Biomedical subjects

M Del Rio

Publications and source records attributed to M Del Rio.

At least 37 records · Page 2Linked to original sources

PubMed1998

Modulation of murine lymphocyte functions by sulfated cholecystokinin octapeptide.

The effects in vitro of the sulfated octapeptide form of cholecystokinin (CCK-8) at concentrations ranging from 10(-13) M to 10(-6) M on several functions of murine lymphocytes were studied, i.e. adherence to substrate, mobility (spontaneous and directed by chemical gradient or chemotaxis) and spontaneous and phytohemagglutinin (PHA)-mediated proliferation. Lymphocytes were obtained from peritoneal suspension as well as from axillary nodes, spleen and thymus of BALB/c mice. CCK-8, at concentrations from 10(-10) M to 10(-8) M, significantly inhibited the mobility capacity and the PHA-induced proliferation and increased the adherence and the spontaneous proliferation of lymphocytes. A dose-response relationship was observed, with a maximum effect on lymphocyte functions at 10(-10) M. In addition, CCK-8 induced a significant decrease in membrane and cytosol protein kinase C (PKC) activity in murine lymphocytes, as well as an increase of intracellular cyclic AMP levels. These results suggest that CCK-8 is a negative modulator of two important lymphocyte functions in the immune response, i.e. mobility and mitogen-induced proliferation, and that the PKC activity inhibition and cAMP increase could be the mechanisms through which CCK inhibits these lymphocyte activities.

Animals↗

PubMed1998

Changes with age in the modulation of natural killer activity of murine leukocytes by gastrin-releasing peptide, neuropeptide Y and sulfated cholecystokinin octapeptide.

Several investigations have suggested that the interactions between the nervous and immune systems are modified with age. The aim of the present work was to study the effect of three neuropeptides: gastrin-releasing peptide (GRP), neuropeptide Y (NPY) and sulfated cholecystokinin octapeptide (CCK-8 s) on natural killer (NK) activity of spleen, thymus and axillary node leukocytes from BALB/c male, young (8+/-1 weeks), adult (24+/-2 weeks) and old (72+/-2 weeks) mice. We used cells from murine lymphoma YAC-1 as targets for the cytotoxic assay and three physiological concentrations of the neuropeptides (10(-8), 10(-10) and 10(-12) M). In control samples, in the absence of neuropeptide, we observed a decreased NK activity in young and old mice with respect to the adults in the three organs studied. Regarding the effect of the neuropeptides, GRP stimulates the cytotoxic activity of leukocytes from all locations, in adult animals. At the same age, NPY also stimulates the NK activity of leukocytes from axillary nodes and thymus, whereas it decreases the NK activity of spleen leukocytes from young mice. CCK-8 s has an inhibitory effect on the axillary node leukocytes from young mice and spleen leukocytes from old animals. However, CCK-8 s increased the NK activity of thymus leukocytes from young and adult mice. The results indicate that the highest values of NK activity are found in adult mice, and that the stimulating effect of the three neuropeptides studied on NK activity of leukocytes from adult mice are reduced or disappeared, in general, in old as well as in young animals. Furthermore, the changes observed with ageing in the modulation of NK activity by the neuropeptides studied suggest an altered integration of the nervous and immune systems.

Aging↗

PubMed1998

Large surface of cultured human epithelium obtained on a dermal matrix based on live fibroblast-containing fibrin gels.

The aim of this study was to develop a new keratinocyte culture system on a dermal equivalent suitable for skin wound closure. Our dermal matrix is based on a fibrin gel from plasma cryoprecipitate containing live human fibroblast (from human foreskin). Keratinocytes obtained from primary culture according to the Rheinwald and Green method, were seeded on the gel at different seeding ratios. In all cases, the keratinocytes plated on the dermal equivalent grew to confluence and stratified epithelium was obtained within 10-15 days in culture. Early expression of basal membrane proteins was detected by immunostaining with laminin and type IV collagen antibodies. Cell proliferation was detected both in the epidermal layer and in the fibroblast embedded in the gel as assessed by BrdU incorporation. Detachment of composite cultures from dishes or flasks is a simple and quick procedure without the need for dispase treatment. Grafting of composite cultures to nude mice gave rise to an orderly stratified, orthokeratinized epithelium resembling human epidermis. A number of advantages including a large expansion factor without the need of 3T3 feeder layer, the availability of fibrin/plasma cryoprecipitate from blood banks and the versatile manipulation of composite cultures suggest that this system could be suitable for the definitive coverage of severely burned patients.

Adult↗

PubMed1998

Stimulated astrocytes release high-mobility group 1 protein, an inducer of LAN-5 neuroblastoma cell differentiation.

Stimulated astrocytes specifically release large amounts of high-mobility group 1 protein into the extracellular medium. The identity of the released protein has been established on the basis of its biological activity on murine erythroleukaemia cells and by its immunoreactivity against a specific monoclonal antibody. High-mobility group 1 protein also plays an essential role in differentiation of LAN-5 neuroblastoma cells which, following stimulation with retinoic acid, express high-mobility group 1 protein on to the external surface of the plasma membrane. In retinoic acid-induced LAN-5 cells, high-mobility group 1 protein is not secreted but is accumulated in a membrane-bound form, particularly at the level of neurite outgrowths. These cells can also be induced to differentiate by high-mobility group 1 protein coated on the surface of the cell culture vessels. The specific function of the protein in this process is indicated by inhibition of cell differentiation by an anti-high-mobility group 1 protein antibody. The data are consistent with a role of high-mobility group 1 protein in promoting cell-cell interactions and in the development of nerve tissues.

Animals↗

PubMed1998

Systemic long-term delivery of antibodies in immunocompetent animals using cellulose sulphate capsules containing antibody-producing cells.

Implantation of capsules containing antibody-producing cells into patients would potentially permit systemic long-term delivery of antibodies and might, thus, be useful in the development of surveillance treatments for cancers and severe viral diseases. We show that cellulose sulphate (CS) capsules containing hybridoma cells, when implanted subcutaneously or in the intraperitoneal cavity, can be used for delivering monoclonal antibodies into the blood-stream of immunocompetent mice for at least several months. In contrast to capsules implanted into the intraperitoneal cavity, which remain mobile and nonvascularized, capsules implanted under the skin form neo-organs which become vascularized within days. This may explain the higher blood concentration of the antibody we have observed in the latter case. Importantly, neither an isolating fibrosis nor an obvious inflammatory response was detected at the capsule implantation sites during observation periods as long as 10 months. Finally, no anti-idiotypic immune response against the ectopically delivered antibody was shown to occur. This rules out any potent adjuvant effect of the cellulose sulphate matrix that might have stimulated a neutralizing humoral response. Taken together, our data indicate that encapsulation of antibody-producing cells into CS might be used in antibody-based gene/cell therapy approaches.

Animals↗

PubMed1997

Inhibition of human neutrophil functions by sulfated and nonsulfated cholecystokinin octapeptides.

The effects of CCK-8s and desulfated CCK-8 at concentrations ranging from 10(-14) to 10(-6) M were studied in vitro on several functions of human peripheral neutrophils: adherence to substrate, mobility (spontaneous and directed by a chemical gradient or chemotaxis), ingestion of inert particles (latex beads) or cells (Candida albicans), and production of superoxide anion measured by the nitroblue tetrazolium reduction test. The effect of CCK-8s on intracellular levels of cAMP was investigated as well as the implication of calcium in the action of CCK-8s on phagocytic function using stimulants and inhibitors of both intracellular and extracellular calcium channels. The two peptides, at concentrations from 10(-12) to 10(-8) M, inhibited significantly both mobility and ingestion capacities and increased adherence to substrate. A dose-response relationship was observed with a maximum inhibition of neutrophil functions at 10(-10) M, CCK-8s and desulfated CCK-8 induced in these cells a significant, but transient, increase of cAMP levels at 60 s. Moreover, CCK-8s was found to inhibit completely the stimulation of latex bead phagocytosis in neutrophils produced by the calcium ionophore A23187. These results suggest that CCK-8 is a negative modulator of several neutrophil functions and that the inhibition of these activities could be carried out through an increase of the intracellular cAMP levels and a decrease of the extracellular calcium input.

Adult↗

PubMed1997

Action of elgodipine on atherosclerosis development, cell growth, and oncogene expression in vascular smooth muscle cells.

1. Elgodipine (ELG) had no significant effect on aortic content of cholesterol, plasma cholesterol, or triglycerides concentrations in cholesterol-fed rabbits. However, ELG administration produced a dose-dependent and significant reduction of calcium content of the aorta. 2. In vitro studies showed that ELG was able to inhibit vascular smooth muscle proliferation through a mechanism independent of the expression of the transcription factors c-fos and c-jun.

Animals↗

PubMed1996

Monoamine oxidase B expression is selectively regulated by dexamethasone in cultured rat astrocytes.

The influence of dexamethasone on monoamine oxidase (MAO) A and B expression and activity was investigated in primary cultures of rat type 1 astrocytes cultured under serum free, defined conditions. Dexamethasone treatment resulted in a dose- and time-dependent induction of MAO-B, but not of MAO-A, activity. The selective MAO-B increase was substantially reduced by the antagonist RU 486, thus suggesting a glucocorticoid receptor-mediated action of the hormone. Kinetic analysis showed an increase in Vmax of MAO-B with no change in apparent K(m). The dexamethasone-induced selective rise in MAO-B activity appeared to be due to enhanced enzyme synthesis, since MAO-B mRNA was markedly increased by dexamethasone treatment and the recovery of MAO-B activity after its irreversible inhibition by deprenyl was more pronounced in the presence than in the absence of the hormone. Furthermore, the dexamethasone effect was abolished by the protein synthesis inhibitors actinomycin D or cycloheximide. The present study demonstrates that dexamethasone is able to selectively induce MAO-B in type 1 astrocytes and leads to speculation of a possible role for glucocorticoids in the increase in brain MAO-B associated with neurodegenerative disorders, such as Parkinson's and Alzheimer's diseases.

Animals↗

PubMed1996

Influence of culture conditions on monoamine oxidase A and B activity in rat astrocytes.

Astroglial cells dispersed from newborn rat hemispheres were established in medium supplemented with 20 per cent fetal calf serum (FBS) and then grown to a confluent monolayer in the presence of 10 per cent FBS or charcoal-stripped FBS (CS). Type 1 astrocytes were subcultured and either maintained under the same conditions of the primary cultures or converted to serum-free chemically defined medium (CDM). No differences were found in either MAO A or MAO B activity of astrocytes grown in the presence of FBS or CS after 15 and 21 days in vitro (day 1 and 6 of subculture). In contrast, on day 21 both MAO A and MAO B activities were markedly higher in astrocytes subcultured in CDM compared with cells maintained in serum-supplemented medium. This difference appeared to be due to increased number of enzyme molecules, since kinetic analysis showed an increase in Vmax of both MAO isoenzymes in serum-free medium, but no change in Km. Consistently, the recovery of MAO A and MAO B activity after irreversible enzyme inhibition by clorgyline and deprenyl was faster in CDM than in FBS-supplemented medium, indicating enhanced enzyme synthesis under serum-free condition. Estimates of half-lives for the recovery of MAO A and MAO B activity indicated that, under both culture conditions, type A activity had a higher turnover rate than type B. The effect of CDM on astrocyte MAO does not appear to be due to selection of a subpopulation of cells, but rather linked to a morphological change (differentiation) with increased synthesis of both MAO isoenzymes.

Animals↗

PubMed1996

Action of probucol in arteries from normal and hypercholesterolaemic rabbits.

1. The effect of probucol on the vascular reactivity of different arteries isolated from rabbits was studied as well as its effects on the development of atherosclerosis in a cholesterol-fed rabbit model. 2. Probucol 10(-6)-5 x 10(-4)M produced a concentration-dependent inhibition of the contractile responses induced by KCI (80 mM), the sequence for the IC50 was: mesenteric artery (5th branch, 4.8 +/- 2.6 x 10(-5) M) > aorta (8.2 +/- 2.3 x 10(-5) M) > femoral artery (> 5 x 10(-4) M). The response to noradrenaline was: mesenteric artery (5th branch, 4.2 +/- 1.3 x 10(-5) M) > aorta (3.2 +/- 3.0 x 10(-4) M) > femoral (> 5 x 10(-4) M). 3. In the aorta, probucol (10(-5)-10(-4) M) shifted the concentration-response curves to Ca2+ downward and to the right. 4. Probucol at 5 x 10(-5) M and 5 x 10(-4) M showed a reduction in the 45Ca2+ uptake in resting, non-stimulated aortic rings as well as the uptake induced by both noradrenaline 10(-6) M and KCI 80 mM. 5. In experiments in vivo, probucol did not affect lipid profiles; however, drug-treatment significantly decreased the cholesterol content of aortic tissue and the extent of intimal surface covered with atherosclerotic lesions. 6. The vascular reactivity was recovered in femoral arteries from rabbits on the atherogenic diet plus probucol. 7. It is concluded that the effect of probucol in vascular smooth muscle can be attributed to an inhibition of Ca2+ entry through both potential- and receptor-operated pathways. Moreover our findings suggest that the effects of probucol on movement of calcium in vascular smooth muscle may play an important role in the mechanism of antiatherogenic properties of this drug.

Animals↗

PubMed1995

Stimulation of natural killer (NK) and antibody-dependent cellular cytotoxicity (ADCC) activities in murine leukocytes by bombesin-related peptides requires the presence of adherent cells.

Bombesin and the two mammalian bombesin-related peptides, gastrin-releasing peptide (GRP) and neuromedin C, at physiological concentrations have been previously shown to stimulate significantly in vitro the antibody-dependent cellular cytotoxicity (ADCC) and natural killer (NK) activities in BALB/c mouse leukocytes from axillary nodes, spleen and thymus. In the present work we have shown that adherent cells are required in leukocyte samples for stimulation of cytotoxicity by the neuropeptides, which suggests that this effect may be mediated by those cells. Here we demonstrate the specificity of the effects by reversing them in the presence of the bombesin-antagonist (Leu13-psi CH2NH-Leu14)-BN, and by detecting specific receptors for GRP on macrophages of high and low affinity. Using the same binding technics, no receptors for this neuropeptide were found in non-adherent leukocytes.

Animals↗

PubMed1995

Comparative study of elgodipine and nisoldipine on the contractile responses of various isolated blood vessels.

The effects of elgodipine, a new dihydropyridine derivative, were compared to those of nisoldipine on contractile responses in various isolated artery rings and on mechanical activity in portal vein segments. Arteries used were: rabbit aorta, mesenteric (fifth branch), femoral and basilar, and sheep coronary arteries. Elgodipine and nisoldipine (10(-16)-3 x 10(-6) M) produced a concentration-dependent inhibition of the contractile responses induced by high K+ (80 mM), 5-hydroxytryptamine (10(-5) M) or noradrenaline (10(-6) M or 10(-4) M) in all the arteries studied. The inhibitory effect of elgodipine was greater in mesenteric resistance vessels (IC50 = 8.0 +/- 2.1 x 10(-12) M and 2.0 +/- 0.5 x 10(-13) M for the depression of high K(+)- and agonist-induced contraction, respectively), and in coronary arteries (IC50 = 2.6 +/- 0.3 x 10(-10) M and 9.0 +/- 1.4 x 10(-8) M for the inhibition of high K(+)- and agonist-induced contraction, respectively). In addition, the action of elgodipine in peripheral resistance vessels and in the coronary artery was more prominent than in aorta or femoral arteries, and this tissue selectivity was more apparent for elgodipine than for nisoldipine. In rat portal vein elgodipine (IC50 = 6.5 +/- 0.9 x 10(-8) M) and nisoldipine (IC50 = 8.5 +/- 1.3 x 10(-8) M) reduced in a concentration-dependent manner the development of mechanical activity. Furthermore, contractile responses produced by the addition of Ca2+ (1-5 mM) to Ca(2+)-free high K+ solution were also concentration dependently inhibited by elgodipine. However, elgodipine did not modify noradrenaline-induced contractions attributed to intracellular Ca2+ release. The results of this study indicate that elgodipine has potent vasodilator properties and vascular selectivity. The mechanisms through which elgodipine relaxes vascular smooth fibres seem to be related to its ability to inhibit the entry of extracellular Ca2+ into the cell.

Animals↗

PubMed1995

Inhibition of murine peritoneal macrophage functions by sulfated cholecystokinin octapeptide.

The effect in vitro of the sulfated octapeptide form of cholecystokinin, CCK-8, at concentrations from 10(-12) M to 10(-6) M on several functions of resting peritoneal macrophages from BALB/c mice: adherence to substrate, mobility (spontaneous and directed by chemical gradient or chemotaxis), ingestion of inert particles (latex beads) or cells (Candida albicans), and production of superoxide anion measured by nitroblue tetrazolium reduction was studied. CCK-8, at concentrations from 10(-10) M to 10(-8) M, inhibited significantly all functions studied with the exception of adherence to substrate, which was increased. A dose-response relationship was observed, with a maximum inhibition of macrophage functions found at 10(-8) M. This neuropeptide induced in murine macrophages a significant, but transient, increase of cAMP levels at 60 sec. On the contrary, CCK-8 produced a slight but significant decrease of protein kinase C (PKC) activity at 5 min of incubation. These results suggest that CCK-8 is a negative modulator of several macrophage functions, and that the inhibition of these activities is carried out through an increase of intracellular cAMP levels and a decrease in PKC activity.

Animals↗

PubMed1995

Effects of indapamide on atherosclerosis development in cholesterol-fed rabbits.

We examined the effect of indapamide (IND) on the development of atherosclerosis lesions in rabbits maintained on a 1% (wt/wt) cholesterol-enriched diet for a 16-week period. IND was supplemented to the diet at three different levels to correspond to doses of 0.1, 0.3, and 1 mg/kg/day. Throughout the treatment, dietary consumption and body weight gains were comparable among the experimental and control groups. IND had no significant effect on plasma cholesterol, triglycerides, or phospholipids concentrations. Despite the lack of effect of the drug on these parameters, its administration produced a tendency toward a reduction in the aortic content of cholesterol and a dose-dependent and significant decrease in aortic damage. In the aortic arch, the extent of intimal aortic surface covered by grossly discernible atherosclerotic lesions was decreased by IND 1 mg/kg/day from 11.02 +/- 1.10 to 6.00 +/- 1.00% (p < 0.05) and from 9.72 +/- 1.39 to 5.37 +/- 1.20% (p < 0.05) in the remaining thoracic sections. In addition, the former dose also reduced the number of lesions per square centimeter from 3.69 +/- 0.68 to 1.72 +/- 0.53% (p < 0.05), and from 3.37 +/- 0.85 to 1.55 +/- 0.46% (p < 0.05) in aortic arch and in thoracic sections, respectively. The possibility that IND reduces the development of atherosclerotic lesions produced by diet-induced hypercholesterolemia through a mechanism involving its calcium antagonist and/or its antioxidant activity is discussed.

Administration, Oral↗

PubMed1995

Idiotypic restriction of murine monoclonal antibodies to a defined antigenic region of human thyroglobulin.

In previous studies, we demonstrated that anti-human thyroglobulin (hTg) autoantibodies in patients with thyroid disorders exhibit a restricted epitopic specificity towards antigenic region II defined by its reactivity with four murine monoclonal antibodies (mAb 3, 6, 10, 15). To analyze the relationships between epitopic specificity and idiotypic expression of these mAb, two polyclonal anti-idiotypic sera were generated in rabbits by immunization with F(ab')2 fragments of mAb 3 and mAb 10. These anti-idiotypic preparations (AI 3 and AI 10) were tested against a panel of hTg-mAb produced in different strains of mice (HR BIOZZI and BALB/c). The idiotypic analysis showed that AI 3 and AI 10 specifically recognized framework-associated idiotopes as well as paratope-associated idiotopes shared by region II mAb. These results demonstrate that specificity for region II was strongly associated with a restricted idiotype suggesting a high sequence homology between V regions. In addition, naïve BALB/c mice immunized with AI 3 or AI 10 produced anti-hTg (Ab3) antibodies that recognize region II epitopes. These latter findings reveal that anti-Id contain a population of Ab2 beta carrying the internal image of region II epitopes.

Animals↗

PubMed1994

Chemoattractant capacity of bombesin, gastrin-releasing peptide and neuromedin C is mediated through PKC activation in murine peritoneal leukocytes.

Bombesin-like peptides have been recently shown to regulate immune functions. In the present work, we have studied their action as chemoattractants for murine peritoneal macrophages and lymphocytes. The results showed a significant increase in the number of cells that migrate when they are exposed to a gradient of bombesin, gastrin-releasing peptide (GRP) or neuromedin C (from 10(-8) to 10(-12) M). The most effective of the three neuropeptides studied was GRP, even more than formyl-Met-Leu-Phe peptide (FMLP), an established leukocyte chemoattractant. GRP action was mediated through specific cell receptors as it was significantly reduced in presence of a competitive and specific bombesin receptor antagonist. In the presence of retinal, a protein kinase C (PKC) inhibitor, the chemoattractant capacity of GRP was considerably reduced. In order to investigate further the mechanism of action involved in the GRP effect, we measured PKC activity. Peritoneal cells incubated with GRP experimented an increase in PKC activity to the same extent of that produced by the PKC activator phorbol myristate acetate (PMA). These data prove that bombesin-like peptides are potent chemoattractants for murine peritoneal macrophages and lymphocytes, and that their action is at least in part mediated through PKC activation.

Analysis of Variance↗

PubMed1994

Bombesin, gastrin-releasing peptide, and neuromedin C modulate murine lymphocyte proliferation through adherent accessory cells and activate protein kinase C.

Recent data have shown the ability of bombesin-related peptides to stimulate murine macrophage functions. In the present study, we have investigated the effect of bombesin, gastrin-releasing peptide (GRP), and neuromedin C on the proliferative response of lymphocytes from murine axillary nodes, spleen, and thymus. The results show that these neuropeptides at 10(-9), 10(-10), and 10(-11) M concentrations modulate the lymphoproliferative response, stimulating to a small but significant extent the spontaneous proliferation and inhibiting to a great extent the lymphoproliferative response to the mitogen concanavalin A (Con A). This regulation is probably mediated through adherent accessory cells, since their presence for the neuropeptides to produce their effect. The increased interleukin-1 beta production by Con A in cultures of peritoneal macrophages (a model of adherent accessory cells) decreased after the addition of bombesin, GRP, and neuromedin C; this diminution is a possible mechanism for their inhibitory action on the lymphoproliferative response to Con A. In addition, these neuropeptides caused a significant protein kinase C activation in total leukocyte population and T-enriched lymphocytes from axillary nodes, as well as in peritoneal macrophages.

Animals↗

PubMed1993

Effects of indapamide on contractile responses and 45Ca2+ movements in various isolated blood vessels.

The effects of indapamide on contractile responses in various isolated artery rings and on spontaneous mechanical activity in portal vein segments were investigated. Arteries used were: rabbit aorta, mesenteric (fifth branch), femoral and basilar, and sheep coronary arteries. 45Ca2+ uptake was also analysed in rabbit mesenteric arteries. Indapamide (10(-10)-3 x 10(-4) M) produced a concentration-dependent inhibition of the contractile responses induced by high K+ (80 mM), 5-hydroxytryptamine (10(-5) M), and noradrenaline (10(-6) or 10(-4) M) in all the arteries studied. The inhibitory effect was greater in mesenteric (fifth branch) the IC50 values being 9.2 +/- 3.0 x 10(-6) and 5.5 +/- 4.0 x 10(-8) M for depression of high K(+)- and agonist-induced contractions, respectively. Indapamide inhibited in a concentration-dependent manner the contractile responses elicited by the addition of Ca2+ (1-5 mM) to Ca(2+)-free high K+ solution as well as the spontaneous mechanical activity of rat portal vein. Indapamide also reduced the 45Ca2+ uptake in rabbit mesenteric arteries stimulated by noradrenaline (10(-4) M) or by high K+ (80 mM) without affecting the Ca2+ influx in resting tissues. Our results indicate that indapamide blocked both depolarization-and noradrenaline-induced Ca2+ influx while it did not modify passive Ca2+ entry. Peripheral resistance vessels were demonstrated to be the arteries most sensitive to indapamide vascular effects.

Animals↗