Biomedical subjects

Y Shen

Publications and source records attributed to Y Shen.

At least 37 records · Page 2Linked to original sources

PubMed2005

Linkage analysis of chromosome 1 with essential hypertension and blood pressure quantitative traits in Chinese families.

Summary Several recent studies have linked human chromosome 1p to essential hypertension (EH) or blood pressure (BP) levels. In an independent population of 148 hypertensive families from China we tested these findings. Thirty highly informative microsatellite markers spanning about 284 cM were genotyped. Qualitative linkage analysis was conducted using non-parametric linkage analysis implemented within the GENEHUNTER 2.0 software, whereas quantitative analysis was performed with the variance-component method integrated in the S.O.L.A.R. 1.7.4. software with an additional Haseman-Elston method using the SAGE/SIBPAL2 program. We observed suggestive linkage between D1S2890 (1p31, 80.9 cM) and hypertension using the multipoint non-parametric linkage analysis (NPL = 2.19, P = 0.01). In the quantitative analysis we didn't observe a significant excess of identity-by-descent allele sharing between the systolic blood pressure levels and the markers. However, the D1S207 microsatellite marker (1p21) which is located about 107 cM from the telomere of 1p showed weak linkage evidence with the diastolic blood pressure levels (LOD = 1.42). These findings suggest linkage of 1p31 with essential hypertension in the ethnic Chinese, and provide a potential clue for future studies involving candidate genes for hypertension.

Adult↗

PubMed2005

Radiation-induced changes in gene expression in the silkworm revealed by serial analysis of gene expression (SAGE).

Serial analysis of gene expression (SAGE) was used to examine the profile of expressed genes during embryonic development in the domesticated silkworm, Bombyx mori, after irradiation with Cobalt-60. A comparison of the SAGE sequence tags derived from irradiated embryos with those from normal embryos revealed 673 differentially expressed genes (P < 0.01 and at least three folds change). Of these, 292 genes were highly expressed in normal embryos and 381 genes were highly expressed in irradiated embryos. These results provide valuable information for understanding the mechanisms of radiation-induced changes in gene expression. In addition, it was noted that the generation of longer cDNA fragments from SAGE tags is an efficient way to identify genes, thereby facilitating the analysis of large numbers of unknown genes.

Animals↗

PubMed2005

Defects in ProTaper S1 instruments after clinical use: longitudinal examination.

AIM: To evaluate defects in ProTaper shaping instrument S1 after a defined schedule of clinical use. METHODOLOGY: Among all ProTaper files discarded from an endodontic clinic at a stomatological school in China over a period of 17 months, 122 S1 instruments were collected. They were ultrasonically cleaned, autoclaved and then examined in the laboratory. Any instrument separation was noted; the average length involved was determined. The 0.5 mm region on either side of this length of discarded but intact instruments was examined circumferentially by scanning electron microscope. The region adjacent to the broken end of the fractured instruments was also examined in the same way. RESULTS: One specimen was lost during processing. Of the remaining 121 instruments, 27 were separated with a mean fracture length of 3.67 mm from the tip. Of these, two files showed macroscopically torsional fracture and the others showed signs of flexural fatigue. Only one file that had not fractured showed visible unwinding defects. Examination of the 3.1-4.1 mm region of other unfractured instruments revealed the presence of microcracks, surface debris, pitting and/or wear of their cutting edges. Some debris particles seemed to have been trapped in crack-like structures. CONCLUSIONS: Multiple use of ProTaper S1 pre-disposed the instrument to microcrack formation and wear of the cutting edges. There was a low prevalence of plastic deformation and most ProTaper S1 instruments failed without discernible sign of unwinding of the flutes. Further studies should address the mode of failure and the role of debris particles in the fracture mechanism.

Dental Alloys↗

PubMed2005

Defects in ProTaper S1 instruments after clinical use: fractographic examination.

AIM: To investigate the mode of failure of a brand of nickel-titanium instruments separated during clinical use, by detailed examination of the fracture surface. METHODOLOGY: A total of 122 ProTaper S1 instruments were discarded from an endodontic clinic at a stomatological school in China over a period of 17 months; 28 had fractured. These fractured instruments were ultrasonically cleaned, autoclaved and then examined under a scanning electron microscope. From the lateral view the fracture was classified into 'torsional' or 'flexural'. The specimens were then re-mounted and the presence of characteristics of shear failure and fatigue striations was recorded under high-power view of the fracture surface. The difference in the mean lengths of fractured segment between the shear and fatigue groups was compared using Student's t-test. RESULTS: Twenty-seven separated instruments were available for analysis. Under low-power magnification, only two fell into the category of 'torsional' failure when examined laterally; the others appeared to be 'flexural'. Close examination of the fracture surface revealed the presence of fatigue striations in 18 specimens. Nine instruments (including the two putative 'torsional' failures above) fell into the shear fracture group, in which fatigue striations were absent or characteristics of shear failure of the material were found. The mean length of fractured segments resulting from fatigue failure (4.3+/-1.9 mm) was significantly greater than that for shear failure (2.5+/-0.8 mm) (P<0.001, two-sample t-test). CONCLUSIONS: Examination of the fracture surface at high magnification is essential to reveal features that may indicate the possible origin of cracks and the mode of material failure. Macroscopic or lateral examination of separated instruments would fail to reveal the true mechanism of failure. Fatigue seems to be an important reason for the separation of rotary instruments during clinical use.

Dental Alloys↗

PubMed2005

HLA-DPA1 promoter haplotypes are differently distributed in southern Chinese ethnic groups.

DPA1 gene is one of the human leukocyte antigen (HLA) class II genes and its promoter is highly polymorphic. From comparative studies among five southern Chinese populations, Jing, Li, Bai, Lahu, and Meizhou Han, we describe their single-nucleotide polymorphism (SNP)/haplotype frequency data of HLA-DPA1 gene promoter in this study. Within the 760-bp promoter region, we have identified 21 SNPs and nine possible haplotypes. Pair-wise comparisons show similar frequencies distribution of the HLA-DPA1 promoter haplotypes among Jing, Li, and Bai, whereas all pair-wise comparisons involved with Lahu or Meizhou Han and other ethnic groups show remarkable difference. The differences in frequencies of HLA-DPA1 promoter alleles may reveal different ethnic origins and demographic histories of the five populations. Our study may help distinguishing each of these populations by sequence variations of HLA-DPA1 promoter, which may be served as functional molecular markers for clinical and immunological studies involving the DPA1 locus.

Alleles↗

PubMed2005

Influence of motility and vitality in intracytoplasmic sperm injection with ejaculated and testicular sperm.

The vitality of spermatozoa used for intracytoplasmic sperm injection (ICSI) is a crucial factor for fertilization, establishment and outcome of a pregnancy in assisted reproductive technique cycles. The sperm origin may also be a limiting factor, although little is known about this issue. It is known that the motility of injected spermatozoa and their origin from ejaculate or testicular biopsies are important predictors in terms of fertilization, pregnancy and birth rates. Oocytes of patients in 2593 cycles were retrieved in our in vitro fertilization programme and inseminated via ICSI. We used motile (group 1, n = 2317) or immotile ejaculated spermatozoa (group 2, n = 79), motile sperm retrieved from testicular biopsies (group 3, n = 62) and immotile spermatozoa from testicular biopsies (group 4, n = 135). Female age and number of oocytes retrieved did not differ significantly among the groups. The fertilization rates were as follows: 67.1% in group 1, 49.8% in group 2, 68.3% in group 3 and 47.8% in group 4. The pregnancy rates in cases where three embryos had been transferred amounted to 35.7% in group 1, 17.3% in group 2, 38.3% in group 3 and 20.5% in group 4. The embryo quality showed no differences between groups 1 and 3 (14.5), and between groups 2 (11.8) and 4 (10.8). The abortion rate was similar in groups 1-3, but increased in group 4 (26.6%, 27.3%, 31.6% and 55.5%). Irrespective of their origin, the fertilization potential of injected spermatozoa was found to be influenced by motility. The resulting pregnancy and birth rates, i.e. the potential of the resulting embryos to implant and to achieve viable pregnancies, seem to be additionally dependent on the sperm origin. This was well shown by declining rates when spermatozoa in a relatively early stage of maturity had been used. We see increasing evidence that the degree of sperm maturity has an important impact on the outcome of ICSI. In obstructive azoospermia, spermatozoa retrieved from the epididymis should be used rather than testicular biopsy spermatozoa, or testicular sperm should be preincubated in culture medium before ICSI.

Adult↗

PubMed2005

Gamma-S crystallin gene (CRYGS) mutation causes dominant progressive cortical cataract in humans.

BACKGROUND: Congenital or childhood cataract is clinically and genetically a highly heterogeneous lens disorder in children. Autosomal dominant inheritance is most common. OBJECTIVE: To report the identification of a mutation in the human CRYGS gene. SUBJECTS AND METHODS: A large six generation family affected by progressive polymorphic cortical cataract was investigated. After excluding loci for known cataract candidate genes using 39 fluorescent microsatellite markers, a whole genome scan was carried out. RESULTS: The disease was associated with inheritance of a 20.7 cM locus on chromosome 3q26.3-qter, with a maximum LOD score of 6.34 (theta = 0) at marker D3S1602. Haplotype analysis indicated that the disease gene lay at approximately 2.8 Mb physical intervals between D3S1571 and D3S3570 and contained CRYGS on 3q27.3. By sequencing the CRYGS gene, a distinct 1619G-->T (AC068631) heterozygous missense mutation in exon 2 was identified, co-segregating with the disease phenotype in this family and resulting in a glycine (GGC) to valine residue (GTC) substitution in codon 18 (NP_060011). CONCLUSIONS: This report is the first description of a mutation in CRYGS with autosomal dominant cataract in humans.

Amino Acid Sequence↗

PubMed2005

The growth hormone receptor gene is associated with mandibular height in a Chinese population.

Genetic influences are important in the determination of mandibular morphology, and growth hormone receptor (GHR) is believed to have an important influence on the growth of craniofacial bone. In this study, we used quantitative trait locus methods to evaluate the relationship between craniofacial morphology and single-nucleotide polymorphisms (SNPs) in GHR in an unselected healthy Chinese population. We systematically screened the 10 exons and nearby introns of GHR and identified 6 SNPs. Using 4 SNPs as markers, we studied the relationships between genotypes and craniofacial linear measurements. Individuals with the genotype CC of polymorphism I526L had a significantly greater mandibular ramus length (condylion-gonion/ articulare-gonion) than those with genotype AC or AA. Haplotype analysis showed that there were also significant differences between the long and short mandibular height groups in an extreme population. Our results indicate that the GHR gene polymorphism I526L is associated with mandibular height in the Chinese population.

Adenine↗

PubMed2005

Aclarubicin and low-dose Cytosine arabinoside in combination with granulocyte colony-stimulating factor in treating acute myeloid leukemia patients with relapsed or refractory disease and myelodysplastic syndrome: a multicenter study of 112 Chinese patients.

One hundred twelve patients with geriatric acute myeloid leukemia (AML), refractory or relapsed AML, or myelodysplastic syndrome and refractory anemia with excess of blasts in transformation (MDS-RAEBt) were entered into this study to receive CAG (aclarubicin and low-dose cytosine arabinoside [Ara-C]in combination with granulocyte colony-stimulating factor [G-CSF]) with the objective of evaluating the efficacy and tolerance of this regimen. Low-dose Ara-C was given subcutaneously at a dosage of 10 mg/m2 every 12 hours on days 1 to 14. Aclarubicin was administered intravenously at a dosage of 14 mg/m2 per day on days 1 to 4 (CAG regimen A) or 7 mg/m2 on days 1 to 8 (CAG regimen B). Recombinant G-CSF was given subcutaneously at a dosage of 200 3g/m2 per day on days 1 to 14. We demonstrated comparable overall complete remission rates for the 4 groups of patients: 30.8% (8/26) in the elderly patients, 48.4% (30/62) in the refractory AML patients, 44.4% (8/18) in the relapsed AML patients, and 38.5% (5/13) in the MDS-RAEBt patients. Of the 52 patients followed up, the 12-month progression-free survival (PFS) and overall survival (OS) rates estimated by the Kaplan-Meier method were 40.73% 3 8.15% and 42.85% 3 8.23%, respectively. The median PFS and OS times were 9.0 3 2.2 months and 11.0 3 1.6 months, respectively. Toxic effects were very rare and mainly consisted of neutropenia and thrombocytopenia due to myelosuppression; approximately 70% to 80% of patients had neutropenia or thrombocytopenia that exceeded National Cancer Institute grade II. Nonhematologic toxicities were not observed in this study. The CAG regimen seems promising, with acceptable toxicity, for the treatment of various categories of poor-prognosis AML and MDS-RAEBt.

Aclarubicin↗

PubMed2004

The CLDN5 locus may be involved in the vulnerability to schizophrenia.

The present study was designed to detect three single nucleotide polymorphisms (SNPs) located on 22q11 that was thought as being of particularly importance for genetic research into schizophrenia. We recruited a total of 176 Chinese family trios of Han descent, consisting of mothers, fathers and affected offspring with schizophrenia for the genetic analysis. The transmission disequilibrium test (TDT) showed that of three SNPs, rs10314 in the 3'-untranslated region of the CLDN5 locus was associated with schizophrenia (chi(2) = 4.75, P = 0.029). The other two SNPs, rs1548359 present in the CDC45L locus centromeric of rs10314 and rs739371 in the 5'-flanking region of the CLDN5 locus, did not show such an association. The global chi-square (chi(2)) test showed that the 3-SNP haplotype system was not associated with schizophrenia although the 1-df test for individual haplotypes showed that the rs1548359(C)-rs10314(G)-rs739371(C) haplotype was excessively non-transmitted (chi(2) = 5.32, P = 0.02). Because the claudin proteins are a major component for barrier-forming tight junctions that could play a crucial role in response to changing natural, physiological and pathological conditions, the CLDN5 association with schizophrenia may be an important clue leading to look into a meeting point of genetic and environmental factors.

Cell Cycle Proteins↗

PubMed2004

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) in a Chinese family: clinical, radiological and skin biopsy features.

We describe the clinical, radiological, genetic and skin biopsy findings of the first Chinese family with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). Of the 43-member family tree extending over three generations, eight had typical clinical features of CADASIL with recurrent ischemic stroke. In the three surviving affected family members, brain MRI showed extensive leukoaraiosis. Genotyping revealed heterozygous C to T mutation at nucleotide 406 in exon 3. Unusual clinical features were cerebellar infarction as a presenting complaint and a late age of onset with mild symptoms at age 69. A novel finding is the suggestion of a direct correlation between clinical disease severity and the quantity of ultrastructural pathognomonic granular osmophilic material (GOM) seen on skin biopsy.

Aged↗

PubMed2004

No association between the PTGS2/PLA2G4A locus and schizophrenia in a Chinese population.

The present study was undertaken to replicate an association between the PTGS2/PLA2G4A locus and schizophrenia among a Chinese population. We recruited 168 Chinese parent-offspring trios of Han descent, consisting of fathers, mothers and affected offspring with schizophrenia. Of 3 informative SNPs genotyped, no one showed allelic association with schizophrenia; the haplotype analysis also failed to capture a haplotypic association with the illness. Because the frequencies of alleles and genotypes of SNPs analyzed differ in the Chinese population as compared with a British population that initially showed the genetic association between the PTGS2/PLA2G4A locus and schizophrenia, the ethnic background may be a major reason for poor replication of the initial finding.

Asian People↗

PubMed2004

A dual frequency, ultrasonic, microengineered particle manipulator.

Ultrasonic standing waves can be used to generate forces on particles within a fluid. Recent work has concentrated on developing devices that manipulate the particles so that they are concentrated near the centre of the cavity. It is also possible to design a device that concentrates the particles at the wall of a cavity. This paper describes a device that has the capability of operating in several modes to allow concentration of particles at either the cavity wall or the centre of the cavity, depending on the driving frequency.

Journal Article↗

PubMed2004

Association study of an SNP combination pattern in the dopaminergic pathway in paranoid schizophrenia: a novel strategy for complex disorders.

Schizophrenia is a common mental disorder with a complex pattern of inheritance. Despite a large number of studies in the past decades, its molecular etiology remains unknown. In this study, we proposed a 'system-thinking' strategy in seeking the combined effect of susceptibility genes for a complex disorder by using paranoid schizophrenia as an example. We genotyped 85 reported single-nucleotide polymorphisms (SNPs) present in 23 genes for the dopamine (DA) metabolism pathway among 83 paranoid schizophrenics and 108 normal controls with detailed clinical and genetic information. We developed two novel multilocus approaches-the potential effective SNP combination pattern and potential effective dynamic effects analysis, by which three susceptibility genotype combinations were found to be associated with schizophrenia. These results were also validated in a family-based cohort consisting of 95 family trios of paranoid schizophrenia. The present findings suggest that the COMT and ALDH3 combination may be the most common type involved in predisposing to schizophrenia. Since the combination blocks the whole pathways for the breakdown of DA and noradrenaline, it is very likely to play a central role in developing paranoid schizophrenia.

Adolescent↗

PubMed2004

Value of CSF beta-amyloid1-42 and tau as predictors of Alzheimer's disease in patients with mild cognitive impairment.

Subjects with mild cognitive impairment (MCI) are at a high risk of developing clinical Alzheimer's disease (AD). We asked to what extent the core biomarker candidates cerebro-spinal fluid (CSF) beta-amyloid(1-42) (Abeta(1-42)) and CSF tau protein concentrations predict conversion from MCI to AD. We studied 52 patients with MCI, 93 AD patients, and 10 healthy controls (HC). The MCI group was composed of 29 patients who had converted to AD during follow-up, and of 23 patients who showed no cognitive decline. CSF Abeta(1-42) and tau protein levels were assessed at baseline in all subjects, using enzyme-linked immunosorbent assays. For assessment of sensitivity and specificity, we used independently established reference values for CSF Abeta(1-42) and CSF tau. The levels of CSF tau were increased, whereas levels of Abeta(1-42) were decreased in MCI subjects. Abeta(1-42) predicted AD in converted MCI with a sensitivity of 59% and a specificity of 100% compared to HC. Tau yielded a greater sensitivity of 83% and a specificity of 90%. In a multiple Cox regression analysis within the MCI group, low baseline levels of Abeta(1-42), but not other predictor variables (tau protein, gender, age, apolipoprotein E epsilon4 carrier status, Mini Mental Status Examination score, observation time, antidementia therapy), correlated with conversion status (P<0.05). Our findings support the notion that CSF tau and Abeta(1-42) may be useful biomarkers in the early identification of AD in MCI subjects.

Aged↗

PubMed2004

Subunit interaction and regulation of activity through terminal domains of the family D DNA polymerase from Pyrococcus horikoshii.

Family D DNA polymerase (PolD) has recently been found in the Euryarchaeota subdomain of Archaea. Its genes are adjacent to several other genes related to DNA replication, repair and recombination in the genome, suggesting that this enzyme may be the major DNA replicase in Euryarchaeota. We successfully cloned, expressed, and purified the family D DNA polymerase from Pyrococcus horikoshii (PolDPho). By site-directed mutagenesis, we identified amino acid residues Asp-1122 and Asp-1124 of a large subunit as the essential residues responsible for DNA-polymerizing activity. We analysed the domain structure using proteins truncated at the N- and C-termini of both small and large subunits (DP1Pho and DP2Pho), and identified putative regions responsible for subunit interaction, oligomerization and regulation of the 3'-5' exonuclease activity in PolDPho. It was also found that the internal region of the putative zinc finger motif (cysteine cluster II) at the C-terminal of DP2Pho is involved in the 3'-5' exonuclease activity. Using gel filtration analysis, we determined the molecular masses of the recombinant PolDPho and the N-terminal putative dimerization domain of the large subunit, and proposed that PolD from P. horikoshii probably forms a heterotetrameric structure in solution. Based on these results, a model regarding the subunit interaction and regulation of activity of PolDPho is proposed.

Amino Acid Motifs↗

PubMed2004

Protothecosis successfully treated with amikacin combined with tetracyclines.

Summary We report a case of protothecosis in an 18-year-old female student caused by Prototheca zopfii successfully treated with amikacin combined with tetracyclines. Zusammenfassung Es wird über eine Protothecose, verursacht durch Prototheca zopfii, bei einer 18-jährigen Studentin berichtet, die erfolgreich mit Amikacin in Kombination mit Tetracyclinen behandelt wurde.

Adolescent↗

PubMed2004

Mutations in SCN9A, encoding a sodium channel alpha subunit, in patients with primary erythermalgia.

Primary erythermalgia is a rare autosomal dominant disease characterised by intermittent burning pain with redness and heat in the extremities. A previous study established the linkage of primary erythermalgia to a 7.94 cM interval on chromosome 2q, but the causative gene was not identified. We performed linkage analysis in a Chinese family with primary erythermalgia, and screened the mutations in the two candidate genes, SCN9A and GCA, in the family and a sporadic patient. Linkage analysis yielded a maximum lod score of 2.11 for both markers D2S2370 and D2S2330. Based on critical recombination events in two patients in the family, we further limited the genetic region to 5.98 cM between D2S2370 and D2S2345. We then identified two missense mutations in SCN9A in the family (T2573A) and the sporadic patient (T2543C). Our data suggest that mutations in SCN9A cause primary erythermalgia. SCN9A, encoding a voltage-gated sodium channel alpha subunit predominantly expressed in sensory and sympathetic neurones, may play an important role in nociception and vasomotor regulation.

Base Sequence↗