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Biomedical subjects

J L Ramirez

Publications and source records attributed to J L Ramirez.

50 records · Page 3Linked to original sources
PubMed1987

Influence of season on estrous and luteinizing hormone responses to estradiol benzoate in ovariectomized sows.

The objective of this experiment was to determine whether seasonal differences existed in estrous and LH responses to estradiol benzoate (EB) in ovariectomized sows. Sows were ovariectomized after weaning their first litter, and treatment was begun 120 d after ovariectomy. Sows were given 400 mug EB intramuscularly (i.m.) on July 24, 1982 (summer), October 24, 1984 (fall), January 29, 1985 (winter), and March 27, 1985 (spring). Beginning 24 h after EB, sows were checked for estrus four times daily. Proportion in estrus was affected by season, with all sows exhibiting estrus within 5 d after EB in summer, winter, and spring. Only three of five sows exhibited estrus within 5 d after EB in fall. Interval (h) to estrus was delayed in fall (80 h) compared to other seasons (62.6 h; SEM = 4.5). Concentrations of LH were suppressed within 6 h after EB in all seasons but rebounded to pre-injection levels more slowly in fall and spring than in winter and summer. Frequency of LH peaks (3.2 +/- .4 4 h ) was not affected by season, but amplitude (1.9 vs 0.9 ng/ml) and baseline (2.7 vs 1.6 ng/ml) were greater (P < 0.05) for summer than for the other seasons combined. At 6 h after injection, concentrations of estradiol-17beta (pg/ml) were greater in summer (58.3) than in fall (19.0), winter (32.4), or spring (16.6; SEM = 10.4). We conclude that environmental factors associated with season alter responsiveness of the brain to estradiol, thereby controlling sexual behavior and LH secretion.

Journal Article↗
PubMed1982

Creation of a data base for sequences of ribosomal nucleic acids and detection of conserved restriction endonucleases sites through computerized processing.

As part of a project pertaining the organization of ribosomal genes in Kinetoplastidae, we have created a data base for published sequences of ribosomal nucleic acids, with information in Spanish. As a first step in their processing, we have written a computer program which introduces the new feature of determining the length of the fragments produced after single or multiple digestion with any of the known restriction enzymes. With this information we have detected conserved SAU 3A sites: (i) at the 5' end of the 5.8S rRNA and at the 3' end of the small subunit rRNA, both included in similar larger sequences; (ii) in the 5.8S rRNA of vertebrates (a second one), which is not present in lower eukaryotes, showing a clear evolutive divergence; and, (iii) at the 5' terminal of the small subunit rRNA, included in a larger conserved sequence. The possible biological importance of these sequences is discussed.

Animals↗
PubMed1980

Pharmacokinetics of oral and intravenous indomethacin in preterm infants.

The pharmacokinetic profile of indomethacin administered either orally or intravenously in 13 preterm infants with significant patent ductus arteriosus (PDA) is reported. 9 infants received oral indomethacin and 4 received intravenous therapy. Plasma half-life was significantly prolonged as compared to adult values and demonstrated significant correlation with gestational age. Mean half-life in neonates less than 32 weeks gestation was 17.2 (0.8) vs. 12.5 (0.5) h for neonates greater than 32 weeks gestation. Bioavailability of the oral dosage based on AUC was 13% but no difference was observed in the plasma protein binding or distribution volume of drug as compared to adult values. No serious complications could be attributed to the use of indomethacin at these dose levels in the premature infant.

Administration, Oral↗
PubMedDate not supplied

Trypanosomatidae codon usage and GC distribution.

A study of Trypanosomatidae GC distribution and codon usage is presented. The codon usage patterns in coincidence with the phylogenetical data are similar in Crithidia and Leishmania, whereas they are more divergent in Trypanosoma brucei and T. cruzi. The analysis of the GC mutational pressure in these organisms reveals that T. brucei, and to a lesser extent T. cruzi, have evolved towards a more balanced use of all bases, whereas Leishmania and Crithidia retain features of a primeval genetic apparatus. Tables with the approximated GC mutational pressure in homologous genes, and codon usage in Trypanosomatidae are presented.

Animals↗
PubMedDate not supplied

The Trypanosoma cruzi genome project: nuclear karyotype and gene mapping of clone CL Brener.

By using improved pulsed field gel electrophoresis conditions, the molecular karyotype of the reference clone CL Brener selected for Trypanosoma cruzi genome project was established. A total of 20 uniform chromosomal bands ranging in size from 0.45 to 3.5 Megabase pairs (Mbp) were resolved in a single run. The weighted sum of the chromosomal bands was approximately 87 Mbp. Chromoblots were hybridized with 39 different homologous probes, 13 of which identified single chromosomes. Several markers showed linkage and four different linkage groups were identified, each comprising two markers. Densitometric analysis suggests that most of the chromosomal bands contain two or more chromosomes representing either homologous chromosomes and/or heterologous chromosomes with similar sizes.

Animals↗
PubMedDate not supplied

Evaluation of DNA recombinant methodologies for the diagnosis of Plasmodium falciparum and their comparison with the microscopy assay.

Since 1984, DNA tests based on the highly repeated subtelomeric sequences of Plasmodium falciparum (rep 20) have been frequently used in malaria diagnosis. Rep 20 is very specific for this parasite, and is made of 21 bp units, organized in repeated blocks with direct and inverted orientation. Based in this particular organization, we selected a unique consensus oligonucleotide (pf-21) to drive a PCR reaction coupled to hybridization to non-radioactive labeled probes. The pf-21 unique oligo PCR (pf-21-I) assay produced DNA amplification fingerprints when was applied on purified P. falciparum DNA samples (Brazil and Colombia), as well as in patient's blood samples from a large area of Venezuela. The performance of the Pf-21-I assay was compared against Giemsa stained thick blood smears from samples collected at a malaria endemic area of the Bolivar State, Venezuela, at the field station of Malariología in Tumeremo. Coupled to non-radioactive hybridization the pf-21-I performed better than the traditional microscopic method with a r = 1.7:1. In the case of mixed infections the r value of P. falciparum detection increased to 2.5:1. The increased diagnostic sensitivity of the test produced with this homologous oligonucleotide could provide an alternative to the epidemiological diagnosis of P. falciparum being currently used in Venezuela endemic areas, where low parasitemia levels and asymptomatic malaria are frequent. In addition, the DNA fingerprint could be tested in molecular population studies.

Animals↗
PubMedDate not supplied

Generation of memory CD4+, CD8+, CD45RO+ and CD16- lymphocytes activated with IL-2, INF-gamma, and TNF-alpha with specific cytotoxicity against autologous cervical cancer cells in a mixed leukocyte-tumour cell culture.

Cytotoxic T lymphocytes (CTL) specific against autologous human cervical cancer cells were generated in vitro from peripheral blood leukocytes (PBL) from four patients with non-keratinized epidermoid carcinoma. For this purpose, these patients' PBL were co-cultured for 28 days either with IL-2 or a mixture of IL-2, IFN-gamma and TNF-alpha in the presence of autologous tumour cells (ATC). Our results showed that these CTL were highly cytotoxic for ATC, weakly cytotoxic for heterologous cervical cancer tumour cells, and not cytotoxic for carcinoma cell lines, normal cervix cells nor autologous PBL. Proliferation and cytotoxicity against ATC were greater when the PBL were activated with the three cytokines. These CTL had a CD4:CD8 ratio of 1:1, were CD16- and CD45RO+ and their killing activity was inhibited by antibodies against CD3, CD8 and MHC-class I but not by antibodies against CD4, CD16 or HLA-class II. The possibility of generating specific CTL in long term cultures for cervical cancer therapy is also discussed.

Antibodies, Monoclonal↗