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Biomedical subjects

R Rodríguez

Publications and source records attributed to R Rodríguez.

At least 109 records · Page 6Linked to original sources
PubMed1999

Simultaneous involvement of the jejunum and the colon by type-1 neurofibromatosis.

Type-1 neurofibromatosis (NF-1) or Von Recklinghausen disease is an autosomal dominant hereditary condition that may affect the gastrointestinal tract in 25% of cases and which takes three main forms: ganglioneuromatosis, stromal tumors, and tumors in the duodenum and periampullar region. Not infrequently, these patients present with gastrointestinal bleeding. We present the case of a 48-year-old patient diagnosed as having NF-1, with relapsing episodes of gastrointestinal hemorrhage, in which we discovered the simultaneous presence of a stromal tumor in the jejunum together with polypoid and diffuse ganglioneuromatosis in the colon.

Colon↗
PubMed1999

Neural contribution to the effect of glucagon-like peptide-1-(7-36) amide on arterial blood pressure in rats.

This study was designed to determine the contribution of the central nervous system (CNS) to the effects of glucagon-like peptide-1-(7-36) amide (tGLP-1) on arterial blood pressure and heart rate in rats. Accordingly, intracerebroventricular administration of the peptide produced an increase in cardiovascular parameters, which was blocked by previous administration of exendin-(9-39) through the same route, but not when it was intravenously injected. Intravenous administration of tGLP-1 produced a significant increase in arterial blood pressure and heart rate, which was blocked by the previous intracerebroventricular or intravenous administration of exendin-(9-39). Bilateral vagotomy blocked the stimulating effect of intracerebroventricular tGLP-1 administration on arterial blood pressure and heart rate. Also, bilateral vagotomy prevented the blocking effect of intracerebroventricular but not of intravenous exendin-(9-39) on cardiovascular parameters after intravenous administration of tGLP-1. These findings suggest that the action of tGLP-1 on cardiovascular parameters is under a dual control generated in the CNS and in peripheral structures and that the neural information emerging in the brain is transmitted to the periphery through the vagus nerve.

Animals↗
PubMed1999

Vinorelbine and paclitaxel as first-line chemotherapy in metastatic breast cancer.

PURPOSE: To evaluate the efficacy and toxicity of a combination of vinorelbine (VNB) and paclitaxel (PTX) as first-line chemotherapy in metastatic breast carcinoma (MBC). PATIENTS AND METHODS: Between August 1995 and August 1997, 49 patients with untreated MBC received a regimen that consisted of VNB 30 mg/m2 in a 20-minute intravenous (IV) infusion on days 1 and 8 and PTX 135 mg/m2 in a 3-hour IV infusion (starting 1 hour after VNB) on day 1. Cycles were repeated every 28 days. The median age of the patients was 52 years, and 59% of patients were postmenopausal. Median performance status was 1. Dominant sites of disease were soft tissue in 6%, bone in 29%, and viscera in 65%. RESULTS: Objective responses were recorded in 27 of 45 assessable patients (60%; 95% confidence interval, 46% to 74%). Complete remissions occurred in three patients (7%), and partial remissions occurred in 24 patients (53%). No change was recorded in 12 patients (27%), and progressive disease occurred in six patients (13%). The median time to treatment failure was 7 months, and median survival duration was 17 months. The limiting toxicity was myelosuppression, mainly leukopenia in 49 patients (100%) (grade 1 to grade 2, four patients; grade 3, 30 patients; and grade 4, 15 patients). Neutropenia was observed in 100% of patients (grade 1 to grade 2, three patients; grade 3, 11 patients; grade 4, 35 patients). Two treatment-related deaths due to febrile neutropenia were observed in patients with massive liver involvement. Peripheral neurotoxicity developed in 33 patients (67%) (grade 1, 25 patients; grade 2, eight patients); there were no grade 3 or grade 4 episodes. CONCLUSION: The combination of VNB-PTX showed significant activity as first-line chemotherapy for patients with MBC. Myelosuppression was the dose-limiting side effect, whereas neurotoxicity was mild to moderate.

Adult↗
PubMed1999

The major olive pollen allergen (Ole e I) shows both gametophytic and sporophytic expression during anther development, and its synthesis and storage takes place in the RER.

The distribution of Ole e I (the major olive pollen allergen) and its transcripts was investigated in the anther from premeiotic stages until the dehiscent pollen stage. Crude protein extracts were analyzed by immunoblotting and probed with a monoclonal antibody to Ole e I. The protein, with three variants, was found to accumulate from the early microspore stage onwards. In addition to the previously reported localization of the protein, Ole e I has been immunolocalized for the first time within the pollen wall and in the tapetum. Reverse transcription-polymerase chain reaction analysis using specific oligonucleotides and RNA extracted from whole anthers revealed that the Ole e I gene is expressed from the late tetrad stage onwards. No expression was found in control tissues such as petals, roots or leaves. Light microscopy in situ hybridization on developing flower buds and dehiscent pollen confirmed the transcripts to be present in both the microspores and the sporophytic tissue (tapetum). Labeling was found primarily in the tapetum, reaching the highest concentration in the cytoplasm of the developing and mature pollen, once tapetum started to degenerate. In situ hybridization at the transmission electron microscope level showed the transcripts to accumulate on ribosomes of the rough endoplasmic reticulum. These studies, together with others carried out previously by us, indicated that both synthesis and storage of Ole e I take place in the endoplasmic reticulum, coincidentally with the conspicuous changes suffered by this membrane system during pollen development. This process is most likely controlled at the transcriptional level. The localization of the protein in the pollen ectexine bring new insights into the function of the allergen, which are discussed.

Allergens↗
PubMed1999

[Importance of the benzylpenicillin nucleus and the side chain of the beta-lactams. Demonstration by skin tests and RAST in penicillin allergic patients].

We studied 30 patients with beta-Lactams allergy demonstrated by clinical findings. The aim of this work was to determine the capacity of the beta-Lactams nucleus and the side chain in the induction of specific IgE to BPO, Ax, Amp, performed by intradermal skin test and RAST. The patients were divided by clinical manifestations in: 1-Accelerated reactions (n:19); and 2-Immediate reactions (n:11). The Prick tests were performed with BPO-PL, Ax-PL, Amp-PL, MDM-BP, MDM-Ax, MDM-Amp. The accelerated group presented BPO-PL (+) in 2 cases, Ax-PL & Amp-PL (+) in 4 cases, and all of the reactives were (+) in 13 out of 19 cases. The immediate group presented MDM-BP (+) in 10 out of 11 cases and MDM-Amp was (+) in 1 out of 11 cases. The RAST's were performed in all patients(n:30). In accelerated group were (+) to BPO-PL in 13 out of 19 cases, to Ax-PL in 3 out of 19 cases, to Amp-PL in 1 out 19 cases, to BPO-PL and Ax-PL on overlap in 1 out of 19 cases, and 1 case was negative to all reactives. The immediate group presented RAST's negatives in 11 out of 11 cases. The control group(n:20) presented Prick (+) to Ax-PL in 1 out of 20 cases, and the others reactives were negatives in all cases. The RAST's to all reactives were (-) in 20 out of 20 subjects. These results indicate that BPO was the most important determinant, and the side chain of the Ax or Amp were others determinants of the beta-Lactams drugs. These determinants induced specific IgE, and in rare occasions appears specific IgE for two different determinants on overlap in the same patient. The intradermal skin testing is the method of choice to study the penicillin allergies, because non satisfactory RAST's have yet been developed for minor determinant-specific IgE antibodies.

Adult↗
PubMed1998

Molecular cloning and expression of active Ole e 3, a major allergen from olive-tree pollen and member of a novel family of Ca2+-binding proteins (polcalcins) involved in allergy.

A cDNA encoding Ole e 3, a major allergen from olive-tree pollen, has been cloned and sequenced. A strategy based on two-step PCR amplification towards the 5' end and 3' end, with an internal specific primer, has been used. The isolated cDNA contains an open reading frame coding for a polypeptide of 84 amino acids, which is in agreement with the composition and molecular mass of the natural allergen, exhibiting two 12-residue segments homologous to Ca2+-binding sites of EF-hand type. The cDNA was inserted into the pET-11b expression vector and over-expressed in Escherichia coli. The purified recombinant protein shows identical secondary structure to that of the natural allergen and is able to bind both IgE from sera of patients allergic to olive pollen and polyclonal antibodies raised against olive-pollen Ole e 3. The capacity of binding Ca2+ has been demonstrated for both natural and recombinant allergens. RNA transcripts of Ole e 3 were only detected in pollen tissue. Northern-blot and Western-blot analyses of poly(A)+ RNA and protein extracts, respectively, obtained from a variety of olive-tree-related and nonrelated mature pollens demonstrated the presence of Ole e 3 homologous proteins. This indicates a sequence conservation and widespread distribution for this family of Ca2+-binding proteins that can be responsible for allergenic cross-reactivity. We suggest the tentative generic name of polcalcins for the members of this family of Ca2+-binding proteins from pollen.

Allergens↗
PubMed1998

[Usefulness of anti-neutrophil cytoplasmic antibodies, anti-proteinase 3 and anti-myeloperoxidase in management of small vessel vasculitis].

BACKGROUND: Analysis of usefulness of antineutrophil cytoplasmic antibodies (AN-CA) as a marker of clinical activity in small vessel vasculitis. PATIENTS AND METHODS: 33 patients, 10 patients with Wegener's granulomatosis (WG) and 23 with microscopic polyangiitis (MPA) and rapidly progressive glomerulonephritis type III (RPGN III). The clinic and serologic follow-up was accomplished every 3 months during an average of 19 (SD, 24) months (range 3-52 months. The serologic follow-up included the determination of ANCA by indirect immunofluorescence (IFI) and ELISA, as well as the serum level of C reactive protein (RCP). RESULTS: At the time of diagnosis all patients were ANCA positive by IFI and ELISA. The seroconversion of ANCA from positive to negative was produced in 30/33 patients (90%). Twenty-six out of these 30 patients (87%) achieved the seroconversion within the first 6 months. During the follow-up 4 patients had a major relapse, all with positive ANCA. In 2 patients, one of each group, seroconversion from negative to positive was not associated with clinical relapse of vasculitis. CONCLUSION: ANCA should be used in conjunction with other indices of disease activity in patients with small vessel vasculitis.

Adult↗
PubMed1998

The mouse tumor necrosis factor receptor 2 gene: genomic structure and characterization of the two transcripts.

The mouse TNFR2 gene has been cloned, sequenced, and characterized as a gene spanning >44 kb of the genome. By alignment of five genomic clones we have established that TNFR2 consists of 10 exons and 9 introns with exons ranging in size from 35 bp to 2.6 kb and introns ranging from 322 bp to >16 kb. All splice acceptor and donor sites conform to the canonical AG/GT rule. The translation initiation and termination sites are located in exon 1 and 10, respectively. Although TNFR2 lacks a canonical TATA box, the gene is transcribed from a unique start site located 70 bp upstream of the ATG initiation codon that conforms to the consensus Inr motif. Several cis-elements for transcription factors were identified in the 5' flanking region, including NF-1, Sp-1, AP2, gamma-IRE, and NF-kappaBeta motifs. Functional analysis indicates that the region -705/-412 contains a negative cis-acting element and that the minimal promoter contains motifs that confer LPS inducibility. Two mouse TNFR2 mRNAs of 3.2 and 4.1 kb are detected by Northern blot analysis, but until now their origin has not been explained. No evidence of alternative splicing of the coding exons was found. However, hybridization studies and amplification of cDNA ends suggest the use of a noncanonical polyadenylation signal in the untranslated region of exon 10. A comparative analysis of the 3' untranslated regions of the human and mouse TNFR2 genes shows highly divergent 3' ends. The possibility of an ancestral mouse TNFR2 mRNA similar to the short transcript is discussed.

Amino Acid Sequence↗
PubMed1998

Independence of carbon and nitrogen control in the posttranslational regulation of nitrate transport in the cyanobacterium Synechococcus sp. strain PCC 7942.

Nitrate transport by Synechococcus sp. strain PCC 7942 cells was inhibited by ammonium and by inhibitors of CO2 fixation. Ammonium assimilation inhibitors, such as L-methionine D,L-sulfoximine, were known to prevent the negative effects of ammonium and of inhibitors of CO2 fixation on nitrate uptake, leading to propose that CO2 fixation was required to counteract the feed-back inhibition of nitrate assimilation. In NR-less mutants, L-methionine D,L-sulfoximine prevented the negative effects of ammonium on nitrate transport, but not always prevented those of inhibiting CO2 fixation. The carboxy-terminal domain of the NrtC subunit of the nitrate transporter has recently been identified as a regulatory domain involved in N-control. The mutant strain NC2, constructed by deleting the 3' portion of nrtC, showed high nitrate transport activity insensitive to ammonium but sensitive to inhibitors of CO2 fixation. These findings indicate that the C-control and the N-control of nitrate transport are independent at both the physiological and the molecular level.

Biological Transport↗
PubMed1998

[antineutrophil cytoplasmic autoantibodies in inflammatory bowel disease].

BACKGROUND: The aim of the present study was to determine the prevalence and diagnostic usefulness of antineutrophil cytoplasmic antibodies (ANCA) in a Spanish population of patients with inflammatory bowel disease from the province of Tarragona. PATIENTS AND METHODS: One hundred and fifty-six sera obtained from 116 patients with inflammatory bowel disease (75 ulcerative colitis and 41 Crohn's disease) and 40 healthy controls were tested using an indirect immunofluorescence assay. RESULTS: ANCA were detected in 65% of patients with ulcerative colitis but in only 12% of patients with Crohn's disease (p < 0.01), and 2.5% of control subjects (p < 0.01). The overall sensitivity of the test for the diagnosis of ulcerative colitis was 65% with a specificity of 88% and a positive predictive value of 91%. Among patients with ulcerative colitis there was no relationship between the presence or titre of ANCA and the duration, the clinical course, the extent, the disease activity or the need for medical treatment. CONCLUSIONS: In the population studied, ANCA occur more commonly in ulcerative colitis than in Crohn's disease, as reported in other populations. Their determination in patients with inflammatory bowel disease may be useful to differentiate ulcerative colitis from Crohn's disease.

Adult↗
PubMed1998

Extracellular acidification modifies Ca2+ fluxes in rat brain synaptosomes.

We examined the influence of external acidification on Ca2+ fluxes (45Ca2+ influx and 45Ca2+ efflux) in rat brain synaptosomes. A change on external pH (pHe) from 7.5 to 6.5 linearly decreased the 45Ca2+ uptake (5nmoles/mg protein/pHunit) and increased the 45Ca2+ efflux (1.5 fold/pH unit). These changes were both Na+ dependent and amiloride sensitive suggesting that the Na+/Ca2+ exchanger could be involved. The addition of the Ca2+ channel blockers (diltiazem, verapamil, nifedipine) did not prevent the decrease of the 45Ca2+ uptake evoked by acid pHe and so the involvement of the voltage-sensitive Ca2+ channels could be discarded. In order to determine whether the Na+/Ca2+ exchanger was directly activated by H+ or was indirectly activated by an internal mobilization of Ca2+ from intrasynaptosomal stores we examined the effect of pHe variation on phophoinositide hydrolisis. An increase on phosphoinositide hydrolisis was observed at acid pHe values (7 and 6.5). The hydrolisis was amiloride insensitive. On the other hand 1mM neomycin did inhibit the effect of acidic pHe on Ca2+ fluxes. Taken together, the results of our study provide evidence that external acidification stimulates phospholipase C leading to an increase in phosphoinositide hydrolisis and Ca2+ mobilization. The increase in intracellular Ca2+ would stimulate the Na+/Ca2+ exchanger, increasing Ca2+ efflux and reducing the global Ca2+ influx.

Animals↗
PubMed1998

Biosorption of nickel using filamentous fungi.

Nickel (Ni) uptake capability from aqueous solutions was studied in a filamentous fungi strains group of Rhizopus sp., Penicillium sp. Aspergillus sp., Trichoderma sp., Byschoclamyss sp., and Mucor sp. The metal uptake of a Rhizopus sp. strain, which has the highest uptake capacity, was corroborated by electron microscopy; no Ni deposits were observed on the cell wall, but rather a homogeneous accumulation was seen on the cell surface. The influence on the capacity of metal uptake by environmental parameters such as pH, temperature, time, and the interference of other ions in the solution, was also studied. Nickel accumulation by the selected strains is fast, occurring in less than 30 min, and does not require a microorganism's active metabolism to take place. The sorption isotherms were established for the selected fungi, in order to determine the maximum metal uptake capacity. The sorption isotherms were fixed to the mathematical models of Freundlich and Langmuir, obtaining better performance on the Langmuir model.

Aspergillus↗
PubMed1998

Detection of anti-PL-12 autoantibodies by ELISA using a recombinant antigen; study of the immunoreactive region.

Autoantibodies to aminoacyl-tRNA synthetases are highly associated with myositis and detection is important in clinical diagnosis; however, current methods of screening limit its clinical utility. In the present study, alanyl-tRNA synthetase (PL-12) recombinant protein was obtained by immunological screening of a HeLa expression library and used in an ELISA with 22 anti-PL-12 sera, 200 autoimmune sera negative for PL-12 and 100 healthy individual sera. Sensitivity of the method was 95% (21/22) and specificity 100%. Mapping of the immunoreactive region was carried out using three anti-PL-12 sera and different recombinant protein-derived peptides. Results show that the same conformational epitope located within amino acids 730-951 of the PL-12 antigen outside the catalytic region was recognized by the three anti-PL-12 sera tested. We conclude that ELISA using recombinant protein is an effective and useful method for routine screening for anti-PL-12 autoantibodies.

Alanine-tRNA Ligase↗
PubMed1998

Biomodulation with sequential intravenous IFN-alpha2b and 5-fluorouracil as second-line treatment in patients with advanced colorectal cancer.

A phase II trial was carried out by the Grupo Oncologico Cooperativo del Sur (G.O.C.S.) to assess the efficacy and toxicity of a biochemical modulation of 5-fluorouracil (5-FU) by i.v. pretreatment with interferon (IFN)-alpha2b in patients with advanced colorectal carcinoma refractory to previous therapy with 5-FU modulated by methotrexate (MTX) or leucovorin (LV) or both. Between January 1993 and October 1995, 34 patients were entered on the study. The treatment was IFN-alpha2b 5 x 10(6)/m2 IU in a 1-h i.v. infusion, followed immediately by 5-FU 600 mg/m2 i.v. bolus injection. Courses were repeated weekly until observation of progressive disease or severe toxicity. One patient could not be assessed for response. Objective regression was observed in 2 of 33 patients (6%, 95% confidence interval, 0%-14%). No patient achieved a complete response. Two patients had partial responses (6%). No change was recorded in 14 patients (41%), and progressive disease occurred in 17 (52%). The median time to treatment failure was 3 months, and the median survival was 5 months. Toxicity was within acceptable limits. The main side effects were mucositis and diarrhea. Four episodes of grade 2 stomatitis were observed, causing dosage modifications. The most frequent toxic effects attributable to IFN-alpha2b were mild fatigue and fever. In conclusion, second-line therapy with i.v. IFN-alpha2b preceding 5-FU has shown an interesting profile of activity in a patient population with clearly unfavorable characteristics. From this perspective, further appropriately designed studies are needed to identify the greatest potential of IFN-alpha2b as a modulator of 5-FU.

Adolescent↗
PubMed1998

Olive-pollen profilin. Molecular and immunologic properties.

Olive-pollen profilin has been isolated and characterized as a significant allergen. Its molecular properties, such as a molecular mass of 15 kDa; amino-acid composition; and secondary repetitive structure percentages of 15% alpha-helix, 33% beta-strand, 20% beta-turn, and 32% random coil, have been determined. Its allergenic capability, a recognition frequency estimated at 24% of olive-hypersensitive patients, and high cross-reactivity with all the pollen used have been found. The presence of conformation epitopes in the olive profilin, as well as a high structural and immunologic similarity to other pollen sources such as birch and ash, can be established from these studies.

Amino Acids↗
PubMed1998

[Polymerase chain reaction for rapid detection and serotyping of dengue virus in clinical samples].

This study describes the benefits of using reverse transcriptase polymerase chain reaction (RT-PCR) for the rapid detection and typing of dengue virus in clinical samples. Twenty-seven serum specimens from patients with dengue fever and dengue hemorrhagic fever in Colombia, Nicaragua, and Panama were directly subjected to RT-PCR for the detection of dengue virus. The resulting double-stranded DNA product was typed by a second round of PCR amplification (nested PCR) with type-specific primers, viral culture/indirect immunofluorescence (IIF), and enzyme-linked electroimmunoassay for IgM anti-dengue antibodies. The amplified virus genome was detected and typed within 8 hours. Nested RT-PCR, using viral culture and IIF as the gold standard, showed 100% sensitivity; 78% specificity; 69% positive predictive value, and 100% negative predictive value. It is noteworthy that two of the specimens whose results were positive with nested RT-PCR and negative with viral culture showed specific IgM antibodies. The results of the RT-PCR were in close agreement with those obtained through viral culture. This suggests PCR can greatly facilitate the rapid and early diagnosis of dengue infection.

Colombia↗
PubMed1998

[Central nervous system infection by free-living amebas: report of 3 Venezuelan cases].

INTRODUCTION: Infection of the Central Nervous System by free living amebas is an unusual event, 344 cases have been reported to date. The disease becomes evident in two different clinical fashions: Primary Amebic Meningoencephalitis (PAM) caused by Naegleria fowleri and Granulomatous Amebic Encephalitis (GAE) induced by Spp. of Acanthamoeba and Balamuthia. CLINICAL CASES: The authors report three new cases from Venezuela. Case 1. 34 years old man, with a chief complaint of general malaise, headache and fever, a diagnosis of common cold was made and the patient was treated as such, he did not improve and was admitted to the hospital with deterioration of his clinical status; the patient died 10 days after the onset of his illness which was determined to be GAE produced by Balamuthia mandrillaris. Case 2. 8 years old female admitted to the hospital because of fever, headache and generalized seizures of sudden onset; neurocysticercosis was diagnosed and following improvement the patient was discharged and readmitted on two occasions because of relapse and worsening of her illness, she died 2 months after the onset of her disease that was diagnosed by autopsy as GAE due to Balamuthia mandrillaris. Case 3. 16 years old male, previously healthy, who following immersion in a water tank was admitted to the hospital because of meningeal irritation that progressed to coma and death in a 7 day lapse; autopsy revealed PAM by Naegleria fowleri. The two cases of GAE due to Balamuthia mandrillaris occurred in apparently immunocompetent individuals, contrary to the statement that these microorganisms are opportunistic. CONCLUSION: We believe that neurological infection by amphizoic amebas is being underdiagnosed, probably due to ignorance regarding this pathology or because of a very low autopsy rate in most countries.

Adolescent↗