Decreased expression of surfactant Protein-C and CD74 in alveolar epithelial cells during influenza virus A(H1N1)pdm09 and H3N2 infection.

The primary replication site of Influenza A virus (IAV) is type II alveolar epithelial cells (AECII), which are central to normal lung function and present important immune functions. Surfactant components are synthesized primarily by AECII, which play a crucial role in host defense against infection. The aim of this study was to analyze if the impact of influenza infection is differential between A(H1N1)pdm09 and A/Victoria/3/75 (H3N2) on costimulatory molecules and ProSP-C expression in AECII from BALB/c mice infected and A549 cell line infected with both strains. Pandemic A(H1N1)pdm09 and A/Victoria/3/75 (H3N2) were used to infect BALB/c mice and the A549 cell line. We evaluated the surface expression of co-stimulatory molecules (CD45/CD31/CD74/ProSP-C) in AECII and A549 cell lines. Our results showed a significant decrease in ProSP-C+ CD31- CD45- and CD74+ CD31- CD45- expression in AECII and A549 cell line with the virus strain A(H1N1)pdm09 versus A/Victoria/3/75 (H3N2) and controls (non-infection conditions). Our findings indicate that changes in the expression of ProSP-C in AECII and A549 cell lines in infection conditions could result in dysfunction leading to decreased lung compliance, increased work of breathing and increased susceptibility to injury.

First Evidence of Akodon-Borne Orthohantavirus in Northeastern Argentina.

Orthohantaviruses (genus Orthohantavirus, family Hantaviridae) are the etiologic agents of Hantavirus Pulmonary Syndrome in the Americas. In South America, orthohantaviruses are highly diverse and are hosted by sigmodontine rodents (subfamiliy Sigmodontinae, family Cricetidae), an also diverse group of rodents. The aims of this work were to (1) identify orthohantavirus hosts and (2) to study the spatial and temporal variations in the prevalence of infection and their associations with community, environmental and individual characteristics, in different environments of Misiones province, northeastern Argentina. Live-capture sessions were carried out during two years in different land uses, with a trapping effort of 31,653 trap nights. We captured 719 individuals from the species Akodon montensis, Rattus rattus, Mus musculus, Calomys tener, Thaptomys nigrita, Oligoryzomys nigripes, Euryoryzomys russatus, Oligoryzomys flavescens, Brucepattersonius sp., and Juliomys pictipes. Antibodies against orthohantavirus were detected in Akodon montensis in one natural protected and one periurban areas, and it was the most abundant species in almost every study sites. We observed the presence of spatial focality of orthohantavirus infection and a positive association with host abundance suggesting the existence of a threshold density. At the individual level, large, reproductively active, and male individuals were more likely to have antibodies against orthohantavirus. This is the first record of orthohantavirus infection in A. montensis in Argentina, which shows the importance of investigations about emerging diseases.

[Hantavirus pulmonary syndrome in Buenos Aires Province]. / Sindrome pulmonar por hantavirus en la Provincia de Buenos Aires.

In Argentina the first Hantavirus Pulmonary Syndrome (HPS) cases were characterized in 1995. Since then, Argentina is the country with the highest number of notified cases in South America. The disease is distributed in Northern, Southern and Central regions of the country, being Buenos Aires the most affected province from the Central region. In this study, we present seasonal and geographical distribution of HPS cases in Buenos Aires province, the association with diverse viral lineages and the serological characteristics of hantavirus infection in the period from 1997 up to the first semester of the year 2000. An increase in the number of HPS cases was observed up to 1999 and a gradual mortality decrease in the whole period. The cases occurred between spring and autumn, with a maximum peak in summer. The serological response was studied in 58 HPS confirmed cases at different times after the onset of symptoms. The cases were distributed between 27 localities, in two different directions from the city of Buenos Aires: South-southwest and North-northeast. More than 52% of the cases occurred in La Plata and neighboring localities. The viral genomes from 39 cases were all characterised as Andes virus (AND): AND Cent Plata 16%; AND Cent 21% and AND Cent Bs.As. 60%. Andes virus lineages only cocirculated in La Plata city. These results will contribute to establish a risk map leading to the implementation of improved strategies of prevention.

Sindrome pulmonar por hantavirus en la Provincia de Buenos Aires. / [Hantavirus pulmonary syndrome in Buenos Aires Province]

In Argentina the first Hantavirus Pulmonary Syndrome (HPS) cases were characterized in 1995. Since then, Argentina is the country with the highest number of notified cases in South America. The disease is distributed in Northern, Southern and Central regions of the country, being Buenos Aires the most affected province from the Central region. In this study, we present seasonal and geographical distribution of HPS cases in Buenos Aires province, the association with diverse viral lineages and the serological characteristics of hantavirus infection in the period from 1997 up to the first semester of the year 2000. An increase in the number of HPS cases was observed up to 1999 and a gradual mortality decrease in the whole period. The cases occurred between spring and autumn, with a maximum peak in summer. The serological response was studied in 58 HPS confirmed cases at different times after the onset of symptoms. The cases were distributed between 27 localities, in two different directions from the city of Buenos Aires: South-southwest and North-northeast. More than 52

of the cases occurred in La Plata and neighboring localities. The viral genomes from 39 cases were all characterised as Andes virus (AND): AND Cent Plata 16

; AND Cent 21

and AND Cent Bs.As. 60

. Andes virus lineages only cocirculated in La Plata city. These results will contribute to establish a risk map leading to the implementation of improved strategies of prevention.

Genetic diversity, distribution, and serological features of hantavirus infection in five countries in South America.

Since 1995 when the first case of hantavirus pulmonary syndrome (HPS) was reported in Patagonia, there have been more than 400 cases of HPS reported in five countries in South America. The first case of HPS was associated with Andes (AND) virus. In this study, we report on the genetic diversity, geographical distribution, and serological features of hantavirus infection in six countries in South America based on 87 HPS cases from Argentina, Bolivia, Chile, Paraguay, and Uruguay. An early immunoglobulin M (IgM), IgA, and IgG humoral response was observed in almost all HPS cases. The IgM response appears to peak 1 or 2 days after the onset of symptoms. Peak IgG antibody titers occur mostly after the first week. Low IgG titers or the absence of IgG was associated with higher mortality rates. The IgA response peaks around day 15 and then rapidly decreases. The results of phylogenetic analysis based on partial M-fragment G1- and G2-encoding sequences showed that HPS cases from the five countries were infected with viruses related to AND or Laguna Negra (LN) virus. Within AND virus-infected persons, at least five major genetic lineages were found; one lineage was detected in Uruguayan and Argentinean cases from both sides of the Rio de la Plata river. Two Paraguayan patients were infected with a virus different from LN virus. According to the results of phylogenetic analyses, this virus probably belongs to a distinct lineage related more closely to the AND virus than to the LN virus, suggesting that there is probably an Oligoryzomys-borne viral variant circulating in Paraguay. These studies may contribute to a better understanding of hantavirus human infection in South America.

Atomic-absorption spectrometric determination of calcium, magnesium and potassium in leaf samples after decomposition with molten sodium hydroxide.

The decomposition of standard leaf samples of varied origin and nature by fusion with sodium hydroxide in an open system has been studied. The use of sodium nitrate as an auxiliary agent facilitated the mineralization of most of the samples. The solutions obtained were analysed for calcium, magnesium and potassium by flame atomic-absorption spectrometry. The method is fast and quite precise, with absolute standard deviations of 0.04-0.13, 0.002-0.03 and 0.04-0.12% for calcium, magnesium and potassium contents of O.8-5.0, 0.13-0.48 and 0.36-2.2% respectively. The limits of detection (mug/ml) in the determination step were 0.10 for calcium, 0.011 for magnesium, and 0.09 for potassium.

Quantitative approximation for the selectivity of analytical spectrophotometric procedures with systems which do not obey Beer's law.

A selectivity index is proposed for defining the selectivity of a spectrophotometric procedure that is subject to interference by species which do not obey Beer's law in the system. The interactions between analyte and interferents which affect the absorbance of an analytical system are studied by means of a simple mathematical model. Theoretical expressions are derived which represent the selectivity as a function of the analyte or interfering species concentration. The treatment is illustrated by a study of the Zr(IV)-chloranilic acid system in presence of thorium as interferent.

Spectrophotometric determination of fluoride in fluoride-bearing minerals after decomposition by fusion with sodium hydroxide.

The decomposition of highly insoluble minerals (fluorspar and cryolite) by fusion with molten alkali-metal hydroxides is studied. The introduction of additives such as aluminium compounds or sodium peroxide to obtain total liberation of fluoride from calcium fluoride samples, is tested. The fusion is done in a silver crucible with a Bunsen burner. The cooled melt is easily soluble, giving solutions suitable for spectrophotometric fluoride determination by the Zr(IV)-fluoride-Erichrome Cyanine R method.

Determination of phosphorus in samples of vegetable origin Mineralization with molten alkali and spectrophotometric determination.

For determination of phosphorus in samples of vegetable origin (leaves and wheat flour) decomposition by means of molten alkali is proposed. Two procedures have been studied, one with dry reagents including an auxiliary oxidant, and the other with initially moist alkali with no extra oxidant. The fusion product is easily soluble and produces a solution suitable for elemental analysis. The phosphorus is determined by the molybdenum blue method. The suggested mineralization is rapid, accurate and precise.

Polarographic determination of proguanil and chlorhexidine.

The method is based on the cathodic wave obtained for chlorhexidine and proguanil in buffered aqueous dimethylformamide media. Concentrations up to 8 x 10(-5) and 6 x 10(-4)M, respectively, can be determined. The difference in behaviour at various pH values or in the presence of surface-active agents, is useful for characterization of both biguanides.