Intranasal administration of oxytocin increases human aggressive behavior.

Considering its role in prosocial behaviors, oxytocin (OT) has been suggested to diminish levels of aggression. Nevertheless, recent findings indicate that oxytocin may have a broader influence on increasing the salience of social stimuli and may therefore, under certain circumstances, increase antisocial behaviors such as aggression. This controversy led to the following speculations: If indeed oxytocin promotes primarily prosocial behavior, administration of OT is expected to diminish levels of aggression. However, if oxytocin mainly acts to increase the salience of social stimuli, it is expected to elevate levels of aggression following provocation. In order to test this assumption we used the Social Orientation Paradigm (SOP), a monetary game played against a fictitious partner that allows measuring three types of responses in the context of provocation: an aggressive response - reducing a point from the fictitious partner, an individualistic response - adding a point to oneself, and a collaborative response - adding half a point to the partner and half a point to oneself. In the current double-blind, placebo-controlled, within-subject study design, 45 participants completed the SOP task following the administration of oxytocin or placebo. The results indicated that among subjects naïve to the procedure oxytocin increased aggressive responses in comparison with placebo. These results support the saliency hypothesis of oxytocin and suggest that oxytocin plays a complex role in the modulation of human behavior.

[Update on microsporidiosis in humans]. / Actualizaciones sobre microsporidiosis en el hombre.

The importance of microsporidium as an opportunistic agent in immunocompromised and AIDS patients is reviewed. Five strains of the agent have been described: Encephalitozoon, Enterocytozoon, Nosema, Pleistophora and Septata. The clinical presentation may be as 1) Generalized infections with multisystemic involvement, specially of the central nervous system; 2) Intestinal, that is the most important and frequent localization in man, and that may cause death in AIDS patients; 3) Ocular, that affects cornea, conjunctiva and may extend to paranasal sinuses; 4) Liver and biliary tract infection with granulomatous lesions, hepatic necrosis or sclerosing colangitis and 5) Muscular, affecting skeletal muscle. The diagnosis is difficult and is established finding spores in the affected tissues with light or electron microscopy. Lately, the diagnosis of intestinal microsporidiosis is made looking for faecal spores. The resistant wall of spores hampers treatment. However, good results are obtained with Albendazole in intestinal microsporidiosis.

[A case of congenital chagasic megaesophagus: evolution until death caused by esophageal neoplasm, at 27 years of age]. / Un caso de megaesófago chagásico congénito: evolución hasta su fallecimiento por cáncer del esófago, a los veintisiete años de edad.

A symptomatic megaesophagus was demonstrated in a three months old boy with Chagas disease. He had a difficult evolution with frequent aspiration pneumonias and progressive undernutrition. At 14 years old a cardiomyotomy (Heller's procedure) was performed, with good results that allowed a near normal life. At 27 years old, the patient started with progressive dysphagia due to an epidermoid esophageal carcinoma and died after surgery. Since a higher frequency of esophageal carcinoma is observed in achalasia, periodic endoscopic examinations are mandatory.

[Evaluation of commercially available reagents for diagnosis of chagas disease in Chilean blood banks. I. Selection of reagents]. / Evaluacion de reactivos comerciales empleados en el diagnostico de la enfermedad de Chagas en bancos de Sangre de Chile. I seleccion de reactivos.

Infection with T cruzi through blood transfusion is an important public health problem in Latin America, including Chile. A study on the sensitivity, specificity and applicability of currently applied methods was performed. Ten commercially available products were tested in a panel of 180 blood specimens against the indirect immunofluorescence antibody test (IFAT) and the immunoperoxidase test (IP). Qualitative concordance ranged from 82 to 98%, sensitivity from 64 to 97% and specificity from 93 to 100%. Some commercial products had a low performance and ELISA is recommended for routine use in Chilean blood banks, given its significantly higher sensitivity and specificity when compared to the hemagglutination test. In addition, experience with the use of the ELISA test is widespread in Chile.

[Application of a system of serological surveillance of Chagas disease in a region of high chagasic endemia. I. Prevalence of Trypanosoma cruzi infection in Salamanca]. / Aplicación de un sistema de vigilancia serológica de la enfermedad de Chagas en una localidad de alta endemia chagásica. I. prevalencia de infección por Trypanosoma cruzi en Salamanca.

A serologic study for prevalence of Chagas infection was performed in Salamanca, Northern Chile. Indirect immunofluorescence and indirect hemagglutination reactions were used in samples from 1529 females and 698 males representing 10% of the population. A total of 499 positive results were obtained. The incidence of infection increases at a mean rate of 1% per year up to age 30, declining slowly in older groups to reach a maximum of 39.7% for the population. These data will be used to implement appropriate serologic surveillance programs and sanitary control measures in this and other populations.

[Chagas' disease in patients in chronic hemodialysis. Prevalence and risk of transmission by blood transfusion]. / Enfermedad de Chagas en pacientes en hemodiálisis crónica. Prevalencia y riesgo de transmisión por transfusión sanguínea.

A serologic study of Chagas disease was performed in 110 patients submitted to chronic hemodialisis and blood transfusions. Immunofluorescence antibody testing (IgG and IgM) was positive in 6 out of 62 patients receiving multiple blood transfusions (9.7%), but negative in all 48 subjects without transfusions. Thus, repeated blood transfusion is a significant risk for T cruzi infection in chronic hemodialized patients.

Hydatidosis diagnosis by double diffusion in agar with arc 5 detection.

To further assess the double diffusion arc 5 (DD5) test for human hydatidosis, the test was performed on sera from 45 patients with surgically confirmed hydatidosis and 54 with other pathologies in Santiago, Chile. Combined with tests reported previously, this brought the total number of study subjects with confirmed hydatidosis to 98 and the total with other pathologies to 128. Overall, the test yielded positive results with sera from 55 (56%) of the 98 serologically confirmed cases, the degree of seropositivity among patients with pulmonary hydatidosis (36%) being relatively low. The criteria adopted for a positive result were the presence of arc 5 or, in the absence of arc 5, the presence of three or more bands of precipitate. On the basis of these criteria, no false positive results were detected using sera from the 128 patients with other pathologies. It is concluded that using the DD5 test to diagnose hydatidosis in clinically selected individuals can provide results of high specificity; i.e., positive results can be taken as confirming presence of the infection. On the other hand, a negative DD5 result does not constitute definite proof that no hydatid cysts are present.