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Biomedical subjects

S Muto

Publications and source records attributed to S Muto.

At least 145 records · Page 8Linked to original sources
PubMed1989

Behavioral endocrinology of male rats with periodic sexual contacts with exclusive or varied females.

Sexual contact keys a profound series of acute and chronic changes in males that, presumably, are orchestrated by acute pulsatile release of hormones. An experimental paradigm is reported in which male rats were paired periodically with either the same or different estrous females to receive identical amounts of copulatory experiences. Results confirmed the hypothesis that exposure to an unfamiliar female would induce a different endocrine response which would be reflected in various androgen-sensitive systems. The "successively polygynous" males showed more sexual behavior than "monogamous" males, and their respective females solicited the males differently, as well. Circulating levels of testosterone were higher immediately after sexual contact with an unfamiliar than with a familiar female partner. There were no differences in testosterone titers among the groups when the animals were killed at either 2 or 7 weeks after the final copulatory experiences. Yet, necropsies at 2 weeks postcopulation revealed that primary and secondary sex structures from polygynous males clearly were larger. Differences between the two experimental groups were reduced after 7 weeks of sexual rest, yet, polygnous males continued to show a different structural profile than the other groups. Conclusions were that males may experience greater activation of androgen-sensitive behavior and physiology following qualitatively different sexual contacts.

Adrenal Glands↗
PubMed1989

[Regulation of osteoclastic bone resorption. 1. Limitation of osteoclast motile activity by fibroblast-like cells].

The cell-to-cell interaction between osteoclasts and fibroblast-like cells, which were mechanically disaggregated from long bones of neonatal rabbits, was investigated to clarify the cellular mechanisms responsible for the regulation of osteoclastic bone resorption by using phase-contrast time lapse recording and fluorescent microscopy for visualization of F-actin cytoskeleton. Osteoclasts showed rapid extension and retraction of pseudopodia with intense ruffling activity and active translocation over a glass surface when there was enough open space around them, while fibroblast-like cells seemed much more stationary. Osteoclasts were not able to cross over cell bodies of fibroblast-like cells which interfered with migration of the osteoclasts. As fibroblast-like cells proliferated, they gradually took over the open glass surface and finally tightly surrounded the osteoclasts. Such osteoclasts usually became contracted and pseudopodial and migratory activities decreased. Fluorescent microscopy of well-spread osteoclaststs stained with rhodamine-labeled phalloidin revealed development of a band-like structure composed of a number of brightly fluorescent F-actin dots at the cell periphery and fine F-actin bundles which run through the cell bodies. On the other hand, contracted osteoclasts tightly surrounded by fibroblast-like cells showed conglomerates composed of accumulated F-actin dots instead of the band-like structure. An F-actin pattern of fibroblast-like cells, which was very different from that of osteoclasts, displayed thick and straight bright bundles with in the cell bodies. The present observation suggests that ongoing osteoclastic bone resorption may be regulated by fibroblast-like cells through limitation of osteoclastic motile activity, and alteration of cytoskeleton and cell-substratum interaction which occurred in osteoclasts may be involved in the mechanism.

Actins↗
PubMed1988

Synergistic effect of lymphokines and lipopolysaccharides on macrophage chemiluminescence. Appearance of spontaneous chemiluminescence and its correlation with cytotoxicity.

A new type of chemiluminescence (CL) was observed in thioglycolate-elicited ICR mouse peritoneal macrophages which had been incubated for 24 h in medium containing lymphokines (LK) and lipopolysaccharides (LPS), and then exposed to a CL reagent solution containing luminol and phorbol myristate acetate (PMA). The new CL, which was clearly distinguishable from PMA-induced CL, appeared immediately after the addition of the CL reagent solution, reaching a maximal level at about 30 s, and disappeared rapidly. We have called the new CL 'spontaneous CL', since it appeared spontaneously without PMA triggering. When the macrophages were incubated with LK in the presence of 10 ng/ml of LPS, the spontaneous CL began to appear after about 4 h incubation, the maximal level being reached at about 12 h, after which it decreased gradually on further incubation. After 48 h, it could not be observed at all. The spontaneous CL could be observed only in macrophages simultaneously treated with LK and LPS, as in the case of cytotoxicity. The correlation between spontaneous CL and cytotoxicity was suggested by the following; they showed a similar dose dependency to LK, and neither of them could be induced in aged macrophages which had been incubated in vitro for 1 day before exposure to LK and LPS. These results suggest that spontaneous CL measurement could possibly replace the cytotoxicity test as a simple method for the determination of macrophage activating factor.

Animals↗
PubMed1988

Structural changes in nuclear chromatin in rat pituitary after chronic stress of low intensity.

Acute, intense sources of "psychogenic" stress clearly modify the structure and function of the hypophysis, and there are concomitant changes in many peripheral physiological systems. Less dramatic sources of stress yield more equivocal results. An experiment is reported in which nuclear morphology of adenohypophyseal cells from 49 male rats exposed to a chronic, low-intensity stressor was examined both by conventional histological and computer-assisted-image-processing methods. The hypothesis tested was that an unequivocal pattern of morphological changes in the nucleus and nuclear chromatin would be revealed by image processing. Rats were killed after living for a year in a relatively low-stress environment, "crowded" in groups of five animals per cage. The control condition was a minimal stress environment of two rats per cage. Results suggested few signs of pathology from peripheral measures of hypophyseal activity, and direct light microscopic examination of the gland revealed no differences between the two groups. Analysis of computer-enhanced images of the pars distalis nuclei from the adenohypophysis, on the other hand, generated findings that were statistically and biologically significant. Nuclear size increased in the stress condition, the number of chromatin and area occupied by the particles increased, and the position of chromatin shifted toward the periphery of the nucleus. Perhaps more important, optical density analysis indicated that chromatin was less tightly packed in the experimental animals. Implications are that chronic, low-intensity stress modulates nuclear structural changes from a dormant to an active state that portend changes in the peripheral systems influenced by the hypophysis.

Adrenal Glands↗
PubMed1988

Effect of PSK, a protein-bound polysaccharide from Coriolus versicolor, on drug-metabolizing enzymes in sarcoma-180 bearing and normal mice.

The effects of PSK and Propionibacterium acnes (anaerobic Corynebacterium) on hepatic drug-metabolizing enzymes were studied using sarcoma-180 bearing and non-tumor bearing mice. PSK had no influence on aminopyrine N-demethylase and aniline hydroxylase activities, cytochrome P-450 concentration in hepatic microsomes, and the reductase activity of cytochrome c in normal mice. The content of cytochrome P-450 was not significantly reduced in S-180 bearing mice. On the other hand, P. acnes administration significantly decreased the amount of cytochromes P-450 and b5 and aminopyrine N-demethylase activity. When FT-207 (Tegafur) was administered orally to S-180 bearing mice combined with the immunoadjuvants, only P. acnes significantly reduced the 5-FU levels in the serum and some organs.

Adjuvants, Immunologic↗
PubMed1988

Photosynthetic characteristics of an amphibious plant, Eleocharis vivipara: Expression of C(4) and C(3) modes in contrasting environments.

Eleocharis vivipara Link, a freshwater amphibious leafless plant belonging to the Cyperaceae can grow in both terrestrial and submersed aquatic conditions. Two forms of E. vivipara obtained from these contrasting environments were examined for the characteristics associated with C(4) and C(3) photosynthesis. In the terrestrial form (delta (13)C values = -13.5 to -15.4 per thousand, where per thousand is parts per thousand), the culms, which are photosynthetic organs, possess a Kranz-type anatomy typical of C(4) plants, and well-developed bundle-sheath cells contain numerous large chloroplasts. In the submersed form (delta (13)C value = -25.9 per thousand), the culms possess anatomical features characteristic of submersed aquatic plants, and the reduced bundle-sheath cells contain only a few small chloroplasts. (14)C pulse-(12)C chase experiments showed that the terrestrial form and the submersed form fix carbon by way of the C(4) pathway, with aspartate (40%) and malate (35%) as the main primary products, and by way of the C(3) pathway, with 3-phosphoglyceric acid (53%) and sugar phosphates (14%) as the main primary products, respectively. The terrestrial form showed photosynthetic enzyme activities typical of the NAD-malic enzyme-C(4) subtype, whereas the submersed form showed decreased activities of key C(4) enzymes and an increased ribulose 1,5-bisphosphate carboxylase (EC 4.1.1.39) activity. These data suggest that this species can differentiate into the C(4) mode under terrestrial conditions and into the C(3) mode under submersed conditions.

Journal Article↗
PubMed1988

An acute increase of peritubular K stimulates K transport through cell pathways of CCT.

In this study, we have investigated net transport and electrical properties of isolated perfused cortical collecting ducts of control and DOCA-treated rabbits to clarify the cell mechanism for secreting K on an acute increase of peritubular K concentration. Raising bath K in control experiments caused an increase in net K secretion (-JK) and net Na absorption (JNa). Barium (5 mM), a known blocker of basolateral K conductance, added to the bath had no effect on this transport stimulation. In the presence of luminal Ba (5 mM) -JK was reduced to zero, but JNa was unaltered. When bath K was increased -JK increased to a value slightly greater than zero, but not different from the predicted passive flux through the paracellular pathway. In tubules of DOCA-treated rabbits, raising K in the bath increased -JK and JNa. The observed stimulation of -JK was blunted in the presence of Ba in the bath, whereas the increase in JNa remained the same. Thus, in DOCA-treated tubules, Ba in the bath significantly attenuated the increase in K secretion without affecting the transport stimulation of JNa. When Ba was added to the perfusate and bath K increased, -JK, which was initially 22.1, increased to 36.4 pmol.mm-1.min-1. Thus a "Ba-insensitive" pathway became more evident in CCTs from DOCA-treated rabbits.(ABSTRACT TRUNCATED AT 250 WORDS)

Algorithms↗
PubMed1988

Hypochlorhydria and hypergastrinemia and their association with gastrointestinal bleeding in young patients with chronic renal failure.

In 40 young patients with chronic renal failure (CRF) on maintenance hemodialysis and 22 control subjects, (1) basal and test meal-stimulated gastrin concentrations, (2) basal and pentagastrin-stimulated gastric acid outputs, and (3) endoscopic examinations were studied. Age-matched CRF patients with control subjects had higher circulating gastrin levels both in the fasting and the test meal-stimulated state and they also had hypochlorhydria. After a test meal, the peak increment of serum gastrin in the CRF patients was more prolonged and greater than in controls. Endoscopic findings showed that the most predominant lesion in the CRF patients was hemorrhagic gastritis. Nine (64.2%) out of 14 patients were hyposecretors and none were hypersecretors. Patients with hyposecretion had higher gastrin levels as well as the same incidence of abnormal endoscopic findings as patients with normosecretion. It is concluded that hypergastrinemia in young CRF patients might be due to a combined effect of impaired renal clearance capacity and overproduction of gastrin associated with hypochlorhydria and also that the cause of gastritis in the young CRF patients might partly be due to a relative impairment of the mucosal defensive mechanism to acid. Our data suggest that the parietal cell response to gastrin in CRF patient may be impaired.

Adult↗
PubMed1988

Hypochlorhydria and hypergastrinemia and their association with gastrointestinal bleeding in undialyzed and hemodialyzed patients.

In 15 undialyzed (UD) patients and 26 hemodialyzed (HD) patients, (1) basal and test meal-stimulated gastrin concentrations, (2) basal and pentagastrin-stimulated gastric acid outputs, and (3) endoscopic examinations were studied. Also studied were the morphological and functional differences of the gastrointestinal tract between UD and HD patients. HD patients had lower gastric acid outputs and higher circulating gastrin levels in the fasting state. After a test meal, the peak increment of serum gastrin in UD and HD patients occurred 30 and 60 min later, respectively, and the response was prolonged in each group. Endoscopic findings showed that the incidence of abnormalities in each group was very similar, that is, the most predominant lesions in each group were hemorrhagic and atrophic gastritis. The data suggested that the response to gastrin of parietal cell and the defensive mechanism of gastrointestinal mucosa in HD patients may be impaired.

Adult↗
PubMed1988

Effects of a high potassium diet on electrical properties of cortical collecting ducts from adrenalectomized rabbits.

The cortical collecting tubule is one of the main nephron sites where mineralocorticoids and a high potassium diet modulate sodium (Na) and potassium (K) transport. In this study we explored the steroid-independent effects of a high K diet on the electrical transport properties of the isolated rabbit cortical collecting tubule principal cells. The electrophysiological analysis included transepithelial and single-cell potential measurements and equivalent circuit analysis. Rabbits were adrenalectomized (ADX) and received either a control diet (300 meq K/kg diet) or a high K diet (600 meq/kg diet) for 10 d before the experiment. The mean plasma K of ADX control animals was 6.9 mM, that of ADX animals on the high K diet 8.3 mM. The transepithelial potential difference was significantly elevated in the high K group (-3.5 mV, lumen negative), compared with ADX controls (-1.4 mV). The basolateral membrane potential in high K animals was also significantly elevated (-73 mV, cell negative, compared with -63 mV in controls). Estimates of the apical membrane partial Na and K conductances (GaNa and GaK) and of ion currents (IaNa and IaK) also demonstrated stimulation by the high K diet. In the high K group, both GaNa and GaK (0.56 and 2.67 mS.cm-2) were higher than control values (0.27 and 1.17 mS.cm-2). IaNa and IaK were also higher in high K animals (47.8 and -26.2 microA.cm-2) compared with control animals (22.4 and -11.6 microA.cm-2). Thus, a high K intake per se can induce electrophysiological changes consistent with stimulation of Na reabsorption and K secretion.

Adrenalectomy↗
PubMed1988

Quadricuspid aortic valve perforation resulting from bacterial endocarditis--2-D echo- and angiographic diagnosis and its surgical treatment.

A 75-year-old man with quadricuspid aortic valve regurgitation affected by bacterial endocarditis is reported. The aortic valve consisted of 4 equal-sized cusps (type a) and a supernumerary cusp located between the right and noncoronary cusps. A right coronary ostium was close to the accessory commissure, but there was no displacement. A few small fenestrations were found at the 4 commissures and a large perforation resulting from endocarditis was observed in the noncoronary cusp. 2-D echocardiogram and angiogram suggested these findings, and they were confirmed at surgery. Successful aortic valve replacement was achieved.

Aged↗
PubMed1988

Changes in tumor cell adhesiveness affecting speed of dissemination and mode of metastatic growth.

Adhesion variants can be isolated from suspension growing highly metastatic murine ESb tumor cells under reproducible conditions from uncloned as well as from cloned ESb tumor cells. One such variant, ESb-MP, has been analyzed in detail. In vitro it had similar growth properties and high invasive capacity as the parental ESb cells. In vivo, ESb-MP cells showed a reduced growth capacity as compared to ESb cells. This was seen at the site of tumor cell transplantation (increased latency period) as well as at the site of secondary tumor growth in internal organs. ESb-MP tumor cells disseminated much later than ESb cells from the primary tumor into the blood stream. Both tumor lines metastasized to the liver but they affected liver functions in a different way: ESb cells infiltrated the liver diffusely and exerted toxic effects on liver parenchyma very quickly. This resulted in early increase of liver enzyme activity in the blood. In contrast, liver infiltrated by ESb-MP cells showed a more focal type of colonization and the organs seemed to be functioning for much longer periods. In fact, animals inoculated with ESb-MP cells subcutaneously or intravenously had an increased life expectancy compared to ESb-tumor-bearing animals of about 300%. The organotropism of both tumor lines remained similar although there were kinetic and quantitative differences, especially with regard to the kidney. In late stages of tumor growth, ESb-MP-tumor-bearing animals developed a high percentage of metastases in the kidney and around and within the spinal cord, thereby causing a syndrome of hind-leg paralysis. This syndrome was remarkable in its reproducibility, especially after intravenous tumor cell inoculation. The changed adhesiveness thus seemed to have affected the tumor latency period, the speed of dissemination into blood and internal organs, the mode of organ infiltration (focal vs. diffuse) and of metastatic growth, parameters which all might contribute to the greatly reduced overall malignancy.

Animals↗
PubMed1987

Quantitative description of nuclear morphology in assessing resistance of sarcoma 180 to adriamycin.

Resistance to adriamycin generally is explained through changes of cell/drug interactions that possibly reflect structural alterations of intracellular targets. One of the main targets of adriamycin is believed to be nuclear chromatin. In order to recognize chromatin alterations, we studied cell nuclei morphology and chromatin structure by means of digital image analysis. The studies were performed in both adriamycin-sensitive and -resistant Sarcoma 180 cell lines which were cultured under growth-stimulated and nonstimulated conditions. Using specially developed methods, we extracted parameters characterizing geometrical, optical, and structural properties of the cell nuclei from light microscopical images. The latter parameters concerned microscopical appearances of condensed chromatin and were described by features of high-optical-density regions. The results demonstrated that the quantitative criteria applied enabled the discrimination of sensitive and resistant cells. The most important parameters are the nuclear size, number, distribution, and optical density of condensed chromatin regions. In addition, the criteria permit recognition of changes related to differences in the growth conditions of the cells. The data of the image analysis suggest that adriamycin resistance in Sarcoma 180 cells is associated with characteristic patterns of cell nuclear morphology which can be described with a sufficient number of appropriate parameters. The advantages of image analysis are evident when these results are compared with the flow cytometric findings. The conclusion is that structural features of nuclear chromatin provide information essential for the assessment of drug resistance.

Animals↗
PubMed1987

Effects of adrenalectomy on CCD: evidence for differential response of two cell types.

Electrophysiological and chemical methods were used to determine the Na and K transport properties of the isolated cortical collecting duct (CCD) of control and adrenalectomized (ADX) rabbits. Net fluxes of Na (JNa) and K (-JK) in controls were 5.7 and 3.2 pmol . mm-1 . min-1 and in ADX were 1.0 and 0.7 pmol . mm-1 . min-1, respectively, similar to electrically determined rates. In separate experiments, blind impalement of cells from adrenal intact (group 1), ADX (group 2), and ADX rabbits treated with deoxycorticosterone (group 3) allowed identification of two distinct cell types, majority cells (MA) and minority cells (MI). In all groups, MA were distinguished from MI by a relatively high basolateral membrane potential (-Vb), low apical membrane fractional resistance (FRa), and presence of apical and basolateral membrane K conductances. Vb of MA (-82.4 mV) was significantly hyperpolarized in groups 1 and 3 combined, when compared with group 2 (-66.4 mV). However, there was no significant difference between Vb of MI in group 2 (-38.9 mV) and Vb of MI in groups 1 and 3 (-36.2 mV). In MA of group 1 equivalent circuit values of apical membrane Na and K conductances (GNaa, GKa) and maximum pump current (Ipmax) were 0.84 and 6.72 mS/cm2 and 46.7 microA/cm2, respectively. These values in group 2 were significantly lower (0.28 and 1.52 mS/cm2 and 8.7 microA/cm2, respectively). It is concluded that two cell types can be distinguished electrically in the CCD. MA have properties consistent with principal cells and MI have properties consistent with intercalated cells. ADX causes a decrease in GNaa, GKa, and Ipmax of PC that results in proportionate decreases in INaa and IKa.

Adrenalectomy↗
PubMed1987

Na-dependent effects of DOCA on cellular transport properties of CCDs from ADX rabbits.

Microelectrode methods were used to assess the Na-dependent effects of mineralocorticoids on the conductive transport properties of cortical collecting ducts (CCD) from adrenalectomized (ADX) rabbits. Rabbits were divided into four groups: control, 3 h treatment with deoxycorticosterone (DOCA), 18 h DOCA treatment, and 18 h DOCA plus amiloride treatment. After only 3 h of DOCA treatment the transepithelial potential (VT) increased significantly from -1.4 to -8.7 mV, and after 18 h VT increased further to -19.3 mV. The basolateral membrane potential (Vb) significantly increased after 18 h (from -61.6 to -87.6 mV). However, compared with treatment with DOCA alone for 18 h, both -VT and -Vb were significantly attenuated with DOCA plus amiloride treatment to -8.3 and -72.9 mV, respectively. The apical membrane Na and K currents (INaa and IKa) and conductances (GNaa and GKa) were all increased after 3 h DOCA treatment. After 18 h of DOCA treatment, IKa, INaa, and GKa increased further, but GNaa remained unchanged. On simultaneous treatment with DOCA and amiloride, the maximum pump current (Ipmax), IKa, INaa, and GKa but not GNaa were all reduced significantly. These results support a mechanism whereby mineralocorticoids first increase GNaa. A rise in cell Na results then in the simultaneous increase in GKa and sodium transport, probably by insertion of new Na pumps. An additional direct effect of DOCA on GKa and Ipmax is not excluded.

Adrenalectomy↗