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Biomedical subjects

R Steiner

Publications and source records attributed to R Steiner.

At least 127 records · Page 7Linked to original sources
PubMed1986

Size and shape of the multicatalytic proteinase from rat skeletal muscle.

The multicatalytic proteinase from rat skeletal muscle, a non-lysosomal high molecular weight enzyme active at neutral to alkaline pH, has been examined in the electron microscope as well as by dynamic laser light scattering. Both methods reveal monodisperse particles. Electron micrographs show a cylinder-shaped complex with a diameter of 11 nm and a length of 16 nm in negatively stained, and a diameter of 9.6 nm and a length of 14.3 nm in freeze-dried, heavy metal replicated specimens. The molecule is composed of four rings or disks.

Animals↗
PubMed1985

[Accuracy of prenatal weight estimation using ultrasound in the case of birth weights less than 2000 grams].

In this study foetal weight as estimated by ultrasound was compared with the true birth weight of children having a birth weight of less than 2000 g (n = 105). The estimation of foetal weight was achieved using the authors' own diagram containing a curve for the biparietal and the thoracal diameter as well as for the foetal weight. The data for the weight curve were taken from two European populations (Bonn and Winterthur). There was a highly significant correlation between the ultrasonically estimated foetal weight and the true birth weight. Only in the group less than 1200 g a significant overestimation of foetal weight could be shown by using the weight curve of the population of Bonn, whereas the percentage deviation of both weight curves was comparable: when using the curve of Bonn 68% of readings had a deviation of less than 10%, whereas with the curve of Winterthur this was the case for 65% of the readings.

Embryonic and Fetal Development↗
PubMed1985

Clinical evaluation of semiautomatic blood pressure devices for self-recording.

Sixteen semiautomatic blood pressure devices for self-recording were compared with a Hawksley random zero sphygmomanometer using three criteria for determination of accuracy: correlation analysis; mean differences; standard deviation of mean differences. Only one of the tested instruments showed excellent results, but three other devices had satisfactory accuracy of blood pressure recording. These devices could be recommended for self-recording by patients. Only minor differences were found between the devices as regards reliability and convenience in use.

Blood Pressure Determination↗
PubMed1983

Drug-induced surface potential changes of lipid vesicles and the role of calcium.

The effects of four different drugs with local anesthetic properties were investigated on the surface potential of phospholipid vesicles composed of electrostatically neutral lipids (phosphatidylcholine), negatively charged lipids (phosphatidylserine) and a mixture of acidic and neutral lipids (soy bean lipids). Propranolol, tetracaine, lidocaine and procaine decrease the negative surface potential of phosphatidylserine and soy bean liposomes and increase that of phosphatidylcholine liposomes. The drugs interact with the liposomes in such a way that the protonated amine groups point towards the polar head groups of the phospholipids and the rest of the molecule is probably incorporated into the hydrophobic core of the lipid bilayer. The same sequence in drug activity normally measured in biological tissues (propranolol greater than tetracaine greater than lidocaine greater than procaine) is found for the surface potential change of the phospholipids. Calcium prevents the binding of the drugs to phosphatidylserine, especially the binding of lidocaine and procaine. Because of its high affinity for negative surface charges, Ca2+ chelates with phosphatidylserine and blocks the incorporation of the drug molecule. Vice versa, when incorporated into the liposomal bilayer, the drug blocks the interaction of calcium. These antagonistic effects are only observed in liposomes made from acidic phospholipids and not in those made from pure electrostatically neutral lipids like phosphatidylcholine.

Anesthetics, Local↗
PubMed1983

Effect of pH and different substrates on the electrokinetic properties of (Na+, K+)-ATPase vesicles.

Some biophysical properties of a (Na+, K+)-ATPase preparation from guinea-pig kidney have been analysed. The recently developed technique of laser Doppler spectroscopy was applied to measure particle mobility under electrophoretic conditions. The following results were obtained: 1. magnesium ions at pH 7.3 decrease the mobility of the ATPase containing vesicles by binding to negatively charged surface groups. At pH 3.3 the competitive binding of protons causes a shift of the mobility vs. [Mg2+] curve to higher values of [Mg2+], 2. binding of ATP at pH 7.3 (Kd = 0.9 X 10(-4) M for (mM 1 NaCl, 0.2 KCl, 0.1 MgCl2, 0.1 Tris) was measured as an increase in particle mobility depending also on [Mg2+]. At pH 3.3 also unspecific ATP-binding occurred, 3. ITP and GTP had the same Kd value as ATP; ADP a slightly lower one (Kd = 1.2 X 10(-4) M). Tris-H3PO4 (Kd = 2.6 X 10(-4) M) was also able to increase particle mobility, but only at higher concentrations and not to the same extent as ATP; AMP induced only very small changes, 4. from the mobility-pH curve an isoelectric point of 4.1 is derived (buffer: 1 mM NaCl, 0.2 mM KCl, 0.1 mM MgCl2, 0.1 mM Tris). In the presence of 0.9 mM ATP the isoelectric point is shifted to 3.2. As the electrophoretic mobility is directly proportional to the net charge of the vesicles, the results may be interpreted as changes in surface charge density, originating from both a conformational change of the ATPase polypeptide and a decrease in vesicle size.

Adenosine Triphosphate↗
PubMed1983

The effect of different surface chemical groups on drug binding to liposomes.

The binding of four secondary and tertiary amine drugs with local anesthetic activity (propranolol, tetracaine, lidocaine, procaine) to liposomes containing charged surface groups of different chemical composition has been investigated. Binding is determined by measurement of partition coefficients and of drug induced zeta potential changes of the liposomes. For propranolol 30% of the total amount of drug dissolved in phosphatidylcholine is located as protonated form in the liposome surface. Fifty percent of tetracaine and 13% of procaine contribute to the surface charges. Negative surface charges (phosphatidylserine) facilitate drug binding and drug protonization in the liposome surface. Positive surface charges (hexadecyltrimethylammonium) prevent the protonization of the drugs. Different chemical groups of single negatively charged phospholipids or of electrostatically neutral lipids have no significant effect on drug binding which proves that binding is not influenced by steric and bulky head group configurations. The drugs interact hydrophobically with the lipid phase in such a way that the drug amine protonizes in the presence of the negatively charged phosphate oxygen of the phospholipid. Hexadecanoic acid is located deeper within the liposome surface than other negatively charged phospholipids. Correspondingly the drug action is weaker and drug protonization is prevented.

Anesthetics, Local↗
PubMed1983

Adriamycin alone or combined with vincristine in the treatment of advanced breast cancer.

One hundred and nineteen women with advanced breast cancer treated previously by endocrine therapy but no prior chemotherapy were given adriamycin 70 mg/m2 i.v. on day 1 of a 3-weekly cycle for 8 courses, followed by a regimen of cyclophosphamide, methotrexate and 5-fluorouracil (CMF) until relapse. They were allocated randomly to receive either no treatment (group A) or vincristine 1.4 mg/m2 i.v. on days 1 and 8 during treatment with adriamycin (group AV). In 107 evaluable patients objective responses were seen in 30/53 patients (57%) in group A and in 28/54 patients (52%) in group AV. The projected dose of adriamycin received was 78% in group A and 75% in group AV; and 60% for vincristine in group AV. The subjective and haematological toxicity for adriamycin was similar in both groups, but 65% of patients treated with vincristine developed neurotoxicity. The median duration of objective regressions was the same for both groups (7 months), and the median time to failure was 5 months for group A and 6 months for group AV respectively. The median survival of the responders tended to be longer in group AV (17.5 months) than in group A (13 months), but this difference was not statistically significant (P = 0.112). It is concluded that there is no advantage therapeutically in combining vincristine and adriamycin in patients with advanced breast cancer.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1983

Results of endocrine therapy do not predict response to chemotherapy in advanced breast cancer.

One hundred and four patients with advanced breast cancer treated with adriamycin +/- vincristine had had prior endocrine therapy. Of 28 responders to prior endocrine therapy a response to subsequent chemotherapy occurred in 15 (54%); the response frequency in the 76 non-responders to endocrine therapy was 51% (39 patients). The median time to treatment failure was not significantly different between responders to prior endocrine treatment and non-responders (7 months vs 5 months; P = 0.136). Although the median survival from starting chemotherapy tended to be longer in the endocrine responders (18 months) than in the non-responders (12 months), there was no significant difference between the two groups (chi = 2.749; P = 0.097). In a subgroup of 31 non-responders to endocrine therapy who had had stable disease (greater than or equal to 6 months) the median time to treatment failure was 6 months and median survival 13 months. This lack of differences existed for each subgroup of endocrine therapy. Response to prior endocrine treatment was not shown to be a determinant of response to subsequent chemotherapy.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1982

Contribution of prednisolone to the primary endocrine treatment of advanced breast cancer.

Two hundred and four patients with progressive locally advanced or metastatic breast cancer not controllable by local therapy alone, and who had had no prior systemic therapy for advanced disease, were treated by primary endocrine therapy according to menopausal status. Premenopausal patients received ovarian irradiation (O) whilst postmenopausal patients received tamoxifen 10 mg b.d. (T). Patients were randomised to receive either no additional treatment or prednisolone 5 mg b.d. (P). In 180 evaluable patients, T + P induced significantly more responses than T alone (26/73 vs 9/72, P less than 0.01) and the addition of P to O in premenopausal patients also induced more responses than O alone (7/16 vs 4/19), but this difference was not significant and accrual of premenopausal patients continues. There was a trend for patients receiving T + P to have a longer survival than those receiving T alone (median 25 vs 16 months). These trends occurred in patients with tumours positive for oestrogen receptors and when receptor status was unknown; patients with receptor-negative tumours had a negligible response to endocrine treatment. P mitigated the occurrence of hypercalcaemia and tumour flare sometimes seen with T alone.

Adult↗
PubMed1981

Cell electrophoresis for diagnostic purposes. I. Diagnostic value of the electrophoretic mobility test (EMT) for the detection of gynaecological malignancies.

Lymphocytes from 278 gynaecological patients (100 controls and 178 patients with a malignant condition) have been investigated for their response to encephalitogenic factor, cancer basic protein, and KCl extract of adenocarcinoma of the body of the uterus as "antigens", using tanned sheep erythrocytes ETS as indicator particles in the electrophoretic mobility test (EMT). Electrophoretic mobility was measured with a Zeiss cytopherometer. The study was split into three test series producing in the cancer group 66% correct positive test results (34% false negatives) and in the control group 83% correct negative results (17% false positives). Consequently, with the instrumentation used, EMT is, at least in our hands, not sufficiently reliable for the diagnosis of cancer.

Adenocarcinoma↗
PubMed1981

Cell electrophoresis for diagnostic purposes. II. Critical evaluation of conventional cytopherometry.

Determination of the electrophoretic mobility of test cells has been widely used in an attempt to detect so-called lymphokines in a laboratory test for cancer, but operational difficulties are inherent in conventional cytopherometers. This study therefore investigates the technical and operational aspects of cell electrophoresis, using the Zeiss cytopherometer; e.g. influence of electro-osmosis, focus uncertainty, movement due to convection and other sources of error. Implications and possible improvements in the test are discussed.

Cell Movement↗