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Biomedical subjects

M Kusuhara

Publications and source records attributed to M Kusuhara.

29 records · Page 2Linked to original sources
PubMed1990

Alterations in membrane fluidity during keratinocyte differentiation measured by fluorescence polarization.

The epidermis shows a distinctive pattern of differentiation wherein keratinocytes proliferate in the basal cell layer and mature into spinous and granular cells. Using a discontinuous density-gradient centrifugation method, guinea-pig keratinocytes were separated into high (HDF), intermediate (IDF), and low (LDF) density fractions. Morphological and flow cytometrical observations demonstrated that HDF, IDF, and LDF were basal, spinous, and granular cell-rich fractions, respectively. Membrane fluidity of the fractionated keratinocytes was measured by diphenylhexatriene fluorescence polarization. Polarization (p)-value of keratinocytes was negatively correlated with temperature. At each temperature, HDF cells showed a lower p-value than IDF or HDF cells except at 40 degrees C. Since a low p-value indicates a high degree of Brownian motion, membrane fluidity is higher in basal cells and lower in spinous and granular cells. Our results indicate that membrane fluidity of guinea-pig keratinocytes decreases during their maturation.

Animals↗
PubMed1990

Atrial natriuretic peptide secretion in rabbits with aortic regurgitation.

We investigated whether or not the extent of secretion of atrial natriuretic peptide (ANP) was altered during the chronic course of aortic regurgitation (AR) in rabbits. AR was induced by aortic valve perforation in 20 rabbits. Left ventricular end-diastolic pressure (LVEDP) was used as an index of the severity of heart failure. LVEDP and plasma immunoreactive(IR)-ANP were measured before and at 15 min, 1 week, and 4 weeks after induction of AR. In each period a correlation between LVEDP and plasma IR-ANP was observed, and the coefficients and covariances did not vary throughout the experiment. We conclude, therefore, that a chronic change in ANP secretion does not develop during the first 4 weeks after induction of AR in rabbits.

Animals↗
PubMed1990

Intracoronary endothelin-1 increases coronary retrograde pressure by constricting arterioles.

STUDY OBJECTIVE: The aim was to determine the site of coronary vasoconstriction induced by endothelin, by investigating the response in terms of retrograde pressure and reactive hyperaemia. EXPERIMENTAL MATERIAL: Twelve anaesthetised mongrel dogs, 12-14 kg, were used for the studies. DESIGN: The left anterior descending coronary artery was cannulated and perfused with blood through an extracorporeal bypass. The effects of intracoronary endothelin-1 (1-500 pmol) on coronary blood flow, coronary flow reserve (the peak reactive flow and the repayment after 15 s coronary occlusion), and retrograde coronary pressure during coronary occlusion were studied (n = 7). The retrograde coronary flow was collected from the bypass at each dose (n = 5). MEASUREMENTS AND MAIN RESULTS: At doses of greater than 20 pmol the coronary flow decreased dose dependently and reached almost zero flow at 500 pmol. The coronary flow reserve also decreased; however, the retrograde pressure was raised dose dependently at doses of greater than 10 pmol. At a dose of 500 pmol, the retrograde pressure was increased to 61 mm Hg [82(SEM 12)% of the coronary perfusion pressure]. Retrograde flow remained unchanged throughout the experiment. CONCLUSIONS: The endothelin-1 induced rise in retrograde pressure is in accordance with a dose dependent reduction in coronary flow reserve, and collateral flow was not augmented by endothelin. It is concluded that the effect of endothelin-1 on coronary circulation in situ was mainly due to the constriction of small resistant vessels.

Animals↗
PubMed1990

Cutaneous phaeohyphomycosis caused by Exophiala jeanselmei after renal transplantation.

A 60-year-old man who had had a renal transplantation developed a nodule on the dorsum of his right middle finger, which was subsequently diagnosed as cutaneous phaeohyphomycosis caused by Exophiala jeanselmei. The patient was successfully treated with 5-fluorocytosine. To our knowledge, this case is the third reported case in the world caused by this species in a postrenal transplant patient that manifested as phaeohyphomycosis.

Dermatomycoses↗
PubMed1989

Effect of endothelin as a coronary vasoconstrictor in the Langendorff-perfused rat heart.

The effects of endothelin on coronary circulation were studied in isolated rat heart using a constant-flow system. Endothelin (10 fmol to 20 pmol/g heart weight) elevated the coronary perfusion pressure in a dose-dependent manner. Nifedipine (100 nM) inhibited the vasoconstriction and shifted the dose-response curve to the right. These results indicate that endothelin is a potent coronary vasoconstrictor and that its action is possibly mediated by the nifedipine-dependent Ca2+ channel.

Animals↗
PubMed1989

Mobilization of intracellular calcium by endothelin in Swiss 3T3 cells.

When intracellular free Ca2+ concentration [( Ca2+]i) was monitored in fura2-loaded Swiss 3T3 cells, endothelin increased [Ca2+]i in a dose-dependent manner; after the addition of endothelin, an initial transient peak was observed immediately and was followed by a sustained increase in [Ca2+]i lasting at least 5 min. 45Ca2+ efflux and influx experiments in endothelin-stimulated Swiss 3T3 cells revealed that the change in [Ca2+]i could be explained by a dual mechanism; an initial transient peak induced mainly by the release of Ca2+ from intracellular stores and the sustained increase by an influx of extracellular Ca2+. Cellular generation of inositol 1,4,5-trisphosphate and cyclic AMP were not induced by endothelin, suggesting that other cellular mediators with the capacity to release Ca2+ from intracellular stores play a significant role in the signal transduction pathway of endothelin in Swiss 3T3 cells.

Animals↗
PubMed1989

Endothelin potentiates growth factor-stimulated DNA synthesis in Swiss 3T3 cells.

A murine cell line, Swiss 3T3, is commonly used for the study of cellular growth. The present study revealed that this cell line possesses high-affinity receptors for endothelin, a vasoactive peptide derived from vascular endothelial cells. In this cell line, endothelin potentiated DNA synthesis stimulated by platelet-derived growth factor, basic fibroblast growth factor or insulin. The endothelin concentration required for potentiating DNA synthesis in this cell line is almost the same as that reported previously in endothelin-induced vasoconstriction. Since endothelin increased intracellular calcium levels, this ion may participate in the signal transduction pathways by which endothelin induces potentiation of DNA synthesis.

Animals↗
PubMed1988

Purification of rat cutaneous mast cells with Percoll density centrifugation.

The skin is the major site on anaphylaxis, and cutaneous mast cells have an important role in its reactions. The isolation and purification of rat cutaneous mast cells are described here. Rat abdominal skin was digested with collagenase and hyaluronidase, and centrifuged with Percoll. The buoyant density of cutaneous mast cells was high, and relatively pure mast cells were obtained. The purity of cutaneous mast cells was 74% +/- 2.4% before and 50.0% +/- 6.4% after Percoll density centrifugation; peritoneal mast cells revealed 5.8% +/- 1.3% purity before and 61.0% +/-10.6% purity after the same procedure. The isolated cutaneous cells released 21.3% +/- 3.8% histamine and the peritoneal mast cells released 55.5% +/- 3.8% histamine upon stimulation with 10 micrograms/ml compound 48/80. These findings suggest that there are functional subsets of connective tissue mast cells.

Animals↗
PubMed1988

Statistical survey of 150 cases with sporotrichosis.

A survey of 150 cases with sporotrichosis seen at the Dermatological Clinic of Kurume University Hospital from February 1962 to October 1986 was reported. The proportion of cases with sporotrichosis to the total number of outpatients was 0.17%. Greater percentage of cases fell into the less than 10 years old or more than 40 years old groups. The male to female ratio was 1:1.46, and 38 cases occurred in farmers. Geographic distribution was remarkable, especially around the Chikugo and Yabe river. Sixty-four cases showed the cutaneous lymphangitic type and 85 cases the localized cutaneous type and one case atypical type. The face and upper extremities were the most affected. The sporotrichin test was positive in 117 of 131 cases. The causative organism was demonstrated in tissue sections in 69% of the cases.

Adolescent↗
PubMed1988

Cardiovascular effects of intravenous and intracoronary administration of atrial natriuretic peptide in halothane anesthetized dogs.

Cardiovascular actions of synthetic 1-28 human natriuretic peptides (hANP) were examined in dogs anesthetized with halothane. In seven closed-chest dogs a Swan-Ganz catheter was inserted for measurement of cardiac output. Intravenous infusion of increasing doses of hANP (0.1, 0.3, 0.9 microgram/kg/min) lowered mean aortic pressure without affecting heart rate significantly. Cardiac output and pulmonary wedge pressure were markedly decreased while total peripheral resistance was increased significantly. All these parameters returned to control levels after 1 hr of recovery with an 100-150ml of saline infusion to increase pulmonary capillary wedge pressure to the preinfusion value. Intracoronary infusion of hANP (0.05 and 0.1 microgram/kg/min) did not cause any significant changes in coronary flow and regional contraction. These results indicate that the hypotensive action of hANP is due to a decrease in cardiac output mediated by reduced preload but not by negative inotropic action.

Anesthesia↗