Chronic failure of inhibition of the CA1 area of the hippocampus following kainic acid lesions of the CA3/4 area

The chronic effects of the lesioning agent, kainic acid, on paired pulse inhibition in the CA1 area were investigated in the hippocampus both in vivo and in vitro. Pretreatment of animals with a unilateral intracerebroventricular (i.c.v.) injection of kainic acid resulted in a lesion of the CA3/4 area of the hippocampus ipsilateral to the injection site. On activating the surviving Schaffer collateral afferents in the contralateral hippocampus, normal paired-pulse inhibition of the extracellularly recorded population spike in CA1 was observed. On activating the surviving commissural afferents to the CA1 area ipsilateral to the lesion, no such inhibition could be observed. However, paired-pulse inhibition was recorded in the dentate gyrus ipsilateral to the lesion in response to stimulation of the perforant path. The chronic failure of inhibition following the unilateral i.c.v. injection of kainic acid further supports the use of this method to provide a chronic model in the rat for the study of epileptogenesis in the hippocampus.     

The public health nurse as a guide in infant child-care and education

The prime aim of the study was to develop the child-care and education guidance provided by public health nurses at health centres for parents of children aged 1 or 2. The research was partly carried out according to the principles of action research. The researcher's purpose was to influence the public health nurses' child-care and education guidance by designing measures and forms for the documentation and evaluation of the development, environment, and care practices of children aged 1 or 2. Methods were improved by the collaboration between the researcher and the nurses in the course of the research. In addition, the investigator designed a child-care and guidance programme for parents of such children. The premise of the public health nurse's action was the WHO's process model for nursing. The study focused on public health nurses and on children aged 1-2 and their parents. The overall action model of the public health nurses (needs assessment, goal-setting, implementation of action and evaluation) improved in the course of the experiment. The methods facilitated the implementation of action and provided it with clear objectives. The reliability and validity of the methods were reasonably high. The parents of the experimental group felt significantly more often then than those of the control group that they had obtained information about the development, care, and education of the child aged 1-2 from the public health nurses. The guidance had also helped the parents solve child rearing problems. The level of development in the children of the experimental group was higher than that of the control group at 24 months, in certain areas.     

The synaptically evoked late hyperpolarisation in hippocampal CA1 pyramidal cells is resistant to intracellular EGTA

It has been suggested that the late hyperpolarisation following synaptic activation of hippocampal CA1 pyramidal neurons is activated by calcium influx. This hypothesis was examined using microelectrodes containing EGTA. Intracellular injection of EGTA blocked the afterhyperpolarisation which normally followed cell firing produced by injection of a depolarising current or the ionophoresis of glutamate onto the apical dendrites. In contrast, the hyperpolarisation following synaptic activation was resistant to EGTA. The results suggest that this potential is not dependent on intracellular Ca2+. Other possible mechanisms are discussed.     

Model of spatio-temporal propagation of action potentials in the Schaffer collateral pathway of the CA1 area of the rat hippocampus

There is a sharp contrast between the profuse in vivo axonal arborization of CA3 pyramidal cells in the CA1 area and the low probability of finding pairs of connected CA3-CA1 pyramidal cells in vitro. These anatomical differences contribute to a connectivity argument for discrepancies between electrophysiological data recorded in vitro and in vivo. In order to investigate this issue, we have developed a realistic computer model of the Schaffer collateral pathway of the hippocampus and analyzed the spatio-temporal distribution of action potentials along this pathway following three different types of electrical test stimulus. Direct activation of mossy fibers, CA3 pyramidal cells and focal stimulation of CA1 stratum radiatum were investigated. The parameters of the model were selected from available biological data. Spikes in Schaffer collaterals were followed from their onset in the CA3 pyramidal cell initial segment to the last order branches of their axonal tree in two types of configuration: the whole hippocampus and the slice configuration. The anatomical and electropysiological characteristics of the mossy fibre and Schaffer collateral pathways were found to impose strong constraints on the spatio-temporal distribution of action potentials in the CA1 area. Specific projection zones are determined by the spatial localization of the emitting CA3 pyramidal cells. Their position also defines precise time windows during which some CA1 projection zones receive a large number of correlated signals. Moreover, the variability of the delay at the mossy fibre/CA3 pyramidal cell synapse seems to provide the CA1 projection zones with a background level of excitation. Finally, we show how the patterns of activation obtained in the whole hippocampus are different from those obtained in the slice. Hippocampus 7:58–72, 1997. © 1997 Wiley-Liss, Inc.     

深圳市感染性腹泻监测信息管理系统评估

目的评估深圳市感染性腹泻监测信息管理系统运行状况,以提高监测工作质量。方法参照国际疾病监测系统评估方法,依据深圳市感染性腹泻病原谱哨点监测工作方案要求,通过现场考察、问卷调查等方法,对该市11家哨点医院、6个区疾病预防控制中心和市疾病预防控制中心工作情况及该系统使用情况开展调查。结果本次评估共调查该信息管理系统相关操作人员40人,男性14人（35％）,女性26人（65％）,其中疾病预防控制机构22人,医疗机构18人,被调查人群在性别、年龄、学历上差异均无统计学意义;在可操作性方面,大部分人认为系统容易使用,界面美观舒适,用语浅显易懂,能很快学会;47．5％的人认为登录速度还不够理想。在简便性方面,大部分人认为该系统对日常工作影响较小,病例定义容易判断、细菌和病毒纳入标准较容易判断,病例排除标准容易判断;41．0％的人认为系统要求的样本数量难以达到。在及时性方面,对患者样本的采集和检测基本能在患者发病3d内完成,但对患者信息的录入时间不一致;在数据可靠性方面,大部分人认为录入数据真实可信,结果真实可信,愿意使用该系统进行统计分析,统计功能能够达到需求,有32．5％的人认为不能很好地了解本监测点的情况。在目的可达性方面,大部分人认为能够了解感染性腹泻的病原谱构成,对暴发疫情起到早期预警的作用,能够引导对重点地区和人群的主动监测,能为微生物风险评估提供疾病监测的本底数据。结论深圳市感染性腹泻监测信息管理系统运转良好,但仍存在部分问题,个别监测目标目前仍难以实现,有待进一步完善。     

Antibiotics to prevent complications following dental implant treatment

A substantive amendment to this systematic review was last made on 15 March 2003. Cochrane reviews are regularly checked and updated if necessary. Background Some dental implant failures may be due to bacterial contamination at implant insertion. Infections around biomaterials are difficult to treat and almost all infected implants have to be removed. In general, antibiotic prophylaxis in surgery is only indicated for patients at risk of infectious endocarditis, for patients with reduced host‐response, when surgery is performed in infected sites, in cases of extensive and prolonged surgical interventions and when large foreign materials are implanted. To minimize infections after dental implant placement various prophylactic systemic antibiotic regimens have been suggested. More recent protocols recommended short term prophylaxis, if antibiotics have to be used. With the administration of antibiotics adverse events may occur, ranging from diarrhoea to life‐threatening allergic reactions. Another major concern associated with the widespread use of antibiotics is the selection of antibiotic‐resistant bacteria. The use of antibiotics in implant dentistry is controversial. It would be useful to know whether prophylactic antibiotics are effective in reducing failures of dental implants. Objectives T o assess the beneficial or harmful effects of the administration of prophylactic antibiotics for dental implant placement versus no antibiotic/placebo administration and if antibiotics are of benefit, to find which type, dosage and duration is the most effective. Search strategy We searched the Cochrane Oral Health Group's Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE. We handsearched several dental journals. No language restrictions were applied. Personal contacts and manufacturers of dental implants were contacted to identify unpublished trials. Most recent search: March 2003. Selection criteria Randomized controlled clinical trials (RCTs) with a follow‐up of at least three months comparing the administration of various prophylactic antibiotics regimens and no antibiotics/placebo to patients undergoing dental implant placement. Outcome measures were prosthesis failures, implant failures, postoperative infections and adverse events (gastrointestinal, hypersensitivity). Data collection and analysis Screening of eligible studies, assessment of the methodological quality of the trials and data extraction were to be conducted in duplicate and independently by two reviewers. Results were to be expressed as random effects models using weighted mean differences for continuous outcomes and relative risk for dichotomous outcomes with 95 per cent confidence interval. Heterogeneity was to be investigated including both clinical and methodological factors. Main Results No RCTs were identified. Reviewers' Conclusions There is not appropriate scientific evidence to recommend or discourage the use of prophylactic systemic antibiotics to prevent complications and failures of dental implants. Even though the present review did not assess the effectiveness of prophylactic antibiotics for patients at risk for endocarditis, it seems sensible to recommend the use of prophylactic antibiotics for patients at high and moderate risk for endocarditis, with immunodeficiencies, metabolic diseases, irradiated in the head and neck area and when an extensive or prolonged surgery is anticipated.     

Measurement systems in principle and in practice: the example of nursing workload

There has been a rapid development of measurement systems in the health services in the United Kingdom (UK) over recent years, not always matched by a thorough understanding of the phenomenon being measured and rarely based on any assessment of reliability or validity A particularly flagrant example of this process is the development of nursing workload measurement systems (NWMS) The estimates from four NWMS were examined They were substantially different from each other for no obvious reason, and the difference between any of the estimates and the actual nursing hours worked could not be explained in terms of any other aspect of the nursing process There is no evidence that the NWMS deployed in the UK are anything more than an expensive numbers game, without this kind of investigation of how they actually work in practice , it would be prudent to be wary about any of the measurement systems which have been proposed Yet many of the measurement systems used in other sectors of the health service are equally untested