Evaluation of Mitochondrial Function in Blood Samples Shows Distinct Patterns in Subjects with Thyroid Carcinoma from Those with Hyperplasia.

Metabolic adaptations are a hallmark of cancer and may be exploited to develop novel diagnostic and therapeutic tools. Only about 50% of the patients who undergo thyroidectomy due to suspicion of thyroid cancer actually have the disease, highlighting the diagnostic limitations of current tools. We explored the possibility of using non-invasive blood tests to accurately diagnose thyroid cancer. We analyzed blood and thyroid tissue samples from two independent cohorts of patients undergoing thyroidectomy at the Hospital Universitario 12 de Octubre (Madrid, Spain). As expected, histological comparisons of thyroid cancer and hyperplasia revealed higher proliferation and apoptotic rates and enhanced vascular alterations in the former. Notably, they also revealed increased levels of membrane-bound phosphorylated AKT, suggestive of enhanced glycolysis, and alterations in mitochondrial sub-cellular distribution. Both characteristics are common metabolic adaptations in primary tumors. These data together with reduced mtDNA copy number and elevated levels of the mitochondrial antioxidant PRX3 in cancer tissue samples suggest the presence of mitochondrial oxidative stress. In plasma, cancer patients showed higher levels of cfDNA and mtDNA. Of note, mtDNA plasma levels inversely correlated with those in the tissue, suggesting that higher death rates were linked to lower mtDNA copy number. In PBMCs, cancer patients showed higher levels of PGC-1α, a positive regulator of mitochondrial function, but this increase was not associated with a corresponding induction of its target genes, suggesting a reduced activity in cancer patients. We also observed a significant difference in the PRDX3/PFKFB3 correlation at the gene expression level, between carcinoma and hyperplasia patients, also indicative of increased systemic metabolic stress in cancer patients. The correlation of mtDNA levels in tissue and PBMCs further stressed the interconnection between systemic and tumor metabolism. Evaluation of the mitochondrial gene ND1 in plasma, PBMCs and tissue samples, suggested that it could be a good biomarker for systemic oxidative metabolism, with ND1/mtDNA ratio positively correlating in PBMCs and tissue samples. In contrast, ND4 evaluation would be informative of tumor development, with ND4/mtDNA ratio specifically altered in the tumor context. Taken together, our data suggest that metabolic dysregulation in thyroid cancer can be monitored accurately in blood samples and might be exploited for the accurate discrimination of cancer from hyperplasia.

Heat shock protein 27 activity is linked to endothelial barrier recovery after proinflammatory GPCR-induced disruption.

Vascular inflammation causes endothelial barrier disruption and tissue edema. Several inflammatory mediators act through G protein­coupled receptors (GPCRs), including protease-activated receptor-1 (PAR1), to elicit inflammatory responses. The activation of PAR1 by its ligand thrombin stimulates proinflammatory, p38 mitogen-activated protein kinase (MAPK) signaling that promotes endothelial barrier disruption. Through mass spectrometry phosphoproteomics, we identified heat shock protein 27 (HSP27), which exists as a large oligomer that binds to actin, as a promising candidate for the p38-mediated regulation of barrier integrity. Depletion of HSP27 by siRNA enhanced endothelial cell barrier permeability and slowed recovery after thrombin stimulation. We further showed that two effector kinases of p38 MAPK, MAPKAPK2 (MK2) and MAPKAPK3 (MK3), differentially phosphorylated HSP27 at Ser15, Ser78, and Ser82. Whereas inhibition of thrombin-stimulated p38 activation blocked HSP27 phosphorylation at all three sites, inhibition of MK2 reduced the phosphorylation of only Ser15 and Ser78. Inhibition of both MK2 and MK3 was necessary to attenuate Ser82 phosphorylation. Thrombin-stimulated p38-MK2-MK3 signaling induced HSP27 oligomer disassembly. However, a phosphorylation-deficient mutant of HSP27 exhibited defective oligomer disassembly and altered the dynamics of barrier recovery after thrombin stimulation. Moreover, blocking HSP27 oligomer reassembly with the small-molecule inhibitor J2 enhanced endothelial barrier permeability in vitro and vascular leakage in vivo in response to PAR1 activation. These studies reveal the distinct regulation of HSP27 phosphorylation and function induced by the GPCR-stimulated p38-MK2-MK3 signaling axis that controls the dynamics of endothelial barrier recovery in vitro and vascular leakage in vivo.

Relación entre sobrecarga y competencias del cuidar en cuidadores informales de personas con enfermedades crónicas / The Relationship between Overload and Caregiving Competencies in Informal Caregivers of People with Chronic Diseases / Relação entre sobrecarga e competências do cuidar em cuidadores informais de pessoas com doenças crônicas

Introducción. El desarrollo de enfermedades crónicas y sus posibles complicaciones conllevan la necesidad de recibir cuidados de alguna persona del entorno social o familiar, quien se convierte en cuidador informal. Al desempeñar su rol, esta persona puede experimentar situaciones o características propias del cuidador que repercuten en las competencias del cuidar y sobrecarga, aspectos que podrían afectar la díada cuidador-cuidado. Objetivo. Identificar la relación entre competencias del cuidar y sobrecarga en cuidadores informales de personas con enfermedades crónicas. Metodología. Estudio transversal-correlacional, n= 259 cuidadores informales de personas con enfermedades crónicas, usuarios de dos hospitales generales de Tamaulipas, seleccionados por muestreo no probabilístico, intencional. Se aplicó una cédula de datos sociodemográficos, instrumento Zarit y CUIDAR. Para el análisis, se aplicó estadística descriptiva e inferencial. Resultados. Los cuidadores fueron mayormente mujeres, con parentesco de hija y esposa. Se detectó una correlación negativa y estadísticamente significativa (rs= -.160, p= 0.01) entre la sobrecarga y competencias del cuidar. Discusión. El perfil de los cuidadores de este estudio concuerda con la literatura internacional. La correlación entre las variables de investigación se ha documentado en escasos estudios, por lo que representa un avance de conocimiento en el ámbito de los cuidadores. Conclusión. Se evidenció una correlación que se puede interpretar de la siguiente manera: "a mayor sobrecarga, menor competencias del cuidar". Hallazgo que evidencia necesidades en conocimientos y habilidades para ejercer de forma óptima el rol de cuidador y por ende, tener la capacidad de afrontar situaciones de sobrecarga. Cómo citar. Del Ángel-García JE, León-Hernández RC, Méndez-Santos G, Peñarrieta-De Córdova I, Flores-Barrios F. Relación entre sobrecarga y competencias del cuidar en cuidadores informales de personas con enfermedades crónicas. MedUNAB. 2020;23(2): 233-241. doi: 10.29375/01237047.3878

Introduction: When people develop chronic diseases and their possible complications, it leads to the need to receive care from someone in social or family contexts. This person becomes an informal caregiver. By playing this role, this person can experience situations or characteristics inherent to caregivers, which impact caregiving competencies and overload. These aspects could affect the caregiver-care receiver dyad. Objective. To identify the relationship between caregiving competencies and overload in informal caregivers of people with chronic diseases. Methods. A transversal, correlational study, n= 259, on informal caregivers of people with chronic diseases, users of two general hospitals in Tamaulipas, selected through intentional non-probability sampling. A sociodemographic data form and the Zarit and CUIDAR instruments were used. Descriptive and inferential statistics were applied for the analysis. Results. Caregivers were mostly women, with kinship as daughters or wives. A negative, statistically significant correlation was detected (rs= -.160, p= 0.01) between overload and caregiving competencies. Discussion. Caregivers' profiles in this study concur with international literature. The correlation between research variables has been documented in very few studies, reason why it represents progress in knowledge in the field of caregiving. Conclusion. A correlation that can be interpreted as follows was observed: "more overload implies less caregiving competencies." This finding demonstrates the need for knowledge and skills to optimally provide care and, therefore, have the capacity to face overload situations. Cómo citar. Del Ángel-García JE, León-Hernández RC, Méndez-Santos G, Peñarrieta-De Córdova I, Flores-Barrios F. Relación entre sobrecarga y competencias del cuidar en cuidadores informales de personas con enfermedades crónicas. MedUNAB. 2020;23(2): 233-241. doi: 10.29375/01237047.3878

Introdução. O desenvolvimento de doenças crônicas e suas possíveis complicações acarretam a necessidade de receber cuidados de alguém no ambiente social ou familiar, que se torna cuidador informal. Ao desempenhar seu papel, essa pessoa pode experimentar situações ou características próprias dos cuidadores que tange às competências para cuidar e sobrecarga, aspectos que podem afetar a díade cuidador-cuidado. Objetivo. Identificar a relação entre as competências do cuidar e a sobrecarga em cuidadores informais de pessoas com doenças crônicas. Métodos. Estudo transversal correlacional, n= 259 cuidadores informais de pessoas com doenças crônicas, usuários de dois hospitais gerais de Tamaulipas, selecionados por amostragem intencional não probabilística. Foram aplicados informações sociodemográficas, escala Zarit e CUIDAR. Para a análise, aplicou-se estatística descritiva e inferencial. Resultados. Os cuidadores eram em sua maioria mulheres, com o relacionamento de filha e esposa. Foi detectada correlação negativa e estatisticamente significante (rs= -.160, p= 0.01) entre a sobrecarga e as competências do cuidar. Discussão. O perfil dos cuidadores deste estudo concorda com a literatura internacional. A correlação entre as variáveis de pesquisa foi documentada em poucos estudos e, portanto, representa um avanço no conhecimento na área de cuidadores. Conclusão. Evidenciou-se uma correlação que pode ser interpretada da seguinte forma: "quanto maior a sobrecarga, menor a competência do cuidar". Achado que evidencia a necessidade de conhecimentos e habilidades para exercer de maneira ideal o papel de cuidador e, por tanto, ter a capacidade de enfrentar situações de sobrecarga. Cómo citar. Del Ángel-García JE, León-Hernández RC, Méndez-Santos G, Peñarrieta-De Córdova I, Flores-Barrios F. Relación entre sobrecarga y competencias del cuidar en cuidadores informales de personas con enfermedades crónicas. MedUNAB. 2020;23(2): 233-241. doi: 10.29375/01237047.3878

The Relationship between Overload and Caregiving Competencies in Informal Caregivers of People with Chronic Diseases / Relación entre sobrecarga y competencias del cuidar en cuidadores informales de personas con enfermedades crónicas / Relação entre sobrecarga e competências do cuidar em cuidadores informais de pessoas com doenças crônicas

Introduction: When people develop chronic diseases and their possible complications, it leads to the need to receive care from someone in social or family contexts. This person becomes an informal caregiver. By playing this role, this person can experience situations or characteristics inherent to caregivers, which impact caregiving competencies and overload. These aspects could affect the caregiver-care receiver dyad. Objective. To identify the relationship between caregiving competencies and overload in informal caregivers of people with chronic diseases. Methods. A transversal, correlational study, n= 259, on informal caregivers of people with chronic diseases, users of two general hospitals in Tamaulipas, selected through intentional non-probability sampling. A sociodemographic data form and the Zarit and CUIDAR instruments were used. Descriptive and inferential statistics were applied for the analysis. Results. Caregivers were mostly women, with kinship as daughters or wives. A negative, statistically significant correlation was detected (rs= -.160, p= 0.01) between overload and caregiving competencies. Discussion. Caregivers' profiles in this study concur with international literature. The correlation between research variables has been documented in very few studies, reason why it represents progress in knowledge in the field of caregiving. Conclusion. A correlation that can be interpreted as follows was observed: "more overload implies less caregiving competencies." This finding demonstrates the need for knowledge and skills to optimally provide care and, therefore, have the capacity to face overload situations. Cómo citar. Del Ángel-García JE, León-Hernández RC, Méndez-Santos G, Peñarrieta-De Córdova I, Flores-Barrios F. Relación entre sobrecarga y competencias del cuidar en cuidadores informales de personas con enfermedades crónicas. MedUNAB. 2020;23(2): 233-241. doi: 10.29375/01237047.3878

Introducción. El desarrollo de enfermedades crónicas y sus posibles complicaciones conllevan la necesidad de recibir cuidados de alguna persona del entorno social o familiar, quien se convierte en cuidador informal. Al desempeñar su rol, esta persona puede experimentar situaciones o características propias del cuidador que repercuten en las competencias del cuidar y sobrecarga, aspectos que podrían afectar la díada cuidador-cuidado. Objetivo. Identificar la relación entre competencias del cuidar y sobrecarga en cuidadores informales de personas con enfermedades crónicas. Metodología. Estudio transversal-correlacional, n= 259 cuidadores informales de personas con enfermedades crónicas, usuarios de dos hospitales generales de Tamaulipas, seleccionados por muestreo no probabilístico, intencional. Se aplicó una cédula de datos sociodemográficos, instrumento Zarit y CUIDAR. Para el análisis, se aplicó estadística descriptiva e inferencial. Resultados. Los cuidadores fueron mayormente mujeres, con parentesco de hija y esposa. Se detectó una correlación negativa y estadísticamente significativa (rs= -.160, p= 0.01) entre la sobrecarga y competencias del cuidar. Discusión. El perfil de los cuidadores de este estudio concuerda con la literatura internacional. La correlación entre las variables de investigación se ha documentado en escasos estudios, por lo que representa un avance de conocimiento en el ámbito de los cuidadores. Conclusión. Se evidenció una correlación que se puede interpretar de la siguiente manera: "a mayor sobrecarga, menor competencias del cuidar". Hallazgo que evidencia necesidades en conocimientos y habilidades para ejercer de forma óptima el rol de cuidador y por ende, tener la capacidad de afrontar situaciones de sobrecarga. Cómo citar. Del Ángel-García JE, León-Hernández RC, Méndez-Santos G, Peñarrieta-De Córdova I, Flores-Barrios F. Relación entre sobrecarga y competencias del cuidar en cuidadores informales de personas con enfermedades crónicas. MedUNAB. 2020;23(2): 233-241. doi: 10.29375/01237047.3878

Introdução. O desenvolvimento de doenças crônicas e suas possíveis complicações acarretam a necessidade de receber cuidados de alguém no ambiente social ou familiar, que se torna cuidador informal. Ao desempenhar seu papel, essa pessoa pode experimentar situações ou características próprias dos cuidadores que tange às competências para cuidar e sobrecarga, aspectos que podem afetar a díade cuidador-cuidado. Objetivo. Identificar a relação entre as competências do cuidar e a sobrecarga em cuidadores informais de pessoas com doenças crônicas. Métodos. Estudo transversal correlacional, n= 259 cuidadores informais de pessoas com doenças crônicas, usuários de dois hospitais gerais de Tamaulipas, selecionados por amostragem intencional não probabilística. Foram aplicados informações sociodemográficas, escala Zarit e CUIDAR. Para a análise, aplicou-se estatística descritiva e inferencial. Resultados. Os cuidadores eram em sua maioria mulheres, com o relacionamento de filha e esposa. Foi detectada correlação negativa e estatisticamente significante (rs= -.160, p= 0.01) entre a sobrecarga e as competências do cuidar. Discussão. O perfil dos cuidadores deste estudo concorda com a literatura internacional. A correlação entre as variáveis de pesquisa foi documentada em poucos estudos e, portanto, representa um avanço no conhecimento na área de cuidadores. Conclusão. Evidenciou-se uma correlação que pode ser interpretada da seguinte forma: "quanto maior a sobrecarga, menor a competência do cuidar". Achado que evidencia a necessidade de conhecimentos e habilidades para exercer de maneira ideal o papel de cuidador e, por tanto, ter a capacidade de enfrentar situações de sobrecarga. Cómo citar. Del Ángel-García JE, León-Hernández RC, Méndez-Santos G, Peñarrieta-De Córdova I, Flores-Barrios F. Relación entre sobrecarga y competencias del cuidar en cuidadores informales de personas con enfermedades crónicas. MedUNAB. 2020;23(2): 233-241. doi: 10.29375/01237047.3878

Recycling and Endosomal Sorting of Protease-activated Receptor-1 Is Distinctly Regulated by Rab11A and Rab11B Proteins.

Protease-activated receptor-1 (PAR1) is a G protein-coupled receptor that undergoes proteolytic irreversible activation by coagulant and anti-coagulant proteases. Given the irreversible activation of PAR1, signaling by the receptor is tightly regulated through desensitization and intracellular trafficking. PAR1 displays both constitutive and agonist-induced internalization. Constitutive internalization of PAR1 is important for generating an internal pool of naïve receptors that replenish the cell surface and facilitate resensitization, whereas agonist-induced internalization of PAR1 is critical for terminating G protein signaling. We showed that PAR1 constitutive internalization is mediated by the adaptor protein complex-2 (AP-2), whereas AP-2 and epsin control agonist-induced PAR1 internalization. However, the mechanisms that regulate PAR1 recycling are not known. In the present study we screened a siRNA library of 140 different membrane trafficking proteins to identify key regulators of PAR1 intracellular trafficking. In addition to known mediators of PAR1 endocytosis, we identified Rab11B as a critical regulator of PAR1 trafficking. We found that siRNA-mediated depletion of Rab11B and not Rab11A blocks PAR1 recycling, which enhanced receptor lysosomal degradation. Although Rab11A is not required for PAR1 recycling, depletion of Rab11A resulted in intracellular accumulation of PAR1 through disruption of basal lysosomal degradation of the receptor. Moreover, enhanced degradation of PAR1 observed in Rab11B-deficient cells is blocked by depletion of Rab11A and the autophagy related-5 protein, suggesting that PAR1 is shuttled to an autophagic degradation pathway in the absence of Rab11B recycling. Together these findings suggest that Rab11A and Rab11B differentially regulate intracellular trafficking of PAR1 through distinct endosomal sorting mechanisms.

Six simple questions to detect malnutrition or malnutrition risk in elderly women.

UNLABELLED: Of the numerous instruments available to detect nutritional risk, the most widely used is the Mini Nutritional Assessment (MNA), but it takes 15-20 min to complete and its systematic administration in primary care units is not feasible in practice. We developed a tool to evaluate malnutrition risk that can be completed more rapidly using just clinical variables. Between 2008 and 2013, we conducted a cross-sectional study of 418 women aged ≥60 years from Mexico. Our outcome was positive MNA and our secondary variables included were: physical activity, diabetes mellitus, hypertension, educational level, dentition, psychological problems, living arrangements, history of falls, age and the number of tablets taken daily. The sample was divided randomly into two groups: construction and validation. Construction: a risk table was constructed to estimate the likelihood of the outcome, and risk groups were formed. VALIDATION: the area under the ROC curve (AUC) was calculated and we compared the expected and the observed outcomes. The following risk factors were identified: physical activity, hypertension, diabetes, dentition, psychological problems and living with the family. The AUC was 0.77 (95% CI [0.68-0.86], p < 0.001). No differences were found between the expected and the observed outcomes (p = 0.902). This study presents a new malnutrition screening test for use in elderly women. The test is based on six very simple, quick and easy-to-evaluate questions, enabling the MNA to be reserved for confirmation. However, it should be used with caution until validation studies have been performed in other geographical areas.

N-linked glycosylation of protease-activated receptor-1 at extracellular loop 2 regulates G-protein signaling bias.

Protease-activated receptor-1 (PAR1) is a G-protein-coupled receptor (GPCR) for the coagulant protease thrombin. Similar to other GPCRs, PAR1 is promiscuous and couples to multiple heterotrimeric G-protein subtypes in the same cell and promotes diverse cellular responses. The molecular mechanism by which activation of a given GPCR with the same ligand permits coupling to multiple G-protein subtypes is unclear. Here, we report that N-linked glycosylation of PAR1 at extracellular loop 2 (ECL2) controls G12/13 versus Gq coupling specificity in response to thrombin stimulation. A PAR1 mutant deficient in glycosylation at ECL2 was more effective at stimulating Gq-mediated phosphoinositide signaling compared with glycosylated wildtype receptor. In contrast, wildtype PAR1 displayed a greater efficacy at G12/13-dependent RhoA activation compared with mutant receptor lacking glycosylation at ECL2. Endogenous PAR1 rendered deficient in glycosylation using tunicamycin, a glycoprotein synthesis inhibitor, also exhibited increased PI signaling and diminished RhoA activation opposite to native receptor. Remarkably, PAR1 wildtype and glycosylation-deficient mutant were equally effective at coupling to Gi and ß-arrestin-1. Consistent with preferential G12/13 coupling, thrombin-stimulated PAR1 wildtype strongly induced RhoA-mediated stress fiber formation compared with mutant receptor. In striking contrast, glycosylation-deficient PAR1 was more effective at increasing cellular proliferation, associated with Gq signaling, than wildtype receptor. These studies suggest that N-linked glycosylation at ECL2 contributes to the stabilization of an active PAR1 state that preferentially couples to G12/13 versus Gq and defines a previously unidentified function for N-linked glycosylation of GPCRs in regulating G-protein signaling bias.

Self-management in chronic conditions: partners in health scale instrument validation.

AIMS: This article describes a study that aimed to validate the Self-care in Chronic Conditions Partners in Health Scale instrument in the Mexican population. The instrument has been validated in Australia for use as a screening tool by primary healthcare professionals to assess the self-care skills and abilities of people with a chronic illness. METHODS: Validation was conducted using baseline data for 552 people with diabetes, hypertension and cancer aged 18 or older who were users of healthcare centres in Tampico, Tamaulipas, Mexico. RESULTS: Results show high reliability and validity of the instrument and three themes were identified: knowledge, adherence, and dealing with and managing side effects. CONCLUSION: The findings suggest the scale is useful as a generic self-rated clinical tool for assessing self-management in a range of chronic conditions, and provides an outcome measure for comparing populations and change in patient self-management knowledge and behaviour. The authors recommend validating the scale in other Latin-American settings with more research into the effect of gender on self- management.

Validación del instrumento: competencias de enfermería en salud pública. Lima, Perú / Validation of instrument: skills in public health nursing. Lima, Lima

Objetivo: validar el instrumento: "Competencias del profesional de Enfermería en Salud" elaborado por la Asociación Americana de Enfermería en Salud Pública, USA, en contexto peruano. Material y métodos: estudio transversal, la población estuvo conformada por profesionales de Enfermería que laboran en el primer nivel de atención de una red de servicios del Ministerio de Salud de Lima norte, Perú. Se utilizó una muestra por conveniencia a 108 profesioanles. Se utilizaron las técnicas de juicio de expertos, análisis factorial y el alpha de Cronbach para la validez estadistica. Resultados: se presenta un instrumento con validez en su constructo de cuatro dimensiones, que evalúa 8 competencias con 48 actividades relacionadas con competencias del profesional de enfermería en salud pública, y con una buena confiabilidad con valores alpha de Cronbach de 0,959. Conclusiones: se cuenta con un instrumento que permitirá evaluar las competencias que debe tener un profesional de enfermería que desarrolla una actividad de salud publica en el primer nivel de atención, por lo que se sugiere aplicarlo en otros contextos del país, sin embargo, se necesita seguir realizando mas investigaciones que permitan cubrir otras competencias para estos profesionales.

Objetive: To validate the instrument: "Competencies of the Professional of Nursing in Public Health" elaborated by the American Association of Nursing in Public Health, Usa; in a Peruvian context. Material and Methods: A transversal study was applied, the population were profesionals of nursings that will work in the first level of attention of a Service network of the Ministry of Health of North Lima, Peru. A sample of convenience was applied to 108 professionals. The techniques of expert judment were used together with factorial analysis and the alpha of cronbach for teh statistic validation. Results: The factorial analysis identified 8 factors that evaluate 8 competencies with 48 activities related with competencies of the professional of nursinf in public health and with a good reliability with alpha of cronbach values of 0.959. Conclusion: An instrument is available to start an evaluation of the competencies that a professional of nursing, who develops an activity of public health in the first level of attention, should have, reason why it is suggested to apply it in other contexts of the country, however, more researches that allow to cover other competencies of this profession are needed.

Targeting tuberculosis testing: the yield of source case investigations for young children with reactive tuberculin skin tests.

OBJECTIVE: This study was designed to determine the yield of investigations whose aim is to identify a source case for tuberculosis infection among tuberculin reactors 3 years of age or younger. METHODS: The authors describe the results of associate investigations conducted for child tuberculin reactors reported from January 1, 1996, through June 30, 1998. Associates were defined as individuals who live with or spend significant time with a child reactor. An associate investigation was defined as evaluation of at least one associate. A source case was an associate older than 10 years of age who had culture-positive, pulmonary tuberculosis during a period when the child could have been exposed. RESULTS: Two hundred seven children had an associate investigation performed with a median of four associates investigated per child (range 1-21). Birthplace was known for 187 (90%); 128 were U.S.-born. Of 1,222 associates identified, 980 (80%) were evaluated. Among 452 (46%) associates for whom birthplace was known, 250 (55%) were non-U.S.-born. Of 980 associates, 668 were household contacts; 198 (30%) were infected, three had prior tuberculosis disease, and three had active tuberculosis. Two active cases met source case criteria; the yield was 0.9 (2 of 207) source cases per 100 children investigated. Of 312 non-household contacts, 57 (18%) were infected and none had the disease. CONCLUSIONS: Although few source cases were identified for young tuberculin skin test reactors in New York City, investigations identified a proportion of cases and infection in associates similar to that identified among contacts to pulmonary tuberculosis cases. Such investigations may be identifying a high-risk group and should be considered, depending on program resources.