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Biomedical subjects

C R Morris

Publications and source records attributed to C R Morris.

At least 19 recordsLinked to original sources
PubMed1995

An evaluation of the aquatic hazard of cumene (isopropyl benzene).

Cumene manufacturers were required under a TSCA Section 4(a) test rule to evaluate the aquatic toxicity of cumene to daphnids, rainbow trout, mysid shrimp, and sheepshead minnows. Because of cumene's high volatility (vapor pressure, 3.2 mm Hg at 20 degrees C), all tests were conducted under flowthrough conditions using a proportional diluter system. The 96-hr LC50s for rainbow trout, sheepshead minnow, and mysid shrimp, based on mean measured concentrations, were 4.8, 4.7, and 1.3 mg/liter, respectively. The 48-hr daphnid EC50 was 4.0 mg/liter. Although cumene is considered moderately toxic to aquatic organisms under rigorous laboratory conditions, its volatility and biodegradability greatly reduce its hazard to the aquatic environment.

Animals↗
PubMed1995

Enzootic pneumonia: comparison of cough and lung lesions as predictors of weight gain in swine.

A prospective cohort study was undertaken in a commercial swine herd to determine the relationship between weight gain and the occurrence of enzootic pneumonia (EP). Estimates of the association between EP and weight gain were obtained from multiple linear regression models, using coughing episodes or slaughter checks as indicators of EP status. Models were estimated for pigs in 2 different age groups: roasters (n = 1084, sold at 32 to 50 kg) and market hogs (n = 1162, sold at 100 to 110 kg). The relationship between presence of lung lesions at slaughter and previous coughing episodes was also investigated. Throughout the study period, clinical evaluations were performed weekly, and coughing episodes recorded for each pig. Lungs were inspected at slaughter, and scores were expressed as the percentage of the lung with gross pneumonic lesions. Coughing and lung scores were significantly correlated, after adjusting for other covariates (R = 0.32 and 0.59, respectively, for market hogs and roasters). However, the agreement beyond chance between coughing history and lung lesions at slaughter was poor among both roasters and market hogs (kappa = 0.17 and 0.07, respectively). Although very specific, weekly assessment of coughing was not a sensitive indicator of lung lesions at slaughter. In multiple regression, lung score was a highly significant predictor of lower final weight in pigs of both age groups (P < 0.001 in the selected regression models).(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1994

Fatal myocardial infarction resulting from coronary arteritis in a patient with polymyalgia rheumatica and biopsy-proved temporal arteritis. A case report and review of the literature.

Giant cell arteritis is frequently an attendant complication of polymyalgia rheumatica. While involvement of other arterial beds is occasionally identified, this syndrome is most frequently recognized when symptomatic involvement of the temporal arteries occurs. We describe such a patient who despite initial treatment with high-dose intravenous and standard (5-day) orally administered corticosteroid therapy suffered a fatal myocardial infarction, which at autopsy was shown to be a consequence of granulomatous coronary arteritis. The literature is reviewed and the clinical implications of this case are discussed.

Aged↗
PubMed1993

Inhibition by phenylethyl and phenylhexyl isothiocyanate of metabolism of and DNA methylation by N-nitrosomethylamylamine in rats.

We investigated the effect of 2-phenylethyl and 6-phenylhexyl isothiocyanate (PEITC and PHITC) on the metabolism of the rat esophageal carcinogen, N-nitrosomethylamylamine (NMAA). PEITC was administered orally to MRC-Wistar rats as single doses of 0.1 or 1.0 mmol/kg, or by other regimens. When esophagi and liver slices from the treated rats were incubated with 23 microM NMAA, the formation of 2- to 5-hydroxy-NMAA was inhibited by 45-90% for esophagus and by 14-19% for liver slices. In contrast, when esophagi and liver slices from untreated MRC-Wistar rats were incubated in vitro with NMAA and 10 microM PEITC, the PEITC inhibited hydroxy-NMAA formation similarly (by 79-89%) in the two tissues. Also, PEITC inhibited the formation from NMAA of the hydroxy-NMAAs, formaldehyde and pentaldehyde by esophageal and liver microsomes to similar extents. In studies on DNA methylation by NMAA, 7- and O6-methylguanine (O6-MeG) were determined by HPLC with fluorimetric detection. Guanine methylation in esophageal and liver DNA was generally close to linear for doses of 5-50 mg NMAA/kg. With 50 mg NMAA/kg, guanine methylation in esophageal and liver DNA peaked after 5 h, and 8-11% of the peak O6-MeG persisted after 72 h. A single dose of 0.1 or 1.0 mmol PEITC/kg reduced the O6-MeG levels by 44-51% in the esophagus but by only 7-22% in the liver. Administration of the PEITC homolog, PHITC, inhibited NMAA metabolism by liver slices from the treated rats and the methylation of guanine in liver DNA, but had little effect in the esophagus, i.e. PHITC tended to have the opposite tissue specificity to PEITC. The finding that administration of PEITC specifically inhibited NMAA metabolism in the rat esophagus supports the view that PEITC may be a useful chemopreventive agent against esophageal carcinogenesis in humans.

Animals↗
PubMed1989

Hexachlorobenzene episode in Turkey.

During the period 1955-1959, approximately 4000 people in southeast Anatolia developed porphyria due to the ingestion of hexachlorobenzene (HCB), a fungicide added to wheat seedlings. These HCB exposures subsequently led to the development of bullae on sun-exposed areas, hyperpigmentation, hypertrichosis, and porphyrinuria. The condition was called kara yara or "black sore." Many of the breast-fed children under the age of 2 years whose mothers had ingested HCB-treated grain died from a disease known as pembe yara or "pink sore." In this follow-up study of 252 patients, 20-30 years postexposure, there were 162 males and 90 females, with an average current age of 35.7 years, an average of onset of 7.6 years, and a duration of 2.2 years. Many patients had dermatologic, neurologic, and orthopedic symptoms and signs. The observed clinical findings include scarring of the face and hands (83.7%), hyperpigmentation (65%), hypertrichosis (44.8%), pinched facies (40.1%), painless arthritis (70.2%), small hands (66.6%), sensory shading (60.6%), myotonia (37.9%), cogwheeling (41.9%), enlarged thyroid (34.9%), and enlarged liver (4.8%). Urine and stool porphyrin levels were determined in all patients, and 17 have at least one of the porphyrins elevated. A total of 56 specimens of human milk obtained from mothers with porphyria were analyzed for HCB. The average value was 0.51 ppm in HCB-exposed patients compared to 0.07 ppm in unexposed controls. Offspring of mothers with three decades of HCB-induced porphyria appear normal.

Adolescent↗
PubMed1989

Quality assurance in toxicology studies in developing countries.

As developing countries become more involved in the international chemical trade, they must adhere to certain requirements for importation of their chemicals into foreign countries. These developing countries will be required to provide basic safety information on their chemical products, including data developed from chemical and toxicologic testing. These data must be developed in accordance with the national requirements of the importing country. Many importing countries have adopted the OECD Test Guidelines and the OECD Principles of Good Laboratory Practice (GLP) as primary guidance to assure the quality of laboratory data. These procedures provide a basis for internationally acceptable data. Several countries have incorporated many of these provisions into their national laws or administrative procedures. These procedures describe the process of documenting the conduct of laboratory studies, including recording of data, reporting of study results, and storage of data gathered. This process is intended to assure the quality and integrity of the data so that, if required, the study can be reconstructed by an auditor or an inspector. Details of these procedures and their applicability to the international chemical trade are discussed.

Developing Countries↗
PubMed1988

A three-year experience with CCPD in a university-based dialysis and transplantation program.

A three-year experience with CCPD in adults and children in a university-based Dialysis and Transplantation Program is presented. Fifty-one patients began treatment from March of 1984 through February of 1987 (5 infants less than age three years, 11 children ages 3 to 17 years and 35 adults, of whom 8 had diabetes mellitus). The approach to treatment selection and the results of treatment including peritonitis rates and patient outcomes are described in the different groups. CCPD has become the treatment of choice for infants and children with ESRD awaiting kidney transplantation. In adults it is a considered a reasonable alternative, and may be the preferred dialysis, modality, in elderly patients, patients with diabetes mellitus and patients with severe cardiovascular disease who require or prefer assistance, who wish to be at home, and who tolerate hemodialysis poorly. This segment of the dialysis population appears to be increasing steadily.

Academic Medical Centers↗
PubMed1986

Dimensional reproduction in rotational panoramic radiography.

The customary mathematical expressions for magnification in rotational panoramic radiography are examined. It is shown that although these expressions yield correct results for small objects placed perpendicularly to the central ray of the beam, they must be corrected in other situations.

Computers↗
PubMed1986

Resolution of several screen-film combinations in rotational panoramic radiography.

Data for screen-film combinations suitable for panoramic radiography were obtained from the Eastman Kodak Company, Rochester, New York. Image resolution was calculated at various object depths with the use of system data for the Panorex 2 unit (S. S. White Company, Holmdel, New Jersey). An experimental test was performed in which clinicians ranked the various combinations with respect to diagnostic quality. The rankings by the observers generally reflected the resolution of the screen-film combinations.

Evaluation Studies as Topic↗
PubMed1986

Adaptation of the Panorex II for use with rare earth screen-film combinations.

A series of radiographs of a tissue-equivalent phantom was taken in order to arrive at satisfactory radiographic techniques for the use of rare earth screens with the Panorex II. The radiation reduction needed for use of the rare earth screens was made with various filters. There was a 40% to 60% reduction in patient exposure for all of the rare earth exposures. Raters agreed that all films that were ranked were diagnostically acceptable, although differences were noted.

Humans↗
PubMed1986

Kodak T-Mat G film in rotational panoramic radiography.

Panoramic radiographs were taken of a tissue-equivalent phantom to evaluate T-Mat G and Ortho G films in combination with rare earth screens. The radiographs were compared to radiographs made with high-speed calcium tungstate screens and Kodak XRP film. The reduction in the amount of radiation necessary for the use of rare earth screens (50% to 70%) was accomplished by lowering the mA and adding filtration. All evaluated films were diagnostically acceptable. There was a marked preference of the T-Mat radiographs over the Ortho G radiographs and a slight preference over radiographs made with the standard calcium-tungstate screen-film system.

Humans↗