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Biomedical subjects

M Chiba

Publications and source records attributed to M Chiba.

At least 343 records · Page 19Linked to original sources
PubMed1985

Comparison of differentiation patterns in 12-O-tetradecanoylphorbol-13-acetate-treated epidermis and fetal epidermis.

12-O-Tetradecanoylphorbol-13-acetate (TPA)-treated adult epidermis as well as untreated fetal and adult epidermis were investigated to elucidate the effect of TPA in terms of cell differentiation using techniques of ultrastructural stereology. Twenty-four hours after a single application of TPA, the treated epidermis was characterized by involutional changes, i.e., increased volume density of intercellular spaces and of mitochondria, vacuoles, and cytoplasmic ground substance in the basal layer. However, 48 h after application, the TPA-treated epidermis was very similar to fetal epidermis, i.e., high volume density of nuclei ribosomes, rough endoplasmic reticulum, membrane-coating granules, and keratohyalin granules, and low volume density of bundled filaments in the upper layers. These stereological data indicate that the changes observed 48 h after TPA treatment were related not only to increased cell proliferation but also to inhibition of cell differentiation expressed as a reversion of the adult differentiation patterns and the acquisition of fetal characteristics in all epidermal layers.

Animals↗
PubMed1985

Effects of colchicine and hydrocortisone on unimpeded eruption rates of root-resected mandibular incisors of rats.

A single injection of colchicine and daily injections of hydrocortisone have opposite effects on tooth eruption, respectively causing marked reduction and marked increase in unimpeded eruption rates in the root-resected incisors of rats. Unimpeded eruption rates of both root-resected and normal, non-resected, incisors responded identically to these two drugs, providing support for the view that the eruptive process following root resection is physiological. It was not possible to obtain direct evidence relating to either the hydrostatic pressure or the periodontal fibroblast hypotheses of tooth eruption; the drugs used to affect the eruption rates of resected rat incisors could also affect either the tissue hydrostatic pressure or the motility or contractibility of periodontal fibroblasts or both.

Animals↗
PubMed1985

Body reactions during chain saw work.

Body reactions during chain saw work were studied in 14 subjects. The subjects divided into three groups (control, sulpiride, and propranolol) successively cut down logs with a chain saw for seven minutes. The start of the sawing led to a pronounced increase in heart rate which persisted during the sawing. The groups taking sulpiride and propranolol showed a smaller increase in heart rate compared with the controls. Hormonal values (adrenocorticotropic hormone (ACTH), cortisol, adrenaline (Ad), noradrenaline (NA), and dopamine) were increased by the operation. A comparison of these values before and after the operation showed that the increase of cortisol, Ad, and NA values was highest in the controls, intermediate in the propranolol group, and lowest in the sulpiride group. The increase in ACTH, however, was greatest in the sulpiride group, intermediate in the controls and correct in the propranolol group. These findings provide some evidence that chain saw work may have an influence on the whole body, including the hypothalamus and the limbic lobe of the brain.

Adrenocorticotropic Hormone↗
PubMed1985

Effects of diltiazem on occupational Raynaud's syndrome (vibration disease).

An open trial on the therapeutic effect of diltiazem, a calcium antagonist, was conducted on occupational Raynaud's syndrome (vibration disease). Seventeen men with vibration disease were studied. The mean age was 54 years. No patient had cardiovascular disease. Primary and secondary cases of Raynaud's phenomenon were excluded. Diltiazem, 30mg orally 3 times daily, was given to the patients for 6 weeks. Before and after this treatment period, we evaluated the subjective symptoms (11 items including Raynaud's phenomenon, numbness of hands and arms, stiffness of shoulder and neck, and others) and peripheral function (by cold water immersion test, vibration and pain sensations for fingers, tapping test, and momentary grasp strength test), and did laboratory blood tests (12 variables). The "effective" rates of subjective symptoms evaluating by the method of 5 steps and the peripheral function was 69.6% and 52.9%, respectively. The overall effectiveness of diltiazem therapy was assessed by collectively evaluating the changes in subjective symptoms, peripheral functions, and the occurrence of side effects. No side effects occurred during the treatment period. Thus, the collective effectiveness of diltiazem was 64.7%. In conclusion, diltiazem, a calcium antagonist, can be effective in long-term treatment of patients with vibration disease.

Benzazepines↗
PubMed1985

Constitution of the greater splanchnic nerve in the rat.

The greater splanchnic nerve originating from the sympathetic ganglia between the 10th and 12th ribs on the dorsal thoracic wall passes through the diaphragm between its medial and lateral erura, to form the celiac plexus around the celiac trunk and superior mesenteric artery in the abdominal cavity. The nerve consists of about 10,000 of nerve fibers and of 25,000 of ganglion cells in its whole length of 2.5 cm; nerve fibers can be divided into myelinated fibers, accounting for less than 6% of total numbers, and unmyelinated fibers, which amount to more 90%. Special attention was not paid to the numerous ganglion cells in terms of their shapes, sizes, and cell organelles except for a small number of binucleate cells. However, the nerve contains remarkable synapses that connect between axon showing flat, elliptical, and cored vesicles and dendrite, between another type of axon having elliptical and cored vesicles and dendrite, and even between dendrite and cell body, in which synaptic vesicles are small spherical and elliptical. These facts can suggest that the greater splanchnic nerve contains more complex structure than has been hitherto described.

Animals↗
PubMed1984

The organ distribution of tin and the effect of tin on concentrations of several essential elements in rabbit.

The organ distribution and the effects of administration of tin, 5 mumol/kg/day, for 6 days on calcium, copper, iron, magnesium, phosphate, and zinc concentrations in plasma, erythrocytes, liver, kidney, and spleen of adult rabbits were studied. Kidney contained the highest concentration of tin, 15.0 +/- 1.64 micrograms/g wet weight (mean +/- S.D., n = 4). The concentrations of copper, phosphate, and magnesium increased significantly in the kidney, while magnesium concentration decreased in erythrocytes 1 day after the administration of tin for 6 consecutive days. A high correlation coefficient between magnesium and phosphate was observed in all organs tested. The correlation coefficients between P vs. Cu, P vs. Ca, and Mg vs. Ca in the liver were lowered during the period of tin administration, whereas those between P vs. Zn, Mg vs. Zn, and Cu vs. Zn in the kidney disappeared after tin administration was completed.

Animals↗
PubMed1984

The in vitro effects of zinc and manganese on delta-aminolevulinic acid dehydratase activity inhibited by lead or tin.

The effects of the administration of lead and tin on delta-aminolevulinic acid dehydratase (5-aminolevulinate hydro-lyase, ALAD, EC 4.2.1.24) activity in human, rabbit, and mouse blood were studied in vivo. In addition the ability of zinc, manganese, and dithiothreitol (DTT) to restore ALAD activity in the blood of lead- or tin-treated subjects was examined in vitro. Manganese, zinc, and DTT restored ALAD activity in vitro. The optimal concentration of zinc required in vitro was 10(-4) M in blood of lead-exposed humans and lead- or tin-administered mice, and 10(-3) M in blood of rabbits treated with either lead or tin. Even at the optimal concentration of zinc, the reactivating effect was incomplete, the highest recovery being about one-third of the control activity. However, the simultaneous addition of zinc and DTT increased ALAD activity to levels comparable with those of controls. Manganese was less effective than zinc in restoring ALAD activity in vitro; the effective dose was 10(-2) M in the blood of lead-exposed subjects, while little effect was noted in tin-treated subjects. Manganese was as effective as DTT in protecting against the inhibition of ALAD activity in vitro by excessive zinc. In contrast, DTT restored ALAD activity completely in the blood of tin-treated rabbits and produced about an 80% recovery of enzyme activity in the blood of tin-treated mice, but only a 35% recovery in the blood of lead-treated rabbits. These results suggest that the mechanisms by which lead and tin inhibit ALAD activity are different.

Animals↗
PubMed1984

The effects of stannous chloride on the humoral immune response of mice.

The effects of stannous chloride (SnCl2) on primary and secondary immune responses to sheep red blood cells (SRBCs) were examined in mice. I.p. administration of 167 mumol/kg/day of SnCl2 for 3 consecutive days suppressed the number of splenic indirect plaque-forming cells (PFCs) in the primary response and the hemagglutination (HA) and hemolytic reaction (HR) titers of non-2-mercaptoethanol(2-ME)-treated sera in both the primary and secondary immune response. However, tin affected neither the indirect PFC response nor the antibody titers of the 2-ME-treated sera after the secondary immunization, which was performed on day 6 following the primary immunization. These results suggest that the subacute administration of tin suppresses part of the immune response in which IgM antibody production plays an important role, and that the production of IgG in the secondary immune response is little affected, while the IgG production in the primary response is suppressed or delayed.

Animals↗
PubMed1984

The in vivo effects of manganese and zinc on delta-aminolevulinic acid dehydratase activity inhibited by lead.

The in vivo effects of zinc (Zn) and manganese (Mn) on the activity of delta-aminolevulinic acid dehydratase (5-aminolevulinate hydrolyase, ALAD, EC 4.2.1.24) in blood with and without inhibition by lead and on the functions of the liver and kidney were studied in rabbits. Administration of Zn or Mn alone caused little change in any of the 29 parameters tested at concentrations of 5, 10, 25 or 50 mumol element/kg body weight. Administration of 5 mumol lead/kg inhibited ALAD activity in blood, but it did not induce any marked effects on the indices of hepatic and renal functions. In simultaneous i.v. injection with lead and manganese, both at a dose of 5 mumol/kg, however, the recovery process of ALAD activity was delayed. Three out of 29 parameters tested, beta-lipoprotein, triglyceride and aldolase, increased significantly one day after simultaneous injection with lead and manganese. Equimolar zinc did not show either an antagonistic or cooperative effect on these three parameters and the ALAD activity in blood.

Animals↗
PubMed1984

Keratinocyte damage produced by 12-O-tetradecanoylphorbol-13-acetate in rodent epidermis.

Cell damage produced by 12-O-tetradecanoylphorbol-13-acetate (TPA) was evaluated in keratinocyte suspensions obtained from TPA treated mouse epidermis using a dye-exclusion technique, and in tissue sections studied by light microscopy and quantitative enzyme histochemistry. TPA induced a maximum of approximately 25% of trypan blue stained basal keratinocytes using topical doses of 2, 20 and 200 micrograms. With the first two doses this effect was detectable at 12-24 h and disappeared 48-96 h after TPA treatment, whereas with 200 micrograms TPA the cell damage persisted for a longer time. Oxidative enzyme changes were moderate, and no changes in acid phosphatase levels could be detected. The facts that no signs of cell necrosis could be seen in tissue sections from epidermis treated with 2 and 20 micrograms TPA; that only a moderate change in oxidative enzyme pattern, without statistically significant variations in succinic dehydrogenase and cytochrome oxidase, could be detected, and that no shift of the damaged basal keratinocytes into the suprabasal compartment was evident, are indicative of moderate, probably sublethal damage induced by TPA. Although eventually committed to terminal differentiation, the epidermal cells do not show the cytologic and metabolic features of lethally damaged cells, suggesting that the membrane damage detected by the dye exclusion technique may be sublethal. Thus, it is possible that TPA can induce a reactive or regenerative type of epidermal hyperplasia without the prerequisite of extensive keratinocyte necrosis.

Animals↗
PubMed1984

A protective action of coenzyme Q10 on chlorpromazine-induced cell damage in the cultured rat myocardial cells.

The interactions between coenzyme Q10 (CoQ) and chlorpromazine (CPZ) were studied after CPZ-induced injury of cultured myocardial cells of new-born Wistar rats. Administration of 7.5 X 10(-6) M of CPZ caused decreases in adenosine triphosphate (ATP) contents and beating rates by 77.4% and 54.2%, respectively. These changes were dependent on the dosage of CPZ. Histologically, many lamellated granules appeared in the cytoplasm and seemed to originate from mitochondria. The decreased density of the mitochondrial matrix and an irregular arrangement of cristae were also observed. Coincubation of the cultures with CPZ and CoQ led to a dose-dependent increase in ATP contents and beating rates. The appearance of increased number of granules in the cytoplasm was suppressed. Indomethacin, an inhibitor of prostaglandin synthesis, interfered with the effects of CoQ on the CPZ-induced myocardial cell injury. These findings suggest that CoQ may protect myocardial cells from CPZ-induced injury, and that prostaglandins may play an important role in the action of CoQ.

Adenosine Triphosphate↗
PubMed1984

A morphometric study of dedifferentiated and involutional dark keratinocytes in 12-O-tetradecanoylphorbol-13-acetate-treated mouse epidermis.

The epidermis of mice treated with 12-O-tetradecanoylphorbol-13-acetate (TPA) was investigated using the method of stereological cytology. These procedures were carried out in order to quantify the morphological changes taking place in basal cells, the presumed target cells of TPA in the epidermis. The basal layer of the treated epidermis was composed of TPA-induced dark basal keratinocytes (DC) and clear basal keratinocytes. TPA-induced DC could be divided into two types. Type 1 was characterized by a relatively high volume fraction of ribosome and nonbundled filaments and by a low volume fraction of bundled filaments. These characteristics of type 1 DC were relatively constant over the observation period. Type II DC were characterized by a high volume density of mitochrondria , bundled filaments, and cytoplasmic vacuoles. This type of DC was seldom seen in normal epidermis but constituted approximately 20% of the dark cells in the epidermis 24 and 48 hr after treatment with TPA. In contrast, clear basal keratinocytes exhibited time-dependent changes such as an increase of the relative volume of nuclei; an increase in the volume density of mitochondria, nonbundled filaments, and ribosomes; and a decrease in the volume density of bundled filaments. Both the qualitative and quantitative analyses of TPA-treated and fetal epidermis suggest a close similarity between type 1 DC and DC seen in normal fetal epidermis, thus supporting the view that type 1 DC are poorly differentiated cells or dedifferentiated cells, different from type II or involutional DC.

Animals↗