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Biomedical subjects

C Kerr

Publications and source records attributed to C Kerr.

At least 55 records · Page 3Linked to original sources

Cardiac electrophysiology and conduction pathway ablation.

Invasive cardiac electrophysiological (EP) testing and transcatheter ablation are new methods available for the diagnosis and treatment of complex dysrhythmias. The purpose of this review is to familiarize anaesthetists with these procedures. The information presented combines a literature review with the authors' experience. This article reviews normal cardiac conduction, tachycardia pathogenesis, principles of cardiac EP study and techniques of conduction pathway ablation. The anaesthetic considerations, including the choice of anaesthetic agent, monitoring problems, drug interactions, special methods of dysrhythmia termination in the EP lab, and complications specific to these procedures, are detailed. Balanced general anaesthesia or monitored anaesthesia care (MAC) sedation with benzodiazepines, propofol and narcotics are acceptable. Several conclusions can be drawn: transcatheter ablation is an effective treatment for many reentry tachycardias; anaesthetic assistance for this procedure will increasingly be needed; anaesthesia can easily be provided without influencing accurate EP testing; overdrive pacing is the method of choice for terminating tachydysrhythmias in the EP lab.

Anesthesia, General↗

Suicide and unemployment in Australia 1907-1990.

Ever since Durkheim postulated a relationship between economic change and suicide there has been evidence of a general association between aggregate data on unemployment and the frequency of suicide. Quantitatively, however, the association has been variable and it is clear that due to differing cultural, social and individual determinants of suicide, the relationship is complex. Methodological difficulties abound with interpretation of aggregate data. Australian records for most of the present century are suitable for examining secular trends in suicide and unemployment by age group and gender to gain an indication of the extent to which both parameters may be causally related. An aggregate/ecological study was designed to incorporate quantitative and qualitative strategies. Annual age-adjusted male and female suicide rates and annual unemployment rates were derived for the period 1907-1990. Female suicide rates were generally stable throughout the period, whereas those for males demonstrated sharp fluctuations with the peaks coinciding with times of high unemployment. The association between suicide and unemployment for 15-24 year old males was comparatively high for the recent period, 1966-1990. The increasingly youthful contribution to male suicide was demonstrated by a rise in the loss of life years during 1973-1984. Despite the inability of any investigation based on aggregate data to establish an unequivocable causal relationship, no evidence was detected to suggest that relatively high population levels of unemployment were not related to the occurrence of suicide.

Adolescent↗

Randomized controlled study of a retiree health promotion program. The Bank of American Study.

The initial results of a 12-month controlled trial of a health promotion program in 5686 Bank of America retirees, randomized into full program, questionnaire only, and insurance claims only groups, were analyzed to determine whether the health promotion program was effective. Comparisons were between program and questionnaire only groups for self-reported health habit changes, health risk scores, medical care utilization, and days confined to home, and between all groups for insurance claims data. The intervention, or full program, included health habit questionnaires administered every 6 months, individualized time-oriented health risk appraisals, personal recommendation letters, self-management materials, and a health promotion book. Twelve-month changes in health habits, health status, and economic variables favored the full program group in 31 of 32 comparisons and were statistically significant at the .05 level in two-tailed tests in 19 comparisons and at the .01 level in two-tailed tests in 13 comparisons. Over 12 months, overall computed health risk scores decreased by 4.3% in the full program experimental group and increased by 7.2% in the questionnaire only control group. Total direct and indirect costs decreased by 11% in the experimental group and increased by 6.3% in the questionnaire only control group. Analysis of claims data confirmed these trends. A low-cost health promotion program for retirees was effective in changing health behaviors and has potential to decrease health care utilization.

Aged↗

Education for management in the new public health.

The new public health movement has developed over the last decade and is emerging as an alternative to traditional concepts in Europe, Canada, and Australia, but not in the U.S.A. Fundamental principles, evolved mainly by the World Health Organization under the banner of the "Health for All by the Year 2000" Strategy, include community participation in health policy development and implementation of programs, emphases on primary health care and health promotion, and inter-sectoral cooperation involving agencies whose influence impinges on health. Little attention has been given to organizational and management activities. Decentralized organization of public health activities appears to be an absolute requirement, along with firm political commitment to new public health concepts. Typically, however, health authorities have tended to develop separate bureaus for new public health activities rather than integrate the latter with traditional administrative structures. It is evident that a new style of management is needed with emphases on flexibility and interactional skills. Formal attempts to incorporate new public health principles in graduate educational programs are currently underway in Europe, where all nations are committed to the concepts. The European M.P.H., which includes an as-yet-undefined component of management education, will have a core curriculum based on the new public health. Although there has been considerable activity in Australia, uncertainty remains over the viability of the new movement due to the creation of separate bureaus operating parallel to traditional health departments and their reliance mainly on a single source of funding from the federal government.

Australia↗

The influence of health insurance status on the organisation of patient care in Sydney public hospitals.

Utilising intensive semi-structured interviews with health professionals working in public hospitals in Sydney, a comparison was made of the perceived similarities and differences in the medical and administrative management of patients who were covered by Medicare and those who were privately insured. Interviewees argued that there was evidence of preferential access to public hospital care for privately insured patients due to medical misrepresentation of the urgency of their cases. They reported that some medical and administrative practices existed which compromised the choice of admission as a Medicare patient for those with private insurance, and for those without private insurance who were referred to hospital by a specialist. It was suggested also by the interviewees that medical considerations encouraged continuity of specialist care for Medicare patients admitted to hospital when they were known to an attending specialist. Such an allegation places in some doubt the claim made by private insurers that choice of doctor is permitted only under their cover. Interviewees did not report knowledge of any form of compromise in the quality of hospital care on the basis of medical preference for private patients. However, it was reported that private patients may, in some instances, be denied a full range of hospital services due to doctors' attempts to monopolise their treatment.

Continuity of Patient Care↗

Bovine retinal explants cultured in collagen gels. A model system for the study of proliferative retinopathy.

We have developed a model system for studying proliferative retinopathy in vitro using bovine retinal explants cultured in collagen gels. Cellular outgrowth from retinal explants occurred after 7 days as single cells from peripapillary explants or as cell sheets and tubular outgrowths from peripheral retinal explants. Single cell outgrowths were shown immunohistochemically to be endothelial cells or macrophages; sheetlike and tubular outgrowths also constituted cords of endothelial cells with stromal macrophages, but in addition glial cells were closely associated with the endothelial cells. Cellular outgrowths were preceded by extensive macrophage activation within the ischemic retinal explant, suggesting that macrophage-derived angiogenic factors may be important in inducing retinal endothelial cell proliferation. In addition, glial cell-derived factors may have a role in the development of vessellike tubular structures from endothelial cell outgrowths.

Animals↗

Efficacy of empirical cardiac pacing in syncope of unknown cause.

Cardiac pacing is often considered in patients with recurrent syncope after repeated attempts to document the cause have failed. To assess the results of this tactic we reviewed the records of 104 patients who had received pacemakers for known or suspected bradycardia between September 1973 and March 1985. The patients were classified retrospectively into three groups: group 1 (31 patients with a mean age of 73 years) had unequivocal documentation of bradycardia during syncope, group 2 (42 patients with a mean age of 71 years) had electrocardiographic or electrophysiologic evidence of potential bradycardia but no documentation during spontaneous syncope, and group 3 (31 patients with a mean age of 69 years) had a history "suggestive of" bradycardia-related syncope but no other evidence to support the diagnosis. The rates of recurrence of syncope during follow-up were 6.3%, 7.3% and 32.2% in groups 1, 2 and 3 respectively (p less than 0.01). In group 3 recurrence was more probable in patients with loss of consciousness for more than 2 minutes than in those who were unconscious for 2 minutes or less (p less than 0.05). The results suggest that pacemaker implantation is justified for recurrent syncope after extensive attempts to document a spell have failed if abnormal diagnostic test results suggest bradycardia as a possible cause. Empirical pacing is less satisfactory in patients with normal results of evaluation but may arguably be justified when patients have recurrent syncope with injury.

Aged↗

Sexual, reproductive and contraceptive risk factors for carcinoma-in-situ of the uterine cervix in Sydney.

Sexual, reproductive and contraceptive risk factors were investigated in a matched community-based case-control study of carcinoma-in-situ of the uterine cervix in Sydney. The risk was related strongly to the number of sexual partners: women who had had seven or more sexual partners in a lifetime had a six-fold increased risk compared with those with one or no partner. Early age at first sexual intercourse was also a risk factor, but this effect was reduced substantially after adjustment for the number of partners, with only a two-fold excess risk persisting for those with first intercourse before the age of 16 years as compared with those whose first sexual intercourse was at the age of 25 years or later. The long-term use of oral contraceptive agents was associated with an elevated risk (relative risk, 2.3 for more than six years of use); this effect was maintained for both oestrogen and progestogen doses. The risk increased with the number of induced abortions that had been undergone (relative risk, 2.2 for two or more abortions), but this effect was not statistically significant. A protective effect was found for women who had had a tubal ligation, for those who practised the rhythm method of birth control, and for women who breastfed. It is possible that these reduced risks may relate to unmeasured variables of life-style.

Adolescent↗

A rash decision.

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Acute Disease↗

Dual-label immunocytochemistry of the active multiple sclerosis lesion: major histocompatibility complex and activation antigens.

Fresh-frozen autopsy material containing active inflammatory lesions from 9 different patients with multiple sclerosis (MS) was analyzed by immunocytochemistry using a panel of monoclonal antibodies, and a dual-label immunocytochemical method was developed which permitted the simultaneous detection of two different surface markers on a single cell. We now report the following. (1) The predominant T-cell phenotype within MS lesions is CD2,3,8. This phenotype marks the suppressor-cytotoxic subset. (2) These cells do not express the natural killer cell marker NKH-1, which is present on a subset of CD8-positive cells in peripheral blood. (3) The infiltrating cell expresses class I (HLA A, B, C), but not class II (DR and DQ), major histocompatibility complex (MHC) molecules. (4) Other T-cell surface molecules, including the activation antigens interleukin-2 receptor, Ta1, and T11-3, as well as the marker 2H4, are largely not expressed. (5) Endothelial cells express both class I and class II MHC molecules and the 4B4 molecule in both MS and control tissue. (6) Astrocytes within the vicinity of MS lesions are predominantly class II MHC-negative. These results demonstrate that the T-cell infiltrate present in MS tissue on autopsy has a restricted phenotypic profile, but they also raise the possibility that, within this population, few activated effector cells are present.

Antigens, Surface↗

Reproductive behaviour and consistent patterns of abnormality in offspring of Vietnam veterans.

In view of the persistent claim of Australian Vietnam veterans that their health and that of their children were adversely affected, aspects of reproductive behaviour and the distribution of disease and disability in family units were investigated in a sample of Tasmanian veterans and another group chosen for comparison of selected characteristics. One third of veterans reported serious health problems and their reproductive behaviour differed with more marital breakdowns, increased use of reproductive alternatives, and more complications of pregnancy. Patterns of malformation and disease among veterans' children involved predominantly the central nervous, skeletal, and cardiovascular systems. A similar pattern was detected on review of the three other major investigations on veterans' offspring in the USA and Australia. Although plausible mechanisms remain unknown, the evidence from all available studies supports a causal contribution to defects in veterans' children from a paternally mediated genetic effect.

Abnormalities, Drug-Induced↗

Effect of sinus node on spontaneous release of natriuretic peptide in isolated atria.

Experiments were conducted to examine the release of atrial natriuretic peptide (ANP) in an isolated atrium in the presence and absence of sinus node tissue. The first series of experiments were conducted with the aid of a metabolic chamber to examine the spontaneous release of ANP by the right atrium with and without the sinus node region. The left atrium was also studied. The right atrium with the sinus node, quiescent right atrium without the sinus node, and the left atrium were incubated at 35 degrees C in 10 mL of oxygenated Tyrode's solution. After 40 min of equilibration, the incubation medium was removed at 10-min intervals for the determination of immunoreactive ANP concentration. The right atria with the sinus node released the highest amount of ANP into the incubation medium (32.2 +/- 2.7 pg.min-1.mg-1), compared with quiescent right atria (20.9 +/- 3.7 pg.min-1.mg-1). The left atria released the least amount of ANP into the incubation medium (9.9 +/- 1.5 pg.min-1.mg-1) when compared with the quiescent right atria and the right atria. In the second series of experiments, the right atrium was divided into the sinus node region and the quiescent right atrium, and these tissues were studied in paired fashion with a modified Langendorff preparation. The right atrium without the sinus node and sinus node region were perfused with Tyrode's solution, equilibrated with 95% O2 and 5% CO2 at 37 degrees C with a constant flow of 0.5 mL/min.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Gastrointestinal bleeding after craniotomy: a retrospective review of 518 patients.

A retrospective review of the medical records of 518 patients who underwent craniotomy over a 3 year interval was carried out to determine the rate of gastrointestinal bleeding and its relationship to the Glasgow Coma Score. There were 288 [55.5%] males and 230 [44.5%] females in the series; the mean age was 51.5 +/- 18.9 years. Forty percent had brain tumours, 18% had subarachnoid hemorrhage, 14% had spontaneous intracerebral hemorrhage, 19% had head injury and 8% had other diagnoses. Forty-eight [9.3%] of the patients had significant gastrointestinal bleeding, the distribution of which was as follows: hematemesis [37/518], melena [11/518] and/or hematochezia [4/518]. A further 51 [9.8%] had evidence of "coffee ground emesis" only. Of those with a Glasgow Coma Score of less than 10, 21% had significant GI bleeding while only 7% of patients with a Glasgow Coma Score greater than 10 had such a bleed [p less than 0.005]. Further analysis showed that the incidence of GI bleeding in patients who underwent craniotomy increased with decreasing GCS. GI bleeding did not correlate with age, sex, steroid administration or casual use of anti-ulcer medication.

Adult↗