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Biomedical subjects

E Myhre

Publications and source records attributed to E Myhre.

At least 37 records · Page 2Linked to original sources
PubMed1985

Hypertrophic cardiomyopathy characterised by beta-adrenoceptor density, relative amount of beta-adrenoceptor subtypes and adenylate cyclase activity.

The total quantity of beta-adrenoceptors and the relative amount of beta 1 and beta 2 receptor subtypes were determined in heart biopsies of 10 patients with various heart diseases and 5 patients suffering from hypertrophic cardiomyopathy (HOCM). In membrane particle preparations from the same patients we also examined the activity of the adenylate cyclase (AC), and its response to isoprenaline, terbutaline, histamine and sodium fluoride (NaF). The high affinity ligand [125I] (1)-cyanopindolol (CYP) was used in the binding assays, and the highly beta 2-selective antagonist ICI 118 551 for the determination of beta-adrenoceptor subtypes. No differences were found in total beta-adrenoceptor density between patients with HOCM and "controls" (27.6 +/- 14.2 vs 26.5 +/- 10.7 fmol . mg-1 protein). The relative amounts of beta 1 and beta 2 receptor subtypes were similar, patients with HOCM had 82.1 +/- 4.9% of beta 1 and 14.4 +/- 3.9% of the beta 2 receptor subtype, compared with 76.3 +/- 11.5% of beta 1 and 20.7 +/- 11.0% of the beta 2 subtype in the "control" patients. Both absolute activity of AC (pmol . mg-1 protein . min) as well as the relative responses to the various stimulators were not significantly different between the two groups. Thus, this study does not support the hypothesis that HOCM is a disorder with altered beta-adrenoceptor number or adenylate cyclase response to adrenergic agonists. Furthermore, HOCM is not associated with altered response of the AC system to histamine or NaF.

Adenylyl Cyclases↗
PubMed1985

Determination of the mean pressure gradient in mitral stenosis by Doppler echocardiography.

Measurement of the mean pressure gradient provides an important estimation of the severity of mitral stenosis. However, determination of the mean pressure gradient from Doppler recordings has been unsatisfactory using previously described methods. In this study, a new method calculating the mean pressure gradient, the integral method is described. It was developed from mathematical analysis of Doppler velocity curves. Doppler echocardiography and cardiac catheterisation were performed in 23 patients with mitral stenosis to evaluate the accuracy of three current mathematical methods of determining the mean pressure gradient. The mean pressure gradients calculated by the three methods correlated highly with that measured by catheterisation (r = 0.93). However, the mean pressure gradients calculated by the previously described mean velocity square method and the arithmetical average method underestimated significantly that measured by cardiac catheterisation. In contrast, there was no significant difference between the mean pressure gradients calculated by the integral method and measured by cardiac catheterisation. These results confirm the usefulness of Doppler echocardiography for determining the mean pressure gradient in mitral stenosis and demonstrate that among current methods, the integral method provides the most accurate calculations of the mean pressure gradient.

Adult↗
PubMed1985

Noninvasive quantification of the aortic valve area in aortic stenosis by Doppler echocardiography.

To develop a noninvasive approach to the quantification of the stenotic aortic valve area, Doppler echocardiography and cardiac catheterisation were performed in 24 patients with pure aortic stenosis. The transmitral volumetric flow was measured by Doppler echocardiography and calculated as the product of the corrected mitral orifice area (CMA) and the diastolic velocity integral (DVI). The maximal aortic jet velocities were recorded by Doppler technique and integrated to obtain the systolic velocity integral (SVI). Assuming that the aortic and mitral volumetric flows are equal, the aortic valve area (AVA) was calculated as: AVA = CMA X DVI/SVI. Mean pressure gradient and cardiac output were measured during catheterisation and the aortic valve area was calculated by the Gorlin formula. Comparison between the aortic valve area determined by Doppler technique and catheterisation yielded a close correlation (r = 0.92, P less than 0.001), and there was no significant difference between the two measurements. Good correlations of the instantaneous pressure gradient and the stroke volume were also obtained between the two techniques (r = 0.91 and r = 0.90, respectively, P less than 0.001). These results demonstrate that our Doppler echocardiographic method provides a promising approach to the noninvasive quantification of the aortic valve area in aortic stenosis.

Adult↗
PubMed1985

Doppler echocardiographic measurement of cardiac output using the mitral orifice method.

Cardiac output was determined in 20 patients with various cardiac conditions by measuring the cross sectional area of the mitral orifice by echocardiography and the transmitral flow by the Doppler technique. Cardiac output was calculated by multiplying the corrected mitral orifice area by the maximum diastolic velocity integral recorded by the pulsed mode. The results were compared with that obtained by the Fick method. The correlation for cardiac output by the two techniques was high in the whole group, particularly in patients without mitral regurgitation. There was also a good correlation for stroke volume determined by the two methods. Cardiac output was significantly overestimated by the continuous mode and in patients with mitral regurgitation. These results show that the mitral orifice method provides a new and reliable approach to the non-invasive measurement of cardiac output.

Adolescent↗
PubMed1985

Changes in left ventricular stroke volume measured by Doppler echocardiography.

Cardiac stroke volume was measured simultaneously by Doppler echocardiography and thermodilution in 20 patients with coronary artery disease. Stroke volume as determined by ultrasound was calculated from the area of the aortic orifice and the flow velocity just distal to the aortic cusps. The recordings were made twice at rest. Ten patients were given dobutamine (2.5 and 5.0 micrograms/kg/min) by infusion to induce rapid changes in stroke volume from the resting state. The individual Doppler data before, during, and after dobutamine infusion correlated closely with the thermodilution data (r = 0.92). These results suggest that Doppler echocardiography reliably detects changes in stroke volume.

Adult↗
PubMed1985

Measurement of mitral regurgitation by Doppler echocardiography.

In an attempt to develop a new approach to the non-invasive measurement of mitral regurgitation, Doppler echocardiography and left ventriculography were performed in 20 patients without valvar heart disease (group A) and in 30 patients with pure mitral regurgitation (group B). Volumetric flows through the aortic and the mitral orifices were determined by Doppler echocardiography. Aortic flow (AF) was calculated as the product of the aortic orifice area and the systolic velocity integral. The mitral flow (MF) was calculated as the product of the corrected mitral orifice area and the diastolic velocity integral. The mitral regurgitant fraction (RF) was calculated as RF = 1 - AF/MF. In group A aortic and mitral flow were very similar and the difference between the two did not differ significantly from zero. In group B the mitral flow was significantly larger than the aortic flow. There was a good correlation (r = 0.82) between the regurgitant fraction determined by Doppler echocardiography and the regurgitant grades determined by left ventriculography. The regurgitant fraction increased significantly with each grade of severity. These results show that Doppler echocardiography can be used to give a reliable measure of both aortic and mitral flow. This technique is a new and promising approach to the non-invasive measurement of mitral regurgitation.

Adult↗
PubMed1984

Effects of a selective thromboxane synthetase inhibitor, dazoxiben, and of acetylsalicylic acid on myocardial ischemia in patients with coronary artery disease.

Thromboxane A2 (TxA2) may aggravate myocardial ischemia by inducing vasoconstriction and platelet aggregation in small coronary vessels, whereas prostacyclin (PGI2) counteracts these effects. Acetylsalicylic acid (ASA) inhibits the formation of TxA2 as well as PGI2, whereas dazoxiben, a thromboxane synthetase inhibitor, reduces TxA2 formation selectively. In 25 patients with coronary artery disease, 2 identical atrial pacing stress tests were performed: before and after the administration of dazoxiben (200 mg) in 15 patients and before and after ASA (250 mg) in 10. The ischemic response, quantified by coronary sinus and aortic lactate levels and by ST depression, was significantly reduced after administration of dazoxiben (p less than 0.02) but not after ASA. Heart rate at rest, myocardial extraction of free fatty acids and the arteriovenous oxygen difference was unaffected by medication. Both drugs reduced TxB2 levels to the same extent, whereas collagen-induced aggregation was more reduced after ASA than after dazoxiben. The effect of dazoxiben on ischemia was probably a result of inhibited TxA2 and preserved PGI2 production, which increased blood flow to ischemic regions.

Aspirin↗
PubMed1984

Evaluation of potential adverse effects of sodium nitroprusside during pacing-induced myocardial ischaemia in man.

To elucidate the potential harmful effects of sodium nitroprusside (NP) on myocardial ischaemia, eleven patients with coronary artery disease were studied before and during two doses NP infusion. The infusion rates were adjusted to reduce systolic aortic pressure by 10-20 mmHg and to between 100 and 110 mmHg. Myocardial haemodynamic and metabolic measurements were undertaken in sinus rhythm and during pacing-induced angina pectoris. The procedure was repeated at the low and high dose NP using the same pacing rate. One patient did not develop ischaemia and was excluded. Low dose NP reduced ischaemia slightly, whereas the higher dose had no effect despite falling indices of cardiac work. The oxygen uptake was maintained except at high dose treatment during pacing due to an increased catecholamine stimulation. The transmural perfusion gradient was unchanged at low dose NP, but fell at the higher dose suggesting reduced perfusion of ischaemic tissue. High dose NP also decreased coronary arteriolar resistance considerably which may have induced a coronary 'steal' effect. Thus, NP may induce adverse haemodynamic and metabolic changes which counteract the beneficial actions of the drug on ischaemia when used in high doses and in patients without heart failure.

Acute Disease↗
PubMed1984

Doppler echocardiography in adults with isolated ventricular septal defect.

Doppler echocardiography and cardiac catheterization were undertaken in 70 consecutive patients, 31-68 years of age (mean 39), who had isolated congenital ventricular septal defects (VSD), 28 of whom had been operated upon. In 50 patients with invasively proven VSD, 37 had a correct Doppler diagnosis of VSD (group 1) and in 13 a false negative result was obtained (group 2); i.e. a sensitivity of 74%. No false positive Doppler diagnosis was made in the 20 patients without evidence of shunt. Left to right ventricular systolic pressure difference (delta P) ranged between 55 and 142 mm Hg, with a mean value of 103 mm Hg in group 1 and 99 mm Hg in group 2. There was good correlation between delta P obtained by continuous wave Doppler and catheterisation in 17 group 1 patients with moderate and large shunts (r = 0.81, P less than 0.001). There was no correlation in the remaining 20 patients in group 1 with small shunts (r = 0.20, P greater than 0.1). Doppler echocardiography in the adult with isolated VSD has good sensitivity and excellent specificity. Doppler prediction of delta P is reasonably correct in patients with moderate and large shunts, but of no value in patients with small shunts.

Adult↗
PubMed1984

Human endometrium and endometriotic tissue obtained simultaneously: a comparative histological study.

A comparative study on the histological appearance of endometrium and endometriotic tissue obtained simultaneously has been performed. In all, 47 endometriotic samples from 28 patients were examined. In 15 cases, samples from more than one endometriotic lesion were included. The endometriotic tissue had developed a distinctive menstrual phase pattern in 23 patients (82%). In 16 of these patients (70%), the phase pattern was found to be synchronous (+/- 3 days) in the two tissue types. In seven cases (30%), it varied inconsistently as compared with the endometrial phase. In the remaining five cases (18%), no menstrual phase pattern was found in the endometriotic specimens in spite of a well-defined phase in the endometrium. When biopsy specimens from different endometriotic lesions in the same patient showed a menstrual phase pattern, the phase did not differ significantly among the specimens. Although a menstrual phase pattern could be recognized in the endometriotic tissue samples in most cases, a considerable variability in glandular and epithelial cell morphology was frequently found.

Adult↗
PubMed1984

The role of chronic non-specific inflammatory lesions of the placenta in intra-uterine growth retardation.

Placentae from 108 cases of intra-uterine growth retardation (IUGR) were examined microscopically with special emphasis on the occurrence of chronic non-specific inflammatory lesions. Sixteen cases (14.8%) showed severe villitis (SV) while 15 (13.8%) showed moderate villitis (MV). The SV-cases seemed to be more severely growth retarded, while no differences in the growth patterns appeared. A greater part of the SV-cases than of those with moderate or no villitis were cases without maternal or fetal causes for the growth retardation. The placental weight and placental index were higher in the cases with severe villitis. A mixture of lymphocytes and histiocytes was the most common finding among the placentae with villitis. Six cases of umbilical cord thrombangitis were registered, the majority of these being associated with villitis. The present findings suggest an association between intrauterine growth retardation and villitis of unknown etiology.

Birth Weight↗
PubMed1984

Determination of cardiac output by Doppler echocardiography.

Cardiac output determined by Doppler echocardiography was compared with that determined by thermodilution at rest and during dobutamine infusion in 10 patients (group A) and by the Fick method at rest in 11 patients (group B). All patients had angina pectoris without valvular heart disease. Maximum spatial blood velocity and cross sectional aortic area were estimated by the Doppler technique and echocardiography. Cardiac output was calculated by multiplying blood velocity by aortic area at various levels in the ascending aorta. The best correlation of cardiac output between the invasive and non-invasive methods was obtained when maximum velocity in the aortic root and the aortic orifice area were used in the calculations. Cardiac output was considerably overestimated when area measurements in the aortic root were used.

Adult↗
PubMed1984

Potential deleterious haemodynamic effects of glyceryl trinitrate on myocardial ischaemia in man.

The potential adverse effects of glyceryl trinitrate on myocardial ischaemia were studied using low and high dose infusions in 10 patients with coronary heart disease. Cardiac venous flow was measured by the thermodilution technique and blood was sampled for metabolic studies. Angina pectoris was provoked by atrial pacing before drug infusion and the same heart rate was regained with low and high doses of glyceryl trinitrate. Both doses reduced myocardial ischaemia equally. The low dose of glyceryl trinitrate reduced mean systolic aortic pressure from 145(23) to 128(23) mm Hg and the high dose further to 103(9) mm Hg. Myocardial oxygen uptake decreased owing to a combined reduction in preload and afterload with the low dose and was substantially more reduced with the high dose owing to a further afterload reduction. Transmural perfusion gradient did not change with the low dose of glyceryl trinitrate but fell significantly with the high dose. This fall in myocardial perfusion probably accounts for the lack of further reduction in ischaemia with the high dose. Thus the adverse effects of glyceryl trinitrate infusion are small and do not increase myocardial ischaemia.

Adult↗
PubMed1984

Is fibrocystic breast disease a pre-malignant state?

Fibrocystic disease is the most frequent lesion of the breast. When considered as a single diagnostic entity, benign breast disease has generally been reported to be associated with a relative risk of from 1.5 to 3.0 for breast cancer. Few studies have failed to find any association between fibrocystic breast disease and breast cancer. However, the term fibrocystic breast disease encompasses a variety of histologic changes and accordingly a variety of designations. This lack of a clear classification may account for the divergent results in studies on the relationship between cystic disease and breast cancer. Some investigators have in fact examined the risk of breast cancer among women with various forms of fibrocystic disease. Particularly high risks have been associated with atypical epithelial hyperplasia. There is disagreement among pathologists as to whether ductal papillomas are 'precancerous' or cancerous.

Breast Neoplasms↗
PubMed1983

The effect of a thromboxane synthetase inhibitor, dazoxiben, and acetylsalicylic acid on platelet function and prostaglandin metabolism.

Twenty-four men received either placebo, 0.1 g of the thromboxane synthetase inhibitor dazoxiben, 0.25 or 1.0 g of acetylsalicylic acid (ASA). Dazoxiben reduced the maximal rate of collagen-induced platelet aggregation, but less than did ASA. ASA abolished secondary, ADP-induced aggregation, dazoxiben not. Both drugs prolonged the bleeding-time. Plasma thromboxane B2 (TxB2) levels did not change significantly after dazoxiben, whereas the prostacyclin metabolite 6-keto-PGF1 alpha rose. The larger dose of ASA reduced both TxB2 and 6-keto-PGF1 alpha in plasma. Whole blood was allowed to clot in order to estimate prostaglandin metabolism. Both drugs prevented thromboxane production effectively. Formation of 6-keto-PGF1 alpha decreased by 95 per cent after ASA but was more than doubled after dazoxiben. Dazoxiben is a selective and effective thromboxane synthetase inhibitor, but has a weaker effect on platelet reactivity than ASA, possibly because endoperoxide formation is not prevented.

6-Ketoprostaglandin F1 alpha↗
PubMed1983

Different protein A immunosorbents may have different binding specificity for rat immunoglobulins.

Purified polyclonal immunoglobulin preparations representing the 4 rat IgG subclasses were tested for binding to Staphylococcus aureus protein A attached to 3 different solid phases (Staphylococcus aureus Cowan I bacteria, Sepharose CL4B and Sepharose 6MB). Protein A Sepharose CL4B showed higher reactivity with IgG1 and IgG2b than the staphylococci, whereas protein A Sepharose 6MB showed a lower uptake of these subclasses. No differences were seen for IgG2a and IgG2c. Protein A on different solid phases cannot be used interchangeably without confirmation of binding specificity.

Animals↗