Fetal Supraventricular Tachycardia: Histologic Evidence of Accessory Pathways Due to Incomplete Annulus Fibrosus Formation

BACKGROUND

Atrioventricular (AV) reentrant tachycardia is a common type of supraventricular tachycardia (SVT) that occurs in the fetus and neonate. Although many tachycardias resolve within several weeks of birth or respond to medical management, disruptions in the cardiac annulus fibrosus and development of additional accessory pathways may lead to refractory dysrhythmia resulting in fetal hydrops and ultimately, fetal death.

OBJECTIVES

While accessory pathways have been well documented anatomically in adult and childhood tachyarrhythmias, there are no reports of the histology of these pathways in human fetuses with SVT.

RESEARCH DESIGN, SUBJECTS, MEASURES

This is a small case series of 2 fetuses with a history of SVT that resulted in fetal hydrops.

RESULTS

In both cases, examination of the cardiac conduction system was unremarkable and examination of the atrioventricular junction revealed a focally thinned and/or discontinuous annulus fibrosus with documented direct continuity between the atrial and ventricular myocardium in 1 case.

CONCLUSIONS

This case series demonstrates that thinning or absence of the annulus fibrosus is a feature seen in fetal SVT, and the development of subsequent aberrant AV connections due to defective formation of the annulus fibrosus suggests a possible cause for these arrhythmias.

Normal placental structural anatomy: ultrasound and doppler features elucidated with US-MR image fusion and ferumoxytol-enhanced MRI

PURPOSE

To elucidate ultrasound features of normal placental anatomy through correlation of gray-scale and ultrasound Doppler with ferumoxytol-enhanced MRI features using US-MR image fusion.

METHODS

All patients referred to MR for ultrasound findings worrisome for PAS (placenta accreta spectrum) were included in this retrospective study. MR studies included a ferumoxytol-enhanced T1-weighted MRI. Ultrasound imaging included gray-scale, color Doppler, power Doppler, and spectral Doppler techniques. After the MR, US-MRI fusion was performed by co-registering a MR acquisition to real-time US, which allowed precise, point-to-point correlation of placental features.

RESULTS

Fourteen patients at risk for PAS were studied using the US-MR image fusion. At delivery, there were six cases without PAS (gestational age range: 24 weeks 3 days to 34 weeks 0 days), and these composed the study cohort. Placental features that were on high signal intensity on post-ferumoxytol acquisitions represent spaces with maternal blood flow and corresponded to hypoechoic areas on ultrasound created by a paucity of reflective interfaces (villi). Color and spectral Doppler allowed the separation of maternal and fetal circulations in individual perfusional domains and demonstrated spiral artery inflow, circulation around the villous tree, and return of blood flow to the basal plate. Recognizable histopathologic features by ultrasound included the central cavity, villous tree, and venous return channels.

CONCLUSION

Internal placental architecture can be discerned on ultrasound. This anatomy can be correlated and confirmed with ferumoxytol-MR through US-MR fusion. Understanding this structural anatomy on ultrasound could serve as a basis to identify normal and abnormal placental features.

Ferumoxytol-enhanced magnetic resonance imaging with volume rendering: A new approach for the depiction of internal placental structure in vivo

INTRODUCTION

Placental function is vitally important, but placental assessment is limited by current imaging methods in vivo. The goal of this study is to determine if ferumoxytol-enhanced MR studies might be used to depict placental structure during pregnancy.

METHODS

Ten pregnant women were referred for MRI evaluation of abnormal placentation. The study group was composed five of these patients whose placentas were normal at pathology. MR studies consisted of pre-contrast SSFSE (single-shot fast spin-echo), SSFP (steady-state free procession), diffusion, and ferumoxytol-enhanced acquisitions. The post-contrast sequences were compared to pre-contrast SSFSE, SSFP, and diffusion acquisitions for features of correspondence. MR images were also compared to histopathology for anatomic landmarks including the three-ring pattern of the functional vascular exchange unit (the placentone) created by this central cavity surrounded by a ring of clustered villi, and an outer ring of dispersed villi corresponding to the maternal venous outflow channel. The measured sizes of these features on MR were compared to reported sizes.

RESULTS

Post-ferumoxytol images showed enhancement of the maternal blood within the placenta, notably the intervillous space and the myometrial vessels. The unenhanced fetal vessels were most visible on the MinIP (minimum intensity projection) images; the enhanced maternal vessels were most visible on the MIP (maximum intensity projection) images. Composite MIP/MinIP images show the relation of maternal and fetal circulations. The signal intensities replicate the relative contributions from enhanced maternal blood and unenhanced chorionic villi.

DISCUSSION

Ferumoxytol-enhanced MR imaging can depict the internal anatomy of the placenta in vivo of clarity and detail. This could represent a new diagnostic approach to placental disorders.

Human immune globulin treatment controls Zika viremia in pregnant rhesus macaques

There are currently no approved drugs to treat Zika virus (ZIKV) infection during pregnancy. Hyperimmune globulin products such as VARIZIG and WinRho are FDA-approved to treat conditions during pregnancy such as Varicella Zoster virus infection and Rh-incompatibility. We administered ZIKV-specific human immune globulin as a treatment in pregnant rhesus macaques one day after subcutaneous ZIKV infection. All animals controlled ZIKV viremia following the treatment and generated robust levels of anti-Zika virus antibodies in their blood. No adverse fetal or infant outcomes were identified in the treated animals, yet the placebo control treated animals also did not have signs related to congenital Zika syndrome (CZS). Human immune globulin may be a viable prophylaxis and treatment option for ZIKV infection during pregnancy, however, more studies are required to fully assess the impact of this treatment to prevent CZS.

Zika Virus Infection of Pregnant Ifnar1-/- Mice Triggers Strain-Specific Differences in Fetal Outcomes

Zika virus (ZIKV) is a flavivirus that causes a constellation of adverse fetal outcomes collectively termed congenital Zika syndrome (CZS). However, not all pregnancies exposed to ZIKV result in an infant with apparent defects. During the 2015 to 2016 American outbreak of ZIKV, CZS rates varied by geographic location. The underlying mechanisms responsible for this heterogeneity in outcomes have not been well defined. Therefore, we sought to characterize and compare the pathogenic potential of multiple Asian-/American-lineage ZIKV strains in an established Ifnar1-/- pregnant mouse model. Here, we show significant differences in the rate of fetal demise following maternal inoculation with ZIKV strains from Puerto Rico, Panama, Mexico, Brazil, and Cambodia. Rates of fetal demise broadly correlated with maternal viremia but were independent of fetus and placenta virus titer, indicating that additional underlying factors contribute to fetal outcome. Our results, in concert with those from other studies, suggest that subtle differences in ZIKV strains may have important phenotypic impacts. With ZIKV now endemic in the Americas, greater emphasis needs to be placed on elucidating and understanding the underlying mechanisms that contribute to fetal outcome. IMPORTANCE Zika virus (ZIKV) transmission has been reported in 87 countries and territories around the globe. ZIKV infection during pregnancy is associated with adverse fetal outcomes, including birth defects, microcephaly, neurological complications, and even spontaneous abortion. Rates of adverse fetal outcomes vary between regions, and not every pregnancy exposed to ZIKV results in birth defects. Not much is known about how or if the infecting ZIKV strain is linked to fetal outcomes. Our research provides evidence of phenotypic heterogeneity between Asian-/American-lineage ZIKV strains and provides insight into the underlying causes of adverse fetal outcomes. Understanding ZIKV strain-dependent pathogenic potential during pregnancy and elucidating underlying causes of diverse clinical sequelae observed during human infections is critical to understanding ZIKV on a global scale.

Previous exposure to dengue virus is associated with increased Zika virus burden at the maternal-fetal interface in rhesus macaques

Concerns have arisen that pre-existing immunity to dengue virus (DENV) could enhance Zika virus (ZIKV) disease, due to the homology between ZIKV and DENV and the observation of antibody-dependent enhancement (ADE) among DENV serotypes. To date, no study has examined the impact of pre-existing DENV immunity on ZIKV pathogenesis during pregnancy in a translational non-human primate model. Here we show that macaques with a prior DENV-2 exposure had a higher burden of ZIKV vRNA in maternal-fetal interface tissues as compared to DENV-naive macaques. However, pre-existing DENV immunity had no detectable impact on ZIKV replication kinetics in maternal plasma, and all pregnancies progressed to term without adverse outcomes or gross fetal abnormalities detectable at delivery. Understanding the risks of ADE to pregnant women worldwide is critical as vaccines against DENV and ZIKV are developed and licensed and as DENV and ZIKV continue to circulate.

Dissecting the Cardiac Conduction System: Is It Worthwhile?

BACKGROUND

Pathologic examination of conduction system (CS) is not routinely performed, and histologic changes are mostly reported in forensic practice.

METHODS

We studied the value of dissecting the CS in a cohort of pediatric patients with unexplained sudden death or severe, inexplicable arrhythmias. Histopathologic changes present in CS components were recorded and correlated with findings noted in other cardiac structures.

RESULTS

Twenty-one subjects (11 unexplained sudden deaths and 10 life-threatening arrhythmias) were identified; 18 (86%) had CS pathologic abnormalities. In 13 patients (62%), the CS findings mirrored those found in other cardiac sections (inflammation, allograft vasculopathy, vascular fibromuscular dysplasia, cardiomyopathy-related changes, and tumor/tumor-like conditions). Five cases (24%) had abnormalities restricted to CS (bundle of His [BH] with fibrotic scar and patch material following ventricular septal defect repair, inflammation, BH with fibrosis and calcifications, and intimal fibroplasia of sinoatrial node artery).

CONCLUSIONS

Pathologic changes within the CS are present in a high number of pediatric patients presenting with unexplained sudden death or life-threatening arrhythmias. Frequently, the findings mirror those observed in other cardiac structures. However, in a significant number of cases (24%), the changes are restricted to CS and likely explain the patients' symptoms or cause of death, suggesting that systematic dissection of CS unveils valuable information.

Spondweni virus causes fetal harm in Ifnar1-/- mice and is transmitted by Aedes aegypti mosquitoes

Spondweni virus (SPONV) is the most closely related known flavivirus to Zika virus (ZIKV). Its pathogenic potential and vector specificity have not been well defined. SPONV has been found predominantly in Africa, but was recently detected in a pool of Culex quinquefasciatus mosquitoes in Haiti. Here we show that SPONV can cause significant fetal harm, including demise, comparable to ZIKV, in a mouse model of vertical transmission. Following maternal inoculation, we detected infectious SPONV in placentas and fetuses, along with significant fetal and placental histopathology, together suggesting vertical transmission. To test vector competence, we exposed Aedes aegypti and Culex quinquefasciatus mosquitoes to SPONV-infected bloodmeals. Aedes aegypti could efficiently transmit SPONV, whereas Culex quinquefasciatus could not. Our results suggest that SPONV has the same features that made ZIKV a public health risk.

The Placental Distal Villous Hypoplasia Pattern: Interobserver Agreement and Automated Fractal Dimension as an Objective Metric

The distal villous hypoplasia (DVH) pattern is a placental correlate of fetal growth restriction. Because the pattern seems to involve less complexity than do appropriately developed placental villi, we postulated that it may be associated with lower fractal dimension-a mathematical measure of complexity. Our study objectives were to evaluate interobserver agreement related to the DVH pattern among expert pathologists and to determine whether pathologist classification of DVH correlates with fractal dimension. A study set of 30 images of placental parenchyma at ×4 magnification was created by a single pathologist from a digital slide archive. The images were graded for the DVH pattern according to pre-specified definitions and included 10 images graded as "no DVH" (grade  =  0), 10 with mild to moderate DVH (grade  =  1), and 10 with severe DVH (grade  =  2). The images were randomly sorted and shown to a panel of 4 international experts who similarly graded the images for DVH. Weighted kappas were calculated. For each image, fractal dimension was calculated by the Box Counting method. The correlation coefficient between (1) the averaged DVH scores obtained by the 5 pathologists and (2) fractal dimension was calculated. The mean weighted kappa score among the observers was 0.59 (range: 0.42-0.70). The correlation coefficient between fractal dimension and the averaged DVH score was -0.915 (P < 0.001). Expert pathologists achieve fair to substantial agreement in grading DVH, indicating consensus on the definition of DVH. Distal villous hypoplasia correlates extremely well with fractal dimension and represents an objective measure for DVH.

Osteochondroma With Contiguous Bronchogenic Cyst of the Scapula

Osteochondroma is a benign bone tumor composed of a bony protrusion with an overlying cartilage cap. Osteochondromas arise in the scapula in 3% to 5% of cases, making them the most common benign bone tumor in this location. Scapular osteochondromas cause various pathologies of the shoulder girdle, including snapping scapula syndrome, chest wall deformity, shoulder impingement, and bursa formation. Bronchogenic cyst is an exceedingly rare finding in the periscapular area. It is a congenital cystic mass lined by tracheobronchial structures and respiratory epithelium. To our knowledge, there are no reports of a contiguous osteochondroma and bronchogenic cyst. A 12-month-old boy presented with an incidentally noted mass on the spine of the scapula, which drained scant, clear fluid through an adjacent pinprick-sized hole. Imaging revealed an exostosis with an adjacent cystic mass. The mass and cyst were excised en bloc, and histopathologic examination confirmed the diagnosis of osteochondroma with contiguous bronchogenic cyst. In this case, we present the report of a novel dual lesion.

Placental mesenchymal dysplasia without fetal development in a twin gestation: a case report and review of the spectrum of androgenetic biparental mosaicism

We report a dichorionic twin gestation with diffuse placental mesenchymal dysplasia (PMD) and androgenetic biparental mosaicism (ABM) involving one twin's placenta with complete absence of fetal development for that twin. To our knowledge, this is the 1st reported case of PMD without fetal development. We discuss the gross, histologic, and genetic hallmarks of PMD and the spectrum of variability depending on degree and distribution of ABM.

Recurrent massive perivillous fibrin deposition in the placenta associated with fetal renal tubular dysgenesis: case report and literature review

Massive perivillous fibrin deposition (MPVFD) of the placenta and renal tubular dysgenesis (RTD) are relatively rare diseases with potential recurrent risks that have not previously associated in the literature. Herein, we report the clinical course, autopsy findings, and placental pathologic features from 3 consecutive pregnancies delivered in 1 woman, all showing recurrent MPVFD in the placenta and RTD in the bilateral fetal kidneys.

Pathologic Examination of Fetal and Placental Tissue Obtained by Dilation and Evacuation

Context.—Dilation and evacuation (D&E) is an alternative method to induction of labor for pregnancy termination and intrauterine fetal demise, and it is the most common mode of second-trimester uterine evacuation in the United States. Many D&E specimens are examined in surgical pathology, and there is little information available in surgical pathology textbooks or the literature to assist pathologists in these examinations.

Objective.—To provide an overview of the D&E procedure, discuss related legal issues, provide guidelines for routine pathologic examination of D&E specimens, and demonstrate the importance of careful pathologic examination of D&E specimens.

Data Sources.—Case-derived material and literature review.

Conclusions.—Pathologic examination of D&E specimens has been understudied. However, the available literature and our experience support the fact that careful pathologic examination of D&E specimens can identify significant fetal and placental changes that can confirm clinical diagnoses or provide definitive diagnosis, assist in explaining the cause of intrauterine fetal demise, and identify unexpected anomalies that may provide further clues to a diagnostic syndrome or mechanism of anomaly formation.

Predicting relapse in favorable histology Wilms tumor using gene expression analysis: a report from the Renal Tumor Committee of the Children's Oncology Group

PURPOSE

The past two decades has seen significant improvement in the overall survival of patients with favorable histology Wilms tumor (FHWT); however, this progress has reached a plateau. Further improvements may rely on the ability to better stratify patients by risk of relapse. This study determines the feasibility and potential clinical utility of classifiers of relapse based on global gene expression analysis.

EXPERIMENTAL DESIGN

Two hundred fifty FHWT of all stages enriched for relapses treated on National Wilms Tumor Study-5 passed quality variables and were suitable for analysis using oligonucleotide arrays. Relapse risk stratification used support vector machine; 2- and 10-fold cross-validations were applied.

RESULTS

The number of genes associated with relapse was less than that predicted by chance alone for 106 patients (32 relapses) with stages I and II FHWT treated with chemotherapy, and no further analyses were done. This number was greater than expected by chance for 76 local stage III patients. Cross-validation including an additional 68 local stage III patients (total 144 patients, 53 relapses) showed that classifiers for relapse composed of 50 genes were associated with a median sensitivity of 47% and specificity of 70%.

CONCLUSIONS

This study shows the feasibility and modest accuracy of stratifying local stage III FHWT using a classifier of <50 genes. Validation using an independent patient population is needed. Analysis of genes differentially expressed in relapse patients revealed apoptosis, Wnt signaling, insulin-like growth factor pathway, and epigenetic modification to be mechanisms important in relapse. Potential therapeutic targets include FRAP/MTOR and CD40.

High Histone Acetylation and Decreased Polycomb Repressive Complex 2 Member Levels Regulate Gene Specific Transcriptional Changes During Early Embryonic Stem Cell Differentiation Induced by Retinoic Acid

Histone modifications play a crucial role during embryonic stem (ES) cell differentiation. During differentiation, binding of polycomb repressive complex 2 (PRC2), which mediates trimethylation of lysine 27 on histone H3 (K27me3), is lost on developmental genes that are transcriptionally induced. We observed a global decrease in K27me3 in as little as 3 days after differentiation of mouse ES cells induced by retinoic acid (RA) treatment. The global levels of the histone K27 methyltransferase EZH2 also decreased with RA treatment. A loss of EZH2 binding and K27me3 was observed locally on PRC2 target genes induced after 3 days of RA, including Nestin. In contrast, direct RA-responsive genes that are rapidly induced, such as Hoxa1, showed a loss of EZH2 binding and K27me3 after only a few hours of RA treatment. Following differentiation induced by leukemia inhibitor factor (LIF) withdrawal without RA, Hoxa1 was not transcriptionally activated. Small interfering RNA-mediated knockdown of EZH2 resulted in loss of K27me3 during LIF withdrawal, but the Hoxa1 gene remained transcriptionally silent after loss of this repressive mark. Induction of histone hyperacetylation overrode the repressive K27me3 modification and resulted in Hoxa1 gene expression. Together, these data show that there are multiple temporal phases of derepression of PRC2 target genes during ES cell differentiation and that other epigenetic marks (specifically, increased acetylation of histones H3 and H4), in addition to derepression, are important for gene-specific transcriptional activation. This report demonstrates the temporal interplay of various epigenetic changes in regulating gene expression during early ES cell differentiation.

Chromatin context dominates estrogen regulation of pS2 gene expression

Chromatin structure and transcription factor activity collaborate to set the transcription level of a gene. Our understanding of the relative contributions of each of these factors at a specific gene is limited. We studied the effects of an altered chromatin environment on the activity of the estrogen-responsive pS2 promoter. We created stable cell lines with the pS2 promoter situated in an alternative chromatin site in addition to it being in its native site. Both promoters were estrogen-responsive for estrogen receptor alpha (ERalpha) recruitment, but transcription was inducible only at the native site. At the recombinant site, transcription was high and constitutive. Higher histone H3 and H4 acetylation (acH3 and acH4), as well as trimethylated lysine 4 on histone H3 levels, was observed at the recombinant site compared to the native site in vehicle treated cells. Inhibition of histone deacetylases (HDACs) resulted in increased acH4, but only modest increases in acH3, ERalpha binding and basal transcription at the native pS2 site. Inhibiting HDACs had no effect on transcription from the recombinant site. These data suggest that highly active chromatin is not only permissive for transcription, but can override the requirement for the transcription factor at an inducible promoter.

Fraser syndrome: affected siblings born to nonconsanguineous parents and diagnosed at autopsy

Fraser syndrome (MIM 219000) is a rare genetic disorder with major features including cryptophthalmos, syndactyly, and genital anomalies. We report 2 independently autopsied children of the same nonconsanguineous parents. The siblings exhibit similar clinical features, all of which are consistent with a diagnosis of Fraser syndrome. The gross and microscopic findings provide insight into the highly variable clinical presentation of Fraser syndrome. Molecular diagnostic studies of the index case failed to identify one of the known gene mutations in the FRAS1 and FREM2 genes associated with Fraser syndrome. This raises the possibility that other genes or undetected mutations in the FRAS1/FREM2 genes may cause Fraser syndrome.

The DNA binding domain of estrogen receptor alpha is required for high-affinity nuclear interaction induced by estradiol

Estrogen receptor alpha (ER) is a member of the nuclear hormone receptor family, which upon binding estrogen shows increased apparent affinity for nuclear components (tight nuclear binding). The nuclear components that mediate this tight nuclear binding have been proposed to include both ER-DNA interactions and ER-protein interactions. In this paper, we demonstrate that tight nuclear binding of ER upon estrogen occupation requires ER-DNA interactions. Hormone-bound ER can be extracted from the nucleus in low-salt buffer using various polyanions, which mimic the phosphate backbone of DNA. The importance of specific ER-DNA interactions in mediating tight nuclear binding is also supported by the 380-fold lower concentration of the ERE oligonucleotide necessary to extract estrogen-occupied ER from the nucleus compared to the polyanions. We also demonstrate that estrogen-induced tight nuclear binding requires both the nuclear localization domain and the DNA binding domain of ER. Finally, enzymatic degradation of nuclear DNA allows us to recover 45% of tight nuclear-bound ER. We further demonstrate that ER-AIB1 interaction is not required for estrogen-induced tight nuclear binding. Taken together, we propose a model in which tight nuclear binding of the estrogen-occupied ER is predominantly mediated by ER-DNA interactions. The effects of estrogen binding on altering DNA binding in whole cells are proposed to occur through estrogen-induced changes in ER-chaperone protein interactions, which alter the DNA accessibility of ER but do not directly change the affinity of the ER for DNA, which is similar for both unoccupied and occupied ER.

The role of histone acetylation in regulating early gene expression patterns during early embryonic stem cell differentiation

We have examined the role of histone acetylation in the very earliest steps of differentiation of mouse embryonic stem cells in response to withdrawal of leukemia inhibitory factor (LIF) as a differentiation signal. The cells undergo dramatic changes in morphology and an ordered program of gene expression changes representing differentiation to all three germ layers over the first 3-5 days of LIF withdrawal. We observed a global increase in acetylation on histone H4 and to a lesser extent on histone H3 over this time period. Treatment of the cells with trichostatin A (TSA), a histone deacetylase inhibitor, induced changes in morphology, gene expression, and histone acetylation that mimicked differentiation induced by withdrawal of LIF. We examined localized histone acetylation in the regulatory regions of genes that were transcriptionally either active in undifferentiated cells, induced during differentiation, or inactive under all treatments. There was striking concordance in the histone acetylation patterns of specific genes induced by both TSA and LIF withdrawal. Increased histone acetylation in local regions correlated best with induction of gene expression. Finally, TSA treatment did not support the maintenance or progression of differentiation. Upon removal of TSA, the cells reverted to the undifferentiated phenotype. We concluded that increased histone acetylation at specific genes played a role in their expression, but additional events are required for maintenance of differentiated gene expression and loss of the pluripotent state.

Dynamic Changes in Histone H3 Phosphoacetylation during Early Embryonic Stem Cell Differentiation Are Directly Mediated by Mitogen- and Stress-activated Protein Kinase 1 via Activation of MAPK Pathways

Embryonic stem (ES) cells are pluripotent cells capable of unlimited self-renewal and differentiation into the three embryonic germ layers under appropriate conditions. Mechanisms for control of the early period of differentiation, involving exit from the pluripotent state and lineage commitment, are not well understood. An emerging concept is that epigenetic histone modifications may play a role during this early period. We have found that upon differentiation of mouse ES cells by removal of the cytokine leukemia inhibitory factor, there is a global increase in coupled histone H3 phosphorylation (Ser-10)-acetylation (Lys-14) (H3 phosphoacetylation). We show that this occurs through activation of both the extracellular signal-regulated kinase (ERK) and p38 MAPK signaling pathways. Early ES cell differentiation is delayed using pharmacological inhibitors of the ERK and p38 pathways. One common point of convergence of these pathways is the activation of the mitogen- and stress-activated protein kinase 1 (MSK1). We show here that MSK1 is the critical mediator of differentiation-induced H3 phosphoacetylation using both the chemical inhibitor H89 and RNA interference. Interestingly, inhibition of H3 phosphoacetylation also alters gene expression during early differentiation. These results point to an important role for both epigenetic histone modifications and kinase pathways in modulating early ES differentiation.

Activation of Wnt/beta-catenin signaling in distinct histologic subtypes of human germ cell tumors

The molecular signaling pathways mediating human germ cell tumor (GCT) formation and progression are poorly understood despite a large number of studies detailing recurrent cytogenetic abnormalities. Germ cell tumors consist of multiple histologic subtypes and can also be divided into infantile/childhood or adolescent/adult tumors as well as gonadal or nongonadal sites of origin. All of these parameters are important in defining clinical outcome and in understanding the pathogenesis of these tumors. We utilized complementary DNA (cDNA) microarray analysis to identify differences in signal transduction pathways between 2 histologic subtypes of malignant ovarian GCTs (dysgerminomas versus ovarian endodermal sinus tumors). Hierarchical cluster analysis using only the genes involved in Wnt/beta-catenin signaling was able to distinguish these 2 tumor subtypes from each other. Wnt13 and beta-catenin showed significant differential expression patterns between the 2 tumor subtypes, and the results were confirmed by semiquantitative reverse transcriptase-polymerase chain reaction. Additional GCTs were studied for the expression of other members of Wnt/beta-catenin signaling, including Wnt13, frizzled, disheveled, low-density lipoprotein receptor-related protein 6, and beta-catenin. Differential expression levels were identified for several histologic subtypes of human GCTs. Finally, we prepared tissue microarrays containing GCTs from 83 different patients and demonstrated high levels of beta-catenin protein expression in 100% and nuclear accumulation in approximately 50% to 70% of all endodermal sinus tumors and immature teratomas (ITs). This pattern was independent of the patient's age. No nuclear accumulation of beta-catenin was observed in germinomas, embryonal carcinomas, or choriocarcinomas. These results indicate that activation of Wnt/beta-catenin signaling plays an important role in the pathogenesis of 2 histologic subtypes of human GCTs.

Differentiation of murine embryonic stem cells induces progesterone receptor gene expression

The role of steroid hormone receptors in very early embryonic development remains unknown. Clearly, expression during organogenesis is important for tissue-specific development. However, progesterone receptor (PR) and estrogen receptors (ERalpha, ERbeta) are expressed during early development through the blastocyst stage in mice and other species, and yet are not essential for embryonic viability. We have utilized the mouse embryonic stem (mES) cell model to investigate the regulated expression of these receptors during differentiation. Surprisingly, one of the earliest changes in gene expression in response to a differentiation signal observed is PR gene induction. It parallels the time course of expression for the patterning genes Hoxb1 and Hoxa5. Unexpectedly, PR gene expression is not regulated in an estrogen-dependent manner by endogenous ERs or by transiently overexpressed ERalpha. Our results suggest a potentially novel mechanism of PR gene regulation within mES cells compared to adult tissues and the possibility of unique targets of PR action during early mES cell differentiation.

Transcription factor accessibility and histone acetylation of the progesterone receptor gene differs between parental MCF-7 cells and a subline that has lost progesterone receptor expression

The human progesterone receptor (PgR) gene has a complex promoter that produces alternate mRNAs encoding the PgRA (94 kDa) and PgRB (120 kDa) protein isoforms. Expression of PgR is induced by estradiol (E(2)) in the breast, reproductive tract and many cell lines despite the lack of a classical estrogen responsive element (ERE) in the promoter regions. We employed chromatin immunoprecipitation (ChIP) to analyze the sites of estrogen receptor alpha (ERalpha) and Sp1 occupancy of the PgR promoters in vivo. We also assessed the functional relevance of histone acetylation levels on the accessibility of transcription factors to the promoter and subsequent hormone-induced transcription. We utilized MCF-7 human breast cancer cells that express PgR in response to E(2) and the MCF-7 derived C4 cell strain that has lost PgR expression as a model system. We found that promoter-wide levels of histone acetylation were not decreased in C4 cells, but that access was partially blocked for Sp1 and completely blocked for ERalpha. The basal level of histone acetylation at six localized regions of the promoter did show some differences between cell lines, but it did not correlate with transcription factor binding. Furthermore, we found only a modest and highly localized change in histone acetylation levels in response to E(2) at only one of three sites of ERalpha binding in MCF-7 cells. This was at the B1 site at the distal 5' end of the promoter. This site also showed a significant decrease in basal histone acetylation in C4 compared to MCF-7 cells. We speculate that the histone acetylation level at this site may be a marker for chromatin structure that affects the access of transcription factors to the whole promoter.

Genetic and genetic expression analyses of clear cell sarcoma of the kidney

Clear cell sarcoma of the kidney (CCSK) represents a significant diagnostic and clinical challenge. In search of diagnostically useful or biologically significant genetic abnormalities, we screened 30 CCSKs from the National Wilms Tumor Study Group. Genetic gains and losses were analyzed using comparative genomic hybridization; loss of heterozygosity at 11p15 was studied using microsatellite analysis. Loss of imprinting (LOI) was studied using allele-specific expression or methylation analysis at the ApaI polymorphic site for IGF2, AluI and RsaI sites for H19, and Cfo I site for SNRPN. Comparative genomic hybridization analysis revealed quantitative abnormalities in only 4 of 30 CCSKs. Two showed gain of 1q, one also showed loss of 10q, and the other also showed loss of terminal 4p. The other two cases demonstrated chromosome 19 loss and chromosome 19p gain, respectively. All 22 cases informative for 11p15 showed retention of both alleles. Of 14 CCSKs informative for IGF2, six showed biallelic expression; all three CCSKs informative for H19 exhibited monoallelic expression. The normal imprint pattern was present in all six CCSKs analyzed for SNRPN methylation. These data demonstrate an absence of consistent genetic gains or losses in CCSKs using these methods. The high frequency of LOI for IGF2 in CCSKs (43%) is comparable to that reported in Wilms tumors. The retention of imprinting at the SNRPN and H19 loci confirm that LOI is not a ubiquitous epigenetic change. This suggests that IGF2, a potent growth factor, may play a role in the development or progression of CCSK.

Performance characteristics of a reverse transcriptase-polymerase chain reaction assay for the detection of tumor-specific fusion transcripts from archival tissue

Pediatric small round cell tumors still pose tremendous diagnostic problems. In difficult cases, the ability to detect tumor-specific gene fusion transcripts for several of these neoplasms, including Ewing sarcoma/peripheral primitive neuroectodermal tumor (ES/PNET), synovial sarcoma (SS), alveolar rhabdomyosarcoma (ARMS), and desmoplastic small round cell tumor (DSRCT) using reverse transcriptase-polymerase chain reaction (RT-PCR), can be extremely helpful. Few studies to date, however, have systematically examined several different tumor types for the presence of multiple different fusion transcripts in order to determine the specificity and sensitivity of the RT-PCR method, and no study has addressed this issue for formalin-fixed material. The objectives of this study were to address the specificity, sensitivity, and practicality of such an assay applied strictly to formalin-fixed tissue blocks. Our results demonstrate that, for these tumors, the overall sensitivity for detecting each fusion transcript is similar to that reported in the literature for RT-PCR on fresh or formalin-fixed tissues. The specificity of the assay is very high, being essentially 100% for each primer pair when interpreting the results from visual inspection of agarose gels. However, when these same agarose gels were examined using Southern blotting, a small number of tumors also yielded reproducibly detectable weak signals for unexpected fusion products, in addition to a strong signal for the expected fusion product. Fluorescence in situ hybridization (FISH) studies in one such case indicated that a rearrangement that would account for the unexpected fusion was not present, while another case was equivocal. The overall specificity for each primer pair used in this assay ranged from 94 to 100%. Therefore, RT-PCR using formalin-fixed paraffin-embedded tissue sections can be used to detect chimeric transcripts as a reliable, highly sensitive, and highly specific diagnostic assay. However, we strongly suggest that the final interpretation of the results from this assay be viewed in light of the other features of the case, including clinical history, histology, and immunohistochemistry, by the diagnostic pathologist. Additional studies such as FISH may be useful in clarifying the nature of equivocal or unexpected results.

Genetic analysis of mediastinal nonseminomatous germ cell tumors in children and adolescents

Primary mediastinal germ cell tumors (M-GCTs) represent a heterogeneous group of tumors that varies with regard to age at presentation, histologic differentiation, and outcome. We retrospectively analyzed archival tissue samples of mediastinal mature and immature teratomas (n = 15) and malignant nonseminomatous M-GCTs (n = 20) with comparative genomic hybridization (CGH). The aim of this study was to define distinct genetic subgroups of M-GCT among the pediatric cohort that may differ in their clinical behavior and prognosis. All pure teratomas showed normal CGH profiles. Malignant M-GCTs in infants and children < 8 years old most frequently showed a gain of 1q, 3, and 20q and a loss of 1p, 4q, and 6q. Gain of 12p and sex chromosomal abnormalities were not observed in this age group. In contrast, the gain of 12p was the most common aberration in M-GCTs that arose in children > or = 8 years old. Additional recurrent changes included the loss of chromosome 13 and the gain of chromosome 21. All ten adolescents with malignant M-GCT were male, and five showed a gain of the X chromosome. In two of these five patients, Klinefelter syndrome was confirmed by cytogenetic analysis or by fluorescence in situ hybridization (FISH). In conclusion, CGH analysis of M-GCTs defines distinct genetic subgroups. Mediastinal teratomas show no genetic gains or losses. Malignant M-GCTs in children < 8 years old show the same pattern of gains and losses identified in sacrococcygeal and testicular GCTs at this age, and they lack sex-chromosomal abnormalities. Malignant M-GCTs in children > or = 8 years old show the same genetic profile previously reported in gonadal GCTs at this age. In addition, approximately 50% demonstrate a gain of the X chromosome, consistent with Klinefelter syndrome. Cooperative group studies reveal a significantly better prognosis of malignant M-GCT arising in infants compared to that in adolescents, suggesting that these genetic differences are associated with differences in clinical behavior.

Deletion mapping of 6q21-26 and frequency of 1p36 deletion in childhood endodermal sinus tumors by microsatellite analysis

The most common malignant germ cell tumor of early childhood is the endodermal sinus tumor (CEST), also known as yolk sac tumor. Previous cytogenetic studies of CEST have demonstrated recurrent deletion of distal regions of chromosomes 1p and 6q. Studies utilizing comparative genomic hybridization have likewise demonstrated loss of distal 6q, however these studies show discrepant data concerning chromosome 1 abnormalities. This study analyses 18 CESTs for loss of heterozygosity (LOH) of distal chromosome 6q utilizing 17 microsatellite markers and 13 tumors were analysed for LOH of distal 1p using two microsatellite markers. LOH of 6q was found in 13/18 tumors (72 %). This data confirms that loss of genetic material on 6q is one of the most common abnormalities in CESTs and narrows the region of loss, enabling candidate tumor suppressor genes to be identified and analysed. In addition, LOH of 1p36 was identified in five of 11 informative tumors, clarifying prior conflicting data and confirming that 1p deletion is a common event in CESTs.

Multipoint imprinting analysis indicates a common precursor cell for gonadal and nongonadal pediatric germ cell tumors

Pediatric germ cell tumors (GCTs) commonly arise at extragonadal sites. It has been proposed that nongonadal GCTs arise from ectopic primordial germ cells that have aberrantly migrated during embryogenesis. During a time between their migration and development to mature gametes, primordial germ cells are characterized by their lack of imprinting, which can be assessed by the evaluation of allelic gene expression and DNA methylation in differentially methylated control regions. To elucidate the cellular origin of nongonadal GCTs, we evaluated the imprinting status of 21 gonadal and 21 nongonadal pediatric GCTs. Allele-specific H19 and IGF-2 expression was assessed with reverse transcription-PCR followed by digestion at polymorphic restriction sites. DNA methylation was evaluated after bisulfite modification, PCR amplification, and restriction digestion at a consistently methylated CpG dinucleotide within the 5' flanking region of the SNRPN gene. These results were compared with genetic gains and losses determined by comparative genomic hybridization. Seven of 15 informative tumors showed biallelic H19 expression, and 8 of 17 informative tumors showed biallelic IGF-2 expression. The frequency of biallelic gene expression was comparable in gonadal and nongonadal GCTs. Sixteen of 19 gonadal GCTs and 17 of 21 nongonadal GCTs showed absence of methylation of SNRPN consistent with loss of imprinting. One testicular GCT and three nongonadal GCTs showed a somatic methylation pattern. Two ovarian teratomas and one mediastinal teratoma showed only methylated SNRPN, consistent with entry into meiosis. Twenty-one of 22 non-GCT control samples showed a somatic methylation pattern. Gonadal and nongonadal germ cell tumors are derived from primordial germ cells that have consistently lost the imprinting of SNRPN and partly lost imprinting of H19 and IGF-2. Because the imprinting pattern of the latter genes differs from that found in testicular GCTs of adult patients, our data suggest that pediatric GCTs arise from a different stage of germ cell development.

Patterns of congenital lower urinary tract obstructive uropathy: relation to abnormal prostate and bladder development and the prune belly syndrome

The pathogenesis of lower urinary tract obstruction is disputed, particularly its relation to both abnormal prostatic development and the prune belly syndrome (PBS). In an attempt to clarify this issue we examined 11 males (17-38 weeks gestation) with PBS who were autopsied at our institution. The lower urinary tract was embedded intact and prepared as serial histologic sections. Of the 11 cases, 8 demonstrated mechanical obstruction of the lower urinary tract. In five of these eight cases, a "flap-valve" structure was formed by an abnormal angulation between the prostatic and penile portions of the urethra. These had dilated, thin-walled bladders and prostates and moderate to severe renal dysplasia. One of the eight cases had a valve-like obstruction at the level of the mid-prostatic urethra associated with a complex cloacal malformation and a thin-walled bladder, another case had an epithelial plug at the penile meatus, and the last of the eight cases had a posterior urethral valve. The three remaining cases showed no mechanical obstruction. However, each had megacystis with marked thickening, interstitial fibrosis, and disarray of smooth muscle bundles in the bladder wall. In 10 cases, the prostate had no or only sparse, flattened glands. These results suggest that the abnormal development of the prostate in PBS may be explained as a pressure-induced dysplasia rather than a primary maldevelopment. The findings further suggest that abnormal prostatic development and the prune belly syndrome may arise from either anatomic obstruction of various types or functional obstruction from megacystis.

Genetic analysis of childhood germ cell tumors with comparative genomic hybridization

BACKGROUND

Germ Cell Tumors (GCTs) in children and adolescents constitute a clinically and histologically heterogeneous group of tumors. Compared to GCTs in adults, the numbers of GCTs in children analyzed with cytogenetic and molecular genetic techniques is limited. However, the data available to date reveal a pattern of cytogenetic aberrations different from that in adults. Comparative genomic hybridization (CGH) is a valuable technique for the genetic profiling of tumors that allows screening for chromosomal imbalances consistent with amplification of oncogenes and loss of putative tumor suppressor genes. As CGH does not require tissue culture, it also allows analysing archival tissue samples.

PATIENTS

This study focuses exclusively on GCTs in children younger than ten years of age and summarizes the genetic data of 51 tumors. Eighteen teratomas and 33 malignant GCTs were included. Primary sites were the testis (n=10), coccyx (n=13), mediastinum (n=20), ovary (n=5), CNS (n=2), and the face (n=1).

METHODS

The experimental procedure includes differential enzymatic fluorescence labeling of tumor and control DNA followed by comparative hybridization to normal male chromosomes, karyotyping and computerized analysis of the fluorescence profiles.

RESULTS

With the exception of one testicular and two ovarian tumors, malignant GCTs in children do not show chromosomal gain of 12p, which is characteristic of GCTs in adult patients. Irrespective of the primary site, childhood GCTs show chromosomal imbalances of chromosome 1 (loss of distal 1p, gain of 1q), deletion of 4q and 6q as well as gain of 20q at a high frequency.

CONCLUSIONS

These studies will help guiding further investigations elucidating the role of putative tumor suppressor genes at e.g. 1p36 and 6q. In addition, further studies incorporated in prospective therapeutic protocols are necessary to evaluate the prognostic relevance of specific genetic aberrations.

Primary cardiac gastrinoma causing Zollinger-Ellison syndrome

Primary cardiac tumors are rare, and there are no reports of patients with a functional gastroenteropancreatic tumor syndrome caused by such a tumor. This case report describes a patient with a cardiac gastrinoma causing Zollinger-Ellison syndrome. Evidence is presented that this tumor represents a primary cardiac tumor. The exact identification of this gastrinoma in an extra-abdominal site was facilitated by the use of [111In-DTPA-DPhe1]octreotide scanning for somatostatin receptors, which these tumors characteristically possess in high numbers. The recent availability of this novel localization method may facilitate identification of extra-abdominal sites in an increasing proportion of patients with gastrinomas and related neuroendocrine functional tumors in which no intra-abdominal primary tumor is currently found.

Probable nuclear precursors of preprolactin mRNA in rat pituitary cells

In the rat pituitary, several species of preprolactin (pPrl) mRNA larger than the mature mRNA have been reported (Maurer, R. A., Gubbins, E. J., Erwin, C. R., and Donelson, J. E. (1980) J Biol. Chem. 255, 2243-2246). We examined the size distribution of pPrl transcripts in nuclear, cytoplasmic, and nuclear poly(A)-containing RNA from rat pituitary tumor MtTW10 and from the pituitaries of diethylstilbestrol-treated Fischer 344 X Holtzman rats. RNA was electrophoresed in agarose/2.2 M formaldehyde horizontal slab gels, transferred to diazobenzyloxymethyl paper or to nitro-cellulose paper, and hybridized with a nick-translated recombinant DNA probe containing rat pPrl cDNA sequences. Up to 8 putative precursor mRNA molecules were detected which were from 2 to 13 times the length of mature pPrl mRNA. Three of these RNA species were larger than the maximum size of putative precursors previously reported. These probable precursors were nuclear in origin and polyadenylated, at least in the case of pituitary tumor cells. The largest molecule, 14 kilobase pairs long, may approximate the size of the initial transcript of the prolactin gene.