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Biomedical subjects

R Rodríguez

Publications and source records attributed to R Rodríguez.

At least 19 recordsLinked to original sources
PubMed1992

Tumor cytostasis mediated by a monoclonal IgM antibody promoting adhesion between macrophages and tumor cells. Evidence for a lectin-like behavior.

We have shown previously that an IgM mAb (A10) recognizing Ehrlich tumor (ET) cell surface carbohydrates, inhibits in vivo ET growth by a macrophage-dependent mechanism. The inhibition mechanism involving both IgM and macrophages was unclear because receptors for IgM on macrophages are controversial and another monoclonal IgM (E1), also recognizing ET cell surface carbohydrates, was completely unable to show any protective effect. Here we show that A10, but not E1, was able to promote adhesion between macrophages and ET cells by a receptor for IgM-independent mechanism. Immunofluorescence studies showed that A10, but not E1, did react with macrophages if these cells were preincubated with a source of Ag spontaneously released from ET cells. This Ag release appeared to be required for A10-mediated adhesion, because adhesion was not obtained when ET cells fixed with paraformaldehyde were used. Cytostasis studies performed with macrophages stimulated with L-929 conditioned medium and ET cells showed that A10, but not E1 nor unrelated IgM, was able to inhibit ET cell proliferation in vitro by a mechanism involving cell contact between both cell populations. Therefore, IgM inhibition of ET growth, both in vivo and in vitro, could be explained by a lectin-like mechanism, where IgM, recognizing Ag of tumor origin, bridges macrophages to tumor cells.

Animals↗
PubMed1992

Nitrate transport in the cyanobacterium Anacystis nidulans R2. Kinetic and energetic aspects.

Nitrate transport has been studied in the cyanobacterium Anacystis nidulans R2 by monitoring intracellular nitrate accumulation in intact cells of the mutant strain FM6, which lacks nitrate reductase activity and is therefore unable to reduce the transported nitrate. Kinetic analysis of nitrate transport as a function of external nitrate concentration revealed apparent substrate inhibition, with a peak velocity at 20-25 microM-nitrate. A Ks (NO3-) of 1 microM was calculated. Nitrate transport exhibited a stringent requirement for Na+. Neither Li+ nor K+ could substitute for Na+. Monensin depressed nitrate transport in a concentration-dependent manner, inhibition being more than 60% at 2 microM, indicating that the Na(+)-dependence of active nitrate transport relies on the maintenance of a Na+ electrochemical gradient. The operation of an Na+/NO3- symport system is suggested. Nitrite behaved as an effective competitive inhibitor of nitrate transport, with a Ki (NO2-) of 3 microM. The time course of nitrite inhibition of nitrate transport was consistent with competitive inhibition by mixed alternative substrates. Nitrate and nitrite might be transported by the same carrier.

Biological Transport↗
PubMed1992

[A 2-year follow-up of a program for the control of cardiovascular risk factors among asymptomatic workers].

In 1987, a cardiovascular risk profile was obtained on 836 workers of the National Electricity Co in Santiago. There were 714 males and 125 females, the mean age was 45 years (ES +/- 0.3). Hypertension (systolic pressure > 160 or diastolic > 90 mmHg) was present in 17% of subjects, hypercholesterolemia (> 240 mg/dl or > 220 mg/dl associated to 2 other risk factors) in 17%, obesity (> 20% above ideal weight) in 33% and 29% were smokers. An advice to stop smoking, changes in the casino menu and hypertension, obesity and hypercholesterolemia's control programs were offered. These were attended by 108 hypertensives, 141 subjects with hypercholesterolemia and 104 obese individuals with an attendance rate of 64%, 75 and 77% respectively. Measurements repeated 2 years later revealed a reduction in diastolic pressure of 3.3 +/- 1.1 mmHg (p < 0.004) only in adherent subjects. Cholesterol levels were reduced by 24 +/- 3 mg/dl (p < 0.001) with no differences for non participants, adherent and non adherent subjects. Adherent obese subjects reduced their weight by 2.2 +/- 0.4 kg (p < 0.001). There was no change in the number of smokers.

Cardiovascular Diseases↗
PubMed1992

[Genetic evidence of a species complex in Anopheles pseudopunctipennis pseudopunctipennis].

In light of inconsistencies in the pattern of malaria transmission within geographical areas inhabited by Anopheles pseudopunctipennis pseudopunctipennis, a study was carried out to investigate the possibility that this vector constitutes a species complex. Hybrid crossing studies, electrophoretic analysis of enzyme loci, and DNA restriction analysis were conducted on mosquitoes captured at nine sites in Mexico, Bolivia, and Peru. The sterility of generations resulting from cross-mating of Mexican female mosquitoes and South American male mosquitoes; the results of electrophoretic analysis, which showed differences at two loci; and a genetic distance value of 0.13 confirmed the existence of a species complex, probably produced by allopatric speciation. It is concluded that the geographic distribution of this newly discovered species complex should be defined, in view of its potential effect on malaria control.

Animals↗
PubMed1991

A new distinct group of 2 S albumins from rapeseed. Amino acid sequence of two low molecular weight napins.

Two napins (nIa and nIb), isolated from Brassica napus (rapeseed) seeds, have been sequenced. The two proteins show the common structural pattern of the 2 S albumins, since they are composed of two disulfide-linked chains of different size, yet they exhibit an atypical low molecular weight (12.5 kDa vs. 14.5 kDa of the major napins). High sequence similarity has been found between these 2 proteins, but only 54% similarity can be estimated from their comparison with the 14.5 kDa major napins. Thus, nIa and nIb are considered representatives of a new distinct group of rapeseed napins since all the previously known napins exhibit 95% sequence similarity. Unexpectedly, the similarity increases when compared with the 2 S proteins from other species.

2S Albumins, Plant↗
PubMed1991

Structural analysis of the small chain of the 2S albumin, napin nIII, from rapeseed. Chemical and spectroscopic evidence of an intramolecular bond formation.

Napin nIII is a 2S albumin from rapeseed (Brassica napus L.) homologous to the major mustard allergen. It is composed of two different polypeptide chains linked by two disulphide bonds. The small chain has been isolated by reverse-phase HPLC after reduction of the native protein and its primary structure elucidated. This 37 residue polypeptide contains only two cysteines, at positions 10 and 23, which show a great tendency to form a non-native intramolecular disulphide bridge. The kinetic analysis of this process was performed by measuring the fluorescence emission of the single tryptophan residue of the molecule since its fluorescence intensity is about 30% decreased during disulphide formation. Small changes on the secondary structure of the polypeptide were measured by circular dichroism. The process is delayed in the presence of the reduced large chain of nIII. However, no dimer formation was detected under the conditions used, either between small chains or between the small and the large chains. Thus, the interchain disulphide formation in napin nIII should be considered as an early step during maturation of this multi-subunit seed protein.

2S Albumins, Plant↗
PubMed1991

Hand motor patterns after the correction of left-nondominant-hand mirror writing.

In a previous report, the author studied a left-nondominant-hand mirror writer, postulating that her mirror writing resulted from the failure to reverse the right-hand writing motor patterns when transmitted from the left to the right cerebral hemisphere. In this study, the patient was asked to write in normal fashion with the left hand; the result was a mixture of handwriting motor patterns which included normal letters, letters with reversed direction tracings, letters with one or more than one loop-tracings and illegible letters. The author considers this result to be a further support for the above-proposed hypothesis.

Adult↗
PubMed1991

Isolation and characterization of a major allergen from oriental mustard seeds, BrajI.

A 2 S albumin from oriental mustard (Brassica juncea) seeds has been isolated and characterized as an allergen. This protein, BrajI, was recognized by human IgE from mustard-sensitive individuals, as proved by using two different enzyme immunoassays. BrajI was found to be closely related to Sin a I, the major allergen from yellow mustard seeds. Many fractions with molecular weights ranging from 16,000 to 16,400 and with differences in charge were separated by ion-exchange chromatography. They exhibited small but significant amino acid composition differences for Glx, Val, Ile, Lys, and Arg contents. The heterogeneity of BrajI can be explained by size and charge differences of its heavy and light chains. All of the isoallergenic forms of BrajI gave a single precipitation band in double diffusion immunoassays when using a Sin a-I-specific rabbit polyclonal serum.

2S Albumins, Plant↗
PubMed1991

Prognostic implication of anti-neutrophil cytoplasmic autoantibodies with myeloperoxidase specificity in anti-glomerular basement membrane disease.

Anti-neutrophil cytoplasmic autoantibodies (ANCA) were detected in 12 out of 37 (32%) serum samples from patients with anti-glomerular basement membrane (GMB) disease by an indirect immunofluorescence assay. In 11 cases, ANCA were directed against myeloperoxidase, as revealed employing neutrophils devoid of this enzyme as the test substrate. Patients having both ANCA and anti-GBM antibodies (AGBMA) were considerably older (mean age 59 years) than patients with AGBMA alone (mean age 33 years). In addition, patients with both antibodies had some clinical and pathologic data that suggested an associated systemic vasculitis. This was supported by the fact that among these patients, those with highest ANCA titres recovered renal function despite being initially on hemodialysis, as opposed to those with lowest ANCA titres or AGBMA alone. In patients with both antibodies, there was an inverse relationship between AGBMA and ANCA values (p = 0.02). Moreover, the mean AGBMA level tended to be higher for patients with AGBMA alone than for those with both ANCA and AGBMA. These results suggest that, at least in some cases, there may be a contribution of an ANCA-related mechanism in the pathogenesis of anti-GBM disease. Although the exact role of ANCA in this and other diseases remains to be clarified, there is important clinical evidence that in anti-GBM disease ANCA may represent a serologic marker of good prognosis identifying a subset of patients who may recover renal function.

Adolescent↗
PubMed1991

[Preventive medical examination in asymptomatic workers: design and initial outcome of an institutional program].

We have designed a preventive medical examination program for workers of an electric company in Santiago, Chile. The first stage, directed mainly to identification of cardiovascular risk factors was completed in 1987. 1006 males and 163 females with mean age 45 +/- 9.4 years (range 22-65) were screened. High blood pressure mainly of mild degree was detected in 17.6% of subjects (57% of them were new cases). Total cholesterol above 220 mg/dl and HDL cholesterol below 40 mg/dl were present in 33% and 22%, respectively. Obesity (body weight > 120% of ideal weight for height) was present in 19%, and body mass index was above 27 in 25% of subjects. 23% of males and 31% of females smoked 1 or more cigarettes a day and 2% had an abnormal non-fasting glucose level. A total of 750 workers have at least 1 risk factor that should be corrected. No cases of cancer were detected by Papanicolaou and mammography. A positive correlation was found among LDL cholesterol, age and triglyceride levels and HDL was negatively correlated to triglycerides, blood glucose and obesity. A multivariate analysis of these factors revealed that only age was related to LDL levels and triglycerides to HDL levels. This health prevention program may help a significant number of asymptomatic workers by detecting risk factors that need correction in order to decrease mortality and morbidity in this population.

Adult↗
PubMed1991

Advanced colorectal carcinoma. A prospective randomized trial of sequential methotrexate, 5-fluorouracil, and leucovorin versus 5-fluorouracil alone.

One hundred and twenty-five previously untreated patients bearing metastatic or advanced recurrent (inoperable) colorectal carcinoma and measurable disease were prospectively randomized. Those in arm A received 5-fluorouracil (5-FU), 1,200 mg/m2 i.v. infusion over 2 h, while those in arm B received methotrexate (MTX), 200 mg/m2 i.v. (push injection), followed 20 h later by 5-FU, 1,200 mg/m2 i.v. infusion over 2 h, plus calcium leucovorin (LV), 25 mg i.m. every 6 h for eight doses beginning 24 h after MTX administration. Cycles were repeated every 15 days. All patients receiving treatment were evaluable for toxicity and survival, and 118 patients were evaluable for response. The objective regression rate (complete plus partial response) was 12% (7 of 58) in arm A and 28% (17 of 60) in arm B (p = 0.049). No change was observed in 24% (14 of 58) in arm A and in 35% (21 of 60) in arm B (p = 0.28), while progressive disease was registered in 64% (37 of 58) and 37% (22 of 60) in arms A and B, respectively (p = 0.006). Median duration of response was 3 months in arm A and 5 months in arm B (p = 0.39). The median survival was 8.3 months in arm A and 11.2 months in arm B (p = 0.25). No statistically significant differences were found when objective regression and survival were related to site of primary tumor, performance status, and number of involved organs. There were two drug-related deaths in arm B due to severe myelosuppression followed by mucositis and sepsis. Of nonhematologic toxicities, diarrhea was more frequently observed in arm B, as were mucositis and infectious complications. Our results indicate that the sequential schedule MTX-5-FU-LV with 20-h intervals between MTX and 5-FU is superior in terms of objective regression to 5-FU alone given at the dose and schedule used in the present study. However, MTX-5-FU-LV did not have a significant impact on survival.

Adult↗
PubMed1990

Isolation of three allergenic fractions of the major allergen from Olea europea pollen and N-terminal amino acid sequence.

A method to isolate the major allergen from olive pollen (Ole e I) in high yield is described. The allergenic fraction has been separated into 3 subfractions by reverse-phase HPLC. All these fractions were reactive to allergic sera from olive-sensitized patients, giving similar responses. No significant differences were observed between the amino acid compositions of these three proteins. The amino acid sequence of the first 27 amino acid residues from the N-terminal end is given. No homologies have been detected between Ole e I and other known allergens obtained from pollen.

Allergens↗