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Biomedical subjects

Z Wen

Publications and source records attributed to Z Wen.

At least 37 records · Page 2Linked to original sources
PubMed2001

Cytochrome P450 CYP6L1 is specifically expressed in the reproductive tissues of adult male German cockroaches, Blattella germanica (L.).

A full-length cDNA encoding a new cytochrome P450, CYP6L1, was cloned from German cockroaches, Blattella germanica. CYP6L1 has an open reading frame of 1509 nucleotides with a deduced protein of 503 amino acids and molecular mass of 57 Kd. CYP6L1 is most similar to CYP6H1, a putative ecdysone 20-hydroxylase from Locusta migratoria. CYP6L1 mRNA was not detected in embryos nor nymphs, nor in adult females. CYP6L1 mRNA was detected only in the testes and accessory glands of male adult German cockroaches. Given that the testes and accessory glands are the most important components of the reproductive system in male insects, the expression of CYP6L1 mRNA exclusively in these tissues strongly suggests that CYP6L1 has a role in reproduction. Possible substrates for CYP6L1 are discussed.

Amino Acid Sequence↗
PubMed2001

Truly hybrid interventional MR/X-ray system: investigation of in vivo applications.

RATIONALE AND OBJECTIVES: The purpose of this study was to provide in vivo demonstrations of the functionality of a truly hybrid interventional x-ray/magnetic resonance (MR) system. MATERIALS AND METHODS: A digital flat-panel x-ray system (1,024(2) array of 200 microm pixels, 30 frames per second) was integrated into an interventional 0.5-T magnet. The hybrid system is capable of MR and x-ray imaging of the same field of view without patient movement. Two intravascular procedures were performed in a 22-kg porcine model: placement of a transjugular intrahepatic portosystemic shunt (TIPS) (x-ray-guided catheterization of the hepatic vein, MR fluoroscopy-guided portal puncture, and x-ray-guided stent placement) and mock chemoembolization (x-ray-guided subselective catheterization of a renal artery branch and MR evaluation of perfused volume). RESULTS: The resolution and frame rate of the x-ray fluoroscopy images were sufficient to visualize and place devices, including nitinol guidewires (0.016-0.035-inch diameter) and stents and a 2.3-F catheter. Fifth-order branches of the renal artery could be seen. The quality of both real-time (3.5 frames per second) and standard MR images was not affected by the x-ray system. During MR-guided TIPS placement, the trocar and the portal vein could be easily visualized, allowing successful puncture from hepatic to portal vein. CONCLUSION: Switching back and forth between x-ray and MR imaging modalities without requiring movement of the patient was demonstrated. The integrated nature of the system could be especially beneficial when x-ray and MR image guidance are used iteratively.

Animals↗
PubMed2001

Cloning of two novel P450 cDNAs from German cockroaches, Blattella germanica (L.): CYP6K1 and CYP6J1.

Two novel P450 cDNAs, CYP6K1 and CYP6J1, were isolated from German cockroaches, Blattella germanica (L). Both CYP6K1 and CYP6J1 are typical microsomal P450s and their deduced amino acid sequences share a number of common characteristics with other members of the P450 superfamily. Both CYP6K1 and CYP6J1 showed the highest per cent identity (based on the deduced amino acid sequence) to CYP6L1 from B. germanica and CYP6H1, a putative ecdysone 20-hydroxylase from Locusta migratoria. Using a CYP6K1 probe, two mRNA signals (~2.5 and ~2.1 kb) were detected in all life stages. Both signals were just detectable in the eggs and became stronger in later instars. The strongest signals were detected in the fifth and sixth instars as well as in adults. These two bands were also detected in the abdomens and in the remainder of bodies of both male and female adults. Southern blots suggest the two mRNA bands detected in the Northern blot might be a result of alternative splicing. No signal could be detected at any life stage using the CYP6J1 probe, suggesting that CYP6J1 was expressed at a low level.

Amino Acid Sequence↗
PubMed2001

Photoaffinity labeling of insect nicotinic acetylcholine receptors with a novel [(3)H]azidoneonicotinoid.

The nicotinic acetylcholine receptor (nAChR) is a ligand-gated ion channel in the insect CNS and a target for major insecticides. Here we use photoaffinity labeling to approach the functional architecture of insect nAChRs. Two candidate 5-azido-6-chloropyridin-3-yl photoaffinity probes are evaluated for their receptor potencies: azidoneonicotinoid (AzNN) with an acyclic nitroguanidine moiety; azidodehydrothiacloprid. Compared to their non-azido parents, both probes are of decreased potencies at Drosophila (fruit fly) and Musca (housefly) receptors but AzNN retains full potency at the Myzus (aphid) receptor. [(3)H]AzNN was therefore radiosynthesized at high specific activity (84 Ci/mmol) as a novel photoaffinity probe. [(3)H]AzNN binds to a single high-affinity site in Myzus that is competitively inhibited by imidacloprid and nicotine and further characterized as to its pharmacological profile with various nicotinic ligands. [(3)H]AzNN photoaffinity labeling of Myzus and Homalodisca (leafhopper) detects a single radiolabeled peak in each case displaceable with imidacloprid and nicotine and with molecular masses corresponding to approximately 45 and approximately 56 kDa, respectively. The photoaffinity-labeled receptor in both Drosophila and Musca has imidacloprid- and nicotine-sensitive profiles and migrates at approximately 66 kDa. These photoaffinity-labeled polypeptides are considered to be the insecticide-binding subunits of native insect nAChRs.

Animals↗
PubMed2001

[Effect of radiation with 60Co on RBC membrane elastic shear modulus and membrane viscosity].

RBC membrane shear elastic modulus and membrane viscosity are two important indexes reflecting RBC membrane viscoelasticity. Their variation was investigated in this study after rabbits were radiated with 60Co. With a new ektacytometer, we measured the small deformation index (DId) and the half-time of deformation relaxation (t0.5) of RBC in flow field then we calculated RBC membrane shear elastic modulus and membrane viscosity. We found that the value of RBC membrane shear elastic modulus and membrane viscosity continuously increased from 0 to 16th day then continuously decreased and tended to be stable on 60th day or so. The reason may lie in the variation of proportion of new and old RBC in blood and variation of microconformation of RBC membrane after rabbits were radiated with 60Co.

Animals↗
PubMed2001

[Effects of the alterations of membrane shear elastic modulus and viscosity on the deformation and orientation of RBCs].

Neuraminidase can partly remove the surface charge of RBCs through a biochemical interaction; thus it can give rise to alterations in the microstructure of membrane, the shear elastic modulus (E) and the viscosity(micron) of membrane. Changing the time of treatment and the dose of neuraminidase and using a new ektacytometry that can separate deformation index DI into orientation index (DI)or and small deformation index (DI)d for RBCs in shear flow field of low viscosity, we measured (DI)d and the half time t0.5 when the DI recovered to half of the maximum in the process of relaxation for every treated sample. (DI)d and t0.5 were put respectively into the RBC membrane shear elastic modulus formula and the membrane viscosity formula which were put forward by Wen Zong-yao and Yan Zong-yi et al[1]. The rules of the alterations of E and micron were obtained. We also measured DI and (DI)or. It was found that E and micron increased greatly but DI and (DI)or decreased when the dose of neuraminidase and the time of treatment were increased. There was a contrary correlation between them. These data demonstrated that the increase of E and micron weakened the deformability and the ability of orientation of RBCs.

Animals↗
PubMed2001

Effect of 60Co irradiation on characteristics of hemorheology in rabbits.

A high-dose (7 Gy) whole-body 60Co irradiation for a short period caused disturbances of hematopoietic function. A decrease in the hematocrit of the circulating blood lasted for about 15 days, thus forming an anemic animal model. We studied the influence of high-dose 60Co irradiation on hemorheologic parameters: percentage of reticulocytes, RBC deformability, sedimentation rate and plasma fibrinogen concentration in the rabbit. It was found that the plasma fibrinogen concentration increased to twice more than control level and that percentage of reticulocytes in circulation disappeared immediately after irradiation. The deformation index of RBCs in shear flow decreased from a value of 58% down to a value of 42% in the first two weeks and gradually returned to control levels about 40 days after 60Co irradiation. Our results showed that a short period of high-dose 60Co irradiation caused severe and relatively long-lasting damage of hematopoietic system in animals' body.

Animals↗
PubMed2001

[A summary description of development in immunosensor].

In this review, an introduction to the concept and fundamental principles of immunosensor is given, and immunosensor is classified into many types according to the difference of transducers, each type being compared with others and explicated in derivation and developing process respectively. Two problems about the fabrication of immunosensor, which are immobilization and reproductivity, are addressed fleetly. In addition, the application and developing tendency of immunosensor are described briefly.

Biosensing Techniques↗
PubMed2001

[Association between apolipoprotein E polymorphism and Alzheimer's disease: A population-based study in Guangzhou, China].

OBJECTIVE: To investigate the distribution of apolipoprotein E (apoE) genotype of patients with Alzheimer's disease (AD) in the population aged 75 and older in Guangzhou and to determine whether there was an association between AD and apoE epsilon4 allele. METHODS: A systematic cluster sampling design, two-stage screening and field evaluations were used in a cross-sectional population-based study. Three thousand eight handred and twenty-five subjects aged 75 and above in Liwan district of Guangzhou were interviewed. Blood samples were collected from 110 cases and 518 normal controls. The criteria of DSM-III-R and NINCDS-ADRDA were used for clinical diagnosis of probable AD. Polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) were used to determine apoE genotypes. RESULTS: There were 190 cases diagnosed as sporadic AD from this sample. The frequencies of the three apoE alleles were detected as follows: epsilon2 = 0.100, epsilon3 = 0.832, epsilon4 = 0.068 in AD patients; epsilon2 = 0.092, epsilon3 = 0.843, epsilon4 = 0.065 in normal controls. The frequencies of apoE genotype and allele in the AD patients were not significantly different from that in normal subjects (P > 0.05). CONCLUSION: No association between sporadic AD and apoE epsilon4 allele was found among the population aged 75 and above in Liwan district of Guangzhou.

Aged↗
PubMed2000

Pleural lavage cytology in esophageal cancer without pleural effusions: clinicopathologic analysis.

OBJECTIVE: The literature of pleural lavage cytology (PLC) is focused on lung cancer. We conducted this pilot study to determine the incidence of malignant pleural cytologies in patients without pleural effusions who undergo curative resection for esophageal cancer, and to evaluate the clinicopathologic significance of positive cytology. METHODS: Forty-eight patients underwent esophagectomy for thoracic esophageal cancer in our unit from January 1998 to January 1999. After thoracotomy, pleural lavage was performed before any intrathoracic manipulation and cytologically evaluated. RESULTS: There was one patient with stage I, 27 patients with stage II, and 20 patients with stage III cancer of the thoracic esophagus. The mean age was 55 years (range 41-77 years). Fifteen cases (31.3%) were found to have positive lymph nodes (N1). Squamous cell carcinoma was the dominant histopathologic type (91.7%). Positive lavage cytology in the whole group was found in 18.8% (9/48). There was no significant correlation to gender, age, clinical symptoms, histology, T or N status, TNM stage, or tumor location. CONCLUSIONS: The incidence of positive pleural lavage cytology in esophageal cancer is disconcertingly high. Positive cytology might suggest a more aggressive tumor biology. Future studies on its relation to survival and occult lymphatic metastasis are warranted.

Adult↗
PubMed2000

A study of hemorheological behaviour for patients with Alzheimer's disease at the early stages.

To evaluate the change of hemorheological indexes for patients with Alzheimer's disease (AD) at the early stages and to discuss effects of these changes on AD, high shear value of whole blood viscosity (etabh), reduced high shear value of whole blood viscosity (retabh), low shear value of whole blood viscosity (etabl), reduced low shear, value of whole blood viscosity (retabl), KT value of whole blood viscosity, hematocrit (HCT) and blood plasma viscosity (etaP) were measured in 31 patients with probable AD at the early stages and 33 age-matched healthy subjects. There were significant differences of all hemorheological indexes between AD group and control group except HCT. Step discriminant analysis revealed 81.25% of overall group-classified accuracy in a hemorheological discriminant function consisting of etabl, retabl, retabh and HCT. Significant difference of hemorheological indexes existed between AD and age-matched healthy control subjects. The results showed that measurement of hemorheological indexes could be used as one of reference standards of diagnosis in AD.

Aged↗
PubMed2000

Influence of neuraminidase on the characteristics of microrheology of red blood cells.

Surface charge was removed from RBC (erythrocyte) membrane to different degrees with biochemical methods, i.e., treatment of RBCs with neuraminidase, either using different doses for the same incubation time (1 hour) or using the same dose (75 milli-unit) for different incubation time. Several rheological properties of the RBCs with surface charge removal were observed, including the deformation index DI (using traditional ektacytometry) orientation index (DI)or and small deformation index (Dl)d (using new ektacytometry), the viscosity at low and high shear rates (using a cone-plate rotating viscosimeter). In addition, photographs of RBCs aggregation under a microscope and the histograms of RBC aggregate size after treatment with neuraminidase were obtained. It is found from these experiments that the decrease of the surface charge of RBCs leads to the decrease in the deformation and orientation indices as well as the increase in blood viscosity.

Animals↗
PubMed2000

[Expression of telomerase and its RNA in nasopharyngeal carcinoma].

OBJECTIVE: To study the activity of telomerase and the expression of its RNA in nasopharyneal carcinoma (NPC) and HNE1 cell lines of NPC. METHODS: Telomerase activity was detected with telomeric repeat amplification protocol (TRAP) PCR ELISA kit in 41 cases of NPC, 14 cases of tissues adjacent to the carcinoma, and 19 cases of chronic nasopharyngitis, HNE1 cell lines of NPC, HL60 cell lines of leukemia, TUL1 cell lines of lung cancer, as well as three other kinds of normal control cells. The sensitivity and specificity of telomerase assay were also analyzed. Moreover, the expression of human telomerase RNA (hTR) was studied in 27 cases of NPC, 19 cases of adjacent nasopharyngeal tissues, and 17 cases of control groups by RT-nested PCR. RESULTS: The telomerase activity was found increased in NPC and in tissues adjacent to NPC with absorbance value (A value) of 1.15 U +/- 0.78 U and 1.04 U +/- 0.67 U respectively, compared with chronic nasopharyngitis (A = 0.18 U +/- 0.09 U). In NPC with cervical lymphnodes involvement the telomerase activity (A = 1.25 U +/- 0.79 U) was higher than in those without involvement (A = 1.02 U +/- 0.71 U), P < 0.05. The telomerase activity was also observed in HNE1 cell lines (A = 1.26 U +/- 0.97 U) and in other two kinds of cancer cell lines, but not in the three kinds of normal control cells. By contrast, no significant difference was seen in the expression of hTR among the three nasopharyngeal biopsy groups (P > 0.05). Finally, the sensitivity of telomerase assay was high (at an amount of 10(2) HNE1 cells), and the specificity was also high (after inactivation by heat or RNase, the telomerase activity was very low). CONCLUSIONS: A high frequency of telomerase activity is commonly seen in NPC, adjacent nasopharyngeal tissues, and HNE1 cell lines and is closely associated with NPC with cervical lymphnodes involvement. Both sensitivity and specificity of the telomerase assay are high. However, owing to the fact that the expression of hTR has no obvious difference between NPC and normal tissues and does not always correspond with the telomerase activity, it would be better to do TRAP as well as hTR assays for the activity and expression in assessing the carcinogenesis of NPC. So, more intensive study on the role of hTR in the carcinogenesis of NPC and on the exact relationship between hTR and telomerase is needed.

Adult↗
PubMed2000

[Preliminary clinical comparison of HLF and ELF regimen in the treatment of advanced gastric carcinoma in middle-aged and elderly patients].

OBJECTIVE: To observe the therapeutic effects and toxicity of HLF (hydroxycamptothecin HCPT/leucovorin LV/fluorouracil 5-Fu) regimen and ELF (etoposide VP-16/LV/5-Fu) regimen in middle-aged and elderly patients with advanced gastric carcinoma. METHODS: A group of twenty-five cases were treated with HLF regimen, and the other group of 23 cases were treated with ELF regimen. RESULTS: Of the 25 cases treated with HLF regimen, there was no complete remission (CR), but there were 12 partial response (PR), 11 no response (NC), and 2 had progressive disease (PD). The response rate (RR) was 48.0%. Of the 23 patients treated with ELF regimen, there was no CR, there were 9 PR, 11 NC, and 3 PD. The RR was 39.1% (P > 0.05). The main toxicity was myelosuppression and stomatocace. Grade III-IV stomatocace in HLF regimen group (68.0%) was more commonly seen than that in ELF regimen group (39.1%, P < 0.05). There was no cardiac or renal toxicity observed. CONCLUSION: HLF regimen is promising for treatment of advanced gastric carcinoma in middle-aged and elderly patients with the merits of low toxicity affecting heart, kidney and bladder except stomatocace, which is worthy of further clinical trial.

Aged↗
PubMed1999

House-fly cytochrome P450 CYP6D1: 5' flanking sequences and comparison of alleles.

CYP6D1 is a cytochrome P450 found in the house fly, Musca domestica. Expression is greater in pyrethroid-resistant vs. -susceptible strains and can be induced by phenobarbital in adult susceptible flies. CYP6D1 is expressed only in adult flies. To gain information about possible regulatory elements involved in CYP6D1 expression, and to confirm the gene sequence that was previously determined by polymerase chain reaction (PCR), we screened a house-fly library prepared with genomic DNA from the pyrethroid-resistant LPR strain. A CYP6D1v1 clone was isolated and sequenced. This clone contained 887 nucleotides 5' to the open reading frame and a previously unknown 2.4-kb intron. Using polymerase chain reaction with primers based on the CYP6D1v1 allele, the sequences 5' to the ORF were obtained from five pyrethroid susceptible strains. The transcription initiation site (TIS) was identified at the same position in LPR and two susceptible strains (86 nucleotides upstream from the translation start site). A comparison of the 5' flanking sequences revealed a high degree of similarity for most regions, although differences in the sequences were identified. The possible roles of these sequence differences in regulation of CYP6D1 expression are discussed.

Alleles↗
PubMed1999

The linker domain of Stat1 is required for gamma interferon-driven transcription.

Upon binding of gamma interferon (IFN-gamma) to its receptor, the latent transcription factor Stat1 becomes phosphorylated, dimerizes, and enters the nucleus to activate transcription. In response to IFN-alpha, Stat1 binds to Stat2 in a heterodimer that recruits p48, an IRF family member, to activate transcription. A number of functional domains of the STATs, including a C-terminal transactivation domain, a dimerization domain, and an SH2 domain, are known. However, the highly conserved residues between the DNA binding and SH2 domains (463 to 566), recently christened the linker domain on the basis of crystallographic studies, have remained without a known function. In the present study, we report that KE544-545AA point mutants in Stat1 abolish transcriptional responses to IFN-gamma but not to IFN-alpha. We further show that this mutant Stat1 undergoes normal phosphorylation, nuclear translocation, and DNA binding. Taken together with recent structural evidence, these results suggest that the linker domain acts as a critical contact point during the construction of a Stat1-driven transcriptional complex.

Amino Acid Sequence↗
PubMed1999

A quantitative MR study of the hippocampal formation, the amygdala, and the temporal horn of the lateral ventricle in healthy subjects 40 to 90 years of age.

BACKGROUND AND PURPOSE: Several investigators have defined normal age-specific values for the medial temporal lobe structures in neurologically normal elderly subjects, but, to our knowledge, no one has reported those values for a large sample of healthy volunteers. The purpose of our study was to define normal age-specific values for the hippocampal formation, the amygdala, and the temporal horn of the lateral ventricle by age group, ranging from 40 to 90 years, in order to generate a guideline for the quantitative MR diagnosis and differential diagnosis for early Alzheimer disease. METHODS: MR-based volumetric measurements of the hippocampal formation, the amygdala, and the temporal horn, standardized by total intracranial volume, were obtained from oblique coronal and sagittal T1-weighted MR images in 619 healthy volunteers and two cadaveric specimens. RESULTS: Differences in standardized volumes of the hippocampal formation, the amygdala, and the temporal horn were significant among the 61- to 70-year-old, 71- to 80-year-old, and 81- to 90-year-old groups, and were not significant between the 40- to 50-year-old and 51- to 60-year-old groups. We found no significant differences in side or sex among the age groups for any of the structures. CONCLUSION: Differences in the mean value and in the 95% normal range of standardized volumes of the hippocampal formation, the amygdala, and the temporal horn correspond to differences in age among healthy subjects; therefore, age should be considered a factor in correlative research, especially in that involving patients in the early stages of Alzheimer disease.

Adult↗