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Biomedical subjects

M Bachmann

Publications and source records attributed to M Bachmann.

At least 163 records · Page 9Linked to original sources
PubMed1983

Potentiation of the cytostatic effect of bleomycin on L5178y mouse lymphoma cells by pepleomycin.

Bleomycin (BLM) and pepleomycin (PEP) are two chemically related glycopeptide antitumor antibiotics which differ in their terminal residues only. Studying the growth-inhibitory potencies of BLM (clinical mixture), BLM-A2, BLM-B2 and PEP in the L5178y mouse lymphoma cell culture system, it was elucidated that the slopes of the dose-response curves at the ED50 concentration (around 1 microgram/ml) were steeper for PEP than for BLM. This result together with cytotoxicity determinations revealed a cytostatic action of PEP within a closer concentration range than BLM. Both drugs inhibit cell proliferation during S- and G2-phase. Given in combination, BLM and PEP inhibit cell proliferation in a highly significant synergistic way (FIC indexes: 0.25-0.46). This in vitro result, which might be of therapeutic importance, is correlated with differences on the molecular level. Determinations of the ratio between the number of single- and double-strand breaks in the DNA (the target molecule of the drugs) revealed a considerably lower value for DNA from BLM-treated cells (1.9:1) than for DNA from PEP-treated cells (13:1).

Animals↗
PubMed1983

Partial purification and properties of a chromatin bound endonuclease from the marine sponge Geodia cydonium.

A chromatin bound endonuclease (Mr:107,000) has been extracted and partially purified from the siliceous sponge Geodia cydonium. Disc gel electrophoresis showed that only one enzyme was present in the partially purified preparation which was able to degrade DNA and poly(A). The enzyme liberates oligonucleotides on incubation with poly(A), which are further degraded to yield the 5'-mononucleotide, which has a pI of 6.5 and a pH optimum of 7.5-8.0. Cations are not required for enzymic activity and EDTA does not inhibit the enzyme. Only iodosobenzoic acid was found to completely inhibit the enzyme. The enzyme hydrolysed poly(A), poly(U), poly(C), DNA, poly[d(A-T)], poly[d(G-C)], but not poly (dA) or poly(G).

Animals↗
PubMed1983

Chromatin structure from the marine sponge Geodia cydonium.

The histones isolated from the siliceous sponge Geodia cydonium have been separated using two electrophoretic techniques. A comparison of their mobilities with those of calf thymus and rat liver show that some Geodia histone species (H3, H1 and H1(0) exhibit electrophoretic variance. The results show, that as in other eukaryotic systems the sponge chromatin contains the core histones (H2A, H2B, H3 and H4) and the linker histone (H1). ADP-ribosylation of Geodia histones and separation of the individual histones by electrophoresis resulted in four histones being radiolabeled. Digestion of Geodia chromatin with endogenous endonuclease is shown to result in the formation of nucleosome particles containing approximately 200 base pairs of DNA. A major product of endogenous endonuclease digestion is a relatively stable 110 base pair intermediate. Incubation of chromatin with DNase II and separation of the products under denaturing conditions reveals 20 bands migrating at 10 base intervals.

Adenosine Diphosphate Ribose↗
PubMed1983

[Studying pulmonary mechanics in intensive care].

Assessing pulmonary function in critically ill patients is difficult, mainly because of lack of cooperation, artificial ventilation and jeopardized vital functions. We describe bedside methods and mobile equipment used to measure lung volumes, static pulmonary and thoracic compliance. The analysis of single and multiple-breath nitrogen washout curves allows an estimation of closing volume and an assessment of the inhomogeneity of ventilation. The use of a microcomputer facilitates recording, calculation, reproduction and classification of the data; it also permits the collection of more information in a shorter time, allowing the adjustment of mechanical ventilation to the underlying pulmonary disease.

Critical Care↗
PubMed1983

Respiratory depressant effects of different doses of midazolam and lack of reversal with naloxone--a double-blind randomized study.

Conflicting data concerning the ventilatory effects of benzodiazepines may be caused by the large variability in investigational conditions. Respiratory effects of three different intravenous doses of midazolam (0.05 mg/kg, 0.1 mg/kg, 0.2 mg/kg) and placebo were measured in a double-blind and randomized fashion in eight healthy volunteers. The respiratory variables were analyzed by means of a noninvasive method, thereby avoiding interferences associated with the stimulating effects of mouthpiece and nose clip. After injection of midazolam, tidal volume decreased by 40% with the three doses and respiratory frequency increased to the same extent, minute ventilation remained constant. Only the largest dose of the drug produced a significant decrease (P less than 0.05) in O2 saturation that was related to the longer duration of apnea. Intravenous naloxone (0.015 mg/kg) injected 5 min after midazolam did not change any measured respiratory or hemodynamic variable. We conclude that the respiratory effects of midazolam are poorly dose related and not reversed by naloxone. The observed compensatory increase in respiratory frequency which is not noted in other studies, is probably related to the noninvasive measurement technique used.

Adult↗
PubMed1982

Isolation and partial characterization of a toxin from the venom of the East African orthognath spider Pterinochilus spec.

A minor basic polypeptide in the venom of the East African orthognath spider Pterinochilus spec. was the most toxic of 16 basic components in this venom. This toxin A4/4 was purified by gel permeation on Sephadex G-50 and ion exchange chromatography on CM-Sephadex C-25 with a yield of 1.3% of the total protein content of the crude venom. The polypeptide has an isoelectric point of 9.39 and molecular weight of 10,500. The s.c. LD50 in mice is 0.1 mg/kg. Death occurred due to respiratory paralysis. After administration of sublethal doses rapid reversibility of the symptoms and total recovery of the animals was observed.

Amino Acids↗
PubMed1981

Metabolism of [14C]emodin in the rat.

1. Absorption, excretion, tissue distribution and metabolism of the anthraquinone [14C]emodin was studied after a single oral administration (approx. 50 mg/kg) to rats. 2. Urinary excretion amounted to 18(+/- 5)% dose in 24 h and to 22(+/- 6)% in 72 h. 3. Metabolites found in pooled urine (0-72 h) were mostly free anthraquinones (emodin and emodic acid, 16% dose); 3% was conjugated and 3% was non-extractable radioactivity. 4. In 24 h, 48 +/- 11% and in 120 h, 68 +/- 8% dose was excreted in the faeces, mostly in the free anthraquinone form. 5. In two cannulated rats biliary excretion reached a maximum at approx. 6 h and amounted to 49% dose within 15 h; 70% of biliary activity was in the form of conjugated emodin. 6. The content of radioactivity in most organs decreased significantly between 3 and 5 days. In kidneys, however, the 14C activity was still equiv. to 4.33 p.p.m. emodin after five days. Mesenterium and fat tissue showed increasing 14C activity from 72 to 120 h.

Animals↗
PubMed1980

[Mimicking of mitral stenosis by asymmetrical hypertrophic cardiomyopathy].

Pressure gradients between atrium and left ventricle were measured in 5 of 17 patients with the diagnosis of hypertrophic cardiomyopathy. The diagnosis was confirmed by echocardiography and angiography. In 2 patients the hypertrophic cardiomyopathy was obstructive for the left ventricular outflow tract. Mitral stenosis was suspected in 3 out of the 5 patients who presented atrial fibrillation or frequent premature atrial beats and atrial overload phenomena of a third heart sound (which was misinterpreted as mitral opening snap) together with radiological enlargement of left atrium. Cardiac catheterization revealed middle pressure gradients between 7 and 14 mm Hg over mitral valve in 3 patients. In 2 patients significant early and middiastolic pressure gradients were recorded only after left ventricular angiography (volume load) was performed. Based on the data from cardiac catheterization, mitral stenosis was diagnosed in one patient, surgery revealed normal mitral leaflets. Echocardiography showed normally mobile mitral leaflets as well as signs of interventricular septal hypertrophy in all 5 patients. (In the patient who underwent surgery echocardiography was performed after the operation.) There were no echocardiographic signs of left ventricular inflow obstruction. The pathophysiologic mechanism of myocardial hypertrophy mimicking mitral stenosis is unknown. It may be suspected that third heart sound, diastolic murmur and the left ventricular inflow obstruction apparent from the pressure gradient are due to diminished myocardial compliance, direct mechanical effects of septal hypertrophy and decreased mobility of anterior mitral leaflet. Mimicking of mitral stenosis exists. Hypertrophic cardiomyopathy should therefore be considered in the differential diagnosis of mitral stenosis. Echocardiography may be helpful in evaluation.

Adult↗
PubMed1980

Purification and Partial Characterization of an Aminopeptidase from Lactobacillus lactis.

A surface-bound aminopeptidase of Lactobacillus lactis cells was solubilized with lysozyme, and the extract was subjected to streptomycin sulfate precipitation, ammonium sulfate fractionation, chromatography on Sephadex G-100 and diethylaminoethyl-Sephadex A-50, and preparative polyacrylamide gel electrophoresis. The purified enzyme was homogeneous in disc electrophoretic analysis and consisted of a single polypeptide chain with a molecular weight of 78,000 to 81,000. The optimal pH and optimal temperature for enzyme activity were 6.2 to 7.2 and 47.5 degrees C, respectively, for l-lysine-4-nitroanilide as the substrate. The enzyme was activated by Co and Zn ions and inhibited by Cu, Hg, and Fe ions and by the metal-complexing reagents ethylenediaminetetraacetic acid, 1,10-phenanthroline, and alpha,alpha'-dipyridyl. Higher concentrations of substrate and hydrolysis products also inhibited the activity of the enzyme. The aminopeptidase had broad substrate specificity and hydrolyzed many amino acid arylamides and many peptides with unsubstituted NH(2)-terminal amino acids.

Journal Article↗
PubMed1980

Papilloma of the bronchus.

Based on the observation of a recurring bronchial papilloma in a 56-year-old male, the authors aim at directing the interest of pneumologists, and especially endoscopists, to this group of rare lesions. The tumor observed obviously developed in a lung lobe affected by chronic tuberculosis, and presented with luminal obstruction. The histopathological definition of solitary papilloma, its differential diagnosis from from papillomatosis, the probable dignity of this type of lesions and the clinical features are discussed.

Bronchial Neoplasms↗
PubMed1979

[Atenolol in the treatment of angina pectoris].

18 patients with angina pectoris participated in a double blind trial with atenolol (100 mg and 200 mg once daily, or 100 mg twice daily) and propranolol (80 mg twice daily). The number of anginal attacks (NAP), the number of days free of pain (NAFT), consumption of sublingual nitroglycerin (NNT) and bicycle ergometry data (EFE) were recorded. Atenolol given in a dose of 100 g twice daily significantly reduced NAP and NNT as compared with the other dose schedules for atenolol and propranolol. There was, however, no difference between NAFT and EFE under any of the treatment schedules mentioned above. Only with 100 mg atenolol twice daily was it possible to reduce heart rate at rest and immediately after exercise testing, and also diastolic blood pressure (at rest, upright and after stress testing). In spite of the long plasma T 1/2 (= 24 hours) reported by others, atenolol given twice daily seems to be the most effective schedule. It is concluded that atenolol (100 mg twice daily) has a more potent anti-anginal effect than propranolol (80 mg twice daily). In addition, atenolol has the advantage of being cardioselective.

Aged↗
PubMed1979

[Formation of chondroid tissue in the left ventricle and bundle of His in complex congenital cardiac abnormality (author's transl)].

The formation of chondroid tissue in the heart ventricles and in the region of the ventriculoatrial transition is regarded as a rare lesion of the human heart. We present the observation of a not well-known disorder of cardiac development connected with a cartilagineous transformation of endo- and myocardial tissue. Chondroid change was found in the innermost parts of the left ventricle in a heart with severe hypoplasia of left parts and aortic atresia. Cartilage-like tissue reached to the region of the bundle of His and to supraanular parts of the interatrial septum. The possible genesis of this change, that may be of clinical relevance, is discussed with regard to normal endo- and myocardial development.

Autopsy↗