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Biomedical subjects

A Samuel

Publications and source records attributed to A Samuel.

31 records · Page 2Linked to original sources
PubMed1985

A study of alpha thalassaemia families in western Saudi Arabia.

In Saudi Arabia there are three alpha globin chain alleles alpha alpha/, -alpha/, alpha alpha T/-producing six genotypes. In this study of 12 alpha thalassaemia families, the phenotypic expression of these six genotypes is determined. Globin chain biosynthesis gave five non overlapping ratios of 0.9 +/- 0.05, 0.69 +/- 0.06, 0.5 +/- 0.03, 0.38 +/- 0.04 and 0.23 +/- 0.06. The five groups are shown to be normal, alpha thal 2 trait with genotype -alpha/ alpha alpha, mild alpha thal 1 with -alpha/-alpha and alpha alpha/alpha alpha T as genotypes, severe alpha thal 1 with genotype -alpha/alpha alpha T and Hb H disease. The red cell indices MCV, MCH and MCHC of the groups show a step ladder fall. Hb H inclusions in red cells are slight in the mild alpha thal 1 and rises to gross in Hb H disease. The latter disease also shares typical red blood cell appearances with severe alpha thal 1. Hb H disease is relatively mild with no gross bony changes.

Adolescent↗
PubMed1980

Iridium- 191 angiocardiography for the detection and quantitation of left-to-right shunting.

An osmium- 191 leads to iridium- 191 generator that can deliver multiple doses of Ir- 191m for first-pass radionuclide angiography has been developed. Iridium- 191m has a physical half-life of 4.96 sec and decays with emission of 65-keV and 129-keV photons in 58 and 30% abundance, respectively. Using a gamma camera, Ir- 191m radionuclide angiography was carried out, in dogs and ten patients, for the detection and quantitation of left-to-right shunting. In a one-year-old patients, 25 mCi of Ir- 191m results in a whole-body radiation absorbed dose of 35 mrad. Multiple Ir- 191m angiograms can be performed, seconds to minutes apart, without interference from background. The 15.4-day half-life of Os- 191 permits transportation of the generator to centers far from the production facility. With the low radiation dose, high information density, and the ability to repeat studies with Ir- 191m, clinical use of radionuclide angiography should be expanded.

Adolescent↗
PubMed1980

A new osmium-191 leads to iridium-191m generator.

A new osmium-191 leads to iridium-191m generator suitable for first-pass radionuclide angiocardiography has been developed. This generator system allows repeated elutions of 4.96-sec iridium-191m from its 15.4-day Os- 191 parent. The Os-191 is loaded on an anion-exchange column (AGMP-1) and Ir- 191m eluted with 0.9% NaCl at pH 1. Each elution (0.6 to 1 ml) of the generator yields about 7 to 10% Ir-191m and gives 0.003-0.008% of Os-191 breakthrough. Toxicity studies of the generator eluate carried out in animals support the safety of using iridium-191m in humans. The long shelf-life of the generator (approximately equal to 2 wk) will allow medical centers to use Ir- 191m for routine clinical diagnosis. Iridium-191m obtained by this method should find additional useful applications in nuclear medicine.

Animals↗
PubMed1979

Desferoxamine mesylate (Desferal): a contrast-enhancing agent for gallium-37 imaging.

Desferal (desferoxamine mesylate) was investigated as a contrast-enhancing agent for tumor and abscess imaging with 67Ga-citrate. Tumor studies were performed in mice with Cloudman S-91 melanoma. Abscess studies were performed with a subcutaneous abscess model in rabbits. When Desferal is administered 16 to 18 hours after injection of 67Ga, rapid blood clearance of 67 Ga occurs with only slight (tumor) or no (abscess) loss of activity from the lesion. Retention in other organs is variable. Tumor-to-blood ratios are improved eightfold in tumor and fourfold in abscess in studies performed with single Desferal injections of 150 mg/kg. Blood and total body clearance studies in rabbits reveal that maximum Desferal effect is achieved in the 17 to 50 mg/kg dose range and that only minimal improvement occurs at higher doses.

Abscess↗
PubMed1976

Late thrombosis of the aortic Bjork-Shiley prosthesis. Its clinical recognition and management.

Seven cases of massive thrombosis of an aortic Bjork-Shiley prosthesis were encountered among 433 valvular implants. Four patients died before treatment could be instituted, and three underwent repeat surgery successfully. Anticoagulation therapy was probably well maintained in four, and poorly maintained in three patients. These cases illustrated the need for a high index of suspicion and prompt recognition of this complication in patients with Bjork-Shiley prostheses. The diagnosis of massive thrombosis should be suspected with the rapid onset of (1) signs of congestive heart failure, (2) absence or attenuation of valvular clicks, (3) aortic regurgitation, or (4) hemolytic anemia. Salvage of these patients requires emergency replacement of the thrombosed prosthesis or removal of the thrombus.

Aged↗
PubMed1975

Localization in the cell cycle of the antimitotic action of the pyrrolizidine alkaloid, lasiocarpine and of its metabolite, dehydroheliotridine.

The antimitotic action of the pyrrolizidine alkaloid lasiocarpine on rat liver parenchyma was investigated using as the experimental model the wave of mitosis produced in liver by a single dose of thioacetamide. A single low dose of lasiocarpine administered two weeks before the thioacetamide, almost completely inhibited the mitotic wave without inhibiting to the same extent the preceding wave of DNA synthesis. By the use of selective inhibitors and radioisotope labelling, the location of the mitotic block was found to be either in the latter half of the DNA synthetic phase, S, or early in G2, the post-synthetic phase. The mitotic wave was similarly inhibited by pretreatment of the rats with a single injection of dehydroheliotridine, a pyrrolic metabolite of heliotridine-based pyrrolizidine alkaloids.

Animals↗
PubMed1975

Preliminary experience with the use of a programmable pacemaker.

One hundred sixty-four patients, in whom new externally programmable pacemakers had been inserted, were studied over a two year period, beginning July, 1972. Following implantation, the rate and current output of this pacemaker could be changed at any time by a non-invasive technique involving electromagnetic pulse trains emitted by an external "programmer". In 89 percent of the patients it was possible to reduce battery output by half, implying greater longevity of the pacer in these cases. In 15 percent of the patients, manipulative control of the pacemaker rate was employed and found beneficial.

Adult↗
PubMedDate not supplied

Exploratory research as andragogic continuing education.

The continuing education aspect of an exploratory research project was evaluated in terms of Knowles's learning assumptions and teaching design factors. Although most of the project's assumptions were congruent with Knowles's andragogic assumptions, the design factors were found to be more pedagogic. Using more andragogic design factors in the future would strengthen this continuing education approach.

Adult↗