B S Winkler

University of Plymouth

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Co-Authors

M V Riley

Smith-Kettlewell Eye Research Institute

J. K. Margerison

University of Nottingham

Catherine A. Starnes

Smith-Kettlewell Eye Research Institute

M I Peters

Maria College

CA Starnes

Oakland University

M. J. Arnold

Technical University of Munich

Flora Solomon

Oakland University

Caroline Czajkowski

University of Connecticut

Flávio Dutra de Resende

Agência Paulista de Tecnologia dos Agronegócios

Stephen M. Orselli

Oakland University

Cooperative Institutions

University of Rochester

Oakland University

Smith-Kettlewell Eye Research Institute

Wayne State University

Michigan United

National Eye Institute

Universidade Estadual Paulista (Unesp)

Beaumont Hospital, Royal Oak

Institute of Cell Biology and Neurobiology

National Institutes of Health

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Energy metabolism in human retinal Müller cells.

PubMed (2000)

B S Winkler M. J. Arnold M A Brassell Donald G. Puro

To measure selected parameters of energy metabolism and adenosine triphosphate (ATP) production in passaged monolayer cultures of human retinal glial (Müller) cells to assess the effects of varying substrate and oxygen availability on the biochemistry and histologic integrity of these cells.

Adenosine triphosphate

Anaerobic glycolysis

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Citations (154)

ATPase activities of human retina and pigment epithelium-choroid.

PubMed (1982)

B S Winkler J.M. Hopkins

The Mg2+-, the Na+-K+-, and the HCO3--stimulated ATPase activities have been measured in the retina and pigment epithelium of postmortem human donor eyes. Activities were measured between 24 and 72 hr after death, following storage of the eyes in moistened chambers kept in a refrigerator. There appeared to be no significant differences in the ATPase activities between the 24 and 72 hr tissues. The human retina demonstrated both Mg2+- and Na+-K+-stimulated ATPase activity, but no HCO3+-stimulated ATPase activity, but not HCO3+-stimulated ATPase activity. The Na+-K+ ATPase activity was 1.54 mumol Pi/hr/mg protein, which amounted to 37% of the total ATP hydrolysis of the retina. The pigment epithelium-choroid showed significant Mg2+-, Na+-K+-, and HCO3--stimulated ATPase activities, with the stimulation caused by HCO3- about 25% greater than the effect due to Na+-K+, 0.64 vs. 0.51 mumol Pi/hr/mg protein. These findings in human retina and pigment epithelium-choroid show that certain metabolic processes continue to operate for several days after death.

Choroid

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Citations (3)

Importance of bicarbonate in retinal function.

PubMed (1977)

B S Winkler V Simson Jeffrey D. Benner

This study demonstrates a requirement for bicarbonate in retinal function. Omission of bicarbonate, with either phosphate or Tris used to maintain a constant pH, leads to significant changes in both the electroretinogram potentials and metabolism of the isolated rat retina. Electroretinograms in bicarbonate-free media show a selective loss of the b wave and a decline in the amplitudes of the a wave and Slow PIII. Substitution of phosphate for bicarbonate causes a 60 and 52% decrease in aerobic and anaerobic lactate production, respectively, but this substitution leads to a 27% increase in aerobic retinal ATP content. It is suggested that the electrical effects of bicarbonate-free media are due to a decrease in utilization of ATP below critical levels at critical sites.

Bicarbonate

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Citations (43)

Modification of the surface characteristics of anodic alumina membranes using sol–gel precursor chemistry

Journal of Membrane Science (2003)

B S Winkler

Streaming current

Zeta potential

Surface charge

10.1016/j.memsci.2003.07.015

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Citations (28)

Energy Requirements, Ion Transport and Metabolic Overload in Retinal Cells

Investigative Ophthalmology & Visual Science (2004)

B S Winkler Catherine A. Starnes Z. Firouzgan

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Is inorganic phosphate (Pi) a limiting factor for rapid postischemic ATP repletion?

Journal of Molecular and Cellular Cardiology (1986)

M Fischer Arnd B. Buchwald B S Winkler Wolfgang Schäper

Limiting

10.1016/s0022-2828(86)80854-9

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Citations (2)

Hyaluronidase and Retinal Function

Archives of Ophthalmology (1985)

B S Winkler Eva Cohn

Using the incubated isolated rat retina, the effects of hyaluronidase on the electroretinogram (ERG) and metabolic activities were investigated. Initial experiments established the activity of hyaluronidase needed to liquefy, within 15 to 30 minutes, the vitreous of postmortem human eyes; this concentration was 1,000 units/mL. Rat retinas were superfused with a bicarbonate-buffered, oxygenated medium to which hyaluronidase was added in activities ranging from 100 to 5,000 units/mL. These concentrations of hyaluronidase did not significantly alter the amplitudes of the a waves and b waves of the ERG in comparison to their control amplitudes. Measurements were also made of lactic acid production, oxygen consumption, glutathione content, and adenosine triphosphatase activities in control and hyaluronidase-exposed retinas. In the presence of hyaluronidase, their respective values were similar to the controls for all biochemical factors studied. The present experiments demonstrate that addition of hyaluronidase to an "ocular irrigating" solution results in normal ERGs and normal retinal metabolic activity and suggests the possibility that hyaluronidase may be useful in enzyme-assisted vitrectomy.

Hyaluronidase

Bicarbonate

10.1001/archopht.1985.01050110139043

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Citations (7)

Na+-K+ and HCO-3 ATPase activity in retina: dependence on calcium and sodium.

PubMed (1977)

B S Winkler M V Riley

With the use of homogenates of whole rat retina, the activities of Na+-K+-- and HCO-3-stimulated ATPases were measured in media containing different concentrations of calcium and sodium ions. In comparison to the Na+-K+ ATPase activity observed in the presence of 2 mM calcium and 130 mM sodium, the omission of calcium from the medium led to a 16-fold increase in activity. Furthermore, the omission of calcium and the reduction of the concentration of sodium in the medium to 25 mM also resulted in an increase in activity of ninefold. This study also demonstrates, for the first time, the existence of a HCO-3 stimulated. ATPase activity in the retina. These results are discussed in relation to recent observations on the effects of calcium- and bicarbonate-free media on the electrical and metabolic activities of the rat retina.

Bicarbonate

Sodium bicarbonate

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Citations (20)

Relationship between fluid transport and in situ inhibition of Na(+)-K+ adenosine triphosphatase in corneal endothelium.

PubMed (1994)

M V Riley B S Winkler M I Peters Caroline Czajkowski

To examine the relationship between the activity of the sodium pump of the corneal endothelium and corneal thickness. It was postulated that because inhibition pressure of the stroma decreases as thickness increases, a partially inhibited sodium pump would result in a new steady-state thickness of the cornea when reduced rates of fluid influx and efflux were equal. Measurements of physiologic behavior and biochemical activity were to be made in the same tissue and thus establish the relationship directly.Rabbit corneas were superfused with a bicarbonate Ringer solution containing different concentrations of ouabain. Exposure to ouabain was either continuous for 4 hours or for an initial 10 minutes followed by ouabain-free superfusion. Thickness was measured, and, after superfusion, endothelium was removed from the corneas, sonicated, and assayed for Na(+)-K+ adenosine triphosphatase (ATPase) activity without further addition of ouabain to the assay medium. Thickness was also measured during superfusion with suboptimal concentrations of Na+ or HCO3- and with brefeldin A, an inhibitor of protein trafficking.Continuous exposure to ouabain caused corneas to swell, but no new steady-state thickness was reached. At low concentrations, swelling rates increased with time, as did the extent of inhibition of the Na(+)-K+ ATPase. With only a 10-minute exposure to ouabain, swelling rates with 10(-4) M to 10(-5) M decreased with the duration of ouabain-free superfusion. Similar swelling curves were obtained by reductions in Na+ or HCO3- concentrations in the superfusion medium, indicating that partial inhibition of the endothelial fluid transport processes, whether via the Na(+)-K+ ATPase or by suboptimal ionic conditions, led toward a new equilibrium thickness of the cornea. However, when superfusion was continued for more than 4 hours, the corneas exposed for 10 minutes to 3 x 10(-5) M or lower-concentration ouabain showed increasing Na(+)-K+ ATPase activity and began to thin, indicating a recovery of fluid transport capability. This recovery was blocked by addition of brefeldin A during the ouabain-free superfusion.Inhibition of Na(+)-K+ ATPase by low concentrations of ouabain increases with time. Temporary exposure to ouabain causes swelling at rates that decline with time as ouabain dissociates from enzyme sites. This dissociation, together with the turnover of Na(+)-K+ ATPase in the plasma membrane, can lead to recovery of normal thickness in ouabain-exposed corneas. Twenty percent of Na(+)-K+ ATPase in the endothelium is estimated to be intracellular, and about 20% of the activity can be inhibited without inducing swelling.

Triphosphatase

Corneal Endothelium

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Citations (22)

Hoof measurements and their relationship to lameness in first lactation heifers

Proceedings of the British Society of Animal Science (2005)

B S Winkler J. K. Margerison

A significantly greater percentage of lesions on the claws of the outer hind foot has been recorded and this has been linked to the foot and leg conformation of the cow. Claw measurements were compared to survival rates and locomotion scores (Boelling and Pollot, 1998), but few experiments looked at changes during the lactation period (Offer et al ., 2000) in heifers housed in straw yards and compared them to changes in lesion scores. The aim of this experiment was to compare measurements of the front and hind claws to the incidence of lameness and the formation of lesions in the sole horn during the pre- and postpartum period in first lactation heifers housed in straw yards.

Claw

Hoof

Foot (prosody)

10.1017/s1752756200011194

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Citations (0)