Biomedical subjects
Publications and source records attributed to V L Fox.
Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) syndrome is a rare disorder that presents in childhood; however, marked delay in diagnosis is common. We report a case and review the literature describing the typical features that should alert pediatricians to the diagnosis. We also describe a novel management strategy for providing symptomatic relief.
Gastrointestinal endoscopy is an essential modality often used for initial diagnostic assessment and staging of visceral vascular anomalies, especially when bleeding is the presenting symptom. Some lesions have a pathognomonic appearance on endoscopy. Others are less clearly identifiable and require a multidisciplinary assessment, including histopathology, for a correct diagnosis. Proper application of nomenclature is crucial to prevent the institution of improper therapies. Advanced endoscopic methods, including endosonography and various hemostatic techniques, are useful to evaluate the depth and character of gastrointestinal wall involvement and to provide minimally invasive treatment when appropriate.
Gastrointestinal (GI) bleeding is an alarming problem in children. Although many causes of GI bleeding are common to children and adults, the frequency of specific causes differs greatly, and some lesions, such as necrotizing enterocolitis or allergic colitis, are unique to children. This article reviews the spectrum of GI bleeding in infants and children. The causes, diagnostic evaluation, and management are discussed, and differences with adult medicine are highlighted.
BACKGROUND/PURPOSE: Lower intestinal venous malformations are rare anomalies resulting from errors in vascular morphogenesis. These lesions may cause significant chronic and acute gastrointestinal hemorrhage. Venous malformations are unresponsive to angiogenesis inhibitors. Although these anomalies generally are incompletely resectable because of diffuse pelvic and mesenteric involvement, the authors sought to abate bleeding by excluding the lesion from the gastrointestinal lumen. METHODS: Three patients with circumferential transmural venous malformations of the colorectum, pelvis, and mesentery were identified. Imaging findings were similar among the patients and included circumferential septated bright signal on T2-weighted magnetic resonance imaging (MRI) contrast enhancement, and multiple phleboliths, seen best on computed tomography (CT). The lesion extended from the anus to the splenic flexure in 2 patients and throughout the entire colorectum in the other. Each had daily hematochezia for many years and required transfusions and chronic iron therapy. Although bleeding began in childhood in each patient, no therapy was successful until ages 7, 24, and 45. Colectomy, anorectal mucosectomy (through the pelvic venous malformation), and endorectal pull-through and anastomosis was performed (coloanal in 2 and ileoanal in 1). RESULTS: Bleeding essentially has been eradicated in all 3 patients with 10- to 57-month follow-up. One patient received a 3-unit transfusion intraoperatively, and the other 2 received none. The most recent patient to undergo surgery, who has residual venous malformation in the remaining 1 cm of anal mucosa, has some mild difficulty with fecal control if her diet results in loose stool. CONCLUSION: Colectomy with mucosectomy and endorectal pull-through should be considered for diffuse venous malformations of the colorectum before the development of large transfusion requirements.
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The emergence of pediatric gastroenterology as a subspecialty and improved design and widespread distribution of small diameter endoscopes have combined to foster dramatic expansion in the practice of pediatric endoscopy over the past three decades. Endoscopic evaluation and treatment of gastrointestinal disease in children has led to new diagnoses and provided exciting opportunities for nonsurgical treatment. This article will focus on important pediatric applications, highlight differences with adult practice, and anticipate future research and development of pediatric endoscopy.
Infiltration of esophageal epithelium by eosinophils is seen in reflux esophagitis and allergic gastroenteritis. This study was performed to identify differences between patients with acid reflux esophagitis and those with non-acid reflux, possibly allergic, esophagitis. Intraepithelial eosinophils were demonstrated in posttherapy esophageal biopsy specimens in 28 children treated for gastroesophageal reflux disease (GERD). These patients were divided into three groups based on their response to treatment and the results of esophageal pH probe monitoring. Eleven patients (Group A) had incomplete clinical response and normal pH probe monitoring results. Ten patients (Group B) had incomplete response but did not have pH probe monitoring. These two groups formed the index population. Seven patients (Group C) had clinical improvement with GERD therapy and abnormal pH probe monitoring characteristic of GERD; they constituted the control population. Clinical, laboratory, and pathologic features were evaluated to detect differences between index and control populations. Dysphagia, food impaction, failure to thrive, peripheral eosinophilia, and abnormal allergen skin test results were detected only in Group A and B patients. Biopsy specimens of the distal 9 cm of the esophagus, after GERD therapy, contained larger numbers of eosinophils in Groups A and B than in Group C as shown on high-power fields (HPF) (A: 31/HPF +/- 19.5; B: 28/HPF +/-23.7; versus C: 5/HPF +/-6.7; p = 0.009). Eosinophil aggregates were identified only in Groups A and B (p = 0.07). Eosinophils located preferentially in the superficial layers of the squamous epithelium were noted only in Groups A and B (p = 0.02). Group A and B patients demonstrated clinical improvement when given antiallergic therapy. The authors identified a group of pediatric patients characterized by an allergic history, lack of adequate response to GERD therapy, normal esophageal pH probe monitoring results, and large numbers of eosinophils in esophageal biopsy specimens obtained after GERD treatment. On the basis of these features, the authors propose that these patients represent examples of allergic esophagitis.
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The recent cloning of a human sodium-dependent bile acid transporter (NTCP) permits analysis of its expression in human liver disease and investigation of potential primary defects in its expression. NTCP from normal human liver (NHL) was first characterized in detail. Northern blotting of RNA from NHL revealed a 1.8-kb NTCP transcript. Western blotting of crude NHL plasma membranes using a carboxyterminal antipeptide antibody showed that NTCP is a 39-kd polypeptide that is N-glycosylated to a final molecular weight of 56 kd. Indirect immunofluorescent analysis of NHL sections indicated that the NTCP protein is expressed on the basolateral surface of hepatocytes. We hypothesized that the clinical phenotype of a defect in NTCP might be hypercholanemia in the relative absence of liver disease. Accordingly, the coding region of the NTCP gene of two children with this phenotype was sequenced after reverse transcription/polymerase chain reaction (RT/PCR) amplification. No primary defects in the deduced NTCP amino acid sequence were found. Despite the extremely high serum bile salt levels (235 and 126 micromol/L) in these two patients, NTCP messenger RNA (mRNA) and protein expression were quantitatively normal, in contrast to the published observations in a rat model of cholestasis secondary to common bile duct ligation. Hepatic steady-state NTCP mRNA levels in a group of 23 pre- and postportoenterostomy biliary atresia patients were inversely related to total bilirubin, indicating that extrahepatic bile duct obstruction leads to down-regulation of NTCP mRNA levels, similar to that observed in rat common bile duct ligation. Therefore the lack of down-regulation in the two patients with hypercholanemia indicates that elevated serum bile salts are not sufficient to down-regulate NTCP expression, these two patients have abnormal responses to hypercholanemia, or these two patients have a defect in a gene other than NTCP that influences hepatic clearance of bile salts.
BACKGROUND: Percutaneous endoscopic gastrostomy has gained wide acceptance for patients who require prolonged tube feeding support. We sought to identify complications and associated risk factors of endoscopic gastrostomy and subsequent catheter replacement in pediatric patients. METHODS: Medical records were reviewed for 137 patients. Odds ratios were calculated for complications related to patient age, weight, weight-for-age Z score, and principal diagnosis. RESULTS: Seventeen patients (12.4%) developed significant complications after gastrostomy: cellulitis occurred in 10 patients (7.3%); other complications included gastrocolic fistula (2), duodenal hematoma (1), complicated pneumoperitoneum (1), necrotizing fasciitis (1), gastric perforation (1), and catheter migration (1). Patients with cancer had significantly greater odds for developing a wound infection, and patients with AIDS had significantly greater odds for total complications. A trend toward increased wound infection was observed in patients with cardiac disease. Age, weight, and weight-for-age Z score were not associated with adverse outcome. Two complications occurred in 85 patients (2.4%) after gastrostomy catheter replacement. CONCLUSIONS: Pediatric patients with cancer and AIDS are at increased risk for complications after endoscopic gastrostomy regardless of age, weight, or nutritional status. Infrequent yet life-threatening complications may occur after replacement of initial gastrostomy catheter.
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Seven consecutive patients presenting acutely with suspected variceal hemorrhage underwent endoscopic variceal ligation (EVL) of esophageal varices. Active bleeding had ceased by the time of the initial EVL session in all patients, although active variceal hemorrhage was controlled by EVL in one patient during a subsequent episode of bleeding. Treatment sessions were repeated at approximately monthly intervals until varices were reduced in size to grade 1 (< 4 mm diameter) or eradicated. All patients had portal hypertension secondary to intrahepatic disease. Patient age ranged from 2.4 to 14.5 years (mean, 8.5 years). One patient underwent successful liver transplantation 1 week after the initial treatment session. The remaining six patients required a mean (+/- SD) of 4.0 +/- 1.3 treatment sessions for elimination of varices. One episode of recurrent variceal hemorrhage and one episode of treatment-related hemorrhage occurred in two separate patients. Transient, mild dysphagia or odynophagia occurred in all patients. No other complications were reported during a mean (+/- SD) follow-up period of 13.8 +/- 4.6 months (range, 8-20 months). Recurrent varices were seen in three of four (75%) patients returning for follow-up endoscopy between 5 and 8 months from initial eradication. All underwent repeat EVL without complication. Endoscopic variceal ligation may be a suitable substitute for sclerotherapy in children with bleeding esophageal varices.
Monoclonal antibodies to T-cell receptors were used to investigate the prevalence of the two distinct T-cell subpopulations (TCR alpha beta+ and TCR gamma delta+ cells) in the intestinal mucosa of children with celiac disease (gluten-sensitive enteropathy) as compared with normal intestinal mucosa. TCR gamma delta+ cells were rarely identified in the epithelium of human fetal or normal postnatal intestine and few were present in the lamina propria, whereas the number of distribution of TCR alpha beta+ cells closely resembled that of CD3+ cells. Compared with normal intestine, a significant increase in the number of CD3+, CD8+, TCR alpha beta+, and TCR gamma delta+ intraepithelial lymphocytes was present in celiac disease. Although the mucosal TCR gamma delta+ cells were less numerous than TCR alpha beta+ cells in celiac disease, there was a marked increase in the number of TCR gamma delta+ cells as compared with controls. The ligand recognized by the gamma delta T-cell receptor and the function of these cells have not been determined; however, these findings suggest a possible role for TCR gamma delta+ lymphocytes in mucosal immune responses and tissue injury as seen in celiac disease.
The human T cell receptor gamma chain locus encodes the immunoglobulin-like gamma chain polypeptide and spans a distance of approximately 150 kb. Previous studies have not precisely characterized the interval separating variable regions from joining--constant regions which is excised during gamma gene rearrangement. We report a series of overlapping cosmids which includes the portion of the gamma chain locus beginning with V2 and extends to the second exon of C2. Sixteen kilobases separate the most 3' variable region gene, V4, from the most 5' joining segment, J1.1.
Children, as consumers of health resources, have special developmental, psychological, and medical needs different from those of adults. Thus, cost containment efforts can affect children differently. Data related to insurance benefits changes, intensified market forces, and reductions in federal funding are cited. Their analysis focuses on the importance of accountability in applying cost constraints to services that can have a significant effect upon the health and well-being of one quarter of the next generation.
Monoclonal antibodies conjugated with fluorescein permitted rapid, strain-specific identification of influenza A isolates and type-specific identification of influenza B isolates by direct immunofluorescence staining. Identification of H1 influenza A strains could be accomplished by direct immunofluorescence on cell culture fluids lacking sufficient hemagglutinin activity to permit identification by hemagglutination inhibition.