Uncertainties about interpretation of ventricular stimulation studies in patients with Wolff-Parkinson-White syndrome.
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Electric Stimulation↗
Biomedical subjects
K Robinson
Publications and source records attributed to K Robinson.
A portable system for measuring cutaneous thresholds for warming and cooling.
Measurement of cutaneous thermal thresholds is a valuable technique for detecting small fibre neuropathy. A robust and portable microcomputer controlled system, which separately measures thresholds for warming and cooling, is described. Thresholds at three sites have been measured; the cheek, the dorsum of the hand and the sole of the foot. Regional variability and a correlation with age have been found, indicating the sensitivity of this system.
Computers↗
Examination of the esterified fatty acids from mouse erythrocyte and synaptosomal membrane phospholipids and their distribution between the various phospholipid types.
Esterified fatty acids from mouse erythrocyte and synaptosomal membranes were characterised by fused-silica capillary gas-liquid chromatography and gas chromatography-mass spectrometry. Structural information was obtained from the mass spectra of a number of derivatives including trimethylsilyl (TMS), methyl and picolinyl esters together with the TMS ethers of glycols derived from the unsaturated acids. In addition to previously characterised acids, small concentrations of several acids previously unreported from these membranes were identified. These included branched chain acids and several unsaturated acids.
Animals↗
Smoking in an industrial population. An analysis by birth cohort.
Between 1981 and 1984, 10,923 male and 624 female employees of the Australian petroleum industry were interviewed and the information that was collected included a detailed life-time smoking history. Comparison with another survey suggested that, in terms of smoking habits at least, this industrial population did not differ substantially from the general population. On the assumption that reasons for entering and leaving the industry are unconnected with smoking habit, the data were analysed by birth cohorts. In men, each successive generation has contained fewer smokers at every age over 20 years and this is due both to a reduction in the rate of starting to smoke, and to an increase in the cessation rates. In the case of women, the situation is reversed, and successive generations show an increasing prevalence and increasing starting rates.
Adolescent↗
On electrical currents in development.
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Animals↗
A data acquisition, display and plotting program for the IBM PC.
A program, AQ, has been developed to perform analog-to-digital (A/D) conversions on IBM PC products using the Data Translation DT2801-A or DT2801 boards. This program provides support for all of the triggered and continuous A/D modes of these boards. Additional subroutines for management of data files and display of acquired data have also been developed. These programs have been written so that a minimum number of keystrokes are required for their operation. Parameter files are used to simplify reconfiguration of this program for various data acquisition tasks.
Analog-Digital Conversion↗
A time- and voltage-dependent K+ current in single cardiac cells from bullfrog atrium.
Individual myocytes were isolated from bullfrog atrium by enzymatic and mechanical dispersion, and a one-microelectrode voltage clamp was used to record the slow outward K+ currents. In normal [K+]o (2.5 mM), the slow outward current tails reverse between -95 and -100 mV. This finding, and the observed 51-mV shift of Erev/10-fold change in [K+]o, strongly suggest that the "delayed rectifier" in bullfrog atrial cells is a K+ current. This current, IK, plays an important role in initiating repolarization, and it is distinct from the quasi-instantaneous, inwardly rectifying background current, IK. In atrial cells, IK does not exhibit inactivation, and very long depolarizing clamp steps (20 s) can be applied without producing extracellular K+ accumulation. The possibility of [K+]o accumulation contributing to these slow outward current changes was assessed by (a) comparing reversal potentials measured after short (2 s) and very long (15 s) activating prepulses, and (b) studying the kinetics of IK at various holding potentials and after systematically altering [K+]o. In the absence of [K+]o accumulation, the steady state activation curve (n infinity) and fully activated current-voltage (I-V) relation can be obtained directly. The threshold of the n infinity curve is near -50 mV, and it approaches a maximum at +20 mV; the half-activation point is approximately -16 mV. The fully activated I-V curve of IK is approximately linear in the range -40 to +30 mV. Semilog plots of the current tails show that each tail is a single-exponential function, which suggests that only one Hodgkin-Huxley conductance underlies this slow outward current. Quantitative analysis of the time course of onset of IK and of the corresponding envelope of tails demonstrate that the activation variable, n, must be raised to the second power to fit the sigmoid onset accurately. The voltage dependence of the kinetics of IK was studied by recording and curve-fitting activating and deactivating (tail) currents. The resulting 1/tau n curve is U-shaped and somewhat asymmetric; IK exhibits strong voltage dependence in the diastolic range of potentials. Changes in the [Ca2+]o in the superfusing Ringer's, and/or addition of La3+ to block the transmembrane Ca2+ current, show that the time course and magnitude of IK are not significantly modulated by transmembrane Ca2+ movements, i.e., by ICa. These experimentally measured voltage- and time-dependent descriptors of IK strongly suggest an important functional role for IK in atrial tissue: it initiates repolarization and can be an important determinant of rate-induced changes in action potential duration.
Animals↗
Older women: a literature review.
Older women need special attention and study in the health care profession, yet this attention has not been forthcoming. Age has a serious impact on women. This paper reports on the state of the literature on older women. This literature review on older women includes specific problem areas, such as caregiving, social networks, and retirement. Nursing will have many opportunities for development and implementation of resources for this vast age group. The literature on older women is examined, including strengths and weaknesses. Recommendations for future research to build knowledge and theory in nursing are identified.
Aged↗
The aetiology and prognostic implications of reciprocal electrocardiographic changes in acute myocardial infarction.
The relations between reciprocal ST segment depression in the electrocardiogram and infarct size and 10 year prognosis were studied in 315 patients who survived for at least 28 days after a first anterior or inferior myocardial infarction. ST depression was more common in inferior infarcts (72%) than in anterior (37%) ones. It occurred more frequently in complicated infarcts and in the presence of considerable ST elevation. Patients experiencing second or third degree heart block were significantly more likely to show reciprocal changes. The rise in peak cardiac enzyme concentration was higher in patients showing ST depression. In patients with ST depression, peak creatine kinase concentration was 46% higher, aspartate aminotransferase was 39% higher, and lactate dehydrogenase 29% higher after correction for site and complications. A discriminant function analysis selected infarct site, peak aspartate aminotransferase, and magnitude of ST elevation as predictors of the occurrence of ST depression. Age, severity, and smoking status did not significantly improve discrimination. Despite larger increases in peak enzyme concentrations patients with ST depression had marginally fewer subsequent episodes of unstable angina or fatal or non-fatal infarction and a marginally lower 10 year death rate. Neither difference was statistically significant. ST depression occurring early in the acute phase of myocardial infarction is likely to be a reflection of electrophysiological changes taking place at the site of the infarct that is manifested in the contralateral surface of the heart. Other causes, however, such as transient ischaemia at the site of the reciprocal changes or extension of the infarct to contiguous areas cannot be excluded in all cases.
Electrocardiography↗
Return to employment of professional drivers following myocardial infarction.
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Accidents, Traffic↗
Hypertrophic cardiomyopathy: report of a family.
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Adolescent↗
Body fluid levels of lysergide (LSD).
Published lysergide (LSD) levels in body fluids are summarised, together with the results of 20 cases in which we determined LSD in body fluids by radioimmunoassay. The validity of methods used for LSD analysis is discussed.
Adolescent↗
Photometric evaluation of YAG-induced polymethylmethacrylate damage in a keratoprosthesis.
The use of the Nd:YAG laser in the photodiscission of retroprosthetic membranes represents a new clinical application. However, the potential adverse ophthalmic effects of YAG-induced PMMA damage to the keratoprosthesis are unknown. Consequently, precise photometric studies were conducted to evaluate image quality of the keratoprosthesis following YAG laser irradiation.
Humans↗
Radioimmunoassay of tricyclic antidepressant and some phenothiazine drugs in forensic toxicology.
A radioimmunoassay suitable for screening blood and urine samples for tricyclic antidepressant and some phenothiazine drugs in forensic toxicology is described. The assay displays a remarkably broad spectrum of cross-reactivity that enables therapeutic or subtherapeutic levels of most tricyclic antidepressants and a number of phenothiazines in blood to be detected. The antiserum is commercially available and the radioligand, a radioiodinated conjugate of N-acetyl-L-histidine and nortriptyline, is easily prepared. Blood samples require prior extraction to reduce the background but urine may be assayed directly. 75 microliters of blood or 100 microliter of urine are required. Haemolysis or decomposition of the samples, common anticoagulants and sodium fluoride do not affect the results. Data for 57 compounds are presented.
Antidepressive Agents, Tricyclic↗
Is there a role for the liver in the control of food intake?
The liver, despite its key place in energy regulation, has been implicated in feeding for only the last 20 yr and this theory is still quite controversial. Information about liver metabolism is transmitted to areas in the brain which receive other information relevant to feeding such as from gustatory and central glucoreceptors. Behavioral studies of feeding in which nutrients or antimetabolites have been infused into the liver are equivocal. However, if one considers the liver as acting in concert with oral factors and the gastrointestinal tract, its role in feeding becomes clearer. Glucose infusion into the liver or oral intake of glucose have small effects on glucose intake by themselves. Combined, these two manipulations interact giving reliable suppression of subsequent glucose intake. Fructose when given peripherally is not metabolized by the brain but is by the liver and can suppress feeding. These and other considerations suggest that the liver is probably important in controlling feeding as part of a sequence of integrated events beginning in the mouth, integrated by the brain, and ending with the appropriate behaviors.
Animals↗
Sodium and potassium fluxes and compartmentation in roots of atriplex and oat.
K(+) and Na(+) fluxes and ion content have been studied in roots of Atriplex nummularia Lindl. and Avena sativa L. cv Goodfield grown in 3 millimolar K(+) with or without 3 or 50 millimolar NaCl. Compartmental analysis was carried out with entire root systems under steady-state conditions.Increasing ambient Na(+) concentrations from 0 to 50 millimolar altered K(+), in Atriplex, as follows: slightly decreased the cytoplasmic content (Q(c)), the vacuolar content (Q(v)), and the plasma membrane influx and efflux. Xylem transport for K(+) decreased by 63% in Atriplex. For oat roots, similar increases in Na(+) altered K(+) parameters as follows: plasma membrane influx and efflux decreased by about 80%. Q(c) decreased by 65%, and xylem transport decreased by 91%. No change, however, was observed in Q(v) for K(+). Increasing ambient Na(+) resulted in higher (3 to 5-fold) Na(+) fluxes across the plasma membrane and in Q(c) of both species. In Atriplex, Na(+) fluxes across the tonoplast and Q(v) increased as external Na(+) was increased. In oat, however, no significant change was observed in Na(+) flux across the tonoplast or in Q(v) as external Na(+) was increased. In oat roots, Na(+) reduced K(+) uptake markedly; in Atriplex, this was not as pronounced. However, even at high Na(+) levels, the influx transport system at the plasma membrane of both species preferred K(+) over Na(+).Based upon the Ussing-Teorell equation, it was concluded that active inward transport of K(+) occurred across the plasma membrane, and passive movement of K(+) occurred across the tonoplast in both species. Na(+), in oat roots, was actively pumped out of the cytoplasm to the exterior, whereas, in Atriplex, Na(+) was passively distributed between the free space, cytoplasm, and vacuole.
Journal Article↗
The Soroako nickel project: a healthy development?
The establishment of a nickel mine has greatly affected the lives of the inhabitants of a formerly remote rural community in Indonesia. The article examines some of the health consequences of the project for the local people. In particular, it discusses problems of water and sanitation in the mining town, the nutritional consequences of changing social relations with capitalist development, and problems in the delivery of health care. The conflicts generated by these issues indicate some of the shortcomings of a national development strategy which relies heavily on private foreign investment.
Delivery of Health Care↗