Defining RNA oligonucleotides that reverse deleterious phase transitions of RNA-binding proteins with prion-like domains

RNA-binding proteins with prion-like domains, such as FUS and TDP-43, condense into functional liquids, which can transform into pathological fibrils that underpin fatal neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS)/frontotemporal dementia (FTD). Here, we define short RNAs (24-48 nucleotides) that prevent FUS fibrillization by promoting liquid phases, and distinct short RNAs that prevent and, remarkably, reverse FUS condensation and fibrillization. These activities require interactions with multiple RNA-binding domains of FUS and are encoded by RNA sequence, length, and structure. Importantly, we define a short RNA that dissolves aberrant cytoplasmic FUS condensates, restores nuclear FUS, and mitigates FUS proteotoxicity in optogenetic models and human motor neurons. Another short RNA dissolves aberrant cytoplasmic TDP-43 condensates, restores nuclear TDP-43, and mitigates TDP-43 proteotoxicity. Since short RNAs can be effectively delivered to the human brain, these oligonucleotides could have therapeutic utility for ALS/FTD and related disorders.

Loss of function of the ALS-associated NEK1 kinase disrupts microtubule homeostasis and nuclear import

Loss-of-function variants in NIMA-related kinase 1 (NEK1) constitute a major genetic cause of amyotrophic lateral sclerosis (ALS), accounting for 2 to 3% of all cases. However, how NEK1 mutations cause motor neuron (MN) dysfunction is unknown. Using mass spectrometry analyses for NEK1 interactors and NEK1-dependent expression changes, we find functional enrichment for proteins involved in the microtubule cytoskeleton and nucleocytoplasmic transport. We show that α-tubulin and importin-β1, two key proteins involved in these processes, are phosphorylated by NEK1 in vitro. NEK1 is essential for motor control and survival in Drosophila models in vivo, while using several induced pluripotent stem cell (iPSC)-MN models, including NEK1 knockdown, kinase inhibition, and a patient mutation, we find evidence for disruptions in microtubule homeostasis and nuclear import. Notably, stabilizing microtubules with two distinct classes of drugs restored NEK1-dependent deficits in both pathways. The capacity of NEK1 to modulate these processes that are critically involved in ALS pathophysiology renders this kinase a formidable therapeutic candidate.

NUP62 localizes to ALS/FTLD pathological assemblies and contributes to TDP-43 insolubility

A G4C2 hexanucleotide repeat expansion in the C9orf72 gene is the most common genetic cause of ALS and FTLD (C9-ALS/FTLD) with cytoplasmic TDP-43 inclusions observed in regions of neurodegeneration. The accumulation of repetitive RNAs and dipeptide repeat protein (DPR) are two proposed mechanisms of toxicity in C9-ALS/FTLD and linked to impaired nucleocytoplasmic transport. Nucleocytoplasmic transport is regulated by the phenylalanine-glycine nucleoporins (FG nups) that comprise the nuclear pore complex (NPC) permeability barrier. However, the relationship between FG nups and TDP-43 pathology remains elusive. Our studies show that nuclear depletion and cytoplasmic mislocalization of one FG nup, NUP62, is linked to TDP-43 mislocalization in C9-ALS/FTLD iPSC neurons. Poly-glycine arginine (GR) DPR accumulation initiates the formation of cytoplasmic RNA granules that recruit NUP62 and TDP-43. Cytoplasmic NUP62 and TDP-43 interactions promotes their insolubility and NUP62:TDP-43 inclusions are frequently found in C9orf72 ALS/FTLD as well as sporadic ALS/FTLD postmortem CNS tissue. Our findings indicate NUP62 cytoplasmic mislocalization contributes to TDP-43 proteinopathy in ALS/FTLD.

RNA modulates physiological and neuropathological protein phase transitions

Aggregation of RNA-binding proteins (RBPs) is a pathological hallmark of neurodegenerative disorders like amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). In these diseases, TDP-43 and FUS RBPs are depleted from the nuclear compartment, where they are normally localized, and found within cytoplasmic inclusions in degenerating regions of affected individuals' postmortem tissue. The mechanisms responsible for aggregation of these proteins has remained elusive, but recent studies suggest liquid-liquid phase separation (LLPS) might serve as a critical nucleation step in formation of pathological inclusions. The process of phase separation also underlies the formation and maintenance of several functional membraneless organelles (MLOs) throughout the cell, some of which contain TDP-43, FUS, and other disease-linked RBPs. One common ligand of disease-linked RBPs, RNA, is a major component of MLOs containing RBPs and has been demonstrated to be a strong modulator of RBP phase transitions. Although early evidence suggested a largely synergistic effect of RNA on RBP phase separation and MLO assembly, recent work indicates that RNA can also antagonize RBP phase behavior under certain physiological and pathological conditions. In this review, we describe the mechanisms underlying RNA-mediated phase transitions of RBPs and examine the molecular properties of these interactions, such as RNA length, sequence, and secondary structure, that mediate physiological or pathological LLPS.

RNA dependent suppression of C9orf72 ALS/FTD associated neurodegeneration by Matrin-3

The most common genetic cause of amyotrophic lateral sclerosis (ALS) is a GGGGCC (G4C2) hexanucleotide repeat expansions in first intron of the C9orf72 gene. The accumulation of repetitive RNA sequences can mediate toxicity potentially through the formation of intranuclear RNA foci that sequester key RNA-binding proteins (RBPs), and non-ATG mediated translation into toxic dipeptide protein repeats. However, the contribution of RBP sequestration to the mechanisms underlying RNA-mediated toxicity remain unknown. Here we show that the ALS-associated RNA-binding protein, Matrin-3 (MATR3), colocalizes with G4C2 RNA foci in patient tissues as well as iPSC-derived motor neurons harboring the C9orf72 mutation. Hyperexpansion of C9 repeats perturbed subcellular distribution and levels of endogenous MATR3 in C9-ALS patient-derived motor neurons. Interestingly, we observed that ectopic expression of human MATR3 strongly mitigates G4C2-mediated neurodegeneration in vivo. MATR3-mediated suppression of C9 toxicity was dependent on the RNA-binding domain of MATR3. Importantly, we found that expression of MATR3 reduced the levels of RAN-translation products in mammalian cells in an RNA-dependent manner. Finally, we have shown that knocking down endogenous MATR3 in C9-ALS patient-derived iPSC neurons decreased the presence of G4C2 RNA foci in the nucleus. Overall, these studies suggest that MATR3 genetically modifies the neuropathological and the pathobiology of C9orf72 ALS through modulating the RNA foci and RAN translation.

Optogenetic TDP-43 nucleation induces persistent insoluble species and progressive motor dysfunction in vivo

TDP-43 is a predominantly nuclear DNA/RNA binding protein that is often mislocalized into insoluble cytoplasmic inclusions in post-mortem patient tissue in a variety of neurodegenerative disorders including Amyotrophic Lateral Sclerosis (ALS) and Frontotemporal dementia (FTD). The underlying causes of TDP-43 proteinopathies remain unclear, but recent studies indicate the formation of these protein assemblies is driven by aberrant phase transitions of RNA deficient TDP-43. Technical limitations have prevented our ability to understand how TDP-43 proteinopathy relates to disease pathogenesis. Current animal models of TDP-43 proteinopathy often rely on overexpression of wild-type TDP-43 to non-physiological levels that may initiate neurotoxicity through nuclear gain of function mechanisms, or by the expression of disease-causing mutations found in only a fraction of ALS patients. New technologies allowing for light-responsive control of subcellular protein crowding provide a promising approach to drive intracellular protein aggregation, as we have previously demonstrated in vitro. Here we present a model for the optogenetic induction of TDP-43 proteinopathy in Drosophila that recapitulates key features of patient pathology, including detergent insoluble cytoplamsic inclusions and progressive motor dysfunction.

RNA Binding Antagonizes Neurotoxic Phase Transitions of TDP-43

TDP-43 proteinopathy is a pathological hallmark of amyotrophic lateral sclerosis and frontotemporal dementia where cytoplasmic TDP-43 inclusions are observed within degenerating regions of patient postmortem tissue. The mechanism by which TDP-43 aggregates has remained elusive due to technological limitations, which prevent the analysis of specific TDP-43 interactions in live cells. We present an optogenetic approach to reliably induce TDP-43 proteinopathy under spatiotemporal control. We show that the formation of pathologically relevant inclusions is driven by aberrant interactions between low-complexity domains of TDP-43 that are antagonized by RNA binding. Although stress granules are hypothesized to be a conduit for seeding TDP-43 proteinopathy, we demonstrate pathological inclusions outside these RNA-rich structures. Furthermore, we show that aberrant phase transitions of cytoplasmic TDP-43 are neurotoxic and that treatment with oligonucleotides composed of TDP-43 target sequences prevent inclusions and rescue neurotoxicity. Collectively, these studies provide insight into the mechanisms that underlie TDP-43 proteinopathy and present a potential avenue for therapeutic intervention.

Factors associated with ambulatory care sensitive emergency department visits for South Carolina Medicaid members with intellectual disability

INTRODUCTION

Ambulatory care sensitive conditions (ACSCs) can be seen as failure of access or management in primary care settings. Identifying factors associated with ACSCs for individuals with an Intellectual Disability (ID) provide insight into potential interventions.

METHOD

To assess the association between emergency department (ED) ACSC visits and a number of demographic and health characteristics of South Carolina Medicaid members with ID. A retrospective cohort of adults with ID was followed from 2001 to 2011. Using ICD-9-CM codes, four ID subgroups, totalling 14 650 members, were studied.

RESULTS

There were 106 919 ED visits, with 21 214 visits (19.8%) classified as ACSC. Of those, 82.9% were treated and released from EDs with costs averaging $578 per visit. People with mild and unspecified ID averaged greater than one ED visit per member year. Those with Down syndrome and other genetic cause ID had the lowest rates of ED visits but the highest percentage of ACSC ED visits that resulted in inpatient hospitalisation (26.6% vs. an average of 16.8% for other subgroups). When compared with other residential types, those residing at home with no health support services had the highest ED visit rate and were most likely to be discharged back to the community following an ED visit (85.2%). Adults residing in a nursing home had lower rates of ED visits but were most likely to be admitted to the hospital (38.9%) following an ED visit. Epilepsy and convulsions were the leading cause (29.6%) of ACSC ED visits across all subgroups and residential settings.

CONCLUSION

Prevention of ACSC ED visits may be possible by targeting adults with ID who live at home without health support services.

Hypoxic-Preconditioned Bone Marrow Stem Cell Medium Significantly Improves Outcome After Retinal Ischemia in Rats

PURPOSE

We have previously demonstrated the protective effect of bone marrow stem cell (BMSC)-conditioned medium in retinal ischemic injury. We hypothesized here that hypoxic preconditioning of stem cells significantly enhances the neuroprotective effect of the conditioned medium and thereby augments the protective effect in ischemic retina.

METHODS

Rats were subjected to retinal ischemia by increasing intraocular pressure to 130 to 135 mm Hg for 55 minutes. Hypoxic-preconditioned, hypoxic unconditioned, or normoxic medium was injected into the vitreous 24 hours after ischemia ended. Recovery was assessed 7 days after injections by comparing electroretinography measurements, histologic examination, and apoptosis (TUNEL, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay). To compare proteins secreted into the medium in the groups and the effect of hypoxic exposure, we used rat cytokine arrays.

RESULTS

Eyes injected with hypoxic BMSC-conditioned medium 24 hours after ischemia demonstrated significantly enhanced return of retinal function, decreased retinal ganglion cell layer loss, and attenuated apoptosis compared to those administered normoxic or hypoxic unconditioned medium. Hypoxic-preconditioned medium had 21 significantly increased protein levels compared to normoxic medium.

CONCLUSIONS

The medium from hypoxic-preconditioned BMSCs robustly restored retinal function and prevented cell loss after ischemia when injected 24 hours after ischemia. The protective effect was even more pronounced than in our previous studies of normoxic conditioned medium. Prosurvival signals triggered by the secretome may play a role in this neuroprotective effect.

Lineage-specific RUNX3 hypomethylation marks the preneoplastic immune component of gastric cancer

Runt domain transcription factor 3 (RUNX3) is widely regarded as a tumour-suppressor gene inactivated by DNA hypermethylation of its canonical CpG (cytidine-phosphate-guanidine) island (CGI) promoter in gastric cancer (GC). Absence of RUNX3 expression from normal gastric epithelial cells (GECs), the progenitors to GC, coupled with frequent RUNX3 overexpression in GC progression, challenge this longstanding paradigm. However, epigenetic models to better describe RUNX3 deregulation in GC have not emerged. Here, we identify lineage-specific DNA methylation at an alternate, non-CGI promoter (P1) as a new mechanism of RUNX3 epigenetic control. In normal GECs, P1 was hypermethylated and repressed, whereas in immune lineages P1 was hypomethylated and widely expressed. In human GC development, we detected aberrant P1 hypomethylation signatures associated with the early inflammatory, preneoplastic and tumour stages. Aberrant P1 hypomethylation was fully recapitulated in mouse models of gastric inflammation and tumorigenesis. Cell sorting showed that P1 hypomethylation reflects altered cell-type composition of the gastric epithelium/tumour microenvironment caused by immune cell recruitment, not methylation loss. Finally, via long-term culture of gastric tumour epithelium, we revealed that de novo methylation of the RUNX3 canonical CGI promoter is a bystander effect of oncogenic immortalization and not likely causal in GC pathogenesis as previously argued. We propose a new model of RUNX3 epigenetic control in cancer, based on immune-specific, non-CGI promoter hypomethylation. This novel epigenetic signature may have utility in early detection of GC and possibly other epithelial cancers with premalignant immune involvement.

Deriving and propagating mouse embryonic stem cell lines for studying genomic imprinting

Embryonic stem (ES) cells are a cell culture derivative of the blastocyst inner cell mass (ICM), the latter giving rise to the embryo, the amnion, the yolk sac, and the chrorioallantoic portion of the placenta. Blastocyst injection chimera experiments show that ES cells are similar to early-stage ICM cells in that they contribute to the primitive ectoderm and endoderm derivatives (1). However, it is probably not possible to equate these two cell types, as ES cells appear to be produced by the cell culture environment and have no exact counterpart in the blastocyst. Instead, ES cells could be thought of as being ICM cells that, instead of undergoing rapid differentiation as they would in vivo, are abnormally locked into continuing cycles of division in the undifferentiated state by virtue of the action of exogenous factors. Leukemia inhibitory factor, LIF, is one such factor (2,3) and is indispensable for the propagation of mouse ES cells at least when primary embryo fibroblasts (PEFs) are used as feeder layers (4).

Religiosity, spirituality and antenatal anxiety in Southern U.S. women

INTRODUCTION

We investigated the association between religiosity, spirituality, and anxiety in pregnant women, taking into account potential confounders.

MATERIALS AND METHODS

From September 2005 through March 2006, pregnant women in three obstetrics practices in the American South were included in a cross-sectional study. The anxiety subscale of the Hospital Anxiety and Depression Scale (HADS) was used to measure anxiety.

RESULTS

Of the 344 participating women, 23 screened positive for moderate to severe anxiety (HADS [anxiety] score greater than 10). Overall religiosity or spirituality (odds ratio [OR], 0.53; p=0.006) and social support (OR, 0.42; p<0.0001) were significantly associated with significantly lower odds of a positive anxiety screen. Among the specific measures of religiosity or spirituality, self-rated religiosity, self-rated spirituality, and participation in nonorganizational religious activities were significantly associated with lower odds of moderate to severe anxiety symptoms.

DISCUSSION AND CONCLUSIONS

Religiosity and spirituality are associated with reduced anxiety in pregnant women. Additional study is needed to evaluate whether the association is causal.

Is postal follow-up of childhood cancer survivors worthwhile?

BACKGROUND

Childhood cancer survival has increased over the last 30 years, but long-term effects necessitate continued monitoring of survivors. Since not all of them attend follow-up clinics, this study assesses the efficacy of obtaining information from general practitioners (GPs) through a 5-year rolling postal program.

PROCEDURE

Survivors were included who had been diagnosed with a malignancy in the West Midlands since 1957 and were not attending central long-term follow-up clinics.

RESULTS

One thousand twenty-seven patients were followed up between 1993 and 2004. Replies were received on 903 (88% response). There were 44 subsequent malignancies and 42 deaths. No medical problems were reported in 341/935 patients (36.5%); in the other 594 endocrine effects were the most common, with visual effects the biggest single problem. Brain tumor survivors had the largest proportion of problems.

CONCLUSIONS

The response rate and information quality achieved show that this method of follow-up is feasible, in cases of discharged or defaulting patients. These data will complement those derived from hospital-based follow-up studies, to give a broader understanding of the spectrum of late effects experienced by survivors and may inform the development of specific long-term follow-up protocols.

Down-regulation of ATM protein in HRS cells of nodular sclerosis Hodgkin's lymphoma in children occurs in the absence ofATMgene inactivation

The tumour component of classical Hodgkin's lymphoma (cHL), Hodgkin Reed-Sternberg (HRS) cells, are believed to be derived from germinal centre (GC) B cells but intriguingly display a characteristic loss of B cell receptor (BCR) expression. The precise mechanisms by which BCR-negative HRS cell progenitors survive negative selection during the GC reaction remain obscure. Individuals with ataxia telangiectasia, caused by biallelic inactivation of the DNA damage response gene, ataxia telangiectasia mutated (ATM), have a higher risk of cHL development. Here we show that, in contrast to normal GC B cells that expressed low but detectable ATM protein, ATM protein was not detected in HRS cells of 17/18 cases of paediatric cHL, all but one with nodular sclerosis (NS) subtype. A comprehensive analysis of the ATM gene in microdissected HRS cells of nine representative tumours showed no evidence of either loss of heterozygosity or consistent pathogenic mutations. Furthermore, bisulphite sequencing of the ATM promoter from HRS cells of five tumours also revealed the absence of hypermethylation. Since our microarray data suggested significantly reduced ATM transcription in HRS cells compared to GC B cells, we conclude that loss of ATM expression could be the result of alterations in upstream regulators of ATM transcription. Importantly, ATM loss in paediatric cHLs has clinical implications and could be potentially exploited to guide future, less toxic, tumour-specific treatments.

Congenital abnormalities and clinical features associated with Wilms’ tumour: A comprehensive study from a centre serving a large population

Altogether 156 children treated for Wilms' tumour (WT) between 1970 and 1998 were studied. Sixty-six children, selected only by their attendance at clinic, were carefully examined and the findings compared to those from a case note review of 90 children. Congenital abnormalities were present in 45% of the examined cohort, in 19% of the case notes review group and in 30% overall. Novel findings included the association of WT with Marshall Smith syndrome, developmental delay in 3 of 4 cases of WT (one bilateral) and 1 sibling from consanguineous Pakistani families and another sibling also had leukaemia. The possibility of rare DNA repair or cancer predisposing disorders among these 4 families requires further study. Careful examination and history taking of an unselected patient cohort revealed a higher than expected incidence of clinical abnormalities which may be overlooked if not specifically sought.

Mutagenesis in mice of nuclear hormone receptor binding sites in the Igf2/H19 imprinting control region

The H19/Igf2 imprinting control region (ICR) is a DNA methylation-dependent chromatin insulator in somatic cells. The hypomethylated maternally inherited ICR binds the insulator protein CTCF at four sites, and blocks activity of the proximal Igf2 promoter by insulating it from the shared distal enhancers. The hypermethylated paternally inherited ICR lacks CTCF binding and insulator activity, but induces methylation-silencing of the paternal H19 promoter. The paternal-specific methylation of the ICR is established in the male germ cells, while the ICR emerges from the female germ line in an unmethylated form. Despite several attempts to find cis-regulatory elements, it is still unknown what determines these male and female germ cell-specific epigenetic modifications. We recently proposed that five in vivo footprints spanning fifteen half nuclear hormone receptor (NHR) binding sites within the ICR might be involved, and here we report on the effects of mutagenizing all of these half sites in mice. No effect was obtained--in the female and male germ lines the mutant ICR remained hypomethylated and hypermethylated, respectively. The ICR imprinting mechanism remains undefined.

Caring for survivors of childhood cancers: the size of the problem

Many survivors of childhood cancer have significant health problems due to their illness or treatment. This population-based study examines the number of long-term survivors, their disabilities and consequent long-term care needs. Survival rates for children diagnosed with cancer between 1960 and 1999 in the West Midlands, United Kingdom (UK), were used to estimate future long-term survivor numbers. Treatment and late effects data on a cohort of patients surviving for more than 5 years were used to consider continuing care needs. Between the 1960s and 1990s, 5-year survival increased from 23% to 70%. There were 98 5-year survivors in 1970, and numbers may exceed 2,100 by the end of 2005. Most (at least 61%) survivors in the West Midlands Region have one or more chronic medical problems and may require multidisciplinary care. We conclude that, in order to determine how to provide cost-effective care for this increasing population, protocol delivered management with audit is needed.

Seasonal differences in the onset of the EBV-positive and -negative forms of paediatric Hodgkin's lymphoma

In this study, we have shown that there are seasonal differences in the onset of the (Epstein–Barr virus) EBV-positive and -negative forms of paediatric Hodgkin's lymphoma (HL). This suggests aetiological differences between the two forms of this disease. EBV-positive HL might be a rare consequence of primary EBV infection.

Sacrococcygeal teratomas: the UK Children's Cancer Study Group's experience. I. Neonatal

The aim of this study was to review the United Kingdom Children's Cancer Study Group (UKCCSG) experience of sacrococcygeal teratomas (SCT) including histological presentation, response to surgery and chemotherapy, and long term effects of the tumour and treatment. This paper presents the results for those children diagnosed during the neonatal period. Children aged up to 4 weeks with biopsy proven localised or metastatic sacrococcygeal germ cell tumours were eligible. From 1st January 1989 to 31st December 1997 (9 years), 15 UKCCSG centres registered 51 neonates with SCT into GC 8901. Surgery alone was performed in all and the prognosis was good - except for 1 baby who died from massive haemorrhage at the initial operation and 1 who died from the complications of prematurity. Seven of the 51 children (14%) who had teratomas in the neonatal period (5 mature, two immature) had yolk sac tumour (YST) recurrence at: 4, 12, 15, 20, 20, 28 and 32 months of age. These children received chemotherapy in the form of etoposide/bleomycin/carboplatin (JEB) and are alive and well at review. These results emphasise the need for oncological follow-up of SCT and the good response to JEB chemotherapy of malignant teratomas and YST.

Imprinting in the germ line

Genomic imprinting is an epigenetic system of gene regulation in mammals. It determines the parent-of-origin-dependent expression of a small number of imprinted genes during development, i.e., the maternal allele is inactive while the paternal is active, or vice versa. Imprinting is imparted in the germ line and involves differential DNA methylation such that particular DNA regions become methylated in one sex of germ line but not in the other. Inheritance of these differential egg and sperm methylation states is then transmitted to somatic cells, where they lead to differential maternal and paternal allelic activity, or monoallelic expression. Increasing evidence indicates that the inherited and stable differential allelic methylation regulates monoallelic expression by influencing the activity of gene regulatory elements-for one allele the element is switched off by methylation, while for the other the element is left potentially active by the lack of methylation. An interesting feature of the germ line is that, despite the presence of genomic imprinting, either as imprints inherited from the zygote or as new imprints imparted according to germ cell sex, imprinted genes are biallelically expressed as if imprints were not present. One explanation for this observation is that imprints have no influence over the germ cell's transcriptional machinery, i.e., imprinting may be neutralized in the germ cell lineage. This phenomenon may have a common basis with other unique features of the germ line, such as totipotency, perhaps in some unique aspect of chromatin structure.

Molecular analysis of single colonies reveals a diverse origin of initial clonal proliferation in B-precursor acute lymphoblastic leukemia that can precede the t(12;21) translocation

The pathogenesis of pediatric B-precursor acute lymphoblastic leukemia is largely unknown, and even with nonrandom chromosomal translocations present, the precise order of clonal molecular events is undefined. We developed an in vitro system using cytokines interleukin (IL)-3, IL-7, IL-10, and FMS-like tyrosine kinase 3 ligand with CD40 ligand-expressing fibroblasts to obtain single blast colonies from which clonal immunoglobulin heavy chain (IgH), T-cell receptor delta gene rearrangements, and, in t(12;21)-positive cases, TEL-AML1 fusion transcripts could be simultaneously PCR amplified. The proliferation of early tumor progenitors increased subclone detection enabling us, in seven diagnostic samples, to determine the stage of differentiation at which each leukemia occurred. Four were derived from the stage before initiation of IgH rearrangement, one during recombination of variable, joining, and diversity segments of the heavy chain gene VDJ(H), and two after completion of IgH rearrangement. Furthermore, analysis of a t(12;21)-positive leukemia with unusually late onset, identified both TEL-AML1-positive and -negative colonies carrying a clonal T-cell receptor delta rearrangement, inferring the presence of clonal expansion before the occurrence of the t(12;21). In contrast, in a typical, early onset t(12;21)-positive leukemia, the t(12;21) appeared to be the first clonal event. In both leukemias, the t(12;21) occurred before recombination of variable, joining and diversity segments of the heavy chain gene VDJ.

South Asian ethnicity and material deprivation increase the risk of Epstein-Barr virus infection in childhood Hodgkin's disease

In order to further define the factors associated with the observed variations in the Epstein-Barr virus-positive rate in childhood Hodgkin's disease, we have studied the effect of material deprivation (measured by the Townsend score) and ethnic origin on the frequency of Epstein-Barr virus-positivity in 55 cases of childhood Hodgkin's disease, diagnosed between 1981 and 1999, from a multi-ethnic region of the United Kingdom. Epstein-Barr virus status was determined by immunohistochemistry for the Epstein-Barr virus-encoded latent membrane protein-1. 62% of cases were Epstein-Barr virus-positive. Ethnic group was the strongest predictor of Epstein-Barr virus-positivity, with South Asians having a more than 20-fold risk of being Epstein-Barr virus-positive compared with non-South Asians. An increased risk was still present after adjusting for deprivation. Townsend scores were significantly higher (indicating more deprivation) in the Epstein-Barr virus-positive group, particularly in males. The relative risk of Epstein-Barr virus-positivity showed a gradient with increasing Townsend score; the risk being 7-times higher in the most deprived quartile compared with the least deprived group. Although the association between Townsend score and Epstein-Barr virus-positivity was reduced after adjusting for ethnic group, the risk of Epstein-Barr virus-positivity was still 3-times higher in the most deprived compared with the least deprived quartile. In addition, cases having 2 or more siblings were 5-times as likely to be Epstein-Barr virus-positive as those from smaller families. These results provide the first evidence of a strong association between Epstein-Barr virus-positive Hodgkin's disease and South Asian children from the United Kingdom. In addition, deprivation may increase the likelihood of Epstein-Barr virus-positive disease independently of ethnicity.

Neuroblastomas with chromosome 11q loss and single copy MYCN comprise a biologically distinct group of tumours with adverse prognosis

Neuroblastoma is a heterogeneous tumour and its effective clinical management is dependent on accurate prognostic evaluation. In approximately 25% of patients amplification of the MYCN oncogene is known to be associated with a poor outcome. In order to identify additional molecular markers with prognostic potential in non-MYCN-amplified neuroblastomas, we looked for a correlation between clinical outcome and loss of heterozygosity (LOH) on four chromosomes that frequently show alteration in neuroblastoma (chromosomes 3, 4, 11 and 14). Chromosome 11q loss (with frequent parallel loss of chromosomes 3p, 4p and/or 14q) was found exclusively in tumours without MYCN amplification and was significantly associated with poor event-free survival. The 2-year event-free survival rate for 11q LOH cases was 30%, compared to 34% for MYCN-amplified cases and 100% for cases without these abnormalities. While 11q LOH was associated predominantly with advanced-stage disease, 2 cases with low-stage disease and 11q LOH both suffered relapses. We conclude that chromosome 11q loss defines a biologically distinct group of tumours without MYCN amplification that appear to have potential for aggressive metastatic growth. Thus this genetic alteration may be an important new prognostic marker in neuroblastoma.

A complex duplication created by gene targeting at the imprinted H19 locus results in two classes of methylation and correlated Igf2 expression phenotypes

Imprinting of the mouse H19 and Igf2 genes is dependent on the presence of an intervening imprinting control region (ICR) situated 2 kb upstream of H19 and approximately 70 kb downstream of Igf2. Several recent studies have provided substantial evidence that the unmethylated maternal ICR acts as an insulator that prevents activation of Igf2 by a suite of enhancers downstream of the H19 gene. The methylated paternal ICR and H19 promoter have no activity, allowing sole activation of Igf2 expression. We have produced mice in which a duplication of the H19/Igf2 ICR produces, in each generation, two classes of methylation levels that correlated with two Igf2 imprinting phenotypes. One hypermethylated class also shows activation of the normally silent Igf2 gene, whereas the other hypomethylated class shows only slight activation of Igf2, in agreement with methylation's role in ICR function. This study describes a rare, possibly unique type of mutation that induces two distinct phenotypes in each generation.

Methylated DNA sequences in genomic imprinting

Genomic imprinting is a special form of epigenetic system that determines the parent-of-origin-specific, or monoallelic, expression of a small number of genes, termed "imprinted" genes. Considerable sequence and methylation analysis of imprinted genes has revealed a common theme: Regions of allele-specific methylation inherited from the gametes, or primary differentially methylated regions (DMRs), are associated with CpG islands and repeat elements, and this overall structure suggests functional significance. For at least three imprinted genes the sequence of the primary DMR constitutes an element able to regulate gene activity in cis--a chromatin insulator and a promoter of an antisense transcript. In these cases the unique feature of imprinting appears to be in the ability to switch the regulatory capacity of these elements on or off by the absence or presence of inherited methylation. Increasing evidence therefore suggests that genomic imprinting for at least some genes constitutes the regulation of gene regulatory elements by methylation. An important challenge now is to determine how the differential methylation of primary DMR sequences is established in the germ line. If methylation is the primary imprint, then the processes establishing it are the primary imprinting mechanisms. Trans-acting factors that are expressed in one sex of germ line and not the other are likely to be involved, and their ability to methylate may be mediated through repeat elements associated with the sequence of primary DMRs.

Survival of children with malignant germ cell, trophoblastic and other gonadal tumours in Europe

Collaborators of the EUROCARE study had provided records on 1263 cases of germ cell, trophoblastic and other gonadal neoplasms, registered in 34 cancer registries in 16 European countries over the period 1978--1992 and followed-up until the end of 1994. Observed 5-year actuarial survival for 490 cases diagnosed in 1985-1989 was 80% (95% confidence interval (CI)=(76, 83)). The corresponding figures were calculated for the intracranial and intraspinal germ cell tumours (68%, 95% CI=(57, 76)), other non-gonadal germ cell tumours (76%, 95% CI=(68, 82)), gonadal germ-cell tumours (89%, 95% CI=(85, 93)) and gonadal carcinomas (50%, CI=(24, 76)). Relatively large differences in survival were observed between age-sex subgroups, which also differed with histology, with extremely poor survival of young children with intracranial and intraspinal germ cell tumours. Lower survival was observed in the countries with formerly socialist economies. Time trends in survival were examined for the entire study period, including only the cases registered in the large contributing registries. For all germ cell tumours, the risk ratios calculated in the Cox regression analysis were markedly lowered for the years after the reference period of 1978--1981. The improved outcome is attributed to treatment advances.

Childhood cancer and parental use of tobacco: findings from the inter-regional epidemiological study of childhood cancer (IRESCC)

Parental smoking data have been re-abstracted from the interview records of the Inter-Regional Epidemiological Study of Childhood Cancer (IRESCC) to test further the hypothesis that paternal cigarette smoking is a risk factor for the generality of childhood cancer. Reported cigarette smoking habits for the parents of 555 children diagnosed with cancer in the period 1980-1983 were compared, in two separate matched pairs analyses, with similar information for the parents of 555 children selected from GP lists (GP controls) and for the parents of 555 hospitalized children (hospital controls). When cases were compared with GP controls there was a statistically significant positive trend (P = 0.02) between the risk of childhood cancer and paternal daily consumption of cigarettes before the pregnancy; there was no significant trend for maternal smoking habit. When cases were compared with hospital controls there was a statistically significant negative trend (P< 0.001) between the risk of childhood cancer and maternal daily consumption of cigarettes before the pregnancy; there was no significant trend for paternal smoking habit. Neither of the significant trends could be explained by adjustment for socioeconomic grouping, ethnic origin or parental age at the birth of the child, or by simultaneous analysis of parental smoking habits. Relations between maternal consumption of cigarettes and birth weights suggested that (maternal) smoking data were equally reliable for case and control subjects, although comparisons with national data suggested that the hospital control parents were unusually heavy smokers. These findings give some support for the hypothesis that paternal cigarette smoking is a potential risk factor for the generality of childhood cancers.

The United Kingdom Children's Cancer Study Group's second germ cell tumor study: carboplatin, etoposide, and bleomycin are effective treatment for children with malignant extracranial germ cell tumors, with acceptable toxicity

PURPOSE

To evaluate carboplatin, etoposide, and bleomycin (JEB) in children with malignant extracranial germ cell tumors (GCTs).

PATIENTS AND METHODS

Malignant GCTs in children aged 0 to 16 years were excised without major morbidity or otherwise biopsied. Stage I testicular and some ovarian GCTs were resected and monitored with alpha-fetoprotein (AFP) ("watch-and-wait" approach). Patients with recurrent stage I disease and all other patients received JEB (etoposide 120 mg/m(2) on days 1 through 3, carboplatin 600 mg/m(2) on day 2, and bleomycin 15 mg/m(2) on day 3). Courses were administered every 3 to 4 weeks until remission, and then two more courses were given. Chemotherapy toxicities were assessed using World Health Organization or Brock grading.

RESULTS

Between January 1989 and December 1997, 192 patients were registered. Eight were excluded because either there was no histologic diagnosis (n = 3) or chemotherapy was given off-study (n = 5). The remaining 184 patients had germinoma (n = 20), malignant teratoma (n = 55), embryonal carcinoma (n = 1), yolk sac tumor (n = 107), or choriocarcinoma (n = 1). Forty-seven patients were treated with surgery alone, and 137 patients received JEB. The 5-year survival rate in March 1999 for all 184 patients was 93.2% (95% confidence interval [CI], 87.9% to 96.3%); for the 137 JEB-treated patients, it was 90.9% (95% CI, 83.9% to 95.0%), with an event-free survival rate of 87.8% (95% CI, 81.1% to 92.4%). The median follow-up after JEB treatment was 53 months (range, 0 to 109 months); the median number of courses was five (range, three to eight). Site, stage, and AFP level had prognostic significance. Nonfatal hematologic toxicity was common, but deafness and pulmonary and renal toxicities were rare. One child died of a thoracic tumor and bronchopulmonary dysplasia, and another died of acute myeloid leukemia.

CONCLUSION

Conservative surgery, a watch-and-wait approach after complete excision, and JEB for those requiring chemotherapy produced high cure rates and few serious complications.

Low glutathione peroxidase activity in Gpx1 knockout mice protects jejunum crypts from gamma-irradiation damage

Gpx1 knockout (KO) mice had a higher number of regenerating crypts in the jejunum than did Gpx2-KO or wild-type mice analyzed 4 days after > or =10 Gy gamma-irradiation. Without gamma-irradiation, glutathione peroxidase (GPX) activity in the jejunal and ileal epithelium of Gpx1-KO mice was <10 and approximately 35%, respectively, of that of the wild-type mice. Four days after exposure to 11 Gy, GPX activity in wild-type and Gpx1-KO ileum was doubled and tripled, respectively. However, jejunal GPX activity was not changed. Thus the lack of GPX activity in the jejunum is associated with better regeneration of crypt epithelium after radiation. Gpx2 gene expression was solely responsible for the increase in GPX activity in the ileum, since radiation did not alter GPX activity in Gpx2-KO mice. The intestinal Gpx2 mRNA levels of Gpx1-KO and wild-type mice increased up to 14- and 7-fold after radiation, respectively. Although the Gpx1-KO jejunum had higher levels of PGE(2) than the wild-type jejunum after exposure to 0 or 15 Gy, these differences were not statistically significant. Thus whether GPX inhibits PG biosynthesis in vivo remains to be established. We can conclude that the Gpx2 gene compensates for the lack of Gpx1 gene expression in the ileal epithelium. This may have abolished the protective effect in Gpx1-KO mice against the radiation damage in the ileum.

Characterization and chromosome location of the mouse link protein gene (Crtl1)

Link protein (LP) plays an essential role in endochondral bone formation by stabilizing the supramolecular assemblies of aggrecan and hyaluronan. We have isolated and characterized the mouse link protein gene (Crtl1). It is longer than 40 kb and transcribed from two alternative promoters, leading to heterogenous mRNAs between 5.3 and 1.3 kb in size. Apart from the coding sequence, the 5' flanking region is also highly conserved in mammals. Immunostaining revealed high levels of LP expression in the cartilaginous primordia of skeletal elements and low levels in other tissues. Using single-strand conformation polymorphism analysis, Crtl1 was assigned to mouse chromosome 13, tightly linked to Dhfr.

Maternal-specific footprints at putative CTCF sites in the H19 imprinting control region give evidence for insulator function

Parent-of-origin-specific expression of the mouse insulin-like growth factor 2 (Igf2) gene and the closely linked H19 gene are regulated by an intervening 2 kb imprinting control region (ICR), which displays parentspecific differential DNA methylation [1] [2]. Four 21 bp repeats are embedded within the ICR and are conserved in the putative ICR of human and rat Igf2 and H19, suggesting that the repeats have a function [3] [4]. Here, we report that prominent DNA footprints were found in vivo on the unmethylated maternal ICR at all four 21 bp repeats, demonstrating the presence of protein binding. The methylated paternal ICR displayed no footprints. Significantly, the maternal-specific footprints were localized to putative binding sites for CTCF, a highly conserved zinc-finger DNA-binding protein with multiple roles in gene regulation including that of chromatin insulator function [5] [6]. These results strongly suggest that the maternal ICR functions as an insulator element in regulating mutually exclusive expression of Igf2 and H19 in cis.

Factors affecting survival in White and Asian children with acute lymphoblastic leukaemia

Some studies suggest that Asian children with leukaemia have a worse outcome than Whites. Survival of Asians with ALL treated at the Birmingham Children's Hospital from 1975 to 1994 was the same as that of Whites, despite their greater deprivation and poorer nutrition. For one 5-year period (1980-1984) Asians had significantly poorer survival, even after adjustment for prognostic factors. Poor treatment compliance during that period may have contributed to this difference.

Experience with quinupristin/dalfopristin in treating infections with vancomycin-resistant Enterococcus faecium in children

BACKGROUND

The emergence and spread of vancomycin-resistant Enterococcus faecium (VREF) has presented serious therapeutic difficulties because of the lack of reliably active antibiotics. Quinupristin/dalfopristin is a new injectable streptogramin antibiotic that is active against most strains of VREF. Experience with this agent in adults with VREF infections is well-documented; however, there are few reports of its use in children. We report on eight children with VREF infections who received quinupristin/dalfopristin under a compassionate use protocol.

METHODS

Quinupristin/dalfopristin was administered according to the manufacturer's recommendations. Clinical and laboratory data were recorded for each patient.

RESULTS

The infections treated comprised six cases of bacteremia and two of peritonitis. All patients had serious underlying conditions. Seven patients recovered fully. One patient died, having experienced a relapse of his infection after quinupristin/dalfopristin was discontinued. None of the patients experienced side effects or other adverse events.

CONCLUSION

Quinupristin/dalfopristin was well-tolerated and generally effective in children with infections caused by VREF. There is increasing evidence that it may be more effective than other currently available antibiotics in some such patients.

Clonal diversity of Ig and T-cell receptor gene rearrangements in childhood B-precursor acute lymphoblastic leukaemia

The majority of paediatric B precursor acute lymphoblastic leukaemias in children are derived from a single transformed haematopoietic cell with complete or partial VDJ recombination within the immunoglobulin heavy chain gene. A high frequency of patients also show rearrangements within TCRdelta and TCRgamma loci and in up to 40% of children there is an excess of immune system gene rearrangements compared with the number of identified alleles of immune system genes, suggesting the presence of multiple leukaemic subclones -clonal diversity. It has been observed by us and other investigators that in individual patients the pattern of immune system gene rearrangements often changes between presentation and relapse. In order to explore the possibility that clonal diversity plays a biological role during disease progression we optimised methods for subclone detection and analysed the prognostic significance of clonal diversity among 75 children with B precursor-ALL. Our results suggest that clonal diversity plays a role in disease progression as patients with oligoclonal disease showed a significantly shorter disease free survival than patients with monoclonal disease. This trend was of particular importance in the 'standard risk' group of ALL where aggressive disease could not be recognised by other means. In addition, generation of independent subclones from an early, non-rearranged tumour progenitor appears to be a common feature among leukaemias with aggressive clinical behaviour. We speculate on the type of genetic factors which may participate both in the generation of subclones and also in wider genomic instability and which are likely to be required for the aggressive clinical phenotype in children with ALL.

Pediatric oncology and hematology in Birmingham, England

The hematology and oncology service at Birmingham Children's Hospital was established in the late 1960s and now is one of the largest in the United Kingdom. It provides comprehensive care for the entire range of childhood malignancies, coagulation disorders, and hemoglobinopathies and other hematological disorders, and undertakes bone marrow transplant and megatherapy/peripheral blood stem cell procedures. Research includes clinical trials of treatments of childhood cancers; molecular biology studies on leukemia, Hodgkin's disease, neuroblastoma, and sarconas; childhood cancer epidemiology, and geographical and racial incidence; and treatment of hemophilia and molecular investigation of coagulation disorders. These activities involve collaboration with local, national, and international research groups.

Characterization of novel parent-specific epigenetic modifications upstream of the imprinted mouse H19 gene

Genomic imprinting results in parent-specific monoallelic expression of a small number of genes in mammals. The identity of imprints is unknown, but much evidence points to a role for DNA methylation. The maternal alleles of the imprinted H19 gene are active and hypomethylated; the paternal alleles are inactive and hypermethylated. Roles for other epigenetic modifications are suggested by allele-specific differences in nuclease hypersensitivity at particular sites. To further analyze the possible epigenetic mechanisms determining monoallelic expression of H19, we have conducted in vivo dimethylsulfate and DNase I footprinting of regions upstream of the coding sequence in parthenogenetic and androgenetic embryonic stem cells. These cells carry only maternally and paternally derived alleles, respectively. We observed the presence of maternal-allele-specific dimethylsulfate and DNase I footprints at the promoter indicative of protein-DNA interactions at a CCAAT box and at binding sites for transcription factors Sp1 and AP-2. Also, at the boundary of a region further upstream for which existent differential methylation has been suggested to constitute an imprint, we observed a number of strand-specific dimethylsulfate reactivity differences specific to the maternal allele, along with an unusual chromatin structure in that both strands of maternally derived DNA were strongly hypersensitive to DNase I cutting over a distance of 100 nucleotides. We therefore reveal the existence of novel parent-specific epigenetic modifications, which in addition to DNA methylation, could constitute imprints or maintain monoallelic expression of H19.

Binomial cokriging for estimating and mapping the risk of childhood cancer

The incidences of human diseases vary from place to place, and this is also likely to be so for the risk of people developing many of them. We have analysed the spatial distribution of childhood cancer in the West Midland Health Authority Region of England from 1980 to 1984. This is a rare disease which is considered to be noncontagious. The observed frequencies of the disease in the electoral wards have been converted to proportions that estimate the risk of a child's developing it. The spatial autocorrelation of the risk, expressed in the variogram, was determined in a novel way from the proportions within electoral wards by treating them as binomial variables dependent on the risk and the numbers of children in the wards. The observed variogram was modelled by Whittle's elementary two-dimensional correlation. Covariances of the proportion and cross covariances between the proportion and the risk were derived, and from the latter and the proportions the risk was estimated in two ways by a form of cokriging: ordinary and conditional unbiased cokriging. The variogram of the risk shows strong autocorrelation, and the kriged estimates, when mapped, have a distribution that is far from even. There are patches where the estimated risk is large, especially in the rural south west and the suburban north east; and there are other patches, notably the more densely populated areas, where it is small.

Neuroblastoma in Europe: differences in the pattern of disease in the UK. SENSE. Study group for the Evaluation of Neuroblastoma Screening in Europe

BACKGROUND

Neuroblastoma is a major contributor to childhood cancer mortality, but its prognosis varies with age and stage of disease, and some tumours regress spontaneously. Urinary screening programmes or clinical examination may detect the disease before symptoms appear, but the benefit of early diagnosis is uncertain. We examined the incidence, pattern, and presentation of neuroblastoma in four European countries.

METHOD

Population-based incidence rates were derived for France, Austria, Germany, and the UK. Age, sex, and stage distribution were analysed by Mantel-Haenszel techniques and Poisson regression. The proportion of incidental diagnoses (cases without symptoms found at routine health checks or during investigation of other disorders) and mortality rates were also compared.

FINDINGS

Between 1987 and 1991, 1672 cases of neuroblastoma were diagnosed in children under 15 years old (France, 624; Austria, 69; Germany, 493; UK, 486). Age-standardised annual incidence was significantly lower in the UK (10.1/million) than in France (12.5) and Germany (11.4). In the UK a deficit of low-stage disease in infants was accompanied by an excess of stage IV in older children. The UK had significantly fewer incidental diagnoses (8%) than Austria (27%) and Germany (34%). UK mortality rates were significantly higher than German or French rates.

INTERPRETATION

In the UK, neuroblastoma diagnosis is delayed, possibly because of a less rigorous system of health checks for children. Although some overdiagnosis occurs in mainland Europe, our data suggest that in the UK some low-stage cases, undetected in infancy, may later present as advanced disease. This finding has implications for screening programmes and organisation of routine surveillance of infant health in the UK.

Clonal diversity of Ig and T-cell-receptor gene rearrangements identifies a subset of childhood B-precursor acute lymphoblastic leukemia with increased risk of relapse

Current prognostic indicators such as age, sex, and white blood cell count (WBC) fail to identify all children with more aggressive forms of B-precursor acute lymphoblastic leukemia (ALL), and a proportion of patients without poor prognostic indicators still relapse. Results obtained from an analysis of 65 pediatic B-precursor ALL patients indicated that subclone formation leading to clonal diversity, as detected by Ig and T-cell receptor (TCR) gene rearrangements, may represent a very useful prognostic indicator, independent of age, sex, and WBC. Disease-free survival was significantly shorter in those patients showing clonal diversity at presentation. Furthermore, clonal diversity was detected not only in the majority of high-risk patients who relapsed but was also associated with a high probability of relapse in standard-risk patients. Sixty-five percent (13/20) of standard-risk patients who also showed clonal diversity subsequently relapsed, whereas the percentage of relapses among standard-risk patients without clonal diversity was much lower at 19% (7/36). Continued clonal evolution during disease progression is an important feature of aggressive B-precursor ALL. All 5 patients with clonal diversity who were followed up in our study showed a change in the pattern of clonality between presentation and relapse. This implies an important role for clonal diversity as a mechanism of disease progression through the process of clonal variation and clonal selection.

Bisulfite sequencing in preimplantation embryos: DNA methylation profile of the upstream region of the mouse imprinted H19 gene

In this study we describe a modification of the bisulfite genomic sequencing protocol that enables detection of methylation from as few as five diploid cells from preimplantation mouse embryos. We have used bisulfite genomic sequencing to study the methylation profile of the putative imprinting element upstream of the mouse H19 gene at several stages of embryonic development, including fertilized oocytes and two-cell embryos. The methylation of the H19 imprinting element has recently been described extensively for midgestation embryos, but remains poorly characterized for the preimplantation stages of development, despite widespread changes in genomic DNA methylation occurring at this time. We studied the methylation profile of 35 CpG sites spanning two regions within the H19 imprinting element and found that an overall pattern of allele-specific methylation was maintained at all developmental stages examined, including fertilized oocytes and two-cell embryos. However, allele-specific methylation was not maintained in an absolute fashion subsequent to the first cell division, with a clear flux between partial de novo methylation of the maternal allele and partial demethylation of the paternal allele. Our findings highlight the dynamics of methylation in the early embryo and suggest that it is the overall level of methylation that is responsible for maintenance of the imprinting element and not the methylation of individual CpG sites.

Involvement of IsK-associated K+ channel in heart rate control of repolarization in a murine engineered model of Jervell and Lange-Nielsen syndrome

The Jervell and Lange-Nielsen (JLN) syndrome affects the human cardioauditory system, associating a profound bilateral deafness with an abnormally long QT interval on the ECG. It results from mutations in KVLQT1 and ISK genes that encode the 2 subunits forming the K+ channel responsible for the cardiac and inner ear slowly activating component of the delayed rectifier K+ current (IKs). A JLN mouse model that presents typical inner ear defects has been created by knocking out the isk gene (isk-/-). This study specifically reports on the cardiac phenotype counterpart, determined in the whole animal and at mRNAs and cellular levels. Surface ECG recordings of isk-/- mice showed a longer QT interval at slow heart rates, a paradoxical shorter QT interval at fast heart rates, and an overall exacerbated QT-heart rate adaptation compared with wild-type (WT) mice. A 300-ms increase in the heart rate cycle length induces a 309+/-21% increase in the QT duration of the WT mice versus a 500+/-50% in isk-/- mice (P<0.001). It is concluded that the isk gene product and/or IKs, when present, blunts the QT adaptation to heart rate variations and that steeper QT-RR relationships reflect a greater susceptibility to arrhythmias in patients lacking IKs.

Altered synaptic physiology and reduced susceptibility to kainate-induced seizures in GluR6-deficient mice

L-glutamate, the neurotransmitter of the majority of excitatory synapses in the brain, acts on three classes of ionotropic receptors: NMDA (N-methyl-D-aspartate), AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid) and kainate receptors. Little is known about the physiological role of kainate receptors because in many experimental situations it is not possible to distinguish them from AMPA receptors. Mice with disrupted kainate receptor genes enable the study of the specific role of kainate receptors in synaptic transmission as well as in the neurotoxic effects of kainate. We have now generated mutant mice lacking the kainate-receptor subunit GluR6. The hippocampal neurons in the CA3 region of these mutant mice are much less sensitive to kainate. In addition, a postsynaptic kainate current evoked in CA3 neurons by a train of stimulation of the mossy fibre system is absent in the mutant. We find that GluR6-deficient mice are less susceptible to systemic administration of kainate, as judged by onset of seizures and by the activation of immediate early genes in the hippocampus. Our results indicate that kainate receptors containing the GluR6 subunit are important in synaptic transmission as well as in the epileptogenic effects of kainate.

UKCCSG's germ cell tumour (GCT) studies: improving outcome for children with malignant extracranial non-gonadal tumours--carboplatin, etoposide, and bleomycin are effective and less toxic than previous regimens. United Kingdom Children's Cancer Study Group

BACKGROUND

We report the efficacy and late effects of carboplatin, etoposide, and bleomycin (JEB) for extracranial non-gonadal tumours (GCII, 1989-95) compared with the 5 previous regimens (GCI, 1979-1988) consisting of 3 vincristine, actinomycin, and cyclophosphamide (VAC) and 2 platinum-based protocols.

METHODS AND RESULTS

Median follow-up for 52 patients in the GCI study and 46 in GCII was 105 and 48 months, respectively. For GCI, 5- and 10-year actuarial survival was 63% (95% Confidence interval 50 to 75%) or 72% (57 to 83%) if 6 cases given low-dose VAC were excluded. For GCII, 5-year survival was significantly greater at 95% (83 to 99%), p = 0.01. Event-free survival was 46% at 5 years for GCI (33 to 59%) or 52% excluding the low-dose VAC cases (38 to 66%), while for GCII it was 87% (74 to 94%), p = 0.002. Five-year event-free survival of 21 children given cisplatin, etoposide, and bleomycin (BEP) in GCI was 57% (37 to 76%) compared with 87% (74 to 94%) for 46 given JEB in GCII, P = 0.02. Late effects in 30 evaluable survivors of GCI and 43 GCII included renal impairment in 6 in GCI and 0 in GCII and deafness in 11 and 4, respectively. Among 17 survivors of sacrococcygeal tumours treated in GCI, 4 have neuropathic bladder/bowel and another shortening of a leg. In GCII, 4 of 26 have neuropathic bladder/bowel with lower limb weakness in one.

CONCLUSIONS

We found JEB to be more effective and less toxic than our previous regimens. Some survivors of sacrococcygeal tumours have neurological late effects.