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Biomedical subjects

W H Stern

Publications and source records attributed to W H Stern.

54 records · Page 3Linked to original sources
PubMed1981

Anatomical recovery following retinal detachment: clinicopathological correlations.

The histological findings in experimental retinal detachment and reattachment of the cat retina are described. Loss of photoreceptor outer segments, mounding of the apical surface of the retinal pigment epithelium, and loss of the apical villi of the retinal pigment epithelium are prominent features of the detached cat retina. Reattachment within the first week of retinal detachment is followed by good photoreceptor regeneration and orientation. Longer term detachment of 2 to 6 weeks results in poorer photoreceptor outer segment regeneration and orientation 4 weeks following reattachment surgery. These experimental results are consistent with clinical data concerning visual recovery following retinal reattachment surgery.

Animals↗
PubMed1981

The onset of pigment epithelial proliferation after retinal detachment.

The adult mammalian retinal pigment epithelium (RPE) is mitotically inactive, yet retains the capacity to proliferate under certain conditions. To determine the onset of RPE proliferation after retinal detachment, we examined experimentally detached cat retinas of 12, 24, 48, and 72 hr duration. An additional animal served as a nondetached, sham-operated control. 3H-thymidine was injected into the vitreous chamber and the eyes were processed for light microscopic autoradiography. Autoradiograms from both the control and the 12 hr detachment showed no evidence of labeled RPE nuclei; however, labeled nuclei were present at both 24 and 48 hr after detachment. Labeled nuclei per millimeter of RPE at 24 hr were 55% of the 48 hr rate. Mitotic figures were noted only at 48 and 72 hr after detachment. No labeled RPE nuclei appeared in autoradiograms that bordered the detachment zone. Electron micrographs showed that proliferating RPE cells assume several configurations, some of which have been reported in other species. The proliferative response of the RPE occurs much sooner than had previously been thought. It appears to be a local effect that does not involve retinal regions beyond the detachment boundaries, and it may have potentially adverse effects when the retina and RPE are reapposed after retinal reattachment surgery.

Animals↗
PubMed1980

An integrated approach to vitrectomy instrumentation.

I devised a vitrectomy instrument integrating tray for a variety of vitrectomy systems. The tray controls the infusion and suction instrumentation through pinch valves, provides pathways for fiberoptic, diathermy and electrical cords, and provides silicone moldings for holding the various instruments used in vitrectomy surgery.

Electrosurgery↗
PubMed1980

Interrelationships between the retinal pigment epithelium and the neurosensory retina.

The role of the retinal pigment epithelium in regulating transport between the choriocapillariss and sensory retina was studied by examining the diffusion fluorescent across the intact rabbit retinal pigment epithelium and the retinal pigment epithelium damaged by intravenous injection of sodium iodate. Destruction of the tight junctions of the retinal pigment epithelium allowed free diffusion of fluorescein from the choroid into the retina. The electrical characteristics of the cat retinal pigment epithelium which play an important role in governing transport of substances across the retinal pigment epithelium were studied. The apical membrane of the cat retinal pigment epithelium resembled that of the frog in having high sensitivity to apical K+, greater sensitivity to apical Na+, and less sensitivity to apical HCO3-. The apical membrane was sensitive to oubain which produced a rapid fall in the transepithelial potential. Previous studies of the electrical properties of the retinal epithelium in cold blooded preparations are summarized with emphasis on the important interactions between the retinal pigment epithelium and sensory retina and the implications that these studies have with regard to the regulation of photoreceptor function.

Animals↗
PubMed1979

Radial buckling of posterior retinal tears.

We devised a method for safely placing mattress sutures for radial scleral buckling of posterior retinal holes. The ability to pass the needle in the anteroposterior direction, as well as the ability to tie the posterior ends of the mattress suture anteriorly where they are easily accessible, makes this method of placing the mattress suture safe and effective for posterior radial buckles.

Humans↗
PubMed1979

Blepharochalasis.

The condition of blepharochalasis and its treatment are discussed. Four cases are presented which show a physical sign that may help in its diagnosis.

Adolescent↗
PubMed1979

Vitrectomy instrumentation for surgical evacuation of total anterior chamber hyphema and control of recurrent anterior chamber hemorrhage.

A patient with recurrent bleeding during hyphema extraction with the O'Malley ocutome was treated by elevation of the intraocular pressure to 50 mm Hg for 5 minutes with fluid from the infusing needle. When intraocular pressure was returned to normal, there was cessation of bleeding and postoperatively the anterior chamber remained free of blood. Elevation of intraocular pressure is offered as an initial alternative to air injection or cyclodiathermy for control of bleeding during hyphema extraction.

Child↗
PubMed1978

Initial observations on the isolated retinal pigment epithelium-choroid of the cat.

An in vitro preparation of a mammalian retinal pigment epithelium (RPE)-choroid was developed, that of the cat, in order to study the RPE in isolation from the neural retina. The purpose of these initial experiments was to evaluate the electrical characteristics of the tissue and the ionic properties of the RPE apical membrane. They were designed so that results would be directly comparable to those previously obtained on a more extensively studied cold-blooded preparation, the bullfrog. The electrical characteristics of the best cat tissues were similar to those routinely obtained in bullfrog, whereas the average cat apical membrane potential was 20 mV more depolarized than that of frog. The apical membrane of cat resembled the frog's in having a large sensitivity to potassium, but it had a relatively smaller sensitivity to bicarbonate and a relatively larger sensitivity to sodium. The cat, like the frog, also had a ouabain-sensitive mechanism on its apical membrane that directly contributed to membrane potential. Two factors contributing to the lower apical membrane potential in cat were the higher potassium concentration of the mammalian salt solution and the sodium conductance of the apical membrane.

Animals↗
PubMed1977

Listeria monocytogenes endophthalmitis.

A 62-year-old white man developed an acute anterior chamber inflammation in his left eye. Listeria monocytogenes was cultured from the vitreous aspirate. There was no evidence for ocular trauma or distant site of infection from which hematogenous spread of the organism occurred. No underlying state of immunocompromise was demonstrated. The endophthalmitis responded well to therapy.

Anterior Chamber↗
PubMed1977

The effect of mannitol infusion on retinal function and oxygen tension.

Mannitol administered intravenously in rhesus monkeys resulted in a temporary recovery of the visual evoked response (VER) after its decrease due to elevation of the intraocular pressure. Mannitol infusion caused an immediate, albeit transitory, increase in retinal oxygen tension. These changes were independent of the ocular hypotensive effect of mannitol, and we conclude that the drug is a far better agent for the treatment of acute glaucoma than heretofore believed.

Animals↗
PubMed1976

Submacular choroidal circulation.

A neoprene latex and pigment mixture was injected into the choroidal blood vessels of human cadaver eyes. When peripheral resistence was normal, a single arteriole filled a single lobule of the choriocapillaris drained by mulitple surrounding venules. The choridal veins interconnected and an increase in the peripheral resistance caused by elevation of the venous pressure resulted in filling of contiguous lobules in a retrograde manner through the venules that normally drain them.

Aged↗
PubMed1975

Intracranial ophthalmic artery aneurysm.

A 45-year old black man with a carotid-ophthalmic artery aneurysm developed sudden loss of vision in his left eye, a mid-dilated pupil, and pain on movement of the left eye. A temporal island of vision was present in the left eye and the right visual field was normal. There were no other neurologic abnormalities. The aneurysm spontaneously ruptured, resulting in the death of the patient.

Blindness↗
PubMedDate not supplied

Relationship of muscle capillary basement membrane thickness and diabetic retinopathy.

We examined the relationship between the thickness of the quadriceps muscle capillary basement membrane and diabetic retinopathy. Basement membrane thickness was measured in two groups of patients with long-standing type II diabetes mellitus. One group of patients (N = 13) had no evidence of diabetic retinopathy on fluorescein angiography, whereas the other (N = 12) had proliferative microvascular disease. All the patients were male, and both groups were of similar ages, duration of diabetes, serum creatinines, and glycemic control as reflected by HbA1 levels. Mean muscle capillary basement membrane width (+/- SE) of the patients with proliferative retinopathy (3346 +/- 262) was significantly greater (P less than .05) than that observed in the patients without retinopathy (2660 +/- 177). The results of this study suggest that there is a relationship between capillary basement membrane thickness in skeletal muscle and the severity of microangiopathy in the eye. However, there was a substantial overlap between the two groups, indicating that for any individual patient the measurement of muscle capillary basement width will probably not be useful in identifying the presence or absence of retinopathy.

Aged↗