Who Transmits Tuberculosis to Whom: A Cross-Sectional Analysis of a Cohort Study in Lima, Peru.

Rationale: The persistent burden of tuberculosis (TB) disease emphasizes the need to identify individuals with TB for treatment and those at a high risk of incident TB for prevention. Targeting interventions toward those at high risk of developing and transmitting TB is a public health priority. Objectives: We aimed to identify characteristics of individuals involved in TB transmission in a community setting, which may guide the prioritization of targeted interventions. Methods: We collected clinical and sociodemographic data from a cohort of patients with TB in Lima, Peru. We used whole-genome sequencing data to assess the genetic distance between all possible pairs of patients; we considered pairs to be the result of a direct transmission event if they differed by three or fewer SNPs, and we assumed that the first diagnosed patient in a pair was the transmitter and the second was the recipient. We used logistic regression to examine the association between host factors and the likelihood of direct TB transmission. Measurements and Main Results: Analyzing data from 2,518 index patients with TB, we identified 1,447 direct transmission pairs. Regardless of recipient attributes, individuals less than 34 years old, males, and those with a history of incarceration had a higher likelihood of being transmitters in direct transmission pairs. Direct transmission was more likely when both patients were drinkers or smokers. Conclusions: This study identifies men, young adults, former prisoners, alcohol consumers, and smokers as priority groups for targeted interventions. Innovative strategies are needed to extend TB screening to social groups such as young adults and prisoners with limited access to routine preventive care.

Chest Radiograph Screening for Detecting Subclinical Tuberculosis in Asymptomatic Household Contacts, Peru.

The World Health Organization's end TB strategy promotes the use of symptom and chest radiograph screening for tuberculosis (TB) disease. However, asymptomatic early states of TB beyond latent TB infection and active disease can go unrecognized using current screening criteria. We conducted a longitudinal cohort study enrolling household contacts initially free of TB disease and followed them for the occurrence of incident TB over 1 year. Among 1,747 screened contacts, 27 (52%) of the 52 persons in whom TB subsequently developed during follow-up had a baseline abnormal radiograph. Of contacts without TB symptoms, persons with an abnormal radiograph were at higher risk for subsequent TB than persons with an unremarkable radiograph (adjusted hazard ratio 15.62 [95% CI 7.74-31.54]). In young adults, we found a strong linear relationship between radiograph severity and time to TB diagnosis. Our findings suggest chest radiograph screening can extend to detecting early TB states, thereby enabling timely intervention.

Development and Pilot-Testing of an Optimized Conversational Agent or "Chatbot" for Peruvian Adolescents Living With HIV to Facilitate Mental Health Screening, Education, Self-Help, and Linkage to Care: Protocol for a Mixed Methods, Community-Engaged Study.

BACKGROUND: Adolescents living with HIV are disproportionally affected by depression, which worsens antiretroviral therapy adherence, increases viral load, and doubles the risk of mortality. Because most adolescents living with HIV live in low- and middle-income countries, few receive depression treatment due to a lack of mental health services and specialists in low-resource settings. Chatbot technology, used increasingly in health service delivery, is a promising approach for delivering low-intensity depression care to adolescents living with HIV in resource-constrained settings. OBJECTIVE: The goal of this study is to develop and pilot-test for the feasibility and acceptability of a prototype, optimized conversational agent (chatbot) to provide mental health education, self-help skills, and care linkage for adolescents living with HIV. METHODS: Chatbot development comprises 3 phases conducted over 2 years. In the first phase (year 1), formative research will be conducted to understand the views, opinions, and preferences of up to 48 youths aged 10-19 years (6 focus groups of up to 8 adolescents living with HIV per group), their caregivers (5 in-depth interviews), and HIV program personnel (5 in-depth interviews) regarding depression among adolescents living with HIV. We will also investigate the perceived acceptability of a mental health chatbot, including barriers and facilitators to accessing and using a chatbot for depression care by adolescents living with HIV. In the second phase (year 1), we will iteratively program a chatbot using the SmartBot360 software with successive versions (0.1, 0.2, and 0.3), meeting regularly with a Youth Advisory Board comprised of adolescents living with HIV who will guide and inform the chatbot development and content to arrive at a prototype version (version 1.0) for pilot-testing. In the third phase (year 2), we will pilot-test the prototype chatbot among 50 adolescents living with HIV naïve to its development. Participants will interact with the chatbot for up to 2 weeks, and data will be collected on the acceptability of the chatbot-delivered depression education and self-help strategies, depression knowledge changes, and intention to seek care linkage. RESULTS: The study was awarded in April 2022, received institutional review board approval in November 2022, received funding in December 2022, and commenced recruitment in March 2023. By the completion of study phases 1 and 2, we expect our chatbot to incorporate key needs and preferences gathered from focus groups and interviews to develop the chatbot. By the completion of study phase 3, we will have assessed the feasibility and acceptability of the prototype chatbot. Study phase 3 began in April 2024. Final results are expected by January 2025 and published thereafter. CONCLUSIONS: The study will produce a prototype mental health chatbot developed with and for adolescents living with HIV that will be ready for efficacy testing in a subsequent, larger study. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/55559.

Programmatic implementation of depression screening and remote mental health support sessions for persons recently diagnosed with TB in Lima, Peru during the COVID-19 pandemic.

Background: Few studies have explored a stepped care model for delivering mental health care to persons with tuberculosis (TB). Here, we evaluated depression screening and remote low-intensity mental health interventions for persons initiating TB treatment in Lima, Peru during the COVID-19 pandemic. Methods: We used the Patient Health Questionnaire 9 (PHQ-9) to screen participants for depressive symptoms (PHQ-9 ≥ 5). Participants with PHQ-9, 5-14 received remote Psychological First Aid (PFA) or Problem Management Plus (PM+). Participants were reevaluated 6 months after intervention completion. We then compared the change in median PHQ-9 scores before and after intervention completion. Those with PHQ-9 ≥ 15 were referred to higher-level care. Findings: We found that 62 (45.9%) of the 135 participants had PHQ-9 ≥ 5 at baseline. Then, 54 individuals with PHQ-9, 5-9 received PFA, of which 44 (81.5%) were reevaluated. We observed significant reductions in median PHQ-9 scores from 6 to 2 (r = 0.98; p < 0.001). Four participants with PHQ-9, 10-14 received PM+ but were unable to be reevaluated. Four participants with PHQ-9 ≥ 15 were referred to higher-level care. Conclusions: Depressive symptoms were common among persons recently diagnosed with TB. We observed improvements in depressive symptoms 6 months later for most participants who received remote sessions of PFA.

Tuberculosis treatment loss to follow-up in children exposed at home: A prospective cohort study.

Background: Loss to follow-up (LTFU) from tuberculosis (TB) treatment and care is a significant public health problem. It is important to understand what drives LTFU in children - a population whose treatment and management depend on an adult caregiver - to better provide support services to families affected by TB. Methods: We conducted a prospective cohort study of household contacts in Lima, Peru (2009-12). Using multilevel logistic regression analysis, we explored individual-level characteristics of children and their adult household members with TB disease to identify risk factors for LTFU among children initiated on treatment for TB. Results: A total of 154 child (0-14 years) household contacts were diagnosed with TB and initiated on treatment. While most (n = 133, 86.4%) had a successful outcome, 20 (13.0%) children were LTFU. Six (30.0%) children were LTFU within three months, nine (45.0%) between five to seven months, and three (15.0%) after seven months of treatment being initiated. In univariable analysis, children with index patients above 25 years of age had decreased odds of being LTFU (odds ratio = 0.26; 95% confidence interval = 0.08-0.84) compared to children with index patients 25 years or younger. Conclusions: In this cohort, more than 10% of children sick with TB who were exposed to the disease at home were LTFU. An integrated, family-centred TB prevention and management approach may reduce barriers to a child completing their course of TB treatment.

Perspectives on competency-based feedback for training non-specialists to deliver psychological interventions: multi-site qualitative study of the EQUIP competency-based approach.

BACKGROUND: The use of feedback to address gaps and reinforce skills is a key component of successful competency-based mental health and psychosocial support intervention training approaches. Competency-based feedback during training and supervision for personnel delivering psychological interventions is vital for safe and effective care. AIMS: For non-specialists trained in low-resource settings, there is a lack of standardised feedback systems. This study explores perspectives on competency-based feedback, using structured role-plays that are featured on the Ensuring Quality in Psychosocial and Mental Health Care (EQUIP) platform developed by the World Health Organization and United Nations Children's Fund. METHOD: Qualitative data were collected from supervisors, trainers and trainees from multiple EQUIP training sites (Ethiopia, Kenya, Lebanon, Peru and Uganda), from 18 key informant interviews and five focus group discussions (N = 41 participants). Qualitative analysis was conducted in Dedoose, using a codebook with deductively and inductively developed themes. RESULTS: Four main themes demonstrated how a competency-based structure enhanced the feedback process: (a) competency-based feedback was personalised and goal-specific, (b) competency-based feedback supported a feedback loop, (c) competency-based feedback supported a comfortable and objective feedback environment, and (d) competency-based feedback created greater opportunities for flexibility in training and supervision. CONCLUSIONS: A better understanding of the role of feedback supports the implementation of competency-based training that is systematic and effective for trainers and supervisors, which ultimately benefits the learning process for trainees.

Alveolar rhabdomyosarcoma: origin and prognostic implications of molecular findings / Rabdomiosarcoma alveolar: origen de los hallazgos moleculares e implicaciones pronósticas

Abstract: We present the case of a 2-year-old male patient with a facial tumor partially treated with chemotherapy before his admission to our institution. The tumor involved from the frontal region to the maxillary floor, the orbit, and the maxillary and sphenoid sinuses. The histopathological diagnosis revealed a stage IV alveolar rhabdomyosarcoma with infiltration to bone marrow and cerebrospinal fluid. He was managed with four cycles of adriamycin, actinomycin, cyclophosphamide and vincristine; cisplatin and irinotecan were added to the last cycle. The tumor had a 50% size reduction, but the patient died after a neutropenia and fever episode. The aggressive behavior of alveolar rhabdomyosarcoma has been associated with the expression of oncogenic fusion proteins resulting from chromosomal translocations, particularly t(2;13) (q35;q14) PAX3/FOXO1, and t(1;13) (p36;q14) PAX7/FOXO1 which were present in this patient.

Resumen: Se presenta el caso de un niño de dos años de edad con un tumor facial tratado parcialmente con quimioterapia anterior a su admisión en este hospital. El tumor abarcaba desde la región frontal hasta el piso maxilar, la órbita y los senos esfenoidales y maxilares. El diagnóstico histopatológico reveló un rabdomiosarcoma alveolar estadio IV con infiltración a la médula ósea y fluido cerebroespinal. El paciente fue tratado con cuatro ciclos de adriamicina, actinomicina, ciclofosfamida y vincristina; al último ciclo se añadieron cisplatino e irinotecan. El tumor se redujo en 50% de su tamaño, pero el paciente murió tras un episodio febril y neutropénico. La agresividad del rabdomiosarcoma alveolar se ha asociado con la expresión de proteínas oncogénicas de fusión provenientes de translocaciones cromosomales, particularmente t(2;13) (q35;q14) PAX3/FOXO1 y t(1;13) (p36;q14) PAX7/FOXO1, presentes en este paciente.

Malaria seroprevalence in blood bank donors from endemic and non-endemic areas of Venezuela

In Venezuela, a total of 363,466 malaria cases were reported between 1999-2009. Several states are experiencing malaria epidemics, increasing the risk of vector and possibly transfusion transmission. We investigated the risk of transfusion transmission in blood banks from endemic and non-endemic areas of Venezuela by examining blood donations for evidence of malaria infection. For this, commercial kits were used to detect both malaria-specific antibodies (all species) and malaria antigen (Plasmodium falciparum only) in samples from Venezuelan blood donors (n = 762). All samples were further studied by microscopy and polymerase chain reaction (PCR). The antibody results showed that P. falciparum-infected patients had a lower sample/cut-off ratio than Plasmodium vivax-infected patients. Conversely, a higher ratio for antigen was observed among all P. falciparum-infected individuals. Sensitivity and specificity were higher for malarial antigens (100 and 99.8 percent) than for antibodies (82.2 and 97.4 percent). Antibody-positive donors were observed in Caracas, Ciudad Bolívar, Puerto Ayacucho and Cumaná, with prevalences of 1.02, 1.60, 3.23 and 3.63 percent, respectively. No PCR-positive samples were observed among the donors. However, our results show significant levels of seropositivity in blood donors, suggesting that more effective measures are required to ensure that transfusion transmission does not occur.

Frecuencia y patotipos de Escherichia coli diarrogénicas en niños peruanos con y sin diarrea / Frequency and pathotypes of diarrheagenic Escherichia coli in peruvian children with and without diarrhea

Introducción. Las E. coli diarrogénicas (DEC) son una de las principales causas de diarrea en niños en países en vías de desarrollo. Sin embargo, no son rutinariamente diagnosticadas en los laboratorios clínicos. Objetivos. Determinar la prevalencia de las DEC en niños peruanos y describir la variabilidad genética de estas cepas. Materiales y métodos. Se utilizaron 8 003 cepas de E. coli previamente aisladas de ocho estudios previos de diarrea en niños, mayormente en zonas periurbanas de Lima. El diagnóstico de las DEC fue a través de un PCR múltiple a tiempo real para los seis grupos de DEC. Se empleó PCR para la determinación de genes adicionales de virulencia. Resultados. La prevalencia promedio global en muestras de diarrea (n=4 243) fue: E. coli enteroagregativa (EAEC) 9,9 por ciento, enteropatogénica (EPEC) 8,5 por ciento, enterotoxigénica (ETEC) 6,9 por ciento, difusamente adherente (DAEC) 4,8 por ciento, productora de toxina shiga (STEC) 0,8 por ciento y enteroinvasiva (EIEC) 0,6 por ciento. La frecuencia relativa de cada patógeno varía según la edad y tipo de estudio. Los principales patotipos en muestras control (n=3 760) fueron EPEC (10,9 por ciento) y EAEC (10,4 por ciento). Se encontró una gran variabilidad en la frecuencia de genes de virulencia para cada patotipo, así como en los mecanismos moleculares de resistencia, sin diferencias significativas entre muestras de diarrea y control. Conclusiones. Las DEC son causa importante de diarrea en niños peruanos. Estos patógenos son altamente heterogéneos. Se requieren estudios adicionales para determinar la prevalencia en zonas rurales del Perú, así como en casos graves de diarrea.

Introduction. Diarrheagenic E. coli (DEC) are a major cause of diarrhea in children in developing countries. However, they are not part of routine diagnosis in clinical laboratories. Objectives. To determine the DEC prevalence in Peruvian children and to describe the genetic variability of these strains. Materials and methods. A total of 8 003 E. coli strains previously isolated from eight different studies of diarrhea in children, mainly from peri-urban areas of Lima, were analyzed. Diagnosis of DEC was done with Multiplex real-time PCR using genes for each of the 6 DEC groups. Conventional PCR was performed for the detection of additional virulence genes. Results. Globally, the mean prevalence in diarrhea samples (n=4,243) was: enteroaggregative E. coli (EAEC) 9.9 percent, enteropathogenic E. coli (EPEC) 8.5 percent, enterotoxigenic E. coli (ETEC) 6.9 percent, diffusely adherent E. coli (DAEC) 4.8 percent, Shiga toxin-producing E. coli (STEC) 0.8 percent and enteroinvasive E. coli (EIEC) 0.6 percent. The relative frequency of each pathogen varies according to the age and the type of study. The main pathotypes in control samples (n=3,760) were EPEC (10.9 percent) and EAEC (10.4 percent). An important variability in the virulence genes frequency and molecular resistance mechanisms for each pathotype was found, without differences between diarrhea and control groups. Conclusions. DEC are a major cause of diarrhea in Peruvian children. These pathogens are highly heterogeneous. Additional studies are required to determine the prevalence in rural areas of Peru and in severe diarrhea cases.

Patrones de adherencia de cepas de Escherichia coli Difusamente adherente (DAEC) provenientes de niños con y sin diarrea / Adhesion patterns in diffusely adherent Escherichia coli (DAEC) strains isolated from children With and without diarrhea

Introducción. Las E. coli de adherencia difusa (DAEC) son el sexto grupo de E. coli diarrogénicas reconocidas. Su asociación con diarrea es controversial. No se conoce la variabilidad en los patrones de adherencia de cepas clínicas. Objetivos. Comparar los patrones de adherencia entre cepas aisladas de niños con y sin diarrea. Materiales y métodos. Se analizó 31 cepas DAEC, 25 de diarrea y 6 de niños asintomáticos (control) aislados de un estudio de cohorte de niños menores de 12 meses en el cono sur de Lima. Las DAEC fueron identificadas por PCR (gen daaD). Se evaluó el patrón y grado de adherencia en cultivos de células HEp-2; la polimerización de actina se evaluó por la prueba de coloración de fluorescencia de actina (FAS); y la motilidad se evaluó por métodos convencionales microbiológicos. Resultados. El patrón de adherencia difusa se encontró en el 88 por ciento de muestras de diarrea y en el 100 por ciento de muestras control. La cantidad de bacterias adheridas por célula fue significativamente menor en las muestras de diarrea (p<0,05). Sin embargo, la polimerización de actina fue mayor en las muestras de diarrea (60 por ciento frente a 17 por ciento). La prueba de motilidad fue positiva en el 60 por ciento de las cepas de diarrea y en el total de muestras control. Conclusiones. Nuestros hallazgos sugieren la existencia de diferencia en los patrones de adherencia, polimerización de actina y motilidad entre cepas de DAEC correspondientes a los grupos de diarrea y control. La significancia de estos resultados debe confirmarse con mayor número de cepas, así como la determinación de los genes de virulencia en las cepas.

Introduction. Diffusely adherent E. coli (DAEC) is the sixth recognized group of diarrheagenic E. coli. However, its association with diarrhea remains controversial. Variability in the adherence patterns of clinical strains is unknown. Objectives. To compare the adherence patterns between strains isolated from children with and without diarrhea. Materials and methods. A total of 31 DAEC strains were analyzed, 25 from children with diarrhea and 6 from asymptomatic (control) children, isolated from a cohort study of children under one year of age in the southern districts of Lima. DAEC were identified by PCR (daaD gene). The pattern and adherence score in HEp-2 cell culture were evaluated, Actin polimerization was determined by fluorescence actin staining (FAS) and motility was evaluated by conventional microbiology methods. Results. Diffuse adherence pattern was found in 88 percent of diarrhea samples and in the total of control strains. The number of bacteria adhered per cell was significantly lower in diarrhea samples (p<0.05). However, actin polymerization was greater in diarrhea samples (60 percent vs. 17 percent). Motility test was positive in 60 percent of the diarrhea samples and in all control samples. Conclusions. Our findings suggest a difference between adherence patterns, actin polymerization and motility between DAEC strains corresponding to diarrhea and control groups. The significance of these results must be confirmed with a bigger number of strains and determining the presence of virulence genes in the strains.

Tumor venéreo transmisible en caninos del área metropolitana de la ciudad de México / Canine Transmissible Venereal Tumor in the Metropolitan Area of Mexico City

Un estudio fue conducido en 9 centros de control de rabia en la zona metropolitana de la ciudad de México, de enero a julio 2007. Los perros muestreados fueron capturados en las calles. Un total de 717 muestras de perros sacrificados fueron evaluadas para determinar la presencia de tumor venéreo transmisible canino, considerando solamente perros mayores de 1 año. La enfermedad fue detectada en 17,48% de las muestras y no hubo diferencia entre el origen, que tuvo un rango de 12,44 a 33,33%. La edad del perro afectó la frecuencia (P<0,05) siendo menor en los perros geriatras (> 7 años; 7,14%), y la más alta en el grupo de 3 a 4 años (20,95). No hubo diferencia entre género (machos 19,13% vs. hembras 15,30%) a pesar de que hubo una tendencia a ser mayor en machos (P=0,07). El tumor venéreo transmisible canino está presente en los perros capturados en las calles de ciudad de México y la presencia de la enfermedad es similar a la reportada en otros países.

A study was conducted at the 9 Rabies Control Centers in the metropolitan zone of Mexico City, from January to July 2007, sampled dogs were captured in the streets. A total of 717 samples were obtained from sacrificed dogs older than 1 year old to determine the presence of canine transmissible venereal tumor. The disease was detected in 17.48% of the samples and there was no difference between origins of sample which ranged from 12.44 to 33.33%. The age of the dog affected (P<0.05) the frequency, being lower in older dogs (>7 years; 7.14%), and the highest in the group from 3 to 4 years (20.95%). There was not difference between sexes (males 19.13% vs. females 15.30%) even when there was a tendency to be higher in males (P=0.07). Canine transmissible venereal tumor was present in street dogs captured in Mexico City and its presence is similar to that reported in other countries.

Eficacia de la clorhexidina y del control mecánico en la reducción de gingivitis en niños de 10 a 12 años / Eficacy of chlorhexidine and mechanical control at reducing gingivitis in 10-12 years old children

Objetivo: determinar la efectividad de la clorhexidina y del control mecánico o la combinación de ambos medios en la reducción de gingivitis en niños de 10 a 12 años. Material y método: 40 niños de 10 a 12 años con gingivitis participaron en la investigación y fueron distribuidos en cuatro grupos: Grupo 1: recibieron cepillo dental, Grupo 2: recibieron cepillo más hilo dental, Grupo 3: sólo recibió enjuagatorio de clorhexidina al 0.12% y Grupo 4: recibieron cepillo más hilo dental y clorhexidina al 0.12%. A cada niño se le registró el índice gingival (Loe y Silness), el índice de placa y el índice de sangrado papilar de Muhlemann, al inicio, a los 3 días, 7 días y a las 2 semanas. Resultados: después de 2 semanas el grupo cepillo más hilo dental y clorhexidina al 0.12% tuvo una reducción significante de placa (de 1.40 redujo a 0.22), de inflamación gingival (de 1,33 redujo a 0,42) y de sitios sangrantes (de 1,29 redujo a 0,46). Conclusiones: estos datos demuestran que el control mecánico combinado con la clorhexidina es efectivo en la reducción de gingivitis en niños de 10 a 12 años de edad.

Objective: to determine the efficacy of chlorhexidine and mechanical control or the combination of both at reducing gingivitis in 10-12 years old children. Materials and Method: 40 children, age 10-12 years with gingivitis participated in the investigation, and separated into four groups: Group one received toothbrush; group two received toothbrush plus dental floss; Group three received 0.12% chlorhexidine mouthrinses alone; Group four received toothbrush plus dental floss and 0.12% chlorhexidine. For each child, a gingival index (Loe y Silness), plaque index and bleeding index (Mühlemann) were rercorded at baseline, day 3, day 7 and at 2 weeks. Results: after 2 weeks the toothbrush plus dental floss and 0.12% chlorhexidine group had significant reduction of plaque (of 1,40 reduced to 0,22), gingival inflammation (of 1.33 reduced to 0.42) and in bleeding sites (of 1.29 reduced to 0,46). Conclusions: these data show that the mechanical control combined with chlorhexidine is effective at reducing gingivitis in 10-12 years old children.

Determinación fenotípica de subpoblaciones de células madre derivadas de sangre de cordón umbilical / Phenotypical determinants of stem cell subpopulations derived from human umbilical cord blood

Introducción. La sangre de cordón umbilical humana es una alternativa para la obtención de células madre hematopoyéticas; sin embargo, no es clara la expresión conjunta de los antígenos CD34, CD38 y HLA-DR, ni de antígenos embrionarios asociados con este tipo de muestra. Objetivos. Determinar la expresión en membrana de los antígenos CD34, CD38 y HLA-DR, así como de los antígenos embrionarios SSEA-4 (Specific Stage Embryonic Antigen–4) y CD13. Materiales y métodos. El estudio se realizó en muestras de sangre de cordón umbilical obtenidas de ochenta mujeres en estado de gravidez normal a término que asistieron al servicio de ginecobstetricia del Hospital Universitario San Ignacio. Los antígenos se determinaron mediante citometría de flujo. Resultados. El rango de células CD34+ presentes en sangre de cordón umbilical humana fue mayor al 0,2 por ciento (p=0,0010): a partir de esta población el rango de CD34+/ CD38-/ HLA-DR- fue de 0,0153 por ciento a 0,0234 por ciento, de CD34+/CD38+/HLA-DR- fue de 0,0191 por ciento a 0,296 por ciento, de CD34+/CD38-/HLA-DR+ fue de 0,0427 por ciento a 0,0676 por ciento, y de CD34+/CD38+/HLA-DR+ fue de 0,2427 por ciento a 0,5117 por ciento. La expresión de los antígenos embrionarios SSEA-4 y CD13 se determinó con el mismo método y se encontraron ocho muestras positivas para la expresión de estos antígenos. Conclusiones. El fenotipo que se expresa con mayor frecuencia en sangre de cordón umbilical corresponde a CD34+ CD38+ HLA DR+; además, el hallazgo de antígenos embrionarios podría indicar que en sangre de cordón umbilical humana existen poblaciones celulares con fenotipos similares a los progenitores celulares adultos multipotentes (Multipotent Adult Progenitor Cells) descritos en médula ósea.

Stage-specific activity of potential antimalarial compounds measured in vitro by flow cytometry in comparison to optical microscopy and hypoxanthine uptake

The evaluation of new antimalarial agents using older methods of monitoring sensitivity to antimalarial drugs are laborious and poorly suited to discriminate stage-specific activity. We used flow cytometry to study the effect of established antimalarial compounds, cysteine protease inhibitors, and a quinolone against asexual stages of Plasmodium falciparum. Cultured P. falciparum parasites were treated for 48 h with different drug concentrations and the parasitemia was determined by flow cytometry methods after DNA staining with propidium iodide. P. falciparum erythrocytic life cycle stages were readily distinguished by flow cytometry. Activities of established and new antimalarial compounds measured by flow cytometry were equivalent to results obtained with microscopy and metabolite uptake assays. The antimalarial activity of all compounds was higher against P. falciparum trophozoite stages. Advantages of flow cytometry analysis over traditional assays included higher throughput for data collection, insight into the stage-specificity of antimalarial activity avoiding use of radioactive isotopes.

Detección parsitológica y molecular de infecciones naturales por trypanosoma evansy y trypanosoma vivax en búfalos de agua (bubalus bubalis) y chigüires (hydrochoerus hydrochaeris) en los estados Apure Cojedes y Guárico Venezuela / Parasitological and molecular detection of natural infection by trypanosoma evansi and trypanosoma vivax in water buffaloes (bubalus bubalis) and capybaras (hydrochoerus hydrochaeris) in Apure Cojedes and Guarico states Venezuela

Este estudio evaluó la presencia de Trypanosoma evansi y Trypanosoma vivax en búfalos de agua (Bubalus bubalis) y chigüires (Hydrochoerus hydrochaeris) de tres estados de Venezuela por técnicas parasitológicas y moleculares (frotis teñido: FT; microcentrifugación capilar: TMC; reacción en cadena de la Polimerasa: PCR), estableciéndose el porcentaje de infecciones activas. En 316 muestras sanguíneas de búfalos las tasas de detección para FT, TMC y PCR fueron de 20 (6,33 por ciento), 36 (11,39 por ciento) y 60 (18,98 por ciento),respectivamente. Por PCR se caracterizó a T. vivax como la especie responsable de todas las infecciones, no detectándose presencia de T. evansi. En 186 muestras de chigüires FT y TMC identificaron positividad en 36 (19,35 por ciento) y 71 (38,17 por ciento) de estas, respectivamente, con altas parasitemias; en 27 de estas se observaron tripanosomas del Subgénero Megatrypanum. Por PCR se caracterizaron como T. evansi 51 muestras de chigüires, seis con resultados TMC-negativo. No se detectó T. vivax en chigüires. Un análisis de t-student estableció diferencias (p<0.05) entre los valores de hematocrito (Ht) de búfalos positivos y negativos a tripanosomas; mientras que por análisis de varianza se detectó efecto (p< 0.05) del grado de parasitemia sobre el Ht. No hubo ningún efecto (p>0.05) al realizar los mismos análisis para las muestras de chigüires.

Estabilidade da carne bovina em atmosfera estabilizada após maturaçäo em embalagem a vácuo / Aged beef stability in modified atmosphere packages

Cortes em bifes de alcatra e contrafilé foram acondicionados a vácuo e maturados durante 20 dias a 0ºC. Posteriormente, foram retirados da embalagem e acondicionados em atmosfera modificada ( composiçäo gasosa inicial de 68 por cento de oxigênio, 15 por cento de nitrogênio, 17 por cento de gás carbônico e 66 por cento de oxigênio, 17 por cento de nitrogênio, 18 por cento de gás carbônico, respectivamente ). Para fins comparativos, prepararam-se amostras dos mesmos cortes em ar atmosférico. Periodicamente, o produto estocado a 1 ñ 1ºC foi avaliado quanto à qualidade microbiológica, sensorial, perda de líquido e pH. Também se avaliou a composiçäo gasosa do espaço-livre das embalagens com atmosfera modificada. A atmosfera modificada, no sistema em teste, teve pouco efeito sobre o crescimento de aeróbios psicrotrófilos, provavelmente porque os cortes apresentaram altas contagens iniciais de bactérias lácticas, devido a prévia estocagem a vácuo. Durante a estocagem, a perda de líquido exsudado e a variaçäo de pH foram semelhantes nos dois sistemas de acondicionamento, para ambos os cortes. A vida útil dos bifes de alcatra estocados em ar e atmosfera modificada foi de 5 e 6 dias, respectivamente. Os fatores limitantes da aceitabilidade foram a cor da carne ( ar e atmosfera modificada ), a descoloraçäo ( ar ) e a uniformidade da cor ( atmosfera modificada ). A vida útil dos bifes de contrafilé foi aumentada de 4 dias em ar para 7 dias em atmosfera modificada, sendo que os fatores limitantes da vida útil foram os mesmos citados para a alcatra, acrescidos da cor da gordura do produto mantido em ar