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Biomedical subjects

F Sato

Publications and source records attributed to F Sato.

At least 415 records · Page 23Linked to original sources
PubMed1982

Spontaneous sweat secretion in calcium-free strontium medium.

Sr2+ substitutes for Ca2+ in methacholine (MCH)-evoked sweat secretion in isolated simian eccrine sweat glands, but four to eight times greater concentrations of Sr2+ were required to achieve the same effect as did a given Ca2+ concentration. In Ca2+-free Sr2+ medium the anticholinergic effect of atropine was reduced by about four orders of magnitude. In the Sr2+ medium, spontaneous sweat secretion (SSS) was also observed in the absence of any pharmacological stimuli. SSS occurs slowly, reaching a plateau after 30 min incubation. The maximal SSS is a saturation function of Sr2+ concentration reaching a maximum at 8 mM. Sr2+-induced SSS was inhibitable by removal of Sr2+, low bath temperature (10-14 degrees C), ouabain (5 X 10(-6) M), and D 600 (10(-3) M). Ca2+ was found to inhibit Sr2+-induced SSS, but a Schild plot for the Ca2+ and Sr2+ dose relationship failed to show a slope of unity. The data suggest that Sr2+-induced SSS represents actual secretory processes, which are triggered by Sr2+ leaking into the cell through as yet undefined membrane channels.

Animals↗
PubMed1982

Transepithelial potential during strontium-induced spontaneous sweating.

Transepithelial electrical potential difference (PD) of the secretory portion of the rhesus monkey palm eccrine sweat gland was studied in both Ca2+-containing (control and Ca2+-free Sr2+ media. In the control medium, the luminal PD was a saturation function of the methacholine (MCH) concentration, reaching a plateau at about -6 mV (lumen negative) at 10(-5) M MCH. In the Sr2+ medium, the luminal PD increased spontaneously with a time course similar to that the spontaneous sweat secretion (SSS). Like SSS, the spontaneous luminal PD in the Sr2+ medium is a saturation function of the Sr2+ concentration in the bath, reaching a plateau at -9 mV at 8 mM Sr2+. Addition of MCH to the Sr2+ medium caused a rapid increase in the lumen-negative PD as seen in the control medium. The spontaneous lumen-negative PD was abolished by subsequent addition of Ca2+ to the bath, as was the SSS [K. Sato, Am. J. Physiol. 239 (Cell Physiol. 8): C90-C97, 1980]. The data further reinforce the notion that Sr2+-induced SSS represents true secretory processes which are triggered by Sr2+ leaking into the cell bypassing the receptor-agonist interaction.

Animals↗
PubMed1982

In vivo and in vitro characteristics of eccrine sweating in patas and rhesus monkeys.

Biopsy specimens from the chest, palm, back, and lateral calf were obtained from three patas (4-6 kg) and two rhesus monkeys (6 and 8 kg) tranquilized with ketamine hydrochloride (10 mg/kg). The eccrine sweat glands of the specimens were subsequently isolated under a stereomicroscope and prepared for analysis. In both palmar and hairy skin (chest, lateral calf) patas eccrine glands were larger than those isolated from corresponding sites obtained from the rhesus specimens. In vitro stimulation of the patas' glands with methacholine (MCH) chloride produced a dose-dependent increase in sweating rate that was blocked by atropine. Maximal palmar sweating was comparable between the two species of monkey. Mean maximal in vitro sweating rates on the chest and lateral calf of the three patas monkeys were 3.79 and 4.6 nl. gl-1.min-1, respectively. In contrast, the in vitro sweating rate of the rhesus chest glands was negligibly small, i.e., 0.05 nl.gl-1. min-1. Maximal in vivo sweating rates measured by resistance hygrometry during exercise in a hot (40 degrees C) environment were usually synchronous, cyclic, and only slightly below maximal in vitro rates. When the monkey (patas) was already sweating, the onset and cessation of exercise produced an immediate rise and decline in sweating, respectively. At any given rectal or mean skin temperature, sweating was two- to sixfold higher in the patas compared with that of the rhesus monkey. These results indicate that the patas monkey is an excellent model for studying the physiology of sweating in humans.

Animals↗
PubMed1982

[Clinical study of cefsulodin on infectious diseases in otorhinolaryngological field].

The clinical effect of cefsulodin (CFS) on Pseudomonas species infections in otorhinolaryngologic field was studied in 10 patients. The overall clinical effectiveness was 80% (excellent 4, good 4, poor 2). The bacteriological response of CFS against Pseudomonas species was evaluated from 11 strains. Eradication rate of Pseudomonas species was 82%. In 1 case, body temperature was rised after injection. No abnormal laboratory findings, relating to the drug, were observed after treatment.

Adult↗
PubMed1981

Cytochemical study on enzyme activity associated with cerebrospinal fluid secretion in the choroid plexus and ventricular ependyma.

Normal adult albino and Sprague-Dawley rats, under intraperitoneal Nembutal anesthesia, were used to demonstrate enzymatic activity in the choroid plexus and ventricular ependyma. The brain tissues were perfused or immersed with cold 2% glutaraldehyde and 8% sucrose in 0.1 M cacodylate buffer (pH 7.2-7.4) for 30 min and washed overnight in the same buffer solution., The choroid plexus (lateral and fourth ventricles) and ventricular ependyma (lateral ventricle) were trimmed from the fixed and washed brain tissues, which were frozen and sectioned. For histo- and cyto-chemical study, the sections were immersed in the following incubation media; for Na+, K+-ATPase (ouabain-sensitive, K+-dependent, p-nitrophenylphosphatase: p-NPPase) according to the one-step method of Mayahara et al. (1978): for Mg2+- ATPase, Wachstein-Meisel's incubation medium (1957); for adenylate cyclase (AC), following Araki and Saito's lead citrate method (1979). The cytochemical findings gave the following results. In the choroid plexus, the ouabain-sensitive electron-dense reaction products of NA+, K+-ATPase (p-NPPase) were strongly positive in the microvilli and along the inner surface of microvilli, without showing any Mg2+-ATPase and AC activities, and all three enzymatic activities were positive along the basal plasmalemmas and negative along the lateral and apical (not including microvilli) plasmalemmas. In the ventricular ependyma, Na+,K+-ATPase (P-NPPase) activity was not found, and the reaction product of AC was observed on the apical plasmalemmas and those of Mg2+-ATPase along the basal plasmalemmas. These cytochemical findings are helpful in understanding the regulation of cerebrospinal fluid production through Na+, K+-ATPase (p-NPPase) and cyclic AMP (AC).

4-Nitrophenylphosphatase↗
PubMed1981

On the mechanism by which insulin stimulates protein synthesis in chick embryo fibroblasts.

It has been known that insulin raises the rate of incorporation of [3H]leucine into the total protein of hormone-deficient chick embryo fibroblasts by approximately 1.5-fold. The elevation is not dependent upon the production of new messenger ribonucleic acids (mRNAs). Evidence is now presented in support of the following points: the greater labelling is due to more rapid polypeptide synthesis, not to an increase in the specific activity of leucyl-tRNA; the enhanced synthesis derives largely or entirely from a speeding up of the process of initiation, rather than that of elongation or termination; and the 1.5-fold stimulation is due to the elevated rates of formation of at least many of the fibroblast proteins. The hormone was shown before to stimulate posttranscriptionally and highly preferentially for formation of ribosomal proteins in the resting chick embryo cells. The question has been asked here whether insulin increases the production of total cell ribosomal protein by chemically altering preformed mRNAs. Results obtained by translating messages from deprived and hormone-treated cells in wheat germ and reticulocyte preparations do not support a mechanism involving covalent modification of preformed mRNAs. The observations, coupled with those previously made with inhibitors of translation, lead us to suggest that insulin stimulates protein synthesis in the resting chick embryo cells by activating limiting components of the initiation system. The effects of the hormone are greatest with messages, such as those for the ribosomal proteins, that have low affinities for the limiting initiation components.

Animals↗
PubMed1981

Ultrastructural localization of carbonic anhydrase activity in the rat choroid plexus epithelial cell.

Localization of carbonic anhydrase activity was studied electron microscopically on cells of the rat choroid plexus epithelium. For the ultracytochemical detection of these activities, Yokota's technique (1969), which is the modification of Hansson's method (1967) was employed. Numerous electron dense reaction products were observed in the microvilli of the choroidal epithelial cell. The reaction deposits were also remarkably present in the infoldings of the basal plasmalemma but to a lesser extent than in the microvilli. The localization sites were mainly on the plasma membrane, but some reaction products were also observed in the cytoplasm near the plasma membrane. Hardly any reaction product was found in the intracellular organelles except for the mitochondria in which reaction products were occasionally observed on the cristae. These activities were completely inhibited by acetazolamide. As the carbonic anhydrase activity was histochemically seen in the microvilli and the basal infoldings, it is likely that carbonic anhydrase is related to an active transport process in the secretion of cerebrospinal fluid as is Na+, K+ -ATPase (Masuzawa et al. 1980).

Animals↗
PubMed1981

The enzyme cytochemistry of the intracellular organelles in the rat choroid plexus epithelial cell.

Electron microscopic cytochemical studies on the rat choroid plexus epithelium have revealed enzymatic sites for the activities of acid phosphatase, glucose-6-phosphatase and thiamine pyrophosphatase on different organelles. Only the activity of acid phosphatase has been previously described. Acid phosphatase, glucose-6-phosphatase and thiamine pyrophosphatase were respectively situated mainly in the lysosomes, in the endoplasmic reticulum an nuclear envelope, and in the Golgi complex. These three enzymes can thus be considered as marker enzymes for their respective organelles in the choroid plexus epithelial cells as well as in other tissue cells. The possible function of these enzymes in the choroid plexus epithelial cells is also briefly discussed.

Acid Phosphatase↗
PubMed1981

Cyclic AMP accumulation in the beta adrenergic mechanism of eccrine sweat secretion.

Tissue cyclic 3'5'-AMP (cAMP) concentrations were measured after stimulation of isolated monkey palm eccrine sweat glands with various stimulants of sweat secretion. The cellular cAMP levels increased curvilinearly with time of incubation to reach a steady state after 5 min of incubation with isoproterenol. Theophylline more than doubled the isoproterenol-induced cAMP accumulation, whereas theophylline alone increased the basal cAMP level to a minor extent. Phenylephrine failed to stimulate cAMP accumulation. There was no increase in the cAMP level after stimulation with methacholine. A calcium ionophore, A23187, also failed to stimulate cAMP accumulation. Since isoproterenol, theophylline (or isobutylmethylxanthine), and dibutyryl cAMP all induced eccrine sweat secretion in isolated, cannulated sweat glands to varying degrees in vitro, cAMP is probably involved in the beta adrenergic mechanism of sweat induction. The isoproterenol-induced cAMP accumulation was not inhibited by removal of Ca2+ from the incubation medium for as long as 30 min. The striking similarity between the eccrine sweat gland and the salivary glands in the roles that Ca2+ and cAMP play in stimulus secretion coupling indicates that the eccrine sweat gland will serve as another useful model system for the study of the mechanisms of exocrine secretion.

Animals↗
PubMed1981

Ultrastructure of disseminated choroid plexus papilloma.

A disseminated choroid plexus papilloma (DCPP) with a malignant change in the cervico-spinal leptomeninges observed 4 years after the removal of choroid plexus papilloma (CPP), originating from the fourth ventricle, was studied under the electron microscope. Although the ultrastructure of intracranial CPP has been reported by several authors, there are just a few reports on DCPP. The present tumor was ultrastructurally very similar to normal choroid plexus, but the lack of the capillary fenestration and of invaginations of the epithelial basal plasmalemmas suggested that the epithelium was deprived of secretory function.

Cerebral Ventricle Neoplasms↗
PubMed1981

Late effects of whole or partial body x-irradiation on mice: life shortening.

Life table data were obtained on 2400 ddY/SLC female mice exposed at 10 weeks of age to a single dose of X-rays. Doses given to the whole body were 95, 190, 380 and 570 rad, and to head, trunk or lower body, 190, 380, 570 and 760 rad. The mean survival time of unirradiated controls was 73 weeks. The mean survival times after whole body exposure decreased linearly with increasing dose. The estimate of life shortening per 100 rad was 7.2 per cent for whole body exposure. The life shortening after head or lower body exposure to a dose of 190 rad was 6.2 and 7.1 weeks respectively, and almost no further life shortening up to 760 rad. After trunk irradiation with 190 rad, life shortening was 10.4 weeks and beyond that dose life shortening was 1.1 per cent per 100 rad.

Actuarial Analysis↗
PubMed1981

Retrovirus particles in spontaneously occurring and radiation-induced tumors in ddY mice.

Among spontaneously occurring tumors, pulmonary tumor, malignant lymphoma, mammary tumor, and ovarian tumor were the major ones in 232 ddY female mice. The former three tumors appeared significantly earlier and the latter one increased in incidence in 229 mice given 600 R whole or 800 R partial body (tunk) x-irradiation at the age of 10 weeks. Five tumors were examined electronmicroscopically from each tumor type of both the spontaneously occurring and radiation-induced tumors. C type virus particles were present only in the malignant lymphoma and B particles in the mammary, ovarian and pulmonary tumors, which are all of epithelial character. Thus, as far as we were concerned in this mouse strain, B particles were produced preferentially in epithelial cells and C particles in non-epithelial cells. The retrovirus particles were found in the same frequency, namely, 10 of 20 tumors examined in both the tumor groups. From our results, the intervention of virus in radiation carcinogenesis still remains in question.

Animals↗