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Biomedical subjects

M Michalik

Publications and source records attributed to M Michalik.

At least 55 records · Page 3Linked to original sources
PubMed1988

Restricted amino acid nutrition induces attachment to glass and spreading of Ehrlich ascites tumour cells.

Ehrlich ascites tumour (EAT) cells were cultured in vitro in Eagle's MEM and Medium 199 with a lowered amino-acid content. Under these conditions EAT cells lose their rounded shape typical of highly malignant cancer cells, and begin to spread on the substratum. The changes in EAT cell morphology are preceded by a decrease in the rate of protein synthesis. These changes were maintained for three days after returning the cells to Eagle's MEM with a normal amino-acid content, but the return to control media did not cause reasumption of growth in the once spread cells. The increase in glucose content (up to five-fold) or the presence of inhibitors of DNA synthesis did not prevent the attachment and flattening of EAT cells in media with a lowered amino acid content. Several possible mechanisms of the influence of restricted amino-acid availability on the changes in EAT cell surface properties are pointed out and the need for study of cancer cell responses to restricted nutrition is discussed.

Amino Acids↗
PubMed1988

[Pathophysiologic aspects of conservative therapy of post-traumatic cerebrovascular disorders of the microcirculation].

In order to avoid or diminish secondary cerebral damage in the treatment of the craniocerebral trauma the removal of disturbances of the microcirculation is of decisive importance to the course of the disease and the prognosis. The microcirculation is essentially determined by rheological factors such as haematocrit, plasma viscosity, aggregation and fluidity of erythrocytes. Rheological aspects should be included to a greater extent than has been done until now in the basic therapy of traumatic cerebral blood supply disturbances. If this is not done, an important therapeutic reserve is not made use of. In our opinion isovolaemic haemodilution is a practical method. The application of cerebroselective calcium antagonists appears to be reasonable as well.

Brain Concussion↗
PubMed1987

Inhibitory effect of gentamicin on gluconeogenesis from pyruvate, propionate, and lactate in isolated rabbit kidney-cortex tubules.

The effect of gentamicin on glucose production in isolated rabbit renal tubules was studied with lactate, propionate, malate, 2-oxoglutarate, and succinate as substrates. This antibiotic at 5 mM concentration inhibited gluconeogenesis from lactate by about 60% and that from either pyruvate or propionate by about 30%. In contrast, it did not alter the rate of glucose formation from other substrates studied. The rate of gluconeogenesis was higher at 1 mM propionate than at increasing concentrations of this substrate and was stimulated in the presence of 1 mM carnitine. However, the addition of carnitine did not affect the degree of inhibition of glucose formation by gentamicin. Since the mitochondrial free coenzyme A level was significantly lower in the presence of 10 than 1 mM propionate and increased on the addition of carnitine to the reaction medium, the inhibitory effect of propionate concentrations above 1 mM on gluconeogenesis in rabbit renal tubules may be due to a depletion of the free mitochondrial coenzyme A level, resulting in an inhibition of the mitochondrial coenzyme A-dependent reactions. In intact rabbit kidney cortex mitochondria incubated in State 4 as well as in Triton X-100-treated mitochondria, 5 mM gentamicin inhibited by about 30-40% the incorporation of 14CO2 into both pyruvate and propionate. The results indicate that the inhibitory effect of gentamicin on glucose formation in isolated kidney tubules incubated with lactate, pyruvate, or propionate is likely due to a decrease of the rate of carboxylation reactions.

Animals↗
PubMed1987

[Spectral analyses in ocular microtremor in disorders of brain stem function].

In 61 healthy and 79 patients the small involuntary movements were recorded using a piezoelecric strain gauge transducer mounted on a modified optical frame. The recording was followed by a spectralanalytic process with special programs. We used a detailed neurological examination for estimating the clinical condition of the patients. The spectral analysis of the ocular microtremor supplies results which correspond to the clinical condition in each case of the patients with increased central herniation. A irreversible loss of cerebral function (brain death) can also be documented. Patients with special clinical syndromes show tremograms which answer the probably extent of damage of (meso-)pontine parts. We investigated and discussed effects of the influence of central-nervous drugs, age-dependent relations, the significance of cardiovascular pulsations and questions and questions of the comparability of findings between both bulbi. The ocular microtremor shows burst-like components with a frequency peak between 60 and 90 oscillations per second. At present must be assessed that it could be a potential monitor of the function of the reticular (meso-)pontine formation.

Brain Death↗
PubMed1987

[Computerized tomography and infusion test as a simultaneous study method in post-traumatic hydrocephalus].

The cerebral compression of a patient with posttraumatic hydrocephalus was measured intraventricularly, and an intrathecas infusion test was made simultaneously with computed tomography. Substractive computed tomography pictures show that continuously increasing volume does not imply uniform enlargement of the ventricular system, the cornua of the lateral ventricles in particular exhibiting a frontal increase in size.

Adult↗
PubMed1986

Enzyme-linked immunosorbent assay (ELISA) for the detection and differentiation of Clostridium botulinum toxins type A and B.

Affinity chromatography has been used for a two-step purification of commercial horse botulinum antitoxic globulins type A and B. The first step performed using CH-Sepharose 4B conjugated to toxin type A (or B), permitted the removal of non-botulinal antibodies from antitoxic globulin type A (or B). The anti-botulinal antibodies obtained from the first step were cross-absorbed in the second affinity chromatography using CH-Sepharose 4B conjugated to toxin B (for the purification of antibodies to type A) or to toxin A (for antibodies to type B). The antibodies obtained were used to coat polystyrene wells in an ELISA for the detection of botulinum toxin type A and type B. The first purification step increases the sensitivity of such an ELISA whereas the second step improved the specificity of the test. Only slight cross-reactions were observed between the type A and type B detection systems. The sensitivity achieved with ELISA was 100 and 300 DLM (dosis lethalis minima) for type A and B respectively.

Botulinum Toxins↗
PubMed1986

Substrate-dependent effect of 1-34 human parathyroid hormone fragment, dibutyryl cAMP and cAMP on gluconeogenesis in rabbit renal tubules.

In the presence of 0.5 mM extracellular Ca2+ concentration both 1-34 human parathyroid hormone fragment (0.5 micrograms/ml) as well as 0.1 mM dibutyryl cAMP stimulated gluconeogenesis from lactate in renal tubules isolated from fed rabbits. However, these two compounds did not affect glucose synthesis from pyruvate as substrate. When 2.5 mM Ca2+ was present the stimulatory effect of the hormone fragment on gluconeogenesis from lactate was not detected but dibutyryl cAMP increased markedly the rate of glucose formation from lactate, dihydroxyacetone and glutamate, and inhibited this process from pyruvate and malate. Moreover, dibutyryl cAMP was ineffective in the presence of either 2-oxoglutarate or fructose as substrate. Similar changes in glucose formation were caused by 0.1 mM cAMP. As concluded from the 'crossover' plot the stimulatory effect of dibutyryl cAMP on glucose formation from lactate may result from an acceleration of pyruvate carboxylation due to an increase of intramitochondrial acetyl-CoA, while an inhibition by this compound of gluconeogenesis from pyruvate is likely due to an elevation of mitochondrial NADH/NAD+ ratio, resulting in a decrease of generation of oxaloacetate, the substrate of phosphoenolpyruvate carboxykinase. Dibutyryl cAMP decreased the conversion of fracture 1,6-bisphosphate to fructose 6-phosphate in the presence of both substrates which may be secondary to an inhibition of fructose 1,6-bisphosphatase.

Animals↗
PubMed1986

Determination of soluble antigens of Clostridium botulinum A by chemiluminescent--immunosorbent assay (CLISA).

The chemiluminescent--immunosorbent assay (CLISA) was adopted for Cl. botulinum A soluble toxic antigens determination. Luminol (ABEI) labelled botulinum antitoxin globulins showed a strongly positive specific immunochemiluminescent reactions with the native botulinum toxin preparations coupled (adsorbed) on polystyrene balls. The sensitivity of the reaction reached 20 DLM/ml (5,000 light impulses per 40 sec) in comparison with 2 X 10(6) DLM (57,000 impulses), control preparations (1,500 impulses) and the background (150-300 impulses). The results give a perspective further investigations with the CLISA for rapid indication of Cl. botulinum toxic antigens.

Antigens, Bacterial↗
PubMed1985

Density-dependent survival of Ehrlich ascites tumour cells in the presence of various substrates for energy metabolism.

We have found that Ehrlich ascites tumour (EAT) cells, deprived of any carbon source, and suspended at a density of 2 X 10(5) cells/cm3, begin to die only after 12 h of starvation, though it is known that under these conditions they lose over 80% of their ATP within 30 min. Moreover, we have found that the viability of the cells incubated in the absence of any substrate for energy metabolism is strongly dependent on the density of the cell suspension, and can be significantly improved simply by increasing the suspension density. This prompted us to investigate the density dependence of the maintenance of EAT cell viability in the presence of various substrates for energy metabolism and metabolic intermediates. It was found that: Glucose ensures 48 h viability of EAT cells irrespective of suspension density. Fatty acids and pyruvate as sole carbon source do not improve EAT cell survival. In the presence of glutamine as sole carbon source the EAT cell survival shows dependence on cell-suspension density. At densities of 1.6 X 10(6) to 3.2 X 10(6) cells/cm3 the cell viability is maintained at least as well as in the presence of glucose, but at low cell-suspension densities glutamine does not support cell viability. In the presence of glutamine, addition of 1 mM-inosine and 1 mM-uridine ensures high cell survival irrespective of the cell-suspension density. In the presence of inosine or uridine (10 mM) as sole carbon source, the EAT cell survival is the same as in the presence of glucose and does not depend upon cell-suspension density. Guanosine is less effective, whereas adenosine has no effect at all on the maintenance of EAT cell viability for 48 h. There is no correlation at all between EAT cell survival and the rate of lactic acid production. At a cell-suspension density of 1.6 X 10(6) cells/cm3 the cell survival is of the same order in the presence of glutamine as in the presence of glucose, in spite of the fact that in the first case the rate of lactic acid production is more than 20 times lower. There is no correlation between the capacity of particular nucleosides to support EAT cell survival and their effects on glycolysis and oxygen consumption.

Animals↗
PubMed1984

[Standardized monitoring of brain function].

A form is described for recording the results obtained when monitoring the brain function in cases of severe acute brain damage. The form follows the principles introduced in other countries for recording the results of similar standard examinations, but the symptoms and scalings have been modified to suit the author's requirements. The state consciousness as shown by the opening of the eyes, verbal response and motor reactions to various stimuli is considered essential for the continuous monitoring of the brain function, as are also the dilation of the pupile and their response to light and the vestibuloocular reaction. The form also contains entries for respiration, blood pressure, heart rate and body temperature. The neurological symptoms have been selected on the basis of their diagnostic value, consistency and simplicity of examination and interpretation. The advantages of a standard examination scheme are explained. Advice is given regarding the examination of the different symptoms.

Brain Damage, Chronic↗