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Biomedical subjects

J G Scott

Publications and source records attributed to J G Scott.

At least 91 records · Page 5Linked to original sources
PubMed1989

Interactions between pesticide genes: model and experiment.

In response to years of intense selection pressure by organophosphate insecticides, several different insecticide resistance mechanisms have evolved in natural populations of the mosquito Culex pipiens. We examined interactions between two of the most important mechanisms using a four-compartment model of insecticide pharmacokinetics. The joint effect of different mechanisms of resistance can be expressed in terms of epistasis at the physiological level in this model. The type of epistasis predicted by the model depends on the particular physiological mechanisms of resistance involved. Resistance due to a reduced penetration of the insecticide combines multiplicatively with other resistance factors, but resistance due to detoxicative processes and to insensitivity of the target site combines additively. How the pattern of epistasis at the physiological level is translated into fitness epistasis in natural populations of this mosquito depends on the intensity and pattern of insecticide selection in the field.

Animals↗
PubMed1989

An improved method for preparation, stabilization, and storage of house fly (Diptera: Muscidae) microsomes.

An improved method for preparation and storage of insect microsomes from house fly, Musca domestica L., abdomens was developed. Microsomes were prepared in phosphate buffer fortified with glycerol, dithiothreitol, ethylenediaminetetraacetic acid, phenylmethylsulfonyl fluoride, and 1-phenyl-2-thiourea. No cytochrome P-420 was observed when abdomens were isolated by our method. No measurable loss of cytochrome P-450, cytochrome b5 or NADPH-cytochrome c (P-450) reductase levels, or methoxyresorufin O-demethylation, 7-ethoxycoumarin O-deethylation, or aryl hydrocarbon hydroxylation activities occurred when a diluted suspension (protein concentration of 2 mg/ml) of microsomes was stored at -80 degrees C for at least 2 mo.

Animals↗
PubMed1989

An evaluation of outpatient bone marrow harvesting.

In order to avoid the difficulties in scheduling and cost involved in admitting patients to hospital to undergo bone marrow harvests, we assessed outpatient marrow harvesting for autologous bone marrow transplant (BMT) candidates. Over a 13-month period, 39 consecutive patients with hematologic malignancies underwent bone marrow harvests as outpatients. For comparison we also evaluated 20 consecutive patients with similar disease status who had undergone bone marrow harvests as inpatients over the preceding 6 months. The mean hemoglobin value prior to harvest the mean volume of marrow harvested, and the mean nucleated cell count in the outpatient group were not significantly different from those of the inpatient group. There were no intraoperative complications. Of these 39 patients, 36 were discharged later the same day on oral iron supplements, with no adverse sequelae. Local pain was well controlled at home with mild oral analgesics. Two patients required admission due to postoperative hypotension--both responded promptly to intravenous (IV) fluids and blood and were discharged the following day. One patient was admitted postoperatively due to fever. There was a trend for the outpatients to receive less intra- and postoperative blood transfusions, but this did not reach statistical significance. The results suggest that most candidates for autologous BMT can safely undergo bone marrow harvesting as outpatients, thereby relieving pressure for hospital beds, potentially reducing costs and improving bed utilization. The study also raises the possibility of safely performing outpatient harvests on allogeneic BMT donors.

Adolescent↗
PubMed1989

Classification behavior and measures of intelligence: dimensional identity versus overall similarity.

Individuals tend to adopt either analytic or holistic modes of categorizing objects. In two studies, we examined the relation between these categorization tendencies and cognitive abilities as measured by standard psychometric instruments. The participants in both studies were pretested with a restricted classification task in which it was possible for them to classify simple stimuli by dimensional identity or overall similarity. Those making a large number of either type of categorization were then tested with subtests of the WAIS-R and with the Raven's progressive matrices. Across both studies, the analytic individuals (many dimensional identity classifications) scored higher than the holistic individuals (many overall similarity classifications) on some but not all of the subtests. The results are consistent with the idea that holistic modes of categorization may be more "primitive" than analytic modes. The findings are discussed in terms of the association between categorization mode and either general or specific cognitive abilities.

Adult↗
PubMed1988

Efficacy of 2'-deoxycoformycin in hairy-cell leukemia: a study of the National Cancer Institute of Canada Clinical Trials Group.

Thirty-one patients with hairy-cell leukemia were treated with 2'-deoxycoformycin (DCF) in a National Cancer Institute of Canada multicenter trial. The DCF was administered in a cycle (4 mg/m2 iv weekly X 3), which was repeated every 8 weeks. Following a complete remission, consolidation was done with two further cycles of DCF. Of 28 patients evaluable for response, 25 obtained a complete remission; 3 had a partial response. To date there has been only one relapse; the median time with no therapy was 429.5 days (range 99-743 days). Toxicity was moderate and included nausea and vomiting, lethargy, and skin rash; with the first cycle of treatment, neutropenia and an increased incidence of fever or infection were also observed. We conclude that low-dose DCF is highly effective in treating hairy-cell leukemia.

Antineoplastic Agents↗
PubMed1988

Chemotherapy following surgery for stages IE and IIE non-Hodgkin's lymphoma of the gastrointestinal tract.

Twenty-six patients were treated with chemotherapy following surgery for gastrointestinal non-Hodgkin's lymphoma (GI-NHL). The median age was 50 years (range, 20 to 76). The primary site included stomach (16 patients), small bowel (seven), large bowel (two), and mesenteric nodes (one). Following surgery, nine patients had macroscopic and four patients had microscopic residual disease, and 13 were felt to have had complete surgical resection. Thirteen patients were stage I and 13 were stage II. Sixteen patients were treated with COPP (cyclophosphamide, vincristine, procarbazine, prednisone), nine with CHOP (cyclophosphamide, doxorubicin, vincristine, prednisone), and one with CVP (cyclophosphamide, vincristine, prednisone). At a median follow-up of 50 months (8+ to 178+ months) ten of 12 stage I patients and nine of 14 stage II patients remain alive. Of the nine patients with macroscopic residual disease, four died of disease 6.5 to 11.0 months after diagnosis, and five are alive 8+ to 178+ months from diagnosis. Fourteen of the remaining 17 patients who had complete surgical resection are alive without disease. Death in the other three patients was due to multiple abdominal abscesses at 12 months, adenocarcinoma of the colon at 57 months, and dementia and progressive neurologic dysfunction at 65 months. No patient who had complete resection has relapsed or developed systemic disease after chemotherapy. These results suggest that complete surgical resection is an important prognostic factor and that chemotherapy without irradiation in completely resected localized GI-NHL can prevent local and systemic relapse resulting in long-term disease-free survival.

Adult↗
PubMed1987

Oxidative metabolism of the GABAA receptor antagonist t-butylbicycloortho[3H]benzoate.

1. The trioxabicyclooctane ring of t-butylbicycloortho[3H]benzoate (TBOB), (CH3)3CC(CH2O)3CC6H5, is cleaved to yield the 3-oxo-benzoate, (CH3)3CC(CHO)(CH2OH)CH2OC(O)C6H5, on O-methylene hydroxylation by microsomes from mouse liver or houseflies in the presence of NADPH. 2. The methyl and phenyl substituents are tentatively identified as additional sites of oxidative metabolism. 3. The 3-oxo-benzoate from oxidative cage opening and the bis-(hydroxymethyl)-benzoate, (CH3)3CC(CH2OH)2CH2OC(O)C6H5, from enzymic reduction of the 3-oxo-benzoate undergo esteratic hydrolysis to benzoic acid. 4. Metabolites of TBOB excreted by rats and houseflies include the bis-(hydroxymethyl)-benzoate and benzoic and hippuric acids. 5. Metabolic hydroxylation of TBOB at O-methylene, alkyl and aryl substituents may serve as a model for detoxication reactions of related potent GABAA receptor antagonists and insecticides.

Animals↗
PubMed1986

The biochemical genetics of permethrin resistance in the Learn-PyR strain of house fly.

Permethrin resistance in the Learn-PyR strain of house fly was examined in four genetically derived substrains, each being homozygous for a different "resistant" autosome of the Learn-PyR strain. The resistance of these derivative strains was characterized toxicologically and biochemically. The relative levels of resistance to permethrin conferred by each autosome were 5 greater than 3 greater than 1 greater than 2. Three factors were associated with resistance: (1) increased mixed-function oxidase (MFO) activity associated with elevated levels of cytochrome P-450, cytochrome b5, and NADPH-cytochrome c reductase (P-450 reductase) activity; (2) target-site insensitivity (kdr); and (3) decreased cuticular penetration. Permethrin resistance factors on chromosome 1 consisted of a piperonyl butoxide (PB)-suppressible mechanism correlated with increased levels of cytochromes P-450 and b5; on chromosome 2, a PB-suppressible mechanism associated with elevated amounts of cytochrome P-450; on chromosome 3, decreased cuticular penetration, kdr, and increased amounts of P-450 reductase activity; and on chromosome 5, a largely PB-suppressible mechanism correlated with elevated levels of cytochrome P-450 and P-450 reductase activity.

Animals↗
PubMed1986

Malathion-specific resistance in Anopheles stephensi from Pakistan.

A strain of Anopheles stephensi from Pakistan (MalR) was 8.7-fold resistant to malathion and 6.7-fold cross-resistant to phenthoate, but not to other carboxylesters; no cross-resistance to bendiocarb, fenitrothion, permethrin and carbaryl was detected. Resistance was not associated with elevated levels of general esterase activity, as determined by hydrolysis of naphth-l-yl acetate (alpha-NA), but was correlated with higher levels of malathion carboxylesterase (MCE) activity in vitro. The results suggest that a highly specific type of esterase mediated resistance, such as MCE, can best be detected by an enzyme specific assay rather than one for general esterase activity. A new, rapid and sensitive assay for mosquito MCE is given.

Animals↗
PubMed1986

Cardiac assessment for patients undergoing noncardiac surgery. A multifactorial clinical risk index.

In this article, we describe a multifactorial cardiac risk index that can be used to assess patients undergoing noncardiac surgery. The index is a modified version of an index that was previously generated by Goldman and coworkers on a set of 1001 consecutive patients and prospectively validated in our clinical setting (a general medical consultation service in a large teaching hospital) on 455 patients. We present a Bayesian approach to assessing cardiac risks by converting average risks for patients undergoing particular surgical procedures (pretest probabilities) to average risks for patients with each index score (posttest probabilities). A simple nomogram is presented for performing such a calculation.

Aged↗
PubMed1985

Tetracycline sclerosis in the management of malignant pericardial effusion.

Twenty-two patients with malignant pericardial effusion were seen at the Toronto General Hospital between 1979 and 1984. Under ECG monitoring, an indwelling Kifa catheter was inserted into the pericardial sac and then connected to a Hemovac system and allowed to drain for 12 to 24 hours. Xylocaine hydrochloride, 100 mg, was first instilled intrapericardially, followed by tetracycline hydrochloride, 500 to 1,000 mg, dissolved in 20 mL normal saline. The catheter was clamped for one to two hours and then allowed to drain into the Hemovac. This procedure was repeated every 24 to 48 hours until the net drainage was less than 25 mL/24 hours. Nine men and 13 women were treated (median age, 55 years). The primary malignancy included lung in 15 patients, breast in two patients, and carcinoma of the stomach, ovary, pleural mesothelioma, chronic granulocytic leukemia, and adenocarcinoma of unknown primary in one patient each. Twenty patients received one to five instillations of tetracycline. In one patient the catheter could not be inserted into the pericardial sac, and in one patient the catheter clotted before tetracycline instillation. Minor complications included transient arrhythmia in two patients, postinjection pain in four patients, and self-limited temperature elevation greater than 38.5 degrees C in two patients. fifteen patients had good control of their malignant pericardial effusion for more than 30 days (median survival, 160 days; range, 38 to 275 days). Three patients died before 30 days without evidence of effusion, and no patient surviving longer than 30 days developed recurrent effusion or pericardial constriction. Intrapericardial tetracycline instillation is a safe and efficacious treatment for malignant pericardial effusion and should be considered the first treatment modality in this situation.

Adult↗
PubMed1983

The effect of maternal steroid administration on fetal platelet count in immunologic thrombocytopenic purpura. Management of pregnancy and mode of delivery.

Eight pregnancies complicated by immunologic thrombocytopenic purpura are described and the literature is reviewed. We conclude that, while steroid treatment favorably influenced fetal platelet counts in our cases, overall experience with this disease indicates that such protection is incomplete in some cases and unnecessary in others. Antiplatelet antibody levels show promise as excellent indicators of fetal thrombocytopenia, and elevated levels may be an indication for steroid therapy for the improvement of fetal well-being in some cases.

Adrenal Cortex Hormones↗