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Biomedical subjects

G Gibson

Publications and source records attributed to G Gibson.

At least 145 records · Page 8Linked to original sources
PubMed1986

In vivo brain calcium homeostasis during aging.

Since in vitro experiments suggest that brain calcium metabolism is altered with aging, the estimated rate of calcium uptake by the brain in vivo was determined with senescence. Calcium-45 incorporation into cortex, striatum, hippocampus, cerebellum, forebrain, midbrain and brainstem was determined in 3-, 10- and 30-month-old mice at 5 h after either an intravenous or intraperitoneal injection. Calcium uptake (brain dpm/mg protein divided by blood specific activity at 5 h) into these regions declined 19-33% at 10 months and 41-51% at 30 months. Subcellular fractionation of the cortex revealed that the decrease was similar in P1 (myelin, nuclei and tissue debris), P2 (synaptosomes, mitochondria and myelin) and S2 (microsomes, ribosomes and cytosol). Brain calcium concentrations declined with age in brain stem (-62%) and midbrain (-48%) but did not significantly vary with age in the other regions. These results support the suggestion that alterations in calcium homeostasis may underlie age-related changes in neurotransmitter metabolism.

Aging↗
PubMed1986

Serum concentrations of meperidine in patients with sickle cell crisis.

We compared mean serum concentrations of meperidine in sickle cell patients in crisis and control patients receiving meperidine prior to incision and drainage of abscesses. Eight sickle cell and five control patients without confounding illnesses consented to participate and received 100 mg meperidine in the deltoid or gluteal muscle for pain. Blood samples were drawn at baseline, 0.25, 0.50, 0.75, 1.0, 1.5, and 2.0 hours postinjection. In the sickle cell group, mean peak concentration of meperidine was 0.32 +/- 0.08 micrograms/mL at an average of 0.5 +/- 0.07 hours postinjection. Among controls mean peak concentration was 0.72 +/- 0.37 micrograms/mL at an average of 0.6 +/- 0.11 hours. The difference in peak concentrations was significant at all time intervals (P less than .01); the difference in times to peak was not significant. We conclude that, given a standard dose, serum concentrations of meperidine differ between sickle cell and control patients, which may suggest reasons for the relatively poor pain control often noted in sickle cell patients.

Absorption↗
PubMed1986

The effects of etomidate in the cat middle cerebral artery occlusion model of brain ischaemia. An experimental study.

The effects of etomidate on focal cerebral ischaemia following transorbital occlusion of the cat middle cerebral artery were investigated. Etomidate had no effect on CBF before or after onset of ischaemia by comparison with controls, but caused a greater fall in CBF in cats with high preocclusion or initial ischaemic CBF than in those in which CBF was lower. There were more sustained rises in Kp on SG. The established flow threshold for water accumulation was lost; more gyri with CBF above and fewer gyri with CBF below the flow threshold accumulated water. The relationship between mean occlusion CBF and in vitro GABA uptake was lost; uptakes from MG were lower and from SG and EG higher than expected. In the ischaemic penumbra there was a trend towards reduction in CBF, disruption of ion homeostasis and cerebral oedema formation, whilst in areas of lower flow there was some recovery of GABA uptake and less cerebral oedema following administration of etomidate.

Animals↗
PubMed1985

Oral health in a long-term care institution equipped with a dental service.

The oral health and medico-dental status of 250 mostly elderly residents of a long term care institution were assessed by examination and a review of medical records. In addition, attitudes to dental care, dental experiences, and demands for care were solicited from those who could participate in an interview. There were no dental complaints from 70% of those interviewed. The complaints most frequently reported were difficulties with mouth dryness, hygiene, and chewing. Natural teeth remained in at least one jaw in 30% of the 245 residents examined. Dental caries was present in 78% of this dentate group, with coronal and root lesions equally prevalent. Gingival bleeding was also common in this group and 29% had deep periodontal pockets. Nearly 50% of the mandibular dentures and 25% of the maxillary dentures examined were inadequate. Mandibular dysfunction occurred in 25% of the population and was more frequent in the dentate group. Oral mucosal pathoses were rare. No correlation was found between the systemic health and the oral health of the residents. There was a need to improve the oral hygiene of most of those examined. Less than 20% of the denture wearers would have benefitted from treatment and 10% of those with defective dentures were considered unsuitable for treatment. In contrast, 60% of those with natural teeth required restorations and 36% needed one or more teeth removed. Very few urgent needs were seen. An inter-examiner accumulative inconsistency of 11% was measured between the three examiners, and a third of the assessments made of periodontal status were contradictory.

Aged↗
PubMed1985

The effects of hyperglycaemia on changes during reperfusion following focal cerebral ischaemia in the cat.

The effects of isosmolar loads of glucose and saline after onset of focal cerebral ischaemia (middle cerebral artery occlusion) were compared in cats. In cats given saline cerebral blood flow (CBF) fell and then rose slightly on the marginal gyrus (infarct penumbra). There was a sustained fall in CBF on the suprasylvian and ectosylvian gyri (infarct core). Reperfusion restored blood flow to preocclusion levels with no overall postischaemic hypoperfusion. Below ischaemic flows of 14 ml/100 g/min brain specific gravity was reduced in a smaller proportion of gyri by contrast with non reperfused cortex, suggesting that in some gyri resolution of cerebral oedema had taken place. GABA uptake was normal in the infarct core, but was reduced within the ischaemic penumbra. In animals given glucose after occlusion, CBF fell on the marginal gyrus during reperfusion. The degree of resolution of cerebral oedema was less than in saline infused cats. GABA uptake showed a pattern of abnormality similar to that seen in saline infused cats, except that uptake values were lower in the infarct core. Pial surface potassium activity remained elevated in the penumbra following reperfusion in glucose infused cats, but returned to normal in saline infused cats. Implications for the management of cerebral ischaemia in man are discussed.

Animals↗
PubMed1983

Herpes zoster ophthalmicus with contralateral hemiplegia: identification of cause.

A patient with herpes zoster ophthalmicus developed hemiparesis that at first responded to steroids but, when these were reduced, culminated in massive cerebral infarction and death. The cause was an extensive necrotizing arteritis of large and small cerebral arteries. Herpes-like virions were identified in smooth muscle cells of the middle cerebral artery.

Aged↗
PubMed1983

The cortical ischaemic penumbra associated with occlusion of the middle cerebral artery in the cat: 1. Topography of changes in blood flow, potassium ion activity, and EEG.

The gyral topography of the ischaemic penumbra associated with middle cerebral artery occlusion was studied in cats; local blood flow (hydrogen clearance, 2-min initial slope analysis), pial surface potassium activity (Kp), and electroencephalogram (EEG) amplitude were recorded on the ectosylvian, suprasylvian, and marginal gyri. Penumbral conditions were defined as a reduction of EEG amplitude in the absence of a major increase in Kp. Whole hemisphere cerebral blood flow prior to occlusion was 35.6 +/- 11.4 (SD) ml 100 g-1 min-1 (n = 25), and fell significantly (p less than 0.001) to 13.0 +/- 4.7 (SD), 14.1 +/- 6.6, and 23.8 +/- 9.3 on ectosylvian, suprasylvian, and marginal gyri, respectively. Pre-occlusion Kp was 3.0 +/- 0.9 mM (n = 53); sustained, steady-state increases in excess of 11.5 mM occurred in 5 of 7 (71%) experiments on ectosylvian gyrus, in 13 of 22 (59%) experiments on suprasylvian gyrus, and in 2 of 24 experiments on marginal gyrus. Transient increases in Kp occurred at occlusion and resolved to baselines significantly higher than control in 5 (23%) experiments in suprasylvian gyrus and in 15 (63%) on marginal gyrus. In 7 experiments on the marginal gyrus (29%), no increase in Kp greater than 1 mM occurred. In contrast, EEG amplitude on this gyrus was reduced by middle cerebral artery occlusion in 25 of 26 experiments, and it is concluded that this gyrus is the principal site of ischaemic penumbra in the model; in 41% of experiments similar conditions were also present on the suprasylvian gyrus.

Animals↗
PubMed1983

The cortical ischaemic penumbra associated with occlusion of the middle cerebral artery in the cat: 2. Studies of histopathology, water content, and in vitro neurotransmitter uptake.

The nature of the ischaemic penumbra, as defined by suppression of electroencephalogram amplitude in the absence of increase in steady state pial surface potassium activity in excess of 13 mM, was examined in the marginal gyrus of cats subjected to middle cerebral artery occlusion. In vitro synaptosomal neurotransmitter uptake, water content (specific gravity), and histopathology at the light and electron microscopic level were studied and the results compared with those obtained at deeper, critical levels of ischaemia (less than 15 ml 100 g-1 min-1). [3H]4-Aminobutyric acid uptake was 104% of control in the marginal gyrus (NS), and 61 and 48% (p less than 0.05) in critical ischaemia. It is concluded that impairment of in vivo synaptosomal uptake is a marker of simultaneous widespread damage to neurones, rather than of a change restricted to the synaptic compartment, although the present findings cannot exclude reversible, substrate-limited impairment of uptake in vivo. Reductions in specific gravity were seen only with critical ischaemia. In 5 of 6 experiments, early or classical ischaemic neuronal cell changes and reactive glia were seen on light microscopy in restricted areas in the marginal gyrus, either in microfoci or scattered more diffusely. Ultrastructural changes were more frequent but were considered to affect only a minority of neurones. Hypotheses for selective electrophysiological suppression in penumbra are discussed.

Animals↗
PubMed1983

Inclusion body myositis (IBM): myopathy or neuropathy?

Inclusion body myositis (IBM) is described in six elderly patients (three women) and in a young familial patient. They all showed the morphologically characteristic vacuoles containing osmiophilic membranous whorls and intracytoplasmic or intranuclear inclusions. There is a well-delineated bimodal age spectrum of IBM, with onset in the second and sixth decades, but otherwise the disorder seems to be a specific entity. Clinical, electrophysiologic, and morphologic features suggest a neurogenic origin in some cases.

Aged↗
PubMed1983

Hospitals and health maintenance organizations: an analysis of the Minneapolis-St. Paul experience.

Minneapolis-St. Paul is recognized as a prime example of health care competition. Policymakers and others have been asked to look to the Twin Cities as a model upon which to base new competitive initiatives in the health care sector. Yet little is known about the impact of Health Maintenance Organizations (HMOs) on other health care providers. This study examines the effects of the area's seven health maintenance organizations on the local hospital community. Three questions are addressed. First, is the situation in the Twin Cities unique? A comparison of case study findings and the available literature together with hospital data from similarly HMO-penetrated markets suggests that the Twin Cities' hospital market is indeed different. Second, what is the nature of hospital-HMO interaction? The flexibility of contracting apparently allows hospitals to affiliate successfully with an HMO under a variety of service and reimbursement agreements. Third, what effect has HMO activity had on community-wide utilization? While HMO enrollees clearly use fewer hospital days and the trend in the community is toward fewer days, attributing the change to HMOs is difficult. A large portion of the differences between HMO and community-wide utilization levels is attributable to differences in population.

Economic Competition↗
PubMed1980

Use of prophylactic antibiotics in surgical procedures: peer review guidelines as a method for quality assurance.

Concomitant with the development of guidelines for the use of prophylactic antibiotics in surgery, the Veterans Administration undertook a survey of its surgical chiefs in which the likelihood of peer review guidelines being an effective method of quality assurance was assessed. The scope of the present problem was also assessed in terms of the misuse of antimicrobial agents in surgical units. The implications of this study for quality assurance are:(1) Chiefs of surgery can be influenced by peer review guidelines, but other sources can also have impact. (2) The control practices used by chiefs to influence their staffs are limited. (3) The mechanisms used by chiefs to monitor adherence to their policies are mostly informal. The implications of this study in relation to surgical antibiotic prophylaxis are: (1) The practices of surgical chiefs differ significantly from peer review guidelines. (2) The problem is far more serious for certain surgical procedures than for others. (3) Most misuse errors are errors of commission rather than omission.

Anti-Bacterial Agents↗
PubMed1980

Systemic complications with intravenous diazepam.

There are few published reports of complications following intravenous diazepam administration. However, more than 200 cases were reported to the United States Department of Health, Education and Welfare during a 7-year period. The systemic complications have been categorized by the authors, and common contributing factors are emphasized. The information obtained from these reports provides further knowledge of both the avoidance and the treatment of such complications and emphasizes the importance of reporting the adverse effects of any drug to a central body.

Adult↗