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Biomedical subjects

Amy S Paller

Publications and source records attributed to Amy S Paller.

At least 37 records · Page 2Linked to original sources
PubMed2004

New KIT mutations in patients with piebaldism.

BACKGROUND: Piebaldism is an autosomal dominantly inherited disorder characterized by congenital leukoderma, typically on the forehead, abdomen, and knees. The leukoderma is usually stable throughout life. KIT mutations have been demonstrated in about 75% of patients with piebaldism. OBJECTIVES: To identify KIT mutations of the family with piebaldism and examine genotype-phenotype correlations in this disorder. METHODS: PCR-direct-sequencing technique using genomic DNA from peripheral leukocytes. RESULTS: We have studied 10 individuals within six piebaldism families and able to identify six novel mutations in the KIT gene in patients with piebaldism. These include four frameshift mutations: 142delG, 1768-1769delAG, 2139delC, 2246-2249delAAAG, and two missense mutations: M541L, Y870C. CONCLUSIONS: These six new mutations are associated with phenotypes that are well in accordance with our knowledge of genotype-phenotype correlations in KIT.

Adult↗
PubMed2004

Subcutaneous panniculitic T-cell lymphoma in children: response to combination therapy with cyclosporine and chemotherapy.

We describe 2 adolescent boys with facial swelling and/or subcutaneous nodules and fever. Extensive evaluation, including several biopsy specimens, led to a diagnosis of subcutaneous panniculitic T-cell lymphoma, an entity rarely seen in children. Both patients were treated with oral cyclosporine in an effort to suppress the cytokine release from T-cells that has been thought to induce the hemophagocytic syndrome. The patients responded dramatically to cyclosporine treatment with defervescence of the fever and reduction in number and size of the subcutaneous nodules. Subsequent therapy with multidrug chemotherapy achieved complete remission in the first patient. This report suggests the value of cyclosporine as a first-line agent coupled with chemotherapy in the treatment of patients with subcutaneous panniculitic T-cell lymphoma. A clinicopathologic review of 8 described pediatric cases of subcutaneous panniculitic T-cell lymphoma is also presented.

Adolescent↗
PubMed2004

Venous malformations in blue rubber bleb nevus syndrome: variable onset of presentation.

Blue rubber bleb nevus syndrome (BRBNS) is a rare disorder characterized by discrete venous malformations of varying size and appearance that are present on the skin and within the gastrointestinal tract. The characteristic cutaneous lesions consist of deep-blue, soft, rubbery blebs, which are easily compressible. A serious complication is gastrointestinal bleeding. Because venous malformations were described historically as cavernous hemangiomas, the lesions of BRBNS were also inappropriately called hemangiomas in the literature. We describe 3 cases to delineate the venous malformations of BRBNS and to highlight their variable onset of presentation and progression. In one case, a venous malformation was noted during a prenatal ultrasound evaluation at 5 months gestation. The other 2 cases demonstrated a lack of the classic cutaneous lesions at birth. BRBNS consists of multiple venous malformations, rather than hemangiomas as described. Subcutaneous venous malformations may occasionally be the sole presenting finding in patients with this unusual syndrome, and may be evident even in the prenatal period.

Female↗
PubMed2004

Piecing together the puzzle of cutaneous mosaicism.

Autosomal dominant disorders of the skin may present in a pattern following the lines of embryologic development of the ectoderm. In these cases, the surrounding skin is normal, and molecular studies have shown that the causative mutation is confined to the affected ectodermal tissue (type 1 mosaicism). Rarely, an individual shows skin lesions that follow the pattern of type 1 mosaicism, but the rest of the skin shows a milder form of the disorder (type 2 mosaicism). A new study provides the molecular basis for type 2 mosaicism.

Body Patterning↗
PubMed2004

Effectiveness of imiquimod cream 5% for treating childhood molluscum contagiosum in a double-blind, randomized pilot trial.

The safety and effectiveness of imiquimod cream 5% were evaluated in the treatment of molluscum contagiosum (MC) in children. Twenty-three children ranging in age from 1 to 9 years with MC infection were randomized to either imiquimod cream 5% (12 patients) or vehicle (11 patients). Parents applied study drug to patient's lesions 3 times a week for 12 weeks. Patients presented to the clinic every 2 weeks until the end of study (week 12) for safety evaluation and lesion count. Local skin reactions, partial and complete clearances, and lesion counts were statistically analyzed. Partial clearance (> or = 30% clearance of lesions) at weeks 4 and 12 was noted in 58.3% (7/12) and 66.7% (8/12) of imiquimod patients and in 0% (0/11) and 18.2% (2/11) of vehicle patients (imiquimod vs vehicle: week 4, P = .0046; week 12, P = .0361). Complete clearance at week 12 was noted in 33.3% (4/12) of imiquimod patients and in 9.1% (1/11) of vehicle patients. The mean percentage change in lesion count at week 12 was -45.9% in the imiquimod group and +26.9% in the vehicle group. Imiquimod was well tolerated and appears to be a promising therapeutic option in the treatment of MC in children. Larger studies are needed to confirm the results of this small pilot study.

Adjuvants, Immunologic↗
PubMed2003

Ganglioside GM3 blocks the activation of epidermal growth factor receptor induced by integrin at specific tyrosine sites.

The epidermal growth factor receptor (EGFR) can be activated by both direct ligand binding and cross-talk with other molecules, such as integrins. This integrin-mediated cross-talk with growth factor receptors participates in regulating cell proliferation, survival, migration, and invasion. Previous studies have shown that ligand-dependent EGFR activation is inhibited by GM3, the predominant ganglioside of epithelial cells, but the effect of GM3 on ligand-independent, integrin-EGFR cross-talk is unknown. Using a squamous carcinoma cell line we show that endogenous accumulation of GM3 disrupts the ligand-independent association of the integrin beta1 subunit with EGFR and results in inhibition of cell proliferation. Consistently, endogenous depletion of GM3 markedly increases the association of EGFR with tyrosine-phosphorylated integrin beta1 and promotes cell proliferation. The ligand-independent stimulation of EGFR does not require focal adhesion kinase phosphorylation or cytoskeletal rearrangement. Stimulation of EGFR and mitogen-activated protein kinase signaling by GM3 depletion involves the phosphorylation of EGFR at tyrosine residues 845, 1068, and 1148 but not 1086 or 1173. The specific blockade of phosphorylation at Tyr-845 with Src family kinase inhibition and at Tyr-1148 with phosphatidylinositol 3-kinase inhibition suggests that GM3 inhibits integrin-induced, ligand-independent EGFR phosphorylation (cross-talk) through suppression of Src family kinase and phosphatidylinositol 3-kinase signaling.

Cell Line↗
PubMed2003

Mutations in capillary morphogenesis gene-2 result in the allelic disorders juvenile hyaline fibromatosis and infantile systemic hyalinosis.

Juvenile hyaline fibromatosis (JHF) and infantile systemic hyalinosis (ISH) are autosomal recessive syndromes of unknown etiology characterized by multiple, recurring subcutaneous tumors, gingival hypertrophy, joint contractures, osteolysis, and osteoporosis. Both are believed to be allelic disorders; ISH is distinguished from JHF by its more severe phenotype, which includes hyaline deposits in multiple organs, recurrent infections, and death within the first 2 years of life. Using the previously reported chromosome 4q21 JHF disease locus as a guide for candidate-gene identification, we identified and characterized JHF and ISH disease-causing mutations in the capillary morphogenesis factor-2 gene (CMG2). Although CMG2 encodes a protein upregulated in endothelial cells during capillary formation and was recently shown to function as an anthrax-toxin receptor, its physiologic role is unclear. Two ISH family-specific truncating mutations, E220X and the 1-bp insertion P357insC that results in translation of an out-of-frame stop codon, were generated by site-directed mutagenesis and were shown to delete the CMG-2 transmembrane and/or cytosolic domains, respectively. An ISH compound mutation, I189T, is predicted to create a novel and destabilizing internal cavity within the protein. The JHF family-specific homoallelic missense mutation G105D destabilizes a von Willebrand factor A extracellular domain alpha-helix, whereas the other mutation, L329R, occurs within the transmembrane domain of the protein. Finally, and possibly providing insight into the pathophysiology of these diseases, analysis of fibroblasts derived from patients with JHF or ISH suggests that CMG2 mutations abrogate normal cell interactions with the extracellular matrix.

Amino Acid Sequence↗
PubMed2003

Ganglioside GM3 inhibits matrix metalloproteinase-9 activation and disrupts its association with integrin.

Gangliosides GM3 and GT1b both inhibit epithelial cell adhesion and migration on fibronectin. GT1b binds to integrin alpha5beta1 and blocks the integrin-fibronectin interaction; GM3 does not interact with integrin, and its effect is poorly understood. We evaluated the effects of endogenous modulation of GM3 expression on epithelial cell motility on several matrices and the mechanism of these effects. Endogenous accumulation of GM3 decreased cell migration on fibronectin, types I, IV, and VII collagen matrices; depletion of GM3 dramatically increased cell migration, regardless of matrix. GM3 overexpression and depletion in vitro correlated inversely with the expression and activity of matrix metalloproteinase-9; consistently, the cell migration stimulated by GM3 depletion is reversed by inhibition of matrix metalloproteinase-9 activity. Accumulation and depletion of GM3 in epithelial cells grown on fibronectin also correlated inversely with epidermal growth factor receptor and mitogen activated protein kinase phosphorylation and with Jun expression. Ganglioside depletion facilitated the co-immunoprecipitation of matrix metal-loproteinase-9 and integrin alpha5beta1, while endogenous accumulation of GM3, but not GT1b, blocked the co-immunoprecipitation. These data suggest modulation of epidermal growth factor receptor signaling and dissociation of integrin/matrix metalloproteinase-9 as mechanisms for the GM3-induced effects on matrix metalloproteinase-9 function.

Cell Line↗
PubMed2003

Atopic dermatitis and the atopic march.

Atopic dermatitis (AD), one of the most common skin disorders seen in infants and children, usually has its onset during the first 6 months of life. The prevalence of AD is similar in the United States, Europe, and Japan and is increasing, similar to that of other atopic disorders, particularly asthma. AD has been classified into 3 sequential phases: infantile, childhood, and adult, each with characteristic physical findings. AD has a tremendously negative effect on the quality of life of patients as well as family, most commonly disturbing sleep. The condition also creates a great financial burden for both the family and society. The cutaneous manifestations of atopy often represent the beginning of the atopic march. On the basis of several longitudinal studies, approximately half of AD patients will develop asthma, particularly with severe AD, and two thirds will develop allergic rhinitis. Epicutaneous sensitization has been thought to be responsible, with subsequent migration of sensitized T cells into the nose and airways, causing upper and lower airway disease. Animal models and human observation concur with this theory. Preliminary prevention studies with oral antihistamines provide evidence that early intervention might slow the atopic march.

Asthma↗
PubMed2003

Extracellular matrix protein 1 gene (ECM1) mutations in lipoid proteinosis and genotype-phenotype correlation.

The autosomal recessive disorder lipoid proteinosis results from mutations in extracellular matrix protein 1 (ECM1), a glycoprotein expressed in several tissues (including skin) and composed of two alternatively spliced isoforms, ECM1a and ECM1b, the latter lacking exon 7 of this 10-exon gene (ECM1). To date, mutations that either affect ECM1a alone or perturb both ECM1 transcripts have been demonstrated in six cases. However, lipoid proteinosis is clinically heterogeneous with affected individuals displaying differing degrees of skin scarring and infiltration, variable signs of hoarseness and respiratory distress, and in some cases neurological abnormalities such as temporal lobe epilepsy. In this study, we sequenced ECM1 in 10 further unrelated patients with lipoid proteinosis to extend genotype-phenotype correlation and to add to the mutation database. We identified seven new homozygous nonsense or frameshift mutations: R53X (exon 3); 243delG (exon 4); 507delT (exon 6); 735delTG (exon 7); 785delA (exon 7); 892delC (exon 7) and 1190insC (exon 8), as well as two new compound heterozygous mutations: W160X/F167I (exon 6) and 542insAA/R243X (exons 6/7), none of which were found in controls. The mutation 507delT occurred in two unrelated subjects on different ECM1 haplotypes and may therefore represent a recurrent mutation in lipoid proteinosis. Taken with the previously documented mutations in ECM1, this study supports the view that exons 6 and 7 are the most common sites for ECM1 mutations in lipoid proteinosis. Clinically, it appears that mutations outside exon 7 are usually associated with a slightly more severe mucocutaneous lipoid proteinosis phenotype, but neurological features do not show any specific genotype-phenotype correlation.

Adolescent↗
PubMed2003

Topically applied imiquimod inhibits vascular tumor growth in vivo.

Vascular tumors occur in approximately 10% of all infants and may be associated with significant morbidity. Available therapies for vascular tumors, such as systemic corticosteroids, vincristine, and interferon-alpha, may cause toxicity, limiting their use to complicated cases. Using a mouse hemangioendothelioma model, we investigated the efficacy and mechanism of action of imiquimod, a topically applied inducer of cytokines. Application of imiquimod cream, whether initiated at the time of cell inoculation or when tumors became visible, significantly decreased tumor growth and increased animal survival in comparison with control mice. Imiquimod-treated tumors showed decreased tumor cell proliferation, increased tumor apoptosis, and increased expression of tissue inhibitor of matrix metalloproteinase-1 with decreased activity of matrix metalloproteinase-9. The demonstration that local application of imiquimod inhibits vascular tumor enlargement in the mouse vascular tumor model suggests a novel, less toxic means of treating infantile hemangioendotheliomas and perhaps other cutaneous vascular tumors.

Administration, Topical↗