Search results for "Lactates"

Acute changes of systemic parameters in tumour-bearing rats, and of tumour glucose, lactate, and ATP levels upon local hyperthermia and/or hyperglyca…

1991

Arterial blood pressure and relevant parameters of the arterial blood (O2 and CO2 tensions, pH, haematocrit, serum electrolytes and osmolality) were determined in tumour-bearing rats upon local hyperthermia (HT) and/or hyperglycaemia (HG). Tumour heating was performed in a saline bath (44 degrees C) for 120 min; hyperglycaemia was induced by i.v. infusion of 40% glucose solution for 150 min [blood glucose levels: 35-40 mM during heating; total amount of glucose: 1.19 g/100 g body wt.; infusion rates: 0.31 ml (100 g body wt.)-1 min-1 for 2 min, 0.02 ml (100 g body wt.)-1 min-1 for 88 min, and 0.01 ml (100 g body wt.)-1 min-1 for 60 min]. Immediately after treatment, glucose, lactate and ATP …

Fasting prior to transient cerebral ischemia reduces delayed neuronal necrosis.

1990

A transient brain ischemia of 30-min duration was induced by the four-vessel occlusion technique in normally fed and in 48-hr-fasted rats. Evaluation of brain damage 72 hr after ischemia showed that fasting reduced neuronal necrosis in the striatum, the neocortex, and the lateral part of the CA1 sector of hippocampus. Signs of status spongiosis in the pars reticulata of the substantia nigra were seen in 75% of fed rats and in only 19% of fasted rats. The protective effect was associated with reduction in mortality and in postischemic seizure incidence. The metabolic changes induced by fasting were evaluated before and during ischemia. After 30 min of four-vessel occlusion, fasted rats showe…

Lipid metabolism during exercise

1980

Seven physically fit (well-trained, maximal oxygen uptake 69.6 +/- 4.4 ml x kg-1 min-1) and eight less fit (moderately trained, maximal oxygen uptake 56.1 +/- 5.7 ml x kg-1 x min-1) healthy male subjects were exercised for 4 h by bicycle ergometry against a pedalling resistance calculated to cause oxygen consumption corresponding to approximately 30% of each individual's maximal oxygen uptake value. Respiratory exchange ratio was estimated at 1 h and blood glucose and lactate concentrations and muscle glycogen content at 2 h intervals. Muscle glycogen content decreased markedly during the first 2 h of exercise in the well-trained group but was similar after 4 h exercise in both groups. No m…

Changes in selected biochemical parameters in the brain of the fish, Anguilla anguilla (L.), exposed to lindane.

1991

Biological response of multicellular emt6 spheroids to exogenous lactate

1991

The influence of elevated lactate concentrations, as found in tumor microregions, on cellular growth, viability, and metabolic state was studied employing the multicellular spheroid model. Spheroids of EMT6/Ro cells were cultured at 37 degrees C in 5% or 20% (v/v) oxygen, using stirred media with various concentrations of exogenous lactate ranging from 0.0 mM (standard conditions) to 20.0 mM. Elevated concentrations of exogenous lactate led to a considerable decrease of the maximum spheroid diameter at growth saturation, e.g., for 20% O2 from around 1700 microns to 700 microns in 0.0 and 20.0 mM lactate respectively. Histological investigations showed that the thickness of the viable cell r…

Metabolic Imaging in Microregions of Tumors and Normal Tissues With Bioluminescence and Photon Counting

1988

A method has been developed for metabolic imaging on a microscopic level in tumors, tumor spheroids, and normal tissues. The technique makes it possible to determine the spatial distribution of glucose, lactate, and ATP in absolute terms at similar locations within tissues or cell aggregates. The substrate distributions are registered in serial cryostat sections from tissue cryobiopsies or from frozen spheroids with the use of bioluminescence reactions. The light emission is measured directly by a special imaging photon counting system enabling on-line image analysis. The technique has been applied to human breast cancer xenografts, to spheroids originating from a human colon adenocarcinoma…

Lactate-induced inhibition of tumor cell proliferation.

1988

Abstract Culture medium that was recovered from tumor cell or fibroblast cultures during the plateau phase, and that was replenished by addition of glucose, glutamine, and serum and readjustment of pH had a distinct growth-inhibiting effect on monolayer cell cultures. The effect, which was not specific for a given cell strain, may be partially responsible for the "density inhibition" commonly observed in malignant cells grown in monolayer cultures. By modifying fresh growth media, it was shown that the growth inhibition observed can be partly attributed to the accumulation of lactate in the culture medium of plateau phase cells. This substance reduced the plating efficiency and the number o…

Growth rates or radiobiological hypoxia are not correlated with local metabolite content in human melanoma xenografts with similar vascular network.

1995

Investigations were carried out on two lines of human melanomas (MF; n = 12 and EE; n = 13) xenografted in nude mice. The tumours were characterised by a similar vascular supply but showed a pronounced difference in the rate of volume growth and in the radiobiologically hypoxic fraction. The distribution of ATP, glucose and lactate in the tumours was investigated using quantitative bioluminescence and single photon imaging. Concentrations of the metabolites were obtained as global values for the entire tumour mass, in regions with densely packed, structurally intact tumour cells ('viable zones'), in areas with necrosis, stromal cells and fibrous material ('necrotic zones') and in adjacent n…

Geographical mapping of metabolites in biological tissue with quantitative bioluminescence and single photon imaging

1993

This article features a novel technique for measuring the spatial distribution of metabolites, such as ATP, glucose, and lactate, in rapidly frozen tissue. Concentration values are obtained in absolute terms and with a spatial resolution of single-cell dimension. The method is based on enzymatic reactions that link the metabolite of interest to luciferase with subsequent light emission. Using a specific array, cryosections are brought into contact with the enzymes in a well-defined, reproducible way inducing a distribution of light across the section with an intensity that is proportional to the metabolite concentration. The emitted light can be visualized through a microscope and an imagin…

Cloning and sequencing of the gene encoding α-acetolactate decarboxylase fromLeuconostoc oenos

1996

The alsD gene encoding alpha-acetolactate decarboxylase was isolated from a genomic library of Leuconostoc oenos, using a screening procedure developed on microtiter plates. The nucleotide sequence of alsD encodes a putative protein of 239 amino acids showing significant similarity with other bacterial alpha-acetolactate decarboxylases. Upstream from alsD lies an open reading frame (alsS) which is highly similar to bacterial genes coding for catabolic alpha-acetolactate synthases. Northern (RNA) blotting analyses indicated the presence of a 2.4-kb dicistronic transcript of alsS and alsD. This suggests that the alsS and alsD genes are organized in a single operon.