Biomedical subjects

Sizhong Zhang

Publications and source records attributed to Sizhong Zhang.

At least 19 recordsLinked to original sources

PubMed2006

Preliminary study of the relationship between DAZ gene copy deletions and spermatogenic impairment in Chinese men.

Copy deletion screening of DAZ gene family on the Y chromosome in 485 patients with idiopathic azoospermia or oligozoospermia and 236 fertile men revealed that the prevalence of deletion patterns of the entire DAZ gene and DAZ1/DAZ2 gene were significantly higher in the patients than in fertile men. The deletion patterns correlate with spermatogenic impairment in a Chinese population.

Adult↗

PubMed2006

Microvascular density and vascular endothelial growth factor have little correlation with prognosis of craniopharyngioma.

BACKGROUND: Craniopharyngioma is histologically a benign epithelial tumor located in the supersellar cistern that often presents aggressive growth and repeated recurrence. The authors hypothesized that craniopharyngioma recurrence and invasive growth are angiogenesis dependent and evaluated the significance of vascularization in the prognosis of craniopharyngioma by a prospective cohort study. METHODS: The cohorts consisted of 32 patients with AE and 31 patients with SP tumor. The primary and recurrence removal specimens of the cohort patients were gathered. Microvascular density and VEGF protein in the recurrence group and recurrence-free group were detected by the immunohistochemistry avidin-biotin-peroxidase method and analyzed quantitatively through computer-assisted microscopy to evaluate the correlation of MVD and VEGF with prognosis of craniopharyngiomas. RESULTS: The average follow-up phase was 63.34 months; 14 of 32 patients with AE and 6 of 31 patients with SP had recurrence and underwent operation again. Although MVD and VEGF have significant difference between AE and SP (P=.000, P=.018, respectively), MVD and VEGF have no statistical difference between the recurrence group and recurrence-free group (P>.05). CONCLUSIONS: Microvascular density and VEGF in craniopharyngioma tissue have no correlation with prognosis of the tumor, which may be explained by the minimal blood circulation in the craniopharyngioma. Adamantine epithelioma showed more tendency to recur than SP.

Craniopharyngioma↗

PubMed2005

Single nucleotide polymorphisms of the gonadotrophin-regulated testicular helicase (GRTH) gene may be associated with the human spermatogenesis impairment.

BACKGROUND: Gonadotropin-regulated testicular RNA helicase (GRTH) is a testis-specific RNA helicase that is essential for completion of spermatogenesis and is involved in pathogenesis of impaired spermatogenesis in mouse. It is therefore reasonable to postulate that human GRTH gene may also play a role in impaired spermatogenesis in humans. To test this hypothesis, we investigated the possible association between the variations of the GRTH gene and human spermatogenesis impairment. METHODS: Mutation screening of exons and intron/exon boundaries of GRTH gene was carried out by denaturing high-performance liquid chromatography (DHPLC) in 347 infertile patients with idiopathic azoospermia and severe oligozoospermia as well as 201 fertile men. RESULTS: Four single nucleotide polymorphisms (SNP), namely IVS6+55G-->T, ISV8+10A-->C, c.852C-->T and c.927G-->A, were identified. Among them, significant differences in polymorphism frequencies were observed at the polymorphic IVS6+55G-->T and c.852C-->T loci between the patients and controls, and a significant association between haplotypes of these two loci and male infertility with impaired spermatogenesis was detected. CONCLUSIONS: Results of the present study indicate that SNP IVS6+55G-->T and c.852C-->T of GRTH gene may be associated with male infertility with azoospermia or severe oligozoospermia, suggesting that variations in GRTH gene may contribute to susceptibility to spermatogenic impairment in humans.

Base Sequence↗

PubMed2005

The common variant N372H in BRCA2 gene may be associated with idiopathic male infertility with azoospermia or severe oligozoospermia.

OBJECTIVE: To explore the possible association between the common single nucleotide polymorphism N372H in human breast cancer susceptibility gene 2 (BRCA2) and the idiopathic male infertility with azoospermia or severe oligozoospermia. STUDY DESIGN: The study included 240 infertile patients with idiopathic azoospermia or severe oligozoospermia and 250 fathered controls. The allele and genotype frequencies of the polymorphism N372H in BRCA2 gene were investigated in both patients and controls using denaturing high performance liquid chromatography analysis (DHPLC). RESULTS: The frequency of allele H of the polymorphism N372H in patients was significantly higher than that of the controls (23.5% versus 17.6%, OR = 1.49, 95% CI 1.06-1.97, P = 0.02) and the subjects bearing rare allele H (NH + HH) significantly increased in patients compared with controls (41.7% versus 32.4%, 95% CI 1.03-2.15, P = 0.03). CONCLUSION: The results of this study suggested that the polymorphism N372H in BRCA2 gene may be associated with idiopathic male infertility with azoospermia or severe oligozoospermia.

Chromatography, High Pressure Liquid↗

PubMed2005

Carriers of three polymorphisms of cholesteryl ester transfer protein gene are at increased risk to coronary heart disease in a Chinese population.

BACKGROUND: The cholesteryl ester transfer protein (CETP) is a key participant in the reverse transport of cholesterol from the peripheral tissue to the liver and the polymorphism in the CETP gene may therefore alter the susceptibility to coronary heart disease (CHD). The aim of the present study was to screen the CETP gene for new single nucleotide polymorphisms (SNPs) and to determine whether SNPs at important cholesterol metabolism gene loci might exert effects on the risk to CHD in Chinese. METHODS: Genomic DNA samples were collected from 203 Chinese patients with CHD and 209 age- and gender-matched controls. The coding region, adjacent intronic sequences and promoter region (totally 5501 bp) of the CETP gene were screened based on a combination of polymerase chain reaction, denaturing high performance liquid chromatography and DNA sequencing. The association of individual single nucleotide polymorphisms with CHD was assessed by univariate, multivariate analysis and haplotype analysis. RESULTS: Fifteen SNPs were identified in the CETP gene including 12 novel ones, of which, 3 were in promoter region, 1 in exon 10, and other 9 in introns. The frequencies of -644C, +13054T, 296Q, and 442G alleles were considerably higher, while the frequency of +9907A allele lower, in CHD patients than those in controls (p=0.016, p=0.043, p=0.006, p=0.006, and p=0.029, respectively). The results of individual polymorphism analyses were confirmed by haplotype analysis for the combination of these 5 SNPs. The -644A/C, L296Q, and D442G polymorphisms were found to be associated with CHD in this Chinese population by multivariate analysis (p=0.009, p=0.024, and p=0.007, respectively). The adjusted odds ratio for the development of CHD for the -644C allele carriers was 1.63 compared with -644AA genotype (95% CI 1.05-2.78; p<0.01), 1.71 for the 296Q allele carriers relative to 296LL genotype (95% CI 1.10-2.89; p<0.05), and 1.31 for the 442G allele carriers relative to 442DD genotype (95% CI 1.02-2.56; p<0.01), respectively. CONCLUSIONS: There is a significant relation between the polymorphisms in the CETP gene and the development of CHD, and individuals homozygous or heterozygous for the -644C, 296Q, and 442G alleles of the CETP gene are at increased risk to develop CHD in this Chinese population.

Asian People↗

PubMed2005

The APOC3 SstI polymorphism is weakly associated with sporadic Alzheimer's disease in a Chinese population.

In order to clarify the relationship of apolipoprotein CIII (APOC3) polymorphism and sporadic Alzheimer's disease (AD) in Chinese, 165 sporadic AD patients and 174 age-matched elderly individuals were genotyped for the APOC3 SstI and apolipoprotein E (APOE) HhaI polymorphisms. As the result, the APOC3 3017G allele was found to be associated with AD in APOE epsilon4 allele noncarriers (chi2=4.433, P=0.035), and the risk estimate of allele C versus G resulted in an OR of 1.56 (95% CI: 1.03-2.37), although in total no significant differences of allelic or genotypic frequencies between patients and controls were found. Assessment of interaction between APOE epsilon4 and APOC3 3017G status presented an adjusted odds ratio of 0.62 (95% CI: 0.37-1.03) with a borderline significant P-value (P=0.066). Therefore, we conclude that the rare APOC3 G allele may offer some protection against the development of sporadic AD in APOE epsilon4 noncarriers in Chinese.

Aged↗

PubMed2005

Association between DNA variant sites in the apolipoprotein A5 gene and coronary heart disease in Chinese.

The recently discovered apolipoprotein A5 ( APOA5 ) gene has been shown to be important in determining plasma triglyceride levels, a major cardiovascular disease risk factor. We searched for possible associations of the APOA5 gene polymorphisms S19W and -1131T>C with coronary heart disease (CHD) in a Chinese population. A total of 483 Chinese CHD patients and 502 control non-CHD subjects were genotyped by polymerase chain reaction-restriction fragment length polymorphism for these 2 single nucleotide polymorphisms. We found that the minor allele 19W was observed only in CHD patients and not in controls, with allelic frequencies of 0.047 and 0.000, respectively ( P < .000001), and the minor allele -1131C was significantly higher in CHD patients than in controls (0.391 vs 0.299, P < .0001). These results suggest that both the S19W and -1131T>C variations in the APOA5 gene are associated with the CHD and appear to be 2 genetic risk factors for CHD susceptibility in Chinese. Moreover, we found that triglyceride levels were significantly higher in -1131C carriers than in -1131T subjects of the control group and that high-density-lipoprotein cholesterol was decreased in -1131C carriers among CHD patients.

Apolipoprotein A-V↗

PubMed2005

Mutation screening and association study of the neprilysin gene in sporadic Alzheimer's disease in Chinese persons.

Neprilysin has been reported to be a major beta-amyloid peptide (Abeta)-degrading enzyme. The decreased expression and activity of it may contribute to the development of Alzheimer's disease by promoting the accumulation of Abeta. We used denaturing high-performance liquid chromatography to screen the neprilysin gene (NEP) for single nucleotide polymorphisms (SNPs) in 257 Chinese sporadic Alzheimer's disease patients and 242 cognitive normal controls. As a result, eight novel and one known SNP were identified. Three of them, -204G-->C in the promoter region, IVS17-294C-->T, and IVS22+36C-->A showed a significant association with Alzheimer's disease (p = .006,.017, and.003, respectively). Subsequent haplotype analysis provided further evidence of the association (global p < .0001 for the three SNPs mentioned above, and global p < .01 for the eight SNPs with rare allele frequency > 1%). These findings indicate that genetic variations within or extremely close to NEP might influence the susceptibility to Alzheimer's disease in Chinese persons.

Aged↗

PubMed2005

Distinct transcriptional regulation and function of the human BACE2 and BACE1 genes.

Amyloid beta protein (Abeta) is the principal component of neuritic plaques in Alzheimer's disease (AD). Abeta is derived from beta amyloid precursor protein (APP) by beta- and gamma-secretases. Beta-site APP cleaving enzyme 1 (BACE1) has been identified as the major beta-secretase. BACE2 is the homolog of BACE1. The BACE2 gene is on chromosome 21 and has been implicated in the pathogenesis of AD. However, the function of BACE2 in Abeta generation is controversial. Some studies have shown that BACE2 cleaved APP at the beta-site whereas other studies showed it cleaved around the alpha-secretase site. To elucidate the involvement of BACE2 in AD pathogenesis, we compared BACE2 and BACE1 gene regulation and their functions in Abeta generation. We cloned and functionally characterized the human BACE2 promoter. The BACE2 gene is controlled by a TATA-less promoter. Though Sp1 can regulate both BACE1 and BACE2 genes, comparative sequence analysis and transcription factor prediction showed little similarity between the two promoters. BACE1 increased APP cleavage at the beta-site and Abeta production whereas BACE2 did not. Overexpression of BACE2 significantly increased sAPP levels in conditioned media but markedly reduced Abeta production. Knockdown of BACE2 resulted in increased APP C83. Our data indicate that despite being homologous in amino acid sequence, BACE2 and BACE1 have distinct functions and transcriptional regulation. BACE2 is not a beta-secretase, but processes APP within the Abeta domain at a site downstream of the alpha-secretase cleavage site. Our data argue against BACE2 being involved in the formation of neuritic plaques in AD.

Alzheimer Disease↗

PubMed2005

[No evidence for genetic association between alpha-2 macroglobulin I1000V polymorphism and sporadic Alzheimer's disease in two independent Chinese populations].

OBJECTIVE: Alpha-2 macroglobulin (alpha2M) is a proteinase inhibitor found in association with senile plaques in Alzheimer's disease (AD). Also alpha2M has been implicated in several pathophysiological processes in AD. In view of the recent contradictory reports on the relationship between AD and a common polymorphism I1000V in A2M gene, the present authors studied a relatively large sample, determined the genotype of the I1000V polymorphism in A2M gene in sporadic AD patients and age-matched controls with normal cognition, and examined the possible association of the polymorphism with AD. METHODS: Genotypes of A2M and apolipoprotein E (apoE) were detected by polymerase chain reaction combined with restriction fragment length polymorphism in 257 patients and 242 controls in Guangzhou, and 112 patients and 113 controls in Chengdu. RESULTS: The 1000Val allele frequencies in the merged AD and control groups were 7.7% and 8.7%, respectively. The differences of allelic and genotypic frequencies between the patients and control subjects were not statistically significant, even after stratification by apoE epsilon4 status or by age-of-onset of the disease. CONCLUSION: The results of this study revealed no association between the I1000V polymorphism of A2M and Chinese sporadic AD in Guangzhou and Chengdu.

Aged↗

PubMed2004

Novel P143L polymorphism of the LCAT gene is associated with dyslipidemia in Chinese patients who have coronary atherosclerotic heart disease.

Coronary atherosclerotic heart disease (CAD) is a multifactorial disorder resulting from numerous gene-gene and gene-environment interactions. Lecithin:cholesterol acyltransferase (LCAT), a key enzyme in reverse cholesterol transport and the metabolism of high-density lipoprotein (HDL), is thought to be a candidate gene related to dyslipidemia and CAD. Variations in the LCAT gene were investigated in 190 CAD patients and 209 age- and gender-matched controls by denaturing high-performance liquid chromatography, and confirmed by sequencing and RFLP assay. In CAD patients, a novel single-nucleotide polymorphism (P143L) in exon 4 of the LCAT gene was discovered in nine males and two females (frequency of 5.79%), which was found in none of 209 controls. The genotype and allele distribution of P143L is significantly (P<0.04 ) higher in the low HDL-C subgroup than in the normal HDL-C subgroup in both male patients and all CAD patients. P143L was also found to be significantly (P<0.01) associated with the low HDL-C phenotype in both male patients and all CAD patients, with odds-ratios of 7.003 (95% CI 2.243-21.859) and 5.754 (95% CI 1.893-13.785), respectively. Thus, the P143L polymorphism may play a role in causing decreased HDL-C levels, leading to increased risk of dyslipidemia and CAD in Chinese.

Aged↗

PubMed2004

Possible association between Cys311Ser polymorphism of paraoxonase 2 gene and late-onset Alzheimer's disease in Chinese.

The common polymorphism at codon 311 (C311S) of paraoxonase 2 gene (PON2) was investigated in 165 patients with sporadic late-onset Alzheimer's disease (LOAD) and 174 controls in Chinese. The PON2*C allele frequency was significantly increased in the patients as compared with controls. However, no significant difference was observed after stratification of apolipoprotein E (ApoE) epsilon4 allele. These results suggested that the PON2 polymorphism might be a risk factor for LOAD independent of ApoE epsilon4 status in Chinese.

Aged↗

PubMed2004

The 1239G/C polymorphism in exon 5 of BACE1 gene may be associated with sporadic Alzheimer's disease in Chinese Hans.

Beta-site amyloid-precursor protein cleaving enzyme (BACE1) is a candidate risk factor for Alzheimer's disease (AD) because of involving in generating beta-amyloid peptide, which is thought to play a central role in the pathogenesis of the disease. A single nucleotide polymorphism 1239G/C in exon 5 of BACE1 gene and a weak association between this polymorphism and AD in Caucasian APOEepsilon4 allele carriers has been reported. To examine possible association of the polymorphism with sporadic AD, two Chinese Han cohorts including 257 patients and 242 age-matched controls in Guangzhou and 112 patients and 113 controls in Chengdu were genotyped using PCR-RFLP techniques. The frequency of the C allele in controls of both cohorts was 0.65, which was higher than that in Caucasian populations [0.39 by Nowotny et al. 2001: Neuroport 12:1799-1802; 0.44 by Nicolaou et al. 2001: Neurogenetics 3:203-206]. There was a significant excess of C allele among the patients in both cohorts (Guangzhou, 0.71 vs. 0.65, chi(2) = 5.20, P = 0.02; Chengdu, 0.74 vs. 0.65, chi(2) = 4.36, P = 0.04). The CC genotype was found to be associated with AD (Guangzhou cohort, OR = 1.56, 95% CI = 1.09-2.23; Chengdu cohort, OR = 1.74, 95% CI = 1.03-2.95; combined sample: OR = 1.61, 95% CI = 1.20-2.17). The association remained in non-APOE epsilon4 allele carriers when all subjects were divided on the basis of the APOEepsilon4 status. Our findings suggest that the 1239G/C polymorphism in exon 5 of BACE1 gene may be associated with sporadic AD in Chinese Hans.

Age of Onset↗

PubMed2004

8302A/C and (TTA)n polymorphisms in the HMG-CoA reductase gene may be associated with some plasma lipid metabolic phenotypes in patients with coronary heart disease.

HMG-CoA reductase (HMGCR) is a rate-limiting enzyme that participates in cholesterol metabolism. Here we analyzed the 8302A/C and the (TTA)n polymorphisms in the HMGCR gene in 169 Chinese patients with coronary heart disease (CHD) and 161 age-matched controls. Results indicated that the levels of plasma VLDL and TG in patients with the AA genotype of the 8302A/C locus were significantly higher than in patients with other genotypes (P < 0.05). In addition, the frequency of allele A4 of the (TTA)n locus was higher (P < 0.05) and the frequency of allele A5 was lower (P = 0.002) in CHD patients than in the controls. This suggests that both polymorphisms in the HMGCR gene may be associated with lipid and lipoprotein abnormalities in CHD in the Chinese.

Asian People↗

PubMed2004

[Idiopathic male infertility and partial copy deletion of DAZ gene family].

OBJECTIVE: To analyze the pattern and prevalence of partial copy deletion of deleted-in-azoospermia (DAZ) gene in the azoospermia factor C(AZFc) region of patients with idiopathic azoospermia or severe oligozoospermia. METHODS: sY581 and sY587 in DAZ gene region were analyzed by polymerase chain reaction-restriction length polymorphism(PCR-RFLP) for its deletion in 197 patients with azoospermia, 166 patients with severe oligozoospermia, and 210 fertile men as controls. RESULTS: Deletion of both DAZ1 and DAZ2 was detected in 18 patients with azoospermia and 10 with severe oligozoospermia, and the prevalence was 9.1% and 6.0% respectively. There was significant difference in deletion rate between the cases and controls. CONCLUSION: The frequency of partial copy deletion of DAZ gene in Chinese idiopathic azoospermia or severe oligozoospermia patients is much higher than that of fertile controls, suggesting that the deletion of DAZ1/DAZ2 may be one of the important genetic etiological factors of spermatogenesis damage. The pattern and prevalence of DAZ partial copy deletion are similar to those of Caucasians populations, and detection of DAZ gene partial copy deletion by PCR-RFLP may be adopted as an additional clinical gene diagnostic measure after AZF microdeletion detection.

Azoospermia↗

PubMed2003

Molecular cloning and characterization of a mouse spermatogenesis-related ring finger gene znf230.

Complete cDNA of mouse gene znf230 was cloned by rapid amplification of cDNA ends (RACE). This cDNA is 982 base pairs (bp) in length and encodes a 230 amino acids (aa) protein with a ring finger domain at its C-terminus. Ninety-one and 98% nucleotide (nt) and aa sequence identity are observed with its human homolog. Revealed by Northern blot and reverse transcriptase-polymerase chain reaction (RT-PCR), this cDNA is only detected in testicular tissue, whereas the longer transcripts of 2.4 and 4.4kb are ubiquitously expressed. The expression of znf230 in testis is developmentally regulated and first detected at day 6 postnatal (pn). It reaches adult level between day 14 and 21 pn during which round spermatids appear in seminiferous tubule. The protein of znf230 exhibits DNA binding activity and its ring finger domain may function as an activator module in transcription. Therefore, it is postulated that znf230 may function as a testis specific transcription factor during mouse spermatogenesis.

Amino Acid Sequence↗

PubMed2003

A single nucleotide deletion of 293delT in SEDL gene causing spondyloepiphyseal dysplasia tarda in a four-generation Chinese family.

Spondyloepiphyseal Dysplasia Tarda (SEDT; MIM 313400) is a rare genetically heterogeneous disorder of vertebral and epiphyseal growth resulting in disproportionally short-trunked short stature, barrel-shaped chest, and dysplasia of the large joints. It is caused by the mutations of SEDL gene. The distinctive radiological signs and the X-linked mode of inheritance make it easy to diagnose. Here a four-generation Chinese SEDT family has been analyzed and the disease-causing mutation has been found. After polymerase chain reaction (PCR)-single strand conformation polymorphism (SSCP) analysis and DNA sequencing, a previously unreported deletion of T in exon 5 of SEDL gene (i.e. 293delT) was observed and seven individuals in the family carried the mutation. It results in frameshift and a putative truncated protein with the 97 N-terminal amino acids, and 9 changed amino acids. Therefore, loss of function of the gene could be predicted. However, this mutation has not been detected in 50 age and sex matched unrelated controls.

Adult↗

PubMed2003

[Study on the association of lecithin cholesterol acyltransferase gene polymorphisms with the lipid metabolism in coronary atherosclerotic heart disease].

OBJECTIVE: To examine the distribution of 3 polymorphisms of lecithin cholesterol acyltransferase gene in Chinese population and the association of these polymorphisms with lipid metabolism in patients with atherosclerotic heart disease (CHD). METHODS: Genotypes and frequencies of 3 sites were examined by PCR-restriction fragment length polymorphism technique in 209 unrelated normal control individuals and 203 CHD patients. RESULTS: The observed allele frequencies conform well to Hardy-Weinberg equilibrium. The frequency of 608T allele was significantly higher in controls than that in patients (P=0.034). Compared with the CHD patients without 608T, the CHD patients with 608T exhibited a significant increase in plasma HDL-C concentration (P=0.015). 911T/C and 1188C/T polymorphisms were not found in either group. CONCLUSION: 608T polymorphism of LCAT gene was associated with higher plasma HDL-C level in CHD patients, while 911T/C and 1188C/T polymorphisms maybe very rare in Chinese population.

Alleles↗