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L Rodríguez

Publications and source records attributed to L Rodríguez.

At least 91 records · Page 5Linked to original sources
PubMed1994

[Detection of immunoglobulin A in serum and saliva of patients with hepatitis A].

Specific secretory serum IgA antibodies to the hepatitis A virus from samples from patients with clinical symptoms compatible to hepatitis A, their contacts, and healthy subjects were analyzed using an ELISA technique; results were compared with those of specific serum IgM antibodies to the hepatitis A virus. The following results were attained in 175 blood samples: coincidence by 98.8%; sensitivity by 96.8%; and specificity by 100%. Two cases were negative to IGA and positive to IGM. On comparing the presence of IGA in saliva with the presence of IGM in blood, coincidence was of 88.1%; sensitivity, of 40.9% and specificity, of 100%. Of the 22 cases with positive IGM in blood, only 9 showed specific IGA antibodies in the saliva. The 111 cases who had negative IGM in blood were also negative to IGA. The obtained data suggest that specific serum IGA antibodies to the hepatitis A virus are an indicator of a recent or occurrent infection due to this virus and thus it may be considered and alternative for the diagnosis of this disease.

Enzyme-Linked Immunosorbent Assay↗
PubMed1993

Vincristine cellular pharmacokinetic changes associated with multidrug resistance.

The correlation between vincristine cellular pharmacokinetics and its biological action was analyzed in L5178Y cells and in a multidrug resistant subline (VCR/G40) at the nM drug concentration range attained in serum during the clinical use of the drug. The reduced rate of drug influx and the higher drug efflux measured in VCR/G40 cells justify the lower drug accumulation characterized in these cells compared to the parental cells. Nevertheless this does not seem to be the sole reason accounting for the resistance expression since similar cytotoxic effects of vincristine on both cell lines were only attained when the intracellular drug concentration was ten times higher in resistant than in parental cells. Bearing in mind that the drug-binding kinetics have not been modified during the resistance development, our results indicate that some vincristine accumulated by resistant cells may be compartmentalized into these cells before its interaction with microtubules.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1993

[HLA A, B, C and DR antigens in a urban population from Santiago of Chile].

HLA antigens vary in different ethnical groups and in Chile there are no reports on the frequency of these antigens in a normal representative population. The few existing studies are of indigenous populations and control groups, without including HLA-DR antigens. Therefore, the aim of this study was to study the frequency of HLA A, B and C antigens in 349 individuals and HLA-DR in 257, using the microlymphocytotoxicity method, and compared the results with those on normal caucasian populations (Europe and USA). Significant differences were found for 7 antigens of group A, 10 of group B, 4 of group C and 6 of group DR. The observed difference allow us to conclude that the population from Santiago has a distinct HLA antigen distribution. This fact must be bore in mind future studies in genetics, paternity or autoimmune diseases.

Adult↗
PubMed1993

[Evaluation of the determination of total cholesterol in Chilean clinical laboratories].

The precise and accurate measurement of total cholesterol is necessary to correctly identify hypercholesterolemia. The aim of this study was to assess the measurement of serum cholesterol in clinical laboratories using as acceptability criteria the recommendations of the "National Cholesterol Education Program" (that consider acceptable a deviation < 5% from the real value and ideal a deviation < or = 3%). In each of three assessments, three pools of lyophilized sera with different levels of cholesterol were used method. Twenty nine to 42.3% of laboratories had results within the ideal interval and 49.5 to 60% within the acceptable range of deviation. In the last assessment, only 17% of laboratories had their three values within the ideal range. Only 39.4% of laboratories use 200 mg/dl as the cut off point to diagnose hypercholesterolemia. It is concluded that the standardization of cholesterol measurement and the use of a common cut off point to diagnose hypercholesterolemia must be emphasized.

Chile↗
PubMed1993

Immobilization of beta-glucosidase from Penicillium funiculosum on nylon powder.

beta-Glucosidase from Penicillium funiculosum was immobilized on nylon powder previously activated with triethyloxonium tetrafluoroborate, 1,2-diaminoethane and glutaraldehyde. The activation of the nylon powder and the immobilization processes were studied and optimized for the enzyme and the matrix. A high activity retention (67%) was obtained using the activation and immobilization conditions finally selected.

Borates↗
PubMed1992

Novel genetic markers of rheumatoid arthritis in Chilean patients, by DR serotyping and restriction fragment length polymorphism analysis.

OBJECTIVE: The analysis of genetic markers of rheumatoid arthritis (RA) in a population in which the DR4 serotype is not strongly associated with the disease. METHODS: Chilean RA patients (56 seropositive and 22 seronegative) and 141 controls were studied by serotyping. Southern blot analysis of Bam HI restriction fragment length polymorphism (RFLP) was done in genomic DNA from 46 patients with seropositive RA, 17 patients with seronegative RA, and 45 controls, using a complementary DNA probe specific for DRB1 genes. RESULTS: The prevalence of the HLA-DR9 haplotype was strikingly higher in seropositive RA patients (21%) than in controls (3%) (Pcorr less than 0.0008, by Fisher's exact test; relative risk [RR] = 9.34). The prevalence of DR4 and DR1 haplotypes, although slightly increased, did not achieve a significant preponderance. The simultaneous presence of two Bam HI fragments (3.6 kb and 4.5 kb) was found with higher prevalence in seropositive patients (83%; RR = 9; Pcorr less than 0.00002) than in controls (36%), and seemed higher in seronegative RA patients as well (71%; RR = 4). Furthermore, its prevalence remained increased in comparisons of DR4 positive controls (36%) with DR4 positive seropositive patients (100%; RR = 67; Pcorr less than 0.0002) and DR4 positive seronegative patients (100%; RR = 36; Pcorr less than 0.006), even after excluding the DR9 positive individuals. A tendency toward higher association with DR1 seropositive RA patients (67%; RR = 12), a group with no DR4 or DR9 positive individuals, than in DR1 positive controls (14%), was also observed. CONCLUSION: The HLA-DR9 haplotype was definitively consolidated as a very strong genetic marker exclusively for seropositive RA in Chilean patients, as suggested by our previous observations. RFLP analysis showed that the simultaneous presence of 3.6-kb and 4.5-kb Bam HI fragments constituted a better RA marker than did any of the heretofore studied haplotypes. These fragments together would be linked to RA independently of the DR1, DR4, and DR9 haplotypes. The overall evidence indicates that Chilean seropositive RA patients display a genetic background that is different from that underlying RA susceptibility in other populations and suggests the existence of common, as well as distinct, genetic elements predisposing to seronegative and seropositive RA.

Adult↗
PubMed1990

Weak association between HLA-DR4 and rheumatoid arthritis in Chilean patients.

Evidence has suggested a genetic link between the HLA-DR4 phenotype and rheumatoid arthritis (RA), particularly in its seropositive form. Such an association varies among different ethnic groups and remains controversial for seronegative patients. Data obtained for a group of 64 Chilean patients with RA (46 seropositive, 18 seronegative), as defined by the 1987 criteria of the American Rheumatism Association, and for 76 controls are reported here. The prevalence of HLA-DR4 and DR9 was significantly increased in the group of patients considered as a whole. The prevalence of HLA-DR4 was not significantly higher, however, when seronegative and seropositive patients were separately compared with controls. Also, it did not correlate with the severity of the disease within each subgroup of patients. On the other hand, HLA-DR9 showed a highly significant difference, not previously described, only for the seropositive patients in comparison with controls. The prevalence of DQ specificities showed no relevant differences among the groups. The HLA-DR4 serotype, therefore, is a weak marker for RA and does not differentiate any subgroup of patients in the Chilean group studied. This new finding, indicating an association between RA and the DR9 antigen, may be explained by the suggestion that susceptibility epitopes are shared among different DR molecules. This hypothesis might also account for the variation in the association of DR4 with RA.

Arthritis, Rheumatoid↗
PubMed1990

[Non-Hodgkin's lymphomas. Results of alternating chemotherapy versus sequential chemotherapy].

An analysis is presented of the results attained in 115 cases of advanced non-Hodgkin's lymphoma (stages III and IV) with high or intermediate grade histology (with exception of lymphoblastic lymphoma) which had received no previous treatment. The patients were distributed at random into two groups, A and B. Patients in group A received the classical CHOP-Bleo regimen, and they were given six courses at three-week intervals. The patients of group B received alternate chemotherapy consisting of two CHOP-Bleo courses, two CMED (cyclophosphamide, methotrexate, etoposide, dexamethasone) courses, and two CHOP-Bleo courses. The complete remission rates were 68% for patients of group A and 70% for patients of group B (p = 0.81); the duration of complete remission was 36 and 45 months, respectively (p = 0.73). Nineteen cases in group A (34%) and 18 in group B (30%) relapsed. Disease-free survival at five years was 34% for group A and 40% for group B (p = 0.67). No differences were found in toxicity of chemotherapy between the two groups. It was concluded that the alternate chemotherapy regimen CHOP-Bleo/CMED shows similar effects than the classical CHOP-Bleo treatment, and provides a lesser amount of adriamycin, which makes it feasible to use this or other anthracycline drugs in case of relapse; the use of this regimen must be borne in mind when the patient is carrying a myocardiopathy.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1990

[Evaluation in our milieu of an ELISA method (ANDA-Tb) for the serological diagnosis of tuberculosis].

We have evaluated the new ELISA test (ANDA-Tb) for the serological diagnosis of tuberculosis in serum samples from 343 individuals: 160 were from blood donors, 152 from patients with nontuberculous diseases, most of them respiratory, and 31 from tuberculous patients diagnosed by positive culture. Using a cutoff value in 350 serounits we had a positive predictive value of 57% and a negative predictive value of 98% in blood donors, and 43% and 97%, respectively, in control patients. Sensitivity was 68%. There was a higher false positive rate in patients with respiratory diseases, particularly acute pneumonia. We conclude that this particular ELISA is very useful as a supportive test for the diagnosis of tuberculosis, with a lower specificity in hospital nontuberculous patients.

Antibodies, Bacterial↗
PubMed1990

[Treatment of bladder instability using intravaginal electric stimulation (intrarectal)].

Fourteen patients (13 females, 1 male) with urinary incontinence from bladder instability were treated with intravaginal (intrarectal) electrical stimulation. Good results were achieved in 57.1% of the cases. The foregoing finding shows that intravaginal (intrarectal) electrical stimulation may constitute a therapeutic option in urinary incontinence from bladder instability.

Adolescent↗
PubMed1989

Protective effect of colchiceine against acute liver damage.

Pretreatment of rats with colchiceine (10 micrograms/day/rat) for seven days protected against CCl4-induced liver damage. CCl4 intoxication was demonstrated histologically and by increased serum activities of alanine amino transferase (ALT), alkaline phosphatase (Alk. Phosph.) gamma glutamyl transpeptidase (GGTP), bilirubins and decreased activity of glucose-6-phosphatase (G-6Pase). Furthermore, an increase in liver lipid peroxidation and a decrease in plasma membrane GGTP and Alk. Phosph. activities were found. Colchiceine increased 1.5-fold the LD50 of CCl4 and prevented the release of intracellular enzymes as well as the decrease in GGTP and Alk. Phosph. activities in plasma membranes. It also completely prevented the lipid peroxidation induced by CCl4 and limited the extent of the histological changes.

Alanine Transaminase↗
PubMed1989

Role of glutamine aminotransferase in glutamine catabolism by Saccharomyces cerevisiae under microaerophilic conditions.

The involvement of glutamine aminotransferase activity in glutamine catabolism by Saccharomyces cerevisiae under microaerophilic conditions was studied. We were able to show that there are at least two different glutamine aminotransferase activities that are differentiated genetically, by their substrate specificity (pyruvate and glyoxylate dependence), and their different modes of regulation. The pyruvate-dependent glutamine aminotransferase activity plays a major role in glutamine catabolism under microaerophilic conditions since the wild-type strain S288C showed a 10-fold higher activity in static cultures than in agitated ones. The same strain also had 3-fold higher glutaminase B activity in agitated cultures than in static ones. Pyruvate-dependent glutamine aminotransferase activity is not regulated directly by O2 itself since a rho- strain showed a high activity regardless of the extent of aeration of cultures. Finally, we were able to isolate a mutant, strain CN20, derived from the rho- strain and unable to utilize glutamine as the sole nitrogen source, which was severely affected in pyruvate-dependent but not in glyoxylate-dependent aminotransferase activity.

Aerobiosis↗
PubMed1989

Isolation and characterization of a Saccharomyces cerevisiae mutant with impaired glutamate synthase activity.

A mutant of Saccharomyces cerevisiae that lacks glutamate synthase (GOGAT) activity has been isolated. This mutant was obtained after chemical mutagenesis of a NADP-glutamate dehydrogenase-less mutant strain. The gdh gus mutant is a glutamate auxotroph. The genetic analysis of the gus mutant showed that the GOGAT-less phenotype is due to the presence of two loosely linked mutations. Evidence is presented which suggests the possibility that S. cerevisiae has two GOGAT activities, designated GOGAT A and GOGAT B. These activities can be distinguished by their pH optima and by their regulation by glutamate. Furthermore, one of the mutations responsible for the GOGAT-less phenotype affected GOGAT A activity, while the other mutation affected GOGAT B activity.

Crosses, Genetic↗
PubMed1989

Effect of alpha factor pheromone on the activity of enzymes which catalyze the synthesis and hydrolysis of cell wall structural polymers from Saccharomyces cerevisiae.

Cells of Saccharomyces cerevisiae of the a mating type treated with alpha factor contain an increased amount of structural polymers (beta-glucans and chitin) in their cell walls and, consequently, exhibit higher glucan synthetase and chitin synthetase activities than untreated cells. However, alpha factor has no detectable effect on the activities of these enzymes when they are assayed, "in vitro", in the presence of the pheromone. On the other hand, the activity of beta-glucanases remains constant during the time that growth of a cells is kept arrested by alpha factor at the G1 phase of the cell division cycle and starts to increase when budding of the cells is reinitiated.

Catalysis↗
PubMed1989

[Long-term results in the treatment of lymphomas using polychemotherapy (CHOP)].

The long-term results achieved with CHOP chemotherapy in 131 patients with non-Hodgkin's lymphoma of diffuse histological pattern and in advanced stages were analysed. The mean age of the patients was 49 years. Complete remission was achieved in 68 cases (60 %). There was good tolerance in general terms, without any lethal complications. The median survival was 27 months; 28 patients (25 % of the whole series) are alive and disease-free after 10 years, so they can be considered as cured. High lactate-dehydrogenase levels, bulky tumoural mass and high degree of histological malignancy were identified as poor-prognosis factors. CHOP chemotherapy appears as a useful means of treating non-Hodgkin's lymphoma, as shown by the number of patients achieving long lasting remission and by the tolerance. Nevertheless, this treatment is of less value in patients with poorer prognosis, in whom other regimens must be borne in mind.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1988

Synthesis of Saccharomyces cerevisiae invertase by Schizosaccharomyces pombe.

In order to gain information on the ability of the glycosylation system of Schizosaccharomyces pombe to process heterologous glycoproteins, the expression of Saccharomyces cerevisiae invertase in the former yeast was studied. Sc. pombe cells are able to produce enzymatically active invertase from the S. cerevisiae SUC2 gene introduced by transformation and the enzyme is glycosylated and secreted into the cell wall. However, Sc. pombe transformants do not glycosylate the heterologous enzyme as their own invertase since it is not bound by the lectin from Bandeiraea simplicifolia seeds, which indicates the absence of terminal galactose residues. Moreover, the electrophoretic mobility of the heterologous invertase is similar to that of the large enzyme from S. cerevisiae, both in its native form and after being deglycosylated with Endo H. These results suggest that the polypeptide chain of S. cerevisiae invertase is the primary factor for the glycosylation in Sc. pombe cells.

Concanavalin A↗