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Biomedical subjects

E Myhre

Publications and source records attributed to E Myhre.

At least 55 records · Page 3Linked to original sources
PubMed1983

The effects of nifedipine, a calcium antagonist, on platelet function.

Platelet function was studied before and 1 hour after ingestion of 20 mg nifedipine, a new calcium antagonist, in 20 patients with coronary heart disease. Platelet counts remained unchanged. Platelet adhesiveness, measured as retention in glass bead columns with Hellem's method for native blood, did not drop significantly eigher when 0.9 or 3.6 ml of blood was used. Platelet aggregation, which is dependent on extracellular calcium, was induced in citrated platelet-rich plasma. The mean maximal rate of primary aggregation, initiated with three different concentrations of adenosine diphosphate, was reduced by 20% to 26%. The rate of irreversible collagen-induced aggregation was on average 23% lower after nifedipine. The mean bleeding time was 36 seconds, or 12%, longer after ingestion of the drug. The moderate, but significant reduction of platelet aggregation and prolongation of the bleeding time by nifedipine may be mediated through inhibition of calcium transport across the platelet membrane.

Adenosine Diphosphate↗
PubMed1983

Isolated ventricular septal defect in adults. Clinical and haemodynamic findings.

Clinical and haemodynamic findings were reviewed in 109 consecutive patients in whom an isolated ventricular septal defect was diagnosed after the age of 15 years (range 15-65 years). Most patients had no or minor cardiac symptoms. Based on the left to right shunt size and pulmonary pressure, 32 (29%) patients had large and 75 (69%) small ventricular septal defects, whereas in two (2%) patients data were insufficiently complete for determining the size. The anatomical location was membranous in 92% and muscular in 8% of the 51 patients in whom this could be assessed from a left ventricular angiogram or the surgeon's report of a subsequent operation, or both. Nine (8%) patients had developed the Eisenmenger syndrome, 12 had aortic regurgitation, and 16 (15%) had bacterial endocarditis, the incidence of the latter being 5.7 per 1000 patient years. Of the 34 (31%) patients who underwent surgery, five (15%) died while in hospital. In contrast with reports from paediatric series our study in adults showed a predominance of small ventricular septal defects and a high frequency of irreversible pulmonary hypertension and serious complications, such as aortic regurgitation and bacterial endocarditis. Thus ventricular septal defects in adults should--regardless of symptoms--be looked on as potentially serious.

Adolescent↗
PubMed1983

False suspicion of coronary heart disease: a 7 year follow-up study of 36 apparently healthy middle-aged men.

Latent coronary heart disease was suspected in 115 of 2014 apparently healthy middle-aged men after a baseline cardiovascular survey. One hundred five of these men underwent angiography and 36 were found to have normal coronary arteries (group 1). A 7 year follow-up survey revealed that: (1) three had died of sudden cardiac death, (2) four had received a diagnosis of cardiomyopathy, (3) one had developed aortic dilatation/aortic regurgitation since the baseline survey, (4) they all had a significantly more rapid decline in their physical performance and maximal heart rate levels from the time of the baseline survey to follow-up than did randomly selected normal controls (group 2), and (5) thallium study results were normal in both groups (27 and 26 patients), but technetium ventriculography revealed a subnormal increase in ejection fraction during exercise (less than 5% units) in 14 of 27 group 1 subjects and in 4 of 26 group 2 subjects. Thus, incipient heart disease may be present in subjects in whom coronary angiographic examination has removed a previous suspicion of coronary heart disease.

Adult↗
PubMed1982

Fractionation of rat IgG subclasses and screening for IgG Fc-binding to bacteria.

The four IgG subclasses of the rat, IgGl, IgG2a, IgG2b and IgG2c, were purified from normal serum by a combination of protein A-affinity chromatography and DEAE-cellulose chromatography. Purified, radiolabelled preparations of IgG were tested for binding to Gram-positive bacteria representing five different Fc-receptor (FcR) types. Distinct rat subclass-specific Fc-binding was noted to bacterial species belonging to different Fc-receptor types. Staphylococcus aureus (FcR I) strains bind IgGl and IgG2c as shown by others. Group C and G Streptococci (FcR III) bind all four subclasses of rat IgG. Streptococcus zooepidemicus strains (FcR V) also bind all four subclases but only to a lower degree. Human group A Streptococci (FcR II) and bovine group G Streptococci (FcR IV) do not bind any of the rat IgG subclasses. Elution studies on two strains. Staphylococcus aureus, Cowan I, and human group G Streptococcus, G 148, showed that both thiocyanate and pH-elution might be useful for the fractionation of IgG subclasses bound to bacterial cells. The present work indicates the possible use of bacterial cells as solid-phase absorbents in immunological studies of rat IgG.

Animals↗
PubMed1982

Coronary artery disease with and without angina--two different entities?

Coronary heart disease (CHD), previously neither diagnosed nor suspected, was strongly suspected in 115 of 2014 men aged 40-59 years during a cardiovascular survey examination. Sixty-nine of 105 men who underwent diagnostic coronary angiography had pathologic angiograms. Twenty-six of these 69 had angina pectoris (AP) with and without pathologic exercise ECGs and 43 had pathologic exercise ECG as the only indicator of CHD. The extent of coronary artery changes was similar in the two groups. The men without AP were in almost all respects similar to 1832 men labelled as normals. The men with AP differed in several respects from their non-AP angiographic counterparts and from their non-AP angiographic counterparts and from the normals: they had more dyspepsia, a higher stress score, higher serum cholesterol and triglycerides, lower antithrombin III levels in the blood and lower blood platelet retention values. These results indicate that coronary artery disease with and without AP may represent somewhat different pathogenetic entities.

Adult↗
PubMed1982

Platelet function related to the development and presenting symptoms in coronary artery disease. An epidemiological study in apparently healthy men.

Among 2014 apparently healthy men aged 40-59 years platelet function was studied with Hellem's retention method in 488 men. In 55 of these 488 men coronary heart disease (CHD) was strongly suspected and coronary angiography confirmed the diagnosis in 34 of 51 angiographied men. Platelet responsiveness was significantly lower among those who had angina pectoris than among their CHD-suspect counterparts without angina, regardless of coronary angiographic findings. Since angiopositive men without angina and 408 "normals" had similar retention values, it seems as if presenting symptoms, but not the development of CHD are linked to platelet function. During a near maximal bicycle exercise test significantly higher peak exercise blood pressure was found among men with very low retention values than among men with retention values in the middle and upper range. This could not be explained by differences in maximal heart rate or work performance. This indicates that blood pressure regulation during exercise may in part be linked to platelet function related mechanisms.

Adult↗
PubMed1982

The absorption and excretion of methyldopa ingested concomitantly with amino acids or food rich in protein.

Absorption and urinary excretion of 2-14C-L-alpha-methyldopa (alpha MD) were investigated in 5 healthy human volunteers. The drug was administered alone, with a mixture of amino acids and with a meal consisting of roast beef. The radioactivity in plasma and urine was not decreased significantly by either treatment, and it was concluded that the overall absorption of the drug was virtually unchanged. The amount of unconjugated alpha MD in plasma and urine, however, was significantly decreased following administration of the drug with roast beef. As the acid labile conjugates of alpha MD were practically unchanged an increased biotransformation to other metabolites owing to the protein rich meal was suggested more probable than competition between alpha MD and amino acids in the specific transport systems.

Adult↗
PubMed1981

Can acetylsalicylic acid alone prevent arterial thromboembolism? A pilot study in patients with aortic ball valve prostheses.

Encouraged by the effective prevention of arterial thromboembolism with a combination of ASA and anticoagulants (9), the present study was done in 77 patients with a single Starr-Edwards aortic ball valve. They received one gm. of ASA daily, then the dose of anticoagulants was reduced gradually and the drug discontinued on average five weeks later. Six arterial embolic episodes occurred in five patients, the incidence being 14.5 complications per 100 patients per year. Five emboli were cerebral, none of them serious, and one was removed from a femoral artery. Four of the embolic episodes occurred in three of the 11 patients with continuous arrhythmia, probably from venus thrombi that developed in the left atrium. The occurrence of only two embolic complications in the 66 patients with sinus rhythm suggests some prevention of arterial thrombus formation on the prosthetic valves. The results indicate that ASA is inferior to anticoagulants in patients with arrhythmia, while it may represent an alternative to anticoagulation in individuals with sinus rhythm. We prefer, however, the combined therapy in patients with aortic valve prostheses because of the strong anti-thrombotic effect achieved by this treatment.

Adult↗
PubMed1980

Effect of specific binding of human albumin, fibrinogen, and immunoglobulin G on surface characteristics of bacterial strains as revealed by partition experiments in polymer phase systems.

Four strains of gram-positive cocci with different combinations of positive binding of human proteins were investigated with respect to changes in physicochemical surface properties after specific protein binding. Staphylococcus aureus Cowan I, two group A beta-hemolytic streptococci, and one group G streptococcal strain were studied; they represented three different combinations of reactivity for human serum albumin, human immunoglobulin G, and fibrinogen. Using single-tube partition of bacterial cells in a dextran-polyethylene glycol system of constant polymer concentration but varying ionic compositions, it was possible to detect changes in the partition of bacteria after specific protein binding. There was a correlation between the binding of radiolabled human proteins to the bacterial strains and the effect of human proteins on the partition of the bacteria in the phase systems. Thus, the specific binding of proteins to the bacteria changes their physicochemical surface properties. These types of bacteria-protein interactions may play an important role in modulating host-parasite relationships.

Animals↗
PubMed1979

Interactions between human serum proteins and oral streptococci reveal occurrence of receptors for aggregated beta 2-microglobulin.

A total of 31 strains of oral streptococci representing Streptococcus mutans, Streptococcus sanguis, Streptococcus mitior, Streptococcus salivarius, and Streptococcus milleri were tested for possible binding of human immunoglobulins G, G1, G2, G3, G4, A1, A2, M1, and M2 and haptoglobin, hemoglobin, fibrinogen, and aggregated beta 2-microglobulin. Radiolabeled beta 2-microglobulin in aggregated form showed affinity for 20 of the 31 strains tested. Binding activity for the protein was found in strains belonging to all five species. The bacterial receptor was resistant to trypsin. Monomeric, unlabeled beta 2-microglobulin did not interfere with the binding of the aggregated form. Of the other proteins tested, only the immunoglobulin A1 protein showed positive binding, and that was only with a single strain of S. milleri. beta 2-Microglobulin is present on all nucleated cell membranes in vivo. The reaction between aggregated beta 2-microglobulin and oral streptococci is a new type of human-bacterium interaction which should be considered in studies of bacterial adherence.

Beta-Globulins↗
PubMed1979

Fibrinogen binding structures in beta-hemolytic streptococci group A, C, and G. Comparisons with receptors for IgG and aggregated beta 2-microglobulin.

Binding of radiolabelled fibrinogen was measured to 197 strains of 16 different bacterial species. All streptococcal strains belonging to groups A, C, and G isolated from human sources were strongly positive. S. aureus strains showed low binding values. Occasional group B streptococci were positive. Reactive strains were also noted among group C streptococci of animal origin, Streptococcus zooepidemicus and Str. equii, and bovine beta-hemolytic group G streptococci. Bovine alpha-hemolytic group G strains as well as the remaining seven species of human origin were all negative. Inhibition experiments and correlation studies indicated that the streptococcal receptor for fibrinogen was different from immunoglobulin Fc binding reactivity. Comparisons with the newly discovered beta 2-microglobulin binding factor showed that trypsin concentrations which destroyed this receptor left the fibrinogen receptor intact. Although the two receptors correlate in strain population studies and show competition for binding the difference in trypsin sensitivity indicates that they represent two different structural entities. Both receptors might serve as basic markers for M-protein like surface components of Gram positive cocci.

Beta-Globulins↗