Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011570 (depression)
 172,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The cell-mediated immune (CMI) mechanism was evaluated in 10 space shuttle astronauts by measuring their delayed-type hypersensitivity response to seven common recall antigens. The Multitest CMI test system was used to administer antigens of tetanus, diphtheria, Streptococcus, Proteus, old tuberculin, Candida, and Trichophyton to the forearm 46 h before nominal mission termination; readings were conducted 2 h after landing. The mean number of reactions was reduced from 4.5 preflight to 3.0 inflight, and the mean reaction score was reduced from 21.4 to 13.7 mm inflight. The data presented suggest that the CMI system is still being degraded by space flight conditions on day 4 and that between day 5 and day 10, the depression maximizes and the system begins to adjust to the new conditions. The relation of these in vivo findings to previously reported in vitro results is discussed.
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PMID:In vivo testing confirms a blunting of the human cell-mediated immune mechanism during space flight. 143 48

The effects of 2,3-butanedione monoxime (BDM) on contraction characteristics were studied at 5 degrees C in single intact fibres isolated from the tibialis anterior muscle of the frog. The force-velocity relation was determined using the controlled-velocity method in either whole fibres or short fibre segments in which sarcomere shortening was measured by a laser light diffraction method. It is shown that 3 mM BDM decreases the speed of rise and the amount of tetanus tension, reduces the maximum velocity of shortening and increases the curvature of the force-velocity relation, as well as the value for the stiffness to tension ratio. BDM also slowed down the redevelopment of tetanus tension after a period of unloaded shortening both in fixed-end and in length-clamp conditions. In normal and in BDM-treated fibres length-clamping increased the speed of the initial rise of tetanus tension but not that of the recovery after shortening. The observed force-velocity data points were fitted by the Huxley (1957) equation. It was found that BDM produces a conspicuous decrease of the rate constant for crossbridge attachment. This effect, and also a reduction of the force per crossbridge, are responsible for the depression of the contractile characteristics produced by BDM.
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PMID:Effects of 2,3-butanedione monoxime on the crossbridge kinetics in frog single muscle fibres. 146 80

To define conserved domains within the light (L) chains of clostridial neurotoxins, we determined the sequence of botulinum neurotoxin type B (BoNT/B) and aligned it with those of tetanus toxin (TeTx) and BoNT/A, BoNT/C1, BoNT/D, and BoNT/E. The L chains of BoNT/B and TeTx share 51.6% identical amino acid residues whereas the degree of identity to other clostridial neurotoxins does not exceed 36.5%. Each of the L chains contains a conserved motif, HExxHxxH, characteristic for metalloproteases. We then generated specific 5'- and 3'-deletion mutants of the L chain genes of TeTx and BoNT/A and tested the biological properties of the gene products by microinjection of the corresponding mRNAs into identified presynaptic cholinergic neurons of the buccal ganglia of Aplysia californica. Toxicity was determined by measurement of neurotransmitter release, as detected by depression of postsynaptic responses to presynaptic stimuli (Mochida, S., Poulain, B., Eisel, U., Binz, T., Kurazono, H., Niemann, H., and Tauc, L. (1990) Proc. Natl. Acad. Sci. U. S. A. 87, 7844-7848). Our studies allow the following conclusions. 1) Residues Cys439 of TeTx and Cys430 of BoNT/A, both of which participate in the interchain disulfide bond, play no role in the toxification reaction. 2) Derivatives of TeTx that lacked either 8 amino- or 65 carboxyl-terminal residues are still toxic, whereas those lacking 10 amino- or 68 carboxyl-terminal residues are nontoxic. 3) For BoNT/A, toxicity could be demonstrated only in the presence of added nontoxic heavy (H) chain. A deletion of 8 amino-terminal or 32 carboxyl-terminal residues from the L chain had no effect on toxicity, whereas a removal of 10 amino-terminal or 57 carboxyl-terminal amino acids abolished toxicity. 4) The synergistic effect mediated by the H chain is linked to the carboxyl-terminal portion of the H chain, as demonstrated by injection of HC-specific mRNA into neurons containing the L chain. This finding suggests that the HC domain of the H chain becomes exposed to the cytosol during or after the putative translocation step of the L chain.
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PMID:Minimal essential domains specifying toxicity of the light chains of tetanus toxin and botulinum neurotoxin type A. 163 16

1. Whether the function of the postsynaptic acetylcholine receptor is use-dependently affected by repetitive nerve stimulation in the presence of competitive antagonists was studied in the mouse phrenic nerve-hemidiaphragm preparation. 2. For electrophysiological experiments, the preparation was immobilized by synthetic mu-conotoxin, which preferentially blocks muscular Na-channels causing neither depolarization of the membrane potential, inhibition of quantal transmitter release, nor depression of nicotinic receptor function. 3. High concentrations of cobratoxin depressed indirect twitches and endplate potentials (e.p.ps) without inducing waning of contractilities or run-down of trains of e.p.ps evoked at 10-100 Hz. However, waning and run-down were accelerated after washout of the toxin despite diminished postsynaptic receptor blockade. Once the run-down of e.p.ps was produced by washout or low concentrations of cobratoxin, further depression of e.p.p. amplitude with high concentrations of cobratoxin did not attenuate the e.p.p. run-down. 4. The degrees of waning of tetanus and trains of e.p.ps produced by a very high concentration of tubocurarine (20 microM) were also less than that caused at a 100 fold lower concentration, albeit the amplitudes of twitches and the first e.p.p. were depressed more rapidly and markedly. 5. Tubocurarine, like cobratoxin, depressed the amplitude of miniature endplate potentials (m.e.p.ps) more than e.p.ps. 6. In contrast to the steepened run-down of successive e.p.ps in the presence of low concentrations of either nicotinic antagonists, the amplitude of m.e.p.ps observed during repetitive stimulation was uniform and was not different from that before stimulation. 7. The results suggest that the e.p.p. run-down and tetanic fade induced by nicotinic antagonists are due to a slow kinetic blockade of presynaptic receptors and confirm that the e.p.p. run-down is not produced by a use-dependent failure of postsynaptic nicotinic receptors. The roles of the presynaptic nicotinic receptor in positive or negative feedback modulations of transmitter release are discussed.
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PMID:Run-down of neuromuscular transmission during repetitive nerve activity by nicotinic antagonists is not due to desensitization of the postsynaptic receptor. 167 97

All the experiments were carried out in slices of rat prefrontal cortex maintained in vitro. The effect of 2-amino-5-phosphonovalerate (APV) was tested on the postsynaptic potential (PSP) recorded in layer V pyramidal cells, in response to single or high frequency stimulation of the superficial layers I-II. Wash-out of Mg2+ increased the amplitude and duration of the PSPs. This effect resulted from activation of N-methyl-D-aspartate (NMDA) receptors since it was suppressed by bath application of APV. Furthermore, in every cell tested in Mg2+ containing medium (N = 16), exposure to APV reversibly reduced both mono- and polysynaptic components of the PSPs, indicating that, even in the control solution, activation of NMDA-coupled channels contributed to these synaptic events. Finally, the anomalous voltage-dependence of the EPSP in the presence of Mg2+ and its sensitivity to APV suggests that at least a fraction of the NMDA receptors are postsynaptically located. Tetanization was applied to the afferents of cells bathed in control- or APV-medium. Long-term potentiation (LTP) or long-term depression (LTD) is defined as an increase or a decrease respectively, of the PSPs peak amplitude or initial slope, lasting 20 min. In the control medium, LTP in synaptic efficacy was observed in 34% of the cells and LTD in 48% (N = 23). When exposed to APV, none of the cells tested (N = 16) showed LTP of the response. In contrast, the tetanus induced a LTD of the PSP amplitude or slope in 14 out of these 16 cells. The percentage of cells showing LTD in synaptic efficacy (87%) when the NMDA receptors activation was blocked was significantly higher than that in control-medium.
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PMID:Blockade of NMDA receptors unmasks a long-term depression in synaptic efficacy in rat prefrontal neurons in vitro. 168 Jul 38

The chronic epileptic syndrome induced by injecting tetanus toxin into rat hippocampus causes functional changes that essentially are permanent, outlasting the period of active seizures by at least 1 year. These long-term changes have been characterized by an impaired performance on a range of behavioral tasks, which in turn have been associated with a physiologic depression of hippocampal evoked responses but not with any discernible histopathology. In the present study, we examined the hippocampi of rats in the postseizure phase of the tetanus toxin model and observed no significant changes in the concentration of neurochemical markers for six neurotransmitters. Therefore, the long-term reduction in hippocampal excitability cannot be attributed to any major loss of afferents or hippocampal neurons using aspartate, acetylcholine, gamma-aminobutyric acid (GABA), glutamate, norepinephrine (NE), or serotonin as their transmitters.
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PMID:Lack of change in neurochemical markers during the postepileptic phase of intrahippocampal tetanus toxin syndrome in rats. 170 Sep 50

The effect of ruthenium red (RR) on the electrical and contractile responses, membrane Ca currents, staining patterns of the external and internal membrane system were tested in intact and mechanically skinned muscle fibres of the crayfish Astacus fluviatilis. The following results were obtained: 1. Depression of the contractile responses following membrane depolarization (twitch, tetanus, potassium contractures). 2. Caffeine contractures were unaffected in intact (100 mumol/l - 1 mmol/l RR) and blocked in skinned fibres (30 mumol/l RR). 3. Mechanical threshold and mechanical latency were increased and/or prolonged. 4. The rate of depolarization of the action potentials (AP) was decreased and decremental spread of AP was recorded. 5. Both fast and slowly inactivating Ca ionic currents were decreased and the time constants of activation (tau(m] and inactivation (tau(h] were prolonged after RR (100 mumol/l) pretreatment. 6. The penetration of RR into the T-system was inversely related to its binding to the sarcolemma. The depression of depolarization-induced contractions was most pronounced in fibres with unstained sarcolemma and stained T-tubules. In intact fibres, neither terminal cisternae nor other elements of SR were stained. On the contrary, all internal membrane structures were stained in skinned fibres. There was a gradient of staining intensity from surface toward the interior.
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PMID:Effects of ruthenium red on excitation and contraction in muscle fibres with Ca2+ electrogenesis. 170 75

A randomized, double-masked, placebo-controlled clinical trial was conducted with 236 preschool children, age 3-6 y, in Indonesia to assess immune status in mild vitamin A deficiency. The immune response to tetanus immunization was used as a measure of immune competence. Clinically normal children (n = 118) and children with mild xerophthalmia (n = 118) were randomly assigned to receive oral vitamin A (60,000 micrograms retinol equivalent) or placebo treatment for a total of four study groups. Two weeks after treatment, children were immunized with diphtheria-pertussis-tetanus vaccine. The immunoglobulin G (IgG) responses to tetanus at baseline and 3 wk following immunization were measured by ELISA. After adjusting for previous tetanus immunization, clinically normal and xerophthalmic children receiving vitamin A had a significantly greater IgG response to tetanus than clinically normal and xerophthalmic children receiving placebo (P less than 0.05). These results suggest that children with mild vitamin A deficiency have a relative immune depression compared with children who have been supplemented to normal vitamin A levels.
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PMID:Depressed immune response to tetanus in children with vitamin A deficiency. 172 57

The results of medical examinations carried out on 212 missionary personnel from one missionary society returning on leave to the UK are presented. The great majority of missionaries worked in developing countries. They served in 27 countries altogether and for a total of 488 person years. The commonest illnesses reported overseas were malaria (87.3 per 1000 person years at risk), diarrhoea (63.5), anxiety (63.5), depression (41.0) and giardiasis (38.9). More illnesses were reported from West Africa (698 per 1000 person years at risk) than from any other region. Ten people (4.7%) were repatriated for health reasons and 10 relatives also returned as a consequence. Sixty per cent of those returning did so because of psychiatric illness. The highest rates of immunization achieved were for yellow fever (100% of those travelling to affected countries), tetanus (93%), polio (85%), typhoid (71%) and tuberculosis (53%). The results of urinalysis (100% of adults), full blood counts (78% of adults) and stool tests (74% of all people) are reported. The study shows that the history and psychiatric examination are an important part of the medical examination of people returning from overseas. Physical examination and urinalysis did not contribute much information, although the full blood count and absolute eosinophil count were useful tests.
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PMID:A survey of the health of British missionaries. 185 37

The effects of removing extracellular Ca++ ions or of adding the organic calcium channel antagonist, nitrendipine, were tested on twitches and tetani (100 Hz for 2 sec) in frog toe muscles. Under conditions that did not reduce or that potentiated twitches, both procedures reduced the size of the tetanic responses. This depression was seen as an inability to maintain the maximum tetanic tension for more than 0.5 sec. Intracellular microelectrode recordings showed that the muscle fibers were depolarized (mean about 23 mV) during the stimulus train and the fiber only slowly repolarized after the train. The latter effect is the "late negative afterpotential" and it is produced by the accumulation of K+ ions in the t-tubules during the action potential train. Neither the depolarization nor the late negative afterpotentials were decreased in amplitude by nitrendipine. These results indicate that the voltage-sensitive, slow Ca++ channels are opened by the accumulation of K+ ions in the t-tubules during the tetanus and that the Ca++ ions entering via these channels are required to maintain the full strength of the tetanic contraction. It is suggested that this is a function of these Ca++ channels concentrated in the t-tubules of skeletal muscle fibers.
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PMID:Decrease in the size of tetanic responses produced by nitrendipine or by extracellular calcium ion removal without blocking twitches or action potentials in skeletal muscle. 190 44


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