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Biomedical subjects

C Ohkubo

Publications and source records attributed to C Ohkubo.

At least 37 records · Page 2Linked to original sources
PubMed1995

Selectin- and integrin-mediated T-lymphocyte rolling and arrest on TNF-alpha-activated endothelium: augmentation by erythrocytes.

The adhesive and hemodynamic forces that lead to lymphocyte rolling and arrest on activated endothelium and the biophysical role of various adhesion molecules and blood elements in this process are poorly understood. By quantifying their behaviour both in vivo and in vitro, we show here that erythrocytes facilitate selectin- and integrin-mediated rolling and binding of T-lymphocytes on tumor necrosis factor alpha-activated endothelium. The relative contribution of selectins and integrins to this process can be distinguished by using a simple mathematical expression of lymphocyte capture within the range of physiological shear stress. The need for selectin participation in lymphocyte capture increases with shear stress (> 1 dyn/cm2), and both beta 1 and beta 2 integrins act in synergy to produce adhesive drag on captured cells. These findings are potentially useful in developing strategies for intervening with T-cells in a variety of normal and pathological responses as well as for the delivery of genetically modified T-cells to their targets in vivo.

Animals↗
PubMed1995

Physiological reaction and manual performance during work in cold storages.

Subjects were 10 workers (Group R) working in two cold storages (air temperature was between -20 degrees C and -23.2 degrees C), and eight workers (Group C) working in a general storehouse (air temperature was between 12 degrees C and 15.2 degrees C). They were all male workers operating forklift-trucks. Average (SE) age for Group R was 41.4(1.3) years and for Group C was 47.3(1.6) years. Hand tremor, handgrip strength, pinch strength, counting task, flicker value, peak flow rate and blood pressure were measured five times (before work, at 10 a.m., before lunch, at 3 p.m. and after work) per day. Blood samples were collected before lunch. Free fatty acid (FFA) of Group R was significantly higher than that of Group C. There were no significant differences in handgrip strength, pinch strength, counting task, flicker value and peak flow rate between Group R and Group C. However, changes in hand tremor and diastolic blood pressure for Group R were significantly greater than those for Group C. Only for Group R, there was a significant relationship between FFA and the hand tremor values measured the second time. Work loads of Group R would be increased by not only the extreme coldness but also large temperature difference between the inside and the outside of the cold storages. The actual forklift work in these cold storages did not cause a distinct reduction in manual performance, but caused an increase in stress which would be expressed as an increase in catecholamine excretion.

Adaptation, Physiological↗
PubMed1992

[A successfully treated case of thoracic meningocele with von Recklinghausen's disease].

Intrathoracic meningocele is an uncommon disease. Only 95 cases in the foreign literature and 13 cases in Japanese literature have been reported since Phol Meningocele occurs most frequently in the sacral and lumbar spinal regions. In this present paper, an 18-year-old female with intrathoracic meningocele associated with neurofibromatosis is described. The patient was admitted to our Surgical Clinic with a complaint of constrictive pain in the upper chest. The meningocele was diagnosed preoperatively and resected surgically by left thoracotomy. The patient has been followed up to for six years without any evidences of local recurrence. However, she recently complains of headache and weakened eyesight because of pituitary tumor, the operative indication of which is now discussed.

Adolescent↗
PubMed1992

Modulation of hepatic and pulmonary drug-metabolizing enzyme activities of rabbits by dietary cholesterol.

Modulation of the activities of drug-metabolizing enzymes by dietary cholesterol was studied in rabbits. In male rabbits fed a 1.5% cholesterol-diet, an elevated levels of serum cholesterols and triglycerides were observed from the early phase of cholesterol-feeding. At 12 weeks after the onset of cholesterol feeding, a marked increase was observed in the wet weights of livers but not of lungs, while total contents of lipids and cholesterols were elevated in both tissues in cholesterol-fed animals. The content of collagen was increased significantly in livers, but not in lungs and the phase I drug-metabolizing enzyme activities were significantly reduced in livers but remained unchanged in lungs by cholesterol feeding. On the other hand, the phase II drug-metabolizing enzyme activities varied depending on the enzymes in both tissues. The results demonstrate that dietary cholesterol induces different effects on rabbit liver and lung and that the modulation of the hepatic enzymes by dietary cholesterol in rabbits differs from that in rats, mice and guinea pigs in which the activity of the enzymes are elevated by dietary cholesterol.

Animals↗
PubMed1991

Interleukin 2 induced leukocyte adhesion to the normal and tumor microvascular endothelium in vivo and its inhibition by dextran sulfate: implications for vascular leak syndrome.

The maximum dose of interleukin 2 (IL-2) alone or with adoptively transferred lymphocytes is limited by the vascular leak syndrome, resulting from an increase in vascular permeability. Using intravital microscopy to quantify cell interaction in vivo and the Miles assay to assess changes in vascular permeability, we have shown that IL-2 increases both leukocyte-endothelial cell adhesion and vascular permeability in the cutaneous tissue of rabbits. Both of these processes can be reversed to a large extent using dextran sulfate (Mr approximately 500,000; 10 mg/kg body weight), a nonspecific blocker of leukocyte-endothelial adhesion. These results suggest that increased leukocyte (probably lymphocyte) adhesion to the postcapillary microvasculature contributes significantly to the IL-2 induced increase in permeability. Therefore, as more specific inhibitors of leukocyte-endothelial adhesion become available, improved strategies could be developed to control or prevent IL-2 toxicity.

Animals↗
PubMed1989

[Structural designs in the removable partial dentures].

Today the removable partial dentures are used as permanent prosthetic devices. Thus, their designs must be considered the prevention of breakage or deformation. A metal plate denture consisting of double structure has been designed with the intention of improved mechanical strength and durability. Principal investigations of this study were to introduce structural design techniques and apply them to denture design, to analyze the double structure using the finite element method, to judge reliability using a statical bending test, to compare the breaking strength of each structure, and to measure movement during function of mandibular extension base removable partial dentures on the simulation model. The summary of results is shown below: 1. Calculated values and experimental values were a fairly good approximation. 2. The reinforcement and Lightweight method of double structure was made evident. 3. Regarding the packing resins, METADENT was slightly superior in mechanical strength to ACRON. 4. Maximum stiffness of the double structure was approximately 7-10 times that of skeleton types, and breaking strength was about 9 times. 5. Tensile strain generated at the double structure was statistical less than for skeleton types. 6. When loads of 10 kg applied, the difference of distal displacement between double structure and skeleton types was between 70-80 microns. 7. The stiffness of the skeleton types decreased remarkably by shortening the denture flanges, but the double structure did not show significant change.

Dental Stress Analysis↗
PubMed1989

[Basic studies on hard direct reline resins. Part 1. Adhesive strength].

Direct relining methods has come to occupy an important position in removable denture prosthodontics. The purpose of this study was to investigate the effect of various experimental conditions on the adhesive strength of hard direct reline resins to denture base resin. The experimental conditions were as follows: 1) immersion time of denture base resin before relining, 2) amount of load at relining, 3) roughness of adhesive surface, 4) immersion time of relined resin. The following results were obtained: 1. The adhesive strength of Rebaron was the highest, followed by that of TRIAD and KOOLiner. 2. The immersion times of denture base resin did not appreciably affect the adhesive strength. 3. With the rougher adhesive surface, Rebaron and KOOLiner showed a tendency to increase adhesive strength. 4. The adhesive strength was not appreciably affected by load. 5. We did not find a definitive correlation between adhesive strength and immersion times of relined resin.

Adhesiveness↗
PubMed1988

[Acute effects of topical application of methyl N-trimethyl-gamma-aminobutyrate chloride on cutaneous microcirculation in the healthy male rabbit].

Effects of acetylcholine (ACh) and its reversed carboxy analogue, methyl N-trimethyl-gamma-aminobutyrate chloride (MTB), induced either by topical application to the skin surface around a transparent round table chamber (REC) that had been previously installed to the ear lobe or by intravenous injection on the micro- and macrocirculations were studied in the healthy male rabbit. The effects of both drugs on the cutaneous microcirculation within the REC were observed vital-microscopically under conscious conditions and the microcirculatory events were visualized with a microscope-closed TV system and microphotoelectric plethysmography. The results were as follows: (1) Topical application of 1% MTB cream caused an enhanced perfusion of rhythmic microvascular blood due to vasomotion for a period of 30 min or longer, while ACh did so to a much less extent, if any. On the other hand, no appreciable change developed in any systemic hemodynamic parameters. (2) Intravenous administration of MTB or ACh caused a very transient dilator effect on micro-and macrocirculatory blood vessels according to its cholinergic stimulation, which could be blocked by atropinization. Almost the same efficacy on vasomotion was observed for each drug. (3) These findings indicate that the topical application of MTB to the skin surface may cause a physiologically acceptable vasodilation accompanied by vasomotion, and it would facilitate the oxygen diffusion by the follicular circulation.

Acetylcholine↗
PubMed1988

A modified rabbit ear chamber and an example of its application for intravital-microscopic study on acute effects of topical thermal stimulation.

A pre-existing plastic rabbit ear chamber was modified to be applicable for intravital-microscopic observations in pharmacological as well as pathophysiological studies on inflammation. The chamber consists of a base disk, a mica (or glass) cover-slip and a holder ring. The base disk has a round-table with a central protrusion in which a heat conductor of platinum wire is so implanted near the protrusion that thermal stimulation can be given to the regenerated tissue between the table and the coverslip.

Animals↗
PubMed1988

Intravital-microscopic observations on the intravascular behavior of blood cell components during dietary-induced hyperlipidemia in the male rabbit.

In normal male rabbits loaded dietary cholesterol, intravital-microscopy revealed a marked acceleration of intravascular adhesiveness of white blood cells and aggregability of red blood cells and a swarming of lipid-laden macrophages in connective tissue space concurrently with a systemic hyperlipidemia and anemia. Possible roles of the microcirculatory changes in the atherogenesis were discussed.

Animals↗
PubMed1987

Vasodilator effects of cepharanthine, a biscoclaurine alkaloid, on cutaneous microcirculation in the rabbit.

Cutaneous microcirculatory responses to intravenous administration of cepharanthine (CT), a biscoclaurine alkaloid, isolated from Stephania cepharantha, were studied in a transparent round chamber installed in a rabbit ear, under conscious conditions. Vital-microscopic observations were made visually with a microscope-closed TV system and microphotoelectric plethysmography. Following the CT administration in doses of 1.0 and 3.0 mg/kg, an enhancement of rhythmic perfusion of microvascular blood due to vasomotion was developed for a period of 1 h or longer, although no appreciable change was observed following CT administration at 10.0 mg/kg. The microvascular dilator effect of CT appeared to have no direct association with systemic hemodynamics, based on the additional measurements of heart rate, blood pressure, carotid blood flow and auricular arterial blood flow.

Alkaloids↗
PubMed1987

Effects of acupuncture needle application upon cutaneous microcirculation of rabbit ear lobe.

Microcirculatory effects of the application of an acupuncture needle (32-gauge, silver) to the back, corresponding to Geshu (B17) in human beings, were studied in vivo by microscope, using a transparent ear chamber in conscious rabbits. Although no striking findings were obtained during the needle application for a period of 30 minutes, it was clearly observed that the microvascular blood flow increases gradually in parallel with augmenting spontaneous rhythmic fluctuation of the vessel diameter, namely vasomotion, throughout a continuous observation period longer than 2 hours following release from the needle application. Diameters of arterioles and venules at the full-dilating phases of vasomotion reached levels higher than 200% and 250% of the initial values just before application of the needle, respectively. The clinical efficacy of acupuncture was suggested to be explained at least in part by the increased rhythmic microvascular blood flow in parallel with vasomotion, from the physiological point of view based on the previous investigations.

Acupuncture Therapy↗
PubMed1980

Cutaneous microcirculatory effects of various vasodilator agents on the conscious rabbit, with special regard to changes in the rhythmic property of vasomotion.

Microcirculatory effects of intravenous administrations in the appropriate doses of phenoxybenzamine (POBA), phentolamine (PTA), nicotinic acid (NAc), trimetazidine (TMZ), dilazep (DZ), cepharanthine (CT), alpha-tocopheryl acetate (TP-A), and alpha-tocopheryl nicotinate (TP-N) as vasodilator agents were investigated in the subcutaneous tissue within a transparent ear chamber of the normal conscious rabbit. The intra-vital microscopic findings obtained following administration of the drugs were as follows: POBA, a marked and long-lasting vasodilatation without vasomotion (more than 1 hour); PTA, a quite brief vasodilatation followed by a marked and long-lasting vasoconstriction without vasomotion (more than 1 hour); NAc, a short-lasting vasodilatation with slightly blunted vasomotion (less than 10 minutes); TMZ, DZ, CT, TP-A, and TP-N, a similar notable and transient vasodilatation with vasomotion (about 1 hour or more). Some physiological implications on the microcirculatory changes induced by administrations of the drugs were discussed especially in relation to the significance of sustaining the rhythmic fluctuations of blood flow due to vasomotion.

Animals↗