P2X receptor-mediated muscle pressor reflex in myocardial infarction

A previous report from this laboratory demonstrated that the ATP-sensitive P2X receptor-mediated muscle pressor reflex was augmented in rats with heart failure (HF). The purpose of this study was to better understand the underlying mechanisms for this greater response in HF rats. We examined 1) responsiveness of the P2X receptor to alpha,beta-methylene ATP (alpha,beta-me-ATP), a P2X receptor agonist, in control and HF rats induced by myocardial infarction (MI); 2) the relationship between P2X-induced blood pressure response and left ventricular (LV) function; and 3) the expression of P2X receptors in the dorsal root ganglion (DRG) of control rats and rats with HF. Eight to 14 wk after coronary artery ligation, the severity of the MI was determined by echocardiography. In the first group of the experiment, alpha,beta-me-ATP (0.0625, 0.125, 0.25, and 0.5 mM) was injected into the arterial blood supply of the hindlimb muscles to evoke a pressor response in 17 decerebrated rats (6 controls, 6 small MIs with infarcts of the LV between 10 and 35%, and 5 large MIs with infarcts >35%). The P2X agonist increased blood pressure, and the effect was significantly accentuated in large MI rats compared with small MI rats and control rats. A significant correlation was observed between alpha,beta-me-ATP-evoked pressor response and the LV fractional shortening, an index of LV function. In the second group of the experiment, immunocytochemistry was used to examine the immunoreactivity of P2X receptor in the DRG neurons of small diameter fibers in six healthy control rats, five small MI, and five large MI rats. The percentage of P2X immunostaining-positive neurons in the DRG was markedly greater in large MI rats (52% vs. 29% in controls and 34% in small MIs, P < 0.05). In conclusion, our findings demonstrate that 1) muscle afferent-mediated pressor response of P2X activation was exaggerated in MI animals, and the responsiveness was related to the degree of LV dysfunction; and 2) augmented reflex response was associated with upregulated P2X receptors in the DRG neurons of thin fiber afferent nerves following MI. The data suggest that P2X-mediated responsiveness in the processing of muscle afferent signals may have important implications for understanding cardiovascular responses to exercise in HF.     

以潮霉素B抗性为选择标记的深黄被孢霉原生质体转化

利用亚硝基胍(MNNG)诱变方法筛选了一株深黄被孢霉潮霉素B敏感型菌株M6-22-4。采用PEG介导的方法,将含有E.coli潮霉素B抗性标记的PD4质粒转入敏感株M6-22-4原生质体,并在潮霉素B浓度为400μg/mL的选择培养基上筛选转化子,获得了1.6~2.8个转化子/μg质粒DNA的转化频率。稳定性实验表明,质粒线性化后所获得的转化子在PDA培养基上传代10代以后,转接到选择平板上有31.6%仍具有HmB抗性;随机挑选了3个转化子,通过PCR方法检测到潮霉素抗性基因的存在,Southern杂交发现,潮霉素抗性基因已经以1~2拷贝数整合到深黄被孢霉M6-22-4染色体上,这是深黄被孢霉转化系统的首次报道。     

中国堇菜属美丽堇菜亚属(堇菜科)植物分类学修订

对中国堇菜属美丽堇菜亚属植物进行了系统学修订,确认中国堇菜属美丽堇菜亚属植物共有6种,列出分种检索表,对《中国植物志》51卷中未记载的3种进行了详细的描述,并对塔城堇菜、深紫堇菜及隐距堇菜进行了绘图。     

海南鹦哥岭自然保护区的珍稀濒危植物与保育

对鹦哥岭的珍稀濒危植物进行野外调查表明,本区共有野生分布的珍稀濒危植物79种,隶属于47科71属。其中属于1999年国家重点一级保护4种,如海南苏铁(Cycas hainansis)、坡垒(Hopea hainansis)、台湾苏铁(Cy-cas taiwaniana)和伯乐树(Bretschneidera sinensis),国家二级保护14种。建议将18种列入国家保护名录中,20种列入省级保护名录,其中有30种为海南特有种。鹦哥岭珍稀濒危植物面临的威胁主要有原始森林面积的减少、人为毁林开荒和分布区限制。针对珍稀濒危植物的现状和受到的威胁,提出了应重点加强保护的6个地点及相应的保护对策和建议。     

银杏叶提取物的微生物转化研究Ⅲ．转化产物的化学成分

为研究银杏叶提取物经微生物转化后的化学成分,采用微生物转化的方法对银杏叶提取物进行处理得到转化粗提物,采用硅胶、Sephadex^TM LH-20凝胶等色谱技术对转化粗提物进行分离纯化,通过波谱分析单体结构鉴定。结果发现,从银杏叶提取物的转化粗提物中分得5个化合物,分别为异鼠李素（isorhamnetin,1）、山奈酚（kaempferol,2）、斛皮素（quercefin,3）、山奈酚-3-O-α-L-鼠李糖苷（kaempferol-3-O-α-L-rhamnosid,4）、斛皮素-3-O-α-L-鼠李糖苷（quercetin-3-O-α-L-rhamnosid,5）。结果表明,这是首次用微生物转化的方法对银杏叶提取物进行处理。     

耐甲氧西林葡萄球菌和肠球菌blaTEM及tetM基因检测

目的了解临床分离的耐甲氧西林葡萄球菌(MRS)和肠球菌中blaTEM及tetM基因存在状况。方法分离50株耐甲氧西林金黄色葡萄球菌(MRSA),7株耐甲氧西林表皮葡萄球菌(MRSE)、5株耐甲氧西林溶血葡萄球菌(MRSH)、15株粪肠球菌和9株屎肠球菌,采用PCR技术检测耐药基因。结果MRSA、MRSE、MRSH、粪肠球菌和屎肠球菌中blaTEM基因阳性率分别为40.0%、57.1%、60.0%、6.7%和88.9%,tetM基因阳性率分别为100%、0%、0%、66.7%、0%。结论blaTEM基因阳性率在MRS中较高,在屎肠球菌中则很高;携带tetM基因是MRSA和粪肠球菌对四环素耐药的主要原因。     

自体内皮前体细胞移植对急性心肌梗死大鼠微血管新生及心功能的影响

目的探讨外周血来源的内皮前体细胞自体移植,对大鼠急性心肌梗死后微血管新生与心功能的影响。方法抽取SD大鼠外周动脉血,应用Ficoll密度梯度离心法获取单个核细胞。应用含有VEGF和bFGF的特定培养基体外培养,得到内皮前体细胞;结扎SD大鼠冠状动脉左前降支,建立急性心肌梗死模型;然后将得到的自体内皮前体细胞植入缺血心肌局部区域。对照组动物注入细胞培养液。结果与对照组比较,细胞移植组大鼠心功能明显改善,心肌收缩力显著优于对照组;梗死心肌微血管新生更为明显。结论急性心肌梗死心肌局部移植外周血来源的自体内皮前体细胞,能够促进血管新生;对局部梗死心肌组织结构有一定的保护作用,并可在不同时点不同程度恢复心肌收缩力,显著改善心功能。     

Differential sympathetic outflow elicited by active muscle in rats

The present study was undertaken to test the hypothesis that activation of the muscle reflex elicits less sympathetic activation in skeletal muscle than in internal organs. In decerebrate rats, we examined renal and lumbar (mainly innervating hindlimb blood vessels) sympathetic nerve activities (RSNA and LSNA, respectively) during 1 min of 1) repetitive (1- to 4-s stimulation-to-relaxation) contraction of the triceps surae muscle, 2) repetitive tendon stretch, and 3) repetitive contraction with hindlimb circulatory occlusion. During these interventions, RSNA and LSNA responded synchronously as tension developed. The increase was greater in RSNA than in LSNA [+51 +/- 14 vs. +24 +/- 5% (P < 0.05) with contraction, +46 +/- 8 vs. +17 +/- 4% (P < 0.05) with stretch, +76 +/- 20 vs. 39 +/- 7% (P < 0.05) with contraction during occlusion] during all three interventions: repetitive contraction (n = 10, +508 +/- 48 g tension from baseline), tendon stretch (n = 12, +454 +/- 34 g), and contraction during occlusion (n = 9, +473 +/- 33 g). Additionally, hindlimb circulatory occlusion significantly enhanced RSNA and LSNA responses to contraction. These data demonstrate that RSNA responses to muscle contraction and stretch are greater than LSNA responses. We suggest that activation of the muscle afferents induces the differential sympathetic outflow that is directed toward the kidney as opposed to the limbs. This differential outflow contributes to the distribution of cardiac output observed during exercise. We further suggest that as exercise proceeds, muscle metabolites produced in contracting muscle sensitize muscle afferents and enhance sympathetic drive to limbs and renal beds.     

Interstitial norepinephrine concentrations in skeletal muscle of ischemic heart failure

During exercise, sympathetic nerve responses are accentuated in heart failure (HF), and this enhances norepinephrine (NE) release and evokes vasoconstriction. Two key pathophysiological responses could contribute to the greater NE release: 1) increased sympathetic nerve discharge and 2) increased NE in the neurovascular junction for a given level of sympathetic discharge. In this report, we focus on the second of these two general issues and test the following hypotheses: 1) in HF for a given level of sympathetic nerve stimulation, NE concentration in the interstitium (an index of neurovascular NE) would be greater, and 2) the greater interstitial NE concentration would be linked to reduced NE uptake. Studies were performed in rats 8-10 wk after induction of myocardial infarction (MI). Interstitial NE samples were collected from microdialysis probes inserted into the hindlimb muscle. Dialysate concentration of NE was determined by the HPLC method. First, interstitial NE concentration increased during electrical stimulation of the lumbar sympathetic nerves in eight control rats. An increase in interstitial NE concentration was significantly greater in 10 rats with severe MI. Additionally, an NE uptake-1 inhibitor (desipramine, 1 microM) was injected into the arterial blood supply of the muscle in six control and eight MI rats. Desipramine increased interstitial NE concentration by 24% in control and by only 3% (P < 0.05 vs. control) in MI rats. In conclusion, given levels of electrical stimulation of the lumbar sympathetic nerve lead to higher interstitial NE concentration in HF. This effect is due, in part, to reduced NE uptake-1 in HF.     

陕西红脂大小蠹天敌种类调查

对陕西红脂大小蠹Dendroctonus valens LeConte危害区的天敌种类调查表明,寄生于红脂大小蠹的病原真菌共有5种,其中幼虫期有头孢霉Cephalosporium sp.、球孢白僵菌Beauveria bassiana和拟卵孢霉Ovulariopsis sp.,成虫期有球孢白僵菌Beauveria bassiana、枝顶孢霉Acremonium sp.、头孢霉Cephalosporium sp.、木霉Trichoderma sp.4种,其中以球孢白僵菌和枝顶孢霉Acremonium sp.的致病能力最为显著。捕食性天敌昆虫主要有西岳蛇蛉Agulla xiyue Yang et Chou、日本弓背蚁Camponotus japionicus Mayr、中华红林蚁Formica sinensis Wheeler、蚁形郭公甲Thanasimus formicarius(L.)及纤细阎甲Platysoma attenuata(LeConte),它们对红脂大小蠹均有较明显的控制作用。寄生性天敌主要有1种寄生蝇和1种茧蜂。