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Biomedical subjects

Z Chen

Publications and source records attributed to Z Chen.

At least 253 records · Page 14Linked to original sources

Enhanced continent mechanism of tapered ileum by extramural support from the pouch and abdominal walls: a preliminary report of a clinical study.

PURPOSE: We constructed a reliable continent tube that is easy to catheterize and surgically simple. MATERIALS AND METHODS: Eight patients with bladder cancer underwent a procedure in which ileal segment was tapered as an efferent tube, of which a part was placed between the back surface of the rectus muscle and the ileal pouch wall. The internal orifice of the tapered ileum was anastomosed to the ileal pouch and its external orifice was anastomosed to the umbilicus. Urodynamic and radiological studies were done postoperatively in 7 cases. RESULTS: The stoma was easily catheterized with a 16Fr catheter in all cases. One patient died of heart disease 55 days postoperatively, while 6 of the remaining 7 were completely continent day and night. Urodynamic study of the efferent tubes showed that maximum close pressure with the pouch full was significantly higher than with the pouch empty (p <0.001). Retrograde radiography of the efferent tubes demonstrated perfect canalization without stenosis. CONCLUSIONS: This study indicates that the continent mechanism of tapered ileum may be greatly enhanced by fixing it between the abdominal and pouch walls. This maneuver also provides easy catheterization and surgical simplicity.

Abdominal Muscles↗

Coexpression of proangiogenic factors IL-8 and VEGF by human head and neck squamous cell carcinoma involves coactivation by MEK-MAPK and IKK-NF-kappaB signal pathways.

Interleukin 8 (IL-8) and vascular endothelial growth factor (VEGF) promote tumor angiogenesis, growth, and metastasis and are coexpressed by human head and neck squamous cell carcinomas (HNSCCs) and a variety of other cancers. The promoters of the IL-8 and VEGF genes contain different recognition sites for transcription factors nuclear factor (NF)-kappaB and activator protein-1 (AP-1), which we showed previously are coactivated in HNSCCs. NF-kappaB and AP-1 may be modulated by the inhibitor kappaB kinase (IKK) and mitogen-activated protein kinase (MAPK) signal pathways, but the contribution of these pathways to expression of IL-8 and VEGF and as potential targets for antiangiogenesis therapy in HNSCC is not known. In this study, we examined the effects of modulation of the MAPK and IKK pathways on expression of IL-8 and VEGF by UM-SCC-9 and UM-SCC-11B cell lines. Interruption of IKK-mediated activation of NF-kappaB by expression of an inhibitor kappaB alpha mutant (IkappaB alphaM) in UM-SCC-9 cells resulted in partial inhibition of expression of IL-8 but not VEGF. Analysis of possible alternative pathways for induction of these genes revealed activation of the MAPK extracellular signal-regulated kinase (ERK1/2) in cell lines UM-SCC-9 and UM-SCC-11B. Basal and tumor necrosis factor-alpha-inducible phosphorylation of ERK1/2 and secretion of IL-8 and VEGF could be specifically inhibited by a MEK inhibitor, U0126. Expression of IL-8 and VEGF in the cell lines was associated with coactivation of both NF-kappaB and AP-1, and U0126 inhibited both NF-kappaB and AP-1 reporter activity in UM-SCC-9 and UM-SCC-11B cells. The ERK pathway appears to contribute to expression of IL-8 and VEGF and transactivation of NF-kappaB as well as AP-1 in HNSCC. Combined inhibition of both MAPK and IKK pathways may be needed for suppression of the signal transduction mechanism(s) regulating VEGF and IL-8 secretion and angiogenesis by human HNSCC.

Butadienes↗

[Mannose-binding protein gene polymorphism influences the patterns of glomerular immune deposition in IgA nephropathy].

OBJECTIVE: To investigate the relationship between mannose-binding protein(MBP) gene codon 54 (GGC/GAC) polymorphism and the patterns of glomerular immune deposition in IgA nephropathy (IgAN) and explore its functional significance. METHODS: IgAN patients were divided into two groups according to the pattern of glomerular immune deposition. Group A included 77 patients with glomerular IgA and C3 deposits. Group AGM consisted of 70 patients with glomerular IgA, IgG, IgM, C3 and Clq deposits. One hundred and forty healthy adults were used as normal controls. MBP genotypes were investigated by PCR-RFLP. Serum MBP levels of some subjects with different genotypes were also assayed by ELISA simultaneously. RESULTS: The genotype frequency of GAC heterozygotes was significantly higher in group AGM than in group A (41.4% vs. 19.5%, P<0.01) or normal subjects (41.4% vs. 26.4%, P<0.05), while no difference was found in the distribution of MBP genotypes between group A and normal subjects. The allele frequency of GAC mutation was also higher in group AGM than in group A (0.236 vs. 0.136, P<0.05) or normal subjects (0.236 vs. 0.146, P<0.05). The variant allele (GAC) was markedly associated with group AGM (OR=1.95, 95%CI: 1.06-3.58). In both group A and group AGM, more patients carrying the variant allele had episodes of upper respiratory or gastrointestinal infections prior to the onset or exacerbation of IgAN than wild homozygotes. In addition, a significant difference in serum MBP level was also observed among the three genotypes (GGC/GGC>GGC/GAC>GAC/GAC) (P<0.0001) for all groups, while there were no differences in serum MBP levels for subjects with the same genotypes among the three groups (P>0.05). CONCLUSION: The above findings provide evidence that IgAN patients with abundant immune deposits in glomeruli show a higher frequency of MBP gene variation which is associated with a high frequency of infection and a low serum MBP level. This genetic deficiency may lead to an impaired first-line defense and a less effective clearance of immune complex than those without this mutation and thereafter accelerate glomerular immune deposition during the process of disease.

Adolescent↗

Telomerase activity in relation to pro- and anti-apoptotic protein expression in high grade non-Hodgkin's lymphomas.

BACKGROUND AND OBJECTIVES: Telomerase activity (TA) is determined by the catalytic unit telomerase reverse transcriptase (hTERT). In vitro studies show that hTERT is downregulated by wild type p53 and TA is upregulated by BCL-2 expression. The aim of this study was to investigate the relationship of TA and mRNA expression of hTERT, telomerase RNA (hTER) and Tankyrase in 31 samples from patients with high-grade non-Hodgkin's lymphoma (HG-NHL). The results were then related to apoptosis and proliferation and the expression of p53 and BCL-2 family member proteins. DESIGN AND METHODS: The telomeric repeat amplification protocol (TRAP) assay and reverse transcription-polymerase chain reaction (RT-PCR) were used to quantify TA, and hTERT, hTER and Tankyrase mRNA expression. Proliferation (Ki67), p53, BCL-2, MCL-1, BAX and BAK protein expression were evaluated by immunohistochemistry. Apoptosis was evaluated by TUNEL staining. RESULTS: TA was detected in 93% of HG-NHL and tended to be higher in p53+ lymphomas. A positive correlation existed between mRNA expression of hTERT, hTER and Tankyrase. hTERT mRNA expression tended to be higher with increasing levels of apoptosis and proliferation, in HG-NHL samples lacking BAX expression and in samples from patients with survival shorter than 3.5 years. hTER mRNA expression was significantly higher in BAX and BAK negative samples. INTERPRETATION AND CONCLUSIONS: Telomerase is activated or upregulated in the majority of HG-NHL. Enhanced TA combined with deregulation of the factors responsible for cell survival and proliferation may contribute to the development and progression of lymphomas. Observation that high hTERT mRNA expression may be related to shorter survival should prompt further investigation of the clinical significance of TA and its components in HG-NHL.

Adult↗

Novel proteasome inhibitor PS-341 inhibits activation of nuclear factor-kappa B, cell survival, tumor growth, and angiogenesis in squamous cell carcinoma.

We have shown that activation of nuclear factor-kappa B (NF-kappa B) promotes cell survival and expression of cytokines such as growth-regulated oncogene-alpha, which can modulate angiogenesis, growth, and metastasis of squamous cell carcinoma (SCC). Activation of NF-kappa B and cytoprotective genes in cancer may result from signal-induced phosphorylation and proteasome-dependent degradation of inhibitor-kappa B. In this study, we examined the effects of the novel proteasome inhibitor PS-341 on activation of NF-kappa B and cell survival, growth, and angiogenesis in murine and human SCC cell lines. PS-341 inhibited activation of NF-kappa B DNA binding and functional reporter activity at concentrations between 10(-8) and 10(-7) M. Cytotoxicity was observed at 10(-7) M in four murine and two human SCC lines, and followed early cleavage of poly(ADP-ribose) polymerase, a marker of caspase-mediated apoptosis. In vivo, PS-341 inhibited growth of murine and human SCC in mice at doses of 1--2 mg/kg given three times weekly, and dose-limiting toxicity was encountered at 2 mg/kg. Tumor growth inhibition was associated with a marked decrease in vessel density. PS-341 inhibited expression of the proangiogenic cytokines growth-regulated oncogene-alpha and vascular endothelial growth factor by SCC in the range at which PS-341 inhibits NF-kappa B. We conclude that PS-341 inhibits activation of NF-kappa B pathway components related to cell survival, tumor growth, and angiogenesis in SCC.

Animals↗

[Comparison of denaturing high performance liquid chromatography with direct sequencing in the detection of single nucleotide polymorphism].

OBJECTIVE: Investigate the sensitivity and accuracy of the denaturing high performance liquid chromatography(DHPLC) technique for the detection of single nucleotide polymorphism(SNP). METHODS: Forty-one samples were detected by both DHPLC and direct sequencing. RESULTS: The comparison demonstrated that DHPLC detected all heterozygous sequences found by direct sequencing. No false-positive signals were seen in the cases of homozygous sequences. Furthermore, no false-negative results were ever obtained with heterozygous mutations or polymorphisms, or both. CONCLUSION: DHPLC is a potent method for SNP identification especially SNP typing in large scale screening.

Chromatography, High Pressure Liquid↗

Imaging blood flow in human port-wine stain in situ and in real time using optical Doppler tomography.

BACKGROUND: Optical Doppler tomography (ODT) combines laser Doppler flowmetry with optical coherence tomography to obtain high-resolution images of blood flow in human skin in situ and in real time. OBSERVATIONS: We present a case in which ODT was used on a patient with a port-wine stain (PWS) birthmark to document the change of blood flow in response to laser therapy. It might be possible to use ODT blood flow measurements in situ to assist in assessing the efficacy of laser PWS therapy. If partial restoration of flow occurs immediately or shortly after laser exposure, indicative of reperfusion due to inadequate blood vessel injury, the PWS can be retreated using higher light dosages. Retreatment is continued until the measured Doppler shift is zero due to a permanent reduction in blood flow, indicative of irreversible microthrombus formation in the PWS vessels. CONCLUSIONS: We have demonstrated that ODT may be used for noninvasive imaging of blood vessels in PWS skin. Moreover, ODT will potentially allow laser therapy to be optimized on an individual patient basis by providing a fast, semiquantitative evaluation of the efficacy of PWS laser therapy in situ and in real time.

Humans↗

IL (interleukin)-1alpha promotes nuclear factor-kappaB and AP-1-induced IL-8 expression, cell survival, and proliferation in head and neck squamous cell carcinomas.

Interleukin 1alpha (IL-1alpha) is an important regulatory cytokine, the release of which after an injury can induce activation of transcription factors nuclear factor (NF)kappaB and activator protein (AP-1), which promote expression of genes involved in cell survival, proliferation, and angiogenesis. IL-1alpha is expressed autonomously by head and neck squamous cell carcinomas (HNSCCs) and a variety of other cancers, raising the possibility that IL-1alpha may serve as an autocrine factor that stimulates the activation of prosurvival transcription factors and target genes in cancer. In this study, we examined the role of IL-1alpha in the activation of NFkappaB and AP-1, the expression of proangiogenic cytokine IL-8, and in the survival and proliferation of HNSCC cell lines. HNSCCs were found to secrete and respond to functional IL-1alpha, in that culture supernatant from a high IL-1alpha-secreting line, UM-SCC-11B, could induce secretion of cytokine IL-8 by a low IL-1alpha-secreting line, UM-SCC-9; and the induction of IL-8 secretion could be blocked by the anti-IL-1alpha-neutralizing antibody or the IL-1 receptor antagonist (IL-1RA). Furthermore, IL-1alpha could induce the expression of IL-8 through an autocrine mechanism, in that transfection of UM-SCC-9 cells with a plasmid encoding IL-1alpha resulted in the increased coexpression of IL-1alpha and IL-8; whereas transfection with a plasmid encoding IL-1RA lacking the secretory leader sequence led to the decreased coexpression of IL-1alpha and IL-8. IL-1alpha was found to induce coexpression of IL-8 through the activation of NFkappaB and AP-1, in that mutation of the NFkappaB site within the IL-8 promoter abolished autocrine- and recombinant IL-1alpha-induced IL-8 reporter gene activity, whereas mutation in AP-1 partially decreased IL-8 reporter gene activity in UM-SCC-9 cells. Intracellular expression of IL-1RA decreased NFkappaB reporter gene activity, indicating that endogenously expressed IL-1alpha contributes to constitutive NFkappaB activation in this HNSCC line. Expression of IL-1alpha affected survival of UM-SCC-9, inasmuch as transfection of cells with plasmid encoding IL-1alpha or IL-1RA led to the increased or decreased survival of cells cotransfected with a beta-galactosidase reporter gene, respectively. IL-1alpha was also found to promote the increased growth of UM-SCC-9 cells in vitro. We demonstrate that exogenous and endogenous IL-1alpha contributes to the transcriptional activation of NFkappaB and AP-1, to the expression of IL-8, and to cell survival and the growth of HNSCC in vitro.

Carcinoma, Squamous Cell↗

[Purification and immobilization of the proteinase from mung bean burgeon inactivating soybean trypsin inhibitor].

By 30%-60% s(NH4)2SO4 fractional precipitation, anion-exchange chromatographs on DEAE-Sepharose CL-6B, gel filtration on Sephacryl S-200 and anion-exchange chromatographs on Waters AP-1 column(ProteinTm-Pak DEAE 15HR), a proteinase which can inactivated STI was purified from mung bean(Phaseolus aureus) burgeon. It was stable at temperatures lower than 50 degrees C and pH7.5-8.5, and the Km and Vmax of the proteinase for STI was 769.2 alpha-N-benzoyl-L-arginine ethyl ester(BAEE)/mL and 115.3BAEE/min/mL respectively. The molecular weight of the proteinase was estimated to be 29.8kD by SDS-PAGE. The proteinase immobilized by polyacrylamide was stable at temperatures lower than 60 degrees C and pH7.0-9.0, and the apparent Km* and Vmax* of the immobilized proteinase for STI was 1303.8 (BAEE)/mL and 94.34(BAEE)/min/mL respectively. The half-life of the immobilized proteinase was about 12 days at 4 degrees C.

Endopeptidases↗

18-Crown-6-Tetracarboxylic acid as a chiral additive for the simultaneous separation of o-, m- and p-enantiomers of phenylalanine family by capillary electrophoresis.

Simultaneous separation of 12 o-, m- and p-positional enantiomers of tyrosine and fluorophenylalanine has been achieved by the use of optically active 18-crown-6-tetracarboxylic acid (18C6H4) as an additive in the background electrolyte. It has been investigated that the separation conditions such as pH, electroosmotic flow, the concentration of 18C6H4 and applied voltages have critical influence on the simultaneous separation. Based on the information of electropherograms obtained, the interaction between the chiral selector and positional enantiomers has been discussed. It was shown that alpha-methyl group in the amino acid enantiomers make the resolution be reduced, and that o-, m- and p-substituents have an influence on the resolution.

Crown Ethers↗

[The apolipoprotein E gene polymorphism in children with steroid-resistant idiopathic nephrotic syndrome].

OBJECTIVE: To study apolipoprotein E gene polymorphism in children with steroid- resistant idiopathic nephrotic syndrome (SRINS). METHODS: Sixty children with SRINS (including 9 children with focalsclerosing glomerulonephritis) were observed in comparison with 80 age-sex-matched healthy children. Seven lipoprote in metabolism parameters including serum total-cholesterol(TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), apolipoprotein AI(apoAI), apolipoprotein B (apoB), lipoprotein (a)[Lp (a)] were detected by enzyme method, and single-strand conformation polymorphism(PCR-SSCP) was used to determine the apoE genotypes in the two groups. RESULTS: Serum TC, TG, HDL-C, LDL-C, apoAI, apoB, Lp(a) in the observation group were significantly higher than those in the healthy controls (P<0.01). After 6 months, the levels of serum TC, TG, LDL-C,apoB,Lp(a) were 81.25%, 78.13%, 84.38%, 87.50% and 78.13% respectively in 32 SRINS cases of the observation group. The apo epsilon 2 allele gene frequence was higher in the observation group than in the controls (11.66% vs 5.00%, P<0.05). The apo apsilon 2 allele gene frequence in the cases of focalsclerosing glomerulonephritis was significantly higher than that in the controls (22.22% vs 5.00%, P<0.01). CONCLUSION: The above results indicate the obvious and long term abnormalities of serum lipoprotein metabolism in the children with SRINS. The apo apsilon 2 allele gene frequence is higher in the children with SRINS. There are risk factors for atherosclerosis and cardiovascular diseases in the children with SRINS. The antilipemic drugs should be considered in use for the children with SRINS.

Apolipoprotein A-I↗

[A simple and rapid new method for SNP typing by single-tube bi-directional allele specific amplification].

OBJECTIVE: To establish a new method for single nucleotide polymorphism(SNP) typing based on allele specific PCR: single-tube bi-directional amplification (SB-ASA), and study the influence on specific extension by introducing a mismatch at the third 3'terminal base of allele specific primers. METHODS: Two allele specific primers, with a mismatch introduced at the third 3'terminal base, were both included in PCR system; they extended in opposite directions and amplified two allele specific fragments different in size. The genotype was determined by observing the length of amplified fragments after agarose electrophoresis. The proper ranges of annealing temperature (Ta) under which primers can specifically extend were achieved by observing the amplification status at different temperatures. RESULTS: SB-ASA was successfully used to type 36 samples for four different kinds of SNPs. Typing results were completely consistent with those by directional sequencing. Proper Ta ranges of two primers were expanded respectively from 64-69 degrees centigrade to 46-66 degrees centigrade and from 60-62 degrees centigrade to 56-61 degrees centigrade by introducing a mismatch at the third 3'terminal base. CONCLUSION: SB-ASA is a simple, rapid and efficient new method for SNP typing. During allele specific PCR reaction, specific primers with a mismatch at the third 3'terminal base have more power to identify two alleles.

Alleles↗

Isolation, purification and N-terminal sequencing of a bioactive peptide that alters action potentials from the venom of Buthus martensii Karsch.

A bioactive peptide that extensively prolongs action potentials (APs) in frog nerve has been isolated and purified from the venom of the scorpion Buthus martensii Karsch (BMK). The peptide, designated as BMK 18(2), was purified using gel filtration, ion exchange, FPLC, and HPLC chromatography. APs recorded in the presence of nanomolar concentrations of the peptide were extensively prolonged with some attenuation in their heights. The N-terminal sequence of BMK 18(2) was found to be: VRDAYIAEDYD-VYH-ARDA. Sequence similarity comparisons to other alpha-scorpion toxins suggest that the two blanks in the sequences are cysteines. The molecular weight (M.W.) of BMK 18(2) was determined by LC/MS/MS to be 7185 Da. Since the peptide prolongs APs when both K+ and Ca++ channels were blocked and shows sequence similarity to other alpha-neurotoxins, it appears likely that BMK 18(2) acts to alter Na channel inactivation to produce its effect.

Action Potentials↗

[Overexpression of artificial synthetic gene of Aspergillus niger NRRL3135 phytase in Pichia pastoris].

The phytase gene of Aspergillus niger NRRL3135 was modified with a deletion of intron and signal coding sequence. Then, according to the codon preference of Pichia pastoris, modified phyA gene was artificially synthesized and cloned into expression vector of pPICZ alpha A. The recombinant plasmid was transformed into chromosome of Pichia pastoris X-33 strain by electroporation. The results of SDS-PAGE and enzymatic kinetic analysis proved that the recombinant phytase was secreted into culture medium with nearly same character of natural phytase. After screening for high level productive yeast strains, a strain named SPAN-III produced recombinant phytase with 165,000 u/mL under the condition of shake cultivation. It will satisfy the demand for industrialized production in some degree.

6-Phytase↗

Biphasic urethral sphincter responses to acetic acid infusion into the lower urinary tract in anesthetized cats.

PURPOSE: Varying the concentration of infused acetic acid produced bladder irritation and dose dependent increases in external urethral sphincter electromyography activity in cats. We further characterized acetic acid induced external urethral sphincter electromyography activity in intact and acute spinal cord injured animals. MATERIALS AND METHODS: Bladder cystometrography and external urethral sphincter electromyography were continuously recorded in chloralose anesthetized cats. Dilute 0.05% to 0.8% acetic acid was infused into the lower urinary tract through the bladder dome. Intravesical or intraurethral infusion was performed separately in bladder neck ligated preparations. In some animals the spinal cord was transected at L1 to L2 2 to 8 hours before the study. RESULTS: Acetic acid infusion into the lower urinary tract elicited dose dependent increases in tonic external urethral sphincter activity. However, a prolonged infusion of 0.7% to 0.8% acetic acid usually inhibited external urethral sphincter activity. The excitatory external urethral sphincter response was elicited by intraurethral but not by intravesical infusion. This response remained in acute spinal cord injured animals. The inhibition of tonic external urethral sphincter activity during 0.7% to 0.8% acetic acid infusion was observed when there was extreme bladder irritation characterized by continual contractions. Induced tonic external urethral sphincter activity was attenuated by intrathecal administration of prazosin or scopolamine and abolished by hexamethonium. CONCLUSIONS: Acetic acid infusion into the lower urinary tract elicits biphasic external urethral sphincter responses. The early excitatory response is a spinal urethrourethral reflex and the late inhibitory phase results from negative vesicourethral feedback control. Spinal muscarinic cholinergic and alpha-adrenergic receptors are involved in acetic acid induced excitatory external urethral sphincter responses.

Acetic Acid↗

[Chromosomal aberration analyzed by comparative genomic hybridization in nasopharyngeal carcinoma].

OBJECTIVE: To identify genetic alteration in primary sporadic nasopharyngeal carcinoma(NPC) in Hunan. METHODS: Comparative genomic hybridization was applied to investigate the genomic imbalance in a series of 20 cases of primary nasopharyngeal carcinomas. RESULTS: The common chromosomal alterations included gains of chromosomes 1q, 2, 3q, 7q,8q,12 as well as losses of chromosomes 3p, 9p, 11q, 16q. CONCLUSION: There are multiple regions of chromosomes with copy number changes in NPC. The tumor suppressor genes and oncogenes on these regions may be involved in the development and progress of nasopharyngeal carcinoma.

Chromosome Aberrations↗

[The association between SA gene and essential hypertension in Han Chinese].

OBJECTIVE: To evaluate the linkage of SA gene locus to essential hypertension(EH) in affected Han Chinese sib pairs and to ascertain the association of SA gene CT79 polymorphism with essential hypertension in Han Chinese hypertensives. METHODS: In Han Chinese at Shanghai, 96 random individuals, 80 essentially hypertensive sib pairs with hypertensive family history, 200 essential hypertensives with hypertensive family history and 200 normotensive control(NC) subjects without such family history were enrolled in these serial studies. MF-PCR-SSCP technique was applied to detect the frequency distributions of SA gene microsatellite D16S3046, D16S3136 and D16S3068. The linkage of SA gene locus to essential hypertension was analyzed by Green's IBS for affected siblings. SA gene variant was screened by PCR-SSCP- silver staining and confirmed by DNA sequencing, then an association study was performed to determine whether such variant was associated with essential hypertension. RESULTS: The frequency distributions of SA gene microsatellites D16S3046, D16S3136 and D16S3068 were of high polymorphism. The polymorphism information contents of D16S3046, D16S3136 and D16S3068 were 0.86, 0.82 and 0.80, and the heterozygosities 0.88, 0.71 and 0.77. The linkage of SA gene locus to essential hypertension was not observed; the linkage analysis t values of D16S3046,D16S3136 and D16S3068 were 0.972, 0.622 and 0.236, and the P values 0.384, 0.543 and 0.871, respectively. The C two head right arrow T substitution was confirmed, but there was no association of such variant with essential hypertension. The frequency distributions of genotypes and alleles in the hypertensive group were not significantly different from those in the normotensive group (P>0.05). CONCLUSION: SA gene is not linked to or associated with essential hypertension in Han Chinese. SA gene may not be a susceptible gene contributing to the development of essential hypertension in Han Chinese.

Adult↗