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Biomedical subjects

S M Roberts

Publications and source records attributed to S M Roberts.

At least 127 records · Page 7Linked to original sources
PubMed1987

Antagonism of cocaine-induced hepatotoxicity by the alpha adrenergic antagonists phentolamine and yohimbine.

The ability of the alpha adrenoreceptor antagonists phentolamine and yohimbine to antagonize cocaine-induced hepatotoxicity was determined in phenobarbital-induced B6C3/F1 mice. Hepatotoxicity was assessed by the histologic extent of necrosis, incidence of latent lethality and increases in serum alanine aminotransferase activity. The depression of hepatic glutathione levels also were measured. The administration of a single 5-mg/kg dose of phentolamine antagonized the decrease in glutathione levels and the elevation of aminotransferase activity caused by a 60-mg/kg dose of cocaine. Similar results were obtained in mice pretreated with the alpha-2 antagonist yohimbine. Whereas the duration of antagonism could be extended by administering a 30-mg/kg dose of yohimbine, the magnitude of the antagonism was not increased. In contrast to the experiments with the larger dose, multiple hourly doses of 2.5 mg/kg of yohimbine increased both the duration of antagonism and the magnitude of protection against the hepatotoxicity produced by cocaine. Yohimbine pretreatment reduced cocaine-induced latent lethality by 50%, but did not alter the time to lethality. The results of these experiments indicate that the alpha adrenoreceptor antagonist reduces the toxicity of cocaine rather than merely delaying its time of onset. This effect does not appear to result from an inhibition of the toxic metabolite(s) of cocaine, as a 10-fold molar excess of yohimbine failed to antagonize lipid peroxidation caused by in vitro incubation of cocaine with hepatic microsomes. Additional experiments in mice whose liver metabolism had not been induced by prior pretreatment with phenobarbital revealed that 60 mg/kg of cocaine lowered glutathione but was not hepatotoxic.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic alpha-Antagonists↗
PubMed1986

Prevalence and treatment of palpebral neoplasms in the dog: 200 cases (1975-1983).

The prevalence and treatment of 255 eyelid tumors in 200 dogs was related to breed, age, sex, location, and tumor type. Treatment methods included cryosurgery and surgical excision. The mean age of all dogs with eyelid tumors was 9.6 years (+/- 0.2 SEM). Beagles, Siberian Huskies, and English Setters had a higher risk of tumor development, whereas the mixed-breed dogs had a lower risk. Sebaceous tarsal gland adenomas, benign melanomas, and papillomas were observed most often (88%). Malignant tumors (melanoma, adenocarcinoma, basal cell carcinoma, mast cell tumor, squamous cell carcinoma, hemangiosarcoma, and myoblastoma) comprised 8.2% of the tumors. Tumor recurrence rates between dogs treated with cryosurgery and those treated surgically were not significantly different (15.1% and 10.5%, respectively). The mean recurrence time after cryosurgery was 7.4 months (+/- 1.9 SEM), whereas it was 28.3 months (+/- 7.2 SEM) after surgical excision. Using either treatment, the long-term side effects were similar. The overall cosmetic appearance was observed to be better with cryosurgery.

Animals↗
PubMed1986

Antibacterial activity of dilute povidone-iodine solutions used for ocular surface disinfection in dogs.

Bacterial cultures of specimens from healthy canine eyelids and ocular surfaces were found to demonstrate bacterial growth in 69.7% (53/76) of the eyes sampled. Organisms most commonly isolated included: Staphylococcus aureus, alpha-hemolytic Streptococcus sp, S epidermidis, and Escherichia coli. Evaluation of dilute povidone-iodine solutions for effectiveness as ocular surface disinfectants was conducted. Bacterial growth initially detected in 32 of 46 eyes was not detected after disinfection with a 2-minute scrub and 2-minute soaking procedure, using 1:2, 1:10, or 1:50 dilutions of a povidone-iodine solution that contained 1% available iodine. The eyelid and ocular surfaces of 16 eyes were disinfected with 1:100 povidone-iodine solution. Bacterial growth initially present in 10 of 16 eyes was present in 1 eye after disinfection and consisted of a single colony of E coli. After eyes were disinfected with 1:10, 1:50, or 1:100 povidone-iodine solutions, there was no evidence of corneal epithelial edema or sloughing. In 15 eyes subjected to disinfection with the 1:2 dilution, one instance of epithelial corneal edema was noticed. A 1:50 dilution of povidone-iodine is recommended as an ocular surface disinfectant for use in presurgical situations.

Animals↗
PubMed1985

Enzyme-controlled reactions giving alkanols of use in the synthesis of biologically active molecules.

(+/-)-Bicyclo[3.2.0]hept-2-en-6-one was reduced using a variety of fungi including yeasts. Baker's yeast gave 6-exo-(1R,5S,6S)-bicyclo[3.2.0]hept-2-en-6-ol and 6-endo-(1S,5R,6S)-bicyclo[3.2.0]hept-2-en-6-ol while Curvularia lunata and Mortierella ramanniana gave only the 6-endo-alcohol and optically active bicycloheptenone. The optically active bicycloheptenols were used to prepare prostaglandin F2 alpha in the natural configuration.

Alcohols↗
PubMed1985

BCG treatment of periocular sarcoid.

Twenty-six horses and five mules with periocular sarcoids were treated with intralesional injections of a purified bacillus of Calmette and Guerin (BCG) cell walls in oil suspension. All sarcoids were cured and the horses and mules remained free from recurrence of sarcoid during the two-year follow-up period.

Animals↗
PubMed1985

Utilizing the health belief model to predict dieting and exercising behavior of obese and nonobese adolescents.

This study was undertaken to explain dieting and exercising behavior of obese and nonobese adolescents as measured by the elements of the Health Belief Model (HBM). An elicitation questionnaire was used to determine salient beliefs about dieting, exercising, and obesity for each of the major components of the HBM. The Health Belief Model questionnaire, developed from the elicited salient beliefs, contained items employed to measure attitudes towards obesity and exercise, knowledge of obesity and exercise, weight locus of control, and beliefs and evaluations about obesity and exercise. Discriminant analysis and stepwise discriminant analysis were employed in the data analysis of the 69 obese and 100 nonobese HBM respondents to determine the relative importance of the investigated factors in predicting obesity. It was found that benefits of dieting was the most powerful predictor of dieting behavior for the obese adolescents, whereas susceptibility to the causes of obesity best explained present dieting behavior of nonobese adolescents. Exercising behavior of obese teenagers was best explained by cues to exercising. No HBM variables were significant in predicting exercising behavior of nonobese adolescents.

Adolescent↗
PubMed1984

Lacerations of the equine eye: a review of 48 cases.

Perforating corneal wounds in horses have a better prognosis than wounds that involve both cornea and sclera. Sharp objects tend to produce more isolated corneal wounds and have a better prognosis than do wounds produced by blunt objects. The records of 43 horses that sustained penetrating wounds of the cornea were reviewed. In addition, the surgical approach and postoperative wound management is described. The report attempts to provide more information regarding the management of ocular trauma in horses.

Animals↗
PubMed1984

Effect of ophthalmic prednisolone acetate on the canine adrenal gland and hepatic function.

Iatrogenic hypothalamic-hypophysis-adrenal axis suppression occurred in 5 small dogs as a result of ophthalmic instillation of 1% prednisolone acetate. An ophthalmic suspension was applied 4 times a day to each eye, such that 4 mg/day was delivered for 2 weeks followed by 2.67 mg/day for 2 weeks. After treatment week 2, serum cortisol decreased from base-line mean values of 17.66 ng/ml (before ACTH) and 139.16 ng/ml (60 minutes after ACTH) to 3.22 ng/ml (before ACTH) and 13.58 ng/ml (60 minutes after ACTH). After treatment week 4, serum cortisol values decreased to a mean of 1.76 ng/ml (before ACTH) and 4.82 ng/ml (60 minutes after ACTH). Before ACTH cortisol values returned to base line 2 weeks after discontinuing treatment. Values after ACTH administration remained 26% lower than base line (P = 0.0132), although within a normal response range. Hepatic carbohydrate metabolism was altered, allowing marked glycogen accumulation. Marked increases in the blood glucose values after glucagon stimulation testing occurred at 3, 5, 15, 30, and 60 minutes after glucagon administration. The greatest increase corresponded to the 30-minute sample with a mean glucose increase of 112.40 mg/dl from base-line values (P = 0.0022) as a result of the ophthalmic corticosteroid applied. Seemingly, topical ophthalmic corticosteroids have the potential for causing adrenocortical suppression and hepatic metabolic changes. The dosage level of treatment was low enough to avoid major hematologic changes. The exaggerated response to the glucagon tolerance test indicates that this test can be used in detecting hyperglucocorticism.

Administration, Topical↗
PubMed1983

Tegument surface membranes of adult Schistosoma mansoni: development of a method for their isolation.

Several approaches to surface membrane stripping have been applied to the adult schistosome. Membrane removal was evaluated by the use of different extrinsic and intrinsic markers of which alkaline phosphatase proved to be the most reliable. After initial studies employing incubation of worms in buffer alone, Triton X-100 or freeze/thaw, the last method was chosen for development. The final method applies a single freeze/thaw step to adult worms in balanced salt solution followed by short bursts of agitation on a vortex mixer to release the tegument. Differential and density gradient steps subsequently yield a final membrane pellet enriched over 130 times in surface alkaline phosphatase. The method has been characterized during its development using electron microscopy and enzyme markers for contaminant worm fractions.

Alkaline Phosphatase↗
PubMed1983

Identification of exposed components on the surface of adult Schistosoma mansoni by lactoperoxidase-catalysed iodination.

Adult schistosomes have been labelled with 125I using the lactoperoxidase-catalysed technique modified to cause minimal worm damage. After surface membrane removal and characterization, at least 13 labelled proteins were identified together with a large amount of labelled glycolipids, free fatty acids and phospholipids, especially phosphatidyl ethanolamine. Cationised ferritin has been used to stimulate surface membrane turnover of iodinated worms and the shedding of covalently bound 125I-counts used as an index of turnover. Finally worms have been iodinated before and after stimulation of membrane turnover in chemically defined media and the patterns of labelled proteins were compared.

Alkaline Phosphatase↗
PubMed1982

Massive intoxication with acetaminophen and propoxyphene: unexpected survival and unusual pharmacokinetics of acetaminophen.

A 28-year-old woman ingested an estimated 58 g acetaminophen and 9 g propoxyphene 20 h before hospitalization. Her serum acetaminophen concentration at 22 h was 485 micrograms/mL and declined with an unusually long half-life of 14 h. Hemodialysis for 4 h (started at 36 h) reduced the acetaminophen concentration from 250 to 32 micrograms/mL. The patient's complete recovery was remarkable because of the large amounts of drugs ingested, the delayed treatment, and prior exposure to enzyme inducers (known to increase acetaminophen hepatotoxicity). Administration of N-acetylcysteine prevented inorganic sulfate depletion usually caused by acetaminophen and may have increased the formation of acetaminophen sulfate. Some patients eliminate large overdoses of acetaminophen very slowly. Measures to enhance the elimination of this drug and its toxic metabolite by these individuals may be useful even when diagnosis or hospitalization is delayed.

Acetaminophen↗
PubMed1981

Evaluation of methods for producing renal dysfunction in rats.

The following methods for producing renal dysfunction in rats were compared: single-step 5/6th nephrectomy, two-step 5/6th nephrectomy, bilateral ureteral ligation, and uranyl nitrate injection. Control groups consisted of single- and two-step sham-operated animals and animals that received an injection of normal saline solution. The methods were evaluated on the basis of the following criteria, which were assessed daily for 6 days: survival, body weight, hematocrit, serum creatinine concentration, serum urea nitrogen concentration, serum glutamic pyruvic transaminase activity, serum albumin concentration, and serum protein binding of salicylate (determined every other day). Animals with bilateral ureteral ligation survived only 2 days, single-step 5/6th nephrectomy caused a high incidence of fatalities. Some of the methods were associated with the development of hypoalbuminemia, but no significant elevation of transaminase activity occurred. Serum protein binding of salicylate was reduced in rats with renal dysfunction. A strong positive correlation between the creatinine and urea nitrogen concentrations in the serum of animals with renal dysfunction (r = 0.91, p less than 0.001) and a negative correlation between the serum albumin concentration and salicylate free fraction (r = -0.71, p less than 0.001) were found. Uranyl nitrate injection has the advantages of technical simplicity, a high survival rate (no deaths in this study), and relatively consistent and sustained diminution of renal function (as reflected by serum creatinine and urea nitrogen concentrations).

Animals↗