Biomedical subjects

Wei Han

Publications and source records attributed to Wei Han.

116 records · Page 7Linked to original sources

PubMed2003

[Progress of chlamydomonas as a model organism].

The unicellular alga Chlamydomonas offers a simple life cycle, easy culture and isolation of series of mutants, established the techniques and tool kit for molecular genetics and genetics analysis. It is now becoming the model organism for studies on photosynthesis in plant, flagellar assembly and function, cell cycle and circadian rhythms, signal transduction, light perception and cell recognition. It is summarized the progress of study on Chlamydomonas as a model organism in this paper.

English Abstract↗

PubMed2002

Comparison of ion-channel subunit expression in canine cardiac Purkinje fibers and ventricular muscle.

Although Purkinje fibers (PFs) play an important role in cardiac electrophysiology, almost nothing is known about the expression of ion-channel subunits in PFs. We applied competitive reverse transcription-polymerase chain reaction, Western blotting, and immunocytochemistry to compare the expression of ion-channel subunit mRNA and protein in canine PFs versus ventricular muscle (VM). For transient outward current-related subunits, Kv4.2 was not detected, and Kv1.4 expression was extremely low. Kv4.3 expression was of the same order for VM and PFs. The tetraethylammonium chloride-sensitive subunit Kv3.4 was expressed much more strongly in PFs than in VM, and Kv channel-interacting protein transcript expression was 25-fold stronger in VM than in PFs. For delayed rectifiers, ERG and KvLQT1 expression was lower in PFs at both mRNA and protein levels. Although minK transcripts were more numerous in PFs, minK protein was significantly more strongly expressed in VM. L-type Ca2+ current alpha-subunit (Ca(V)1.2) and Na+-Ca2+ exchanger proteins were more strongly expressed in VM than in PFs. For T-type Ca2+ current, Ca(V)3.1, Ca(V)3.2, and Ca(V)3.3 transcripts were all more strongly expressed in PFs. For the nonselective cation current, hyperpolarization-activated cation channel 1 (HCN1) expression was subquantifiable, HCN2 transcript expression was comparable in PFs and VM, and HCN4 mRNA expression was strong in PFs but below the detection threshold in VM. HCN2 and HCN4 protein expression was much stronger in PFs than in VM. We conclude that ion-channel subunit expression in PFs differs from that in VM in ways that are consistent with, and shed light on the molecular basis of, well-recognized fundamental PF ionic properties.

Animals↗

PubMed2002

Properties of potassium currents in Purkinje cells of failing human hearts.

Cardiac Purkinje fibers play an important role in cardiac arrhythmias, but no information is available about ionic currents in human cardiac Purkinje cells (PCs). PCs and midmyocardial ventricular myocytes (VMs) were isolated from explanted human hearts. K(+) currents were evaluated at 37 degrees C with whole cell patch clamp. PCs had clear inward rectifier K(+) current (I(K1)), with a density not significantly different from VMs between -110 and -20 mV. A Cs(+)-sensitive, time-dependent hyperpolarization-activated current was measurable negative to -60 mV. Transient outward current (I(to)) density was smaller, but end pulse sustained current (I(sus)) was larger, in PCs vs. VMs. I(to) recovery was substantially slower in PCs, leading to strong frequency dependence. Unlike VM I(to), which was unaffected by 10 mM tetraethylammonium, Purkinje I(to) was strongly inhibited by tetraethylammonium, and Purkinje I(to) was 10-fold more sensitive to 4-aminopyridine than VM. PC I(sus) was also reduced strongly by 10 mM tetraethylammonium. In conclusion, human PCs demonstrate a prominent I(K1), a time-dependent hyperpolarization-activated current, and an I(to) with pharmacological sensitivity and recovery kinetics different from those in the atrium or ventricle and compatible with a different molecular basis.

Adult↗

PubMed2002

Beta-catenin expression and allelic loss at APC in sporadic colorectal carcinogenesis.

beta-catenin is involved in E-cadherin-mediated cell adhesion, intracellular signal transduction, and also interacts with adenomatous polyposis coli (APC) protein. We previously found that 31% of colorectal adenomas and 84% of carcinomas showed reduced membranous staining of beta-catenin, while 46% of adenomas and 79% of carcinomas displayed beta-catenin nuclear expression. Importantly, a reciprocal relationship between reduced membranous and increased nuclear beta-catenin expression was demonstrated in the development from adenoma to carcinoma. To clarify whether this relates to an abnormality of the APC gene ( APC), we have now studied allele loss in microdissected tissues from 74 adenomas and 21 carcinomas (sporadic cases, previously immunostained for beta-catenin) by analysis of the microsatellites D5S346, D5S82 and D5S299. Fifty-five tumors (57.8%) showed allele loss at APC (no difference between adenomas and carcinomas). Thirty-one of these 55 (31/55, 56.4%) displayed both increased nuclear localization and reduced membranous staining of beta-catenin, and thirteen tumors (13/55, 23.6%) manifested either nuclear expression without changes in membranous expression or reduced membranous staining without nuclear expression (9 and 4 cases, respectively), while 11 (11/55, 20.0%) preserved normal membranous expression. Adenomas and carcinomas showing both nuclear and reduced membranous expression of beta-catenin, compared with those with normal membranous expression, tended to show allele loss ( P<0.01). In addition, 24 (24/95, 25.6%) tumors showed a change in the pattern of beta-catenin expression, but did not exhibit allele loss. These results suggest that although there may be a number of mechanisms responsible for changes in beta-catenin expression in colorectal tumors, dysfunction of APC may be the major cause of this phenomenon.

Adenoma↗

PubMed2002

[Construction of bi-cistronic co-expression plasmid of mIL-12 and the expression in vitro or in vivo]

OBJECTIVE: To construct a bi-cistronic co-expression plasmid for mouse interleukin-12 and to observe its expression in vitro or in vivo.METHODS: The full-length cDNA encoding p35 and p40 was cloned into eukaryotic cells expression vector pcDNA 3.1 respectively. Subsequently,the p35 expression unit was inserted into pcDNA 3.1/p40 to produce the bi-cistronic co-expression plasmid in which the p35 and p40 genes were controlled by their own CMV.The plasmid was expressed in vitro and in vivo. RESULTS: The mIL-12 in the supernatant was detected by ELISA after the pCmIL-12 was transfected into COS-7 cells. The activity of NK cells could be augmented by the supernatant in vitro and also by by intradermal delivery of pCmIL-12 in vivo. CONCLUSION: The plasmid constructed by us can express biologically active mIL-12 in vitro and in vivo.

Journal Article↗

PubMed2002

[The effect of multi-unit ribozymes on the growth inhibition and apoptosis induction of CML K562 cells].

OBJECTIVE: To investigate the possibility of multi-unit ribozymes to purge bone marrow of chronic myelocytic leukemia (CML), its in vitro cleavage ability and the reversal effect on CML cell's malignant phenotype. METHODS: As bcr-abl fusion gene plays an important role in CML pathology, three single-unit ribozymes were designed and synthesized in 44 base pairs near the fusion point, two enzyme cleavage sites on bcr gene and one on abl gene. Multi-unit ribozymes' in vitro transcription and retroviral vector through gene recombination were constructed. Then, its in vitro cleavage ability was tested and the retroviral vector was transfected into K562 cell. Through MTT assay, the incorporation rate of (3)H-TdR, RT-PCR, Southern and Northern blot hybridization, flow cytometry, transmission and scanning electron microscopy were used to study the effect of multi-unit ribozymes on CML cell proliferation, cell structure, cell cycle and the induction of apoptosis. RESULTS: Multi-unit ribozymes had in vitro cleavage efficiency of 70.8%. After the transfection of multi-unit ribozymes retroviral vector into K562 cell, cell proliferation and DNA synthesis were greatly reduced with an inhibition rate of about 50% after 96 hours of transfection. Multi-unit ribozymes could cleave K562 cell's RNA with a reduction rate about one 1 000 th of the original. By flow cytometry (FCM), 18.4% cells underwent apoptosis after 72 hours transfection with most of the cells blocked in the G phase. Here, the ratio in S phase was lowered by 41.9%. Under transmission and scanning electron microscope, compaction of nuclear chromation and apoptosis bodies were observed in the transfected cells. CONCLUSION: Multi-unit ribozymes possess high cleavage ability in vitro. The ribozymes, whose retroviral vector being transfected into CML cell, are able to express a lasting ability to cleave the fusion gene, induce apoptosis, reduce cell proliferation, revert the malignant phenotype. It is possible to make use of multi-unit ribozymes to purge CML bone marrow. Therefore, multi-unit ribozymes may very well be valuable in the gene therapy of CML.

Apoptosis↗

PubMed2002

[CD62p expression in platelet during the preparation course of Cryopreservated platelet-rich plasma].

In order to explore the factors that affect CD62p expression in platelet during the whole course of cryopreservated platelets preparation, CD62p expression of platelet was evaluated by flow cytometry assay. The whole course of cryopreservated platelets preparation in order included whole blood collection, centrifugation for fresh platelet-rich plasma preparation, addition of dimethyl sulfoxide, and freeze in -80 degrees C refrigerator and thaw in 38 degrees C water bath. Result showed that the CD62p expressed slowly from whole blood collection to addition of dimethyl sulfoxide, but expressed abruptly after freeze and thaw and it occupied 82 per cent of the whole expression. It was concluded that the whole blood collection, centrifugation for fresh platelet enriched plasma preparation and addition of dimethyl sulfoxide were optimized in the whole course, but the damage to platelets in the whole course of cryopreservation could not be avoided. It suggests that improved techniques are needed to reduce the damage to cryopreservated platelets.

Blood Platelets↗

PubMed2002

[Flow cytometry combined assay for phosphatidylserine and CD62p expressed by preserved platelets].

Human platelets have distinct characters when preserved by different methods. A efficient flow cytometric assay for different preserved platelets expression of CD62p and phosphatidylserine(PS) is in dire need. Efficient flow cytometric assay for CD62p and PS expressed by preserved platelets was established and the major conditions were optimized. The platelets need not to be washed to wipe off plasma and can be labelled diredtly during the sample preparation. It is efficient for flow cytometric analysis when fresh platelet riched plasma (FPRP) was set as negative control, thrombin actived FPRP, and liquid nitrogen treated FPRP were set as positive control respectively. Gly-Pro-Arg-Pro acetate salt (GPRP) was applied to prevent platelets aggregation and fibrin formation, stabilize platelets and minimize the artificial platelets activation. This is also the key to conquer difficulty of flow cytometric quantitive analysis when platelet, Ca(2+) and plasma coexist. This flow cytometric method is specially suitable for the multi-parameter assay including PS expression for cryopreserved platelets. Minimal sample manipulation, no fixation, and GPRP application resulted in minor artifacts and good sample stability. Results suggested, this flow cytometric assay for preserved platelets is simple and efficient. In addition, the author prepared four different methods treated platelets that can be easily distinguished through this flow cytometric assay. It not only makes sure the practicability of this flow cytometric assay, but also suggests the value of the treated platelets applied in preserved platelets flow cytometric ass

Blood Platelets↗