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Biomedical subjects

D S Hull

Publications and source records attributed to D S Hull.

At least 37 records · Page 2Linked to original sources
PubMed1986

BSS and BSS-plus: effect on corneal endothelial ionic and non-ionic fluxes.

Rabbit corneas were mounted in water jacketed chambers and the endothelial surface perfused with either BSS (Balanced Salt Solution) or BSS-Plus for 3 hr. Unidirectional and net fluxes of sodium were similar in both groups of corneas. Bicarbonate fluxes in BSS-Plus were statistically similar to those in Krebs-Ringer solution. Bicarbonate fluxes could not be determined with BSS because the solution does not contain bicarbonate. In addition, there was no statistically significant alteration of inulin or dextran permeability when comparing perfusion with BSS and BSS-Plus. From this study it appears that BSS and BSS-Plus are comparable in their ability to maintain corneal endothelial physiologic function during in-vitro perfusion. This is in contrast to previous work which showed that BSS-Plus induced less endothelial morphologic change than BSS. It is concluded that morphologic alterations may be more sensitive parameters of endothelial stress than are fluxes and permeabilities.

Acetates↗
PubMed1986

Effect of ambient pH on corneal endothelial sodium fluxes.

Sodium fluxes across the isolated rabbit corneal endothelium were measured as a function of ambient pH and bicarbonate concentrations. At pH 7, the net sodium flux (J endo str net) was effectively obliterated at all bicarbonate concentrations, relative to controls at pH 7.5. At pH 8, the net sodium flux was obliterated at 5 mM bicarbonate, was unchanged at 25 mM bicarbonate, and was enhanced at 40 mM bicarbonate, relative to controls at pH 7.5. The decrease in net sodium flux under these conditions relative to previously demonstrated maintenance of bicarbonate fluxes under almost identical conditions suggest that sodium and bicarbonate transverse the endothelium by different routes. In addition, changes in unidirectional fluxes, when ambient pH is decreased from 7.5 to 7, are not equal, illustrating that the fluxes probably occur via different pathways. A complex interrelationship exists between sodium, bicarbonate, and proton movement.

Animals↗
PubMed1985

Corneal endothelium following immersion of eyes in water.

Eye banks are occasionally asked to retrieve corneal tissue from drowning victims. The ambient water surrounding the eyes before recovery of the victim has chemical, pH, and osmotic characteristics different from those of aqueous humor, thereby possibly making corneas recovered from these eyes unsuitable for transplantation. Corneal endothelial cell function and ultrastructure were maintained following soaking of rabbit eyes for three hours in either seawater, fresh lake water, or chlorinated swimming-pool water at 25 degrees C. The data suggest that physiological and ultrastructural integrity of the corneal endothelium is maintained under these conditions, and that if other, generally accepted criteria of donor suitability are met, such corneas are probably suitable for transplantation.

Animals↗
PubMed1985

Effect of oxygen free radical products on rabbit iris vascular permeability.

Oxygen free radicals and their products are known to be elaborated by inflammatory cells during the 'respiratory burst'. Xanthine oxidase combined with hypoxanthine was injected into the anterior chamber of rabbit eyes. This combination is known to result in the production of oxygen free radicals. Iris fluorescein angiography performed 2 h and 24 h following injection of xanthine oxidase and hypoxanthine into the anterior chamber resulted in increased iris vascular permeability. The increased permeability was not modified by either of the prostaglandin inhibitors naproxen or aspirin nor by the free radical scavenger D-penicillamine. This study demonstrates that iris vascular permeability, and possibly blood-aqueous barrier permeability is increased following exposure to chemically generated oxygen free radicals. It is possible that the increased iris vascular permeability that occurs during ocular inflammatory processes may in part be mediated by oxygen free radical products. This model may be useful in developing therapeutic modalities directed at preventing the damaging effect of oxygen free radical products, and this may be of benefit in reducing the untoward effects of ocular inflammatory disorders.

Animals↗
PubMed1985

Effect of hematoporphyrin derivative on rabbit corneal endothelial cell function and ultrastructure.

Hematoporphyrin derivative (HpD) is a systemically administered photosensitizing agent that may be of value in the treatment of solid tumors. When corneal endothelial cells were perfused in the specular microscope with HpD and exposed to a 25-W incandescent light at 5 cm (5.5 mW/cm2) there was anatomic disruption of corneal endothelial cells and swelling of the corneal stroma. Perfusion with 0.2 microliter/ml (1.0 microgram/ml) HpD and 5 min exposure to light resulted in a corneal swelling of 71 +/- 4 microns after 3 hr, whereas perfusion with 0.2 microliter/ml HpD and a 1-min exposure to light resulted in a corneal swelling of 36 +/- 4 microns after 3 hr. Perfusion with 0.2 microliter/ml HpD with no light exposure resulted in a corneal swelling of 22 +/- 4 microns after 3 hr. Inclusion of 100 micrograms/ml catalase in the perfusion solution resulted in a significant 38% reduction of the corneal swelling. The inclusion of either 100 micrograms/ml superoxide dismutase, 15 mM D-mannitol, 5 mM ascorbic acid, 1/4% DMSO, 50 microns EDTA, 50 microns DETAPAC, 10 mM L-histidine, or 1 mM sodium azide did not modify the corneal swelling induced by the photosensitization reaction. Perfusion of corneal endothelial cells with 2 microliters/ml (10 micrograms/ml) HpD and exposure to 25-W incandescent light for 5 min resulted in swelling of mitochondria, the appearance of vacuoles in the cytoplasm, and rapid corneal swelling. The data suggests that corneal endothelial cells can be damaged by hydrogen peroxide generated by the dismutation of superoxide anion produced during the photoreaction. Superoxide anion itself and hydroxyl-free radical do not appear to participate in causing the endothelial cell damage. The role of singlet oxygen remains somewhat unclear. The data suggests that further in vivo studies should be performed to delineate precautions that should be taken to protect the corneal endothelium during photoradiation therapy.

Animals↗
PubMed1984

Effect of HEPES buffer on corneal storage in MK medium.

Rabbit corneas were stored for 7 days in either MK medium containing gentamicin or modified MK medium containing HEPES buffer, gentamicin and phenol red. Corneas stored for 7 days in modified MK medium were thicker than corneas stored in MK medium. Corneal endothelial permeability to inulin and dextran was similar following 7 days of storage in either solution. Transmission electron microscopy of corneal endothelial cells stored in either solution showed intact cell membranes and organelles. In vitro perfusion of rabbit corneas in the specular microscope with Krebs Ringer bicarbonate containing HEPES buffer swelled at 17 +/- 1 micron/h, whereas those perfused with Krebs Ringer bicarbonate alone swelled at 7 +/- micron/h. Perfusion with Krebs Ringer bicarbonate containing phenol red did not result in an increased corneal swelling rate. The work indicates that HEPES buffer has an adverse effect on corneal endothelial pumping function, and this results in corneal swelling during storage as well as during perfusion in the specular microscope. The adverse effect appears to be, at least in part, transient: however, the ultimate, long term effect of HEPES buffer on corneas stored prior to penetrating keratoplasty is not known and deserves continued investigation.

Animals↗
PubMed1984

Potassium superoxide induction of rabbit corneal endothelial cell damage.

Rabbit corneal endothelial cells were perfused with a Krebs Ringer bicarbonate solution to which potassium superoxide had been added. Concentrations of potassium superoxide of 0.5 mM and higher resulted in severe anatomic and physiologic alteration of endothelial cells that resulted in corneal swelling. Catalase offered protection whereas the toxic effect was unaltered by superoxide dismutase, ascorbic acid, DETAPAC, EDTA, EDTA-FeC1(20, or DMSO. The data suggests that hydrogen peroxide is the toxic species and that superoxide anion and hydroxyl free radical are either not toxic in this system or are at such low concentrations that cell damage does not occur. The role of singlet oxygen cannot be defined, but its participation appears unlikely. Endothelial intracellular glutathione levels and redox state were unaffected by perfusion with a solution to which 0.3 mM potassium superoxide had been added.

Animals↗
PubMed1984

Cornea endothelial rose bengal photosensitization. Effect on permeability, sodium flux, and ultrastructure.

Rabbit corneal endothelial cells demonstrated an increase of endothelial membrane permeability to inulin following perfusion with 5 X 10(-6) M rose bengal and exposure to 1050 muW/cm2 incandescent light for either 1 min or 5 min when compared to corneas similarly perfused with rose bengal but not exposed to light. Endothelial permeability to dextran was unaltered following the photosensitization reaction. Rose bengal perfusion in the absence of light caused an increase in the unidirectional sodium fluxes (J stroma endothelium and J endothelium stroma); however, a net sodium flux was still present and directed from the stroma to the endothelium. Exposure of rose bengal perfused endothelial cells to incandescent light resulted in a further increase in the unidirectional passive sodium flux in both directions and a reduction in the active component of the sodium flux from stroma to endothelium. This caused a reduction in the net active transport of sodium across the endothelium following the photosensitization reaction. Transmission electron microscopy showed no alteration of endothelial cell ultrastructural integrity following rose bengal perfusion in the absence of light. However, rose bengal perfusion accompanied by exposure to 1050 muW/cm2 incandescent light caused swelling of endoplasmic reticulum and mitochondria. The data indicate that rose bengal photosensitization has an adverse effect on endothelial cell energy production as well as transport and barrier function.

Animals↗
PubMed1984

Hydrogen peroxide-mediated corneal endothelial damage. Induction by oxygen free radical.

Polymorphonuclear leukocytes and other inflammatory cells release superoxide anion and additional oxidant species following stimulation. Corneal endothelial cells were exposed to a flux of chemically generated superoxide anion (oxygen-free radical) produced by the combination of 1 mM hypoxanthine and 0.06 U/ml xanthine oxidase. Exposure of endothelial cells to the combination of hypoxanthine and xanthine oxidase resulted in anatomic disruption of the cells with interference in the function of endothelial water movement and resultant swelling of the corneal stroma. Catalase reduced the corneal swelling caused by exposure of endothelium to the oxygen-free radical generating system, whereas superoxide dismutase, ascorbic acid, D-mannitol, and ethanol did not prevent damage. The data suggest that hydrogen peroxide produced during the dismutation reaction of the superoxide anion is one of the toxic species, whereas the superoxide anion itself and the hydroxyl-free radical probably do not participate. The data suggest that corneal endothelial cells are susceptible to physiologic and anatomic damage induced by the products of reactive oxygen species, which, from previous studies, are known to be generated by inflammatory cells. The development of therapeutic modalities directed at the prevention of damage produced by hydrogen peroxide and other oxidant species may be of benefit in reducing corneal endothelial cell damage secondary to ocular inflammatory disease processes.

Animals↗
PubMed1983

Radial keratotomy. Effect on cornea and aqueous humor physiology in the rabbit.

Radial keratotomy may cause anatomical damage to the rabbit corneal endothelium. To determine if physiological and functional alterations occur, radial keratotomy was performed on rabbit corneas using eight incisions with sparing of a 3.5-mm central pupillary area. Cornea endothelial membrane permeabilities were determined at various times up to ten weeks following the procedure using simultaneous flux determinations of tritiated inulin and dextran labeled with radioactive carbon on isolated corneas. At all times after radial keratotomy, there was no probable physiologically important change in corneal endothelial permeability to either of the labeled compounds. Fluorophotometry performed in a second group of animals at varying intervals following radial keratotomy showed no probable physiologically important change in endothelial fluorescein permeability. Aqueous humor turnover rate was reduced 16% and 29% at one week and nine to ten weeks, respectively, following radial keratotomy.

Animals↗
PubMed1983

Radial keratotomy and corneal permeability in Owl Monkey.

Radial keratotomy was performed on Owl Monkey corneas using 8 incisions with sparing of a 3.5mm central pupillary area. Cornea endothelial membrane permeabilities were determined at 2 days, and 4 weeks, following the procedure using simultaneous flux determinations of 3H-labeled inulin and 14C-labelled dextran. Inulin permeability was increased 27% two days following the procedure, and had returned to levels comparable to the unoperated eye 4 weeks following the procedure. Dextran permeability was unaltered at both 2 days, and 4 weeks, following the procedure. This study has shown that radial keratotomy causes a transient reduction in endothelial barrier function with the production of physiologically significant 'holes' in the membrane in the immediate post-operative period. The relationship of this physiological alteration to ultimate endothelial cell function is, at the present time, unknown.

Animals↗
PubMed1983

Mycobacterium chelonei keratitis: a case report.

The case is reported of a patient who initially presented with a dendritiform corneal ulcer that ultimately failed to heal and in which Mycobacterium chelonei was repeatedly cultured. The organism was sensitive only to kanamycin and amikacin; however, topical administration of these antibiotics failed to achieve a complete cure. Penetrating keratoplasty was ultimately required to eradicate the organism from the cornea.

Aged↗
PubMed1983

Intracellular pH and glutathione levels in rabbit corneal endothelium following storage in moist chamber and MK medium.

Rabbit corneas were stored for up to 14 days at 4 C either as the whole eye in a moist chamber or as the isolated cornea in MK medium with HEPES buffer. The intracellular pH, the glutathione content, and its oxidation state were determined in the endothelial cells of fresh and stored tissue. The endothelial pH was found to be unchanged following storage of up to 7 days by either method, but after 14 days the pH rose slightly but statistically significantly in corneas stored by both techniques. The intracellular pH was similar in endothelia of those corneas stored in MK medium and of those stored as the whole eye in a moist chamber, for all time periods studied. The intracellular total and percent oxidized glutathione of the endothelium were increased by 50 and 180%, respectively, following 7 days of moist chamber storage. Over this time period there was a 50-fold increase in total glutathione content of the aqueous humor in the stored eyes. In contrast, corneas stored in MK medium for 7 days maintained intracellular total glutathione at levels similar to those of fresh corneas. A gradual but constant decrease in percent oxidized glutathione was observed with increasing length of storage. In terms of pH and glutathione content, the MK medium provided a much more stable environment for the stored cornea than did the aqueous humor in the stored eye.

Animals↗
PubMed1982

Acyclovir and vidarabine monophosphate: comparison of iontophoretic and intravenous administration for the treatment of HSV-1 stromal keratitis.

We determined the therapeutic efficacy of iontophoretic application of acyclovir and vidarabine monophosphate (ara-AMP) for the treatment of herpes simplex virus (HSV) type 1-induced stromal keratitis in rabbits. The therapeutic efficacy of intravenous administration of acyclovir was assessed in the same model. Stromal keratitis was produced by intrastromal injection of 10 microliters purified HSV-1, McKrae strain. Treatment began the first day after intrastromal injection. Iontophoresis (0.5 mAmp for four minutes) of 3.4 percent (0.1 M) ara-AMP and 5.0 percent (0.22 M) acyclovir was performed once daily for five consecutive days in two treatment groups. Intravenous administration of 50 mg acyclovir/kg was performed twice daily for eight consecutive days. Intravenous administration of NaCl (0.14 M) and ocular iontophoresis of NaCl (0.14 M) were performed as controls in the two treatment groups. At least two scorers performed a single masked evaluation of the disease severity (lesion scoring) of the conjunctiva, corneal epithelium, stroma, and iris by still lamp examination. The eyes were scored daily for 12 consecutive days, and then every other day up to day 22. Iontophoresis of acyclovir or ara-AMP significantly reduced the course of the disease compared with iontophoresis of NaCl. Intravenous administration of acyclovir significantly reduced the disease compared with intravenous NaCl. This suggests that iontophoresis of acyclovir or ara-AMP either alone or in combination with intravenous administration of acyclovir may be of value in the treatment of HSV-1 stromal keratitis.

Acyclovir↗
PubMed1982

Metastatic endophthalmitis: a complication of meningococcal meningitis.

A 13-month-old child with Neisseria meningitidis developed bilateral metastatic endophthalmitis. Treatment with systemic and periocular injections of penicillin G and steroids resulted in resolution of the meningitis and the endophthalmitis. This case should alert the pediatrician to the possibility of binding endophthalmitis in a patient with meningitis and ocular abnormalities.

Conjunctiva↗
PubMed1982

Corneal endothelial glutathione after photodynamic change.

Rabbit corneal endothelial cells perfused with 5 X 10(-6)M rose bengal and exposed to incandescent light demonstrated no alteration of either total of or percent oxidized glutathione after 1 hr. Addition of 5400 U/ml catalase to the perfusing solution had no effect on total glutathione levels but caused a marked reduction in percent oxidized glutathione in corneas exposed to light as well as in those not exposed to light. Substitution of sucrose for glucose in the perfusing solution had no effect on total or percent oxidized glutathione. Perfusion of rabbit corneal endothelium with 0.5 mM chlorpromazine and exposure to ultraviolet (UV) light resulted in no change in total glutathione content. A marked reduction in percent oxidized glutathione occurred, however, in corneas perfused with 0.5 mM chlorpromazine both in the presence and absence of UV light. It is concluded that photodynamically induced swelling of corneas is not the result of a failure of the glutathione redox system.

Animals↗