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Biomedical subjects

W H Benson

Publications and source records attributed to W H Benson.

At least 37 records · Page 2Linked to original sources
PubMed1992

Comparison of techniques for culturing corneal ulcers.

All consecutive cases of presumed microbial keratitis were cultured with both a platinum spatula and calcium alginate swab moistened with trypticase soy broth. Ten (77%) of the 13 culture-proven ulcers in this series showed a greater number of colonies and more confluent growth on the agar plates inoculated with a moistened swab compared with a much lower yield obtained using a platinum spatula. All culture-positive bacterial ulcers showed growth when cultured with a swab. Two ulcers that were partially treated before culturing yielded very light growth from those rows inoculated with a swab and no growth from those rows inoculated with a spatula. Two ulcers showed equal growth between the two methods. One ulcer (Actinomycetes-Streptomyces/Nocardia) had greater growth obtained with a spatula compared with a swab. This series demonstrated a significantly greater retrieval of organisms from bacterial keratitis when a calcium alginate swab moistened with trypticase soy broth was used to rub the ulcer and directly inoculate the solid agar media. The single case of filamentous bacteria suggests that a spatula may yield better organism retrieval from ulcers caused by filamentous organisms.

Bacteria↗
PubMed1992

Foreshortening of the inferior conjunctival fornix associated with chronic glaucoma medications.

The authors designed a device to measure the depth of the inferior conjunctival fornix at the slit lamp using topical anesthesia. The fornices of 179 glaucoma patients receiving topical medications for glaucoma and 420 control subjects who had no history of ocular disease were measured. These measurements were age-stratified by decade. A significant foreshortening of the inferior conjunctival fornix was found with aging (P less than 0.01). Patients in their sixth through ninth decades using miotics for 3 years or longer and patients using nonmiotic agents for 3 years or longer exhibited significant foreshortening of the inferior fornix when compared with age-stratified (by decade) control subjects (P less than 0.01). These observations suggest that increasing age and topical medications for glaucoma, or the preservatives, used for 3 years or longer, are independently associated with conjunctival shrinkage.

Adolescent↗
PubMed1992

The red eye: avoiding pitfalls from topical ocular therapy.

Acute and general medical care facilities are often faced with the challenge of diagnosing and managing problems related to the external eye. Making the correct diagnosis, possessing knowledge of the natural course of the disease, and understanding the potential benefits and risks of topical ocular therapy are necessary for the proper management of an acute or chronic red eye.

Conjunctivitis↗
PubMed1991

Evaluation of humic-pesticide interactions on the acute toxicity of selected organophosphate and carbamate insecticides.

The ability of water resource managers to accurately predict the toxicity of agricultural chemicals in aquatic ecosystems is essential for the development of reliable water quality standards. At present, accurate predictions are difficult due to the paucity of data concerning the interaction of these chemicals with organic constituents of the freshwater chemical matrix. Dissolved humic materials are ubiquitous components of freshwater ecosystems and can affect the availability and toxicity of chemicals in the environment. In the present investigation, the influence of humic acid (HA) on the acute toxicity of selected organophosphate and carbamate insecticides was examined using a bacterial bioluminescence inhibition assay. EC50 values for the pesticides were determined in the presence of 0, 0.5, 5.0, 50, and 100 mg/liter HA. A combination of antagonistic and synergistic effects was observed with the selected organophosphate and carbamate insecticides examined. HA significantly reduced the toxicity of azinophos-methyl, chlorpyrifos, and carbofuran, while enhanced toxicity was observed with methyl parathion and carbaryl. These results indicate that humic-pesticide interactions can alter the toxicity of agricultural chemicals. Moreover, the influence of humic materials on the toxicity of these chemicals is dependent on temporal relationships and HA concentration.

Carbamates↗
PubMed1989

The effect of humic acid on the toxicity and bioavailability of trivalent chromium.

The influence of humic acid (HA) on the toxicity and bioavailability of two forms of trivalent chromium (chromic chloride and chrome lignosulfonate) was evaluated using a common freshwater invertebrate, Daphnia pulex. With both compounds, the 50 mg/liter HA significantly decreased toxicity at all time points examined. The remaining two HA concentrations, 0.5 and 5 mg/liter, either had no influence or decreased the toxicity of the compounds. Humic acid appeared to have no influence on the bioavailability of chrome lignosulfonate. However, for chromic chloride, 5 and 50 mg/liter HA decreased the percentage free chromium at all time points examined.

Animals↗
PubMed1989

Diabetic retinopathy in a rural diabetic population. Prevalence and risk.

As part of the West Virginia Diabetes Eye Care Project of 1986, 178 patients in a rural diabetic population were screened for diabetic retinopathy using psychophysical testing and stereo fundus photography. The effects of sex, age, mode of therapy, and duration of diabetes mellitus on the prevalence of retinopathy were investigated. The prevalence of retinopathy was 34 per cent among insulin-treated patients, 18 per cent for those receiving oral hypoglycemics, and seven per cent for the diet-controlled group. Diabetic retinopathy was most prevalent among insulin-dependent patients with prolonged duration of disease. Age did not affect the prevalence of retinopathy after adjustment for sex and duration of diabetes.

Diabetes Mellitus↗
PubMed1988

Increased mortality rates after cataract surgery. A statistical analysis.

One hundred ninety-three patients 50 to 89 years of age had cataract surgery between January 1, 1979, and December 31, 1980, at West Virginia University Medical Center, Morgantown. In comparison with 182 patients who elected one of three other surgical procedures, cataract surgery patients had a significantly higher mortality rate (P = 0.0005) than control group patients, according to life-table analysis estimates adjusted for age and sex. Patients with adult onset diabetes mellitus had slight increased survival and did not alter relative mortality. The authors' results support the hypothesis that senile cataracts may reflect systemic factors in addition to localized ocular disease.

Aged↗
PubMed1987

Influence of cadmium exposure on selected hematological parameters in freshwater teleost, Notemigonus crysoleucas.

The use of hematological parameters for assessing the acute toxicity of heavy metals to mammals has shown considerable promise. These parameters include the measurement of blood glucose, hematocrit, and a variety of enzymes. The present investigation was undertaken to evaluate the use of selected hematological parameters in aquatic organisms. Exposure of Notemigonus crysoleucas to cadmium resulted in a 96-hr LC50 value of 3.15 mg Cd/liter. The influence of cadmium on selected hematological parameters was examined following 96 hr of exposure to 0, 1.35, and 2.40 mg Cd/liter. Cadmium exposure produced significant alterations (P less than 0.05) in the levels of glucose, aspartate aminotransaminase, and alanine aminotransaminase. Hematocrit was not altered by exposure to cadmium. These results indicate that glucose and transaminases may be useful as diagnostic tests for cadmium exposure in aquatic organisms.

Animals↗
PubMed1987

Comparative activity of gill ATPase in three freshwater teleosts exposed to cadmium.

The comparative activity of gill ATPase was examined in the bluegill sunfish (Lepomis macrochirus), fathead minnow (Pimephales promelas), and golden shiner (Notemigonus crysoleucas). Basal Na/K ATPase activity was highest in bluegill sunfish (1.46 mumol Pi/mg protein/hr) and lowest in golden shiners (1.01 mumol Pi/mg protein/hr). While a stimulation of Na/K ATPase activity was observed at an exposure concentration of 1 micrograms Cd/liter in the bluegill sunfish and fathead minnows, an inhibition of enzymatic activity was observed at higher exposure concentrations (10 and 100 micrograms Cd/liter). Gill Na/K ATPase activity in golden shiners was not significantly influenced by cadmium exposure. The observed insensitivity of Na/K ATPase in golden shiners may, in part, be related to high background concentrations of cadmium in gill tissue. In all three species examined, gill residual ATPase activity was not significantly altered by cadmium exposure.

Animals↗
PubMed1987

Influence of chemical and environmental stressors on acute cadmium toxicity.

Previous investigations have demonstrated that the cytosolic protein metallothionein (MT) is induced not only by exposure to certain heavy metals but also by a variety of other factors, including environmental stress. While MT synthesis has been observed with exposure to cold temperatures, there is a paucity of data concerning the influence of cold on heavy-metal toxicity. The present investigation focused on the influence of metal and cold pretreatments on the acute toxicity of cadmium. Mortalities of 80% and 100% were observed for mice orally administered challenge doses of 100 mg Cd/kg and 150 mg Cd/kg, respectively. To determine a protective cadmium pretreatment dose, animals were administered 2.5, 5, 10, 20, 25, and 50 mg Cd/kg 24 h prior to cadmium challenge. In animals pretreated with 10 mg Cd/kg, mortalities of 20% and 70% were observed with the respective challenge doses. Immediately following cold stress (4 degrees C, 12 h), mortalities of 30% and 90% were observed with cadmium challenge doses of 100 and 150 mg Cd/kg, respectively. Significant correlations were demonstrated between induced hepatic MT concentrations and cadmium pretreatment (r = 0.99), as well as cold pretreatment (r = 0.87). Results of this investigation indicate that stressors, such as cold, influence the acute toxicity of cadmium to the same magnitude as metal pretreatment. This induced tolerance to cadmium was attributed, in part, to the induction of MT synthesis. Furthermore, the induced levels of MT resulting from cold stress may confound the simplistic approach of using MT as a biological monitor of occupational exposure to cadmium.

Animals↗
PubMed1986

Evaluation of a new approach to the safety assessment of biomaterials.

The effectiveness of a bacterial luminescence inhibition assay in assessing the toxicity of compounds which are released from biomaterials was evaluated. Luminescence from a strain of bacteria most closely resembling Photobacterium phosphoreum was measured. The concentration that inhibited luminescence by 50% (EC50) was determined for selected plasticizers, monomers and additives. The intraperitoneal (i.p.-ALD) and intravenous (i.v.-ALD) approximate lethal doses were determined using mice. By ranking the reference compounds toxic/non-toxic, a 37.5% agreement was obtained for the i.p.-ALD and i.v.-ALD toxicity data. While there was only a 12.5% agreement for the i.p. ALD and EC50 values, there was a 75% agreement between the i.v.-ALD and EC50 values. Although additional validation is required, these results provide preliminary indications that the bacterial luminescence inhibition assay is a promising alternative approach to the safety assessment of biomaterials.

Animals↗
PubMed1985

Cocainism--a workable model for recovery.

Presented here is a model for the diagnosis and treatment of cocaine dependence. Intrinsic in the understanding of this model is the use of the disease concept of chemical dependence. Within the construct of this model we regard cocaine dependence or "cocainism" as a disease process and part of the spectrum of the disease of chemical dependence. We note that "pure" cocainism is rare and cocaine is usually just another chemical used in the polyaddicted patient. We call cocaine the "Great Precipitator" as it often brings the polyaddicted chemically-dependent person into a crisis that requires a treatment intervention. Cocainism, with its overwhelming compulsion and destruction, often precipitates a crisis in a matter of months from first use. As psychiatrists practicing addictionology, we understand the need to deal with cocainism as a primary disease process rather than a symptom of an underlying psychiatric illness. We deal with cocainism as we deal with alcoholism. While the DSM-III requires withdrawal and tolerance changes to be an essential feature for dependence, we more easily identify the disease of cocainism by its production of intense psychological addiction. Thereby the diagnosis of the disease of cocainism, as with other drugs (including alcohol) in the spectrum of chemical dependence, is characterized by the persistent, uncontrolled, compulsive use of cocaine. This illogical, irrational compulsion with continued, repeated use of cocaine as it destroys the individual's life, is the primary symptom of this disease. In regards to specific considerations, the psychiatric complications of cocainism, which can include cocaine induced psychosis, can persist beyond the intoxication period. We also note the depression that can accompany abstinence from cocaine and often has a protracted course following initial abstinence as well. We advocate the very cautious use of any psychotropic medications after an alloted period of time since we find that many of these additional symptoms seem to dissipate during the treatment process when involved in our suggested setting. In the cases of where it is determined that additional psychiatric illness co-exist with cocaine and chemical dependence such as in "dual diagnosis" patients, we have had that success by treating both illnesses concomitantly and aggressively. The "contract" with the dual diagnosis patient has afforded excellent results in this instance. The treatment modalities most effective in this model include a treatment team with its multidisciplinary and recovering and non-recovering characteristics, and the use of the group process and peer group therapy.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMedDate not supplied

Tetanus prophylaxis following ocular injuries.

The administration of prophylaxis against tetanus following a corneal abrasion is routinely performed in many acute care facilities, despite a lack of support in the literature for its necessity. The risk of developing clinical tetanus from three different types of injuries to the eye was evaluated in an animal model. Clinical tetanus was induced in unimmunized mice by injecting Clostridium tetani organisms or toxin into the anterior chamber. Immunized mice injected intracamerally did not develop signs of tetanus. Tetanus was not induced by topical inoculation of either live organisms or toxin following corneal epithelial debridement or stromal scarification of unimmunized and immunized mice. The results of this study support the administration of prophylaxis against tetanus following perforating ocular injuries. However, our results do not support its routine use following uncomplicated corneal abrasions or other types of nonperforating ocular injuries.

Animals↗
PubMedDate not supplied

Interactions of chlorpyrifos and methyl mercury: a mechanistic approach to assess chemical mixtures.

The mechanism of interaction between chlorpyrifos, an organophosphate insecticide, and methyl mercury was assessed utilizing the amphipod, Hyalella azteca. Previous studies have demonstrated that chlorpyrifos and methyl mercury interact additively with survival as the endpoint. In addition, exposure to chlorpyrifos and methyl mercury increased the accumulation and decreased the elimination of methyl mercury. To further examine the mechanism responsible for these interactions, the in vivo and in vitro inhibition of acetylcholinesterase enzyme activity was assessed following exposure to methyl mercury and chlorpyrifos. In vivo, methyl mercury antagonized the effects of chlorpyrifos on acetylcholinesterase inhibition. Additional studies demonstrated that methyl mercury did not affect the in vitro bioactivation of chlorpyrifos or the subsequent inhibition of acetylcholinesterase enzyme activity. Chemical-chemical interactions were examined utilizing chromatographic techniques and suggested the formation of a chlorpyrifos-methyl mercury complex. The formation of this complex may result in increased accumulation of methyl mercury, apparent additive toxicity, and protection against chlorpyrifos-mediated acetylcholinesterase inhibition.

Acetylcholinesterase↗