Umadevi Tantravahi

Homology of lubricin and superficial zone protein (SZP): products of megakaryocyte stimulating factor (MSF) gene expression by human synovial fibroblasts and articular chondrocytes localized to chromosome 1q25.

We have previously identified megakaryocyte stimulating factor (MSF) gene expression by synovial fibroblasts as the origin of lubricin in the synovial cavity. Lubricin is a mucinous glycoprotein responsible for the boundary lubrication of articular cartilage. MSF has a significant homology to vitronectin and is composed of 12 exons. RNA was purified from human synovial fibroblasts and articular chondrocytes grown in vitro from tissue explants obtained from subjects without degenerative joint disease. RT‐PCR was used with multiple complimentary primer pairs spanning the central mucin expressing exon 6 of the MSF gene and individual exons on both the N‐ and C‐terminal sides of exon 6. Exons 2, 4 and 5 appear to be variably expressed by synovial fibroblasts and articular chondrocytes. Lubricating mucin, in the form of MSF, is expressed by both chondrocytes and synovial fibroblasts in vitro. Both lubricin and superficial zone protein (SZP), a related proteoglycan, share a similar primary structure but could differ in post‐translational modifications with O‐linked oligosaccharides which are predominant in lubricin and with limited amounts chondroitin and keratan sulfate found in SZP. Since most of the MSF exons are involved in the expression of lubricating mucin, a strong homology to vitronectin persists. It is therefore appropriate to consider that both SZP and lubricin occupy a new class of biomolecules termed tribonectins. Screening of a human genome bacterial artificial chromsome (BAC) library with a cDNA primer pair complimentary for exon 6 identified two clones. Both clones were complimentary for chromosome 1q25 by in situ hybridization. This same locus was previously implicated in camptodactyl‐arthropathy‐pericarditis syndrome (CAP) by genetic mapping. It is hypothesized that CAP, a large joint arthropathy, may be associated with ineffective boundary lubrication provided by synovial fluid.

Herceptin and Gemcitabine for Metastatic Pancreatic Cancers That Overexpress HER-2/neu

Purpose: To determine the response rate and toxicities of Herceptin and gemcitabine for patients with metastatic pancreatic adenocarcinomas that overexpress HER-2/neu. Methods and Materials: Patients with metastatic pancreatic cancer with 2 +/3 + HER-2/neu expression by immunohistochemistry were eligible. Patients received gemcitabine, 1 g/m2/week, for 7 of 8 weeks followed by 3 of every 4 weeks, and Herceptin, 4 mg/kg loading dose, followed by 2 mg/kg/week. Results: Screening logs demonstrated the rate of HER-2/neu overexpression was 16%. Thirty-four patients were enrolled. Thirty patients (88%) had pancreatic cancers with 2 + overexpression and 4 patients (12%) had 3 + overexpression. Toxicity was similar to gemcitabine alone. Confirmed partial responses were observed in 2 of 32 patients (6%). Thirteen of 32 patients (41%) had either a partial response or a > 50% reduction in CA 19–9. The median survival for all 34 patients was 7 months, and the 1-year survival was 19%. Conclusion: The response rate of Herceptin and gemcitabine is similar to gemcitabine alone. The 7-month median survival in patients with metastatic pancreatic cancer suggests there may be a modest benefit for some patients. Infrequent HER-2/neu overexpression limits the role of targeting the HER-2/neu gene and prevents definitive conclusions on the addition of Herceptin to gemcibine for patients with pancreatic cancer.

Functional genomic analysis of amniotic fluid cell-free mRNA suggests that oxidative stress is significant in Down syndrome fetuses

To characterize the differences between second trimester Down syndrome (DS) and euploid fetuses, we used Affymetrix microarrays to compare gene expression in uncultured amniotic fluid supernatant samples. Functional pathway analysis highlighted the importance of oxidative stress, ion transport, and G protein signaling in the DS fetuses. Further evidence supporting these results was derived by correlating the observed gene expression patterns to those of small molecule drugs via the Connectivity Map. Our results suggest that there are secondary adverse consequences of DS evident in the second trimester, leading to testable hypotheses about possible antenatal therapy for DS.

Microarray Analysis of Cell-Free Fetal DNA in Amniotic Fluid: a Prenatal Molecular Karyotype

Metaphase karyotype analysis of fetal cells obtained by amniocentesis or chorionic villus sampling is the current standard for prenatal cytogenetic diagnosis, particularly for the detection of trisomy 21. We previously demonstrated that large quantities of cell-free fetal DNA (cffDNA) are easily extracted from amniotic fluid (AF). In this study, we explored potential clinical applications of AF cffDNA by testing its ability to hybridize to DNA microarrays for comparative genomic hybridization (CGH) analysis. cffDNA isolated from 11 male fetuses showed significantly increased hybridization signals on SRY and decreased signals on X-chromosome markers, compared with female reference DNA. cffDNA isolated from six female fetuses showed the reverse when compared with male reference DNA. cffDNA from three fetuses with trisomy 21 had increased hybridization signals on the majority of the chromosome 21 markers, and cffDNA from a fetus with monosomy X (Turner syndrome) had decreased hybridization signals on most X-chromosome markers, compared with euploid female reference DNA. These results indicate that cffDNA extracted from AF can be analyzed using CGH microarrays to correctly identify fetal sex and aneuploidy. This technology facilitates rapid screening of samples for whole-chromosome changes and may augment standard karyotyping techniques by providing additional molecular information.

Trastuzumab, paclitaxel, cisplatin, and radiation for adenocarcinoma of the esophagus: a phase I study.

PURPOSE To conduct a phase I study incorporating trastuzumab with paclitaxel, cisplatin, and radiation for adenocarcinoma of the esophagus. METHODS AND MATERIALS Patients with adenocarcinoma of the esophagus without distant organ metastases were eligible. All patients received cisplatin 25 mg/m2 and paclitaxel 50 mg/m2 weekly for 6 weeks with radiation 50.4 Gy. HER-2/neu-positive patients (2+/3+ by immunohistochemistry) received weekly trastuzumab at dose levels of 1, 1.5, or 2 mg/kg weekly for 5 weeks after an initial bolus of 2, 3, or 4 mg/kg, respectively. HER-2/neu-negative patients received the same chemoradiation without trastuzumab as a control for toxicity. Dose-limiting toxicities were defined as grade 3 esophageal, cardiac, or pulmonary toxicity. RESULTS Twelve of 36 screened patients (33%) overexpressed HER-2/neu by immunohistochemistry (seven 3+ and five 2+). Eight of 12 patients with HER-2/neu overexpression by IHC had an increase in the number of HER-2/neu genes, six from amplification of the HER-2/ neu gene and two were hypderdiploid for chromosome 17. Thirty patients were enrolled (12 HER-2/neu-positive and 18 HER-2/neu-negative controls). No increase in toxicity was seen with the addition of trastuzumab. One of 12 patients in the trastuzumab arm and 8 of 17 in the control arm had grade 3 esophagitis (p < or = .026). Mean left ventricular ejection fraction for the trastuzumab group was 57% before treatment and 56% after treatment. CONCLUSION HER-2/neu is overexpressed in approximately one-third of esophageal adenocarcinomas. Trastuzumab can be added at full dose to cisplatin, paclitaxel, and radiation. Future studies of trastuzumab in esophageal adenocarcinoma are indicated.

Periventricular nodular heterotopia and Williams syndrome.

We report here on the first case of a child with bilateral periventricular nodular heterotopia (PNH) and Williams syndrome. Fluorescent in situ hybridization (FISH) analyses demonstrated a deletion of the elastin gene in the Williams syndrome critical region (WSCR). Further mapping by loss of heterozygosity analysis both by microsatellite marker and SNP profiling demonstrated a 1.5 Mb deletion beyond the telomeric end of the typical WSCR. No mutations were identified in the X‐linked filamin‐A gene (the most common cause of PNH). These findings suggest another dominant PNH disorder along chromosome 7q11.23.

Attitudes Toward Cystic Fibrosis Carrier and Prenatal Testing and Utilization of Carrier Testing Among Relatives of Individuals with Cystic Fibrosis

A questionnaire and an offer of free carrier testing was mailed to 173 relatives of individuals with CF. The questionnaire addressed their knowledge of clinical and genetic aspects of CF, as well as their attitudes toward carrier testing, prenatal diagnosis, and pregnancy termination for CF. Eighty-one individuals returned the questionnaire (47%) and 50 elected carrier testing (29%). Most respondents underestimated their carrier risk (60%), but overestimated their risk to have a child with CF (63%). Most (93%) indicated they would utilize carrier testing, and 70% would use prenatal testing; however, only 7% would consider terminating a pregnancy for CF. The intention to use prenatal testing was correlated with the perceived health of the proband and whether the respondent was planning to have (more) children. The acceptability of abortion was correlated with the respondents perceived impact or burden of CF.

Transcriptomic Analysis of Cell-Free Fetal RNA Suggests a Specific Molecular Phenotype in Trisomy 18

Trisomy 18 is a common human aneuploidy that is associated with significant perinatal mortality. Unlike the well-characterized “critical region” in trisomy 21 (21q22), there is no corresponding region on chromosome 18 associated with its pathogenesis. The high morbidity and mortality of affected individuals has limited extensive investigations. In order to better understand the molecular mechanisms underlying the congenital anomalies observed in this condition, we investigated the in utero gene expression profile of second trimester fetuses affected with trisomy 18. Total RNA was extracted from cell-free amniotic fluid supernatant from aneuploid fetuses and euploid controls matched for gestational age and hybridized to Affymetrix U133 Plus 2.0 arrays. Individual differentially expressed transcripts were obtained by two-tailed t tests. Over-represented functional pathways among these genes were identified with DAVID and Ingenuity® Pathways Analysis. Results show that three hundred and fifty-two probe sets representing 251 annotated genes were statistically significantly differentially expressed between trisomy 18 and controls. Only 7 genes (2.8% of the annotated total) were located on chromosome 18, including ROCK1, an up-regulated gene involved in valvuloseptal and endocardial cushion formation. Pathway analysis indicated disrupted function in ion transport, MHCII/T cell mediated immunity, DNA repair, G-protein mediated signaling, kinases, and glycosylation. Significant down-regulation of genes involved in adrenal development was identified, which may explain both the abnormal maternal serum estriols and the pre and postnatal growth restriction in trisomy 18. Comparison of this gene set to one previously generated for trisomy 21 fetuses revealed only six overlapping differentially regulated genes. This study contributes novel information regarding functional developmental gene expression differences in fetuses with trisomy 18.

Fas-Ligand-Induced Apoptosis of Respiratory Epithelial Cells Causes Disruption of Postcanalicular Alveolar Development

Premature infants are at risk for bronchopulmonary dysplasia, a complex condition characterized by impaired alveolar development and increased alveolar epithelial apoptosis. The functional involvement of pulmonary apoptosis in bronchopulmonary dysplasia- associated alveolar disruption remains undetermined. The aims of this study were to generate conditional lung-specific Fas-ligand (FasL) transgenic mice and to determine the effects of FasL-induced respiratory epithelial apoptosis on alveolar remodeling in postcanalicular lungs. Transgenic (TetOp)(7)-FasL responder mice, generated by pronuclear microinjection, were bred with Clara cell secretory protein (CCSP)-rtTA activator mice. Doxycycline (Dox) was administered from embryonal day 14 to postnatal day 7, and lungs were studied between embryonal day 19 and postnatal day 21. Dox administration induced marked respiratory epithelium-specific FasL mRNA and protein up-regulation in double-transgenic CCSP-rtTA(+)/(TetOp)(7)-FasL(+) mice compared with single-transgenic CCSP-rtTA(+) littermates. The Dox-induced FasL up-regulation was associated with dramatically increased apoptosis of alveolar type II cells and Clara cells, disrupted alveolar development, decreased vascular density, and increased postnatal lethality. These data demonstrate that FasL-induced alveolar epithelial apoptosis during postcanalicular lung remodeling is sufficient to disrupt alveolar development after birth. The availability of inducible lung-specific FasL transgenic mice will facilitate studies of the role of apoptosis in normal and disrupted alveologenesis and may lead to novel therapeutic approaches for perinatal and adult pulmonary diseases characterized by dysregulated apoptosis.

Genetic and phenotypic diversity of NHE6 mutations in Christianson syndrome

Recently, Christianson syndrome (CS) has been determined to be caused by mutations in the X‐linked Na+/H+ exchanger 6 (NHE6). We aimed to determine the diagnostic criteria and mutational spectrum for CS.