Mark A. Lovell

The fine structure of the olfactory mucosa in man.

SummaryThis report gives a detailed description of the fine structure of the olfactory mucosa in man. Using a special biopsy instrument and technique, fresh biopsies of olfactory epithelium were taken under local anaesthesia from eight normal volunteers. Transmission electron microscopy reveals that human olfactory epithelium has four major cell types: ciliated olfactory receptors, supporting cells, basal cells and microvillar cells. The ciliated olfactory receptors, as in other mammals, are bipolar neurons; the dendrite tip, modified to form the olfactory vesicle, bears 10–30 cilia that lack dynein arms. The supporting cells, markedly different from the goblet cells of respiratory epithelium, are not specialized for mucus secretion. Instead they are equipped to contribute materials to, and remove materials from, the surface mucus. The basal cells are stem cells that serve to replace epithelial cells and receptors lost during normal turnover or injury. In addition to ciliated olfactory neurons, supporting cells and basal cells, the human olfactory mucosa contains a distinct fourth cell type, the microvillar cell, of unknown function. The apical pole of the cell sends a tuft of short microvilli into the nasal cavity; its basal pole gives rise to a slender cytoplasmic process that resembles an axon. If microvillar cells prove to be sensory cells, the current concept of the human olfactory epithelium will have to be revised to include two morphologically distinct classes of receptors.

The oesophageal string test: a novel, minimally invasive method measures mucosal inflammation in eosinophilic oesophagitis

Objective Eosinophil predominant inflammation characterises histological features of eosinophilic oesophagitis (EoE). Endoscopy with biopsy is currently the only method to assess oesophageal mucosal inflammation in EoE. We hypothesised that measurements of luminal eosinophil-derived proteins would correlate with oesophageal mucosal inflammation in children with EoE. Design The Enterotest diagnostic device was used to develop an oesophageal string test (EST) as a minimally invasive clinical device. EST samples and oesophageal mucosal biopsies were obtained from children undergoing upper endoscopy for clinically defined indications. Eosinophil-derived proteins including eosinophil secondary granule proteins (major basic protein-1, eosinophil-derived neurotoxin, eosinophil cationic protein, eosinophil peroxidase) and Charcot–Leyden crystal protein/galectin-10 were measured by ELISA in luminal effluents eluted from ESTs and extracts of mucosal biopsies. Results ESTs were performed in 41 children with active EoE (n=14), EoE in remission (n=8), gastro-oesophageal reflux disease (n=4) and controls with normal oesophagus (n=15). EST measurement of eosinophil-derived protein biomarkers significantly distinguished between children with active EoE, treated EoE in remission, gastro-oesophageal reflux disease and normal oesophagus. Levels of luminal eosinophil-derived proteins in EST samples significantly correlated with peak and mean oesophageal eosinophils/high power field (HPF), eosinophil peroxidase indices and levels of the same eosinophil-derived proteins in extracts of oesophageal biopsies. Conclusions The presence of eosinophil-derived proteins in luminal secretions is reflective of mucosal inflammation in children with EoE. The EST is a novel, minimally invasive device for measuring oesophageal eosinophilic inflammation in children with EoE.

Toll-like receptor 4–dependent Kupffer cell activation and liver injury in a novel mouse model of parenteral nutrition and intestinal injury†‡

Infants with intestinal failure who are parenteral nutrition (PN)‐dependent may develop cholestatic liver injury and cirrhosis (PN‐associated liver injury: PNALI). The pathogenesis of PNALI remains incompletely understood. We hypothesized that intestinal injury with increased intestinal permeability combined with administration of PN promotes lipopolysaccharide (LPS)–Toll‐like receptor 4 (TLR4) signaling dependent Kupffer cell (KC) activation as an early event in the pathogenesis of PNALI. We developed a mouse model in which intestinal injury and increased permeability were induced by oral treatment for 4 days with dextran sulphate sodium (DSS) followed by continuous infusion of soy lipid‐based PN solution through a central venous catheter for 7 (PN7d/DSS) and 28 (PN28d/DSS) days. Purified KCs were probed for transcription of proinflammatory cytokines. PN7d/DSS mice showed increased intestinal permeability and elevated portal vein LPS levels, evidence of hepatocyte injury and cholestasis (serum aspartate aminotransferase, alanine aminotransferase, bile acids, total bilirubin), and increased KC expression of interleukin‐6 (Il6), tumor necrosis factor α (Tnfα), and transforming growth factor β (Tgfβ). Markers of liver injury remained elevated in PN28d/DSS mice associated with lobular inflammation, hepatocyte apoptosis, peliosis, and KC hypertrophy and hyperplasia. PN infusion without DSS pretreatment or DSS pretreatment alone did not result in liver injury or KC activation, even though portal vein LPS levels were elevated. Suppression of the intestinal microbiota with broad spectrum antibiotics or ablation of TLR4 signaling in Tlr4 mutant mice resulted in significantly reduced KC activation and markedly attenuated liver injury in PN7d/DSS mice. Conclusion: These data suggest that intestinal‐derived LPS activates KC through TLR4 signaling in early stages of PNALI. (HEPATOLOGY 2012)

Recurrent inflammatory pseudotumors in children

BACKGROUND/PURPOSE pulmonary (PPT) and extrapulmonary pseudotumors (EPPT) are uncommon benign tumors, which, in general, do not recur after complete resection. Recurrence rates for both types of pseudotumors are undocumented in a large population of children, and the salient features of potential recurrences are unspecified. METHODS This is a report of 15 children with PPT and EPPT; 3 children had a recurrence. These pseudotumors recurred despite adequate primary resection of all gross disease at first presentation. The literature was reviewed to determine rate of recurrence for PPT and EPPT and also to document features common to recurrent pseudotumors. RESULTS Overall recurrence rate for pseudotumors was 14%. PPT and EPPT, which were not confined to a single organ, had a high chance of recurrence (46% and 30%, respectively) compared with PPT and EPPT, which were confined to a single organ (1.5% and 8%, respectively). Recurrences have appeared between 3 months and 7 years. Intraabdominal EPPT accounts for more than 75% of the EPPT recurrences. CONCLUSIONS PPT and EPPT recur more frequently than anticipated. All pseudotumors, which on initial presentation extend beyond the confines of a single organ, have a high chance of recurrence despite what appears to be adequate resection. Children with pseudotumors that extend beyond a single organ, require frequent postoperative evaluation for recurrence and may be candidates for chemotherapy or radiotherapy at the time of initial resection.

Ectopic Expression of the Proto-oncogene Mer in Pediatric T-Cell Acute Lymphoblastic Leukemia

Purpose: The Mer receptor tyrosine kinase, cloned from a B-lymphoblastoid library, is the mammalian orthologue of the chicken retroviral oncogene v-eyk and sends antiapoptotic and transforming signals when activated. To determine if Mer expression is ectopic in T-cell acute lymphoblastic leukemia (ALL) and potentially important in leukemogenesis, we analyzed Mer expression in normal human thymocytes and lymphocytes and in pediatric ALL patient samples. Experimental Design: Reverse transcription-PCR, flow cytometry, and immunohistochemistry were used to determine expression of Mer in sorted human thymocyte populations, lymphocytes, and lymphocytes activated by phytohemagglutinin or phorbol 12-myristate 13-acetate/ionophore. Mer expression in 34 T-cell ALL (T-ALL) patient samples was evaluated by reverse transcription-PCR, and Mer protein expression in a separate cohort of 16 patient samples was assayed by flow cytometry and Western blot. Results: Mer expression was absent in normal thymocytes or lymphocytes, and in T cells activated with phytohemagglutinin or phorbol 12-myristate 13-acetate/ionophore. In contrast, Jurkat cells and T-ALL patient samples expressed unique 180 to 185 kDa Mer protein glycoforms. Substantial Mer RNA levels were principally observed in a subset of T-ALL patient samples that expressed B220 (P = 0.004) but lacked surface expression of CD3 (P = 0.02) and CD4 (P = 0.006), a phenotypic profile consistent with immature lymphoblasts. In addition, 8 of 16 T-ALL patient samples had Mer protein detected by flow cytometry and Western blot. Conclusions: Transforming Mer signals may contribute to T-cell leukemogenesis, and abnormal Mer expression may be a novel therapeutic target in pediatric ALL therapy.

Feeding Dysfunction in Children With Eosinophilic Gastrointestinal Diseases

OBJECTIVES: Feeding dysfunction (FD) seen in younger children with eosinophilic gastrointestinal disease (EGID) has not been well described. Thus, our aim was to further characterize FD in children with EGIDs. METHODS: A retrospective medical record analysis of 200 children seen over 12 months in a multidisciplinary Gastrointestinal Eosinophilic Diseases Program was performed. The clinical data of 33 children identified as also having FD were examined, including information obtained by history, physical examination, feeding evaluation, review of nutritional data, allergy testing and histologic assessment of mucosal biopsies. RESULTS: Of 200 children with EGIDs, 16.5% had significant FD. The median age of this group was 34 months (range: 14–113 months). A variety of learned maladaptive feeding behaviors were reported in 93.9%. Frequent gagging or vomiting occurred in 84.8%. Food sensitivity was documented in 88% while 52% had other allergic disease. Twenty one percent were diagnosed with failure to thrive and 69.7% required individual or group feeding therapy. Forty-two percent had residual eosinophilia of >15 per HPF on esophageal biopsies performed at the time of symptoms. CONCLUSIONS: FD is prevalent in children with EGIDs often presenting as maladaptive learned feeding behaviors with altered mealtime dynamics and physical difficulties in eating mechanics. FD can persist even after eosinophilic inflammation is successfully treated. Awareness of the increased prevalence of FD in children with EGIDs with enable earlier recognition of this problem, resulting in a comprehensive, individualized treatment plan with the desired outcome of improving the development, feeding, and nutrition of these children.

Failure of resolution of portal fibrosis during omega-3 fatty acid lipid emulsion therapy in two patients with irreversible intestinal failure.

Parenteral omega-3 fatty acid lipid emulsions have been evaluated for their potential role in reversing intestinal failure-associated liver disease. We report our experience using Omegaven in 2 patients with irreversible intestinal failure and intestinal failure-associated liver disease. Despite biochemical and histologic improvement in cholestasis, both patients had persisting, significant portal fibrosis on liver biopsy.

Gonadoblastoma and Turner Syndrome

PURPOSE The presence of a Y chromosome in the extrascrotal gonad of patients with intersex disorders has been associated with a high risk of GB and, potentially, GCT. Recently, modern sophisticated genotyping has revealed a subgroup of TS cases with a mosaic karyotype expressing a Y chromosome. We sought to evaluate this group of patients and address their risk of gonadoblastoma. MATERIALS AND METHODS We reviewed the records and genotyping of all females newly diagnosed with TS between 1990 and 2002 at Childrens Hospital in Denver. All patients with TS and Y chromosome mosaicism underwent gonadectomy, and the specimens were evaluated for the presence of gonadoblastoma on histological analysis and to identify Y chromosome on genotyping. RESULTS A total of 192 girls with a clinical diagnosis of TS were identified between January 1990 and December 2002. Seven records were unavailable and 19 patients did not have karyotypic analyses available in the hospital charts. Of the remaining 166 patients 67 exhibited mosaic cell lines, of whom 8 had 45,X0/46,XY mosaic pattern and 59 had mosaic patterns without Y chromosomal elements. All 8 patients with Y mosaicism underwent uneventful laparoscopic gonadectomy on an outpatient basis. One patient observed to have bilateral dysgenetic gonads after gonadectomy was excluded from the study. Gonadoblastoma (bilateral 2 patients, unilateral 1) was detected in 3 of 7 patients (43%) with Y mosaicism. CONCLUSIONS In our series 4.8% of evaluable patients with TS carried a 45,X0/46,XY karyotype. Gonadoblastoma can be evident even at an early age in streak gonads with Y mosaicism and may be bilateral. We recommend prophylactic laparoscopic gonadectomy of streak gonads in patients with TS who carry a Y mosaic genotype, because fertility is not an issue, surgical morbidity is minor and there may be a high potential for malignant transformation of gonadoblastomas in this population.

Mechanisms of Disease: inborn errors of bile acid synthesis

Inborn errors of bile acid synthesis are rare genetic disorders that can present as neonatal cholestasis, neurologic disease or fat-soluble-vitamin deficiencies. There are nine known defects of bile acid synthesis, including oxysterol 7α-hydroxylase deficiency, Δ4-3-oxosteroid-5β-reductase deficiency, 3β-hydroxy-Δ5-C27-steroid dehydrogenase deficiency, cerebrotendinous xanthomatosis (also known as sterol 27-hydroxylase deficiency), α-methylacyl-CoA racemase deficiency, and Zellweger syndrome (also known as cerebrohepatorenal syndrome). These diseases are characterized by a failure to produce normal bile acids and an accumulation of unusual bile acids and bile acid intermediaries. Individuals with inborn errors of bile acid synthesis generally present with the hallmark features of normal or low serum bile acid concentrations, normal γ-glutamyl transpeptidase concentrations and the absence of pruritus. Failure to diagnose any of these conditions can result in liver failure or progressive chronic liver disease. If recognized early, many patients can have a remarkable clinical response to oral bile acid therapy.

Danon disease presenting with dilated cardiomyopathy and a complex phenotype

AbstractX-linked dilated cardiomyopathy (XLCM) was first described in 1987 and associated with dystrophin gene (DMD) mutations a decade later in one of the original two families. Here we report long-term follow-up of the second family (XLCM-2), for which a DMD mutation was never found. Analysis of the lysosome-associated membrane protein-2 (LAMP-2) gene detected a novel mutation, confirming a diagnosis of Danon disease. The broad phenotype in this family included dilated and hypertrophic cardiomyopathy, cardiac pre-excitation, skeletal myopathy with high serum creatine kinase, cognitive impairment (in males), and a pigmentary retinopathy in affected females. Cardiac biopsy specimens showed extensive vacuolar changes in an affected adult male. Remarkably, the skeletal muscle biopsy in a 13-month-old mutation-carrying male showed no vacuolization by standard histology. We conclude that XLCM may be the presenting sign of Danon disease and, in the presence of a familial history of HCM, pre-excitation, skeletal muscle involvement and retinal pigmentary dystrophy should prompt LAMP-2 clinical testing. Furthermore, the absence of vacuolar myopathy in biopsies from young patients may not exclude Danon disease.