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Biomedical subjects

T Kuwabara

Publications and source records attributed to T Kuwabara.

At least 307 records · Page 17Linked to original sources
PubMed1980

Membrane alterations during cataract development in the Nakano mouse lens.

The anterior cortical fiber cells of the 12-day-old Nakano mouse lens revealed an extremely large number of gap junctions, the appearance of which was identical to those of the normal lens. Although the number of gap junctions of the cells in the same area at 29 days was comparable to that seen at 12 days, the size of each junction became smaller with cataract formation. The junctions were almost absent in the anterior cortical cells in 7-month-old Nakano mice. Biochemical analysis revealed that the 26,000 MW polypeptide closely associated with the cell membrane was lower in amount in the membrane preparation of the 29-day Nakano mouse lens than in the 12-day lenses. With the membrane fractions of lenses from 90-day Nakano mice, the absence of a major 26,000 NW polypeptide component correlates with the decrease in gap junction structures. The alternations in the gap junctions and membrane associated polypeptides of the Nakano lens may be linked with the steps leading to cataract development.

Aging↗
PubMed1980

Deficiencies of vitamins E and A in the rat. Retinal damage and lipofuscin accumulation.

The interrelationships of vitamins E and A in maintaining various structural components of the retina were studied in four groups of weanling female rats fed purified diets adequate or deficient in each vitamin: +E, +A; -E, +A; +E, -A; and -E, -A. Groups deficient in retinol (-A) were supplemented with retinoic acid. After 14, 21, and 35 weeks, the retinas were examined histologically and ultrastructurally. At 35 weeks, the doubly deficient rats (-E, -A) had lost 92% of their rod nuclei, whereas rats deficient in vitamins A (+E, -A) or E (-E, +A) alone had lost only 34% and 20%, respectively. Vitamin E deficiency resulted in extensive lipofuscin deposits in the retinal pigment epithelium as early as 21 weeks, but the presence of vitamin A doubled the number of lipofuscin granules (-E, +A vs. -E, -A) and induced an even greater increase in their autofluorescence. Another clear influence of vitamin A was seen when +E, +A retinas autofluoresced not only much more than +E, -A retinas, which had similar numbers of granules, but also more than -E, -A retinas, which had about twice as many lipofuscin granules. In the retina, unlike the uterus, the lipofuscin-specific autofluorescence and lipofuscin granule number were not proportional. Moreover, the numbers of granules were influenced by both vitamins E and A, whereas the intensity of lipofuscin-specific autofluorescence was determined almost exclusively by vitamin A. Probably the accelerated loss of photoreceptor cells in -E, -A retinas resulted from both oxidation of membranes and oxidation of retinal vitamin A stores in the absence of vitamin E protection.

Animals↗
PubMed1979

Purification and characterization of 33 kilodalton protein of spinach chloroplasts.

A protein was prepared from spinach chloroplasts in a highly purified form. The isoelectric point of the protein was 5.2. The apparent molecular weight was estimated to be 33 000 by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate and urea, and 34 000 by gel filtration column chromatography with Sephadex G-100. The protein was provisionally named '33 kilodalton protein' according to the molecular weight. The absorption spectrum of the protein did not show any absorption band in the visible region. No histidine was found in the amino acid analysis of the protein. The 33 kilodalton protein was released from the thylakoid membrane by EDTA-treatment and also by sonic oscillation. The protein was bound to System II particles, but not to System I particles.

Amino Acids↗
PubMed1979

Ocular manifestations of familial high-density lipoprotein deficiency (Tangier disease).

Corneal clouding is one of the manifestations of Tangier disease, an inherited disorder in which cholesterol-rich lipids are deposited in various tissues of the body. The cause of the corneal clouding is unknown. This study documents the clinical course and conjunctival biopsy findings of a 60-year-old man who was one of the earliest patients to be recognized with Tangier disease and in whom progressive corneal clouding developed in adult life. Noteworthy in the biopsy specimens were birefringent lipid particles that were predominantly present in degenerating pericytes of the conjunctival vessels.

Arteries↗
PubMed1979

Structural and biochemical changes in vitamin A--deficient rat retinas.

The levels of rhodopsin and opsin were investigated in relation to the maintenance of retinal structure in retinas of vitamin A--deficient rats in low levels of cyclic illumination (1.5 to 2 foot-candles). Rhodopsin levels decreased in the deficient retinas to approximately 20% of control at 9 weeks, and this level was retained through 39 weeks on the deficient diet. Opsin levels decreased at a slower rate but reached about 20% of control levels at 32 weeks. Despite the decrease in rhodopsin levels, obvious deterioration of disc structure was not observed until 16 weeks of deficiency, when opsin levels had already decreased to 60% to 70% of control. The structural disruption of photoreceptor outer segments was localized initially in discs of the distal third. Rod cell degeneration preceded cone cell degeneration in vitamin A--deficient retinas. Most of the rods and cones persisted in the posterior retina at 23 weeks on the deficient diet; however, by 40 weeks, only 11% of the rod nuclei remained. In contrast, about 63% of the cone nuclei were present at 40 weeks of deficiency. The photoreceptor cells were affected by the deficiency to a greater extent in the inferior hemisphere than in the superior hemisphere of the eye.

Animals↗
PubMed1979

Vitamin E deficiency and the retina: photoreceptor and pigment epithelial changes.

To investigate the role of normal vitamin E levels and the interrelationships between vitamin E and A in maintaining the visual cells of the retina, weanling female Sprague-Dawley rats were fed vitamin E-free diets differing tenfold in their vitamin A content (0.8 and 8.0 mg of retinol per kilogram of diet). Rats on vitamin E-free diets with the higher vitamin A level exhibited marked disruption of photoreceptor outer segment membranes and a fivefold increase in the number of lipofuscin granules in the pigment epithelial cells which ingest these membranes. Rats on vitamin E-free diets with the lower vitamin A level showed the same retinal damages plus significant loss of photoreceptor cells compared to age-matched rats on control diets. Rods and cones were involved equally, and their pattern of loss was not like that found in vitamin A deficiency. Normal levels of vitamin E probably protect photoreceptor membranes from oxidative damage and retard the accumulation of their remnants and other products of lipid breakdown in the pigment epithelium. The vitamin A status of rats has a significant influence on the extent of damage induced by vitamin E deficiency.

Animals↗
PubMed1979

[On the phenomena of multiple extravasations of contrast medium in cerebral angiogram of the cases of hypertensive intracerebral hematoma (author's transl)].

It is interesting to note the pathological findings that the rupture of multiple microaneurysms in the basal ganglia appears to be the cause of the hypertensive intracerebral hematoma. But there is few report that the carotid angiogram demonstrated multiple leakages of contrast medium of intracerebral hematoma in vivo than in Westberg's postmortem angiogram. The authors experienced 15 cases of hypertensive intracerebral hematoma whose cerebral angiogram showed extravasation of contrast material. It was fifty-seven per cent of which angiogram within 6 hours after the stroke showed leakage of contrast medium. However, there was remarkably decreased appearance of the extravasation after 9 hours after the stroke. Moreover, emphasis showed be placed upon the facts that eleven cases of 15 cases showed more than two adjacent spotty extravasations of contrast medium and that six cases demonstrated the simultaneous multiple leakages of contrast material from more than two lentriculostriate arteries. These angiographic findings has led us to the conclusion that there is intimate correlation between the large hematoma and multiple ruptures of the microaneurysms of lentriculostriate arteries.

Adult↗
PubMed1978

Ocular cryptococcosis.

We studied ocular cryptococcosis in a 59-year-old man who had received extensive chemotherapy for abdominal malignant lymphoma. Mucinous lesions containing abundant cryptococci, but no inflammatory cells, formed in the posterior choroid of the eye. Electron microscopy revealed that mucin, a filamentous substance, coated the encapsulated organisms. Except for a few degenerating ones in histiocytes, most cryptococci appeared in the extracellular space.

Antineoplastic Agents↗
PubMed1978

[Unilateral exophthalmos caused by organized hematoma of the orbit--report of a case (author's transl)].

The authors reported a case with unilateral proptosis of over ten years' duration due to organized hematoma of the orbit. It has generally been accepted that any given hemorrhage within the orbit can be resolved in a relatively short period of time. Persistent intraorbital hematoma, therefore, in the form of organized hematoma is very unusual in incidence and has been reported very few in the literature. Our patient presented himself with a ten-and-several-year history of unilateral exophthalmos, limited ocular movement and decreased visual acuity on the involved side. There was no specific symptom when compared with the other intraorbital tumors. Total resection of the tumor was performed through transcranial frontozygomatic approach. Histopathologic examination revealed evidence of organized hematoma without definite sources of bleeding such as microangioma, microaneurysm or arteriovenous malformation. Retrospective review of history failed to uncover episodes of hemorrhagic tendency or direct trauma to the head or the orbit. Subsequently a diagnosis of spontaneous organized hematoma was made. Great emphasis was laid on the fact that CT-scan was one of the most useful diagnostic tools. Our surgical approach was introduced and discussed.

Adult↗
PubMed1978

A new, albino-beige mouse: giant granules in retinal pigment epithelium.

Albino-beige mice were produced in order to combine two experimentally useful characteristics, albinism and lysosomal dysfunction, in the same animal. The retinal pigment epithelium of albino-beige mice formed giant intracellular granules. Exposure of albino-beige mice to white light of 150 foot-candles for 3 to 10 hr induced marked phagocytosis of rod outer segment fragments by the retinal pigment epithelium, resulting in intracellular accumulations of undigested disk membranes within the giant granules. Additional, incompletely processed membranes accumulated as the mice aged or were exposed to 150 foot-candle light for longer periods. Such accumulations of ingested membranes were not observed in the pigment epithelium of exposed or aging albino mice heterozygous for the beige gene. Because of its altered processing of ingested outer segment membranes, this new albino mouse should be useful for studying the possible roles of the retinal pigment epithelium in the maintenance of photoreceptor cells and in their recovery from light damage and other insults.

Animals↗