Towards establishing MS prevalence in Latin America and the Caribbean.

A very high prevalence of multiple sclerosis (MS) has been reported in some Western European and North American countries. The few surveys of MS epidemiology in South America reveal lower prevalence rates, implying that susceptibility varies between distinct ethnic groups, thus forming an important determinant of the geographic distribution of the disease. The objective of this study is to review MS prevalence estimates in different Latin American and Caribbean countries. We reviewed surveys of regional MS prevalence from 1991 to 2011. Sources included an online database, authors' reports and proceedings or specific lectures from regional conferences. We obtained a total of 30 prevalence surveys from 15 countries, showing low/medium MS prevalence rates. Both the number and the quality of prevalence surveys have greatly improved in this region over recent decades. This is the first collaborative study to map the regional frequency of MS. Establishment of standardized methods and joint epidemiological studies will advance future MS research in Latin America and the Caribbean.

Molecular characterization of the CCR 5 gene in seronegative individuals exposed to human immunodeficiency virus (HIV).

BACKGROUND: Both clinical and laboratory evidence in exposed seronegative (ESN) individuals to human HIV-1 has suggested the existence of mechanisms of natural resistance to the infection. A 32 base-pair deletion in the gene that codes for the CCR5, which is the main coreceptor for HIV-1, confers a high degree of resistance to HIV-1 infection. However, the genotype Delta32/Delta32 is present only in 2-4% of Caucasoid ESN individuals suggesting the existence of other mechanisms of protection. Mutations different from Delta32 have also been proposed as playing a role in resistance/susceptibility to this infection. OBJECTIVE: To screen for different mutations along the entire coding region of the ccr5 gene that can potentially explain the persistent seronegativity in a group of ESN individuals. STUDY DESIGN: Of a total of 86 individuals analyzed for Delta32 mutation by the PCR technique, 36 scored HIV seropositive (SP) and 50 were ESN. The entire group of ESN individuals was screened for other mutations in the ccr5 gene by single strand conformational polymorphism (SSCP) and DNA sequencing. RESULTS: The frequency of the mutant allele Delta32 was 4% (4/100) for ESN individuals and 4.2% (3/72) for SP individuals. The homozygous mutant genotype (Delta32/Delta32) was found in only 2% (1/50) of ESN individuals, but in no SP individuals. The heterozygous genotype was found in 8.3% (3/36) of SP individuals and in 4% (2/50) of ESN individuals. The differences in the allelic and genotypic frequencies among the groups were not statistically significant. A comparison between the observed and the expected genotypic frequencies showed that they were significantly different for the ESN group, suggesting a protective, yet indirect effect of the mutant genotype. CONCLUSIONS: The screening of the entire coding region of the ccr5 gene in all ESN did not revealed no other mutations that could account for resistance to HIV-1 infection. Although the CCR5 molecule is the most important coreceptor for HIV-1, mutations in this gene do not account for most of the cases of natural resistance to this virus that have so far been reported.

Frequency of respiratory syncytial virus in hospitalized infants with lower acute respiratory tract infection in Colombia.

PIP: In Colombia, health workers obtained a nasopharyngeal wash from 103 infants aged less than 12 months hospitalized for acute lower respiratory infection (ALRI) at the General Hospital of Medellin during April 1994 to April 1995 so researchers could determine the frequency of ALRI caused by respiratory syncytial virus (RSV) in hospitalized children. Immunofluorescence detected RSV infection in 43 (41.7%) patients. The presence of the following signs and symptoms allowed a clinical diagnosis of a viral infection: rhinorrhea, prolonged expiration, expiratory wheezing, interstitial infiltrates, and hyperinflation on chest radiographs as well as negative tests for 3 or 4 acute phase reactants. The physicians initiated antibiotic therapy (for 1-3 days) in 12 cases (27.9%) based on acute phase reactant findings who actually had an RSV infection. When the physicians learned that the laboratory confirmed RSV infection, they stopped antibiotic therapy. Antibiotics were continued in 16 (37.2%) other RSV infected infants, all of whom were less than 2 months old, due to mixed pneumonia (viral and bacterial). 39.4% of RSV-infected children whose clinical findings strongly suggested RSV received no antibiotics. None of these children or other ALRI patients with a viral disease suffered complications. They required less hospitalization time--since no further diagnostic tests were needed--than ALRI patients with a bacterial infection. Admissions for both ALRI and RSV infection peaked during November to January. RSV incidence peaked in January (23.3%). The leading reasons for hospitalization were pneumonia and bronchiolitis. These findings show that RSV diagnosis is useful and it lessens the indiscriminate use of antibiotics.^ieng

Environmental pollution and malignant lymphomas: a tentative contribution to geographic pathology.

The present study reports of the geographic distribution of 2,878 cases of uniformly classified malignant lymphomas and of 2,349 similar cases from the literature. Data on histological entities are compared with the geographic and socio-economic characteristics of the regions where they preferentially occur. The results provide three patterns in lymphoma distribution: small cell lymphocytic lymphomas are frequent among populations of European extraction and in farming rather than industrial regions. Lymphomas derived from cells of the germinal center are seen preferentially in so-called "underdeveloped countries", and large cell (immunoblastic) lymphomas appear rather characteristic of industrial areas. Besides genetic influences (rare chronic lymphocytic leukemia (CLL) in Asia as compared to Europe), the results suggest environmental cofactors in the pathogenesis of malignant lymphomas. CLL is more frequent in areas with rather low-dose chronic toxic influences such as from the use of fertilizers and pesticides in farming. Germinal center cell lymphomas tend to occur more frequently in countries with nutritional and hygienic deficiencies with frequent infectious diseases. Large cell high malignancy lymphomas apparently prefer highly industrialized regions with pollution of water supplies by more toxic and immunosuppressive substances.

Experimental murine paracoccidiodomycosis induced by the inhalation of conidia.

Adult BALB/c mice of both sexes were infected intranasally with 10(6) viable P. brasiliensis conidia. Animals were sacrificed at intervals up to 6 months and studied by histopathology and organ cultures. At the time of challenge lung sections showed that instilled conidia had reached the alveoli; at 12 h such conidia were transforming into yeast cells, with multiple buds appearing by 18 h. Initially, the cellular infiltrate was composed of polymorphonuclear leukocytes; 6 days later, lymphocytes, plasmocytes and macrophages predominated. Multinucleated giant cells appeared only after 6 weeks. The rate of pulmonary infection as determined by organ culture was high (82 of the 83 mice studied). The experimental infection was progressive as indicated by increasing numbers of viable fungi with time. The results of this study demonstrate that the conidia produced by P. brasiliensis mycelial form are infectious, producing active disease in healthy animals.

Pathogenesis of paracoccidioidomycosis: a histopathological study of the experimental murine infection.

The pathogenesis of primary pulmonary P. brasiliensis infection, the systemic dissemination which followed, and the histopathology of the main organs involved was studied in a murine model of chronic paracoccidioidomycosis. Adult male BALB/C mice, were challenged intranasally with 26 X 10(-6) viable P. brasiliensis yeast cells. We inoculated 86 animals which were sacrificed from 0 h to 20 weeks. As controls, 11 mice were instilled with saline solution, and 48 with 26 X 10(-6) heat-killed. P. brasiliensis yeast cells. None of the animals receiving saline, exhibited pathologic alterations; 11.6% of those inoculated with the heat-killed cells, revealed mild, transitory acino-pulmonary neutrophilic infiltrates. The animals infected with viable cells, developed a systemic process affecting mainly the lungs (46.5%), liver (18.6%), lymph-nodes (18.6%), and spleen (3.5%). In this group of animals, lung lesions were detected regularly at all time periods from 3 h to 20 weeks. A multiple bronchopneumonic process was initially observed at 6 h, reached its maximum intensity around the third day, subsided thereafter but did not disappear and reactivated after the fifth week to become stationary until the end of experiments. Dissemination to other organs occurred early, and apparently by the hematogenous route. Initially the inflammatory cell infiltrate was mainly neutrophilic. With time, these cells were gradually replaced by lymphocytes, histiocytes and plasmocytes. Granuloma configuration of the cell infiltrate was distinctly seen around the fifth week, with multinucleated giant cells appearing at the ninth week. Hiliary lymph-node involvement was rare (7%) and primary lung lesions, as seen in tuberculosis and histoplasmosis, were not observed.

A new working formulation of non-Hodgkin's lymphomas. A retrospective study of the new NCI classification proposal in comparison to the Rappaport and Kiel classifications.

Two hundred thirty cases of malignant non-Hodgkin's lymphomas were reclassified in a retrospective study according to the New Working Formulation for Clinical Usage of the NCI as compared to the Rappaport and Kiel classifications. The reproducibility for the individual schemes this study was 81% (Rappaport), 79% (Kiel), and 85% (New Working Formulation). In keeping with the results of the NCI international study, all lymphomas were subdivided into 3 prognostic groups: (1) low-grade malignancy (6.0 years median survival); (2) intermediate-grade malignancy (3.5 years median survival); and (3) high-grade malignancy (1.4 years median survival). The NCI-proposed New Working Formulation for Clinical Usage is thus recommended as practical and unprejudicing classification scheme for general application; however, its usefulness as tool for translating one classification scheme into another appears limited.

Recovery of Paracoccidioides brasiliensis from a partially calcified lymph node lesion by microaerophilic incubation of liquid media.

Surgical specimens were obtained from a patient who had had life-threatening paracoccidioidomycosis 5 years previously. Residual lesions were found in the mesenteric lymph nodes; there were areas of caseous necrosis separated from the surrounding tissue by a fibrous capsule made of connective tissue. Abundant P. brasiliensis cells, many of which appeared degenerated, were observed in the necrotic material. Primary isolation was possible only under the microaerophilic conditions offered by fluid media kept stationary at 36 degrees C. Cultures in solid media were obtained after serial passages and gradual accommodation of the strain to aerobic incubation. It is apparent that P. brasiliensis yeast cells can become accustomed to reduced oxygen tension in the tissues. In this way, they are able to withstand the passing of time without completely losing their viability.

Entomoftoramicosis nasofacial (Rinoficomicosis). Estudio clinicopatologico de un segundo caso colombiano. / Nasofacial entomophthoramycosis. (Rhinophycomycosis). Clinicopathological study of a second Colombian case

Las enfermedades humanas causadas por Zigomicetos (Ficomicetos) pueden dividirse en dos grupos, las Mucormicosis y las Entomoftoramicosis. La Mucormicosis es causada por hongos del orden Mucorales y se observa en condiciones de bajas defensas del huesped. La Entomoftoramicosis, causada por hongos del orden Entomoftorales incluye la variedad Basidiobola, causada por el Basidiobolus haptosporus y la Conidiabolae cuyo agente es el Conidiobolus (Entomophthora) coronatus; a diferencia de los Mucorales este grupo puede afectar a pacientes sanos. Se presenta un segundo caso colombiano de Entomoftoramicosis naso-facial (Rinoficomicosis) observada en un paciente moreno de 36 anos procedente del Choco, lugar de procedencia del primer caso observado en el pais y cuyos aspectos clinicos e histopatologicos se resumen brevemente

Ultrastructural studies on hydantoin induced lymphomas in mice.

Ultrastructural studies were done on cells from original tumors and from short time cultures of mouse thymic lymphomas experimentally induced by chronic exposure to diphenyl-hydantoin. The tumors appeared in mouse strains with low (C57Bl) and high (SJL/J) susceptibility to spontaneous lymphoma development and were not observed in a resistant strain (C3Hf). Thymic lymphoma development was usually preceded by increasing lymphoreticular atrophy followed by progressive reticulohistiocytic hyperplasia, and subsequently spread to other tissues. Morphologically the tumor was characterized as a lymphoblastic lymphoma. Abnormal cell changes in the original tumors and cultured cells, and the presence of murine C-type particles in the cultured cells but not in the original tumors, are discussed in relation with the disturbance of immune system and the lymphoma enhancement produced by diphenyl-hydantoin.

Hodgkin's disease in Medellin, Colombia.

Four hundred and fifty two cases of Hodgkin's disease (H.D.) were studied in Medellin, Colombia, following the Rye histological classification: The relative frequency of H.D. was 2.3% for all malignancies and 34% for the solid lymphoreticular tumors. The percentage of H.D. in children as compared with adults was 27%, which is higher than usually reported. The age curve of incidence was bimodal with a first high peak at age 5--9 years and a lower second peak between 15--25 years. Males predominated mainly in children, 4.5--1. The epidemiological pattern for H.D. in our area generally corresponded with the Type I recently described for developing countries; but a high frequency for Nodular Sclerosis in children, with unusual anatomical localizations, more severe clinical manifestations, and poorer prognosis seems to indicate complex factors in the etiopathogenesis of the disease in the same geographical area.