The effect of several naturally-occurring retinoids and 13-cis-retinoic acid on the proliferation... more The effect of several naturally-occurring retinoids and 13-cis-retinoic acid on the proliferation of cultured bovine retinal pigment epithelial (RPE) cells was investigated. None of the retinoids tested were toxic to the cultures and all, except retinylpalmitate, inhibited cell proliferation when given for more than 3 days. The relative potencies of the retinoids were; all-trans-retinoic acid greater than 13-cis-retinoic acid greater than all-trans-retinol approximately equal to all-trans-retinaldehyde. Uptake of retinoic acid by cultured RPE cells was 10-fold less than the uptake of retinol. Although retinoic acid-treated cultures showed strong density-dependent growth inhibition, cellular proliferation was inhibited more in sparse cultures than in dense ones. Retinoic acid did not significantly inhibit the proliferation of first passage bovine or rabbit RPE cells, but partially inhibited the proliferation of first passage human RPE cells. The sensitivity of all these cultures to growth inhibition by retinoic acid increased in subsequent subcultures, yet there was no effect of passage number on retinoic acid uptake. This study demonstrates that RPE cell proliferation can be inhibited by retinoic acid but the sensitivity of these cells to the retinoid's effects are modulated by incubation time, in vitro aging, and cell density.
With refinement of vitrectomy techniques over the past 30 years, the treatment of rhegmatogenous ... more With refinement of vitrectomy techniques over the past 30 years, the treatment of rhegmatogenous retinal detachment (RRD) has transitioned from the almost exclusive use of extraocular techniques to the present time in which intraocular interventions are available and, in some practices, enjoy almost exclusive use for primary repair of RRD. Except for those situations in which a retinal detachment is associated with obvious immediate complications related to the cataract surgery, the considerations for the treatment of pseudophakic RRD are quite similar to those of phakic RRD. The current options are: use of an extraocular buckling device, vitrectomy-related procedures, intraocular gas injection with associated retinopexy, and combinations of these. Disagreement on the ideal intervention for pseudophakic retinal detachment is not uncommon and particularly so in those RRDs which lie somewhere in the spectrum between complex and simple. As is so often the case in the surgical treatment of disease, there may not be one ideal technique for a particular type of RRD; but knowledge of alternatives logically increases the likelihood of a successful result. The goal of this paper is to outline the clinical factors shown to be of importance in deciding which technique will have the greatest chance at not only achieving retinal re-attachment but also in optimizing long-term vision.
Purpose. To examine the stability of retinoic acid administered to cultured bovine retinal pigmen... more Purpose. To examine the stability of retinoic acid administered to cultured bovine retinal pigment epithelial (RPE) cells and to determine if RPE cells metabolize retinoic acid by a cytochrome P-450 mechanism. Methods. Retinoic acid metabolism was examined in cultured RPE cells and subcellular frac- tions quantitatively by a thin-layer chromatography procedure and qualitatively by normal and reverse phase high-performance liquid
Fundus autofluorescence is a non-invasive imaging modality that measures lipofuscin that has accu... more Fundus autofluorescence is a non-invasive imaging modality that measures lipofuscin that has accumulated in the retinal pigment epithelium (RPE). Excessive lipofuscin in the RPE is a common pathway found in several diseases including Stargardt's disease and age-related macular degeneration. This review discusses the role of photooxidative damage in the development of lipofuscin and the principles of fundus autofluorescence.
We recorded the preoperative pattern reversal visual-evoked responses in 16 subjects (16 eyes) wi... more We recorded the preoperative pattern reversal visual-evoked responses in 16 subjects (16 eyes) with macular gliosis who underwent membrane-peeling operations. A postoperative visual improvement of one octave or more was observed in 11 of 16 eyes (68.8%). Preoperatively, ten eyes had peak amplitudes greater than or equal to 2 microV, all 11 eyes had either lowpass or bandpass curve shapes, and ten eyes had recordable responses to 20- or 10-minutes of an arc check sizes. Each of the three preoperative criteria was significantly associated with a postoperative visual improvement of one octave or more (P = .01, .02, and .02, respectively). These results demonstrate that the preoperative pattern reversal visual-evoked response can objectively assess the function of the underlying macula in patients with macular gliosis and, consequently, is helpful in determining which patient would most likely benefit from a membrane-peeling operation.
Purpose. The authors previously reported that blood speeds in the retinal arteries were signifi- ... more Purpose. The authors previously reported that blood speeds in the retinal arteries were signifi- cantly lower in patients with type I diabetes than in controls without diabetes. The purpose of this long-term, follow-up study was to characterize the natural course of changes in blood speed and blood flow in these patients. Methods. Twenty-four patients were followed up with serial annual
Methods: Eight eyes of 4 cynomolgus monkeys were evaluated. One eye of each monkey was treated wi... more Methods: Eight eyes of 4 cynomolgus monkeys were evaluated. One eye of each monkey was treated with 2 µg of prostaglandin F2a isopropyl ester twice daily for 5 days, and intraocular pressure reduction was con- firmed. These eyes were fixed in methacarn, and paraf- fin sections were immunostained using antibodies to col- lagen types I, III, or IV. To measure
With refinement of vitrectomy techniques over the past 30 years, the treatment of rhegmatogenous ... more With refinement of vitrectomy techniques over the past 30 years, the treatment of rhegmatogenous retinal detachment (RRD) has transitioned from the almost exclusive use of extraocular techniques to the present time in which intraocular interventions are available and, in some practices, enjoy almost exclusive use for primary repair of RRD. Except for those situations in which a retinal detachment is associated with obvious immediate complications related to the cataract surgery, the considerations for the treatment of pseudophakic RRD are quite similar to those of phakic RRD. The current options are: use of an extraocular buckling device, vitrectomy-related procedures, intraocular gas injection with associated retinopexy, and combinations of these. Disagreement on the ideal intervention for pseudophakic retinal detachment is not uncommon and particularly so in those RRDs which lie somewhere in the spectrum between complex and simple. As is so often the case in the surgical treatment of disease, there may not be one ideal technique for a particular type of RRD; but knowledge of alternatives logically increases the likelihood of a successful result. The goal of this paper is to outline the clinical factors shown to be of importance in deciding which technique will have the greatest chance at not only achieving retinal re-attachment but also in optimizing long-term vision.
The coagulase-negative staphylococci are the most common causes of postoperative endophthalmitis.... more The coagulase-negative staphylococci are the most common causes of postoperative endophthalmitis. This study investigates the variability in the disease spectrum and visual outcome of coagulase-negative staphylococcal endophthalmitis in a large, single-center series. Ninety consecutive cases of coagulase-negative staphylococcal endophthalmitis were investigated retrospectively from two time periods, 1978 to 1982 and 1985 to 1987, separated by a transitional period in cataract surgery technique. Using a detailed protocol, inpatient, outpatient, and microbiologic records were analyzed. Six-month visual acuity results were obtained. Diagnosis frequently was delayed, often suspected only after hypopyon development. Thirty-seven percent of patients presented more than 1 week after the inoculating event, and 13% presented after more than 1 month. Variable asymptomatic intervals and gradually worsening inflammatory prodromes are noted. Painless endophthalmitis occurred in 16%. Non-epidermidis infections comprised 28%. With vitrectomy/intraocular antibiotic management, 38% and 68% achieved visual acuities of 20/50 and 20/400, respectively. Overall, 10% of patients developed late retinal detachments. This occurred in only 4% of patients, with endophthalmitis occurring after cataract surgery. Ophthalmologists should become familiar with the emerging concepts of delayed-onset, chronic, and often painless endophthalmitis in which the coagulase-negative staphylococci play a prominent role.
In a double-masked, randomized, placebo-controlled, two-period crossover study, we measured the e... more In a double-masked, randomized, placebo-controlled, two-period crossover study, we measured the effect of aspirin on retinal blood flow in 8 type I diabetic patients, 5 with no observable retinopathy, and 3 with 1-10 observable microaneurysms and no other signs of retinopathy. Each patient ingested 1 capsule/day of either aspirin (650 mg) or placebo for 14 days. Following a 1-month washout period, the treatment was reversed. The bidirectional laser Doppler technique and monochromatic photography were used to measure the blood flow rate in a major temporal retinal artery in 1 eye of each patient at baseline and on the 14th day of each treatment period. Retinal blood flow increased following aspirin in 7 of the 8 patients. Using a standard crossover analysis we found a mean aspirin-placebo treatment difference of 21 +/- 17% (mean +/- 95% CI), which was statistically significant (p = 0.03). Retinal blood flow increased following aspirin by 44 +/- 10% (mean +/- SEM) in the 5 patients with no retinopathy (p = 0.04), but only by 8 +/- 10% (n.s.) in the 3 patients with minimal retinopathy.
It has been suggested that elevated levels of insulin or insulin-like growth factors (IGFs) play ... more It has been suggested that elevated levels of insulin or insulin-like growth factors (IGFs) play a role in the development of diabetic vascular complications. Previously, we have shown a differential response to insulin between vascular cells from retinal capillaries and large arteries with the former being much more insulin responsive. In the present study, we have characterized the receptors and the growth-promoting effect of insulinlike growth factor I (IGF-I) and multiplication-stimulating activity (MSA, an IGF-II) on endothelial cells and pericytes from calf retinal capillaries and on endothelial and smooth muscle cells from calf aorta. We found single and separate populations of high affinity receptors for IGF-I and MSA with respective affinity constants of 1 X 10(-9) M-1 and 10(-8) M-1 in all four cell types studied. Specific binding of IGF-I was between 7.2 and 7.9% per milligram of protein in endothelial cells and 9.1 and 10.4% in the vascular supporting cells. For 125I-MSA, retinal endothelial cells bound only 1.7-2.5%, whereas the aortic endothelial cells and the vascular supporting cells bound between 5.6 and 8.5% per milligram of protein. The specificity of the receptors for IGF-I and MSA differed, as insulin and MSA was able to compete with 125I-IGF-I for binding to the IGF-I receptors with 0.01-0.1, the potency of unlabeled IGF-I, whereas even 1 X 10(-6) M, insulin did not significantly compete with 125I-MSA for binding to the receptors for MSA. For growth-promoting effects, as measured by the incorporation of [3H]thymidine into DNA, confluent retinal endothelial cells responded to IGF-I and MSA by up to threefold increase in the rate of DNA synthesis, whereas confluent aortic endothelial cells did not respond at all. A similar differential of response to insulin between micro- and macrovascular endothelial cells was reported by us previously. In the retinal endothelium, insulin was more potent than IGF-I and IGF-I was more potent that MSA. In the retinal and aortic supporting cells, no differential response to insulin or the IGFs was observed. In the retinal pericytes, IGF-I, which stimulated significant DNA synthesis beginning at 1 X 10(-9) M, and had a maximal effect at 5 X 10(-8) M, was 10-fold more potent than MSA and equally potent to insulin. In the aortic smooth muscle cells, IGF-I was 10-100 times more potent than insulin or MSA. In the retinal and aortic supporting cells, no differential response to insulin or the IGFs was observed. In the retinal pericytes, IGF-I, which stimulated significant DNA synthesis beginning at 1 X 10(-9) M, and had a maximal effect at 5 X 10(-8) M, was 10-fold more potent than MSA and equally potent to insulin. In the aortic smooth muscle cells, IGF-I was 10-100 times more potent than insulin or MSA. In addition, insulin and IGF-I at 1 X 10(-6) and 1 X 10(-8) M, respectively, stimulated these cells to grow by doubling the number of cells as well. In all responsive tissues, the combination of insulin and IGFs were added together, no further increase in effect was seen. These data showed that vascular cells have insulin and IGF receptors, but have a differential response to these hormones. These differences in biological response between cells from retinal capillaries and large arteries could provide clues to understanding the pathogenesis of diabetic micro- and macroangiopathy.
The effect of several naturally-occurring retinoids and 13-cis-retinoic acid on the proliferation... more The effect of several naturally-occurring retinoids and 13-cis-retinoic acid on the proliferation of cultured bovine retinal pigment epithelial (RPE) cells was investigated. None of the retinoids tested were toxic to the cultures and all, except retinylpalmitate, inhibited cell proliferation when given for more than 3 days. The relative potencies of the retinoids were; all-trans-retinoic acid greater than 13-cis-retinoic acid greater than all-trans-retinol approximately equal to all-trans-retinaldehyde. Uptake of retinoic acid by cultured RPE cells was 10-fold less than the uptake of retinol. Although retinoic acid-treated cultures showed strong density-dependent growth inhibition, cellular proliferation was inhibited more in sparse cultures than in dense ones. Retinoic acid did not significantly inhibit the proliferation of first passage bovine or rabbit RPE cells, but partially inhibited the proliferation of first passage human RPE cells. The sensitivity of all these cultures to growth inhibition by retinoic acid increased in subsequent subcultures, yet there was no effect of passage number on retinoic acid uptake. This study demonstrates that RPE cell proliferation can be inhibited by retinoic acid but the sensitivity of these cells to the retinoid's effects are modulated by incubation time, in vitro aging, and cell density.
With refinement of vitrectomy techniques over the past 30 years, the treatment of rhegmatogenous ... more With refinement of vitrectomy techniques over the past 30 years, the treatment of rhegmatogenous retinal detachment (RRD) has transitioned from the almost exclusive use of extraocular techniques to the present time in which intraocular interventions are available and, in some practices, enjoy almost exclusive use for primary repair of RRD. Except for those situations in which a retinal detachment is associated with obvious immediate complications related to the cataract surgery, the considerations for the treatment of pseudophakic RRD are quite similar to those of phakic RRD. The current options are: use of an extraocular buckling device, vitrectomy-related procedures, intraocular gas injection with associated retinopexy, and combinations of these. Disagreement on the ideal intervention for pseudophakic retinal detachment is not uncommon and particularly so in those RRDs which lie somewhere in the spectrum between complex and simple. As is so often the case in the surgical treatment of disease, there may not be one ideal technique for a particular type of RRD; but knowledge of alternatives logically increases the likelihood of a successful result. The goal of this paper is to outline the clinical factors shown to be of importance in deciding which technique will have the greatest chance at not only achieving retinal re-attachment but also in optimizing long-term vision.
Purpose. To examine the stability of retinoic acid administered to cultured bovine retinal pigmen... more Purpose. To examine the stability of retinoic acid administered to cultured bovine retinal pigment epithelial (RPE) cells and to determine if RPE cells metabolize retinoic acid by a cytochrome P-450 mechanism. Methods. Retinoic acid metabolism was examined in cultured RPE cells and subcellular frac- tions quantitatively by a thin-layer chromatography procedure and qualitatively by normal and reverse phase high-performance liquid
Fundus autofluorescence is a non-invasive imaging modality that measures lipofuscin that has accu... more Fundus autofluorescence is a non-invasive imaging modality that measures lipofuscin that has accumulated in the retinal pigment epithelium (RPE). Excessive lipofuscin in the RPE is a common pathway found in several diseases including Stargardt's disease and age-related macular degeneration. This review discusses the role of photooxidative damage in the development of lipofuscin and the principles of fundus autofluorescence.
We recorded the preoperative pattern reversal visual-evoked responses in 16 subjects (16 eyes) wi... more We recorded the preoperative pattern reversal visual-evoked responses in 16 subjects (16 eyes) with macular gliosis who underwent membrane-peeling operations. A postoperative visual improvement of one octave or more was observed in 11 of 16 eyes (68.8%). Preoperatively, ten eyes had peak amplitudes greater than or equal to 2 microV, all 11 eyes had either lowpass or bandpass curve shapes, and ten eyes had recordable responses to 20- or 10-minutes of an arc check sizes. Each of the three preoperative criteria was significantly associated with a postoperative visual improvement of one octave or more (P = .01, .02, and .02, respectively). These results demonstrate that the preoperative pattern reversal visual-evoked response can objectively assess the function of the underlying macula in patients with macular gliosis and, consequently, is helpful in determining which patient would most likely benefit from a membrane-peeling operation.
Purpose. The authors previously reported that blood speeds in the retinal arteries were signifi- ... more Purpose. The authors previously reported that blood speeds in the retinal arteries were signifi- cantly lower in patients with type I diabetes than in controls without diabetes. The purpose of this long-term, follow-up study was to characterize the natural course of changes in blood speed and blood flow in these patients. Methods. Twenty-four patients were followed up with serial annual
Methods: Eight eyes of 4 cynomolgus monkeys were evaluated. One eye of each monkey was treated wi... more Methods: Eight eyes of 4 cynomolgus monkeys were evaluated. One eye of each monkey was treated with 2 µg of prostaglandin F2a isopropyl ester twice daily for 5 days, and intraocular pressure reduction was con- firmed. These eyes were fixed in methacarn, and paraf- fin sections were immunostained using antibodies to col- lagen types I, III, or IV. To measure
With refinement of vitrectomy techniques over the past 30 years, the treatment of rhegmatogenous ... more With refinement of vitrectomy techniques over the past 30 years, the treatment of rhegmatogenous retinal detachment (RRD) has transitioned from the almost exclusive use of extraocular techniques to the present time in which intraocular interventions are available and, in some practices, enjoy almost exclusive use for primary repair of RRD. Except for those situations in which a retinal detachment is associated with obvious immediate complications related to the cataract surgery, the considerations for the treatment of pseudophakic RRD are quite similar to those of phakic RRD. The current options are: use of an extraocular buckling device, vitrectomy-related procedures, intraocular gas injection with associated retinopexy, and combinations of these. Disagreement on the ideal intervention for pseudophakic retinal detachment is not uncommon and particularly so in those RRDs which lie somewhere in the spectrum between complex and simple. As is so often the case in the surgical treatment of disease, there may not be one ideal technique for a particular type of RRD; but knowledge of alternatives logically increases the likelihood of a successful result. The goal of this paper is to outline the clinical factors shown to be of importance in deciding which technique will have the greatest chance at not only achieving retinal re-attachment but also in optimizing long-term vision.
The coagulase-negative staphylococci are the most common causes of postoperative endophthalmitis.... more The coagulase-negative staphylococci are the most common causes of postoperative endophthalmitis. This study investigates the variability in the disease spectrum and visual outcome of coagulase-negative staphylococcal endophthalmitis in a large, single-center series. Ninety consecutive cases of coagulase-negative staphylococcal endophthalmitis were investigated retrospectively from two time periods, 1978 to 1982 and 1985 to 1987, separated by a transitional period in cataract surgery technique. Using a detailed protocol, inpatient, outpatient, and microbiologic records were analyzed. Six-month visual acuity results were obtained. Diagnosis frequently was delayed, often suspected only after hypopyon development. Thirty-seven percent of patients presented more than 1 week after the inoculating event, and 13% presented after more than 1 month. Variable asymptomatic intervals and gradually worsening inflammatory prodromes are noted. Painless endophthalmitis occurred in 16%. Non-epidermidis infections comprised 28%. With vitrectomy/intraocular antibiotic management, 38% and 68% achieved visual acuities of 20/50 and 20/400, respectively. Overall, 10% of patients developed late retinal detachments. This occurred in only 4% of patients, with endophthalmitis occurring after cataract surgery. Ophthalmologists should become familiar with the emerging concepts of delayed-onset, chronic, and often painless endophthalmitis in which the coagulase-negative staphylococci play a prominent role.
In a double-masked, randomized, placebo-controlled, two-period crossover study, we measured the e... more In a double-masked, randomized, placebo-controlled, two-period crossover study, we measured the effect of aspirin on retinal blood flow in 8 type I diabetic patients, 5 with no observable retinopathy, and 3 with 1-10 observable microaneurysms and no other signs of retinopathy. Each patient ingested 1 capsule/day of either aspirin (650 mg) or placebo for 14 days. Following a 1-month washout period, the treatment was reversed. The bidirectional laser Doppler technique and monochromatic photography were used to measure the blood flow rate in a major temporal retinal artery in 1 eye of each patient at baseline and on the 14th day of each treatment period. Retinal blood flow increased following aspirin in 7 of the 8 patients. Using a standard crossover analysis we found a mean aspirin-placebo treatment difference of 21 +/- 17% (mean +/- 95% CI), which was statistically significant (p = 0.03). Retinal blood flow increased following aspirin by 44 +/- 10% (mean +/- SEM) in the 5 patients with no retinopathy (p = 0.04), but only by 8 +/- 10% (n.s.) in the 3 patients with minimal retinopathy.
It has been suggested that elevated levels of insulin or insulin-like growth factors (IGFs) play ... more It has been suggested that elevated levels of insulin or insulin-like growth factors (IGFs) play a role in the development of diabetic vascular complications. Previously, we have shown a differential response to insulin between vascular cells from retinal capillaries and large arteries with the former being much more insulin responsive. In the present study, we have characterized the receptors and the growth-promoting effect of insulinlike growth factor I (IGF-I) and multiplication-stimulating activity (MSA, an IGF-II) on endothelial cells and pericytes from calf retinal capillaries and on endothelial and smooth muscle cells from calf aorta. We found single and separate populations of high affinity receptors for IGF-I and MSA with respective affinity constants of 1 X 10(-9) M-1 and 10(-8) M-1 in all four cell types studied. Specific binding of IGF-I was between 7.2 and 7.9% per milligram of protein in endothelial cells and 9.1 and 10.4% in the vascular supporting cells. For 125I-MSA, retinal endothelial cells bound only 1.7-2.5%, whereas the aortic endothelial cells and the vascular supporting cells bound between 5.6 and 8.5% per milligram of protein. The specificity of the receptors for IGF-I and MSA differed, as insulin and MSA was able to compete with 125I-IGF-I for binding to the IGF-I receptors with 0.01-0.1, the potency of unlabeled IGF-I, whereas even 1 X 10(-6) M, insulin did not significantly compete with 125I-MSA for binding to the receptors for MSA. For growth-promoting effects, as measured by the incorporation of [3H]thymidine into DNA, confluent retinal endothelial cells responded to IGF-I and MSA by up to threefold increase in the rate of DNA synthesis, whereas confluent aortic endothelial cells did not respond at all. A similar differential of response to insulin between micro- and macrovascular endothelial cells was reported by us previously. In the retinal endothelium, insulin was more potent than IGF-I and IGF-I was more potent that MSA. In the retinal and aortic supporting cells, no differential response to insulin or the IGFs was observed. In the retinal pericytes, IGF-I, which stimulated significant DNA synthesis beginning at 1 X 10(-9) M, and had a maximal effect at 5 X 10(-8) M, was 10-fold more potent than MSA and equally potent to insulin. In the aortic smooth muscle cells, IGF-I was 10-100 times more potent than insulin or MSA. In the retinal and aortic supporting cells, no differential response to insulin or the IGFs was observed. In the retinal pericytes, IGF-I, which stimulated significant DNA synthesis beginning at 1 X 10(-9) M, and had a maximal effect at 5 X 10(-8) M, was 10-fold more potent than MSA and equally potent to insulin. In the aortic smooth muscle cells, IGF-I was 10-100 times more potent than insulin or MSA. In addition, insulin and IGF-I at 1 X 10(-6) and 1 X 10(-8) M, respectively, stimulated these cells to grow by doubling the number of cells as well. In all responsive tissues, the combination of insulin and IGFs were added together, no further increase in effect was seen. These data showed that vascular cells have insulin and IGF receptors, but have a differential response to these hormones. These differences in biological response between cells from retinal capillaries and large arteries could provide clues to understanding the pathogenesis of diabetic micro- and macroangiopathy.
Uploads
Papers by Sheldon Buzney