Biomedical subjects

Wen Chen

Publications and source records attributed to Wen Chen.

At least 37 records · Page 2Linked to original sources

PubMed2005

Wind-dispersed seed deposition patterns and seedling recruitment of Artemisia halodendron in a moving sandy land.

BACKGROUND AND AIMS: Artemisia halodendron is a native sub-shrub that occurs mainly in moving and semi-fixed sandy lands in Inner Mongolia, China. Information on the spatial patterns of wind-dispersed seed deposition and seedling recruitment of A. halodendron inhabiting moving sandy lands is very limited. The aim of this study was to examine wind-dispersed seed deposition patterns and post-dispersal recruitment of A. halodendron seedlings. * METHODS: The spatial patterns of wind-dispersed seed deposition and seedling recruitment of A. halodendron were examined by investigating the numbers of deposited seeds, emerged and surviving seedlings using sampling points at a range of distances from the parent plant in eight compass directions for two consecutive growing seasons. * KEY RESULTS: Wind-dispersed seed deposition showed considerable variation between directions and years. Wind transported A. halodendron seeds only a few meters away from the parent plant in all eight directions. Seedling emergence and establishment also showed between-direction and between-year variability, but the spatial pattern of seedling distribution differed from that of seed deposition. Only a very small fraction (<1 %) of the deposited seeds emerged in the field and survived for long enough to be included in our seedling censuses at the end of the growing season. * CONCLUSIONS: The spatial variation in wind speed and frequency strongly affects the pattern of seed deposition, although the variation in seed deposition does not determine the spatial pattern of seedling recruitment. Seeds of A. halodendron are not dispersed very well by wind. The low probability of recruitment success for A. halodendron seedlings suggests that this species does not rely on seedling recruitment for its persistence and maintenance of population.

Artemisia↗

PubMed2005

Comparative regulation of major enzymes in the bile acid biosynthesis pathway by cholesterol, cholate and taurine in mice and rats.

These enzymes play important roles in the biosynthesis of bile acids. They are cholesterol 7alpha-hydroxylase (CYP7A1), the rate limiting enzyme in the classic pathway, sterol 12alpha-hydroxylase (CYP8B1), the key enzyme for synthesis of cholic acid (CA), and sterol 27-hydroxylase (CYP27), the initial enzyme in the alternative pathway. In the present study, the susceptibility of these three enzymes to dietary cholesterol and cholate, and the cholesterol lowering effect of taurine were determined in male C57BL/6 mice and Wistar rats. Both mice and rats were divided into 6 groups: control group (N), high cholesterol diet group (C), high cholesterol and cholate diet group (CB), and their 1% taurine-supplemented groups (NT, CT, CBT, respectively). After animals were fed with the respective diets for one week, the mRNA levels of CYP7A1 increased in the C-group compared with those of the N-group, and decreased in the CB-group compared with those of the C-group in both mice and rats. But the extent of decrease is different between the two species. CYP8B1 was also markedly repressed by cholate in mice, but not in rats. These results are consistent with the changes in serum and liver cholesterol concentrations. Taurine significantly increased CYP7A1 mRNA levels in the CBT-group compared with the CB-group in both animal models, with a subsequent decrease in serum and liver cholesterol levels and increase in fecal bile acid excretion. Up-regulated CYP8B1 was also observed after taurine supplementation in the CBT-group in mice. No increase in CYP7A1 was produced by taurine in the CT-group compared with that of the C-group in mice, although the changes of serum and liver cholesterol and fecal bile acids indicated taurine showed an efficient cholesterol lowering effect. In addition, CYP27 was induced in both C- and CB-groups of rats but not of mice, and no changes were produced by taurine. The overall results suggest that there are differences between mice and rats in susceptibility of the three enzymes to dietary cholesterol and cholate, and taurine induced CYP7A1 to produce its cholesterol-lowering effect only in the presence of cholate in the cholesterol diet.

Analysis of Variance↗

PubMed2005

An expression signature classifies chemotherapy-resistant pediatric osteosarcoma.

Osteosarcoma is the most common malignant bone tumor in children. Osteosarcoma patients who respond poorly to chemotherapy are at a higher risk of relapse and adverse outcome. Therefore, it was the aim of this study to identify prognostic factors at the time of diagnosis to characterize the genes predictive of poor survival outcome and to identify potential novel therapeutic targets. Expression profiling of 30 osteosarcoma diagnostic biopsy samples, 15 with inferior necrosis following induction chemotherapy (Huvos I/II) and 15 with superior necrosis following induction chemotherapy (Huvos III/IV), was conducted using Affymetrix U95Av2 oligonucleotide microarrays. One hundred and four genes were found to be statistically significant and highly differentially expressed between Huvos I/II and III/IV patients. Statistically significant genes were validated on a small independent cohort comprised of osteosarcoma xenograft tumor samples. Markers of Huvos I/II response predominantly were gene products involved in extracellular matrix (ECM) microenvironment remodeling and osteoclast differentiation. A striking finding was the significant decrease in osteoprotegerin, an osteoclastogenesis inhibitory factor. Additional genes involved in osteoclastogenesis and bone resorption, which were statistically different, include annexin 2, SMAD, PLA2G2A, and TGFbeta1. ECM remodeling genes include desmoplakin, SPARCL1, biglycan, and PECAM. Gene expression of select genes involved in tumor progression, ECM remodeling, and osteoclastogenesis were validated via quantitative reverse transcription-PCR in an independent cohort. We propose that osteosarcoma tumor-driven changes in the bone microenvironment contribute to the chemotherapy-resistant phenotype and offer testable hypotheses to potentially enhance therapeutic response.

Animals↗

PubMed2005

Site-selective DNA hydrolysis by Ce(IV)-EDTA with the use of one oligonucleotide additive bearing two monophosphates.

Two deoxyuridine derivatives each bearing a monophosphate group at the 5-position with a C3 linker, were incorporated into an oligonucleotide. By using this modified oligonucleotide, a bulge was formed at a predetermined position in a DNA substrate, and two monophosphate groups were placed at both junctions of the bulge. Upon treatment of the mixture with Ce(IV)-EDTA at pH 7.0, the phosphodiester linkages at the bulge site were selectively and efficiently hydrolyzed. The monophosphate groups introduced into the bulge site greatly accelerated site-selective DNA scission. Compared with the previously reported two-additive system, which combines two oligonucleotide additives each with a monophosphate at their termini, the present one-additive system is simpler and more convenient. Furthermore, site-selective DNA hydrolysis by using this one-additive system is successful even at high reaction temperatures (e.g., 55 degrees C). This reflects the thermodynamic stability of the duplexes formed between the substrate and the additive DNA.

Base Sequence↗

PubMed2005

Asymptomatic genital infection of human papillomavirus in pregnant women and the vertical transmission route.

To further investigate the vertical transmission route of human papillomavirus (HPV) and the indication for the choice of mode of delivery, the infective status of 152 asymptomatic pregnant wemen and the maternal-fetal transmission were studied. By using general primers in polymerase chain reaction (GP-PCR) combined with restriction fragment length polymorphism analysis, HPV DNA positive rate in cervical secretions and venous blood in asymptomatic pregnant women was 36.21% and 52.78%, respectively, and the identified genotypes were mainly HPV16 and 18. The maternal-fetal transmission rate of HPV via genital tract as well as blood was 40.91% and 57. 89%, respectively. It was concluded that besides the transmission route of genital tract and amniotic fluid, there was also transplacental transmission of HPV in utero. Therefore,in our opinion, it is not an absolut indication to perform a cesarean delivery for the pregnant women with HPV asymtomatic genital infection.

DNA, Viral↗

PubMed2005

Combined buccal mucosa graft and local flap for urethral reconstruction in various forms of hyposapdias.

PURPOSE: Hypospadias is one of the most common congenital deformities in the male urogenital system. Although there are more than 250 techniques for treating hypospadias, it is often difficult to repair severe hypospadias using conventional methods. MATERIALS AND METHODS: We combined a buccal mucosa graft with a local onlay flap for urethral reconstruction in cases of severe hypospadias or a failed previous operation. A total of 162 patients with hypospadias (glandular 11, penile 40, penoscrotal 49, scrotal 34 and perineal 28) were treated between July 2000 and November 2003. For patients whose urethral meatus was perineal 2 treatment steps were taken. First, we used the aforementioned method to construct the penile urethra, and then we constructed the scrotal and perineal urethra with a local flap. RESULTS: Of the 134 nonperineal cases 127 were managed successfully in 1 stage, and 26 of 28 perineal cases were managed successfully in 2 stages. Most patients had a satisfactory penile appearance. A urethral fistula resulted in 8 cases, of which 4 closed spontaneously within 1 month postoperatively. Meatal stenosis occurred in 1 case. CONCLUSIONS: This technique is simple, safe and reliable, especially in cases of failed previous operation or for salvage hypospadias repair with deficient local tissue.

Adolescent↗

PubMed2005

Proteomic analysis of corticobasal degeneration: a case study of corticobasal degeneration at the proteome level.

Corticobasal degeneration (CBD) is an adult-onset progressive neurodegenerative disorder. However, its pathogenic mechanisms underlying this disorder remain poorly understood. The authors examined changes of proteome profiles between three nondemented comparison brains and a CBD brain based on two-dimensional gel electrophoresis. Two up-regulated proteins in the CBD brain were identified as protein-L-isoaspartate (D-aspartate) O-methyltransferase and cofilin 1 (non-muscle), and six down-regulated proteins were identified as carbonyl reductase [NADPH] 1, two of peptidyl-prolyl cis-trans isomerase A, ubiquitin carboxyl-terminal hydrolase isozyme L1, phosphoglycerate mutase 1 (brain) and chain A of human peroxiredoxin 5. Subsequently, the possible relevance of these changes was analyzed.

Aged↗

PubMed2005

Biofilm formation by the periodontopathic bacteria Treponema denticola and Porphyromonas gingivalis.

BACKGROUND: Periodontitis develops as a result of the interaction of the host with subgingival plaque bacteria. Both Porphyromonas gingivalis and Treponema denticola are frequently associated together in these oral biofilms. METHODS: The molecular basis for in vitro biofilm formation was investigated for P. gingivalis 381, T. denticola 35405, and mixtures of the two organisms using microtiter plate assays. In addition, the biofilms were examined following confocal laser scanning microscopy. RESULTS: P. gingivalis 381, but not T. denticola strains, formed biofilms in vitro. This property was dependent, in part, on the strain 381 fimA, ppk, and usp genes. Microarray and Northern blot analyses suggested that the expression of the ppk gene was required for maximal expression of the uspA gene. P. gingivalis 381 formed synergistic biofilms when incubated with T. denticola strains. This process was dependent upon the strain 381 rgpB and fimA genes as well as the T. denticola flgE and cfpA genes. CONCLUSIONS: P. gingivalis 381 formed synergistic biofilms with T. denticola 35405. These results may be relevant to the previous observations that the two organisms are frequently observed together in subgingival plaque with the spirochetes localized to the exterior of the oral biofilms. It is suggested that other such synergistic effects may also occur between other plaque bacteria.

Bacterial Proteins↗

PubMed2005

Automation of liquid-liquid extraction-spectrophotometry using prolonged pseudo-liquid drops and handheld CCD for speciation of Cr(VI) and Cr(III) in water samples.

A simple spectrophotometric system, based on a prolonged pseudo-liquid drop device as an optical cell and a handheld charge coupled device (CCD) as a detector, was constructed for automatic liquid-liquid extraction and spectrophotometric speciation of trace Cr(VI) and Cr(III) in water samples. A tungsten halogen lamp was used as the light source, and a laboratory-constructed T-tube with two open ends was used to form the prolonged pseudo-liquid drop inside the tube. In the medium of perchloric acid solution, Cr(VI) reacted with 1,5-diphenylcarbazide (DPC); the formed complex was automatically extracted into n-pentanol, with a preconcentration ratio of about 5. The organic phase with extracted chromium complex was then pumped through the optical cell for absorbance measurement at 548 nm. Under optimal conditions, the calibration curve was linear in the range of 7.5 - 350 microg L(-1), with a correlation coefficient of 0.9993. The limit of detection (3sigma) was 7.5 microg L(-1). That Cr(III) species cannot react with DPC, but can be oxidized to Cr(VI) prior to determination, is the basis of the speciation analysis. The proposed speciation analysis was sensitive, yet simple, labor-effective, and cost-effective. It has been preliminarily applied for the speciation of Cr(VI) and Cr(III) in spiked river and tap water samples. It can also be used for other automatic liquid-liquid extraction-spectrophotometric determinations.

Automation↗

PubMed2005

Hepatitis C virus infection, Linxian, China.

Bloodborne viruses may have spread in rural China during the past 25 years, but population-based prevalence estimates are lacking. We examined the frequency of hepatitis C virus (HCV) and HIV type 1 (HIV-1) among residents of Linxian, a rural community in Henan Province. In 2000, blood was collected from participants (> or = 55 years of age) who had enrolled in a population-based nutritional intervention trial in 1985. We randomly selected 500 participants for HCV testing and 200 participants for HIV-1 testing. For HCV, 48 (9.6%) of 500 participants were positive by enzyme immunoassay and recombinant immunoblot assay (95% confidence interval, 7.0%-12.2%), and prevalence was lowest in the most geographically isolated participants. Among the HCV-infected participants, 42 had a specimen available from 1985, of which 16 (38.1%) were positive for HCV. For HIV-1, 0/200 participants were positive. We conclude that HCV is now a common infection among older adults in Linxian, China.

Aged↗

PubMed2005

[Repair of face soft tissue defect with prefabricated neck expander flap with the vessels of temporalis superficialis].

OBJECTIVE: To probe the principle and the method to repair facial soft tissue defect with the prefabricated expander flap the neck with the vessels of temporalis superficialis. METHODS: The expander was implanted into the surface layer of the platysma in neck. The pedicle of the expander flap contained the arteria temporalis superficialis and its ramux parietalis. After 3 months, the prefabricated island expander flaps pedicled with the arteria temporalis superficialis and its ramux parietalis could be transferred to the face. From 1998 to 2003, 6 cases of facial soft tissue defects were repaired. The maximal flap size was 12 cm x 8 cm. The pedicle length was 7-8 cm. RESULTS: After a follow-up of 3-6 months, all expander flaps survived. The excellent function and cosmetic result were achieved. CONCLUSION: The prefabricated expander flaps of the neck pedicled with the arteria temporalis superficialis and its ramux parietalis can be transferred to the upper face to repair tissues defect. The supply of blood of the prefabricated expander flaps were safe and reliable. The survived areas of the flaps are directly proportional to the areas of temporalis superficialis fascia combining the expander flaps.

Adolescent↗

PubMed2005

[Bacteriology study of hypospadias].

OBJECTIVE: This clinical study was to explore why the neo-urethra is liable to be infected after hypospadias operation, find the source and the common floras of infection, and accordingly, improve the peroperation procedures so as to reduce postoperative infection rate. METHODS: The pathogenic floras were examined and analyzed by germiculture and karyotype analysis. RESULTS: The bacteria in the neo-urethra mostly came from the orifice and the reconstruction material of the urethra. The most common floras that caused infection were gram-positive coccus. The most sensitive antibiotics for hypospadias infection were demethylvancomycin. CONCLUSION: The postoperative infection of hypospadias is incisional, not the urinary system infection. Because the microenvironment of the neo-urethra is more suitable for infection than that of the skin or mucosa, the reconstructed urethra is likely to be infected.

Bacterial Typing Techniques↗

PubMed2005

[Accumulation of La(NO3)3 in mice liver and its genetic toxicity].

By using ICP-MS method, this paper determined the accumulation of La in mice liver after the mice being fed with La(NO3)3 water solution for thirty days, and through in vitro experiment, studied the effect of La(NO3)3 on the micronucleus rate of mice bone marrow cells and the cleavage action of La(NO3)3 on genome DNA to investigate the genetic toxicity of La. The results showed that when the treated concentration was 1000, 500, 300 and 50 microg x ml(-1), the amount of La in mice liver reached 1.46, 0.558, 0.529 and 0.083 microg x g(-1), respectively. Compared with control, the La amount in disposed groups' mice livers increased with increasing La(NO3)3 concentration in water (r = 0.980). T-test results showed that there existed significant differences in 1000, 500 and 300 microg x ml(-1) disposed groups when compared with the control (P < 0.05). The micronucleus rate of mice bone marrow cells increased with increasing La(NO3)3 concentration in water (r = 0.853). The in vitro experiments showed that La(NO3)3 could make DNA cleaved. It could be concluded that that La might be accumulated in organisms, and could induce the damage of genetic material in cells.

Animals↗

PubMed2005

[Effect of triptolide on urinary monocyte chemottractant protein-1 in patients with diabetic nephropathy].

OBJECTIVE: To observe the change of urinary monocyte chemottractant protein-1 (MCP-1) in patients with diabetic nephropathy (DN), and to explore the therapeutic effect and mechanism of triptolide (TL) in treating DN. METHODS: Thirty-five patients in the treated group were treated with TL plus benazepril and thirty two patients in the control group were treated with benazepril alone for six months. The change of urinary MCP-1 was measured before and after treatment. RESULTS: Level of urinary MCP-1 in DN patients was significantly higher than that in healthy subjects (P < 0.01), but it could be significantly decreased after TL treatment, showing significant difference as compared with that in the control group (P < 0.05). CONCLUSION: Determination of urinary MCP-1 level is beneficial to know the degree of kidney inflammation in DN patients. TL can inhibit inflammatory reaction to decrease the level of urinary MCP-1, and thus improve the renal function.

Adult↗

PubMed2005

[The inherent liability to infection of various tissue for urethra reconstruction].

OBJECTIVE: Observing the long-term results of reconstructed urethra to reduce the postop infection rate of hypospadias. To explore the standard of selecting tissue for urethra reconstruction by comparing the different inherent liability to infection in use of different kinds of tissue for urethra reconstruction. METHODS: Neo-urethra inner wall and normal urethra were observed through urography and urethroscope. The tissue section of neo-urethra, normal urethra and tissue for urethra reconstruction were observed through light microscope, scanning electron microscope and transmission electron microscope. RESULTS: The structure and liability to infection of neo-urethra made of bladder mucosa, buccal mucosa or skin never changed after long time. Metaplasia never took place in neo-urethra. CONCLUSIONS: The structure and liability to infection of neo-urethra were the same as those of the congeneric tissue. Bladder or buccal mucosa is the best tissue for urethra reconstruction considering urethra microenvironment. Neo-urethra made of skin is more liable to infection by nature. The best opportunity of hypospadias operation should be before puberty.

Adolescent↗

PubMed2005

[Repair of distal urethral stricture after urethroplasty of hypospadias].

OBJECTIVE: To search for a new method to repair distal urethral stricture resulting from urethroplasty of hypospadias. METHODS: From February 2000 to March 2004, 16 patients with distal urethral stricture were treated by use of cutting stricture urethra and their distal urethra were reconstructed with phallic flap. RESULTS: All operations were successful without complication of flap necrosis. After 7 days of operation, the patients had free micturition and thick stream of urine. Eleven patients were followed 2 months to 4 years, the satisfactory result was obtained. CONCLUSION: It is a simple and good method to reconstruct the distal urethra by superimposing the phallic flap on the cut stricture urethra after urethroplasty of hypospadias.

Child↗

PubMed2005

[Study on the mechanism of oocyte aneuploidy by spectral karyotyping].

OBJECTIVE: To establish the method of detecting oocyte aneuploidy by spectral karyotyping (SKY). METHODS: The unfertilized oocytes were fixed 1-2 days after oocyte retrieval. Spectral karyotyping was performed according to the protocol. RESULTS: 64% of oocytes were normal, 36% of oocytes were aneuploidy, of which 22% were due to nondisjunction and 14% unbalanced predivision. CONCLUSION: SKY is an effective method for detecting oocyte aneuploidy. Both nondisjunction and unbalanced predivision are involved in oocyte aneuploidy formation.

Aneuploidy↗

PubMed2005

[Effect of Chinese herbal medicine on patients with primary hepatic carcinoma in III stage during perioperational period: a report of 42 cases].

OBJECTIVE: To investigate the synergetic effect of general therapy of Chinese herbal medicine with surgical operation. METHODS: Fourty-two patients in the integrative group were treated with jiedu xiaozheng yin for 7 days before operation, and fuzheng yiliu recipe after operation for 2 years, and 30 patients in the control group underwent operation alone. Their cellular immune function, survival rate and recurrence rate were compared and analyzed. RESULTS: The accumulative survival rate of 6-month, 12-month, 24-month and 36-month in the integrative group was 97.6%(41/42), 85.7%(36/42), 52.3% (22/42) and 45.5(17/42)% respectively and those in the control group 96.7% (29/30), 83.3% (25/30), 50.0% (15/30) and 30.0% (9/30), respectively, among them the 36-month survival rate was significantly different between the two groups (P < 0.05). The 24-month recurrence rate in the two groups was 54.8% and 80.0% respectively, the difference between the two was significant (P < 0.05). CONCLUSION: Administration of compound Chinese herbal medicine in peri-operational period has definite effect on primary hepatic carcinoma in III stage, it can improve patients' immune function, decrease the recurrence rate and increase the cumulative survival rate.

Adult↗