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Biomedical subjects

M McKee

Publications and source records attributed to M McKee.

At least 235 records · Page 13Linked to original sources
PubMed1991

Which general surgical operations must be done at night?

During the 1980s there has been increasing concern about hospital medical staffing. Achieving a Balance will lead to a reduction in the number of registrars and a possible increase in the work done out-of-hours by consultants. The deleterious effects of long hours of work have also attracted attention and, in particular, there is concern about the safety of operations performed at night by unsupervised junior doctors. There is an urgent need to examine how out-of-hours work can be reduced. This study was conducted in two phases. The out-of-hours surgical workload in four hospitals was examined. Appropriateness of the procedures and activities being carried out was then considered by a consensus panel, aided by a literature review. Most out-of-hours operations were performed by junior staff. The principal reasons suggested for operating at night are lack of day-time theatre space and the need to gain experience. There was considerable variation in the frequency with which different types of operation were performed among hospitals. The views of the panel suggest that up to one-third of operations currently performed at night could be postponed. It may be possible to postpone a higher proportion of operations performed after midnight. The appropriateness of the remaining operations has major implications for the work of consultants following the implementation of Achieving a Balance.

Emergencies↗
PubMed1990

Prevention of chemically induced changes in synaptosomal membrane order by ganglioside GM1 and alpha-tocopherol.

Synaptosomal membrane order has been studied by analysis of light depolarization by fluorescent dyes intercalated within membranes following exposure to various environmental toxicants. Two probes were explored: 1,6-diphenyl-1,3,5-hexatriene (DPH), signaling predominantly from the lipid-rich membrane core, and 1-[4-(trimethylamino)phenyl]-6-phenyl-1,3,5-hexatriene (TMA-DPH), reporting from the more hydrophilic membrane surface. Chlordecone, a neurotoxic insecticide, decreased the anisotropy of either dye and this change could be prevented by prior treatment of synaptosomes with ganglioside GM1 but not alpha-tocopherol. Exposure to an iron-ascorbic acid oxidizing mixture enhanced synaptosomal membrane order and this effect was blocked by preincubation with alpha-tocopherol but not ganglioside GM1. While these interactions may have partially reflected additive anisotropy changes, the protective agents were also effective at concentrations where they did not in themselves modulate membrane order. Methyl mercuric chloride at concentrations up to 100 microM had no discernable effect upon membrane order. It is suggested that these changes in membrane order may underlie some of the previously reported variations in the content of ionic calcium and in the leakiness of synaptosomes.

Animals↗
PubMed1990

Organometal-induced increases in oxygen reactive species: the potential of 2',7'-dichlorofluorescin diacetate as an index of neurotoxic damage.

The effects of the neurotoxic metals methylmercury (MeHg) and trimethyltin (TMT) on oxygen reactive species formation within a crude synaptosomal fraction (P2), using the probe 2',7'-dichlorofluorescin diacetate (DCFH-DA), and intracellular calcium ([Ca2+]i), with the fluorescent indicator fluo-3, have been investigated. Two and seven days after a single injection of MeHg (1 mg/kg) the formation rate of cerebellar oxygen reactive species was significantly increased. Hippocampal and frontocortical oxygen reactive species were elevated 2 days after TMT injection (3 mg/kg). In vitro exposure to MeHg (10-20 microM) increased the formation rate of oxygen reactive species, while TMT (5-40 microM) was without effect. Levels of [Ca2+]i were unaltered in P2 fractions from cerebellum and hippocampus of animals treated with either organometal. The data demonstrate that oxygen reactive species are elevated in brain regions, cerebellum (MeHg) and hippocampus (TMT), believed to be selectively vulnerable to these toxic agents. Findings suggest that oxidative damage may be a mechanism underlying the toxicity of both organometals. The use of DCFH-DA may have potential in the nervous system as an indicator of neurotoxic damage.

Animals↗
PubMed1990

Prevention of chemically induced synaptosomal changes.

The ability of altered environmental conditions to modulate some properties of synaptosomes has been studied. Incubation conditions used included the presence of methyl mercury or an organochlorine insecticide: chlordecone. Other adverse chemical conditions during incubation were the absence of calcium salts from the incubation medium or the addition of agents bringing about enhanced oxidative conditions. Synaptosomal parameters studied were the cytosolic level of free, ionic calcium, [Ca2+]i, the extent of depolarization-induced uptake of radioactive calcium, and the permeability of the limiting membrane. In addition, peroxidative activity was estimated by quantitation of thiobarbituric acid-reactive material. All these facets of synaptosomal function were responsive to the presence of these potentially deleterious changes in the incubation medium. While the response of [Ca2+]i was potentially in either direction, all adverse conditions increased synaptosomal permeability as evaluated by leakage of fura-2 into the extracellular compartment. Pretreatment with ganglioside GM1 in some situations or alpha-tocopherol in others could either wholly or partially prevent the onset of such altered synaptosomal characteristics.

Animals↗
PubMed1989

Increased fragility of neuronal membranes with aging.

Changes in membrane integrity have been implicated as a contributing factor in the aging process. We have examined the relative stability of synaptosomal membranes from young and aged mice, in response to chemically induced damage. The basal characteristics of the resting synaptosomes prepared from mice of either age were indistinguishable, as judged by intracellular levels of ionic calcium and by efflux of the fluorescent probe employed, fura-2. However, the response of isolated nerve endings to the presence of a neurotoxic agent, the insecticide chlordecone, was markedly different. Exposure to this chemical invariably elevated free calcium and increased the rate of leakage of fura-2 into the extracellular space. These effects were much more pronounced in preparations derived from aged animals. The implication of these findings is that neural membranes of aged animals are more susceptible to malfunction induced by xenobiotic agents and are less able to maintain homeostasis under such circumstances.

Aging↗
PubMed1981

Deficits in habituation of cardiac arousal responses incurred by telencephalic ablation in goldfish, Carassius auratus, and their relation to other telencephalic functions.

The effects of telencephalic ablation on the habituation of cardiac arousal responses in goldfish was studied. The ablation was performed either by ligating the telencephalon of habituated fish between stimulus presentations or by aspiration prior to habituation. The former technique caused dishabituation; the latter, a slower rate of habituation than that of sham-operated controls. The habituation deficit incurred by surgical ablation was found to decline with time, being small after 2 wk. The results are discussed in relation to other telencephalic involvements in behavior and to the plasticity of other parts of the brain which enables them to assume telencephalic functions.

Animals↗
PubMed1979

'TEAM' up for technology assessment.

Recently, the technology evaluation and acquisition methods (TEAM) project was launched to study the current state of the art of decision making in hospitals.

American Hospital Association↗
PubMedDate not supplied

Health sector reform in the former Soviet Republics of Central Asia.

Health services in the former Soviet Republics of Central Asia face many challenges, not least a rising burden of disease and severe economic constraints. Each government has developed proposals for reform. This paper describes the key elements of the proposals developed in each country. They have many features in common, such as financing based on social insurance, although they also have many differences, reflecting national political, economic and historical circumstances. While most attention so far has concentrated on the design of the proposed systems, it is argued here that there has been inadequate attention to the obstacles to implementation. These stem from the many adverse factors in the context within which reforms are taking place, weaknesses in the process of reform, and failure to involve the groups whose actions will be necessary for success. It is argued that governments and those advising them must place greater emphasis on the challenges of implementation, including the development of a much better understanding of the context within which change must take place.

Asia, Central↗