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Biomedical subjects

H Kawamura

Publications and source records attributed to H Kawamura.

At least 361 records · Page 20Linked to original sources
PubMed1987

Transplantation of the suprachiasmatic nucleus in the rat.

Restoration of the circadian rhythmicity in wheel-running activity was shown in rats with bilateral suprachiasmatic nuclei (SCN) lesions, after transplantation of the neonatal SCN into the wall of the third ventricle. Free-running circadian rhythms of the wheel-running activity were recorded in young adult rats at least for a month under constant dark condition. Then, bilateral SCNs were completely lesioned electrolytically under deep pentobarbital anaesthesia. After further recording for more than two months without obvious circadian rhythmicity in wheel-running activity, the animals were subjected to transplantation of the SCN. SCNs taken from day 1 neonatal rats were transplanted by injecting the grafts into the third ventricle of the host rat under pentobarbital anaesthesia. After recovery from the procedure, the rat was returned to a cage with a running wheel. Food and water were available at all times. Successful transplantation led to restoration of the circadian rhythmicity starting from two weeks and up to three months after the transplantation. To identify the SCN in the transplanted graft, we used an immunohistochemical staining method for the VIP (vasoactive intestinal polypeptide) and vasopressin. The VIP was located particularly in the ventral area of the SCN, whereas vasopressin was in the dorsal area. In most cases, where circadian rhythmicity was successfully restored, the graft was attached to the caudal wall of the third ventricle.

Animals↗
PubMed1987

A comparative study of the calcification-promoting action of 1,25 (OH)2D3 and calcitonin on the growth cartilage of rats with 1-hydroxyethylidene-1, 1-biphosphonic acid (HEBP)-induced rickets.

When HEBP (1-hydroxyethylidene-1, 1-biphosphonic acid) was administered to young rats in large doses over a short period rickets was consistently produced. When HEBP was administered concomitantly with 1,25 (OH)2D3 or calcitonin (CT), calcification appeared in the growth-plate cartilage where there had been an increase in thickness due to the inhibition of calcification. This experiment was done in an attempt to clarify differences in the calcification-promoting mechanisms of 1,25 (OH)2D3 and CT. The serum alkaline phosphatase level was reduced in rats with an accelerated calcification following the administration of 1,25 (OH)2D3, but there was no reduction in the serum alkaline phosphatase level in rats in which the calcification was accelerated by the administration of CT. The mode of appearance of calcification in the growth-plate cartilage by 1,25 (OH)2D3 or CT differed, depending on the time of administration. These results suggest that mechanisms involved in the enhancement of calcification by 1,25 (OH)2D3 and CT differ in cases where rickets are induced by HEBP.

Alkaline Phosphatase↗
PubMed1987

Intestinal bacteria antagonistic to Clostridium difficile in mice.

Overgrowth by Clostridium difficile has been reported in conventional mice injected intraperitoneally with ampicillin. In this study, we aimed to determine which types of indigenous intestinal bacteria were eliminated by ampicillin to allow overgrowth by C. difficile. C. difficile overgrowth was associated with a decrease in the numbers of lactobacilli, an increase in bacteroidaceae and a slight decrease in the frequency of isolation of fusiform-shaped bacteria (clostridia). C. difficile cytotoxin was detected in caeca from mice in which the numbers of C. difficile were greater than 10(5) per gram of faeces. Gnotobiotic mice were inoculated with various groups of intestinal anaerobes to determine which members of the indigenous flora would antagonize C. difficile. Gnotobiotic mice inoculated with three strains of lactobacilli, 37 strains of bacteroides or 46 strains of clostridia isolated from limited-flora mice were unable to eliminate C. difficile. C. difficile was eliminated, however, from the gastrointestinal tracts of gnotobiotic mice inoculated with whole faeces or chloroform-treated faeces from conventional mice or whole faeces from limited-flora mice containing only clostridia.

Ampicillin↗
PubMed1987

Morphologic study of inclusions in tissues from pigs inoculated with cytomegalovirus.

Six 5-day-old gnotobiotic pigs inoculated intranasally with the J-1 strain of porcine cytomegalovirus (PCMV) were euthanatized within 9 to 18 days after inoculation. All pigs developed a subclinical form of PCMV infection and had characteristic intranuclear inclusions in all tissues. Morphologically, 2 types of inclusions were observed. One was a small herpetic intranuclear inclusion in reticuloendothelial cells, which contained a few nucleocapsids in the nucleus. The other was a typical cytomegalic intranuclear inclusion in macrophages in the lungs and in tubuloalveolar gland cells in the nasal mucosa. Inclusions contained many nucleocapsides in the nucleus and a large number of enveloped viral particles in the cytoplasm. The distribution of the specific immunofluorescent antigen of PCMV was coincident with the presence of herpetic and cytomegalic inclusions.

Animals↗
PubMed1987

Possible pathogenesis of congenital stationary night blindness.

We reported a case of congenital stationary night blindness (CSNB) who showed Schubert-Bornschein type electroretinogram (ERG) in the right eye and nearly normal ERG in the left eye with absolute glaucoma. From the electrophysiological findings of both eyes and histological findings of the enucleated eye, we concluded that the mechanism of night blindness in CSNB is an abnormal inhibition in the bipolar cell layer. The experiments in rabbits by vincristine intravenous and intravitreous administrations did not give rise to a negative type ERG, but to a decrease of the amplitude of all ERG components. The lesion of CSNB which was reported to be responsible in the synaptic terminal by Ripps et al could not be confirmed.

Aged↗
PubMed1987

[CT-guided stereotactic brachytherapy in deep-seated malignant gliomas--interstitial irradiation by double-catheter after-loading method].

CT-guided stereotactic brachytherapy has been performed for the deep-seated malignant gliomas using the double-catheter after-loading method. The catheter system consists of two coaxial polyethylene tubes with closed tips. The outer catheter is 3.0 mm in outer diameter and 2.4 mm in inner diameter. The inner catheter is 2.0 mm in outside diameter and 1.4 mm in inside diameter, and contains the radioactive sources. Localization of the target volume is determined by the preoperative findings of computed tomography (CT), magnetic resonance imaging (MRI), and cerebral angiography. Dosimetry and dose planning are so finalized for the target volume as to be irradiated interstitially more than tumoricidal dose. After stereotactic biopsy of the deep-seated brain tumors, stereotactic implantation of the outer catheters is performed using Iseki Stereotactic System in the CT room. Burr holes had been previously opened in the operating room. The inner catheters containing nonradioactive sources (dummy sources) are inserted, and skull X-p is taken to confirm the position of the dummy sources, and to calculate the dosimetry by computer. The inner catheters are replaced with catheters containing radioactive sources (226Ra) in the irradiation room. 226Ra sources deliver at least 500 rads/day (approximately 20 rads/hr) to the target volume as interstitial irradiation. Two patients of malignant gliomas treated with this procedure were shown as representative cases. These patients underwent CT-guided stereotactic brachytherapy as "boost" combined with conventional external irradiation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

[EEG topographic changes of brain abscesses in children].

EEG topography was investigated before and after surgical treatment in 4 patients with brain abscess aged from 5 to 13 years. According to the recording technique designed by Matsuoka and Ueno, the recorded EEG for each 5 seconds was analyzed to obtain square roots of power spectra for each band of delta (2-3.8 Hz), theta (4-7.8 Hz) and alpha (8-12.8 Hz) which were then added for the 60-seconds duration of each trial. After that, numerical matrix presenting the topographic distribution of spectral energy of each band were constructed and displayed as color images. In addition, the EEG topographies of brain abscesses were compared with the CT scans simultaneously obtained. In all of four cases before surgical treatment of the brain abscess, the location of the focal delta wave on the EEG topography was more closely related to the site of brain abscess comparing with its correlation between the location of the delta focus on the conventional EEG and the site of brain abscess. In contrast, as for the theta wave, there was no prominent correlation to the site of the brain abscess. In the early stage of 10-15 days after aspiration of the brain abscess, the most characteristic change of the EEG topography was an approximately 25% reduction of the maximum equivalent voltage of delta band with associated disappearance of the sharply located focal delta wave being noted before aspiration.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1987

Possible microapocrine-type secretion developing in prostatic secretory epithelial cells of older rats in the early stage of castration.

Secretory epithelial cells at 1 and 2 d after castration became higher than those of control as the result of convex protrusion of the apical cytoplasm into the acinar lumen, which was quickly followed by pinching off the small balloon-like cytoplasmic process developing on its surface. At the same time, the secretory vacuoles became more numerous, while the well-developed Golgi region, prominent rough endoplasmic reticulum and its dilated end facing the Golgi region remeined. On 7 and 14 d after castration, secretory epithelial cells became markedly low and they had very few secretory vacuoles, regressed Golgi region and a markedly reduced amount of rough endoplasmic reticulum. At 7 d after castration, marcrophage-like cells appeared among secretory epithelial cells and acinar basal lamina. These findings might suggest that the involutionary process of secretory epithelial cells was started by apical convex protrusion and accompanied by microapocrine secretion of its subsurface cytoplasm followed by phagocytosis of the remaining disintegrated cytoplasm by macrophage-like cells.

Animals↗