Expression of the axon growth-related neural adhesion molecule TAG-1/axonin-1 in the adult mouse brain

 TAG-1/axonin-1 is a neuronal cell adhesion molecule of the immunoglobulin superfamily. It is predominantly expressed during neural development and has been reported to be involved in axonal growth and pathfinding. Here, the expression of TAG-1/axonin-1 was investigated anatomically in the adult mouse brain by in situ hybridization using digoxigenin-labeled cRNA probes. Low levels of TAG-1/axonin-1 could be detected in cerebellar granule cells, in tufted and mitral cells of the olfactory bulb, and in pyramidal cells of area CA1 and CA3 of the hippocampus. We suspect that the expression of TAG-1/axonin-1 in these structures of the adult brain may serve neural plasticity. Accepted: 8 September 1997     

孕妇血清标记物在中孕筛查中的应用

目的 :通过对孕妇血清标记物甲胎蛋白 (AFP)和人绒毛膜促性腺激素 ( β -HCG )测定来筛选缺陷儿。 方法 :用放射免疫法对 6 2例孕 14～ 2 3周妊娠妇女上述标记物连测 3次 ,每次隔 12～ 14d ,以两次异常为高危个体。每例筛查者跟踪至胎儿出生后。结果 :在筛查中发现了 1例先天愚型和 1例无脑儿。结论 :上述两种血清标记物可以作为神经管缺陷和先天愚型筛查的一项常规方法     

2158 例神经管缺陷儿的产前B型超声波诊断分析

回顾性分析1990～1993年全国28省、市、自治区233所医院,住院分娩的孕满28周的2158例神经管缺陷儿的产前诊断情况,了解我国神经管缺陷儿产前B型超声波诊断情况.结果显示:我国神经管缺陷产前诊断的比例为61.8%,产前B型超声波诊断的比例为56.5%,其中无脑畸形、脑膜脑膨出、脊髓外翻的产前B型超声波诊断比例分别为66.7% 、62.5%、52.5%.胸段(46.4%)、腰段(43.4%)的脊柱裂产前B型超声波诊断的病例较颈段 (35.5%)、骶段(31.7%)高(P<0.05).省级、市级、县级及部队工矿医院神经管缺陷的产前B型超声波诊断比例分别为55.7%、59.4%、49.0%、57.2%.1991～1993年神经管缺陷产前B型超声波诊断比例分别为53.5%、55.8%、60.7%、54.7%.无脑畸形、脑膜脑膨出、脊髓外翻产前B型超声波诊断的比例较高.     

Assessment of Photoinduced Frontal Polymerization Processes for a Stable 1K System

Frontal polymerization (FP) has attracted increasing interest in recent years in various applications. This polymerization method can be very promising for the polymerization of thick materials with high fillers content in the range of 50–80% (weight) by local application of a reasonable amount of energy. In this work, recent advances in controllable and predictive behavior for photoinduced frontal photopolymerization are reported. Here, tert-butyl peroxybenzoate (Luperox-P) is selected to initiate thermal polymerization at depth because its high polymerization ability and its decomposition temperature is in a promising range, i.e., neither extremely high (monomer decomposition) nor very low (storage stability issues). Thermal imaging experiments are used to follow the temperatures in the samples in real time. The number of cured layers and the depth of cure are also determined. This paper investigates various factors such as the contents of both photo and thermal initiators, the light intensity, the fiber contents, the irradiation time, etc., resulting in a statistical design of experiments with the factors: 1) content of Luperox P and 2) the irradiation time used to investigate the influence on photoinduced frontal polymerization. Markedly, FP appears to be fully controllable for a storage-stable, tunable 1K system.     

Mitochondrial myopathy: correlation between oxidative defect and mitochondrial DNA deletions at single fiber level

In situ hybridization combined with immunohistochemical techniques has been applied to study patients affected by mitochondrial myopathies with large mitochondrial (mt)DNA deletions. All patients' muscle biopsies showed ragged red fibers (RRFs) and cytochrome oxidase (COX) deficiency. Two digoxygenin-labeled, polymerase chain reaction (PCR)-amplifed DNAs were used as probes. One probe was designed to hybridize only with wild-type mtDNAs, while the other recognized both wild-type and deleted mtDNAs. Concomitant immunocytochemical analysis using antibodies against subunits II, III, (encoded by mtDNA) and IV (encoded by nuclear DNA) of COX was carried out. In our patients deleted mtDNAs are overexpressed in COX-negative RRFs, while wild-type mtDNAs are decreased in the same fibers. Immunohistochemistry studies show that COX IV is overexpressed in RRFs and that COX II and COX III subunits are still present. Deleted mtDNAs are spatially segregated in muscle fibers, where they interfere with the local population of normal mitochondrial genomes, causing a regional deficiency of the mitochondrial respiratory activity.This work was supported by the Associazione Amici del Centro Dino Ferrari     

Release and actions of adenosine in the central nervous system

Adenosine is released from active neurons into the extracellular fluid at a concentration of about 1mol/l. Neither the precise cellular origin nor the biochemical form of release has been firmly established, though the nucleotide is probably released partly directly, as a result of raised intracellular levels, and partly as nucleotides, which are subsequently hydrolysed. Once in the extracellular medium, adenosine markedly inhibits the release of excitatory neurotransmitters and modulatory peptides and has direct inhibitory effects on postsynaptic excitability via A₁ receptors. A population of A₂ receptors may mediate depolarization and enhanced transmitter release. Adenosine also modulates neuronal sensitivity to acetylcholine and catecholarnines, all these effects probably contributing to the behavioural changes observed in conscious animals. As a result of their many actions, adenosine analogues are being intensively investigated for use as anticonvulsant, anxiolytic, and neuroprotective agents.     

Regeneration of neuronal nitric oxide synthase (nNOS)-containing nerve fibers in rat corpus cavernosum

Aim: To investigate the effect of cavernous nerve injury on the nNOS-containing nerve fibers in rat corpus cavernosum.Methods: Thirty-three male SD rats were randomized into 3 groups: 5 rats underwent pelvic exploration without tran-section of cavernous nerve as the sham-operated controls, the unilateral injury group (14 rats) had the cavernous nerve cuton one side, and the bilateral injury group (14 rats) had the nerves cut on both sides. Corpora cavernosa were harvestedat the 3rd week and 6th month after surgery, nNOS-positive nerve fibers were examined with strepavidin peroxidase im-munohistochemistry techniques (SP method). Results: After bilateral ablation, the nNOS-positive nerve fibers weresignificantly decreased at both the 3rd week ( 17 ± 4) and the 6th month (16 ± 4). For the unilateral injury group, thenNOS-positive nerve fibers were similarly decreased on the side of the neurotomy at the 3rd week (18 ± 6), but by the 6thmonth, the number increased significantly (61±9) and approximated th     

High resolution evoked potentials of cognition

Summary The precision of four methods of quantifying neuroelectric signals has been improved by increasing EEG spatial sampling, using up to 124 electrodes, and by accurate anatomical registration of the EEG with Magnetic Resonance Images (MRIs). One such method, equivalent dipole modeling, is a well-known form of source localization which is useful when the generator of the scalp recorded signal approximates a simple dipolar source, as is usually the case with early and mid-latency Evoked Potentials (EPs). Two methods of enhancing spatial detail which benefit from increased spatial sampling include the Laplacian Derivation and the Finite Element Deblurring method. The latter is a new technique which estimates the EP distribution at the superficial cortical surface. The fourth method, Evoked Potential Covariance, characterizes the spatiotemporal relationships among EP segments at different recording sites. This is useful when studying functional neural networks underlying higher cognitive functions. These methods are reviewed and examples of results of their application in recent experiments are presented.Supported by competitive grants from The National Institute of Mental Health, The National Institute of Neurological Diseases and Stroke, The Air Force Office of Scientific Research, The Office of Naval Research, The National Science Foundation NASA and The National Institute on Alcohol Abuse and Alcoholism of the United States Federal Government. Thanks to all members of the EEG Systems Laboratory and SAM Technology, past and present, for their vital contributions to the work presented here.This paper is based on an invited lecture given at the Tenth Anniversary Meeting of The Japanese Society for Brain Electromagnetic Topography held in Fukuoka, Japan in September, 1992.     

Metabolic and neuroanatomical correlates of barrel-rolling and oculoclonic convulsions induced by intraventricular endothelin-1: a novel peptidergic signaling mechanism in visuovestibular and oculomotor regulation?

The neuroactive peptide endothelin-1 has receptors distributed abundantly among subdivisions and nuclei of the visuovestibular and oculomotor systems. In previous work, we and others described the convulsive manifestations resulting from central injection of this neuropeptide, including nystagmus, oculoclonus, exophthalmos, tonic hindlimb extension, and a generalized repetitive motor disturbance called barrel-rolling. We applied the quantitative, autoradiographic [¹⁴C]deoxy-glucose method to examine the hypothesis that visuovestibular and oculomotor structures would become metabolically stimulated when endothelin was introduced into the brain via the ventricular system in conscious rats. Since previous work had demonstrated that hypermetabolic responses to endothelin in other neural systems were inhibited by an antagonist of neuronal calcium L-type channels, nimodipine, we further tested whether the increased function of vestibulooculomotor nuclei whose metabolic activity was sensitive to endothelin could be altered following nimodipine pretreatment via the ventricle. A single unilateral injection of endothelin (9 pmol in 3 l saline) into a lateral ventricle provoked significantly increased rates of glucose metabolism in 22 of 39 individual anatomical structures of the visuovestibular and oculomotor systems. Among those affected were the superficial stratum of the caudal superior colliculus (+25%), the optic tract bilaterally (+ 35 to 43%), the oculomotor cranial nerve nuclei (III, IV, VI; range of +21 to 47%), and the medial terminal nucleus of the accessory optic tract which harbors dense fields of endothelin binding sites (bilateral increase of +70 to 96%). Several other nuclei involved in the proprioceptive and visuovestibular disturbance caused by endothelin displayed increased metabolic activity, including the cuneate, gracile, sensory trigeminal, and prepositus hypoglossal nuclei, the vestibular subnuclear system, and the cerebellar flocculus. Identification of hypermetabolic responsivity to endothelin in these structures provides further information on the anatomical substrates mediating the behavioral phenomenology of endothelin-induced motor convulsions which involve the paroxysmal participation of the extraocular muscles and motor control systems producing barrel-rolling convulsions. Nimodipine pretreatment inhibited both the convulsive activity and the cerebral hypermetabolic responses to intraventricular endothelin. The results indicate that the neural systems sensitive to intraventricular endothelin become functionally active via a calcium-mediated process that may involve the neuropeptide as an intrinsic signaling molecule.     

Widespread Horizontal Connections Arising from Layer 5/6 Border Inverted Cells in Rabbit Visual Cortex

Herein we describe the inverted cells [defined as those projection neurons having a major dendritic shaft abpially oriented (Bueno-López et al., Eur. J. Neurosci. , 3, 415, 1991)] originating a unique set of cortical connections characterized by extraordinarily widespread horizontal distribution. Single and multiple injections of wheatgerm agglutinin - horseradish peroxidase were made in areas 17 and 18 and the resulting retrograde labelling in the cortex was analysed. The findings were assessed in independent control experiments in which Fluoro-Gold was used as retrograde tracer. Following single injections in area 17 several separate patches of labelled cells comprising layers 2–6 were consistently found in area 18. In addition to these associational cells a number of labelled cells appeared at the layer 5/6 border but were distributed over most of the tangential extent of the visual occipital cortex. This widespread pattern was particularly striking in brains after multiple injections. In these brains a conspicuous band of labelled cells at the 5/6 border radiated from the injection sites, making up an apparently continuous horizontal sheet that intersected the striate - extrastriate boundary and merged with the patches of labelled cells in area 18 and beyond. Most of the cells in the 5/6 border band were inverted cells (82%; n = 2081). Injections in area 18 failed to produce such a widespread set of labelled cells in area 17. The functional significance of these connections furnished by the 5/6 border inverted cells remains to be determined, but their distribution would allow for convergent/divergent binding interactions both intra-areally (within area 17) and inter-areally (from area 18 to area 17).