Decreased circulation in the feline choriocapillaris underlying retinal photocoagulation lesions.

PURPOSE: To investigate the effects of argon laser photocoagulation on the choroidal circulation in cats. METHODS: Three sizes of argon laser lesions designed to damage the outer retina were created in six cats: larger than 1 mm, 500 µm, and 200 µm. At least 1 month after the lesions, damage to the choroidal vasculature was studied in two ways. First, scanning laser ophthalmoscopy was used to obtain infrared reflectance (IR) photographs and indocyanine green (ICG) angiograms. Second, fluorescent microspheres (15 µm) were injected into the left ventricle. The globes were fixed, the choroid was flat mounted, and images were taken with a fluorescence microscope. Retinal histology was assessed in comparable lesions. RESULTS: Histology showed that the inner retina was preserved, but the choroid, tapetum, and outer retina were damaged. ICG angiograms revealed choriocapillaris loss in large lesions and in some 500-µm lesions, whereas the larger vessels were preserved; in 200 µm lesions, choriocapillaris loss was not detectable. However, in all lesions, the distribution of microspheres revealed little if any choriocapillaris flow. In larger lesions, the damaged region was surrounded by an area in which the number of microspheres was higher than in the lesion but lower than in the normal retina. CONCLUSIONS: Under lesions that destroyed photoreceptors, the choriocapillaris was also compromised, even when no change could be detected with ICG angiography. Panretinal photocoagulation is designed to increase retinal PO2 by allowing choroidal oxygen to reach the inner retina, but its effectiveness may be limited by damage to the choriocapillaris.

Machine-smoking studies of cigarette filter color to estimate tar yield by visual assessment and through the use of a colorimeter.

This paper explores using the intensity of the stain on the end of the filter ("filter color") as a vehicle for estimating cigarette tar yield, both by instrument reading of the filter color and by visual comparison to a template. The correlation of machine-measured tar yield to filter color measured with a colorimeter was reasonably strong and was relatively unaffected by different puff volumes or different tobacco moistures. However, the correlation of filter color to machine-measured nicotine yield was affected by the moisture content of the cigarette. Filter color, as measured by a colorimeter, was generally comparable to filter extraction of either nicotine or solanesol in its correlation to machine-smoked tar yields. It was found that the color of the tar stain changes over time. Panelists could generally correctly order the filters from machine-smoked cigarettes by tar yield using the intensity of the tar stain. However, there was considerable variation in the panelist-to-panelist tar yield estimates. The wide person-to-person variation in tar yield estimates, and other factors discussed in the text could severely limit the usefulness and practicality of this approach for visually estimating the tar yield of machine-smoked cigarettes.

Effects of photocoagulation on intraretinal PO2 in cat.

PURPOSE: To test the hypothesis that intraretinal Po(2) increases after photocoagulation. METHODS: Anesthetized cats underwent retinal argon laser photocoagulation. At least 4 weeks after treatment, Po(2)-sensitive microelectrodes were used to record intraretinal Po(2) profiles from healed photocoagulation lesions in anesthetized cats breathing air. Histopathologic examination of the retinas was used to confirm that the photoreceptors were destroyed and that the inner retinal layers were preserved, though somewhat disorganized, as in human panretinal photocoagulation (PRP). RESULTS: The retina and tapetum were thinner in the lesioned retina than in the nonphotocoagulated retina. Average Po(2) across the inner 50% of the retina was higher (22 +/- 10 mm Hg) in photocoagulated retina than in untreated retina (14 +/- 7 mm Hg; P < 0.01; n = 13 cats). The minimum Po(2) was also significantly higher, whereas choroidal Po(2) was significantly lower in the photocoagulated retina than in untreated retina. No significant difference was found in the preretinal vitreous. After lesions, inner retinal Po(2) could also be maintained above zero, even in the absence of retinal circulation. CONCLUSIONS: Previous measurements showed increased Po(2) in the preretinal vitreous of rabbits and pigs (but not cats) after photocoagulation of the outer retina. These intraretinal measurements in cats provide further evidence for a chronic increase in inner retinal Po(2) in lesioned areas during air breathing.

Genetic study of familial uveal melanoma: association of uveal and cutaneous melanoma with cutaneous and ocular nevi.

PURPOSE: To evaluate a kindred with familial uveal and cutaneous melanoma and to identify potential genetic and environmental factors that may predispose individuals to develop uveal melanoma. DESIGN: Family-based case report with detailed clinical and genetic evaluation. PARTICIPANTS: Ten siblings in a single nuclear family. METHODS: Evaluation of a large sibship via family history, complete eye and skin examinations, environmental risk factor questionnaire, and genetic testing, as well as a MEDLINE search of familial uveal melanoma kindreds. MAIN OUTCOME MEASURES: Cutaneous and ocular nevi, benign and malignant neoplasms of skin and other sites, brief skin cancer risk assessment tool risk classification for cutaneous melanoma, DNA sequencing of p16INK4a and p14ARF genes, and citations on familial uveal melanoma. RESULTS: The proband and his mother had uveal melanoma, 3 cutaneous melanomas occurred among 2 siblings, and 2 other siblings had basal cell carcinomas. No germline mutations were detected in the melanoma-associated tumor suppressor genes p16INK4a and p14ARF. Seven out of 10 siblings had a history of cutaneous and/or ocular nevi. Of the 3 subjects without nevi, 2 had histories of eye or skin malignancies (1 uveal melanoma, 1 basal cell carcinoma). Three of the 10 siblings had relevant ocular findings (2 choroidal nevi, 1 uveal melanoma). Six were also found to be in the "high-risk" classification for cutaneous malignancies based on scores from a previously validated risk assessment tool. This family, combined with the 91 previously reported familial uveal melanoma kindreds, brings to 92 the total number thus far recorded. CONCLUSIONS: Our results strengthen the association between uveal melanoma, atypical nevi, and cutaneous melanoma. This relationship supports the recommendation that individuals with a personal or family history of uveal melanoma, particularly in combination with atypical nevi, should be regularly screened for uveal and cutaneous melanoma.

Little capsulorhexis tear-out rescue.

Backward traction on the capsule flap forms the basis of a predictable technique for rescuing the capsulorhexis from a radial tear-out.

Does anticoagulation do more harm than good?: A comparison of patients treated without prophylaxis and patients treated with low-dose warfarin after total knee arthroplasty.

A cohort of 785 patients treated without any form of thromboprophylaxis was compared with an identical group of 957 patients treated with 6 weeks of low-dose warfarin. All complications seen within 90 days of surgery were recorded. The control group had a total complication rate of 2.2%, with a death rate from thromboembolic disease of 0.0% and a total death rate of 0.2%. The warfarin group had a total complication rate of 4.7%, with a death rate from thromboembolic disease of 0.0% and a total death rate of 0.1%. Both deaths in the control group were from cardiac disease, while the death in the warfarin group was due to a massive gastrointestinal bleeding. The warfarin group had twice the infection rate of the control group.

Fast HPLC with a silica-based monolithic ODS column.

Fast high-performance liquid chromatography is becoming routine in laboratories that require high throughput or for combinatorial libraries. Reduced analysis time is commonly achieved by using shorter columns and higher flow rates. Shorter columns require smaller particles in order to maintain efficiency. However, smaller particles increase backpressure, which limits both column length and higher flow rates for typical LC pumps. This disadvantage has been addressed by the emergence of monolithic liquid chromatographic columns (1). Unlike particle-base columns, monolithic columns consist of a continuous rod-shaped porous network with a bimodal pore distribution. In this study, a commercially available 50- x 4.6-mm silica-based octadecyl silane monolithic column (Chromolith SpeedROD RP18e, EM Science, Gibbstown, NJ) was used to separate a seven-component test mixture with a wide range of polarity. The primary goals of this investigation were: (a) to study the chemistry (selectivity) of the new silica-based monolithic columns and (b) to study their run-to-run and column-to-column performance (retention times and peak areas). The selectivity (alpha factor) is a ratio of partition coefficients and, if comparable for a variety of solutes, would mean that methods could be readily transferred between particulate and monolithic columns.