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Biomedical subjects

T Kuwabara

Publications and source records attributed to T Kuwabara.

At least 289 records · Page 16Linked to original sources
PubMed1981

Effects of moderate-intensity light on vitamin A-deficient rat retinas.

The effects of moderate-intensity light (150 to 200 ft-cd) on retinal structure were compared between retinol-adequate and retinol-deficient rats after 1 to 6 days of light exposure during the 12 hr light phase of the cycle. Both damage to the outer segments and loss of photoreceptor cells were accelerated in retinol-adequate rats. Outer segments in retinas of retinol-adequate rats showed an abnormal staining pattern and disruption of disc structure in the distal portion about 2 days before those of retinol-deficient rats. After 4 days of exposure 24% of the photoreceptor cells had degenerated in the retinol-adequate retinas, but only 6% in the retinol-deficient retinas. By 6 days 65% and 41% of the photoreceptors had degenerated in the retinol-adequate and retinol-deficient retinas, respectively. Thus light exposure induced more rapid degeneration of photoreceptor cells in rats receiving adequate retinol than in those deficient in this vitamin.

Animals↗
PubMed1981

[A case of alpha-fetoprotein producing primary intracranial embryonal carcinoma treated with combination chemotherapy with cis-platinum, vinblastine and bleomycin (author's transl)].

A case of alpha-fetoprotein (AFP) producing primary intracranial embryonal carcinoma was reported with special reference to the chemotherapy. The patient was a 14-year-old male who had suffered from vomiting and disturbance of consciousness. CT scan revealed a tumor originating in the anterior part of the third ventricle and expanding into both lateral ventricles. Right frontotemporal craniotomy was performed and the tumor was totally removed under the microscope. The histological diagnosis was embryonal carcinoma. Inspite of the elevated amount of AFP in the serum, we could not verify the yolk sac element in the surgical specimen. Three months later, he became drowsy and another CT scan revealed recurrence of the tumor. Ommaya's reservoir was placed and CSF was drained to control the intracranial hypertension. But the disturbance of consciousness did not improve. We then started a combination chemotherapy with cis-platinum, vinblastine and bleomycin. Cis-platinum was given in a dosage of 20 mg/m2 body surface area as a 15 min. intravenous infusion for 5 consecutive days every 3 weeks for three courses. Vinblastine was given in a dosage of 0.4 mg/kg body weight intravenously for 2 consecutive days every 3 weeks for three courses. Bleomycin was given in a dosage of 30 mg intravenously 6 hours after vinblastine weekly for a total of 12 weeks. The AFP level of the serum and CSF was monitored every several days. After the chemotherapy, the AFP level of the serum and CSF decreased. Repeated CT scan revealed no evidence of tumor. His clinical condition improved remarkably. Toxicity was vomiting, proteinuria and leukopenia, but not so severe. Proteinuria continued after the chemotherapy, but BUN and creatinine did not elevate. It was emphasized that the combination chemotherapy with cis-platinum, vinblastine and bleomycin is effective remission-induction treatment for AFP producing primary intracranial embryonal carcinoma.

Adolescent↗
PubMed1981

Damage to the monkey retina by broad-spectrum fluorescent light.

Adult rhesus and pigtail monkeys were exposed to a uniform field of light from daylight fluorescent lamps to determine the initial site and characteristics of structural retinal damage induced by continuous exposure and the threshold intensity required to produce the effects. Electron microscopic examination revealed that the initial site of damage is the photoreceptor outer segments. Damage remained restricted to the outer segments at intensities as high as 24,700 lux and with 12 hr exposure periods repeated for up to 4 days. Rods were swollen at the distal tip and showed disc membrane separation. Come outer segments were affected at the proximal end with vesiculation and membrane rearrangement. The threshold intensity for morphological changes to comes in the macula for a single 12 hr exposure was between 195 and 361 mu W/cm2 at the retina (400 to 700 mm; uncorrected for ocular transmittance), whereas the threshold for changes in rods was higher, at between 361 and 615 mu W/cm2. These levels correspond to between 5900 and 10,800 lux (550 to 1000 ft-cd) for comes and 10,800 to 19,400 lux (1000 to 1800 ft-cd) for rods of monkeys with fully dilated pupils. The paramacular areas of the retina were less sensitive to damage than macular areas of the same animal. No paramacular changes were observed in animals exposed to 10,800 lux or less. The patched (control) eyes of each monkey remained structurally normal in both the macula and paramacula at all exposure levels. These results demonstrate the sensitivity of the adult primate retina to damage by relatively moderate levels of light.

Animals↗
PubMed1981

Regression of the tunica vasculosa lentis in the postnatal rat.

Involution of the tunica vasculosa lentis (TVL) was examined in albino rats from 1 to 21 days after birth. Scanning electron microscopy demonstrated that as the lens increased in size, the larger vessels became straight and the small interconnecting vessels disappeared. Transmission electron microscopy revealed that the endothelial cells lost their close relationship with the posterior lens capsule. In the endothelial cells and pericytes the cytoplasm was dense, and many of the organelles became to recognize. However, the cells appeared to remain intact for into regression, shrinking until a basement membrane-like remnant remained. Vitreal cells were close to the TVL throughout the period studied, but few contained phagosomes. During regression the TVL appeared to (1) change its shape in order to accommodate the enlarging ocular structure, (2) maintain separation of the vitreal and vascular compartments by remaining intact during regression and (3) be associated with vitreal cells, which did not seem to play a prominent role in the involution of these vessels.

Animals↗
PubMed1980

Cerebellar neuroblastoma. A light and ultrastructural study.

A cerebellar tumor of a 4-month-old girl was examined by light and electron microscopy. The presence of numerous synaptic vesicles in many cell processes and the occasional synaptic devices warranted the diagnosis of neuroblastoma of the cerebellum. The nature of the tumor is discussed briefly.

Cerebellar Neoplasms↗
PubMed1980

Lipofuscin in vitamin E deficiency and the possible role of retinol.

This study was designed to determine if the vitamin A status of rats could affect the degree of lipofuscin formation in vitamin E deficient rats, inasmuch as an earlier report proposed a retinoyl complex in human brain lipofuscin pigment. Female rats were depleted of vitamin E from weaning while being maintained on different intakes of vitamin A (0, 0.8 and 8.0 mg/kg diet). The amount of lipofuscin present in the uterus was estimated at intervals between 2 and 8 months by visual observations, by histological fluorescence and by organic solvent extractable fluorescence. There was no difference in pigment deposition by any of the three criteria used, whether the animals were made retinol deficient and maintained on retinoic acid or were fed a low or high intake of retinol. Organic solvent extractable fluorescence was a poor indicator of the degree of pigment deposition in the uterus. It appears unlikely that retinol is a significant component of lipofuscin pigment in this tissue.

Animals↗