Biomedical subjects

M Grdisa

Publications and source records attributed to M Grdisa.

30 records · Page 2Linked to original sources

PubMed1994

Effect of hypothalamic 5,7-dihydroxytryptamine lesion on the anterograde transport of serotonin as measured with labeled alpha-methyl serotonin.

The anterograde axonal transport of serotonin along the medial forebrain bundle (MFB) 5 days after unilateral dorsal hypothalamic 5,7-dihydroxytryptamine (5,7-DHT) lesion was examined in rat brain. Measurements were done using in vivo synthesized radioactively labeled alpha-methyl serotonin (used here as a serotonin tracer), from i.v. injected labeled alpha-methyl-L-tryptophan, a substitute neurotransmitter and analog of serotonin. Data indicated that after destruction of the presynaptic terminals with 5,7-DHT, the rate of axonal transport of serotonin and/or the rate of serotonin synthesis in the spared and/or damaged neurons was increased. The rate of serotonin anterograde transport on the lesioned side was above 25 mm/d compared to 12.31 +/- 0.49 mm/d on the contralateral side and 12.13 +/- 0.44 mm/d in control (sham injected) rats. The difference in rate between the lesioned and control rats was highly significant; P < 0.005 (two-tailed t-test). The amount of neurotransmitter anterogradely transported along the medial forebrain bundle and/or synthesized in the neurons was 18.8 +/- 4.1 times greater on the side of the 5,7-DHT hypothalamic lesion than that on the contralateral sides or that found in the saline-injected rats. There was no difference in the radioactivity found on the left or right side of the medial forebrain bundle in the rats 5 days after lesion in the rostal midbrain with 5,7-DHT. Five days after the lesion there was also no difference in the anterograde protein transport measured by stereotaxic injection of [3H]proline into the dorsal raphe.

5,7-Dihydroxytryptamine↗

PubMed1994

Loss of glucose transporters is an early event in differentiation of HD3 cells.

The HD3 cell, a chicken erythroblast cell line infected with a temperature-sensitive avian erythroblastosis virus, becomes committed to differentiate to an erythrocyte upon temperature shift in presence of inducers. Before induction, the HD3 cell transports glucose and 2-deoxyglucose (2-DG). 3-O-methylglucose is poorly taken up. Upon induction of differentiation, glucose and 2-DG transport activity fall. Twenty-four hours postinduction, up to 75% of the glucose transport activity may disappear. By use of cDNA probes for chicken glucose transporters, two species of mRNA of 3.1 and 1.7 kb (equivalent to mammalian GLUT1 and GLUT3 mRNA, respectively) are detected. Both messages virtually disappear within 48 h after induction. Run-on assays show the cessation of synthesis of the corresponding RNAs parallel to the loss of glucose transport. In contrast to the glucose transporters, the nucleoside transporter level increases after induction of hematopoiesis. This developmental pattern is consistent with earlier studies showing that mature chicken erythrocytes have little glucose transport activity but retain appreciable levels of the nucleoside transporter and that nucleosides and glutamine provide major sources of oxidizable carbon compounds to sustain metabolism in circulating chicken erythrocytes.

3-O-Methylglucose↗

PubMed1993

Expression and loss of the transferrin receptor in growing and differentiating HD3 cells.

During induced differentiation and maturation of HD3 cells (a chicken erythroblast cell line infected with a temperature-sensitive mutant of the avian erythroblastosis virus), the levels of transferrin receptor (TFR) and nucleoside transporter increase. Both these activities increase before elevated levels of hemoglobin are detected. Shortly after induction, as cellular TFR levels rise, a native-size TFR is detected in the cell-free culture medium, associated with an exosome fraction (100,000 xg pellet). Nucleoside transporter (measured as NBMPR-binding activity) is not increased in this pellet with induction. Previous studies have suggested that exosome formation in peripheral reticulocytes may be a significant route for loss of specific membrane proteins (Johnstone et al., 1991). Although the present experiments in HD3 cells do not address the quantitative importance of exosome formation, the studies suggest that exosome formation is an early event in commitment to the red cell lineage and is not a phenomenon restricted to the terminal stages of red cell maturation.

Adenosine Triphosphate↗

PubMed1993

Rapid steady-state analysis of blood-brain transfer of L-Trp in rat, with special reference to the plasma protein binding.

We estimated constants for the binding of tryptophan (Trp) to plasma proteins, and for the transfer of Trp from plasma to brain in rat. The measurements were made under conditions in which the plasma and brain concentrations of Trp were raised to new steady-states for at least 10 min before being measured. The concentration of other competing amino acids were also at a steady-state. The plasma Trp concentration was elevated by i.p. injection of different doses of L-tryptophan methyl ester 60 min before the measurement of the plasma-brain transfer. We simultaneously measured blood flow with [14C]-butanol, and the brain tissue Trp uptake with [3H]Trp. The maximal velocity (Vmax), apparent half-saturation Michaelis-Menten constant (Km(app)), and diffusion constant (PdS) for Trp transport from plasma into brain were found to be 7.0 +/- 2.1 nmol g-1 min-1, 36 +/- 17 microM, and 0.065 +/- 0.006 ml g-1 min-1, respectively. The maximum plasma protein binding (Bmax) and dissociation constant (KD) for Trp were estimated at 360 +/- 16 nmol/ml-plasma and 81 +/- 10 microM, respectively. We conclude that the plasma protein binding of Trp inhibits the blood-brain transfer in inverse proportion to the plasma free Trp concentration.

Animals↗

PubMed1992

Blood-brain barrier transfer of L-Trp and alpha-MTrp in Li-treated rats.

Blood-brain barrier (BBB) transport for L-Trp and alpha-methyl-L-tryptophan was evaluated in Li-treated rats. Five different brain areas as well as left to right differences were examined. No left to right difference in the PS product was observed. Lithium treatment had a significant effect on the plasma concentration of Val, Leu and Ile but no effect on plasma total or free Trp. The ratio of plasma Trp to the sum of Leu, Val, Ile, Phe, Met and Tyr is increased in the Li-treated rats but not significantly. However, the ratio of Trp/(Val+Leu+Ile) is significantly increased in the Li-treated rats. The Km apparent (Kmapp) for the BBB Trp transport is significantly decreased (affinity of the carrier for Trp is increased) in the Li-treated rats. A decrease in the Kmapp is one of the possible factors responsible for an increase in the brain Trp concentration and subsequent increase in the brain serotonin synthesis in Li-treated rats.

Animals↗

PubMed1991

The fate of human polymorphonuclear leukocyte aminopeptidases upon cell stimulation with phagocytic and chemical stimuli.

1. After being treated with nonopsonized zymosan A or phorbol-12-myristate-13-acetate, human polymorphonuclear leukocytes release aminopeptidases together with granules marker-enzymes and vitamin B12-binding protein. 2. Chemotactic peptide, fMet-Leu-Phe and its analogs, fMet-Phe, fMet-Ala and fMet-Leu-Phe-Lys have a similar effect. 3. By their isoelectric point determinations the released aminopeptidases correspond to the enzymes from granules. Among aminopeptidases released the highest activities were those toward methionine- and alanine-2-naphthylamide and the lowest one toward arginine-2-naphthylamide.

Aminopeptidases↗

PubMed1991

Types and localization of aminopeptidases in different human blood cells.

1. Erythrocytes, polymorphonuclears, monocytes and lymphocytes isolated from human peripheral blood, were shown to possess in their cytosols, granules and microsomal fractions, aminopeptidases capable of hydrolysing arginyl-, leucyl-, methionyl-, phenylalanyl- and alanyl-2-naphthylamide. 2. In different cell compartments enzymes of different pI were responsible for these activities. 3. Chloride activated arginine aminopeptidase, broad specificity aminopeptidase and dipeptidyl peptidase III were found in cytosols of all examined cells. 4. In granules at least two aminopeptidases, a basic or neutral one, and an acidic one inactive at pH 4.4, could be discerned, whereas in microsomal fractions a broad specificity aminopeptidase preferring methionine was detected. 5. There is a considerable degree of similarity in the pattern of aminopeptidases within different blood cells. This may suggest that their functions are correlated to the physiological role of a particular cell compartment, rather than to that of a distinct cell type.

Aminopeptidases↗

PubMed1986

Human polymorphonuclear leukocytes aminopeptidases.

In human polymorphonuclear leukocytes a methionine, leucine, arginine, phenylalanine and alanine aminopeptidase activities were detected, both in cytosol and secondary granules. All activities were EDTA sensitive and their pH optima were in the range of pH 6.5 to 8.6. In the cytosol two enzymes could be distinguished, broad substrate specificity aminopeptidase of pH 4.7-4.9 and a chloride dependent arginine aminopeptidase of pI 5.3-5.5. The granules contain aminopeptidase of pI 4.0-4.6 and of pI 9.8-10.2, different from those in the cytosol. Among them broad specificity aminopeptidases and possibly specific methionine and leucine aminopeptidases could be discerned.

Alanine↗

PubMedDate not supplied

Stimulation of growth factor synthesis in skin wounds using tissue extract (G-90) from the earthworm Eissenia foetida.

Growth factors are biologically-active mediators that bind to specific receptors on target cells and regulate genes involved in cell growth, wound healing and regeneration. In the case of wound healing, a proper wound dressing is needed to cover the wound area, protect the damaged tissue, and if possible to activate cell proliferation and stimulate the healing process. In this study we examined the efficacy of a glycolipoprotein tissue homogenate extract from Eisenia foetida (G-90) to activate signal transduction pathways, leading to wound healing. We measured the activation of EGF and FGF in healthy skin, in wounds with physiological healing and in wounds treated with G-90. The activation of EGF and FGF was measured during the first 24 h of wound healing under both physiological conditions and treatment with G-90. In both cases an increased concentration of EGF and FGF was observed 6 h after wounding. In comparison with healthy skin, the concentration of EGF increased 10-fold and FGF five-fold in wounds treated with G-90 (10 ng ml(-1)). Healing in physiological conditions resulted in a two-fold increase of EGF and 1.5-fold of FGF.

Animals↗

PubMedDate not supplied

Nucleosides and glutamine are primary energy substrates for embryonic and adult chicken red cells.

It has been assumed that glucose is a major energy yielding substrate for chicken red blood cells. In this report we show that glucose fails to maintain cellular ATP levels in embryonic and mature chicken erythrocytes during overnight incubation. Of over a dozen metabolites tested, inosine, guanosine, and glutamine were the most efficacious ATP-sustaining substrates. Of seven potential citric acid cycle substrates, only glutamine significantly sustained ATP levels. Incubation with inosine plus glutamine sustained the ATP level at over 70% of the initial value found in embryonic chicken red cells. Uridine, cytidine, xanthosine, glutamate, and pyruvate were ineffective substrates. Similar results were obtained with adult erythrocytes, except that glutamine plus inosine fully sustained ATP levels during long-term incubation. Adenosine did not sustain ATP levels. Below 1 mM, the adenosine level was rapidly exhausted and above 1 mM its presence led to cell lysis. The ability of some nucleosides to maintain ATP levels is consistent with the high numbers of nitrobenzylthioinosine binding sites (nucleoside transporter sites) both in mature chicken red cells (approximately 10,000 sites/cell) and in embryonic red cells (approximately 30,000 sites/cell). Unlike pig red cells which switch from glucose to nucleosides at the erythrocyte stage, chicken cells show primary dependence on nucleoside metabolism at the embryonic stage.

Adenosine↗

PubMedDate not supplied

Effect of a 17-member azalide on tumor cell growth.

The action of the 17-member azalide 4'-demycarosyl-20-deoxo-20-(di-N-benzylamino)-8a-aza-8a-homotyl osin was examined in vitro using five different human cell lines: laryngeal carcinoma (Hep2), pancreatic carcinoma (MiaPaCa2), breast carcinoma (MCF7), neuroblastoma, and normal diploid fibroblast (Hef522). After exposure, the cell growth was arrested, and morphological changes occurred in a dose-dependent manner. At a concentration of 10(-4) M the azalide completely inhibited the growth of all cell lines examined and induced morphological changes such as cell shrinkage, chromatin condensation, and DNA fragmentation. These features point to apoptosis.

Anti-Bacterial Agents↗

PubMedDate not supplied

Alternative sources of fibrinolytic, anticoagulative, antimicrobial and anticancer molecules.

The medicinal properties of earthworms in various remedies date back to 1340 A.D. and have been extended to other countries and cultures. Assays of tissue homogenates of earthworm (Eisenia foetida) have revealed a glycolipoprotein mixture referred to as G-90 that is composed of macromolecules with medical and pharmaceutical applications. There are several functions attributed to G-90: possession of several growth factors that: stimulate proliferation in cell cultures, contain an insulin like growth factor (IGF like), an immunoglobulin like growth factor (IgFG-like), possess two serine peptidases with a tyrosine code and epidermal growth factor (EGF). In contrast, G-90 exerts strong fibrinolytic and anticoagulative activity capable of lysing fibrin clots. Actions of these two properties are dependent upon concentration. Anti-coagulative activity also depends upon the kind of anticoagulants (G-90, PI, PII). G-90 can also act as antioxidant, exert antimicrobial activities in vitro and in vivo. The bacteriostatic effect is significantly greater for non-pathogenic species. Finally G-90 also participates in tissue regeneration and wound healing. Taken together, components of earthworms could be tested in certain clinical trials.

Animals↗