PubMed Health⌕ Search

Biomedical subjects

J S Garvey

Publications and source records attributed to J S Garvey.

15 recordsLinked to original sources
PubMed1992

Differential effect of adrenalectomy on rat liver metallothionein mRNA levels in basal and stress conditions.

Liver metallothionein (MT) mRNA and serum MT levels of adrenalectomized (ADX) and sham-ADX rats in basal and stress (1, 3 or 6 h of restraint) conditions have been measured. Serum MT levels were overall lower in ADX than in sham-ADX rats. Basal liver MT mRNA levels were increased in ADX rats, suggesting that glucocorticoids have an inhibitory role on the regulation of liver MT synthesis. In contrast, liver MT mRNA levels were increased by stress in sham-ADX but not in ADX rats, suggesting a stimulatory role for glucocorticoids. These results suggest that glucocorticoids have a different role in liver MT regulation depending on the physiological situation.

Adrenalectomy↗
PubMed1991

Glial immunoreactivity for metallothionein in the rat brain.

A series of frozen and vibratome coronal sections of the rat brain were examined by immunocytochemistry for the presence of a cysteine-rich metal binding protein, metallothionein (MT). Astrocytes throughout the brain and brainstem stained positively for MT; neurons and oligodendroglia were unstained. Ependymal cells and tanycyte processes in the hypothalamus were also immunoreactive, along with a narrow zone of immunopositivity along the margins of the area postrema. Gomori-positive astrocytes in the hypothalamus, identifiable by toluidine blue staining, metal-containing cytoplasmic granules, represented a subset of MT-positive astrocytes that may be involved in reactions to blood-borne metal compounds that penetrate into circumventricular organs of the brain.

Animals↗
PubMed1991

Role of extracellular zinc and copper on metallothionein regulation in cultured rat hepatocytes.

Cellular and extracellular metallothionein contents of rat hepatocytes cultured in the presence of albumin (30 mumol/L) with zinc (1, 10, 50 and 100 mumol/L), copper (1, 10 and 50 mumol/L), zinc and copper (1, 10 and 50 mumol/L of each metal) or no metals in the culture medium have been measured by radioimmunoassay. Cellular metallothionein levels increased steadily with culture time regardless of the metal treatment and showed little dependence (only a twofold increase) on extracellular zinc or copper at all metal concentrations and times (up to 3 days) studied. In contrast, the presence of both metals simultaneously in the culture medium strongly increased cellular metallothionein contents, acting synergistically in some cases. Significant extracellular metallothionein was observed when copper or zinc and copper were present in the culture medium, most of which is likely a consequence of cell leakage because no evidence of physiological secretion was observed. Total metallothionein production (cellular and extracellular metallothionein levels) indicated that copper was a better metallothionein inducer than zinc in these experimental conditions. These results indicate that metallothionein regulation in the hepatocyte is different depending on the extracellular metal levels and composition and that attention must be given to metallothionein release from the hepatocyte.

Analysis of Variance↗
PubMed1991

Metallothionein in rat lung during postnatal development.

Zn and Cu concentration, content, and distribution in lung were quantitated in neonatal and adult Lewis rats. Total lung Cu and Zn content rose dramatically during postnatal development, paralleling increases in lung and body weight. Cu concentration was 2-fold higher in adult lung than in neonatal lung whereas Zn concentration was unaffected by developmental age. A Cu-containing protein with an approximate molecular weight of 10,000 Da was identified immunologically as metallothionein (MT). At term, native MT concentration in the lung was 4-fold higher than in adult lungs. By day 4 postpartum, MT concentration was reduced by half and reached a level characteristic of the adult by 7 days postpartum. MT was localized in nuclear and cytoplasmic compartments of positive lung cells by immunofluorescent techniques; initially, nuclear MT staining was more intense than cytoplasmic staining.

Animals↗
PubMed1991

Effect of morphine administration on rat liver metallothionein and zinc metabolism.

The putative involvement of opioid receptors in rat liver metallothionein (MT) regulation has been studied by means of morphine administration. Rat liver MT levels were significantly increased by morphine (10 mg kg-1). This increase was blocked by the opiate antagonist naloxone (4 mg kg-1), suggesting that the effect of morphine on liver MT could involve opioid receptors. The effect of morphine appears to be mediated, at least in part, by glucocorticoids and catecholamines, inasmuch as the administration of specific receptor blockers, RU 486 (100 mg kg-1) for glucocorticoids and labetalol (5 mg kg-1) for catecholamines, diminished liver MT increase induced by morphine. These results identify a potential mediation mechanism for regulating liver MT levels. The putative role of endogenous opioids on liver MT response to stress was also studied by means of opioid receptor blockers. The effect of stress on liver MT levels was not altered by blockade of opioid receptors with either naloxone (4 mg kg-1) or naltrexone (4 mg kg-1) or diprenorphine (4 and 20 mg kg-1), suggesting that endogenous opioids are not involved in MT response to stress. Zn metabolism was also altered by morphine, as morphine administration increased liver cytosolic Zn and decreased serum Zn levels. In contrast to those found in liver MT, these changes were not naloxone-sensitive. The results obtained with RU 486 and labetalol suggest that the effect of morphine on Zn metabolism was mediated in part by glucocorticoids and catecholamines.

Animals↗
PubMed1990

On the metallothionein, glutathione and cysteine relationship in rat liver.

Stress and starvation increased liver metallothionein (MT) and decreased liver glutathione (GSH) levels. Serum cysteine plus cystine levels were increased by stress. The exogenous administration of GSH, while not modifying hepatic GSH content, increased liver MT levels in basal and starved rats but not in stressed rats. Liver and serum cysteine levels were increased by GSH administration, a process partially reverted by the irreversible inhibitor of gamma-glutamyl transpeptidase, alpha-amino-3-chloro-4,5-dihydro-5-isoxazoleacetic acid. Mouse and rat liver MT levels were also increased by buthionine sulfoximine, an inhibitor of GSH synthesis, indicating that GSH is not a necessary precursor of MT. In addition, the hepatic MT content was increased by the administration of cysteine in a dose-response manner. These results suggest that hepatic MT synthesis is elevated by increased cysteine pools, and that MT, GSH and cysteine levels are somehow inter-related. MT, besides GSH, may be contemplated as a putative intracellular reservoir of cysteine in the liver of adult rats.

Animals↗
PubMed1979

Isolation and characterization of hepatocytes and Kupffer cells.

Simplified isolation procedures are described for the parenchymal cell of the liver and the major non-parenchymal cell, the Kupffer cell. Hepatocytes are obtained in a purity of approximately 100%; a yield 10 X 10(6) cells/g liver tissue and the viability is greater than 85%. The recovery of Kupffer cells is 82%, viability 87% and purity 67%. Characterization of Kupffer cells is by the peroxidatic reaction, of hepatocytes by gluconeogenesis and also culture on collagen plates in a non-protein medium yielding albumin.

Animals↗
PubMed1977

Improved methods for separation and purification by affinity chromatography.

Defined conditions for simplified Affinity Chromatography suitable for instructional and research purposes, were developed. The standard method of activation of polysaccharide gels using BrCN was modified and improved using a highly buffered reaction solution. A batchwise protocol for the immunoadsorbent isolation of anti-BSA was used (with commonly employed dissociation agents) and comparative data were obtained.

Acetonitriles↗