Functional connections and epileptic spread between hippocampus, entorhinal cortex and amygdala in a modified horizontal slice preparation of the rat brain

The hippocampus, the entorhinal cortex and the amygdala are interconnected structures of the limbic system that are implicated in memory and emotional behaviour. They demonstrate synaptic plasticity and are susceptible to development of temporal lobe epilepsy, which may lead to emotional and psychological disturbances. Their relative anatomical disposition has limited the study of neurotransmission and epileptic spread between these three regions in previous in vitro preparations. Here we describe a novel, modified-horizontal slice preparation that includes in the same plane the hippocampus, entorhinal cortex and amygdala. We found that, following application of bicuculline, each region in our preparation could generate spontaneous bursts that resembled epileptic interictal spikes. This spontaneous activity initiated in the hippocampal CA3/2 region, from where it propagated and controlled the activity in the entorhinal cortex and the amygdala. We found that this spontaneous bursting activity could spread via two different pathways. The first pathway comprises the well-known subiculum-entorhinal cortex-perirhinal cortex-amygdala route. The second pathway consists of a direct connection between the CA1 region and perirhinal cortex, through which the hippocampal bursting activity can spread to the amygdala while bypassing the entorhinal cortex. Thus, our experiments provide a new in vitro model of initiation and spread of epileptic-like activity in the ventral part of the limbic system, which includes a novel, fast and functional connection between the CA1 region and perirhinal cortex.     

Stimulation of growth hormone release in man by the potent D2-dopamine agonist CV 205-502: comparison of responses to intravenous and oral administration

It is well known that dopaminergic agents are stimulators of GH release in man, and although responses are sometimes unreliable, oral L-dopa and iv dopamine have frequently been employed in the evaluation of GH-deficient states. To assess the effects on GH secretion of a new potent D2-dopamine agonist, the octahydrobenzo(g)quinoline CV 205-502 (CV) we have investigated the GH responses in healthy male volunteers to four different iv doses. For this purpose 3 separate groups of 9 subjects were studied. The respective groups were administered on separate occasions 10 micrograms CV and placebo (group 1), 5 micrograms, 2.5 micrograms, and placebo (group 2), and 1 microgram and placebo (group 3). Each subject received drug and placebo in a double blind randomly assigned order, with at least 5 days between their administration. Active compound or placebo was infused over 30 min, and blood sampling was carried out for 72 h after cessation of infusion. Peak GH levels occurred between 45-60 min after the end of the infusion; the observed maximum GH concentrations were 19.2 +/- 2.9 micrograms/L (10 micrograms, iv; P less than 0.001 vs. placebo), 9.61 +/- 2.1 (5 micrograms, iv; P less than 0.001 vs. placebo), 4.7 +/- 1.7 (2.5 micrograms, iv; P less than 0.05 vs. placebo), and 1.9 +/- 0.8 micrograms/L (1 micrograms, iv; P = NS vs. placebo). The mean integrated GH secretion expressed in arbitrary units [area under the response curve (AUC)] up to 3 h postinfusion showed a typical dose-response relationship. Mean values were 1715 +/- 269.4 (10 micrograms, iv; P less than 0.001 vs. placebo), 956.1 +/- 189.9 (5 micrograms, iv; P less than 0.001 vs. placebo), 312.8 +/- 105.8 (2.5 micrograms, iv), and 162.8 +/- 47.5 (1 microgram, iv). In a second study with a separate group of 18 volunteers, we compared the GH response to an oral dose of 100 micrograms CV with those to 5 micrograms CV given iv and placebo treatment. Peak GH values in this study were 20.3 +/- 5.5 micrograms/L (100 micrograms, orally; P less than 0.01 vs. placebo) and 14.6 +/- 2.8 (5 micrograms, iv; P less than 0.001 vs. placebo). Maximum levels occurred 45 min after the infusion and 90 min after ingestion (60 min relative to the end of the infusion).(ABSTRACT TRUNCATED AT 400 WORDS)     

Mutational scanning of large genes by extensive PCR multiplexing and two-dimensional electrophoresis: application to the RB1 gene

With the rapid increase in the number of identified human disease genes, the development of accurate and cost-efficient mutation tests has become opportune. Here we present a combination of extensive PCR multiplexing and two-dimensional (2-D) DNA electrophoresis to screen for mutations in 26 exons of the retinoblastoma (RB1) tumor suppressor gene. In 2-D electrophoresis, fragments are separated according to size and base pair sequence in non-denaturing and denaturing gradient gels, respectively. All target fragments, designed to have optimal melting characteristics, were prepared in a two-step PCR (a 6-plex long-PCR pre- amplification and a subsequent 25-plex short-PCR) followed by heteroduplexing. The mixture of PCR amplicons was then subjected to 2-D electrophoresis under a single set of experimental conditions. With this design, 35 previously identified mutations in 18 different exons were detected in 33 bilateral retinoblastoma patients. These results suggest that 2-D electrophoresis in this format provides a generally applicable, practical and fast way to diagnose with high accuracy large genes for a broad spectrum of possible disease-causing mutations.      

Noradrenaline Increases K-conductance and Reduces Glutamatergic Transmission in the Mouse Entorhinal Cortex by Activation of α2-Adrenoreceptors

The entorhinal cortex is a gateway to the hippocampus; it receives inputs from several cortical associative areas as well as subcortical areas. Since there is evidence showing that noradrenaline reduces the epileptic activity generated in the entorhinal cortex, we have examined the action of noradrenaline in the superficial layer of the entorhinal cortex, which is the main source of afferents to the hippocampus. In a previous study we showed that noradrenaline hyperpolarized layer II entorhinal cortex neurons and reduced global synaptic transmission via α₂-adrenoreceptors. Here we present a detailed analysis of the effect of noradrenaline on membrane resistance and on the pharmacologically isolated postsynaptic potentials in layer II entorhinal cortex neurons of mice. Noradrenaline (50 μM) hyperpolarized most layer II entorhinal cortex neurons. This hyperpolarization corresponded to an outward current with a reversal potential following the Nernst equilibrium potential for potassium. The hyperpolarizing effect of noradrenaline was blocked by 10 μM yohimbine. These observations suggest that noradrenaline activates a potassium conductance via an α₂-adrenoreceptor. Noradrenaline (10–50 μM) reversibly reduced the amplitude of the pharmacologically isolated excitatory potentials mediated by both NMDA and α-amino-3-hydroxy-5-methyl-isoxazole-propionic acid (AMPA) receptors, the former being more strongly affected. Again this effect was blocked by 10 μM yohimbine. In contrast, GABA_A-mediated synaptic transmission was virtually unaffected by noradrenaline. Thus, noradrenaline appears to strongly inhibit the glutamate-mediated synaptic transmission in the entorhinal cortex without affecting inhibitory post-synaptic potentials. These observations suggest that α₂-adrenergic receptor agonists may exert a beneficial effect in the control of hyperexcitability in temporal lobe epilepsy.     

Relationship between image quality and ultrasound exposure level in diagnostic US devices

Ultrasonographic B-mode images were obtained at various exposure levels with three real-time diagnostic scanners. Adult human and tissue-equivalent phantom images were compared in terms of diagnostic content and depth of penetration. For the exposure level settings used, spatial-peak pulse-average intensities ranged from approximately 10 to 500 W/cm2. At the 3.50-3.75-MHz nominal frequencies used in the study, images of the human abdomen showed little discernible change in quality with varying exposure levels. However, phantom tests confirmed that depth of penetration is a function of exposure level. The results suggest that a judicious use of exposure level and receiver gain controls can be a practical means for minimizing patient exposure to ultrasound without sacrifice of diagnostic effectiveness.     

男性不育症精浆中超氧化物歧化酶、锌、睾酮含量的研究

本文采用一种简便灵敏的改良邻苯三酚法测定了236例不育症患者和27例正常育龄男子精浆中铜锌超氧化物歧化酶(CuZn-SoD)含量,同时还测定了精浆锌(Zn)和睾酮(T)含量。结果表明:在不育症精浆中,CuZn-SOD、Zn、T与精子密度之间均有显著正相关(P<0.01);CuZn-SOD和Zn含量与精子活动度均有密切关系,含量高活动度也高(P<0.001);CuZn-SOD和Zn之间亦存在显著正相关(P<0.01). 在精子密度范围同60～100×10~6/ml时.不育组与生育组精浆中CuZn-SOD、Zn、T含量均无统计学差异(P<0.2).本究究提示.CuZn-SOD作为精浆保护因子,通过抑制类脂过氧化反应使精子免受损伤。精浆CuZn-SOD含量测定有可能作为衡量精液质量的新指标。应用SOD类制剂治疗男性不育症可能有裨益。     

UK childbirth delivery options in 2001–2002: alternatives to consultant unit booking and delivery

BACKGROUND: Government policy advocates maternal choice in pregnancy care. Two key issues are place of birth and type of lead professional. Anecdotal evidence suggests there is variation in both these issues across the UK, but there has been no recent national assessment of whether maternal options are in line with government policy. AIM: To establish the range of women's childbirth delivery options, degree of midwife autonomy, and supporting training and governance mechanisms. DESIGN: Two postal questionnaires. SETTING: UK maternity units. METHOD: Questionnaires were sent to maternity services managers. MAIN OUTCOME MEASURES: number and type of units and births, transfers and care types; midwifery procedures; clinical governance and training activities. RESULTS: Completed questionnaires were received from 301 out of 308 (97.7%) units in 2002 and from 258 out of 309 (83.5%) units in 2001. Midwife-led care is available in 186 English (76.9%), 15 Welsh (78.9%), 18 Scottish (48.6%) and three Northern Ireland (30.0%) units. There are 73 (24.3%) stand-alone, 22 (7.3%) alongside, 127 (42.2%) integrated and 79 (26.2%) consultant units (for definitions of unit types, see main text), with a median 2215 hospital, 25 home and 210 midwife-led births. The median antenatal and labour transfers from midwife-led units are 25.5% (interquartile range [IQR] = 18.5-36.5%) and 18.0% (IQR = 13.4-24.8%) respectively; transfers are independent of distance to nearest consultant unit, country and unit type. CONCLUSIONS: Despite government policy promoting greater parental choice, this is not in evidence in many parts of the UK. The wide variations in home birth, midwife-led care and maternity-unit types merit further exploration. If more midwife-led units are to be established as a way of promoting parental choice and dealing with junior doctor rota problems, then such units must have adequate governance and training activities in place.     

Epstein-Barr virus-associated hemophagocytic syndrome: virological and immunopathological studies

The virus-associated hemophagocytic syndrome (VAHS) is a disorder characterized by a benign, generalized histiocytic proliferation, with marked hemophagocytosis associated with systemic viral infections. We have studied the virological and immunopathological events occurring in two children experiencing Epstein-Barr VAHS. Neither of the patients had an underlying immunodeficiency and both recovered from their disease and are completely well one year after follow-up. In each patient, evidence for primary Epstein-Barr virus (EBV) infection was documented with a typical humoral immune response, including IgM antibody directed against virus capsid antigen. EBV was demonstrated in lymphoreticular tissues by electron microscopy and molecular hybridization studies. Permissive EBV infection was suggested by the finding of mature virus particles and linear viral DNA in lymphoreticular tissues. Immunopathological studies demonstrated complete effacement of lymph node architecture by a marked proliferation of immunoblasts in patient 1 and infiltration and effacement of the lymph node architecture with benign-appearing histiocytes in patient 2. Atypical lymphocytes characteristic of acute EBV infection were notably absent in the peripheral blood of both patients and cytotoxic T cells, which normally lyse EBV-infected B cells, were also absent from the peripheral circulation. Our observations suggest that EBV-induced VAHS may be the result of an increased virus burden in the face of immunoregulatory cell imbalances.