[Descriptive epidemiology of children with acute myeloid leukemia residing in Mexico City: a report from the Mexican Inter-Institutional Group for Identifying Childhood Leukemia Causes]

INTRODUCTION

Acute myeloid leukemias represent the second most common childhood leukemia subtype. In Mexico, there are few studies on descriptive epidemiology for this disease.

AIMS

To report acute myeloid leukemia incidence for children less than 15 years of age in the Metropolitan Area of the Valley of Mexico for a period of five years (2010-2014) and to analyze whether there are differences in the incidence of acute myeloid leukemia by regions.

MATERIAL AND METHODS

A descriptive study was conducted in nine public hospitals in Mexico City. The crude annual average incidence rate and adjusted average annual incidence rate were calculated.

RESULTS

A total of 190 patients with diagnosis of de novo acute myeloid leukemia were analyzed. Male sex (57.2%) and acute myeloid leukemia-M3 subtype (25.3%) were more frequent. The adjusted average annual incidence rates for Mexico City and for the Metropolitan Area of the Valley of Mexico were 8.18 and 7.74 per million children under 15 years old, respectively.

CONCLUSIONS

It seems that childhood acute myeloid leukemia incidence is increasing in Mexico City, which makes the identification of associated risk factors imperative.

[Identification of Mycobacterium avium-intracellulare complex by PCR of AIDS and disseminated mycobacteriosis]

OBJECTIVE

The aim of this study is to differentially identify MAC by PCR in patients with AIDS and disseminated mycobacteriosis.

METHODS

A cross sectional study was conducted in Mexico to identify MAC by Molecular Biology. Two sets of primers were synthesized: MAV and MIN, for M. avium and M. intracellulare, respectively. Whole-cell DNAs obtained from 29 clinical isolates and clinical serum specimens from other 24 patients with AIDS and disseminated mycobacterial infection were extracted and amplified by PCR with the MAV and MIN primers. The MAV and MIN primers each amplified one highly specific 1.3-kb segment of the homologous DNA, respectively.

RESULTS

Twenty-nine DNAs from MAC clinical isolates identified by Gen-Probe AccuProbes were amplified with the MAV primers. Of the 24 clinical samples, 3 were positive for M. avium and 6 for M. tuberculosis.

CONCLUSIONS

Our results demonstrated that PCR technique could be applied for the differentiation of M. avium and M. intracellulare by specific 16S rRNA primers. In patients with advanced stage AIDS and in whom disseminated mycobacteriosis is suspected, the presence of anemia (even with negative cultures), elevated alkaline phosphatase and a median CD4 count of 15.9/mL, the diagnosis of infection by MAC should be strongly considered; we suggest that in accordance with our findings, a more precise stratification of patients in terms of their CD4 T cell counts is warranted.

Differential Immune Profiles in Two Pandemic Influenza A(H1N1)pdm09 Virus Waves at Pandemic Epicenter

Background and Aims

Severe influenza A(H1N1)pdm2009 virus infection cases are characterized by sustained immune activation during influenza pandemics. Seasonal flu data suggest that immune mediators could be modified by wave-related changes. Our aim was to determine the behavior of soluble and cell-related mediators in two waves at the epicenter of the 2009 influenza pandemic.

Methods

Leukocyte surface activation markers were studied in serum from peripheral blood samples, collected from the 1^st (April–May, 2009) and 2^nd (October 2009–February 2010) pandemic waves. Patients with confirmed influenza A(H1N1)pdm2009 virus infection (H1N1), influenza-like illness (ILI) or healthy donors (H) were analyzed.

Results

Serum IL-6, IL-4 and IL-10 levels were elevated in H1N1 patients from the 2^nd pandemic wave. Additionally, the frequency of helper and cytotoxic T cells was reduced during the 1^st wave, whereas CD69 expression in helper T cells was increased in the 2^nd wave for both H1N1 and ILI patients. In contrast, CD62L expression in granulocytes from the ILI group was increased in both waves but in monocytes only in the 2^nd wave. Triggering Receptor Expressed on Myeloid cells (TREM)-1 expression was elevated only in H1N1 patients at the 1^st wave.

Conclusions

Our results show that during the 2009 influenza pandemic a T cell activation phenotype is observed in a wave-dependent fashion, with an expanded activation in the 2^nd wave, compared to the 1^st wave. Conversely, granulocyte and monocyte activation is infection-dependent. This evidence collected at the pandemic epicenter in 2009 could help us understand the differences in the underlying cellular mechanisms that drive the wave-related immune profile behaviors that occur against influenza viruses during pandemics.

Clinical, radiological and molecular diagnosis correlation in serum samples from patients with osteoarticular tuberculosis

OBJECTIVE

To assess the role of polymerase chain reaction (PCR) in serum samples, in the diagnosis of osteoarticular tuberculosis (OTB) in a setting where only clinical and imaging diagnoses determine the treatment.

METHODS

A total of 44 consecutive serum specimens were collected from clinically suspected OTB patients, based on clinical and radiological [X-ray or magnetic resonance imaging/computed tomography] features. They were screened by in-house nested PCR. In addition, a few specimens were examined by Gram stain, acid-fast bacilli stain, histopathology and routine bacterial culture. A total of 39 specimens were collected from patients suffering from other bone diseases of nontuberculous origin and included as negative controls.

RESULTS

Of the 44 clinically suspected OTB patients, in-house nested PCR was positive in 40 (91%) cases; PCR was negative in 38 (97%) negative controls. Sensitivity and specificity of our in-house nested PCR was 90.9% and 97.4%, respectively. The PCR report was available within 48 h. It was possible to standardize serum PCR technique and in positive cases, a good correlation was observed in terms of an adequate treatment response.

CONCLUSIONS

Nested PCR in serum samples is a rapid, highly sensitive and specific modality for OTB detection. PCR should be performed in addition to clinical evaluation, imaging studies, acid-fast bacilli staining, culture and histopathology diagnosis, if possible.

Interferon γ in patients with HIV/AIDS and suspicion or latent tuberculosis infection

OBJECTIVE

To assess the usefulness of IGRA test (QuantiFERON(®)-Cell mediated immune) compared with the tuberculin skin test.

METHODS

A cross-sectional study was carried out in Mexico, 25 infected patients with HIV-AIDS and the suspicion or with latent tuberculous infection (LTBI) who were >18 years of age and without treatment for tuberculosis (TB), were enrolled in the study.

RESULTS

Median cluster of differentiation (CD4) count was 364 cells/μ L and median HIV viral load was 50 copies/mL. Overall, 20 patients (80%) had at least one positive diagnostic test for LTBI: four (16%) had a positive tuberculin skin test and 19 (76%), a positive QuantiFERON(®)-tuberculosis.

CONCLUSIONS

No agreement is found between the two diagnostic tests: k = -0.004, 95% confidence interval (-0.2219, 0.2210). Additional longitudinal studies among HIV-infected populations with high prevalence of TB are needed to further assess the usefulness of IGRAs in this patient population.

-592 and -1082 interleukin-10 polymorphisms in pulmonary tuberculosis with type 2 diabetes

OBJECTIVE

To determine the polymorphisms of Interleukin-10 (IL-10) (-592, -1082) in pulmonary tuberculosis (PTB) with and without type 2 diabetes (T2D).

METHODS

We studied a Mexican mestizo population of 37 patients with TB in remission (TBr) and 40 with active pulmonary TB (PTB), 21 patients with TB + T2D, 47 blood donors accepted, and 13 healthy health-care workers with tuberculin skin test positive. Determination of IL-10 polymorphisms was performed by real-time Polymerase chain reaction.

RESULTS

IL-10-592C/A presented in a greater proportion in healthy individuals than in patients with type 2 diabetes and TB in a not quite significant statistically manner. IL-10-1082A/A presented more frequently in the group of patients with both diseases, not being statistically significant in comparison with the group of healthy subjects.

CONCLUSIONS

This study describes two important new findings. First, it reveals that the IL-10 (-592 A/A and -592 C/C) polymorphisms were found in a greater proportion in a group of patients with T2D and TB than in healthy subjects. Second, the study provides evidence that the (-1082 G/G) polymorphism presented with greater frequency in healthy individuals than in patients with both of these diseases.

Genetic polymorphisms of the tumor necrosis factor and lymphotoxin alpha in type 2 diabetes

OBJECTIVE

To investigate the frequency of the single-base change polymorphic variants identified in tumor necrosis factor (TNF) gene (-308 G/A) and lymphotoxin alpha (LTA) (+252 G/A) in patients with type 2 diabetes (T2D).

METHODS

A prospective study in a Mexican-mestizo population of 51 patients with T2D and 48 healthy subjects was carried out. We took a peripheral blood sample from each individual for identification of the polymorphic genotypes by polymerase chain reaction.

RESULTS

The genotype distribution in T2D was: TNF alpha homozygous 0%; TNFG/A heterozygous 20%; TNFG homozygous 80%.

CONCLUSIONS

In regards to the TNF -308 G/A genotype, we found a significant difference (p = 0.012) with a bigger frequency in the group of patients. The health controls showed a higher frequency of TNF -308 G/G genotype (p = 0.034).

Pandemic influenza A/H1N1 virus infection and TNF, LTA, IL1B, IL6, IL8, and CCL polymorphisms in Mexican population: a case-control study

Background

Some patients have a greater response to viral infection than do others having a similar level of viral replication. Hypercytokinemia is the principal immunopathological mechanism that contributes to a severer clinical course in cases of influenza A/H1N1. The benefit produced, or damage caused, by these cytokines in severe disease is not known. The genes that code for these molecules are polymorphic and certain alleles have been associated with susceptibility to various diseases. The objective of the present study was to determine whether there was an association between polymorphisms of TNF, LTA, IL1B, IL6, IL8, and CCL1 and the infection and severity of the illness caused by the pandemic A/H1N1 in Mexico in 2009.

Methods

Case–control study. The cases were patients confirmed with real time PCR with infection by the A/H1N1 pandemic virus. The controls were patients with infection like to influenza and non-familial healthy contacts of the patients with influenza. Medical history and outcome of the disease was registered. The DNA samples were genotyped for polymorphisms TNF rs361525, rs1800629, and rs1800750; LTA rs909253; IL1B rs16944; IL6 rs1818879; IL8 rs4073; and CCL1 rs2282691. Odds ratio (OR) and the 95% confidence interval (95% CI) were calculated. The logistic regression model was adjusted by age and severity of the illness in cases.

Results

Infection with the pandemic A/H1N1 virus was associated with the following genotypes: TNF rs361525 AA, OR = 27.00; 95% CI = 3.07–1248.77); LTA rs909253 AG (OR = 4.33, 95% CI = 1.82–10.32); TNF rs1800750 AA (OR = 4.33, 95% CI = 1.48–12.64); additionally, LTA rs909253 AG showed a limited statistically significant association with mortality (p = 0.06, OR = 3.13). Carriers of the TNF rs1800629 GA genotype were associated with high levels of blood urea nitrogen (p = 0.05); those of the TNF rs1800750 AA genotype, with high levels of creatine phosphokinase (p=0.05). The IL1B rs16944 AA genotype was associated with an elevated number of leukocytes (p <0.001) and the IL8 rs4073 AA genotype, with a higher value for P_aO₂ mm Hg.

Conclusion

The polymorphisms of genes involved in the inflammatory process contributed to the severity of the clinical behavior of infection by the pandemic influenza A/H1N1 virus.

Functional state analysis of phagocytic cells of patients with type 2 diabetes and pulmonary tuberculosis

BACKGROUND

The phagocytic function in pulmonary tuberculosis (PTB) and Type 2 diabetes (T2D) has been explored mainly in macrophages but not in polymorphonuclears (PMN). The purpose of this study was to determine the functional status of PMN leukocytes in patients with pulmonary tuberculosis (PTB), Type 2 diabetes (T2D), and in patients with both diseases.

METHODS

An observational, prospective, and comparative study was carried out. 30 ambulatory patients with T2D, 10 with PTB undergoing treatment and 10 patients with PTB and T2D, and 44 healthy subjects were studied. PMN leukocytes were separated, the capacity of these cells to produce hydrogen peroxide and to reduce nitroblue tetrazolium (NBT) in response to stimulus with the phorbolic ester of myristic acid (PMA) was measured; and the capacity of PMN leukocytes to adhere to surfaces was determined.

RESULTS

Concerning the test for adherence, on comparing healthy subjects with patients with T2D+PTB, we observed a clear decrease in cellular adherence in the group of patients with both diseases; it was statistically significant (p = 0.007).With regard to phagocytic function, we observed that in NBT reduction as well as in hydrogen peroxide production, statistically significant differences were not obtained on comparing healthy subjects with any of the three groups of patients.

CONCLUSIONS

We observed a clear decrease in cellular adherence when both diseases co-exist. These results could indicate the need for the co-existence of T2D and TB to cause deterioration in the cells' adherence activity. The microtechniques employed permit the evaluation in a practical manner of certain phagocytic-activity expressions.

[CSF RT-PCR standardization in pediatric patients with enteroviral central nervous system infection]

OBJECTIVE

We standardized the RT-PCR panviral CSF and determined its applicability in detecting acute enterovirus infection in the central nervous system in children under 15 years.

MATERIAL AND METHODS

RT-PCR was performed directly in CSF samples of 10 pediatric patients with suspected CNS infection and 9, with different conditions of the central nervous system.

RESULTS

80% (8/10) of RT-PCR samples were positive for enterovirus in patients with suspected CNS infection and no sample was positive in patients with different ailments.

CONCLUSIONS

Since enteroviruses are among the main etiologies of pediatric encephalitis, RT-PCR could be particularly useful for rapid detection in CSF.

Cross-talk between Rac1 and Cdc42 GTPases regulates formation of filopodia required for dengue virus type-2 entry into HMEC-1 cells

Infection with dengue virus type-2 (DENV-2) begins with virus adherence to cell surface receptors. In endothelial cells (HMEC-1), a cell model for DENV-2 infection, alpha 5 beta 3 integrin has been identified as a putative receptor for the virus. Previous work had suggested that the actin cytoskeleton of HMEC-1 cells plays an important role in virus entry and infection. In the present work, fixed and living HMEC-1 cells expressing enhanced green fluorescent protein-actin were monitored for actin reorganization after virus inoculation, utilizing fluorescence and time lapse microscopy. Cell infection and production of infective viruses were quantified using an anti-E protein antibody and by measuring the p.f.u. ml(-1). Specific drugs that antagonize actin organization and regulate actin-signalling pathways were tested in viral adhesion and infection assays, as were the expression of dominant-negative Rac1 and Cdc42 proteins. Disorganization of actin precluded infection, while microtubule depolymerization had no effect. Activation of Rac1 and Cdc42 signalling, which occurs upon virus binding, induced reorganization of actin to form filopodia in the cellular periphery. Formation of filopodia was a requirement for virus entry and further cell infection. Expression of the dominant-negative proteins Rac1 and Cdc42 confirmed the role of these GTPases in the actin reorganization that is required to form filopodia. In addition, inhibition of the ATPase activity of myosin II greatly decreased infection, suggesting its participation in filopodial stability. We show here, for the first time, that internalization of DENV-2 into endothelial cells requires viral induction of dynamic filopodia regulated by Rac1 and Cdc42 cross-talk and myosin II motor activities.

Anti-chlamydophila pneumoniae antibodies as associated factor for carotid atherosclerosis in patients with AIDS

Atherosclerosis is a multifactor disease. Lately, infectious factors such as C. pneumoniae have been found to be involved. To determine whether the infection by C. pneumoniae is a risk factor for atherosclerosis in patients with AIDS. Case-control study on 43 patients with AIDS under HAART (16 cases and 27 controls). To document atherosclerosis, a carotid and transcranial Doppler ultrasound was performed. Anti-C pneumoniae antibodies were searched using a microimmunofluorescence test for IgM and IgG levels. To study the associations with risk of atherosclerosis, Odds Ratios were calculated for each IgG anti-C. pneumoniae antibody titre. A titre of 1:64 significantly increased the risk of atherosclerosis. These results suggest that hypertriglyceridemia and C. pneumoniae infection coexistence significantly increases the risk of atherosclerosis. The inverse geometric average of the antibodies titre against C. pneumoniae in individuals with atheromatous plaque fell to 64, two titres above the controls. This difference turned out to be statistically significant. Exposure to C. pneumoniae with antibodies (IgG) should be considered in any HIV diagnosed patient as a risk factor for atherosclerosis, having found that the inverse geometric averages of antibodies titre are significantly different comparing cases and controls, especially in patients with dyslipidemia, hypertriglyceridemia or in patients whose treatments could cause these conditions. In patients with concomitant hypertriglyceridemia, the association increases up to three times. It is advisable that AIDS patients take a serological test to determine exposure to C. pneumoniae, and to assess treatment options.

[Ying-Yang (YY-1) expression and Fas in biopsies of children with type IV lupus nephritis correlates with the clinical condition]

BACKGROUND

It has been demonstrated that Fasmediated apoptosis participates in the physiopathology of lupus nephritis, although it is not clear whether it contributes to the development of the tissue damage.Since YY-1 down regulates Fas in cancer cell lines, it is reasonable to consider that this transcription factor may control Fas expression in lupus nephritis. The objective was to determine the correlation between YY-1 and Fas expression in renal biopsies from children with type IV lupus nephritis, and their association with the clinical condition of the patients.

MATERIAL AND METHODS

Eighteen biopsies from children with type IV lupus nephritis and 5 controls were studied. Fas and YY-1 expression were determined by immunochemistry and quantified by densytometric analysis. The clinical conditions at the moment the biopsy were obtained from the clinical records and the results were analyzed through a one-way ANOVA with p<0.005.

RESULTS

The results of the densytometric analysis showed an inverse relationship between YY-1 and Fas expression. YY-1 was grouped according to the intensity of expression in low, moderate and high and compared with the expression of Fas. The lupus nephritis biopsies, which revealed high expression of YY-1, corresponded to patients with less number of clinical complications,better outcome and fewer alterations on renal function.In contrast, low expression of YY-1 correlated with high Fas expression and worst clinical conditions.

CONCLUSIONS

The present study suggests that YY-1regulates Fas expression in lupus nephritis and that it is associated with the clinical outcome of the patients,although further studies are necessary to determine weather it factor may serve as a prognosis factor. This is the first evidence of YY-1 participation in the physiopathology of lupus nephritis.

The intron 1 of HPV 16 has a suboptimal branch point at a guanosine

The branch point sequence (BPS) of intron 1 of the HPV-16 was determined via RT-PCR in a cell free system, using lariat intermediates obtained by in vitro splicing reactions. We used synthetic E6/E7 transcripts and HeLa nuclear protein extracts to obtain the splicing intermediates. Then, a divergent oligonucleotide primer set, pairing on the lariat RNA that encompassed the 2'-5' phosphodiester bond formed between the 5' end of the intron and the BPS, was used for cDNA synthesis and PCR amplification. Subsequent RT-PCR assays revealed four splicing intermediates, made up of a major intermediary corresponding to the BPS and four cryptic branched sequences. Only intermediates bound at the 5' end of the intron are probably the authentic branch point sequence, and all of them branch at guanosine 328 instead of the typical adenosine. Unusually, the BPS of intron 1 of HPV-16 is a suboptimal sequence (AGUGAGU) that differs from the eukaryotic consensus BPS, which correlates with the splicing profile observed for early transcripts of HPV-16 in tumors and tumor derived cell lines. The implications of this unusual branch point sequence for splicing of the HPV-16 pre-mRNA are discussed.

[Antibodies against Chlamydophila in patients with acute myocardial infarction and coronary risk and their association with mortality]

OBJECTIVE

The primary aim of this study was to determine whether antibodies against Chlamydophila pneumoniae in patients with acute myocardial infarction (AMI) and coronary risk factors are associated with death.

MATERIAL AND METHODS

A cross-sectional study was conducted among 100 patients hospitalized in the Coronary Unit of Centro Medico La Raza Hospital of the Mexican Institute of Social Security, between 1999 and 2000. Subjects were males and females older than 18 years, diagnosed with AMI and coronary risk. Antibodies against Chlamydophila pneumoniae, Chlamydophila psitacii and Chlamydia trachomatis were measured using an indirect microinmunofluorescence assay. In addition, blood samples from 33 patients from the original group were taken when the patients were discharged from the hospital,and 3 months after their myocardial infarction. Data analysis consisted of geometric means and standard deviations as well as odds ratios with 95% confidence intervals.

RESULTS

Seventy percent of patients presented antibodies against Chlamydophila pneumoniae. Antibodies against Chlamydophila psittaci and Chlamydia trachomatis were not identified. No statistically significant association was found between antibodies and death in these patients with coronary risk factors and AMI. In the subgroup of 33 individuals 25 had antibodies against Chlamydophila pneumoniae and in 83% of them antibodies decreased three months after the AMI event.

CONCLUSIONS

Even though patients with coronary risk factors and AMI had an increased seropositivity for Chlamydophila pneumoniae it was not significantly associated with death.

Display and release of the Plasmodium falciparum circumsporozoite protein using the autotransporter MisL of Salmonella enterica

The Salmonella enterica MisL (protein of membrane insertion and secretion) is an autotransporter with high homology to AIDA-I (adhesin involved in diffuse adherence) of enteropathogenic Escherichia coli. Considering that it has been reported that the MisL beta translocator domain is able to display heterologous passenger peptides to the bacterial surface, we developed a system to display proteins and release them to the external environment by means of proteolytic cleavage. Plasmids were constructed encoding 8 or 53 repeats of the NANP (Asp-Ala-Asp-Pro) tetrapeptide, which is the main B cell epitope of the Plasmodium falciparum circumsporozoitic protein (CSP), fused to the the MisL beta-domain and including the recognition cleavage sequence from the E. coli OmpT surface protease. E. coli XL-10Gold and BL21(DE3) (OmpT positive and negative, respectively) and Salmonella enterica serovar Typhimurium SL3261 (Aro A(-)) were transformed with the plasmids and, both expression and localization of the fusion proteins were assessed by Western blot, indirect immunofluorescence, and flow cytometry, using a monoclonal antibody against (NANP)(3). Higher expression of the (NANP)(8) and (NANP)(53) fusion proteins was demonstrated on the bacterial surface of the OmpT negative E. coli strains and the (NANP)(53) in the culture supernatant of E. coli XL-10Gold indicating a protease mediated cleavage. The flow cytometry analysis suggested 71 and 98% cleavage efficiency for the (NANP)(8) and (NANP)(53), respectively, in E. coli XL-10Gold. Similar results were obtained in S. enterica serovar Typhimurium SL3261, suggesting the involvement of other proteases related to OmpT. These results demonstrate that MisL may be used for the autodisplay and release of passenger proteins in attenuated Salmonella or E. coli strains, which may have several applications in vaccine design.

Expression of the Plasmodium falciparum immunodominant epitope (NANP)(4) on the surface of Salmonella enterica using the autotransporter MisL

Gram-negative bacterial proteins which are exported from the cytosol to the external environment by the type V secretion system are also known as autotransporters. Once translocated to the periplasmic compartment by the sec-dependent general secretory pathway, their C-terminal domain forms a pore through which the N-terminal domain travels to the outer membrane without the need of other accessory proteins. MisL (protein of membrane insertion and secretion) is a protein of unknown function located in the pathogenicity island SPI-3 of Salmonella enterica and classified as an autotransporter due to its high homology to Escherichia coli AIDA-I. In the present work, the MisL C-terminal translocator domain was used to display the immunodominant B-cell epitope of the circumsporozoite protein (CSP) from Plasmodium falciparum on the surface of Salmonella enterica serovar Typhimurium (serovar Typhimurium SL3261) and serovar Typhi (serovar Typhi CVD 908). The MisL beta domain was predicted by alignment with AIDA-I, amplified from serovar Typhimurium SL3261, cloned in a plasmid fused to four repeats of the tetrapeptide NANP behind the Escherichia coli heat-labile enterotoxin B subunit signal peptide to ensure periplasmic traffic, and expressed under the control of the anaerobically inducible nirB promoter. The fusion protein was translocated to the outer membrane of both bacterial strains, although the foreign epitope was displayed more efficiently in serovar Typhimurium SL3261, which elicited a better specific antibody response in BALB/c mice. More importantly, antibodies were able to recognize the native CSP in P. falciparum sporozoites. These results confirm that MisL is indeed an autotransporter and that it can be used to express foreign immunogenic epitopes on the surface of gram-negative bacteria.

New approaches to improve a peptide vaccine against porcine Taenia solium cysticercosis

Cysticercosis caused by Taenia solium frequently affects human health and rustic porciculture. Cysticerci may localize in the central nervous system of humans causing neurocysticercosis, a major health problem in undeveloped countries. Prevalence and intensity of this disease in pigs and humans are related to social factors (poor personal hygiene, low sanitary conditions, rustic rearing of pigs, open fecalism) and possibly to biological factors such as immunity, genetic background, and gender. The indispensable role of pigs as an obligatory intermediate host in the life cycle offers the possibility of interfering with transmission through vaccination of pigs. An effective vaccine based on three synthetic peptides against pig cysticercosis has been successfully developed and proved effective in experimental and field conditions. The well-defined peptides that constitute the cysticercosis vaccine offer the possibility to explore alternative forms of antigen production and delivery systems that may improve the cost/benefit of this and other vaccines. Encouraging results were obtained in attempts to produce large amounts of these peptides and increased its immunogenicity by expression in recombinant filamentous phage (M13), in transgenic plants (carrots and papaya), and associated to bacterial immunogenic carrier proteins.

Medium-sized arterial vasculitis associated with vascular deposits of immunoglobin E. Favorable response to intravenous methylprednisolone and cyclophosphamide

Herein we describe the case of a female patient with medium-sized arterial vasculitis associated with high serum immunoglobin E (lgE) levels in the absence of eosinophilia. During occlusive vascular events, IgE deposits in the arterial muscle layer were demonstrated by immunohistochemistry, suggesting a pathogenic role of this antibody in blood vessel inflammation. Combined treatment with methylprednisolone and cyclophosphamide was successful in reducing serum IgE levels and IgE tissue deposits and in inducing the clinical manifestations of vasculitis into remission. This primary medium-sized IgE-associated vasculitis may constitute a new syndrome not previously reported.

[Principal serotypes of Salmonella identified in 10703 strains in Mexico from 1982 to 1993]

From 1982 to 1993, 10703 Salmonella strains from The National Network of Diarroheal Laboratories of Mexico were sent to the Enteric Bacteriology Laboratory of INDRE. The strains were confirmed by serology and 119 different Salmonella serotypes were found. The most frequent serotypes were as follows: S. typhimurium, S, enteritidis, S. agona & S. typhi. The strains were classified according to the source of isolation as follows: 6671 strains (62.33%) from clinical samples, mainly of faecal origin; 2903 (27.1%) from food for human consumption; 425 from food for animal consumption, 665 (6.21%) from environment or fomites and 39 (0.36%) from animals. The most frequent serotype in clinical samples was S. typhimurium among 96 different serotypes. The main serotype from blood cultures was S. typhi although 27 other serotypes were found. Of thirteen serotypes related to diarrhoeal outbreaks the higher frequency of S. typhimurium was observed but S. typhi caused more outbreaks. A frequency of 119/> 2000 serotypes was observed, that means less than 5% of Salmonella known serotypes. A yearly variability on serotype predominance was observed as well as changes on source of isolation. This results suggest that epidemiological surveillance of salmonellosis should be continued and improved, looking for cases, asymptomatic carriers and contaminated food for human consumption.

[Seroepidemiology of cholera in Mexico]

Antibodies against Vibrio cholerae were determined in 2352 serum samples obtained from patients with clinical diagnosis of cholera. Samples from their contacts and from healthy people living in the same communities were also analyzed. Vibriocidal antibodies with titers 1:160 or higher were observed in 25% of the samples. An increase of vibriocidal and antitoxin antibody titers were observed in 56 to 60% of the patients in which paired samples were available, one obtained in the acute phase of the disease and the other in the convalescence, confirming the diagnosis of cholera. Differences in the antibody titers were noticed when comparing the serotype according to the geographic area and the season of the year.

[Analysis of 1185 strains of Shigella isolated in Mexico from 1982 to 1993]

During the period from 1982 to 1993, 1185 Shigella strains from the National Network of Diarrhoeal Laboratories were sent to the Enteric Bacteriology Laboratory of INDRE. These strains from patients of various ages with diarrhoeal illness were serologically confirmed. The frequency was as follows: S. flexneri (61.35%), S. sonnei (26%), S. dysenteriae (6.4%) and S. boydii (6.2%). S. dysenteriae 1 is an epidemiologicaly important species because it has caused diarrhoeal outbreaks on the southern border of Mexico that later spread through Central America. It must be considered that the 20 isolates obtained in 1989 were from an intentional search focused on S. dysenteriae. Authors pretend to continue with epidemiological surveillance focused on Shigella and intensify the intentional search in order to identify possible human or environmental S. dysenteriae 1 reservoires.

[Evaluation of the ELISA method for cholera toxin determination in Vibrio cholerae cultures]

ELISA test was evaluated in 503 cultures of Vibrio cholerae O1 y 303 Non-O1. The cultures were isolated from sewage from different states of México between june 1991 and october 1992. The sensitivity was 100% and specificity was 96%. Only 12 strains of V. cholerae Non-O1 were positive for CT toxin. When these cultures were confirmed by polymerase chain reaction (PCR) for cholera toxin, the results were negative. ELISA test is a good alternative to be used for toxin production in cultures of V. cholerae, it needs confirmation only with O1 negative and Non-O1 positive reactions.

[Identification of Vibrio cholerae O1 by flow cytometry]

A total of 72 peptonated water samples suspected of carrying Vibrio cholerae were assessed by laser flow cytometry (LFC) and compared with positive culture. We used a direct fluorescence technique using polyclonal (PolAb) and monoclonal antibodies (MoAb) conjugated to fluorescein. The PolAb were able to detect 33 positive samples. A clear difference among the 20 positive samples was found with only three V. cholerae O1 false negatives when MoAb were used whereas all 13 V. cholerae Non O1 samples were detected. The correlation index comparing control autofluorescence with peptonated water samples show a R = 0.69, versus 0.96 with pure V. cholerae O1 strains. Our data suggest that the LFC technique is able to recognize V. cholerae O1 from a mixture of microorganisms with high sensitivity and specificity in a few hours.