Tritium forms discrimination in ryegrass under constant tritium exposure: From seed germination to seedling autotrophy

Uncertainties remain regarding the fate of atmospheric tritium after it has been assimilated in grasslands (ryegrass) in the form of TFWT (Tissue Free Water Tritium) or OBT (Organically Bound Tritium). One such uncertainty relates to the tritium forms discrimination during transfer from TFWT to OBT resulting from photosynthesis (OBT_photo), corresponding to the OBT_photo/TFWT ratio. In this study, the OBT/TFWT ratio is determined by experiments in the laboratory using a ryegrass model and hydroponic cultures, with constant activity of tritium in the form of tritiated water (denoted as HTO) in the "water" compartment (liquid HTO) and "air" compartment (HTO vapour in the air). The OBT_photo/TFWT ratio and the exchangeable OBT fraction are measured for three parts of the plant: the leaf, seed and root. Plant growth is modelled using dehydrated biomass measurements taken over time in the laboratory and integrating physiological functions of the plant during the first ten days after germination. The results suggest that there is no measurable discrimination of tritium in the plant organic matter produced by photosynthesis.

Frequency of Mycobacterium bovis as an etiologic agent in extrapulmonary tuberculosis in HIV-positive and -negative Mexican patients

Mycobacterium bovis can be an important etiological agent for extrapulmonary (EP) manifestations of tuberculosis, especially in HIV-infected persons. From January 2000 to December 2003, M. bovis as a cause of EP tuberculosis was investigated at the Pneumonology Service, Hospital General de Mexico, Mexico City. Eighty HIV-positive (HIV+) patients and 83 HIV-negative (HIV-) with EP involvement (ganglionar, genitourinary, meningeal, cutaneous, peritoneal, and pericardial) were analyzed using clinical, immunological, bacteriological, histopathological, and molecular biology methods. Mycobacterium species were identified by hsp65-RFLP analysis and species of M. tuberculosis complex isolates by spoligotyping. M. bovis was present in 6 HIV- cases (7.2%; 3 with lymphadenitis and 3 genitourinary) vs 11 in HIV+ cases (13.75%; 7 with lymphadenitis, 3 genitourinary, and 1 meningeal). Favorable response to retroviral and specific M. bovis chemotherapy was observed. Spoligotyping showed a unique profile in each isolate, 16 belonging to BOV1 lineage and 1 to BOV2 lineage. M. bovis is an significant re-emerging cause of EPTB in Mexico. Consumption of unpasteurized dairy products is the most likely source of transmission. Successful treatment depends on the adequate and opportune identification of the agent responsible.

Analysis of antibody response in human dengue patients from the Mexican coast using recombinant antigens

This study was undertaken to evaluate the feasibility of using recombinant dengue proteins to discriminate between acute dengue infections versus uninfected dengue samples. Dengue virus proteins E, NS1, NS3, and NS4B were cloned as fusion proteins and expressed in Escherichia coli. Recombinant products were tested in 100 serum samples obtained from acute dengue fever cases collected from 3 states of Mexico where dengue is endemic. Sera from 75 healthy individuals living in nonendemic areas for dengue were used as a control group. In sera from the dengue patients group, antibody responses to E protein were demonstrated in 91% of cases and NS1 protein was recognized to various extents (99%) within the first 7 days of infection. The antibody responses to NS3 and NS4B were frequently of low magnitude. Consistent negative antibody responses to all proteins were found in sera from the control group. These data suggest that the glutathione-S-transferase (GST)-dengue fusion proteins may be feasible antigens for a sensitive and specific serological assay.

Peripheral blood CD161+ T cells from asthmatic patients are activated during asthma attack and predominantly produce IFN-gamma

In humans, T cells expressing the CD161 molecule NKR-P1A constitute around 20% of the circulating CD3(+) cells and are potentially immunoregulatory in several diseases. Their role in asthma is not well known, but they could participate in asthma attacks. To determinate whether activation of CD161(+) T cells and their cytokine production correlate with clinical status of asthma, we analysed blood samples from asthma attack patients (AAP) and stable asthma patients (SAP) in comparison with healthy non-atopic controls (HC). There was a significant higher baseline expression of CD69 on T cells from AAP and the difference was more notorious on CD161(+) T cells; upregulation of CD69 was observed on both CD161(-) and CD161(+) T cells driven by Dermatophagoides pteronyssinus crude extract, whereas polyclonal stimulation with phorbol 12-myristate 13-acetate plus ionomycin predominantly induced IFN-gamma but no IL-4, IL-5 and IL-13 by CD161(+) T cells in all groups; upon polyclonal stimulation, there were more CD161(+) T cells producing IFN-gamma and less CD161(-) T cells producing this cytokine, contrasting with the opposite results observed in SAP and HC groups. Our results indicate that, during asthma attack, CD161(+) T cells are activated and are able to produce predominantly IFN-gamma but no Th2 cytokines. We hypothesize that during an asthma attack, IFN-gamma produced by CD161(+) T cells could help to reestablish the Th1/Th2 equilibrium. These observations may contribute to the understanding of the immune mechanisms involved in asthma attacks.

Tuberculosis is still a major cause of cervical lymphadenopathies in adults from developing countries

To establish the frequency of infectious aetiology in Mexican adult patients with cervical lymphadenopathies (CLAs), 87 consecutive patients with enlarged cervical lymphatic nodes, HIV negative and without anti-tuberculous treatment, were selected from a tertiary-level speciality concentration hospital. Histopathological studies, investigation of acid-fast bacilli, cultures in Löwenstein Jensen and Mycobacterium growth indicator tube (MGIT) media, and in-house polymerase chain reaction (PCR) with IS6110-based primers for Mycobacterium tuberculosis complex were performed in resected lymphatic nodes. Non-infectious aetiology corresponded to 45 cases (52 %). Tuberculosis was suspected in 42 cases (48%) by histology and confirmed positive results were obtained by staining in 8 (19%), by culture in 23 (55%), and by PCR in 34 (81 %) patients. All were confirmed after therapeutic success. In addition to the epidemiological transition process occurring in Mexico, tuberculosis remains an important cause of CLA. Histopathology with confirmatory studies including PCR can detect tuberculous aetiology.

Underestimation of Mycobacterium tuberculosis infection in HIV-infected subjects using reactivity to tuberculin and anergy panel

BACKGROUND

This study aimed to evaluate purified protein derivative (PPD) reactivity and its interrelationship with anergy panel and CD4+ lymphocytes in HIV-infected subjects as compared to PPD reactivity in HIV-uninfected individuals in a tuberculosis endemic and high Bacillus Calmette-Guérin (BCG) coverage environment.

METHODS

Clients of four Mexico City HIV detection centres were screened for HIV-1 antibodies (ELISA or haemagglutination, Western Blot); reactivity to PPD (Mantoux PPD, 5TU RT-23), Candida (1:1000, 0.1 ml), and tetanus toxoid (10Lf, 0.1 ml); and CD4+ T cells. Active tuberculosis was excluded. Informed consent was obtained.

RESULTS

From 5130 clients 1168 subjects were enrolled; of these 801 (68.6%) were HIV positive. Reactivity to PPD among HIV-positive subjects was found in 174 (22%), 261 (32.6%), and 296 (37%), at PPD cutoff levels of > or =10 mm, > or =5 mm, and > or =2 mm as compared to 224 (61%) of 367 HIV-negative individuals' reactors to PPD (> or =10 mm) (P < 0.001). After exclusion of anergic individuals using two cutoff levels for cutaneous allergens (< or =2 mm and < or =5 mm), PPD reactivity between HIV-infected and uninfected individuals continued to be significantly different. Only HIV-infected individuals with CD4+ T cells > or =500 cells/mm3 had similar reactivity to PPD as HIV-uninfected individuals. Variables associated with PPD reactivity were CD4+ T cell counts, BCG scar, HIV infection and age.

CONCLUSIONS

PPD reactivity was useful to diagnose tuberculosis infection only among HIV-infected individuals with CD4+ counts > or =500 cells/mm3. Among individuals with lower counts, lowering cutoff levels or using anergy panel did not permit comparable reactivity as that observed among HIV-uninfected individuals.

Antibody response to Klebsiella pneumoniae 60 kDa protein in familial and sporadic ankylosing spondylitis: role of HLA-B27 and characterization as a GroEL-like protein

OBJECTIVE

To study the antibody response of HLA-B27+ patients with ankylosing spondylitis (AS) and their first degree relatives to the 60 kDa protein of Klebsiella pneumoniae and to characterize this protein.

METHODS

Sera from 84 individuals were analyzed by ELISA to determine the titer of antibodies against the 60 kDa protein of K. pneumoniae. Subjects were divided into 3 categories: Group 1: 44 HLA-B27+ AS related individuals (35 patients, 9 healthy controls); Group 2: 28 healthy B27- AS related individuals; and Group 3: 12 healthy B27- non-AS related subjects. The 60 kDa protein of K. pneumoniae was induced at 45 degrees C and purified by electroelution from sodium dodecyl sulfate-polyacrylamide gel electrophoresis. It was characterized as a GroEL-like heat shock protein (HSP). The recognition of GroEL-like protein was confirmed by immunoblot of 2 dimension electrophoresis. The response to GroEL-like protein from other bacteria and the response to lipopolysaccharide (LPS) was also analyzed by immunoblot.

RESULTS

HLA-B27+ individuals (Group 1), independent of their disease status, showed a significant higher response to the 60 kDa protein of K. pneumoniae than HLA-B27- subjects from Groups 2 and 3 (p < 0.0001). This protein was characterized as a HSP of the GroEL family and designated HSP60Kp. The GroEL of other enterobacteria as well as that of Mycobacterium leprae were recognized by HLA-B27+ individuals by immunoblot, whereas HLA-B27- individuals did not. LPS was not recognized by HLA-B27 positive or negative subjects.

CONCLUSION

These findings suggest a relationship between HLA-B27 and the response to a GroEL-like protein that could have implications in AS.

[Importance of molecular methodology in diagnosis]

The National Institute for Epidemiological Diagnosis and Reference (INDRE) partially supports epidemiological surveillance programs through the identification of most infectious agents prevalent in the country. The success of a program for the control or eradication of a particular infectious disease mainly depends on the opportune and accurate identification of the corresponding etiologic agent. For laboratory diagnosis at INDRE, both conventional methodology using direct or microscopic examinations of specimens or growth in culture media followed by physiological or immunological characterization of the isolate, as well as new techniques based in biochemical, immunochemical and molecular biology procedures are carried out. Antigens can be detected in clinical samples by ELISAs with polyclonal or monoclonal antibodies. Specific nucleic acids can be extracted, identified and typed with techniques like electrophoresis, hybridization with genomic probes, polymerase chain reaction or fragment restriction length polymorphism. Recombinant molecules or highly purified antigens are being obtained and used for the determination of antibodies, mainly with indirect ELISA, IgM capture-ELISA and Western Blot. The better performance, specificity and sensitivity of these laboratory procedures, provide faster results, with equal or greater accuracy than traditional ones, at lower cost.

Antibody response to nitrogenase-positive and -negative Klebsiella pneumoniae strains in juvenile-onset ankylosing spondylitis patients and their first degree relatives: lack of differential recognition of the bacterial nitrogenase

In the search for the pathogenic consequences of the molecular mimicry between the Klebsiella pneumoniae nitrogenase and the HLA-B27 antigen, sera from individuals belonging to 16 kindreds with juvenile-onset ankylosing spondylitis cases, were analyzed for antibodies against nitrogenase-positive and -negative K. pneumoniae whole bacterial extracts. An initial screening for nitrogenase producing K. pneumoniae strains was performed in 31 clinical isolates. The best nitrogenase producing strain was selected as well as a non producing one for immunoblot analysis using sera from 82 subjects, 55 HLA-B27 positive, of which 26 had some clinical manifestations. Even though electrophoretic patterns were different in both strains, there was no distinctive differential recognition of the 30-40 kDa proteins where the nitrogenase subcomponent which shares the sequence QTDRED with the HLA-B27 molecule is located. On the other hand, strong recognition of a protein of 60 kDa (p60Kp) was detected in 75% of HLA-B27 positive tested subjects independently of their clinical status. Studies on the nature of this protein and its participation in the pathogenesis of ankylosing spondylitis are now in progress.

Identification of phosphatidate nonlamellar phases on liposomes by flow cytometry

This study is the first report that demonstrates nonlamellar arrangements, or lipidic particles, of phosphatidate inserted in the lipid bilayer of liposomes using polyclonal antibodies from mice and flow cytometry. Sera immunoreactivity was analyzed using liposomes that displayed smooth bilayers of phosphatidate particles, as shown by electron microscopy. This cytofluorimetric analysis showed that immune mice sera have a specific immunoreactivity with the phosphatide particles formed by Mn2+, which also cross-reacted with those formed by Ca2+ and with cardiolipin particles formed by Mn2+. In addition, these immune sera hardly reacted with smooth bilayered liposomes, independently of the lipid composition studied. Thus, this new methodology can be applied to demonstrate nonlamellar molecular arrangements in biological membranes.

Cytokines and the immune response

The recent massive growth and development of clinical immunology has been enriched by the discovery of a new family of molecules, the cytokines, which consist of various groups of polypeptide mediators involved in the communication network of the cells of the immune system. This article provides an overview of the immune system and the current status of the cytokines and their clinical application.

Comparative assessment of the leprosy antibody absorption test, Mycobacterium leprae extract enzyme-linked immunosorbent assay, and gelatin particle agglutination test for serodiagnosis of lepromatous leprosy

A comparative assessment of three serological methods for leprosy diagnosis (the fluorescent leprosy antibody absorption [FLA-ABS] test, the Mycobacterium leprae soluble-extract enzyme-linked immunosorbent assay [ELISA], and the M. leprae particle agglutination [MLPA] test) was carried out. The objective was to identify their performance in clinical and epidemiological diagnosis of leprosy. The study group included 45 lepromatous leprosy patients under treatment. Specificity was > 95% for all three assays, and sensitivity was 95, 58, and 74% for the FLA-ABS test, the MLPA test, and the ELISA, respectively. The only cross-reactivity for M. tuberculosis-infected patients was with the soluble-extract ELISA. Although the FLA-ABS test displayed the highest specificity and sensitivity values, it can only be used in well-developed laboratories, and the patient's clinical and epidemiological background must be considered when results are interpreted because the test remains positive after therapeutic success and could be positive for some household contacts. The MLPA test is easier to perform and interpret, and it is adequate for small laboratories and epidemiological studies intended to detect active untreated or irregularly treated leprosy cases. Therefore, the FLA-ABS and MLPA tests are complementary, and both should be used for serodiagnosis of leprosy.

[Phagocytic capacity of peritoneal exudate cells from rats immunized with a ribosomal preparation of Ty2 Salmonella typhi]

It was compared the activity of exudate peritoneal cells (EPC) obtained from CFW mice immunized either with Salmonella typhi Ty2 ribosomal fraction or whole-cell heat inactivated vaccine, both in comparison with EPC from sham-immunized. In the group which received ribosomal preparation, a subcutaneous dose equivalent to 100 micrograms of RNA in incomplete Freund's adjuvant (IFA) was initially used and 14 days after a booster of the same dose in IFA was given. A single dose of whole-cell heat inactivated vaccine, with 10(6) bacteria in IFA was employed subcutaneously in animals of the second group. EPC from controls and immunized mice were withdrawn at periods of 7, 11, 14, 18, 22, 25, 29 and 31 days after immunization and each sample was incubated in vitro in presence of live virulent non-opsonized S. typhi Ty2 in 1:200 cell-bacteria relation. Twenty four hours after cultivation, EPC bacterial capacity was determined after cell disruption and enumeration of survival bacteria were made through viable counts. Results have shown that EPC from mice immunized were more efficient in eliminating intracellular bacteria than those which came from sham-immunized animals. Also, it was found that EPC from mice immunized with ribosomal preparation were more efficient (maximum P = 0.005) than EPC from the mice which received killed whole bacteria.

Demonstration of acid-fast bacilli in skin biopsies from indeterminate leprosy cases

Because the correct diagnosis of indeterminate leprosy (IL) requires the finding of acid-fast bacilli in skin lesions from clinically and histopathologically suggestive cases, it is necessary to develop a reliable method for this purpose. This paper presents a simple procedure, available to every general laboratory, which consists in obtaining 2 suspensions: SI, by mincing and grinding the tissue in phosphate-buffered saline; and SII, after treating SI with NaOH solution and digesting with trypsin. In 22 IL skin biopsies, bacilli were directly observed in only 3 with the Ziehl-Neelsen (ZN) stain; and with the peroxidase-antiperoxidase method it was impossible to differentiate between nonspecific precipitate and true positive reactions. In contrast, 18 positive results from the same 22 samples were obtained when both SI and SII were evaluated with ZN stain. The logarithmic bacterial index was also increased in at least 7 cases.

The HLA system in the prevalent Mexican Indian group: the Nahuas

Results of HLA-A, B and C typing as well as haplotype frequencies in the Nahuas, who are the predominant Indian group in Mexico are presented. ABO and Rh blood groups show the genetic homogeneity of this population, since all of them were group O and Rh+. The most frequent antigens and haplotype are in general, the same as in some, but not all Amerindian tribes (Papago, Pimas, Zuñi from North America and Ixils from Guatemala). When compared to other Mongoloids, the HLA pattern is very close to the Japanese population. Antigens Bw39 and Cw4 look like markers of Nahuas and because Bw16 cells from four individuals could not be assigned either as Bw38 or Bw39, and 6 subjects did not type for any of the Bw22 splits, new subtypes of these antigens are probable.

HLA-DR antigens in Mexican patients with Guillain-Barré syndrome

The distribution of HLA-DR antigens was investigated in 38 Mexican Mestizo patients with Guillain-Barré syndrome (GBS) and in 100 healthy controls belonging to the same population. IgG, IgM, IgA, CH50, C3, C4 and the number of T and B lymphocytes were also evaluated in the patients. Only DR3 was significantly increased in the patients (Yates' chi 2 = 9.943, Pc = 0.014) and the relative risk for developing the disease was 3.49. These findings support the hypothesis that DR3 or a closely linked Ir gene may play some role in the susceptibility to GBS.

HLA frequencies in a Mexican Mestizo population

The aim of the present study was to reevaluate the distribution of HLA antigens in Mexican Mestizos since, in our previous report, very few specificities were explored for this population. The Mestizos are primarly a mixture of Caucasians (Spaniards) and Mexican Indians and account at the present time for about 95% of the total Mexican population. A and B antigens were typed on isolated cells using a microlymphocytotoxicity technique. Antigen, gene and haplotype frequencies were calculated including the significance for delta values. The results clearly showed that the HLA distribution differs from other ethnic groups and the predominant antigens are A2, A9, B5, Bw35 and B40, but the general pattern clearly shows the participation in genetical composition of Spanish and Mexican Indian backgrounds. The most frequent haplotypes were A2-B5, A9-Bw35, A9-B40 and A2-B40, which are also the most common in some Mongoloid populations.

Immunological features of tuberculosis

Some aspects of cell-mediated immunity were explored in a population of 51 patients with active pulmonary tuberculosis in comparison with 30 apparently healthy volunteers randomly taken from the Mexican general population. Evaluation included DNCB sensitization, PPD skin test, determination of LIF, E and EAC-rosette formation and the ability of lymphocytes to survive in culture through periods of up to 48 hours. The results for the in vivo assays showed significant differences between the compared populations since the frequency of a positive PPD skin test was higher in the patients (p = 0.0000004) but only 60.8% of them responded to DNBC (p = 0.006). It was expected that there would be some impairment in the production of LIF and in the number of E-rosettes, however, this did not occur. Survival of lymphocytes in culture demonstrated an altered population of cells, probably weak even before blood samples were taken, in the tuberculosis group (p = 0.05). Furthermore, cell mortality was very notable in patients with cavitated and infiltrative lesions, after 48 hours culture (p = 0.015 and 0.02 respectively) suggesting the presence of a population of cells unable to function optimally.