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Biomedical subjects

H Nagata

Publications and source records attributed to H Nagata.

At least 343 records · Page 19Linked to original sources
PubMed1984

[Effect of local sustained stress on general oxygen consumption in belt conveyer workers].

The modern mechanization and rationalization of production procedures have recently reduced the intensity of work in most factories. However, it has been pointed out that monotonous inactive work and/or co-operative work can in some sense impose stronger mental and physical stresses which may induce ill health in workers. In this study, assuming the assembly and adjustment of videotape-recorders on a belt conveyor to be representative of monotonous inactive and co-operative work, changes in oxygen consumption, heart rate, blood pressure, body temperature, critical flicker fusion and subjective symptoms of fatigue throughout a workday have been followed for six female workers engaged in this type of work. The main results obtained were as follows: The average oxygen consumption of six workers was 230 ml/min, almost unchanged during the work. The belt conveyor work indicated the metabolic rate of 0.3 in terms of relative metabolic rate. The net daily energy expenditure due to the work was only about 100 kcal. The average heart rate during assembly and adjustment were respectively, about 1.4 and 1.2 times the average heart rate at rest. The blood pressure and the rate of oxygen removal increased slightly as the work progressed in assembly work, but did not increase at all in adjustment work. The critical flicker fusion and body temperature showed little change during the work.

Adult↗
PubMed1984

Uptake of carbon and polystyrene particles by the sinusoidal endothelium of rabbit bone marrow and liver and rat bone marrow, with special reference to multiparticle-pinocytosis.

The endocytosis of tracer particles by sinusoidal endothelial cells was studied in the bone marrow and liver of the rabbit and in the bone marrow of the rat after intravenous injection. The tracer particles used included carbon particles and polystyrene particles of different sizes ranging from 0.11 to 5.7 micron in diameter. The sinusoidal endothelial cells of the rabbit liver and rat bone marrow took up carbon through the formation of bristle-coated vesicles at the luminal surface, but they eventually failed to ingest polystyrene particles of 0.11 micron or larger. On the other hand, the sinusoidal endothelial cells of the rabbit bone marrow took up carbon and polystyrene particles varying from 0.11 to 2.02 micron in diameter. These endothelial cells were found to sequester circulating tracer particles in the cytoplasm through the formation of two kinds of vesicles at the luminal surface: bristle-coated vesicles and "multiparticle-pinocytotic vesicles." This special type of pinocytotic vesicle was larger in diameter than the bristle-coated vesicle and variable in size according to the size or amount of the particles to be sequestered. Carbon and 0.11 micron polystyrene particles were taken up by means of both the bristle-coated vesicles and multiparticle-pinocytotic vesicles, whereas particles 0.30 micron in diameter or larger were taken up by the vesicles similar in nature to multiparticle-pinocytotic vesicles. A sequence for the morphological events occurring in the formation of multiparticle-pinocytotic vesicles in the sinusoidal endothelial cells of rabbit bone marrow shall be suggested and discussed.

Animals↗
PubMed1984

Neurotransmitters in dementia.

Changes in the activity of neurotransmitters in dementia were studied by measuring the activities of each of choline acetyltransferase (CAT), dopamine-beta-hydroxylase (DBH) and hydroxylase cofactor (tetrahydrobiopterine; BPH4), and the concentrations of homovanillic acid (HVA) and vasopressin. CAT activity was low in the cerebral cortex of patients with senile dementia of Alzheimer's type (SDAT). The CAT activity was high in the nucleus basalis, which correlated well with the CAT activity in the cerebral cortex, Brodmann areas 22 and 17. DBH activity was lower in the cerebrospinal fluid (CSF) of SDAT and multi-infarct dementia (MID) patients than in that of control subjects. No age-related change was observed in control subjects. Serum DBH activity was decreased in patients with SDAT but not in patients with MID. DBH activity was especially low in the serum of SDAT patients with a low dementia rating score and/or severe brain atrophy shown on computed tomography (CT) scan. Serum DBH activity was also decreased in older normal subjects (greater than or equal to 80 years). The concentration of HVA in the CSF of control subjects decreased with the advance of age, but the decrease in HVA concentration was more pronounced in the CSF of SDAT patients, which would reflect the lowered dopaminergic activity in SDAT. BPH4 activity was also decreased in the CSF of SDAT patients. Arginine-vasopressin was widely demonstrated in the cerebral cortex of control subjects but could not be detected in many areas of the cerebral cortices of demented patients. These results suggest that a deficit of dopamine, noradrenaline or vasopressin as well as acetylcholine may occur in the brain of SDAT patients. The evidence presented points toward areas for consideration in the search for methods of therapy or prevention of SDAT.

Adult↗
PubMed1984

Histologic and microcirculatory changes in alcohol-induced gastric lesions in the rat: effect of prostaglandin cytoprotection.

The effect of 16,16-dimethyl prostaglandin E2 (dmPGE2) on histologic and microcirculatory changes in alcohol-induced gastric mucosal injury was studied. A histologic study confirmed that dmPGE2 does not protect the surface mucous cells against ethanol injury but does protect against the deeper necrotic lesion. Both the gross injury and the necrotic lesion were as severe after 1 min of ethanol exposure as after 60 min. A study of benzidine-stained sections and hematoxylin and eosin-stained sections revealed marked engorgement of microvessels and hemorrhage in the superficial mucosa after ethanol injury. Pretreatment with dmPGE2 prevented these. An in vivo fluorescent microscopy study revealed that there was total stasis of blood flow in the injured area. After the intravascular injection of a fluorescein-albumin conjugate, the conjugate filled microvessels in grossly normal areas of mucosa but not in grossly injured areas. Pretreatment with dmPGE2 prevented this microcirculatory change. This alcohol-induced stasis of flow in injured areas may be of pathogenetic significance and prostaglandin protection might involve prevention of this microcirculatory change.

16,16-Dimethylprostaglandin E2↗
PubMed1984

In vivo observation of the lymphatic system in the rat stomach.

The anatomy of the lymphatic system in the rat stomach was studied by means of fluorescent in vivo microscopy. A fluorescein-albumin conjugate was injected via a micropipette into the mucosa, submucosa, or muscularis externa. The movement of the conjugate was visualized using a closed-circuit television system. When injected into the base of the mucosa, the conjugate was seen to flow from the deposited pool. These fluorescent streams, 21-53 micron in diameter, formed a network in the base of the mucosa and superficial submucosa. They were in close approximation to, but separate from, the arterioles and venules. These fluorescent channels are probably lymphatic microvessels, as they were connected to larger lymphatic vessels running parallel to the large arterioles and venules in the deep submucosa. These larger lymphatic vessels passed through the muscularis externa and drained into extragastric lymphatic vessels on the lesser or greater curvature. There was no network of lymphatic microvessels in the deep submucosa or muscularis externa. The extragastric lymphatic vessels, 50-340 micron in diameter, had valves and displayed spontaneous contractions, moving the conjugate toward the lymph nodes.

Animals↗
PubMed1983

Increased manganese level in spinal cords of amyotrophic lateral sclerosis determined by radiochemical neutron activation analysis.

The manganese distribution in the cross-section of the cervical, thoracic and lumbar portion of the spinal cords from 7 autopsied cases with amyotrophic lateral sclerosis (ALS) and 6 control subjects were determined by radiochemical neutron activation analysis. It was possible to determine 1 ng levels of manganese content accurately in the small tissues about 1 mg of dried weight using wet ashing and chemical separation after neutron activation. The dried weight of spinal cord was about 1/3 of the wet weight. Manganese concentration in the wet tissue was calculated from the ratio of dried to wet weight. In the anterior horn of the cervical cords of ALS, manganese concentration was the highest; 1.75 +/- 0.39 ng/mg of dried weight and 0.59 +/- 0.09 ng/mg of wet weight, respectively. These were significantly higher (P less than 0.01) compared to those in controls; 1.02 +/- 0.12 ng/mg of dried weight and 0.35 +/- 0.04 ng/mg of wet weight, respectively. The elevation of manganese level in the spinal cords of ALS was more prominent in the anterior horn and lateral column than in the posterior column both in dried and wet tissues. Since manganese inhibits neuronal transmission, it is likely that neurological degenerative changes occur as a result of local disturbances of manganese metabolism in the spinal cord of ALS.

Amyotrophic Lateral Sclerosis↗
PubMed1983

Effect of histamine on microvascular permeability in the rat stomach.

The effect of histamine on gastric microvascular permeability to macromolecules in the rat was studied using fluorescent in vivo microscopy. Histamine was applied topically to the serosal surface for study of the muscularis externa, to the submucosa, and to the superficial mucosa, and the area of leaks of a fluorescein-albumin conjugate from microvessels was quantitated. In the muscularis externa both histamine and an H1-agonist, but not an H2-agonist, caused dose-dependent leak of conjugate from venules. An H1-antagonist, but not an H2-antagonist, decreased the histamine-induced leak. In the submucosa histamine caused dose-dependent dilatation of arterioles but not leak of conjugate. In contrast, bradykinin caused both dose-dependent dilatation of arterioles and leak of conjugate from venules. In the superficial mucosa histamine did not cause any leak. In conclusion, topical histamine 1) increased microvascular permeability to macromolecules from venules in the muscularis externa via H1-receptors, 2) did not affect microvascular permeability in the submucosa (this may be due to lack of histamine receptors on the venules as bradykinin increased venular permeability), and 3) did not affect microvascular permeability in the superficial mucosa, but there might not have been adequate histamine backdiffusion.

Animals↗
PubMed1982

Effect of colchicine on intestinal alkaline phosphatase activity during linoleic acid absorption in rats.

The purpose of this study is to examine whether intestinal alkaline phosphatase (IAP) plays a role in transporting lipoproteins to lymphatics during fat absorption. In control rats, the increased activity of IAP in intestinal lymph was observed parallel with the amount of absorbed linoleic acid. In colchicine-treated rats, lymphatic absorption of intraduodenally administered linoleic acid was decreased and administered lipid was transported slowly to lymphatics, mostly in the form of free fatty acid. However, the equal or slightly larger amount of output of IAP to lymphatics was observed in spite of the decrease in lipid absorption in colchicine-treated rats. Histochemically, prolonged activity of IAP in stroma and submucosal lymphatics was found in colchicine-treated rats fed with fat. These results suggest that microtubules are not involved in IAP transport into lymphatics, and these data do not necessarily rule out that IAP plays a role in lipoprotein transport.

Alkaline Phosphatase↗
PubMed1982

Role of dextran sulfate in urokinase therapy and evaluation of the effects by estimation of plasmin inhibitor, fibrinogenolytic degradation products, and fibrinolytic degradation products.

The present study was concerned with changes in APTT and coagulation-fibrinolytic inhibitors in 2 groups of patients receiving either UK with heparin or UK with heparin and dextran sulfate (DS). APTT just after UK treatment showed a significant prolongation in patients receiving combination treatment with DS, but contrarily a shortening in patients receiving those with DS. This result indicated the usefulness of DS combination in UK treatment. There was a marked difference between the responses of alpha 2-PI and antiplasmin to the treatment, presumably as a result of immune complex formation of the alpha 2-PI with plasmin. However, no marked difference in alpha 2-PI and AT-III existed both just after and at 24 hours after UK treatment in patients receiving UK (240,000 units) with both heparin and DS and those receiving UK (480,000 units) with heparin. Those results suggest that the dosage of UK can be reduced by combination of DS. Successful UK treatment in clinical cases resulted in a decrease of alpha 2-PI and an increase of fibrinogenolytic or fibrinolytic degradation products. For these reasons, effective UK treatment appears to require combination with DS and several treatment days under the condition with a decrease of alpha 2-PI (50%) and fibrinogenolysis with fibrinolysis, which are followed by administrations of UK.

Antithrombin III↗
PubMed1982

Asparenomycins A, B and C, new carbapenem antibiotics. IV. Antibacterial activity.

Asparenomycins (ASM) A, B and C, new members of the carbapenem family of antibiotics, are broad spectrum antibiotics with activity against Gram-positive and Gram-negative bacteria. ASM A was bactericidal to both aerobic and anaerobic bacteria, although morphological alterations of ASM A exposed cells differed significantly between Escherichia coli and Bacteroides fragilis; with the former ovoidal forms were produced while with the latter elongated forms were seen. Synergistic activities were observed with a combination of ASM A and ampicillin (ABPC) against various ABPC-resistant bacteria presumably as a result of the inhibition by ASM A of beta-lactamases. ASM A showed relatively weak therapeutic activity against E. coli infected mice, because of instability in body fluids, a common property of the carbapenem family of antibiotics.

Animals↗