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Xi-ru Wu

Publications and source records attributed to Xi-ru Wu.

At least 19 recordsLinked to original sources
PubMed2006

[Knocking down rat Mecp2 expression by RNAi].

OBJECTIVE: To find the valid siRNA (small interference RNA) sequence to knock down rat Mecp2 expression for the analysis of Mecp2 function by RNA interference (RNAi). METHODS: A plasmid (pMecp2-RFP) expressing rat Mecp2 and marker gene red fluorescent protein (RFP) as a fusion gene was constracted. We first selected a candidate valid sequence by cotransfecting the pMecp2-RFP with 4 candidate siRNAs targeting rat Mecp2 to HEK293T cells respectively, and then identified the RNAi efficiency of the candidate valid siRNA by detecting its effect on suppressing the expression of endogenous rat Mecp2 in PC12 cells. RESULTS: siRNA sequence (5'-GCUGUGAAGGAAUCUUCUA-3') targeting rat Mecp2 mRNA 918-936nt was the valid sequence to knock down rat Mecp2 expression by RNA interference. As the target sequence was located in exon 4 of rat Mecp2 mRNA, we assumed that it could suppress the expression of Mecp2alpha and Mecp2beta at the same time. And as the target sequence was located in the coding region of rat Mecp2, we assumed that it could suppress the expression of both 1.9 kb and 10 kb of rat Mecp2 transcript. CONCLUSION: This study has laid the foundation for constructing rat Mecp2 knocked-down neuronal cell model to study the gene function of Mecp2 in brain development.

Animals↗
PubMed2006

Clinical and laboratory survey of 65 Chinese patients with Leigh syndrome.

BACKGROUND: Leigh syndrome is an inherited neurodegenerative disease that emerges in infancy and childhood and presents with a clinically heterogeneous variety of neuromuscular and non-neuromuscular disorders. It can result from the inheritance of mutations in either nuclear or mitochondrial DNA. In the current study, we performed a retrospective study in 65 patients in order to investigate the clinical and genetic characteristics of Leigh syndrome in Chinese patients. METHODS: Sixty-five unrelated cases (35 men and 30 women) who were hospitalized in the past 12 years were reviewed. Diagnosis was based on both the clinical presentation and the characteristic neuropathologic findings of bilateral symmetric necrotizing lesions in the basal ganglia and brain stem as detected using cranial computed tomography (CT) scan or magnetic resonance imaging (MRI). The differential diagnosis of organic acidurias and fatty acid beta-oxidation defects were performed. Specific point mutations and deletions in mitochondrial DNA (T8993G, T8993C, T9176C, A8344G, A3243G) were screened by PCR-restriction analysis and Southern blot. The SURF1 gene was sequenced. Skeletal muscle biopsies were performed in 17 (26.2%) of the patients. The diagnosis was confirmed by autopsy in 6 (9.2%) patients. RESULTS: The patients had various forms of metabolic encephalomyopathy. Fifty-nine (90.8%) of the patients had the typical neuroradiological features of Leigh syndrome, including symmetrical necrotizing lesions scattered within the basal ganglia, thalamus and brain stem. Twenty (30.8%) patients were confirmed by genetic, biochemical analysis and autopsy. Specific point mutations in mitochondrial DNA were found in 5 cases (7.7%). Of these, the A8344G mutation was detected in 2 patients. The T8993G, T8993C, and A3243G point mutations were identified in 3 other patients, respectively. SURF1 mutations associated with cytochrome c oxidase deficiency were identified in 8 (12.3%) families by DNA sequencing. A G604C mutation was identified in 6 (9.2%) patients. The genotypes of 52 patients remained unknown. CONCLUSIONS: Leigh syndrome presents as a diverse array of clinical features and can result from specific mutations in nuclear or mitochondrial DNA. In this study, SURF1 mutations associated with cytochrome c oxidase deficiency were identified in 8 (12.3%) out of 65 patients with Leigh syndrome. It indicates that SURF1 mutations might be a common cause of Leigh syndrome in China. The etiology of Leigh syndrome in Chinese patients represents a persistent challenge to clinicians.

Adolescent↗
PubMed2006

The genotype and phenotype studies of 40 Chinese patients with X-linked adrenoleukodystrophy (X-ALD).

OBJECTIVE: To elucidate the phenotype and the genotype-phenotype correlations in Chinese patients with X-linked adrenoleukodystrophy (X-ALD). METHODS: Clinical features of 40 Chinese patients with X-ALD were studied and mutation spectrums were investigated by polymerase chain reaction (PCR) and sequencing. RESULTS: Among these patients, four were siblings from two unrelated families, the others were unrelated. There were 31 cases with childhood cerebral (CCALD), 8 cases with adolescent cerebral (ACALD) and 1 case with adrenomyeloneuropathy (AMN). Visual impairment, which presented in 12 cases (30%), was the most common initial symptom. Nine (69%) of 13 cases who had hydrocortisone and ACTH measured showed adrenal insufficiency. By follow-up date, 19 cases (47.5%) were dead. The interval from onset to death varied from 1 to 6 years and the average were 3.3 years. The mean age at death was 10.5 years. Eleven cases (27.5%) were in vegetable state. The mean interval from onset to apparently vegetable state was 2.8 years (range from 1 to 6 years). Four cases had progressive neurological disability. Four cases were lost follow-up. One case with CCALD and one case with ACALD progressed slowly. The courses of the disease of these two patients were 5 years and 15 years respectively. Thirty five mutations were identified in 40 cases. Most were located within exon 1-3 (40%, 16/40) and exon 6-8 (42%, 17/40). There is a distinct clustering of missense mutations in exon 6 (17%, 7/40). Five types of mutations were associated with CCALD, three with ACALD and a missense mutation was identified in the patients with AMN. The two patients with long disease courses had a missense mutation c.1559 T>A and a nonsense mutation c.1785 G>A respectively. The siblings with similar manifestations and onset age were observed in two families, whose mutations were c.887 A>G and c.1028 G>T. CONCLUSION: The phenotypes, disease severity and rate of neurodegeneration could not be predicted by the nature of mutations.

Adolescent↗
PubMed2006

Medical genetic issues in clinical of pediatric neurology practice:a history of pediatrics in Peking University First Hospital.

The Department of Pediatrics of Peking University First Hospital has a long term of outstanding history. It was established about 60 years ago. After the division of pediatric neurology (DPN) had been established in 1960s, it had been assigned to cover genetic disorders. During the recent 20 years, efforts have been put on three aspects: (1) Pediatric neurology clinical service and education; (2) research studies of childhood epilepsies and pediatric neurogenetic disorders; and (3) development of a strong DPN team to establish a comprehensive pediatric neurological program. In this paper, we reviewed the history of the pediatric neurology division in our department, our clinical and research work and achievements for neurogenetic diseases.

Genetic Techniques↗
PubMed2006

[Research on genes susceptible to childhood absence epilepsy].

Despite a few genes that do not encode ion channels have been identified as implicating some kinds of human idiopathic epilepsies(IE) in recent years, but genetic discoveries have shown the ion channels to play a central role in genetic pathomechanism of IE. The gene mutations of ion channels are a common cause of some rare monogenic IE which could be so-called as channelopathies, and able to be applied to account for the questioned epileptic syndrome to minority of families and sporadic cases. However, more frustrating has been from the genetic research on more common IE with complex inheritance due to the unknown mode of inheritance, the phenotypic heterogeneity and the uncertainty of genetic overlap among syndrome subtypes, which have limited gene mapping. Absence epilepsy is a kind of common IE subtype and shows a complex way to inherit. Evidences from heredity investigation indicate that eleven genes are correlated with absence epilepsy, of which four encode the neuronal calcium channel subunits. Therefore, calcium channel genes may be considered as important candidates for involving in absence epilepsy. To focus the genetics research on calcium channel genes of absence epilepsy may be opening an optimal gate to the pathogenetic study of more common IE with complex inheritance, and benefit to elucidate the molecular mechanisms of absence epilepsy finally, one of the more common IE subtypes with complex inheritance.

Calcium↗
PubMed2006

[MECP2 gene mutations in twenty-six cases with atypical Rett syndrome].

OBJECTIVE: Rett syndrome (RTT) is an X-linked progressive neurodeveopmental disorder that almost exclusively affects girls, and is one of the most common causes of mental retardation in females, with an estimated prevalence of approximately 1 in 10,000 - 15,000 female individuals. Mutations in X-linked methyl-CpG-binding protein 2 (MECP2) gene, located on chromosome Xq28, have been found to be a cause of RS. A lot of mutations have been reported to be related to RS recently. Mutations are found in 70% - 85% of patients with classical RTT and in less than 50% of patients with atypical RS. Up to now, RTT is diagnosed based on a consistent counseling for clinical features and the established diagnostic criteria. The present study aimed to investigate frequency and type of mutation of MECP2 gene and if hot spot of mutation exits in patients with atypical RTT and find out the relationship between genotype and phenotype. METHODS: A systematic analysis of the entire coding region of MECP2 in 26 unrelated patients with atypical RTT was performed by polymerase chain reaction (PCR) and direct sequencing. Genomic DNA was extracted using standard procedures from the peripheral blood leukocytes of each patient. PCR amplification products were checked by 2% agarose gel electrophoresis and were subsequently sequenced with ABI 3730 Automated DNA Sequencer with both the forward and reverse primers. Mutational analyses were performed using normal human genomic MECP2 sequence as a reference (GenBank accession NO.AF030876). RESULTS: Seven mutations were identified in 12 of 26 patients. Most of the mutations were missense mutation; c.397C > T (R133C) was found in 3 of 26 patients; c.473C > T (T158M) and c.916C > T (R306C) were found in 2 of 26 patients, respectively; c.397A > G (R133H) and c.1005G > A (R335C) were found in 1 of 26 patients, respectively. One base pair deletion mutation (806delG) resulting in frameshift was found in 2 of 26 patients, and 1 base pair transversion at splice accept-site (IVS3-2A > T). CONCLUSION: The results of this study indicated that c.397C > T (R133C), c.473C > T (T158M) and c.916C > T (R306C) were hot spot mutations in MECP2 gene of patients with atypical RTT. There was some relationship between genotype and phenotype.

Base Sequence↗
PubMed2006

[The effect of CACNA1H gene G773D mutation on calcium channel function].

OBJECTIVE: To study the effect of CACNA1H gene mutation G773D on calcium channel function. METHODS: By the overlap extension PCR we introduced G773D mutation into a human Cav3.2acDNA for constructing the mutant. And then using whole cell clamp technique, we studied the alterations of channel behavior in transfected HEK-293 cells. RESULTS: There were no difference in kinetics of activation and inactivation of calcium channel between wild type and mutant. However comparing with the wild-type Cav3.2 channel, G773D mutant could increase the calcium current density significantly. CONCLUSION: CACNA1H gene G773D mutation is able to increase calcium current and neuronal excitability.

Base Sequence↗
PubMed2006

[Analysis of ARSA mutations in a Chinese family with metachromatic leukodystrophy].

OBJECTIVE: To identify arylsulftase A gene (ARSA) mutations in a Chinese family with MLD. METHODS: There were two MLD patients in the investigated family. The proband, an 11-year-old girl, was well until the age of 5 years, when she began to experience difficult walking and mental regression. Magnetic resonance imaging (MRI) of her brain showed widespread demyelination, nerve conduction velocity reduced, and ASA activity measured in white blood cells was zero. So, the child was diagnosed having MLD. The proband's young brother also got the same phenotype except clinical symptom being milder than hers. Their parents and elder sister all had normal phenotypes. Genomic DNA samples were extracted from peripheral bloods of the proband and all her family members. All 8 exons and exon-intron boundaries of ARSA gene were amplified by polymerase chain reaction (PCR) and followed by direct DNA sequencing. RESULTS: Two heterozygous mutations of ARSA, which were named as, G251A (R84Q) and G296T (G99V) were identified in the proband. The two mutations were located in exon 2. The same genotype was found in the proband's young brother, but these mutations were not detected in proband's elder sister. The proband's mother had the heterozygous mutations G296T (G99V), and her father had the heterozygous mutation G251A (R84Q). CONCLUSION: These two MLD patients are with both compound heterozygous mutations, which mean one allele with the G296T (G99V) mutation was from their mother, and the other allele with the G251A (R84Q) mutation got from their father. The parents are both carrier with normal phenotype.

Alleles↗
PubMed2006

[X chromosome inactivation patterns in patients with Rett syndrome and their mothers and the parental origin of the priority inactive X chromosome].

OBJECTIVE: Rett syndrome (RTT) is a severe childhood neurodevelopmental disorder mainly affecting females. The pathogenic gene is located at Xq28, which codes for the methyl-CpG-binding protein 2. MECP2 gene is affected by X chromosome inactivation (XCI). The different XCI patterns of females could affect the expression ratios of pathogenic gene, causing changes in clinical symptoms. In order to understand the XCI patterns in RTT patients and the relationship between XCI pattern, genotype and phenotype, the XCI patterns in patients with RTT and their mothers, the parental origin of the priority inactive X chromosome in RTT, and the relations of XCI patterns with genotype and phenotype in RTT cases were analyzed. METHODS: Genomic DNA was extracted from peripheral blood of 55 cases with RTT (52 with MECP2 mutations, 3 without mutations), 53 mothers of RTT cases and 48 normal female controls. DNA was digested with methylation sensitive restriction endonuclease Hpa II. Then the undigested and digested DNAs were amplified via PCR for the first exon of human androgen receptor (AR) gene. PCR products were analyzed by Genescan. RESULTS: The heterozygotic rates of AR gene were 82%, 77% and 83% in RTT patients, mothers and controls, respectively. XCI distribution pattern of RTT was different from that of the mothers and control, P < 0.05. More mothers and controls than RTT patients were in the area of XCI 50:50 - 59:41. The differences between them were statistically significant (P < 0.05). No significant difference in XCI distribution patterns between mothers and the control groups was found (P > 0.05). Non-random XCI rates in the areas of XCI >or= 65:35 and >or= 80:20 were 53.35% and 17.8%, respectively, in RTT patients, compared with the mothers group (36.6%, 7.3%) and control group (35%, 10%), it was higher in RTT patients, but the difference was not statistically significant (P > 0.05). In 18 of 21 cases with XCI >or= 65:35, the priority inactive X chromosome was of paternal origin (85.7%). Variable XCI patterns were observed in the same gene mutation patients. The highly skewed XCI as well as the random XCI were found in patients with mild, severe and typical phenotype. The rate of highly skewed XCI in atypical patients was higher than that in typical RTT patients. The rate of highly skewed XCI in T158M was higher than the other type mutations. No highly skewed XCI was observed in cases with R133C mutation. CONCLUSION: The XCI distribution pattern of RTT patients was different from that of RTT mother and control groups. There was no significant difference in XCI distribution patterns between mothers and the control groups. It was not a main genetic pattern in RTT that mothers as the carriers to transmit the pathogenic gene to the patients. Non-random XCI was not the main XCI pattern in RTT patients. The priority inactive X chromosome was mainly of paternal origin. XCI could modify the clinical phenotype of RTT, but had limitations in explaining all the phenotypes manifested in RTT cases.

Adolescent↗
PubMed2005

[Advances of research in ion channels in idiopathic epilepsy].

Epilepsy is a kind of brain dysfunction syndrome caused by so many reasons instead of a certain disease. Abnormal neuron discharge can cause epilepsy. Idiopathic epilepsy refers to epilepsy or epilepsy syndrome without any latent reasons but inherited trait. Idiopathic epilepsy is confirmed as an ion channelopathy at present. The first genemutation was found in idiopathic epilepsy in 1995, and a lot of genes coding either voltage-gated or ligand-gated ion channels have been found since then. In the present review, some new advances in research on ion channels dysfunction in idiopathic epilepsy are summarized.

Animals↗
PubMed2005

[Recent advances in the diagnosis and treatment of lysosomal storage diseases].

Lysosomal storage diseases are a group of genetic disorders that result from the defect in lysosomal function. Signs and symptoms are variable, it is difficult to diagnose this group of disease merely by the clinical manifestation. The diagnosis usually is made by measuring the activity of the corresponding enzyme. Gene mutational analysis is useful for the diagnosis of some of the lysosome storage diseases. The treatment has focused on the replacement of the defective enzyme responsible for the disease and the hematopoietic stem cell transplantation. Both of them have achieved exciting outcomes in some of the diseases.

Gangliosidoses, GM2↗
PubMed2005

[Helper-virus-free herpes simplex virus-1 vector mediated LacZ gene expression in cultured cortical neurons].

OBJECTIVE: To obtain knowledge about the helper-virus-free packaging system of HSV-1 vector and its use in cultured neurons by investigating helper-virus-free packaging of HSV-1 vector and LacZ gene expression mediated by the vector in rat cultured cortical neurons. METHODS: The cosmids with inserts of HSV-1 genome were digested by Pac I, purified and cotransfected with HSV plasmid vector DNA (with LacZ gene) into 2-2 cells. After 3 hour incubation at 37 degrees C, the media were changed into DMEM with 6% CCS. And the 2-2 cells were incubated for 72 hours at 34 degrees C. Then the virus particles were harvested. The medium with the virus particles was added to BHK cells. After 24 hour further culture, X-gal staining was performed. The virus particles were added to 3 day cultured cortical neurons. After 1, 7 and 14 day further cultures, neurons were stained by X-gal and observed under microscope. RESULTS: The BHK cells (stained blue) expressing LacZ gene could be seen after 24 hour further culture. After 1, 7 and 14 day further cultures, neurons stained blue by X-gal staining could be seen all the time in different groups. CONCLUSION: Helper-virus-free package system can produce effective virus particles from HSV-1 plasmid vector with A tyrosine TH-NF chimeric promoter and mediate stable exogenous gene expression in cultured neurons, thus providing a useful tool for gene transfer and study of gene function in the nervous system.

Animals↗
PubMed2005

[T-type calcium channel gene-CACNA1H is a susceptibility gene to childhood absence epilepsy].

OBJECTIVE: Childhood absence epilepsy (CAE) is one of the most frequently recognized syndromes among the idiopathic generalized epilepsies (IGEs). It is considered to be a hereditary disease. The possible inheritance pattern of CAE is polygenic. The genes responsible for CAE, however, have not yet been identified. The aim of this study was to further investigate based on the authors' recent work whether or not T-type calcium channel gene-CACNA1H is a susceptibility gene to childhood absence epilepsy. METHODS: The authors conducted the mutation screening of the exons 6-12 and the nearby partial introns of the CACNA1H gene using the method of direct sequencing of PCR products in 48 newly found CAE patients. RESULTS: The authors found 13 single nucleotide polymorphisms (SNPs). They also found 4 mutations which only existed in CAE patients. Both G773D and H515Y mutations were heterozygous. The mutation of H515Y has never been reported previously. The patient inherited the mutation from his mother. The authors found two CAE patients with the mutation of G773D previously. This is the third time that the authors found one more CAE family with this G773D mutation, and the patient with the mutation G773D inherited the mutation from his father. CONCLUSION: T-type calcium channel gene-CACNA1H might be a susceptibility gene to childhood absence epilepsy.

Amino Acid Sequence↗
PubMed2005

[Clinical and laboratory screening studies on urea cycle defects].

OBJECTIVE: To investigate the incidences of urea cycle defects (UCDs) in the patients with hyperammonemia and study their etiology, clinical and laboratory features. METHODS: In the past 7 years, 26 cases (10.2%) of UCDs were detected from 254 patients with hyperammonemia. The etiological diagnoses were made by blood amino acids analysis, urinary organic acid analysis and blood acylcarnitine profile analysis. Three patients with citrullinemia type II were further confirmed by liver pathological analysis and gene diagnosis. RESULTS: Among 26 cases with UCDs, 15 had ornithine transcarbamylase (OTC) deficiency, 5 had citrullinemia type I, 3 had citrullinemia type II and 3 patients had arginemia. The age of onset of the patients ranged from 3 days to 13 years. Three cases (11.5%) developed hyperammonemic encephalopathy during neonatal period. Thirteen (50.0%), 7 (26.9%) and 3 (11.5%) cases developed clinical symptoms at the age of 1 to 12 months, 1 to 3 years and 6 to 13 years, respectively. Positive family history was found in 11 cases (42.3%). Among 26 patients with UCDs, 9 (34.6%) were hospitalized with the complains of seizures, psychomotor retardation, vomiting and unconsciousness, 8 (30.8%) with recurrent vomiting, headache and coma, 6 due to liver dysfunction. Intrahepatic cholestatic jaundice was found in 3 patients with citrullinemia type II. Blood ammonia ranged from 58 to 259 micromol/L on their first visit to our hospital. Twenty cases (76.9%) had liver dysfunction, 4 patients (15.4%) were diagnosed postmortem. Twenty-one patients got treatment and were followed up. Among them, 7 cases died of hyperammonemic encephalopathy or upper alimentary tract bleeding. Clinical improvement was observed in 14 cases. A boy with OTC deficiency who received a partial liver transplant from his mother showed normal general condition for two years. CONCLUSIONS: UCDs are the most frequent causes of congenital hyperammonemia. In this study, 26 patients (10.2%) with UCDs were identified from 254 patients with hyperammonemia resulting in encephalopathy and liver dysfunction. Early diagnosis and treatment can contribute a lot to improve the prognosis of the patients. Blood ammonia assay and further etiological analysis should be considered in the differential diagnosis of neurological and hepatic abnormality.

Adolescent↗
PubMed2005

[Screening for carrier and prenatal diagnosis of X-linked adrenoleukodystrophy].

OBJECTIVE: X-linked adrenoleukodystrophy (X-ALD) is the most common peroxisomal disorder characterized by progressive demyelination of the central nervous system, adrenal cortex insufficiency and accumulation of saturated very long chain fatty acids (VLCFAs) in tissues and body fluids due to the impaired beta-oxidation in peroxisomes. X-ALD shows a wide range of phenotypic variation. Childhood cerebral form (CCER) is the most common phenotype with severe neurological symptoms and often the average interval from onset to total disability or death is 3 years. So far no effective treatment is available for the underlying defect. Screening for carriers of mutated relevant gene and prenatal diagnosis are very important for the prevention of the disease. In this study, the authors explored the method of carrier screening and prenatal diagnosis of X-ALD. METHODS: The plasma VLCFAs levels of 83 suspected carriers for ALD were determined by using GC/MS and ABCD1 gene mutational analysis was performed in 31 of them. Amniocentesis was performed in 9 suspected carriers for ALD during 18 - 30 gestational weeks. The VLCFAs level of cultured amniocytes was tested with GC/MS. ABCD1 gene mutational analysis was performed on two cases (one was a male and the other a female) whose VLCFAs levels of amniocytes were found elevated. The plasma VLCFAs levels were measured in five of the nine prenatally diagnosed children when they were 1 day to 3.5 years old. RESULTS: Fifty-one of 83 suspected carriers had high plasma VLCFAs levels; 29 of 31 suspected carriers showed ABCD1 gene mutation. Among the nine fetuses, four were males and five were females. The VLCFAs levels of the cultured amniocytes were high in two cases, one was female and the other a male. ABCD1 gene mutational analysis of these two cases showed a 871G > A (E291K) mutation and a 726G > A (W242X) mutation, respectively, which confirmed the biochemical result. The VLCFAs levels were normal in the rest of cases and five of them were confirmed by postnatal plasma VLCFAs assay. CONCLUSION: The carrier screening and prenatal diagnosis are very important for prevention of the X-ALD. Only the combined use of plasma VLCFAs level analysis and ABCD1 gene mutational analysis could detect X-ALD carriers correctly. ABCD1 gene mutational analysis and postnatal plasma VLCFAs level test verified that amniocytes VLCFAs level analysis is a reliable prenatal diagnostic method for this disease.

ATP Binding Cassette Transporter, Subfamily D, Mem↗