Search PubMed⌕ Search

Biomedical subjects

R M Harrison

Publications and source records attributed to R M Harrison.

At least 91 records · Page 5Linked to original sources
PubMed1985

Sperm parameters and testicular volumes in Saguinus mystax.

Adult male Saguinus mystax tamarins were evaluated for sperm parameters and testicular volumes. Sperm concentrations average 195.5 X 10(6)/cc with 41.7% motile sperm. Semen specimens were classified as normal, relative to sperm morphology, when 95% or more of the sperm in the specimen had normal morphology; 76% of the animals evaluated had normal semen specimens using this criterion. Testicular volumes averaged 726.9 mm3. A total of 50 infants were sired by 16 of these males during the period covered by this report.

Animals↗
PubMed1985

Testicular blood flow in monkeys as measured by xenon clearance and radioactive microspheres.

Testicular blood flow was measured in monkeys using a 133xenon clearance technique and a 141cerium microsphere entrapment technique. The clearance procedure provided values that tended to be lower than those obtained using the microspheres, was technically less difficult, and has the advantage of being a clinical tool. The microsphere entrapment technique provides the simultaneous evaluations in numerous tissue sites but requires the removal of the tissues to be evaluated. The xenon clearance technique appears to be better suited for evaluations in nonhuman primates.

Animals↗
PubMed1983

Physico-chemical characterization of atmospheric trace metal emissions from a primary zinc-lead smelter.

Emissions from the stacks of a major primary zinc--lead smelter were characterised using X-ray powder diffraction spectrometry (XRD). The following chemical phases were identified: PbSO4, PbO X PbSO4, PbO, PbS, PbO, ZnO, alpha-ZnS, CdO. A complementary environmental investigation revealed that, within the works boundary, the airborne metals might be associated mainly with the fugitive blowage of coarse particles containing primary ore minerals. However, such fugitive emissions were found to be of low significance in the local environment outside the works perimeter, where fine particle emissions from the stacks of the smelter were the predominant source of airborne cadmium, lead and zinc.

Air Pollutants↗
PubMed1983

Ambient air quality in the vicinity of a works manufacturing sulphuric acid, phosphoric acid and sodium tripolyphosphate.

Airborne concentrations of sulphur dioxide, nitrogen dioxide, sulphate and fluorides have been determined in the vicinity of a large industrial producer of sulphuric acid, phosphoric acid and sodium tripolyphosphate. The results indicate that the Works does not contribute significantly to 24-h average levels of nitrogen dioxide or sulphuric acid, but does cause an elevation in local sulphur dioxide and fluoride concentrations. Measurements of phosphate deposition demonstrate that the Works is a source of both condensed phosphate and orthophosphate emissions. It is concluded that ambient air pollution concentrations are well within accepted standards for human health, but that alleged damage to garden plants may be due to airborne fluorides and/or phosphate deposition.

Air↗
PubMed1983

Tissue-air ratios and scatter-air ratios for diagnostic radiology (1-4 mm Al HVL).

Tissue-air and scatter-air ratios for use in diagnostic radiology (1-4 mm Al HVL) have been calculated from previously reported measurements of percentage depth doses (PDD) and backscatter factors (BSF) for the same quality range. Tabulations of TAR are presented. The calculated TARs are compared with direct measurements of TAR which have been carried out by other workers. TARs and SARs are shown to be functions of peak tube potential for a given first HVL as a consequence of a similar dependence of PDD. This emphasises once again the inadequacy of the first HVL alone as a specifier of beam quality.

Radiation Dosage↗
PubMed1983

Theoretical and experimental studies of the influence of air kerma rate on threshold contrast in diagnostic fluoroscopy systems.

Experimental measurements of threshold contrast (CT) as a function of air kerma rate at the input plane of the image intensifier have been made for several diagnostic fluoroscopy units in clinical use. Threshold contrasts are determined by viewing a test object containing holes of fixed diameter and various depths under defined irradiation conditions. Kerma rate variations are effected by introducing aluminum sheets into the x-ray beam at fixed values of tube potential and current. At low kerma rates where quantum noise dominates, low tube potentials (60 kVp) usually yield lower values of CT than do higher potentials (100 kVp). At higher kerma rates the opposite is often true. A simple theoretical model for noise propagation in fluoroscopic imaging systems using models of diagnostic x-ray spectra lends qualitative support to the experimental findings. The often-quoted suggested upper limit of 100 mu R s-1 (0.87 mu Gy s-1) at the input phosphor would seem to be justified under the test conditions since little improvement in CT is usually observed at higher kerma rates. However, application to clinical practice would ideally require the use of more realistic phantom studies.

Air↗
PubMed1983

A re-evaluation of the 'saturated scatter' method for estimating the energy imparted to patients during diagnostic radiology examinations.

Central-axis depth dose data for diagnostic qualities (1-4 mm Al HVL) have been used to calculate the total energy imparted to patients or phantoms during X-ray examinations. A 'saturated scatter' method has been used and allowance is made for the finite dimensions of the patient by using PDD data for large but finite field sizes. For the purpose of integration, PDD data have been represented as a function of depth by two exponential components. Data in the form of energy imparted per unit central-axis surface dose and per unit surface X-ray field are tabulated as functions of kVp, first HVL, phantom thickness and the field size of the original PDD data. Comparison with energy fluence calculations of total energy imparted made by other workers indicates good agreement under similar phantom and X-ray quality conditions, although it is noted that anatomical variations between patients will in practice lead to uncertainties in the total energy imparted.

Humans↗
PubMed1982

Backscatter factors for diagnostic radiology (1-4 mm Al HVL).

Backscatter factors (BSF) in the diagnostic radiology quality range (1-4 mm Al) have been determined by ionisation chamber and TLD techniques. Ionisation chamber measurements are subject to systematic errors due to displacement of the scattering medium, although high precision allows the demonstration of the kVp dependence of BSF for a given first HVL. TLD techniques lead to a reduction of these systematic errors although the read-out procedures lead to lower precision than ionisation chamber measurements. Comparison of the TLD-based measurements with the data of Br. J. Radiol. Supplement 11 indicates good agreement (less than 2%) for HVLS greater than 2 mm Al and field sizes greater than 10 cm x 10 cm. Comparison with the work of other authors not covered by Supplement 11 indicates, in general, good agreement only where kVp-filter combinations are similar. The importance is stressed of taking into account the kVp-filter combination when defining the quality of an X-ray beam.

Radiation Dosage↗
PubMed1982

Women's treatment decisions for genital symptoms.

A study of illness behaviour and sexually transmitted diseases (STDs) investigated the ways in which women with symptoms potentially attributable to STD reached a decision on whether or not treatment should be sought. It was found that non-treatment of genital symptoms is partially explained by women classifying symptoms as normal: 53% among those not seeking treatment did so, compared to 12% and 10% in the two treated groups. When people are uncertain about symptoms there is a motivation to seek treatment. Thus, nearly all women in this category thought treatment necessary. Even among women who do seek treatment, the majority do so only after a period of waiting. Only 45% and 43% in the two treated groups reported seeking treatment immediately. The biological and sociological background relevant to treatment decisions indicate that it will be difficult to achieve changes in these percentages.

Female↗
PubMed1981

Lead content of small mammals at a roadside site in relation to the pathways of exposure.

Concentration of lead have been determined in three species of small mammal, Sorex araneus, Clethrionomys glareolus and Apodemus sylvaticus at roadside and control sites. The results are considered in relation to the lead content of the diet and the air, and it is concluded that the diet provides far the major pathway for lead exposure, even at the roadside site. Bone lead concentrations are found to be consistent with estimated lead exposure and metabolism.

Animals↗
PubMed1981

Central-axis depth-dose data for diagnostic radiology.

Depth-dose data have been measured for a range of irradiation conditions relevant to diagnostic radiology in order to provide a basis for the calculation of patient dosage arising from X-ray examinations. In general, data are required for larger field sizes, longer source-surface distances and greater tube filtrations than are commonly encountered in radiotherapy. Principles and techniques of measurement are discussed with particular attention to the specification of X-ray beam quality. It is recommended that both peak tube potential and first half-value thickness should be specified, especially for the determination of doses at depths of 5 cm or more. With the appropriate specification of quality, good agreement is found between these measurements and other compilations of depth-dose data for radiotherapy use. Zero-area depth-doses have also been measured and compared with calculated values derived from theoretical considerations of X-ray beam spectra.

Radiation Dosage↗
PubMed1981

Culture of seminal fluid in a fertility clinic.

To determine whether the culture of seminal fluid in a fertility clinic is of importance, bacterial cultures were obtained in a consecutive series of 96 patients. Routine bacteriologic cultures were performed within 1 hour of collection. Ureaplasma urealyticum (T-mycoplasma) cultures were also obtained in the last 31 of the patients in this series. Of these 96 patients, 11% showed significant bacterial growth (greater than 10(4) colonies/ml) in the semen specimens, 8% in those patients with normal semen analyses and 14% in those with abnormal analyses. Fifty-eight per cent of semen specimens were positive for U. urealyticum. In reference to normal and abnormal semen analyses the distribution was the same regardless of the presence or absence of U. urealyticum. Antibiotic treatment resulted in minor changes in motility and morphology in a few patients despite conversion to a negative culture. Cultures were also coordinated with microscopic urinalysis and the presence of white blood cells or bacteria in stained smears of semen. There were no significant differences between groups with positive or negative cultures. Trichomonas vaginalis was not seen.

Bacteriological Techniques↗