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)

In this paper a study is presented of the characteristics of redox-linked proton ejection exhibited by isolated beef-heart cytochrome c oxidase incorporated in asolectin vesicles. The enzyme was 90% oriented 'right-side out' as in the mitochondrial membrane. The effects on the H+/e- stoichiometry of the modalities of activation of electron flow, the pH of the medium and its ionic composition were investigated. The results obtained show that, whilst ferrocytochrome c pulses of the aerobic oxidase vesicles at neutral pH and in the presence of saturating concentrations of valinomycin and K+ to ensure charge compensation produced H+/e- ratios around 1 (as has been shown previously), oxygen pulses of reduced anaerobic vesicles supplemented with cytochrome c, gave H+/e- ratios around 0.3. The H+/e- ratios exhibited, with both reductant and oxidant pulses, a marked pH dependence. Maximum values were observed at pH 7.0-7.7, which decreased to negligible values at acidic pH with apparent pKa of 6.7-6.3. Mg2+ and Ca2+ caused a marked depression of the H+/e- ratio, which in the presence of these cations and after a few ferrocytochrome pulses, became negligible. Analysis of cytochrome c oxidation showed that the modalities of activation of electron flow and divalent cations exerted profound effects on the kinetics of cytochrome c oxidation by oxidase vesicles. The observations presented seem to provide interesting clues for the nature and mechanism of redox-linked proton ejection in reconstituted cytochrome c oxidase.
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PMID:Characteristics of the redox-linked proton ejection in beef-heart cytochrome c oxidase reconstituted in liposomes. 303 20

Guanine nucleotide-binding stimulatory regulatory protein of adenylate cyclase system, Ns, in rat erythrocytes was activated by the treatment with guanylyl 5'-imidodiphosphate or NaF-AlCl3 in the presence of Mg2+. The activation was counterbalanced to the basal state either by the removal of Mg2+ or by the addition of beta(gamma)-subunit of N protein of this system. The depression from the activated state was markedly protected by the coexistence of forskolin at the time of the deactivation depending on the dose of forskolin. EC50 of forskolin for the stabilizing effect was much lower than that for the stimulation of adenylate cyclase activity. These data indicate that forskolin has an effect on the interaction between Ns and catalytic unit of adenylate cyclase system in addition to the direct effect on the catalytic unit.
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PMID:Forskolin stabilizes a functionally coupled state between activated guanine nucleotide-binding stimulatory regulatory protein, Ns, and catalytic protein of adenylate cyclase system in rat erythrocytes. 308 54

Free intracellular magnesium in red blood cells (RBC) of 9 normotensives and 7 essential hypertensives was estimated from the amount of magnesium released by an incubation with the ionophore A 23187 (8 microM). In hypertensives, Mg released to the suspension medium was 0.42 +/- 0.10 mmol/l, thus being significantly lower than in normotensives (0.52 +/- 0.09 mmol/l; p less than 0.05). Total RBC Mg and serum Mg were not different in both groups. The chloride distribution ratio between the extracellular and intracellular concentrations was insignificantly increased in hypertensives, thus indicating a depressed intracellular chloride concentration as reported earlier. This ratio is essential for the calculation of the free intracellular Mg from equilibrated extracellular Mg. Taking the latter finding into account, no significant depression of free intracellular Mg can be detected in RBC of hypertensives in this study.
Magnesium 1988
PMID:Magnesium release from red blood cells of hypertensive man by the ionophore A 23187. 313 78

The effect of pH on the excitation-contraction coupling system of canine masseter muscle was studied by evaluating the functional integrity of the sarcoplasmic reticulum (SR) and myofibrils. Increasing proton concentration (pH 7.0-5.8) significantly reduced oxalate supported SR calcium uptake velocity, while Ca2+-stimulated, Mg2+-dependent ATPase activity was unaffected by pH. The efficiency ratio of calcium transport, or the coupling ratio (mumoles Ca2+ transported/mumoles ATP hydrolyzed), decreased from 1.094 +/- 0.042 at pH 7.0 to 0.946 +/- 0.036 at pH 6.0 (P less than 0.05) and to 0.780 +/- 0.024 at pH 5.8 (P less than 0.01). Myofibrillar pCa (-log [free Ca2+] )-ATPase activity was unaffected between pH 7.0 and pH 6.5. At pH 6.0, increasing Ca2+ concentration inhibited myofibrillar ATPase activity, and this inhibitory phenomenon was accentuated at pH 5.8. Kinetic analysis of the myofibrillar pCa-ATPase data, utilizing double-reciprocal plots, demonstrated an increase in Km at low pH. It is concluded that acidosis significantly uncouples calcium transport from ATP hydrolysis in the SR of masseter muscle and significantly alters myofibrillar ATPase activity. It is hypothesized that these defects may explain an observed depression in skeletal muscle cell function during ischemia.
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PMID:Characterization of the effect of pH on the excitation-contraction coupling system of canine masseter muscle. 315 68

Studies were done to ascertain whether dietary magnesium, manganese and boron affect the response of the rat to high dietary aluminum. Four factorially arranged experiments of 7 weeks duration were performed with weanling Sprague-Dawley male rats. The variables were the following supplements (microgram/g fresh diet): boron as boric acid, 0 and 3; aluminum as aluminum chloride, 0 and 1,000; and magnesium as magnesium acetate, 100 and 400 (experiments 1 and 4) or 100, 200 and 400 (experiments 2 and 3). In experiments 1 and 2, the diet was supplemented with 20 micrograms manganese/g as manganese acetate, in experiments 3 and 4 the supplement was 50 micrograms/g. High dietary aluminum seemed most toxic when dietary magnesium was low enough to cause a marked growth depression (100 micrograms/g). High dietary aluminum elevated the spleen weight/body weight and liver weight/body weight ratios in magnesium-deficient, but not in magnesium-adequate rats. High dietary aluminum depressed the concentrations of magnesium in bone more markedly in magnesium-deficient than adequate rats. On the other hand, aluminum seemed most toxic when dietary boron was not low. Aluminum more markedly depressed growth in boron-supplemented than boron-deprived rats. In the boron-deprived rats fed 400 micrograms magnesium/g of diet, high dietary aluminum (1,000 micrograms/g) apparently was beneficial, in experiments 2 and 3, hematocrit, and hemoglobin were actually normalized by high dietary aluminum. Plasma magnesium was significantly depressed by high dietary aluminum when the manganese supplement was 50 micrograms/g diet but not when it was 20 micrograms/g diet. On the other hand, growth was more markedly depressed by high dietary aluminum in boron-supplemented rats when the manganese supplement was 20 rather than 50 micrograms/g diet. The findings indicate that the response of rats to high dietary aluminum is influenced by magnesium, boron, and manganese nutriture.
Magnesium 1988
PMID:Dietary magnesium, manganese and boron affect the response of rats to high dietary aluminum. 318 13

Mg deficiency is a frequent complication of inflammatory bowel disease (IBD) demonstrated in 13-88% of patients. Decreased oral intake, malabsorption and increased intestinal losses are the major causes of Mg deficiency. The complications of Mg deficiency include: cramps, bone pain, delirium, acute crises of tetany, fatigue, depression, cardiac abnormalities, urolithiasis, impaired healing and colonic motility disorders. Serum Mg is an insensitive index of Mg status in IBD. Twenty-four-hour urinary excretion of Mg is a sensitive index and should be monitored periodically. Parenteral Mg requirements in patients with IBD are at least 120 mg/day or more depending upon fecal or stomal losses. Oral requirements may be as great as 700 mg/day depending on the severity of malabsorption.
Magnesium 1988
PMID:Magnesium and inflammatory bowel disease. 329 19

The anesthetic effects of the tocolytic agents, magnesium sulfate and ritodrine hydrochloride, were investigated by determining their effect on the minimal alveolar anesthetic concentration (MAC) of halothane in male and in pregnant and nonpregnant female rats. Magnesium and ritodrine were administered by continuous intravenous infusion to mechanically ventilated rats anesthetized with halothane. The tail-clamp technique was used to establish the MAC of halothane before and then again during the infusion of either magnesium or ritodrine. Ritodrine produced no change in halothane MAC. Increasing magnesium dosages and magnesium plasma levels were associated with nonlinear reductions in halothane MAC that were unrelated to sex or pregnancy. The alveolar halothane MAC concentration in pregnant rats (0.85 +/- 0.02) was not significantly different from the halothane MAC in nonpregnant female or male rats. At the highest plasma magnesium concentrations (15.8 +/- 1.57 mg/dl) achieved in the pregnant rats, the alveolar halothane MAC was 0.36 +/- 0.13, a 61.6% reduction in MAC. The anesthetic effects of magnesium were not attributable to cardiovascular, respiratory, or neuromuscular depression. Major decreases in blood pressure occurred only in the pregnant rats with the highest magnesium concentrations.
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PMID:The anesthetic contribution of magnesium sulfate and ritodrine hydrochloride in rats. 333 43

The sea urchin embryo nuclei which retained their ability to maintain the DNA synthesis in an in vitro system were isolated. The DNA synthesis isolated nuclei was shown to be an ATP-dependent process which is inhibited by low concentrations of actinomycin D, a polymerase alpha araCTP inhibitor. The newly synthesized DNA is represented by short fragments of about 4S. After addition of Ca2+, Mg2+-dependent DNAase to sea urchin embryo nuclei, the synthesis of short DNA fragments is enhanced. This stimulating effect of Ca2+, Mg2+-dependent DNAase is ATP-dependent and is observed only within a narrow range of enzyme concentrations (of the order of 1-5 units of DNAase activity per ml of incubation sample). The increase in the enzyme concentration to 10 or more units of activity results in the depression of DNA synthesis. It is concluded that DNA replication in sea urchin embryo nuclei depends on the presence of active DNAases as well as on the number of accessible initiation sites of DNA replication.
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PMID:[Effect of Ca2+, Mg2+-dependent deoxyribonuclease on DNA synthesis in cell nuclei from embryos of the sea urchin Strongylocentrotus intermedius]. 344 31

The effect of Mg infusions on cardiovascular function were investigated in 6 adult male chacma baboons over a wide range of serum Mg concentrations. There was a dose-dependent reduction in systemic vascular resistance which correlated well with serum Mg levels (r = -0.67; p less than 0.001), but arterial blood pressure was only moderately affected at serum Mg levels below 5 mmol/l. Heart rate was reduced at serum Mg concentrations above 5 mmol/l. Cardiac output and stroke work were increased at all Mg levels up to 5 mmol/l, and stroke volume increased significantly until the serum Mg level exceeded 7 mmol/l. Central venous pressure and pulmonary capillary wedge pressure were not affected by increasing magnesium levels, and there was no evidence of myocardial depression at any level of serum Mg.
Magnesium 1987
PMID:Cardiovascular effects of magnesium sulphate in the baboon. 344 7

We used isolated chick retina in vitro to study the participation of the extracellular milieu in the occurrence and propagation of spreading depression. The propagation was followed by visual observation or microphotometry and the ionic changes in the extracellular compartment were recorded with double-barreled ion-selective microelectrodes. The front of the spreading wave is accompanied by increased light scattering in the tissue and by decrease of Cl-, Na+, and Ca2+, increase of K+, and an alkaline-acid shift in the extracellular space, concomitant with the slow voltage changes characteristic of the wave. As the spread is related to the chemical steady-state of the extracellular milieu, the velocity of propagation is influenced by a balanced interplay of the chemical constituents of the superfusing solution, e.g., K+, HCO-3, and glucose facilitate, while Cl- and Mg2+ hinder the wave. Steady-state alterations induced by physical factors (temperature) or related to experimental conditions (speed and direction of superfusate flow) change markedly the velocity of propagation. Generally the procedures that cause increase of velocity augment the susceptibility of the preparation to the reaction and eventually may trigger it. Propagated spreading depression is considered as a chemical diffusion reaction pervading more intensively the inner plexiform layer of the retina.
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PMID:Retinal spreading depression and the extracellular milieu. 362 Oct 34


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