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Biomedical subjects

R Steiner

Publications and source records attributed to R Steiner.

At least 145 records · Page 8Linked to original sources
PubMed1981

Patterns of disturbed myocardial perfusion in patients with coronary artery disease. Regional myocardial perfusion in angina pectoris.

Fifty patients who presented with angina pectoris were studied to examine the disturbances of regional myocardial perfusion during stress. Each patient underwent 16-point precordial mapping of the ECG during an exercise test, and coronary and left ventricular angiography. Regional myocardial perfusion was assessed using an atrial pacing test and a short-lived radionuclide, krypton-81m. Eleven patients had negative exercise tests and uniform increases in myocardial activity of krypton-81m of 98 +/- 18.0% during pacing. Ten patients performed 30,000-43,000 J in positive exercise tests. These patients showed abnormal coronary anatomy and increases in myocardial activity of krypton-81m to remote and jeopardized myocardium at the onset of pacing. However, further pacing produced a decrease in activity in the affected segment of 68.0 +/- 9.0% accompanied by ST-segment depression and angina. Twelve patients achieved 26,000-32,000 J in positive exercise tests and had significant coronary artery disease. Atrial pacing produced increased activity of krypton-81m to remote myocardium. The jeopardized segment at first showed no change and then a decrease in regional activity of krypton-81m (89.0 +/- 17%) accompanied by ST-segment depression and chest pain. Seventeen patients achieved only 7000-22,000 J in positive exercise tests. These patients showed abnormal coronary anatomy and developed decreases in regional activity of krypton-81m to the affected segment of myocardium starting at the onset of atrial pacing and decreasing by 88 +/- 0 7.0% below control. We conclude that different patterns of disturbed myocardial distribution of krypton-81m are present during stress-induced ischemia in patients with coronary artery disease. There was a close temporal relationship between these disturbances and ST-segment depression.

Adult↗
PubMed1981

The influence of aromatic substitution on the negative inotropic action of verapamil in the isolated cat papillary muscle.

The influence of ring substitution on the negative-inotropic action of the Ca-antagonist verapamil (Isoptin) by means of qualitative and quantitative analyses of the structure-activity relationships has been investigated. The relative contribution of the two aromatic rings to the negative-inotropic potency of verapamil was tested. a) Ring substituents strongly influence the negative-inotropic potency (ED50 values from 7.9 x 10(-7) mol/l to 1.3 x 10(-4) mol/l). The character of the negative-inotropic effect typical for verapamil is not altered (except by very bulky substituents).

Animals↗
PubMed1980

[K (killer) and NK (natural killer) cells: characteristics, functions and biological properties (author's transl)].

Cell-mediated cytotoxicity is considered to be an important defence system of the body in the case of virus diseases, transplant rejection and in the early stages of cancer. Apart from T lymphocytes, two types of effector cells which lyse tissue culture cells by different mechanisms have been investigated intensively over the past decade--K (killer) and NK (natural killer) cells. K cells possess the capacity to lyse antibody-coated target cells. These effector cells have been described to occur mainly in peripheral blood and spleen. They are small lymphocyte-like cells which possess receptors for the Fc part of immunoglobulin G. Other surface markers may be present on these cells, depending on the organ of isolation. Other cytotoxic effector cells with similar morphology and surface markers possess the capacity to lyse tissue culture cells without participation of antibody and without in vitro or in vivo sensitization. These cells are called NK cells and are found in peripheral blood, spleen, tonsils and lymph nodes. Up to now neither type of effector cells has been unequivocably identified as mature B or T cells, granulocytes, monocytes or macrophages. Differences exist between the effector mechanisms of K and NK cells, as shown by different susceptibility to modulation of effector cell function by cortisone and, probably, by interferon. Whether K and NK cells represent functional stages of identical cells and furthermore, whether these cells belong to a third lymphocyte population or represent immature mononuclear cells are questions remaining to be clarified.

Animals↗
PubMed1980

Modulation of NK and K cell activity by trypsin treatment of effector cells.

The effect of trypsin-treated human peripheral blood lymphocytes on spontaneous cell-mediated cytotoxicity (SCMC) and antibody-dependent cellular cytotoxicity (ADCC) was investigated using benzylpenicilloyl (BPO)-coated HeLa cells as targets. For ADCC-experiments an anti-BPO-IgG was purified from rabbit hyperimmune sera by affinity and subsequent ion exchange chromatography and used in different concentrations. After treatment of lymphocytes with high enzyme concentrations (21,500 U/2 X 10(6) lymphocytes/ml) both SCMC (mediated by NK cells) and ADCC (mediated by K cells) were markedly reduced in 3 hours as well as 18 hours 51Cr-release assays. Since decrease of K cell activity in this kind of assay might be due to impairment of SCMC, the effect of trypsin treatment was reevaluated in an NK-free system using BPO-coated lymphocytes as target cells and lymphocytes from the same donor as effector cells. Once again, in this system the K-cell activity was significantly reduced. Chessboard titration resulted in either enhancement of depression of ADCC depending on the dose of enzyme and IgG concentrations. In addition it could be seen from these dose response studies with different IgG concentrations (10--10,000 ng/ml) and different proteolytic activities (170--21,500 U/2 X 10(6) lymphocytes/ml) that the use of high IgG concentrations and low proteolytic activities might simulate resistance of K cells to trypsin treatment. The data presented indicate that the IgG-mediated ADCC should no longer be designated as "trypsin-resistant".

Animals↗
PubMed1980

Cadiovascular complications of homozygous familial hypercholesterolaemia.

Seven patients with homozygous familial hypercholesterolaemia, two female and five male, aged 12 to 25 years, underwent clinical and angiographic assessment to define the associated cardiovascular abnormalities. Four patients had angina, two of whom also had syncope on exertion. All had an ejection systolic murmur but no ejection click and a loud aortic second sound. All but one had a systolic gradient between the left ventricle and aorta, ranging from 20 to 80 mmHg at the time of presentation. Angiography showed a characteristic narrowing of the aortic root in all and five of the seven patients had coronary ostial stenosis. One patient died after an aortocoronary bypass and aortic valvotomy and two others underwent aortocoronary bypass and aortic valve replacement, one of whom also died after operation. The survivor and three other patients are now undergoing regular plasma exchange and remain well. The seventh patient died suddenly before the latter form of treatment could be started. These findings confirm that premature, severe atheroma of the aortic valve and root is a characteristic feature of homozygous familial hypercholesterolaemia and carries a high mortality.

Adolescent↗
PubMed1979

[High-dose ifosfamide therapy: systemic use of a mucolytic agent for the reduction of urotoxicity].

Ifosfamid is an alkylating cytostatic agent which appears to differ in its clinical spectrum from the chemically similar cyclophosphamid. So far, however, its pronounced urotoxicity has limited dosage. In spite of prophylactic measures such as forced diuresis and alkalinization of the urine, the treatment has frequently has to be broken off because of macrohematuria and hemorrhagic cystitis. By repeated intravenous administration of sodium-mercapto-ethan-sulfonate (NNI: Mesnum) the urotoxic side effects of ifosfamid can largely be prevented. During 26 cycles of treatment in 18 patients, asymptomatic microhematuria was observed 6 times and macrohematuria only once in a patient with vesico-vaginal fistula. In another case where therapy had had to be discontinued because of hemorrhagic cystitis in spite of conventional prophylaxis, the treatment could be continued without change in the urine sediment under prophylaxis with Mesnum. Mesnum does not affect the antitumoral activity of ifosfamid.

Adult↗
PubMed1979

Krypton-81m in the physiologic assessment of coronary arterial stenosis in man.

Fifteen patients with frequent anginal chest pain underwent diagnostic cardiac catheterization. After coronary arteriography a specially designed cardiac catheter was seated in the aortic root, permitting the continuous infusion of krypton-81m into the right and left aortic sinuses. A gamma camera, areas of interest and a visual display unit were used to record images and the regional myocardial equilibrium of activity before, during and after a standarized atrial pacing test. The unique physical properties of krypton-81m allowed the continuous imaging and recording of moment to moment changes in regional myocardial perfusion. This investigation revealed that when the coronary arteriogram was normal or revealed lumonal stenosis of less than 50 percent, regional myocardial perfusion was uniform at rest and during stress. Two patients with a previous history of myocardial infarction had defects of regional perfusion at rest and during stress. Krypton scintigraphy demonstrated reversible regional defects in myocardial perfusion during stress in seven patients with greater than 70 percent stenosis of one or more coronary arteries. Alterations in regional myocardial perfusion occurred within 30 seconds of the start of atrial pacing in all the patients and preceded the onset of electrocardiographic signs of ischemia or chest pain.

Adult↗
PubMed1978

Investigations on the structure-activity relationships of verapamil.

An investigation was carried out towards a qualitative and quantitative structure-activity relationship of verapamil based on an analysis of the frequency-dependent negative inotropic action exerted in cat papillary muscles by various groups of verapamil derivatives. (1) Substituents of the benzene ring near the asymmetric carbon atom and the isopropyl group were found to be no essential substituents for the frequency-dependent negative inotropic action of verapamil but to have a strong influence on the potency of the drug. (2) Both the tertiary amino nitrogen and the two benzene rings are essential for the frequency-dependent negative inotropic action of verapamil (3) The molecular importance of the N-methyl group is probably based on steric effects. (4) Investigations of the verapamil derivative H 1 revealed that a quaternization of the drug is followed by a total loss of effectiveness. (5) No significant correlation of the biological activity of verapamil derivatives with the partition coefficient P has been obtained. (6) Hansch analysis with verapamil derivatives of group A (= different substitution of the benzene ring near C) shows that the variance of biological activity can be optimally correlated to a combination of the Hammett constant and the molar volume. Hansch analysis of group B (= exchange of isopropyl group) led to the conclusion that hydrophobic effects are responsible for the influence of the isopropyl substituent.

Animals↗
PubMed1978

[Clinical trial of bupivacaine-CO2 (author's transl)].

One hundred and forty-one patients for general and urological surgery were anaesthetized by epidural anesthesia (PDA) using bupivacaine-CO2 0.5% solutions. A frequency peak for the initial dose between 21-23 ml was noted. The response time and latency period were found to be 2.99 +/- 1.40 min and 11.02 +/- 3.66 min (smallest time unit 0.5 min). The effective duration was 5.02 +/- 0.93 h. The sensory spread reached on average to T 6.06 +/- 1.41 segments for the patients with typical injection locations at L2/3-L4/5. A mean dose of 6.25 +/- 0.18 mg per spinal segment was used. Side effects were not seen apart from occasional hypotension. The failures were not related to the anesthetic drug. The degree of muscle relaxation was for the majority of cases evaluated at 2 +, which was sufficient for the abdominal operations. The results are compared with the data obtained using bupivacaine-HC1; the advantages of bupivacaine-CO2 are described.

Adolescent↗
PubMed1978

[Experiences with hyperbaric bupivacaine solutions in spinal analgesia (author's transl)].

Spinalanaesthesia with hyperbaric bupivacaine (0.4%, 1.0%, 0.5%) was used in 713 patients having general surgical and urological operations. On average 19.30 +/- 1.55 mg bupivacaine was given and a spread of anaesthesia up to Th 7.21 +/- 1.55 achieved. Detailed evaluation of the 3rd group (0.5%) showed a latency period of 2.21 +/- 0.82 min and mean effective time of 4.33 +/- 0.75 h. The motor blockade was in 87% complete. The problem of the 0.5% solution with a specific gravity of 1.037 g/ml, which is in our opinion too high, was pointed out and a recommendation for a specific gravity of about 1.020 g/ml was given. Assuming proper positioning, spinal anesthesia with hyperbaric bupivacaine is a safe and simple anaesthetic method.

Anesthesia, Spinal↗
PubMed1977

[Concerning the casuistics by aspiration of waste oil sediments (author's transl)].

When cleaning an underground waste oil dump, an 18 year old worker suffered loss of consciousness by inhaling vapours of trichloroethylene and then suffocated by aspiration of waste oil sediments. Histological examination of the lungs proved the copious presence of partly granulous darkish-brown and of rather light coloured crystalloid foreign substances up to the multiple size of erythrocytes. "Chemical examination of blood, brain and urine showed the presence of trichloroethylene and its metabolites, respectively. The trichloroethylene concentration has been determined in the brain."

Adolescent↗