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Biomedical subjects

J Piltz

Publications and source records attributed to J Piltz.

7 recordsLinked to original sources
PubMed2001

Acute effects of sldenafil ctrate (Viagra) on intraocular pressure in open-angle glaucoma.

PURPOSE: To assess the acute effects of sildenafil citrate (VIAGRA) on the intraocular pressure (IOP) of patients with chronic open-angle glaucoma. DESIGN: This was a double-blind, randomized, placebo-controlled, crossover study, in which 15 patients received a single oral dose of sildenafil 100 mg or matching placebo on two separate occasions. METHODS: Fifteen subjects aged 63 +/- 14 years (mean +/- SD) with bilateral chronic open-angle glaucoma were administered a single oral dose of sildenafil 100 mg or matching placebo on two separate occasions at least 3 days apart. IOP was measured in both eyes by Goldmann ap-planation tonometry at baseline and then at 1-5 hours after dosing. Brachial artery systolic and diastolic blood pressures were determined by sphygmomanometry, and heart rate was also monitored at baseline and 1-5 hours after dosing. RESULTS: Compared with placebo, no statistically or clinically significant change in IOP was detected after a single dose of sildenafil 100 mg (P =.20). Moreover, no significant change in mean systemic blood pressure (P =.12) or heart rate (P =.72) was detected after treatment with sildenafil. CONCLUSION: At the maximum therapeutic dose of 100 mg, sildenafil did not produce any significant acute change in IOP in men with chronic open-angle glaucoma. This information is of importance for patients with glaucoma receiving sildenafil for treatment of erectile dysfunction.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed2000

Contralateral effect of topical beta-adrenergic antagonists in initial one-eyed trials in the ocular hypertension treatment study.

PURPOSE: To evaluate the magnitude of the contralateral effect of topically administered beta-blockers on intraocular pressure. METHODS: The Ocular Hypertension Treatment Study enrolled 1,636 subjects. Of these, 817 subjects were randomized to receive topical ocular hypotensive medication and 819 subjects were randomized to close observation (i.e., no topical medication). We compared the intraocular pressure of the contralateral eye of subjects at the baseline visit and after an initial one-eyed therapeutic trial of topical beta-blockers. We examined differences between baseline and follow-up intraocular pressure in untreated eyes of subjects randomized to close observation. RESULTS: The mean reduction in intraocular pressure in the beta-blocker-treated eyes was -5.9 +/- 3. 4 mm Hg (-22% +/- 12%; Student t test, P <.0001). In the contralateral eyes, mean intraocular pressure reduction was -1.5 +/- 3.0 mm Hg (-5.8% +/- 12%; P <.0001). Of the contralateral eyes, 35% showed a reduction of 3 mm Hg or more, and 10% showed a reduction of 6 mm Hg or more. The contralateral effect of the relatively selective beta-blocker betaxolol did not differ from that of any of the nonselective beta-blockers. Factors associated with the magnitude of the contralateral effect were the degree of intraocular pressure reduction in the treated eye and baseline intraocular pressure of the contralateral eye. In the close observation group, no significant reduction in intraocular pressure was noted between the baseline and follow-up visit. CONCLUSIONS: The contralateral effect is important in clinical practice and in clinical trials when the hypotensive effect of a topical beta-blocker is evaluated by means of a one-eyed therapeutic trial.

Administration, Topical↗
PubMed1999

Optic nerve blood flow in glaucoma: effect of systemic hypertension.

PURPOSE: To investigate optic nerve head blood flow in patients with glaucoma and to assess the effect of systemic hypertension. METHODS: This study included 24 eyes of 24 patients with primary open-angle glaucoma. Eleven of these patients had a history of systemic hypertension. Results in patients with glaucoma were compared with those of 13 eyes of 13 age-matched normal controls. Determinations of relative optic nerve head blood velocity, volume, and flow were obtained with laser Doppler flowmetry in the superotemporal and inferotemporal neuroretinal rim and also in the cup. Means of the velocity, volume, and flow of these three measurement sites were calculated for each subject. RESULTS: Mean overall optic nerve head blood flow was 29% lower in glaucoma patients than in normal controls (t test, P < .001). This decrease in flow was mainly caused by a decrease of 23% in mean blood velocity (P < .001). Mean flow in glaucoma patients without systemic hypertension was 26% lower than that of glaucoma patients with hypertension (Tukey honest significant difference test, P = .05). A significant direct correlation was observed between mean flow and mean blood pressure (R = 0.51, P < .02). CONCLUSIONS: Optic nerve blood flow is reduced in glaucoma patients. Glaucoma patients without systemic hypertension have lower optic nerve blood flow than those with hypertension. Our results raise concerns that treatment of systemic hypertension may further decrease optic nerve blood flow in glaucoma patients.

Adult↗
PubMed1998

Optic nerve and choroidal circulation in glaucoma.

PURPOSE: To investigate the circulation of the optic nerve head and choroid in patients with glaucoma. METHODS: Laser Doppler flowmetry was used to determine optic nerve head relative blood velocity (ONVel), volume (ONVol), and flow (ONFlow) in 19 primary open-angle glaucoma patients and 15 age-matched healthy control subjects. In each subject, determinations were obtained from four sites on the neuroretinal tissue and from the center of the cup. A mean of the ONVel, ONVol, and ONFlow for these five measurement sites were calculated for each subject and defined as ONVel5, ONVol5, and ONFlow5. Circulatory parameters were correlated with measures of disease progression such as cup-to-disc ratio and Humphrey visual field indices. Measurements of relative choroidal blood velocity, volume, and flow were also obtained from the foveola. RESULTS: In glaucoma patients, mean ONFlow5 was significantly lower than in control subjects (24%; P = 0.001; independent, two-tailed Student's t-test). This decrease was caused by a significant decrease in ONVol5 (15%; P = 0.04) and a nonsignificant decrease in ONVel5 (10%; P = 0.07). In glaucomatous eyes, mean ONFlow was significantly reduced from normal, by 28% in the inferior temporal neuroretinal rim location (P = 0.001) and by 24% in the superior temporal location (P = 0.001). Although mean ONFlow was also decreased by 33% in the cup, the difference was not statistically significant after a Bonferroni correction was applied. No significant differences from normal were observed in the superior and inferior nasal rim tissues. In glaucoma patients, ONFlow5 was significantly and inversely correlated with the corrected pattern standard deviation (R = -0.53; P = 0.02) and with the cup-to-disc ratio (R = -0.65; P = 0.002). Choroidal blood flow measurements obtained in the foveola of glaucomatous eyes showed no statistically significant differences from normal. CONCLUSIONS: ONFlow5 is reduced by approximately 24% in glaucoma patients. In the inferior temporal rim, the area in which nerve bundle defects most commonly occur, blood flow is reduced by 28%. Patients with more advanced glaucomatous damage, as detected by visual field corrected pattern standard deviation and measurement of the cup-to-disc ratio, tend to have lower ONFlow5. These results suggest a decrease in optic nerve blood flow that is correlated with functional and morphologic measures of glaucomatous progression. However, from these results we cannot conclude whether this decrease in flow has a primary role in the etiology of glaucoma or whether it is the result of the loss of neural components caused by this disease.

Adult↗
PubMed1993

Effect of aging on retinal macular microcirculation: a blue field simulation study.

PURPOSE: Structural changes in the retina are known to occur with aging. This study was performed to investigate whether aging also affects the retinal macular microcirculation. METHODS: Healthy volunteers with ages ranging from 20 to 78 years (mean +/- SD, 49 +/- 19 years) were included in this study. The retinal macular microcirculation was assessed with the blue field simulation technique, based on the blue field entoptic phenomenon. Subjects were asked to match the velocity and density of computer-simulated particles displayed on a screen with those of their entoptically observed leukocytes. Ten matching trials were performed, and an average leukocyte velocity and density were calculated. RESULTS: Significant negative linear correlations were observed between velocity and age (P = 0.0001) and density and age (P = 0.009). Older subjects (50 to 78 years of age) had a significantly slower velocity (0.61 +/- 0.21 mm/s) and smaller density (90 +/- 43 particles per field of view) than younger subjects (0.92 +/- 0.12 mm/s and 135 +/- 65 particles, respectively; unpaired Student's t-test, P = 0.001 and P = 0.01, respectively). CONCLUSIONS: These results suggest that, in normal subjects, retinal macular blood flow decreases with age. The 20% decrease in average velocity with age is very similar to the age-related decrease in number of cells observed in the human foveal ganglion cell layer.

Adult↗
PubMed1989

Endocytosis in the rat retinal pigment epithelium.

Endocytosis in the retinal pigment epithelium (RPE) of rats was studied using horseradish peroxidase, microperoxidase and ferritin tracers. Tracer uptake was mediated by coated pits and coated vesicles. Coated pits formed at two discrete regions at the RPE plasma membrane: that portion of basal membrane directly opposing Bruch's membrane, and at the bases of the apical lamellae and villi. Two populations of coated vesicles were identified and distinguished by size, location and function. Large coated vesicles (91.8 +/- 14.7 nm in diameter) were located near the cell surface and incorporated tracer. Small coated vesicles (64.5 +/- 15.7 nm diameter) located more deeply within the cell were not tracer-labeled, and were often fused with the endoplasmic reticulum or the Golgi apparatus. Observations of the endocytic pathway in rat RPE cells are presented. Tracer was also found in organelles of the lysosomal system, e.g. the multivesicular body, but was not identified in the smooth endoplasmic reticulum or Golgi apparatus.

Animals↗