[Alleles of the major histocompatibility system associated with susceptibility to the development of Takayasu's arteritis]

OBJECTIVE

Since 1972, the relationship between HLA alleles and the susceptibility for Takayasu arteritis (TA) has been studied on different populations. Hence the results up to date are heterogeneous, the objective of the present review is to analyze the relationship between the presence of HLA alleles and the susceptibility for the development of TA considering the ethnic origin of the studied populations.

MATERIAL AND METHODS

We carried out a bibliographic review from clinical articles of case and controls studies on different populations on which the relationship between HLA alleles and the susceptibility for TA was studied, published since 1972 until February 2000.

RESULTS

We reviewed articles of studies on Asian, Arab, North-American and Mexican Mestizo populations. On Asian populations TA was associated with HLA-A31, -B52, -B39, -B5 and -DR2, on Arabs with HLA-A2, -A9, -B35 and -DR7, on North-Americans with HLA-DR4 and on Mexican Mestizo with HLA-B5, -B52 and -DR6. On the other hand, recent reports establish that several HLA-B alleles (HLA-B52 and HLA-B39) associated with the disease share some residues important on the antigen presentation.

CONCLUSIONS

Hence the heterogeneity of the results obtained up to date, it stands out the increase on HLA-B52 and HLA-DR4 reported on ethnically different populations. More recent data point the possible participation of an epitope located on the peptide-binding site of the HLA-B molecule (positions 63 and 67) that seems to be shared by several alleles associated with the disease. These residues might be participating on the presentation of an unknown antigen that would unchain the disease on the genetically susceptible individuals group.

[Specific dilated myocardiopathy. Chronic chagasic cardiopathy at the National Institute of Cardiology Ignacio Chávez]

Cardiomyopathies are a heterogenous group of heart ailments. Some of them are primary myocardial diseases and are classified as dilated, hypertrophic, restrictive and arryhithmogenic. Dilated cardiomyopathies (DCs) are the most common. Sometimes it is possible to identify an etiologic agent, in that case we talk about a specific dilated cardiomyopathy. Here in, we review one of these specific DCs, the so called Chronic Chagasic Cardiopathy (CCC) from the point of view of our personal experience at the Instituto Nacional de Cardiología "Ignacio Chávez". Chagas' disease is present in Mexico, therefore CCC is also present. We estimate that 5,000 people, suffer CCC with severe symptoms. In Mexico, Chagas' disease occurs below the Tropic of Cancer and between 2,000-2,500 m above sea level, in this area there is a real risk for vectorial infection, mainly in rural villages. Clinical diagnosis should be supported by epidemiological and seroepidemiological confirmatory data. There is not appropriate therapy yet for this condition.

Seroprevalence of human Trypanosoma cruzi infection in diferent geografic zones of Chiapas, Mexico

A serologic survey was carried out in four different geographic zones of Chiapas, Mexico. A total of 1,333 samples were collected from residents of thirteen communities located on the Coast, Central Mountain, Lacandon Forest and a zone called Mesochiapas. One hundred and fifty one seropositive individuals (11.3%) were identified. Human Trypanosoma cruzi infection was influenced by geography. In the Lacandon Forest and Central Mountains there was a higher seroprevalence 32.1 and 13.8% respectively, than on the coast (1.2%). In Mesochiapas there were no seropositive individuals among the 137 persons tested. An active transmission is probably continuing because seropositive cases (13.8%) were detected in children under 10 years of age. The vector recognized on the Coast was Triatoma dimidiata while in the Lacandon Forest it was Rhodnius prolixus.

Standardization of micro-enzyme-linked immunosorbent assay (ELISA) and Western blot for detection of Trypanosoma cruzi antibodies using extracts from Mexican strains as antigens

BACKGROUND

This report describes two assays for the detection of anti-Trypanosoma cruzi antibodies using Mexican strains of the parasite and the concordance with two assays previously evaluated at the Instituto Nacional de Cardiología Ignacio Chávez in Mexico City.

METHODS

Micro-enzyme-linked immunosorbent assay (ELISA) and Western blot were used for the detection of T. cruzi antibodies with a total extract of epimastigote from Ninoa and Queretaro, which are Mexican strains of T. cruzi. To standardize these methods, a total of 246 serum samples was used. In addition, sera from six confirmed Mexican chronic individuals in the asymptomatic phase were also used for comparison with the Argentinean antigen.

RESULTS

ELISA was 100% specific in that no false positive results were found with sera of both healthy individuals and non-Chagasic cardiopaths. Sera from individuals infected with Leishmania sp. showed approximately 16% of cross-reaction with ELISA. The test showed a positive predictive value of 90% and a negative predictive value of 100%. Western blot was also a highly sensitive test for detecting chronic Chagasic symptomatic patients from Mexico because no false negative results were obtained. Furthermore, it was possible to use Western blot to detect seven immunodominant antigens of approximately 30, 32, 40, 42, 65, 70, and 83 kDa. Concordance with two previous standardized tests at the Instituto Nacional de Cardiología showed a Kappa index of 0.96, indicating high concordance between the results obtained at these two laboratories. Finally, ELISA using Ninoa antigen extract was more sensitive than ELISA with an Argentinean extract, which failed to detect individuals in the chronic asymptomatic phase (undetermined phase) of infection.

CONCLUSIONS

This study indicates that ELISA and Western blot using Ninoa and/or Queretaro extracts of T. cruzi as antigens are useful tools in the detection of individuals who have been exposed to T. cruzi both in the undetermined/asymptomatic and symptomatic phases. More concordance studies such as this are recommended to obtain an accurate Chagas diagnostic test and to determine the real prevalence of this disease in Mexico.

IgG subclass reactivity to Trypanosoma cruzi in chronic chagasic patients

BACKGROUND

The anti-Trypanosoma cruzi antibodies isotype profile in Chagas' disease has been studied in relation to different clinical manifestations. A high titer of IgG anti-T. cruzi antibodies is found in patients with cardiac involvement, while a high titer of IgA anti-T. cruzi antibodies is associated with digestive forms.

OBJECTIVE

The aim of this work was to analyze the IgG subclass reactivity of anti-T. cruzi antibodies in patients with chronic Chagasic cardiomyopathy.

METHODS

Twelve consecutive chagasic patients were analyzed for IgG subclass reactivity to a T. cruzi antigenic extract. They had a complete clinical evaluation, peripheral EKG, echocardiography, left ventriculogram, and coronariography.

RESULTS

All patients came from rural areas of Mexico and had lived in endemic zones for over seven years. They presented left ventricular endsystolic dimension above 42 mm in 58% (7/12) and ejection fraction below 50% in 58% (7/12). We found that IgG1 and IgG2 anti-T. cruzi antibodies showed higher titer than IgG3 antibodies, with consistently low titer of IgG4 antibodies. Expression of the four IgG subclasses of anti-T. cruzi antibodies suggest a mixed Th1/Th2-like immune response under a probably continuous chronic antigenic stimulation. On the other hand, high levels of IgG2 anti-T. cruzi antibodies showed a tendency to be associated with severe cardiomegaly.

CONCLUSIONS

Our results suggest that a mixed Th1/Th2-like immune response may take place in chronic chagasic patients under a chronic antigenic stimulation.

Immunogenetics and clinical aspects of Takayasu's arteritis patients in a Mexican Mestizo population

OBJECTIVE

The aim of the present work was to study the association between HLA alleles and Takayasu's arteritis in Mexican Mestizo patients.

METHODS

The study included 26 Mexican Mestizo patients with Takayasu's arteritis and 99 healthy unrelated individuals. HLA-A, -B and -DR alleles were determined by polymerase chain reaction PCR-SSP RESULTS: Increased gene frequencies were demonstrated for HLA-B15(p=0.009,pC=0.020,OR=3.24,EF=11.9%) and HLA-B52 (p=0.008, pC=0.027, OR=5.16, EF=7.7%), and a decreased frequency for the HLA-A24 allele in patients compared to normal controls (p=0.035, pC=NS, PF=11.1%). When HLA typing was correlated to clinicalfeatures in 24 cases, wefound an increasedfrequencies of HLA-DR14 in patients with systemic arterial hypertension (p=0.005, pC=0.004, OR=24.6, EF=38.3%) and HLA-A2 on patients with pulmonary involvement (p=0.034, pC=0.036, OR=3.67, EF=40.4%) when compared to patients without these clinical manifestations.

CONCLUSION

These data confirm HLA-B52 as a relevant susceptibility allele for Takayasu's arteritis and suggest that HLA-B15 could be important as a marker of the disease in Mexican patients. Other class I and/or class II alleles could also be relevant as markers for the clinical features present in these patients.

[Rheumatic fever in the 5-year period of 1994-1999 at 2 hospitals in San Luis Potosi and Mexico D.F]

OBJECTIVE

To assess the incidence of acute Rheumatic Fever (ARF).

PATIENTS AND METHODS

A retrospective, descriptive, observational study on the first attack and recurrence was performed in a general hospital and a reference center.

RESULTS

By Jones criteria: 67 cases, 39 women and 28 men; 58% first attack, 42% recurrence. Higher incidence during spring-winter. The most common major criteria were: carditis, polyarthritis. The most common minor criteria were: fever, arthralgias and acute phase reaction markers. No differences between hospitals were noted. Evidence of contact with streptococcus was found. Mitral, aortic and tricuspid valves were commonly affected. Incidence in the age group > 5 < 20 was 7/1000.

DISCUSSION

Incidence of ARF has decreased, but has not been eradicated. It occurs in developing countries, where it remains an issue of public health. Failures in clinical suspicion, prophylaxis, and adherence to treatment influence this situation. Education for health, early diagnosis, and primary and secondary prophylaxis should be reinforced.

Persistence of Trypanosoma cruzi in chronic chagasic cardiopathy patients

BACKGROUND

Although patients with chronic chagasic cardiopathy do have a strong immune response against Trypanosoma cruzi, they have transient and low parasitemia as well as tissue amastigote nests. When conventional studies were carried out, demonstration of such abnormalities is minimally achieved. Molecular biology may provide the best tools to demonstrate parasite persistence, which could be pathogenic in this progressive disease.

METHODS

We studied 16 patients with chronic chagasic cardiopathy (CCC) at the Instituto Nacional de Cardiología Ignacio Chávez in Mexico City. Patients had undergone a complete clinical evaluation, and had antibodies against Trypanosoma cruzi. They came from different rural areas in Mexico. Blood samples were obtained and processed for hemoculture and PCR technique. A CCC necropsy case was also sought for the presence of parasite antigen or DNA, using immunohistochemistry and PCR methods in archival tissues.

RESULTS

Five of 16 (31%) hemocultures demonstrated circulating T. cruzi; 60% occurred in persons between 25 and 40 years old. In contrast, we found a positive PCR amplification in 81%; therefore, molecular biology tools appear to be more sensitive for demonstrating parasite persistence. There were no correlations between parasitemic state and clinical findings or specific antibody titer. The autopsy case had parasite antigens and DNA in heart tissues.

CONCLUSIONS

Chronic chagasic cardiopathy patients do have persistence of parasite even when parasitemia is low or absent. The continuous presence of a parasite load could maintain immune stimulus and perhaps enhance a pathogenic immune or autoimmune tissue damage in susceptible hosts.

Absence of antiphospholipid/co-factor antibodies in Takayasu arteritis

There are anecdotal reports and small series describing the presence of anticardiolipin antibodies in patients with Takayasu Arteritis. This communication describes a systematic study searching for non-organ specific autoantibodies which includes antinuclear antibodies, anticardiolipin and anti-beta(2) GP(1) antibodies in a cohort of 28 Mexicans with angiographic definitive diagnostic of Takayasu Arteritis.

MATERIAL AND METHODS

Twenty-eight consecutive patients, who fulfilled classification and diagnostic criteria for Takayasu Arteritis and had a diagnostic panaortogram, were bled to study the presence of circulating autoantibodies in a cross-sectional design.

RESULTS

There were no antinuclear antibodies, although a few sera had faint cytoplasm fluorescent deposit and reacted with cell extract. We did not recognize a distinct pattern. Also, there was no IgG nor IgM anticardiolipin antibodies nor anticofactor antibodies of clinical interest.

DISCUSSION AND CONCLUSIONS

The presence of circulating non-organ specific autoantibodies is not a characteristic feature in Takayasu Arteritis when strict diagnostic criteria are applied. The occasional presence of such immune markers could be due to technical differences in sample management, less strict diagnosis or biological variability in certain cases, but has no diagnostic value.

[Does heart sarcoma mimick lupus erythematosus and vasculitis? Report of 2 cases]

Primary heart tumors are rare. The most common one is myxoma. It may synthetize IL-6 and frequently shown systemic clinical manifestations that confuse the diagnosis. Primary heart sarcomas are even more rare, as far as we know they have been not associated with systemic illnesses. We observed two cases with a presumptive diagnosis of systemic lupus erythematosus who were identified as primary sarcomatous heart neoplasms after surgical excision.

[The utility of rapid qualitative determination of troponin T, the MB fraction of creatine phosphokinase and myoglobin in acute ischemic coronary syndromes]

The objective of our study was to validate the diagnostic utility of cardiac troponine T in acute ischemic syndromes, and also in cases of difficult diagnosis. We analyzed its concordance and compare them with conventional enzymatic quantitative methods. We determined sensitivity, specificity, positive and negative predictive values and likelihood ratio. Kappa index was used to know the concordance grade between T troponin and the positive or negative results of the quantitative enzymatic curve. Stochastic significance was valued by Chi square of Mcnemar test. In seventy patients who arrived to the hospital with chest pain who were assigned to five different groups. The sensitivity in quantitative markers was higher than qualitative methods, however the specificity, likelihood ratio was lower. In the total group the concordance analysis between qualitative and quantitative markers was adequate, (kappa index 0.65 p < 0.05). This study suggest that the rapid bedside qualitative test by cardiac Troponin T is a good diagnostic marker compared with conventional quantitative markers to evaluate chest pain in acute ischemic syndromes.

Antiaorta antibodies and Takayasu arteritis

A search for antibodies reactive against a total human aorta extract and its main protein components such as elastin, fibronectin and collagen was attempted by electroimmunetransference and ELISA. Thirty five sera from clinically and angiographically proven diagnosis of Takayasu Arteritis patients were compared with 32 sera from people without abnormalities. Non specific binding was found on electroimmune transference and no difference was shown in optical density readings in ELISA, therefore, we did not demonstrate the presence of antiaorta specific antibodies in this vasculitic condition. Our findings are in agreement with several authors, the contribution of humoral immunity to pathogenesis of Takayasu Arteritis has not been proved yet.

[Coxiella burnetii endocarditis. A report of the first case diagnosed in Mexico]

The first case of Q fever endocarditis that has been diagnosed in Mexico is presented. A 10-year-old girl with discrete subaortic stenosis (SAS) and patent ductus arteriosus (PDA) was seen in December of 1996 with fever, hepatomegaly and splenomegaly. She presented also anemia, leukopenia, hypergammaglobulinemia, positive rheumatoid factor, cryoglobulinemia, antinuclear and anticytoplasmic antibodies (anti-RNA-proteins and anti-DNA). An aortic valve vegetation was seen by echocardiogram. Blood-cultures were negative. Antibody test for Coxiella burnetii was positive. Treatment with doxicyclin was initiated as soon the diagnosis was done. PDA was closed, SAS was liberated and two aortic vegetations were resected. Endocarditis in Q fever occurs when there is predisposing heart disease and/or immunodeficiency. Effective therapy has not yet been established. The diagnosis of Q fever endocarditis is difficult; it should be considered, in case of clinical suspicion of endocarditis with negative blood-cultures.

Humoral nitric oxide levels and antibody immune response of symptomatic and indeterminate Chagas' disease patients to commercial and autochthonous Trypanosoma cruzi antigen

We report here the evaluation of chagasic patients for the presence and/or severity of the disease, antibody to Trypanosoma cruzi, and nitric oxide (NO) serum levels. Serum samples tested by ELISA with autochthonous and commercial antigen revealed that 10% and 7.5% of the individuals were anti-T. cruzi antibody-positive, respectively. Ten of 21 seropositive individuals had no clinical signs, the other 11 cases presented cardiomyopathy and/or mega-gastrointestinal syndromes, and three patients presented a combined form. A statistical difference (P < 0.001) in antibody titer between asymptomatic and symptomatic patients with autochthonous antigen was detected, and serum NO levels was found to be three times higher in cases than in controls. These results suggest that it is recommended to use a sole source of antigen (autochthonous) for the serodiagnosis of Chagas' disease, and that the pathogenic role of NO in this disease should be evaluated.

[Rheumatic cardiopathy and Chagas disease]

Rheumatic heart disease is common in the undeveloped world; Chagas disease, a typical rural parasitic condition started to affect urban areas. Both have a relatively high incidence and prevalence in Latin America, however, we could not find a report of patients with coincidental rheumatic heart disease and Chagas disease. Herein we report the first documented case.

[The usefulness of determining myoglobin, creatine phosphokinase MB isoenzyme, lactate dehydrogenase and aspartate aminotransferase in the diagnosis of acute myocardial infarct]

Diagnosis of acute myocardial infarction is made with the aid of biomarkers such as structural myocardial proteins, myoglobin (MG) or specific enzymes, creatine phosphokinase isoenzyme MB (CK-MB) or non specific enzymes, lactic dehydrogenase (DHL) and aspartate aminotransferase (AST). We found good sensitivity (71%-50%), specificity (85%-100%) and predictive values (Pos. 77%-100%, Neg. 82%-72%) for Mg and CK-MB, supporting their clinical usefulness. In contrast DHL and AST were not clinically useful for early diagnosis.

Molecular analysis of snRNAs and scRNAs using autoantibodies from patients with systemic lupus erythematosus

Immunoprecipitation analysis of total HeLa cells RNA extract by protein A-Sheparose purified autoantibodies and pCp 32P-3' end labeling RNAs revealed that U1, U2, U4 and U5 snRNAs are related with anti-Sm or U1nRNP autoantibodies, while the hY1, hY3, hY4 and hY5 scRNAs were related to anti-SSA/Ro autoantibodies present in sera of patients with Systemic Lupus Erythematosus. The authors detected molecular snRNAs and scRNAs specificities by autoantibodies in 71 sera, the molecular RNA specificity for anti-Sm (U1, U2, U4 and U5 snRNAs) was present in 39%; anti-SSA/Ro sera reacted against scRNAs (hY1, hY3, hY4 and hY5) in 36%, then anti-U1nRNP sera recognized U1 snRNA in 13% of sera and anti-rRNP related with rRNA were recognized in 8%. Twenty-nine SLE sera were RNA negative. A molecular characterization of the autoantibodies in sera from SLE patients may be a useful tool for clinical and laboratory diagnosis of SLE, and the use of autoantibodies as molecular probes allows to continue exploring some basic mechanism of gene expression.

[Late potentials and variability of cardiac frequency in chronic chagasic myocardiopathy and other myocardiopathies]

In patients suffering dilated cardiomyopathy, chagasic or not, and in healthy volunteers we applied signal-averaged electrocardiography to detect late potentials and to study heart autonomic control. Thus, with non-invasive methods, we were able to explore the progress of depolarization and heart rate variability. It was found that Chagasic patients have more late potentials and abnormalities in the heart variability; with less co-morbid process when compared with patients suffering miscellaneous cardiomyopathies. These preliminary findings corroborate and expand previous observations by several authors. The signal-averaged electrocardiogram is a valuable tool for clinical diagnosis and research, particularly for studies on dilated cardiomyopathy, specially those with parasitic etiology.

Absence of ANCA in Mexican patients with Takayasu's arteritis

Antineutrophil cytoplasmic autoantibodies (ANCA) were sought in 43 sera from 39 Mexican patients with typical Takayasu's arteritis (TA), (5 with active and 34 with inactive disease), and in a comparative group comprising 50 sera. Results were negative in all cases. This suggests that ANCA are not a serologic feature in TA per se, even during its active stage. ANCA positivity in TA, when present, may be a non-related phenomenon and probably identifies a subset of patients with atypical forms of TA or a polyangiitis overlap syndrome.