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)

Cadmium affects the induction of thymidine and thymidylate kinases in regenerating rat liver. EDTA administered simultaneously with cadmium reverses its inhibitory action on enzyme synthesis, and prevents the depression of thymidine incorporation into DNA observed in cadmium-treated animals. Zinc does not abolish the inhibitory action of cadmium on the synthesis of DNA in regenerating liver, and the incorporation of thymidine into DNA in the testes was inhibited more by intraperitoneal injection of cadmium plus zinc than by injection of cadmium alone. Inhibition of thymidine incorporation into DNA in the liver and testes was proportional to the amount of cadmium administered up to about 2 mg CdCl2/kg body weight, but surprisingly, higher doses of cadmium caused less inhibition.
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PMID:Synthesis of DNA in the liver and testes of cadmium-tested partially hepatectomized rats. 22 99

The effects of an 8-day intravenous infusion of dexamethasone (7.6 mg kg-0.75 body weight) on collagen biosynthesis and wool growth in skin were examined in four Merino wethers. Plasma dexamethasone concentrations reached their peaks during the first 24 h infusion, which were followed by relatively stable levels (c. 1 X 10(-7) M) for the next 4--5 days. Minor increases in plasma dexamethasone levels were recorded during the final 2 days of treatment. Dexamethasone concentrations quickly fell below the level of detection once infusion ceased. Marked decreases in the wet weight, thickness and protein content of skin were observed at the end of infusion. DNA content was reduced to 42.4 +/- 4.9% s.e.m. during the first 2 days of treatment, but in the next 4 days of infusion gradually increased to 85.0 +/0 12.5% of controls. The level of collagen (expressed as hydroxyproline content of its acid hydrolysate) was elevated throughout the infusion and then gradually declined in 3 weeks to about 60% of controls. The biosynthesis of collagen measured by the rate of [14C]hydroxyproline formation and the activity of proline, 2-oxoglutarate dioxygenase (EC 1.14.11.2. formerly prolyl hydroxylase) was reduced during the first half of treatment to a greater extent than the rate of [14C]proline incorporation into proteins. Wool growth was reduced by 80.4 +/- 11.6% in the post-infusion period which allowed three sheep out of four to be defleeced. Inhibition of collagen biosynthesis in sheep skin was due initially to a decrease in the activity of proline, 2-oxoglutarate dioxygenase and later to the reduced rate of proline incorporation into proteins. It was also evident that changes in biosynthetic rate of collagen were not reflected in the total level of skin collagen. The extent of wool growth depression in individual animals paralleled the changes in DNA content and the extent of collagen biosynthesis inhibition.
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PMID:Effect of intravenously infused dexamethasone on collagen metabolism in skin of merino sheep. 23 81

Ten hypophysectomized and 10 normal female albino rats, 50-days-old, were kept for 5 days and treated with tritiated thymidine 1 hour before sacrifice of the animals. The animals were weighed and the histomorphology of the palate epithelium was studied including the thickness, cell density, and DNA labeling index. The hypophysectomized rats failed to gain weight after 5 days. The palatal epithelium showed a normal morphology indicating the hypophysectomy allowed for differentiation of squamous epithelium. There was a significant reduction in the thickness of the epithelium and a reduced cell density. This was attributed to a significant decrease in DNA synthesis. The epithelial cells were lost from the surface without adequate replacement due to an expected depression in mitotic activity. DNA synthesis may be depressed due to reduced ATP synthesis resulting from suboptimal glucose metabolism and depression in protein synthesis.
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PMID:The effects of hypophysectomy upon DNA synthesis in rat oral epithelium. 26 47

A TdR carrier-transport system, believed to be facilitated diffusion, has been shown to exist in Ehrlich ascites tumour cells. It is suggested that this system is the predominant transport mechanism at low extracellular concentrations (less than 1-5 micron). The transport system was damaged considerably by 5 krad X-radiation, resulting in a 30-35 per cent reduction in the initial total TdR uptake rat at low extracellular concentrations and 15-20 min after irradiation. The extent of the damage was dependent on the age of the cells as was reflected by relative decreases in V max and Km. It can be concluded that the enhanced depression in 14C-TdR incorporation into DNA of irradiated cells when low precursor concentrations were used for monitoring, is partly attributed to the radiation-induced damage to the carrier-transport system. The permeability constant for passive diffusion in asynchronous E.A.T. cells and the endogenous natural rate of dTTP synthesis in S-phase cells were estimated.
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PMID:The effects of X-radiation on thymidine-transport kinetics and DNA synthesis in Ehrlich ascites tumour cells in relation to extracellular thymidine concentration. 30 32

The effect of long-term repeated cyclophosphamide administration at low doses on T and B lymphocyte levels in the blood, lymph nodes and thymus of the guinea pig has been studied. A significant depletion of B cell levels occurred in the blood and the lymph nodes. Although there was evidence of depression of T cell levels in both blood and thymus, these changes were not statistically significant, except in the case of total T lymphocyte levels in the blood in one experiment. It is suggested that differences in sensitivity of T and B cells to cyclophosphamide may be related to differences in proliferative turnover and in their capacity to repair damage to DNA.
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PMID:Effect of long-term cyclophosphamide treatment on T and B lymphocytes in normal guinea pigs. 30 19

The expression of the transient depression in the rate of DNA synthesis normally observed after exposure of randomly-dividing Chinese hamster V-79 or Chinese hamster CHO cells to ionizing radiation can be postponed or diminished by a post-irradiation treatment with 1.0 to 1.0 mM adenine or 1.5 mM caffeine. Caffeine may exert its effect by creating additional sites for replication in irradiated cells. Cells treated with caffeine or adenine for 2 or 4 hours after exposure to 3000 rad of 300 kVp X-rays exhibit depressed synthesis only after the removal of caffeine or adenine. These alterations in the timing of the X-ray-induced depression of the rate of DNA synthesis have no effect on X-ray-induced cell killing. Although a 4 hour post-irradiation treatment of randomly-dividing Chinese hamster V-79 cells with 1.0 or 2.0 mM caffeine potentiates X-ray-induced cell killing, this reduction in survival is due primarily to effects on cells in S-phase.
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PMID:DNA synthesis and cell survival after X-irradiation of mammalian cells treated with caffeine or adenine. 30 81

Syntheses of chromosomal proteins was studied in relation to DNA syntheses in the rat thymus following whole-body X-irradiation (600 rad). There was a considerable depression of the syntheses of DNA and histones during the first 4--48 hours after irradiation. The syntheses of histones H3 and H4 plus H2A were affected to a much greater degree than those of histones H1 and H2B, suggesting a tight coupling between the syntheses of DNA and histones H3 and H4 plus H2A. A part of the lysine-rich histones H1 and H2B, however, seems to be synthesized, even in the absence of DNA synthesis. Biosynthesis of non-histone proteins was also depressed in the thymus after irradiation. The degree of inhibition, however, was very low, except for the syntheses of a few non-histone protein components which were depressed to a considerable extent. This implies that the synthesis of the majority of non-histone proteins is independent of DNA synthesis.
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PMID:Syntheses of DNA and chromosomal proteins in the rat thymus following whole-body X-irradiation. 30 73

Cyclophosphamide was used to assess the role of suppressor cells in the contact sensitivity reaction. A single painting with 300 microgram and 30 microgram oxazolone produced poor contact sensitivity reactions (ear swelling). Cyclophosphamide (200 mg/kg) 2 days before painting increased the response to the lower doses but had less effect on the response to 3 mg oxazolone. A single feed with 10 mg oxazolone caused strong contact sensitivity while lower doses (10-1000 microgram) caused poor responses. Cyclophosphamide increased the response to the lower doses but not to the highest dose of oxazolone. These results suggested that the poor response to painting and feeding lower doses of oxazolone was due to a suppressor system which was sensitive to cyclophosphamide. A different result was obtained when contact sensitivity was measured by arrival of radioactively labelled cells. Cyclophosphamide had the greatest effect on cell arrival when high doses were fed. This indicates that ear swelling and cell arrival measure separate aspects of the contact sensitivity response. The lower doses of oxazolone, which caused little contact sensitivity, reduced the response to a standard immunizing dose. This low dose unresponsiveness occurred after either painting or feeding (Chase-Sulzberger phenomenon). It did not occur in mice treated with cyclophosphamide before the first exposure to oxazolone. This suggested that the low dose unresponsiveness was due to suppressor cells. The response to oxazolone was also assessed by DNA synthesis in the regional lymph nodes. A small dose of oxazolone (30 microgram) caused a peak of DNA synthesis on day four while a high dose (3 mg) caused a peak on day three. Pretreatment with cyclophosphamide depressed the response to 30 microgram although it increased contact sensitivity. The secondary response was smaller than the primary on days 3, 4 and 5 after immunization but larger on day two. The depression but not the increase was prevented by cyclophosphamide and was probably due to a suppressor system.
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PMID:Contact sensitivity and the DNA response in mice to high and low doses of oxazolone: low dose unresponsiveness following painting and feeding and its prevention by pretreatment with cyclophosphamide. 31 60

The intercalating dye ethidium bromide (EB), inhibits excision of pyrimidine dimers from UV-irradiated excision-proficient Escherichia coli B/r hcr+ cells. Inhibition is total at a 2.5 - 10(-4) M concentration 120 min after irradiation with a dose of 750 erg/mm2. The viability of irradiated cells diminishes in proportion to the EB concentration. Under wholly analogous conditions of cultivation and irradiation no inhibitory effect of KCN and caffeine (CFF) and only a slight effect of chloramphenicol (CAP) on dimer excision has been observed. The viability of cells is affected by these compounds but it does not appear to depend on the quantity of excised photoproducts. A change in the secondary structure of DNA induced by intercalation of EB appears to be the reason for the depression of excision of UV photoproducts.
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PMID:Effect of some drugs on excision repair in E. coli cells. 32 80

Seven temperature-sensitive mutants have been isolated in Saccharomyces cerevisiae which show a reproducible defect in DNA synthesis at the restrictive temperature. One of these is allelic with rna11 (Hartwell et al., 1970) but the remaining mutants define six complementation groups and probably represent six different genes. The gene symbol dds (for depressed DNA synthesis) is proposed. At the restrictive temperature, rna11-2, dds2-1 and dds6-1 show a rapid and almost total cessation of DNA and RNA synthesis, whilst protein synthesis continues for several hours. The remaining dds mutants show a reduced rate of DNA synthesis from the time of temperature shift (dd1, dds3, dds4) or a cessation of DNA synthesis at a later time (dds5). In some cases, RNA synthesis is affected concomitantly with, or soon after, the depression in DNA synthesis. Possible reasons for the phenotypes of these mutants, and for the relative absence of yeast mutants which are unambiguously and specifically affected in DNA synthesis, are discussed. In addition, we report the isolation of seven new alleles of known cdc genes and ten new mutants with a cell cycle phenotype that complement those already known.
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PMID:Mutants of yeast with depressed DNA synthesis. 35 10


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