RESUMO
ABSTRACT: Nonmuscle cell contractility is an essential feature underlying diverse cellular processes such as motility, morphogenesis, division and genome replication, intracellular transport, and secretion. Blood clot contraction is a well-studied process driven by contracting platelets. Megakaryocytes (MKs), which are the precursors to platelets, can be found in bone marrow and lungs. Although they express many of the same proteins and structures found in platelets, little is known about their ability to engage with extracellular proteins such as fibrin and contract. Here, we have measured the ability of MKs to compress plasma clots. Megakaryocytes derived from human induced pluripotent stem cells (iPSCs) were suspended in human platelet-free blood plasma and stimulated with thrombin. Using real-time macroscale optical tracking, confocal microscopy, and biomechanical measurements, we found that activated iPSC-derived MKs (iMKs) caused macroscopic volumetric clot shrinkage, as well as densification and stiffening of the fibrin network via fibrin-attached plasma membrane protrusions undergoing extension-retraction cycles that cause shortening and bending of fibrin fibers. Contraction induced by iMKs involved 2 kinetic phases with distinct rates and durations. It was suppressed by inhibitors of nonmuscle myosin IIA, actin polymerization, and integrin αIIbß3-fibrin interactions, indicating that the molecular mechanisms of iMK contractility were similar or identical to those in activated platelets. Our findings provide new insights into MK biomechanics and suggest that iMKs can be used as a model system to study platelet contractility. Physiologically, the ability of MKs to contract plasma clots may play a role in the mechanical remodeling of intravascular blood clots and thrombi.
Assuntos
Células-Tronco Pluripotentes Induzidas , Trombose , Humanos , Megacariócitos/metabolismo , Células-Tronco Pluripotentes Induzidas/metabolismo , Plaquetas/metabolismo , Trombose/metabolismo , Fibrina/metabolismo , PlasmaRESUMO
Rebalancing the hemostatic system by targeting endogenous anticoagulant pathways, like the protein C (PC) system, is being tested as a means of improving hemostasis in patients with hemophilia. Recent intravital studies of hemostasis demonstrated that, in some vascular contexts, thrombin activity is sequestered in the extravascular compartment. These findings raise important questions about the context-dependent contribution of activated PC (APC) to the hemostatic response, because PC activation occurs on the surface of endothelial cells. We used a combination of pharmacologic, genetic, imaging, and computational approaches to examine the relationships among thrombin spatial distribution, PC activation, and APC anticoagulant function. We found that inhibition of APC activity, in mice either harboring the factor V Leiden mutation or infused with an APC-blocking antibody, significantly enhanced fibrin formation and platelet activation in a microvascular injury model, consistent with the role of APC as an anticoagulant. In contrast, inhibition of APC activity had no effect on hemostasis after penetrating injury of the mouse jugular vein. Computational studies showed that differences in blood velocity, injury size, and vessel geometry determine the localization of thrombin generation and, consequently, the extent of PC activation. Computational predictions were tested in vivo and showed that when thrombin generation occurred intravascularly, without penetration of the vessel wall, inhibition of APC significantly increased fibrin formation in the jugular vein. Together, these studies show the importance of thrombin spatial distribution in determining PC activation during hemostasis and thrombosis.
Assuntos
Hemostáticos , Trombose , Animais , Anticoagulantes/farmacologia , Células Endoteliais/metabolismo , Fibrina/metabolismo , Hemostasia , Humanos , Camundongos , Proteína C/farmacologia , Trombina/metabolismo , Trombose/metabolismoRESUMO
G protein-coupled receptors are critical mediators of platelet activation whose signaling can be modulated by members of the regulator of G protein signaling (RGS) family. The 2 most abundant RGS proteins in human and mouse platelets are RGS10 and RGS18. While each has been studied individually, critical questions remain about the overall impact of this mode of regulation in platelets. Here, we report that mice missing both proteins show reduced platelet survival and a 40% decrease in platelet count that can be partially reversed with aspirin and a P2Y12 antagonist. Their platelets have increased basal (TREM)-like transcript-1 expression, a leftward shift in the dose/response for a thrombin receptor-activating peptide, an increased maximum response to adenosine 5'-diphosphate and TxA2, and a greatly exaggerated response to penetrating injuries in vivo. Neither of the individual knockouts displays this constellation of findings. RGS10-/- platelets have an enhanced response to agonists in vitro, but platelet count and survival are normal. RGS18-/- mice have a 15% reduction in platelet count that is not affected by antiplatelet agents, nearly normal responses to platelet agonists, and normal platelet survival. Megakaryocyte number and ploidy are normal in all 3 mouse lines, but platelet recovery from severe acute thrombocytopenia is slower in RGS18-/- and RGS10-/-18-/- mice. Collectively, these results show that RGS10 and RGS18 have complementary roles in platelets. Removing both at the same time discloses the extent to which this regulatory mechanism normally controls platelet reactivity in vivo, modulates the hemostatic response to injury, promotes platelet production, and prolongs platelet survival.
Assuntos
Plaquetas/metabolismo , Ativação Plaquetária/genética , Proteínas RGS/genética , Trombopoese/genética , Animais , Plaquetas/efeitos dos fármacos , Sobrevivência Celular/genética , Camundongos , Camundongos Knockout , Fosforilação , Fator de Ativação de Plaquetas/farmacologia , Ativação Plaquetária/efeitos dos fármacos , Inibidores da Agregação Plaquetária/farmacologia , Contagem de Plaquetas , Proteínas RGS/metabolismo , Trombopoese/efeitos dos fármacosRESUMO
G protein-coupled receptors (GPCRs) mediate the majority of platelet activation in response to agonists. However, questions remain regarding the mechanisms that provide negative feedback toward activated GPCRs to limit platelet activation and thrombus formation. Here we provide the first evidence that GPCR kinase 6 (GRK6) serves this role in platelets, using GRK6-/- mice generated by CRISPR-Cas9 genome editing to examine the consequences of GRK6 knockout on GPCR-dependent signaling. Hemostatic thrombi formed in GRK6-/- mice are larger than in wild-type (WT) controls during the early stages of thrombus formation, with a rapid increase in platelet accumulation at the site of injury. GRK6-/- platelets have increased platelet activation, but in an agonist-selective manner. Responses to PAR4 agonist or adenosine 5'-diphosphate stimulation in GRK6-/- platelets are increased compared with WT littermates, whereas the response to thromboxane A2 (TxA2) is normal. Underlying these changes in GRK6-/- platelets is an increase in Ca2+ mobilization, Akt activation, and granule secretion. Furthermore, deletion of GRK6 in human MEG-01 cells causes an increase in Ca2+ response and PAR1 surface expression in response to thrombin. Finally, we show that human platelet activation in response to thrombin causes an increase in binding of GRK6 to PAR1, as well as an increase in the phosphorylation of PAR1. Deletion of GRK6 in MEG-01 cells causes a decrease in PAR1 phosphorylation. Taken together, these data show that GRK6 regulates the hemostatic response to injury through PAR- and P2Y12-mediated effects, helping to limit the rate of platelet activation during thrombus growth and prevent inappropriate platelet activation.
Assuntos
Plaquetas , Hemostáticos , Animais , Camundongos , Ativação Plaquetária , Receptores de Trombina , Transdução de SinaisRESUMO
OBJECTIVE: To identify risk factors associated with nonmelanoma skin cancer (NMSC) occurrence and survival in children. STUDY DESIGN: This was a multicenter, retrospective, case-control study of patients <20 years of age diagnosed with NMSC between 1995 and 2015 from 11 academic medical centers. The primary outcome measure was frequency of cases and controls with predisposing genetic conditions and/or iatrogenic exposures, including chemotherapy, radiation, systemic immunosuppression, and voriconazole. RESULTS: Of the 124 children with NMSC (40 with basal cell carcinoma, 90 with squamous cell carcinoma), 70% had at least 1 identifiable risk factor. Forty-four percent of the cases had a predisposing genetic condition or skin lesion, and 29% had 1 or more iatrogenic exposures of prolonged immunosuppression, radiation therapy, chemotherapy, and/or voriconazole use. Prolonged immunosuppression and voriconazole use were associated with squamous cell carcinoma occurrence (cases vs controls; 30% vs 0%, P = .0002, and 15% vs 0%, P = .03, respectively), and radiation therapy and chemotherapy were associated with basal cell carcinoma occurrence (both 20% vs 1%, P < .0001). Forty-eight percent of initial skin cancers had been present for >12 months prior to diagnosis and 49% of patients were diagnosed with ≥2 skin cancers. At last follow-up, 5% (6 of 124) of patients with NMSC died. Voriconazole exposure was noted in 7 cases and associated with worse 3-year overall survival (P = .001). CONCLUSIONS: NMSC in children and young adults is often associated with a predisposing condition or iatrogenic exposure. High-risk patients should be identified early to provide appropriate counseling and management.
Assuntos
Carcinoma Basocelular/epidemiologia , Carcinoma de Células Escamosas/epidemiologia , Neoplasias Cutâneas/epidemiologia , Adolescente , Antifúngicos/efeitos adversos , Antineoplásicos/efeitos adversos , Estudos de Casos e Controles , Criança , Pré-Escolar , Feminino , Predisposição Genética para Doença/epidemiologia , Humanos , Imunossupressores/efeitos adversos , Lactente , Masculino , Radioterapia/efeitos adversos , Estudos Retrospectivos , Fatores de Risco , Estados Unidos/epidemiologia , Voriconazol/efeitos adversos , Adulto JovemRESUMO
Many genetic loci affect circulating lipid levels, but it remains unknown whether lifestyle factors, such as physical activity, modify these genetic effects. To identify lipid loci interacting with physical activity, we performed genome-wide analyses of circulating HDL cholesterol, LDL cholesterol, and triglyceride levels in up to 120,979 individuals of European, African, Asian, Hispanic, and Brazilian ancestry, with follow-up of suggestive associations in an additional 131,012 individuals. We find four loci, in/near CLASP1, LHX1, SNTA1, and CNTNAP2, that are associated with circulating lipid levels through interaction with physical activity; higher levels of physical activity enhance the HDL cholesterol-increasing effects of the CLASP1, LHX1, and SNTA1 loci and attenuate the LDL cholesterol-increasing effect of the CNTNAP2 locus. The CLASP1, LHX1, and SNTA1 regions harbor genes linked to muscle function and lipid metabolism. Our results elucidate the role of physical activity interactions in the genetic contribution to blood lipid levels.
Assuntos
Exercício Físico , Loci Gênicos/genética , Lipídeos/sangue , Lipídeos/genética , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Povo Asiático/genética , População Negra/genética , Brasil , Proteínas de Ligação ao Cálcio/genética , Colesterol/sangue , HDL-Colesterol/sangue , HDL-Colesterol/genética , LDL-Colesterol/sangue , LDL-Colesterol/genética , Feminino , Estudo de Associação Genômica Ampla , Genótipo , Hispânico ou Latino/genética , Humanos , Proteínas com Homeodomínio LIM/genética , Metabolismo dos Lipídeos/genética , Masculino , Proteínas de Membrana/genética , Proteínas Associadas aos Microtúbulos/genética , Pessoa de Meia-Idade , Proteínas Musculares/genética , Proteínas do Tecido Nervoso/genética , Fatores de Transcrição/genética , Triglicerídeos/sangue , Triglicerídeos/genética , População Branca/genética , Adulto JovemRESUMO
Previous studies have shown that hemostatic thrombi formed in response to penetrating injuries have a core of densely packed, fibrin-associated platelets overlaid by a shell of less-activated, loosely packed platelets. Here we asked, first, how the diverse elements of this structure combine to stem the loss of plasma-borne molecules and, second, whether antiplatelet agents and anticoagulants that perturb thrombus structure affect the re-establishment of a tight vascular seal. The studies combined high-resolution intravital microscopy with a photo-activatable fluorescent albumin marker to simultaneously track thrombus formation and protein transport following injuries to mouse cremaster muscle venules. The results show that protein loss persists after red cell loss has ceased. Blocking platelet deposition with an αIIbß3antagonist delays vessel sealing and increases extravascular protein accumulation, as does either inhibiting adenosine 5'-diphosphate (ADP) P2Y12receptors or reducing integrin-dependent signaling and retraction. In contrast, sealing was unaffected by introducing hirudin to block fibrin accumulation or a Gi2α gain-of-function mutation to expand the thrombus shell. Collectively, these observations describe a novel approach for studying vessel sealing after injury in real time in vivo and show that (1) the core/shell architecture previously observed in arterioles also occurs in venules, (2) plasma leakage persists well beyond red cell escape and mature thrombus formation, (3) the most critical events for limiting plasma extravasation are the stable accumulation of platelets, ADP-dependent signaling, and the emergence of a densely packed core, not the accumulation of fibrin, and (4) drugs that affect platelet accumulation and packing can delay vessel sealing, permitting protein escape to continue.
Assuntos
Proteínas Sanguíneas/metabolismo , Hemostasia , Microvasos/lesões , Microvasos/patologia , Trombose/patologia , Difosfato de Adenosina/metabolismo , Animais , Proteínas Sanguíneas/análise , Fibrina/análise , Fibrina/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Microvasos/metabolismo , Ativação Plaquetária , Contagem de Plaquetas , Trombose/sangue , Trombose/metabolismoAssuntos
Dermatite Atópica/terapia , Hipersensibilidade Alimentar/terapia , Criança , Dermatite Atópica/etiologia , Dermatite Atópica/imunologia , Dessensibilização Imunológica , Dieta , Proteínas Filagrinas , Hipersensibilidade Alimentar/diagnóstico , Hipersensibilidade Alimentar/etiologia , Hipersensibilidade Alimentar/imunologia , Humanos , Imunoglobulina E/sangue , Imunoterapia , Proteínas de Filamentos Intermediários/genética , Mutação , Prognóstico , Fatores de Risco , Testes Cutâneos , Linfócitos T/fisiologiaRESUMO
Hemostatic thrombi develop a characteristic architecture in which a core of highly activated platelets is covered by a shell of less-activated platelets. Here we have used a systems biology approach to examine the interrelationship of this architecture with transport rates and agonist distribution in the gaps between platelets. Studies were performed in mice using probes for platelet accumulation, packing density, and activation plus recently developed transport and thrombin activity probes. The results show that intrathrombus transport within the core is much slower than within the shell. The region of slowest transport coincides with the region of greatest packing density and thrombin activity, and appears prior to full platelet activation. Deleting the contact-dependent signaling molecule, Sema4D, delays platelet activation, but not the emergence of the low transport region. Collectively, these results suggest a timeline in which initial platelet accumulation and the narrowing gaps between platelets create a region of reduced transport that facilitates local thrombin accumulation and greater platelet activation, whereas faster transport rates within the shell help to limit thrombin accumulation and growth of the core. Thus, from a systems perspective, platelet accumulation produces an altered microenvironment that shapes thrombus architecture, which in turn affects agonist distribution and subsequent thrombus growth.
Assuntos
Coagulação Sanguínea , Modelos Cardiovasculares , Ativação Plaquetária , Trombina/metabolismo , Animais , Humanos , Camundongos , Transporte ProteicoRESUMO
BACKGROUND: Topical fixed-combination therapy containing 1% clindamycin as 1.2% clindamycin phosphate (CLNP) and 3% benzoyl peroxide (BPO) is an effective treatment for acne vulgaris (acne). OBJECTIVES: To demonstrate that the combination of 1.2% CLNP with lower strength BPO (CLNP 1.2%-BPO 3%) in a gel formulation is superior to each individual ingredient, CLNP 1.2% and BPO 3%, and vehicle gel. METHODS: A total of 1,319 patients with acne, aged 12 years or older, were enrolled and randomized (1:1:1:1) to receive CLNP 1.2%-BPO 3%, CLNP 1.2% gel, BPO 3% gel, or vehicle gel once-daily in a 12-week, multicenter, double-blind, parallel-group, vehicle-controlled study. Subjects were evaluated at baseline, weeks 2, 4, 8, and 12 or early termination. Assessment of efficacy was evaluated using a six-point Investigator's Static Global Assessment (ISGA) and Subject's Global Assessment (SGA) of acne severity and lesion counts (inflammatory, non-inflammatory, and total). Safety assessments included skin tolerability and adverse events (AEs). RESULTS: A greater proportion of subjects who used CLNP 1.2%-BPO 3% gel (39%) had a two grade improvement in ISGA from baseline to week 12 compared with CLNP 1.2% (25%; P<0.001), BPO 3% (30%; P=0.016), and vehicle (18%; P<0.001). CLNP 1.2%- BPO 3% was superior to CLNP 1.2% and vehicle alone in the absolute reduction from baseline to week 12 in all three lesion types (P<0.001 all pair-wise comparisons). CLNP 1.2%-BPO 3% was superior to BPO 3% alone in the absolute reduction from baseline to week 12 in inflammatory (P=0.015) and total (P=0.032) lesion counts. The incidence of product-related AEs was low and similar in all study groups (1% with CLNP 1.2%-BPO 3%, 2% with CLNP 1.2%, 2% with BPO 3%, and 2% with vehicle). Local tolerability assessments showed similar minimal changes from baseline to week 12 in all study groups. CONCLUSION: CLNP 1.2%-BPO 3% gel provides superior efficacy to improve ISGA score and reduce inflammatory and total lesion counts compared with the individual active ingredients (CLNP 1.2% and BPO 3%) and vehicle, while maintaining a highly favorable safety and tolerability profile similar to BPO 3% alone.
Assuntos
Acne Vulgar/tratamento farmacológico , Antibacterianos/uso terapêutico , Peróxido de Benzoíla/uso terapêutico , Clindamicina/uso terapêutico , Fármacos Dermatológicos/uso terapêutico , Adolescente , Adulto , Antibacterianos/efeitos adversos , Belize , Peróxido de Benzoíla/efeitos adversos , Canadá , Criança , Clindamicina/efeitos adversos , Fármacos Dermatológicos/efeitos adversos , Método Duplo-Cego , Combinação de Medicamentos , Feminino , Géis , Humanos , Masculino , Pessoa de Meia-Idade , Resultado do Tratamento , Estados Unidos , Adulto JovemRESUMO
OBJECTIVE: To examine the efficacy and safety of MAS063DP (Atopiclair) cream in the management of mild to moderate atopic dermatitis in infants and children. STUDY DESIGN: One hundred forty-two patients aged 6 months to 12 years were administered MAS063DP (n = 72) or vehicle (n = 70) cream 3 times per day to affected areas and sites prone to develop atopic dermatitis. The primary endpoint for efficacy was the Investigator's Global Assessment at day 22. Secondary endpoints included Investigator's Global Assessment at other time-points, patient's/caregiver's assessment of pruritus, onset, duration of itch relief, Eczema Area and Severity Index, subject's/caregiver's assessment of global response, and need for rescue medication in the event of an atopic dermatitis flare. RESULTS: MAS063DP cream was statistically more effective (P < .0001) than vehicle cream for the primary endpoint and all secondary endpoints. Treatment discontinuation as a result of an adverse event occurred in 9.9% of patients using MAS063DP cream and 16% of patients using vehicle cream. CONCLUSION: MAS063DP cream is effective and safe as monotherapy for the treatment of symptoms of mild to moderate atopic dermatitis in infants and children.
Assuntos
Dermatite Atópica/tratamento farmacológico , Gorduras na Dieta/uso terapêutico , Ácido Glicirretínico/uso terapêutico , Extratos Vegetais/uso terapêutico , Criança , Pré-Escolar , Formas de Dosagem , Método Duplo-Cego , Feminino , Humanos , Lactente , Masculino , Veículos Farmacêuticos , Índice de Gravidade de DoençaRESUMO
OBJECTIVES: Juvenile localized scleroderma (JLS) usually has its onset during later childhood. This report describes the clinical and serologic features of six children with congenital localized scleroderma (CLS). STUDY DESIGN: A large, multinational study was conducted among pediatric rheumatology and dermatology centers by collecting information on demographics, family history, triggering environmental factors, clinical features, laboratory reports, and treatment of patients with JLS. Patients with onset at birth were carefully examined. RESULTS: Among 750 patients with JLS, 6 patients (0.8%) had scleroderma-related lesions at birth. Female-to-male ratio was 2:1. All patients had linear scleroderma, in four involving the face with en coup de sabre appearance. Two patients were misdiagnosed as having skin infection, one nevus, one salmon patch, and two undefined skin lesions. The mean diagnostic delay was 3.9 years. In comparison with the group of 733 patients with late-onset JLS, CLS presented a significantly more prolonged disease duration at diagnosis and a higher frequency of en coup de sabre subtypes. CONCLUSIONS: Congenital localized scleroderma is a rare and probably underestimated condition in neonates. The linear subtype was the exclusive manifestation of the disease. CLS should be included in the differential diagnosis of infants with cutaneous erythematous fibrotic lesions to avoid functional and aesthetic sequelae and to allow prompt therapy.
Assuntos
Esclerodermia Localizada/congênito , Esclerodermia Localizada/diagnóstico , Atrofia/patologia , Biópsia , Quelantes/uso terapêutico , Pré-Escolar , Feminino , Seguimentos , Humanos , Imunossupressores/uso terapêutico , Lactente , Recém-Nascido , Metotrexato/uso terapêutico , Penicilamina/uso terapêutico , Esclerodermia Localizada/tratamento farmacológico , Pele/patologiaRESUMO
THE PRACTICE OF "head-shrinking" has been the proper domain not of Africa but rather of the denizens of South America. Specifically, in the post-Columbian period, it has been most famously the practice of a tribe of indigenous people commonly called the Jivaro or Jivaro-Shuar. The evidence suggests that the Jivaro-Shuar are merely the last group to retain a custom widespread in northwestern South America. In both ceramic and textile art of the pre-Columbian residents of Peru, the motif of trophy heads smaller than normal life-size heads commonly recurs; the motif is seen even in surviving carvings in stone and shell. Moreover, although not true shrunken heads, trophy heads found in late pre-Columbian and even post-Columbian graves of the region demonstrate techniques of display very similar to those used by the Jivaro-Shuar, at least some of which are best understood in the context of head-shrinking. Regardless, the Jivaro-Shuar and their practices provide an illustrative counterexample to popular myth regarding the culture and science of the shrinking of human heads.
Assuntos
Antropologia Cultural , Embalsamamento/métodos , Etnicidade , Cabeça , Guerra , Equador/etnologia , Humanos , Indígenas Sul-Americanos/etnologiaRESUMO
Objetivando correlacionar o doseamento do lactate liquórico com a evolução clínica de pacientes com meningite, atendidos no HURN foram estudados prospectivamente 45 amostras de LCR (Líquido Cefalorraquidiano), durante o período de setembro/94 a agosto/95. Os LCR obtidos foram analisados bioquímica e microbiologicamente, conforme metodologia já padronizada, acrescidos do doseamento de lactato e do teste de látex-aglutinação, respectivamente. Os LCR foram divididos em 3 grupos. 1º Grupo: Controle composto por 10 pacientes não portadores de meningite, onde os valores de lacto estiveram dentro dos valores de referência, (X=15, 32mg/dl D,P=2,88) (valor de referência 10,8 a 18,9mg/dl); 2º Grupo: composto por 15 pacientes portadores de meningite linfomonocitária, onde os valores de lacto-liquórico estiveram alterados (X=22,64mg/d; D.P.=7,39); 3º Grupo: composto por 20 pacientes portadores de meningite purulenta, onde os valores de lactato estiveram muito mais elevados do que os valores de referência (X=131,36mg/dl: D.P. =46,4). Os autores verificaram que com a evolução clínica direcionada para cura, os níveis de lactato diminuíram sensivelmente, sugerindo-se assim, que o doseamento de lactato possa ser um parâmetro clínico-laboratorial para a alta dos pacientes com meningite.
Assuntos
Humanos , Líquido Cefalorraquidiano , Cálculos da Dosagem de Medicamento , Lactatos/administração & dosagem , MeningiteRESUMO
Enteric types of adenovirus have recently been identified as a causative agent of infantile gastroenteritis. We utilized enzyme immunoassay and tissue culture techniques to evaluate prospectively the role of ET Ad in diarrhea occurring in hospitalized infants. We found that ET Ad was associated with 14 of 27 cases of diarrhea occurring during a 12-week study period in the late autumn and early winter months; ET Ad was found in the stool of only one of 72 children without diarrhea (P less than 0.001). Although adenoviruses other than ET Ad were found in the stools of two of the 27 children with diarrhea, such viruses were also found in the stools of five of 72 children without diarrhea and thus could not be statistically correlated with acute gastroenteritis. Children infected with ET Ad had diarrhea for a mean of 8.0 days, compared to a mean duration of 4.2 days for the children with gastroenteritis not associated with ET Ad. Thirteen of the 14 children with ET Ad gastroenteritis had respiratory symptoms such as cough, rhinorrhea, or wheezing, six had roentgenographic evidence of pneumonia, and three children had bilateral conjunctivitis. This study documents that ET Ad can be an important cause of acute gastrointestinal disease in hospitalized infants and young children and that gastrointestinal infections with ET Ad can be associated with a high rate of respiratory disease.