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Biomedical subjects

K Obara

Publications and source records attributed to K Obara.

At least 163 records · Page 9Linked to original sources
PubMed1984

Some properties of chemically skinned single smooth muscle cells.

Properties of isolated single smooth muscle cells in which the surface membrane has been made highly permeable by saponin treatment are described. The single cells were isolated from guinea pig taenia caeci by digestion with collagenase and skinned in a relaxing solution by treatment with 7 micrograms/ml saponin for 10 min. The skinned single cells showed Ca2+-regulated shortening in the presence of Mg-ATP, and the maximum degree of shortening was larger than that of the potassium-induced shortening observed in the intact isolated single cells. The half maximum shortening of the skinned single cells occurred at about 5 x 10(-8) Ca2+. The skinned single cells showed a significantly higher Ca2+-sensitivity than the skinned fiber bundles. The shortening-pCa curve for the skinned single cells was unchanged by alteration of pH and ionic strength, but it was shifted to the left by increasing MgATP concentration or to the right by increasing free Mg2+ concentration. The skinned single cells retained their internal Ca2+ storage site function. Caffeine induced shortening in the skinned single cells preloaded with Ca2+, and this shortening was suppressed by procaine. The release of Ca2+ from the storage site could be produced and facilitated by Ca2+ itself when the skinned single cells were exposed to Ca2+ with a concentration of about 2 x 10(-8) M and this release was suppressed by procaine. These results suggest that the Ca2+-induced Ca2+ release mechanism may play a role in the regulation of the stored Ca2+ in this cell.

Adenosine Triphosphate↗
PubMed1984

Isolation and contractile properties of single smooth muscle cells from guinea pig taenia caeci.

A method for the isolation of single smooth muscle cells from guinea pig taenia caeci is described. The single cells were prepared by digestion with 0.3% collagenase and 0.6% trypsin inhibitor in Ca2+-free solution. This procedure produced a high yield of intact cells. Most cells obtained by this procedure were relaxed and showed large contractile responses to excitatory stimulus. Maximal responses of the single cells to acetylcholine (ACh), histamine, and high K+ were attained within 20 sec, and the per cent decrease in cell length was 30-40%. Times for maximal responses of the single cells were shorter than those of the muscle strips. Single cells exhibited a dose-dependent graded response to calcium under depolarized conditions, ACh, histamine, and high K+, and a voltage- and duration-dependent response to electrical stimulation. The ED50s of ACh in the single cells and in the muscle strips were about 2 X 10(-8) and 1.5 X 10(-7) M, respectively. The muscle strips had a lower sensitivity than the single cells to ACh. The generally smooth surface of the relaxed cell contrasted with the numerous evaginations present on the fully contracted cell. I believe that single smooth muscle cells isolated from guinea pig using my technique are, at present, better for physiological and pharmacological studies than are cells isolated using other techniques.

Acetylcholine↗
PubMed1983

[Experience in treatment of Mycoplasma pneumoniae with acetylspiramycin].

Antibiotics of tetracycline and macrolide groups are mainly used in treatment of Mycoplasma pneumonia. In this study, acetylspiramycin (ASPM), an antibiotic of macrolide group, was given to 15 cases of Mycoplasma pneumoniae who visited this institute during the period from January, 1980 to March, 1981, and its clinical effects and side effects were investigated. The therapeutic effects were evaluated by days to the normal body temperature, to improvement in cough and to improvement in X-ray findings. The increase in serum antibody value was adopted as the diagnostic index of Mycoplasma infection. The patients who entered into this study were 7 males and 8 females, ranged from 19 to 60 years of age with an average of 36.3 years. The daily dose of ASPM was 600 to 1,200 mg (potency), and the mean administration period was 18.1 days. The results obtained were as follows. 1. The temperature fell to the normal within 2 to 7 days. 2. Cough disappeared in 2 days at shortest and in 55 days at longest. The mean period of cough disappearance was 14.5 days. 3. In 10 cases who could be followed up, shadows in X-ray films disappeared in 3 days at shortest and in 40 days at longest. The mean period to shadow disappearance was 18.6 days. 4. As regards clinical effects, marked improvement was obtained in 2 cases, improvement in 9, slight improvement in 4, and no change in 0 (improvement rate: 73.3%). 5. As a side effect, nausea was found in 1 case, but it was improved by discontinuance of administration.

Adult↗
PubMed1982

The increase of cardiac beta 1-subtype of beta-adrenergic receptors in adult rats following neonatal 6-hydroxydopa treatment.

An analysis of Hofstee plots of specific [3H]dihydroalprenolol ([3H]DHA) binding in the presence of various concentrations of practolol showed that KD and Bmax in beta 1-subtype adrenoceptors were 19.2-fold lower and 2.76-fold higher than those in beta 2-subtype in adult rat hearts, respectively. Neonatal treatment with 6-hydroxydopa produced a significant increase only in Bmax in beta 1-adrenoceptors without changing Bmax and KD in beta 2-receptors. "Up' regulation in the density of beta 2-type of adrenoceptors seems to be caused by the 6-hydroxydopa-induced sympathetic lesion.

Animals↗
PubMed1981

Free vascularized fibular graft for replacement of the radius after excision of giant cell tumor: case report.

A case is reported in which a giant cell tumor of the distal end of the radius was treated by massive resection and reconstruction with a free vascularized bone graft taken from the fibula. The postoperative course was uneventful. Angiograms made eight weeks after surgery showed patent anastomoses. One year after surgery there was no evidence of recurrence of the tumor, and roentgenograms showed no degenerative changes and bony union with hypertrophy at the junction of the radius and the graft. An excellent clinical result was obtained, and the patient was able to return to his original occupation as an illustrator.

Bone Neoplasms↗