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Biomedical subjects

G Krohel

Publications and source records attributed to G Krohel.

6 recordsLinked to original sources
PubMed1986

Qualitative and quantitative ultrastructural observations on retinal ganglion cell layer of rat after intraorbital optic nerve crush.

Rat retinal ganglion cell layer (GCL) was examined ultrastructurally 1-180 days after intraorbital crushing of one optic nerve. It was confirmed quantitatively that axotomized ganglion cells lost cisternal membranes of the rough endoplasmic reticulum (RER) and showed disintegration of Nissl bodies and ribosomal rosettes 3 days postoperatively. Between 60 and 180 days after neurotomy there was partial reversion of the RER towards normal. At postoperative intervals of 14-60 days, chromatin aggregation became conspicuous and some nuclei were prominently furrowed and contained electron-dense inclusions. Concurrently, profiles of dead ganglion cells were encountered. Mean mitochondrial area increased in axotomized neurons but mitochondrial density declined, while the Golgi apparatus, lamellar specializations of the RER and the size of nuclei did not change significantly. Cytoplasmic atrophy was profound, however. Small nerve cells of the GCL appeared morphologically distinct from ganglion cells and did not undergo appreciable alteration. A decline in neuronal density, approximating 35%, occurred between the third and seventh postoperative day and progressed slowly thereafter. Neuronal density was 32% of normal 180 days postoperatively. A temporary increase in glial density 3-28 days after operation was due to microglial hyperplasia. Müller cell and astrocytic processes hypertrophied, infiltrated nerve fibre bundles, and surrounded and intruded into neuronal somata. Bundles of unmyelinated small axons, invested by astrocytes and basal lamina, were present within the necrotic cavity of the lesioned nerve 28-90 days postoperatively and had cytologic features of regenerative axonal sprouts. We conclude that intraorbital optic nerve crush is followed by a noteworthy degree of regenerative axonal sprouting which occurs and persists against a background of slow but relentless decline in the retinal ganglion cell population. This slow decline follows a rapidly-sustained loss of approximately one-third of the axotomized retinal ganglion cells during the first postoperative week. Intraorbital, as opposed to intracranial, injury of the optic nerve appears, paradoxically, to induce both a greater degree of ganglion cell death and a greater amount of regenerative axonal sprouting. Cytologic changes in axotomized retinal ganglion cells resemble those described for other populations of mammalian intrinsic neurons subjected to like injury.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1986

The spectrum of neurologic disorder from vitamin E deficiency.

We describe nine patients with fat malabsorption in whom a spectrum of vitamin E deficiency was present. Early deficiency was generally asymptomatic, and intermediate deficiency produced some impairment. Ataxia, weakness, reflex changes, impaired vision, and pigment retinopathy were associated with chronic, advanced deficiency. In the last group, delayed central somatosensory conduction and amplitude reduction of the electroretinogram were present. In adults, a severe vitamin E deficiency state existed for more than 5 years before producing measurable neurologic damage. The clinical picture is less homogeneous than previously suggested, and electrophysiologic abnormalities need not predate clinical dysfunction.

Adult↗
PubMed1982

Hydroxychloroquine. Seven-year experience.

Ninety-nine patients were treated with hydroxychloroquine sulfate for connective tissue diseases during a seven year period. All patients received the medication for at least one year and most were treated with a daily dosage of 400 mg. Four patients experienced toxic effects, but no patient sustained permanent loss of visual acuity. Toxicity did not seem to represent a cumulative dosage effect. Funduscopic and visual field examinations at six-month intervals are sufficient to detect the occasional adverse reactions and prevent serious retinal toxic effects when a maximum daily dosage of 400 mg is maintained.

Adult↗
PubMed1979

Ophthalmologic safety of long-term hydroxychloroquine treatment.

Ocular toxicity of long-term hydroxychloroquine treatment was assessed by regular ophthalmologic examinations in 99 patients. No patient developed significant loss of vision or visual field constriction to a white test object. Three patients had evidence of toxicity, but the medication had to be permanently discontinued in only one who subsequently had regression of all abnormalities except visual field constriction to a red test object. Neither duration of treatment nor the diagnosis of systemic lupus erythematosus predisposed patients to toxicity.

Accommodation, Ocular↗
PubMed1979

Voluntary vertical nystagmus.

A patient with hypertropia caused by fourth-nerve palsy manifested primary position oscillations characteristic of voluntary nystagmus. This benign condition must be kept in mind even when dealing with primary position vertical nystagmus to avoid extensive and potentially dangerous investigations.

Adult↗