An infant surgical table for laser photocoagulation: ergonomic improvement analysis.

Current methods of treatment for retinopathy of prematurity, using laser photocoagulation, require surgeons to assume awkward standing positions, which can result in occupational injury. A new infant surgical table was designed for improving this surgical procedure. To quantify its benefits, an ergonomic comparison of the standard and modified procedures was carried out, using specialized checklists, Nordic Musculoskeletal Questionnaires, and analysis of videotaped procedures using an Ovako Working Posture Analysing System method. Analysis of the typical laser photocoagulation procedure revealed a high risk for cumulative trauma disorders. The majority of the risk factors were lowered considerably with use of the new table. Improvement was largely due to the new table allowing seated postures during surgery, relieving muscular stress on the back, shoulders and legs. This study demonstrates risk reduction through engineering design of new medical devices, and illustrates how combining different assessment approaches can help evaluate ergonomic impact of medical technologies.

Prostaglandin analogs in the treatment of glaucoma.

Prostaglandin (PG) analogs are some of the most recent additions to the list of ocular hypotensive medications. Two analogs of naturally occurring PGs are available commercially, isopropyl unoprostone (Rescula [Ciba Vision, Atlanta, GA]) and latanoprost (Xalatan [Pharmacia & Upjohn, Bridgewater, NJ]). Presently, latanoprost 0. 005% is the only PG analog commercially available in the United States. These agents have been shown to be the most effective topical medications for reducing intraocular pressure. They have a different mechanism of action than other ocular hypotensives, and act primarily by increasing uveoscleral outflow. Because of this, PGs have a substantial additive effect when used with agents that reduce aqueous production (eg, beta blockers or carbonic anhydrase inhibitors) or that increase trabecular outflow facility (eg, pilocarpine). Local side effects include mild conjunctival hyperemia and local irritation, darkening of iris color, increased growth of eyelashes, and a possible association with cystoid macular edema or iritis in some patients with other risk factors. No systemic side effects have been proven to be caused by latanoprost. Recommended dosing is once daily at bedtime.

Diffusion of volatile organics through contact lenses.

The purpose of this study was to determine the effect of contact lenses on the exposure of eyes to vapors of organic solvents. Vials of normal saline with and without contact lens barriers were exposed to known concentrations of vapors of acetone, diethyl ether, trichloroethylene (TCE), and toluene. Uptake in vials with hydrogel polymacon (38% water content) lens interfaces was consistently lower than in control vials for exposure times of 2 minutes to 4 hours. Average concentrations were 54%, 26%, 28%, and 25% of the control for acetone, ethyl ether, TCE, and toluene, respectively. After removal from the test chambers, vials with polymacon lenses in place retained ethyl ether, TCE, and toluene significantly longer than control vials without lenses, and concentrations were generally equal in experimental and control vials 24 hours after removal. Uptake across rigid gas permeable lenses (RGP) (silicone/acrylate and fluoropolymer) and hydrogel lenses (polymacon, vifilcon A and etafilcon A) was positively correlated with the water content of the lenses. Uptake across hydrogel lenses ranged from approximately 10 to over 100 times the uptake across RGP lenses for all test compounds except acetone after exposure times of 4 minutes and 30 minutes. Based on these data, we conclude that contact lenses worn in environments containing volatile organic solvents may decrease the exposure of the eye to these compounds.

Seasonal occurrence of rotavirus in sewage.

A seasonal distribution was observed for rotaviruses in sewage by using indirect immunofluorescence. Levels were low from May through September and generally higher during winter and spring. In contrast, no seasonal pattern was observed for total enteroviruses. Limitations of the indirect immunofluorescence assay and enzyme immunoassay for environmental samples are discussed.

Evaluation of a commercial enzyme immunoassay kit for rotavirus detection.

A commercial enzyme immunoassay kit (Rotazyme) was compared to electron microscopy for the detection of rotavirus in stool specimens collected during diarrhea outbreaks at day care centers in Houston. EIA was more sensitive than EM and detected SA-11 rotavirus which titered 2.0 X 10(3) PFU/ml.

Reduction of cytotoxicity in virus concentrates from environmental samples.

The reduction of cytotoxicity in virus concentrates from environmental samples was accomplished by high-speed centrifugation and by filtration of the samples through positively charged depth filters.

Distribution of viruses associated with particles in waste water.

The distribution of solids-associated viruses in wastewater was studied to determine the effect of treatment processes on viruses associated with solids. Solids less than 0.3 micrometers in diameter were separated from the liquid phase of each sample by using a continuous-flow centrifuge. The percentage of virus associated with solids larger than 0.3 micrometers decreased from 28% in the influent to 3.4% in unchlorinated effluent, and this was accompanied by a 92% decrease in the total concentration of virus. These results indicate that the original solids-associated virus as well as that is secondarily adsorbed to mixed liquor-suspended solids is lost during clarification. The total concentration of virus was reduced by 82% by chlorination, and the percentage of virus associated with solids increased to 7.7% upon chlorination, indicating some protection due to association with particles larger than 0.3 micrometers. When a suspension of fecal particles and a 0.22-micrometers filtrate of a fecal homogenate were sonicated, a threefold increase in virus titer was observed in each. This demonstrated that viruses may be attached to particles smaller than 0.22 micrometers. Thus, small viral aggregates or viruses attached to submicron particles represented the major portion of solids-associated virus in treated sewage.

Uptake and survival of enteric viruses in the blue crab, Callinectes sapidus.

Uptake of poliovirus 1 by the blue crab, Callinectes sapidus, was measured to assess the likelihood of contamination by human enteric viruses. Virus was found in all parts of the crab within 2 h after the crab was placed in contaminated artificial seawater. The highest concentrations of virus were found in the hemolymph and digestive tract, but the meat also contained virus. The concentration of virus in the crabs was generally less than in the surrounding water. Changes in salinity did not substantially affect the rate of accumulation. An increase in temperature from 15 to 25 degrees C increased the rates of both uptake and removal. Poliovirus survived up to 6 days in crabs at a temperature of 15 degrees C and a salinity of 10 g/kg. When contaminated crabs were boiled, 99.9% of poliovirus 1, simian rotavirus SA11, and a natural isolate of echovirus 1 were inactivated within 8 min. These data demonstrate that viruses in crabs should not pose a serious health hazard if recommended cooking procedures are used.

Water-to-Air Fractionation of Bacteria.

Differences in the ability of bacterial species to be transported from water to air by bursting bubbles were investigated. Bubbles were generated in suspensions of mixed bacterial cultures, and the concentration was measured for each species in the top jet drop ejected. This concentration divided by the concentration in the bulk menstruum is the concentration factor (CF). Bubbles were generated 2 cm below the liquid surface, and jet drops with diameters from 34 to 136 mum were studied. Serratia marinorubra and Micrococcus euryhalis had CFs which were generally 10 to 100 times greater than those of Escherichia coli, Pseudomonas bathycetes, and spores of Bacillus subtilis. P. bathycetes never had a CF significantly greater than 1 at any drop size, and spores of B. subtilis had a maximum CF of 4. E. coli had a maximum CF of 6 for 1- or 2-day old cultures, but this increased to 80 when a 5-day-old culture was used. This change in the CF with age of the cells indicates that composition of the cell may be a factor influencing its ability to concentrate in jet drops.

Survival of poliovirus within organic solids during chlorination.

Poliovirus in fecal homogenates was used to determine the protection against inactivation by chlorination afforded virus that was occluded within particulates. Virus that was closely associated with or occluded within small fecal particulates was protected. A fourfold increase in combined residual chlorine was required to achieve the same degree of inactivation for occluded virus as for free or secondarily adsorbed virus. A combined chlorine residual of 6.6 mg/liter was necessary to achieve 50% inactivation in 15 min at pH 8.0 and 22 degrees C in a particulate suspension containing occluded virus compared to 1.4 mg/liter for free virus. These differences were found to be relatively small compared to differences due to the presence of dissolved organics or between free and combined chlorine residuals. The results suggest different mechanisms of protection due to adsorption and occlusion.