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)

After incubation at pH 10 or higher, Bacillus thuringiensis spores and endotoxin, at concentrations above 0.1 IU/ml, affected transport parameters in the isolated midgut of Manduca sexta larvae. (Toxic activity was lost during roughly 1 week at pH 11.) About 60% of the short-circuit current was inhibited, and the remainder was reversibly inhibited by anoxia. Electrical resistance was reduced by about 55% and oxygen uptake stimulated by about 30%. Influx of potassium from blood-side to lumen-side ('active' flux) was unaffected but flux in the reverse direction was nearly tripled. These results suggest that hydrolysis of the toxin yields an inhibitor of potassium transport, presumably a polypeptide. It is argued that inhibition is not primarily by uncoupling of oxidative phosphorylation, but instead by interference with an active depression of the efflux of potassium from lumen-side to blood-side.
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PMID:Mechanism of inhibition of active potassium transport in isolated midgut of Manduca sexta by Bacillus thuringiensis endotoxin. 4 81

In order to understand the mechanism of decreased protein synthesis in the liver of rats fed a protein-free diet, the average polypeptide chain assembly time (tc) was measured by the method of Mathews et al. (J. Biol. Chem. (1973) 248, 1329). For rats fed a normal diet, tc in liver in vivo was 1.28 min. A 10-day period of protein depletion led to a value of tc = 2.08 min, corresponding to a 38% depression in polypeptide elongation rate. Protein depletion caused an extensive breakdown of hepatic polysomes and refeeding of a complete mixture of amino acids resulted in rapid recovery of polysomal profile. But tc in the liver of the refed animals gave still depressed value of 1.95 min. The amount and size distribution of poly(A)-containing mRNA in the liver, as determined by [3H]poly(U) hybridization, were the same for normal and depleted groups. These results suggest that both initiation and elongation steps of protein synthesis are depressed in the liver of protein-depleted rats. Refeeding of amino acid mixture rapidly restores initiation but not elongation activity.
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PMID:The effect of protein depletion on the rate of protein synthesis in rat liver. 10 91

Previous in vitro studies of the metabolism of the peripheral nerve have been based on incorporation of radioactive precursor into components isolated from whole nerve. In this study we have determined incorporation secifically into myelin components of peripheral nerve by isolating myelin after incubating whole nerves with lipid or protein precursors and by determining the specific activity of the components of that membrane. The effect of diabetes on such incorporation was also studied. In the rat, in vitro incorporation of DL-[1-14C]leucine into protein components of myelin was decreased by 30-88% in diabetic animals as compared to controls. The major polypeptide constituent of rat sciatic nerve myelin (mol st 28,000; 58.5% of total mass of proteins) was not labeled in either the diabetic or the control group. In diabetes incorporation rate into a polypeptide of mol wt 23,000, which constitutes 21% of total mass, was approximately one half that of controls. In polypeptides of mol wt 38,000-49,000, which are heavily labeled in normal animals, but constitute only about 5% of total mass of proteins, depression of incorporation was e-en more marked in the diabetics. While these marked differences in incorporation between diabetic and control animals were observed, the amount of protein and its distribution among the constituent polypeptides was the same in both groups. In young rats made diabetic with streptozotocin and young rabbits made diabetic with alloxan, there was a lower rate of incorporation of the lipid precursors, [1-14C]sodium acetate or [3H]water, into myelin components. In older animals of both species incorporation in the controls was considerably lower than in the yount animals, and the effect of diabetes was no longer apparent. In nondiabetic animals, the in vitro addition of insulin (10-7 M) stimulated incorporation of DL-[1-14C]leucine into myelin proteins 1.6-3.1 times that of controls. This stimulation by insulin in vitro was not seen in diabetic animals. In animals in which diabetes had spontaneously recovered, however, incorporation rate in the in vitro experiments approached that of controls and were significantly above that in animals whose diabetes persisted. Since myelin is the palsma membrane of the Schwann cell, these studies provide evidence that the Schwann cell is affected by insulin and that some aspects of the metabolism of myelin are altered in insulin-deficient states.
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PMID:Metabolism of peripheral nerve myelin in experimental diabetes. 12 35

It has been reported previously that in cats pre-treatment for 24 to 48 hours with neomycin sulphate resulted in a change in the pattern of neuromuscular block subsequently produced with this antibiotic. The unique characteristics of neomycin-induced neuromuscular block observed during acute exposure gave way to a pattern of block usually observed with tubocurarine. In a similar experiment on six cats we have demonstrated that with polymyxin B prolonged exposure did not result in a comparable time-dependent change in the nature of the neuromuscular block it produced, in terms of train-of-four, tetanic, and post-tetanic behaviour of the neurally-elicited muscle response. The differing characteristics of neuromuscular block seen with various antibiotics, e.g. the aminoglycoside neomycin as opposed to the polypeptide polymyxin B, during acute and sub-chronic exposure is stressed. Previously observed ability of 4 aminopyridine 0.6 mg/kg to reverse the neuromuscular and cardiovascular depression during acute exposure to polymyxin B persisted in prolonged exposure.
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PMID:Neuromuscular and cardiovascular depression produced by prolonged exposure to Polymyxin B. 20 22

The effects of the polypeptide antibiotic, polymyxin B, on myocardial contractility were studied in t;e isolated rat heart muscle. Five different doses of polymyxin B were tested. There were no changes in contractility with does ranging from the clinical therapeutic value to three times greater. There was an initial increase and then depression with a dose six times greater than the therapeutic dose. There was no direct competitive interaction between polymyxin B and halothane or Ca2+. This suggests that polymyxin B does not depress the myocardium in clinical doses and does not interfere with Ca2+ influx at the myocardial cell membrane.
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PMID:Polymyxin B and heart muscle. 22 88

Growth of Escherichia coli K-12 strains in the presence of the vitamin cyanocobalamin (B12) resulted in an 80 to 90% reduction in B12 uptake activity of washed cells. Coincident with the decline in uptake activity was the depression of B12-binding activity in energy-poisoned cells, suggesting that growth in B12 resulted in the repression of synthesis of the B12 receptor protein in the outer membrane. Growth in the presence of B12 led to marked reduction in sensitivity to the E colicins, whose adsorption to cells requires the B12 receptor, and to a decrease in the amount of a band on electropherograms of outer membrane proteins. That polypeptide was also missing from mutants altered at btuB, the locus encoding the B12 receptor. Addition of B12 to growing cultures resulted in the exponential decline in specific activity of B12 uptake, as expected for dilution of functional receptors by further growth. Repression of receptor synthesis appears to be regulated by the level of intracellular, rather than extracellular, B12 and is separate from the regulation of the methionine biosynthetic pathway. Mutants altered in btuC, which are defective in accumulation and retention of B12, exhibit a much lower degree of repressibility.
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PMID:Repression of synthesis of the vitamin B12 receptor in Escherichia coli. 36 85

Synthetic salmon calcitonin was administered subcutaneously to 12 inpatients with several primary psychotic diagnoses. Increases in serum total calcium and inorganic phosphorus levels and decreases in CSF calcium level had earlier been observed during periodic psychotic agitation or mania. By contrast, calcitonin, which decreased serum calcium and phosphorus levels and increased CSF calcium level, appeared to produce transient (24-hour) increases in depression and decreases in arousal in this double-blind placebo-controlled trial. Quantitative activity monitoring confirmed the rater's impression that this agent had tranquilizing or depressant effects in such patients. When given in the evening, this polypeptide also appeared to delay sleep onset, as demonstrated both by nurses' 30-minute sleep checks and by the same longitudinal activity record. A decreased hypocalcemic response to calcitonin was noted in the agitated patients, which might explain the increases in serum calcium level described at the "switch".
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PMID:Use of calcitonin in psychotic agitation or mania. 76 Jun 98

Inotropic effects of angiotensin II were studied in 26 anesthetized dogs with different conditions of autonomic activity. The values of maximal velocity of contraction (Vmax TP) were compared before and 10 minutes after the arterial pressure was elevated by the infusion of the drug. In eight dogs, previously treated with atropine and reserpine, the administration of angiotensin had no effect on mean values of Vmax TP. Nine animals submitted to ganglionic blockade by hexamethonium presented an improvement of myocardial contractility when angiotensin was infused. In nine dogs studied with intact nervous system, infusion of the drug was accompanied by decrease of mean values of the index. It was concluded that the polypeptide exerts no important physiological effects upon myocardial contractility without the mediation of the autonomic nervous system. It was considered that the positive inotropic effect verified in dogs under ganglionic blockade was due to adrenergic hyperactivity induced by angiotensin. The depression of the contractile state observed in intact animals was supposed to be mediated by variations of autonomic nervous system activiity consequent to baroreceptor reflex.
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PMID:Role of the autonomic nervous system in the inotropic variations induced by the infusion of angiotensin II. 123 24

Seasonal affective disorder is a form of depression which recurs at the same time of the year. Exposure to bright artificial light at a dose of 2,500 lux is used to treat seasonal affective disorders. We exposed a pigmented (Brown Norway) and a nonpigmented (Sprague-Dawley) rat strain with bright artificial light for 21 days at two doses (2,500 and 6,100 lux) and analyzed dopamine, dihydroxyphenyl-acetic acid, 5-hydroxytryptamine (5-HT), and 5-hydroxyindole-acetic acid (5-HIAA) by high performance liquid chromatography (HPLC) and electrochemical detection in eight different brain regions. Furthermore, we measured tissue levels of substance P (SP), neurokinins (NK), vasoactive intestinal polypeptide (VIP), calcitonin gene-related peptide (CGRP), and neuropeptide Y (NPY) with radioimmunoassay. Our data obtained with light microscopy show that bright artificial light at both doses induced a massive destruction of photoreceptors in the retina of albino rats but not of the pigmented rat strain. Retinal lesion of photoreceptors resulted in increased tissue levels of all measured neuropeptides except SP in the hypothalamus and increased VIP in the ventral tegmental area/substantia nigra. Furthermore, increased 5-HT and 5-HIAA tissue levels were found in the ventral tegmental area/substantia nigra. In contrast, in the frontal cortex there was a significant reduction in 5-HIAA tissue levels and a decreased 5-HIAA/5-HT ratio, indicating decreased 5-HT metabolism. Light exposure of the pigmented rat strain revealed no changes in the measured biogenic amines and neuropeptides in any investigated brain region. Our data suggest that retinal lesion but not direct visual neurotransmission induced changes in neurotransmitters in some brain regions. We conclude that Brown Norway rats but not Sprague-Dawley rats are useful to study neurochemical effects of bright artificial light. However, Sprague-Dawley rats may be a useful tool to study biochemical mechanisms of photoreceptor damage by bright light.
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PMID:Effects of bright artificial light on monoamines and neuropeptides in eight different brain regions compared in a pigmented and nonpigmented rat strain. 152 5

An alanine-rich, alpha-helical antifreeze polypeptide (AFP) from the winter flounder and seven analogs with variations in the arrangement of neutral, polar amino acids were synthesized. Circular dichroism studies determined that all of the peptides, except for one containing a proline residue, were essentially 100% alpha-helical. Freezing point depression data, analyzed by three methods, showed that rearrangement of polar residues resulted in moderate to complete loss of anti-freeze activity. It was observed that ice crystals grow as hexagonal bipyramids in dilute solutions, with a constant c to alpha axis ratio of about 3.3. Above a critical threshold concentration, which may depend on the AFP to ice binding constant and reflect the onset of cooperative interactions, growth ceases until the temperature is lowered to the freezing point. We conclude that a specific arrangement of both threonine and asparagine (or aspartic acid) residues is critical for maximal activity and that the AFPs probably bind to the pyramidal faces of ice with a specific orientation. These conclusions are consistent with a recent report (Knight, C. A., Cheng, C. C., and DeVries, A. L. (1991) Biophys. J. 59, 409-418) that a similar AFP adsorbs to the [2021] pyramidal planes of ice in dilute solution.
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PMID:Structure-function relationships in an antifreeze polypeptide. The role of neutral, polar amino acids. 162 10


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