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Biomedical subjects

C Rodríguez

Publications and source records attributed to C Rodríguez.

At least 91 records · Page 5Linked to original sources
PubMed2000

Regulation of immunoglobulin secretion by plasma cells infiltrating nasal polyps.

OBJECTIVE/HYPOTHESIS: To learn more about the role of plasma cells infiltrating nasal polyps in the pathogenesis of nasal polyposis, we examined their function by analyzing immunoglobulin (Ig) production and the factors implicated in the secretion. STUDY DESIGN: A series of 19 consecutive nasal polyp tissue samples and, as a control, peripheral blood samples from the same patients, were studied by histopathological and immunological examination. METHODS: Hematoxylin-eosin and immunohistochemical staining was carried out to identify plasma cells infiltrating nasal polyps. Nasal polyp mononuclear cells (NPMNCs) were purified from nasal polyp tissue samples, and Ig-secreting cells were identified in cytospin preparations stained with fluorescein isothiocyanate-conjugated antibodies against IgA, IgG, IgM, and IgE. Purified NPMNCs were cultured in basal conditions and after the addition of several stimuli. Ig secreted into the culture supernatants was evaluated by an enzyme-linked immunosorbent assay. RESULTS: Plasma cells accounted for an important fraction of the inflammatory infiltrate. The main Ig isotype synthesized by these cells was IgA, whereas little IgE was detected. In vitro cultures demonstrated that the plasma cells actively secreted Ig for a short period. When cytokine dependence was analyzed, interleukin-10 (IL-10) and tumor necrosis factor-alpha (TNF-alpha) were shown to be partially responsible for the Ig production. Dependence on CD95-mediated apoptosis was not observed. CONCLUSIONS: Nasal polyp-infiltrating plasma cells are mainly IgA-secreting cells, the latter property being related to the mucosal immune system. The IgA production is partly dependent on IL-10 and TNF-alpha. The absence of IgE-secreting cells in most of the samples suggests that a type I hypersensitivity reaction is not essential for the development of nasal polyp.

Adolescent↗
PubMed2000

Carbohydrate and energy-yielding metabolism in non-conventional yeasts.

Sugars are excellent carbon sources for all yeasts. Since a vast amount of information is available on the components of the pathways of sugar utilization in Saccharomyces cerevisiae it has been tacitly assumed that other yeasts use sugars in the same way. However, although the pathways of sugar utilization follow the same theme in all yeasts, important biochemical and genetic variations on it exist. Basically, in most non-conventional yeasts, in contrast to S. cerevisiae, respiration in the presence of oxygen is prominent for the use of sugars. This review provides comparative information on the different steps of the fundamental pathways of sugar utilization in non-conventional yeasts: glycolysis, fermentation, tricarboxylic acid cycle, pentose phosphate pathway and respiration. We consider also gluconeogenesis and, briefly, catabolite repression. We have centered our attention in the genera Kluyveromyces, Candida, Pichia, Yarrowia and Schizosaccharomyces, although occasional reference to other genera is made. The review shows that basic knowledge is missing on many components of these pathways and also that studies on regulation of critical steps are scarce. Information on these points would be important to generate genetically engineered yeast strains for certain industrial uses.

Carbohydrate Metabolism↗
PubMed2000

Differences in the formation of PPARalpha-RXR/acoPPRE complexes between responsive and nonresponsive species upon fibrate administration.

Peroxisome proliferator-activated receptor-alpha (PPARalpha) is responsible for the hypolipidemic, peroxisome proliferation and carcinogenic effects of fibrates. Rats and mice are responsive, but guinea pigs and primates are resistant to the proliferative and carcinogenic effects of these drugs, but the hypolipidemic effect is still manifest. It is not yet clear whether humans should be considered unresponsive, and there is concern about the long-term safety of fibrates. We present molecular evidence for the reported resistance of human cells to peroxisome proliferation by describing a deficient interaction of nuclear extracts from human cells with an acyl-CoA oxidase (ACO)-peroxisome proliferator response element probe upon fibrate addition. Electrophoretic mobility shift assay analysis showed that ciprofibrate elicited a concentration-dependent increase in the binding of nuclear extracts from cells of rat (Morris) and human (HepG2) origin to an ACO-peroxisome proliferator response element probe, although in HepG2 cells the increase was of marginal statistical significance. In Morris cells, the increase was more marked than in HepG2 cells (4-fold versus 1.5-fold at 0.2 mM ciprofibrate), and maximal binding was achieved earlier in Morris (30 min) than in HepG2 cells (3 h). Morris cells responded to the addition of ciprofibrate by increasing the levels of ACO mRNA, whereas HepG2 did not. The ratio between PPARbeta/PPARalpha mRNAs was higher in HepG2 cells than in Morris cells (3.2 versus 1.9), pointing to an antagonizing effect of PPARbeta on PPARalpha activity. These results were obtained in untransfected cells expressing their own basal set of receptors. We also provide evidence of the translocation of PPARalpha from the cytosol to the nucleus upon activation by ciprofibrate.

Acyl-CoA Oxidase↗
PubMed2000

Isolation of the MIG1 gene from Candida albicans and effects of its disruption on catabolite repression.

We have cloned a Candida albicans gene (CaMIG1) that encodes a protein homologous to the DNA-binding protein Mig1 from Saccharomyces cerevisiae (ScMig1). The C. albicans Mig1 protein (CaMig1) differs from ScMig1, in that, among other things, it lacks a putative phosphorylation site for Snf1 and presents several long stretches rich in glutamine or in asparagine, serine, and threonine and has the effector domain located at some distance (50 amino acids) from the carboxy terminus. Expression of CaMIG1 was low and was similar in glucose-, sucrose-, or ethanol-containing media. Disruption of the two CaMIG1 genomic copies had no effect in filamentation or infectivity. Levels of a glucose-repressible alpha-glucosidase, implicated in both sucrose and maltose utilization, were similar in wild-type or mig1/mig1 cells. Disruption of CaMIG1 had also no effect on the expression of the glucose-repressed gene CaGAL1. CaMIG1 was functional in S. cerevisiae, as judged by its ability to suppress the phenotypes produced by mig1 or tps1 mutations. In addition, CaMig1 formed specific complexes with the URS1 region of the S. cerevisiae FBP1 gene. The existence of a possible functional analogue of CaMIG1 in C. albicans was suggested by the results of band shift experiments.

Amino Acid Sequence↗
PubMed2000

Influence of human wet cerumen on the growth of common and pathogenic bacteria of the ear.

The available data on the effect of human wet cerumen on bacterial growth are not conclusive. Nevertheless it is widely accepted that cerumen has a bactericidal effect. In this study the activity of human wet cerumen on bacterial growth was assessed by applying cerumen suspensions to bacterial cultures. Bacterial counts were performed before and after application of cerumen suspensions. A total of 383 assays was carried out with 73 pools of cerumen that were tested against cultures of Staphylococcus aureus, Staphylococcus epidermidis, Corynebacterium spp., Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa and Serratia marcescens. An increase in growth occurred much more frequently than a decrease in growth in almost every microrganism tested, with the mean increase percentage being much higher than the mean decrease percentage, except in the case of S. aureus. The largest average growth increase was obtained with E. coli. The largest average decrease in bacterial growth was recorded with S. marcescens. Our study does not support the conception of a decrease in bacterial growth produced by humen wet cerumen. In vitro, the most observable effect was in fact an increase in microbial growth.

Adolescent↗
PubMed2000

[The prolonged administration of intravenous immunoglobulins as a treatment for refractory fistulous Crohn's diseases].

Fistulating Crohn's disease is present in 17-35% of non-surgically treated patients and in up to 45% of surgically treated ones. Among the several therapeutic alternatives for this disease is intravenous immunoglobulin administration. We present a 28-year-old woman with refractory fistulating Crohn's disease who improved after prolonged immunoglobulin administration (32 months).

Adult↗
PubMed2000

[Invasive hepatosplenic hyalohyphomycosis. Report of a case].

Invasive fungal infections are an increasingly common problem in patients with cancer and other vulnerable groups. We report a case of hepatosplenic hialohifomycosis probably by Aspergillus sp. In a patient with acute leukemia, and prolonged neutropenia, treated with corticosteroids and broad spectrum antibiotics. A review concerning diagnosis, clinical course and treatment of this condition is presented.

Acute Disease↗
PubMed2000

[Current clinical immunology: a genetic and molecular perspective].

During the last few decades, basic scientists and clinicians have gained a deeper insight of the cellular and molecular physiology of the immune system. The widespread application of molecular biology and genetic techniques has advanced our understanding of states of health and disease, bringing forth renewed hopes concerning the advent of a more "specific" therapeutic era of clinical immunology. The precise structural and genetic characterization of molecular complexes such as B and T-cell receptors, the Major Histocompatibility Complex (MHC), cytokines, chemokines, cellular receptors and co-receptors has produced a wealth of information open to both diagnostic and therapeutic purposes. We herein review several recent advances in the molecular and genetic characterization of immune deficiency states, autoimmunity and the induction of antigen specific immune unresponsiveness or tolerance, together with the therapeutic implications of these findings.

Adenosine Deaminase↗
PubMed2000

[Benthic fauna associated to a Thalassia testudinum (Hydrocharitaceae) bed in Parque Nacional Morrocoy, Venezuela].

The benthic fauna and diel variation in a shallow seagrass bed (Thalassia testudinum) were studied in Playa Mero, Venezuela. Samples of organisms and sediments were taken using PVC cylinders, 5cm in diameter, along a transect perpendicular to the coast. Seagrass cover, shoot density and biomass were estimated. The seagrass cover was homogeneous along the transect. The intermediate zone had the highest number of shoots and of above-ground and rhizome biomass. Composition and abundance of benthic organisms were related with seagrass and sediment characteristics. Sediment organic matter content and organism abundance were highest near the shore Molluscs, polychaetes, oligochaetes and nematodes were the most abundant groups. Species richness was higher in daytime (40 versus 28 at night). Gastropods were the most abundant organisms both at day and night while polychaetes and crustaceans increased during the day, and holoturids were more numerous at night.

Animals↗
PubMed1999

Surface molecule loss and bleb formation by human germinal center B cells undergoing apoptosis: role of apoptotic blebs in monocyte chemotaxis.

Human tonsil germinal center (GC) B cells rapidly undergo apoptosis in culture. Annexin-V binding shows an early event in this process. In the present study, this method has been used to label apoptotic GC B cells and to analyze additional surface molecules. The expression of all of the molecules studied was reduced in apoptotic (annexin-V(+)) GC B cells, and the reduction was more marked for CD11a, CD21, CD22, CD49d, and CD54, molecules that participate in survival interaction for GC B cells. The analysis of CD54, one of the molecules that was more drastically reduced, showed that GC, but not mantle zone, B cells actively secrete CD54 to the culture supernatant (SN). The secreted CD54 was partly released from the GC B cells in a particulate form as demonstrated by centrifugation. Further experiments using filtration, fluorescence microscopy, electron microscopy, and flow cytometry analysis showed that GC B cells released to the culture SN a population of spherical membranous vesicles of about 0.18 micrometers in size, similar to the blebs described in other apoptosis systems. Bleb formation depended on active metabolism, Ca(2+), and, in part, on microfilament integrity. GC B-cell-derived blebs were clearly associated with apoptosis, as antiapoptotic stimuli prevented their formation. In addition, GC B-cell-derived blebs contained the adhesion molecules previously studied. Consequently, bleb formation might contribute to the surface molecule loss occurring in apoptotic GC B cells. Finally, a chemotaxis assay showed that GC B-cell blebs were chemotactic for human monocytes, suggesting that this mechanism might operate in vivo.

Antigens, CD↗
PubMed1999

[Reconstitution of peripheral blood lymphocytes in patients treated with bone marrow transplantation: comparison between allogeneic and autologous transplantation].

BACKGROUND: This study compares the immune reconstitution of total T cells, CD4 and CD8 cell subsets, activated T cells, NK cells and B cells in 66 patients who underwent allogeneic or autologous bone marrow transplantation (BMT). PATIENTS, MATERIAL AND METHODS: The reconstitution of peripheral lymphocytes subsets was studied using two-color flow cytometry. The study group consisted of 39 patients who received allogeneic BMT compared with 27 patients who received autologous BMT. Peripheral blood was examined at different time intervals. As a measure of immune function, the response to the mitogen phytohemaglutinin (PHA) was determined. RESULTS: The pattern of recovery of CD3+, CD4+ and CD8+ T cells, as well as the PHA response, was similar for each type of transplant. CD3+CD5- cells were significantly higher following autologous BMT than after allogeneic BMT and during more time. An overexpression of DR on T cells following autologous or allogeneic BMT demonstrates an increasing degree of T-lymphocyte activation. This activated T-cell subset was more stable in patients transplanted with allogeneic BM than in patients treated with autologous BM. The levels of total B cells and CD19+CD5+ B-cells were increased during 2 to 12 months following autologous MBT, remaining normal afterwards; in contrast, the levels of CD19+ lymphocytes and CD19+CD5+B-cells remained higher than normal ranges until 36 months in patients transplanted with allogeneic BM. The percentage of NK cells was significantly increased following both autologous and allogeneic BMT. The highest percentage of NK cells were detected about 2 and 6 months post-transplant in patients treated with autologous or allogeneic BM, respectively. CONCLUSIONS: Allogeneic BMT appears to induce a slight delay recovery of B and NK cells in comparison to autologous BMT. In contrast, T-cells recovery was similar for each type of transplant, although a higher percentage of CD3+CD5- T cells and a faster recovery of activated CD3+DR+ cells to normal levels were observed in patients transplanted with autologous BM.

Adolescent↗
PubMed1999

Glucose signaling in yeast is partially mimicked by galactose and does not require the Tps1 protein.

Glucose produces multiple effects in Saccharomyces cerevisiae, as it controls the expression of many genes and the activity of various enzymes. However, the elements involved in glucose signaling are not well characterized. In this work the capacity of galactose to bring about the same effects than glucose has been assessed. Galactose mimics glucose only partially; it is suggested that it does not interact with a "sensor" in the plasma membrane and that it produces a weaker intracellular signal than glucose. To examine whether trehalose-6P synthase (Tps1) is required to transduce the glucose signal, we have constructed a tps1 hxk2/tps1 HXK2 strain which, at difference of a tps1 strain, grows on glucose, and, at difference of a tps1 hxk2 strain, still possess the Hxk2 protein, possibly involved in glucose repression. From the response of this strain to glucose, we conclude that Tps1 does not play a prominent role in glucose signaling.

Cyclic AMP↗
PubMed1999

Lipoid proteinosis. A biochemical and ultrastructural investigation of two new cases.

Lipoid proteinosis is a rare autosomal recessive disease characterized by cutaneous and visceral lesions, in which large amounts of amorphous material are constantly found in stroma. Morphological and biochemical studies indicate abnormal collagen production, but little attention has been paid to the lipid component of lesions. Microscopic and ultrastructural studies of skin, with special emphasis on fibroblasts, vessels, nerve endings and eccrine sweat glands, were conducted in two patients with lipoid proteinosis. Biochemical studies were undertaken in cultured fibroblasts. Evidence of lysosomal storage in epithelial cells of eccrine sweat glands and in dermal histiocytes, very similar to that found in some metabolic disorders, particularly Farber disease, was found in both cases. Our findings suggest that two alterations might coexist in lipoid proteinosis, one characterized by impaired normal collagen production and the other related to a metabolic defect which may lead to accumulation of ceramide or more complex lipids.

Adult↗
PubMed1999

Involvement of cyclic GMP-dependent mechanism in the nitrergic relaxation of the bovine oesophageal groove.

1. The present study was designed to investigate the mechanisms involved in the relaxations to nitric oxide (NO) of bovine oesophageal groove preparations suspended in organ baths for isometric tension recordings. In preparations treated with guanethidine (10(-5) M) and atropine (10(-7) M) to block adrenergic neurotransmission and muscarinic receptors, respectively, NO released from nitrergic nerves by electrical field stimulation (EFS, 0.5-16 Hz, 1 ms duration, 20 s trains) and exogenously applied as an acidified solution of sodium nitrite (NaNO2, 10(-6)-10(-3) M) caused frequency-and dose-dependent relaxations of noradrenaline (NA, 10(-5) M)-precontracted preparations. 2. Incubation with an inhibitor of NO-stimulated soluble guanylate cyclase, 1H-[1,2,4]oxadiazolo[4,3,-a]quinoxalin-1-one (ODQ, 3 x 10(-6) M, for 30 min) did not change the basal tension of oesophageal groove strips but inhibited relaxations to EFS and to exogenous NO. 3. Treatment with iberiotoxin (10(-7) M) and apamin (5 x 10(-7) M), which are blockers of large and small conductance Ca2+-activated K+ channels, respectively, did not modify basal tension or the relaxations induced by EFS and exogenous NO. Incubation with iberiotoxin (10(-7) M) or apamin (5 x 10(-7) M) plus ODQ (3 x 10(-6) M) significantly reduced the relaxations to EFS and exogenous NO. However, in both cases the reductions were similar to the inhibition caused by ODQ alone. The combined addition of charybdotoxin (3 x 10(-8) M) and apamin (5 x 10(-7) M) did not change relaxations to EFS or exogenous NO of the bovine oesophageal groove. 4. The blocker of ATP-sensitive K+ channels, glibenclamide (10(-6) M), had no effect on either resting tension or relaxations induced by both EFS and exogenous NO. Combined treatment with ODQ (3 x 10(-6) M) and glibenclamide (10(-6) M) did not produce additional inhibition compared to ODQ alone. 5. The present results indicate that NO acts as an inhibitory neurotransmitter by relaxing bovine oesophageal groove smooth muscle through a guanylate cyclase-dependent mechanism which does not appear to involve the opening of K+ channels.

Adrenergic Agents↗
PubMed1999

Pharmacokinetics of indomethacin after intraruminal administration to sheep.

The pharmacokinetics of indomethacin (7 mg/kg) was determined in six adult sheep after intraruminal administration. The plasma concentration-time curves showed different patterns for each sheep, depending on the physiological state of the gastrointestinal tract, where absorption took place, and possible enterohepatic and saliva recycling. Indomethacin was irregularly and poorly absorbed from the rumen after intraruminal administration to sheep. Plasma concentrations barely rose to the lower therapeutic margin and mean bioavailability was 38.25 +/- 15.98%. The elimination phase was slow (beta = 0.015 +/- 0.010 h-1) and the half-life was long (t1/2 beta = 56.52 +/- 31.21 h). The mean residence time was 20.01 +/- 6.92 h.

Animals↗
PubMed1999

Temporal and spatial variation of inversion polymorphism in two natural populations of Drosophila buzzatii.

The inversion polymorphism of the cactophilic fly Drosophila buzzatii was studied in two natural populations. We assessed the temporal changes and microspatial population structure. We observed a significant increase in the frequency of arrangement 2J at the expense of 2ST in both populations. These gene arrangements appear to affect the life-history of flies differently. Environmental heterogeneity explains the karyotype coexistence in nature. The analysis of population structure showed that differentiation of inversion frequencies among individual breeding sites, the rotting clacodes of Opuntia vulgaris, was highly significant. The karyotypic frequencies did not depart significantly from Hardy-Weinberg expectations, neither in individual rots nor in the total population. These results suggest that the observed population structure can be easily accounted by random genetic drift.

Animals↗