动脉腕背支与尺神经手背支伴行 ,穿过尺侧腕屈肌腱的深面 ,从掌侧向后内侧斜行 ,两者成锐角 ,平均 38.6 0± 8.2 0°,行至 1 1 .4 6mm处分为升支与降支。升支穿深筋膜进入皮下组织 ,沿前臂内侧缘上行 1 2 2 .4 0± 1 3.80mm处再分为细小分支 ,升支起始部的外径为 0 .6 2± 0 .2 8mm。结论　尺动脉腕背支升支皮瓣是以尺动脉腕背支升支为蒂 ,可在前臂尺侧设计大面积岛状皮瓣 ,通过转位修复腕部和手部创伤及挛缩瘢痕切除术后的创面 ,不牺牲前臂主要血管 ,手术操作易于掌握     

Secretion of electrolytes by the pancreas of the anaestetized rat.

1. HCO-3, Na+ and K+ concentrations were measured in bile-free pancreatic juice collected from fasted and fed anaesthetized rats. 2. Resting flow rates averaged 0.62 mul. g-1 .min-1 (fasted) and 2.8 mul. g-1. min-1 (fed) and the mean HCO-3 concentrations, respectively, were 25.8 and 33.3 mM. 3. In fasted rats, instillation of HCl into the duodenum caused flow rate to increase threefold and HCO-3 concentrations to double (66 mM). Intravenous infusion of pure natural (GIH) secretin caused a fivefold increase in flow rate; HCO-3 concentrations, again, doubled (67.5 mM). Infusion of synthetic secretin produced effects essentially the same as those produced by GIH secretin. 4. Infusion of Boots secretin caused a thirteenfold increase in flow rate (8.32 mul.g-1. min-1) but HCO-3 concentrations rose only slightly (43.3 mM). However, following cessation of infusion, when flow rate approximated the maximum obtained with pure secretin, the HCO-3 concentration was much higher (57.2 mM at 3.19 uml.g-1.min-1). In fed animals the responses were similar but maximum flow rates were greater (12 mul. g-1. min-1). 5. Infusion of caerulein produced a secretory rate slightly less than with Boots secretin (5.06 mul. g-1.min-1) and HCO-3 concentrations were plasmalike (30.2 mM); infusion of the synthetic octapeptide of cholecystokinin (OP-CCK) gave similar flow rates and HCO-3 concentrations. 6. Infusion of a mixture of caerulein and GIH secretin mimicked closely the effect of Boots secretin. At maximum flow rates (7.6 mul. g-1. min-1) the HCO-3 concentration was 43.7 mM and at lower flow rates (3.90 mul.g-1. min-1) it rose to 54.2mM. 7. It is concluded that the response of the rat pancreas to secretin is qualitatively similar to that of all other vertebrates so far studied, but, relative to other animals, the response is sluggish. In contrast, the rat pancreas responds well to cholecystokinin (CCK) stimulation, yielding a juice with plasma-like HCO-3 concentration. Boots secretin, which is heavily contaminated with CCK, causes a mixed response resembling that of CCK at high secretory rates and that of pure secretin at lower rates. 8. An unexplained feature of rat pancreatic juice was that K+ concentrations, although plasma-like in unstimulated samples, rose to about 8mM when flow rate increases as a result of secretin, but not CCK, stimulation. In all other animals so far studied, the K+ concentration has been found to be independent of flow rate.     

Safety and efficacy of Salmonella gallinarum 9R vaccine in young laying chickens.

Salmonella enterica subsp. enterica serovar Gallinarum (S. gallinarum) is the agent of fowl typhoid, and the 9R vaccine is a commercially available, live vaccine for the prevention of fowl typhoid. The aim of this study was to assess the safety and efficacy of the 9R vaccine in young chickens. The mean weights of 5-week-old chickens vaccinated with one and 10 doses at 2 weeks old were 450.3+/-33.83 g and 446.8+/-35.68 g, respectively, which were statistically lower (P<0.05) than the mean weight (475.5+/-44.17 g) of the control group. Using the same procedure, the mean weights of chickens vaccinated with one and 10 doses at the age of 4 and 6 weeks were 721.3+/-64.03 g and 723.7+/-63.92 g, and 1114.2+/-92.21 g and 1078.27+/-68.93 g, respectively. Compared with the mean weights (725.7+/-49.50 g and 1104.3+/-92.34 g, respectively) of the control groups, there was no difference in terms of statistical significance (P < 0.05). In addition, all vaccinated birds showed no clinical signs and survived the time course of the experiment. When all chickens were challenged with the wild-type S. gallinarum 21 days after one-dose vaccination, the mortalities between the vaccinated group and the control group were 0% to 5% and 95% to 100%, respectively. In addition, the control group demonstrated a 95% to 100% re-isolation rate of the challenge strain in internal organs and the caecum, while in the vaccinated group only a 1% to 60% re-isolation rate was observed. In this study, we showed that adjusting the minimum vaccination age of the 9R vaccine to 4 weeks is acceptable considering the safety and efficacy of the vaccine.     

Mammalian transforming growth factor beta1 activated after ingestion by Anopheles stephensi modulates mosquito immunity

During the process of bloodfeeding by Anopheles stephensi, mammalian latent transforming growth factor beta1 (TGF-beta1) is ingested and activated rapidly in the mosquito midgut. Activation may involve heme and nitric oxide (NO), agents released in the midgut during blood digestion and catalysis of L-arginine oxidation by A. stephensi NO synthase (AsNOS). Active TGF-beta1 persists in the mosquito midgut to extended times postingestion and is recognized by mosquito cells as a cytokine. In a manner analogous to the regulation of vertebrate inducible NO synthase and malaria parasite (Plasmodium) infection in mammals by TGF-beta1, TGF-beta1 regulates AsNOS expression and Plasmodium development in A. stephensi. Together, these observations indicate that, through conserved immunological cross talk, mammalian and mosquito immune systems interface with each other to influence the cycle of Plasmodium development.     

Neural progenitor cells lack immunogenicity and resist destruction as allografts

Multipotent, self-renewing stem and progenitor cells isolated from the mammalian central nervous system (CNS) have been shown to survive as allografts following transplantation to sites throughout the neuraxis. However, studies of this type shed little light upon the immunologic properties of the cells themselves, primarily because little is learned about the intrinsic immunogenic properties of a cell when it is grafted into an immune-privileged site. We have therefore investigated the immunogenic and antigenic properties of CNS progenitor cells by grafting them into a conventional (i.e., non-immune-privileged) site, namely, beneath the kidney capsule. Our results indicate that allogeneic CNS progenitor cells survive at least 4 weeks in a conventional site, during which time they neither sensitize their hosts nor express detectable levels of major histocompatibility complex (MHC) class I or II. These in vivo data are in accord with flow cytometric results showing that CNS progenitor cells do not express MHC class I or class II, either at baseline or upon differentiation in 10% serum. Exposure to interferon gamma, however, reversibly upregulates expression of these key transplantation antigens. Together, these results reveal CNS progenitor cells to possess inherent immune privilege. Since CNS progenitor cell allografts were rejected beneath the kidney capsule following specific sensitization of the host, CNS progenitor cells were able to display alloantigens, albeit not in an immunogenic form.     

Discrimination of single-copy IS6110 DNA fingerprints of Mycobacterium tuberculosis isolates by high-resolution minisatellite-based typing

Seven isoniazid-resistant isolates with mutations in the NADH dehydrogenase (ndh) gene were molecularly typed by IS6110-based restriction fragment length polymorphism analysis. All seven isolates with the R268H mutation had identical 1.4-kb IS6110 fingerprints. High-resolution minisatellite-based typing discriminated five of these isolates; two isolates were identical.