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Biomedical subjects

M Salazar

Publications and source records attributed to M Salazar.

At least 91 records · Page 5Linked to original sources
PubMed1992

Functional deficiency of antigen-presenting cells in the synovial fluid of rheumatoid arthritis.

In our study of rheumatoid arthritis (RA) patients, we observed a decrease of tetanus toxoid antigen-presenting capacity of synovial fluid (SF) adherent cells to autologous T cells of either SF or peripheral blood. Additionally, we found a higher capacity of adherent synovial cells to stimulate autologous T-lymphocytes. Our results suggest that antigen-presenting cells of the SF of RA patients have defects that may play a role in defective presentation of antigens in joints and may account for other abnormal functions important in the pathogenesis of RA.

Adult↗
PubMed1992

Traits that influence longevity in mice: a second look.

Analysis of genetic interactions in the F2 of an intercross of (C57BL/6 x DBA/2) F1J revealed influences of genetic factors on life span. Females lived longer than males. Dilute brown females died sooner than females of other colors. H-2b/H-2b males died sooner than H-2b/H-2d or H-2d/H-2d males, except that among dilute brown males those of typeH-2b/H-2d died sooner. Cluster analysis suggested that male and female genotypes each fall into two groups, with female dilute brown mice having shorter lives than other females, and male H-2b/H-2b mice except dilute brown and dilute brown H-2b/H-2d mice having shorter lives than other males. The association of heterozygosity with life span was clearer in females than in males, yet the longest-lived female genotype was homozygous H-2d/H-2d, of dominant Black phenotype at the Brown locus of chromosome 4, and homozygous dd at the Dilute locus of chromosome 9. The shortest-lived females were dilute brown H-2b/H-2b. The longest-lived and shortest-lived male genotypes were dilute brown H-2d/H-2d and dilute brown H-2b/H-2d, respectively. Although histological findings at postmortem differed between the sexes, there was no association of particular disorders with other genetic markers. The importance of H-2 in males was confirmed, but the allelic effects were perturbed, possibly by the absence of Sendai infection in this experiment. Overall our studies suggest that genetic influences on life span involve interactions between loci, and allelic interactions may change with viral infections or other environmental factors.

Animals↗
PubMed1992

Range of action and genetic bacteriocin codification of Pseudomonas aeruginosa isolated from three different ecological niches.

Strains of Pseudomonas aeruginosa isolated from sediments in wells showed a greater bacteriocinogenic activity in those isolated from river and clinical specimens. More than half of all the strains examined had extrachromosomal DNA. Plasmid DNA was extracted from all the strains and in only 24/120, all from different origins, was the curing achieved; all these strains coded their bacteriocins in the chromosomal DNA.

Bacteriocins↗
PubMed1992

HLA-DQA1 and MLC among HLA (generic)-identical unrelated individuals.

We modified a previously published PCR-RFLP for DQA1 typing (1) and examined the predictive value of HLA-DQA1 in mixed lymphocyte cultures (MLC) among matched (HLA generic types) pairs of unrelated individuals. There were 61/102 (60%) pairs with positive MLC, one-third of which could be predicted by DQA1* typing alone. DQA1 matching and MLC reactions were classified into 3 groups: 1) DQA1 mismatches showing positive MLC: 19/102 (19%); 2) DQA1 matches showing negative MLC: 41/102 (40%); 3) DQA1 identical showing positive MLC: 42/102 (41%). Five different HLA haplotypes that result from non-random association of HLA generic types (high delta haplotypes) were overrepresented in the individuals tested. One of these haplotypes carrying HLA-B7, DR2 was found associated with three different DQA1 alleles (*0201, *0103, *0102). The remaining four high delta haplotypes were associated with one DQA1 allele in all independent examples tested: HLA-A1, B8, DR3 with DQA1*0501; HLA-A26, B38, DR4 with DQA1*0301; HLA-A2, Bw62, DR4 with DQA1*0301 and HLA-A1, Bw57, DR7 with DQA1*0201. Forty per cent of the negative MLC were explained in part by the excessive number of individuals carrying two of these four haplotypes, which probably carry determinants in linkage disequilibrium with HLA. Nineteen per cent of HLA-identical (generic types) unrelated pairs show positive MLC reactions and all of them are DQA1* mismatched, suggesting that DQA1* allele typing should be used to screen samples prior to performing MLC.

Alleles↗
PubMed1992

HLA-DPB1 allele mismatches between unrelated HLA-A,B,C,DR (generic) DQA1-identical unrelated individuals with unreactive MLC.

We have used a PCR-RFLP method with one generic amplification of HLA-DPB1 second exon and 6 endonucleases to differentiate the 19 HLA-DPB1 alleles and 171 heterozygous combinations. The set of primers used in our studies produced fragment sizes different from those published before (1). The HLA-DPB1 alleles in Caucasians showed a higher frequency of DPB1*0401 and DPB1*0402, when compared to a small group of Colombians who showed a higher frequency of DPB1*0402 and DPB1*0201. We found three HLA-DPB1 alleles associated with two HLA haplotypes that result from non-random association of alleles: DPB1*0401 with HLA-A26, B38, DR4, DQA1*0301 and DPB1*0101 and DPB1*0401 with HLA-A1, B8, DR3, DQA1*0501. We also report that 70% of combinations between HLA (generic A,B,C,DR) and DQA1-identical MLC-unreactive cell mixtures showed HLA-DPB1 mismatches, suggesting that HLA-DPB1 differences are not important in MLC reactivity.

Alleles↗
PubMed1992

HLA-DQB1 allele typing by a new PCR-RFLP method: correlation with a PCR-SSO method.

We have developed a new PCR-RFLP method for HLA-DQB1 typing. This method was easy to follow, requiring only one DQB1 generic amplification and 5 endonucleases to assign 14 out of 15 HLA-DQB1 alleles. In addition, we determined that by using one generic amplification and two enzymes (Sau96 I and Hae III) it was possible to type the generic specificities: DQw2, DQw4, DQw5, DQw6, and DQw7, DQw8-9, providing a practical alternative for serological HLA-DQ generic typing. We also performed a side-by-side correlation with a PCR-SSO typing method and found an almost 100% concordance between the methods. The limitations of these methods were: 1) the PCR-RFLP method did not allow the differentiation between the HLA-DQB1*0602 and *0603 alleles; 2) the PCR-SSO method gave crosshybridization signals in the detection of *0302 or *0303 alleles. Our results suggested that both methods, PCR-RFLP and PCR-SSO, are useful alternatives for HLA-DQB1 typing.

Alleles↗
PubMed1992

[Teratogenic action of alpha-asarone in the mouse].

The embryotoxicity and teratogenicity of alpha-asarone were investigated in mice. The drug was dissolved in corn oil, and administered daily, by gavage, on days 6 to 15 of gestation, at 0 (controls), 5, 15, 30 and 60 mg/kg. Fetuses were removed on day 18 by caesarean section and examined using routine teratological methods. A significant maternal toxicity was observed in dams given 60 mg/kg, as indicated by a reduced weight gain. An embryolethality was observed in 15, 30 and 60 mg/kg treated groups. In addition, the highest dose induced fetal malformations, mainly represented by hydrocephaly, extra-ribs, clubfeet and cleft lips.

Abnormalities, Drug-Induced↗
PubMed1991

The cellular basis for lack of antibody response to hepatitis B vaccine in humans.

We had previously obtained evidence that among normal subjects the humoral antibody response to hepatitis B surface antigen (HBsAg) was bimodally distributed with about 14% of subjects producing less than 1,000 estimated radioimmunoassay RIA units. From the study of major histocompatibility complex (MHC) markers in the very poor responders who produced less than 36 estimated RIA units of antibody, it appeared that there was an excess of homozygotes for two extended haplotypes [HLA-B8, SC01, DR3] and [HLA-B44, FC31, DR7]. This finding suggested that a poor response was inherited as a recessive trait requiring nonresponse genes for HBsAg on both MHC haplotypes and was strengthened by finding a much lower antibody response among prospectively immunized homozygotes for [HLA-B8, SC01, DR3] compared with heterozygotes. In the present study, we have analyzed the cellular basis for nonresponse to this antigen by examining antigen-specific proliferation of T cells from responders and nonresponders in the presence and absence of autologous CD8+ (suppressor) cells. Peripheral blood cells from nonresponders to HBsAg failed to undergo a proliferative response to recombinant HBsAg in vitro, whereas cells from responders proliferated vigorously. This failure of cells from nonresponders to proliferate was not reversed in cell mixtures containing CD4+ and antigen-presenting cells devoid of CD8+ cells. There was no difference between responders and nonresponders with respect to the number of circulating T cells or their subsets, or the proliferative response to mitogens such as pokeweed or phytohemagglutinin or another antigen, tetanus toxoid. Our results indicate that our HBsAg nonresponding subjects have a very specific failure in antigen presentation or the stimulation of T helper cells, or both. Our evidence is against specific immune suppression as the basis for their nonresponsiveness. The failure of antigen presentation or T cell help is consistent with recessive inheritance of nonresponsiveness and suggests that response is dominantly inherited.

Antibody Formation↗
PubMed1991

Cytogenetic and teratogenic evaluation of letimide.

Letimide is a new efficient analgesic salicylate derivative. In this study we evaluated its cytogenetic and teratogenic potential. For chromosomal aberrations and sister chromatid exchange analysis we tested 250, 375, 500 and 625 micrograms/ml of letimide in human lymphocyte cultures in vitro, and for the in vivo cytogenetic study analysing the same parameters we studied the effects of 30, 50 and 100 mg/kg in mouse bone marrow cells. The teratogenic study was performed at dosages of 50, 100 and 200 mg/kg/d of letimide in mice. The results agree with the systems studied previously, showing no significant effect in the rate of aberrations, sister chromatid exchanges or congenital malformations induced by this new analgesic.

Adult↗
PubMed1991

Production of platelet-derived growth factor by human lung cancer.

The production of platelet-derived growth factor (PDGF) was studied in small cell lung carcinoma, lung squamous carcinoma and lung adenocarcinoma cell lines, and in seven human lung tissues obtained from each type of lung cancer. By indirect immunofluorescence, PDGF was detected in all the cell lines. Likewise, five out of seven biopsies derived from patients with adenocarcinoma and squamous carcinoma, and four out of seven specimens with small cell carcinoma displayed a positive pattern for PDGF. In addition, lung carcinoma cell lines expressed both PDGF-A and PDGF-B/sis genes, as judged by Northern blot analysis. Biologically active, serum-free conditioned media obtained from all three cell lines stimulated the incorporation of [3H]thymidine into quiescent BALB/c-3T3 cells. This effect was abolished when IgG-PDGF antiserum was used. These findings suggest that an abnormal expression of PDGF occurs in the three more frequent types of lung cancer, which can play a potential role in neoplastic transformation and uncontrolled cell growth.

Adenocarcinoma↗
PubMed1991

HLA-DR generic typing by AFLP.

We have described a practical and inexpensive method whereby any individual can be typed and assigned to any of the 14 generic HLA-DR types: DR1, DRw15, DRw16, DRw17, DRw18, DR4, DRw11, DRw12, DRw13, DRw14, DR7, DRw8, DR9 and DRw10. Previous methods to type these specificities include - among others - serology, conventional RFLP, PCR-oligonucleotide typing, and a PCR-RFLP method useful for typing homozygous individuals. In the method reported here, DNA is amplified with a set of group-specific primers and then restricted with a number of endonucleases. Six group-specific pairs of primers have been chosen to avoid cross-amplification with other DRB alleles, including DRB3, DRB4 and DRB5 alleles, and to anneal at uniform temperature: 61 degrees C. Endonucleases were chosen to generate unique patterns of easily recognizable bands that led to unequivocal assignments of HLA-DR generic types in heterozygous as well as homozygous individuals. This technique involves two steps: 1) Amplification of DNA with six different pairs of primers where DR1, DR4 and DRw10 types can be assigned at once, and 2) Endonuclease digests of amplified DNA to assign DR7, DRw8, DR9, DRw11, DRw12, DRw13, DRw14, DRw15, DRw16, DRw17 and DRw18 types. Individuals carrying any combination of all alleles published so far can be typed by this method. The ease, low cost and reliability of this method are discussed.

Alleles↗
PubMed1991

Diversity and origin of rheumatologic autoantibodies.

A hallmark of sera from patients with systemic rheumatic diseases is the presence of circulating autoantibodies directed against nuclear antigens. The identification of the antigens binding to these antibodies has provided the cell biologist and the immunologist with important tools to study cell structure, cell function, and the processes underlying the immune response. Through the elucidation of autoantibody specificities, the clinician has been provided with a better appreciation of the diagnostic and prognostic significance of autoantibodies. Many autoantigens, including those directed against components in the nuclear matrix, chromosomes, Golgi apparatus, and other intracellular antigens, are not yet characterized nor is their clinical significance established. The mechanisms leading to the breakdown of tolerance and the appearance of autoantibodies are not fully understood. Molecular mimicry at an interspecies or an intracellular level may be involved in altering immune tolerance. On the other hand, studies of epitopes on human autoantigens has provided compelling evidence that most autoantibody responses seen in systemic rheumatic diseases are driven by endogenous antigen.

Amino Acid Sequence↗
PubMed1990

[Teratogenic study of Spirulina in mice].

The embryotoxic and fetotoxic potential of Spirulina was investigated in mice. The algae was given to pregnant animals at the levels of 0, 10, 20 and 30 g/100 in the diet through days 7-13, 1-13 and 1-19 of gestation. On day 19, the rats were sacrificed, and the uterine horns were examined for live, dead and resorbed fetuses. The live fetuses were weighed and examined for external malformations and either skeletal or visceral abnormalities. With the litter as the unit of analysis and when the total number of fetuses affected was considered, no significant difference was found in the number of resorbed or malformed among groups. These results indicate that the feeding of pregnant mice with algae, up to a dietary level of 30 g/100, did not evoke any signs of embryotoxic effects. The Spirulina levels tested in this study represent exaggeration over any anticipated human consumption.

Abnormalities, Drug-Induced↗
PubMed1989

Teratological evaluation of Juniperus sabina essential oil in mice.

Juniperus sabina essential oil was evaluated for its fetotoxic potential on mice. Pregnant dams were injected s.c. (15-45 or 135 mg essential oil/kg body weight) on days 6 to 15 of gestation. They were killed and the uterine contents were examined on day 19 of pregnancy. The fetuses were removed for examination. The dams of the two higher treated groups showed a significant weight loss as compared to controls. An hepatotoxicity was observed among females that resorbed their whole litter, thus indicating a greater susceptibility towards Juniperus sabina essential oil during pregnancy. The essential oil induced, in the three treated groups, an embryotoxicity as manifested by a statistically significant increase in the number of affected litters; but no fetotoxicity.

Animals↗
PubMed1989

Tuberculosis of the larynx: clinical aspects in 19 patients.

Laryngeal tuberculosis continues to exist in spite of extensive tuberculosis eradication campaigns. We present 19 cases of laryngeal tuberculosis seen in our institution between 1982 and 1987. From the clinical findings it is clear that the localization of the lesions has changed since the preantibiotic era. Today the spread appears to be mainly via lymphatic and hematogenic routes, as opposed to the direct spread more common previously. The fibrosis caused by the lesions is incapacitating and frequently requires surgical correction.

Adolescent↗
PubMed1989

[Teratogenic study of Spirulina in rats].

The algae Spirulina has been considered for use as a supplementary protein to feed and food. Any form of single cell protein destined to this purpose should be previously subjected to detailed toxicological investigations in animals or another experimental models. The present study was therefore designed to determine the teratogenic potential of Spirulina in rats. The algae was administered in the diet at the levels of 0, 10, 20 and 30 g/100 g on days 7-14, 1-14 and 1-21 of gestation. The dams were sacrificed prior to term, and the fetuses examined for external, visceral and skeletal abnormalities. Maternal and fetal weights were not affected. Neither fetotoxicity nor teratogenicity was associated with the dietary ingestion of Spirulina. It is also considered important to extend these studies to other animal species.

Abnormalities, Drug-Induced↗