Normal heart function requires generation of a regular rhythm by sinoatrial pacemaker cells and the alteration of this spontaneous heart rate by the autonomic input to match physiological demand. However, the molecular mechanisms that ensure consistent periodicity of cardiac contractions and fine tuning of this process by autonomic system are not completely understood.
Here we examined the contribution of the m2R-IKACh intracellular signaling pathway, which mediates the negative chronotropic effect of parasympathetic stimulation, to the regulation of the cardiac pacemaking rhythm. Using isolated heart preparations and single-cell recordings we show that the m2R-IKACh signaling pathway controls the excitability and firing pattern of the sinoatrial cardiomyocytes and determines variability of cardiac rhythm in a manner independent from the autonomic input. Ablation of the major regulator of this pathway, Rgs6, in mice results in irregular cardiac rhythmicity and increases susceptibility to atrial fibrillation. We further identify several human subjects with variants in the RGS6 gene and show that the loss of function in RGS6 correlates with increased heart rate variability. These findings identify the essential role of the m2R-IKACh signaling pathway in the regulation of cardiac sinus rhythm and implicate RGS6 in arrhythmia pathogenesis.
Yttrium-90 (90Y) positron emission tomography with integrated computed tomography (PET/CT) represents a technological leap from 90Y bremsstrahlung single-photon emission computed tomography with integrated computed tomography (SPECT/CT) by coincidence imaging of low abundance internal pair production. Encouraged by favorable early experiences, we implemented post-radioembolization 90Y PET/CT as an adjunct to 90Y bremsstrahlung SPECT/CT in diagnostic reporting.
This is a retrospective review of all paired 90Y PET/CT and 90Y bremsstrahlung SPECT/CT scans over a 1-year period. We compared image resolution, ability to confirm technical success, detection of non-target activity, and providing conclusive information about 90Y activity within targeted tumor vascular thrombosis. 90Y resin microspheres were used. 90Y PET/CT was performed on a conventional time-of-flight lutetium-yttrium-oxyorthosilicate scanner with minor modifications to acquisition and reconstruction parameters. Specific findings on 90Y PET/CT were corroborated by 90Y bremsstrahlung SPECT/CT, 99mTc macroaggregated albumin SPECT/CT, follow-up diagnostic imaging or review of clinical records.
Diagnostic reporting recommendations were developed from our collective experience across 44 paired scans. Emphasis on the continuity of care improved overall diagnostic accuracy and reporting confidence of the operator. With proper technique, the presence of background noise did not pose a problem for diagnostic reporting. A counter-intuitive but effective technique of detecting non-target activity is proposed, based on the pattern of activity and its relation to underlying anatomy, instead of its visual intensity. In a sub-analysis of 23 patients with a median follow-up of 5.4 months, 90Y PET/CT consistently outperformed 90Y bremsstrahlung SPECT/CT in all aspects of qualitative analysis, including assessment for non-target activity and tumor vascular thrombosis. Parts of viscera closely adjacent to the liver remain challenging for non-target activity detection, compounded by a tendency for mis-registration.
Adherence to proper diagnostic reporting technique and emphasis on continuity of care are vital to the clinical utility of post-radioembolization 90Y PET/CT. 90Y PET/CT is superior to 90Y bremsstrahlung SPECT/CT for the assessment of target and non-target activity.
Yttrium-90 radioembolization; Selective internal radiation therapy; Yttrium-90 PET/CT; Bremsstrahlung SPECT/CT; Diagnostic reporting; Non-target activity
Coincidence imaging of low-abundance yttrium-90 (90Y) internal pair production by positron emission tomography with integrated computed tomography (PET/CT) achieves high-resolution imaging of post-radioembolization microsphere biodistribution. Part 2 analyzes tumor and non-target tissue dose-response by 90Y PET quantification and evaluates the accuracy of tumor 99mTc macroaggregated albumin (MAA) single-photon emission computed tomography with integrated CT (SPECT/CT) predictive dosimetry.
Retrospective dose quantification of 90Y resin microspheres was performed on the same 23-patient data set in part 1. Phantom studies were performed to assure quantitative accuracy of our time-of-flight lutetium-yttrium-oxyorthosilicate system. Dose-responses were analyzed using 90Y dose-volume histograms (DVHs) by PET voxel dosimetry or mean absorbed doses by Medical Internal Radiation Dose macrodosimetry, correlated to follow-up imaging or clinical findings. Intended tumor mean doses by predictive dosimetry were compared to doses by 90Y PET.
Phantom studies demonstrated near-perfect detector linearity and high tumor quantitative accuracy. For hepatocellular carcinomas, complete responses were generally achieved at D70 > 100 Gy (D70, minimum dose to 70% tumor volume), whereas incomplete responses were generally at D70 < 100 Gy; smaller tumors (<80 cm3) achieved D70 > 100 Gy more easily than larger tumors. There was complete response in a cholangiocarcinoma at D70 90 Gy and partial response in an adrenal gastrointestinal stromal tumor metastasis at D70 53 Gy. In two patients, a mean dose of 18 Gy to the stomach was asymptomatic, 49 Gy caused gastritis, 65 Gy caused ulceration, and 53 Gy caused duodenitis. In one patient, a bilateral kidney mean dose of 9 Gy (V20 8%) did not cause clinically relevant nephrotoxicity. Under near-ideal dosimetric conditions, there was excellent correlation between intended tumor mean doses by predictive dosimetry and those by 90Y PET, with a low median relative error of +3.8% (95% confidence interval, -1.2% to +13.2%).
Tumor and non-target tissue absorbed dose quantification by 90Y PET is accurate and yields radiobiologically meaningful dose-response information to guide adjuvant or mitigative action. Tumor 99mTc MAA SPECT/CT predictive dosimetry is feasible. 90Y DVHs may guide future techniques in predictive dosimetry.
Yttrium-90 radioembolization; Selective internal radiation therapy; PET/CT; Voxel dosimetry; Dose-volume histogram; Predictive dosimetry
Anaplastic cortical ependymomas are rare lesions with few cases reported in the literature.
We present a unique case of an anaplastic cortical ependymoma in a 51-year-old female presenting as a butterfly lesion with involvement of both frontal lobes. The patient underwent gross total resection of her tumor with further adjuvant treatment. We present the findings in our case and review the literature surrounding supratentorial ependymomas and their treatment outcomes.
Rarely, cortical ependymoma can present as a butterfly lesion and should be considered in the differential diagnosis of such lesions in adults.
Adult; Anaplastic; Cortical; Ependymoma; Supratentorial
The Proteus syndrome is characterized by the overgrowth of skin, connective tissue, brain, and other tissues. It has been hypothesized that the syndrome is caused by somatic mosaicism for a mutation that is lethal in the nonmosaic state.
We performed exome sequencing of DNA from biopsy samples obtained from patients with the Proteus syndrome and compared the resultant DNA sequences with those of unaffected tissues obtained from the same patients. We confirmed and extended an observed association, using a custom restriction-enzyme assay to analyze the DNA in 158 samples from 29 patients with the Proteus syndrome. We then assayed activation of the AKT protein in affected tissues, using phosphorylation-specific antibodies on Western blots.
Of 29 patients with the Proteus syndrome, 26 had a somatic activating mutation (c.49G→A, p.Glu17Lys) in the oncogene AKT1, encoding the AKT1 kinase, an enzyme known to mediate processes such as cell proliferation and apoptosis. Tissues and cell lines from patients with the Proteus syndrome harbored admixtures of mutant alleles that ranged from 1% to approximately 50%. Mutant cell lines showed greater AKT phosphorylation than did control cell lines. A pair of single-cell clones that were established from the same starting culture and differed with respect to their mutation status had different levels of AKT phosphorylation.
The Proteus syndrome is caused by a somatic activating mutation in AKT1, proving the hypothesis of somatic mosaicism and implicating activation of the PI3K–AKT pathway in the characteristic clinical findings of overgrowth and tumor susceptibility in this disorder. (Funded by the Intramural Research Program of the National Human Genome Research Institute.)
Hypofunction of the N-methyl D-aspartate subtype of glutamate receptor (NMDAR) is hypothesized to be a mechanism underlying cognitive dysfunction in individuals with schizophrenia. For the schizophrenia-linked genes NRG1 and ERBB4, NMDAR hypofunction is thus considered a key detrimental consequence of the excessive NRG1-ErbB4 signaling found in people with schizophrenia. However, we show here that neuregulin 1β–ErbB4 (NRG1β-ErbB4) signaling does not cause general hypofunction of NMDARs. Rather, we find that, in the hippocampus and prefrontal cortex, NRG1β-ErbB4 signaling suppresses the enhancement of synaptic NMDAR currents by the nonreceptor tyrosine kinase Src. NRG1β-ErbB4 signaling prevented induction of long-term potentiation at hippocampal Schaffer collateral–CA1 synapses and suppressed Src-dependent enhancement of NMDAR responses during theta-burst stimulation. Moreover, NRG1β-ErbB4 signaling prevented theta burst–induced phosphorylation of GluN2B by inhibiting Src kinase activity. We propose that NRG1-ErbB4 signaling participates in cognitive dysfunction in schizophrenia by aberrantly suppressing Src-mediated enhancement of synaptic NMDAR function.
PMID: 21441918 CAMSID: cams1842
Ionotropic glutamate receptors of AMPA, NMDA and kainate receptor (KAR) subtypes mediate fast excitatory synaptic transmission in the vertebrate CNS. Auxiliary proteins have been identified for AMPA and NMDA receptor complexes, but little is known about KAR complex proteins. We previously identified the CUB-domain protein, Neto1, as an NMDA receptor-associated polypeptide. Here, we show that Neto1 is also an auxiliary subunit for endogenous synaptic KARs. We found that Neto1 and KARs co-immunoprecipitated from brain lysates, from post-synaptic densities (PSDs) and, in a manner dependent on Neto1 CUB domains, when co-expressed in heterologous cells. In Neto1-null mice, there was an ~50% reduction in the abundance of GluK2-KARs in hippocampal PSDs. Neto1 strongly localized to CA3 stratum lucidum and loss of Neto1 resulted in a selective deficit in KAR-mediated neurotransmission at mossy fiber-CA3 pyramidal cell synapses (MF-CA3): KAR-mediated EPSCs in Neto1-null mice were reduced in amplitude and decayed more rapidly than did those in wild-type mice. In contrast, the loss of Neto2, which also localizes to stratum lucidum and interacts with KARs, had no effect on KAR synaptic abundance or MF-CA3 transmission. Indeed MF-CA3 KAR deficits in Neto1/2 double null mutant mice were indistinguishable from Neto1 single null mice. Thus, our findings establish Neto1 as an auxiliary protein required for synaptic function of KARs. The ability of Neto1 to regulate both NMDARs and KARs reveals a unique dual role in controlling synaptic transmission by serving as an auxiliary protein for these two classes of ionotropic glutamate receptors in a synapse specific fashion.
Defining the genetic contribution of rare variants to common diseases is a major basic and clinical science challenge that could offer new insights into disease etiology and provide potential for directed gene- and pathway-based prevention and treatment. Common and rare nonsynonymous variants in the GCKR gene are associated with alterations in metabolic traits, most notably serum triglyceride levels. GCKR encodes glucokinase regulatory protein (GKRP), a predominantly nuclear protein that inhibits hepatic glucokinase (GCK) and plays a critical role in glucose homeostasis. The mode of action of rare GCKR variants remains unexplored. We identified 19 nonsynonymous GCKR variants among 800 individuals from the ClinSeq medical sequencing project. Excluding the previously described common missense variant p.Pro446Leu, all variants were rare in the cohort. Accordingly, we functionally characterized all variants to evaluate their potential phenotypic effects. Defects were observed for the majority of the rare variants after assessment of cellular localization, ability to interact with GCK, and kinetic activity of the encoded proteins. Comparing the individuals with functional rare variants to those without such variants showed associations with lipid phenotypes. Our findings suggest that, while nonsynonymous GCKR variants, excluding p.Pro446Leu, are rare in individuals of mixed European descent, the majority do affect protein function. In sum, this study utilizes computational, cell biological, and biochemical methods to present a model for interpreting the clinical significance of rare genetic variants in common disease.
Cataract surgery remains the most widely performed intraocular procedure throughout the world. Safety and accuracy of the procedure are paramount and techniques should remain under constant review. Recently, the introduction of the femtosecond laser to assist cataract surgery has provided ophthalmologists with an exciting tool that may further improve outcomes. We review the existing literature and discuss the installation and initial experience of a femtosecond laser into our practice.
Femtosecond laser assisted surgery; Cataract
ClinSeq is a large-scale medical sequencing (LSMS) project at the National Institutes of Health (NIH), the goal of which is to pilot the feasibility of using high throughput genome sequencing for clinical research and eventually to improve the delivery of healthcare. In phase one, 1000 participants are being clinically evaluated for cardiovascular phenotypes and DNA is being collected for sequencing of 400 candidate genes to identify genetic variants that may predispose to the early development of atherosclerosis. We report on an individual with familial hypercholesterolemia (OMIM #143890) who has a novel mutation, c.261_262invGA that predicts a premature stop (p.Trp87X) in the LDLR gene. Although the p.Trp87X predicted protein mutation has been reported, c.261_262invGA is distinct from mutations reported in prior families and emphasizes the importance of describing mutations at the DNA level. It is important to describe mutations according to the underlying DNA change as multiple nucleotide changes may underlie a single predicted protein change.
Radiopharmaceutical therapy, once touted as the “magic bullet” in radiation oncology, is increasingly being used in the treatment of a variety of malignancies; albeit in later disease stages. With ever-increasing public and medical awareness of radiation effects, radiation dosimetry is becoming more important. Dosimetry allows administration of the maximum tolerated radiation dose to the tumor/organ to be treated but limiting radiation to critical organs. Traditional tumor dosimetry involved acquiring pretherapy planar scans and plasma estimates with a diagnostic dose of intended radiopharmaceuticals. New advancements in single photon emission computed tomography and positron emission tomography systems allow semi-quantitative measurements of radiation dosimetry thus allowing treatments tailored to each individual patient.
Radionuclide therapy; radioimmunotherapy; quality of life
Immortal tumor cell lines are an important model system for cancer research, however, misidentification and cross-contamination of cell lines are a common problem. Seven chordoma cell lines are reported in the literature, but none has been characterized in detail. We analyzed gene expression patterns and genomic copy number variations in five putative chordoma cell lines (U-CH1, CCL3, CCL4, GB60, and CM319). We also created a new chordoma cell line, U-CH2, and provided genotypes for cell lines for identity confirmation. Our analyses revealed that CCL3, CCL4, and GB60 are not chordoma cell lines, and that CM319 is a cancer cell line possibly derived from chordoma, but lacking expression of key chordoma biomarkers. U-CH1 and U-CH2 both have gene expression profiles, copy number aberrations, and morphology consistent with chordoma tumors. These cell lines also harbor genetic changes, such as loss of p16, MTAP, or PTEN, that make them potentially useful models for studying mechanisms of chordoma pathogenesis and for evaluating targeted therapies.
Genomic instability plays an important role in most human cancers. To characterize genomic instability in esophageal squamous cell carcinoma (ESCC), we examined loss of heterozygosity (LOH), copy number (CN) loss, CN gain, and gene expression using the Affymetrix GeneChip Human Mapping 500K (n=30 cases) and Human U133A (n=17 cases) arrays in ESCC cases from a high-risk region of China. We found that genomic instability measures varied widely among cases and separated them into two groups: a high-frequency instability group (two-thirds of all cases with one or more instability category ≥ 10%) and a low-frequency instability group (one-third of cases with instability < 10%). Genomic instability also varied widely across chromosomal arms, with the highest frequency of LOH on 9p (33% of informative single nucleotide polymorphisms (SNPs)), CN loss on 3p (33%), and CN gain on 3q (48%). Twenty-two LOH regions were identified: four on 9p, seven on 9q, four on 13q, two on 17p, and five on 17q. Three CN loss regions – 3p12.3, 4p15.1, and 9p21.3 – were detected. Twelve CN gain regions were found, including six on 3q, one on 7q, four on 8q, and one on 11q. One of the most gene-rich of these CN gain regions was 11q13.1-13.4, where 26 genes also had RNA expression data available. CN gain was significantly correlated with increased RNA expression in over 80% of these genes. Our findings demonstrate the potential utility of combining CN analysis and gene expression data to identify genes involved in esophageal carcinogenesis.
esophageal cancer; LOH; copy number alteration; 500K SNP array
Using high-resolution array-CGH, we identified unique duplications of a region on 6q27 in four multiplex families with ≥ 3 cases of chordoma, a cancer of presumed notochordal origin. The duplicated region contains only the T gene (Brachyury), which plays an important role in notochord development and is expressed in most sporadic chordomas. Our findings highlight the need to include screening for complex genomic rearrangements in searches for cancer susceptibility genes.
Familial aggregation, linkage, and case-control studies support the role of germline genes in the etiology of lymphoid malignancies. To further examine the role of genetic variation underlying susceptibility, we analyzed 1536 SNPs in 152 genes involved in apoptosis, DNA repair, immune response, and oxidative stress pathways among a unique sample of 165 unrelated familial cases including patients with chronic lymphocytic leukemia (CLL), Waldenström's (WM), and Hodgkin lymphoma (HL), and 107 spouse controls. We confirmed previous studies showing a polymorphism in the IL10 promoter (rs1800890/-3575T>A) to be associated with non-Hodgkin lymphoma since we found this allele to be associated with both CLL and WM. We also confirmed the role of IL6 variation to be associated with HL. Polymorphisms in the TRAIL gene were associated with both CLL and WM. Future replication and functional studies are needed to clarify the role of these genetic variants. Finally, our data further support the close association of WM and CLL.
Candidate genes; association; familial; lymphoid malignancies; chronic lymphocytic leukemia; Waldenström's macroglobulinemia; Hodgkin lymphoma
Human Disabled-2 (DAB2), is a multi-function signalling molecule that it is frequently down-regulated in human cancers. We aimed to investigate the possible tumour suppressor effect of DAB2 in nasopharyngeal carcinoma (NPC).
We studied the expression of DAB2 in NPC cell lines, xenografts and primary tumour samples. The status of promoter methylation was assessed by methylation specific PCR and bisulfite sequencing. The functional role of DAB2 in NPC was investigated by re-introducing DAB2 expression into NPC cell line C666-1.
Decrease or absent of DAB2 transcript was observed in NPC cell lines and xenografts. Loss of DAB2 protein expression was seen in 72% (33/46) of primary NPC as demonstrated by immunohistochemistry. Aberrant DAB2 promoter methylation was detected in 65.2% (30/46) of primary NPC samples by methylation specific PCR. Treatment of the DAB2 negative NPC cell line C666-1 with 5-aza-2'-deoxycytidine resulted in restoration of DAB2 expression in a dose-dependent manner. Overexpression of DAB2 in NPC cell line C666-1 resulted in reduced growth rate and 35% reduction in anchorage-dependent colony formation, and inhibition of serum-induced c-Fos expression compared to vector-transfected controls. Over expression of DAB2 resulted in alterations of multiple pathways as demonstrated by expression profiling and functional network analysis, which confirmed the role of DAB2 as an adaptor molecule involved in multiple receptor-mediated signalling pathways.
We report the frequent down regulation of DAB2 in NPC and the promoter hypermethylation contributes to the loss of expression of DAB2. This is the first study demonstrating frequent DAB2 promoter hypermethylation in human cancer. Our functional studies support the putative tumour suppressor effect of DAB2 in NPC cells.
Anophthalmia and microphthalmia are etiologically and clinically heterogeneous. Lenz microphthalmia is a syndromic form that is typically inherited in an X-linked pattern, though the causative gene mutation is unknown. Townes-Brocks syndrome manifests thumb anomalies, imperforate anus, and ear anomalies. We present a 13-year-old boy with a syndromic microphthalmia phenotype and a clinical diagnosis of Lenz microphthalmia syndrome.
The patient was subjected to clinical and molecular evaluation, including array CGH analysis. The clinical features included left clinical anophthalmia, right microphthalmia, anteriorly placed anus with fistula, chordee, ventriculoseptal defect, patent ductus arteriosus, posteriorly rotated ears, hypotonia, growth retardation with delayed bone age, and mental retardation. The patient was found to have an approximately 5.6 Mb deletion of 16q11.2q12.1 by microarray based-comparative genomic hybridization, which includes the SALL1 gene, which causes Townes-Brocks syndrome.
Deletions of 16q11.2q12.2 have been reported in several individuals, although those prior reports did not note microphthalmia or anophthalmia. This region includes SALL1, which causes Townes-Brocks syndrome. In retrospect, this child has a number of features that can be explained by the SALL1 deletion, although it is not clear if the microphthalmia is a rare feature of Townes-Brocks syndrome or caused by other mechanisms. These data suggest that rare copy number changes may be a cause of syndromic microphthalmia allowing a personalized genomic medicine approach to the care of patients with these aberrations.
Infection with the Epstein-Barr virus (EBV) is a strong predisposing factor in the development of nasopharyngeal carcinoma (NPC). Many viral gene products including EBNA1, LMP1, and LMP2 have been implicated in NPC tumorigenesis, although the de novo control of these viral oncoproteins remains largely unclear. The recent discovery of EBV-encoded viral microRNA (miRNA) in lymphoid malignancies has prompted us to examine the NPC-associated EBV miRNA. Using large-scale cloning analysis on EBV-positive NPC cells, two novel EBV miRNA, now named miR-BART21 and miR-BART22, were identified. These two EBV-encoded miRNA are abundantly expressed in most NPC samples. We found two nucleotide variations in the primary transcript of miR-BART22, which we experimentally confirmed to augment its biogenesis in vitro and thus may underline the high and consistent expression of miR-BART22 in NPC tumors. More importantly, we determined that the EBV latent membrane protein 2A (LMP2A) is the putative target of miR-BART22. LMP2A is a potent immunogenic viral antigen that is recognized by the cytotoxic T cells; down-modulation of LMP2A expression by miR-BART22 may permit escape of EBV-infected cells from host immune surveillance. Taken together, we demonstrated that two newly identified EBV-encoded miRNA are highly expressed in NPC. Specific sequence variations on the prevalent EBV strain in our locality might contribute to the higher miR-BART22 expression level in our NPC samples. Our findings emphasize the role of miR-BART22 in modulating LMP2A expression, which may facilitate NPC carcinogenesis by evading the host immune response.
In a previous pilot case-control study of individuals diagnosed with esophageal squamous cell carcinoma (ESCC) and matched controls from a high-risk area in China, we identified 38 single nucleotide polymorphisms (SNPs) associated with ESCC located in or near one of 33 genes. In the present study, we attempted to replicate the results of these 38 gene-related SNPs in a new sample of 300 ESCC cases and 300 matched controls from the same study conducted in Shanxi Province, China. Among 36 evaluable SNPs, four were significant in one or more analyses, including SNPs located in EPHB1, PGLYRP2, PIK3C3, and SLC9A9, although the odds ratios (ORs) for these genotypes were modest. Associations were found with EPHB1/rs1515366 (OR 0.92, 95% CI 0.86-0.99; p = 0.019), PIK3C3/rs52911 (OR 0.93, 95% CI 0.88-0.99; p = 0.02), and PGLYRP2/rs959117 (OR 0.93, 95% CI, 0.86-1.01; p = 0.061) in general linear models (additive mode); and the genotype distribution differed between cases and controls for SLC9A9/rs956062 (p = 0.024). To examine these four genes in more detail, 40 HapMap-based tag SNPs from these four genes were evaluated in the same subjects, and seven additional SNPs associated with ESCC were identified. Further confirmation of these findings in other populations and other studies are needed to determine if the signals from these SNPs are indirectly associated due to linkage disequilibrium, or are directly related to biologic function and the development of ESCC.
Esophageal cancer; Replication study; SNP
The N-methyl-D-aspartate receptor (NMDAR), a major excitatory ligand-gated ion channel in the central nervous system (CNS), is a principal mediator of synaptic plasticity. Here we report that neuropilin tolloid-like 1 (Neto1), a complement C1r/C1s, Uegf, Bmp1 (CUB) domain-containing transmembrane protein, is a novel component of the NMDAR complex critical for maintaining the abundance of NR2A-containing NMDARs in the postsynaptic density. Neto1-null mice have depressed long-term potentiation (LTP) at Schaffer collateral-CA1 synapses, with the subunit dependency of LTP induction switching from the normal predominance of NR2A- to NR2B-NMDARs. NMDAR-dependent spatial learning and memory is depressed in Neto1-null mice, indicating that Neto1 regulates NMDA receptor-dependent synaptic plasticity and cognition. Remarkably, we also found that the deficits in LTP, learning, and memory in Neto1-null mice were rescued by the ampakine CX546 at doses without effect in wild-type. Together, our results establish the principle that auxiliary proteins are required for the normal abundance of NMDAR subunits at synapses, and demonstrate that an inherited learning defect can be rescued pharmacologically, a finding with therapeutic implications for humans.
The fundamental unit for information processing in the brain is the synapse, a highly specialized site of communication between the brain's multitude of individual neurons. The strength of the communication at each synapse changes in response to neuronal activity—a process called synaptic plasticity—allowing networks of neurons to adapt and learn. How synaptic plasticity occurs is a major question in neurobiology. A central player in synaptic plasticity is an assembly of synaptic proteins called the NMDA receptor complex. Here, we discovered that the protein Neto1 is a component of the NMDA receptor complex. Neto1-deficient mice had a dramatic decrease in the number of NMDA receptors at synapses and consequently, synaptic plasticity and learning were impaired. By indirectly enhancing the function of the residual NMDA receptors in Neto1-deficient mice with a small molecule, we restored synaptic plasticity and learning to normal levels. Our findings establish the principle that inherited abnormalities of synaptic plasticity and learning due to NMDA receptor dysfunction can be pharmacologically corrected. Our discoveries also suggest that synaptic proteins that share a molecular signature, called the CUB domain, with Neto1 may be important components of synaptic receptors across species, because several CUB-domain proteins in worms have also been found to regulate synaptic receptors.
Spatial learning and memory depend on the N-methyl-D-aspartic acid receptor, a synaptic ion channel regulated by Neto1. Impaired cognition due to the absence of Neto1 can be rescued pharmacologically, a finding with implications for the therapy of inherited learning defects in humans.
A subset of cutaneous malignant melanoma and dysplastic nevi (CMM/DN) families is linked to 1p36. To date, no CMM/DN susceptibility gene has been identified at this locus. Data from mouse studies identified chromodomain helicase DNA binding protein 5 (CHD5) as a tumor suppressor affecting cellular proliferation and apoptosis via the CDKN2A/p53 pathway. Based on these findings, we felt it was important to screen CHD5 as a familial CMM/DN susceptibility gene.
Eight unrelated CMM/DN families showing prior evidence of linkage to the 1p36 locus were identified for CHD5 mutation screening. One CMM/DN affected and one unaffected individual from each family were selected for sequencing of the CHD5 coding exons and their respective intron-exon boundaries. CHD5 variants that were identified solely among affecteds in the screening panel were further assessed by sequencing additional affected and unaffected members of these families to determine if the variant co-segregated with the CMM/DN phenotype.
Single nucleotide polymorphisms in the CHD5 intronic and coding regions were identified among affecteds in the screening panel. None of these variants completely co-segregated with CMM/DN affection status among these eight families.
There is no evidence to support CHD5 as a major melanoma susceptibility gene among the eight CMM/DN families screened.
Implantable devices such as cardiac pacemakers, drug-delivery systems, and defibrillators have had a tremendous impact on the quality of live for many disabled people. To date, many devices have been developed for implantation into various parts of the human body. In this paper, we focus on devices implanted in the head. In particular, we describe the technologies necessary to create implantable microimagers. Design, fabrication, and implementation issues are discussed vis-à-vis two examples of implantable microimagers; the retinal prosthesis and in vivo neuro-microimager. Testing of these devices in animals verify the use of the microimagers in the implanted state. We believe that further advancement of these devices will lead to the development of a new method for medical and scientific applications.
implant; head; microimager; retinal prosthesis; in vivo
With the integration of the KEGG and Predictome databases as well as two search engines for coexpressed genes/proteins using data sets obtained from the Stanford Microarray Database (SMD) and Gene Expression Omnibus (GEO) database, VisANT 3.0 supports exploratory pathway analysis, which includes multi-scale visualization of multiple pathways, editing and annotating pathways using a KEGG compatible visual notation and visualization of expression data in the context of pathways. Expression levels are represented either by color intensity or by nodes with an embedded expression profile. Multiple experiments can be navigated or animated. Known KEGG pathways can be enriched by querying either coexpressed components of known pathway members or proteins with known physical interactions. Predicted pathways for genes/proteins with unknown functions can be inferred from coexpression or physical interaction data. Pathways produced in VisANT can be saved as computer-readable XML format (VisML), graphic images or high-resolution Scalable Vector Graphics (SVG). Pathways in the format of VisML can be securely shared within an interested group or published online using a simple Web link. VisANT is freely available at http://visant.bu.edu.
Currently, the detection and identification of Campylobacter and Arcobacter species remains arduous, largely due to cross-species phenotypic similarities and a relatively narrow spectrum of biochemical reactivity. We have developed a PCR-hybridization strategy, wherein degenerate primers are used to amplify glyA fragments from samples, which are then subjected to species-specific oligodeoxyribonucleotide probe hybridizations, to identify and distinguish between Campylobacter jejuni, C. coli, C. lari, C. upsaliensis, Arcobacter butzleri, and an A. butzleri-like species. Evaluation of this strategy with genomic DNA from different type strains suggests that this approach is both specific and sensitive and thus may be applicable in a diagnostic assay to identify and differentiate these highly related species.