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Biomedical subjects

C Moreno

Publications and source records attributed to C Moreno.

At least 127 records · Page 7Linked to original sources
PubMed1994

Promiscuous T cell recognition of an H-2 IA-presented mycobacterial epitope.

Genetically permissive T cell epitopes are an important prerequisite for the development of peptide-based vaccines or immunodiagnostic reagents. We have investigated the structural requirements of permissive T cell recognition of peptide p350-369 from the 38-kDa antigen of Mycobacterium tuberculosis. This peptide was found to be immunogenic in mice of the H-2b, bm12, d, s and k, but not of the H-2f genotype. T cell responses were restricted by I-A class II molecules. The same epitope core was recognized in the H-2b, d and k genotypes. T cell hybrids from BALB/c and C57BL/10 mice were used to determine: (i) the critical residues using substituted peptide derivatives and (ii) the degree of T cell promiscuity. Two out of five BALB/c (H-2d)-derived hybridomas tested displayed promiscuous peptide recognition in the context of H-2b and H-2bm12 antigen-presenting cells. The recognition of critical residues was found to be uniform for all five hybridomas when tested with syngeneic antigen-presenting cells; additional critical residues were identified when the peptide was recognized in the context of allogeneic antigen-presenting cells. Only one of the four tested C57BL/10 (H-2b) hybridomas showed promiscuity in the context of H-2bm12. Each of these C57BL/10-derived clones had a distinct response profile toward the critical residues. We propose that the demonstrated T cell promiscuity involves peptide interaction with polymorphic H-2 I-A residues.

Amino Acid Sequence↗
PubMed1994

Parental influences to smoke in Latino youth.

BACKGROUND: Latino youth have been found to have a higher prevalence of tobacco use than do other ethnic groups, possibly due to cultural factors and parental influences. METHODS: Seventh-grade students (N = 589) were surveyed in San Diego, California, and Tijuana, Mexico, to assess parental influences to smoke. These parental influence variables were studied with logistic regression, adjusting for age, sex, and number of parents who smoke. RESULTS: Among those whose parents smoke, Mexican students were asked to strike a match to light their parents' cigarettes significantly more often (57%) than Mexican-American students (37%) and U.S. Others (37%) (P < 0.05). Seventeen percent of the Mexican students reported having lit a cigarette in their own mouth for their parents, compared to 18% of Mexican-Americans and only 3% of U.S. Others (P < 0.01). Mexicans reported buying cigarettes for their parents more often (62%), compared with 36% for Mexican-Americans and 30% for U.S. Others (P < 0.01). Child smoking was only associated with friend offers of tobacco and parental prompts to light cigarettes in their mouths. CONCLUSION: Latino parents are inadvertently prompting their children to smoke. Smoking prevention programs targeting Latino youth may need to include a parental tobacco education component.

Adolescent↗
PubMed1994

A temporal-spatial cluster of sudden infant death syndrome in Navarre, Spain.

An apparent temporal-spatial cluster of Sudden Infant Death Syndrome (SIDS) was noted in the Autonomous Community of Navarre, Spain, when four unrelated children aged between 1 and 6 months died unexpectedly within a 7-day interval in January, 1990. The population under one year of age in Navarre was approximately 4,800. The scan test of temporal clustering showed that the sudden infant deaths occurred closer to one another in time significantly more often than would be expected by chance. All four infants lived in a neighbourhood of the capital of Navarre, which accounts for approximately half the region's population. The clustered cases coincided with an outbreak of influenza type A detected by the epidemiological surveillance system and seen by the increase in 1990 over the same period in the previous year in the number of paediatric emergency-ward admissions during the 'epidemic' days. The results confirm the presence of a temporal-spatial cluster of SIDS and favour an environmental etiology where exposure to influenza A viruses is implicated.

Disease Outbreaks↗
PubMed1994

Nested polymerase chain reaction for detection of Legionella pneumophila in water.

A highly sensitive nested polymerase chain reaction (PCR) method was evaluated for detection of Legionella pneumophila in water. Two sets of primers homologous to the coding region of the L. pneumophila macrophage infectivity potentiator (mip) gene were used. Even when starting from minute amounts of L. pneumophila DNA, the double PCR products were readily detected by direct visualization in ethidium-bromide-stained agarose gels. The method was tested on 34 potable water samples from a hospital building and compared with standard culture isolation. L. pneumophila was isolated in only twelve samples, whereas, by nested PCR, 19 samples were positive, 12 of them coincidental with culturing. These results indicate that nested PCR permits detection of L. pneumophila in samples where culturing fails, with the advantage of a rapid turnaround time, simplicity and the ability to detect non-culturable cells, fulfilling the requirements of sensitivity and specificity for routine use in an environmental laboratory.

Blotting, Southern↗
PubMed1994

[Fiberoptic bronchoscope disinfection with glutaraldehyde phenolate in 1:8 solution].

We evaluated the efficacy of phenolated glutaraldehyde in a 1:8 solution for the disinfection of bronchofibroscopes that were highly contaminated with Serratia marcescens and Pseudomonas aeruginosa. An Olympus BF-P10 bronchofibroscope was contaminated with artificial samples containing one of the aforementioned microorganisms in concentrations nearing 10(8) colony forming units per milliliter (cfu/ml). The instruments were then washed with soap and water and submerged in a 1:8 solution of phenolated glutaraldehyde. Samples were taken for culturing after contamination, after washing, and after 10, 15 and 30 min in the disinfectant solution. The level of cfu/ml in the cultures was measured and the definition of failure-to-disinfect was a finding of > or = 1 cfu/ml after each experimental procedure. Twenty procedures, 10 for each microorganism, were carried out. Washing of the bronchofibroscope afforded significant elimination of microorganisms and no colony growth was observed in cultures after 10 min submersion in phenolated glutaraldehyde. We conclude that immersion in a 1:8 solution of phenolated glutaraldehyde after careful washing is a valid way to disinfect bronchofibroscopes that are highly contaminated with S. marcescens and P. aeruginosa.

Bronchoscopes↗
PubMed1994

Insertion sequence IS1137, a new IS3 family element from Mycobacterium smegmatis.

A new insertion sequence (IS) has been isolated from Mycobacterium smegmatis. It is 1361 bp long and possesses characteristics of the IS3 family elements. It harbours 32 bp imperfect inverted repeats at its extremities and a 3 bp direct repeat flanks the element, possibly as the result of a transposition event. This IS, IS1137, contains three major ORFs. Two of them, ORF A and ORF B show homologies both at the amino acid sequence level and at the organization level with the ORFs encoding the transposase of the IS3 family elements. IS1137 has a narrow host range and was found only in M. smegmatis and M. chitae. The fact that IS1137 is not present in the M. tuberculosis complex strains makes this element a new candidate for transposon mutagenesis in mycobacteria.

Amino Acid Sequence↗
PubMed1994

The modulation of tumour necrosis factor-alpha, interleukin-1 alpha and glucose levels with GMDP and other analogues of muramyl dipeptide.

Immunomodulatory agent muramyl dipeptide (MDP) and seven of its analogues were tested for ability to counteract the toxic actions of lipopolysaccharide (LPS) in experimental mouse models. Female BALB/c mice were presensitized with Corynebacterium parvum (P. acnes) and given MDP or equimolar doses of one of its analogues after 2 weeks, followed by intravenous challenge with LPS 18 h later. This treatment produced a sharp increase in blood cytokine (TNF-alpha, IL-1 alpha) levels 4 h after LPS administration followed by a decline to control values after 6 h. Four analogues, GMDP, threonylMDP, GMDPBenz and GMDPOBut, were able to reduce the level of cytokines induced with LPS. For most of the analogues, the higher doses reduced the levels of TNF-alpha but slightly increased the concomitant IL-1 alpha levels. GMDP was the most effective compound tested in terms of reduction of TNF-alpha and IL-1 alpha levels, as well as for reduction of the hypoglycaemia caused by the administration of LPS.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1994

Epitope specificity and isoforms of the mycobacterial 19-kilodalton antigen.

The topography and specificity of B- and T-cell stimulatory epitopes from the 19-kDa protein of Mycobacterium tuberculosis were investigated by using overlapping synthetic peptides. Murine antisera identified two cryptic epitopes (residues 11 to 30 and 61 to 80) and one species-specific immunodominant epitope (residues 140 to 159). Immunoglobulins G1 and G2a antibody isotypes varied for the respective peptide immunogens but without relationship to the T-cell cytokine profiles which were characterized by high gamma interferon and low interleukin 5 levels. Antisera to recombinant M. tuberculosis 19-kDa protein (rGST-19) cross-reacted with homologous proteins of similar size from organisms of the Mycobacterium avium-intracellulare complex. Two-dimensional gel electrophoresis revealed differences in the number, relative mobility, and charge of isoforms of the 19-kDa protein, possibly reflecting posttranslational modifications. The immunodominant T-cell epitope from the M. tuberculosis 19-kDa protein (residues 61 to 80) and the corresponding peptide sequence from Mycobacterium avium subsp. intracellulare (residues 64 to 83), differing at five residues, were both recognized in a genetically permissive manner. Peptides 61-80 and 64-83 stimulated cross-reactive responses in BALB/c (H-2d) mice, while in the C57BL/10 (H-2b) strain, responses to peptide 61-80 were species specific. In purified protein derivative-positive healthy individuals, the M. avium subsp. intracellulare peptide stimulated stronger responses than did the M. tuberculosis peptide, whereas patients with active tuberculosis had enhanced in vitro T-cell responses to both peptides.

Amino Acid Sequence↗
PubMed1994

Sensitization to sunflower pollen: only an occupational allergy?

Sunflower (Helianthus annuus) pollen sensitization has been reported as an occupational allergy. In this report, the sensitization of the general population living in sunflower-growing areas to Helianthus pollen was studied. Both RAST results in 32 adults with summer symptoms previously diagnosed as allergic to Artemisia pollen, and cross-reactivity studies between H. annuus and other Compositae suggested that H. annuus pollen was the main allergen involved in the hypersensitivity reaction of those patients. Good correlation was found between RAST and SPT to Helianthus and between RAST and conjunctival provocation test to Helianthus. Bronchial challenge tests performed on 8 of the 32 patients confirmed the clinical implication of Helianthus pollen in suspected subjects. Five workers, handling sunflower pollen, who suffered from related symptoms were subjected to the same study, showing lesser wheal areas and lesser specific IgE levels than a non-worker group. Thirteen patients with RAST values > or = class 2 showed 2 IgE-binding fractions at 34.0 and 42.8 kD in 65% of sera and 3 IgE-binding fractions at pI 4.9, 9.6 and 10.2 in 54% of sera. By means of micropreparative high-resolution chromatography, it was possible to purify a 34-kD major allergen. Analysis performed by RAST inhibition with sera from atopic patients and ELISA inhibition with experimental anti-Helianthus rabbit sera demonstrated a cross-reactivity between Helianthus and other Compositae, but low affinity of specific anti-Helianthus antibodies for heterologous antigens. Taking into account the above-mentioned data, and the high prevalence of Helianthus pollen in the atmosphere during harvesting (in spite of its entomophilous character), Helianthus pollen should be considered as an allergenic source to be investigated in the general population living in sunflower-growing regions suffering from seasonal summer allergy.

Agricultural Workers' Diseases↗
PubMed1994

Parental prompting of smoking among adolescents in Tijuana, Mexico.

Latino adolescents in the United States and Mexico may have higher rates of tobacco experimentation than other ethnic groups, possibly due to cultural factors and parental influences. This study examined three parental behaviors that may prompt smoking in children in Grades 3, 5, 7, and 9 in Tijuana. Mexico. Surveys were administered to 758 students in randomly selected classes in randomly selected schools in Tijuana. The most frequent prompt was the smoking parent asking the child to buy cigarettes (about two thirds), whereas about 60% asked the child to light the parent's cigarette, and about 20% of smoking parents asked the child to place the cigarette in his or her mouth to light it. Rates of prompting were very low among third graders but increased by Grade 5. Mother's smoking was associated with higher rates of all three types of parental prompting.

Journal Article↗
PubMed1994

[Utility of the direct culture examination (Ziehl-Neelsen) using the Bactec system for the presumptive identification of Mycobacterium tuberculosis complex, Mycobacterium avium complex, Mycobacterium xenopi, and Mycobacterium kansasii].

BACKGROUND: The usefulness of the microscopic examination of Bactec 12B and 13A growth medium as a method for the possible identification of M. tuberculosis complex, M. avium complex, M. xenopi, and M. kansasii was performed out to guide the selection of different genetic identification probes and, in the case of M. xenopi, the selection of the temperature of subcultures incubation. METHODS: Upon detection of an index of growth greater than 100 in Bactec tubes, staining was performed by the Ziehl-Neelsen technique. On the basis of the morphology observed, the possible identification was performed by genetic probes. Subcultures were used for definitive identification. RESULTS: Three hundred forty-four positive samples were studied by radiometric technique. A total of 190 strains were identified as M. tuberculosis, 88 strains as M. avium-intracellulare (MAI), 33 strains as M. xenopi, 14 strains as M. kansasii and 19 strains were identified as: M. gordonae (10), unpigmented rapid growth microbacteria (7), and M. simiae (2). Sensitivity, specificity, positive predictive value, and negative predictive value were 97.9%, 95.4%, 96.4%, and 97.3%, respectively for M. tuberculosis complex, 84.0%, 99.2%, 97.3% 94.7% for M. avium complex; 63.6%, 98.3%, 80.7%, 96.2% for M. xenopi; 35.7%, 98.1%, 45.5% 97.2% for M. kansasii. CONCLUSIONS: The morphology of M. tuberculosis complex examined in the radiometric system in useful to differentiate this species from other microbacteria (MOTT), allowing the selection of specific probe used. Within the MOTT, M. avium complex also has morphological characteristics which are useful for its differentiation, the morphology usually described for the remaining species was frequently not observed.

Bacteriological Techniques↗
PubMed1994

Th1/Th2 profiles in tuberculosis, based on the proliferation and cytokine response of blood lymphocytes to mycobacterial antigens.

Proliferation and cytokine production profiles by blood mononuclear cells in response to in vitro stimulation with mycobacterial antigens were compared in patients with active tuberculosis and in sensitized healthy controls. Interleukin-4 (IL-4) and interferon-gamma (IFN-gamma) were detected at single-cell level using the ELISPOT assay. Patients showed significantly (P < 0.01) increased numbers of IL-4-secreting cells and decreased thymidine incorporation, but no significant difference in IFN-gamma-producing cells in response to the 38,000 MW or 19,000 MW antigens and their immunodominant peptide epitopes. Pronounced individual variations were found in both patient and control groups, when comparing the responsiveness to the mycobacterial extract, two protein antigens and five synthetic peptides. None of the antigens or peptides tested showed preferential stimulation of either IL-4- or IFN-gamma-secreting T cells, and proliferation was not correlated with either IL-4 or IFN-gamma production. In particular, cytokine responsiveness was of similar frequency in subjects who did or did not show positive proliferation, indicating that the latter test was not fully representative of the active T-cell repertoire. It is concluded that the demonstrated Th2 type of profile in response to two prominent mycobacterial antigens may play a role in the mechanisms of defective host resistance in tuberculosis.

Adolescent↗
PubMed1993

Voltammetric studies of the catalytic electron-transfer process between the Desulfovibrio gigas hydrogenase and small proteins isolated from the same genus.

The kinetics of electron transfer between the Desulfovibrio gigas hydrogenase and several electron-transfer proteins from Desulfovibrio species were investigated by cyclic voltammetry, square-wave voltammetry and chronoamperometry. The cytochrome c3 from Desulfovibrio vulgaris (Hildenborough), Desulfovibrio desulfuricans (Norway 4), Desulfovibrio desulfuricans (American Type Culture Collection 27774) and D. gigas (NCIB 9332) were used as redox carriers. They differ in their redox potentials and isoelectric point. Depending on the pH, all the reduced forms of these cytochromes were effective in electron exchange with hydrogenase. Other small electron-transfer proteins such as ferredoxin I, ferredoxin II and rubredoxin from D. gigas were tentatively used as redox carriers. Only ferredoxin II was effective in mediating electron exchange between hydrogenase and the working electrode. The second-order rate constants k for the reaction between reduced proteins and hydrogenase were calculated based on the theory of the simplest electrocatalytic mechanism [Moreno, C., Costa, C., Moura, I., Le Gall, J., Liu, M. Y., Payne, W. J., van Dijk, C. & Moura, J. J. G. (1993) Eur. J. Biochem. 212, 79-86] and the results obtained by cyclic voltammetry were compared with those obtained by chronoamperometry. Values for k of 10(5)-10(6) M-1 s-1 (cytochrome c3 as electron carrier) and 10(4) M-1 s-1 (ferredoxin II as the electron carrier) were determined. The rate-constant values are discussed in terms of the existence of an electrostatic interaction between the electrode surface and the redox carrier and between the redox carrier and a positively charged part of the enzyme.

Catalysis↗
PubMed1993

Genetically permissive recognition of adjacent epitopes from the 19-kDa antigen of Mycobacterium tuberculosis by human and murine T cells.

The specificity of the T cell-immune repertoire at the level of individual antigenic determinants could play a fundamental role in the immunopathogenesis of tuberculous infections. Therefore, we analyzed the immunogenicity, genetic restriction, and epitope core structure of two adjacent, yet distinct, immunodominant T cell determinants from the 19-kDa Ag of Mycobacterium tuberculosis. After immunization with two peptides comprising residues 45 to 64 and 61 to 80, vigorous in vitro proliferative responses to the homologous peptide were elicited in five different strains of C57BL/10 mice (H-2b,k,d,s,f), indicating that both epitopes were recognized in a genetically permissive manner. When immunized with intact 19-kDa protein, lymph node cells from the same mouse strains responded to both peptides, with the exception of H-2b mice, which did not respond to p45-64. Delayed-type hypersensitivity responses in C57BL/10 (H-2b) mice were elicited by p61-80 only, whereas in H-2d mice both peptides were delayed-type hypersensitivity negative, despite eliciting pronounced proliferative responses. Analysis of the proliferative responses of human PBMC in purified protein derivative-positive healthy subjects and tuberculosis patients revealed significant differences in the antigenicity to the two peptides. All purified protein derivative-positive healthy and diseased individuals manifested strong responses to p45-64, indicating HLA permissive recognition. In contrast, pronounced responses to p61-80 were detected only in patients with lymphatic tuberculosis. Epitope core structures, composed of 6 or 7 residues within each peptide, have been mapped with peptides of overlapping sequence. Significantly, for both epitopes, the core sequences recognized by both human and murine T cells were almost identical. We conclude that despite many similarities between murine and human T cell epitope recognition, distinct differences in the responsiveness of the infected host could play a role in pathogenesis. Furthermore, the genetically permissive nature of the identified epitopes is a potentially important attribute for the development of peptide-based diagnostic reagents and vaccines.

Adult↗
PubMed1993

Molecular chaperones and the immune response.

Molecular chaperones belonging to heat shock protein families have been identified as prominent antigens in the immune response to a wide variety of infections. Recognition of such highly conserved antigens may contribute to protective immunity but, in some circumstances, may also have pathological autoimmune consequences. Recognition of chaperones may be an inherent feature of the immune system. Peptide mapping experiments revealed an overlap between hsp 70-binding sites and immunodominant regions of three protein antigens, consistent with a possible functional activity for molecular chaperones in the processing and presentation of peptides during class II-restricted T lymphocyte responses. A functional role for molecular chaperones in antigen processing may be a factor which contributes to their immunogenicity.

Animals↗
PubMed1993

Electrochemical studies of the hexaheme nitrite reductase from Desulfovibrio desulfuricans ATCC 27774.

The electron-transfer kinetics between three different mediators and the hexahemic enzyme nitrite reductase isolated from Desulfovibrio desulfuricans (ATCC 27774) were investigated by cyclic voltammetry and by chronoamperometry. The mediators, methyl viologen, Desulfovibrio vulgaris (Hildenborough) cytochrome c3 and D. desulfuricans (ATCC 27774) cytochrome c3 differ in structure, redox potential and charge. The reduced form of each mediator exchanged electrons with nitrite reductase. Second-order rate constants, k, were calculated on the basis of the theory for a simple catalytic mechanism and the results, obtained by cyclic voltammetry, were compared with those obtained by chronoamperometry. Values for k are in the range 10(6)-10(8) M-1 s-1 and increase in the direction D. desulfuricans cytochrome c3-->D. vulgaris cytochrome c3-->methyl viologen. An explanation is advanced on the basis of electrostatic interactions and relative orientation between the partners involved. Chronoamperometry (computer controlled) offers advantages over cyclic voltammetry in the determination of homogeneous rate constants (faster, more accurate and better reproducibility). Direct, unmediated electrochemical responses of the hexaheme nitrite reductase were also reported.

Cytochrome c Group↗