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Biomedical subjects

P Dolan

Publications and source records attributed to P Dolan.

At least 109 records · Page 6Linked to original sources
PubMed1987

The short-term effects of chymopapain on intervertebral discs.

Cadaveric lumbar discs were injected with chymopapain and subjected to a series of mechanical tests over a period of up to 19 hours. Discs from the same spine injected with saline were used as controls. The results showed that chymopapain had no measurable effect on the mechanical properties of the disc apart from the increased height and stiffening caused by fluid injection. Another series of tests on isolated pieces of disc material showed that chymopapain could reduce the size of prolapsed nuclear material by 24% in one hour and by 80% in 48 hours. It is concluded that, in the short-term, chymopapain has a negligible effect on the mechanics of a disc but it can reduce the size of any prolapsed nuclear material with which it comes in contact.

Adult↗
PubMed1986

Biochemical effects of dithiolthiones.

Administration of dithiolthiones to mice in single intragastric doses (2-4 mmol/kg body weight) or in the diet (0.5% for 14 days), and to rats in the diet (0.1% for 14 days) was found to increase glutathione levels and the activities of a number of enzymes in various tissues including the liver and lung. The enzymes affected were glutathione transferases (with chlorodinitrobenzene or dichloronitrobenzene), quinone and glutathione reductase, and glucose-6-phosphate and 6-phosphogluconate dehydrogenase, all of which are involved directly or indirectly in the detoxication of xenobiotics, including carcinogens. The dithiolthiones tested in mice were oltipraz, ADT, 116L and 129L, and in rats, oltipraz. Intragastric administration of dithiolthiones (oltipraz, ADT or 116L; two doses each of 1 g/kg body weight) did not increase glutathione levels or enzyme activities in murine mammary adenocarcinoma transplants. Increases in glutathione levels and enzyme activities similar to those found with dithiolthiones were observed when a semi-synthetic diet containing 10-40% lyophilized cabbage was fed to mice for 30 days. Dithiolthiones that are present in cabbage may play a role in the protective actions of diets high in vegetables against the toxic actions of xenobiotics. The biochemical effects of dithiolthiones reported here may account for the protective actions of these compounds.

Animal Feed↗
PubMed1986

1,2-Dithiol-3-thione analogs: effects on NAD(P)H:quinone reductase and glutathione levels in murine hepatoma cells.

The 1,2-dithiol-3-thiones are a class of five-membered cyclic sulfur compounds which have chemotherapeutic and chemoprotective properties. The parent 1,2-dithiol-3-thione nucleus and a series of six substituted analogs all induced NAD(P)H: quinone reductase (EC 1.6.99.2) activity and elevated glutathione levels in Hepa 1c1c7 murine hepatoma cells in culture thereby enhancing detoxification potential. These analogs included monosubstituted derivatives with phenyl, p-methoxyphenyl or 2-pyrazinyl groups at C-4 or C-5, and disubstituted compounds bearing phenyl or 2-pyrazinyl moieties at C-5 and an additional methyl group at C-4. This system can be used as an in vitro model for the study of the specificity and mechanism of action of the 1,2-dithiol-3-thiones as already demonstrated for several other classes of chemoprotective agents. The 1,2-dithiol-3-thiones also elevated quinone reductase and glutathione levels in the Hepa 1c1c7 cell mutants (BPrc1 and TAOBPrc1) that are defective in aryl hydrocarbon receptor functions. We conclude that the 1,2-dithiol-3-thiones are largely concerned with the stimulation of metabolic inactivation of electrophiles.

Animals↗
PubMed1986

The stages of disc degeneration as revealed by discograms.

One hundred and thirty-nine discs from cadaveric lumbar spines were injected with a mixture of radio-opaque fluid and dye. Discograms were taken and the discs were then sectioned in the sagittal plane. Examination of the sections revealed that injected fluid did not at first mix with the disc matrix but pushed it aside to form pools of injected fluid. The location of these pools, and hence the appearance of a discogram, depended on the stage of degeneration of the disc. It is concluded that useful clinical information can be obtained from discograms.

Adolescent↗
PubMed1984

Necrotising enterocolitis experience with 54 neonates.

Fifty-four neonates transferred to the neonatal surgical unit because of acute necrotising enterocolitis (N.E.C.) are presented. Eleven died (20.4%), of whom seven were treated conservatively and four by operation. Ten patients required surgical exploration because of intestinal perforation, obstruction or suspected perforation. Another five neonates presented with intestinal perforation and were treated by percutaneous catheter drainage of the peritoneal cavity because of their extreme prematurity. Nine patients developed a colonic stricture diagnosed between six weeks and a year after the onset of the disease. Another six patients showed a segment of colonic narrowing detected on barium enema radiography without clinical evidence of bowel obstruction. They were treated conservatively and showed complete resolution at follow up studies.

Enterocolitis, Pseudomembranous↗
PubMed1982

The antischistosomal activity of oltipraz.

Administration of a single oral dose of oltipraz (5-(2-pyrazinyl)-4 methyl-1,2 dithiol-3-thione) to mice infected with Schistosoma mansoni resulted in the elimination of the parasites. Oltipraz is a slow-acting drug and approximately 2 months are required until its full schistosomicidal effect becomes evident. One of the earliest effects of the drug is a reduction of the glutathione stores of the worms. The antischistosomal activity of oltipraz is lowered when drug metabolism is stimulated by pretreatment with phenobarbital or butyl-hydroxyanisole (BHA). By contrast, administration of L-cysteine is synergistic with the antischistosomal effect of oltipraz. Evaluation of a limited number of oltipraz analogs revealed among dithiolthiones rather stringent structural requirements for antischistosomal activity.

Animals↗
PubMed1976

Serum-free and protein-bound sugars and cardiovascular complications in diabetes mellitus.

Free and protein-bound serum sugars and serum lipids were analyzed in 65 adult diabetic patients, 10 age-matched controls, and 24 male medical students for correlation of carbohydrate changes with the extent of retinal, renal, and cardiovascular disease. In diabetic sera, both protein-bound sugars and free mannose, fucose, and hexosamine were significantly elevated; free galactose and inositol were elevated in some diabetic patients, and essentially undetectable in sera from controls. Serum triglycerides and pre-beta-lipoproteins were also elevated in diabetics, but alpha-lipoproteins decreased. Although no specific relationships were observed with the extent of retinal and renal disease, bivariate analyses by Pearson coefficients of correlation showed correlations between levels of serum-free mannose and systolic blood pressure, free hexosamine and duration of diabetes, and serum protein-bound fucose and age. Serum triglycerides and pre-beta-lipoprotein levels correlated with insulin therapy. These are preliminary leads of laboratory studies related to carbohydrate macromolecular changes which might aid in a better understanding of the cardiovascular complications associated with diabetes.

Adult↗
PubMed1975

Lipoprotein-acid mucopolysaccharide complexes of human atherosclerotic lesions.

Lipoprotein-acid mucopolysaccharide complexes occurring in different types of human atherosclerotic lesions were isolated and partially characterized. Complexes from fatty streaks and fibrous plaques were extracted from pooled tissues with 0.15 M NaCl, purified by gel filtration, and fractionated by ultracentrifugation. Both low and very low density lipoproteins were present; low density lipoprotein was predominant. The complexes were analyzed for uronic acid, cholesterol, phospholipid, and Ca-2+ contents; there was no significant difference in the relative molar ratios between complexes from fatty streaks and fibrous plaques. Acid mucopolysaccharides were isolated from the complexes and identified by electrophoresis and enzymatic studies. Chondroitin sulfate C and hyaluronic acid were found in complexes from fatty streaks and fibrous plaques. Heparin was detected only in fibrous plaques.

Aorta↗
PubMedDate not supplied

The time trade-off method: results from a general population study.

An important consideration when establishing priorities in health care is the likely effects that alternative allocations of resources will have on health-related quality-of-life (HRQoL). This paper reports on a large-scale national study that elicited the relative valuations attached by the general public to different states of health (defined in HRQoL terms). Health state valuations were derived using the time trade-off (TTO) method. The data from 3395 respondents were highly consistent, suggesting that it is feasible to use the TTO method to elicit valuations from the general public. The paper shows that valuations for severe health states appear to be affected by the age and the sex of the respondent; those aged 18-59 have higher valuations than those aged 60 or over and men have higher valuations than women. These results contradict those reported elsewhere and suggest that the small samples used in other studies may be concealing real differences that exist between population sub-groups. This has important implications for public policy decisions.

Adolescent↗