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V Gallo

Publications and source records attributed to V Gallo.

At least 73 records · Page 4Linked to original sources
PubMed1990

Extracellular matrix of cultured glial cells: selective expression of chondroitin 4-sulfate by type-2 astrocytes and their progenitors.

We have studied the extracellular matrix composition of cultured glial cells by immunocytochemistry with different monoclonal and polyclonal antibodies. Double immunofluorescence experiments and metabolic labeling with [3H]glucosamine performed in different types of cerebellar and cortical cultures showed that bipotential progenitors for type-2 astrocytes and for oligodendrocytes (recognized by the monoclonal antibody LB1 at early stages of their development) synthesize chondroitin sulfate (CS) and deposit this proteoglycan in their extracellular matrix. The distribution of the various [3H]glucosamine-labeled glycosaminoglycans between the intracellular and the extracellular space was different. CS was present both within the cells and in the culture medium, although in different amounts. Bi-potential progenitors became also O4-positive during their development in vitro. At the stage of O4-positivity they were still stained with antibodies against CS. However, when the progenitor cells were maintained in serum-free medium and differentiated into Gal-C-positive oligodendrocytes, they became CS-negative. In the presence of fetal calf serum in the culture medium, the bipotential progenitors differentiated into GFAP-positive type-2 astrocytes. These cells still expressed CS: their Golgi area and their surface were stained with anti-CS antibodies. Staining with monoclonal antibodies specific for different types of CS (4-sulfate, 6-sulfate, and unsulfated) revealed that both bipotential progenitors and type-2 astrocytes synthesized only chondroitin 4-sulfate. Type-1 astrocytes were negative for both the polyclonal and the monoclonal anti-CS antibodies. Finally, type-2 astrocytes and their progenitors were weakly stained with anti-laminin antibodies and unstained with anti-fibronectin. Type-1 astrocytes were positive for both anti-laminin and anti-fibronectin antibodies and appeared to secrete fibronectin in the extracellular space.

Animals↗
PubMed1990

A randomized controlled trial of interferon alfa-2b as therapy for chronic non-A, non-B hepatitis.

Eighty patients with chronic non-A, non-B hepatitis completed a randomized controlled trial of the therapeutic efficacy of recombinant interferon alfa-2b. Twenty-nine received 1 million units and 26 received 3 million units of interferon subcutaneously thrice weekly for 6 months, and 25 were controls. Normalization or a significant decrease of alanine aminotransferase values was obtained in 19/29 (66%) patients treated with 1 million units, in 18/26 (69%) patients treated with 3 million units and in one control patient (4%, p less than 0.05). However, when control patients were randomized after the initial 24 weeks to receive 1 or 3 million units of interferon for 48 weeks, 12/14 (86%) patients receiving 3 million units responded to therapy versus 3/11 patients receiving 1 million units (27%, p less than 0.05). After a 1 to 6 months follow-up period post treatment, an alanine aminotransferase relapse was observed in 18/30 (60%) responders to 3 million units and in 17/22 (77%) responders to 1 million units. Cirrhotic patients responded less than patients with non-cirrhotic disease (47 vs. 78%, p less than 0.05). Only responders treated with 3 million units significantly ameliorated their histologic picture (pre-therapy Knodell's index = 8.9, post-therapy = 6.0, p less than 0.05). The data confirm that treatment with interferon is of benefit in patients with chronic non-A, non-B hepatitis.

Adult↗
PubMed1990

Autoantibodies and response to alpha-interferon in patients with chronic viral hepatitis.

One hundred and fifteen patients with chronic type B, D and non-A, non-B hepatitis treated with recombinant alpha-interferon were tested for six different autoantibodies prior to or during therapy, and the course of treatment was compared in autoantibody-positive and -negative patients. Three out of 25 (12%) hepatitis B patients, 14 out of 30 (47%) hepatitis D patients and 19 out of 60 (32%) chronic non-A, non-B hepatitis carriers had baseline or post-therapy autoantibodies. The rate of response between patients with and without autoantibodies among B, D and non-A, non-B patients was, respectively, 67 vs. 79%, 23 vs. 25%, 70 vs. 61% (p = N.S.). No adverse reaction was observed in the 36 patients who had or developed nuclear, smooth muscle, parietal cells and thyroid autoantibodies during therapy. A patient with baseline antibodies against liver and kidney microsomes developed an icteric acute hepatitis at the fourth month of therapy, but five other patients with this reactivity responded to therapy uneventfully. The presence of autoantibodies before therapy or their induction following therapy is not a contraindication to the use of interferon in patients with chronic viral hepatitis.

Animals↗
PubMed1990

Modulation of non-N-methyl-D-aspartate receptors in cultured cerebellar granule cells.

Kainic acid (KA), quisqualic acid (QUIS), and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) stimulated D-[3H]aspartate release from cultured cerebellar granule cells in a concentration-dependent way. The EC50 values were 50 microM for KA (Gallo et al., 1987) and 20 microM for both QUIS and AMPA, but the efficacy of QUIS appeared to be greater than that of AMPA. The release of D-[3H]aspartate induced by KA, QUIS, and AMPA was blocked, in a dose-dependent way, by the new glutamate receptor antagonist 6-cyano-2,3-dihydroxy-7-nitroquinoxaline (CNQX); IC50 values were 0.7 microM in the case of AMPA (50 microM) and 1 microM in the case of KA (50 microM). AMPA (50-300 microM) inhibited the effect of 50 microM KA on D-[3H]aspartate release. At 300 microM AMPA, the effect of KA plus AMPA was not antagonized by the KA receptor antagonist kynurenic acid (KYN). In contrast, when KA was used at an ineffective concentration (10 microM), the addition of AMPA at concentrations below the EC50 value (10-20 microM) resulted in a synergistic effect on D-[3H]aspartate release. In this case, the evoked release of D-[3H]aspartate was sensitive to KYN. KA stimulated the formation of cyclic GMP, whereas QUIS, AMPA, and glutamate were ineffective. The accumulation of cyclic GMP elicited by KA (100 microM) was prevented not only by the antagonists CNQX (IC50 = 1.5 microM) and KYN (IC50 = 200 microM), but also by the agonists AMPA (IC50 = 50 microM) QUIS (IC50 = 3.5 microM), and glutamate (IC50 = 100 microM). We conclude that AMPA, like QUIS, may act as a partial agonist at KA receptors. Moreover, CNQX effectively antagonizes non-N-methyl-D-aspartate receptor-mediated responses in cultured cerebellar granule cells.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed1990

Two cases of congenital hepatic fibrosis in children of consanguineous marriage.

An association of congenital hepatic fibrosis (CHF), Caroli's disease, medullary sponge kidney, type II interventricular defect with right transposition of the aorta, multiple cervical vertebra malformations, and first sacral vertebra schisis in a 16 year old son of consanguineous parents (consanguinity factor = 1/32), is described. The patient's sister presented asymptomatic CHF and medullary sponge kidney only. Parental consanguinity in this case lends support to the view that CHF, medullary sponge kidney and cardiac malformations are more likely to be manifestation of a single recessive gene, with a varying phenotypic expression, than of different mutant genes.

Adolescent↗
PubMed1990

[Liver and thyroid gland. Physiopathologic and clinical relationships].

The liver plays a dominant role in the metabolism of the thyroidal hormones; it is here that the 5' deiodase acts to convert part of T4 to T3. There are eight further circulating iodothyronines: the rT3, mainly derived from T4, appears to be the major inhibitor of T4 and T3. Thus, if rT3 increases, the metabolic effects of T3 and T4 can be quite different. In the course of some chronic systemic diseases (e.g. hepatic cirrhosis) rT3 increases simultaneously with the decrease of T3 levels. Therefore we can describe particular alterations of the thyroidal pattern typical of chronic liver diseases: low T3 syndrome, low T3 and T4 syndrome, high T4 syndrome, mixed forms. T3 and T4 diminish due to inefficient hepatic deiodination and defective hepatocellular uptake. Inefficient hepatic deiodination and defective hepatocellular uptake. T4 levels decrease, most likely because of an inefficient production of thyroid binding globulin, or the action of a peripheral binding inhibitor. During acute liver diseases and primitive biliary cirrhosis, we can observe an increase of T4 and TBG together with an increase of the acute phase proteins. Such complex hormonal mechanisms are not influenced by TSH, which appears normal or inhibited, as the TRH stimulus test is normal. The explication can be found in an enhanced conversion of T4 to T3 in the pituitary gland. The biological and clinical significance of these mechanisms might be that of creating a "protective" state for an organism in a catabolic state by reducing the circulating T3. A relationship has been found between circulating thyroidal hormones levels, particularly the T3, rT3 and rT3/T3 ratio, and the state of hepatic functional insufficiency.(ABSTRACT TRUNCATED AT 250 WORDS)

Homeostasis↗
PubMed1989

Multiple conductance channels in type-2 cerebellar astrocytes activated by excitatory amino acids.

L-GLUTAMATE and L-aspartate are thought to have a widespread function as synaptic transmitters in the mammalian central nervous system and there are at least three types of neuronal glutamate receptors, which can be activated by the selective agonists N-methyl-D-aspartate (NMDA), quisqualate and kainate. Recent experiments indicate that glutamate receptors also occur in astrocytes. We have used patch-clamp methods to determine whether one type of macroglial cell, the type-2 astrocyte, possesses glutamate receptors, as previously proposed from neurochemical studies. We find that glutamate and related amino acids can evoke whole-cell and single-channel currents in type-2 astrocytes from rat cerebellum. Although these cells are found mainly in white matter, where neurotransmission does not occur, their processes are closely associated with axons at nodes of Ranvier, suggesting that such receptors are involved in neuronal-glial signalling at the node. Our experiments show that glial cells possess quisqualate- and kainate-receptor channels but lack receptors for NMDA. Interestingly, these glutamate channels exhibit multiple conductance levels that are similar in amplitude to the neuronal glutamate channels.

Animals↗
PubMed1989

Measurement of amino acid release from cultured cerebellar granule cells by an improved high performance liquid chromatography procedure.

Endogenous amino acid release was examined in rat cerebellar primary cultures comprising more than 95% of glutamatergic granule cells. Eighteen amino acids were determined in the cell extracts and in the release fractions by high performance liquid chromatography, using precolumn derivatization with o-phthaldialdehyde and separation on a reverse-phase column using a multi-step gradient system of two solvents (0.1 M Na+ acetate, pH 7.2/methanol: tetrahydrofuran, 97:3). The fluorimetric response was linear, at least in the range of 2-162 pmol, for all the amino acids analysed, with a detection limit of 1 pmole. We observed a good reproducibility in within-assay and between-assay coefficients of variation of the retention times and fluorescence yield. When cultured granule cells were exposed to the excitatory amino acid receptor agonist quisqualic acid (50 microM), we observed a net increase in the release of glutamate (3 fold over the baseline) and a smaller increase in that of aspartate (2 fold) and taurine (1.6 fold). Other amino acids were not significantly affected. GABA levels were below detection limits, due to the minimal number of GABAergic neurons present in the cultures.

Amino Acids↗
PubMed1989

Expression of excitatory amino acid receptors by cerebellar cells of the type-2 astrocyte cell lineage.

We have used postnatal rat cerebellar astrocyte-enriched cultures to study the excitatory amino acid receptors present on these cells. In the cultures used, type-2 astrocytes (recognized by the monoclonal antibodies A2B5 and LB1) selectively took up gamma-[3H]aminobutyric acid ([3H]GABA) and released it when incubated in the presence of micromolar concentrations of kainic and quisqualic acids. The releasing effect of kainic acid was concentration dependent in the range of 5-100 microM. Quisqualate was more effective than kainate in the lower concentration range but less effective at concentrations at which its releasing activity was maximal (approximately 50 microM). N-Methyl-D-aspartic acid and dihydrokainate (100 microM) did not stimulate [3H]GABA release from cultured astrocytes. L-Glutamic acid (20-100 microM) stimulated [3H]GABA release as effectively as kainate. The stimulatory effects of kainate and quisqualate on [3H]GABA release were completely Na+ dependent; that of kainate was also partially Ca2+ dependent. Kynurenic acid (50-200 microM) selectively antagonized the releasing effects of kainic acid and also that of L-glutamate; quisqualate was unaffected. Quisqualic acid inhibited the releasing effects of kainic acid when both agonists were used at equimolar concentrations (50 microM). D-[3H]aspartate was taken up by both type-1 and type-2 astrocytes, but only type-2 astrocytes released it in the presence of kainic acid. Excitatory amino acid receptors with a pharmacology similar to that of the receptors present in type-2 astrocytes were also expressed by the immature, bipotential progenitors of type-2 astrocytes and oligodendrocytes.

Animals↗
PubMed1989

Quisqualic acid modulates kainate responses in cultured cerebellar granule cells.

The activation of kainic acid and quisqualic acid receptors in cultured cerebellar granule cells stimulated the release of preaccumulated D-[3H]aspartate. The effect of kainate could be distinguished from that of quisqualate by its sensitivity to the antagonists kynurenic acid and 2,3-cis-piperidine dicarboxylic acid. At a concentration of kainic acid (50 microM) close to its half-maximal releasing effect, simultaneous addition of quisqualic acid (10-50 microM) resulted in a significant dose-dependent inhibition of the kainate-induced component of D-[3H]aspartate release, which was monitored by the progressive decrease in sensitivity of the evoked release to kynurenic acid. In contrast, when kainic acid was used at a subeffective concentration (10 microM), addition of low doses of quisqualate (2-5 microM) resulted in a synergistic effect on D-[3H]aspartate release. Under these conditions, the effect of the two agonists was sensitive to kynurenic acid. Kainic acid (50-100 microM) also caused a dose-dependent, kynurenic acid-sensitive accumulation of cyclic GMP (cGMP) in granule cell cultures. Quisqualic acid was, by itself, ineffective and prevented, in a dose-dependent manner, the kainate-induced cGMP formation (IC50 = 5 microM). Finally, the guanylate cyclase activator sodium nitroprusside greatly enhanced cGMP formation but had no effect on D-[3H]aspartate release. Together, these results demonstrate the existence of complex interactions between quisqualic and kainic acids and indicate that the effects of the two glutamate agonists on D-[3H]aspartate release and on cGMP accumulation are independent.

Animals↗
PubMed1988

Effect of depolarization on the maturation of cerebellar granule cells in culture.

The effect of depolarization on the maturation of granule cells derived from cerebella of 8-day-old rats can be studied in cultures in chemically defined media because their survival is not dependent on elevated K+ as it is when they are grown in serum-containing media. As an index of maturation, stimulus-coupled transmitter release was examined. This was chosen because it is closely associated with the neuronal phenotype and, in contrast to granule cells grown under depolarizing conditions in serum-containing media, it has not been known whether this property is expressed during the development of serum-free cells in culture. Veratrine-induced release of preloaded D-[3H]aspartate (Asp), an analogue of glutamate (Glu; the transmitter of the granule cells), was not detectable in the serum-free cells at a time (8-12 days in vitro) when this property was fully developed in cells grown in a medium containing serum and 25 mM K+ (reference cultures). This finding may be related to the failure of the expression of voltage-sensitive calcium channels in the serum-free granule cells. However, in comparison with reference cultures, voltage-sensitive 45Ca2+ entry was only transiently retarded in the serum-free cells. Furthermore, in contrast to the exogenous D-[3H]Asp, stimulated release of endogenous Glu was detectable, although it was substantially lower than in the reference cultures. Autoradiographic studies indicated that the failure to elicit evoked release of the exogenous amino acid was due to a severe retardation of the expression of the acidic amino acid carrier in the serum-free granule cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1988

Stimulus-coupled release of amino acids from cerebellar granule cells in culture.

Cerebellar cultures greatly enriched in excitatory granule neurons were depolarized by exposure to either elevated K+ or veratrine. Stimulation of the release of not only Glu, but also of certain amino acids, including Gly, Ala and Ser, was observed. The effect was specific, as depolarization did not induce the release of all the estimated amino acids or of lactate dehydrogenase. In comparison with the characteristics of the evoked release of Glu, those of the responsive neutral amino acids were similar in terms of Ca2+-dependence, but differences were also noted. Thus, upon stimulation, the relative rise was smaller than for Glu and the degree of depolarization causing maximal release was lower. The questions of whether stimulus-coupled release of the non-transmitter amino acids from granule cells may play a neuromodulatory role in the cerebellum is discussed.

Amino Acids↗
PubMed1987

Functional evaluation of glutamate receptor subtypes in cultured cerebellar neurones and astrocytes.

Micromolar concentrations of kainic acid and quisqualic acid released [3H]D-aspartate preaccumulated by cerebellar granule cells in culture. The effect of kainate was selectively antagonized by kynurenic acid and, less effectively, by PDA. Kainate and quisqualate also increased [3H]GABA release from a subpopulation of cultured cerebellar astrocytes. Kynurenic acid selectively blocked the effect of kainic acid. NMDA and no D-aspartate or GABA releasing effect. These results suggest the existence of two different excitatory amino acid sites active on neurotransmitter amino acid release in both cerebellar granule cells and astrocytes.

Amino Acids↗
PubMed1987

The proteoglycan chondroitin sulfate is present in a subpopulation of cultured astrocytes and in their precursors.

We have used an antibody raised against the bovine nasal cartilage proteoglycan chondroitin sulfate (CS) digested with chondroitinase ABC (anti-CS serum) to stain cerebellar glial cells maintained in culture. In cultures grown in the presence of serum, the antibody stained a subclass of GFAP+ astrocytes which we have previously shown to selectively bind the monoclonal antibodies A2B5 and LB1. Also the direct bipotential precursors of these cells, capable of differentiating into GFAP+ astrocytes or into Gal-C+, O1+ oligodendrocytes depending on the culture conditions, were stained, but stopped to produce CS when they differentiated into oligodendrocytes.

Animals↗
PubMed1987

Glutamate receptor subtypes in cultured cerebellar neurons: modulation of glutamate and gamma-aminobutyric acid release.

Using cerebellar, neuron-enriched primary cultures, we have studied the glutamate receptor subtypes coupled to neurotransmitter amino acid release. Acute exposure of the cultures to micromolar concentrations of kainate and quisqualate stimulated D-[3H]aspartate release, whereas N-methyl-D-aspartate, as well as dihydrokainic acid, were ineffective. The effect of kainic acid was concentration dependent in the concentration range of 20-100 microM. Quisqualic acid was effective at lower concentrations, with maximal releasing activity at about 50 microM. Kainate and dihydrokainate (20-100 microM) inhibited the initial rate of D-[3H]aspartate uptake into cultured granule cells, whereas quisqualate and N-methyl-DL-aspartate were ineffective. D-[3H]Aspartate uptake into confluent cerebellar astrocyte cultures was not affected by kainic acid. The stimulatory effect of kainic acid on D-[3H]aspartate release was Na+ independent, and partly Ca2+ dependent; the effect of quisqualate was Na+ and Ca2+ independent. Kynurenic acid (50-200 microM) and, to a lesser extent, 2,3-cis-piperidine dicarboxylic acid (100-200 microM) antagonized the stimulatory effect of kainate but not that of quisqualate. Kainic and quisqualic acid (20-100 microM) also stimulated gamma-[3H]-aminobutyric acid release from cerebellar cultures, and kynurenic acid antagonized the effect of kainate but not that of quisqualate. In conclusion, kainic acid and quisqualic acid appear to activate two different excitatory amino acid receptor subtypes, both coupled to neurotransmitter amino acid release. Moreover, kainate inhibits D-[3H]aspartate neuronal uptake by interfering with the acidic amino acid high-affinity transport system.

Animals↗
PubMed1987

The role of depolarization in the survival and differentiation of cerebellar granule cells in culture.

Cultures greatly enriched in granule cells from early postnatal cerebellum (P8) were grown in a medium containing fetal calf serum. Under the conditions used, nerve cells died, usually within a week, unless the K+ concentration in the medium was greater than or equal to 20 mM. The requirement for elevated [K+]e was manifested by about 3 d in vitro, and after this time continuous exposure to high [K+]e was essential for the survival of the granule cells. The initial morphological and biochemical maturation of the granule cells was similar in the presence and the absence of elevated [K+]e, suggesting that the dependence on depolarizing conditions develops in parallel with the expression of the differentiated characteristics of the cells. The positive effect of elevated [K+]e on granule cell survival was not influenced by preventing bioelectric activity in the cultures with TTX and xylocaine. On the other hand, depolarization-induced transmembrane Ca2+ flux was essential in securing the maintenance of the granule cells. Depolarized nerve cells were compromised when Ca2+ entry was blocked by elevated Mg2+, EGTA, or organic Ca2+ antagonists, while dihydropyridine Ca2+ agonists [BAY K 8644, (+)-(S)-202 79 1 and CGP 28392] were potent agents preventing nerve cell loss in the presence of 15 mM [K+]e, which was ineffective on its own. Calmodulin inhibitors (1 microM trifluoperazine or calmidazolium) blocked the beneficial effect of K+-induced depolarization on granule cells. The comparison of the timing of the differentiation and innervation of the postmitotic granule cells in vivo with the development of the K+ dependence in vitro would indicate that depolarization of the granule neurons in culture mimics the influence of the physiological stimulation in vivo through excitatory amino acid receptors, including N-methyl-D-aspartate receptors, involving Ca2+ entry and the activation of a Ca2+/calmodulin-dependent protein kinase.

Animals↗
PubMed1986

Kainic acid stimulates GABA release from a subpopulation of cerebellar astrocytes.

The effect of acute exposure to micromolar concentrations of kainic acid was studied in rat cerebellar astroglial cultures consisting of two antigenically and functionally distinct subpopulations of astrocytes. Kainate (20-100 microM) released [3H]GABA preaccumulated by A2B5-positive stellate astrocytes in a concentration-, Na+- and Ca2+-dependent way, and did not interfere with [3H]GABA transport. We hypothesize that kainate depolarizes this class of cells by activating cationic channels and that this results in an imbalance of GABAergic transmission.

Animals↗