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Biomedical subjects

D M Hall

Publications and source records attributed to D M Hall.

At least 37 records · Page 2Linked to original sources
PubMed1999

Splanchnic tissues undergo hypoxic stress during whole body hyperthermia.

Exposure of conscious animals to environmental heat stress increases portal venous radical content. The nature of the observed heat stress-inducible radical molecules suggests that hyperthermia produces cellular hypoxic stress in liver and intestine. To investigate this hypothesis, conscious rats bearing in-dwelling portal venous and femoral artery catheters were exposed to normothermic or hyperthermic conditions. Blood gas levels were monitored during heat stress and for 24 h following heat exposure. Hyperthermia significantly increased arterial O2 saturation, splanchnic arterial-venous O2 difference, and venous PCO2, while decreasing venous O2 saturation and venous pH. One hour after heat exposure, liver glycogen levels were decreased approximately 20%. Two hours after heat exposure, the splanchnic arterial-venous O2 difference remained elevated in heat-stressed animals despite normal Tc. A second group of rats was exposed to similar conditions while receiving intra-arterial injections of the hypoxic cell marker [3H]misonidazole. Liver and intestine were biopsied, and [3H]misonidazole content was quantified. Heat stress increased tissue [3H]misonidazole retention 80% in the liver and 29% in the small intestine. Cellular [3H]misonidazole levels were significantly elevated in intestinal epithelial cells and liver zone 2 and 3 hepatocytes and Kupffer cells. This effect was most prominent in the proximal small intestine and small liver lobi. These data provide evidence that hyperthermia produces cellular hypoxia and metabolic stress in splanchnic tissues and suggest that cellular metabolic stress may contribute to radical generation during heat stress.

Animals↗
PubMed1999

Once- versus twice-daily gentamicin dosing in neonates >/=34 Weeks' gestation: cost-effectiveness analyses.

OBJECTIVES: To compare performance and cost analysis of two gentamicin regimens in infants >/=34 weeks' gestation requiring antibiotics for a 72-hour rule-out sepsis evaluation. A once-daily dosing (ODD) regimen of 4 mg/kg was compared with a standard twice-daily dosing (TDD) regimen of 2.5 mg/kg every 12 hours. SETTING AND DESIGN: Infants at two university-affiliated Level III nurseries were prospectively temporally allocated to receive ODD (n = 27) or TDD (n = 28) as part of their 72-hour empirical antibiotic regimen. Performance of dosing regimens was based on target serum gentamicin concentrations (SGC) established prospectively as a peak of 5 to 10 microgram/mL and a trough of </=2 microgram/mL. SGC were determined by fluorescence polarization immunoassay on day 3 of therapy. Cost data were obtained by distributing a questionnaire to 15 pediatric pharmacy practice sites. Inquiries were made regarding hospital cost of drug acquisition, drug supplies, drug preparation and administration, and serum concentration analysis. Performance and cost data were then used to do a cost-effectiveness analysis. RESULTS: Mean peak concentrations were higher with ODD (7.9 +/- 0.2 microgram/mL) than TDD (6.7 +/- 0.3 microgram/mL). Half of the patients in the TDD group had trough concentrations >2 microgram/mL, compared with none in the ODD group. Overall, 57% of the SGCs in the TDD group were outside the target concentration range versus 7% in the ODD group. Based on questionnaire results, a total 72-hour process cost of ODD versus TDD was compared for regimens with and without use of SGC analysis. If SGCs are obtained, more than 75% of the cost associated with gentamicin therapy is attributable to SGC analysis. Based on a cost-effectiveness analysis, ODD was the dominant dosing strategy in all categories analyzed. CONCLUSIONS: ODD of gentamicin at 4 mg/kg in neonates >/=34 weeks' gestation is the preferable treatment strategy based on: 1) significantly improved SGC performance compared with TDD; 2) elimination of the need for routine SGC collection in infants on short courses of therapy; and 3) significant antibiotic-associated hospital cost savings when compared with conventional therapy of TDD and SGC analysis.

Cost-Benefit Analysis↗
PubMed1998

Opioid mediated effects on the immune system: sympathetic nervous system involvement.

Opioids have been hypothesized to suppress parameters of immune function by acting within the central nervous system to increase the activity of the hypothalamic-pituitary-adrenal axis and the sympathetic nervous system. Production of catecholamines and adrenocorticoids have been demonstrated to be responsible for many of the observed immunomodulatory effects which occur following opioid administration. In general, the sympathetic nervous system has been shown to play a role in regulating lymphocyte proliferation and natural killer cell activity as well as several other parameters of immune function. Here, we will focus primarily on the role of the sympathetic nervous system in modulating opioid induced immunosuppression. The role of the hypothalamic-pituitary adrenal axis is reviewed elsewhere in this issue.

Animals↗
PubMed1998

Screening in child health.

Screening programmes in child health have evolved on the basis of individual enthusiasm and professional consensus, rather than being based on objective evidence of benefit. Three reviews have been carried out in the UK over the past 10 years. The only programmes which show robust evidence of effectiveness are those for PKU and hypothyroidism. The value of screening for hearing loss and vision defects is widely accepted, but there are many unresolved issues. Programmes for detection of congenital dislocation of the hip, congenital heart disease and growth disturbances are of doubtful value. Early identification of developmental problems is stressed by parents, but screening may not be the best way to achieve this. The UK programme of well-child care places increasing emphasis on promotion of physical and emotional health; screening tests should either be subjected to quality monitoring, or removed from the programme if they cannot fulfil the classic criteria of Wilson and Jungner.

Child↗
PubMed1998

Errors in postcode to enumeration district mapping and their effect on small area analyses of health data.

BACKGROUND: Health research often seeks to associate individuals to their socio-economic circumstances by linking an individual's postcode to their Census enumeration district (ED). As part of a study into health visitor resource allocation the objective here is to quantify the errors that arise in attaching ED level deprivation scores to records and counts of records by ED when records are matched to EDs via their postcodes rather than their exact address. METHODS: The result of routine matching of postcodes to EDs was compared with the more accurate method of matching addresses to EDs. Townsend scores were then attributed to records according to the two different methods and the results compared. A sample of 4013 births registered in Sheffield in 1996 was used. RESULTS: The comparative work showed that the mismatching of individual addresses arising from matching postcodes to EDs was 16.4 per cent. (The 95 per cent confidence interval is 15.1-17.7 per cent.) Over one-third of mismatched records (about 6 per cent of the total records) were found to have Townsend scores greater than +/- 2 compared with the score obtained through the more accurate process of address matching. CONCLUSIONS: The evidence of the study is that it is important to recognize there are errors inherent in matching individual addresses to EDs via the address postcode. For problems involving resource allocation and for research into relationships between health outcomes or service uptake and deprivation it may be necessary to seek to quantify the level of error introduced through using postcode to ED matching.

Bias↗
PubMed1998

The costs of early hearing screening in England and Wales.

A survey was carried out in 10 centres in England and Wales to determine the costs of hearing screening in the first year of life. The screens that were studied were targeted neonatal, universal neonatal, and the health visitor distraction test (HVDT) or alternative surveillance. Valid data were available from five centres for targeted neonatal screening (TNS), three for universal neonatal screening (UNS), and nine for the HVDT, although only five of the HVDT screens had valid data for follow up costs. The neonatal costs were consistent across the centres surveyed, whereas those for the HVDT screen varied considerably. The mean service costs for TNS, UNS, and the HVDT at 1994 prices were 5052 Pounds, 13,881 Pounds, and 24,519 Pounds for a standardised district of 1000 live births. Three conclusions seem justified. Firstly, UNS need not be prohibitively expensive as it costs considerably less than HVDT screening. Secondly, TNS appears to be a relatively inexpensive way of improving the age of identification of a proportion of the congenitally hearing impaired. Thirdly, given the published yields for UNS and the HVDT, the results indicate that UNS offers the most cost effective overall approach with alternative systems in place to identify late onset permanent hearing losses.

England↗
PubMed1998

Transition from school to adult life for physically disabled young people.

The transition process for young physically disabled people (n = 87) was studied in three districts to determine how it varied between schools, and how it was perceived by the disabled and their carers. The experiences of the young people were compared with guidelines for good practice based on relevant legislation. Results showed that young disabled people experienced a poor handover to adult services if they had no "statement of special educational need" or if they went to further education college. Young people with cerebral palsy or complex multiple problems fared less well than those with spina bifida or juvenile chronic arthritis. There are several deficiencies in the legislation. Physically disabled young people should receive a transition review regardless of whether they have a "statement". The range of severity and type of disorders among the young physically disabled argues for a range of services--the category is too broad to be useful for research, service planning, and provision.

Adolescent↗
PubMed1998

Centrally-mediated opioid-induced immunosuppression. Elucidation of sympathetic nervous system involvement.

Opioid-induced modulation of the immune system is a complex phenomenon involving opioid receptors, central and sympathetic neural pathways, catecholamine receptors, and other regulatory mechanisms. The precise neural pathways involved in centrally-mediated immune modulation are not currently defined. In addition, the physiological purpose for endogenous opioid modulation of the immune system is not well understood. Perhaps this modulation phenomenon represents an integral feedback loop within a much larger homeostatic control system. Indeed, the role of the HPA axis in immune regulation can not be discarded, and in fact, probably serves to balance immune function, in concert with multiple feedback systems, around some undiscovered parameter of efficiency. Perhaps the physiological role of endogenous opioid control is to act as a monitor poised to subvert chronic inflammatory processes and autoimmune disorders. Regardless of the evolutionary heritage of this and despite the overwhelming complexity of immune regulation, important work substantiating a bidirectional communication link between the brain and the immune system has created a foundation for further elucidation of the intricacies of immunoregulation.

Animals↗
PubMed1997

Fatal meconium aspiration in spite of appropriate perinatal airway management: pulmonary and placental evidence of prenatal disease.

OBJECTIVE: Our purpose was to summarize eight cases of fatal meconium aspiration syndrome where pathologic review showed evidence of chronic prenatal disease and to compare these findings with those of a group of control infants and fetuses who died of other causes. STUDY DESIGN: A 15-year retrospective chart review identified the infants who died of meconium aspiration within 48 hours of life and who also had autopsies performed. Neonatal pulmonary and available placental pathologic findings are described from these study infants and are compared with published norms and with autopsy results from a group of control infants and fetuses. RESULTS: Seven of the eight study infants underwent suctioning of the trachea immediately after birth. In all eight cases the neonatal lungs demonstrated histologic evidence of significant hypoxic changes of a chronic nature with onset before birth. The available placentas showed variable but significant abnormalities that support a case for subacute or chronic in utero compromise. CONCLUSIONS: As in other reports, there is evidence that meconium aspiration may be a prenatal rather than a postnatal disease. However, this is the first study that presents evidence on the basis of both pulmonary and placental pathologic findings and reinforces the importance of placental examinations in complicated pregnancies.

Bronchi↗
PubMed1997

A re-appraisal of screening for colour vision impairments.

Screening for colour vision impairments (CVI) has been carried out in schools in the UK since 1934, but little is known about its yield or value. A survey was conducted among Sheffield schoolboys, school nurses and optometrists to determine the benefits of CVI screening. The results indicated that between 4.2 and 5.2% of boys had been identified as having a CVI, compared with the expected prevalence of 8%. Boys were ill-informed about the significance of CVI for careers planning but recognized the potential importance of having this information before making decisions about choice of subjects and examinations. Possible reasons for the low yield of screening are reviewed and alternative strategies are discussed.

Adolescent↗
PubMed1997

Assessment of maternal anxiety following neonatal screening and investigation for occult spinal dysraphism.

The objective was to determine maternal anxiety and attitudes associated with a programme of neonatal screening and investigation for occult spinal dysraphism. Questionnaires were completed after diagnostic investigation (time 1) and 6 months later (time 2) by 83 mothers of babies with possible markers of occult spinal dysraphism who were normal on spinal ultrasound. Outcome measures were: attitudes to the programme; maternal adjustment and attitudes to the baby; the State-Trait Anxiety Inventory. Fifty-four other postnatal mothers formed the comparison group for maternal adjustment. No significant differences were found between investigation group (time 1) and comparisons on measures of maternal adjustment. Anxious mothers gave more negative responses to some maternal adjustment items but not to attitudes to the programme. Mean state anxiety at time 1 (33.66) and time 2 (33.69) and mean trait anxiety (36.23) were not higher than in mothers of normal babies. It can be concluded that a programme of investigation for neonatal abnormalities that pays attention to detail need not cause excessive maternal anxiety. However, some mothers remain anxious even after receiving normal results. Anxiety can be assessed during appraisal of a new investigation programme, but refinements are needed.

Adaptation, Psychological↗
PubMed1996

Needs of disabled children and their families.

In the new NHS those who provide services for disabled children need to measure and demonstrate their effectiveness, but there are no easily available outcome measures for use by child development centres and teams. The development of an alternative approach, using a series of statements of good practice, is described. Parents of children with cerebral palsy were asked to participate in semistructured interviews, to ascertain the value and relevance of these quality statements. Parents were most concerned about the standard of news breaking and early follow up, the sharing of information, and the supply and repair of equipment. The findings were used to modify the quality checklist and it is proposed that this should form the basis of a "charter for disabled children and their families'.

Attitude to Health↗