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Biomedical subjects

H Kawauchi

Publications and source records attributed to H Kawauchi.

At least 127 records · Page 7Linked to original sources
PubMed1991

The effect of rearing rainbow trout on black or white backgrounds on their secretion of melanin-concentrating hormone and their sensitivity to stress.

Rainbow trout were reared in black or off-white coloured tanks for up to 18 months of age to achieve maximum differences in the synthesis of the neuropeptide, melanin-concentrating hormone (MCH). White-reared fish had greatly increased MCH concentrations in their pituitary glands, in their MCH perikarya and in the presumptive neuromodulatory fibres of the dorsal hypothalamus/thalamus when compared with black-reared and commercially reared trout. Following transfer to brighter white tanks, white-reared fish showed a significant increase in plasma MCH concentration and a reduction of MCH in the pituitary and MCH perikarya. The additional challenge of repeated stress further increased plasma MCH concentration in these fish and also reduced MCH in the dorsal hypothalamus/thalamus. In black-reared fish transferred to white tanks, plasma MCH concentrations were significantly raised after transfer, although they were lower after 11 days than in white-reared counterparts. Transfer from black to white background caused a fall in the MCH concentration in all regions--pituitary gland, perikarya and dorsal hypothalamus/thalamus; if transfer was accompanied by repeated stress, the hormone in the pituitary gland and MCH perikarya became so depleted that plasma MCH concentrations declined. Within each experimental situation (control, background transfer and transfer with stress) there was in inverse correlation between plasma MCH concentrations of black- and white-reared fish and the cortisol concentration. MCH had no direct effect on the secretion of cortisol by interrenal tissue but incubated hypothalami, in which endogenous MCH had been immunoabsorbed, provided evidence that MCH can depress the release of corticotrophin-releasing bioactivity.

Animals↗
PubMed1991

Comparison of lipolytic and antilipolytic activities of lower vertebrate growth hormones on chicken adipose tissue in vitro.

Mammalian and avian growth hormones (GH) (pituitary derived or biosynthetic) exert two effects on chicken adipose tissue explants in vitro. They (i) increase the basal rate of glycerol release a lipolytic effect) and (ii) inhibit glucagon-stimulated glycerol release (an antilipolytic effect). The ability of lower vertebrate GH preparations to exert lipolytic and antilipolytic effects was examined and biological activity was compared to differences in amino-acid residue sequences and to predicted structure. Irrespective of species origin (blue shark, sturgeon, bonito, yellow tail, salmon, bullfrog, sea turtle), all lower vertebrate GH preparations showed very weak (less than 5% the potency of bovine GH), if any, lipolytic activity, but retained strong antilipolytic activity. The present data indicate that the structural requirements for lipolytic and antilipolytic activities of GH differ in chicken adipose tissue. Despite the high sequence homology (88%) between chicken and sea turtle GH, the latter preparation did not stimulate lipolysis. It is suggested that Pro132, conserved only in lipolytically active GH species (human, bovine, and chicken), represents a major determinant of lipolytic activity in chicken adipose tissue. The structural determinants for antilipolytic activity may comprise any or all of residues 3, 17, 64, 108, 109, and 152.

Adipose Tissue↗
PubMed1991

Effect of sodium chloride on pirarubicin induced cell killing in P388 mouse leukemia cells.

The effect of sodium chloride on the cytotoxicity of 4'-O-tetrahydropyranyldoxorubicin (pirarubicin), a novel anthracycline derivative, was investigated on P388 mouse leukemia cells in vitro. The modifications in efficiency of uptake and killing action of pirarubicin were found to be dependent on the ionic strength of the medium. The relationship between intracellular drug accumulation into cells and cell killing was pointed out.

Animals↗
PubMed1991

Potentiation of pirarubicin cytotoxicity by dipyridamole in doxorubicin-resistant mouse P388 leukemia cells.

The activity of dipyridamole and its possible mechanisms which reverse the resistance of pirarubicin were studied in a P388 mouse leukemia cell lines. Dipyridamole alone was minimally cytotoxic in both of the doxorubicin-resistant cell line (P388/DOX) and the sensitive parent cell line (P388/S), but reversed pirarubicin-resistance in a dose-related manner in P388/DOX cells. A similar dose-response relationship was observed for dipyridamole by increasing net intracellular pirarubicin accumulation. The increase was a result of secondary blocking of enhanced pirarubicin efflux from P388/DOX cells. In contrast, dipyridamole did not affect cytotoxicity and transport in the drug-sensitive cell line. It is suggested that dipyridamole is a useful drug for modulation of the multidrug-resistance of cells.

Animals↗
PubMed1991

Effect of chlorpromazine on the toxicity of doxorubicin in mice.

The effect of chlorpromazine (CPZ) on the toxicity of doxorubicin (DOX) were investigated in mice. CPZ significantly enhanced the acute toxicity and bone marrow toxicity induced by DOX. These results suggest the potentiation of DOX toxicity by CPZ is due to increase of sensitivity of mice to DOX.

Animals↗
PubMed1990

Analysis of immunocompetent cells in the middle ear mucosa.

A quantitative analysis of immunocompetent cells in the middle ear mucosa of mice was carried out by an indirect immunostaining method using various monoclonal antibodies. Mice bred in germ-free, specific pathogen-free, and conventional conditions were used to examine nonimmunized middle ear mucosa. Middle ear mucosae of otitis media-induced mice were also examined. In normal middle ear mucosa, mast cells were substantial, followed by Mac-1-positive cells and lymphocytes. Even though IgA-, IgM-, and Lyt-1-positive cells were seen in the mucosa of conventional mice, IgM-positive cells were seen only in mucosae of specific pathogen-free and germ-free mice. In otitis media-induced mice by inoculation with nontypable Haemophilus influenzae or lipopolysaccharide, Mac-1-positive cells were dominant. Although the numbers of IgM- and Lyt-1-positive cells increased markedly, the numbers of other lymphocyte subsets did not increase until 14 days after inoculation. These findings suggest that the middle ear is immunologically a potential organ as long as it is not exposed to antigenic stimulation. It is considered to be an immunoreactive site only after it has been activated with pathogens.

Animals↗
PubMed1990

The complete amino acid sequences of alpha subunits of chum salmon gonadotropins.

The complete amino acid sequences of alpha subunits of chum salmon (Oncorhynchus keta) gonadotropins (GTHs), GTH I and GTH II, were determined. Subunits were separated by reversed-phase high-performance liquid chromatography. Two alpha subunits, I alpha 1 and I alpha 2, were obtained from GTH I, whereas only one alpha subunit was obtained from GTH II. Sequence analysis revealed that GTH I alpha 2 is identical to GTH II alpha, but distinct from GTH I alpha 1. The I alpha 1 and II alpha consist of 95 and 92 amino acid residues, respectively. GTH I alpha 1 has 72% sequence identity with GTH I alpha 2. The two alpha subunits show approximately 65% sequence identity with bovine alpha subunit. This is the first finding of two chemically distinct alpha subunits from one species.

Amino Acid Sequence↗
PubMed1990

Plasma growth hormone levels increase during seawater exposure of sexually mature Atlantic salmon parr (Salmo salar L.).

At the time of smoltification in May, smolts and sexually mature male parr were transferred to seawater (25% salinity) and sampled after 6 and 24 hr. Plasma levels of growth hormone (GH) were measured by radioimmunoassay. There was no difference in GH levels between smolts and mature parr in fresh water. GH levels did not change during exposure of smolts to seawater. In the mature male parr, plasma GH levels increased after 24 hr, when the levels were almost five times those of the freshwater controls. In the mature male parr, there was an increase in plasma osmolality, sodium, and magnesium after 24 hr in seawater; magnesium also increased after 6 hr. The levels of potassium and calcium did not change in either immature parr or mature male parr. The increase in plasma GH levels in the mature parr in seawater may be part of a mechanism to increase hypoosmoregulatory ability in fish not ready for seawater entry.

Animals↗
PubMed1990

The complete amino acid sequence of prolactin from the sea turtle (Chelonia mydas).

The complete amino acid sequence of prolactin (PRL) from a reptile, the sea turtle (Chelonia mydas), was determined for the first time. Sequence analysis was performed on fragments obtained from cleavage of intact and performic acid-oxidized hormone with lysyl endopeptidase, Staphylococcus aureus protease, and o-iodosobenzoic acid employing manual Edman degradation. The sea turtle PRL consists of 198 amino acid residues with three disulfide linkages formed between residues 4-11, 58-173, and 190-198 and possesses heterogeneity indicated by four replacements at positions 55, 145, 148, and 171. Sequence comparison with other vertebrate PRLs revealed that the degree of sequence identity conforms well to expectations based on phylogeny except for the rodent PRLs; sea turtle PRL has 86% identity with chicken PRL; 81% with horse, pig, and fin whale PRLs; 75-71% with cattle, sheep, and human PRLs; 60-56% with mouse and rat PRLs; and 35-31% with carp, salmon, and tilapia PRLs.

Amino Acid Sequence↗
PubMed1990

Development and validation of a competitive enzyme immunoassay for chum salmon prolactin: a comparison to radioimmunoassay.

An enzyme immunoassay (EIA), based on a competitive assay system, for the measurement of prolactin (PRL) in the pituitary of salmonid fishes and of hormone released in medium from incubated pituitary was developed using a rabbit antiserum to chum salmon PRL (PRL, a combination of PRL I and PRL II). Chum salmon PRL was coupled to horseradish peroxidase (HRP). The incubation procedure for the antigen-antibody reaction was analogous to that in the radioimmunoassay (RIA) for PRL. The antibody-bound HRP-PRL was separated by a double antibody method. The enzyme activity in the precipitate was followed by a colorimetric method, in which 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) and o-phenylenediamine were used as substrates. PRL, PRL I, and PRL II showed exactly the same competitive curves in the EIA system. PRL (127-158) showed the highest cross-reactivity among the fragments of PRL examined. Low cross-reactivity was seen with other hormones isolated from chum salmon pituitary. The displacement curves for pituitary extracts from several salmonids, including chum salmon, coho salmon, and rainbow trout, were parallel to that of the PRL standard, whereas those from the carp and tilapia showed negligible cross-reactivity. A parallel displacement curve to the PRL standard was also seen with incubation medium of the pars distalis of the chum salmon pituitary. Plasma from chum salmon, coho salmon, and rainbow trout gave nonspecific HRP activity in the EIA. The values of PRL-EIA were significantly correlated (y = 0.99x + 1.06, r = 0.942, P less than 0.05, n = 24) with those obtained in PRL-RIA.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Plasma profiles of the N-terminal peptide of proopiomelanocortin in the rainbow trout with reference to stress.

Plasma levels of the N-terminal peptide of proopiomelanocortin (NPP) were measured in rainbow trout, Salmo gairdneri, following treatment of handling stress with or without administration of dexamethasone, adaptation to white and black background, and maintenance on a constant light/dark cycle. Effects of exogenously administered NPP on plasma constituents were also examined to provide insight into the biological significance of NPP. Thirty minutes of handling stress in shallow water had no effect on plasma levels of NPP during and after the stress period, whereas significant increases in plasma cortisol and glucose were observed. Intraperitoneal administration of dexamethasone blocked the stress-induced elevation of plasma levels of cortisol and caused a depression of plasma NPP. No difference was observed in plasma levels of NPP between trout adapted to a white background and those adapted to a black background. No diurnal changes in NPP were observed under an artificial light/dark cycle (14L/10D light cycle, 0500-1900 hr light) in May and September. Thus, plasma levels of NPP were considerably constant under various physiological conditions, and no synchronism was observed between plasma NPP and cortisol, although NPP modifies the corticotropin-induced release of cortisol from the interrenal. Plasma constituents such as cortisol, total protein, albumin, plasma amino nitrogen, glucose, free fatty acid, ketone body, sodium, potassium, calcium, and magnesium were not altered by intraperitoneal injections of NPP (1 or 10 micrograms) once daily for 6 days (total of six injections) or once every other day for 28 days (14 injections). High concentrations of NPP were found in the plasma 24 hr after cessation of the serial injections of NPP (10 micrograms), suggesting slow metabolic clearance of the peptide.

Animals↗
PubMed1990

Salmonid pituitary gonadotrophs. I. Distinct cellular distributions of two gonadotropins, GTH I and GTH II.

Using antisera specific for the beta subunits of two distinct coho salmon gonadotropins, GTH I and GTH II, an immunocytochemical study of rainbow trout and Atlantic salmon pituitaries was done. Cells which immunostained with anti-GTH I beta were distributed in the periphery of the glandular cords of the proximal pars distalis (PPD), in close association with somatotrophs. On the other hand, cells immunostained with anti-GTH II beta were located in the central parts of the glandular cords of the PPD. Neither the GTH I-producing nor the GTH II-producing cells stained with antisera against chum salmon growth hormone or the beta subunit of human thyroid-stimulating hormone. Moreover, GTH I and GTH II were localized in distinctly different cells. In no case was colocalization of these GTHs in the same cell observed. Finally, it was concluded that classification of GTH cells as globular and vesicular forms does not reflect the type of hormone produced by the cell, but may reflect differences in the physiological conditions of the cells.

Animals↗
PubMed1990

Salmonid pituitary gonadotrophs. II. Ontogeny of GTH I and GTH II cells in the rainbow trout (Salmo gairdneri irideus).

Immunocytochemistry of rainbow trout pituitary gonadotrophs (GTH I- and GTH II-producing cells) during gametogenesis was investigated. GTH I and GTH II were found in distinctly different cells in all stages of reproductive development that were examined. Only GTH I cells were present in trout prior to puberty. GTH II appeared in addition to GTH I coincident with the onset of vitellogenesis and spermatogenesis. Both GTH I and GTH II cells were found in trout at the time of final reproductive maturation, although the number of GTH II cells was greater than that of GTH I cells. These data indicate that GTH I and GTH II are localized in separate cells in the trout pituitary throughout gametogenesis, and that synthesis of GTH I and GTH II varies during reproductive development.

Animals↗
PubMed1990

cDNA cloning of somatolactin, a pituitary protein related to growth hormone and prolactin.

From a flounder pituitary cDNA library, cDNA clones encoding a 28-kDa glycoprotein produced by the pars intermedia of the pituitary were isolated and characterized. Nucleotide sequencing demonstrated a precursor of the 28-kDa protein, which consisted of 231 amino acid residues, to be cleaved into a signal peptide (24 amino acids) and a mature protein (207 amino acids) containing one N-glycosylation site. By comparison of amino acid sequences, the 28-kDa protein was found to be distantly and similarly related to growth hormone and prolactin. Consequently, it was named somatolactin. Somatolactin mRNAs were specifically expressed as 1.2 and 1.8 kb poly(A)+ RNAs in flounder pituitary.

Amino Acid Sequence↗
PubMed1990

Amino acid sequence of a lectin from Japanese frog (Rana japonica) eggs.

The complete amino acid sequence and the location of disulfide bonds of a lectin from Japanese frog (Rana japonica) eggs, which specifically agglutinates transformed cells, are presented. The sequence was determined by analysis of peptides generated by digestion of the S-carboxyamidomethylated protein with Achromobacter protease I, or chymotrypsin, and by chemical cleavage with BNPS-skatole or cyanogen bromide. The lectin is a single-chain protein consisting of 111 residues, with a pyroglutamyl residue at the amino terminus. Four disulfide bonds link half-cystinyl residue 19 to 72, 34 to 82, 52 to 97, and 94 to 111. The sequence and the location of the disulfide bonds are highly homologous to those of bull frog (Rana catesbeiana) egg S-lectin. They are also homologous to human angiogenin, a tumor angiogenesis factor, and a family of pancreatic ribonucleases.

Amino Acid Sequence↗
PubMed1990

Role of middle ear endotoxin in inner ear inflammatory response and hydrops: long-term study.

The permeability of the round window membrane for Salmonella typhimurium-derived endotoxin was examined with use of a total of 33 chinchillas. One milligram of each endotoxin was instilled into the tympanic cavities via the superior bullae. The endotoxin activities in middle ear effusions (MEEs), perilymph, and sera were determined by limulus amebocyte lysate assay. Endotoxin was detected in perilymph on the inoculated side by 12 hours after endotoxin instillation and persisted for up to 3 weeks. Endotoxin level peaked at 24 to 48 hours postinstillation, and it steadily declined afterward. This result suggests that the maximum penetration occurred during the active inflammatory stage. Histologic evidence demonstrated remarkable pathologic changes in the inner ear, including bleeding and inflammatory cell recruitment, mostly in the perilymphatic spaces (eg, scalae tympani, scalae vestibuli, spiral ligament), strial swelling, and sensory cell degeneration. This result suggests that endotoxin present in the middle ear can permeate the round window membrane, causing inner ear tissue damage in this animal model.

Animals↗