Jaagsiekte sheep retrovirus pseudotyped lentiviral vector-mediated gene transfer to fetal ovine lung.

Viral vector-mediated gene transfer to the postnatal respiratory epithelium has, in general, been of low efficiency due to physical and immunological barriers, non-apical location of cellular receptors critical for viral uptake and limited transduction of resident stem/progenitor cells. These obstacles may be overcome using a prenatal strategy. In this study, HIV-1-based lentiviral vectors (LVs) pseudotyped with the envelope glycoproteins of Jaagsiekte sheep retrovirus (JSRV-LV), baculovirus GP64 (GP64-LV), Ebola Zaire-LV or vesicular stomatitis virus (VSVg-LV) and the adeno-associated virus-2/6.2 (AAV2/6.2) were compared for in utero transfer of a green fluorescent protein (GFP) reporter gene to ovine lung epithelium between days 65 and 78 of gestation. GFP expression was examined on day 85 or 136 of gestation (term is ∼145 days). The percentage of the respiratory epithelial cells expressing GFP in fetal sheep that received the JSRV-LV (3.18 × 10(8)-6.85 × 10(9) viral particles per fetus) was 24.6±0.9% at 3 weeks postinjection (day 85) and 29.9±4.8% at 10 weeks postinjection (day 136). Expression was limited to the surface epithelium lining fetal airways <100 µm internal diameter. Fetal airways were amenable to VSVg-LV transduction, although the percentage of epithelial expression was low (6.6±0.6%) at 1 week postinjection. GP64-LV, Ebola Zaire-LV and AAV2/6.2 failed to transduce the fetal ovine lung under these conditions. These data demonstrate that prenatal lung gene transfer with LV engineered to target apical surface receptors can provide sustained and high levels of transgene expression and support the therapeutic potential of prenatal gene transfer for the treatment of congenital lung diseases.

Dyskeratosis congenita: a combined immunodeficiency with broad clinical spectrum--a single-center pediatric experience.

BACKGROUND: Dyskeratosis Congenita (DKC) is a syndrome characterized by immunodeficiency, bone marrow failure, somatic abnormalities, and cancer predisposition resulting from defective telomere maintenance. The immunologic features of DKC remain under diagnosed and under treated despite the fact that immunodeficiency is a major cause of premature mortality in DKC. METHODS: This study undertook a retrospective review of 7 DKC patients diagnosed at the Children's Hospital of Philadelphia. In parallel, we reviewed previously reported immunologic findings in DKC patients. RESULTS: Immunologic abnormalities (lymphopenia, low B-cell numbers, hypogammaglobulinemia, and decreased T-cell function) were the most frequent laboratory findings at initial presentation, preceding the development of significant anemia or thrombocytopenia. Recurrent sinopulmonary or opportunistic infections were present in 6/7 patients. Infant-onset patients had more severe immunologic and somatic features (particularly severe enteropathy). CONCLUSION: In DKC, development of immunologic abnormalities can precede bone marrow failure, highlighting the importance of proper immunodeficiency management to minimize morbidity and premature mortality in this disease.

Retropharyngeal aberrant thymus.

INTRODUCTION: Upper airway obstruction from a retropharyngeal mass requires urgent evaluation. In children, the differential diagnosis includes infection, trauma, neoplasm, and congenital abnormalities. Aberrant cervical thymic tissue, although occasionally observed on autopsy examination, is rarely clinically significant. We present the case of an infant with respiratory distress attributed to aberrant thymic tissue located in the retropharyngeal space. CASE: A 6-week-old infant was brought to the emergency department for evaluation of stridor associated with periodic episodes of cyanosis. Lateral neck radiograph revealed widening of the retropharyngeal soft tissues. The patient's symptoms did not improve with intravenous ampicillin-sulbactam. Magnetic resonance imaging (MRI) performed on the seventh day of hospitalization revealed a retropharyngeal mass that extended to the carotid space. The mass was easily resected using an intraoral approach. Microscopic examination demonstrated thymic tissue. A normal thymus was also observed in the anterior mediastinum on MRI. The patient recovered uneventfully and had no further episodes of stridor or cyanosis. DISCUSSION: Aberrant cervical thymic tissue may be cystic or solid. Cystic cervical thymus is more common, and 6% of these patients present with symptoms of dyspnea or dysphagia. Aberrant solid cervical thymus usually presents as an asymptomatic anterior neck mass. This case is unusual in that solid thymic tissue was located in the retropharynx, a finding not previously reported in the English literature. Additionally, the patient presented in acute respiratory distress, and the diagnosis was confounded by the presence of mild laryngomalacia. In retrospect, our patient likely had symptoms of intermittent upper airway obstruction since birth. The acute respiratory distress at presentation was likely the result of laryngomalacia exacerbated by the presence of aberrant thymic tissue and a superimposed viral infection. Aberrantly located thymic tissue arises as a consequence of migrational defects during thymic embryogenesis. The thymus is a paired organ derived from the third and, to a lesser extent, fourth pharyngeal pouches. After its appearance during the sixth week of fetal life, it descends to a final position in the anterior mediastinum, adjacent to the parietal pericardium. Aberrant thymic tissue results when this tissue breaks free from the thymus as it migrates caudally. Therefore, aberrant thymic tissue may be found in any position along a line from the angle of the mandible to the sternal notch, and in the anterior mediastinum to the level of the diaphragm. In an autopsy study of 3236 children, abnormally positioned thymic tissue was found in 34 cases (1%). The aberrant thymus was most often located near the thyroid gland (n = 19 cases) but was also detected lower in the anterior neck (n = 6 cases), higher in the anterior neck (n = 8 cases), and at the left base of the skull (n = 1 case). The presence of thymic tissue in the retropharyngeal space in our patient is more unusual given the typical embryologic origin and descent of the thymus in the anterior neck to the mediastinum. Children with aberrant thymus may have associated anomalies. Twenty-four of 34 children (71%) with aberrant thymus detected at autopsy had features consistent with DiGeorge syndrome, and only 5 of the remaining 10 patients had a normal mediastinal thymus present. Our patient had normal serum calcium levels after excision and a mediastinal thymus was visualized on MRI. Biospy is required for diagnosis of cervical thymus and should also be considered to exclude other causes. MRI is helpful in delineating the presence, position, and extent of thymic tissue. Immunologic sequelae or recurrence after resection of an aberrant cervical thymus has not been reported.

Central venulitis in pediatric liver allografts.

Central venulitis (CV), a distinct histologic lesion described in adult liver transplants, can occur with acute portal tract rejection or in isolation (ICV). Possible etiologies include immunosuppressive drug toxicity, acute cellular rejection, viral hepatitis, ischemic injury, and recurrent disease. This study was designed to characterize ICV and to assess its potential etiology in pediatric liver recipients because this population generally does not develop recurrent disease or viral hepatitis. All posttransplantation liver biopsy specimens that were obtained from children who received liver allografts over a 4-year period were reviewed. ICV was identified in 12 of 127 posttransplantation biopsies and in 7 of 45 allograft recipients. Only 4 liver transplantations were performed for potentially recurrent diseases (primary sclerosing cholangitis). ICV first appeared in posttransplantation biopsy specimens significantly later than did portal rejection alone. The finding of CV was not significantly correlated with elevation of Tacrolimus levels, reason for transplantation, donor/recipient cytomegalovirus (CMV) status or blood type, cold ischemic times, or the incidence of outflow obstruction. The responses of CV to therapy were variable and, although the majority of cases resolved, several episodes persisted or recurred. In conclusion, ICV occurs in 16% of pediatric liver allograft recipients and does not appear to be related to recurrent disease, viral hepatitis, drug toxicity, or graft ischemia. CV may be a variant of acute rejection, but longer follow-up is required to determine the most adequate therapy for this entity.

Successful reversal of recalcitrant hepatic allograft rejection by photopheresis.

Extracorporeal photopheresis (ECP) is an immunologic modality that has shown efficacy in the treatment of clonal T-cell diseases, including Sézary syndrome and allograft rejection. In this case report, we expand on this observation to include recalcitrant hepatic allograft rejection. A 14-year-old boy with hepatic allograft rejection refractory to high-dose corticosteroid and lymphocytolytic therapy was treated with 4 sessions of ECP over a 6-week period. After 2 sessions, a liver biopsy showed complete reversal of acute cell-mediated rejection. No opportunistic infections or other adverse events were noted. Photopheresis appears to be a safe and effective modality for the treatment of refractory hepatic allograft rejection.

Colonic inflammation found at diagnosis of juvenile retention polyps in pediatric patients.

OBJECTIVE: The finding of colonic inflammation concurrently with a juvenile retention polyp (JRP) may have prognostic value. However, the significance of abnormal mucosal histology with JRP has not been evaluated. We evaluated the significance of mucosal histology at the time of JRP removal with respect to future development of inflammatory bowel disease (IBD) and polyp recurrence. METHODS: The medical records of patients who had an endoscopic polypectomy performed at the Children's Hospital of Philadelphia (CHOP) from 1/1/87 through 4/30/98 were retrospectively reviewed. RESULTS: JRP was histologically identified in 96 patients. A total of 54 patients had colonic mucosal biopsies: 30 (55.6%) had normal histology and 24 (44.4%) had colitis. Of the 24 patients with colitis, 14 patients (58.3%) had inflammation at the polyp site. Twelve of these patients had additional inflammation elsewhere in the colon. Nine (37.5%) had inflammation elsewhere in the colon; however, biopsies around the polyp site were not obtained. One patient with inflammation did not have the location of the polyp documented. Four patients (16.7%) had IBD at the time of polypectomy; two were diagnosed prior and two coincident with JRP. None have subsequently been diagnosed with IBD. There was no difference in polyp recurrence between those with or without inflammation (16.7% [4/24] vs 10.0% [3/30]). The mean follow-up period was 72.4 months (range, 5-142 months). CONCLUSIONS: In our experience, histological mucosal inflammation is a common finding with JRP. This inflammation may be a precursor for the development of JRP but has no predictive value for polyp recurrence. This colitis does not seem to be associated with IBD.

Candida chorioamnionitis after serial therapeutic amniocenteses: a possible association.

BACKGROUND: Reduction amniocentesis is used in cases of severe polyhydramnios to decrease maternal discomfort and the risk of preterm labor. In a MEDLINE search (1966 to present, English language, keywords: amniocentesis, chorioamnionitis), no report of Candida chorioamnionitis after serial reduction amniocentesis exists. CASE: A 29-year-old primigravida with a history of four therapeutic amniocenteses for idiopathic polyhydramnios developed preterm labor at 30 and 5/7 weeks' gestation, rupture of membranes, and Candida albicans chorioamnionitis. Despite aggressive therapy with amphotericin B, the neonate succumbed to overwhelming systemic candidiasis. CONCLUSION: Serial amniocentesis may place patients at elevated risk for Candida chorioamnionitis and subsequent preterm delivery. Clinicians should consider early diagnostic amniocentesis in patients in preterm labor with a history of prior amniocentesis, and the routine Gram stain and culture of amniotic fluid.

Serum hyaluronan and its association with unfavorable histology and aggressiveness of heterotransplanted Wilms' tumor.

BACKGROUND/PURPOSE: The sera and urine of children with Wilms' tumor (WT) often contain increased concentrations of hyaluronan (HA). The authors developed a heterotransplant model to investigate whether serum HA concentrations could predict the histology and progression of WT. METHODS: Random portions of 8 human WT specimens (7 favorable and 1 unfavorable histology findings) were heterotransplanted into the flanks of severe combined immunodeficient (SCID) mice. After 6 to 20 weeks of observation, animals were killed, and serum HA concentrations, tumor histology, and local invasion were determined. RESULTS: Sera of mice supporting tumor growth had a median HA concentration of 9,379 microg/L (range, 459 to 3,206,176 microg/L) compared with a median HA concentration of 416 microg/L (range, 204 to 782 microg/L) in animals not supporting tumor growth. The highest serum HA concentrations were detected in animals harboring unfavorable histology blastemal-predominant tumors, whereas animals supporting favorable histology epithelial- and stromal-predominant tumors had the lowest serum HA concentrations. In association with markedly increased serum HA, undifferentiated blastemal tumors showed significantly greater growth rates than the more differentiated epithelial or stromal tumors. Additionally, serum HA concentrations were greater in mice with invasive as compared with noninvasive tumors for each histological type. Complete resection of established tumors also resulted in the return of serum HA to preheterotransplant concentrations. Identification of tumor progression was further tested in SCID mice receiving subcutaneous flank injections of the human WT cell line, SK-NEP-1. Significantly greater serum HA concentrations again corresponded with more rapid growth rates and invasiveness. CONCLUSIONS: Serum HA concentrations predict the growth, invasion, and unfavorable histology findings of WT in a heterotransplant model. The authors further speculate that HA may foster an environment conducive to WT aggressiveness.

Hepatic mesenchymal hamartoma associated with mesenchymal stem villous hyperplasia of the placenta.

A rare case of prenatally diagnosed hepatic mesenchymal hamartoma associated with mesenchymal stem villous hyperplasia of the placenta is presented and the literature reviewed. The placenta was noticed to have multiple cysts at 16 weeks' gestation and elevated maternal serum alpha-fetoprotein was present. Cystic liver masses were first detected in the fetus at 34 weeks' gestation. The liver mass showed a progressive enlargement during the third trimester and after birth, necessitating extended left hepatic trisegmentectomy at 3 months of age. Histological examination established the diagnosis of mesenchymal hamartoma of the liver and mesenchymal stem villous hyperplasia of the placenta. This is the first report of this association in which both lesions were diagnosed in utero and confirmed by histology after delivery. The likely pathogenesis of these strikingly similar lesions is discussed.

Significance of lymphoid follicles and aggregates in gastric mucosa of children.

This study was designed to evaluate the significance of gastric lymphoid follicles (LF) and aggregates (LA) in children with and without Helicobacter pylori (HP) infection. All 605 antrum biopsies performed during 1994 were reviewed and classified according to the presence or absence of inflammation, LF, or LA. HP was searched with a DiffQuik stain in all biopsies showing gastritis, LF, or LA. Gastritis was diagnosed in 80 biopsies (16 with LF, 18 with LA and 46 without LA or LF). Identification of HP in these biopsies was as follows: (a) cases with LF: 12/16; (b) cases with LA: 3/18; (c) cases without LF or LA: 8/46. The biopsies without gastritis had a higher frequency of LA (65/525) than of LF (2/525). HP was not identified in any case without gastritis. The presence of LF with histologic gastritis had the strongest correlation with HP (R = 0.5, p < 0.00001). LF with gastritis had a positive predictive value of 75% for HP and the absence of LF had a negative predictive value of 82.8% (sensitivity 52%; specificity 92%). LA with gastritis had no significant correlation with HP. From these results we conclude that lymphoid follicles should be distinguished from lymphoid aggregates. Lymphoid follicles can rarely be present in an otherwise normal gastric mucosa; however, they are more frequently found in cases of gastritis and are strongly associated with HP infection. Lymphoid aggregates are not significantly associated with HP infection and may be a component of the normal gastric lymphoid tissue.

Severity of esophageal eosinophilia predicts response to conventional gastroesophageal reflux therapy.

Pediatric patients who present with symptoms of gastroesophageal reflux and severe eosinophilic esophagitis may be unresponsive to aggressive anti-reflux medical therapy. In order to determine whether the degree of eosinophilia predicts anti-reflux treatment response and possibly distinguishes different etiologies, we reviewed the initial biopsies of patients with esophageal eosinophilia and compared the number of eosinophils with the response to anti-reflux treatment. Over a 1-year period, 102 patients with a biopsy demonstrating at least 1 intraepithelial eosinophil were identified among patients undergoing initial endoscopy for symptoms of reflux. All patients were treated with H2 blockers and prokinetic agents. Treatment response was classified into three categories: improvement, relapse, and failure. There were significant differences between the group who improved (mean eosinophil count [MEC] 1.1 +/- 0.3 SEM) and those who failed (24.5 +/- 6.1 SEM, P < 0.0025) or relapsed 6.4 +/- 2.4 SEM, P < 0.05). A threshold MEC value of > or = 7 provided a sensitivity of 61.3%, a specificity of 95.7%, and a predictive value for treatment failure of 86.1. A MEC value of < 7 provided an 85% predictive value of successful therapy. From these data we made the following conclusions: (1) The number of eosinophils has a predictive value of treatment response with > or = 7 per high power field offering a valuable clinical threshold for predicting outcome of conventional therapy. (2) The variable response to conventional reflux treatment may reflect different etiologies. (3) Alternate medical treatment modalities may be appropriate in the presence of severe eosinophilia, before considering surgical intervention.

Enteric defensin expression in necrotizing enterocolitis.

Immaturity of local innate defenses has been suggested as a factor involved in the pathophysiology of necrotizing enterocolitis (NEC). The mRNA of enteric human defensins 5 (HD5) and 6 (HD6), antibiotic peptides expressed in Paneth cells of the small intestine, have significantly lower levels of expression in fetal life compared with the term newborn and adult. In the current study, intracellular HD5 was demonstrated by immunohistochemistry at 24 wk of gestation, but at low levels, consistent with findings at the mRNA level. These data suggest that the low level enteric defensin expression, characteristic of normal intestinal development, may contribute to the immaturity of local defense, which predisposes the premature infant to NEC. To test if levels of defensin expression are altered in NEC, specimens from six cases of patients with NEC and five control subjects (four patients with atresia and one with meconium ileus) were analyzed to determine HD5 and HD6 mRNA levels by in situ hybridization. Compared with the control group, the level of enteric defensin expression per Paneth cell assessed by image analysis was increased 3-fold in cases of NEC (p = 0.02, analysis of variance and covariance). In addition, the number of Paneth cells was increased 2-fold in the small intestinal crypts of NEC specimens compared with those of control subjects (p < 0.01, covariance analysis). In healthy tissue, peptide levels within Paneth cells paralleled mRNA levels through development. In tissue from infants with NEC, the steady state level of intracellular peptide was not increased in conjunction with the observed rise in defensin mRNA. A straightforward interpretation of this finding is that HD5 is actively secreted in this setting and the Paneth cells maintain a constant steady state level of intracellular peptide, but the possibility of translational regulation of peptide expression is also consistent with these data. The associations between NEC and enteric defensin expression reported here offer support for future studies to address the role of these endogenous host defense factors in the pathophysiology of this disease.

Pneumonia in infants and children: radiological-pathological correlation.

The radiographic characteristics of pulmonary infection in children are many and varied. Although typical patterns are helpful in diagnosis, clinical and laboratory evaluation provide important diagnostic information. An understanding of the basic pathophysiology of infection and an appreciation of the anatomy of the child's growing lung help provide clearer, insightful, and more accurate radiological interpretation.

Primary eosinophilic esophagitis in children: successful treatment with oral corticosteroids.

BACKGROUND: The histologic appearance of esophageal eosinophils has been correlated with esophagitis and gastroesophageal reflux disease in children. Esophageal eosinophilia that persists despite traditional antireflux therapy may not represent treatment failure, but instead may portray early eosinophilic gastroenteritis or allergic esophagitis. In this study, a series of pediatric patients with severe esophageal eosinophilia who were unresponsive to aggressive antireflux therapy were examined and their clinical and histologic response to oral corticosteroid therapy assessed. METHODS: Of 1809 patients evaluated prospectively over 2.5 years for symptoms of gastroesophageal reflux, 20 had persistent symptoms and esophageal eosinophilia, despite aggressive therapy with omeprazole and cisapride. These patients were treated with 1.5 mg/kg oral methylprednisolone per day, divided into twice-daily doses for 4 weeks. All patients underwent clinical, laboratory, and histologic evaluation before and after treatment. RESULTS: Histologic findings in examination of specimens obtained in pretreatment esophageal biopsies in children with primary eosinophilic esophagitis indicated significantly greater eosinophilia (34.2+/-9.6 eosinophils/high-power field [HPF]) compared with that in children with gastroesophageal reflux disease who responded to medical therapy (2.26+/-1.16 eosinophils/HPF; p < 0.001). After corticosteroid therapy, all but one patient with primary eosinophilic esophagitis had dramatic clinical improvement, supported by histologic examination (1.5 +/-0.9 eosinophils/HPF, p < 0.0001). CONCLUSIONS: Pediatric patients in a series with marked esophageal eosinophilia and chronic symptoms of gastroesophageal reflux disease unresponsive to aggressive medical antire-flux therapy had both clinical and histologic improvement after oral corticosteroid therapy.

Cystic lung lesions with systemic arterial blood supply: a hybrid of congenital cystic adenomatoid malformation and bronchopulmonary sequestration.

Congenital cystic adenomatoid malformation and bronchopulmonary sequestration are congenital lung tumors that are classically described as having distinct embryology, pathology, and natural history. The authors treated six patients who had prenatally diagnosed lung masses that displayed clinicopathologic features of both lesion types. At prenatal diagnosis (19 to 30 weeks' gestation), all six lesions were classified sonographically as congenital cystic adenomatoid malformation, and none of the masses appeared to have a systemic arterial blood supply as seen by color flow Doppler study. Two of the six masses showed size regression antenatally. At the time of surgery, all six lesions had a systemic vessel directly from the aorta--five cases were consistent grossly with an intralobular bronchopulmonary sequestration, and one case was consistent with an extralobular bronchopulmonary sequestration. However, all six lesions displayed congenital cystic adenomatoid malformation histology. Hydrops developed in one fetus with a huge mass, and that fetus underwent successful fetal surgical resection (left lower lobectomy) at 22 weeks' gestation with delivery at 35 weeks' gestation. One neonate with a large extralobular bronchopulmonary sequestration was treated with resection and extracorporeal membrane oxygenation (ECMO) but died of pulmonary hypoplasia. Four other patients who had much smaller masses underwent elective lower lobectomy after birth. These findings emphasize the importance of seeking an anomalous blood supply in patients who have congenital lung lesions. These "hybrid" cases suggest a similar embryological origin for congenital cystic adenomatoid malformation and bronchopulmonary sequestration.