Mark Luquette

Endogenous production of heparin-binding EGF-like growth factor during murine partial-thickness burn wound healing.

Heparin-binding EGF-like growth factor (HB-EGF), a potent epithelial cell mitogen, has been identified in human burn blister fluid and excised human burn wounds. Topical application of HB-EGF to murine partial-thickness scald burns accelerated reepithelialization, increased keratinocyte proliferation, and enhanced production of endogenous transforming growth factor-alpha in the healing wounds. The goal of the present study was to examine the production of endogenous HB-EGF and transforming growth factor-alpha (TGF-alpha) in a murine partial-thickness scald burn model. Keratinocyte proliferation was assessed by 5-bromo-deoxyuridine incorporation, and tissue sections were examined by in situ hybridization for HB-EGF mRNA expression and by immunohistochemistry for HB-EGF and TGF-alpha production. HB-EGF mRNA expression and production of HB-EGF and TGF-alpha proteins by both marginal surface keratinocytes and hair follicle epithelial cells reached a maximum by postburn day five and decreased thereafter. This corresponded to the peak period of keratinocyte proliferation. We conclude that HB-EGF and TGF-alpha act in conjunction to stimulate wound healing following thermal injury.

Acceleration of Partial-thickness Burn Wound Healing with Topical Application of Heparin-binding Egf-like Growth Factor (hb-egf)

Heparin-binding EGF-like growth factor has been identified in human burn-wound fluid and in the epithelial cells of excised human partial-thickness burns. In the present study, the effect of heparin-binding EGF-like growth factor on burn-wound healing was evaluated by incorporating purified, recombinant heparin-binding EGF-like growth factor into slow-release cholesterol-lecithin pellets that were applied topically to partial-thickness burns in mice. Both experimental (heparin-binding EGF-like growth factor-treated) and control (untreated) mice were sacrificed on days 3, 5, and 10 after burn. Total burn-wound area, histology, keratinocyte proliferation, and in situ hybridization analysis for transforming growth factor-alpha were determined for each wound. The mean wound area of the experimental group on day 5 after burn was 1.07 cm2, compared with 2.20 cm2 for controls (p=0.04). Cellular proliferation (as measured by immunohistochemical detection of 5-Bromo-2-deoxyuridine) on day 5 after burn in marginal keratinocytes and follicular epithelial cells was greater in the experimental group than in the control group. In situ hybridization showed up-regulation of transforming growth factor-alpha mRNA levels in experimental animals by day 5 after burn. Topical application of heparin-binding EGF-like growth factor significantly accelerates the reepithelialization of murine partial-thickness burns, increases keratinocyte proliferative activity, and enhances production of endogenous transforming growth factor-alpha mRNA.

Immunohistochemical localization of heparin-binding epidermal growth factor-like growth factor in normal skin and skin cancers

SummaryHeparin-binding epidermal growth factor (EGF)-like growth factor is a 22-kDa glycoprotein that was originally identified as a secreted product of cultured human macrophages. Although the growth factor mRNA has been identified in various cells and tissues, the tissue distribution of the protein itself has rarely been demonstrated. In this study, the EGF-like growth factor was detected immunohistochemically in a variety of human skin samples by indirect immunofluorescence using a polyclonal rabbit antiserum raised against residues 26–41 of mature heparin-binding EGF. The keratinocytes of a variety of epithelium-derived structures demonstrated reproducible, specific staining for the EGF. In normal tissues, this staining was prominent in the basal cells of the epidermis and in the epithelial cells lining epidermal appendages such as hair follicles, sebaceous sweat glands and eccrine sweat glands. In addition, specific staining was detected in skin cancers derived from the basal epithelial cell layer, including basal and squamous cell carcinomas of the skin, with no staining detected in melanoma specimens. Immunoreactive heparin-binding EGF was characteristically associated with the surface of cells. With minor exceptions, the immunoreactive sites are identical to the known EGF receptor distribution in the skin, and suggest that keratinocyte-derived heparin-binding EGF may act in concert with other EGF family members in processes such as skin morphogenesis and wound repair, as well as in the development of skin cancers

Heparin-Binding EGF-Like Growth Factor Decreases Inducible Nitric Oxide Synthase and Nitric Oxide Production After Intestinal Ischemia/Reperfusion Injury

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) has been shown to protect intestine from ischemia/reperfusion (I/R) injury in vivo and to down-regulate inducible nitric oxide synthase (iNOS) and nitric oxide (NO) production in intestinal epithelial cells in vitro. The present study was undertaken to investigate whether HB-EGF could modulate the iNOS/NO axis after total midgut I/R injury in rats. I/R injury induced a significant increase in iNOS gene expression (quantified by real-time RT-PCR) and protein production (detected by western blots), as well as elevation of serum NO levels (measured by chemiluminescence assay). Nitrotyrosine (NT) and iNOS production colocalized immunohistochemically, with positive staining found mainly in villous and crypt epithelial cells, as well as ganglion cells. Intraluminal administration of HB-EGF 45 min after the start of a 90-min ischemic interval significantly decreased I/R-induced iNOS gene expression and protein production, as well as serum NO levels. Immunohistochemically, HB-EGF administration led to elimination of iNOS and NT staining in crypt epithelial cells and ganglion cells, with only weak staining that remained in villous epithelial cells. Thus, HB-EGF protects the intestine from I/R injury, at least partially, through down-regulation of the iNOS/NO/NT pathway, a mechanism that is central to I/R injury in multiple organ systems.

Congenital Muscular Dystrophy With Complete Laminin-α2-Deficiency, Cortical Dysplasia, and Cerebral White-Matter Changes in Children

Congenital muscular dystrophy consists of Fukuyama congenital muscular dystrophy, Walker-Warburg syndrome, muscle-eye-brain disease, and occidental congenital muscular dystrophy, which is further divided into laminin-α2-positive and laminin-α2-negative subgroups. These forms of congenital muscular dystrophy are frequently associated with abnormal white-matter changes, whereas the Fukuyama form, Walker-Warburg syndrome, and muscle-eye-brain disease are also frequently found to have polymicrogyria. We now report two infants with complete laminin-α2-deficiency who have not only abnormal cerebral white-matter lesions, but also bioccipital polymicrogyria. There are significant similarities in the clinical and cerebral manifestations among the various types of congenital muscular dystrophy. The diagnosis of the Fukuyama form, laminin-α2-deficiency, Walker-Warburg syndrome, and muscle-eye-brain disease cannot always be established on radiological studies alone. (J Child Neurol 1998;13:253-256)

Mitochondrial DNA Depletion in Children

The first girl of an unrelated couple was noted to have failure to thrive since age 3 months, generalized hypotonia and weakness, hepatomegaly, hypoglycemia, and lactic acidosis at 4 months. She was found to have severe mitochondrial DNA (mtDNA) depletion and respiratory chain complex IV deficiency in both skeletal muscle and liver but without other common mtDNA mutations. Her younger brother developed vomiting at age 3 weeks and was diagnosed as having pyloric stenosis. His skeletal muscle and liver also showed severe mtDNA depletion. He developed generalized weakness and hypotonia, hepatomegaly, and lactic acidosis at age 3 months. Both siblings died of hepatic failure and hemorrhagic complication before 6 months of age. The brother also had chemical pancreatitis, which had not been reported before in mtDNA depletion in children. Severe mtDNA depletion may present with nonspecific symptoms such as vomiting, failure to thrive, and developmental delay; multiorgan involvement such as hepatomegaly, pancreatitis, and myopathy occurs later. Mitochondrial DNA depletion should be considered in the differential diagnosis in children with developmental delay or failure to thrive of unknown etiology. (J Child NeuroL 2000;15:822-824).

Cystic degeneration of heterotopic pancreas

Abstract The case of a large cyst arising from heterotopically-situated pancreatic tissue in an 11-month-old girl is reported. This is the first published report of childhood pancreatic cyst that developed in heterotopic pancreatic tissue. There is strong evidence to suggest that the cyst became symptomatic as a result of secondary infection, an additional unreported phenomenon. This case serves to underscore the fact that pancreatic cysts should be considered in the differential diagnosis of intestinal duplication cysts of childhood.

Massive hemoptysis as the presenting manifestation in a child with histoplasmosis shaffer et al. Massive hemoptysis

A previously healthy and asymptomatic 7‐year‐old white boy presented with a history of two episodes of hemoptysis productive of bright red blood in the 5 days preceding admission. After admission he developed massive hemoptysis that, on bronchoscopy, was noted to be emanating from the right lower lobe. An emergency right lower lobe resection was done. Pathological examination revealed hilar adenopathy and peripheral lesions with caseating granulomas containing yeast, morphologically consistent with Histoplasma capsulatum. Pediatr. Pulmonol. 1997;24:57–60.

Myasthenia Gravis and Associated Autoimmune Diseases in Children

Myasthenia gravis has been associated with other autoimmune disorders. We report two children with myasthenia gravis and another autoimmune disease: an 18-month-old boy with ocular myasthenia gravis and Hashimotos disease and a 14-year-old girl presenting with autoimmune polymyositis, then generalized myasthenia gravis 2 years later. The rare combinations of myasthenia gravis and Hashimotos disease or polymyositis in children are discussed, and we also briefly review myasthenia gravis and other associated autoimmune diseases in children. (J Child Neurol 2000;15:767-769).

Mitochondrial respiratory-chain defects presenting as nonspecific features in children

Patients with mitochondrial respiratory-chain defects frequently exhibit lactic acidosis, ragged red fibers in skeletal muscle samples, and abnormal enzyme assays for the respiratory-chain complex. However, ragged red fibers and lactic acidosis are not always seen in all patients with mitochondrial respiratory-chain defects. We have encountered six children with biochemically proven respiratory chain defects, but typical ragged red fibers were not found in all six patients, and only five patients had increased serum lactate levels. Initially, they present with nonspecific features. However, persistent or progressive clinical features or multiple organ involvement eventually led to the diagnosis of respiratory-chain defects in these patients. Mitochondrial respiratory-chain defects should be considered in the differential diagnosis when persistent, progressive features and especially multiple organ involvement occur. (J Child Neurol 2000;15:445-448).