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Biomedical subjects

M Hall

Publications and source records attributed to M Hall.

At least 235 records · Page 13Linked to original sources
PubMed1988

Stereoselective aspects of the metabolic activation of benzo[a]pyrene by human skin in vitro.

Benzo[a]pyrene (BP) is activated within tissues in both a regio- and a stereoselective manner and, since human skin is sensitive to tumour induction by polycyclic aromatic hydrocarbons (PAH), the steroselective metabolism of BP in this tissue has been investigated. Samples of skin from eleven individuals were treated with [3H]BP in short-term organ culture. Two samples were also treated with mixtures of [14C](+)- and (-)-trans-7,8-dihydro-7,8-dihydroxybenzo[a]pyrene (BP-7,8-dihydrodiol) in varying proportions. Following application of [3H] BP, more 7,8-dihydrodiol was recovered from the skin itself than from the culture fluid in ten cases; no 7.8-dihydrodiol was detected in extracts from the eleventh. The 7,8-dihydrodiol metabolite was extracted predominantly (range 74-greater than 99%) as the (-)-enantiomer in nine of these ten patients, although proportionately more (+)-enantiomer was recovered from the culture fluid than from the skin in each case. The relative proportions of [3H]BP tetrols derived from syn- and anti-7,8-dihydroxy-9,10-oxy-7,8,9,10-tetrahydroxybenzo[a]pyrene (BPDE) detected in these extracts was more variable. When skin samples were treated with [14C]BP-7,8-dihydrodiol, more anti- than syn-BPDE-derived tetrols were extracted, irrespective of the optical purity of the dihydrodiol applied. These findings provide evidence for interindividual variations in the stereoselective metabolism of BP, which may be of some importance in determining individual susceptibility to PAH-induced skin carcinogenesis.

Benzo(a)pyrene↗
PubMed1988

Rotational endarterectomy in normal canine coronary arteries: preliminary report.

Endarterectomy was performed in vivo using a high speed rotating abrasive-tipped catheter device in 11 normal canine coronary arteries. The device is designed to remove atheromatous material from diseased arteries by the abrasive action of its rotating tip. It was operated percutaneously from a femoral approach using conventional angioplasty guiding equipment. The rotating device was advanced over a guide wire from just beyond the tip of the guide catheter into the distal vessel. Six arteries were harvested immediately after endarterectomy and five were left in place for 7 +/- 2.8 days; in the latter group, the animals were maintained on a regimen of aspirin, 325 mg/day. Angiography before and after treatment demonstrated vessel patency in all cases. Caliper-measured luminal diameters were not significantly changed after endarterectomy. Histologic examination of pressure-fixed vessels showed extensive intimal loss and 20 to 30% loss of the internal elastic lamina. Medial damage was superficial and never exceeded 40% of the total medial thickness. There were no vessel perforations. Results of histologic study of the myocardium supplied by the treated vessels were normal without evidence of distal embolization or infarction. It is concluded that a high speed rotating abrasive device can be safely operated percutaneously in normal coronary arteries and results in minimal vessel damage and continued patency at 7 +/- 2.8 days.

Angioplasty, Balloon↗
PubMed1988

Further metabolism of diol-epoxides of chrysene and dibenz[a,c]anthracene to DNA binding species as evidenced by 32P-postlabelling analysis.

Incubation of r-1,t-2-dihydroxy-t-3,4-oxy-1,2,3,4-tetrahydrochrysene (anti-chrysene-1,2-diol 3,4-oxide), the bay-region diol-epoxide of chrysene, with rat liver microsomes in the presence of NADP+ and DNA, followed by 32P-postlabelling analysis of the DNA, revealed the presence of at least two adducts not detected when anti-chrysene-1,2-diol 3,4-oxide was incubated with DNA alone. The formation of these adducts was not blocked by the epoxide hydrolase inhibitor 1,1,1-trichloropropane-2,3-oxide. One of the adducts cochromatographed with the adduct spot obtained when authentic 9-hydroxy-r-1,t-2-dihydroxy-t-3,4-oxy-1,2,3,4-tetrahydrochrysene (anti-9-OH-chrysene-1,2-diol 3,4-oxide) was reacted with DNA. Evidence suggested that a second adduct could also be formed by further metabolism of anti-9-OH-chrysene-1,2-diol 3,4-oxide. In addition, evidence was obtained for the further metabolism of the syn-isomer of chrysene 1,2-diol 3,4-oxide and the anti-isomer of a non-bay-region diol-epoxide of dibenz[a,c]anthracene to DNA binding species, but not for that of either the anti- or syn-isomers of the bay-region diol-epoxide of benzo[a]pyrene, the anti-isomers of the bay-region or a non-bay-region diol-epoxide of benz[a]anthracene, or the anti-isomer of the bay-region diol-epoxide of benzo[b]fluoranthene.

Animals↗
PubMed1988

Long-term follow-up of separate glomerular filtration rate in partially obstructed kidneys. Experimental study.

An often encountered assumption is that non-relieved renal obstruction will lead soon or late to progressive deterioration of the renal function. The effect of non-relieved partial ureteral obstruction on the separate glomerular filtration rate (SGFR) was studied throughout the whole life of a series of rats, who were submitted at the age of 3 months to partial obstruction of the left ureter. An initial and variable postoperative SGFR decrease was gradually observed, but after this period, SGFR remained stable until the natural death of the animal.

Animals↗
PubMed1988

Immunoenzymometric assay of creatine kinase with monoclonal antibodies to the MB isoenzyme compared with electrophoresis.

We compare a "second-generation" immunoenzymometric assay (Tandem-E CKMB II) for creatine kinase (EC 2.7.3.2) MB with its electrophoretic (Beckman Paragon system) determination. In the former, two monoclonal antibodies are directed against the B and M subunits. We evaluated 502 samples from 253 patients. Precision, linearity, and analytical recovery for both assays were excellent. The two methods correlated well (r = 0.936). The reference interval for individuals with no suspected cardiac disorder was 0-6.0 micrograms/L; that for non-infarct patients was 0-18.0 micrograms/L. Peak CK-MB values determined by the two assays agreed for 95% of the patients, in terms of exceeding the normal reference interval or not. Diagnostic efficiencies were 86% (Tandem) and 88% (electrophoresis). The immunoenzymometric assay showed no cross reaction with other CK isoenzymes. Both assay methods performed well in detecting CK-MB, although there were some false positives by both methods, as judged from electrocardiographic results. When total CK for the Tandem assay exceeds 2000 U/L, we recommend calculation of a ratio (CK-MB, micrograms/L:total CK, U/L).

Antibodies, Monoclonal↗
PubMed1987

Raised cerebrospinal-fluid copper concentration in Parkinson's disease.

The cerebrospinal-fluid copper concentration, measured by electrothermal atomisation/atomic absorption spectrophotometry, was significantly higher in 24 patients with untreated, idiopathic Parkinson's disease than in a control population of 34 patients (p less than 0.001). The difference in the in-vitro capacity of copper to damage DNA, measured by the phenanthroline assay was even greater. The high phenanthroline-copper concentration correlated with disease severity (p = 0.02) and with the rate of progression of disease (p less than 0.05). A possible role is suggested for copper-catalysed oxidative mechanisms in the pathogenesis of Parkinson's disease.

Adult↗
PubMed1987

Differential stereoselectivity in the metabolism of benzo[a]pyrene and anthracene by rabbit epidermal and hepatic microsomes.

The stereoselective metabolism of benzo[a]pyrene (BP) to its 7,8-dihydrodiol and of anthracene to its 1,2-dihydrodiol by microsomal fractions of the liver and skin of the rabbit were examined. For both tissues, more anthracene-1,2-dihydrodiol than BP-7,8-dihydrodiol was extracted from these incubations. The BP-7R,8R and anthracene-1S,2S enantiomers were found to predominate with optical purities of greater than or equal to 90% and 32%, respectively. The latter result is in contrast to previous observations made in incubations with rat liver microsomes and might be due to differences in stereoselectivities of cytochromes P-450 between the two species.

Animals↗
PubMed1987

Low-glycemic index diet in hyperlipidemia: use of traditional starchy foods.

To define those patients most likely to benefit from the hypolipidemic effect of low-glycemic-index (GI) traditional starchy foods, 30 hyperlipidemic patients were studied for 3 mo. During the middle month, low-GI foods were substituted for those with a higher GI with minimal change in dietary macronutrient and fiber content. Only in the group (24 patients) with raised triglyceride levels (types IIb, III, and IV) were significant lipid reductions seen: total cholesterol 8.8 +/- 1.5% (p less than 0.001), LDL cholesterol 9.1 +/- 2.4% (p less than 0.001), and serum triglyceride 19.3 +/- 3.2% (p less than 0.001) with no change in HDL cholesterol. The percentage reduction in serum triglyceride related to the initial triglyceride levels (r = 0.56, p less than 0.01). The small weight loss (0.4 kg) on the low-GI diet did not relate to the lipid changes. Low-GI diets may be of use in the management of lipid abnormalities associated with hypertriglyceridemia.

Adult↗
PubMed1987

Sex therapy with lesbian couples: a four stage approach.

The many factors--social, cultural, psychological--that shape homosexual sexual expression render purely behavioral sex therapy models one-dimensional and ineffective for lesbian clients with sexual presenting problems. Though a behavioral approach may be useful later in the treatment of such problems, the effective clinician must first address the inimical social and cultural contexts that frame lesbian sexual impasses. This paper offers specific techniques, both direct and indirect, designed to illuminate and neutralize these contexts. Additionally, the author presents a sequence of sensate focus exercises tailored to the particular needs of lesbian couples.

Adult↗
PubMed1987

Unlocking information technology.

Computer technology has made vast quantities of information more readily available through accessible data bases. This article discusses the use of information technology and some of the problems that have prevented it from being more widely used. Also included is information on some rehabilitation-related data bases.

Computer Literacy↗