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Biomedical subjects

J C Hughes

Publications and source records attributed to J C Hughes.

At least 19 recordsLinked to original sources
PubMed2006

The effects of water treatment residues on soil respiration and microbial community structure.

Land disposal of water treatment residue (WTR), a by-product of potable water production, is increasingly being considered a viable alternative to land filling. It is crucial, inter alia, that soil quality is not affected adversely. Six different WTRs obtained from South African water treatment facilities were added to Hutton and Westleigh topsoils at rates of 0, 5, 15 and 25% (m/m) to determine their impacts on soil basal respiration. In general, respiration increased with rate of addition of WTR. The Umgeni, Rand, Midvaal and Faure2 WTRs had the greatest effect on respiration. Increases in respiration became less marked with time. The Hutton topsoil was mixed with the WTRs (at 15% m/m) and, following incubation, the bacterial community structure was examined by denaturing gradient gel electrophoresis. Changes in community structure were detected after 5 d and were attributed to physico-chemical changes arising from WTR amendment. However, dominant bands associated with the Hutton soil were retained and microbial diversity was not adversely affected. The findings of this investigation suggest that WTRs can be applied to the Hutton soil at a rate of at least 15% (300 Mg ha(-1)) without having a detrimental effect on microbial indicators of soil quality.

Hydrogen-Ion Concentration↗
PubMed2006

The effects of a polyacrylamide-derived water treatment residue on the hydraulic conductivity, water retention and evaporation of four contrasting South African soils and implications for land disposal.

Water treatment residue (WTR), a by-product from the production of potable water, was traditionally disposed of to landfill but there is growing interest in applying this waste to land as an alternative disposal option. Because WTR consists mainly of flocculated fine silt and clay, there is concern that should the residue decompose back to its original constituents, there is an adverse risk for soil water storage and transmission properties of soil. In a laboratory study, four different soil types were amended with a polyacrylamide WTR at rates ranging from 0 to 1280 Mg ha(-1). The treatments were evaluated for changes in water retention, hydraulic conductivity and evaporation. The results showed that WTR decreased bulk density and evaporation and actually increased hydraulic conductivity and water retention, mainly because of the sustained performance of the polymer in binding the silt and clay into gravel-sized aggregates. Such changes were, however, only significant at the 1280 Mg ha(-1) application rate. Therefore, very large amounts of WTR would have to be applied in order to markedly change these inherent physical properties of the soils. In view of this finding, the land treatment of WTR appears possible.

Acrylic Resins↗
PubMed2004

Hookworm (Necator americanus) transmission in inland areas of sandy soils in KwaZulu-Natal, South Africa.

This study extended the association between hookworm transmission in KwaZulu-Natal and the sandy coastal plain by investigating the parasite's occurrence in isolated areas of sandy soils further inland. A school-based prevalence survey was carried out in selected inland sandy areas and in surrounding areas dominated by clay soils within a narrow altitudinal range of between 500 and 700 m to reduce the effect of altitude on climate-related factors (rainfall and temperature). Sandy areas situated on the coastal plain were included in the analysis for comparative purposes. Soil samples (0-50 mm depth) were collected from each locality to assess their nematode loadings and to analyse selected physical and chemical properties. Significant differences were found between the moderate prevalence of hookworm infection among children living in inland areas with sandy soils (17.3%) and the low prevalence in surrounding non-sandy areas (5.3%, P < 0.001), and between infection among children living in all inland areas (9.3%) and the high prevalence on the coastal plain (62.5%, P < 0.001). Amounts of fine and medium sand were highest in both the coastal plain soils and in inland sandy areas and these fractions showed a significant positive correlation with hookworm prevalence and nematode loadings. Clay, coarse sand and organic matter contents were highest in surrounding non-sandy soils and showed a significant negative correlation with the nematode variables. No statistically significant correlations were found with soil pH at study localities. We conclude that properties of inland sandy soils, particularly particle size distribution, correlate well with hookworm prevalence and nematode loadings and therefore provide a more suitable habitat for nematodes than surrounding non-sandy areas. These results suggest that particle size distribution of sand fractions, organic matter and clay content in the soil influence the survival of hookworm larvae and hence the parasite's transmission.

Adolescent↗
PubMed2003

The effect of soil type and climate on hookworm (Necator americanus) distribution in KwaZulu-Natal, South Africa.

We investigated environmental factors influencing the distribution of hookworm infection in KwaZulu-Natal, South Africa. Prevalence data were sourced from previous studies and additional surveys carried out to supplement the database. When geo-referenced the data revealed that higher prevalences are limited to areas below 150 m above sea level, and low prevalences to areas above this altitude. Using univariate analysis we investigated the differences in environmental factors in the two areas. The relationship between hookworm prevalence, altitude and climate-derived variables was assessed using Pearson correlation coefficient, and that of soil type using the t-test. Multivariate analysis was used to determine environmental factors that combine best to provide favourable conditions for hookworm distribution. The results revealed that areas 150 m above sea level, i.e. inland, supported low mean hookworm prevalences (x = 6, n = 21), and were characterized by soils with a clay content of more than 45%, variable temperatures and moderate rainfall. Hookworm prevalence also decreased southwards as temperatures became slightly cooler, rainfall remained more-or-less constant and the coastal plain narrowed. In the multivariate model prevalence was most significantly correlated with the mean daily minimum temperature for January followed by the mean number of rainy days for January. This indicates the importance of summer conditions in the transmission of hookworm infection in KwaZulu-Natal and suggests that transmission may be seasonal.

Adolescent↗
PubMed2001

Views of the person with dementia.

In this paper I consider, in connection with dementia, two views of the person. One view of the person is derived from Locke and Parfit. This tends to regard the person solely in terms of psychological states and his/her connections. The second view of the person is derived from a variety of thinkers. I have called it the situated-embodied-agent view of the person. This view, I suggest, more readily squares with the reality of clinical experience. It regards the person as embedded in a history and culture. The human person is also an embodied agent. I contend that this view encourages a more appropriate approach towards the ethical issues that arise in dementia and towards people with dementia.

Advance Directives↗
PubMed1998

A new gas jet method for the assessment of sensory block after spinal anaesthesia.

We evaluated a new method of assessing sensory block after spinal anaesthesia using a fine gas jet and compared it with other established methods. The gas jet method was used to test the block before and after surgery and was found to compare favourably with pin-prick (median difference 0 and 0 dermatomes) and ethyl chloride (median difference 0.5 and 1.0 dermatomes) but less well with cotton wool (median difference -2.0 and -2.0 dermatomes).

Anesthesia, Obstetrical↗
PubMed1997

Dysgraphia in mild dementia of Alzheimer's type.

We assessed writing abilities in a cohort of 31 patients with a diagnosis of DAT (in two subgroups, with minimal [MMSE 24-28] and mild [MMSE 16-23] levels of dementia), and 10 matched controls. Central aspects of writing were assessed by both written and oral spelling to dictation of 72 single words varying in frequency (high or low) and predictability of sound-to-spelling correspondences (predictable, unpredictable and irregular). All subjects achieved better scores on high, as compared to low, frequency words. The performance of both patient groups was significantly affected by degree of predictability, and was equivalent in the written and oral spelling conditions. Phonologically acceptable alternative spellings (e.g. 'wade'-->WAID) constituted the majority of errors. More peripheral processes in writing were assessed by copying and cross-case transcription of single letters. Subjects were more successful at copying within case than transcribing across case. Performance was also better--substantially so for the mild DAT group--when the target response in either task was an upper- rather than a lower-case letter. There was considerable heterogeneity in performance on the spelling and the letter tasks. Some patients (even in the more affected DAT group) were unimpaired on both tasks, suggesting that dysgraphia is not a constant feature in early DAT. When writing deficits do become apparent, in the earliest stages of the disease the pattern is most likely to be one of mild surface dysgraphia, a form of central dysgraphia; impairments in more peripheral aspects of writing tend to emerge once the disease has progressed beyond the minimal stage.

Aged↗
PubMed1997

The efficacy of disulfiram: a review of outcome studies.

Twenty-four studies of outcome following oral disulfiram and 14 following implanted disulfiram were identified for review from MEDLINE and PsycINFO databases and by manual searching for the period 1967-95. The methodological rigour of these studies was generally poor, albeit not as poor as that of earlier studies (not reviewed here). An overall assessment of the results of research in this field is hampered by the diversity of both the methods used and the subject populations studied. However, it is clear that support for the general use of oral disulfiram is equivocal, mostly being found in the form of reduced quantity of alcohol consumed and a reduced number of drinking days. Evidence for an effect in increasing the proportion of patients who achieve abstinence is surprisingly lacking. Where it is prescribed, disulfiram use should be supervised and it should be employed as one part of a comprehensive treatment programme. There is no good evidence in favour of implanting disulfiram tablets, but the possibility of a depot injection is intriguing.

Administration, Oral↗
PubMed1993

Intracranial haemorrhage associated with ingestion of 'ecstasy'.

A case of a patient with intracranial haemorrhage thought to have been associated with ingestion of 'Ecstasy' [3-4 methylenedioxymethamphetamine (MDMA)] is presented. The case illustrates the importance of drug analysis in cases involving illicit drug use.

3,4-Methylenedioxyamphetamine↗