FRAX score and recent fall history predict the incidence for sarcopenia in community-dwelling older adults: a prospective cohort study.

We hypothesized that the baseline FRAX score and previous falls would predict the incidence of sarcopenia in community-dwelling older adults who received medical check-ups. The FRAX score (hazard ratio [HR] = 1.087, 95% CI 1.014-1.167) and previous falls (HR = 5.181, 95% CI 1.002-26.777) were determined to be independent risk factors for the incidence of sarcopenia. PURPOSE: This prospective study was performed to elucidate the prevalence and incidence of sarcopenia in community-dwelling older adults who received medical check-ups, and to determine whether FRAX score and fall history predict the incidence of sarcopenia. METHODS: Participants were recruited from a group of individuals who had registered for an annual town-sponsored medical check-up. Study inclusion criteria were aged older than 60 years, living independently, and ability to walk without assistance. Individuals who received nursing care were excluded from the study. A total of 426 residential participants were analyzed. Demographic information, fall history of the previous year, and FRAX score without bone mineral density were assessed. The assessment for sarcopenia was based on the recommendations of the Asian Working Group for Sarcopenia. RESULTS: The final sample for the assessment of sarcopenia incidence comprised 258 participants. The mean follow-up time was 2.92 years. The rate of sarcopenia was 1.06 cases per 100 person-years at risk. The Cox multivariate logistic regression model in our analysis was adjusted for age, gender, muscle mass, and covariates and showed that the FRAX score (HR = 1.087, 95% CI 1.014-1.167) and recent history of falls (HR = 5.181, 95% CI 1.002-26.777) were independent risk factors for the incidence of sarcopenia. CONCLUSION: FRAX and history of falling can be a simple screening tool to raise awareness of the prevention of osteoporosis and sarcopenia in clinical settings.

Novel biallelic SZT2 mutations in 3 cases of early-onset epileptic encephalopathy.

The seizure threshold 2 (SZT2) gene encodes a large, highly conserved protein that is associated with epileptogenesis. In mice, Szt2 is abundantly expressed in the central nervous system. Recently, biallelic SZT2 mutations were found in 7 patients (from 5 families) presenting with epileptic encephalopathy with dysmorphic features and/or non-syndromic intellectual disabilities. In this study, we identified by whole-exome sequencing compound heterozygous SZT2 mutations in 3 patients with early-onset epileptic encephalopathies. Six novel SZT2 mutations were found, including 3 truncating, 1 splice site and 2 missense mutations. The splice-site mutation resulted in skipping of exon 20 and was associated with a premature stop codon. All individuals presented with seizures, severe developmental delay and intellectual disabilities with high variability. Brain MRIs revealed a characteristic thick and short corpus callosum or a persistent cavum septum pellucidum in each of the 2 cases. Interestingly, in the third case, born to consanguineous parents, had unexpected compound heterozygous missense mutations. She showed microcephaly despite the other case and previous ones presenting with macrocephaly, suggesting that SZT2 mutations might affect head size.

Genotype-phenotype correlation of contiguous gene deletions of SLC6A8, BCAP31 and ABCD1.

The BCAP31 gene is located between SLC6A8, associated with X-linked creatine transporter deficiency, and ABCD1, associated with X-linked adrenoleukodystrophy. Recently, loss-of-function mutations in BCAP31 were reported in association with severe developmental delay, deafness and dystonia. We characterized the break points in eight patients with deletions of SLC6A8, BCAP31 and/or ABCD1 and studied the genotype-phenotype correlations. The phenotype in patients with contiguous gene deletions involving BCAP31 overlaps with the phenotype of isolated BCAP31 deficiency. Only deletions involving both BCAP31 and ABCD1 were associated with hepatic cholestasis and death before 1 year, which might be explained by a synergistic effect. Remarkably, a patient with an isolated deletion at the 3'-end of SLC6A8 had a similar severe phenotype as seen in BCAP31 deficiency but without deafness. This might be caused by the disturbance of a regulatory element between SLC6A8 and BCAP31.

Phenotype and genotype in 101 males with X-linked creatine transporter deficiency.

BACKGROUND: Creatine transporter deficiency is a monogenic cause of X-linked intellectual disability. Since its first description in 2001 several case reports have been published but an overview of phenotype, genotype and phenotype--genotype correlation has been lacking. METHODS: We performed a retrospective study of clinical, biochemical and molecular genetic data of 101 males with X-linked creatine transporter deficiency from 85 families with a pathogenic mutation in the creatine transporter gene (SLC6A8). RESULTS AND CONCLUSIONS: Most patients developed moderate to severe intellectual disability; mild intellectual disability was rare in adult patients. Speech language development was especially delayed but almost a third of the patients were able to speak in sentences. Besides behavioural problems and seizures, mild to moderate motor dysfunction, including extrapyramidal movement abnormalities, and gastrointestinal problems were frequent clinical features. Urinary creatine to creatinine ratio proved to be a reliable screening method besides MR spectroscopy, molecular genetic testing and creatine uptake studies, allowing definition of diagnostic guidelines. A third of patients had a de novo mutation in the SLC6A8 gene. Mothers with an affected son with a de novo mutation should be counselled about a recurrence risk in further pregnancies due to the possibility of low level somatic or germline mosaicism. Missense mutations with residual activity might be associated with a milder phenotype and large deletions extending beyond the 3' end of the SLC6A8 gene with a more severe phenotype. Evaluation of the biochemical phenotype revealed unexpected high creatine levels in cerebrospinal fluid suggesting that the brain is able to synthesise creatine and that the cerebral creatine deficiency is caused by a defect in the reuptake of creatine within the neurones.

Acute encephalopathy in a patient with Dravet syndrome.

Dravet syndrome (severe myoclonic epilepsy in infancy) is an epileptic syndrome with various types of seizures that begin in the first year of life and may result in intellectual impairment. Mutations of the SCN1A gene are the most prevalent genetic cause of Dravet syndrome. In this study, we report a 12-year-old girl with Dravet syndrome carrying an SCN1A mutation, c.2785Cdel (L929del fsX934). She had an episode of status epilepticus and persistent lethargy after 48 h of acute febrile illness that was preceded by an annual flu vaccination. Low voltage activities detected by electroencephalogram and elevated neuron-specific enolase/interleukin-6 concentrations in the cerebrospinal fluid suggested acute encephalopathy. MRI showed abnormalities in the bilateral thalami, cerebellum and brainstem. These abnormalities were protracted over a month. The biochemical and MRI characteristics of this case are different from any known type of encephalopathy, and may suggest a vulnerability of neurons expressing mutant SCN1A in the brain.

Isolation and characterization of avian influenza viruses from raw poultry products illegally imported to Japan by international flight passengers.

The transportation of poultry and related products for international trade contributes to transboundary pathogen spread and disease outbreaks worldwide. To prevent pathogen incursion through poultry products, many countries have regulations about animal health and poultry product quarantine. However, in Japan, animal products have been illegally introduced into the country in baggage and confiscated at the airport. Lately, the number of illegally imported poultry and the incursion risk of transboundary pathogens through poultry products have been increasing. In this study, we isolated avian influenza viruses (AIVs) from raw poultry products illegally imported to Japan by international passengers. Highly (H5N1 and H5N6) and low (H9N2 and H1N2) pathogenic AIVs were isolated from raw chicken and duck products carried by flight passengers. H5 and H9 isolates were phylogenetically closely related to viruses isolated from poultry in China, and haemagglutinin genes of H5N1 and H5N6 isolates belonged to clades 2.3.2.1c and 2.3.4.4, respectively. Experimental infections of H5 and H9 isolates in chickens and ducks demonstrated pathogenicity and tissue tropism to skeletal muscles. To prevent virus incursion by poultry products, it is important to encourage the phased cleaning based on the disease control and eradication and promote the reduction in contamination risk in animal products.

Aberrant trafficking of a proteolipid protein in a mild Pelizaeus-Merzbacher disease.

Pelizaeus-Merzbacher disease (PMD) is a rare X-linked leukodystrophy caused by proteolipid protein 1 (PLP1) gene mutations. Previous studies indicated that proteolipid proteins (PLPs) with disease-associated mutations are misfolded and trapped in the endoplasmic reticulum (ER) during transportation to the cell surface, which eventually leads to oligodendrocyte cell death in PMD. Here we report a PMD patient with a very mild phenotype carrying a novel mutation (485G-->T) in exon 4 of the PLP1 gene that causes a Trp(162)Leu substitution in the protein. We also investigated intracellular trafficking of this mutant PLP in COS-7 cells. Transiently transfected mutant PLP(W162L) fused to an enhanced green fluorescent protein (EGFP) or a short peptide tag was not carried to the plasma membrane. However, in contrast to previous studies, this mutant PLP was not retained in the ER, indicating an escape of the newly translated protein from the quality control machinery. We also found that the mutant PLP accumulated in the nuclear envelope (NE) in a time-dependent manner. This mutant PLP, with its distribution outside the ER and a very mild phenotype, supports the idea that accumulation of misfolded mutant protein in the ER causes the severe phenotype of PMD.

Role of tissue plasminogen activator receptor LRP in hippocampal long-term potentiation.

The low-density lipoprotein (LDL) receptor-related protein (LRP) is a multifunctional endocytic receptor that is expressed abundantly in neurons of the CNS. Both LRP and several of its ligands, including tissue plasminogen activator (tPA), apolipoprotein E/lipoproteins, alpha(2)-macroglobulin, and the beta-amyloid precursor protein, have been implicated in various neuronal functions and in the pathogenesis of Alzheimer's disease. It has been reported that induction of tPA expression may contribute to activity-dependent synaptic plasticity in the hippocampus and cerebellum. In addition, long-term potentiation (LTP) is significantly decreased in mice lacking tPA. Here we demonstrate that tPA receptor LRP is abundantly expressed in hippocampal neurons and participates in hippocampal LTP. Perfusion of hippocampal slices with receptor-associated protein (RAP), an antagonist for ligand interactions with LRP, significantly reduced late-phase LTP (L-LTP). In addition, RAP also blocked the enhancing effect of synaptic potentiation by exogenous tPA in hippocampal slices prepared from tPA knock-out mice. Metabolic labeling and ligand binding analyses showed that both tPA and LRP are synthesized by hippocampal neurons and that LRP is the major cell surface receptor that binds tPA. Finally, we found that tPA binding to LRP in hippocampal neurons enhances the activity of cyclic AMP-dependent protein kinase, a key molecule that is known to be involved in L-LTP. Taken together, our results demonstrate that interactions between tPA and cell surface LRP are important for hippocampal L-LTP.

Mediastinoscopic extended thymectomy for pediatric patients with myasthenia gravis.

BACKGROUND: Extended thymectomy is indicated for children with myasthenia gravis (MG) when drug-resistance or dependence is seen. We have employed a technique for mediastinoscopic extended thymectomy (MET) on children with MG. METHOD: A total of 14 children underwent MET at Kanagawa Children's Medical Center between 2005 and 2013. A mediastinal operation field was made by a V-shaped hook infrasternally to extirpate the thymus with adipose tissue around the thymus. RESULTS: The operation time and the amount of blood loss were 182±44 minutes and 34±43 ml, respectively. Postoperative complications, in the form of transient paralysis of the right recurrent nerve, occurred in 2 patients. The median length of postoperative hospital stay was 4.5 days. After MET, 6 patients achieved complete remission and 7 patients achieved steroid dose reduction, but no improvement was seen in 1 patient. CONCLUSIONS: This procedure offers the advantage of good surgical access for dissection around the bilateral phrenic nerves in extended total thymectomy, while achieving good cosmetic results.

Mutations in the proteolipid protein gene in Japanese families with Pelizaeus-Merzbacher disease.

Pelizaeus-Merzbacher disease (PMD) is a rare X-linked dysmyelinating disorder of the CNS resulting from abnormalities in the proteolipid protein (PLP) gene. Exonic mutations in the PLP gene are present in 10 to 25% of all cases. In investigating genotype-phenotype correlations, we screened five Japanese families with PMD for PLP gene mutations and compared their clinical manifestations. We identified two novel nucleotide substitutions in exon 5, at V208N and at P210L, in two families. In the remaining three families, there were no mutations detected. Although all patients satisfied the criteria for the classical form of PMD, two families not carrying the mutations showed milder clinical manifestations than those with the mutations. Since linkage analysis has shown homogeneity at the PLP locus in patients with PMD, our findings suggest that there may be genetic abnormalities other than exonic mutations that cause milder forms of PMD.

Induction of cyclooxygenase (COX)-2 but not COX-1 gene expression in apoptotic cell death.

In this study we assessed the regulation of cyclooxygenase (COX)-2 in models of apoptotic cell death in vivo and in vitro. By 6 h after hippocampal colchicine injection in rat, COX-2 (but not COX-1) mRNA expression was elevated. The induction of COX-2 mRNA expression preceded temporally and overlapped anatomically the cellular morphological features of apoptosis in the granule cell layer of the dentate gyrus. Similarly, in an established in vitro model of apoptosis in P19 cells, COX-2 induction preceded apoptosis in response to serum deprivation by 12 h. These studies suggest that COX-2 may be involved in the early mechanisms leading to apoptosis.

Expression of C5a receptor in mouse brain: role in signal transduction and neurodegeneration.

In this study we explored the potential role of the complement derived anaphylatoxin C5a and the expression of its receptor in mouse brain. Using in situ hybridization, we found that C5a receptor messenger RNA is expressed in mouse brain. In response to intraventricular kainic acid injection, there was marked increase in the C5a receptor messenger RNA expression, particularly in hippocampal formation and cerebral cortex. C5a ligand-binding autoradiography confirmed the functional expression and elevation of the C5a receptor post-lesioning. The expression of C5a receptor messenger RNA in brain was confirmed by northern blot hybridization of total RNA from neuronal and glial cells in vitro. Based on these findings we explored the role of C5a in mechanisms of signal transduction in brain cells. Treatment of primary cultures of mouse astrocytes with human recombinant C5a resulted in the activation of mitogen-activated extracellular signal-regulated protein kinase. This response appeared to be mediated by the C5a receptor since astrocyte cultures derived from C5a receptor knockout mice were not responsive to the treatment. Understanding the regulation of C5a receptor in brain and mechanisms by which pro-inflammatory C5a modulates specific signal transduction pathways in brain cells is crucial to studies of inflammatory mechanisms in neurodegeneration.

Requirement for cAMP/calcium response element but not AP-1 site in fibroblast growth factor-2-elicited activation of tyrosine hydroxylase gene expression in PC12 cells.

Basic fibroblast growth factor (FGF-2) mediates numerous important physiological processes, including differentiation and survival of dopaminergic neurons. FGF-2 was found to trigger elevation of tyrosine hydroxylase (TH) gene expression in PC12 cells that was sustained for 1-8 days. FGF-2 induced chloramphenicol acetyltransferase (CAT) reporter activity under control of the TH promoter, indicating that the induction is transcriptionally mediated. The transcriptional activation of TH by FGF-2 was examined using various deletions and point mutations of the 5' flanking region controlling CAT reporter activity. In contrast to the reported mechanisms of transcriptional regulation of TH expression by NGF and phorbol esters, the AP-1 site at -205/-199 was not required for the activation by FGF-2. A construct containing only 60 nucleotides of the promoter was still inducible by FGF-2. However, a construct with a point mutation in the CRE/CaRE was not responsive to induction by FGF-2. These findings indicate that the CRE/CaRE, but not the AP-1, element is required for induction by FGF-2 and point to differences between NGF and FGF-2 in the regulation of TH gene expression.

Microarray expression analysis of gad mice implicates involvement of Parkinson's disease associated UCH-L1 in multiple metabolic pathways.

Parkinson's disease (PD) is thought to be caused by environmental and genetic factors. Mutations in four genes, alpha-synuclein, parkin, DJ-1, and UCH-L1, have been identified in autosomal inherited forms of PD. The pathogenetic cause for the loss of neuronal cells in PD patients, however, remains to be determined. Due to the rarity of mutations in humans with PD, the analysis of animal models might help to further gain insights into the pathogenesis of familial PD. For UCH-L1, deficiency has been described in gad mice leading to axonal degeneration and formation of spheroid bodies in nerve terminals. Here, we investigated the gene expression pattern of the brain of 3-month-old Uch-l1-deficient gracile axonal dystrophy (gad) mice by microarray analysis. A total of 146 genes were differentially regulated by at least a 1.4-fold change with 103 being up-regulated and 43 being down-regulated compared with age and sex matched wildtype littermate mice. The gene products with altered expression are involved in protein degradation, cell cycle, vesicle transport, cellular structure, signal transduction, and transcription regulation. Most of the genes were modestly regulated, which is in agreement that severe alteration of these pathways might be lethal. Among the genes most significantly down-regulated is the brain-derived neurotrophic factor which might be one aspect of the pathogenesis in gad mice. Interestingly, several subunits of the transcription factor CCAAT/enhancer binding protein are up-regulated, which plays a central role in most altered pathways.

Toxins selective for subunit interfaces as probes of nicotinic acetylcholine receptor structure.

The pentameric structure of the nicotinic acetylcholine receptor with two of the five subunit interfaces serving as ligand binding sites offers an opportunity to distinguish features on the surfaces of the subunits and their ligand specificity characteristics. This problem has been approached through the study of assembly of subunits and binding characteristics of selective peptide toxins. The receptor, with its circular order of homologous subunits (alpha gamma alpha delta beta), assembles in only one arrangement, and through mutagenesis, the residues governing assembly can be ascertained. Selectivity of certain toxins is sufficient to readily distinguish between sites at the alpha gamma and alpha delta interfaces. By interchanging residues on the gamma and delta subunits, and ascertaining how they interact with the alpha-subunit, determinants forming the binding sites can be delineated. The alpha-conotoxins, which contain two disulfide loops and 12-14 amino acids, show a 10,000-fold preference for the alpha delta over the alpha gamma subunit interface with alpha epsilon falling between the two. The waglerins, as 22-24 amino acid peptides with a single core disulfide loop, show a 2000-fold preference for alpha epsilon over the alpha gamma and alpha delta interfaces. Finally, the 6700 Da short alpha-neurotoxin from N. mossambica mossambica shows a 10,000-fold preference for the alpha gamma and alpha delta interfaces over alpha epsilon. Selective mutagenesis enables one to also distinguish alpha-neurotoxin binding at the alpha gamma and alpha delta subunits. This information, when coupled with homology modeling of domains and site-directed residue modification, reveals important elements of receptor structure and conformation.

Hypomethylation of the rat tyrosine hydroxylase gene correlates with its expression in several cell types.

Changes in the methylation patterns of genes have been implicated in controlling tissue-specific gene expression. Since the mechanism which causes the developmental appearance of tyrosine hydroxylase (TH) is unknown, we examined the extent of DNA methylation in the rat TH gene is PC12, F4 and liver cells, which differ in their expression of TH. Using methylation-sensitive restriction endonucleases, we found that hypomethylation of the TH gene correlated with its expression in these cells.

Proton MR spectroscopy in Pelizaeus-Merzbacher disease.

Proton MR spectroscopic findings in two patients with genetically defined Pelizaeus-Merzbacher disease revealed ratios of N-acetylaspartate/creatine and choline-containing compounds/creatine that were not significantly different from those found in a population of healthy subjects. These findings suggest that proton MR spectroscopy can aid in the diagnosis of Pelizaeus-Merzbacher disease.