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Biomedical subjects

T Kuwabara

Publications and source records attributed to T Kuwabara.

At least 325 records · Page 18Linked to original sources

Axoplasmic flow during chronic experimental glaucoma. 1. Light and electron microscopic studies of the monkey optic nervehead during development of glaucomatous cupping.

The anterior optic nerve and the macular region of the retina of glaucomatous eyes of five rhesus monkeys (Macaca mulatta) have been examined by light and electron microscopy. The experimental glaucoma had been induced by argon laser treatment of the anterior chamber angle. The eyes were examined 3 to 11 weeks after the onset of sustained elevation of intraocular pressure above 20 mm Hg. Severe degenerative changes were seen in eyes with higher intraocular pressure and longer duration of glaucoma. Eyes with a lesser elevation of intraocular pressure and shorter duration of glaucoma showed changes sharply localized to the axon bundles in the scleral lamina cribrosa. Accumulation of mitochondria and dense bodies occurred anterior and posterior to collagenous septae. The location of these changes is in agreement with the localization of block of axoplasmic transport identified by autoradiographic studies. It is speculated that these cytologic changes reflect blockage of axoplasmic flow in the optic nerve of eyes with glaucoma.

Animals↗

Progressive bilateral essential iris atrophy.

Bilateral progressive essential iris atrophy, more advanced in one eye than in the other, occurred in a 24-year-old white man. Histopathologic examination of the iris from the eye with the more advanced iris atrophy disclosed no vascular abnormalities in that the vessels were patent and appeared normal except for accumulated perivascular connective tissue. Fluorescein angiographic examination of the fellow eye that was undergoing the earliest changes of iris atrophy failed to reveal any vascular abnormalities. However, tonographic examination indicated a markedly decreased outflow facility. There does not appear to be any vascular abnormality involved in the pathogenesis.

Adult↗

Papilledema.

Explore the source record for details and available documents.

Humans↗

[Simplfied technique of lumbar subarachnoid-peritoneal shunt (author's transl)].

The authors have developed a simplified technique of lumbar subarachnoid peritoneal shunt in which the spinal tube is easily introduced through a puncture needle without doing a laminectomy. Seventeen cases of communicating hydrocephalus of various orgin have been treated by this procedure. In this paper, we reported our shunting system and the technique of precedures, and discussed the clinical results and some advantages of this method. The spinal tube is a custom made Silastic tube with small side holes 2 mm apart from each other at slanting tip located within the first 1.0 cm of the end. French No. 5 tube is available for older children and for adults, and French No. 3.6 tube for infants. Total length of the tube measures 30 cm with 4 black markers at 5 cm intervals from the tip for assisting in positioning. The puncture needle is a modified Touhey needle. Two needles different in size are prepared according to the size of the tube. Outer diameter of these needles is 2.1 mn & 1.8 mn. Our operative procedures are divided into following three steps. 1) Puncture of the lumbar subarachnoid space and insertion of the spinal tube through the needle. 2) Introduction and placement of the peritoneal tube into some point of the peritoneal cavity. Concerning to this point, we have the three candidates, namely into the Douglas pouch, the suprahepatic space, and the bursa omental cavity. 3) Connection of the spinal tube and the peritoneal catheter end. We used a kind of flushing device only in some exceptional cases, and recently, we feel that it is not so necessary for this shunting. We have employed this technique in a total of 17 cases. Eleven cases of them are adults and the other 6 cases are children less than 2 years of age. Postoperative follow up period varied from 13 months to 1 month, and all the cases except two had good result, suggesting the shunt system is working well with no evidence of complications such as low pressure syndrome or radicular irritation. Some troubles occurred in two children. One was a disconnection between the spinal and the peritoneal tube, and the other was an obstruction at the peritoneal tube end. The authors believe that our L-P shunt has several advantages as listed below, 1)Procedure is very simple, in other words, there is no need of laminectomy. 2) The entire system is short. 3) No need to pass the catheter into the brain tissue. 4) Obstruction of the spinal catheter end is very unusual. 5) Alteration of communicating hydrocepalus into non communicating one by secondary obstruction of aqueduct of Sylvius is less likely with this shunting system. 6) Siphon effect might be minimal, if present. 7) As compared to V-A shunt, severe complication like septicemia will not occur in the L-P shunt. With this simple method and good material, we hope that this L-P shunt is employed more widely for the patients with communicating hydrocephalus.

Cerebrospinal Fluid Shunts↗

Vitamin A storage and peroxisomes in retinal pigment epithelium and liver.

Retinas and livers were studied with histochemical methods for catalase combined with light and electron microscopy, following intramuscular injections of C57 black mice with retinyl acetate or retinyl palmitate in total doses of 0.9 to 6.7 X 10(6) I.U./kg. body weight. There were clear, dose-related increases in the numbers and sizes of vitamin A--storing lipid droplets in the stellate cells of the liver. Concomitantly, more conservative increases in similar lipid droplets occurred in the pigment epithelium but not in other cells of the retina. Such lipid droplets may represent physiological sites of vitamin A storage which are important for the maintenance of photoreceptor cells by the retinal pigment epithelium. No changes in lipids of the retina or liver were observed in mice injected with retinoic acid or with peanut oil. Both peroxisomes containing catalase and the putative vitamin A--storing lipid droplets were distributed along the basal and lateral cell surfaces of the pigment epithelium where receptors for plasma retinol-binding protein have been reported. Peroxisomes may play a role in the reactions related to the esterification and sequestering of vitamin A.

Animals↗

The pigment epithelium of the monkey. Topographic study by scanning and transmission electron microscopy.

The pigment epithelium of the normal monkey was studied by scanning and transmission electron microscopy. Appearance of microvilli of the cell are demonstrated and compared topographically. The apical surface of the pigment epithelium consists of densely distributed fine microvilli. No thick portion of the villi or the cell borders are seen in normal conditions. The attachment of the epithelium and the outer segment is extremely firm and breakage of the microvilli or outer segments occurs easily in the attempt to separate these two layers.

Animals↗

The Richner-Hanhart syndrome: report of a case with associated tyrosinemia.

The Richner-Hanhart syndrome with tyrosinemia was recognized in a mentally retarded adolescent boy. The clinical manifestations, including hyperkeratosis of the volar aspects of the hands and feet, thickening of the conjunctival epithelium, and corneal opacities, as well as biochemical aberrations of tyrosine metabolism, responded to specific treatment with a diet low in phenylalanine and tyrosine. Light and electron microscopical studies illustrate the underlying conjunctival pathologic changes.

Adolescent↗

Light damage in the developing rat retina.

The effect of bright light on the retinas of developing albino rats was studied electron microscopically. The newly formed outer-segment lamellar membranes of newborn rats raised in continuous bright light appear to be less sensitive to the damaging effects of light, compared to those of rats raised under normal light conditions for at least two weeks. It seems to take about two days before the membranes show damage from continuous exposure to fluorescent lamps. The same brightness damages the adult outer segments within a few hours. Despite the severe damage to the outer segments, the rest of the retina develops normally for one month, and then the photoreceptor cells undergo degeneration. The retinas that have been exposed to bright light for two weeks after birth show considerable damage, but these retinas regenerate in six months.

Animals↗

Electron microscopic study of extraocular muscles in myotonic dystrophy.

The extraocular muscles of two middle-aged men with ophthalmoplegia secondary to myotonic dystrophy were studied by electron microscopy. The main change was disorganization in the arrangement of myofibrils rather than degeneration of the cells. Diseased muscle cells contained randomly distributed, short and irregular myofibrils and individual myofilaments. The cytologic appearance of these muscle cells was similar to that of developing muscle cells. The pathogenesis of the myopathy in myotonic dystrophy may be related to myofibrillogenesis and its maintenance.

Humans↗

Adrenoleukodystrophy with disease of the eye and optic nerve.

Adrenoleukodystrophy is an X-chromosome-linked recessive disease characterized by primary atrophy of the adrenal glands with or without Addison's disease and low plasma cortisol levels, and a degeneration of white matter of the central nervous system with blindness. In suspected cases of adrenoleukodystrophy an impaired rise in plasma cortisol levels after adrenocorticotrophin stimulation may be diagnostic. With the electron microscope, pathognomonic intracytoplasmic lamellar inclusions have been seen in adrenal cortical cells, peripheral nerve Schwann's cells, testicular interstitial cells, and in macrophages of the brain. Adrenoleukodystrophy appears to be a genetically determined lipid storage disease with an error in membrane sterol metabolism. A 10-year-old boy with adrenoleukodystrophy had visual loss, a prominent early symptom. The ocular abnormality consisted of a disproportionate loss of nerve fibers from the macular region. No intracytoplasmic lamellar inclusions were identified in cells representing macrophages within the optic nerve. They contained myelin debris suggestive of end-stage disease.

Adrenal Gland Diseases↗

Optic neuropathy presumably caused by vincristine therapy.

A 36-year-old man with Hodgkin's disease developed symmetric optic neuropathy after treatment with nitrogen mustard, vincristine, procarbazine, and prednisone. Histopathologic sections of the eyes showed loss of ganglion cells in the macular region and atrophy of the corresponding fibers in the optic nerve. Vincristine is presumed to have been the cause of the optic neuropathy because of its recognized neurotoxicity and its temporal relation to the onset of the visual complaint.

Adult↗