Glutamatergic neurotransmission in alcoholism

Substance abuse and dependence is the most common psychiatric problem. Alcohol is the most commonly abused substance and most people who abuse other substance(s) abuse alcohol at the same time. Accumulating evidence suggests that neurophysiological and pathological effects of ethanol are mediated to a considerable extent via the glutamatergic system. Ethanol disrupts glutamatergic neurotransmission by inhibiting the response of the N-methyl-D-aspartate (NMDA) receptor and by promoting neuronal toxicity through upregulation of the NMDA receptor density. Therefore, short-term/acute ethanol treatment results in a blockade of NMDA receptor-mediated neurotransmission and apoptotic cell death by inhibiting the trophic effect mediated by the NMDA receptor whereas chronic ethanol treatment and withdrawal results in an enhanced toxic response toward glutamate. The neurobiology of human alcoholism such as ethanol intoxication, dependence, withdrawal seizures, delirium tremens, Wernicke-Korsakoff syndrome, and fetal alcohol syndrome can be better understood as a spectrum of consequences of ethanol's effect on the NMDA glutamatergic system.     

Muscular dystrophy: Centronucleation may reflect a compensatory activation of defective myonuclei

Muscular dystrophy has long been believed to be characterized by degeneration and abortive regeneration of muscle fibers (the muscle degeneration theory), but unfortunately its pathogenesis is still unclear and an effective treatment has yet to be developed. As a challenge to the theory, we have proposed an alternative muscle-defective-growth theory and a further bone muscle growth imbalance hypothesis supposing possible defects in bone-growth-dependent muscle growth based on our findings in hereditary dystrophic dy mice (C57BL/6Jdy/dy). This review presents some new insights into the pathogenesis of the disease along with our hypothesis, focusing on the physiological meaning of centronucleation, one of the major pathological changes commonly observed in dystrophic muscles of man and experimental animals.     

Evaluation of self-similar features in time series of serum growth hormone and prolactin levels by fractal analysis: Effect of delayed sleep and complexity of diurnal variation

We assayed the diurnal concentrations of growth hormone (GH) and prolactin (PRL) in 6 healthy male volunteers to evaluate the self-similar features in the time series of each hormone on the basis of fractal theory and to determine the fractal dimension as an index of the complexity of the diurnal variation. In addition, we assessed the effects of a 6-hour delay in the sleep period on the complexity of the diurnal variaton of these hormones. There was a statistically significant fractal feature in the serum levels of GH both under the nocturnal-sleep and delayed-sleep conditions in all subjects. The time series of the serum PRL concentrations also showed a statistically significant fractal feature under the nocturnal-sleep and delayed-sleep conditions in all subjects. The fractal dimensions of the patterns of the GH or PRL levels were 1.879 and 1.929 or 1.754 and 1.785 under the nocturnal-sleep and delayed-sleep conditions, respectively. Two-way ANOVA revealed no significant difference in the fractal dimension between the two sleep conditions but did reveal a significant difference between the fractal dimensions of the GH and PRL levels. These results showed (1) that delayed sleep had no significant effect on the complexity of the diurnal pattern of these hormones, and (2) that the diurnal pattern of the GH levels was more complex than that of the PRL levels.     

An outbreak of phaeohyphomycosis in rainbow trout caused by Scolecobasidium humicola

A previously undescribed host for the opportunistic dematiaceous hyphomycete, Scolecobasidium humicola, is reported. Several epizootics among rainbow trout, Salmo gairdneri, occurred in a Tennessee fish hatchery from 1969 to 1973. Symptoms included surface lesions, blisters and abscesses. The kidneys and other internal organs were invaded by the mycelium of S. humicola. Tissue morphology of the fungus was typical of that associated with phaeohyphomycosis. Experimental infections were reproduced in fingerling rainbow trout after intraperitoneal inoculation of S. humicola. Following a change in the hatchery's water supply, no new epizootics have occurred.     

Mating behaviour of Microsporum equinum with Nannizzia otae

Twelve isolates of Microsporum equinum and nine monoascospore cultures of Nannizzia otae were studied on Sabouraud dextrose agar, polished rice grain, and on Pablum cereal agar for their gross morphology and micromorphology. The urease activity of each isolate was determined on Christensen's urea broth, and the in vitro hair perforation test was performed according to Ajello and Georg's technique. The 12 M. equinum isolates were paired with nine tester strains of N. otae (108 crosses) and with five M. canis isolates that were nonfertile with N. otae (60 crosses). The M. equinum isolates were also paired with each other in all possible combinations (78 crosses) on soil-hair medium, Pablum cereal agar, and oatmeal salts agar.Whereas most of the macroconidia produced by the M. equinum isolates were smaller than those of N. otae, some were in the size range of the latter species. Both species hydrolyzed urea within 8 to 14 days. Although N. otae isolates perforated hair consistently, none of the M. equinum isolates perforated hair in vitro. The crosses between N. otae and M. equinum cultures, between isolates of M. canis (that were incompatible with N. otae) and the isolates of M. equinum, and between M. equinum isolates among themselves were nonreactive. These differences strongly support the view that M. equinum is a distinct species and should not be treated as a synonym of M. canis (N. otae).     

Experimental histoplasmosis capsulati in athymic nude mice

Granuloma formation in nude (nu/nu) mice and their heterozygous littermates (nu/+ mice) against Histoplasma capsulatum var. capsulatum infection was studied.A culture of H. capsulatum var. capsulatum, isolated from a granuloma in the nasal cavity of a Japanese patient, was used in this experiment. Sixteen specific-pathogen-free male nu/nu and 32 nu/+ mice were used in this study.The nu/+ mice were divided into two groups. Sixteen nu/+ mice in one group and 16 nu/nu mice were inoculated intraperitoneally with 10⁶ yeast cells of the fungus, those in the other group of nu/+ mice were inoculated intravenously with the same number of the yeast cells. Two mice out of each group were sacrificed 2, 3, 7, 11, 14, 18, 25 and 30 days after inoculation, and each of their organs was examined histopathologically. In addition, pieces of these tissues were cultured on Sabouraud's dextrose agar slants.In the nu/+ mice inoculated intraperitoneally, although the fungus was recovered from the spleen, kidney and lymph nodes during the initial course of the infection, lesions were not detected in their histopathological sections. In the nu/+ mice inoculated intravenously, colonies were recovered from all of the organs examined, other than the brain and thymus, 7 days after inoculation.Histopathologically, a few microfoci consisting chiefly of mononuclear cells with or without yeast cells were found in the liver sections 4 days after inoculation. Seven and 11 days after inoculation the number of lesions had increased. They had large accumulations of mononuclear cells. From day 14 on, almost all of the yeast cells had lost most of their staining affinity or were destroyed in the granuloma. From day 25 on, the granulomatous lesions changed gradually to fibrous tissue.In the nu/nu mice the fungus was readily recovered from the spleen, liver, kidney and lymph nodes. Histopathologically, a few microfoci consisting of mononuclear cells were present in the liver sections 4 days after inoculation. That is to say, during the initial course of infection granulomas were formed. In the liver, from day 7 on, the lesions were large and their number increased. However, there was a definite difference between the nu/nu and nu/+ mice. In the former, the yeast cells were not killed, and they continued to multiply within the granulomas. These granulomas were never transformed into fibrous tissue.     

Kappa opioid agonists inhibit transmitter release from guinea pig hippocampal mossy fiber synaptosomes

Opioid agonists specific for the , , and opioid receptor subtypes were tested for their ability to modulate potassium-evoked release of L-glutamate and dynorphin B-like immunoreactivity from guinea pig hippocampal mossy fiber synaptosomes. The opioid agonists U-62,066E and (–) ethylketocyclazocine, but not the agonist [D-Ala²,N-MePhe⁴,Gly⁵-ol]-enkephalin (DAGO) nor the agonist [D-Pen^2,5]enkephalin (DPDE), inhibited the potassium-evoked release of L-glutamate and dynorphin B-like immunoreactivity. U-62,066E, but not DAGO or DPDE, also inhibited the potassium-evoked rise in mossy fiber synaptosomal cytosolic Ca²⁺ levels, indicating a possible mechanism for agonist inhibition of transmitter release. DAGO and DPDE were found to be without any effect on cytosolic Ca²⁺ levels or transmitter release in this preparation. The U-62,066E inhibition of the potassium-evoked rise in synaptosomal cytosolic Ca²⁺ levels was partially attenuated by the opioid antagonist quadazocine and insensitive to the -opioid specific antagonist ICI 174,864 and the opioid-preferring antagonists naloxone and naltrexone. Quadazocine also reversed U-62,066E inhibition of the potassium-evoked release of L-glutamate, but not dynorphin B-like immunoreactivity. These results suggest that opioid agonists inhibit transmitter release from mossy fiber terminals through both opioid and non- opioid receptor mediated mechanisms.     

Toxic effect on human spermatozoa by Chlamydia trachomatis purified lipopolysaccharide

Abstract We have investigated the effect that lipopolysaccharide extracted from Chlamydia trachomatis has on human spermatozoa. A lipopolysaccharide of 0.1 μg ml⁻¹ caused a spermatozoa mortality rate of 65±4% evaluated by eosin exclusion test. The toxic activity occurred rapidly even after brief incubation times, reaching the maximum (100% mortality) within 60 min.     

Moulting frequency and behavioural responses to salinity and diesel oil in Austromegabalanus psittacus (Molina) (Cirripedia: Balanidae)

Moulting frequency and behavioural responses to salinity and diesel oil concentration were studied in specimens of the giant barnacle Austromegabalanus psittacus (Molina). Moulting frequency and frequency and type of cirral beat, in addition to opercular valve closure time, were measured under controlled conditions. A binary factorial experimental design was carried out at salinities of 20 and 30‰ and diesel oil concentrations of 0.1 and 0.5% v/v. Moulting frequency was greater at 30‰ than at 20‰ salinity and at 0.1% oil concentration than at both 0.5% oil concentration and in controls; it is unlikely that this signified variations in growth. Diesel oil provoked lethal effects at 0.5%, with an average lethal time of 8 days; at 0.1%, only sublethal effects were generated. Cirral beat frequency was greater at 0.1 and 0.5% diesel oil concentration than in controls. This was probably associated with an increase in metabolism, since the most frequent cirral beats are associated with respiration and the active capture of plankton. The effects of the contaminant varied with time, as observed at 15 and 60 min. The opercular valve closure time was longer in controls and decreased as diesel oil concentration increased. Results suggest that this species is highly resistant to pollution, although contaminants could provoke changes in the feeding and growth of specimens. Local variations in salinity have only minor effects on barnacle behaviour.