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Biomedical subjects

L A Wilson

Publications and source records attributed to L A Wilson.

At least 109 records · Page 6Linked to original sources
PubMed1987

Association of Pseudomonas and Serratia corneal ulcers with use of contaminated solutions.

The wetting and soaking solutions and contact lens cases of eye clinic patients commonly were contaminated with gram-negative bacteria during their use. Serratia marcescens occurred most frequently in preserved solutions, whereas Pseudomonas aeruginosa was most often recovered from home-prepared saline. The bacteria were recovered at densities of greater than 10(6) cells per ml and typically persisted in the solutions. Eight patients who developed bacterial keratitis during 1986 used solutions contaminated with the etiological agents of the infections. Improper hygienic practices of the patients and failure of some preservative systems were implicated in the development of the infections.

Adult↗
PubMed1987

Acanthamoeba keratitis. A growing problem in soft and hard contact lens wearers.

Eleven contact lens-wearing patients presented with Acanthamoeba keratitis. Eight cases were culture- and/or stain-positive for Acanthamoeba and three were presumed to have Acanthamoeba keratitis based on history and clinical findings. Six wore daily wear soft contact lenses, two wore extended-wear soft contact lenses, one wore a polymethylmethacrylate hard contact lens, one wore a gas-permeable hard contact lens, and one wore a Saturn lens (combined hard and soft lens). Four patients used distilled water and salt tablet saline, three used tap water and salt tablet saline, two used tap water rinse, two used well water rinse or storage, and one used intravenous (IV) saline. It is apparent that all contact lens wearers are at some risk for Acanthamoeba keratitis developing if proper contact lens care is not maintained. Of great concern is the inability of most current chemical sterilization methods to kill the organism if the lens becomes contaminated. Heat disinfection will kill Acanthamoeba trophozoites and cysts but the lens must not be placed into contaminated solutions afterward. Prevention is very important because medical and surgical treatment failures are frequent. Eye care practitioners who fit contact lenses are advised to use heat disinfection for low-water content stock soft contact lenses, and to use hydrogen peroxide without a catalyst for a minimum of 6 hours for all other stock lens fitting sets, to specifically inquire about contact lens care habits used by their patients, and to discourage the use of homemade saline solutions.

Acanthamoeba↗
PubMed1986

Association of fungi with extended-wear soft contact lenses.

Fungi were isolated from 11 extended-wear soft contact lenses. In two cases, fungi had penetrated through the contact lens and the same fungus was cultured from corneal ulcers. In four cases, fungal growth on and in the soft contact lens matrix was associated with conjunctivitis and punctate fluorescein staining of the corneal epithelium.

Contact Lenses↗
PubMed1986

Rapid diagnosis of Acanthamoeba keratitis from corneal scrapings using indirect fluorescent antibody staining.

Two soft contact lens wearers using a homemade saline solution developed corneal stromal inflammation and epithelial ulceration and were both treated for months with a presumptive diagnosis of herpes simplex keratitis. Subsequently, corneal scrapings revealed refractile, cystic structures consistent with the appearance of Acanthamoeba. This was rapidly confirmed by indirect fluorescent antibody studies, and Acanthamoeba castellani was later identified by growth in culture in both cases. Acanthamoeba is being reported with increasing frequency as a pathogen responsible for chronic stromal keratitis and ulceration in contact lens wearers. Since specific therapy is required to control this organism, rapid diagnosis is essential. Indirect fluorescent antibody staining of corneal scrapings provides a simple means of accomplishing this goal with a high degree of accuracy.

Adolescent↗
PubMed1986

The triple procedure. Analysis of outcome, refraction, and intraocular lens power calculation.

Presented are the results of 66 consecutive, elective, combined procedures of penetrating keratoplasty, extracapsular cataract extraction, and intraocular lens insertion (triple procedure) performed by three surgeons between January 1981 and January 1984. After a mean postoperative followup of 15.8 months, over 90% of the eyes had clear grafts, and of the 56 eyes with good preoperative visual potential, 77% achieved a best corrected visual acuity of 20/40 or better. The postoperative mean refractive deviation from emmetropia was 2.17 diopters, with a range of +6.62 D to -5.50 D, 62% falling between -2.00 and +2.00 diopters. Using multiple regression analysis of preoperative and postoperative variables, an attempt was made to derive a predictive formula for the power of the intraocular lens to be implanted during the triple procedure. In contrast to cataract surgery, where axial length and corneal power remain fairly constant preoperatively and postoperatively, penetrating keratoplasty produces marked changes in corneal curvature and power. Therefore, a single formula could not be derived to predict accurately the intraocular lens power for the patients. However, using the results for an individual surgeon, a formula was derived that could improve the predictability of intraocular lens power.

Aged↗
PubMed1986

Morphology and ultrastructure of fungi in extended-wear soft contact lenses.

Filamentous fungi of the genera Acremonium, Aspergillus, Alternaria, Cladosporium, Curvularia, and Fusarium penetrated the matrix of soft contact lenses both during normal usage and in laboratory studies. Growth of the fungi within the lens matrix increased with increasing water content of the lens. Hyphae within the lens were coiled. Some species penetrated completely through the lens within 96 h. More frequent cleaning and disinfection of extended-wear soft contact lenses is recommended.

Acremonium↗
PubMed1986

Antibiograms, serotypes, and plasmid profiles of Pseudomonas aeruginosa associated with corneal ulcers and contact lens wear.

Pseudomonas aeruginosa was isolated from the corneal scrapings of 11 of 14 patients with gram-negative corneal ulcers and from salt tablet-prepared saline solutions from 6 of these patients wearing soft contact lenses. Comparison of physiological properties, antibiograms, serotypes, and plasmid profiles for five of the patients indicated that the isolates from the ulcer and the saline solution of a given patients were of the same strain. Improper hygienic practices of contact lens wearers appeared to be a major factor in the epidemiology of pseudomonad corneal ulcers.

Adult↗
PubMed1986

Lipoprotein lipase-suppressing mediator in serum of endotoxin-treated rats.

The conditions under which lipoprotein lipase-suppressing mediator is present in serum of endotoxin-treated rats was determined in this study. The suppression of lipoprotein lipase activity in 3T3-L1 cells was used as a bioassay for mediator in serum. Endotoxin (0.1-10 micrograms/ml) and serum from control rats did not suppress lipoprotein lipase activity. Maximum suppression of cell lipoprotein lipase activity (70%) by serum from endotoxic rats required a cell exposure time of 5 h. At the highest dose of endotoxin used (1 mg/100 g), significant suppression was achieved when cells were incubated with 0.5% serum from endotoxic rats (P less than 0.05). Serum obtained 2-3 h after endotoxin injection possessed the maximal ability to suppress lipase activity, but suppressing activity was not present in serum collected 8 h after endotoxin. Rats rendered tolerant to endotoxin by 5 daily injections (0.1 mg/100 g) did not contain detectable levels of mediator in serum after endotoxin injection. The results demonstrate that the presence of lipoprotein lipase activity-suppressing mediator is transitory after in vivo exposure of naive rats to endotoxin, but does not appear in serum of endotoxin tolerant rats.

Animals↗
PubMed1986

Immunological and colorimetric determination of prostatic acid phosphatase--technical and clinical reappraisal in symptomatic patients.

We compared a selection of quantitative immunological methods for prostatic acid phosphatase (PAP) with routine colorimetric assays for total and tartrate-labile acid phosphatase and evaluated their relative clinical merits in the differential diagnosis of prostatic carcinoma. We also assessed a wide range of commercial control materials for suitability of use with these methods. Patients studied included 111 cases of prostatic carcinoma, 42 cases of benign prostatic hyperplasia, and 33 controls. The principles of the methods used included determination of enzymatic activity using p-nitrophenyl phosphate, RIA, immunoradiometric, and enzymoimmunometric assays. Performance characteristics for the immunological methods were inferior to manufacturers' precision and specificity claims. We identified control materials that were unsuitable for routine use. Poor discrimination between clinical groups was observed for all methods. Analysis by use of a receiver operator characteristic plot failed to improve this. We conclude that the immunological methods we studied offer no advantages over colorimetric methods in the differential diagnosis of prostatic cancer in symptomatic patients.

Acid Phosphatase↗
PubMed1986

The University of California Biomechanics Laboratory four-bar polycentric knee linkage. A clinical trial in 20 active above-knee amputees.

A four-bar polycentric prosthetic knee linkage developed by the University of California Biomechanics Laboratory (UCBL) was tested clinically in 20 active veteran above-knee amputees. The mean follow-up period was 12.3 months. At final follow-up evaluation, positive subjective responses were reported by 80% of the amputees. More than one-third reported that the device was superior to any that they had used previously. Almost all subjects found that prior levels of daily activity and the ability to perform specific activities were maintained or enhanced. The increase in knee flexion afforded by the mechanism was found to be an advantage. There was no significant change in various fundamental gait parameters. Problems caused by excessive wear of anodized aluminum linkage pins and by air leaks in the pneumatic swing-phase control unit were corrected easily. These preliminary results encourage further clinical application and study of the UCBL four-bar polycentric knee.

Adult↗
PubMed1985

Slit-lamp microscopic appearance of corneal wound healing after radial keratotomy.

Radial keratotomy offers a unique opportunity to study corneal wound healing because the corneas are normal, the fine knife blades disrupt adjacent tissue minimally, no sutures are used, there is minimal inflammation, and few postoperative drugs are administered. We studied corneal wounds with a slit-lamp microscope as they healed from two weeks to three years after radial keratotomy in 84 eyes of 51 consecutive patients enrolled in the Prospective Evaluation of Radial Keratotomy (PERK) Study. One day after surgery, the incisions were surrounded by edema. At two weeks, a dense, gray, diffusely marginated opacity occupied 0.1 mm on both sides of the incision. At three months, the area adjacent to the incision was filled with discrete, fine, gray spicules that protruded at right angles from the incision. At six months, the gray cloudiness had completely disappeared, and the individual spicules were more prominent. By one year, the spicules were disappearing from the anterior portion of the incision and were concentrated primarily in the posterior part of the incisions. At two and three years, the incision scar was fainter and the spicules had disappeared from all but the deep posterior part of the wound. We believe that these spicules correspond to the reorganization of the stroma along the edges of the corneal incision. The persistence of the spicules suggests that wound healing in radial keratotomy may not be complete until two years or more after surgery.

Cicatrix↗
PubMed1985

Postoperative astigmatism after central vs eccentric penetrating keratoplasties.

Six patients with markedly eccentric penetrating keratoplasties had severe corneal astigmatism (mean, 10.38 +/- 2.91 diopters). In four of these patients the flat meridian was lying in the direction of graft displacement. Laboratory experiments disclosed no statistically significant difference in diameter between the major and minor axes of the corneal buttons in the centrally and eccentrically trephined eyes and we could not elucidate the mechanism of the severe astigmatism. However, in the eccentrically trephined eyes the longer axis consistently lay in the direction of decentration whereas in the centrally trephined eyes the long axis was oriented randomly.

Astigmatism↗
PubMed1985

Gentamicin-resistant Pseudomonas endophthalmitis after penetrating keratoplasty.

A case of pseudomonas endophthalmitis after penetrating keratoplasty is described. Bacterial sensitivities in this case and in five of six previously reported cases of endophthalmitis after corneal transplant showed resistance to gentamicin, an antibiotic routinely used in the transport medium. The recovery of antibiotic resistant bacteria in antibiotic supplemented media is discussed with emphasis on prevention.

Aged↗
PubMed1985

Prescription options for the below knee amputee. A review.

In 1973 a workshop sponsored by the National Academy of Sciences recommended that "efforts to develop prescription criteria for use of the numerous variants of the BK prosthesis should be intensified." This paper provides a review of the important considerations in the prescription of a below-knee prosthesis. It is intended that this information would assist the physician to make better informed decisions regarding the specific type of prosthesis for a particular patient. No attempt has been made to describe all prosthetic options since a majority of amputees are fit with only a few prescriptions. Thus, socket design, suspension, shank type, and foot specification may be optimized for individual patients through mutual agreement of the prosthetist and the knowledgeable physician. This paper will present some of the more difficult prescription solutions to the various fitting problems that are representative of our nation's amputee population. This is done with the knowledge that there may be other and equally successful solutions to these problems. Several illustrative examples are provided.

Adult↗
PubMed1985

Static load response of the heels of SACH feet.

Excessive heel hardness in the prosthetic foot is a frequent problem that may contribute to decreased function in the above knee and below knee amputee. Optimal mechanical characteristics of the SACH (solid ankle cushion heel) foot have not been defined. In an effort to characterize the mechanical properties of the heels of these feet, we performed static load-deformation tests on the heels of SACH feet at stimulated heelstrike. These data were interpreted using least squares fitting of the natural logarithms of the load-deformation data. Statistical comparison of these data revealed no significant difference in the static response of the "medium" and "regular" grades of foot. A difference at the 1% level of confidence was found between the "soft" grade and the two firmer grades. Consistency within a grade of foot was quite good. Comparison of feet from another manufacturer revealed no difference in static response, suggesting consistency in static performance among manufactures. It was our clinical impression that all grades of SACH heels are too stiff.

Artificial Limbs↗