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Biomedical subjects

H T Delves

Publications and source records attributed to H T Delves.

At least 19 recordsLinked to original sources
PubMed1991

The demonstration of nickel in the urease of Helicobacter pylori by atomic absorption spectroscopy.

Fast protein liquid chromatography and SDS-PAGE have been used to isolate and purify Helicobacter pylori urease. A nickel component of the urease was detected in the purified proteins by atomic absorption spectroscopy. The nickel was present only in the 61 kDa polypeptide and in the ratio of between five and six atoms to one molecule of urease, suggesting a hexameric structure. These results are discussed in relation to other bacterial ureases and urease activity at low pH.

Chromatography, Liquid↗
PubMed1990

Lead intake and blood lead in two-year-old U.K. urban children.

A comprehensive study of a group of 2-year-old urban children (n = 97), designed to provide quantitative information simultaneously for lead intakes via all identified pathways, has been carried out in Birmingham (U.K.). Results showed that for children whose blood levels and exposure to environmental lead were within the normal range for the U.K., blood lead concentration was significantly related to a combination of house dust lead loading and an overall rate of touching objects, to water lead concentration and to the parents' smoking habits. On the basis of assumptions used by the Royal Commission on Environmental Pollution (RCEP), the estimated average total uptake of lead was 36 micrograms day-1; of this, 97% was from ingestion from dust, food and water and only 3% from inhalation.

Air Pollutants↗
PubMed1990

Bismuth induced encephalopathy caused by tri potassium dicitrato bismuthate in a patient with chronic renal failure.

A 68 year old man with a creatinine clearance rate of only 15 ml/min took twice the recommended dose of tripotassium dicitrato bismuthate (TDB) as DeNol liquid; 10 ml qds; a total of 864 mg bismuth daily for two months. Whole blood bismuth concentrations rose to 880 micrograms/l and he developed global cerebral dysfunction with hallucinations, ataxia, and an abnormal EEG. Renal clearance of bismuth rose from 0.24 to 2.4 ml/min when the heavy metal chelator 2-3 dimercapto-1 propane sulphonic acid (DMPS) was given by mouth. Bismuth was measured by a novel method involving inductively coupled plasma source mass spectrometry. Fifty days after stopping TDB, whole blood bismuth concentrations fell to 46 micrograms/l and the patient's EEG returned to normal. His mental function also recovered completely. The case serves as a timely reminder that TDB should not be administered to patients with renal disorders, as stated in the data sheet.

Aged↗
PubMed1989

Low blood manganese levels in Liverpool children with Perthes' disease.

The aetiology of Perthes' disease of the hip, avascular necrosis of the head of the femur, is unknown. Children with the disease have a generalised abnormality of growth. A similar disproportionate growth is found in chicks given a diet deficient in manganese. In Liverpool, which has the highest incidence of Perthes' disease reported anywhere in the world, children with the disease were shown to have lower blood manganese levels than controls. This is evidence that manganese deficiency around the time of birth may be a cause of Perthes' disease, but the results require confirmation.

Age Factors↗
PubMed1989

The UK Blood Lead Monitoring Programme 1984-1987: results for 1986.

The Department of the Environment (DOE) undertook an extensive programme to monitor blood lead concentrations annually over the period 1984 to 1987 in the context of the reduction in the maximum permissible lead content of petrol from 0.4 to 0.15 g/l from 1st January 1986. Blood samples (all venous) were analysed for lead by atomic absorption spectrophotometry (AAS); considerable efforts were made to ensure the validity of the analytical results. In 1986, emissions from petrol driven vehicles effectively fell by 60% and air lead concentrations fell by just over 50%. Against the background of a long-term downward trend in blood lead concentrations of 4-5% per year, there were average falls in blood lead in 1986, compared with 1985, of around 1 microgram/100 ml (9-10%) for adults in both 'exposed' and 'control' groups; about 2 micrograms/100 ml (18%) in traffic police; and about 1.5 micrograms/100 ml (16%) in children. Levels fell in 1986 in all age groups, in all social classes, and in all categories of smoking and drinking habits, age of dwelling and length of residence. Exposure to lead from a number of sources was being reduced simultaneously; blood lead concentrations probably fell in both 1985 and in 1986 for reasons additional to the reduction in the lead content of petrol. For children, petrol lead appeared to have been made a slightly larger contribution to the body burden than for adults.

Adult↗
PubMed1988

Blood cadmium concentrations in the general population of British middle-aged men.

Blood cadmium concentrations were determined for 6919 men aged 40-59 randomly selected from general practice registers in 24 British towns. The mean and median blood cadmium were 1.9 and 1.4 micrograms/1 respectively and the distribution was highly skewed. The mean levels in non-smokers was 1.0 micrograms/l and current smokers showed a marked gradient with the daily amount smoked, with a mean of 3.9 micrograms/l in men smoking 40 or more cigarettes per day. Whereas 95% of men who never smoked had blood cadmium less than 2.0 micrograms/l, 80% of men smoking 20 or more cigarettes a day exceeded this figure. 1% of the men had blood cadmium concentrations greater than or equal to 7 micrograms/l virtually all of whom currently smoked cigarettes. Blood cadmium levels in ex-smokers were much lower than in current smokers even for those who had stopped within the past year. However, the mean levels in ex-smokers remained higher than the 'never smoked' for several years after stopping. There was little evidence that age, social class, or alcohol consumption were associated with blood cadmium levels after allowance for cigarette smoking. There is substantial geographic variation in mean blood cadmium for middle-aged men which could not be completely accounted for by smoking differences. Towns in the south and east of England all had mean levels under 2.0 micrograms/l whereas the majority of towns in other parts of Britain had mean levels greater than 2.0 micrograms/l. Possible reasons for this geographic pattern (e.g. geochemistry, industrial exposure, dietary differences) need further exploration.

Adult↗
PubMed1988

UK blood lead monitoring programme 1984-1987: results for 1985.

The Department of the Environment (DOE) has undertaken an extensive programme to monitor blood lead concentrations annually over the period 1984 to 1987 in the context of the reduction in the maximum permissible lead content of petrol from 0.4 to 0.15 g/l from 1 January 1986. The 2500 participants in the study include adults living in heavily trafficked urban areas and in occupational groups particularly exposed to petrol lead; children aged 6-7 years attending schools in heavily trafficked urban areas; and control groups of adults and children in rural areas. Blood samples (all venous) are being analysed for lead by atomic absorption spectrophotometry (AAS); considerable efforts are being made to ensure the validity of the analytical results during the period of the study. Average blood lead concentrations in 1984 and 1985 in both adults and children were generally low and were in line with levels expected on the basis of earlier surveys; only a very small proportion of individuals had raised levels. Detailed statistical analyses have confirmed that blood lead concentrations are related to a range of personal, social and environmental factors including age, sex and smoking and drinking habits. Blood lead levels in the exposed groups of adults and children were on average just under 1 microgram/100 ml lower in 1985 than in 1984, while overall changes in the police and control groups were smaller; there was, however, considerable variability in the changes in the individual surveys, particularly those of children. Levels fell in all social classes and in both categories of age of dwelling, but changes tended to be less marked in those who were older (particularly for men), smoked more, drank more or had lived for more than 15 years at their current address.

Adult↗
PubMed1988

The relationship between blood lead, blood pressure, stroke, and heart attacks in middle-aged British men.

The relationship between blood lead concentration and blood pressure is examined in a survey of 7371 men aged 40 to 59 from 24 British towns. After allowance for relevant confounding variables, including town of residence and alcohol consumption, there exists a very weak but statistically significant positive association between blood lead and both systolic and diastolic blood pressure. These cross-sectional data indicate that an estimated mean increase of 1.45 mm Hg in systolic blood pressure occurs for every doubling of blood lead concentration with a 95% confidence interval of 0.47 to 2.43 mm Hg. After 6 years of follow-up, 316 of these men had major ischemic heart disease, and 66 had a stroke. After allowance for the confounding effects of cigarette smoking and town of residence there is no evidence that blood lead is a risk factor for these cardiovascular events. However, as the blood lead-blood pressure association is so weak, it is unlikely that any consequent association between lead and cardiovascular disease could be demonstrated from prospective epidemiological studies. An overview of data from this and other large epidemiological surveys provides reasonably consistent evidence on lead and blood pressure. While NHANES II data on 2254 U.S. men indicate a slightly stronger association between blood lead and systolic blood pressure, data from two Welsh studies on over 2000 men did not show a statistically significant association. However, the overlapping confidence limits for all these studies suggest that there may be a weak positive statistical association whereby systolic blood pressure is increased by about 1 mm Hg for every doubling of blood lead concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Nickel dermatitis and diet: clinical improvement and a reduction in blood and urine nickel levels with a low-nickel diet.

A 27-year-old nickel-sensitive female who had had continuous spontaneous flare-ups of eczema, including at sites of previous metal contact, experienced a clearing of her eruption after commencing a low-nickel diet. When on the diet, whole-blood and urinary nickel levels fell to half or less of pre-diet values and this coincided with the clinical improvement. Low-nickel diets should be considered for patients who are highly nickel sensitive.

Adult↗
PubMed1988

Skin selenium content measured by hydride generation and atomic absorption spectroscopy.

The concentration of selenium in skin was measured using hydride generation and atomic absorption spectroscopy. The method used in this study was shown to be both accurate and precise, with mean recoveries of 92%-98% of added selenium and a within run relative standard deviation of better than 7% at a selenium concentration of less than 12 nmol/g dry tissue. The method is suitable for rapid analysis of large numbers of samples.

Biopsy↗
PubMed1987

UK Blood Lead Monitoring Programme 1984-1987: protocol and results for 1984.

The Department of the Environment (DOE) has undertaken an extensive programme to monitor blood lead concentrations annually over the period 1984 to 1987 in the context of the reduction in the maximum permissible lead content of petrol from 0.4 to 0.15 g/l from 1st January 1986. The study includes adults living in heavily trafficked urban areas and in occupational groups particularly exposed to petrol lead; children aged 6-7 years attending schools in heavily trafficked urban areas; and control groups of adults and children in rural areas. The surveys are planned to cover about 1500 adults and 1000 children in total each year. Cohorts of adults are being followed, with replacement where necessary owing to moving, etc. For ethical reasons, no child will be sampled more than once, although the schools concerned will be revisited each year; children's blood is also being examined for antibodies to measles and poliomyelitis. Blood samples are being analysed for lead by atomic absorption spectrophotometry (AAS); considerable efforts are being made to ensure the validity of the analytical results during the period of the study. Results for 1984 indicated that average blood lead concentrations in both adults and children were generally low and were in line with levels expected on the basis of earlier surveys; only a very small proportion of individuals had raised levels. A detailed statistical analysis has confirmed the results of the EEC Blood Lead Surveys (carried out in 1979-1981) that blood lead concentrations were related to a range of personal, social and environmental factors including age, sex and smoking and drinking habits. Comparisons of any trends during the survey period in blood level concentrations in the exposed and control groups, together with results from the monitoring of sources of environmental lead should enable a broad assessment to be made of the effect of the reduction in petrol lead.

Adolescent↗
PubMed1985

Assessment of trace element status.

Biochemical and clinical investigations involving trace elements are made for the diagnosis of inherited or acquired deficiencies of essential trace elements and their treatment, to monitor the efficacy of the therapeutic administration of non-essential trace elements in order to achieve maximum clinical response with minimum toxicity, and for the early detection of excessive ingestion of non-essential toxic trace elements. The wide range of tests used to assess trace element status in these three areas of clinical importance is discussed with examples of essential and of toxic trace elements since therapeutic use of trace elements is discussed elsewhere in this issue. Particular attention is given to zinc, copper, selenium, lead and cadmium because the various tests used to assess the status of these elements encompass the principles of all currently available tests. Although trace element analysis of body fluids and tissues is the most useful and most commonly used method of assessment of trace element status, this is of limited value and no single test may be considered as ideal for any element. The provision of more detailed information from elemental analysis of cellular and subcellular fractions and of protein fractions from plasma leads inexorably to measurements of element-dependent enzymes, metalloproteins and of low molecular weight element-binding ligands. Even at this level of discrimination the choice of body tissue or tissue fluid for investigation is determined by the trace element and its principal metabolic targets.

Cadmium↗