The dynamics of erythrocyte infection in bovine anaplasmosis: a flow cytometry-based analysis.

Anaplasma marginale (A. marginale) is an obligate intracellular bacterium that infects bovine erythrocytes causing extravascular hemolysis and anemia. In the present work, we combine SYTO16 labeling of parasitized cells with the statistical power of flow cytometry to study the evolution of erythrocyte infection during bovine anaplasmosis.

Risk factors for hemiretinal vein occlusion: comparison with risk factors for central and branch retinal vein occlusion: the eye disease case-control study.

OBJECTIVE: Possible risk factors for hemiretinal vein occlusion were identified and compared with risk factor profiles for central and branch retinal vein occlusion. DESIGN: The design was a multicenter case-control study. METHODS: The authors identified 79 patients with hemiretinal vein occlusion (HRVO), 258 patients with central retinal vein occlusion (CRVO), 270 patients with branch retinal vein occlusion (BRVO), and 1142 control subjects at 5 clinical centers. Risk factor data were obtained through interviews, clinical examinations, and laboratory analyses of blood specimens. RESULTS: Systemic hypertension and history of diabetes mellitus were associated with increased risk of HRVO. Risk of CRVO increased with history of diabetes, systemic hypertension, and higher erythrocyte sedimentation rate (females only); risk of CRVO decreased with increasing amounts of physical activity and increasing amounts of alcohol consumption. Systemic hypertension, higher body mass index, and higher alpha2-globulin levels were associated with increased risk of BRVO, whereas higher high-density lipoprotein levels and increasing levels of alcohol consumption were associated with decreased risk of BRVO. Glaucoma history was associated with all three types of retinal vein occlusion. CONCLUSION: Patients presenting with retinal vein occlusion should be evaluated for cardiovascular disease, diabetes, and glaucoma.

Serum zinc and serum lipid profiles in 778 adults.

There has been increasing use of high-dosage zinc supplementation in the population, in particular as a potential treatment for age-related macular degeneration. We examined the relationship between fasting serum zinc and serum lipid levels in 778 adults, aged 22 to 80 years, who were control subjects in a multicenter, clinic-based case-control study. The samples were taken during 1987 to 1990, a time when vitamin/mineral supplementation was becoming increasingly common. We found that higher serum zinc levels, most notably those above the highest quintile, were associated with higher levels of total serum cholesterol, low-density-lipoprotein cholesterol, and triglycerides. No significant trend was noted for high-density-lipoprotein cholesterol. Previous studies demonstrated that high-dosage zinc supplements raise serum zinc levels. The possibility that use of such supplements can adversely affect serum lipid profiles suggests that chronic ingestion of such supplements should not be done without adequate medical supervision.

Adenylyl cyclase and G-proteins in Phytomonas.

Phytomonas sp. membranes have an adenylyl cyclase activity which is greater in the presence of Mn2+ than with Mg2+. The Mg2+ and Mn2+ activity ratio varies from one membrane preparation to another, suggesting that the adenylyl cyclase has a variable activation state. A[35S]GTP-gamma-S-binding activity with a Kd of 171 nM was detected in Phytomonas membranes. Incubation of these membranes with activated cholera or pertussis toxin and [adenylate 23P]NAD+ led to incorporation of radioactivity into bands of about 40-44 kDa. Crude membranes were electrophoresed on SDS-polyacrylamide gels and analyzed, by Western blotting, with the 9188 anti-alpha[s] antibody and the AS/7 antibody (anti-alpha[i], anti-alpha[i1], and anti-alpha[i2]. These procedures resulted in the identification of polypeptides of approximately 40-44 kDa. Phytomonas adenylyl cyclase could be activated by treatment of membrane preparations with cholera toxin, in the presence of NAD+, while similar treatment with pertussis toxin did not affect this enzyme activity. These studies indicate that in Phytomonas, adenylyl cyclase activity is coupled to an unknown receptor entity through G alpha[s] proteins.

Dietary carotenoids, vitamins A, C, and E, and advanced age-related macular degeneration. Eye Disease Case-Control Study Group.

OBJECTIVE--To evaluate the relationships between dietary intake of carotenoids and vitamins A, C, and E and the risk of neovascular age-related macular degeneration (AMD), the leading cause of irreversible blindness among adults. DESIGN--The multicenter Eye Disease Case-Control Study. SETTING--Five ophthalmology centers in the United States. PATIENTS--A total of 356 case subjects who were diagnosed with the advanced stage of AMD within 1 year prior to their enrollment, aged 55 to 80 years, and residing near a participating clinical center. The 520 control subjects were from the same geographic areas as case subjects, had other ocular diseases, and were frequency-matched to cases according to age and sex. MAIN OUTCOME MEASURES--The relative risk for AMD was estimated according to dietary indicators of antioxidant status, controlling for smoking and other risk factors, by using multiple logistic-regression analyses. RESULTS--A higher dietary intake of carotenoids was associated with a lower risk for AMD. Adjusting for other risk factors for AMD, we found that those in the highest quintile of carotenoid intake had a 43% lower risk for AMD compared with those in the lowest quintile (odds ratio, 0.57; 95% confidence interval, 0.35 to 0.92; P for trend = .02). Among the specific carotenoids, lutein and zeaxanthin, which are primarily obtained from dark green, leafy vegetables, were most strongly associated with a reduced risk for AMD (P for trend = .001). Several food items rich in carotenoids were inversely associated with AMD. In particular, a higher frequency of intake of spinach or collard greens was associated with a substantially lower risk for AMD (P for trend < .001). The intake of preformed vitamin A (retinol) was not appreciably related to AMD. Neither vitamin E nor total vitamin C consumption was associated with a statistically significant reduced risk for AMD, although a possibly lower risk for AMD was suggested among those with higher intake of vitamin C, particularly from foods. CONCLUSION--Increasing the consumption of foods rich in certain carotenoids, in particular dark green, leafy vegetables, may decrease the risk of developing advanced or exudative AMD, the most visually disabling form of macular degeneration among older people. These findings support the need for further studies of this relationship.

Reduction of macular oedema by acetazolamide in patients with chronic iridocyclitis: a randomised prospective crossover study.

Thirty patients with cystoid macular oedema secondary to chronic iridocyclitis were enrolled in a two period, prospective, randomised, double masked, crossover study that compared sustained release acetazolamide (500 mg twice a day) with a placebo to measure the effects on the reduction of cystoid macular oedema and improvement of visual acuity. All patients were treated for 1 month with either acetazolamide or placebo, received no treatment for 1 month, and were then treated for 1 month with the other medication. Statistically significant improvement in visual acuity was seen at 14 and 28 days in the treated patients. No improvement was seen when patients received placebo. Improved visual acuity was not associated with race or sex. However, younger patients (under age 55 years) were more likely to benefit from treatment. Results of vitreous fluorophotometry, obtained at baseline and 4 weeks, demonstrated an improvement in posterior vitreous penetration ratios and mid vitreous penetration ratios after treatment with acetazolamide but not with placebo.

Intraocular lens implantation versus no intraocular lens implantation in patients with chronic iridocyclitis and pars planitis. A randomized prospective study.

PURPOSE: The authors studied the safety of intraocular lens (IOL) implantation in patients with uveitis. METHODS: The authors prospectively randomized 26 patients with chronic iridocyclitis (22 patients) or pars planitis (4 patients) to undergo IOL implantation or no IOL implantation at the time of cataract surgery. RESULTS: There was no statistical difference in visual acuity results at 1 year between the two groups. There was a trend toward better visual acuity in patients with chronic iridocyclitis without IOLs. Cocoon-like dense fibrous membranes enveloped the IOL in two patients. CONCLUSION: The authors conclude that IOLs are relatively safe in patients with chronic iridocyclitis but that only a much larger study could determine if the trend toward better visual acuity without an IOL was real.

G-protein from Medicago sativa: functional association to photoreceptors.

G-protein subunits were characterized from Medicago sativa (alfalfa) seedlings. Crude membranes and GTP-Sepharose-purified fractions were electrophoresed on SDS/polyacrylamide gels and analysed by Western blotting with 9193 (anti-alpha common) and AS/7 (anti-alpha t, anti-alpha i1 and anti-alpha i2) polyclonal antibodies. These procedures led to the identification of a specific polypeptide band of about 43 kDa. Another polypeptide reacting with the SW/1 (anti-beta) antibody, of about 37 kDa, was also detected. The 43 kDa polypeptide bound specifically [alpha-32P]GTP by a photoaffinity reaction and was ADP-ribosylated by activated cholera toxin, but not by pertussis toxin. Irradiation of etiolated Medicago sativa protoplast preparations at 660 nm for 1 min produced a maximal increase in the guanosine 5'-[gamma-thio]triphosphate (GTP[35S])-binding rate. After this period of irradiation, the binding rate tended to decrease. The effect of a red-light (660 nm) pulse on the binding rate was reversed when it was immediately followed by a period of far-red (> 730 nm) illumination. These results may suggest that activation of GTP[S]-binding rate was a consequence of conversion of phytochrome Pr into the Ptr form.

Elevated serum sialic acid in idiopathic acute iridocyclitis.

We measured the serum levels of sialic acid in 12 patients with idiopathic acute iridocyclitis and 18 normal controls. Sialic acid levels were significantly elevated in the patients with idiopathic acute iridocyclitis. Since animal studies have shown that intraocular inflammation alone cannot elevate serum level of sialic acid, the result of our study suggest that idiopathic acute iridocyclitis may be a multiorgan disease with systemic effects.

Surgical treatment of thyroid-related lower eyelid retraction: a modified approach.

A 15-year retrospective study was performed in 68 patients who underwent scleral implantation for correction of lower eyelid retraction related to Graves' disease. Three variations of the scleral implantation procedure were used over three time periods. Scleral grafting alone ("old" procedure) was performed in 53 patients from 1974 to 1985. Because of persistent lower lid retraction postoperatively, this procedure was modified. Beginning in 1986, a lateral canthal suspension consisting of either a lateral tarsal strip or a lateral tarsorrhaphy was added to the scleral implantation ("intermediate" procedure) and was performed in seven patients. Since 1988, the procedure has been further modified to include both a lateral tarsal strip and a lateral tarsorrhaphy ("new" procedure). Eight patients underwent this procedure. Analysis with Student's t test indicated a statistically significant reduction in lower lid retraction when using the new procedure, as measured by a reduction in the margin reflex distance-2, the distance from the corneal light reflex to the central lower lid (p = 0.02), and by a reduction in inferior central scleral show, the distance from the central lower lid to the inferior limbus (p = 0.02). An analysis of covariance, controlling for age, Hertel exophthalmometry readings, and length of follow-up, also indicated that the reduction in the postoperative margin reflex distance-2 was significant (p = 0.04).

A randomized clinical trial of feeder vessel photocoagulation of sickle cell retinopathy. A long-term follow-up.

Long-term follow-up of patients enrolled in a randomized prospective trial of feeder vessel photocoagulation for proliferative sickle retinopathy has been completed. Of the 44 patients enrolled in Chicago, nearly a decade follow-up has been achieved on 29 patients (45 eyes). There were 20 control untreated eyes and 25 argon laser-treated eyes. Prolonged loss of visual acuity was rare in both groups. Argon laser photocoagulation has had a sustained effect on reducing the incidence of vitreous hemorrhage and visual loss from vitreous hemorrhage. Nine (45%) of 20 control eyes had vitreous hemorrhage, and it was recurrent in six (66%) of these nine eyes. A single episode was the only hemorrhagic event in the treated eyes. The laser-induced complications of choroidal neovascularization or retinal detachment were not associated with long-term visual sequelae. New sea fan evolution in 47% of study eyes suggests that these patients require long-term surveillance.

A randomized clinical trial of scatter photocoagulation of proliferative sickle cell retinopathy.

A randomized prospective clinical trial of argon laser scatter photocoagulation therapy for proliferative sickle cell retinopathy was performed on 116 patients (174 eyes) in Kingston, Jamaica. Ninety-nine eyes were treated with scatter photocoagulation and 75 eyes served as controls. The average length of follow-up was 42 months for the control eyes and 47 months for the treated eyes. Prolonged loss of visual acuity was statistically significantly reduced in the treated eyes. The incidence of vitreous hemorrhage was also significantly reduced in the treated eyes after controlling for the previously defined risk factors of vitreous hemorrhage and extent of proliferative sickle cell retinopathy at entry into the study. There were no complications associated with argon laser scatter photocoagulation. Scatter photocoagulation of proliferative sickle cell retinopathy is currently the most effective and safe way to treat patients with sea fan neovascularization.

Aminocaproic acid versus prednisone for the treatment of traumatic hyphema. A randomized clinical trial.

One hundred twelve patients who sustained hyphema after blunt trauma were enrolled in a double-blind randomized clinical trial to determine the relative efficacies of aminocaproic acid (Amicar) and systemic prednisone for reducing the rate of secondary hemorrhage. Fifty-six patients received an oral dosage of 50 mg/kg of aminocaproic acid every 4 hours for 5 days, up to a maximum of 30 g daily, and 56 patients received an oral dosage of 40 mg of prednisone daily (adjusted for weight) in two divided doses. Placebo pills and liquids were given to each patient to mask the treatment schedules. There were no statistically significant differences between the patient populations for any demographic or clinical characteristic (e.g., visual acuity, intraocular pressure [IOP], initial hyphema size) measured in the study. Blacks comprised 53% of the study population, and the mean age of the patients was 23.5 years. Four patients in each of the treatment groups experienced a secondary hemorrhage; the rebleed rate was 7.1% in each group.

Intraocular tissue plasminogen activator in a rabbit model of traumatic hyphema.

Tissue plasminogen activator was used to evaluate the clearance of traumatic hyphema in a rabbit model. A neodymium-YAG laser was used to disrupt iris vessels, creating a traumatic hyphema. Tissue plasminogen activator (1800 IU/0.1 mL) was injected into the anterior chamber 24 hours after creation of the hyphema. Two control groups (one receiving balanced salt solution and one receiving no treatment) were used for comparison. A multivariate analysis of covariance indicated that the greatest difference in hyphema clearance between the groups occurred at days 3, 4, and 5. Five days after tissue plasminogen activator treatment, the mean size of the clot remaining in the anterior chamber was 27% of that of the original hyphema. In control eyes, almost 60% of the original clot remained at day 5. Treatment of animals with tissue plasminogen activator doses of 5000 IU and 10,000 IU produced a substantial increase in repeated bleeding episodes in our rabbit model. We concluded that although the use of tissue plasminogen activator in our rabbit model of traumatic hyphema significantly improved clearance of blood from the anterior chamber, the remaining clot was of such size that the clinical benefit was questionable.

Comparison of the effects of two viscoelastic agents, Healon and Viscoat, on postoperative intraocular pressure after penetrating keratoplasty.

Sixty-two patients undergoing penetrating keratoplasty were randomized to receive Healon (1% sodium hyaluronate) or Viscoat (3% sodium hyaluronate and 4% chondroitin sulfate) as a means of maintaining the anterior chamber during surgery. Neither viscoelastic agent was irrigated from the eye at the end of the procedure. Intraocular pressures (IOPs) were measured at 4, 10, 24, and 72 hours postoperatively. For the Healon group, IOPs were 16.52, 23.50, 28.31, 23.27, and 16.03 mm Hg at baseline and at the four follow-up periods, respectively. For the Viscoat group, they were 19.10, 28.33, 23.48, 18.62, and 16.17 mm Hg at those points, respectively. IOPs were significantly elevated over baseline in the Healon group at 4, 10, and 24 hours, and in the Viscoat group at 4 and 10 hours. There were no statistically significant differences between the Healon and Viscoat groups at 4, 10, and 72 hours. At 24 hours, the Healon group had a mean pressure rise over baseline of 6.5 mm Hg, while the Viscoat group had returned to baseline levels (P = .02). We conclude that both Healon and Viscoat raise postoperative IOPs, but that Healon appears to elevate IOPs for a longer period after surgery than Viscoat.

Effects of topical glaucoma drugs on fistulized rabbit conjunctiva.

Conjunctival fibroblastic proliferation with contracting scar formation has been implicated as a possible cause of glaucoma filtering surgery failure. The effects of glaucoma medications on bulbar conjunctiva were evaluated in both eyes of 20 pigmented rabbits, with 5 rabbits per group each receiving singular topically applied daily doses of either 0.5% timolol, 1% epinephrine, 4% pilocarpine, or artificial tears in a masked fashion for 4 months. Posterior lip sclerectomies were performed in 16 rabbits--4 from each treatment group. The remaining four rabbits served as nonsurgical controls. Four additional rabbits, which had not received eye drops, were included as a nonmedicated control group, with one rabbit serving as a nonsurgical control. Immunostaining was performed to identify the presence of myofibroblasts in fistulized conjunctiva. Treated surgical eyes, regardless of medication, had higher myofibroblastic cell proliferation than treated nonsurgical eyes. Among fistulized eyes, all medications increased cell proliferation, with pilocarpine eliciting the most dramatic increase compared with all other groups.

Retinal arterial macroaneurysms: risk factors and natural history.

A case control study was conducted to identify the systemic and ocular risk factors for retinal arterial macroaneurysms. Forty-three patients with 52 photographically confirmed macroaneurysms were located. Forty-three age-matched, race-matched concurrent control patients were also identified. The patients with macroaneurysms had decreased visual acuity (p less than 0.0001) and a higher prevalence of hypertension (p = 0.037), female sex (p = 0.099), and retinal vein occlusions (p = 0.055) than controls. In patients with both a macroaneurysm and venous occlusion there was a 12.0 times higher prevalence of macroaneurysms in the area of retina drained by the occluded vein (p less than 0.05). Common findings associated with macroaneurysms included retinal haemorrhage (81% of patients), retinal exudate (70%), vitreous haemorrhage (30%), macular involvement (30%), and distal arteriolar narrowing (26%). Arteriolar occlusion occurred spontaneously (8%) or after laser photocoagulation (16%).

Assessment of intraocular pressure in vitrectomized gas-containing eyes. A clinical and manometric comparison of the Tono-Pen to the pneumotonometer.

Elevation of intraocular pressure (IOP) in gas-containing eyes occurs not infrequently, and applanation tonometry in eyes with epithelial irregularities is not accurate. The pneumotonometer and TonoPen (Oculab, La Jolla, Calif) are alternative tonometers for use in these eyes, yet the accuracy of determining IOP with the Tono-Pen has not been determined manometrically. We performed a clinical and manometric study comparing the Tono-Pen with the pneumotonometer in gasfilled vitrectomized eyes. In our clinical study, we measured IOP in 50 eyes of 50 patients with corneal irregularities following vitrectomy and air/gas-fluid exchange. Tono-Pen measurements were highly correlated with those of the pneumotonometer. However, there was a mean difference of 1.4 mm Hg between Tono-Pen and pneumotonometer IOP readings. A larger percentage of Tono-Pen readings were lower than those of the pneumotonometer as IOP levels increased. To assess the accuracy of these tonometers, we compared manometric readings via an indwelling catheter with Tono-Pen and pneumotonometer IOP readings in 11 eye bank eyes following a lensectomy, vitrectomy, and air-fluid exchange. Overall, Tono-Pen and pneumotonometer readings were highly correlated with those of the manometer. However, both machines showed a significant underestimation of IOP at pressures greater than or equal to 30 mm Hg; pneumotonometer and Tono-Pen readings averaged 10.2 and 12.1 mm Hg lower, respectively, than those of the manometer. We conclude that both the pneumotonometer and the Tono-Pen underestimate IOP at pressures greater than or equal to 30 mm Hg.(ABSTRACT TRUNCATED AT 250 WORDS)