High prevalence of MMTV-like env gene sequences in gestational breast cancer.

Gestational breast cancer (BC) is generally associated with rapid growth and increased mortality. Because the presence of MMTV-like sequences in BC has been associated with laminin receptor expression, a marker of poor prognosis, gestational BCs were analyzed for MMTV env gene-like sequences to explore whether MMTV-like sequences were also associated with its adverse outcome. Whereas 30-38% of sporadic BC have the sequences, in gestational BC the prevalence is 62%. We suggest that hormonal response elements present in the MMTV-like LTR may play a role in promoting cell growth, as they do in the mouse system.

Reconstructing population history using JC virus: Amerinds, Spanish, and Africans in the ancestry of modern Puerto Ricans.

The roots of the Hispanic populations of the Caribbean Islands and Central and South America go back to three continents of the Old World. In Puerto Rico major genetic contributions have come from (1) Asians in the form of the aboriginal Taino population, an Arawak tribe, present when Columbus arrived on the Island, (2) Europeans, largely Spanish explorers, settlers, government administrators, and soldiers, and (3) Africans who came as part of the slave trade. Since JC virus (JCV) genotypes characteristic of Asia, Europe, and Africa have been identified, and excretion of JCV in urine has been proposed as a marker for human migrations, we sought to characterize the JCV strains present in a Caribbean Hispanic population. We found that the strains of JCV present today in Puerto Rico are those derived from the Old World populations represented there: Types 1B and 4 from Spain, Types 3A, 3B, and 6 from Africa, and Type 2A from Asia. The Type 2A genotype represents the indigenous Taino people. This JCV genotype was represented much more frequently (61%) than would be predicted by the trihybrid model of genetic admixture. This might be attributable to characteristics of JCV Type 2A itself, as well as to the nature of the early relationships between Spanish men and native women. These findings indicate that the JCV strains carried by the Taino Indians can be found in today's Puerto Rican population despite the apparent demise of these people more than two centuries ago. Therefore, molecular characterization of JCV provides a tool to supplement genetic techniques for reconstructing population histories including admixed populations.

Promoter activity of the rat connexin 43 gene in NRK cells.

Cellular communication mediated by gap junctions plays a major role in organ function. Gap junction channels are formed by the organization of polypeptide subunits, termed connexins (Cx), on the cell surface of adjacent cells. One mechanism to regulate gap-junctional communication is by change in Cx expression. In the present study, the promoter region of the rat Cx43 gene was characterized. Nested deletions of the 5' flanking region of the first Cx43 exon were coupled to the human growth hormone gene and transfected into normal rat kidney (NRK) cells, that express this gene constitutively. The minimal region of the Cx43 gene that showed maximal promoter activity was localized within 110 bp upstream of the transcriptional initiation site. One particular subregion that contains a Sp-1 binding site (located within 98--93 bp from the transcriptional initiation site) was found to sustain Cx43 promoter activity to the same extent as that of the 110 bp promoter region. Mutations of this Sp-1 binding site abolished transcriptional activity and DNA-protein interactions. These observations suggest that the Sp-1 binding site plays a major role in the basal transcriptional activity of Cx43 gene in NRK cells.

JC virus as a marker of human migration to the Americas.

JC virus is a ubiquitous human polyomavirus present in populations worldwide. Seven genotypes differing in DNA sequence by approximately 1-3% characterize three Old World population groups (African, European and Asian) as well as Oceania. It is possible to follow Old World populations into the New World by the JC virus genotypes they carried. The first population to settle in the Americas, the Native Americans, brought with them type 2A from northeast Asia. European settlers arriving after Columbus carried primarily type 1 and type 4. Africans brought by the slave trade carried type 3 and type 6.

Characterization of an outbreak of tetM-containing Neisseria gonorrhoeae in Argentina.

Phenotypic and molecular characterization of an outbreak of 9 Neisseria gonorrhoeae (NG) isolates exhibiting high-level plasmid mediated resistance to penicillin and tetracycline (PP-TRNG) that took place in Tandil, Argentina between February and April 1995. Comparison with the patterns of the 3 PP-TRNG strains previously isolated were made. We determined the following markers for each strain: antimicrobial susceptibility, serogroup, auxotype, plasmid profile, presence of tetM determinant and restriction pattern of the tetM-containing plasmid. Antimicrobial tests values were: tetracycline disk diameter 12-14 mm, minimum inhibitory concentration (MIC) 32 micrograms/ml; penicillin disk diameter 6 mm, MIC 32 micrograms/ml and sensitive by both methods to spectinomycin, cefuroxime, ceftriaxone and ciprofloxacin. All isolates were of the same serogroup (WI). Ten of the strains, including the 9 from Tandil outbreak, were arginine-requiring, while the other 2 were methionine and arginine-requiring. All of them demonstrate the same plasmid profile (2.6, 3.2, 25.2 MDa). They were positive for the tetM determinant and the restriction analysis identified it is a Dutch-type plasmid. In spite of the temporal and geographical dispersion, PP-TRNG strains in Argentina seem to be highly homogeneous in terms of antimicrobial susceptibility, serogroup, plasmid profiles and even auxotype.

PIP: This study determines the phenotypic and molecular characterization of an outbreak of 9 Neisseria gonorrhea isolates exhibiting high-level plasmid-mediated resistance to penicillin and tetracycline (PP-TRNG) that took place in Tandil, Argentina. Subjects included patients attending Tandil's Sanatamarina Hospital. Individuals infected with sexually transmitted disease were examined using a standardized questionnaire. Results show that all isolates produced B-lactamase, were penicillin resistant (disk zone diameter 6 mm, MIC 32 mcg/ml) and high-level tetracycline resistant (disk zone diameter 12-14 mm, MIC 32 mcg/ml). Moreover, all strains were fully sensitive to cefuroxime, ceftriaxone, ciprofloxacin, and spectinomycin; while autotype and serogroup results showed that all the strains were arginine-requiring and of serogroup WI. In spite of the temporal and geographical dispersion, PP-TRNG strains in Argentina seem to be highly homogeneous in terms of antimicrobial susceptibility, serogroup, plasmid profiles, and even auxotype.

Downregulation of connexin 43 gene expression in rat heart during inflammation. The role of tumour necrosis factor.

Gap junctions form channels that mediate the communication between adjacent cells. Alterations in gap junction function and/or expression are believed to contribute to cardiac dysfunction such as those observed in septic patients. The expression of connexin 43 (Cx43), the subunit component of the most abundant cardiac gap junction, was analysed in rat heart during inflammation induced by the administration of bacterial lipopolysaccharide (LPS). Cx43 mRNA levels were found to be dramatically (>50%) and rapidly (2 h) reduced in the heart after injection of LPS (1 mg/kg). To investigate the possible mechanism of the decrease in Cx43 expression during inflammation, the promoter region of this gene was cloned. The basal Cx43 promoter activity was observed within 224-134 bp of the transcriptional initiation site after transfection into a rat myoblast cell-line (H9c2). The Cx43 promoter activity was found to be reduced by incubation of the transfected cells with serum obtained from LPS-treated rats. Moreover, Cx43 promoter activity was also decreased upon incubation with tumour necrosis factor alpha. These results suggest that Cx43 expression in the heart can be modulated by circulating cytokines. These observations may have important implications in the depression of heart function observed in septic patients.

Expression of the connexin 43 gene is increased in the kidneys and the lungs of rats injected with bacterial lipopolysaccharide.

At the molecular level, the inflammatory response is characterized by changes in gene expression of various organ systems. One gene by which expression has been observed to be altered in the liver during inflammation is connexin (Cx) 32. Cx genes encode the polypeptide subunits of the hemichannels that comprise gap junctions. In the present study, an increase in the expression of a different Cx gene, Cx43, was observed in the kidney and lung of rats injected with a sublethal dose (1 mg/kg) of bacterial lipolysaccharide (LPS). To elucidate the possible mechanism by which the Cx43 expression is increased during inflammation, the 5' flanking region of the gene was cloned and coupled to a reporter gene (human growth hormone). This construct was transfected into cells of renal origin (NRK), which express Cx43 constitutively. The Cx43 promoter activity was indeed found in the cloned region, which contained 725 base pairs upstream of the transcriptional initiation site of the Cx43 gene. The Cx43 promoter activity was found to be increased by incubation of the transfected cells with serum obtained from LPS-treated rats. Moreover, direct incubation of the transfected cells with LPS or interleukin 1beta, but not with other cytokines, was observed to increase the Cx43 promoter activity. These results suggest the expression of Cx43 after administration of LPS is part of the inflammatory response. Moreover, the expression of this gene seems to be mediated by proinflammatory mediators.

[Characterization of isolated adenovirus associated with acute lower respiratory infection in pediatrics]. / Caracterización de aislamientos de adenovirus asociados a infección respiratoria aguda baja en pediatría.

BACKGROUND: Acute respiratory infection (ARI) are a health care problem as the adenovirus (ADV) has shown to be one of the most frequent viral agents detected in children admitted for mild ARI in the authors medium. METHODS: Over a 7-year period (1988-1994) ADV isolated from patients under the age of 5, admitted for mild ARI in hospitals in the city of Buenos Aires (Argentina). All the strains were isolated in HEp-2 cell cultures from nasopharyngeal aspirates in which the presence of ADV was detected by indirect immunofluorescence with monoclonal antibodies. Antigenic characterization was performed by sero- and genome neutralization with restriction enzymes. RESULTS: The isolates corresponded to the genomic variants of ADV 7i, ADV 7c and to a greater number of ADV 7h. An increase was observed in the quantity of cases in the second half of the year. In the population studied, the most commonly infected were males (67.9%) and patients from 2 months to 1 year in age (89.2%). Sixty-six percent of the cases were severe infections with the length of hospitalization being greater than that of patients normally admitted for mild ARI by other virus and showed a high mortality. CONCLUSIONS: All the above events suggest that the genomic variants detected are highly pathogenic.

Primer informe en la República Argentina de resistencia a penicilina en Neisseria gonorrhoeae mediada por el plásmido de 3,2 MDal (africano) / First report in Argentine of resistance to penicillin in Neisseria gonorrhoeae madiated by the 3,2 MDal African plasmid

En la República Argentina, Buenos Aires (INM), detectamos la primer cepa productora de ß-lactamasa en 1980, incrementándose la prevalencia de estas cepas resistentes de 1,9 por ciento (1980-1984) a 30 por ciento (1984-1988) y a 37 por ciento (1989-1991). El objetivo de este trabajo es la caracterización de los plásmidos responsables de esta resistencia, en un estudio retrospectivo que abarca de 1985 a 1991. Se estudiaron 28 cepas de Neisseria gonorrhoeae productoras de penicilinasa (PPNG), enviadas para su estudio o aisladas en nuestro Servicio de exudados genitales. El 100 por ciento de las cepas presentó el plásmido críptico de 2,6 MDal. El plásmido de 3,2 MDal se encontró en 13 cepas (46,4 por ciento) y en el 92,3 por ciento de ellas acompañado por el de 24,4 MDal. En 15 cepas (53,60 por ciento) se detectó la presencia del plásmido de 4,4 MDal, sólo en 9 de ellas (60 por ciento) junto con el plásmido conjugativo. Este es el primer informe sobre la presencia del plásmido de 3,2 MDal (africano) en las cepas PPNG aisladas en la Argentina. Nuestro primer hallazgo de este plásmido data de 1988

Primer informe en la República Argentina de resistencia a penicilina en Neisseria gonorrhoeae mediada por el plásmido de 3,2 MDal (africano) / First report in Argentine of resistance to penicillin in Neisseria gonorrhoeae madiated by the 3,2 MDal African plasmid

En la República Argentina, Buenos Aires (INM), detectamos la primer cepa productora de ß-lactamasa en 1980, incrementándose la prevalencia de estas cepas resistentes de 1,9 por ciento (1980-1984) a 30 por ciento (1984-1988) y a 37 por ciento (1989-1991). El objetivo de este trabajo es la caracterización de los plásmidos responsables de esta resistencia, en un estudio retrospectivo que abarca de 1985 a 1991. Se estudiaron 28 cepas de Neisseria gonorrhoeae productoras de penicilinasa (PPNG), enviadas para su estudio o aisladas en nuestro Servicio de exudados genitales. El 100 por ciento de las cepas presentó el plásmido críptico de 2,6 MDal. El plásmido de 3,2 MDal se encontró en 13 cepas (46,4 por ciento) y en el 92,3 por ciento de ellas acompañado por el de 24,4 MDal. En 15 cepas (53,60 por ciento) se detectó la presencia del plásmido de 4,4 MDal, sólo en 9 de ellas (60 por ciento) junto con el plásmido conjugativo. Este es el primer informe sobre la presencia del plásmido de 3,2 MDal (africano) en las cepas PPNG aisladas en la Argentina. Nuestro primer hallazgo de este plásmido data de 1988 (AU)

[Detection of a new genomic variation of Adenovirus 7 associated to severe infections of the lower respiratory tract]. / Detección de una nueva variación genómica de Adenovirus 7 asociada a infecciones severas del tracto respiratorio inferior.

We report a new genomic variation of Adenovirus 7, associated to severe infections of the lower respiratory tract isolated during September 1990, from children under 3 years of age and living in Buenos Aires city. The restriction analysis with the BamHI, BglI, BglII and SmaI restriction endonucleases demonstrated that the new variation is highly related to the recently described Adenovirus 7h.

Detección de una nueva variación genómica de Adenovirus 7 asociada a infecciones severas del tracto respiratorio inferior. / [Detection of a new genomic variation of Adenovirus 7 associated to severe infections of the lower respiratory tract]

We report a new genomic variation of Adenovirus 7, associated to severe infections of the lower respiratory tract isolated during September 1990, from children under 3 years of age and living in Buenos Aires city. The restriction analysis with the BamHI, BglI, BglII and SmaI restriction endonucleases demonstrated that the new variation is highly related to the recently described Adenovirus 7h.

[Yersinia enterocolitica strains of bovine origin isolated in San Luis, Argentina: virulence, enterotoxigenicity, and antibiotic sensitivity]. / Cepas de Yersinia enterocolitica de origen bovino aisladas en San Luis, Argentina: virulencia, enterotoxigenicidad y sensibilidad a antibióticos.

Eleven Yersinia enterocolitica strains isolated from bovine tongues and classified as B1 0:5 Lis Xz (8), B2 0:9 Lis X3 (2), nontypable (1), were examined for the following virulence-associated characteristics: autoagglutination, calcium dependency, Sereny test, congo red binding and presence of 40-48 MDa plasmids. Heat-stable enterotoxin production was also determined. Antibiotic susceptibility was assayed according to the modified Bauer-Kirby's method. Two Y. enterocolitica B1 0:5 Lis Xz strains were positive for autoagglutination, calcium dependency and congo red binding; both exhibited nearly 40 MDa plasmids and one of them was enterotoxigenic. The other strains did not carry virulence-associated plasmids, 5 were congo red positive and 4 produced enterotoxin. Therefore, two B1 0:5 Lis Xz strains would be potentially virulent. All strains were susceptible to piperacillin, mezlocillin, cefuroxime, cefotaxime, amikacin, kanamycin, sisomicin, phosphomycin , chloramphenicol, trimethoprim-sulfamethoxazole and pipemidic acid. Ampicillin and sulfisoxazole proved to be less efficient.