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Biomedical subjects

T Günther

Publications and source records attributed to T Günther.

At least 127 records · Page 7Linked to original sources

Effect of salicylate on copper metabolism in maternal and fetal rats.

Pregnant Wistar rats were treated with 5 oral doses of 100 or 300 mg/kg salicylic acid from day 16 to 20 of gestation. At day 21 of gestation, copper concentrations were measured in serum, liver and cell organelles of liver from dams and litters after cell fractionation. Salicylate caused a reduction of maternal serum Cu and an increase in fetal liver Cu. The increase of Cu in fetal liver was proportional to the Cu content of the organelles. It was concluded that salicylate bound Cu and transferred Cu from maternal serum to the fetus. The increase in fetal liver Cu was explained by displacement of Zn from Zn-metallothionein by Cu, because Zn-metallothionein is high in fetal liver and Cu has a higher affinity to metallothionein than Zn. Such a mechanism was not significant in maternal liver because of the low Zn-metallothionein content in maternal liver.

Animals↗

Magnesium-induced hypocalcemia in salicylate-treated pregnant rats.

Pregnant and non pregnant rats were fed diets with different Mg content and treated with 5 oral doses of 300 mg/kg salicylic acid for 5 consecutive days or from day 16 to 20 of gestation. One day after the final dosage, serum Mg and Ca concentrations were measured by atomic absorption spectrophotometry. In maternal rats, salicylate caused a strong decrease of serum Ca with increasing serum Mg concentrations (r = -0.8706). In fetal and nonpregnant adult female rats, serum Ca was not significantly decreased by salicylate with increasing serum Mg concentrations. However, the hypocalcemic effect of salicylate was found when nonpregnant young growing rats were fed a Ca-deficient diet.

Animals↗

Increased lipid peroxidation in liver mitochondria from Mg-deficient rats.

Feeding young rats an Mg-deficient diet for 4 weeks increased serum-Fe concentration from 38.2 to 43.7 mumol/L and non Hb-Fe content in liver from 6.33 to 9.31 mmol/kg dry weight. The increase in non Hb-Fe occurred in all liver cell fractions. In heart and kidney, Fe content was not significantly changed by Mg deficiency. Lipid peroxidation measured by formation of malondialdehyde was only increased in liver mitochondria from Mg-deficient rats. Therefore, an Mg-deficiency-induced increase in non Hb-Fe may be involved in the increased lipid peroxidation of liver mitochondria, but cannot represent a general mechanism in the toxicity of Mg deficiency.

Animals↗

Age-dependent accumulation of cadmium in rats exposed to contaminated drinking water; interactions with zinc and copper and subcellular Cd distribution in kidney cells.

One of each pair of female sister rats aging 1, 4, 7 or 10 months was exposed during 3 months to 31.5 mg/L Cd (as CdCl2) in its drinking water and sacrificed immediately after Cd exposure together with its untreated sister. Concentrations of Cd, Zn and Cu were measured in the kidneys (medulla and cortex), the liver, the duodenum and the uterus. Furthermore, the subcellular distribution of Cd was measured in renal tissue. The accumulation of metal ions, defined as the difference between Cd-treated and untreated rats, was pronounced in all tissues except the uterus and was significantly decreased at increasing age. Multivariate analysis of variance revealed significant interaction with Zn and Cu. Higher Cd accumulation in the tissues of young animals probably depends on the higher consumption of contaminated drinking water per kilogram of body weight. High concentrations of Cd detected in cell nuclei may be due to the similarity between Cd2+ and Ca2+.

Aging↗

Biochemical mechanisms affecting susceptibility to noise-induced hearing loss.

In magnesium (Mg)-deficient rats and guinea pigs, noise-induced hearing loss (NIHL) was found to be correlated to the decrease of Mg in serum and perilymph. Also, in noise-exposed humans, NIHL increased with decreasing serum Mg. During the process of mechanoelectrical transduction within the hair cells in the inner ear, membrane permeability of K+ and Ca2+ will transiently increase. Mg deficiency may additionally increase membrane permeability and, therefore, energy-dependent K+ and Ca2+ turnover. The increased release of catecholamines in Mg deficiency may affect the hair cells, either directly by increasing the intracellular concentration of free Ca2+ and/or indirectly by reducing the blood flow. Also, thromboxane A2, which is increased in Mg deficiency, may reduce the blood flow in the inner ear. By these mechanisms, Mg deficiency may cause energy depletion and irreversible damage to the hair cells.

Animals↗

Concentrations of magnesium, zinc and copper in serum of patients with acquired immuno-deficiency syndrome.

The concentrations of Mg, Zn, Cu and albumin, and pseudocholinesterase activity were measured in the sera of 31 AIDS patients, 27 belonging to group IVC1 and 4 to group IVC2. Mean values for all patients were within the normal ranges. Only two patients showed hypozincaemia. A correlation was found between the concentrations of serum zinc and albumin. The serum albumin concentration was correlated with the serum pseudocholinesterase activity.

Acquired Immunodeficiency Syndrome↗

Enhancement of maternal and fetal nephrotoxicity of salicylate by zinc deficiency. Morphological, enzyme histochemical and immunohistochemical studies.

An oral dose of 700 mg/kg salicylic acid was given to normal and Zn-deficient rats at day 16 of gestation. Maternal and fetal kidneys were studied at day 19 of gestation. Zn-deficiency did not cause any lesions detectable by semi-thin section light microscopy, electron microscopy, enzyme histochemistry and immunohistochemistry. Salicylate may lead only to small morphological, enzymatic and cytoskeletal defects in the maternal and fetal kidney. However, enzyme activities decreased in plasma membranes, mitochondria, lysosomes, endoplasmic reticulum and peroxisomes in all segments of the tubular apparatus when salicylate was given to Zn-deficient rats. Cytoskeletal proteins such as keratin in the glomerular cells and epithelial lining of the collecting ducts and vimentin in vascular endothelial cells of the maternal kidney were also affected. In addition, the epithelial cells of the collecting ducts, which were comparatively less damaged, accumulated high amounts of fat. In severe cases, the enzymatic and cytoskeletal lesions were accompanied by hematuria and tubular necroses including and collecting ducts in the renal papilla. In less severe cases reduced activities of brush border hydrolases were the only sign of disturbed renal function in maternal rats indicating that membrane alteration and loss of membrane-bound enzymes are the primary defects. In the fetal kidneys, mitotic activity of the cells of the nephron anlagen and collecting ducts was reduced and enzymatic and morphological differentiation were disturbed. As a consequence less mature nephrons and collecting ducts occurred.

Animals↗

Enhanced ototoxicity of gentamicin and salicylate caused by Mg deficiency and Zn deficiency.

In rats, Mg deficiency caused a moderate hearing loss, measured by means of evoked potentials at 10 and 20 kHz, which was repaired after refeeding a normal diet. Application of 700 mg/kg salicylic acid or injection of 5 x 100 mg/kg gentamicin also caused a reversible hearing loss in normally fed rats. Treatment of Zn-deficient rats with salicylic acid produced a stronger although reversible hearing loss than in normally fed salicylate-treated rats. Treatment of Mg-deficient rats with gentamicin induced a strong hearing loss that was nearly complete and irreversible in 9 of 25 rats.

Animals↗

Effects of salicylate and zinc deficiency on the serum concentrations of magnesium, calcium, and parathyroid hormone.

Oral application of 700 mg/kg salicylic acid to pregnant and non-pregnant female rats caused an increase of serum Mg2+ and a decrease of serum Ca2+ concentration. The salicylate effect was drastically enhanced by Zn deficiency. The increase in serum Mg2+ is probably caused by the nephrotoxicity of salicylate. The decrease of serum Ca2+ concentration is combined with an increase of parathyroid hormone concentration in serum. Probably, salicylate and Zn deficiency inhibit Ca2+ mobilization by parathyroid hormone in bone.

Animals↗

Maternal and fetal iron accumulation in Zn-deficient and salicylate-treated rats.

Nonhemoglobin Fe (non Hb-Fe) content in fetal serum and liver is much higher than in maternal serum and liver. After feeding a Zn-deficient diet to pregnant rats from d 0 to 21, non Hb-Fe content in maternal and fetal serum and liver was increased. After oral application of salicylic acid (300 mg/kg) from d 16 to 20 to normally fed and Zn-deficient dams, non Hb-Fe content in maternal and particularly in fetal serum and liver was drastically increased. In the kidney, Fe was accumulated to a small amount resulting from Zn deficiency and salicylate treatment. Fe accumulation in the liver occurred in all cell fractions, particularly in microsomes. Fe accumulation was confirmed and extended histochemically by Prussian blue staining. It is assumed that salicylate increases intestinal Fe resorption and fetal transfer of Fe. It is discussed that salicylate nephrotoxicity and its enhancement by Zn deficiency is not caused by an Fe-dependent mechanism.

Animals↗

Effects of trifluoperazine and membrane-bound sialic acid on 45Ca2+ uptake into erythrocytes.

After removal of more than 70% of the sialic acid from the erythrocyte membrane by treatment with neuraminidase, trifluoperazine (TFP) increased the rapid and slow phase of 45Ca2+ uptake into erythrocytes, identically to Ca2+ uptake into untreated erythrocytes from patients with tetanic syndrome. Both phases of 45Ca2+ influx were inhibited by extracellular Mg2+, Ki amounted to 4 mmol/l. However, the increased 45Ca2+ influx into patient erythrocytes in the presence of TFP was not caused by a reduced sialic acid content in the patients' erythrocytes. It was concluded that erythrocytes from patients with tetanic syndrome either bind more TFP or, if the same amount of TFP is bound, it has a stronger effect on 45Ca2+ influx.

Calcium Radioisotopes↗

Characterization of Na+/Mg2+ antiport by simultaneous 28Mg2+ influx.

During net Mg2+ efflux from Mg2+-preloaded chicken erythrocytes, which occurs via Na+/Mg2+ antiport, 28Mg2+ is taken up intracellularly. Km of 28Mg2+ influx amounted to 1 mM. In Na+-free medium Vmax of 28Mg2+ influx was increased and Km was reduced to 0.2 mM. 28Mg2+ influx was noncompetitively inhibited by amiloride as was found for Na+/Mg2+ antiport. The results indicate that, extracellularly, Mg2+ can compete with Na+ for common binding sites of the Na+/Mg2+ antiporter, resulting in 28Mg2+-24Mg2+ exchange. The rate of Mg2+ exchange depends on extracellular Na+ and on the rate of net Mg2+ efflux.

Amiloride↗

Enzymatic and morphological response of the thymus to drugs in normal and zinc-deficient pregnant rats and their fetuses.

In the thymus of normally fed pregnant rats the plasma membrane enzymes dipeptidyl peptidase IV (DPP IV) and alkaline phosphatase (alP) were found in cortical and medullary lymphocytes (thymocytes). Plasma membrane aminopeptidase A (APA) and adenosine monophosphate hydrolysing phosphatase (AMPP) were present in cortical reticular cells. In medullary reticular cells, aminopeptidase M (APM), gamma-glutamyl transferase (GGT), adenosine triphosphate (ATPP) and thiamine pyrophosphate (TPPP) cleaving phosphatases were detected. Medullary reticular cells did not contain APA. Lysosomal DPP I and II, acid phosphatase, acid beta-D-galactosidase, beta-D-N-acetyl-glucosaminidase, beta-D-glucuronidase and non-specific esterases occurred especially in macrophages at the corticomedullary junction. The 21-day-old fetal thymus showed a similar reaction pattern as the maternal organ except for APA which was absent before birth. After treatment of the pregnant rats with valproic acid (VPA), salicylic acid (SA), streptozotocin (ST) and retinoic acid (RA) APA showed an increase in activity in the thymic cortex. In addition, ST and RA induced AMPP, ATPP and TPPP activity in cortical reticular cells up to the same pattern as in medullary reticular cells. After ethanol (ET) administration severe damages occurred. The thymic cortex was free of DPP IV-positive lymphocytes; the medullary reticular cells showed reduced or no GGT and occasionally an increased APM activity. Dexamethasone (DEXA) given to normal or zinc-deficient rats produced the most severe lesions; thymocytes with DPP IV activity were completely absent in the cortex and medulla. In Zn-deficient pregnant rats similar alterations were observed as after ET.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Evaluation of the genetic and embryotoxic effects of bis(tri-n-butyltin)oxide (TBTO), a broad-spectrum pesticide, in multiple in vivo and in vitro short-term tests.

The genetic and embryotoxic effects of bis(tri-n-butyltin)oxide (TBTO) were evaluated in multiple in vivo and in vitro short-term tests preparatory to its potential wide use as a molluscicide in control of schistosomiasis. When tested in the rec assay in Bacillus subtilis, TBTO was not mutagenic and it did not induce reverse mutations in Klebsiella pneumoniae. Neither in the presence nor in the absecne of rat liver activation system did TBTO produce point mutations in Salmonella typhimurium strains TA1530, TA1535, TA1538, TA97, TA98 or TA100. TBTO was matagenic in strain TA100 in a fluctuation test, but only in the presence of rat liver S9 (Aroclor-induced). TBTO did not induce gene mutations in the yeast Schizosaccharomyces pombe, mitotic gene conversions in the yeast Saccharomyces cerevisiae, nor sister-chromatid exchange in Chinese hamster ovary cells in the presence or absence of rat or mouse liver S9. In the latter cells, structural chromosomal aberrations, endoreduplicated and polyploid cells were induced. TBTO did not induce gene mutations in V79 Chinese hamster cells (to 8-azaguanine-, ouabain- or 6-thioguanine-resistance) in the presence of a rat liver postmitochondrial fraction or in cell (hamster embryo cells and human and mouse epidermal keratinocyte)-mediated assays. In mouse lymphoma cells, TBTO did not induce 6-thioguanine- or BUdR-resistant mutations. As many tumour promoters inhibit metabolic cooperation between V79 Chinese hamster 6-thioguanine-resistant/-sensitive cells, TBTO was tested but showed no such activity. TBTO was examined for the induction of recessive lethal mutations in adult Berlin K male Drosophila melanogaster, either by feeding or by injection. Doses of 0.37 or 0.74 mM did not increase the number of X-linked recessive lethal mutations. An increased number of micronuclei was observed in the polychromatic erythrocytes of male BALB/c mice 48 h after a single oral dose of TBTO (60 mg/kg bw), while a lower dose (30 mg/kg bw) was ineffective. Neither of the two doses had induced micronuclei 30 h after treatment. The reproductive toxicity of TBTO was studied in NMRI mice. In a 10-day toxicity study, the LD50 and LD10 were 74 and 34 mg/kg bw, respectively. An increased frequency of cleft palates was seen in the fetuses of mice (compared with controls, 0.7%) treated orally during pregnancy with 11.7 mg/kg TBTO (7%), 23.4 mg/kg (24%) or 35 mg/kg (48%).(ABSTRACT TRUNCATED AT 400 WORDS)

Abnormalities, Drug-Induced↗

Alterations of electrolytes in serum and erythrocytes after myocardial infarction.

Electrolyte concentrations in serum and erythrocytes of 56 myocardial infarction (MI) patients and 50 patients having had an orthopedic operation or an accident were measured up to 2 weeks after the event. Several hours after the MI, considerable percentages of patients had had pathologically low serum concentrations of either K, Ca or Mg. In the erythrocytes of the Mi group, K was decreased and Ca increased during the entire period of investigation, whereas the serum electrolytes K and Ca had normalized by day 15, at which time only half of the patients with pathologically low serum Mg had reached the normal Mg range. By correlation analysis it was shown that the more the Ca concentration in the serum was decreased after MI, the less was the concentration of brain muscle creatine kinase.

Adult↗

Amiloride-sensitive net Mg2+ efflux from isolated perfused rat hearts.

Coronary blood vessels of isolated spontaneously beating rat hearts were perfused with an Mg2+-free solution at a rate of 3 ml/min. 1.5-ml fractions were sampled. Net Mg2+ efflux from heart muscle cells was measured by the increase of Mg2+ concentration in the perfusate. Addition of 0.3 microM isoproterenol to the perfusate resulted in a rapidly occurring transient Mg2+ efflux which was inhibited by amiloride.

Amiloride↗

Characterization of furosemide-sensitive Mg2+ influx in Yoshida ascites tumor cells.

Partially Mg2+-depleted Yoshida ascites tumor cells took up Mg2+ after reincubation in Mg2+- and HCO3(-)-containing media. Mg2+ influx was insensitive to ouabain, amiloride and disulfonic stilbenes, but was noncompetitively inhibited by furosemide (Ki = 0.4 mM) and bumetanide. Mg2+ influx obeyed Michaelis-Menten kinetics with respect to Mg2+ concentration (Km = 1.1 mM) and was sigmoidal with respect to HCO3- concentration. Electroneutral Mg2+, HCO3- cotransport was supposed to be the mechanism of Mg2+ influx.

Amiloride↗