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Biomedical subjects

T Dunne

Publications and source records attributed to T Dunne.

16 recordsLinked to original sources
PubMed2000

Interferometric radar measurements of water level changes on the Amazon flood plain

Measurements of water levels in the main channels of rivers, upland tributaries and floodplain lakes are necessary for understanding flooding hazards, methane production, sediment transport and nutrient exchange. But most remote river basins have only a few gauging stations and these tend to be restricted to large river channels. Although radar remote sensing techniques using interferometric phase measurements have the potential to greatly improve spatial sampling, the phase is temporally incoherent over open water and has therefore not been used to determine water levels. Here we use interferometric synthetic aperture radar (SAR) data, acquired over the central Amazon by the Space Shuttle imaging radar mission, to measure subtle water level changes in an area of flooded vegetation on the Amazon flood plain. The technique makes use of the fact that flooded forests and floodplain lakes with emergent shrubs permit radar double-bounce returns from water and vegetation surfaces, thus allowing coherence to be maintained. Our interferometric phase observations show decreases in water levels of 7-11 cm per day for tributaries and lakes within approximately 20 km of a main channel and 2-5 cm per day at distances of approximately 80 km. Proximal floodplain observations are in close agreement with main-channel gauge records, indicating a rapid response of the flood plain to decreases in river stage. With additional data from future satellite missions, the technique described here should provide direct observations important for understanding flood dynamics and hydrologic exchange between rivers and flood plains.

Journal Article↗
PubMed1999

Pre-school follow-up of a cohort of children with myelomeningocele in Cape Town, South Africa.

A cohort of South African children with myelomeningocele was followed for 5 years. Fifty-three were from metropolitan Cape Town and 65 from rural areas including the tribal region of Transkei. The mean general developmental quotient (GQ) at 5 years of age was lower than that previously reported. Black and coloured children had lower GQs than white children, but there were no significant differences between those from the urban and the rural areas. Early closure of the lesion and delivery by caesarean section were associated with higher levels of general developmental functioning. Central nervous system infections and the placement of more than one shunt for hydrocephalus resulted in lower GQs. Lesions above L2 were associated with non-ambulation. Ambulation was more likely in children in Cape Town than in rural children. Urinary incontinence occurred more frequently in rural children and among those in lower socio-economic circumstances.

Cesarean Section↗
PubMed1996

Hospital closure: Phoenix, Hydra or Titanic?

Very little has been published about the effects of hospital closure in terms of the service, financial or management issues of the process. Attempts through a case-study format to redress the balance and as such represents the reflections of practitioners who have recently undergone the experience of hospital closure and the often neglected issues arising both during and after the process.

Employment↗
PubMed1996

A high prevalence of abnormal personality traits in chronic users of anabolic-androgenic steroids.

OBJECTIVE: (1) To assess the personality profiles of the anabolic androgenic steroid users (AAS) and (2) to determine whether valid premorbid personality traits could be obtained from cross sectional assessment using multisource data. METHODS: The first author became a participant-observer in a group of body builders. An experimental group of body builders who had been using AAS for no more than 18 months (n = 12) was identified. A group of control subjects, each of whom claimed that he did not, and never had, used AAS (n = 12) was also recruited during this period. Key informants played a crucial role in recruiting subjects representative of the AAS and body building communities. An interview schedule based on the Diagnostic and statistical manual of mental disorders (DSM3-R) personality disorder criteria was conducted with each subject. Additional data were obtained from an AAS using informant and significant others including family and friends. RESULTS: The user group was significantly heavier than the control group and showed abnormal personality traits, in contrast to the control group. Personality traits of AAS users before the onset of AAS use, assessed retrospectively, were not different from personality traits of control subjects. There were significant differences between the before and after personality traits in AAS user group. CONCLUSIONS: The results suggest (1) that AAS use is associated with significant disturbances in personality profile, and (2) that these personality disturbances are possibly the direct result of AAS use.

Adolescent↗
PubMed1995

The prevalence of antibodies to hepatitis C virus at two haemodialysis units in South Africa.

The prevalence of antibodies against hepatitis C virus (HCV) was determined in 103 haemodialysis patients who attended two dialysis units in South Africa. With the use of a second-generation enzyme-linked immunosorbent assay (UBI HCV EIA, Organon Teknika, The Netherlands) and a 4-recombinant immunoblot assay (Chiron Corporation, USA), antibodies to HCV were found in 22 patients (21%). Statistically significant associations with anti-HCV carrier status were duration of dialysis (P = 0.0005) and number of blood transfusions received (P = 0.008). With stepwise logistic regression analysis it was not possible to separate the effects of HCV status associated with these two variables. A transient elevation in alanine aminotransferase (ALT) occurred in 8 of the 22 anti-HCV-positive patients, compared with 14 of the 81 anti-HCV-negative patients (P = 0.054). As yet, no patients have clinical evidence of ongoing liver disease or persistently elevated ALT levels. Of the 45 dialysis staff members tested, none was positive for anti-HCV.

Adolescent↗
PubMed1993

Serial measurements of circulating tissue plasminogen activator and fibrin(ogen) degradation products predict outcome in gestational proteinuric hypertension.

Gestational proteinuric hypertension (GPH), a major cause of maternal death, may be characterised by hypertension and proteinuria alone or may progress to disturbed coagulation and multiorgan failure. Since the condition can only be reversed by termination of pregnancy, there is a need for reliable indicators of severity. We found circulating levels of tissue plasminogen activator (tPA) (27.98 +/- 2.12 v. 7.17 +/- 0.81 ng/ml, mean +/- SEM), fibrin(ogen) degradation products (FDP) (7.55 +/- 1.99 v. 1.92 +/- 0.47 micrograms/ml) and fibronectin (221 +/- 15.2 v. 120 +/- 15.2 micrograms/ml) to be significantly increased in 21 patients with severe GPH when compared with 21 normotensive, age- and gestational age-matched pregnant controls. More importantly, patients who developed severe GPH showed a progressive increase in tPA and FDP levels with time. This was in contrast to patients who had hypertension and proteinuria alone, in whom tPA and FDP concentrations did not increase. Parallel measurements did not reveal a fall in platelet count or an increase in urinary protein excretion in patients who subsequently progressed to severe disease. Our findings may be of assistance to clinicians faced with the need to prolong pregnancy in patients with GPH in order to ensure fetal viability.

Enzyme-Linked Immunosorbent Assay↗
PubMed1991

St. Thomas' Hospital cardioplegic solution. Beneficial effect of glucose and multidose reinfusions of cardioplegic solution.

The intention of this study was to determine whether glucose is beneficial in a cardioplegic solution when the end products of metabolism produced during the ischemic period are intermittently removed. The experimental model used was the isolated working rat heart, with a 3-hour hypothermic 10 degrees C cardioplegic arrest period. Cardioplegic solutions tested were the St. Thomas' Hospital No. 2 and a modified Krebs-Henseleit cardioplegic solution. Glucose (11 mmol/L) was beneficial when multidose cardioplegia was administered every 30 minutes. Including glucose in Krebs-Henseleit cardioplegic solution improved postischemic recovery of aortic output from 57.0% +/- 1.8% to 65.8% +/- 2.2%; p less than 0.025. The addition of glucose to St. Thomas' Hospital No. 2 cardioplegic solution improved aortic output from 74.6% +/- 1.9% to 87.4% +/- 1.9%; p less than 0.005. Furthermore, a dose-response curve showed that a glucose concentration of 20 mmol/L gave no better recovery than 0 mmol/L, and glucose in St. Thomas Hospital No. 2 cardioplegic solution was beneficial only in the range of 7 to 11 mmol/L. In addition, we showed that multidose cardioplegia was beneficial independent of glucose. Multidose St. Thomas' Hospital No. 2 cardioplegia, as opposed to single-dose cardioplegia, improved aortic output recovery from 57.4% +/- 5.2% to 74.6% +/- 1.9%; p less than 0.025, and with St. Thomas' Hospital No. 2 cardioplegic solution plus glucose (11 mmol/L) aortic output recovery improved from 65.9% +/- 2.9% to 87.4% +/- 1.9%; p less than 0.005. Hence, at least in this screening model, the St. Thomas' Hospital cardioplegic solution should contain glucose in the range of 7 mmol/L to 11 mmol/L, provided multidose cardioplegia is given. We cautiously suggest extrapolation to the human heart, on the basis of supporting clinical arguments that appear general enough to apply to both rat and human metabolisms.

Animals↗
PubMed1990

Endothelial cell toxicity of solid-organ preservation solutions.

Endothelial cell damage caused by myocardial cardioplegic solutions (Bretschneider HTK and St. Thomas' Hospital No. 2) or renal and hepatic cold storage solutions (modified Collins and University of Wisconsin solution) was assessed in monolayer cultures of adult human venous endothelial cells at 4 degrees to 10 degrees C with phase-contrast microscopy. St. Thomas' Hospital solution caused the cells to contract, resulting in disruption of monolayer integrity and opening of intercellular gaps, and resulted in a 24-hour postexposure survival of 51.0% +/- 2.4%. Bretschneider HTK solution altered cellular morphology less and produced the best postexposure survival (80.2% +/- 2.6%; p less than 0.001). Although morphology was altered the least with University of Wisconsin solution, postexposure survival with this solution, which was similar to that with modified Collins solution, was superior to that with St. Thomas' (p less than 0.01) but inferior to that with Bretschneider HTK (p less than 0.05). The superior protection provided by Bretschneider HTK was due to its additives histidine, tryptophan, and KH-2-oxygluterate (p less than 0.005), and to its low chloride content (p less than 0.005). Furthermore, modifying St. Thomas' solution by decreasing its chloride content improved cell survival to 71.2% +/- 2.3% (p less than 0.001). Normothermic (37 degrees C) exposure to Bretschneider HTK, modified Collins, and University of Wisconsin solution was cytotoxic, whereas normothermic exposure to St. Thomas' cardioplegia was not. In conclusion, the preservation solution that is the least harmful to endothelial cells at hypothermia is Bretschneider HTK cardioplegic solution.

Adenosine↗
PubMed1978

Age-dependent structural changes in human neuronal chromatin.

After partial digestion with micrococcal nuclease, DNA was extracted from nuclei of cerebral cortex neurons from young (23--36 y.) and old (78--85 y.) humans. The DNA fragments were subjected to gel electrophoresis, and their base-pair content determined. The nucleosomal DNA repeat length was found to increase from 170 (+/- 18) base-pairs in the young group to 199 (+/- 8) base-pairs in the old group. This increase of 29 base-pairs appears to be confined to the linker region of the nucleosomal DNA, since the core-DNA was always found to contain approx. 140 base-pairs. In addition, the amount of nuclear DNA digested by the micrococcal nuclease was observed to vary with age: after 30 min. of incubation at 37 degrees C hydrolysis of up to 80% of the nuclear DNA in the young but only up to 60% in the old neuronal nuclei was achieved. The age-dependent increase in chromosomal DNA repeat length is a direct proof of alterations in the basic chromatin structure with aging. It cannot be decided, however, whether the change in DNA digestibility is dependent on alterations of the chromatin basic structure, its superstructure, or both.

Adult↗
PubMedDate not supplied

National health care and the grammar of management.

Managers working for the many various interest groups involved in health care reform will necessarily have to make adaptations, according to author Tad Dunne, Ph.D. Thus, Dunne examines some philosophical assumptions about what managers really manage along with some proposals on how to successfully implement the new health care plan, whatever form it ends up taking.

Administrative Personnel↗
PubMedDate not supplied

Group-level ethics in managed care.

Managed care, the newest scheme for health care delivery, is under fire for skimping on quality, hiding information from patients and restricting free choice of providers. Medical group managers now face ethical questions quite unlike the medical ethics taught in medical schools. The new questions are about how the entire network of U.S. health care institutions work. Five principles can guide an appropriate ethics for this group-level reflection: 1) institutions are means to support the common-wealth, not ends in themselves; 2) people have a right to shape their health care options; 3) competition does not exclude collaboration; 4) a proper cost-benefit analysis will regard the entire community, not merely one institution; and 5) mission statements should be written by the people involved in delivering the care.

Cost-Benefit Analysis↗