Abstract: Platelets llave serotonin (5-HT) uptake and storage mechanisms similar to those from neurons. In addition, they represent nearly 99% of blood 5-HT concentration. For these characteristics, platelets are considered useful biomarkers of the serotonergic synaptic neurotransmission, particularly in psychiatric disturbances such as depression. However, most studies which have evaluated platelet 5-HT concentrations in depression have not shown similar findings. It has been suggested that changes in plasma tryptophan (TRP) concentrations might modify 5-HT concentration in the brain, as well as in platelets. Likewise, decreased plasma concentrations of TRP have been found in depressed patients, and the selective 5-HT reuptake inhibitors (SSRIs) induce changes in platelet 5-HT concentration. Considering the controversy surrounding platelet 5-HT concentrations in depressed patients, and the fact that blood 5-HT and TRP have not been studied in the Mexican population, we decided to study 5-HT and tryptophan concentrations in blood and platelets from depressed and control Mexican subjects to evaluate a possible correlation with the severity of depression. The effect of fluoxetine and citalopram treatment on blood and platelet 5-HT and TRP concentrations in depressed patients was also studied. Material and methods Depressed patients The patients of this study were carefully selected and evaluated. Scales based on semi-structured interviews were applied (MINI and SCID-II) by clinical investigators to reduce any possible bias in patient selection. The influence of the seasonal variability on the 5-HT or TRP blood concentrations was controlled by pairing depressed patients and healthy subjects according to age, gender and, in the case of women, menstrual cycle phase. Patients with a complete remission of depression symptoms (defined as a score not higher than 5 points in the Hamilton's scale, and lower than 7 points in Beck's scale) were asked for a blood sample to measure platelet and blood concentrations of 5-HT and TRP. The patients were weighted before the treatment and after their improvement. Control subjects The control group was integrated by 30 healthy subjects, 24 women and 6 men, with an average age of 32.3 ± 10.8 years. Participants were recruited from the overall Mexican population, interviewed by a psychiatrist, and evaluated with the structured interview MINI and the SCID-II, all these to discard any psychiatric diagnose. None of them had received any pharmacological treatment during the three weeks prior to the study. Control and depressed women were paired according to their menstrual cycle phase. All participants received a detailed explanation of the study, and those who voluntarily accepted the stipulations signed an informed consent document. Control and patient subjects were clinically examined and studied with routine laboratory tests (blood count, blood chemistry, urinalysis, and thyroid function test). Blood sample procedures 5-HT and TRP measurements in total blood preparation were carried out according to the method described by Anderson, and were quantified by high performance liquid chromatography (HPLC). Statistical analysis The differences were statistically determined through an analysis of variance (ANOVA), with the assistance of the SPSS 12.00 (Statistical Software by SPPS Inc.). Results Results from laboratory tests, such as blood count, blood chemistry, thyroid function (T3, T4 and TSH) and urinalysis were normal in depressed subjects, as well as in healthy volunteers. Platelet number, blood 5-HT concentration, platelet content of 5-HT, and blood tryptophan concentration showed no significant differences in depressed patients in comparison to control subjects. 5-HT values in blood and platelet were significantly lower than the initial concentrations in patients after antidepressant treatment. Discussion and conclusions Discrepancies between our study and those found in the literature can be explained with three different approaches: ethnical, physiological, and methodological, as is further discussed. The significant decrease produced by the antidepressant treatment in blood and platelet serotonin concentration may be a consequence of the action of SSRIs, due to a 5-HT diminished uptake by the platelet. Considering our results, we conclude that: Blood and platelet 5-HT concentrations were not different between depressed patients and healthy volunteers. Blood TRP concentrations were not different between depressed patients and healthy volunteers. SSRIs (fluoxetine or citalopram) used in the treatment of depressed patients induced a significant decrease in blood and platelet content of 5-HT, and had no effect in TRP concentrations. Based on these results, neither blood/platelet 5-HT nor blood tryptophan concentrations seem to be good biological markers of depressive patients status. However, 5-HT, but not tryp-tophan, might be a reference point for pharmacological treatment effect.
Positive isolation of leptospires prevalence is described in naturally infected rats in the "villa" La Cava, San Isidro, Buenos Aires Province. Monthly captures, each lasting three days, were performed from December 1995 until November 1996. Species, sex and weight of rats captured were determined. The prevalence rates (leptospiras were isolated from kidneys) were 45.8% in Rattus norvegicus and 18.1% in Rattus rattus. The isolations corresponded to virulent strains of Leptospira interrogans serogroup Icterohaemorrhagiae. In Rattus norvegicus there was not significant difference among prevalence rates according to sex or weight. The high and persistent prevalence is a risk for human and animals living in the studied area.
Se describe la prevalencia de leptospiras en ratas capturadas en la villa de emergencia La Cava, San Isidro, provincia de Buenos Aires. Desde diciembre de 1995 hasta noviembre de 1996 se realizaron capturas mensuales de ratas durante tres días en cada relevamiento, a las que se les determinó especie, sexo y peso. Las tasas de prevalencia (examinados en cuanto a su infección de leptospiras por cultivo de riñón) fueron de 45.8% en Rattus norvegicus y de 18.1% en Rattus rattus. Los aislamientos correspondieron a cepas virulentas de Leptospira interrogans serogrupo Icterohaemorrhagiae. Las tasas de prevalencia de leptospiras en Rattus norvegicus no difirieron significativamente en cuanto al sexo ni al peso de los individuos capturados. La prevalencia de leptospiras fue alta y persistente a lo largo del año, a pesar de la aparente disminución de la abundancia de ratas luego del inicio de una campaña de desratización. Esto indica el alto riesgo para personas y animales residentes en el hábitat estudiado.
Because of the importance of food safety for public health, a study was done to determine the microbiologic quality of foods provided to patrons of community dining halls in greater Buenos Aires, Argentina. The study was descriptive and was conducted in three municipalities with intermediate or high poverty indices; a sample of 52 dining halls was selected randomly from those municipalities. Information was Information was collected from April 1994 through April 1995 by means of surveys, direct observations, and microbiologic analyses of the water and food served. Water and food analysis followed the recommendations of the Argentine Food Code and the International Commission on Microbiologic Specifications for Foods, respectively. The results were interpreted according to the values for cooked foods agreed upon by the Working Group on Food Monitoring. The microbiologic analysis revealed that 28 (54%) of the dining halls had food or water of inadequate quality and 11 (21%) had inadequacies in both. Bacillus cereus was the most commonly found pathogenic bacterium in the food samples analyzed. The factors that were significantly associated with unsatisfactory microbiologic conditions in the food and water were lack of disinfection of the water (P = 0.009), lack of hygiene in the environment (P = 0.03), the presence of rodents and insects (P = 0.05), the supply system for raw materials (P = 0.01), and a relatively small number of users, i.e., fewer than 100 (P = 0.0008). It was concluded that water disinfection and general clean-up of the dining halls were measures that could be put in place by providing education in the areas of hygiene and food handling to supervisors and employees. The results obtained also indicate the need to include a food safety evaluation among the general evaluation criteria for food assistance programs.
Debido a la importancia que la inocuidad de los alimentos entraña para la salud pública, se procuró determinar la calidad microbiológica de los alimentos que consumen los usuarios de los comedores comunitarios del conurbano de Buenos Aires, Argentina. Se trata de un estudio descriptivo, cuyo universo lo conformaron tres municipios con índices medianos y altos de pobreza, de los que se extrajo al azar una muestra de 52 comedores. La información se recolectó desde abril de 1994 hasta abril de 1995 inclusive, por medio de encuestas, observaciones directas y análisis microbiológicos del agua y los alimentos servidos. Los análisis del agua y los alimentos se ajustaron, respectivamente, a las recomendaciones del Código Alimentario Argentino y de la Comisión Internacional de Especificaciones Microbiológicas para Alimentos. Los resultados se interpretaron según los valores para alimentos cocidos acordados por el Grupo de Trabajo de Control de Alimentos. La parte microbiológica del estudio mostró que en 28 (54%) de los comedores la comida o el agua era inadecuada y en 11 (21%), ambas eran inadecuadas. Bacillus cereus fue la bacteria patógena que se encontró con mayor frecuencia en los alimentos analizados. Los factores significativamente asociados con condiciones microbiológicas insatisfactorias de las comidas y el agua fueron no desinfectar el agua (P = 0,009), la falta de higiene en el ambiente (P = 0,03), la presencia de roedores e insectos (P = 0,05), el sistema de provisión de materias primas (P = 0,01) y un número de usuarios menor de 100 (P = 0,008). Se concluyó que la desinfección del agua y la limpieza general de los comedores son medidas que pueden implantarse por medio de intervenciones educativas en materia de higiene y manipulación de alimentos dirigidas a los encargados y empleados de los comedores. Los resultados obtenidos también apoyan la conveniencia de incluir la evaluación sanitaria de los alimentos entre los criterios de evaluación general de los programas de asistencia alimentaria.