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Biomedical subjects

L Salazar

Publications and source records attributed to L Salazar.

At least 19 recordsLinked to original sources
PubMed2006

Identification of fatty acid esters and hydrocarbon derivatives from Cyrtocarpa procera Kunth by GC-MS.

Extracts obtained from Cyrtocarpa procera Kunth were evaluated to determine their toxicity on Artemia salina Leach. All the extracts showed a significant activity. Bioguided fractionation of these extracts led to the isolation of beta-sitosterol and the identification of 1,3-propyl-dipentadecanoate, 3-hydroxypropyl-9-octadecenoate, pentadecylbenzene, eicosylbenzene, docosane, heptacosane, dotriacontane and 2,6,10-trimethyltetradecane by GC-MS.

Anacardiaceae↗
PubMed2004

The ambrosanolide cumanin inhibits macrophage nitric oxide synthesis: some structural considerations.

Since its role in inflammatory diseases was recognized, nitric oxide (NO) has become an important mediator to evaluate anti-inflammatory agents. Sesquiterpene lactones, which occur in several medicinal plants, inhibit the NO production in macrophage-like cells. This action is probably due to a 1,4 addition reaction between its alpha,beta-unsaturated carbonyl group with sulfhydryl (SH)-containing compounds. For this reason it is believed that these compounds are cytotoxic, which restricts their therapeutic use. In this contribution, the ability of the ambrosanolide-type sesquiterpene lactone cumanin (from the Asteraceae Ambrosia psilostachya) to inhibit NO biosynthesis was evaluated in lipopolisaccharide-induced peritoneal murine macrophages and its cytotoxicity was assessed in the MTT assay. Cumanin showed a potent inhibitory effect in NO production (IC(50) = 9.38+/-0.38 microM) with low cytotoxicity. The 1,4-addition reaction of thiols was slow, which does not explain the inhibition of NO production but does explain the low cytotoxicity of cumanin with respect to other lactones.

Ambrosia↗
PubMed2003

Psychosocial impact of serological diagnosis of herpes simplex virus type 2: a qualitative assessment.

OBJECTIVES: To assess the emotional and psychosocial responses to a serological diagnosis of HSV-2 infection in individuals without previous history of genital herpes. METHODS: 24 individuals who had a positive HSV-2 serology by western blot and no clinical history of disease were recruited from four clinics (sexually transmitted disease, maternal and infant care, family medicine, and virology research) over a 10 month period. In-depth qualitative interviews were conducted to elicit an individual's responses to the HSV-2 diagnosis. RESULTS: Three categories of themes were identified from the interviews. Short term emotional responses included surprise, denial, confusion, distress, sadness, disappointment, and relief to know. Short term psychosocial responses included fear of telling sex partners, anger at the source partner, guilt about acquiring or transmitting, and concern about transmitting to a child. Perceived ongoing responses included fear of telling future partners, concern about transmitting to a sex partner, feeling sexually undesirable, feeling socially stigmatised, feeling like "damaged goods," sex avoidance due to social responsibility, fear of transmitting to a newborn, and relationship concerns relating to the diagnosis. CONCLUSIONS: Individuals exhibit strong emotional and psychosocial responses to a serological diagnosis of HSV-2 infection. Many of the negative responses may be time limited and influenced by factors that are potentially amenable to counselling.

Adult↗
PubMed2002

Vaccination against the HER-2/neu oncogenic protein.

The HER-2/neu oncogenic protein is a well-defined tumor antigen. HER-2/neu is a shared antigen among multiple tumor types. Patients with HER-2/neu protein-overexpressing breast, ovarian, non-small cell lung, colon, and prostate cancers have been shown to have a pre-existent immune response to HER-2/neu. No matter what the tumor type, endogenous immunity to HER-2/neu detected in cancer patients demonstrates two predominant characteristics. First, HER-2/neu-specific immune responses are found in only a minority of patients whose tumors overexpress HER-2/neu. Secondly, immunity, if detectable, is of low magnitude. These observations have led to the development of vaccine strategies designed to boost HER-2/neu immunity in a majority of patients. HER-2/neu is a non-mutated self-protein, therefore vaccines must be developed based on immunologic principles focused on circumventing tolerance, a primary mechanism of tumor immune escape. HER-2/neu-specific vaccines have been tested in human clinical trials. Early results demonstrate that significant levels of HER-2/neu immunity can be generated with active immunization. The T-cell immunity elicited is durable after vaccinations have ended. Furthermore, despite the generation of CD8(+) and CD4(+) T-cells responsive to HER-2/neu in a majority of patients, there is no evidence of autoimmunity directed against tissues that express basal levels of the protein. Cancer vaccines targeting the HER-2/neu oncogenic protein may be useful adjuvants to standard therapy and aid in the prevention of relapse in patients whose tumors overexpress the protein. Furthermore, boosting HER-2/neu-specific T-cell frequencies via active immunization may allow the ex vivo expansion of HER-2/neu-specific T-cells for use in adoptive immunotherapy, a therapeutic strategy directed against the treatment of established disease.

Animals↗
PubMed2001

Microbiological condition of ground meat retailed in Monterrey, Mexico.

Eighty-eight samples of ground meat were randomly collected from retail stores in the metropolitan area of Monterrey, Mexico, and were analyzed for microbial contamination. Methods were those recommended by the Mexican regulation and/or the U.S. Food and Drug Administration. Over 75% of the samples contained > 10(5) total mesophilic microorganisms per g, and over 40% had >10(6) total coliforms per g. Fecal coliforms were present in most samples. Staphylococcus aureus was detected in 2.3% of the samples, Salmonella spp. in 11.4%, Listeria spp. in 62%, and L. monocytogenes in 16%. Escherichia coli was detected in 76% of samples, but none was serotype O157:H7. Shigella spp. was not found in any sample. Fusarium spp. and Mucor spp. were detected in 3.4% of the samples, and low levels of yeast in 93%. The microbiological quality of the ground meat analyzed was unsatisfactory, and the product could be an important cause of food poisoning.

Animals↗
PubMed2001

[Cellular cycle control in mycobacteria].

Possibly the failure to eradicate the tuberculosis is linked to the pathogenesis of the causative organism, Mycobacterium tuberculosis. These bacteria can lie quiescent in the human host and later multiplies leading to a higher density of bacteria to increase and, hence at progressive tuberculosis. Particularly unknown is how the mechanism work and which are the molecules responsible for determining if the cells goes to an active replicate process, or in contrast to establish a dormant state. Many genes involved in DNA replication, chromosome segregation and cellular division have been cloned and analysed, and in some bacteria, as E. coli, the cellular cycle events have been described. However, the factors coupling these events are unknown.

Cell Division↗
PubMed2001

[Characterization of the expression and function of SigM an ECF sigma factor in mycobacteria].

The survival of M. tuberculosis within the macrophage depends on its ability to respond to oxidative stress, and the ECF subfamily of sigma factors likely play an important role. We studied SigM, a sigma factor whose gene is located near the origin of DNA replication. In both M. smegmatis and M. bovis BCG, the expression of sigM was induced at high temperature and in stationary phase. Mutants of M. smegmatis without an intact sigM were defective for survival in oxidative stress and also for the induction of thioredoxin reductase activity in oxidative stress. The thioredoxin system reduces disulfide bonds that are formed in oxidative stress. SigM thus appears to regulate thioredoxins and forms part of the bacteria's complex protective responses.

DNA Replication↗
PubMed2001

[Chromosome replication in mycobacteria].

Variation in growth rate has provided a basis for the broad classification of Mycobacterium: (i) the slow-growing class includes the human pathogens Mycobacterium tuberculosis and M. leprae, and (ii) the fast-growing class includes saprophytic nonpathogens, such as M. smegmatis. An intimate association between DNA chromosomal replication and growth rate have been suggested. However, the molecular basis of this relation is unknown. In this article, we summarise our recent work on the study of the origin replication region of some species of mycobacteria, determination of the factors regulating the initiation of DNA replication and the characterisation of the main factor of the replicative machinery, the DnaA protein.

Bacterial Proteins↗
PubMed2000

Survey of drug resistance of Mycobacterium tuberculosis in 3 Mexican states, 1997.

BACKGROUND: Drug resistance threatens global tuberculosis (TB) control efforts. Population-based estimates of drug resistance are needed to develop strategies for controlling drug-resistant TB in Mexico. OBJECTIVE: To obtain population-based data on Mycobacterium tuberculosis drug resistance in Mexico. METHODS: To obtain drug resistance data, we conducted a population-based study of TB cases in the states of Baja California, Sinaloa, and Oaxaca, Mexico. We performed cultures and drug susceptibility testing on M tuberculosis isolates from patients with newly diagnosed, smear-positive TB from April 1 to October 31, 1997. RESULTS: Mycobacterium tuberculosis was isolated from 460 (75%) of the 614 patients. Levels of resistance in new and retreatment TB cases to 1 or more of the 3 current first-line drugs used in Mexico (isoniazid, rifampin, and pyrazinamide) were 12.9% and 50.5%, respectively; the corresponding levels of multi-drug-resistant TB were 2.4% and 22.4%. Retreatment cases were significantly more likely than new cases to have isolates resistant to 1 or more of the 3 first-line drugs (relative risk [RR], 3.9; 95% confidence interval [CI], 2.8-5.5), to have isoniazid resistance (RR, 3.6; 95% CI, 2.5-5.2), and to have multi-drug-resistant TB (RR, 9.4; 95% CI, 4.3-20.2). CONCLUSIONS: This population-based study of M tuberculosis demonstrates moderately high levels of drug resistance. Important issues to consider in the national strategy to prevent M tuberculosis resistance in Mexico include consideration of the most appropriate initial therapy in patients with TB, the treatment of patients with multiple drug resistance, and surveillance or periodic surveys of resistance among new TB patients to monitor drug resistance trends.

Adult↗
PubMed2000

Monoclonal antibodies to human apolipoproteins: application to the study of high density lipoprotein subpopulations.

We produced, selected and cloned hybridomas that secrete monoclonal antibodies against human apolipoprotein (apo) A-I. All of the antibodies corresponded to the IgG(1) subclass and were named 1C11, 2B4, 2C10, 7C5, 8A4 and 8A5. The antibodies were characterized by their reactivity with whole lipoproteins, apolipoproteins, synthetic peptides and fragments generated by cleavage of the apo A-I. Three of the monoclonal antibodies studied (2B4, 2C10 and 7C5) were similarly inhibited by an amino-terminal peptide (amino acid sequence 1-20) of apo A-I, whereas antibodies 1C11, 8A4 and 8A5 had no reaction. Other results show that monoclonal antibody 1C11 recognizes an epitope located between amino acids 135-148. We evaluated the monoclonal antibody 8A4 against different HDL subpopulations by competitive displacement analysis and it showed a similar reactivity with the HDL particles: LpA-I and LpA-I:A-II. This antibody was used to standardize a sandwich ELISA to quantitate LpA-I in plasma. We conclude that these monoclonal antibodies are relevant for the study of apo A-I epitope expression and for quantitating apo A-I containing lipoparticles.

Animals↗
PubMed1996

Efflux pump of the proton antiporter family confers low-level fluoroquinolone resistance in Mycobacterium smegmatis.

Due to the resurgence of tuberculosis and the emergence of multidrug-resistant strains, fluoroquinolones (FQ) are being used in selected tuberculosis patients, but FQ-resistant strains of Mycobacterium tuberculosis have rapidly begun to appear. The mechanisms involved in FQ resistance need to be elucidated if the effectiveness of this class of antibiotics is to be improved and prolonged. By using the rapid-growing Mycobacterium smegmatis as a model genetic system, a gene was selected that confers low-level FQ resistance when present on a multicopy plasmid. This gene, lfrA, encodes a putative membrane efflux pump of the major facilitator family, which appears to recognize the hydrophilic FQ, ethidium bromide, acridine, and some quaternary ammonium compounds. It is homologous to qacA from Staphylococcus aureus, tcmA, of Streptomyces glaucescens, and actII and mmr, both from Streptomyces coelicoler. Increased expression of lfrA augments the appearance of subsequent mutations to higher-level FQ resistance.

Amino Acid Sequence↗
PubMed1996

Gene arrangement and organization in a approximately 76 kb fragment encompassing the oriC region of the chromosome of Mycobacterium leprae.

A continuous 75627 bp segment of the Mycobacterium leprae chromosome spanning the oriC region was sequenced. The gene order at this locus was similar to that found in the replication origin region of many other prokaryotes, particularly Mycobacterium tuberculosis and Streptomyces coelicolor. As in the case of several Gram-positive bacteria, essential genes involved in basic cellular functions, such as DNA or RNA metabolism (dnaA, dnaB, dnaN, gyrB, gyrA, pcnB, recF, rnpA, ssb), cell wall synthesis (ponA, pbpA) and probably cell division (gidB, rodA) were found. Strikingly, the gidA gene was absent from this part of the genome and there was no rRNA operon near oriC. The gyrA gene harbours an intein coding sequence indicating that protein splicing is required to produce the mature A subunit of DNA gyrase. Among the many other noteworthy features were ORFs encoding putative serine/threonine protein kinases and a protein phosphatase, three tRNA genes, one M. leprae-specific repetitive element and a glnQ pseudogene.

Amino Acid Sequence↗
PubMed1996

Organization of the origins of replication of the chromosomes of Mycobacterium smegmatis, Mycobacterium leprae and Mycobacterium tuberculosis and isolation of a functional origin from M. smegmatis.

The genus Mycobacterium is composed of species with widely differing growth rates ranging from approximately three hours in Mycobacterium smegmatis to two weeks in Mycobacterium leprae. As DNA replication is coupled to cell duplication, it may be regulated by common mechanisms. The chromosomal regions surrounding the origins of DNA replication from M. smegmatis, M. tuberculosis, and M. leprae have been sequenced, and show very few differences. The gene order, rnpA-rpmH-dnaA-dnaN-recF-orf-gyrB-gyrA, is the same as in other Gram-positive organisms. Although the general organization in M. smegmatis is very similar to that of Streptomyces spp., a closely related genus, M. tuberculosis and M. leprae differ as they lack an open reading frame, between dnaN and recF, which is similar to the gnd gene of Escherichia coli. Within the three mycobacterial species, there is extensive sequence conservation in the intergenic regions flanking dnaA, but more variation from the consensus DnaA box sequence was seen than in other bacteria. By means of subcloning experiments, the putative chromosomal origin of replication of M. smegmatis, containing the dnaA-dnaN region, was shown to promote autonomous replication in M. smegmatis, unlike the corresponding regions from M. tuberculosis or M. leprae.

Bacterial Proteins↗
PubMed1996

Estradiol and progesterone endometrial receptors and body fat distribution in obese women.

The content of endometrial receptors for estradiol (ER) and progesterone (PR) was determined in three groups (10 women each) classified with respect to body fat distribution: (1) normal, nonobese; (2) lower body segment obesity and (3) upper body segment obesity. The ER in group 3 were significantly (p < 0.05) higher than those of group 1. As regards PR, no statistical differences were found among the three groups. These findings demonstrate different endometrial ER concentrations in obese women according to body fat distribution, greater in upper segment obesity. Probably the lack of progesterone as well as other factors in the endocrine milieu of these patients may determine the differences found; therefore, future research on this matter should be carried out.

Adult↗
PubMed1994

Cloning and nucleotide sequence of Mycobacterium tuberculosis gyrA and gyrB genes and detection of quinolone resistance mutations.

The emergence of multidrug-resistant strains of Mycobacterium tuberculosis has resulted in increased interest in the fluoroquinolones (FQs) as antituberculosis agents. To investigate the frequency and mechanisms of FQ resistance in M. tuberculosis, we cloned and sequenced the wild-type gyrA and gyrB genes, which encode the A and B subunits of the DNA gyrase, respectively; DNA gyrase is the main target of the FQs. On the basis of the sequence information, we performed DNA amplification for sequencing and single-strand conformation polymorphism analysis to examine the presumed quinolone resistance regions of gyrA and gyrB from reference strains (n = 4) and clinical isolates (n = 55). Mutations in codons of gyrA analogous to those described in other FQ-resistant bacteria were identified in all isolates (n = 14) for which the ciprofloxacin MIC was > 2 micrograms/ml. In addition, we selected ciprofloxacin-resistant mutants of Mycobacterium bovis BCG and M. tuberculosis Erdman and H37ra. Spontaneously resistant mutants developed at a frequency of 1 in 10(7) to 10(8) at ciprofloxacin concentrations of 2 micrograms/ml, but no primary resistant colonies were selected at higher ciprofloxacin concentrations. Replating of those first-step mutants selected for mutants with high levels of resistance which harbored gyrA mutations similar to those found among clinical FQ-resistant isolates. The gyrA and gyrB sequence information will facilitate analysis of the mechanisms of resistance to drugs which target the gyrase and the implementation of rapid strategies for the estimation of FQ susceptibility in clinical M. tuberculosis isolates.

Anti-Infective Agents↗
PubMed1992

Characterization and nucleotide sequence of the oriT-traM-finP region of the IncFVII plasmid pSU233.

By hybridizing the IncFVII haemolytic plasmid pSU233 with a probe containing the origin of transfer of the IncFII plasmid R1, we isolated a 1.9 kb BglII fragment containing at least the origin of transfer (oriT), and the genes traM and finP. Functional complementation analysis of deletion derivatives was used to map the origin of transfer. We also determined the nucleotide sequence of traM and finP. Comparison with similar regions of several plasmids, also belonging to the Rep-FIIA family, revelaed that pSU233 resembles the F plasmid by very close. The homology is not evenly distributed along this region, but clustered into homologous regions (TraZb-oriT, TraMb-oriT and traM separated by non-homologous regions (TraYb-oriT, finP). This organization resembles that reported for the replication region and also suggests evolution by exchange of modules. In addition, the nucleotide sequence of finP is different from those previously described for other IncF plasmids and constitutes a new allele, which we have denominated allele VI.

Amino Acid Sequence↗