[Isolation of lymphocytic choriomeningitis virus from human individuals]

The activity of lymphocytic choriomeningitis virus (LCMv) in Argentina has been previously reported on the basis of serological evidence in rodents and humans and the isolation of only one strain of LCMv from a Mus domesticus captured in the province of Córdoba. The aim of this paper was to register patients with serological diagnosis of LCM, to isolate and to identify human strains of LCMv in Argentina. During the last 19 years, 15 cases were diagnosed as LCM by immunoflourescent indirect assay (IFI) and enzyme-linked immunosorbent assay (ELISA) but when neutralizing assay (NT) was incorporated, eight cases were classified as confirmed, three as probable and four as negative. The geographic distribution of the cases included three provinces: Córdoba, Buenos Aires and Santa Fe. Viral isolation was attempted in five patients classified as confirmed and only two resulted positive (P5226 and P8573). They were identified as LCMv by IFI and NT. The coexistence of LCMv with other arenaviruses, such as Junin and Oliveros viruses, in the same area, raises the probability of interactions between them, which could modify the virulence and/or pathogenicity for humans associated to genomic changes. Future studies of antigenic, genomic and virulence variability of different Argentine strains of LCMv, as well as the systematic search for human infection, will contribute to define the importance of this viral agent in our country and to implement control measures.

Genetic diversity of the Junin virus in Argentina: geographic and temporal patterns

RNA was purified from 39 strains of cell-cultured Junin virus (JUN) from central Argentina, which included both human- and rodent-derived isolates (a total of 26 and 13, respectively), as well as from 2 laboratory JUN strains, XJ Cl3 and XJ #44. JUN-specific primers were used to amplify a 511-nucleotide (nt) fragment of the nucleocapsid protein gene and a 495-nt fragment of the glycoprotein 1 (GP1) gene. Genetic diversity among JUN strains studied was up to 13% at the nt level and up to 9% at the amino acid (aa) level for the GP1 gene and up to 9% (nt) and 4% (aa) for the NP gene. Phylogenetic analyses of both genes revealed three distinct clades. The first clade was composed of the JUN strains from the center of the endemic area and included the majority of JUN strains analyzed in the current study. The second clade contained 4 JUN strains isolated between 1963 and 1971 from Cordoba Province, the western-most edge of the known endemic area. The third clade contained 4 JUN strains that originated from Calomys musculinus trapped in Zarate, the northeastern edge of the known endemic area. Certain JUN sequences, which were obtained from GenBank and identified as XJ, XJ #44, and Candid #1 strains, appeared to form a separate clade. Over 400 nt of the GP1 and GP2 genes were additionally sequenced for 7 JUN strains derived from patients with different clinical presentations and outcomes of Argentine hemorrhagic fever. Analysis of the corresponding aa sequences did not allow us to attribute any particular genetic marker to the changing severity or clinical form of the human disease.

Hantavirus reservoir hosts associated with peridomestic habitats in Argentina

Five species of sigmodontine rodents have been identified in Argentina as the putative reservoirs of six circulating hantavirus genotypes. Two species of Oligoryzomys are associated with the genotypes causing hantavirus pulmonary syndrome, Oligoryzomys flavescens for Lechiguanas and O. longicaudatus for Andes and Oran genotypes. Reports of human cases of hantavirus pulmonary syndrome prompted rodent trapping (2,299 rodents of 32 species during 27,780 trap nights) at potential exposure sites in three disease-endemic areas. Antibody reactive to Sin Nombre virus was found in six species, including the known hantavirus reservoir species. Risk for peridomestic exposure to host species that carry recognized human pathogens was high in all three major disease-endemic areas.

Genetic diversity and epidemiology of hantaviruses in Argentina

Phylogenetic analysis of a 292-nucleotide (nt) fragment of the hantavirus M genome segment from 36 rodent and 13 human samples from three known foci of hantavirus infection in Argentina was conducted. A 1654-nt fragment of the M genome segment was analyzed for 1 representative of 7 genetically distinct hantavirus lineages identified. Additionally, the nt sequence of the complete M genome segments of Lechiguanas, Oran, and Hu39694 hantavirus genotypes was determined. nt sequence comparisons reveal that 7 hantavirus lineages from Argentina differ from each other by 11.5%-21.8% and from Sin Nombre, Bayou, and Black Creek Canal viruses by 23.8%-26.5%. Phylogenetic analyses demonstrate that they form a unique, separate branch within the clade containing other New World sigmodontine-borne hantaviruses. Most Oligoryzomys-borne hantavirus genotypes clearly map together. The Oligoryzomys-borne genotypes Lechiguanas, Oran, and Andes appear to be associated with human disease. Oligoryzomys longicaudatus was identified as the likely rodent reservoir for Andes virus.

Hantavirus infection in children in Argentina

Clinical hantavirus infection was diagnosed in five Argentine children ages 5 to 11 years by immunoglobulin M (IgM)- capture enzyme-linked immunosorbent assay using Sin Nombre virus (SNV) antigens. Death in three of the children was associated with absence of detectable IgG to SNV antigens. An additional two cases in healthy children were studied: one, a breast-fed 15-month-old whose mother died of suspected hantavirus pulmonary syndrome (HPS) 8 months previously, had hantavirus IgG (> 1:6400); a second, whose mother survived HPS during month three of pregnancy, apparently had maternal antibodies no longer detectable 1 year after birth.

Case report: adrenal myelolipoma--rationale for a noninvasive diagnosis

Myelolipomas are nonfunctioning, benign tumors of the adrenal gland composed of fat and normal bone marrow elements in varying proportions. Although rare, they should be included in the differential diagnosis of the incidentally discovered adrenal mass. The authors describe a patient with a myelolipoma diagnosed by characteristic radiological findings in whom the use of invasive procedures or surgical exploration was unnecessary.

Evaluation of the biological significance of leukocyte infiltration of the thyroid in Graves' disease

Graves' goiter size and gland function may be affected by interferon-gamma influencing actions of the thyroid-stimulating antibody. Goiter weight (n = 20), lymphocytic infiltration and class II antigen expression were assessed. The largest goiters, strikingly, has least infiltration but, overall, the looked-for negative correlation between goiter size and lymphocyte infiltration did not materialize. This was presumably due, in part, to inhibiting antibodies in many (8/18) patients' sera. In addition, our data do not support a major pathogenetic role for class II antigen in Graves' disease.

Determination of replacement and suppressive doses of thyroxine

Suppression daily doses of thyroxine (T4) were determined and the daily amounts of T4 required to replace T4 were established in 217 hypothyroid patients. Patients with Hashimoto's thyroiditis treated daily with 2-3 micrograms/kg lean body mass or 1-2 micrograms/kg body weight T4 had normal serum thyrotrophin (TSH) concentrations, normal response to TSH-releasing hormone (TRH) and normal systolic time intervals but doses higher than 3 micrograms/kg lean body mass or 2 micrograms/kg body weight decreased serum TSH concentrations, with no response to TRH and systolic time intervals typical of hyperthyroidism. In 13/32 (41%) hypothyroid patients with Graves' disease following 131I and/or surgery, the daily T4 replacement dose was similar to that in Hashimoto's thyroiditis patients but in 12 (38%) patients daily doses of 2-3 micrograms/kg lean body mass or 1-2 micrograms/kg body weight T4 increased serum T4 and suppressed TSH levels, and in six (9%) lower doses were required to control hypothyroidism. The T4 suppression dose for patients with thyroid cancer was more than 3 micrograms/kg lean body mass or 2 micrograms/kg body weight, whereas approximately 30% of non-toxic nodular goitre patients required less than 3 micrograms/kg lean body mass. It is concluded that replacement or suppression doses of T4 should be individually determined and that different criteria should be applied for their calculation depending on the thyroid abnormality.

Effects of gamma-interferon and tumor necrosis factor alpha on thyroid cells: induction of class II antigen and inhibition of growth stimulation

A functioning rat thyroid cell line (FRTL5) was used to study interactions of thyrotropin (TSH) and various cytokines on expression of class I and II major histocompatibility complex (MHC) antigens and on growth stimulation. Only gamma-interferon (gamma-IFN) affected MHC antigen expression, i.e., to enhance class I, that was constitutive, and to induce class II. A concomitant, but probably not directly related, effect of gamma-IFN was to diminish growth stimulation, as effected by TSH and other activators of adenylate cyclase and measured by DNA increase and enhanced incorporation of [3H]thymidine into DNA. Stimulation of growth by tetradecanoylphorbol ester was also decreased by gamma-IFN. These effects of gamma-IFN were mimicked to some degree by tumor necrosis factor but there was major synergism between the two cytokines. Enhanced accumulation of cAMP by TSH and other agents was not diminished in these experiments. Flow cytometry analysis showed that inhibition of growth stimulation involved blocking of the passage of cells from the G0/1 phase to the S phase. The data may have relevance to goiter size in autoimmune thyroid disease.

A study of the binding of Graves' immunoglobulins to orbital antigens

The binding of Graves' immunoglobulins to membranes of human eye muscle (HEM) and guinea pig Harderian gland (HG) were studied. The membrane fraction of 100,000 X g sediment was used for ELISA. Serum samples from 55 patients with Graves' ophthalmopathy were evaluated for binding to the membrane preparation. There was a higher binding to HG with the sera from the patients with Graves' ophthalmopathy than in the control group (p less than 0.01), but there was no difference in binding to HEM. Purification of IgG from sera improved binding to HG in both patients' (p less than 0.001) and control group (p less than 0.005). There was also an increase in percentage of positive responses obtained with IgG 48% vs serum samples 37%. In 23 out of 24 patients we found the thickening of extraocular muscles by A-scan ultrasonography. In these groups of patients and 3 others with malignant ophthalmopathy the binding of IgG preparation to HG was similar to control group. In all assays there was an overlap between patients with Graves' ophthalmopathy and control subjects, and a lack of relationship between the responses in ELISA and clinical or severity of ophthalmopathy.

Tolerance and antiviral effect of ribavirin in patients with Argentine hemorrhagic fever

Tolerance and antiviral effect of ribavirin was studied in 6 patients with Argentine hemorrhagic fever (AHF) of more than 8 days of evolution. Administration of ribavirin resulted in a neutralization of viremia and a drop of endogenous interferon titers. The average time of death was delayed. A reversible anemia was the only adverse effect observed. From these results, we conclude that ribavirin has an antiviral effect in advanced cases of AHF, and that anemia, the only secondary reaction observed, can be easily managed. The possible beneficial effect of ribavirin during the initial days of AHF is discussed.

[Odontogenesis in the human fetus: an echographic study]

During real-time ultrasound observation of swallowing movements in the human fetus, changes in the echostructure of the jaws were detected. Dense linear echoes (2-6 mm) arose symmetrically in the superior and inferior jaws from the median to the distal level with increasing gestational age. Their localisation and onset suggested they might represent tooth germs. The comparison between radiography after birth and pre- and postnatal echography confirmed that these particular echoes were indeed calcified tooth germs. The implications of this observation will be discussed in terms of fetal growth maturation and gestational age.

Nifurtimox-induced alterations in the cell-mediated immune response to PPD tin guinea-pigs

Positive skin reactions to PPD in guinea-pigs immunized with Freund's complete adjuvant (FCA) were reversed after treatment with 10 mg/kg/day nifurtimox for 12 days. The in vitro migration of peripheral blood leucocytes from FCA-immunized guinea-pigs was inhibited with PPD, but it returned to normal values after nifurtimox treatment. Furthermore, the cell-free supernatant from PPD-stimulated lymphocytes from FCA-immunized nifurtimox-treated guinea-pigs did not inhibit the migration of normal cells. Thus the administration of nifurtimox impaired the specific cell-mediated immune response to PPD both in vivo and in vitro.