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Biomedical subjects

M Hutton

Publications and source records attributed to M Hutton.

123 records · Page 7Linked to original sources
PubMed1987

The cadmium and lead content of suspended particulate matter emitted from a U.K. refuse incinerator.

Suspended particulate matter (SPM), sampled from the stack of a large refuse incinerator in the U.K., contained markedly elevated levels of Cd (approximately 1600 micrograms g-1) and Pb (approximately 3%). These values were similar to those previously reported for several other incinerators in Europe, but the Pb concentrations were lower than in the SPM from three American incinerators. Calculation of the metal concentration ratio SPM/fly ash for the U.K. incinerator revealed a three-fold enrichment of the two metals on the SPM. Similar ratios were obtained for several other European incinerators; this correspondence in metal partitioning was linked to the use of electrostatic precipitators in these facilities. The SPM metal data obtained in this study were used to estimate atmospheric emissions of 0.5 t Cd year-1 and 11 t Pb year-1 from the incinerator. Extrapolation of the Cd and Pb emission factors derived from this study to the quantity of refuse incinerated in the U.K. results in atmospheric discharges of 6 t Cd year-1 and 115 t Pb year-1. These estimates are in good agreement with those previously reported by an emissions inventory which identified incineration as the single largest source of airborne Cd in the U.K.

Air Pollutants↗
PubMed1986

The quantities of cadmium, lead, mercury and arsenic entering the U.K. environment from human activities.

This paper presents an estimate of the quantities of cadmium, lead, mercury and arsenic entering the U.K. environment from human activities. Discharges are divided into three source categories: the production and use of the elements, inadvertent sources and various waste disposal practices. The major atmospheric sources of cadmium and mercury include refuse incineration, nonferrous metal production, iron and steel production, fossil fuel combustion and, for mercury alone, the chlor-alkali industry. In contrast, lead and arsenic each have only one major atmospheric source: petrol and coal combustion, respectively. The largest inputs of cadmium, lead and mercury to landfill arise from the disposal of municipal wastes; for arsenic, ash disposal from coal combustion is more important. Industrial activities represent the major sources of trace element input to the U.K. sewage system but domestic sources are important for lead and cadmium, while road run-off makes a considerable lead input. In U.K. coastal waters the major sources of cadmium are the direct discharge of sewage and industrial effluents. For the other elements, the dumping of solid wastes is of more significance. The largest inputs of lead, mercury and arsenic to U.K. agricultural land arise from atmospheric deposition; for cadmium the application of phosphate fertilizers is a more important source, while sewage sludge can be of local significance.

Air Pollutants, Occupational↗
PubMed1983

A prospective atmospheric emission inventory for cadmium--the European community as a study area.

The quantities of cadmium emitted to the atmosphere from natural and human sources have been estimated for the member states of the European Community, allowing the construction of an atmospheric emission inventory for cadmium at the regional level. A survey of the available emission data was used to calculate an emission factor (g cadmium emitted tonne -1 material consumed or produced) for each source. This value was applied to the most recent consumption or production data for the region to obtain an annual discharge estimate. Predictions of future trends in cadmium emissions from human sources over the next two decades were based on economic forecasts for the process in question. The iron and steel industries and refuse incineration are the two largest sources of airborne cadmium in the region, followed by volcanic action and zinc production. It is forecast that there will be an increase in cadmium emissions over the next two decades due mainly to the iron and steel industries and zinc production. A comparison of the emission estimates obtained in this study with those given in previously published inventories reveal disparities in the source strengths for some processes. In particular, it would appear that cadmium emissions from coal combustion and non-ferrous metal production have been overestimated in some past studies.

Air Pollutants↗
PubMed1983

Sources of cadmium in the environment.

This paper is concerned with quantifying the major sources of cadmium in the European Community and assessing the relative significance of such inputs to the environmental compartments, air, land, and water. The methodology involved identification of potential sources of cadmium, including natural processes, as well as those associated with human activities. This was followed by a review of any emission studies of these processes and subsequent estimation of an emission factor for each source. The emission factor was applied to the most recent production or consumption data for the process in question to obtain an estimate of the annual discharge. The steel industry and waste incineration, followed by volcanic action and zinc production, are estimated to account for the largest emissions of atmospheric cadmium in the region. Waste disposal results in the single largest input of cadmium to land; the quantity of cadmium associated with this source is greater than the total from the four other major sources--coal combustion, iron and steel production, phosphate fertilizer manufacture and use, and zinc production. The characterization of cadmium inputs to aquatic systems is incomplete but of the sources considered, the manufacture of cadmium-containing articles accounts for the largest discharge, followed by phosphate fertilizer manufacture and zinc production.

Cadmium↗
PubMed1983

The effects of environmental lead exposure and in vitro zinc on tissue delta-aminolevulinic acid dehydratase in urban pigeons.

1. Elevated lead burdens in three urban pigeon populations caused ALAD inhibition, in blood, kidney and liver, the degree of inhibition generally corresponding to the lead content of each tissue. The values obtained are compared with those given by studies of lead exposure in mammals. 2. The usefulness of blood ALAD as an index of lead exposure is discussed. 3. The pH activity profile of ALAD in blood and kidney of urban pigeons was also changed. 4. In vitro zinc additions partially restored lead-inhibited ALAD. 5. These findings are discussed in terms of the possible manner in which lead inhibits ALAD.

Animals↗
PubMed1982

The role of wildlife species in the assessment of biological impact from chronic exposure to persistent chemicals.

Assessments of chemical toxicity have regularly placed reliance upon experimental studies which employ environmentally unrealistic exposure regimes. This approach ignores the long-term low-level nature of environmental exposure which facilitates the development of factors which modify the toxicity of such chemicals. Examples of such adaptive mechanisms will be taken from the author's own studies. Factors discussed include the development of protective trace element interactions in target organs, the induction of specific metal-binding proteins, and the alteration of the distribution of chemicals at the organ and organelle level. Exposure-response investigations in wildlife are not restricted to the organism level and the impact of an environmentally released chemical upon breeding success and population dynamics can also be investigated. Disadvantages and problems associated with this kind of study, such as multiple pollutant exposure and variability in response, will also be considered.

Animal Population Groups↗
PubMed1980

Effect of metoclopramide on interdigestive myoelectric activity in the conscious dog.

The effect of two-hour infusions of metoclopramide at five different doses on interdigestive intestinal electrical activity was studied in four conscious fasting dogs. Spike activity during the infusions was quantitatively compared with activity during preceding and following periods of saline infusion. The effect of the drug was the enhancement of spike activity during migrating myoelectric complexes (MMC) without disruption of the fasting pattern; the effect was most marked in the proximal small intestinal and diminished distally. As in other published studies with metoclopramide, its effects were variable and not dose dependent. The enhancement of the MMC by an exogenous stimulus, not previously reported, provides indirect evidence for cholinergic mediation of cyclical motor activity, and also suggests a rational basis for therapy.

Animals↗
PubMed1979

Quantitative effect of oral feeding on gastrointestinal myoelectric activity in the conscious dog.

Gastrointestinal myoelectric activity was recorded in seven studies in five dogs during two hours of fasting immediately followed by feeding and subsequent recording for four hours. In four studies serial plasma samples were taken for radioimmunoassay of insulin and gastrin. In all animals there was a significant reduction (P less than 0.01) in gastric basic electrical rhythm (BER) frequency on feeding which was sustained throughout the postprandial period. There was no change in the duodenal BER. Feeding induced a significant (P less than 0.01) increase in overall jejunal and ileal (but not duodenal) spike activity. Ileal (but not jejunal) spike activity again increased significantly (P less than 0.05) after the first two post-prandial hours. The changes in serum gastrin or in serum insulin did not appear to account for most of the observed changes in myoelectric activity, suggesting that other humoral and/or neural factors mediate the response to food.

Animals↗
PubMed1978

Factors influencing lactation performance in rural Gambian mothers.

Breast-milk consumption has been measured in a rural African community in which breast-feeding on demand is universally practised until the baby is 18 mos old. The mother's long-term capacity for breast-milk production is determined by the end of the second month of lactation, yield being closely correlated with the infant's birth-weight. Other factors significantly influencing output were parity, month of lactation, baby's weight-for-age, season, and maternal diet. Daily milk consumption was limited primarily by the amount delivered per feed, not the frequency of feeding.

Body Weight↗
PubMed1978

Quantitative comparison of the effects of cholecystokinin, secretin, and pentagastrin on gastrointestinal myoelectric activity in the conscious fasted dog.

The effects on gastrointestinal myoelectric activity of infused pentagastrin, cholecystokinin (CCK), and secretin at physiological doses were studied in live dogs with implanted serosal electrodes during 56 six-hour studies. Pentagastrin dose-dependently increased gastric and duodenal slow-wave frequencies; secretin and CCK did not. Pentagastrin and CCK diminished the incidence of fasting migrating myoelectric complexes (MMCs), but MMCs were abolished only in the proximal small intestine. Pentagastrin infusion was not reflected in an increased number of spikes, whereas CCK induced a dose-dependent increase in jejunal spike activity. Secretin dose-dependently decreased duodenal and jejunal spike incidence without a marked effect on MMC incidence. Analysis of patterns of spike activity showed significant dose-dependent changes with all three peptides. The different effects of pentagastrin and CCK on spike activity in these studies may have been a consequence of pentagastrin-stimulated gastric acid secretion. None of the three peptides produced a pattern of myoelectric activity which closely resembled that seen on feeding; since, unlike food, all three peptides had little or no effect on the distal small intestine, it seems unlikely that combinations of these peptides are responsible for the change induced by food. The failure of these peptides to abolish fasting patterns in the distal intestine suggests a possible mechanism for some types of post-vagotomy dysfunction.

Action Potentials↗
PubMedDate not supplied

Phenotypic correlations in FTDP-17.

Frontotemporal dementias with parkinsonism linked to chromosome 17 (FTDP-17) are hereditary tauopathies affecting at least 50 known kindred worldwide. Most kindred present with severe behavioral or psychiatric manifestations progressing to dementia, while some kindred first manifest a parkinsonian-plus syndrome. Nine missense mutations, one deletion mutation, and two transition mutations not altering the encoded amino acid, have been described in or near the microtubule-binding domains within exons 9, 10, 12, and 13. In addition, five different intronic mutations have been reported in the 5' splice-site of the alternatively spliced exon 10. Missense mutations affecting constitutively expressed exons affect all six major tau isoforms and result in neurofibrillary tangles similar to those present in secondary tauopathies, such as Alzheimer's disease. In contrast, mutations that affect the alternatively spliced exon 10 or its 5' splice regulatory region alter the ratio of the tau isoforms incorporated into the tangles and result in filamentous inclusions resembling those seen in the primary tauopathies, such as progressive supranuclear palsy, corticobasal degeneration, and Pick's disease. The severity and heterogeneity of the clinicomorphologic phenotype may, in part, reflect the diversity in the primary molecular mechanisms of disease in FTDP-17.

Brain↗