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Biomedical subjects

G Carballal

Publications and source records attributed to G Carballal.

At least 19 recordsLinked to original sources
PubMed2006

Dynamics of a hepatitis B virus e antigen minus population ascribed to genotype F during the course of a chronic infection despite the presence of anti-HBs antibodies.

The in vivo evolution of genotype F HBV variants was recorded in a chronically infected patient throughout a 3-year observation period. Fluctuating levels of HBs Ag and anti-HBs antibodies were recorded, both of them cocirculating in peripheral blood samples at given times. Fifty S gene derived clones were sequenced and phylogenetically analyzed. As expected, some amino acid replacements within the S ORF were also observed within the P ORF while others were silent for the former. Such change was statistically significant for both S and P overlapping genes, which clearly indicates the appearance of a positive selection pressure. Supporting this notion, amino acid replacements were documented at both B and T cell epitopes in samples from 1997 and 1998. Several mutations were documented within and outside the "a" determinant in the major hydrophilic region. Such substitutions might have resulted from the attempt of HBV to evade both humoral and/or cellular immune response. To the best of our knowledge this unusual profile of HBV variants in presence of usually "neutralizing" anti-HBs antibodies was examined in vivo for the first time.

Amino Acid Sequence↗
PubMed2003

Hepatitis B virus S gene mutants in a patient with chronic active hepatitis with circulating Anti-HBs antibodies.

An adult male farmer with chronic active hepatitis and cirrhosis despite previous circulating anti-HBs antibodies was studied. No markers of other hepatotropic viral infection were observed. HBV DNA was detected in serum by PCR and was characterized further by restriction fragment length polymorphism (RFLP) and sequencing of cloned PCR products derived from the S gene. The HBV DNA was ascribed to genotype F, and single-strand conformational polymorphism (SSCP) demonstrated the co-circulation of multiple quasispecies. Some of the variants exhibited changes located within the neutralizing "a" determinant, located between amino acids 124-147 of the S protein. Within this region, two clones showed either C124R or C124Y mutations. Other mutations were Q129R, C138R, C139R, and S140T (one clone each). Outside the "a" determinant several substitutions were documented. The high degree of the quasispecies variability was probably linked to the severity of the infection. Most members of the patient's family were infected with HBV, all with genotype F.

Amino Acid Substitution↗
PubMed2003

Cyclic recovery of adenovirus in a stem cell transplant recipient: an inverse association with graft-versus-host disease.

Adenovirus (AdV) infections have been increasingly recognized as significant pathogens that may cause severe morbidity and mortality among stem cell transplant (SCT) recipients. AdV can cause localized infections such as hemorrhagic cystitis (HC), pneumonia, hepatitis and also disseminated disease that can lead to death. We report a case of severe hemorrhagic cystitis in a SCT recipient who died 83 days after transplant. In this patient, AdV recovery was not constantly detected. In fact, fluctuations of the AdV detection in leukocytes and urine were observed by culture and PCR. When analyzing this viral cyclic recovery with different signs or symptoms in the patient, we observed an inverse association with the presence of acute graft-versus-host disease (GVHD). Whether these fluctuations represent donor-derived reactivity, indirectly manifested by the presence of GVHD, requires further study. This is the first case describing a dynamic pattern of AdV replication in leukocytes and urine samples from a patient with severe HC and the temporal correlation with GVHD.

Adenoviruses, Human↗
PubMed2001

Multicentered study of viral acute lower respiratory infections in children from four cities of Argentina, 1993-1994.

This study describes the first multicentered study of acute lower respiratory infection viral etiology in young children from four different geographical areas of Argentina. A total of 1,278 children under 5 years of age, hospitalized in primary care centers from Buenos Aires, Córdoba, Santa Fé and Mar del Plata cities during a 2-year period were studied (1993-1994). Nasopharyngeal aspirates were investigated for respiratory syncytial virus (RSV), adenovirus, parainfluenza, and influenza A and B viruses by indirect immunofluorescence. Out of the patients studied, 946 (74%) were under 1 year of age. Viruses were detected in 399 patients (32%). RSV was observed in 25.3% of the samples, representing 78.2% of all viral positive cases. Adenoviruses were detected in 2.5% of the cases, parainfluenza in 2.2%, influenza A in 2.1%, and influenza B in 0.2%. Compared with other viruses, the higher RSV frequency was statistically significant (P < 0.000). Most RSV cases were detected between May and September with a significant peak in July (P < 0.000). Pneumonia was observed in 46% of the patients, bronchiolitis in 41% and other entities in 13%. The case fatality rate observed during the 2 year study was 0.73%. Most of the above respiratory viruses were detected in the four cities, however, the frequency of RSV and influenza were different in the southern city.

Acute Disease↗
PubMed2001

[Cytomegalovirus isolation by conventional cell culture and shell vial assay].

In immunocompromised patients, diagnosis of Cytomegalovirus (CMV) active infection is of utmost importance for the initiation, monitoring and ending of antiviral therapy. Therefore, the presence of viral replication should be demonstrated. Isolation in tissue culture is one of the standard methods. The objective of the present paper was to compare two isolation procedures for CMV: conventional cell culture (CC) and rapid shell vial (SV) assay in human fibroblasts. A total of 584 clinical samples were studied between 1991 and 1998. CMV was isolated in 14.4% of the samples, 11.8% of which were positive by SV and 7.7% by CC. Out of 84 positive samples, concordance between both methods was observed in 36% of the cases. We found that 46% of the samples were positive only by SV, while 18% were positive only by CC. The average time required for obtaining the results by CC was 22.6 +/- 2.3 days. Out of the 69 samples positive by SV, 43% were already positive after 24 hours and the rest after 48 hours. These results indicate that SV was more sensitive and rapid than CC. The main advantage of CC, despite its time-consuming process, is the ability to recover the viral strain for both antiviral susceptibility phenotypical tests and strain characterization. Furthermore, in this study, absence of CC would have resulted in the loss of 18% of the positive diagnoses. In conclusion, simultaneous use of both methods is suggested in order to obtain a rapid result and the highest sensitivity.

Cytomegalovirus↗
PubMed2000

Clinical and epidemiologic characteristics of respiratory syncytial virus subgroups A and B infections in Santa Fe, Argentina.

Respiratory Syncytial Virus (RSV) has two major antigenic groups, A and B. The implications of these variants in the epidemiology and pathogenesis of RSV infection are not well defined. This study was undertaken to compare the two RSV subgroups in patients admitted to hospital. Clinical and epidemiologic features of RSV subgroups in children under 30 months of age with proven RSV acute lower respiratory infections were examined during 4 winters from 1993 to 1996 in Santa Fe, Argentina. RSV typing was carried out with monoclonal antibodies in nasopharyngeal cells by indirect immunofluorescence. Of the 177 RSV positive nasopharyngeal aspirates obtained from 1993 to 1996, 85 (48%) were available for typing. Seventy-three (85.9%) specimens were identified as Subgroup A and 12 (14.1%) as Subgroup B. Except in 1993, in which only Subgroup A was detected, both variants circulated throughout the epidemic season. Subgroup A infections produced more severe disease than Subgroup B infections, as assessed by the length of the hospital stay and the use of respiratory support. This difference was age related, being evident in infants 0-6 months old. Patients with Subgroup B infections were also significantly less frequently breast-fed (95% vs. 75% for A and B subgroups, respectively; P = 0.04). It is concluded that the severity of disease in Argentinian patients admitted with acute RSV infections may be associated with Subgroup A strains as determined by a serogrouping method.

Antibodies, Monoclonal↗
PubMed2000

Respiratory syncytial virus: changes in prevalence of subgroups A and B among Argentinian children, 1990-1996.

The frequency of respiratory syncytial virus (RSV) and the distribution of subgroups A and B strains during 7 consecutive years (1990-1996) were examined in two cities of Argentina. Nasopharyngeal aspirates from 1,304 children less than 2 years of age hospitalized with acute lower respiratory infection were studied by indirect immunofluorescence. RSV was detected in 352 cases (26.9%), and the peak activity was observed in midwinter. Subgroup characterization was performed with two monoclonal antibodies against the F protein on nasopharyngeal aspirate smears. Of 195 samples, 174 (89.2%) were identified as subgroup A strains and 21 (10.8%) as subgroup B. Both strains cocirculated during 5 of 7 years studied with subgroup A predominating. Subgroup A occurred at least 8 times as often in all years except for 1994-1995. Children infected by subgroup A were younger than those infected by subgroup B (P < 0.05). The association of subgroup A infection with bronchiolitis and subgroup B with pneumonia was statistically significant (P < 0.03).

Antigens, Viral↗
PubMed2000

Genomic and phylogenetic analysis of hepatitis C virus isolates from argentine patients: a six-year retrospective study.

Typing of hepatitis C virus (HCV) isolates from Argentine patients was performed by using different methodologies in a population of 243 patients. HCV subtype was assigned based upon restriction fragment length polymorphism (RFLP). HCV RNA genomes obtained from serum samples were classified as belonging to clade 1 (53.5%), 2 (23. 0%), or 3 (8.6%); 14.8% of samples showed HCV mixed infections, more frequently implying different subtypes within the same clade. In addition to RFLP typing, phylogenetic relatedness among sequences from both 5' untranslated region (n = 50) and nonstructural 5B coding region (n = 15) was established.

5' Untranslated Regions↗
PubMed1999

Genetic diversity of GBV-C/HGV strains among HIV infected-IVDU and blood donors from Buenos Aires, Argentina.

GBV-C/HGV RNA was investigated in serum samples from 70 HIV(+) intravenous drug users (IVDU), as well as from 200 blood donors from Buenos Aires, Argentina. Viral RNA was demonstrated in 21 IVDU by reverse transcription-nested PCR of the 5' UTR. c-DNA amplified products were analyzed and their sequences compared with those downloaded from GenBank. A phylogenetic tree based on 171 sequences demonstrated the presence of three major genogroups, including two subgroups, within local samples, i.e. group 1 (n=1), 2a (n=11), 2b (n=4) and 3 (n=5). These results agreed entirely with those obtained by a novel RFLP (J. Clin. Microbiol. 37, 1340-1347, 1999) of the same 5' UTR amplicons. As expected, GBV-C/HGV RNA prevalence was significantly higher among IVDU than among blood donors (P<0.0001), although within the latter group an unexpectedly high rate was also detected, since 11 of 200 sera (5.5%) proved positive. These viral isolates were ascribed either to subgroup 2a (n=5), subgroup 2b (n=5) or genogroup 3 (n=1). Briefly, this partial view of GBV-C/HGV molecular epidemiology in Argentina shows: (i) different rates of GBV-C/HGV infection within both IVDU and blood donors; (ii) a high prevalence of viral RNA among blood donors; and (iii) a predominant circulation of genogroup 2, with minor contribution of groups 3 and 1.

Adult↗
PubMed1999

Genomic analysis of adenovirus isolated from Argentinian children with acute lower respiratory infections.

BACKGROUND: Adenoviruses are the second cause of acute lower respiratory infection (ALRI) of viral origin in small children from Buenos Aires, Argentina. OBJECTIVE: The aim of this study was to characterize, by restriction enzyme analysis, 17 adenovirus strains isolated from the nasopharyngeal aspirates of children under 2 years of age hospitalized due to ALRI. STUDY DESIGN: Seventeen adenovirus strains isolated between May 1991 and December 1992 in one hospital of Buenos Aires were studied. Adenoviruses were amplified in HEp-2 cells and viral DNA was studied with the restriction enzymes Bam HI and Sma I. RESULTS AND CONCLUSIONS: Eighty two percent (14/17) of the isolates were classified as adenoviruses from subgenus b and 17.7% (3/17) belonged to subgenus c. Genome type 7 h was detected in 85.7% (12/14) and 7 i in 14.3% (2/14) of the strains from subgenus b. The case lethality associated with adenovirus genome type 7 was 28.6% (4/14 cases). Three fatal cases corresponded to Ad 7 h and one to Ad 7i. Ad 7h shows a high prevalence in small children hospitalized with ALRI and is associated with a high fatality rate.

Adenoviruses, Human↗
PubMed1998

Acute lower respiratory infections due to respiratory syncytial virus and adenovirus among hospitalized children from Argentina.

BACKGROUND: Acute lower respiratory infection (ALRI) is one of the main causes of morbidity and mortality in small children. OBJECTIVE: The aim of this study was to determine the frequency, seasonality and association with clinical entities of respiratory syncytial virus (RSV) and adenoviruses in children with ALRI. STUDY DESIGN: During 2 consecutive years (1991-1992), 168 children under 2 years of age hospitalized due to ALRI in a public pediatric hospital of Buenos Aires, Argentina, were studied. RSV and adenoviruses were investigated on nasopharyngeal aspirates (NPA) by indirect immunofluorescence (IIF). HEp-2 cells were used for adenovirus isolation. RESULTS: RSV was detected in 36.3% and adenoviruses in 14.3% of the cases (P < 0.0001). All adenoviruses detected by IIF were also isolated in culture. Out of 61 RSV cases, 57% corresponded to bronchiolitis and 43% to pneumonia. Ninety-two per cent of children with RSV were less than 1 year old and 70% were less than 5 months. The highest number of RSV cases were observed during winter, with a clear peak in July. Seventy-one per cent of adenovirus cases were associated with pneumonia and only 24% with bronchiolitis (P < 0.02), and predominated in children older than 5 months of age (P < 0.0001). Adenoviruses were detected in almost all months of the year with a small peak at the end of winter and beginning of spring. No significant differences in clinical features at admission, breast feeding or malnutrition were observed among children with RSV or adenovirus diagnosis versus those with no viral etiology. The overall fatality rate was 2.4%. In all fatal cases adenovirus was detected in NPA. Thus, fatality rate among patients with adenoviruses reached 16.7%. CONCLUSIONS: Our findings show the importance of RSV and adenoviruses associated with ALRI in hospitalized children under 2 years of age and the different epidemiological patterns of the two viruses in Buenos Aires, Argentina.

Acute Disease↗
PubMed1994

[Chlamydia trachomatis and tubal obstruction sterility].

In order to determine the importance of Chlamydia trachomatis in infertility due to tubal occlusion, the prevalence of C. trachomatis antibody was studied in two populations of Argentine women, pregnant and infertile with tubal occlusion. IgG and IgM against C. trachomatis were determined by indirect immunofluorescence in McCoy cells infected with strain L2Bu434 of C. trachomatis. In infertile women, specific anti-C. trachomatis IgM was detected in 5 out of 32 (15.6%) and IgG in 20 out of 32 (75%). In pregnant women, specific IgM was detected in 4.8% (4/83) and IgG in 20.5% (17/83). The frequency of IgG detection was significantly higher in infertile than in pregnant women (p < 0.000). Thirteen out of 20 (65%) women who underwent laparoscopic examination had evidence of chronic inflammatory disease described as yellowish viscous cysts resembling "frog eggs" in Douglas, utero and/or perihepatitis. Twelve out of fourteen (86%) infertile women with positive serology for C. trachomatis presented one or more of these laparoscopic findings. C. trachomatis antigen was detected in 2 out of 10 tubal biopsies by direct immunofluorescence with monoclonal antibodies although isolation in McCoy cells was negative. Our results show the importance of C. trachomatis in infertility due to tubal occlusion and the need of C. trachomatis diagnosis in routine gynecologic analysis to prevent infertility and neonatal infection.

Adolescent↗
PubMed1992

Chlamydial antibodies in children with lower respiratory disease.

Forty-nine of 255 (19.2%) Argentinean children between the ages of 1 and 18 months without evidence of viral or bacterial infections, but with clinical and radiologic evidence of acute lower respiratory distress, had serologic evidence of recent Chlamydia trachomatis infection by the demonstration of specific IgM, seroconversion or 4-fold rise in titer or elevated titers by enzyme immunoassay and the microimmunofluorescence test. Recent C. trachomatis infection was detected in 28 of 166 (16.9%) of children with bronchiolitis and 18 of 89 (20.2%) with pneumonia. Three additional children with bronchiolitis had Chlamydia pneumoniae-specific antibody. There was a significantly higher prevalence of C. trachomatis infection in children living in La Plata city orphanage (26 of 74, 35.1%) than in those attending 2 pediatric hospitals in Buenos Aires (23 of 181, 12.7%) (P less than 0.001). C. trachomatis infection was detected in all age groups up to 18 months. Thirty of 49 infections were in children older than 3 months of age and 16 were in children older than 6 months. These results suggest that C. trachomatis infection may be associated with bronchiolitis and pneumonia in children between the ages of 1 and 18 months of age in Argentina and that a proportion may be horizontally transmitted.

Antibodies, Bacterial↗
PubMed1992

Prevalence of anti-cytomegalovirus antibodies in a children population of Buenos Aires.

The seroprevalence of anti-Cytomegalovirus antibodies in a selected children population was studied by an enzyme-immunoassay (ELISA) prepared in our laboratory. Sera from 207 children from middle socio-economic classes were studied. Children were divided into the following groups: Group 1: cord sera (n = 87); Group 2: children aged 13 months to 6 years (n = 54); Group 3: children aged 6-15 years (n = 66). Overall seroprevalence was 46.3%. The seropositivity and ELISA index titers for the three groups were, respectively: Group 1, 55%, mean = 2.16; Group 2, 90.7%, mean = 5.15; Group 3, 59%, mean = 2.49. Group 2 exhibited higher seropositivity (p < 0.0001) and higher index titers (p < 0.0001) than the other two groups. These results suggests that primoinfection with Cytomegalovirus in this population occurs in children aged 13 months to 6 years (Group 2). However, the high percentage (55%) of cord blood without anti-Cytomegalovirus antibodies suggests a risk for congenital infection or primary infection for those newborn who required blood transfusions or were fed with bank milk. Further studies are needed to determine the impact of Cytomegalovirus infections in populations from different socio-economic classes, in congenital infections, the prevalence of antibodies in blood banks and their frequency in immunocompromised patients.

Adolescent↗
PubMed1989

Calomys callidus as a potential Junin virus reservoir.

The present study investigated whether C. callidus, a species belonging to the Calomys genus, is capable of developing experimentally a persistent Junin virus (JV) infection. Newborn and adult cricetids were inoculated with the attenuated XJ-Clone 3 strain of JV by intracerebral or mucosal route. The present results indicate that the species is susceptible to JV infection, capable of shedding virus chronically through saliva and developing a persistent infection as shown by the detection of virus in brain tissue at 60 days post infection. These findings, and the fact that this cricetid shares its distribution areas with Calomys musculinus and Akodon azarae, support C. callidus as a potential JV reservoir.

Animals↗
PubMed1989

Formalin inactivated Junin virus: immunogenicity and protection assays.

The aim of this study was to determine if Junin virus inactivated with formalin (FA) was immunogenic and able to elicit a protective response in the guinea pig. The XJ-Clone 3 strain of Junin virus grown in Vero cells was exposed to FA at 0 degrees C. The following inactivated antigens were prepared: A1, 0.1% FA for 50 hr; A2, 0.1% FA for 50 hr followed by concentration with polyethylene glycol (PEG); B1, 0.05% FA for 70 hr; B2, 0.05% FA for 70 hr plus PEG concentration; C, 0.1% FA for 50 hr followed by ultracentrifugation and purification by sucrose gradient. No residual infectivity was detected in any inactivated antigen either after two passages in newborn mice or by coculture with Vero cells. After immunization, high-neutralizing and low-immunofluorescent antibody titers wer obtained in adult mice and guinea pigs, thus showing that antigenicity was preserved. However, in spite of the presence of neutralizing antibodies, guinea pigs gained no protection against challenge with the highly pathogenic XJ strain. These results suggest that antibody amount and/or quality may be inadequate; alternatively, mechanisms other than humoral immunity, such as cellular response, not elicited by inactivated antigens may be essential for protection against Junin virus.

Animals↗
PubMed1989

Viral etiology in acute lower respiratory infections in children from a closed community.

The aim of this study was to determine the viral agents associated with acute lower respiratory infections (ALRI) in young children. During a 2-yr period, 204 nasopharyngeal aspirates (NPA) from children under 4 yr of age living in an orphanage and exhibiting febrile ALRI were studied by both indirect immunofluorescence (IIF) and isolation in four cell lines. NPA cell smears as well as tissue culture cells exhibiting cytopathic effect (CPE) or hemadsorption were stained by IIF for respiratory syncytial virus (RSV), adenovirus, influenza A and B, and parainfluenza 1 and 3. Viral etiology was demonstrated in 21.2% of acute respiratory infection cases. The most frequently detected virus was RSV (53.5% of viral positive diagnoses), followed by unidentified viruses (18.6%), adenovirus (13.9%), influenza A (7%), and parainfluenza 3 (4.7%). The most common clinical entities were: bronchitis, 46.1%; pneumonia, 24%; bronchiolitis, 22%; and multifocal pneumonia, 8%. Malnourishment was found in 56% of children with ALRI, whereas 50% was found among total orphanage population. The 3 to 8-month-old age group accounted for half of all ALRI cases. Viral etiology was shown for 26.5% of patients with pneumonia, 22% with bronchitis, and 16% with bronchiolitis. RSV and adenovirus occurred in fall and winter, while parainfluenza 3 was detected in early spring. In the two fatal cases observed, histologic lesions were compatible with adenovirus infection, but this virus could be isolated from the lung in only one case.

Acute Disease↗