Studies of β-lactamase production in ampicillin resistant Haemophilus influenzae

In 1972, HaelnOPhilus influenzae (HI) was firstlydiscovend being resistant against alnpicillin by producing5-lac~e, since then, studies on the rests~ mechamsms and the moleCular basis of 5-lactalnaSe Pwhctionhave been increasing year by yeax abroadll]. In 1978,Bryan et .l[2] first reported sabins of HI Producing 0-lactamaSe, which was mediated by plaaed, from then on,many stUdies foeused on 3-lactamase encoded by PlaSnddin HI and its relation with ampicillin resisboce. In ourco~, few st…     

Masseteric silent period in healthy young adults

The length of the silent period (SP) has been subject of extensive researches and its use has been established for the diagnosis of dysfunctional individuals. Because of its great variability we should be cautious about its assessment. This study is aimed to find the normal values taken in symptomless subjects using a commercial/medical recording system, designed for clinical use. Thirty-six readings of the SP have been taken causing a chin tap. The assessment of the motor dysfunction and the subsequent depressed activity gave the result of 32.37 ms (SD = 19.47, ranged from 15 to 110). This is slightly more extended than the results described by the majority of the Authors.     

髁状突冷冻再植后颞下颌关节改变的实验研究

目的:为颞下颌关节肿瘤的治疗及关节重建提供一定的理论依据.材料和方法:对16只未成年日本大耳白兔的右侧髁状突施行了冷冻再植术.术后所有动物正常存活,第2、4、8、12周分别处死4只动物.采用常规组织学、扫描电镜及微血管显像等对髁状突和关节盘进行观察.结果:组织学检查发现随着血供逐渐恢复,失去活力的骨被新骨"爬行替代",而髁状突软骨的结构未完全恢复;扫描电镜检查证明了关节盘下腔面的表面结构基本正常,实验后期髁状突的表面较光滑,但无明显胶冻样物;微血管显像显示冷冻再植髁状突逐渐再血管化.16只动物中有3只的手术侧颞下颌关节发生轻度粘连. 结论这些结果证明:髁状突冷冻再植在颞下颌关节重建时有应用的可行性.     

中老年人脾肾虚证与血脂及抗氧化物关系的探讨

采用前瞻性设计方案,利用现代先进的有针对性的指标,应用单因素及多因素综合分析方法,对７７３例中老年人进行脾肾虚证实质的研究。结果发现：中老年人肾虚证与脂质代谢紊乱、机体经物质减少、过氧化脂质增密切相关。同时发现,脾虚证到肾虚证是一个逐渐发展的病理过程,且有层次性。认为肾虚证脂质代谢紊乱程度高于脾虚证,脾虚证与机体抗氧化物减少无密切关系。     

离子通道镶嵌点过程模型在K+通道研究中的应用

目的：用作者提出的离子通道镶嵌点过程模型拟合海马锥体细胞钾离子单通道记录数据分析１７β雌二醇的效应。方法：用协方差密度度量通道记忆,从３个方面做拟合优度检验。结果：该模型与观察资料拟合效果良好;１７β雌二醇能改变海马锥体细胞钾离子单通道的记忆;１７β雌二醇对关闭的影响比对开放的影响大,从而表现为对通道具有抑制作用：浓度为１０ｎｍｏｌ／Ｌ组的１７β雌二醇对通道记忆的影响比对浓度为０１ｎｍｏｌ／Ｌ组的大。结论：Ｍａｒｋｏｖ模型的常规分析只能得到１７β雌二醇对海马锥体细胞钾离子单通道具有抑制作用,而用本模型分析能得到更多通道的信息     

Short-term effects of high-dose 17beta-estradiol in postmenopausal PD patients: a crossover study.

OBJECTIVE: To examine the effect of 17beta-estradiol on the severity of the cardinal signs of PD in postmenopausal women. BACKGROUND: Although the impact of estrogens on the manifestations of PD has not been subjected to rigorous study, their use is generally thought to be associated with a detrimental antidopaminergic effect. METHODS: A double-blind, placebo-controlled, two-arm crossover study of high-dose transdermal 17beta-estradiol was conducted in eight postmenopausal women with mild to moderate PD, all but one of whom exhibited levodopa-induced dyskinesias. Patients were randomized initially to either hormonal treatment or placebo for 2 weeks, followed by a 2-week washout period, and then another 2-week crossover treatment period. Active treatment employed four skin patches each releasing 0.1 mg of estradiol daily, replaced every 2 to 3 days. RESULTS: After 10 days of treatment a significant reduction was observed in the antiparkinsonian threshold dose of IV levodopa. Mean duration and magnitude of the antiparkinsonian response to threshold or high doses of levodopa were unchanged, and dyskinesia scores were unaltered during 17beta-estradiol treatment compared with placebo. No worsening in "on" time or motor ratings with estrogen treatment was documented. CONCLUSIONS: 17beta-estradiol appears to display a slight prodopaminergic (or antiparkinsonian) effect without consistently altering dyskinesias. Standard postmenopausal replacement therapy with transdermal 17beta-estradiol is likely to be well tolerated by many female parkinsonian patients.     

大鼠大脑中动脉缺血和再灌注后环氧合酶-2mRNA表达的研究

目的研究大鼠大脑中动脉缺血和再灌注模型中环氧合酶－２（ＣＯＸ－２）基因的表达。方法原位杂交方法。结果缺血３０ｍｉｎ再灌注组,血流再通４ｈ后缺血区的大脑皮层有很强的表达并持续２４ｈ。缺血９０ｍｉｎ再灌注组和持续缺血组在缺血区以外的广泛大脑皮层显著表达,在海马的齿状回两侧及纹状体也发现表达。ＣＯＸ－２ｍＲＮＡ的表达可被ＭＫ－８０１抑制。而ＮＢＱＸ和倍他米松对其表达没有影响。结论在缺血区、缺血周边部、缺血远隔区有ＮＭＤＡ受体介导的ＣＯＸ－２表达,阐明上述区域花生四烯酸代谢活性化     

Prevention of stroke in urban China: a community-based intervention trial

BACKGROUND AND PURPOSE: Stroke has been the second leading cause of death in large cities in China since the 1980s. Meanwhile, the prevalences of hypertension and smoking have steadily increased over the last 2 decades. Therefore, a community-based intervention trial was initiated in 7 Chinese cities in 1987. The overall goal of the study was to evaluate the effectiveness of an intervention aimed at reducing multiple risk factors for stroke. The primary study objective was to reduce the incidence of stroke by 25% over 3.5 years of intervention. METHODS: In May 1987 in each of 7 the cities, 2 geographically separated communities with a registered population of about 10 000 each were selected as either intervention or control communities. In each community, a cohort containing about 2700 subjects (>/=35 years old) free of stroke was sampled, and a survey was administered to obtain baseline data and screen the eligible subjects for intervention. In each city, a program of treatment for hypertension, heart disease, and diabetes was instituted in the intervention cohort (n approximately 2700) and health education was provided to the full intervention community (n approximately 10 000). A follow-up survey was conducted in 1990. Comparisons of intervention and control cohorts in each city were pooled to yield a single summary. RESULTS: A total of 18 786 subjects were recruited to the intervention cohort and 18 876 to the control cohort from 7 cities. After 3.5 years, 174 new stroke cases had occurred in the intervention cohort and 253 in the control cohort. The 3.5-year cumulative incidence of total stroke was significantly lower in the intervention cohort than the control cohort (0.93% versus 1.34%; RR=0.69; 95% CI, 0.57 to 0.84). The incidence rates of nonfatal and fatal stroke, as well as ischemic and hemorrhagic stroke, were significantly lower in the intervention cohort than the control cohort. The prevalence of hypertension increased by 4.3% in the intervention cohort and by 7.8% in the control cohort. The average systolic and diastolic blood pressures increased more in the control cohort than in the intervention cohort. Among hypertensive individuals in the intervention cohort, awareness of hypertension increased by 6.7% and the percentage of hypertensives who regularly took antihypertensive medication increased 13.2%. All of these indices became worse in the control cohort. The prevalence of heart diseases and diabetes increased significantly in the both cohorts (P<0.01). The prevalence of consumption of alcohol increased slightly, and that of smoking remained constant in both cohorts. CONCLUSIONS: A community-based intervention for stroke reduction is feasible and effective in the cities of China. The reduction, due to the intervention, in the incidence of stroke in the intervention cohort was statistically significant after 3.5 years of intervention. The sharp reduction in the incidence of stroke may be due to the interventions having blunted the expected increase in hypertension that accompanies aging as well as to better and earlier treatment of hypertension, particularly borderline hypertension. Applied health education to all the residents of the community may have prevented some normotensive individuals from developing hypertension and improved overall health awareness and knowledge.     

Influence of fetal to neonatal transition on nitric oxide synthase expression in the nucleus tractus solitarius in sheep

Transition from fetal to newborn life is accompanied by a marked rise in circulating norepinephrine (NE) concentrations though arterial blood pressure does not substantively change. Nitric oxide (NO) plays an important role in the central regulation of sympathetic tone in the nucleus tractus solitarius (NTS) and neuronal NO synthase (nNOS) expression is functionally regulated in the brain. The purpose of these studies was to determine the influence of transition at birth on nNOS expression in the brainstem nuclei, particularly in the NTS, associated with changes in arterial pressure and plasma NE concentration. Experiments were performed using time-dated gestational ewes with twin fetuses. Arterial blood pressure was recorded and arterial blood NE concentrations were measured in the term fetus (gestational 147-148 days) and newborn lambs (4 h of postnatal age). The fetal and newborn animals were then perfused with 4% paraformaldehyde. Sections of the medulla were examined by using both immunolabeling with a polyclonal antibody directed against nNOS and nicotinamide adenine dinucleotide phosphate diaphorase (NADPHd) histochemistry, a marker for expression of nNOS. Micrographs were quantified using a microscope with reticule grid to measure the number of positive cells containing color staining in the brainstem nuclei. Plasma NE concentration in the newborn was more than two-fold greater compared to fetal values but mean arterial blood pressure was similar between fetus and newborn. The nNOS positive cells and NADPHd positive cells were significantly increased in the medial NTS (mNTS) of the newborn compared to fetus. nNOS immunoreactivity and NADPHd reactivity tended to increase in the rostral ventral medulla (RVM) in newborn, but were not altered in other brainstem nuclei during the transition from fetal to newborn life. The results suggest that nNOS expression in the mNTS is predominately enhanced at 4 h of neonatal age vs. the term fetus. We conclude that elevated circulating NE is associated with up-regulation of nNOS in the mNTS which may serve a protective role in central regulation of neonatal arterial blood pressure.     

The tyrosine kinase inhibitor genistein directly inhibits GABAA receptors

The protein tyrosine kinase (PTK) inhibitor genistein has been widely used to examine potential effects of tyrosine phosphorylation on neurotransmitter function. We report here that genistein inhibits GABAA receptors through a direct effect. Extracellular application of genistein and GABA reversibly inhibited GABA-activated currents recorded from HEK293 cells expressing rat alpha1beta2gamma2S or alpha1beta2 receptors, even when genistein was preequilibrated in the intracellular solution. Daidzein, an analog of genistein that does not block PTK, also inhibited GABA-activated current. Coapplication of lavendustin A, a specific inhibitor of PTK, had no effect on the GABA response. Our results demonstrate that genistein has a direct inhibitory effect on GABAA receptors that is not mediated via inhibition of tyrosine kinase.