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Biomedical subjects

Yan Zhang

Publications and source records attributed to Yan Zhang.

At least 541 records · Page 30Linked to original sources
PubMed2002

[Matrine affects early expression of proto-oncogenes in K562 cells].

BACKGROUND & OBJECTIVE: It has been reported that matrine had the anti-tumor activity, and our previous study have provided that matrine had the effects of inhibiting proliferation and inducing differentiation in K562 cell line, but its molecular mechanism is unknown yet. METHOD: The expression of several proto-oncogenes(c-myc, c-jun, H-ras, p21, and HNF-1 alpha) in K562 cell line treated by 0.2 mg/ml matrine were measured by RT-PCR. RESULT: The c-myc, c-jun, and HNF-1 alpha mRNA of K562 cells treated by 0.2 mg/ml matrine were dramatically decreased at the early stage (3 h), while the H-ras and p21 mRNA were increased obviously at the same time. CONCLUSION: The changes of several proto-oncogenes in K562 cells treated by 0.2 mg/ml matrine may be related to inhibiting proliferation and inducing differentiation.

Alkaloids↗
PubMed2002

[Preparation of phage-displayed single chain variable fragments of monoclonal antibody MC5 recognizing colorectal carcinoma].

BACKGROUND & OBJECTIVE: MC5 is a murine monoclonal antibody with a good specificity to human colorectal carcinoma and smaller murine antibody can significantly decrease the possibility of developing human antimouse antibody response in vivo study. The aim of this study was to prepare single chain variable fragments (ScFv) of MC5. METHODS: mRNA was isolated from the hybridoma cell line producing MC5, and the DNAs encoding variable domains of heavy and light chains(VH and VL DNAs) of the antibody were amplified separately by RT-PCR and assembled into ScFv DNAs with a linker DNA. The ScFv DNAs were ligated into the phagemid vector pCANTAB5E and the ligated sample was transformed into E. coli TG1. The transformed cells were infected with M13KO7 helper phage to yield recombinant phage antibody ScFvs. After two rounds of panning with cell line SW480 highly expressing MC5-binding antigen, the phage clones displayed ScFv fragments of the antibody were selected by ELISA, and the affinity of the positive phage clones was assayed by competition ELISA. RESULTS: The VH, VL, and ScFv DNAs were about 340 bp, 320 bp, and 750 bp, respectively. Ten phage clones displayed ScFv of MC5 were selected from 25 enriched phage clones, and 3 of the 10 phage clones had higher affinity of binding to the antigen. CONCLUSION: The phage-displayed ScFv fragments of monoclonal antibody MC5 are successfully produced by phage display technique, which may provide a way for broadening the application range of the antibody.

Animals↗
PubMed2002

[Effect of antisense oligonucleotide against telomerase in rat spermatogonia and its reactivity to cytokine].

OBJECTIVES: To study the change of telomerase activity in rat spermatogonia when the telomerase RNA was enclosed, and reactivity of the change to cytokine(SCF, TGF-beta 1). METHODS: The antisense oligonucleotides(PS-ASON) of telomerase was transfected into proliferating spermatogonia in vitro with the liposomes as the vector. Then the cytokine, stem cell factor (SCF) or transforming growth factor-beta 1(TGF-beta 1), was added. The proliferative activity of the spermatogonia was determined before and after the inhibition by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide]assay. The change of telomerase activity was detected by telomeric repeat amplification protocol (TRAP). RESULTS: 1 mumol/L PS-ASON obviously downregulated the telomerase activity and inhibited spermatogonia proliferation. When the inhibition was over, the activity recovered to some extent(P < 0.01). Growth factors can regulate the spermatogonia after inhibition, SCF may improve the activity of telomerase and the proliferation of spermatogonia. Adversely, TGF-beta 1 may inhibit the recovery of telomerase activity. CONCLUSIONS: To inhibit spermatogonia telomerase activity antisensely can limit the proliferation of spermatogonia efficiently, which was regulated by cytokine. This method might be a new and efficient way in male birth control.

Animals↗
PubMed2002

[Effects of fluvastatin on the levels of C-reactive protein and lipids in patients with hyperlipidemia].

OBJECTIVE: To observe the changes of C-reactive protein (CRP) level and its relationship with blood lipids, and the effects of fluvastatin on CRP and the lipids in patients with hyperlipidemia. METHODS: Serum levels of cholesterol (TC), triglycerides (TG), high density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), very-low-density lipoprotein cholesterol (VLDL-C) and lipoprotein(a)[Lp(a)] were measured by enzyme assay, and plasma CRP level by immunonephelometry before and after fluvastatin treatment (20 mg/d for 4 weeks) in patients with hyperlipidemia. RESULTS: CRP levels were above normal in 90.3% hyperlipidemia cases in spite of the various accompanying diseases. Fluvastatin treatment significantly reduced TC (-7.49%), TG (-14.32%), LDL (-13.88%), VLDL (-18.48%) and TC/HDL(-13.50%) levels (P<0.01), and also brought down Lp(a) concentration (-13.81%). CRP levels was very effectively reduced after the treatment (-15.92%, P<0.001). No association between basal CRP levels and basal lipids and Lp(a) concentrations was observed. Positive correlation of CRP, however, was observed after fluvastatin treatment with TC/HDL (r=0.62, P=0.041) and Lp(a) (r=0.320, P=0.011), while inverse relations were noted between CRP and HDL (r=-0.288, P=0.023). CONCLUSION: CRP levels increases markedly in patients with hyperlipidemia, a fact that is independent of the accompanying diseases. In addition to modulating blood lipid levels, fluvastatin also reduces CRP level, the latter possibly serving as an independent predictive factor for atherosclerotic cardiovascular diseases and also as an indicator for estimating the effectiveness of the treatment.

Adult↗
PubMed2002

[A quantitative assay for telomerase activity in peripheral blood mononuclear cells from patients with acute leukemia].

To establish a quantitative assay for telomerase activity and analyze the telomerase activity in peripheral blood mononuclear cells (PBMNC) from patients with acute leukemia, a fluorescent dye, PicoGreen, was added to the products after telomere repeat amplification protocol. The samples were excited at 480 nm and the fluorescence emission intensity was measured at 520 nm using a spectrofluorometer. Telomerase activity was detected in PBMNCs from 20 cases of normal individuals and 25 patients with acute leukemia. The results showed that the fluorescence of PicoGreen binding to double-stranded DNA specifically was enhanced with increase of DNA quantities. In conclusion, the met hod is rapid, simple and quantitative, the telomerase activities of PBMNCs from acute leukemia patients are significantly higher than that of the normal controls.

Acute Disease↗
PubMed2002

[Effects of matrine on the activity of protein tyrosine kinase and phosphatase in K562 cells].

BACKGROUND & OBJECTIVE: The differentiation of K562 cells can be induced by a given concentration of matrine. This study was designed to investigate the mechanism of signal transduction in induced differentiation of K562 cells. METHODS: ELISA coupled with streptavidin-biotin system was used to dynamically detect the activity of protein tyrosine kinase and phosphatase in the cytoplasm and the membrane of K562 cells treated by matrine. RESULTS: Matrine inhibited the activity of protein tyrosine kinase in K562 cells, and the inhibitive effect depended on matrine of the concentration within 0.1 mg/ml. The effects of different concentration of matrine on the protein tyrosine phosphatase activity had no significant difference. Activity of the protein tyrosine phosphatase decreased transiently accompanied with the activity of the protein tyrosine kinase in K562 cells treated with 0.1 mg/ml matrine. CONCLUSIONS: The change of protein tyrosine kinase activity is involved in the differentiation of K562 cells induced by matrine. The tyrosine kinase activity in cell membrane decreased more rapidly than that in cell cytoplasm, suggesting there be a transmembrane signal transduction. The change of tyrosine phosphatase activity following the kinase indicates the real time regulation of phosphorylation and dephosphorylation. Moreover, the inhibitory effect of matrine on the protein tyrosine kinase shows the characters of specificity and saturation, suggesting the exist of matrine-associated receptor in K562 cells.

Alkaloids↗
PubMed2002

[Antagonistic effect of hydroxysafflor yellow A on the platelet activating factor receptor].

AIM: To observe the antagonistic effect of hydroxysafflor yellow A (HSYA) on the platelet activating factor (PAF). METHODS: Washed rabbit platelet (WRP) aggregation and rabbit polymorphonuclear leukocytes (PMNs) aggregation induced by PAF were observed by turbidimetric assay in vitro. The PAF receptor antagonistic effect of HSYA was investigated by radio ligand binding assay (RLBA). RESULTS: In RLBA the specific binding inhibition effect of HSYA was found to be concentration-dependent in three different [3H]PAF concentrations. In the experiments, WRP aggregation and rabbit PMNs aggregation induced by PAF (9.55 x 10(-10), 9.55 x 10(-6) mol.L-1) were both inhibited by HSYA in a concentration-dependent manner in vitro. The IC50 of HSYA to inhibit WRP and rabbit PMNs aggregation was 0.99 and 0.70 mmol.L-1, respectively. CONCLUSION: The PAF receptor binding can be antagonized by HSYA.

Animals↗
PubMed2002

[Preparation and in vitro release of tetramethylpyrazine phosphate pulsincap capsule controlled by an erodible plug].

AIM: To develop a novel pulsatile drug delivery system of which the lag-time is controlled by an erodible plug (EP) and evaluate its release characteristics in vitro. METHODS: The impermeable capsule body was prepared by fulfilling method and the drug tablet and the erodible plug were made by wet granulating compression. Tetramethylpyrazine phosphate (TMPP) pulsincap capsule was prepared by sealing the drug tablet and fillers inside the impermeable capsule body with the EP. The influence factors on the lag-time such as the EP pharmaceutical properties and the dissolution condition were investigated by dissolution testing. RESULTS: Both the composition and the weight of EP influenced the lag-time of the tetramethylpyrazine phosphate pulsincap capsule significantly. The lag-time prior to the drug release was enhanced when the content of gel-forming excipient (hydroxypropylmethylcellulose, HPMC) in the EP or the weight of EP was increased. The hardness of EP showed minor influence on the lag-time. In addition, the lag-time was shortened when the paddle speed was higher, while the pH value of the dissolution medium exhibited no significant influence on it. CONCLUSION: To meet the chronotherapeutic requirements, a pulsatile drug delivery system with a suitable lag-time can be achieved by adjusting the composition and the EP weight.

Calcium Channel Blockers↗
PubMed2002

[Effects of probiotics additives EM on growth metabolism and immune function of blue fox in growth phase].

Different doses of probiotics EM were added to the diets of blue fox in its growth phase to study the effects of EM additives on its growth, digestion metabolism and immune function. The results showed that with EM additives applied, the ingestion and average daily gains were increased remarkably (P < 0.05). The apparent digest rate of crude fibre, crude protein, mineral elements Ca, P and NPU could be increased (P < 0.05) and correlated with its dose, and the digest rates of the later four targets in group III were increased by 8.21%, 16.27%, 9.82%, and 12.13%, respectively. EM additives could not increase the digest rate of ether extral and N-free extract. Disease of diarrhoea and blood in stool could be prevented and cured, and immune function and the survival rate of fox in growth phase could be increased remarkably. EM, which a kind of efficient, safe and environmental protection additives, can be extended and applied in farming of fur animals.

Animals↗
PubMed2002

A cross-sectional study of health-related behaviors in rural eastern China.

OBJECTIVE: This study examined the status of health-related behaviors among rural residents and the factors influencing the practice of such behaviors. METHODS: One thousand and ninety subjects aged 15 years or over in a rural community, Anhui Province, China were surveyed. A questionnaire was used to collect information on the health knowledge, attitude and behavior of the subjects. Information on health behavior included smoking, drinking, dietary habits, regular exercises, sleeping pattern and oral health behavior. RESULTS: The prevalence of smoking and drinking in the male subjects was 46.5% and 46.9%, respectively. There was a positive significant association between smoking and drinking. Only 8.3% of all subjects ate three regular meals a day regularly. Among subjects who ate two meals a day, 89.7% did not have breakfast. Only 1.7% of subjects took part in regular exercise. About 85% of subjects slept 6 to 8 h per day. Only 38.4% of the respondents had the habit of hand washing before eating and after using the lavatory. 79.3% of the subjects brushed their teeth every day, and among them, only 10.6 percent brushed their teeth twice a day. Further analyses showed that 64.8% of subjects had 3-5 items of positive health behaviors out of 8 items and only 16.9% had six or more items. Logistical regression analyses suggested that better health behavior was affected by sex, age, years of education, income and health knowledge. CONCLUSION: The status of health behaviors among rural residents was generally poor. It is thus urgent to reinforce health education in rural communities in China.

Adolescent↗
PubMed2002

[The development of an automatic microscopic urinary sediment analyzer].

This paper introduces an automatic microscopic urinary sediment analyzer. A set of basic algorithms, including pretreatment and picking up characteristics is brought forward to realize the automatic segmentation of urinary sediment. This paper also characterizes the visible components in urinary sediment in morphology and has sum up 7 morphology parameters and a simple method of classification.

Algorithms↗
PubMed1995

The Role of Mast Cells and Their Mediators in IgG-Antigen Complex-Mediated Inflammation.

The strategic localization of mast cells near blood vessels led us to investigate the involvement of these cells in IgG-antigen complex-mediated inflammation, using mast-cell-deficient mice and their congenic controls. Mast cells were extensively degranulated and contributed to neutrophil influx, plasma exudation, fibrin deposition, edema formation, and tissue damage. Leukotrienes and the tumor necrosis factor (TNF) from mast cells participated in neutrophil elicitation, and histamine and leukotrienes in plasma exudation, fibrin deposition, and edema formation. Reconstituting the deficient mice with mast cells restored the responses, confirming the role of mast cells and their mediators. Studies with decomplemented and C5-deficient mice indicate that mast cells were stimulated by complement early in the reaction and later by an unknown mechanism. The findings show that mast cells and their mediators, such as leukotrienes, histamine, and TNF, play an important role in the initiation of IgG-antigen complex-mediated inflammation.

Journal Article↗
PubMedDate not supplied

Multiplex polymerase chain reaction for detection of herpes simplex virus type 1, type 2, cytomegalovirus, and varicella-zoster virus in ocular viral infections.

PURPOSE: To detect simultaneously herpes simplex virus type 1 (HSV-1), type 2 (HSV-2), cytomegalovirus (CMV), and varicella-zoster virus (VZV) in ocular specimens suspected of indicating viral infection, and to compare the results of multiplex polymerase chain reaction (PCR) with those of uniplex PCR. METHODS: Forty specimens, collected from 33 patients with clinically suspected herpes virus ocular infection, were tested. DNA was extracted from the specimens and amplified by multiplex and uniplex PCR. RESULTS: Both multiplex PCR and uniplex PCR gave the same results. Nineteen (19/33, 57.6%) patients were PCR-positive, among whom HSV-1 was detected in 13 (13/19, 68.4%) patients, and VZV in 6 (6/19, 31.6%) patients. CONCLUSION: These results demonstrated that multiplex PCR is as reliable as uniplex PCR, and is an accurate and a cost-saving method to identify several agents from a single specimen.

Adolescent↗
PubMedDate not supplied

An improved method of region grouping for microcalcification detection in digital mammograms.

A very important issue, namely region grouping, in computer-assisted diagnostic detection of microcalcification clusters (MCC) in digital mammograms is addressed in this work. In the diagnosis of breast cancer, MCC, instead of single and isolated microcalcifications, are considered clinically significant. Grouping individual regions segmented from digital mammograms, therefore, should be a component in an automatic MCC detection system. Actually this component may concern several system modules, such as segmentation, feature extraction, performance estimation aiming at both algorithm optimization and consistent evaluation and ultimately computerized malignancy estimation of calcified lesions. The previous work in the literature used a kernel-based method for region grouping. We proposed a distance-based and dense-to-sparse grouping method. The grouping result should be independent of the size, shape and orientation of real clusters. The application, namely cluster-oriented analysis including an adaptive segmentation method and cluster level feature extraction scheme, is discussed. A preliminary study was performed on a set of 30 full mammograms at 60 microm resolution, containing 40 MCC. The introduction of the cluster level feature extraction and a simple rule-based method reduces false positives from 7.1 to 2.4 per image at the sensitivity of 92.5%. This grouping method provides a solid basis for effective feature extraction-analysis and candidate cluster classification.

Algorithms↗
PubMedDate not supplied

Evaluating tumors and tumorlike lesions of the nasal cavity, the paranasal sinuses, and the adjacent skull base with diffusion-weighted MRI.

PURPOSE: The purpose of this study was to analyze the relationship of apparent diffusion coefficients (ADCs) to the malignant degree and the histopathological features of the lesions in the nasal cavity, the paranasal sinuses, and the adjacent skull base. METHOD: We evaluated the differences of the ADCs between the malignancies (n=18) and the benign lesions (n=6). The correlations between lesion ADCs and lesion cellularity, stroma, and necrosis were calculated. RESULTS: The ADCs of the malignancies were significantly lower than the benign lesions (P<0.0125). The ADCs were inversely correlated with tumor cellularity (P<0.01, r=-0.556). CONCLUSIONS: ADCs provide quantitative information that has limited utility in the differential diagnosis between malignant and benign lesions. The correlation of the histopathology of a lesion with ADCs is quite complex and affected by numerous tumor components besides cellularity including keratin, collagen, myxoid stroma, and necrosis.

Adolescent↗
PubMedDate not supplied

Proton magnetic resonance spectroscopy and diffusion-weighted imaging of central nervous system whipple disease.

A 72-year-old man presented with a 6-month history of dysphagia, fatigue, 60-lb weight loss, and central nervous system (CNS) deficits. Diffusion-weighted magnetic resonance imaging (MRI) of the brain showed mildly elevated nonrestricted apparent diffusion coefficients in the middle cerebellar peduncles, and magnetic resonance spectroscopy (MRS) showed decreased N-acetylaspartate and creatine with increased choline. Diffusion-weighted MRI and MRS offer noninvasive methods to help evaluate in vivo physiologic changes of CNS involvement in Whipple disease.

Aged↗
PubMedDate not supplied

Diagnostic value of gadolinium-enhanced 3D magnetic resonance angiography in patients with suspected hepatic arterial complications after liver transplantation.

PURPOSE: To evaluate the accuracy and clinical role of gadolinium-enhanced 3D magnetic resonance angiography (MRA) in patients with suspected hepatic arterial complications after liver transplantation. MATERIALS AND METHODS: Thirty-six consecutive MRA studies were performed in 33 liver transplant recipients after transplantation. MRA image quality was assessed subjectively. Thirty-two MRA studies were retrospectively reviewed and correlated with surgery (n = 2), conventional angiography (n = 18), or clinical follow-up (n = 12). MRA findings were also correlated with those of Doppler sonography in 30 of the cases. In 20 cases, concordance between MRA and surgery or conventional angiography was evaluated for each grade of hepatic artery stenosis (normal, mild [<50%], moderate [50-75%], severe [>75%], or occluded). RESULTS: MRA image quality was degraded 13 of 36 cases (36.1%) studies. The sensitivity, specificity, and accuracy of MRA by consensus reading for more than 50% of hepatic artery stenosis or occlusion were 67%, 90%, and 81.3%, respectively. Of the 19 cases in which Doppler sonography was abnormal, MRA correctly characterized hepatic artery stenosis in 16 (84.2%). MRA also correctly identified all 5 occurrences of celiac artery stenosis. However, MRA overestimated the severity of hepatic arterial stenosis in 3 (15%) of 20 cases and underestimated 5 (25%) of 20 cases. CONCLUSION: MRA complements Doppler ultrasound to exclude significant hepatic artery stenosis. However, a substantial number of MRA studies were technically inadequate, and MRA demonstrated limited efficacy for correctly grading the severity of hepatic artery stenosis.

Adult↗