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Biomedical subjects

J L Thompson

Publications and source records attributed to J L Thompson.

At least 91 records · Page 5Linked to original sources
PubMed1988

Multicomponent noninvasive physiologic monitoring of circulatory function.

A multicomponent noninvasive monitoring system for high-risk critically ill patients was developed and tested in a series of 58 high-risk surgical patients. The system was comprised of a thoracic electric bioimpedance (TEB) method for cardiac output estimation, laser-Doppler velocimeter for small vessel flow, transcutaneous oxygen (PtcO2) sensor for tissue oxygenation, pulse oximeter for arterial hemoglobin saturation (SaO2) and finger pressor sensor for arterial pressure. In a series of critically ill patients, this noninvasive system was compared with the widely used invasive monitoring system with systemic and pulmonary artery catheters. Despite theoretical limitations of TEB as a measure of cardiac output, there was a satisfactory correlation (r = .83) of cardiac output measured by thermodilution (TD) and TEB throughout a wide range of severe illnesses. Moreover, changes in TEB cardiac output satisfactorily tracked changes in TD cardiac output (r = .91). There was poor correlation between TD cardiac output and BP or heart rate. The incidence of abruptly changing physiologic patterns was observed with simultaneously monitored invasive and noninvasive systems. Descriptions were made of the central circulation, peripheral perfusion, and pulmonary function; common interactive responses of these circulations were also evaluated. Monitored events defined as abrupt reductions in these variables often occurred from reduced cardiac output, PtcO2 or PtcO2/PaO2 index, and infrequently from unanticipated reductions in SaO2. Recovery from the nadir of the monitored event was associated usually with improvements in flow, PtcO2, or both. Hemodynamic and oxygen transport patterns of a few commonly encountered patterns are described.

Adolescent↗
PubMed1987

Rapid kindling in the prepubescent rat.

Bipolar electrodes, stereotaxically implanted in the hippocampus and amygdala of prepubescent rats, were used to deliver 1- or 10-s trains of suprathreshold bipolar stimulations at frequencies of 10 or 60 Hz. The stimuli were administered every 5 min. Rapid kindling was achieved with 10-s but not 1-s stimulation with both 10- and 60-Hz frequencies. Ten-s stimulations with a 60-Hz frequency resulted in more rapid kindling than 10-s stimulations with a 10-Hz frequency. The rate of kindling was similar in the hippocampus and amygdala. In the immature animal rapid kindling can be achieved with electrical stimulations with long duration and short interstimulus intervals.

Amygdala↗
PubMed1987

Critical scholarship: the critique of domination in nursing.

This article explores the development of critical scholarship in nursing. Recent examples of critical analysis in nursing literature suggest an emerging pattern of scholarship that focuses on the critique of domination in nursing. This is a pattern of scholarship that has emerged from contemporary social and historical contexts and one that reflects the experiences of working nurses exposed to contemporary schools of thought. The dynamics of critical scholarship, its origin, its progression, and some contemporary models that describe its outcomes are discussed.

Education, Nursing↗
PubMed1987

Secretory activity in salt glands of birds and turtles: stimulation via cyclic AMP.

O2 consumption in tissue slices from the nasal salt gland of the duck and the lachrymal salt gland of Malaclemys is stimulated by methacholine, a stimulation that is inhibited by bumetanide and by ouabain. In addition, the calcium ionophore A23187 mimics the action of methacholine in stimulating this secretion-related O2 consumption in both glands, suggesting a second-messenger role for this ion in the cholinergic response. However, the adenylate cyclase activator, forskolin, and the cyclic AMP analogue, 8-cpt-cAMP, also stimulate ouabain-sensitive and bumetanide-sensitive O2 consumption in both the duck gland and the Malaclemys gland. It is suggested that the mechanism of salt secretion in the Malaclemys lachrymal gland conforms to that previously described for other extrarenal salt-secreting tissues in nonmammalian vertebrates and, as in the bird gland, is subject to a cholinergic regulation potentially acting via changes in intracellular calcium. In addition to this, secretory activity in both the avian and the turtle glands can be stimulated by a previously undisclosed adenylate cyclase-cyclic AMP system. The identity of the primary signal for such a system is not known, nor is the nature of any interrelationship between the two second-messenger systems that have been identified in these glands.

Animals↗
PubMed1987

Potassium secretion by nasal salt glands of desert lizard Sauromalus obesus.

Potassium secretion by the nasal salt glands of the herbivorous desert lizard Sauromalus obesus was determined in vivo by a new technique. Intraperitoneal injection of KCl rapidly increased the potassium secretion rate from 0.28 to 15.35 mumol X 100 g-1 X h-1. A second identical intraperitoneal injection, given 15 h after the first, further increased potassium secretion to 50.09 mumol X 100 g-1 X h-1. This was associated with a doubling of plasma K+ concentration and salt gland Na+-K+-adenosinetriphosphatase (ATPase) activity. Neither salt gland weight or residual (Mg2+) ATPase activity were affected. In an isolated perfused head preparation, potassium secretion from the nasal salt glands was stimulated from 0.99 to 10.76 mumol X 100 g-1 X h-1 by methacholine and to 14.68 mumol X 100 g-1 X h-1 by forskolin. In this perfused preparation, simultaneous determination of salt gland perfusion flow (using radiolabeled microspheres) and the rate of potassium secretion revealed that the secreting glands removed 68% of the perfusing potassium ions. Calculations indicated that secretion at the maximal rate observed in vivo would necessitate a fourfold increase in the rate of blood flow to the gland.

Adenosine Triphosphatases↗
PubMed1986

Characterization of ferritin in murine erythroleukaemia cells.

Murine erythroleukaemic cells were studied to determine whether different isoferritins have different functions. The cells were labelled with radioactive iron and the pattern of isoferritins was analysed by chromatofocussing. No change was found after iron-loading the cells but after inducing erythroid differentiation with dimethyl sulphoxide (DMSO), iron was incorporated into both more basic and more acidic isoferritins. This was compared to ferritin subunit synthesis; DMSO induced the synthesis of a third, minor subunit whereas iron-loading had no effect. The fate of murine erythroleukaemic cell ferritin iron was followed after incubations in iron-deficient medium containing DMSO; some, but not all, of the ferritin iron was mobilized and used for haem synthesis, and the remaining iron was found amongst the more basic isoferritins. Finally, sequential radioactive iron labels were used to demonstrate that the movement of iron from ferritin to haem was compatible with the 'last-in-first-out' principle, but this could not be related to different isoferritins. These results show firstly that DMSO changes the pattern of isoferritins and ferritin subunits in murine erythroleukaemic cells. Secondly, iron associated with more basic isoferritins seems to be less easily mobilized for haem synthesis. These results support the concept that different isoferritins have different functions.

Animals↗
PubMed1986

An automated microcomputer-based system for determining canine paw pressure quantitatively in the dog synovitis model.

The automated system for measuring canine paw pressure is a very useful tool for the evaluation of nonsteroid antiinflammatory drugs such as indomethacin and ibuprofen in the dog synovitis model. The apparatus has been designed to give the operator control over the dog's posture while measuring hind-paw pressure. The stability of the measuring platform permits reproducible measurement of paw pressures. The software package performs direct data recording and data reduction and eliminates tedious manual calculations. Subsequently, the software produces a printout summarizing the experimental results in tabular and graphic form.

Animals↗
PubMed1986

A reappraisal of the effects of iron and desferrioxamine on the growth of Plasmodium falciparum 'in vitro': the unimportance of serum iron.

It has been suggested that P. falciparum takes up iron from serum and that desferrioxamine, an iron chelating agent, inhibits parasite growth. We have now shown, however, that when all the iron is transferrin bound, P. falciparum, in culture, takes up less than 7 pmol Fe/10(9) parasites/24 h and that incorporation is increased only in the presence of a high molecular weight iron complex not naturally found in serum. Furthermore, removal of iron serum did not reduce parasite growth, and addition of excess iron was inhibitory. Desferrioxamine inhibited growth, but this inhibition was reduced under conditions in which the transfer of iron from transferrin to desferrioxamine was accelerated. We conclude that P. falciparum does not directly utilize serum iron and that desferrioxamine does not inhibit the parasite by interfering with the supply of iron from the incubation medium. The results are relevant to clinical data which suggest that added nutritional iron enhances the host susceptibility to malaria.

Deferoxamine↗
PubMed1986

Perfusion-secretion relationships in the isolated elasmobranch rectal gland.

Perfusion and sodium secretion parameters were measured in the isolated rectal gland of Scyliorhinus canicula L. perfused at in vivo pressures, and the effect of stimulation of secretory activity by cyclic AMP and theophylline on these parameters was determined. Stimulation resulted in large increases in secretion flow rate, percentage extraction of sodium from the perfusing fluid, and arteriovenous sodium concentration difference, but did not affect perfusion flow rate or the sodium concentration of the secreted fluid. Reduction of perfusion flow rate to values below 65% of the control level, achieved by reducing perfusion pressure, produced a marked decline in sodium secretion--a process accompanied by increases in the percentage extraction of sodium and arteriovenous concentration difference of sodium, but again without any change in the sodium concentration of the secreted fluid. The in vivo consequences of these findings are discussed with reference to related findings for the avian nasal salt gland. The normal rate of secretion, its sodium concentration, and the nature of the dependence of secretion rate on perfusion flow below certain levels, were essentially unaffected by a reduction in the availability of oxygen to the gland by approximately 80%. It is concluded that the observed relationship between perfusion flow and sodium secretion rate in the stimulated gland is not related to oxygen availability, and hence that the primary underlying function of the synchronized secretion-related vasodilation seen in the gland is not to increase the supply of oxygen to the stimulated secretory tissue. We discuss possible reasons why this erroneous conclusion has been reached by other workers.

Animals↗
PubMed1985

Practical discourse in nursing: going beyond empiricism and historicism.

This discussion presents a critical appraisal of recent works in Advances in Nursing Science that have dealt with metatheoretical concerns. In metatheoretical analysis, such as that presented by Silva and Rothbart, nurses are beginning to focus on the traditions that have guided research. This process should be extended by reviewing historical stages of development in empiricist and postempiricist philosophy. Recent work in postempiricist philosophy is especially important since it can help nursing transcend historicist insights. Continental philosophy goes beyond historicist critique by focusing on practical discourse within a community of investigators. This is a stage of development that can be rationally decisive for the scientific development of nursing.

Humans↗
PubMed1984

Precision cell location and relocation techniques. An application for cell image analysis.

Two methods for precise cell location and relocation were developed at the Cell Image Analysis Laboratory, NASA, to increase the efficiency of the cell image acquisition process. The first method uses a Zeiss Zonax with a 10 micron scanning stage and automatically records cell coordinates on 5.25-inch floppy disks. The second method uses a Digital Positioning Device with a 10 micron scanning stage, and the cell coordinates displayed on light-emitting diodes (LEDs) are recorded manually. Because of its superior speed and automation, the Zonax was selected as the method of choice. By using a Zonax for off-line cell location and another Zonax for on-line cell relocation, more than three times the number of digitized images were collected in ten months than in the previous three years. Other beneficial applications of the cell location and relocation methods were realized in photomicrography, data base verification and cytopathology.

Computers↗
PubMed1983

A culture method giving substantial yields of normal nasopharyngeal epithelial cells for work with Epstein-Barr virus.

A culture method, utilising a feeder layer of lethally irradiated 3T3 fibroblasts and medium supplemented with hydrocortisone, cholera toxin, and epidermal growth factor, has been elaborated for the in vitro growth of normal human nasopharyngeal epithelial cells. This method allowed the cells to be grown in vitro for periods of up to 146 days, very considerably longer than in previously reported studies, and ensured that the cultures remained largely free from contaminating human fibroblasts. It was found possible to subculture the nasopharyngeal epithelial cells through numerous passages both by dispersing monolayers into single cell suspensions and by transferring coverslip monolayers of the cells to individual Petri dishes. By combining these two methods, at least 50 replicate epithelial cultures could be produced from each tissue sample, thus providing for the first time cultured nasopharyngeal epithelial cells in quantities suitable for extensive experiments with Epstein-Barr virus.

Cells, Cultured↗
PubMed1983

Iron metabolism in murine erythroleukaemic cells.

In an attempt to develop a model system for analysing iron metabolism in a relatively homogeneous population of early red cell precursors, the intracellular distribution of 59Fe was examined in Friend murine erythroleukaemic cells after induction of haemoglobin synthesis with dimethylsulphoxide. After incubation of the cells with 59Fe-labelled transferrin, 59Fe was incorporated into haemoglobin, various ferritin fractions, and into the pellet obtained by centrifugation. No intracellular transferrin or low molecular weight compounds were found. In a series of 'chase' experiments 59Fe accumulated in haem, and some of this radioactivity appeared to be derived from the ferritin fraction. Extra iron could be mobilized from ferritin during chase experiments using iron deficient incubation medium. These studies indicated that, at least under these experimental conditions, ferritin iron in early red cell precursors can be utilized for haemoglobin synthesis.

Animals↗
PubMed1983

Classification of bronchial epithelial atypias by the atypia status index.

The atypia status index (ASI) is a categorization method of classifying digitized images of atypical bronchial epithelial cells in sputum. The ASI is defined as a linear composite of features linearly related to atypia stage. Over 200 features were examined for more than 3,000 cells that had been classified by atypia stage (squamous metaplasia, mild, moderate or severe atypia and malignant) and staining characteristic (orangeophilia and nonorangeophilia). We reduced the number of features by using a selection process to minimize redundancy. The feature weights were optimized via a least-squares procedure. The 14 features selected accounted for over 60% of the variation of atypia stage and produced ASI values that were within one atypia stage of the criterion classification for over 90% of the cells. The results are consistent with the hypothesis of a progressive pattern in bronchial epithelial atypia and indicate the feasibility of using image analysis for mass screening of premalignant atypias in sputum from subjects considered to be at high risk for lung cancer.

Adult↗
PubMed1982

Quantification of an Epstein-Barr virus-associated membrane antigen component.

A method is described for the preparation of a 125I-labelled membrane antigen (MA) component (gp340) from B95-8 cell membranes using sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Good yields of antigenic material were obtained when renaturation of the [125I]gp340 was carried out by removal of SDS in the presence of urea and subsequent removal of the urea. The availability of purified, radiolabelled gp340 has provided the essential basis for the development of a radioimmunoassay which, for the first time, permits quantification of this antigen. The assay has been used to demonstrate that cell membrane MA is a better source of gp340 for large-scale work than is the Epstein-Barr virus envelope and to measure the increase in expression of gp340 following treatment of cells with 12-O-tetradecanoyl-phorbol-13-acetate (TPA).

Animals↗
PubMed1982

Purified Epstein-Barr virus Mr 340,000 glycoprotein induces potent virus-neutralizing antibodies when incorporated in liposomes.

The purified Mr 340,000 glycoprotein component of Epstein-Barr (EB) virus-induced membrane antigen complex incorporated into liposomes was shown to be a potent immunogen in mice. High-titer antisera were induced that (i) are specific for membrane antigen components without absorption, (ii) bind the antigens induced by three different EB virus isolates, and (iii) neutralize the ability of the virus to transform fetal cord blood lymphocytes in vitro. The development of this immunogenic form of purified antigen provides an important step towards a potential subunit vaccine against Epstein-Barr virus infection.

Antibodies, Viral↗