Synaptic transmission of chaotic spike trains between primary afferent fiber and spinal dorsal horn neuron in the rat

Primary sensory neurons can generate irregular burst firings in which the existence of significant deterministic behaviors of chaotic dynamics has been proved with nonlinear time series analysis. But how well the deterministic characteristics and neural information of presynaptic chaotic spike trains were transmitted into postsynaptic spike trains is still an open question. Here we investigated the synaptic transmission of chaotic spike trains between primary Adelta afferent fiber and spinal dorsal horn neuron. Two kinds of basic stimulus unit, brief burst and single pulse, were employed by us to comprise chaotic stimulus trains. For time series analysis, we defined "events" as the longest sequences of spikes with all interspike intervals less than or equal to a certain threshold and extracted the interevent intervals (IEIs) from spike trains. Return map analysis of the IEI series showed that the main temporal structure of chaotic input trains could be detected in postsynaptic output trains, especially under brief-burst stimulation. Using correlation dimension and nonlinear prediction methods, we found that synaptic transmission could influence the nonlinear characteristics of chaotic trains, such as fractal dimension and short-term predictability, with greater influence made under single-pulse stimulation. By calculating the mutual information between input and output trains, we found the information carried by presynaptic spike trains could not be completely transmitted at primary afferent synapses, and that brief bursts could more reliably transmit the information carried by chaotic input trains across synapses. These results indicate that although unreliability exists during synaptic transmission, the main deterministic characteristics of chaotic burst trains can be transmitted across primary afferent synapses. Moreover, brief bursts that come from the periphery can more reliably transmit neural information between primary afferent fibers and spinal dorsal horn neurons.     

Efficacy of sonothrombolysis in a rat model of embolic ischemic stroke

The key goal in the treatment of acute ischemic stroke is fast vessel recanalization. Thrombolysis with recombinant tissue plasminogen activator (rt-PA) is efficient in humans but mean time for recanalization is within hours. Ultrasound bio-effects has been shown to facilitate rt-PA mediated thrombolysis in peripheral arteries. We used an embolic stroke model in the rat. In all rats we induced an ischemic stroke by a selective occlusion of the middle cerebral artery with whole blood clots. From an entire collective of 54 rats 47 completed the protocol (n = 7 died early). Four different groups (no treatment n = 6; full dose rt-PA treatment only [10 mg/kg per body weight] n = 14, half dose rt-PA treatment plus ultrasound n = 10, and full dose rt-PA treatment plus ultrasound n = 17) were investigated. We found a significant reduction of absolute as well as relative infarct volume in the full dose rt-PA plus ultrasound group (81+/-72 mm(3); P< 0.05) in comparison to untreated rats (253+/-159 mm(3); P < 0.05) as well as in comparison to rats treated with full dose rt-PA only (167+/-91 mm(3); P < 0.05). There were five intracranial bleedings giving a bleeding rate of 9.3%. In summary: ultrasound treatment in addition to rt-PA is more effective than single rt-PA treatment in reducing infarct volume and safe with regard to bleeding.     

Disease associations and altered immune function in CD45 138G variant carriers

The CD45 antigen is a haemopoietic cell specific tyrosine phosphatase essential for antigen receptor mediated signalling in lymphocytes. Expression of different patterns of alternatively spliced CD45 isoforms is associated with distinct functions. We recently identified a polymorphism in exon 6 (A138G) of the gene encoding CD45 (PTPRC) that results in altered CD45 splicing. The 138G allele is present at a high frequency among Japanese (23.7%), with 5.1% individuals homozygous for the G allele. In this study we show that the A138G polymorphism is the cause of altered CD45 isoform expression, promoting splicing towards low molecular weight CD45 isoforms. We further report that the frequency of A138G heterozygotes is significantly reduced in number in cohorts of patients with autoimmune Graves' disease or hepatitis B infection, whereas G138G homozygotes are absent from a cohort of Hashimoto's thyroiditis patients. We also show that 138G individuals exhibit altered cytokine production in vitro and an increased proportion of memory T cells. These data suggest that the 138G variant allele strongly influences these diseases by modulation of immune mechanisms and may have achieved its high frequency as a result of a natural selection probably related to pathogen resistance.     

Differences in [3H]-thymidine uptake of lymph node cells stimulated by Con A and PHA in H-2 congenic mouse strains.

The genetic control of the lymphocyte responsiveness to Con A and PHA-P has been studied by using inbred, H-2 congenic mouse strains. Segregation studies were carried out on F1 and backcross mice of a high and a low responder strain. According to the results, there is a strong correlation between the responsiveness of lymph node cells to mitogens and H-2 haplotypes in different H-2 congenic strains of mice and in different backcross generations. High responsiveness to PHA-P is associated with H-2b, while low responsiveness with H-2a or H-2k haplotypes, but the correlation is the inverse in response to Con A, in the parental strains and backcross mice as well. The magnitude of the responses to both Con A and PHA-P was found to be intermediate in F1 heterozygotes of a low and high responder parental strain. The effect of other non H-2 genes on the responsiveness to these mitogens has also been demonstrated.     

Medical data analysis using microprocessor-based Walsh transformations

The use of Fourier transforms based on orthogonal sinusoidal functions is well established in the analysis of spectral components in noisy medical signals. In this paper the use of Walsh transformations based on orthogonal discrete signals is described for the analysis of ‘slow-wave’ rhythms in the gastro-intestinal tract of mammals. The Walsh transform approach has the advantage that very fast algorithms can be developed since multiplications involving sinusoidal functions are replaced by additions and subtractions. These algorithms are very suitable for simple microprocessors and it is shown that, for determining the frequency of gut rhythms, simple filtering and signal conditioning preceding the microprocessor dispenses with the need for analogue to digital conversion. Hence a very simple digital microprocessing system for the continuous monitoring of gut rhythms has been produced. It has also been extended to provide filtering of signals via forward and inverse Walsh transforms.     

Changes in the blood supply of the gastrointestinal tract in rats with age

Summary Regional blood flow of the gastrointestinal (GI) tract and cardiac output have been determined in male Sprague-Dawley rats weighing from 30–726 g. The cardiac output (ml/min per kg) was highest in rats weighing 80–100 g. In heavier rats the cardiac output decreased proportionally with the body weight. The gradient of blood flow to the different parts of the GI tract develops step by step. In the weaning period the blood flow (ml/min per g tissue) through the stomach was less than that through the distal parts of the GI tract. However, the blood flow through the small intestine, cecum and large intestine was uniform at this age. In rats weighing 80–100 g the blood flow through both the cecum and large intestine was less than that through the small intestine. The gradient in blood flow through the various segments of small intestine developed last.     

Relation of impaired lymphocyte proliferative function to other major human immunodeficiency virus type 1-induced immunological changes.

Human immunodeficiency virus (HIV) type 1 (HIV-1) induces impairment of immune function reflected in reduced lymphocyte proliferative responses. Many other immune changes are induced by HIV-1, but their relationship to lymphocyte functional defects is not known. The present study was designed to correlate functional defects with other HIV disease parameters. Cryopreserved samples from 118 HIV-1-positive subjects and 40 seronegative individuals were examined. The main findings were that impaired proliferative responses to mitogens correlated with (i) decreased cell surface expression of the interleukin-2 receptor (CD25), (ii) increased expression of HLA-DR antigens on CD4 cells, (iii) reduced CD4 and increased CD8 cell numbers, and (iv) increased levels of serum immune complex dissociated p24 antigen. However, impaired function was not associated with increased serum neopterin, beta2-microglobulin, or soluble interleukin-2 receptor or with CD38 antigen expression on lymphocytes. In summary, proliferative functional impairment correlated with some, but not all, immunological changes associated with HIV-1 infection. Most of the phenotypic markers that correlated with altered function are cell surface molecules with significant roles in lymphocyte proliferation and were associated primarily with CD4 cells, compatible with the view that dysregulation of CD4 cells is responsible for impaired function.     

Waterborne outbreak of Campylobacter enteritis

A report is given on an outbreak of enteritis which occurred in July 1982 in a kibbutz near Jerusalem. About 150 of the 512 inhabitants were affected.Campylobacter jejuni was isolated from ten out of 42 stool samples examined toward the end of the outbreak. No other enteric pathogen was found. Strong circumstantial evidence indicated an association between the outbreak and the use of water from an unprotected reservoir, but no bacteriological confirmation was obtained.