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Query: UMLS:C0155339 (Brown)
 12,436 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Brown trout, Salmo trutta, were exposed to water containing 0.1 microgram/l 203Hg2+, alone or with potassium ethylxanthate (PEX), sodium isopropylxanthate (SIX), sodium diethyldithiophosphate (SEP), sodium diisopropyldithiophosphate (SIP), sodium dimethyldithiocarbamate (SMC), sodium diethyldithiocarbamate (SEC) or sodium pyridinethione (SPyr), respectively. After 1 week the uptake and distribution of the 203Hg2+ in the fish were examined by gamma spectrometry. SIX, SIP, SMC, SEC and SPyr induced 2-3 times higher 203Hg2+ concentrations in most tissues in comparison with trout exposed to 203Hg2+ only. In the trout exposed to PEX slightly enhanced 203Hg2+ levels were found only in some tissues, and after exposure to SEP a few tissues showed decreased 203Hg2+ concentrations. Determinations of chloroform/water partition coefficients showed that lipophilic chelates are formed between all the examined substances and the 203Hg2+. However, SIX, SIP, SMC, SEC and SPyr, which induced markedly increased tissue levels of the metal, formed 203Hg2+ complexes with higher lipophilicities than SEX and SEP. A facilitated penetration of the lipophilic 203Hg2+ complexes over the gill membranes may underly the increment in the tissue levels of the metal, and the relative lipophilicity of the complexes may be of importance for this effect. In some instances, as with SEP, the 203Hg2+ chelated in complexes with low lipophilicity may even be less able to acumulate in some tissues than the non-complexed metal.
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PMID:Effects of some chelating agents on the uptake and distribution of 203Hg2+ in the brown trout (Salmo trutta): studies on ethyl- and isopropylxanthate, diethyl- and diisopropyldithiophosphate, dimethyl- and diethyldithiocarbamate and pyridinethione. 285 39

Inhibition of red cell water transport by the sulfhydryl reagent 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) has been reported by Naccache and Sha'afi ((1974) J. Cell Physiol. 84, 449-456) but other investigators have not been able to confirm this observation. Brown et al. ((1975) Nature 254, 523-525) have shown that, under appropriate conditions, DTNB binds only to band 3 in the red cell membrane. We have made a detailed investigation of DTNB binding to red cell membranes that had been treated with the sulfhydryl reagent N-ethylmaleimide (NEM), and our results confirm the observation of Brown et al. Since this covalent binding site does not react with either N-ethylmaleimide or the sulfhydryl reagent pCMBS (p-chloromercuribenzenesulfonate), its presence has not previously been reported. This covalent site does not inhibit water transport nor does it affect any transport process we have studied. There is an additional low-affinity (non-covalent) DTNB site that Reithmeier ((1983) Biochim. Biophys. Acta 732, 122-125) has shown to inhibit anion transport. In N-ethylmaleimide-treated red cells, we have found that this binding site inhibits water transport and that the inhibition can be partially reversed by the specific stilbene anion exchange transport inhibitor 4,4'-diisothiocyanostilbene-2,2'-disulfonate (DIDS), thus linking water transport to anion exchange. DTNB binding to this low-affinity site also inhibits ethylene glycol and methyl urea transport with the same KI as that for water inhibition, thus linking these transport systems to that for water and anions. These results support the view that band 3 is a principal constituent of the red cell aqueous channel, through which urea and ethylene glycol also enter the cell.
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PMID:Binding of DTNB to band 3 in the human red cell membrane. 299 87

The phosphoinositides are metabolized by phospholipase C in response to hormone or agonist stimulation in many cell types to produce diglyceride and water-soluble inositol phosphates. We have recently shown that the phospholipase C reaction products include cyclic phosphate esters of inositol. One of these, inositol 1, 2-cyclic 4,5-trisphosphate, is active in promoting Ca2+ mobilization in platelets and in inducing changes in conductance in Limulus photoreceptors similar to those produced by light (Wilson, D. B., Connolly, T. M., Bross, T. E., Majerus, P. W., Sherman, W. R., Tyler, A., Rubin, L. J., and Brown, J. E. (1985) J. Biol. Chem. 260, 13496-13501. In the current study, we have examined the metabolism of the inositol phosphates. We find that both cyclic and non-cyclic inositol trisphosphates are metabolized by inositol 1,4,5-trisphosphate 5-phosphomonoesterase, to inositol 1,2-cyclic bisphosphate and inositol 1,4-bisphosphate, respectively. However, the apparent Km of the enzyme for the cyclic substrate is approximately 10-fold higher than for the non-cyclic substrate. These inositol bisphosphates are more slowly degraded to inositol 1,2-cyclic phosphate and inositol 1-phosphate, respectively. Inositol 1,2-cyclic phosphate is then hydrolyzed to inositol 1-phosphate, which in turn is degraded to inositol and inorganic phosphate by inositol 1-phosphate phosphatase. The human platelet inositol 1,2-cyclic phosphate hydrolase enzyme and a similar rat kidney hydrolase do not utilize the cyclic polyphosphate esters of inositol as substrates. These results suggest that the inositol cyclic phosphates and the non-cyclic inositol phosphates are metabolized separately by phosphatases to cyclic and non-cyclic inositol monophosphates. The cyclic monophosphate is then converted to inositol 1-phosphate by a cyclic hydrolase. We suggest that the enzymes that metabolize the inositol phosphates may serve to regulate cellular responses to these compounds.
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PMID:Isolation and characterization of the inositol cyclic phosphate products of phosphoinositide cleavage by phospholipase C. Metabolism in cell-free extracts. 300 Oct 44

There is considerable disagreement in the literature on changes in the hypothalamo-neurohypophyseal system (HNS) with aging: some reports support HNS degeneration, whereas others claim an activation of this system in senescence. In order to study age-related changes in vasopressin (VP) and oxytocin (OT) excretion in relation to water metabolism, six young (4 months) and 12 aged (34 months) male Brown-Norway rats were placed in metabolism cages. Since plasma testosterone levels have been reported to affect HNS activity and to decline progressively with age, half of the aged animals were given subcutaneous testosterone implants. Urine volume and water intake were significantly increased in aged animals, while urine osmolality was significantly reduced. These changes could not be attributed to diminished VP secretion, since 24-h urinary excretion of this peptide was elevated in the aged animals. In addition, 24-h OT excretion was elevated in the aged animals, indicating an overall activation of the HNS in senescence. VP excretion was significantly correlated with urine osmolality, urine volume and urinary VP concentration. No significant differences were observed between testosterone- and sham-implanted aged rats. It is concluded that the moderate polyuria/polydipsia in the senescent Brown-Norway rat is probably due to renal changes and is accompanied by a compensatory rise in both VP and OT secretion. Testosterone does not affect these changes.
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PMID:Vasopressin and oxytocin excretion in the Brown-Norway rat in relation to aging, water metabolism and testosterone. 321 21

The purine base and nucleoside analogues N2-(p-n-butylphenyl)-guanine (BuPh-Gua) and N2-(p-n-butylphenyl)-2'-deoxyguanosine (BuPh-dGuo) are strong inhibitors of isolated mammalian DNA polymerase alpha, but are less potent that expected as inhibitors of DNA replication in intact cultured cells [G. E. Wright, L. W. Dudycz, Z. Kazimierczuk, N. C. Brown and N. N. Khan, J. med. Chem. 30, 109 (1987)]. The mechanistic basis for these observations was explored using permeable human fibroblasts. DNA replication in the permeable cells was inhibited only slightly by BuPh-Gua and BuPh-dGuo at 100 microM, the highest concentration which could be attained. Similar results were obtained for ultraviolet-induced DNA repair synthesis, a process which is though to involve the same DNA polymerase as replication. More detailed studies were performed using the corresponding nucleotide analogue, N2-(p-n-butylphenyl)-2'-deoxyguanosine-5'-triphosphate (BuPh-dGTP), which is much more water-soluble than the base and nucleoside. The apparent Ki values for BuPh-dGTP inhibition of both replication and ultraviolet-induced repair synthesis in permeable cells were approximately 3 microM. These values are several hundred-fold greater than the apparent Ki for BuPh-dGTP inhibition of isolated human DNA polymerase alpha, which is approximately 10 nM. We conclude that BuPh-Gua and BuPh-dGuo are poor inhibitors of DNA replication in intact cells not because of permeability barriers, but because, unlike polymerase alpha, cellular DNA synthesis is relatively insensitive to this group of inhibitors. These results suggest that polymerase alpha may not be a good general model for predicting the potency of base, deoxyribonucleoside and deoxyribonucleotide analogues as inhibitors of mammalian cellular DNA replication. The fact that the permeable cell systems accurately reflect the relative insensitivity to butylphenyl-guanine derivatives of mammalian DNA replication suggests that permeable cells may be useful tools in future studies of base and nucleoside analogues.
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PMID:Analysis of butylphenyl-guanine, butylphenyl-deoxyguanosine, and butylphenyl-deoxyguanosine triphosphate inhibition of DNA replication and ultraviolet-induced DNA repair synthesis using permeable human fibroblasts. 335 81

To determine the changes in myocardial water during acute cardiac rejection and the effects of Ciclosporin (CYA) on the myocardial water, 90 heterotopic cardiac transplants were performed in rats which were divided into 3 groups, namely those receiving 1) Lewis X Lewis isografts, 2) Lewis X Brown Norway allografts and 3) CYA treated allografts (15 mg/kg/day). The water content was measured in both recipient and donor hearts at 2, 4, 6 and 8 days after transplant. Pathological specimens were examined by light and electron microscopy, and scored on a 0 to 4+ scale of increasing evidence of rejection. The water content of the isografts showed no significant change throughout the post operative period. In contrast, the allografts had significant increase of water content as early as 2 days after transplant, compared to the isografts and recipients hearts. A significant difference in cellular infiltration was noted between isograft and allograft 4 days after transplant. CYA suppressed significantly the increase of myocardial water and cellular infiltration in the allografts. These data suggest that myocardial edema may precede cellular infiltration during the rejection process and it may be suppressed with CYA treatment. The measurement of myocardial water may be useful in early detection of acute cardiac allograft rejection and for examining the therapeutic effects of CYA.
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PMID:Early change of myocardial water during acute cardiac allograft rejection. 354 64

This experiment examined both the short-term and the long-term effects of ovariectomy on brown adipose tissue growth and function in rats to determine if reduced brown adipose tissue thermogenesis might contribute to the weight gain and adiposity. Brown adipose tissue function was assessed by measuring sympathetic nervous system activity (estimated by the rate of norepinephrine turnover) and mitochondrial proton conductance (estimated by specific GDP binding) in interscapular brown adipose tissue. Rats (n = 12 per group) were killed 0 (sham), 1, 2, 4, and 12 weeks after ovariectomy. During the first five weeks after ovariectomy rats overrate and rapidly gained weight. The weight gain was due to increases in all carcass components. Five weeks after ovariectomy food intake returned to control levels, and body weights stabilized 12-16% above sham-operated control weights for the duration of the experiment. Between week 4 and week 12 after surgery there was a redistribution of carcass composition, with decreases in carcass water and fat-free dry weights offset by a further increase in total carcass lipid. Brown adipose tissue pads were heavier in the 1-, 2-, and 4-week ovariectomy groups, but only in the 4-week group was the increase statistically significant. Brown adipose tissue protein, DNA, and norepinephrine content was unchanged 1-, 2-, 4-, or 12-weeks after ovariectomy. There was no difference in either the rate of norepinephrine turnover or specific mitochondrial GDP binding between sham-operated and 1-, 2-, 4-, or 12-week ovariectomized rats.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Short- and long-term effects of ovariectomy on food intake, body weight, carcass composition, and brown adipose tissue in rats. 357 76

Brown trout (Salmo trutta L.) eggs fertilized in clean water were incubated in bleached kraft mill effluent (BKME) concentrations of 0, 0.5, 1, and 2% (v/v) in a continuous-flow system and exposure was continued with the sac fry for most of the yolk sac stage. In addition, sac fry first incubated in clean water were exposed after hatching to the same concentrations for 44 days. Percentage hatching was lower than in the control only in 2% BKME. In all the BKME concentrations, the newly hatched sac fry were shorter than the controls, and their heart rate was slower. All the sac fry in 2% BKME died within 3 weeks after the end of hatching. At the late yolk sac stage the sac fry in the other concentrations of BKME were shorter and less well developed than the controls. Their wet and dry weights were higher and their water content was lower because of retarded yolk absorption. Exposure commencing after hatching also caused retarded growth and development. In the sac fry exposed to BKME only after hatching, mortality increased with the concentration and all the sac fry in 2% BKME died within 4 weeks.
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PMID:Effects of bleached kraft mill effluent on early life stages of brown trout (Salmo trutta L.). 369 67

In a preliminary study, groups of ten female rats received daily doses of either water or solutions of Brown HT providing 250, 500 or 1000 mg Brown HT/kg body weight for 19 consecutive days. While there was no indication of overt toxicity, treated animals at all doses had brown discoloration of lymph nodes, caecum and colon. In the subsequent main study, groups of 30 female rats were given daily oral doses of 0 (water vehicle), 250, 500 or 1000 mg Brown HT/kg from day 0 to day 19 of pregnancy. There were no adverse effects on the numbers of implantations, pre- and post-implantation losses, litter weights, foetal numbers, foetal weights or sex ratio. No abnormalities related to treatment were found in either the skeleton or soft parts of the offspring. It is concluded that doses of up to 1000 mg Brown HT/kg/day given throughout pregnancy failed to exert detectable embryotoxicity or teratogenicity in rats.
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PMID:Teratogenicity and embryotoxicity study of Brown HT in the rat. 369 92

Brown HT was fed to rats of both sexes over three generations at dietary concentrations designed to provide daily intakes of 0, 50, 250 and 500 mg Brown HT/kg body weight/day. During the study a number of females died or failed to nurse their litters. This was so severe following the first mating of F1 adults that the animals were remated to provide the next generation. None of these effects were related to treatment. Body weight and food and water intakes were not adversely affected by treatment. No effects of treatment were seen on reproductive performance or foetal and pup development, apart from slight evidence of a treatment-related retarded ossification of the third sternebrae. Organ weights at autopsy showed two changes, one of which was increased kidney weights which, although not present in every generation, seemed to be related to treatment. The other, increased caecum weights, occurred in adult high-dose females of early generations, but not in males or later generations of the study. Apart from brown coloration of tissues, macroscopic and microscopic examination revealed no treatment-related changes. It was concluded that the no-untoward-effect level in the present study was 250 mg Brown HT/kg/day.
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PMID:Three-generation toxicity study of rats ingesting Brown HT in the diet. 369 9


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