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Biomedical subjects

A Koller

Publications and source records attributed to A Koller.

At least 163 records · Page 9Linked to original sources
PubMed1987

Prognostic significance of agar and liquid cultures in AML patients before treatment, early postinduction and in remission.

In the present study, the growth and differentiation capacity of myeloid leukemic cells in agar and liquid cultures have been investigated in relation to their prognostic significance for treatment outcome and early detection of relapse. Prior to induction therapy, leukemic cells failed to differentiate and the colony or cluster number did not correlate with response to treatment. Seventeen to 42 days after induction, patients with BM cells producing greater than 10 colonies or greater than 30 clusters resp. had a high likelihood of achieving a complete remission. Cells from refractory patients had a significantly impaired differentiation capacity. During remission, a colony number greater than 50 was significantly associated with a high probability to remain in further remission for greater than 3 months. An impaired differentiation was significantly associated with the likelihood of relapsing within 3 months. In the light of these results, agar and liquid cultures appear to be useful for monitoring the effect of induction chemotherapy and detecting patients likely to relapse.

Agar↗
PubMed1987

Quantitative analysis of arteriolar network architecture in cat sartorius muscle.

The geometry of the arteriolar network is one of the major determinants of blood flow distribution within a tissue. The purpose of this study was to describe the distribution of geometrical variables (lengths, diameters) as well as the pattern of branching in the nonarcading portion of the arteriolar network in skeletal muscle. The exteriorized cat sartorius muscle was used as the experimental model. The intravascular fluorescence of fluorescein isothiocyanate (FITC)-labeled Dextran 150 was observed with a low-light-level video camera, and the vascular networks were mapped. Arteriolar lengths and diameters were measured, and vessel position in the network was characterized by Strahler's method of ordering, in which the first-order arterioles give rise to most of the capillaries. Typically, the nonarcading, terminal networks contain three or four arteriolar orders. The sequences of the number of vessels, mean diameter, and mean length for each order are accurately described by geometric progressions (Horton's law). The distribution of diameters within each order was rather narrow: typically two-thirds of the vessels fell within 20% of the mean value. The spread was reduced by half when vessels within a single network were considered. During vasodilation to a standard stimulus the relative dispersion of diameters increased modestly. The distribution of vessel lengths was broader than for diameters. Two-thirds of vessels of a single order fell within 50-75% of the mean. The spread was less within individual networks. The variability of vessel geometry and branching patterns was substantially less within a single network than for a population drawn from a group of networks.

Anatomy↗
PubMed1985

The effect of phenylalanine on intracellular pH and sodium activity in proximal convoluted tubule cells of the frog kidney.

The present study was performed to test the influence of sodium coupled transport of neutral substrates on intracellular pH and sodium activity in proximal tubules of the amphibian kidney. To this end, kidneys of rana esculenta have been isolated and perfused both through the portal vein (peritubular capillaries) and the aorta (luminal perfusate). The potential difference across the peritubular membrane of proximal tubule cells has been reduced with conventional (PDpt) as well as with sodium (PDna) and hydrogen ion (PDh) selective microelectrodes continuously before, during, and after the luminal application of 10 mmol/l phenylalanine, replacing 10 mmol/l raffinose. PDh and PDna allowed the calculation of intracellular pH (pHi) and sodium activity (Nai), respectively. In the absence of phenylalanine in the tubule lumen, PDpt approximates -57.5 +/- 2.3 mV (n = 27), pHi 7.73 +/- 0.04 (n = 14, extracellular pH 7.77), and Nai 13.3 +/- 0.9 mmol/l (n = 13, extracellular sodium activity 74 mmol/l). Within 1 min the luminal application of phenylalanine leads to a depolarisation of PDpt by +32 +/- 2 mV, as well as an increase of pHi by 0.24 +/- 0.04 and of Nai by 5.2 +/- 1.0 mmol/l. At 8 min from luminal application of phenylalanine, Nai plateaus 5 +/- 1 mmol/l above control value, PDpt increases again to a value of +12 +/- 2 mV below and pHi decreases to a value 0.04 +/- 0.07 above their respective control values. All changes are fully reversed after removal of phenylalanine from the tubule lumen.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Possible role of nickel ions in the pathogenesis of ischemic coronary vasoconstriction in the dog heart.

To test the hypothesis that nickel ions released from the ischemic dog myocardium [18] play a role in the pathogenesis of ischemic coronary vasoconstriction, the present experiments on the in situ heart of the anesthetized open-chest dog were designed to analyze coronary vascular action of intravenous (i.v.) and intracoronary (i.c.) injection of exogenous NiCl2 under the influence of ischemia, arterial hypoxemia and adenosine. The experimental results showed that (1) exogenous NiCl2 induced coronary vasoconstriction by a direct action on coronary vessels in low doses (0.02 mg X kg-1 i.v. bolus injection, or 0.04 mg X min-1 X kg-1 i.c. infusion) comparable to the Ni amount released endogenously, (2) NiCl2 significantly inhibited postocclusion reactive hyperemia and coronary vasorelaxation in response to arterial hypoxemia or intracoronary infusion of adenosine, (3) NiCl2 is capable of inducing coronary vasoconstriction when the coronary arteries are dilated by low flow ischemia, arterial hypoxemia and adenosine infusion, and (4) the Ni-sensitivity of coronary arteries increases significantly under these conditions. A hypothetical model is proposed summarizing the possible positive feedback loops triggered by endogenous Ni-release, which may cause coronary vasoconstriction in the ischemic dog myocardium.

Adenosine↗
PubMed1984

Effect of topical adenosine deaminase treatment on the functional hyperemic and hypoxic responses of cerebrocortical microcirculation.

The purpose of this study was to investigate the possible importance of adenosine in cerebrocortical vasodilatation accompanying brain activation (epileptic seizures and direct electrical stimulation) and hypoxia (arterial hypoxia and cyanide poisoning of the brain cortex). In chloralose-anesthetized cats a circumscribed area of the brain cortex was treated with adenosine deaminase (Type III; Sigma), which potently deaminates adenosine to the nonvasoactive inosine. Cerebrocortical vascular volume and fluorescence of reduced nicotinamide adenine dinucleotide were measured in vivo by surface fluororeflectometry. The responses of small pial and intracortical vessels to brain activation and hypoxia were studied in brain cortices superfused with artificial (mock) CSF and 5 U/ml adenosine deaminase. It was found that superficially applied adenosine deaminase readily diffuses onto the brain cortex. Prolonged pretreatment of the brain cortices with 0.025 U/ml adenosine deaminase eliminated almost completely the vasodilative effect of 10(-7) mol/ml adenosine. The inhibitory effect of the enzyme on adenosine-induced cortical vasodilatation was specific, because 5 U/ml adenosine deaminase did not attenuate the vasodilative potency of 10(-8) mol/ml 2-chloroadenosine. Adenosine deaminase (5 U/ml) pretreatment of the brain cortices did not diminish the cerebrocortical vascular volume, which increased with arterial hypoxia, topical cyanide poisoning, and direct electrical stimulation. However, it slightly decreased the vasodilative effect of epileptic seizures. On the basis of these results, it seems very unlikely that adenosine is a critical factor in the control of cerebrovascular tone during arterial hypoxia and brain activation.

Adenosine Deaminase↗
PubMed1982

Inhibition of myocardial reactive hyperaemia but not of hypoxic coronary vasodilatation by constant verapamil infusion in the in situ dog heart.

The purpose of the present study was to investigate the changes of characteristic parameters of myocardial reactive hyperaemia that follow coronary artery occlusion for 10 sec and of the coronary vascular response to hypoxia during constant verapamil infusion (0.01 mg. kg-1 X min-1) in anaesthetized open-chest dogs. Reactive hyperaemia was significantly reduced by the specific Ca-antagonist verapamil, while augmentation of coronary blood flow by 100% N2 inhalation for 30 sec was not significantly influenced by the drug. The experimental results indicate that, similar to myocardial cells, verapamil reduces the oxygen requirement of vascular smooth muscle cells as well. The possibility exist that verapamil excludes factor(s) responsible for the disproportional overpayment of flow debt.

Animals↗
PubMed1982

Effect of verapamil and phenoxybenzamine on nickel-induced coronary vasoconstriction in the anaesthetized dog.

Ni-induced coronary vasoconstriction has been studied in the dog heart in situ in the presence of the selective Ca-antagonist verapamil, and after blocking the alpha-receptors with phenoxybenzamine (PBZ). Verapamil totally abolished the coronary blood flow (CBF) and basal conductance (BC) decreasing effect of low doses of Ni2+ (0.02-0.2 mg/kg-1). The effect of higher doses of Ni2+ (2.0-20.0 mg/kg-1) was reversed by verapamil, i.e. high doses of exogenous NiCl2 increased CBF and BC in the presence of verapamil. The CBF decreasing effect of nickel was not significantly influenced by PBZ pretreatment. The results indicate that trace amounts of exogenous NiCl2 induce coronary vasoconstriction in the dog heart in situ by enhancing Ca2+-influx into vascular smooth muscle cells, which is not mediated by alpha-receptors.

Animals↗
PubMed1978

The influence of maternal immunoglobulin-G-antibodies on indirect haemagglutination in newborns.

High antibody titers against Escherichia coli were found in 100 randomly selected pregnant women by means of indirect haemagglutination (IHA). After birth, sera from the umbilical vein of the newborns were also tested. It was found that the indirect haemagglutination titers of the children were strongly influenced by the IgG which had been transferred via the placenta. Twenty-two sera of newborns showed an increased IHA-titer against E. coli, but only seven children displayed specific IgM antibodies, determined by indirect immunofluorescence. After chromatographic separation of the sera into IgG and IgM fractions, it was demonstrated that isolated antibodies of the IgG type alone can produce increased IHA titers. The assumption that the indirect haemagglutination is determined almost exclusively by antibodies of the IgG type is unfounded. Therefore, indirect haemagglutination is not suitable as a screening-test for newborns.

Antibodies, Bacterial↗
PubMed1977

Canaline carbamoyltransferase in human liver as part of a metabolic cycle in which guanidino compounds are formed.

This and previous papers examine the reasons for the relationship between the concentrations of guanidino-succinate and guanidinoacetate in human urine. With the demonstration here that extracts of human liver-tissue can mediate ureidohomoserine formation from canaline [(2-amino-4-aminooxy)-butyric acid] and carbamoyl phosphate, all steps in a cycle proposed for the production of guanidinoacetate and guanidinosuccinate have been documented. This includes synthesis of canavaninosuccinate from aspartate and ureidohomoserine, reductive cleavage of canavaninosuccinate to form guanidinosuccinate and homoserine, or, alternatively, lytic action on canavaninosuccinate to form fumarate and canavanine, and transamidination to glycine to form guanidinoacetate, regenerating the canaline. We propose that canaline originates from aspartate, but the precise mechanism by which canaline is formed needs to be elucidated.

Aminobutyrates↗
PubMed1976

Osteopathy due to methotrexate.

Two children with ALL receiving long-term therapy with methotrexate (50 mg/week i.v.) developed severe osteoporosis accompanied by swelling of the joints, gait disturbances and fractures after minimal trauma. Bone scans 85Sr disclosed a decreased input and increased turnover of calcium especially in the most used bones. The data of the calcium phosphorus metabolism are within the normal range. The minimal changes in the biopsy material of the iliac crest may be due to little mechanical use so that this part of the skeleton is not much affected by the osteoporosis. Since the controls receiving the same therapy did not have signs of such severe osteoporosis it is assumed that an additional, till unknown factor may play an additional role in this kind of methotrexate side effect.

Calcium↗
PubMed1976

[Burkitt's lymphoma (author's transl)].

Burkitt's lymphoma occurs endemically in Central Africa, but is also found sporadically in areas with temperate climate. A case of Burkitt's lymphoma found in our area is described. The literature in regard to the clinical symptoms, etiology and treatment of Burkitt's lymphoma is reviewed. At the present time cyclophosphamide is considered to be the drug of choice; it leads to a remission rate of about 90%.

Antibodies, Viral↗