Biomedical subjects

X Ke

Publications and source records attributed to X Ke.

At least 19 recordsLinked to original sources

PubMed2005

Uteroplacental insufficiency affects epigenetic determinants of chromatin structure in brains of neonatal and juvenile IUGR rats.

Intrauterine growth retardation (IUGR) increases the risk of neuroendocrine reprogramming. In the rat, IUGR leads to persistent changes in cerebral mRNA levels. This suggests lasting alterations in IUGR cerebral transcriptional regulation, which may result from changes in chromatin structure. Candidate nutritional triggers for these changes include altered cerebral zinc and one-carbon metabolite levels. We hypothesized that IUGR affects cerebral chromatin structure in neonatal and postnatal rat brains. Rats were rendered IUGR by bilateral uterine artery ligation; controls (Con) underwent sham surgery. At day of life 0 (d0), we measured cerebral DNA methylation, histone acetylation, expression of chromatin-affecting enzymes, and cerebral levels of one-carbon metabolites and zinc. At day of life 21 (d21), we measured cerebral DNA methylation and histone acetylation, as well as the caloric content of Con and IUGR rat breast milk. At d0, IUGR significantly decreased genome-wide and CpG island methylation, as well as increased histone 3 lysine 9 (H3/K9) and histone 3 lysine 14 (H3/K14) acetylation in the hippocampus and periventricular white matter, respectively. IUGR also decreased expression of the chromatin-affecting enzymes DNA methyltransferase 1 (DNMT1), methyl-CpG binding protein 2 (MeCP2), and histone deacetylase (HDAC)1 in association with increased cerebral levels of zinc. In d21 female IUGR rats, cerebral CpG DNA methylation remained lower, whereas H3/K9 and H3/K14 hyperacetylation persisted in hippocampus and white matter, respectively. In d21 male rats, IUGR decreased acetylation of H3/K9 and H3/K14 in these respective regions compared with controls. Despite these differences, caloric, fat, and protein content were similar in breast milk from Con and IUGR dams. We conclude that IUGR results in postnatal changes in cerebral chromatin structure and that these changes are sex specific.

Acetylation↗

PubMed2005

A novel locus for autosomal dominant non-syndromic deafness, DFNA53, maps to chromosome 14q11.2-q12.

BACKGROUND: Non-syndromic hearing loss is among the most genetically heterogeneous traits known in humans. To date, at least 50 loci for autosomal dominant non-syndromic sensorineural hearing loss (ADNSSHL) have been identified by linkage analysis. OBJECTIVE: To report the mapping of a novel autosomal dominant deafness locus on the long arm of chromosome 14 at 14q11.2-q12, DFNA53, in a large multigenerational Chinese family with post-lingual, high frequency hearing loss that progresses to involve all frequencies. RESULTS: A maximum multipoint LOD score of 5.4 was obtained for marker D14S1280. The analysis of recombinant haplotypes mapped DFNA53 to a 9.6 cM region interval between markers D14S581 and D14S1021. Four deafness loci (DFNA9, DFNA23, DFNB5, and DFNB35) have previously been mapped to the long arm of chromosome 14. The critical region for DFNA53 contains the gene for DFNA9 but does not overlap with the regions for DFNB5, DFNA23, or DFNB35. Screening of the COCH gene (DFNA9), BOCT, EFS, and HSPC156 within the DFNA53 interval did not identify the cause for deafness in this family. CONCLUSIONS: Identifying the DFNA53 locus is the first step in isolating the gene responsible for hearing loss in this large multigeneration Chinese family.

Adolescent↗

PubMed2003

CpG islands in human X-inactivation.

Sequence comparison analyses have been carried out for 19 genes escaping X-inactivation versus 73 genes subject to X-inactivation, and 100 randomly chosen X chromosome genes versus 100 randomly chosen autosomal genes. The coding sequence of the genes and their upstream and downstream flanking sequences were investigated using a series of windows (1 kb, 2 kb, 5 kb, 10 kb and 100 kb). No significant difference in number of LINE-L1 elements was observed in genes escaping X-inactivation compared to genes subject to X-inactivation. This result, therefore, does not support the suggestion that lack of LINE repeat elements is a key factor for genes escaping X-inactivation. However, significantly reduced numbers of CpG islands and SINE MIR elements were found to be associated with genes escaping X-inactivation. Compared to genes known to be inactivated, genes escaping X-inactivation were observed to have fewer CpG islands, particularly within the 2 kb upstream flanking sequence close to the coding region. The results suggest that CpG islands may play a role in the process of X-inactivation by providing sufficient DNA methylation targets for the maintenance of X-inactivation. Lack of CpG islands may be a major reason for genes escaping X-inactivation regulation.

CpG Islands↗

PubMed2002

The first linkage disequilibrium (LD) maps: delineation of hot and cold blocks by diplotype analysis.

Linkage disequilibrium (LD) provides information about positional cloning, linkage, and evolution that cannot be inferred from other evidence, even when a correct sequence and a linkage map based on more than a handful of families become available. We present theory to construct an LD map for which distances are additive and population-specific maps are expected to be approximately proportional. For this purpose, there is only a modest difference in relative efficiency of haplotypes and diplotypes: resolving the latter into 2-locus haplotypes has significant cost or error and increases information by about 50%. LD maps for a cold spot in 19p13.3 and a more typical region in 3q21 are optimized by interval estimates. For a random sample and trustworthy map the value of LD at large distance can be predicted reliably from information over a small distance and does not depend on the evolutionary variance unless the sample size approaches the population size. Values of the association probability that can be distinguished from the value at large distance are determined not by population size but by time since a critical bottleneck. In these examples, omission of markers with significant Hardy-Weinberg disequilibrium does not improve the map, and widely discrepant draft sequences have similar estimates of the genetic parameters. The LD cold spot in 19p13.3 gives an unusually high estimate of time, supporting an argument that this relationship is general. As predicted for a region with ancient haplotypes or uniformly high recombination, there is no clear evidence of LD clustering. On the contrary, the 3q21 region is resolved into alternating blocks of stable and decreasing LD, as expected from crossover clustering. Construction of a genomewide LD map requires data not yet available, which may be complemented but not replaced by a catalog of haplotypes.

Chromosome Mapping↗

PubMed2002

Recombination, interference and sequence: comparison of chromosomes 21 and 22.

The euchromatic regions of chromosomes 21 and 22 are almost completely sequenced and have similar lengths (33.7-34.6 Mb). This similarity effectively controls for the influence of length, making comparisons of recombination and interference interesting. For both chromosomes, there is less male than female recombination, and male recombination is associated with GT/CA repeats. The striking sex difference may result from greater condensation of chromosomes in paternal meiosis, possibly restricting recombination to regions with longer repeat tracts and/or higher repeat densities. Chiasma interference in both sexes for chromosome 22 and in females for chromosome 21 is close to the genome average. Chromosome 21 is significantly different in male meiosis, with near complete interference, suggesting that even when double recombinants occur they are widely spaced. We propose that this difference is related to the different distribution of GT/CA dinucleotides. These repeats are widely distributed on chromosome 22, perhaps offering greater opportunities for double recombinants to occur within smaller regions, whereas they are largely subtelomeric in distribution on chromosome 21.

Chromosome Mapping↗

PubMed2001

An efficient procedure for genotyping single nucleotide polymorphisms.

Analysis of single nucleotide polymorphisms (SNPs) has been and will be increasingly utilized in various genetic disciplines, particularly in studying genetic determinants of complex diseases. Such studies will be facilitated by rapid, simple, low cost and high throughput methodologies for SNP genotyping. One such method is reported here, named tetra-primer ARMS-PCR, which employs two primer pairs to amplify, respectively, the two different alleles of a SNP in a single PCR reaction. A computer program for designing primers was developed. Tetra-primer ARMS-PCR was combined with microplate array diagonal gel electrophoresis, gaining the advantage of high throughput for gel-based resolution of tetra-primer ARMS-PCR products. The technique was applied to analyse a number of SNPs and the results were completely consistent with those from an independent method, restriction fragment length polymorphism analysis.

DNA↗

PubMed2001

Nitric oxide regulates actin reorganization through cGMP and Ca(2+)/calmodulin in RAW 264.7 cells.

Nitric oxide (NO) has been reported to be involved in the regulation of pseudopodia formation, phagocytosis and adhesion in macrophages through the reorganization of actin. In the present study, we directly separated the globular (G) and filamentous (F) actin from quiescent or NO-stimulated macrophage-like cell line RAW 264.7 cells in order to investigate the dynamic redistribution of actin pools. We also focused on the regulatory mechanisms of actin assembly, induced by NO and its possible subsequent signaling pathway. We showed that predominant G-actin coexisted with Triton X-100-insoluble filamentous (TIF) and Triton X-100-soluble filamentous actin in resting RAW 264.7 cells. The exogenous NO produced by (+/-)-(E)-2-[(E)-hydroxyimino]-6-methoxy-4-methyl-5-nitro-3-hexenamide (NOR1), the endogenous NO induced by lipopolysaccharide (LPS) plus interferon-gamma (IFNgamma), and dibutyryl-cGMP increased the contents of TIF-actin in dose- and time-dependent manners and altered its morphology. The increase in the TIF-actin contents induced by NOR1 or LPS plus IFNgamma was efficiently blocked by the radical scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide and the soluble guanylate cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one or the arginine analogue N(G)-monomethyl-L-arginine acetate, respectively. Preincubation with the calmodulin antagonist W-7 almost completely blocked the NO-induced TIF-actin increase and morphological change. On the other hand, preincubation with C3 transferase, an inhibitor of Rho protein, efficiently prevented the change in cell morphology, but had no effect on the TIF-actin increase. We postulate that cGMP and subsequent Ca(2+)/calmodulin may be key regulators of actin reorganization in NO-stimulated RAW 264.7 cells.

Actins↗

PubMed2001

Card10 is a novel caspase recruitment domain/membrane-associated guanylate kinase family member that interacts with BCL10 and activates NF-kappa B.

BCL10 belongs to the caspase recruitment domain (CARD) family of proteins that regulate apoptosis and NF-kappaB signaling pathways. Analysis of BCL10-deficient mice has revealed that BCL10 mediates NF-kappaB activation by antigen receptors in B and T cells. We recently identified a subclass of CARD proteins (CARD9, CARD11, and CARD14) that may function to connect BCL10 to multiple upstream signaling pathways. We report here that CARD10 is a novel BCL10 interactor that belongs to the membrane-associated guanylate kinase family, a class of proteins that function to organize signaling complexes at plasma membranes. When expressed in cells, CARD10 binds to BCL10 and signals the activation of NF-kappaB through its N-terminal effector CARD domain. We propose that CARD10 functions as a molecular scaffold for the assembly of a BCL10 signaling complex that activates NF-kappaB.

Adaptor Proteins, Signal Transducing↗

PubMed2001

LDB2000: sequence-based integrated maps of the human genome.

MOTIVATION: Integrated maps are useful for gene mapping and establishing the relationship between recombination and sequence. In this paper we describe algorithms and their implementation for constructing sequence-based integrated maps of the human chromosomes, which are presented in LDB2000, a web based resource. Gene mapping efforts are now focussing on linkage disequilibrium mapping and extension of the integrated map to represent the extent of linkage disequilibrium in different genomic regions would further increase the utility of these maps. RESULTS: Sequence-based integrated maps have been completed for chromosomes 21 and 22. These maps provide locations for genes and polymorphic markers in sequence and on genetic linkage, radiation hybrid and cytogenetic scales. Single nucleotide polymorphisms associated with genes in the maps are also included and their sequence locations indicated. Related locus information, such as aliases and expression information, can be searched on the WWW site.

Algorithms↗

PubMed2001

PIRA PCR designer for restriction analysis of single nucleotide polymorphisms.

UNLABELLED: Primer-introduced restriction analysis (PIRA-PCR) is widely used to detect Single Nucleotide Polymorphisms (SNPs). To create artificial Restriction Fragment Length Polymorphism (RFLP), a mismatch is usually introduced near the end of the primer that is close to the mutation of interest. We describe in this report a www-based computer program that screens for the suitable mismatches, designs the primers, lists the appropriate restriction enzymes and other related information. AVAILABILITY: The computer program, with related descriptions, is available at http://cedar.genetics.soton.ac.uk/public_html/primer2.html.

Base Pair Mismatch↗

PubMed2001

A sequence-based integrated map of chromosome 22.

The near-completion of the sequence for chromosome 22q revolutionizes map integration. We describe a sequence-based integrated map containing 968 loci including 516 known or predicted gene sequences, 317 STSs not included in these sequences, and 135 nonexpressed multinucleotide polymorphisms. The published sequence spans 34.6 Mb, inclusive of gaps estimated to total 1.1 Mb, compared with a top-down estimate of 43 Mb. This discrepancy is discussed, but will not be resolved until more of the genome is analyzed. The radiation hybrid map has 5% error in order and 34% error in location exceeding 1 Mb. The utility of a composite location based on evidence other than sequence is limited to regions not yet sequenced. A genetic map conditional on sequence order was constructed from pairwise lods. Its length of 74.8 cM in males and 80.2 cM in females is slightly less than the previous estimate not constrained by sequence order. Five recombination hot spots are detected, with differences in location between the sexes. Male recombination correlates with repetitive DNA, whereas female recombination does not. It remains to be seen whether this is true for other human chromosomes. An algorithm to improve the fit of cytogenetic bands sequence location reduces the discrepancies in cytogenetic assignment from 61 to 38. This sequence-based integrated map is represented in the genetic location database (LDB2000), which is available at http://cedar.genetics.soton.ac.uk/public_html/LDB2000.html.

Base Sequence↗

PubMed2001

Autologous peripheral blood stem cell transplantation in the patients with hematologic malignancies and solid tumors.

OBJECTIVE: To evaluate the long-term therapeutic effects of autologous peripheral blood stem cell transplantation (auto-PBSCT) on the treatment of hematological and solid tumors. METHODS: Fifty-one patients were recruited in this auto-PBSCT study, in which several potentially important parameters were studied including the optimal time for stem cell collection, the dose of stem cell reinfusion, the time of hematopoietic reconstitution, the disease free survival (DFS) and overall survival (OS), complications related to transplantation, and maintenance chemotherapy after auto-PBSCT. RESULTS: After APBSCT, 3-year and 5-year survival rates of NHL were 83.3%; those of AML were 74.7%; those of MM were 37.9% and 19%; those of ALL were 40% and 0% respectively. Hematopoietic reconstitution was greatly promoted by granulocyte colony stimulating factor (G-CSF). The mean time for patients' neutrophil to recover up to > 0.5 x 10(9)/L after APBSCT was 11.14 days in the group of the patients receiving G-CSF in contrast to 17.6 days in the group receiving no G-CSF. The most common complications of transplantation were fever, liver dysfunction and hypokalaemia, which were curable. No death was due to transplantation related complications. CONCLUSION: Comparing with conventional chemotherapy, our study suggests that auto-PBSCT is a very important therapeutic option that can significantly improve the prognosis in the patients with hematological and solid tumors, especially in the patients with AML and NHL.

Adolescent↗

PubMed2001

[Study on mutations in the connexin 26 gene among Chinese with nonsyndromic hearing loss].

OBJECTIVE: To study the relation between nonsyndromic hearing loss in Chinese and mutations in connexin 26 (Cx 26) gene and to explore the pathogenic mechanism. METHODS: One hundred and thirty-eight individuals from thirty-five pedigrees with nonsyndromic hearing loss, 99 children with sporadic nonsyndromic hearing loss and 100 normal adults as control were collected in present studies. The Cx 26 coding sequence was screened by single strand conformational polymorphism (SSCP) and analyzed by direct sequencing when SSCP shifts were observed. RESULTS: Five SSCP shifts in 2 pedigrees were observed. Homozygous deletion C at position 233-235 of Cx 26 cDNA, which resulted in frameshift mutation, was found in 2 pedigrees with nonsyndromic hearing loss. CONCLUSION: The hot-spot mutations of Cx 26 gene in Chinese with nonsyndromic hearing loss may be different from other ethnic groups. The 233-235 delC homozygous mutation of Cx 26 cDNA can result in autosomal recessive nonsyndromic hearing loss in Chinese population.

Adult↗

PubMed2000

Production of fertile transgenic wheat plants via tissue electroporation.

Electroporation has been used effectively to deliver DNA into the tissue of intact wheat immature embryos. Transformed plantlets have been recovered after electroporation using field strengths of 275 and 750 V/cm, 960-µF capacitor and 50 µg/ml of linear plasmid DNA, containing bar and uidA genes. The field strength of 750 V/cm proved to be more effective for DNA delivery (estimated by transient GUS expression) and for recovery of transformed plants (two transgenic plants were recovered with an efficiency of 0.4%). After application of a field strength of 275 V/cm there was no visual evidence of transient GUS expression, but one transgenic plant was recovered with an efficiency of 0.2%, based on the number of electroporated embryos. This indicates that the amount of DNA delivered into the cells was too low for visual identification of transient GUS expression and that GUS expression may not provide an appropriate assessment of the efficiency of DNA delivery. Southern blot hybridisation has revealed a low copy number of transgene integration with some rearrangements in integrated loci. None of the transgenic plants has shown any visual GUS expression, although we could amplify the transcript of the uidA gene in T(0) progeny using RT-PCR. This may indicate that suppression of uidA expression occurred at the post-transcriptional level. The efficiency of tissue electroporation is still dependent on the quality of the plant material which is used but the transformation events were reproducible from one group of experiments to another. At present, this technique is dependent on a combination of factors including pretreatments of the recipient tissue, quality of tissue culture and optimisation of electroporation conditions.

Journal Article↗

PubMed2000

Regulation of Ped gene expression by TAP protein.

The Ped (Preimplantation embryo development) gene regulates fast or slow cleavage of preimplantation mouse embryos and their subsequent survival. The protein product of the Ped gene is the major histocompatibility complex (MHC) class Ib protein Qa-2. MHC class I expression on the cell surface requires the assembly within the endoplasmic reticulum (ER) of an alpha heavy chain, a beta2 microglobulin light chain, and a small peptide. Small peptides are primarily produced in the cytosol by the ubiquitin-proteasome pathway and then are transported into the ER by the transporter associated with antigen processing (TAP) protein. However, some peptides can bind to MHC class I heavy chains in a TAP-independent manner. In this study, we assessed whether TAP protein regulates Qa-2 expression on the cell surface of preimplantation mouse embryos thereby influencing the PED phenotype of the embryos. We chose Tap 1 knockout mice and their control mice (B6.129) as our experimental system. We analyzed Qa-2 mRNA expression by RT-PCR, total Qa-2 protein expression by Western blotting, and cell surface Qa-2 protein expression by Immuno-PCR in preimplantation embryos of both Tap 1 knockout mice and control mice. Then we determined the PED phenotype of both Tap 1 knockout mouse embryos and control mouse embryos. The results showed that Qa-2 expression on the cell surface of preimplantation embryos is dependent on TAP protein, and that Qa-2 expression on the cell surface is required for expression of the fast PED phenotype.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2000

[An analysis of the clinical and laboratory data of 53 cases of non-Hodgkin's lymphoma].

OBJECTIVE: To analyse the influence of factors on the prognoses of non-Hodgkin's lymphoma (NHL) and the clinical usage of IgH and T cell receptor(TCR) gene rearrangement for NHL typing. METHODS: Immunological phenotyping was carried out by SABC, and IgH(FR2A, FR3A) and TCR(beta, gamma) detection by PCR. RESULTS: The age curve of NHL was increased parallel with the patient's age increasing, hazard ratio was increased 1.039n annually. The incidence of B cell NHL(B-NHL) was 66.7%, T cell NHL(T-NHL) was 31.1%, low grade NHL was 56%, middle and high grade NHL were 44%. The positivity of IgH and TCR gene rearrangement in NHL patients were 75% by PCR detection, T and B classification was same as phenotyping. The 3 and 5 years survival ratio: HD were 83.3% and 62.5%, stage I-II of NHL were 88.9% and 66.7%, stage III-IV of NHL were 39.9% and 33.3%, Low grade NHL were 65.1% and 48.8%, middle and high grade NHL were 47.6% and 39.6%. The survival time of APBSCT group was longer than that of the conventional therapy group. CONCLUSION: Age, T,B classification, grading and staging are the important factors which affect on NHL prognoses. APBCST can improve NHL prognoses, especially for those of stage III-IV patients. Molecular biological methods can help T/B classification when it couldn't be confirmed by phenotyping.

Adult↗

PubMed2000

[Inheritance of Qin - Han medicine by Shang Han Za Bing Lun and its development].

Generally recognized to be completed at the end of the Eastern Han dynasty. Shang Han Za Bing Lun is clearly seen to inherit and develop the medicine of Qin - Han period in the aspects of preventive conception.differentiation of 6 - Channel diagnosis, decoction - prescription based on differential diagnosis and miscellaneous internal diseases. The conclusion is based on an overall and profound analysis on authentic writing materials, thus provides a useful enlightenment to contemporary study on TCM.

China↗

PubMed2000

[Examinations of distortion product otoacoustic emission in hereditary progressive non-syndromic hearing loss].

OBJECTIVE: To evaluate the hearing function in patients with hereditary progressive non-syndromic hearing loss. METHODS: Distortion product otoacoustic emissions (DPOAE) and pure tone audiometry were carried out in 52 individuals from a family with non-syndromic hearing loss and 15 persons with normal hearing. RESULTS: 1. Sensorineural hearing loss (SNHL) was found in 34 individuals of the family. Among these individuals, DPOAE was totally absent in 15 cases (29 ears) with pure tone average > or = 40 dB and low amplitude or absent middle to high frequencies in 12 cases (23 ears) with high frequency hearing loss but pure tone average < or = 35 dB. 2. Among 21 individuals (42 ears) with normal audiograms, DPOAE presented lower amplitude or absent high and middle frequencies in 12 individuals. CONCLUSION: DPOAE can be used in identification of subclinical pathologic alterations in the cochlea. This would be of particular value in early diagnosis and genetic consultation.

Audiometry, Pure-Tone↗