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Biomedical subjects

D C Lloyd

Publications and source records attributed to D C Lloyd.

At least 55 records · Page 3Linked to original sources
PubMed1995

The prevalence and prophylaxis of gout in England.

The prevalence of gout in England was reported as having nearly doubled in the 1970s to about 3 per 1000, and it is possible that it has continued to increase. There may also have been some change in the level of prophylactic therapy compared with the 44.8% recorded in 1979. In this study, data were provided from their morbidity registers by 40 volunteer practices with a combined population of over 300,000 patients. Analyses of prevalence by age and sex, and of the extent of prophylaxis were made. The male:female ratio and the increase with age found were in line with earlier work, but overall prevalence was much higher at almost 10 per 1000. There was considerable inter-practice variation: 20% of this could be accounted for by the age and sex structure of the practice populations, but neither economic status nor broad geographical factors appeared to be significant, and it did not appear to be due to variation between practices in the level of special interest in gout. Prophylactic therapy--almost entirely allopurinol--was being prescribed for 48% of the sufferers; though practices varied widely in their propensity to give it, as a group the amount of allopurinol they used was close to the national average. The increase found in the prevalence of gout may be related to an increase in obesity in the population.

Adult↗
PubMed1995

Fluorescence in situ hybridization detection of chromosomal aberrations in human lymphocytes: applicability to biological dosimetry.

Human lymphocytes in G0 have been irradiated with X-ray doses from 0 to 4.0 Gy. Metaphase chromosomes 2, 3 and 5 and all centromeres were painted using fluorescence in situ hybridization (FISH) probe libraries. Dicentrics, centric rings and acentrics in the whole genome as well as translocations involving the painted chromosomes were recorded. The translocations were subdivided as complete or incomplete. Interstitial insertions and inversions were also noted. The observations were also recorded according to the Protocol for Aberration Identification and Nomenclature Terminology (PAINT) system of scoring. Given that the painted chromosomes comprise 20.4% of the genome it was found that the yield of bicoloured dicentrics was consistent with the yield of dicentrics in the whole genome. The yield of radiation-induced translocations was not significantly higher than that of bicoloured dicentrics. Of the translocations, 60% were complete and it was concluded that the majority of dicentrics and translocations are complete exchanges. Chromosome 5 took part in exchanges marginally more commonly than its length suggests, but it is not known if this is a property of the chromosome or whether it is a donor-dependent observation. The PAINT system of recording rearrangements was examined and the suggested numerical interpretation of this nomenclature was considered to be unsuitable for use in the estimation of dose for cases of accidental overexposure.

Adult↗
PubMed1994

Death of a classified worker probably caused by overexposure to gamma radiation.

This paper describes the case of an industrial radiographer who was seriously overexposed to gamma radiation. The exact circumstances of this exposure were not established but it was concluded that he was repeatedly irradiated probably to a total average whole body dose of at least 10 Gy over several years. Also, a much larger dose to a hand required its partial amputation. He developed myelodysplasia, which progressed to acute myeloid leukaemia from which he died. Karyotypic examination of the leukaemic blasts showed changes very similar to those associated with secondary leukaemia that may develop after radio or chemotherapy. The paper describes his medical case history, the investigation of his workplace, and the attempts to estimate his radiation dose by chromosomal analysis of blood lymphocytes and electron spin resonance of dental enamel and bone.

Acute Disease↗
PubMed1993

The effect on apparent size of simulated pulmonary nodules of using three standard CT window settings.

This study was undertaken to determine whether three commonly used combinations of CT display window settings permit accurate measurement of pulmonary nodule size during thoracic CT examination. Forty-five rounded nodules of synthetic material of approximate soft tissue density (+70 Hounsfield units; HU), varying in size from 5.8 mm to 21.4 mm, were suspended in surgical gauze (-900 HU to -950 HU) to simulate pulmonary nodules. CT images were obtained for each nodule using 10 mm and 2 mm CT collimation and the size of each nodule was measured at three window settings: (a) 'soft tissue setting': window width (WW) 400 HU, window level (WL) +20 HU; (b) 'lung setting'. WW 850 HU, WL -750 HU; (c) 'broad lung setting': WW 1350 HU, WL -550 HU. Measurements obtained using either lung setting were highly accurate irrespective of collimation while measurements obtained using soft tissue settings were inaccurate. The choice of display window settings is an important consideration when CT is used to assess the size of pulmonary nodules.

Humans↗
PubMed1993

'Rogue' cells observed in children exposed to radiation from the Chernobyl accident.

Eight 'rogue' lymphocyte metaphases containing a large number of aberrant chromosomes were noted during a survey of chromosomal damage in 328 Belarussian children. The study population comprised children of families living in territory contaminated by radiation from the Chernobyl accident. The majority of the sample had been evacuated within 1 week from very heavily polluted territory to areas that had received much less fallout. Two hundred cells were scored per subject and one rogue cell was found in a child exposed in utero; one in a child conceived after the accident and six in the postnatally exposed group. The possibility that the damage was due to exposure to radio-iodine concentrated in the thyroid gland, or to radiation from incorporated 'hot particles' of an alpha or beta/gamma emitter is discussed. It is concluded that the damage to these cells is unlikely to have been caused by radiation.

Accidents↗
PubMed1993

[Chromosomal damages in human lymphocytes induced by low doses of irradiation].

The observation of chromosomal aberrations in circulating lymphocytes is the most sensitive biological indicator of human exposure to ionising radiation. Data at low doses from in vivo and in vitro irradiated lymphocytes are reviewed. Statistical uncertainties mean that no resolution can be made between a linear or threshold response in the range 0-20 mGy of low LET radiation. Above 20 mGy the data conform to the linear quadratic model. The possibility of measuring chromosomal aberrations for dose estimation, to be used in conjunction with epidemiological studies on groups of persons exposed to radiation from the Chernobyl accident, is discussed.

Cells, Cultured↗
PubMed1992

A survey of lymphocyte chromosomal damage in Slovenian workers exposed to occupational clastogens.

Assays for sister-chromatid exchanges (SCE), unstable chromosome and chromatid aberrations and micronuclei were performed on blood lymphocytes from persons exposed protractedly to radiation or chemical hazards in the workplace. There was a general tendency with all endpoints examined for the yields to increase with years of working in the industry. This was especially marked for SCE. By comparison with a control group of administrative workers the levels of damage were higher, usually significantly so, in the occupational groups. These comprised workers at a nuclear research reactor, a hospital diagnostic X-ray department, a coal mine and a mercury ore mine.

Adult↗
PubMed1992

Case report: small bowel volvulus presenting during pregnancy.

The diagnostic use of ionizing radiation during pregnancy is to be avoided whenever possible due to the risk to the unborn child. However, vomiting presenting after the first trimester of pregnancy is unusual, and if severe or persistent, requires investigation. We present a case where reluctance to expose the fetus to radiation could have resulted in a potentially serious delay in the diagnosis of maternal small bowel volvulus.

Adult↗
PubMed1992

The computed tomographic appearances in pulmonary artery atresia.

Isolated pulmonary artery atresia is an uncommon congenital abnormality. Plain radiography and ventilation/perfusion lung scintigraphy may suggest the diagnosis but pulmonary angiography has traditionally been recommended for confirmation. The computed tomographic (CT) appearances of four patients with isolated atresia of a pulmonary artery are described. In each case the atretic segment of the abnormal vessel could be identified. Other CT findings included reduction of volume of the involved hemithorax, increased density of the affected lung, a small hilum, and an abnormal pulmonary vascular pattern thought to be due to the collateral systemic arterial supply to the intrapulmonary branches of the atretic pulmonary artery. The diagnosis of isolated pulmonary artery atresia can be made using dynamic, contrast enhanced CT without recourse to more invasive procedures.

Adolescent↗
PubMed1992

Chromosomal aberrations in human lymphocytes induced in vitro by very low doses of X-rays.

This paper presents results of a collaborative experiment between six laboratories which examined the yields of unstable chromosomal aberrations in human lymphocytes induced in vitro by X-rays over the dose range 0-300 mGy. The work included data points of nominal doses of 0, 3, 5, 6, 10, 20, 30, 50 and 300 mGy. Cells from 24 donors were examined and a total of about 300,000 metaphases were scored. The work was undertaken to determine the limits of sensitivity of the system taking into account variations in scoring data due to inter-donor sample and inter-laboratory effects. Despite the existence of these effects, aberration yields significantly in excess of control values were seen at doses greater than 20 mGy and these were consistent with a linear extrapolation from higher doses. Below 20 mGy the observed dicentric yields were generally lower than background, but not significantly so. Excess acentric aberrations, on the other hand, and centric rings, were higher than the controls but the increase was usually not significant. It is concluded that the statistical uncertainties are such that below 20 mGy this technique cannot distinguish between a linear or a threshold model.

Chromosome Aberrations↗
PubMed1990

The relationship between colony-forming ability and chromosomal aberrations induced in human T-lymphocytes after gamma-irradiation.

Using aliquots from the same samples of irradiated normal human blood, T-lymphocyte survival was measured by (a) 14-day colony growth, (b) the proportion of chromosomally normal first post-irradiation metaphases and (c) the proportion of cells not suffering interphase death and delay within 48 h after irradiation. Combining (b) and (c) gives a prediction of the proportion of cytogenetically undamaged cells which reach metaphase after 48 h. These cells should be capable of producing viable colonies under suitable culture conditions. A comparison of these values with those observed in (a) shows a reasonable agreement in accordance with the hypothesis that gross chromosomal damage and cell reproductive death are closely related.

Cell Survival↗