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Biomedical subjects

D C Herman

Publications and source records attributed to D C Herman.

At least 19 recordsLinked to original sources
PubMed2001

Increased corneal thickness in patients with ocular hypertension.

BACKGROUND: Central corneal thickness greater than 0.520 mm causes true intraocular pressure to be overestimated when the technique of applanation tonometry is used to measure intraocular pressure. OBJECTIVE: To compare the corneal thickness measurements of patients enrolled in a study of ocular hypertension with those of age-matched control subjects with normal intraocular pressure. METHODS: Central corneal pachymetry using an optical pachymeter was performed on each study subject (n = 55) at baseline and in an independent sample of control subjects. A 2 sample, 2-tailed T test was used to compare the 2 populations. RESULTS: The patients with ocular hypertension had significantly higher mean corneal thickness measurements (mean +/- SD, 0.594 +/- 0.037 mm) than the control group (0.563 +/- 0.027 mm) (P<.001). CONCLUSION: Corneal thickness may be a confounding factor in the measurement of intraocular pressure, and this may modify the risk for progression to glaucoma in patients with ocular hypertension.

Anthropometry↗
PubMed2001

Estimated incidence of open-angle glaucoma in Olmsted County, Minnesota.

PURPOSE: To determine the incidence rates of open-angle glaucoma (OAG) in Olmsted County, MINNESOTA: DESIGN: Retrospective population-based estimate of incidence. PARTICIPANTS: From the medical histories of 60,666 residents of Olmsted County, Minnesota, who had ocular diagnoses during the study period, 114 subjects with newly diagnosed OAG were identified. METHODS: The database of the Rochester Epidemiology Project was used to identify all Olmsted County residents with a coded diagnosis of OAG, glaucoma suspect, or ocular hypertension during the period 1965 to 1980. Subjects newly diagnosed with and treated for OAG who also had documented clinical evidence of elevated intraocular pressure, optic nerve damage, and/or visual field loss consistent with glaucoma were included as incident cases. Population data for Olmsted County were drawn from United States Census data. Crude incidence data were adjusted to the age and gender distribution of the 1990 United States white population. MAIN OUTCOME MEASURES: Estimated incidence rates of OAG. RESULTS: The overall age- and gender-adjusted annual incidence rate of OAG in a predominantly Caucasian population is conservatively estimated to be 14.5 per 100,000 population. The rates increased with age from 1.6 in the fourth decade of life to 94.3 in the eighth decade. There was no significant difference in incidence by gender. The average annual rate of OAG in the last 2 years of the study was 27.7 compared with 12.3 before 1979. This difference is suggestive of the effect of the introduction of a new medical therapy (timolol) for OAG during the last 2 years. CONCLUSIONS: The incidence rates of OAG increase markedly with advancing age, and screening efforts should be targeted at both men and women in the older age groups. The advent of new diagnostic and therapeutic modalities can have an effect on incidence rates.

Adolescent↗
PubMed2000

Reducing the progression of myopia with atropine: a long term cohort study of Olmsted County students.

BACKGROUND: Myopia is an important public health problem because it is common and is associated with increased risk for chorioretinal degeneration, retinal detachment, and other vision- threatening abnormalities. In animals, ocular elongation and myopia progression can be lessened with atropine treatment. This study provides information about progression of myopia and atropine therapy for myopia in humans. METHODS: A total of 214 residents of Olmsted County, Minnesota (118 girls and 96 boys, median age, 11 years; range 6 to 15 years) received atropine for myopia from 1967 through 1974. Control subjects were matched by age, sex, refractive error, and date of baseline examination to 194 of those receiving atropine. Duration of treatment with atropine ranged from 18 weeks to 11.5 years (median 3.5 years). RESULTS: Median followup from initial to last refraction in the atropine group (11.7 years) was similar to that in the control group (12.4 years). Photophobia and blurred vision were frequently reported, but no serious adverse effects were associated with atropine therapy. Mean myopia progression during atropine treatment adjusted for age and refractive error (0.05 diopters per year) was significantly less than that among control subjects (0.36 diopters per year)(P<.001). Final refractions standardized to the age of 20 years showed a greater mean level of myopia in the control group (3.78 diopters) than in the atropine group (2.79 diopters) (P<.001). CONCLUSIONS: The data support the view that atropine therapy is associated with decreased progression of myopia and that beneficial effects remain after treatment has been discontinued.

Adolescent↗
PubMed1999

Probability of filtration surgery in patients with open-angle glaucoma.

OBJECTIVE: To investigate the probability of undergoing filtration surgery in either 1 or both eyes in patients in whom open-angle glaucoma was newly diagnosed. METHODS AND DESIGN: A retrospective community-based study of 295 residents of Olmsted County, Minnesota, in whom open-angle glaucoma was newly diagnosed between January 1, 1965, and December 31, 1980, was performed. Kaplan-Meier methods were used to estimate the cumulative probability of undergoing filtration surgery during a 20-year period. RESULTS: At 20 years of follow-up, the Kaplan-Meier cumulative probability of undergoing filtration surgery in at least 1 eye was estimated to be 23% (95% confidence interval, 16%-30%), and in both eyes the estimate was 12% (95% confidence interval, 6%-17%). Patients with optic nerve damage at the time of diagnosis were more likely to undergo surgery than patients with elevated intraocular pressure but no damage (1 eye, 39% vs 15%; both eyes, 27% vs 5%). CONCLUSION: This retrospective study of a white population newly diagnosed as having and treated for open-angle glaucoma indicates that while most patients did not undergo filtration surgery in the course of glaucoma therapy, at least one third of those with glaucomatous damage at the time of diagnosis underwent filtration surgery.

Aged↗
PubMed1998

The probability of blindness from open-angle glaucoma.

OBJECTIVE: This study aimed to determine the probability of a patient developing legal blindness in either one or both eyes from newly diagnosed and treated open-angle glaucoma (OAG) after starting medical or surgical therapy or both. DESIGN: The study design was a retrospective, community-based descriptive study. PARTICIPANTS: Two hundred ninety-five residents of Olmsted County, Minnesota, newly diagnosed with, and treated for, OAG between 1965 and 1980 with a mean follow-up of 15 years (standard deviation +/- 8 years) participated. INTERVENTION: Kaplan-Meier cumulative probability of blindness was estimated for patients treated and followed for OAG. MAIN OUTCOME MEASURES: Legal blindness, defined as a corrected visual acuity of 20/200 or worse, and/or visual field constricted to 20 degrees or less in its widest diameter with the Goldmann 1114e test object or its equivalent on automated perimetry, secondary to glaucomatous loss, was measured. RESULTS: At 20-years' follow-up, the Kaplan-Meier cumulative probability of glaucoma-related blindness in at least one eye was estimated to be 27% (95% confidence interval, 20%-33%), and for both eyes, it was estimated to be 9% (95% confidence interval, 5%-14%). At the time of diagnosis, 15 patients were blind in at least 1 eye from OAG. CONCLUSION: A retrospective study of a white population determined that the risk of blindness from newly diagnosed and treated OAG may be considerable.

Aged↗
PubMed1997

Adverse side effects associated with latanoprost.

PURPOSE: To report three different adverse reactions after initiating treatment with latanoprost. METHOD: Serial clinical examinations of three patients were performed. RESULTS: Adverse reactions such as ocular hypotony and choroidal effusions, recurrent cystoid macular edema, and facial rash were noted to occur within 1 to 4 weeks after starting topical latanoprost for the treatment of primary open-angle glaucoma. CONCLUSION: Clinicians should be alerted to these possible complications of topical latanoprost therapy.

Aged↗
PubMed1997

Rhamnolipid (biosurfactant) effects on cell aggregation and biodegradation of residual hexadecane under saturated flow conditions.

The objective of this research was to evaluate the effect of low concentrations of a rhamnolipid biosurfactant on the in situ biodegradation of hydrocarbon entrapped in a porous matrix. Experiments were performed with sand-packed columns under saturated flow conditions with hexadecane as a model hydrocarbon. Application of biosurfactant concentrations greater than the CMC (the concentration at which the surfactant molecules spontaneously form micelles or vesicles [0.03 mM]) resulted primarily in the mobilization of hexadecane entrapped within the sand matrix. In contrast, application of biosurfactant concentrations less than the CMC enhanced the in situ mineralization of entrapped hexadecane; however, this effect was dependent on the choice of bacterial isolate. The two Pseudomonas isolates tested, R4 and ATCC 15524, were used because they exhibit different patterns of biodegradation of hexadecane, and they also differed in their physical response to rhamnolipid addition. ATCC 15524 cells formed extensive multicell aggregates in the presence of rhamnolipid while R4 cells were unaffected. This behavior did not affect the ability of the biosurfactant to enhance the biodegradation of hexadecane in well-mixed soil slurry systems but had a large affect on the extent of entrapped hexadecane biodegradation in the sand-packed-column system that was used in this study.

Alkanes↗
PubMed1995

Safety of a clean air storage hood for ophthalmic instruments in the operating room.

PURPOSE: Evaluation of the safety of a laminar flow clean air hood for the sterile storage of ophthalmic instruments in an operating room. METHODS: A ten-year retrospective study of 10,524 surgical procedures performed with instruments stored in a clean air hood was conducted at the Mayo Clinic. Cases of postoperative endophthalmitis were identified through review of the diagnostic indices maintained by the ophthalmology department and the institution and through review of individual patient records. RESULTS: The incidence of endophthalmitis in surgical cases in which instruments stored in a clean air hood were used was 0.076% (eight of 10,524 cases). No clusters of infection were identified. CONCLUSIONS: The use of a laminar flow clean air hood provides access to surgical instruments in a high-volume operating room without exposing patients to an increased risk of endophthalmitis.

Endophthalmitis↗
PubMed1994

Biodegradation of naphthenic acids by microbial populations indigenous to oil sands tailings.

Organic acids, similar in structure to naphthenic acids, have been associated with the acute toxicity of tailings produced by the oil sands industry in northeastern Alberta, Canada. Bacterial cultures enriched from oil sands tailings were found to utilize as their sole carbon source both a commercial mixture of naphthenic acids and a mixture of organic acids extracted from oil sands tailings. Gas chromatographic analysis of both the commercial naphthenic acids and the extracted organic acids revealed an unresolved "hump" formed by the presence of many overlapping peaks. Microbial activity directed against the commercial mixture of naphthenic acids converted approximately 50% of organic carbon into CO2 and resulted in a reduction in many of the gas chromatographic peaks associated with this mixture. Acute toxicity testing utilizing the Microtox test revealed a complete absence of detectable toxicity following the biodegradation of the naphthenic acids. Microbial activity mineralized approximately 20% of the organic carbon present in the extracted organic acids mixture, although there was no indication of a reduction in any gas chromatographic peaks with biodegradation. Microbial attack on the organic acids mixture reduced acute toxicity to approximately one half of the original level. Respirometric measurements of microbial activity within microcosms containing oil sands tailings were used to provide further evidence that the indigenous microbial community could biodegrade naphthenic acids and components within the extracted organic acids mixture.

Acinetobacter calcoaceticus↗
PubMed1993

Optic nerve sheath decompression for visual loss in patients with acquired immunodeficiency syndrome and cryptococcal meningitis with papilledema.

Visual dysfunction developing in association with acquired immunodeficiency syndrome (AIDS) can be multifactorial. Two patients with this syndrome and cryptococcal meningitis had papilledema and visual loss. Both were treated by optic nerve sheath fenestration. One patient had bilateral nonsimultaneous optic nerve sheath fenestrations; visual function improved in one eye. The other patient had bilateral visual improvement after a unilateral optic nerve sheath fenestration. Cryptococcal organisms were present in the dural sheath specimens of both patients despite ongoing therapy with antifungal medication. Postoperative orbital infectious complications did not occur. Autopsy examination of one patient showed that the sites of fenestration were patent. Medical treatment of cryptococcal meningitis associated with AIDS has a guarded prognosis. Optic nerve sheath fenestration offers a treatment alternative for papilledema and visual loss that occur with cryptococcal meningitis.

AIDS-Related Opportunistic Infections↗
PubMed1993

Starvation-survival of a p-nitrophenol-degrading bacterium.

An environmental actinomycetes, capable of utilizing p-nitrophenol as its sole carbon and nitrogen source, was starved for an 8-week period and showed no reduction in its ability to biodegrade p-nitrophenol. Microscopic examination revealed that starvation of the bacterium resulted in the fragmentation of filaments into individual cells.

Actinomycetaceae↗
PubMed1993

Biodegradation of cycloalkane carboxylic acids in oil sand tailings.

The biodegradation of both an n-alkane and several carboxylated cycloalkanes was examined within tailings produced by the extraction of bitumen from the Athabasca oil sands. The carboxylated cycloalkanes examined were structurally similar to naphthenic acids that have been associated with the acute toxicity of oil sand tailings. The biodegradation potential of naphthenic acids was estimated by determining the biodegradation of both the carboxylated cycloalkanes and hexadecane in oil sand tailings. Carboxylated cycloalkanes were biodegraded within oil sand tailings, although compounds with methyl substitutions on the cycloalkane ring were more resistant to microbial degradation. Microbial activity against hexadecane and certain carboxylated cycloalkanes was found to be nitrogen and phosphorus limited.

Alkanes↗