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Biomedical subjects

C R Morris

Publications and source records attributed to C R Morris.

At least 55 records · Page 3Linked to original sources
PubMed1986

Oncogenicity of hexachlorobenzene.

Subchronic and chronic toxicities of hexachlorobenzene (HCB) were studied in both sexes of Swiss mice, Syrian golden hamsters and Sprague-Dawley rats, at dietary dosages of 0, 100 and 200 ppm (mice), and 0, 200 and 400 ppm (hamsters and rats) for 90 days. At day 91, 25/50 animals in each of 18 groups were killed for histology studies. The rest were killed at 6-week intervals until the study was ended. Marked hepatosplenomegaly, enlarged thymuses and lymph nodes, or swollen and granular-looking renal cortices with depressions or nodulary areas were commonly observed. Dose- and sex-dependent progressive changes included toxic-degenerative hepatitis, chronic cirrhosis, hepatomas, bile-duct adenomas and a few hepatocarcinomas in older animals. A generalized lymphohaematopoietic response led to thymic, splenic and nodal lymphosarcomas, especially in female mice. Toxic-tubular nephritis with cortical infarcts developed into regenerative foci and renal adenomas in low incidences. Liver lesions were more prominent in females, while renal changes were most common in male rats. HCB was retested in both sexes of rats at oral doses of 0, 75 and 150 ppm for up to 2 years. At the start, each group contained 94 rats, and four randomly selected rats were killed at weeks 0, 1, 2, 3, 4, 8, 16, 32, 48 and 64 for microscopy. Progressive liver lesions started as hyperaemia and degenerations (4 weeks), and developed into toxic hepatitis, cirrhosis and formation of pre- and neoplastic foci (36 weeks), with hepatomas, bile-duct adenomas and hepatocellular carcinomas (64 weeks) in very high incidences in females and renal adenomas in male rats.

Animals↗
PubMed1986

Porphyria turcica: hexachlorobenzene-induced porphyria.

It has been estimated that during 1955-1959 in southeastern Turkey, approximately 4000 people developed porphyria due to ingestion of hexachlorobenzene (HCB), a fungicide added to wheat seedlings. Patients subsequently developed bullae on sun-exposed areas, hyperpigmentation, hirsutism, weakness and porphyrinuria. Children born to mothers who had ingested the grain were exposed to HCB in maternal milk and transplacentally, resulting in the death of children under the age of two. In this follow-up study, 204 patients with a past history of HCB-induced porphyria were re-evaluated. There were 132 males and 72 females, with an average age of 32.1 years, an average age of onset of 7.1 years and a duration of 2.4 years. The clinical features of the 204 patients were: scarring of the face and hands in 86.7%, hyperpigmentation in 71.1%, hirsutism in 47.1%, pinched facies in 41.2%, fragile skin in 37.7%, painless arthritis in 66.6%, small hands in 64.2%, an enlarged liver in 4.4% and an enlarged thyroid in 37.3%; most patients also showed neurological symptoms. Urine and stool porphyrin levels were determined in all patients. Seventeen showed elevated levels of one of the porphyrins and eight were considered still porphyric after 25-30 years. A total of 56 specimens of human milk obtained from porphyric mothers were analysed for HCB. The average value was 0.51 ppm compared with 0.07 in controls. After HCB ingestion, abnormal porphyrin metabolism, dermatological, orthopaedic and neurological findings, and HCB residues in the milk of porphyric patients have been shown to persist at least for 25-30 years.

Adult↗
PubMed1985

The central plane of the image layer determined experimentally in various rotational panoramic x-ray machines.

The location of the image layer with respect to how a patient is positioned in a rotational panoramic machine is very critical. At present, no simple method exists for routine testing of panoramic machines to verify that the image layer is where the manufacturer intended it to be. The purpose of this experiment was to locate the central plane of the image layer with respect to a reference point on various machines currently on the market. The data obtained from this study can be used for further evaluations of the consistency in the location of the image layer, first with the existing device and later with a test device that would be adaptable to these machines and serve as a quality-control device in assuring that the machines are functioning properly.

Humans↗
PubMed1982

Image distortion in rotational panoramic radiography. VI. Distortion effects in sliding systems.

A mathematical model for calculating the form distortion in rotational panoramic radiographic systems with a sliding beam path and an elliptical form of the sharply depicted plane was developed. The distortion of a spherical model object was calculated for two different systems exemplifying properties of commercially available equipment. The spherical object was distorted toward an ovoid shape in the image. No marked deviations were found between this ovoid distortion and the ellipsoid distortion previously calculated for a theoretical system having a constant effective projection radius and a cylindrical form of the sharply depicted plane. Except for extremely displaced objects in the anterior region the form reproduction in sliding rotational panoramic systems seems to be satisfactory for clinical purposes.

Computers↗
PubMed1982

Hemolysis and acute renal failure following a Portuguese man-of-war sting.

Portuguese man-of-war stings occur frequently at North American beaches. Most produce only local pain and pruritus. A 4-year-old girl who developed a hemolytic reaction and acute renal failure following a severe sting is described. As neither sequela has been previously reported, it is speculated that either the large dose of venom or chance intravenous inoculation may have been responsible. Evidence of hemolysis should be sought in small children with extensive Portuguese man-of-war stings.

Acute Kidney Injury↗
PubMed1981

A new method for image layer analysis in rotational panoramic radiography.

The position and form of the image layer in rotational panoramic radiography vary from one manufacture to another. A method utilizing a digital computer to calculate the position, form, and relative thickness of the image layer from data obtained from two test radiographs is described. The image layer analysis permits the performance of different rotational panoramic radiographic units to be compared independent of various parameters such as beam width and magnification. The image layers for several commercially available units are illustrated.

Computers↗