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J F Douglas

Publications and source records attributed to J F Douglas.

97 records · Page 6Linked to original sources
PubMedDate not supplied

A neurotoxicity assessment of high flash aromatic naphtha.

Catalytic reforming is a refining process that converts naphthenes to aromatics by dehydrogenation to make higher octane gasoline blending components. A portion of this wide-boiling range hydrocarbon stream can be separated by distillation and used for other purposes. One such application is a mixture of predominantly 9-carbon aromatic molecules (C9 Aromatics, primarily isomers of ethyltoluene and trimethylbenzene), which is removed and used as a solvent also known as High Flash Aromatic Naphtha (HFAN). A program was initiated to assess the toxicological properties of HFAN since there may be human exposure, especially in the workplace. The current study was conducted to assess the potential for neurotoxicity in the rat. Adult male Sprague-Dawley rats of approximately 300 grams body weight, in groups of twenty, were exposed by inhalation to HFAN for 90 days at concentrations of 0, 100, 500, and 1500 ppm. During this period the animals were tested monthly for motor activity and in a functional observation battery. After three months of exposure, for 6 hours/day, 5 days/week, 10 animals/group/sex were sacrificed and selected nervous system tissue was examined histopathologically. No signs of neurotoxicity were seen in any of the evaluated parameters, nor was there evidence of pathologic changes in any of the examined tissues.

Administration, Inhalation↗
PubMedDate not supplied

Suggested procedures for reducing the pathology workload in a carcinogen bioassay program, Part I.

Large test programs have been set up to help assess the carcinogenic potential of chemicals introduced into the environment. Most test protocols used in these programs require large numbers of animals and extensive pathologic evaluation of all test and control animals. In this paper we describe modifications to the present pathology protocol which will reduce the pathology workload of the program and make only small changes in the operational character of the screen. The first modification derives from the fact that a tumorigenic effect may be ruled out by looking at the treated animals only. The second procedure suggested uses simple random samples to provide information about the treated groups with still less pathology work. It is emphasized that these proposed modifications should be regarded as a starting point for further discussion and that we encourage comments from all interested scientists.

Animals↗
PubMedDate not supplied

Suggested procedures for reducing the pathology workload in a carcinogen bioassay program, Part II: Incorporating blind pathology techniques and analysis for animals with tumors.

Large testing programs have been set up to help assess the carcinogenic potential of chemicals introduced into the environment. Most test protocols used in these programs require extensive pathologic evaluations of all test and control animals. In Part I we proposed modifications to such complete pathology protocols which would allow substantial reduction in pathology workload while making only small changes in the operational character of the screen. The modifications suggested did require that slides from controls and treatment animals be handled differently and they did not call for a total tumor analysis (i.e. they do not allow blind pathology). In this paper we discuss how blind pathology can be incorporated and suggest a procedure to recover the "total tumor" aspect. It is emphasized that these modifications should be regarded as a starting point for further discussion and that we encourage comments from all interested scientists.

Animals↗
PubMedDate not supplied

Autonomic function in patients on continuous ambulatory peritoneal dialysis.

OBJECTIVE: To investigate sympathetic function in the peripheries of patients on chronic ambulatory peritoneal dialysis (CAPD) using noninvasive techniques. DESIGN: Comparison of peripheral blood flow responses in sympathetic vasoconstrictor reflexes in CAPD patients and matched control subjects. SETTING: Tertiary care hospital and research institution. PATIENTS: Twenty-three clinically stable CAPD patients and 23 control subjects matched for age, sex, and drug therapy. MAIN OUTCOME MEASURES: Sympathetic activity assessed from the reductions in hand and foot blood flow induced by a deep breath and by body surface cooling. Cardiac autonomic activity measured by the changes in heart rate produced by deep breathing, a Valsalva maneuver, and standing from lying. RESULTS: A deep breath induced mean decreases in hand blood flow of 65.1% in the patients and 82.8% in their matched controls. Corresponding reductions in the foot were 46.0% and 70.0%. Body surface cooling reduced mean hand blood flow by 50.3% in the patients and 71.8% in the control subjects. Corresponding values in the foot were 26.7% and 43.6%. The differences in response between the patients and their matched control subjects were all significant (p < 0.01). Cardiac autonomic function assessed by standard tests of heart rate variability was significantly impaired in the patients compared with the control subjects in two of the three tests used (p < 0.001). CONCLUSIONS: Cardiovascular autonomic impairment can affect the peripheral circulation as well as the heart in patients on dialysis, and this may have implications for cardiovascular homeostasis.

Adult↗