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Biomedical subjects

J Wagner

Publications and source records attributed to J Wagner.

At least 505 records · Page 28Linked to original sources
PubMed1975

Stimulation by phenylephrine of myocardial alpha-adrenoceptors in the left ventricle of the cat.

In the anesthetized cat phenylephrine in doses of 10(-8), 3 x 10(-8) and 10(-7) moles/kg caused an increase of dp/dt(max.) of the left ventricle without altering the heart rate. This cardiostimulating effect was inhibited by the alpha-adrenolytic drug phentolamine (10(-6) moles/kg). The beta-adrenolytic agent prindolol (10(-7) moles/kg), which inhibited the increase of dp/dt(max) evoked by isoprenaline as well as by noradrenaline did not influence the positive inotropic effect of phenylephrine, thus favouring the view that there exist myocardial alpha-adrenoceptors in the ventricle of the cat.

Animals↗
PubMed1975

[Permeation-increasing activity of puncture-fluids: 2. Chromatographic and immunoelectrophoretic studies].

A human pleural effusion was separated by gel chromatography, DEAE-chromatography, disk-electrophoresis and immunoelectrophoresis. The fractions obtained were tested for the permeation-increasing activity. IgA, IgM, IgG, transferrin and haptoglobin are not responsible for a permeation-increasing effect. Albumin, alpha1-antitrypsin, acid alpha1-glycoprotein and alpha2-macroglobulin appear only in permeation-active fractions. Of these proteins, however, no direct effect on the permeability of animal membranes is known. It is discussed, whether proteolytic enzymes, which may be bound to these proteins are responsible for the increase of permeation.

Adult↗
PubMed1975

[Non-invasive myocardial scanning with thallium-201: basic principles and methods (author's transl)].

201Tl scanning demonstrated viable myocardium in the area supplied by the anterior interventricular branch (on frontal scanning) and viable myocardium in the interventricular septum and left ventricular lateral wall (scanning in the second oblique position) in 9 of 11 patients. Akinetic myocardial segments in the left ventricular anterior wall and left ventricular apex could be recognized by absent activity when scanning from in front. But hypokinetic segments, which contrary to the appearance with akinesia cannot be equated with myocardial scar, could not according to present experience be recognized by 201TL scanning. The special advantage of 201Tl scanning is is that, except for its intravenous injection, no further invasive procedure has to be undertaken, and it can be repeated. No side effects of complications have been observed.

Angiocardiography↗
PubMed1975

[Selective coronary perfusion scintigraphy. II. Abnormal coronary perfusion pattern (author's transl)].

Integrated assessment of selective coronary angiorgrams and perfusion scintigrams of 86 patients with coronary-artery insufficiency revealed anatomical and topographical details which could not be achieved with one of these methods alone. Pathological perfusion patterns were quite different from normal ones. The functional effects of single, centrally located stenoses, of more peripheral and multiple narrowings, as well as of anastomoses and collaterals were adequately demonstrated by selective coronary perfusion scintigraphy and prevented diagnostic errors. It is, therefore, an additional aid in the diagnosis of coronary-artery disease.

Collateral Circulation↗
PubMed1975

[Permeability enhancement by exudates: 1. Demonstration of high-molecular substances in the animal model].

By means of ultracentrifugation, gel chromatography and polyacryl amide electrophoresis the peritoneal exudates of the rabbit, which increased the permeability of animal membranes, were separated. Among the highly molecular fractions two regions were found, which possessed an activity increasing permeation. Following the chromatographic separation of exudates of the rabbit, which did not reveal an activity increasing permeation, were also found two regions with an activity increasing permeation. The cuases for the activation during the separation process are discussed.

Animals↗
PubMed1975

Functional antagonism between calcium-antagonists and noradrenaline on isolated guinea-pig atria.

In the isolated electrically driven guinea-pig atrium the influence of D 600 and nifedipine on the action of noradrenaline was investigated. 1. The calcium-antagonists caused a dose-dependent negative inotropic effect. 10(-7) M of D 600 or nifedipine inhibited the contractile amplitude by 75 and 55%, respectively. 2. In spite of the pronounced negative inotropic effect evoked by the two calcium-antagonists, the maximal response to noradrenaline was not changed. The sensitivity of the myocardium to noradrenaline was only slightly diminished i.e. by a factor of 4.6 and 3 as calculated from the pD2-values. 3. The functional antagonism between noradrenaline and calcium-antagonists, therefore, offers the possibility to overcome cardiac side-effects of calcium-antagonists.

Animals↗
PubMed1975

Influence of papaverine, D600, and nifedipine on the effects of noradrenaline and calcium on the isolated aorta and mesenteric artery of the rabbit.

The effects of papaverine and of the organic calcium-antagonistic agents D 600 and nifedipine on the contraction induced by noradrenaline and calcium were studied on the isolated aorta and mesenteric artery. The affinities of both agonists, given as pD2-values, were significantly higher on the aorta than on the mesenteric artery. Under our experimental conditions D 600, nifedipine and papaverine were found to act as antagonists against calcium and noradrenaline in a non-competitive fashion. In either vessel, the calcium-antagonistic activity of D 600 and nifedipine was about 1000-fold greater than that of papaverine, whereas their antagonistic activity against noradrenaline was bout 1000-times weaker, i.e. D 600 as well as nifedipine were about equipotent with papaverine. The comparison between the calcium- and the noradrenaline-antagonistic activity offers the possiblity to evaluate the specifcity of calcium antagonistic agents.

Animals↗
PubMed1975

Influence of temperature on the positive inotropic effects mediated by alpha-and-beta-adrenoceptors in the isolated rabbit papillary muscle.

On the isolated rabbit papillary muscle experiments were carried out to determine whether the positive inotropic effects mediated by alpha- and by beta- adrenoceptors are brought about by different mechanisms or not.--For this reason the influence of temperature and the effect of the calcium antagonist D600 on the responses to phenylephrine and to isoprenaline were compared. 1. The maximal inotropic effects of phenylephrine, isoprenaline and calcium were not affected by raising the temperature of the organ bath from 37 degrees to 42 degrees C, wheras the basal developed tension of the muscle was significantly decreased. 2. The dose-response curve for phenylephrine was markedly shifted to the right by raising the temperature (pD2=0.89), while that for isoprenaline was also shifted to the right, but to a lesser extent (pD2=0.23). 3. In the presence of 1.5 times 10-8 M pindolol the shift of the dose-response curve for phenylephrine induced by elevation of temperature was more prominent (pD2=1,91), whereas phentolamine (3 times 10-6 M) inhibited the temperature-induced shift. 4. The positive inotropic effect of phenylephrine--mediated by alpha-adrenoceptors under blockade of beta-adrenoceptors by 1.5 times 10-8 M pindolol--was markedly depressed by D600 (10-7 and 3 times 10-7 M): the dose-response curve was shifted to the right ant the maximal response was depressed. On the other hand, the positive inotropic effect of isoprenaline--mediated by beta-adrenoceptors--was affected to a lesser extent by D600 and the maximal response was not changed. It indicates that the stimulation of alpha- adrenoceptors in the rabbit papillary muscle induces a positive inotropic response through a biochemical process different from that caused via beta- adrenoceptors, i. e., stimulation of alpha- adrenoceptors may increase the intracellular calcium level mainly by changing the transmembrane calcium flux.

Animals↗
PubMed1975

[The Bland-White-Garland syndrome: hemodynamics, clinical picture, therapy].

Two patients with anomalous origin of the left coronary artery from the pulmonary artery are presented. Anatomy, embryology, the problem of the direction of blood flow in the anomalous vessel, and the clinical symptoms of this syndrome are discussed. In spite of large fibrotic areas in the myocardium, the ECG-changes were minimal. Therefore, a nearly normal ECG does not exclude this anomaly. In patients with sudden, unexpected death one should suspect an anomalous origin of a coronary artery. The classification in an "infantile" and "adult" type reflects the extent to which collateral vessels have developed. Ligation of the anomalous coronary artery at the side of its origin with concomitant aorto-coronary bypass appears to be a rational and the only effective way of therapy.

Adult↗
PubMed1975

The influence of temperature increase, elevation of extracellular h+-concentration, and of triiodothyronine on the actions of phenylephrine, histamine, and beta-sympathomimetic drugs on rabbit aortic strips.

In the isolated preparation from the rabbit thoracic aorta, the affinities of the vasoconstrictor agents phenylephrine and histamine, as well as of the vasodilator beta-sympathomimetic drugs isoprenaline, fenoterol (TH 1165a), terbutaline, and salbutamol under the conditions of temperature increase, triiodothyronine and decrease of extracellular pH were investigated. It was observed that (1) a temperature increase from 25 degrees to 42 degrees C significantly indreased the maximal tension evoked by histamine, whereas that induced by the alpha-sympathomimetic drug phenylephrine was not altered significantly; the maximal relaxation caused by beta-sympathomimetic drugs either at 25 degrees or at 42 degrees C did not differ from one another; (2) the affinities of histamine, phenylephrine and of the beta-sympathomimetic drugs isoprenaline, fenoterol, terbutaline, and salbutamol each were comparable at either 25 degrees or 42 degrees C; the rank order of efficacy of the beta-sympathomimetic drugs is isoprenaline greater than fenoterol greater than salbutamol greater than terbutaline; (3) a decrease of the pH from 7.37 to 7.15 diminished the affinities of histamine and of the beta sympathomimetic drugs whereas that of the alpha-adrenergic drug phenylephrine was not altered. A further decrease of the pH to 6.8 diminished additionally the affinity of histamine and of isoprenaline, and especially that of the other beta-sympathomimetic drugs to such an extent that in the latter case complete dose-response curves could not be determined any more; (4) pretreatment of the animals with 0.4 mg/kg of triiodothyronine (T3) for two days, which strongly depressed the tension induced by either histamine or phenylephrine, did not alter the affinity of both drugs; T3 in vitro (10(-6) M) only diminished the affinity of histamine but left that of phenylephrine unaltered; pretreatment for two days with 0.2 mg/kg of T3 yielded a significant diminution of the pD2-values for two beta-sympathomimetic drugs investigated, namely isoprenaline and fenoterol; also the administration of T3 in vitro in a final concentration of 10(-6) M resulted in a diminution of the affinity of both beta-sympathomimetic drugs; (5) the results obtained show that also on the aorta beta-adrenoceptor stimulants are dependent on the metabolic state while alpha-adrenoceptor stimulants are not.

Adrenergic beta-Agonists↗
PubMed1975

Hepatitis B core antigen. Detection of antibody by radioimmunoprecipitation.

Radioactive cores were prepared from concentrated Dane particles by DNA polymerase reaction followed by CsCl density gradient centrifugation. Two radioactive peaks were obtained: one peak with an average density of 1.36 g/cm-3 in CsCl contained cores that possessed full serologic reactivity; the other peak, with a density of 1.28 to 1.32 g/cm-3, contained cores associated with globulin. A double antibody immunoprecipitation test was developed, using the radioactive heavy cores as a source of antigen. The test was at least 300 times as sensitive as complement fixation for detecting antibody to core.

Animals↗