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Biomedical subjects

M J Torres

Publications and source records attributed to M J Torres.

At least 73 records · Page 4Linked to original sources
PubMed1998

Circulating CLA+ lymphocytes from children with atopic dermatitis contain an increased percentage of cells bearing staphylococcal-related T-cell receptor variable segments.

BACKGROUND: Atopic dermatitis is an allergic T-cell mediated skin inflammation. Staphylococcus aureus colonization is very common in cutaneous atopic dermatitis lesions. The cutaneous lymphocyte-associated antigen (CLA) is a T cell skin homing receptor that defines T lymphocytes associated with the cutaneous immune response. OBJECTIVE: To study whether CLA+ T cells from atopic dermatitis children present a selective expression for Staphylococcus aureus-related TCR Vbeta segments. METHODS: Peripheral blood T cells were stained with HECA-452 (anti-CLA) and a panel of TCR Vbeta specific monoclonal antibodies and analysed by flow cytometry. RESULTS: Atopic dermatitis patients have a higher percentage of circulating CLA+ CD3+ lymphocytes compared with healthy controls. Patients with active atopic dermatitis during the study expressed a higher percentage of cells positive for the TCR Vbeta2 and Vbeta5.1 segments in the CLA+ but not in the CLA- subset. These TCR Vbetas are recognized by staphylococcal superantigens. Moreover, there was an increased percentage of HLA-DR+ expression by CLA+ Vbeta5.1+ T cells in patients with active atopic dermatitis, but those patients whose eczema was inactive had very similar values to healthy controls regarding TCR Vbeta and HLA-DR phenotype in circulating CLA+ T lymphocytes. CONCLUSION: Our data indicate that circulating skin-homing T cells of patients with active atopic dermatitis contain an increased percentage of cells bearing TCR Vbeta segments related with Staphylococcus aureus. Staphylococcus superantigens may therefore trigger expansion or at least circulation of appropriate CLA+ T cells.

Antibodies, Monoclonal↗
PubMed1998

New aspects in betalactam recognition.

The data presented in this review confirm that penicillin continues to be the most well defined model for studying drug allergy. The identification of new specificities has improved the understanding of allergy to penicillins, and different well defined subgroups now exist. The capacity of humans to respond to unique penicillin determinants has shown that although penicillin is a very small molecule it can be recognized in different ways by different IgE antibodies. These well defined models have left open the possibility that other betalactams can also induce specific reactions which implies that for diagnostic purposes, in addition to classical determinants, others are required for in vitro and/or in vivo evaluation. When the different subgroups now recognized are compared, not only are there differences in the manner of hapten recognition but also in the evolution of the natural sensitivity and in the capacity for recognizing other structures. The recognition of betalactams by T cells is also important and a number of studies have shown that subjects respond specifically to some aminopenicillins or cephalosporins with good tolerance to benzylpenicillin. The confirmation that these responses can be a T-cell-mediated reaction have been reported not only in vitro by the generation of T cell lines and T cell clones but also in vivo doing skin biopsies in subjects who have developed different types of delayed cutaneous reactions [44]. More studies are needed to determine the structure of T cell epitopes and this will help for a better understanding of both the IgE and IgG-mediated reactions.

Animals↗
PubMed1998

[Characterization of the rpoB gene mutations in clinical isolates of rifampicin-resistant Mycobacterium tuberculosis].

OBJECTIVES: Characterization and frequency of the rpoB gene mutations associated with rifampin resistance in Mycobacterium tuberculosis clinical isolates in Sevilla. METHODS: Characterization of rpoB mutations in 21 rifampicin-resistant strains of M. tuberculosis isolated during a three-year period (1994-1996) by three different molecular methods: a nonradioactive Single-strand conformation polymorphism (SSCP) analysis, DNA sequence analysis and a commercial method the line probe assay InnoLiPA. RESULTS: Five distinct rpoB mutations were identified. Ser531-->Leu mutation was detected in 14 strains (66.7%), H526-->Asp in 3 strains (14.3%), Ans512-->Ser in 1 strain (4.8%), Glu513-->Leu in 1 strain (4.8%). A nine nucleotide deletion (codon 510-513) was found in one strain (4.8%) while in the remaining resistant strain (4.8%) no mutation was detected. CONCLUSIONS: The frequency of the different mutations found in the rpoB gene, associated with rifampicin resistance in Mycobacterium tuberculosis clinical isolates in Seville, are similar to those previously reported. However, two new mutations has been detected: a nine nucleotide deletion (codon 510-513), and the Asn512-->Ser point mutation. The characterization of the mutations in the rpoB gene could serve as epidemiological marker for the rifampicin resistant clinical isolates of M. tuberculosis.

Amino Acid Substitution↗
PubMed1997

Successful administration of cytarabine after a previous anaphylactic reaction.

Cytarabine (Cyt) is an antimetabolite used primarily in the treatment of leukemia, and both immediate and delayed hypersensitivity reactions have been reported. We studied a 9-year-old girl with lymphoblastic leukemia, who developed three anaphylactoid reactions during Cyt treatment courses over a 1-year period. Three years later, Cyt was required again. Although a skin test was negative to Cyt at the concentration of 4 micrograms/ml, we decided on placebo-controlled administration of the drug. The Cyt was well tolerated, and urine values of N-methylhistamine showed no important variations throughout this period compared to those during the placebo administration. Skin tests carried out 14 days after the study were positive at the concentration of 4 micrograms/ml. The history of different episodes of allergic reactions to Cyt, the last one being the most severe, indicated the possible participation of an immediate hypersensitivity phenomenon, but because no studies had been carried out initially, we could not establish the presence of IgE antibodies. These results indicate that good tolerance existed after the control administration procedure. The long interval, 3 years, between the allergic episode and our protocol and the appearance of a positive skin test 14 days after the protocol indicated that the subject had lost sensitivity and become resensitized after the controlled administration procedure.

Anaphylaxis↗
PubMed1997

[Subspecific classification of 11 clinical strains of Klebsiella pneumoniae based on their biochemical, antibiotic and plasmid profiles].

The paper summarizes at a subspecific level 11 clinical strains of K. pneumoniae. The objective of the work was to determine in a simple and effective way differences between different strains of the mentioned taxon. Biochemical characteristics, antibiogram and part of the plasmid spectrum were used for assessment of inter-species differences between different strains and at the same time their use as simple markers of epidemiological analyses is presented.

Bacterial Typing Techniques↗
PubMed1997

Allergic reactions to ampicillin. Studies on the specificity and selectivity in subjects with immediate reactions.

BACKGROUND: Ampicillin (AMP) is a drug that has been prescribed extensively. Reactions that have been reported include exanthema, desquamative contact eczema, urticaria and anaphylaxis. Experimental evidence indicates that the side chain of AMP is a structure that may induce a selective immune response either at the humoral or lymphocyte T-cell level. With regard to IgE reactions, the selectivity and specificity of the response needs to be studied in humans. OBJECTIVES: To study the specificity of the IgE response in a group of subjects who had an immediate allergic reaction after the administration of AMP. METHODS: Subjects developing an immediate response (anaphylaxis or urticaria) after the administration of AMP or an aminopenicillin derivative with the same side chain as AMP were studied. Skin tests were made to determinants generated from benzyl penicillin (BP): benzyl penicilloyl (BPO) and minor determinant mixture (MDM), as well as amoxicillin (AX) and AMP. Specific IgE antibodies were determined to benzyl penicilloyl polylisine (BPO-PLL), amoxicilloyl-polylisine (AX-PLL) and ampicilloyl-polylisine (AMP-PLL). The specificity of the IgE antibody response was studied by RAST and RAST inhibition. Subjects were classified in three categories: group A: those who were skin test and/or RAST positive to determinants derived from benzylpenicillin, group B: those who were negative to determinants derived from benzylpenicillin but were skin test and/or RAST positive to determinants derived from AX and AMP and group C: those who were exclusively positive to determinants derived from AMP. RESULTS: A total of 48 subjects was included in the study. In group A there were 35 cases, in group B 10 cases, and in group C three cases. RAST inhibition studies showed that in some instances the side chain of AMP could induce specific responses with a variable degree of crossreactivity between BP and AX. CONCLUSIONS: Although AMP can induce an immediate IgE response in subjects allergic to betalactams and the structure of the side chain may contribute to the specificity of the response, our results indicate that in most instances crossreactivity with the other penicillins exists and that in the groups studied selective reactions to just AMP derived determinants were uncommon.

Adult↗
PubMed1996

Selective allergic reaction to oral cloxacillin.

BACKGROUND: Previous observations indicate that in some instances subjects allergic to penicillins may experience an allergic reaction after taking the drug by one route but have good tolerance after being administered the same drug by a different route. OBJECTIVE: The purpose was to establish if cloxacillin (CLX) induced a selective response only after oral route administration in a suspected case and to study if there were differences between the oral and parenteral formulations. METHODS: Skin tests were carried out using benzylpenicillin (BP) conjugated to poly-L-lysine (BPO-PLL), minor determinant mixture of benzylpenicillin (MDM), ampicillin (AMP), amoxicillin (AX) and cloxacillin (CLX). Radioallergosorbent assay (RAST) was carried out using BPO-PLL, AX-PLL and CLX-PLL sensitized discs. In the case the skin tests and RAST were negative, a controlled challenge administering the drug by both oral and parenteral route was made. Urine samples were taken at prechallenge (basal levels) and at three periods after challenge (1-3, 3-6 and 6-9 h). Analysis of oral and parenteral formulations was made by HPLC chromatography. RESULTS: All skin tests and RASTs were negative. With the challenge tests the patient tolerated parenteral BP and oral phenoxymethyl penicillin (PV) and oral and parenteral AMP up to therapeutic concentrations. Parenteral CLX (500 mg) was also tolerated but 30 min after administering 50 mg by the oral route progressive generalized erythema with pruritus, facial angioedema and tachycardia developed. Urine samples taken during the challenge tests showed an increased excretion of N-methyl histamine (N-MH) 3 h after challenge with oral CLX but no change in N-MH levels after challenge with parenteral CLX or the other penicillins, indicating that histamine was released during the allergic episode with oral CLX. HPLC analysis of the oral and parenteral CLX formulations indicated that there were no differences and that neither polymers no other contaminant materials were present. CONCLUSION: Although the nature of the allergenic determinant involved in the induction of the reaction is not yet known, the oral route may have favoured the production of a metabolite not generated by the parenteral route.

Administration, Oral↗
PubMed1996

Loss of an HLA haplotype in pancreas cancer tissue and its corresponding tumor derived cell line.

A combination of immunohistochemical, biochemical, and recombinant DNA techniques were used to investigate class I expression in 26 pancreatic adenocarcinomas and 6 autologous tumor-derived cells. The prevalence of HLA losses was found to be comparable to that observed in other tumor types (> 35%), using monomorphic and locus-specific antibodies. In one patient, the original tumor tissue, a tumor derived cell line (IMIM-PC-2), and EBV-transformed lymphocytes were available for study. The patient's phenotype was A25, A30, B18, B18. However, A30 allele product could not be detected in the original tumor not in the cultured tumor cells. In addition, A30 allele could not be isolated from cDNA or genomic clones from the cultured tumor cells whereas it was isolated from the autologous lymphoblastoid cell line. Using isoelectric focusing analysis a significant reduction in the B18 heavy chain product was also observed in the tumor cell line, IMIM-PC-2, suggesting the absence of expression of one allele. Further studies revealed loss of heterozygosity at DR and other loci of chromosome 6 and cytogenetic data strongly suggested deletion of a full chromosome 6. This work indicates for the first time that loss of a full HLA haplotype occurs in tumor tissue and suggests that this mechanism may contribute to the progression of human cancer.

Adenocarcinoma↗
PubMed1995

Comparative study between European and American species of Polistes using sera from European sensitized subjects.

Although the different vespid species of the genus Polistes are found all over the world, studies about allergy sensitization to these species have been made mainly in North America. We studied the specific IgE in a large group of sera from patients sensitized to Polistes dominulus (PD) and determined the crossreactivity with another important European Polistes (P. gallicus [PG]) and with five American relevant species of this genus: P. exclamans (PE), P. fuscatus (PF), P. metricus (PM), P. annularis (PAN) and P. apachus (PAP). Studies indicated that 96.7% of sera with IgE positive to PD were positive to PG. No case positive to just PG was found. The comparison of these two European species with the American relatives indicated that most cases were positive to all the insects although there were significant differences in the radioallergosorbent test (RAST) value. These results were confirmed by RAST inhibition studies, and indicate that although the European and American species are closely related, species specific allergenic differences exist. These data suggest that in vivo studies should be carried out in order to determine the sensitivity and specificity of the European venoms compared with the American species.

Animals↗
PubMed1995

Nonimmediate reactions to betalactams: prevalence and role of the different penicillins.

In patients treated with penicillins, adverse cutaneous reactions can occur within minutes or may take several days to develop. IgE antibody-mediated reactions are well documented, but other mechanisms may also be involved. In particular, nonimmediate reactions have not been studied extensively, and the purpose of the present work was to establish the incidence of such reactions among a large group of patients and to study the penicillins involved. A total of 380 subjects with a history of a cutaneous reaction following administration of a penicillin antibiotic was included in the study. Skin tests and specific IgE measurements (RAST) were carried out using various penicillins and penicillin-related reagents, and patients were also challenged with various penicillins. In some patients with delayed skin test responses, skin biopsies were carried out. The tests confirmed that 74 subjects (19.4% of total investigated) had suffered a cutaneous reaction to a penicillin derivative, and 29 of these subjects (7.6% of total or 39% of confirmed) showed evidence of having suffered a nonimmediate reaction. The latter group were identified by giving a positive delayed direct challenge, and in 65% of the cases a delayed skin test response was detected. In most cases, these responses were to amino penicillins. Skin biopsies showed a lymphomonocytic cell infiltrate. Nonimmediate reactions to penicillins are a reproducible phenomenon, suggesting that a specific mechanism is responsible. By direct challenge, 93% of responders were positive to amino penicillins (10.3% ampicillin, 82.7% amoxicillin), indicating a major role for these penicillins in nonimmediate reactions.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Comparison of Vespula germanica venoms obtained from different sources.

This study was carried out to compare the allergenic potency of Vespula germanica (VG) venoms extracted by different methods and commercially available venoms from Vespula species currently used for in vivo and in vitro studies including immunotherapy. Pure VG venom was used as the reference material. Protein content and enzymatic and allergenic properties of all venoms studied were determined by dye stain reagent, hyaluronidase and phospholipase A1B enzyme activities, and radioallergosorbent test inhibition studies, respectively. Radioallergosorbent test discs sensitized with commercial and pure VG venom were compared using specific IgE antibodies from subjects allergic to VG venom. The data obtained indicate that there were important differences in the allergenic potency between the Vespula species venoms employed for in vivo and/or in vitro assays, VG venom obtained by sac dissection, and pure VG venom. These results indicate that venoms from Vespula species used for in vitro and in vivo tests have a lower concentration of allergens and contain nonvenom proteins. These data should be taken into account when these vespid venoms are used for diagnostic purposes and also when evaluating immunotherapy studies.

Allergens↗