Biomedical subjects

Z Lan

Publications and source records attributed to Z Lan.

11 recordsLinked to original sources

PubMed2006

Prion protein gene (PRNP) polymorphisms in Xinjiang local sheep breeds in China.

Amino acid polymorphisms of the prion protein (PrP) gene (PRNP), particularly those occurring at codons 136, 154, and 171 have a significant influence on scrapie pathogenesis in many sheep breeds. We isolated blood samples from 222 sheep representing the eight main local sheep breeds in the Xinjiang Autonomous Region, the territory with the most abundant local sheep breeds in China, to identify the PRNP polymorphisms and to determine whether these breeds were at risk for developing scrapie. A new PRNP polymorphism encoding either glycine (G) or arginine (R) at codon 85 as well as eight previously reported polymorphisms at codons 101, 112, 127, 141, 146, 154, 171, and 189 in other sheep breeds were detected. Interestingly, the alanine (A)/V polymorphism at codon 136 was not observed in this study, all sheep being homozygous for A at this position. While the previously identified polymorphism of argine (R) or histidine (H) at codon 154 was detected, the H polymorphism was rare (2.25%). Four polymorphisms at codon 171 encoding glutamine (Q), R, H, or lysine (K) were detected. The predominant ARQ allele occurred at a high frequency of 77.48%, suggesting an increased risk of scrapie in Xinjiang Autonomous Region.

Alleles↗

PubMed2001

Pregnancy outcomes of patients who conceived within 1 year after chemotherapy for gestational trophoblastic tumor: a clinical report of 22 patients.

OBJECTIVE: The aim of this study was to explore the risk of pregnancy of patients who conceived within 1 year after successful chemotherapy for gestational trophoblastic tumor (GTT). METHODS: From 1966 to 1996, 22 patients who conceived within 1 year after chemotherapy were followed up and analyzed retrospectively. RESULTS: Among 22 patients, 9 had term deliveries and 1 had a premature birth, 6 had induced abortion at the patient's request, and 6 had therapeutic abortion because of various indications such as repeated hydatidiform mole (1 case), intrauterine death (1 case), inevitable abortion (1 case), and threatened abortion (3 cases). The fetal loss rate was 27.1% (6/22). The incidence rate of gestational trophoblastic disease (GTD) was 9.1% (2/22). The incidence rate of GTT was 4.5% (1/22). The average interval between completion of chemotherapy and pregnancy was 10.25 months in the group of term pregnancies and 5.86 months in that of fetal loss (P < 0.05), indicating that the longer the interval, the lesser the risk of GTD. CONCLUSION: The results suggest that contraception for 1 year is necessary in patients with GTT after successful chemotherapy. However, in the case of a patient who conceives within 1 year, it is not necessary to terminate pregnancy, but the pregnancy must be carefully watched.

Adult↗

PubMed2001

A novel serotype-specific gene cassette (gltA-gltB) is required for expression of teichoic acid-associated surface antigens in Listeria monocytogenes of serotype 4b.

Listeria monocytogenes serotype 4b strains account for about 40% of sporadic cases and many epidemics of listeriosis. Mutations in a chromosomal locus resulted in loss of reactivity with all three monoclonal antibodies (MAbs) which were specific to serotype 4b and the closely related serotypes 4d and 4e. Here we show that this locus contains a serotype 4b-4d-4e-specific gene cassette (3,071 bp) which consists of two genes, gltA and gltB, and is flanked by palindromic sequences (51 and 44 nucleotides). Complete loss of reactivity with the three serotype-specific MAbs resulted from insertional inactivation of either gltA or gltB. The gltA and gltB mutants were characterized by loss and severe reduction, respectively, of glucose in the teichoic acid, whereas galactose, the other serotype-specific sugar substituent in the teichoic acid, was not affected. Within L. monocytogenes, only strains of serotypes 4b, 4d, and 4e harbored the gltA-gltB cassette, whereas coding sequences on either side of the cassette were conserved among all serotypes. Comparative genomic analysis of a serotype 1/2b strain showed that the 3,071-bp gltA-gltB cassette was replaced by a much shorter (528-bp) and unrelated region, flanked by inverted repeats similar to their counterparts in serotype 4b. These findings indicate that in the evolution of different serotypes of L. monocytogenes, this site in the genome has become occupied by serotype-specific sequences which, in the case of serotype 4b, are essential for expression of serotype-specific surface antigens and presence of glucose substituents in the teichoic acids in the cell wall.

Amino Acid Sequence↗

PubMed2000

p55CDC/hCDC20 is associated with BUBR1 and may be a downstream target of the spindle checkpoint kinase.

Eukaryotic cells have evolved a mechanism that delays the progression of mitosis until condensed chromosomes are properly positioned on the mitotic spindle. We have been studying genes that regulated the spindle checkpoint in human cells. Enforced expression of human BUBR1, but not a BUBR1 mutant allele, enhances accumulation of mitotic cells. Yeast two-hybrid system and GST-pulldown analyses show that p55CDC/hCdc20, a protein known to link spindle checkpoint components such as MAD2 to anaphase promoting complex (APC), interacts with BUBR1. In addition, p55CDC is capable of pulling down BUBR1 in sf-9 cells infected with both p55CDC and His6-BUBR1 recombinant baculoviruses but not in the cells infected with p55CDC baculoviruses or with the baculoviral vector alone. Moreover, immunoprecipitation followed by Western blot analyses confirmed that native p55CDC is associated with BUBR1 in HeLa cells. Spindle checkpoint activation by nocodazole treatment enhances the association between p55CDC and His6-BUBR1. In nocodazole-arrested mitotic cells, both CDC16 and hyperphosphorylated CDC27, two APC components, preferentially associate with His6-BUBR1 resins, but not the control resins. Furthermore, BUBR1 phosphorylates p55CDC in vitro, and the phosphorylation of p55CDC by BUBR1 appears to be correlated with spindle checkpoint activation. Together, our studies strongly suggest that BUBR1 may target APC via p55CDC.

Alleles↗

PubMed2000

Transforming activity of receptor tyrosine kinase tyro3 is mediated, at least in part, by the PI3 kinase-signaling pathway.

Protein tyrosine phosphorylation is an integral part of cytokine-induced proliferation and differentiation of hematopoietic cells. The authors previously reported cloning and characterization of the receptor tyrosine kinase Tif, also termed Tyro3. Using the yeast 2-hybrid technology, they recently identified that the p85 subunit of phosphatidylinositol 3-kinase (PI3 kinase) interacted with the cytoplasmic domain of Tyro3. On treatment with epidermal growth factor (EGF), NIH3T3 cells expressed EGFR/Tyro3 (a fusion receptor with the extracellular domain from epidermal growth factor receptor and the transmembrane and cytoplasmic domains from Tyro3), and EGFR/Tyro3 was rapidly phosphorylated on tyrosine residues. The interaction between Tyro3 and p85 was also confirmed by glutathione S-transferase (GST) pull-down experiments. Co-immunoprecipitation followed by Western blot analysis revealed that PI3 kinase was associated with and phosphorylated by the activated Tyro3. Tyro3-associated PI3 kinase exhibited an enhanced kinase activity. In addition, EGF treatment of EGFR/Tyro3-expressing cells led to enhanced phosphorylation of Akt, a downstream component of PI3 kinase. Treatment of NIH3T3 cells expressing a full length of rat Tyro-3, but not NIH3T3 cells, with protein S also resulted in phosphorylation of Akt. Soft agar colony assays showed that the addition of EGF to EGFR/Tyro3-transfected cells, but not to the parental NIH3T3 cells, resulted in a concentration-dependent increase in the formation of anchorage-independent colonies. Tyro3-mediated transformation of NIH3T3 cells was significantly blocked by wortmannin, a PI3 kinase-specific inhibitor. Results of these combined studies strongly suggested that the oncogenic transforming ability of Tyro3 was mediated at least in part by the PI3 kinase pathway. (Blood. 2000;95:633-638)

3T3 Cells↗

PubMed2000

A sheep in wolf's clothing: Listeria innocua strains with teichoic acid-associated surface antigens and genes characteristic of Listeria monocytogenes serogroup 4.

Listeria monocytogenes serotype 4b has been implicated in numerous food-borne epidemics and in a substantial fraction of sporadic listeriosis. A unique lineage of the nonpathogenic species Listeria innocua was found to express teichoic acid-associated surface antigens that were otherwise expressed only by L. monocytogenes of serotype 4b and the rare serotypes 4d and 4e. These L. innocua strains were also found to harbor sequences homologous to the gene gtcA, which has been shown to be essential for teichoic acid glycosylation in L. monocytogenes serotype 4b. Transposon mutagenesis and genetic studies revealed that the gtcA gene identified in this lineage of L. innocua was functional in serotype 4b-like glycosylation of the teichoic acids of these organisms. The genomic organization of the gtcA region was conserved between this lineage of L. innocua and L. monocytogenes serotype 4b. Our data are in agreement with the hypothesis that, in this lineage of L. innocua, gtcA was acquired by lateral transfer from L. monocytogenes serogroup 4. The high degree of nucleotide sequence conservation in the gtcA sequences suggests that such transfer was relatively recent. Transfer events of this type may alter the surface antigenic properties of L. innocua and may eventually lead to evolution of novel pathogenic lineages through additional acquisition of genes from virulent listeriae.

Amino Acid Sequence↗

PubMed2000

[Surgical treatment of patients with stage IV a liver carcinoma].

OBJECTIVE: To study the result of surgical treatment of patients with stage IV a primary liver carcinoma (PLC). METHODS: Twenty-seven patients with stage IV a PLC treated in 1989-1998 were retrospectively studied. The patients could be divided into 2 groups: (1) The resected group(19 cases) and (2) cytoreductive group(8 cases). Intra-operative B-ultrasound was used to prevent missing of any tumor nodules. Unresectable residual nodules were treated by ethanol injection. Multidisciplinary treatment was given in the perioperative period. RESULTS: The overall 1-, 2- and 3-year survival rate of the 27 patients was 71.4%, 55.6% and 7.7% respectively. The 1-, 2- and 3-year survival rate of the resected and cytoreductive group of patients was 73.3%, 58.3%, 10.0% and 66.7%, 50.0%, 0% (P > 0.05) respectively. Complications occurred in 22.0% of the treated patients. There was no operative and hospitalization mortality. CONCLUSIONS: Surgical resection or cytoreductive operation with adjuvant therapy is effective as the first choice of treatment for stage IV a PLC.

Adult↗

PubMed2000

Comparison the efficiency of different surgical procedures for urinary stress incontinence.

OBJECTIVE: To analyse the efficiency of two operations for treatment of urinary stress incontinence (USI). METHODS: The clinical data of 95 USI cases or accompany USI treated by surgical procedures (Kelly operation 63 cases, Colposuspension 32 cases) was analysed retrospectively in our department. RESULTS: The cure rates during three months after operation were 92.9% in Colposuspension group and 68.9% in Kelly operation group (P < 0.05), and decreased to 73.7% and 57.5% one year after operation in Colposuspension group and Kelly operation group respectively (P > 0.05). Abnormal senses rates of sexual intercourse was 3.7% in Colposuspension and 7.3% in Kelly operation group. The length of retaining Foley catheter after Colposuspension was more than Kelly operation. CONCLUSION: The cure rate during three months after Colposuspension is better than Kelly operation. But the cure rates during one year after surgery are the same in two groups.

Female↗

PubMed1999

BUBR1 phosphorylation is regulated during mitotic checkpoint activation.

Eukaryotic cells have evolved a mechanism that delays the progression of mitosis until condensed chromosomes are properly positioned on the mitotic spindle. To understand the molecular basis of such monitoring mechanism in human cells, we have been studying genes that regulate the mitotic checkpoint. Our early studies have led to the cloning of a full-length cDNA encoding MAD3-like protein (also termed BUBR1/MAD3/SSK1). Dot blot analyses show that BUBR1 mRNA is expressed in tissues with a high mitotic index but not in differentiated tissues. Western blot analyses show that in asynchronous cells, BUBR1 protein primarily exhibits a molecular mass of 120 kDa, and its expression is detected in most cell lines examined. In addition, BUBR1 is present during various stages of the cell cycle. As cells enter later S and G2, BUBR1 levels are increased significantly. Nocodazole-arrested mitotic cells obtained by mechanical shake-off contain BUBR1 antigen with a slower mobility on denaturing SDS gels. Phosphatase treatment restores the slowly migrating band to the interphase state, indicating that the slow mobility of the BUBR1 antigen is attributable to phosphorylation. Furthermore, purified recombinant His6-BUBR1 is capable of autophosphorylation. Our studies indicate that BUBR1 phosphorylation status is regulated during spindle disruption. Considering its strong homology to BUB1 protein kinase, BUBR1 may also play an important role in mitotic checkpoint control by phosphorylation of a critical cellular component(s) of the mitotic checkpoint pathway.

Cell Cycle Proteins↗

PubMed1998

Human Bub1: a putative spindle checkpoint kinase closely linked to cell proliferation.

Eukaryotic cells have evolved a mechanism that delays the onset of anaphase until chromosomes are properly positioned on the spindle. To understand the molecular basis of such surveillance mechanism in human cells, we have cloned a full-length cDNA encoding a putative mitotic checkpoint kinase termed hBub1. Sequence comparison reveals that hBub1 is a structurally conserved protein, sharing 23% amino acid residue identity with BUB1 of budding yeast. In addition, the NH2-terminal portion (161 amino acids) of hBub1 shows a significant homology to yeast MAD3, a protein also known to be involved in the mitotic checkpoint response pathway. Northern blot analyses show that the hBub1 mRNA level is abundantly expressed in tissues or cells with a high mitotic index. When Dami cells undergo terminal differentiation after treatment with phorbol ester, hBub1 expression in this cell line is down-regulated rapidly. The hBub1 protein level is low in G1 and remains relatively constant in S, G2, and M phases. Immunofluorescence analysis shows that hBub1 protein colocalizes with a centromere-kinetochore antigen CREST in interphase, mitotic prophase, and nocodazole-treated cells. Antibody electroporation experiments show that hBub1 is an important component of the spindle checkpoint pathway. Furthermore, fluorescence in situ hybridization analysis maps the hBub1 gene to chromosome 2q12-13. Our studies suggest that hBub1 expression is restricted to proliferating cells and appears to be involved in regulating cell cycle progression. The molecular cloning of hBub1 cDNA will facilitate the study of its role in spindle checkpoint control as well as its potential role in certain genetic disorders.

Amino Acid Sequence↗

PubMed1992

An outbreak of poisoning from Penicillium cyclopium contaminated dried persimmon.

It is the first report of an outbreak of 114 food-poisoning cases due to consumption of Penicillium cyclopium contaminated dried persimmon. Gastralgia, diarrhea, dizziness and general malaise are chief symptoms of the poisoning, with incubation period of 2-6 hrs generally and a short disease period (generally recovered within 2-3 days). No enteropathogenic organism, pathogenic coccus and Campylobacter jejuni were detected. Surface fungi counts were 49,000/g, 21.3 times of that discovered in the marketed dried persimmon. Penicillium cyclopium Westling was the dominant fungus isolated. Mouse toxicity tests were carried out with the crude extracts of the fungus culture. Diarrhea, tremor and convulsion were observed before death. During autopsy, necrosis and hemorrhagic foci were observed in G.I. tract after intra-peritoneal injection and intubation. In histo-pathological examination, different degree of necrosis and scaling of gastro-intestinal mucous membrane, lymphocyte infiltration, and necrosis of liver cells and renal tubule epithelial cells could be seen.

Adolescent↗