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J Díaz

Publications and source records attributed to J Díaz.

At least 73 records · Page 4Linked to original sources
PubMed1997

Histone synthesis in Trypanosoma cruzi.

Trypanosoma cruzi is an ancient, parasitic eukaryote which does not undergo chromatin condensation during cell division. This behavior may be explained if one considers the strong amino acid sequence divergence of Trypanosoma histones compared to higher eukaryotes. In the latter organisms histone synthesis is coupled to DNA replication. Considering the nonconserved amino acid sequence of T. cruzi histones, as well as the absence of chromatin condensation in this organism, we have studied histone synthesis in relation to DNA replication in this parasite. We have found that core histones and a fraction of histone H1 are synthesized concomitantly to DNA replication. However, another fraction of histone H1 is constitutively synthesized.

Animals↗
PubMed1997

Antigen recognition characteristics and comparative performance in immunoaffinity purification of two monoclonal antibodies specific for the hepatitis B virus surface antigen.

In this paper we describe the antigen recognition characteristics, variable region base and amino acid sequence, and performance as immunoaffinity chromatography ligands of two MAb specific to the alpha determinant of the HBsAg, derived from the same fusion. We show that the epitope recognized by CB-Hep.0 (IgM) is probably associated to an intrachain disulfide bond in the antigen. On the other hand, CB-Hep.1 (IgG2b) recognizes a heat-resistant non-conformation dependent antigenic determinant on HBsAg. PCR-cloning and sequencing of the variable regions of these two MAb indicated that both heavy chain variable regions were originated from the usage of the same germinal V and J genes. However, the outstanding differences in the size of the VH CDR3, and the absolute difference in the light chain sequences, suggest that the hybridomas were originated from different precursor B lymphocytes. With respect to their use as immunoaffinity chromatography ligands for the purification of a recombinant HBsAg, we found that the IgM immunogel exhibited increased performance with respect to amount of eluted antigen, and final recovery. This difference in overall performance could be attributed to a series of factors: the higher valence number of IgM, a dissimilar distribution of IgM and IgG in the activated gel particles, and differences in antigen recognition between both MAb. Our results suggest that IgM antibodies may be useful in immunopurification, particularly if the antigen is structurally complex and has a high density of repeating epitopes.

Amino Acid Sequence↗
PubMed1997

Purification and characterization of an invertase from Candida utilis: comparison with natural and recombinant yeast invertases.

A periplasmic invertase from the yeast Candida utilis was purified to homogeneity from cells fully derepressed for invertase synthesis. The enzyme was purified by successive Sephacryl S-300, and affinity chromatography and shown to be a dimeric glycoprotein composed of two identical monomer subunits with an apparent molecular mass of 150 kDa. After EndoH treatment, the deglycosylated protein showed an apparent molecular weight of 60 kDa. The apparent K(m) values for sucrose and raffinose were 11 and 150 mM, respectively, similar to those reported in Saccharomyces cerevisiae. The range of optimum temperature was 60-75 degrees C. The optimum pH was 5.5 and the enzyme was stable over pH range 3-6.

Blotting, Southern↗
PubMed1997

No relationship between the IUD position evaluated by ultrasound and complaints of bleeding and pain.

The objectives of this study were to define the "normal" position of the T-shaped intrauterine device (IUD) in the endometrial cavity, using transvaginal ultrasound, and to compare the IUD's position in women with and without complaints of bleeding and/or pain. Vaginal ultrasound was carried out in women who had used a T-Cu 200 or T-Cu 380 for at least 6 months. Of these women, 236 registered bleeding complaints and/or pain and 245 had no complaints. The distances, IUD-endometrium, IUD-myometrium, and IUD-fundus, were measured in each woman. Our results showed that women with and without complaints presented no significant differences in age, parity, type of IUD, duration of use, previous contraceptive method used, hysterometry, uterine position, or period of the cycle in which the ultrasound was performed. The values of the three distances in users without complaints were widely dispersed. The 90th percentile of the IUD-endometrium, IUD-myometrium, and IUD-fundus distances were 7, 11, and 27 mm, respectively. The curve of the values for the three distances among women with complaints was similar to that of the subjects without complaints. Using the generally accepted measurement of 20 or 25 mm as the limits of normality of the distance IUD-fundus, and the 90th percentile of the distance IUD-endometrium as the gold standard, 77% and 43% of the women were false positives for "incorrect IUD position." Similar results were obtained when the 90th percentile of the distance IUD-myometrium was used as a gold standard. We concluded that the 90th percentiles of the distance IUD-endometrium, IUD-myometrium, and IUD-fundus were 7, 11 and 27 mm, respectively, among users without complaints. The ultrasonographic diagnosis of the IUD position was unable to discriminate between women who did or did not have complaints of bleeding and/or pain. If ultrasound were to be performed in T-shaped IUD users, the IUD-myometrium distance is likely to be the most reliable measurement.

Adult↗
PubMed1997

[Evaluation of a rapid method for the identification of the Enterococcus genus].

BACKGROUND: The evaluation of the reliability of a group of three tests: pyrrolidonil-arilamidase, rapid test in NaCl esculin broth and group D antistreptococci agglutination for the rapid identification of the Enterococcus genus were performed. METHODS: One hundred fifty-eight strains of streptococci: 110 strains of Enterococcus faecalis, 8 E. faecium, 3 E. avium, 16 Streptococcus intermedius, 7 S. salivarius, 4 S. bovis, 4 S. constellatus, 2 S. sanguis and 1 strain of S. equinus, S. mitis, S. uberis and S. mutans were studied. The tests used were: rapid test in NaCl- esculin broth, pyrrolidonyl-arilamidase and antigroup D streptococcus agglutination (Patho Dx Strep D/PYR; Diagnostic Product Corporation). All catalase-negative gram-positive cocci or coccibacilli which were positive in the three tests were considered to belong to the Enterococcus genus. The usefulness of Gram staining in culture in thioglycolate broth was also studied comparing it with the results obtained with solid medium. RESULTS: The results of the proposed identification scheme were evaluated calculating different parameters: sensitivity 98%, specificity 100%, positive predictive value, 100%, and negative predictive value 94%. No significant differences were observed between the results obtained with Gram staining with thioglycolate broth and those obtained with solid medium except in the case of the Streptococcus mutans strain. CONCLUSIONS: The application of a combination of tests: pyrroidonyl-arilamidase, antistreptococci group D agglutination and rapid test in NaCl-esculin broth to catalase-negative gram-positive cocci and coccobacilli allows reliable identification in a maximum of three hours of strains belonging to the Enterococcus genus.

Bacteriological Techniques↗
PubMed1997

Effects of anapsos on the activity of the enzyme Cu-Zn-superoxide dismutase in an animal model of neuronal degeneration.

The enzyme Cu-Zn-SOD is a metalloenzyme that catalyzes the dismutation of the superoxide radical into hydrogen peroxide and molecular oxygen, being a defense system against free radical formation. Free radical reactions are implicated in a variety of physiological and pathological processes as aging, apoptosis and neurodegenerative diseases, and abnormalities associated with SOD have been recently documented in several neurodegenerative processes. In this study, we have evaluated the effect of anapsos on Cu-Zn-SOD activity in rats with injections of beta-amyloid protein or water bilaterally into the hippocampus. These injections caused severe cell depletion in the gyrus dentatus. Anapsos is a biological extract obtained from the fern Polypodium leucotomos with immunomodulatory and anti-neoplastic effects tested in animals and humans. Cu-Zn-SOD activity was measured in the hypothalamus, hippocampus, cerebral cortex, liver and spleen of rats treated i.p. with three doses of anapsos for 7 days (4, 20 and 100 mg/kg/day). Control animals were treated with saline solution under the same conditions. Anapsos significantly modified enzyme activity in all the areas tested. Lower doses of anapsos produced decreased SOD activity in the hypothalamus, hippocampus, liver and spleen, while in the cerebral cortex, a significant dose-dependent increase in SOD activity was observed. These results indicate that anapos was able to modify Cu-Zn-SOD activity in this animal model of neuronal degeneration, which may indicate the participation of anapsos in mechanisms of tissue repair after brain damage.

Amyloid beta-Peptides↗
PubMed1997

Prevalence of stroke in two samples (rural and urban) of old people in Spain. A pilot door-to-door study carried out by health professionals.

The aim of this study was to present the prevalence of stroke from a pilot study in old people. The urban site sample (Madrid) was made up of 397 subjects and the rural site sample (Arévalo, Avila) of 862 subjects. The study was performed with a door-to-door methodology. In the urban sample, the prevalence of stroke was 8.5% (CI 95% = 5.5-11.5%) and that of TIA was 2.1% (CI 95% = 0.6-3.6%). In the rural location the prevalence of stroke was 7.1% (CI 95% = 5.4-8.8%). This prevalence of stroke is higher than in other Spanish studies. These results need to be confirmed in a wider investigation.

Aged↗
PubMed1997

The strategic approach to contraceptive introduction.

The introduction of new contraceptive technologies has great potential for expanding contraceptive choice, but in practice, benefits have not always materialized as new methods have been added to public-sector programs. In response to lessons from the past, the UNDP/UNFPA/WHO/World Bank Special Programme of Research, Development, and Research Training in Human Reproduction (HRP) has taken major steps to develop a new approach and to support governments interested in its implementation. After reviewing previous experience with contraceptive introduction, the article outlines the strategic approach and discusses lessons from eight countries. This new approach shifts attention from promotion of a particular technology to an emphasis on the method mix, the capacity to provide services with quality of care, reproductive choice, and users' perspectives and needs. It also suggests that technology choice should be undertaken through a participatory process that begins with an assessment of the need for contraceptive introduction and is followed by research and policy and program development. Initial results from Bolivia, Brazil, Burkina Faso, Chile, Myanmar, South Africa, Vietnam, and Zambia confirm the value of the new approach.

Africa↗
PubMed1997

Anapsos reverses interleukin-1 beta overexpression and behavioral deficits in nbM-lesioned rats.

Rats with neurotoxic lesions, induced by single or double bilateral injections of ibotenic acid into different parts of the nucleus basalis of Meynert (nbM), showed increased psychomotor activity (PMA) and impaired learning in a passive avoidance task. Behavioral deficits were similar in all the groups of lesioned animals, suggesting that the lesion site was not relevant for the ibotenic effects under testing procedures used here. In another experiment, nbM-lesioned rats received acute or daily (5 days) i.p. injections of vehicle or anapsos (100 mg/kg) from the 7th day after surgery. Data indicated that nbM lesions induced an increased production of interleukin-1 beta (IL-1 beta), motor hyperactivity and learning impairment, and that anapsos, a vegetal extract with immunomodulatory activity, reversed brain IL-1 beta overexpression and behavioral alterations in lesioned rats. These results confirm the involvement of IL-1 beta in neurodegeneration associated with cholinergic deficits and the potential utility of compounds with neuroimmunotrophic activity as a new therapeutic strategy in neurodegenerative disorders.

Adjuvants, Immunologic↗
PubMed1996

Phase II study of cisplatin, 5-fluorouracil, and leucovorin in inoperable squamous cell carcinoma of the esophagus. ONCOPAZ Cooperative Group, Spain.

Cisplatin (P) and 5-fluorouracil (5FU) have demonstrated activity for the treatment of squamous cell carcinoma of the esophagus. Previous studies have shown that leucovorin (L) may potentiate the antitumoral activity of 5FU, so we tested the combination P-5FU-L in 31 patients with inoperable squamous cell esophageal carcinoma. Chemotherapy consisted of P 20 mg/m2 in 4 h, followed by L 200 mg/m2 in 2 h and 5FU 600 mg/m2 in 18 h. This schedule was repeated for 5 days every 4 weeks. The treatment plan included three courses of chemotherapy followed by radiotherapy. The overall response rate was 58% (95% CI = 39-76%), with one complete remission (3%), and 61% of patients reported an improvement in dysphagia. Gastrointestinal toxicity was the main side effect: grade 3-4 mucositis appeared in 19% of patients, grade 3-4 nausea/vomiting in 13%, and grade 3-4 diarrhea in 6.5%. There was one toxic death caused by neutropenia and sepsis. Nineteen patients received local radiotherapy after chemotherapy, which increased the overall response rate to 63% (5% complete responses). Dysphagia improved in 75% of them. The median survival for all patients was 11 months. This study shows that sequential therapy with P-5FU-L and radiotherapy achieves a high response rate as well as adequate symptomatic relief in patients with inoperable esophageal cancer. The results justify further evaluation of P-5FU-L in patients with earlier-stage disease.

Adult↗
PubMed1996

Note: comparison of media for the isolation of lactose-positive Salmonella.

We studied the capacity of 10 selective media (Rambach agar, RB; salmonella-shigella agar, SS; SM-ID medium, SM; Hektoen enteric agar, HE; modified semisolid Rappaport-Vassiliadis agar, MSRV; bismuth sulphite agar, BS; MacConkey agar, MC; brilliant green agar, BG; novobiocin-brilliant green-glucose agar, NBG; and novobiocin-brilliant green-glycerol-lactose agar, NBGL), and the C8-esterase test (MUCAP test, Biolife, Italy) to detect the growth of 14 strains of lactose-positive Salmonella (12 Salm. virchow and two Salm. montevideo) and 16 Salm. arizonae. Suspensions of pure strain were plated on the aforementioned media and on Mueller-Hinton, used as a control, with inocula of 3 x 10(2) cfu ml-1. The performance of BS was excellent, determining the 30 strains as typical Salmonella colonies (H2S+). On NBG, 27 strains were detected. On MSRV, only some strains grew and only one produced swarming. On the other media, the two Salm. montevideo and the 12 Salm. virchow strains produced coliform colonies. Some of these latter were inhibited on BG and NBGL. The 16 Salm. arizonae strains produced typical colonies on all the media, except on RB, SM and MSRV. On NBGL, two strains did not produce H2S. The C8-esterase test was only successful with Salm. montevideo and Salm. virchow on NBG and RB (with a few exceptions on the latter). However, with Salm. arizonae the test was positive on SS, MC, HE, BG and NBG. In summary, BS was the best medium of those used (all the 30 strains were isolated), followed by NBG (27 isolates).

Culture Media↗