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Biomedical subjects

J H Phillips

Publications and source records attributed to J H Phillips.

At least 235 records · Page 13Linked to original sources
PubMed1980

Bundle branch block in acute myocardial infarction. Current concepts and indications.

The blood supply to the conducting system is reviewed. As a result of discrete lesion in individual coronary arteries, specific patterns of conduction disturbances arise during myocardial infarction. Inferior wall infarctions produce relatively benign arrhythmia with blocks proximal to the bundle of His. Anterior infarctions tend to produce malignant arrhythmias, with blocks distal to the bundle of His. The appearance of intraventricular conduction blocks and bundle branch blocks may often be the only indication of the development of high grade atrioventricular block. The mortality of patients post-myocardial infarction with different conduction disorders increases but varies according to the nature of the conduction disturbance. Based upon such information, recommendations for temporary and permanent pacing are developed.

Acute Disease↗
PubMed1979

Inhibition of murine natural killer cell-mediated cytotoxicity by pretreatment with ammonium chloride.

In the present study the effect of ammonium chloride on murine natural killer (NK) cell-mediated cytotoxicity to T cell lymphoma, YAC-1 was studied. It was found that ammonium chloride treatment significantly reduced the cytotoxicity of splenic NK cells without any detectable change in cell viability. It is, therefore, suggested to avoid ammonium chloride treatment in order to obtain the realistic reflection of murine NK cell activities.

Ammonium Chloride↗
PubMed1979

Left main coronary artery disease.

Eighteen patients with significant stenosis of the left main coronary artery are reported and compared with 1,040 patients described in the ten largest published series. In comparison to previous reports, our patients have a higher incidence of congestive heart failure, previous myocardial infarction (especially inferior wall), poorer left ventricular function, and more advanced coronary artery disease. Despite this, there was no increased risk during catheterization and bypass surgery. This small group of patients reflects the modern experience that, with increasing awareness of this lesion, there need not necessarily be a higher risk during diagnostic studies and therapeutic intervention.

Adult↗
PubMed1979

Rate-related left bundle branch block secondary to intra-his block.

A 67-year-old man who had chronic aortic valvular disease with first degree AV block and rate-related left bundle branch block on the surface electrocardiogram was studied by His bundle electrography. During conduction with narrow QRS complexes, the first degree block was AV nodal in origin. With spontaneous heart rate acceleration a QRS pattern of left bundle branch block emerged, and the His electrogram revealed split His potentials. This report adds strong support to the evolving concept that left bundle branch block, in some cases, actually may be secondary to block anatomically localized to the His bundle.

Aortic Valve Insufficiency↗
PubMed1979

Hypertrophic obstructive cardiomyopathy and coronary artery spasm.

Three patients had hypertrophic obstructive cardiomyopathy and coronary artery spasm. The clinical diagnosis of hypertrophic obstructive cardiomyopathy, in all patients, was confirmed by echocardiography and angiography. Significant spasm of the right coronary artery was demonstrated in each patient by selective coronary arteriography. One patient had atherosclerotic obstructive three vessel disease, while the other two showed no evidence of any fixed organic narrowing of the coronary arteries. ST segment elevation in the inferior ECG leads was documented in two of the patients in association with coronary spasm.

Cardiomegaly↗
PubMed1978

Proton translocation of the bovine chromaffin-granule membrane.

Bovine chromaffin granules were lysed and their membranes resealed to give osmotically sensitive 'ghosts'. These swell in the presence of salts and MgATP. It is shown that this is due to proton entry accompanied by anions. The rate of swelling depends on the anion present, but swelling is not limited to media containing permeant anions. It is quite marked in solutions of sulphates, phosphates and acetates. It is not uncoupler-sensitive, suggesting that at least one component of swelling is due to coupled proton and anion entry (non-electrogenic proton translocation). Direct measurements of transmembrane pH and potential gradients generated in the presence of MgATP shows that these are rapidly established in sucrose media, and are rather little affected by the presence of salts. They contribute roughly equally to the total protonmotive force. The potential gradient is establihsed very rapidly, but the pH gradient is generated over several minutes. The gradients are not completely dissipated by uncoupler, and it is shown that, in media containing sulphate but no permeant anion, sulphate can be taken up by the 'ghosts'. There thus appear to be two mechanisms of proton translocation across the membrane, both dependent on ATP hydrolysis: an electrogenic transfer of protons, and proton movement linked to an anion transporter of broad specificity.

Adenosine Triphosphate↗
PubMed1978

Hydroxytryptamine transport by the bovine chromaffin-granule membrane.

5-Hydroxytryptamine is accumulated by resealed chromaffin-granule 'ghosts' if a pH gradient (acid inside) is imposed across their membranes by preincubating them at low pH. This uptake, like that driven by MgATP, is reserpine- and uncoupler-sensitive. This strongly suggests that catecholamines are taken up by intact granules in response to a pH gradient. In line with this, it is shown that 5-hydroxytryptamine decreases the pH gradient generated in the presence of MgATP, an effect that is inhibited by reserpine; nigericin, which discharges the pH gradient in the presence of K+, inhibits uptake. Permeant anions, however, also inhibit uptake. It is suggested that this may be because they permit equilibration of amine cations directly across the membrane, down concentration gradients.

Animals↗
PubMed1978

C-type virus-lymphocyte interactions in developing mouse thymus.

The appearance of C-type virus particles in thymus cells of Swiss mouse embryos, 11.5 to 15.5 days post-conception age (PCA), was studied with the electron microscope. In thymic rudiments of all specimens examined, virus particles were seen in epithelial cytoplasm, budding from epithelial cell surfaces and in extracellular spaces. Lymphoid cells were first seen in thymic rudiments of 13.5 days PCA, and did not display virus particles at this stage. At 14.5 days PCA, thymic lymphocytes had localized plasmalemmal thickenings of high electron-density which were adjacent to extracellular virus particles. Viruses appeared to be penetrating thymic lymphocytes by viropexis in embryos of 15.5 days PCA. At this stage, many lymphocytes also had cytoplasmic virus-containing vesicles and viral buds at their surfaces. These observations suggest the possibility that, in embryos, C-type viruses are transmitted horizontally from thymic epithelium to early populations of thymic lymphocytes.

Animals↗
PubMed1978

Adenosine triphosphate in the bovine chromaffin granule.

1. pH and potential gradients are generated across the membranes of chromaffin granule 'ghost' by incubating them with MgATP: the inside of the 'ghosts' is positive and acid with respect to the incubation medium. 2. The pH gradient is partially dissipated by inclusion of a substrate for the catecholamine pump, or a mitochondrial uncoupling agent, but is enhanced by reserpine. 3. An imposed pH gradient leads to amine uptake by the 'ghosts': a potential gradient leads to ATP uptake. Studies with inhibitors confirm that amine accumulation by chromaffin granules is dependent on the former, and that ATP uptake results from ATPase-induced potential difference generation. 4. ATP has two known roles in chromaffin granule structure: the first is as a substrate for a membrane-bound proton-translocating ATPase; the second is as a component of the intragranular catecholamine storage complex.

Adenosine Triphosphate↗
PubMed1977

Passive ion permeability of the chromaffin-granule membrane.

'Ghosts' of bovine chromaffin granules, in which the complex mixture of proteins and solutes normally found in the granule matrix is replaced by buffered sucrose are osmotically sensitive. They shrink when the osmotic pressure of the suspension medium is increased, and swell if solute entry is facilitated by the addition of ionophores. Swelling in the presence of ionophores has been used to investigate the passive ion permeability of these membranes. They have a very low permeability to K+ ions (of the order of 10(-10) cm/s); their permeability to protons, Na+ and choline ions is too low to be detected by these methods. Their passive permeability to anions decreases in the order: CNS- greater than I- greater than CCl3CO2- greater than Br- greater than Cl- greater than SO4(2)- greater than CH3CO2-, HCO3-, F-, PO4(3)- the permeability to hiocyanate being of the order of 10(-7) cm/s. Coupled proton and anion entry is extremely slow, except for weak acids. Fluoride, unexpectedly, also appears to enter rapidly when proton/K+ exchange is facilitated by nigericin. In the presence of K+ salts, nigericin, like valinomycin, induces lysis of intact granules, an effect that is not dependent on the presence of a permeant anion, but is dependent on the pH gradient across the membrane.

Animals↗
PubMed1977

Echocardiographic study of malfunction of the Bjork-Shiley prosthetic heart valve in the mitral position.

This report presents an echocardiographic study of four cases of malfunction of the Bjork-Shiley prosthetic heart valve in the mitral position. The malfunction was proved in all patients by cardiac catheterization, observation at cardiac surgery or findings at postmortem examination. Two distinctive motion patterns of the malfunctioning valves were detected in the echocardiogram. One was a rounded and slowed pattern of opening and closure that correlated with the presence of abnormal clotting on the prosthesis (two patients). The other was an unusual "hump" during the opening phase that correlated with significant perivalve leak (two patients). These patterns along with other observations appears to be valuable in recognizing mitral valve Bjork-Shiley prosthetic malfunction with echocardiography.

Adult↗
PubMed1976

Reduction in myocardial infarct size: prevention of heart cell death.

The course of myocardial necrosis, the clinical syndrome, and methods of treatment are presented. Heart cell death may be prevented by maintaining the balance between myocardial oxygen and energy supply and consumption. New technics of improving this balance by reducing myocardial energy demand, altering metabolism, increasing myocardial substrate supply, and protecting cellular integrity are discussed.

Adrenal Cortex Hormones↗