Kara E Snider

William Penn University, Filadelfia, Pennsylvania, United States

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Publications (11)42.27 Total impact

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    ABSTRACT: Context:Congenital hyperinsulinism (HI) occurs in2 distinct histologic forms: diffuse and focal. Distinguishing between them is essential because a pancreatectomy is curative for focal HI and palliative for diffuse HI.Objective:The purpose of this study was to compare the presentations, treatment, and outcomes of diffuse and focal HI.Design:A retrospective chart review of children who underwent pancreatectomy for hyperinsulinism from December 2004 through September 2012 was conducted.Results:Based on pancreatic histology, 223 children were classified into 3 groups: diffuse (n = 97, 43%), focal (n = 114, 51%), and other (n = 12, 5%). Children with diffuse vs focal HI had significantly different mean gestational ages (38 vs 39 weeks, P < .0005) and birth weights (3963 vs 3717 g P = .012). Children with focal cases presented at an older age (0.3 vs 0 months, P < .0005) and more frequently with seizures (50 vs 25%, P < .0005). Children with diffuse cases had higher insulin levels during hypoglycemia (31.8 vs 12 μU/mL, P < .0005) and required higher glucose infusion rates (19.2 vs 16.1 mg/kg/min, P = .002). Children with diffuse cases had a median pancreatectomy rate of 98%, and postoperatively 41% required treatment for continued hypoglycemia. Children with focal cases had a median pancreatectomy rate of 27, and 94% required no treatment after surgery.Conclusions:Focal and diffuse HI present unique challenges, but the clinical differences between the 2 are subtle. Children with focal HI are at higher risk of delayed diagnosis and hypoglycemic seizures, but most are cured with surgery. In contrast, children with diffuse disease may be identified earlier, but face ongoing blood glucose abnormalities.
    The Journal of Clinical Endocrinology and Metabolism 09/2013; 98(11). DOI:10.1210/jc.2013-2094 · 6.31 Impact Factor
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    ABSTRACT: Abstract Insulin autoimmune syndrome (IAS) or Hirata's disease is a rare cause of hyperinsulinemic hypoglycemia. We report the case of a child with a mild, atypical presentation of IAS. A previously healthy girl, aged 7 years old, developed non-ketotic fasting hypoglycemia during treatment for pneumonia. Laboratory evaluation during hypoglycemia showed the following results: serum glucose, 32 mg/dL (1.8 mmol/L); insulin, 5.6 μIU/mL (38.9 pmol/L); C-peptide, 1.4 ng/mL (0.47 nmol/L); anti-insulin antibody, 6.2% (normal, <2.4%); absence of ketonuria; and positive glucagon stimulation test result. Search for mutation in genes ABCC8, KCNJ11, GLUD1 and MEN1 was negative. Human leukocyte antigen (HLA) typing was HLA-DRB1*1104. Computed tomography scan of the abdomen showed a normal result. The patient evolved with spontaneous resolution of the hypoglycemia, within 30 days, with normalization of serum anti-insulin titers. The serum levels of insulin and anti-insulin antibodies in the patient of this report were not extremely high as previously reported. This novel, mild, or forme fruste presentation of IAS expands the previously reported spectrum of this disease.
    Journal of pediatric endocrinology & metabolism: JPEM 07/2013; 26(11-12):1-4. DOI:10.1515/jpem-2013-0215 · 0.71 Impact Factor
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    ABSTRACT: Context:Hypoglycemia due to congenital hyperinsulinism (HI) is caused by mutations in 9 genes.Objective:Our objective was to correlate genotype with phenotype in 417 children with HI.Methods:Mutation analysis was carried out for the ATP-sensitive potassium (KATP) channel genes (ABCC8 and KCNJ11), GLUD1, and GCK with supplemental screening of rarer genes, HADH, UCP2, HNF4A, HNF1A, and SLC16A1.Results:Mutations were identified in 91% (272 of 298) of diazoxide-unresponsive probands (ABCC8, KCNJ11, and GCK), and in 47% (56 of 118) of diazoxide-responsive probands (ABCC8, KCNJ11, GLUD1, HADH, UCP2, HNF4A, and HNF1A). In diazoxide-unresponsive diffuse probands, 89% (109 of 122) carried KATP mutations; 2% (2 of 122) had GCK mutations. In mutation-positive diazoxide-responsive probands, 42% were GLUD1, 41% were dominant KATP mutations, and 16% were in rare genes (HADH, UCP2, HNF4A, and HNF1A). Of the 183 unique KATP mutations, 70% were novel at the time of identification. Focal HI accounted for 53% (149 of 282) of diazoxide-unresponsive probands; monoallelic recessive KATP mutations were detectable in 97% (145 of 149) of these cases (maternal transmission excluded in all cases tested). The presence of a monoallelic recessive KATP mutation predicted focal HI with 97% sensitivity and 90% specificity.Conclusions:Genotype to phenotype correlations were most successful in children with GLUD1, GCK, and recessive KATP mutations. Correlations were complicated by the high frequency of novel missense KATP mutations that were uncharacterized, because such defects might be either recessive or dominant and, if dominant, be either responsive or unresponsive to diazoxide. Accurate and timely prediction of phenotype based on genotype is critical to limit exposure to persistent hypoglycemia in infants and children with congenital HI.
    The Journal of Clinical Endocrinology and Metabolism 12/2012; 98(2). DOI:10.1210/jc.2012-2169 · 6.31 Impact Factor
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    ABSTRACT: Congenital hyperinsulinism (CHI) occurs as a consequence of unregulated insulin secretion from the pancreatic beta-cells. Severe recessive mutations and milder dominant mutations have been described in the ABCC8 and KCNJ11 genes encoding SUR1 and Kir6.2 subunits of the beta-cell ATP-sensitive K(+) channel. Here we report two patients with CHI unresponsive to medical therapy with diazoxide. Sequencing analysis identified a compound heterozygous mutation in ABCC8 in both patients. The first one, is a carrier for the known mild dominant mutation p.Glu1506Lys jointly with the novel mutation p.Glu1323Lys. The second carries the p.Glu1323Lys mutation and a second novel mutation, p.Met1394Arg. Functional studies of both novel alleles showed reduced or null cell surface expression, typical of recessive mutations. Compound heterozygous mutations in congenital hyperinsulinism result in complex interactions. The studying of these mechanisms can improve the knowledge of this disease and modify its therapy.
    Gene 12/2012; 516(1). DOI:10.1016/j.gene.2012.12.055 · 2.08 Impact Factor
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    ABSTRACT: It has been suggested that xenoestrogens, a group of agents termed endocrine disruptors, may contribute to the development of hormone-dependent cancers, such as breast and endometrial cancers. We previously demonstrated that the xenoestrogen, bisphenol A (BPA), was able to induce the transformation in vitro of human breast epithelial cells. The normal-like human breast epithelial cell line, MCF-10F, formed tubules in collagen (3-D cultures), although after treatment with BPA (10-5 M and 10-6 M BPA) the cells produced less tubules (73% and 80%, respectively) and some spherical masses (27% and 20%, respectively). In the present study, expression and DNA methylation analyses were performed in these cells after exposure to BPA. These cells showed an increased expression of BRCA1, BRCA2, BARD1, CtIP, RAD51 and BRCC3, all of which are genes involved in DNA repair, as well as the downregulation of PDCD5 and BCL2L11 (BIM), both of which are involved in apoptosis. Furthermore, DNA methylation analysis showed that the BPA exposure induced the hypermethylation of BCL2L11, PARD6G, FOXP1 and SFRS11, as well as the hypomethylation of NUP98 and CtIP (RBBP8). Our results indicate that normal human breast epithelial cells exposed to BPA have increased expressions of genes involved in DNA repair in order to overcome the DNA damage induced by this chemical. These results suggest that the breast tissue of women with BRCA1 or BRCA2 mutations could be more susceptible to the effects of BPA.
    International Journal of Oncology 07/2012; 41(1):369-77. DOI:10.3892/ijo.2012.1444 · 3.03 Impact Factor
  • Kara E. Snider · Hormoz Ehya · Jose Russo · Sandra V. Fernandez
    Cancer Research 07/2011; 71(8 Supplement):75-75. DOI:10.1158/1538-7445.AM2011-75 · 9.28 Impact Factor
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    ABSTRACT: Congenital hyperinsulinemic hypoglycemia is a group of genetic disorders of insulin secretion most commonly associated with inactivating mutations of the β-cell ATP-sensitive K(+) channel (K(ATP) channel) genes ABCC8 (SUR1) and KCNJ11 (Kir6.2). Recessive mutations of these genes cause hyperinsulinism that is unresponsive to treatment with diazoxide, a channel agonist. Dominant K(ATP) mutations have been associated with diazoxide-responsive disease. We hypothesized that some medically uncontrollable cases with only one K(ATP) mutation might have dominant, diazoxide-unresponsive disease. Mutations of the K(ATP) genes were identified by sequencing genomic DNA. Effects of mutations on K(ATP) channel function in vitro were studied by expression in COSm6 cells. In 15 families with diazoxide-unresponsive diffuse hyperinsulism, we found 17 patients with a monoallelic missense mutation of SUR1. Nine probands had de novo mutations, two had an affected sibling or parent, and four had an asymptomatic carrier parent. Of the 13 different mutations, 12 were novel. Expression of mutations revealed normal trafficking of channels but severely impaired responses to diazoxide or MgADP. Responses were significantly lower compared with nine SUR1 mutations associated with dominant, diazoxide-responsive hyperinsulinism. These results demonstrate that some dominant mutations of SUR1 can cause diazoxide-unresponsive hyperinsulinism. In vitro expression studies may be helpful in distinguishing such mutations from dominant mutations of SUR1 associated with diazoxide-responsive disease.
    Diabetes 06/2011; 60(6):1797-804. DOI:10.2337/db10-1631 · 8.47 Impact Factor
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    ABSTRACT: Epigenetic inactivation of genes by DNA hypermethylation plays an important role in carcinogenesis. An in vitro model of human breast epithelial cell transformation was used to study epigenetic changes induced by estradiol during the neoplastic process. Different stages of tumor initiation and progression are represented in this model being MCF-10F the normal stage; trMCF cells, the transformed stage; bsMCF cells, the invasive stage and, caMCF cells, the tumor stage. Global methylation studies by restriction landmark genomic scanning (RLGS) showed an increased DNA methylation during the in the invasive and tumor stages. Expression studies showed that NRG1 (neuregulin 1), CSS3 (chondroitin sulfate synthase 3) and SNIP (SNAP-25-interacting protein) were downregulated in the invasive and tumor cells. The transformed cells showed low expression of STXBP6 (amysin) compared to the parental cells MCF-10F. The treatment of these cells with the demethylating agent 5-aza-dC alone or in combination with the histone deacetylase inhibitor trichostatin increased the expression of NRG1, STXBP6, CSS3 and SNIP confirming that DNA methylation plays an important role in the regulation of the expression of these genes. The NRG1 exon 1 has a region located between -136 and +79 (considering +1, the translational initiation site) rich in CpG sites that was analyzed by methylation specific PCR (MSP). NRG1 exon 1 showed progressive changes in the methylation pattern associated with the progression of the neoplastic process in this model; NRG1 exon 1 was unmethylated in MCF-10F and trMCF cells, becoming hypermethylated in the invasive (bsMCF) and tumor (caMCF) stages. Studies of human breast tissue samples showed that NRG1 exon 1 was partially methylated in 14 out of 17 (82.4%) invasive carcinomas although it was unmethylated in normal tissues (8 out of 10 normal breast tissue samples). Furthermore, NRG1 exon 1 was partially methylated in 9 out of 14 (64.3%) morphologically normal tissue samples adjacent to invasive carcinomas.
    Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis 02/2010; 688(1-2):28-35. DOI:10.1016/j.mrfmmm.2010.02.007 · 4.44 Impact Factor
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    Jose Russo · Kara Snider · Julia S Pereira · Irma H Russo
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    ABSTRACT: There is evidence that in the human breast there is a stem cell population that can give rise to many different cell types and have the unique potential to divide asymmetrically. In this way stem cells maintain the stem cell pool and simultaneously generate committed cells that reconstitute the organ for example for preparing the breast for a new pregnancy after the involution from a previous pregnancy and lactation process. In addition to the in vivo models of mammary morphogenesis there are in vitro systems that are more amenable to study in critically determined conditions the ductulogenic pattern of growth of the breast epithelia. Primary mammary epithelial cells grown in collagen matrix are able to form tree-like structures resembling in vivo ductulogenesis. The human breast epithelial cells MCF-10F formed tubules when grown in type I collagen and we demonstrated that treatment of these cells with 17β-estradiol (E(2)) induces phonotypical changes indicative of neoplastic transformation. The transformation of MCF-10F by E(2) is associated with impaired ductal morphogenesis by altering the stem cells unique potential to divide asymmetrically inducing formation of solid masses mimicking intraductal carcinoma that progress to invasive and tumorigenic phenotype. In the present work we present evidence for the mechanism of cell asymmetry leading to normal ductulogenesis and how the normal stem cell is transformed to cancer stem cell by altering this process. Furthermore, we demonstrate that the carcinogenic agent, in this case E(2), induces a defect in the asymmetric cell division program of the normal mammary stem cell.
    Hormone molecular biology and clinical investigation 01/2010; 1(2):53-65. DOI:10.1515/HMBCI.2010.011
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    ABSTRACT: Human chorionic gonadotropin (hCG), a hormone produced during pregnancy, can elicit life-long refractoriness to carcinogenesis by differentiation of the breast epithelium. Human breast epithelial cells MCF-10F form tubules in collagen, mimicking the normal ductules. We have shown that 17 β-estradiol (E2) alter the ductulogenic pattern of these cells. The effect of the recombinant hCG (rhCG) in vitro was evaluated on the transformation of MCF-10F induced by E2. MCF-10F cells were treated with 70 nM E2 alone or in combination with 50 IU/ml rhCG during 2 weeks, while the controls were treated with DMSO (the solvent in which E2 was dissolved) or rhCG alone. At the end of treatment, the cells were plated in type I collagen matrix (3D-cultures) for detecting 2 main phenotypes of cell transformation, namely the loss of ductulogenic capacity and the formation of solid masses. Although E2 significantly increased solid mass formation, this effect was prevented when MCF-10F cells were treated with E2 in combination with rhCG. Furthermore, E2 increased the main duct width (p < 0.001), and caused a disruption of the luminal architecture, whereas rhCG increased the length of the tubules (p < 0.001) and produced tertiary branching. In conclusion, rhCG was able to abrogate the transforming abilities of estradiol, and had the differentiating property by increasing the branching of the tubules formed by breast epithelial cells in collagen. These results further support our hypothesis, known as the terminal differentiation hypothesis of breast cancer prevention, that predicts that hCG treatment results in protection from tumorigenic changes by the loss of susceptible stem cells 1 through a differentiation to refractory stem cells 2 and increase differentiation of the mammary gland.
    Cell Biology International 01/2009; 33(11-33):1135-1143. DOI:10.1016/j.cellbi.2009.07.002 · 1.64 Impact Factor
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Publication Stats

107 Citations
42.27 Total Impact Points

Institutions

  • 2013
    • William Penn University
      Filadelfia, Pennsylvania, United States
  • 2011–2013
    • The Children's Hospital of Philadelphia
      • Division of Endocrinology and Diabetes
      Filadelfia, Pennsylvania, United States
  • 2009–2012
    • Fox Chase Cancer Center
      • Breast Cancer Research Laboratory
      Filadelfia, Pennsylvania, United States