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

The mechanisms controlling secretion of glucagon and other pancreatic hormones were studied in a patient affected with multihormone-secreting islet-cell tumor. Fasting glucagon levels (3,000 pg./ml.) rose to 10 ng./ml. following arginine stimulation. While oral glucose load and intravenous glucose infusion did not suppress glucagon secretion, insulin administration induced a prompt depression in glucagon levels. Glucagon, insulin, and gastrin levels were suppressed by somatostatin while calcium infusion caused a paradoxical increase. It is suggested that only some of the stimulation-inhibition mechanisms were conserved in this case of glucagon-secreting pancreatic tumor.
 ...
PMID:Suppression and stimulation mechanisms controlling glucagon secretion in a case of islet-cell tumor producing glucagon, insulin, and gastrin. 0 26

Some preparations of both native aspartate transcarbamylase from Escherichia coli and catalytic subunit have fewer tight binding sites per oligomer for carbamyl-P than the number of catalytic peptide chains. In contrast, the number of sites for the tight-binding inhibitor N-(phosphonacetyl)-L-aspartate does equal the number of catalytic chains in each case. Binding of the labile carbamyl-P was determined using rapid gel filtration, with conversion to stable carbamyl-L-aspartate during collection. Native enzyme (six catalytic chains) obtained from cells grown under the conditions of J.C. Gerhart and H. Holoubek (J. Biol. Chem. (1967) 242, 2886-2892) has 5.4 tight sites for carbamyl-P at pH 8.0 (KD = 9.9 muM), whereas native enzyme from cells grown with higher concentrations of glucose, uracil, and histidine (to yield more enzyme per unit volume of culture) has only 1.9 tight sites at pH 8.0 (KD = 4.6 muM) and only 2.3 tight sites at pH 7.0 (KD = 2.6 muM). At pH 8.0, catalytic subunit (three catalytic chains) obtained from the former native enzyme has 2.2 tight sites for carbamyl-P (KD = 2.4 muM) and the number of sites is 2.3 in the presence of 35 mM succinate, whereas catalytic subunit obtained from the latter native enzyme has 1.8 tight sites (KD = 3.6 muM) in the absence of succinate and 2.3 tight sites in its presence. The number of tight binding sites is also less than the number of subunit peptide chains in 19F nuclear magnetic resonance experiments performed with catalytic subunit and two fluorinated analogs of carbamyl-P at comparable concentrations of analogs and active sites. A model is proposed in which incomplete removal of formylmethionine from the NH2 termini of the enzyme under conditions of extreme depression affects affinity for ligands.
 ...
PMID:Aspartate transcarbamylase of Escherichia coli. Heterogeneity of binding sites for carbamyl phosphate and fluorinated analogs of carbamyl phosphate. 0 9

Growth of Escherichia coli, based upon the fermentation of glucose, is associated with a low intracellular level of superoxide dismutase. Exhaustion of glucose, or depression of the pH due to accumulation of organic acids, causes these organisms to then obtain energy from the oxidative degradation of other substances present in a rich medium. This shift in metabolism is associated with a marked increase in the rate of synthesis of superoxide dismutase. Depression of the synthesis of superoxide dismutase by glucose is not due to catabolite repression since it is not eliminated by cyclic adenosine 3',5'-monophosphate and since alpha-methyl glucoside does not mimic the effect of glucose. Moreover, glucose itself no longer depresses superoxide dismutase synthesis when the pH has fallen low enough to cause a shift to a non-fermentative metabolism. It appears likely that superoxide dismutase is controlled directly or indirectly by the intracellular level of O2- and that glucose depressed the level of this enzyme because glucose metabolism is not associated with as rapid a production of O2- as is the metabolsim of many other substances. In accord with this view is the observation that paraquat, which can increase the rate of production of O2- by redox cycling, caused a rapid and marked increase in superoxide dismutase.
 ...
PMID:Regulation of superoxide dismutase synthesis in Escherichia coli: glucose effect. 2 Nov 64

Human rheumatoid synovial lining cells have up to four times the capacity to oxidize glucose 6-phosphate, the first step of the hexose monophosphate pathway, as do the nonrheumatoid cells. The reducing equivalents produced by this system have many significant metabolic effects. Exposure of these cells by 10(-5) M prednisolone in vitro, or to 6 mg/day in vivo, causes some depression of this activity in the rheumatoid synovial lining cells; less than this dose of steroid, or the administration of nonsteroidal drugs in vivo, has little or no effect. The depression of activity produced by 6 mg/day does not bring this activity down to the value found in nonrheumatoid synoviocytes.
 ...
PMID:Effect of glucocorticoids on the hexose monophosphate pathway in human rheumatoid synovial lining cells in vitro and in vivo. 2 37

The possible role of glutamate dehydrogenase, glutamate synthase, and glutamine synthetase in the regulation of enzyme formation in the gamma-aminobutyric acid (GABA) catabolic pathway of Escherichia coli K-12 was investigated. Evidence is presented indicating that glutamine synthetase acts as a positive regulator in the E. coli GABA control system. Mutations impairing glutamate synthase activity prevent the depression of the enzymes of the GABA pathway in ammonia-limited glucose media. However, mutations resulting in constitutive synthesis of glutamine synthetase (GlnC) restore the ability of the glutamate synthase-less mutants to grow in glucose-GABA media and result in depressed synthesis of the GABA enzymes. It is suggested that the loss of glutamate synthesis activity affects the GABA control system indirectly by lowering glutamine synthetase levels.
 ...
PMID:Regulation of gamma-aminobutyric acid degradation in Escherichia coli by nitrogen metabolism enzymes. 2 37

Since diffuse changes in blood flow and metabolism occur in the brain following a focal ischemic insult, changes of cerebral blood flow on the side opposite a cerebral infarction were observed. We have examined the course of the cerebral hemodynamic changes occurring in 15 patients with unilateral acute strokes. In 12 of these patients, significant blood flow changes (over 15%) occurred in the nonischemic hemisphere during the period of observation. A similar time course of change was found in the ischemic hemisphere and the flow changes in the two hemispheres appeared parallel to one another (diaschisis). Thus we have demonstrated a significant reduction in flow in the contralateral cortex following a unilateral ischemic insult. This reduction in flow was of the order of 38% from the control value which agrees quite well with the reduction in cortical glucose consumption of the order of 31%. We postulate that these changes are the hemodynamic and metabolic concomitants of diaschisis and may in part be due to a transneuronal depression of function.
 ...
PMID:Alterations in regional cerebral hemodynamics and metabolism produced by focal cerebral ischemia. 3 23

Many specific plasma proteins show dose-related changes when oral estrogens are administered. Large increases in concentration are seen in many important binding proteins, such as the sex hormone-binding globulin, transcortin, the retinol-binding protein, ceruloplasmin, and transferrin. A smaller group of plasma proteins are reduced in amount. These changes are related to altered rates of hepatic synthesis and secretion. As the overall effect of estrogen is one of increased protein synthesis, there is a reduction in the amount of plasma-free amino acids and in the pattern of distribution. Oral contraceptive (OC) users frequently show significant alterations in biochemical tests of vitamin status, at least some of which are related to alterations in plasma proteins. Other biochemical changes associated with OC use include a fasting hyperlipidemia, due mainly to increases in triglycerides, although there is often also a small increase in cholesterol. These changes are due primarily to increases in several lipoprotein fractions and are related mainly to the estrogen component. A deterioration in glucose tolerance occurs in many OC users and is probably induced by both estrogens and progestogens. There is evidence that certain clinical side effects of OCs, such as depression, are associated with specific biochemical changes.
 ...
PMID:Biochemical basis for the selection of oral contraceptives. 3 19

Lipogenic capacity of various dietary carbohydrates starch, glucose sucrose and lactose was tested during ad lib feeding and starvation followed by refeeding. Sucrose was found to have maximal effect on hepatic total lipid and the enzymes in the study followed by glucose and sago while lactose was found to be toxic. Starvation resulted depression in the activities of various enzymes. The enzyme activity inducing effect was again exhibited by sucrose diet during ad lib and restricted refeeding followed by starvation.
 ...
PMID:Effect of different dietary carbohydrates on some hepatic dehydrogenases and total lipid during starvation and refeeding regimen. 3 90

The metabolic effects of 60-min exposure to 250-2000 mg gamma-hydroxybutyrate (GHB) per kilogram or 150-1200 mg gamma-butyrolactone (GBL) per kilogram were studied in rats by measurement of the cerebral hemisphere contents of energy phosphates and glycolytic-Krebs' cycle metabolites. A general pattern of increased glycogen and glucose with decreased pyruvate, lactate, alpha-ketoglutarate, and malate was observed. This pattern in association with unchanged adenylates and decreased energy phosphate utilization was consistent with a metabolic adaptation to a state of cerebral depression. The major qualitative difference between the two drugs was that higher doses of GBL were associated with additional decreases of citrate and glutamate. Since these doses of GBL were also associated with acute increases of arterial CO2 tension, it is proposed that these differences were secondary to hypercapnia and not due to a distinctive primary action of GBL. Derivation of the cytoplasmic NAD(P)H:NAD(P)+ ratios indicated that GHB and GBL were not associated with consistent alterations of the cytoplasmic redox state.
 ...
PMID:A comparison of the effects of gamma-hydroxybutyrate and gamma-butyrolactone on cerebral carbohydrate metabolism. 4 Jun 77

Dextran B1355 induces a direct PFC response detectable with dextran B512-sensitized red cells which is directed towards an alpha1--6-linked glucose epitope. This response is distinguishable from the alpha1--3-linked specificity assayed by homologous sensitization in that: (a) it is totally suppressed in donors previously rendered tolerant of B512; (b) the PFC are sensitive to inhibition by B512 and isomaltohexaose. The alpha1--6 epitope of B1355 is less immunogenic in BALB/c mice than that with alpha1--3 linkage, inducing a lower amplitude of response and requiring a 100-fold greater minimal dose, while conversely, it is the more effective tolerogen. No alpha1--6-specific response develops in 50 per cent of mice given 10 mg of B1355 and all become totally unresponsive within 14 days. This tolerant state remains stable when spleen cells are transferred to irradiated recipients. By comparison, parallel depression of the alpha1--3 response is not great and rapidly lost by similar transfer. No correlation was observed between the levels of alpha1--6 suppression and alpha1--3 response induced by 10 mg of B1355 in individual mice. The dissociative aspects of the responses to these two epitopes present on the same molecule are discussed in relation to some current theories of B-cell tolerance induction. It is argued that the present findings are contrary to those models which attribute a causal role to mitogenic overstimulation or failure to generate an extrinsic 'second signal'.
 ...
PMID:Influence of molecular structure of the tolerogenicity of bacterial dextrans. III. Dissociation between tolerance and immunity to the alpha1--6- and alpha1--3-linked epitopes of dextran B1355. 5 14


1 2 3 4 5 6 7 8 9 10 Next >>