Biomedical subjects

Yan Zhang

Publications and source records attributed to Yan Zhang.

At least 451 records · Page 25Linked to original sources

PubMed2003

Latency-associated peptide prevents skin fibrosis in murine sclerodermatous graft-versus-host disease, a model for human scleroderma.

Murine sclerodermatous graft-versus-host disease (Scl GVHD), produced by transplanting B10.D2 bone marrow and spleen cells to lethally irradiated BALB/cJ mice, is a model for human scleroderma. Mice with Scl GVHD have skin thickening, lung fibrosis, cutaneous mononuclear cell infiltration, and upregulation of cutaneous transforming growth factor beta1 (TGF-beta1) and type I collagen mRNAs by day 21 after bone marrow transplantation. Elevated TGF-beta1 appears to be the critical cytokine driving fibrosis in Scl GVHD, which can be prevented with antibodies to TGF-beta administered early in disease. Here we demonstrate that we can also prevent skin thickening in mice with Scl GVHD with a naturally occurring antagonist to TGF-beta1, human latency-associated peptide (LAP). By quantitative real-time PCR analysis and immunostaining, LAP treatment also abrogates the upregulation of cutaneous TGF-beta1 and connective tissue growth factor mRNAs and type I collagen synthesis in Scl GVHD. In contrast to anti-TGF-beta antibodies, LAP at 4 ng total per mouse has no significant suppressive effect on cutaneous influx of T cells and monocytes or immune cell activation. LAP may be a potential new therapy in scleroderma and other TGF-beta-driven fibrosing disease that targets TGF-beta more specifically, without affecting systemic critical roles of TGF-beta on immune cell function.

Animals↗

PubMed2003

K+ and Na+-induced self-assembly of telomeric oligonucleotide d(TTAGGG)n.

The telomeric DNA oligomers, d(TTAGGG)(n), where n=1, 2, 4, could self-associate into the multi-stranded structures in appropriate condition, exhibited different CD spectra. The presense of Na(+) was more advantage to facilitate the formation of anti-parallel conformation, but the presense of K(+) enhanced their thermal stability. Spectroscopic analysis of 3, 3'-diethyloxadicarbocyanine (DODC) showed the formation of hairpin quadruplex structures for d(TTAGGG)(2) and d(TTAGGG)(4), but d(TTAGGG) could not. The four-stranded tetraplexes and branched nanowire formed in the presense of K(+) or Na(+) alone were observed by atomic force microscopy (AFM). The ability of d(TTAGGG)(n) to self-assemble into four-stranded tetraplexes and nanowires depends strongly on the number of repeating units and ionic environment. A model to explain how these structures formed is proposed.

Cations, Monovalent↗

PubMed2003

Glucuronides are the main isoflavone metabolites in women.

Three experiments were conducted to characterize the metabolism of isoflavones from soy milk in women: two meals in 2 wk separated by a 1-wk washout period (Experiment 1), one meal feeding (Experiment 2) and six consecutive days of feeding (Experiment 3). Urine and plasma samples were extracted directly or predigested before extraction with H-2 beta-glucuronidase/sulfatase or B-3 beta-glucuronidase so that isoflavone glucuronide and sulfate conjugates could be determined by difference. Among the three experiments, no significant differences were found in the proportion of glucuronide, sulfate and aglycone isoflavones recovered from plasma samples taken 3 h after isoflavone dosing or in 24-h urine samples taken after isoflavone dosing. In the 6-d feeding study, samples taken on d 5 and 6 did not differ significantly in isoflavone content or proportion of the metabolites studied. The percentages of daidzein and genistein glucuronides were 73 +/- 4 and 71 +/- 5% of total daidzein and genistein excreted in urine, and 62 +/- 4 and 53 +/- 6% of total daidzein and genistein present in plasma, respectively. Percentages of aglycone daidzein and genistein were 4 +/- 1 and 5 +/- 1% of total daidzein and genistein in urine, and 18 +/- 2 and 26 +/- 7% of total daidzein and genistein present in plasma, respectively. These studies showed that about one fifth of circulating isoflavones are aglycones. Concentrations of isoflavones chosen for in vitro studies should take this into account. Because the glucuronide isoflavones predominate in vivo, these metabolites should not be overlooked as possible contributors to observed effects of isoflavones.

Adult↗

PubMed2003

Evaluation of the effect of protamine on human prostate carcinoma PC-3m using contrast enhanced Doppler ultrasound.

PURPOSE: We evaluated the ability of contrast enhanced Doppler ultrasound (CEDU) to demonstrate changes in tumor vascularity during angiogenesis inhibitive therapy in PC-3m human prostate carcinoma. MATERIALS AND METHODS: Pieces of human prostate carcinoma PC-3m tumor (Institute of Urology, Beijing University, Beijing, People's Republic of China) were transplanted subcutaneously into 48 male BALB/C nude mice (Center of Animal Quarantine, Beijing, People's Republic of China). Protamine (Shanghai Biochemistry Pharmaceutical Co., People's Republic of China) was injected subcutaneously as an angiogenesis inhibitor. The animals were randomly divided into 3 groups according to protamine dose. The color flow signal-pixel rate (SPR) of the images was calculated using the number of pixels showing color Doppler signals as a ratio of the total number of pixels covering the lesion. RESULTS: The SPR of the high and low dose groups were significantly lower than that of the control group (p <0.01). Mean SPR +/- SD in the 3 groups was 0.09 +/- 0.05, 0.11 +/- 0.05 and 0.22 +/- 0.10, respectively. SPR correlated significantly with microvessel density (r = 0.86 to 0.94, p <0.01). CONCLUSIONS: CEDU can effectively reveal the change in vascularity in a tumor that was treated with protamine. In addition to microvessel density, CEDU may become one of several independent prognostic indexes of angiogenesis inhibitor therapy.

Angiogenesis Inhibitors↗

PubMed2003

Antidepressant-like effects of kappa-opioid receptor antagonists in the forced swim test in rats.

We showed previously that cAMP response element-binding protein (CREB) within the nucleus accumbens (NAc) of rats regulates immobility in the forced swim test (FST), an assay used to study depression. Because CREB regulates expression of dynorphin (which acts at kappa-opioid receptors) in NAc neurons, these findings raised the possibility that kappa-receptors mediate immobility behaviors in the FST. Here, we report that i.c.v. administration of the kappa-antagonist nor-binaltorphimine dose dependently decreased immobility in the FST, suggesting that it has antidepressant-like effects. Implicating a specific effect at kappa-receptors, similar antidepressant-like effects were seen after treatment with either of two novel, structurally dissimilar kappa-antagonists: 5'-guanidinonaltrindole, which was effective after i.c.v. but not systemic treatment, and 5'-acetamidinoethylnaltrindole (ANTI), which was potent and effective after systemic treatment. The behavioral effects of the kappa-antagonists resembled those of tricyclic antidepressants (desipramine) and selective serotonin reuptake inhibitors (fluoxetine and citalopram). Conversely, systemic administration of the kappa-agonist [5alpha,7alpha,8beta]-N-methyl-N-[7-[1-pyrrolidinyl]-1-oxaspiro[4.5]dec8-yl]-benzenacetamide (U-69593) dose dependently increased immobility in the FST, consistent with prodepressant-like effects. The effects of the kappa-ligands in the FST were not correlated with nonspecific effects on locomotor activity. Furthermore, the most potent and effective kappa-antagonist (ANTI) did not affect the rewarding impact of lateral hypothalamic brain stimulation at a dose with strong antidepressant-like effects. These findings are consistent with the hypothesis that CREB-mediated induction of dynorphin in the NAc "triggers" immobility behavior in the FST. Furthermore, they raise the possibility that kappa-antagonists may have efficacy as antidepressants, but lack stimulant or reward-related effects.

Animals↗

PubMed2003

A homogeneous fluorescence polarization assay adaptable for a range of protein serine/threonine and tyrosine kinases.

Recently, a new technology for high-throughput screening has been developed, called IMAP(patent pending). IMAP technology has previously been implemented in an assay for cyclic nucleotide phosphodiesterases (PDE). The authors describe the development of a homogeneous, non-antibody-based fluorescence polarization (FP) assay for a variety of protein kinases. In this assay, fluorescently labeled peptide substrate phosphorylated by the kinase is captured on modified nanoparticles through interactions with immobilized metal (M(III)) coordination complexes, resulting in a change from low to high polarization values. This assay is applicable to protein kinases that phosphorylate serine, threonine, or tyrosine residues. The IMAP platform is very compatible with high-throughput robotics and can be applied to the 1536-well format. As there are hundreds of different kinases coded for in the human genome, the assay platform described in this report is a valuable new tool in drug discovery.

Biological Assay↗

PubMed2003

Neuronal overexpression of COX-2 results in dominant production of PGE2 and altered fever response.

Cyclooxygenases catalyze the first committed step in the formation of prostaglandins and thromboxanes from arachidonic acid. Cyclooxygenase-2 (COX-2), the inducible isoform of cyclooxygenase, is expressed in brain selectively in neurons of hippocampus, cerebral cortex, amygdala, and hypothalamus. Prostaglandins function in many processes in the CNS, including fever induction, nociception, and learning and memory, and are upregulated in paradigms of excitotoxic brain injury such as stroke and epilepsy. To address the varied functions of COX-2 and its prostaglandin products in brain, we have developed a transgenic mouse model in which COX-2 is selectively overexpressed in neurons of the CNS. COX-2 transgenic mice demonstrate elevated levels of all prostaglandins and thromboxane, albeit with a predominant induction of PGE(2) over other prostaglandins, followed by more modest inductions of PGI(2), and relatively smaller increases in PGF(2alpha),PGD(2), and TxB(2). We also examined whether increased neuronal production of prostaglandins would affect fever induction in response to the bacterial endotoxin lipopolysaccharide. COX-2 induction in brain endothelium has been previously determined to play an important role in fever induction, and we tested whether neuronal expression of COX-2 in hypothalamus also contributed to the febrile response. We found that in mice expressing transgenic COX-2 in anterior hypothalamus, the febrile response was significantly potentiated in transgenic as compared to non-transgenic mice, with an accelerated onset of fever by 1 2 hours after LPS administration, suggesting a role for neuronally derived COX-2 in the fever response.

Animals↗

PubMed2003

Significance of affinity and cooperativity in oxygen binding to hemoglobin of horse fetal and maternal blood.

The physiological significance of the position and shape of the oxygen equilibrium curve (OEC) of horse hemoglobin (Hb) is considered from the viewpoint of oxygen (O2) transport efficiency and the effectiveness of the Bohr effect. In horse fetal and maternal bloods, their physiological O2 affinities are nearly optimized with respect to the effectiveness of the Bohr shift occurring at the O2 release site, when it is measured by the change in O2 saturation per unit change in P50. With relatively low cooperativity (n=2.69) of horse Hb under physiological conditions, the effectiveness of the Bohr shift for fetal blood at O2 uptake site and maternal blood at O2 release site is high. These facts imply that the position and the cooperativity of horse Hb OEC are optimized to receive maximal benefit from the double Bohr shift. Before exercise, the position of the OEC for adult mares is nearly optimized for the effectiveness of the Bohr shift occurring at the O2 release site, whereas, at maximal exercise, the position of the OEC tends to become advantageous for O2 transport efficiency.

2,3-Diphosphoglycerate↗

PubMed2003

The cooperativity of human fetal and adult hemoglobins is optimized: a consideration based on the effectiveness of the Bohr shift.

The physiological significance of the cooperativity of human hemoglobin (Hb) is considered from the viewpoint of the effectiveness of the Bohr shift at the sites of O(2) release and uptake across the placental membrane. The effects of the Bohr shift was examined by changing the O(2) saturation of Hb (S(pO2)) per unit change in P(50), -dS(PO2)/d P(50), where P(50) is partial pressure of O(2) at half saturation. The Bohr shift at the sites of O(2) uptake and release was found to be highly effective in both fetal and maternal bloods at physiological degree of cooperativity (Hill's coefficient, n=2.65). From the results obtained in this paper, it is concluded that the positions of OECs of fetal and maternal Hbs are regulated to receive a maximal benefit from the Bohr shift, and that a relatively low n value of human tetrameric Hb is adequate for the O(2) and CO(2) exchange across the placental membrane.

Allosteric Regulation↗

PubMed2003

Cloning and expression of ornithine decarboxylase gene from human colorectal carcinoma.

AIM: To construct and express ODC recombinant gene for further exploring its potential use in early diagnosis of colorectal carcinoma. METHODS: Total RNA was extracted from colon cancer tissues and amplified by reverse-transcription PCR with two primers, which span the whole coding region of ODC. The synthesized ODC cDNA was cloned into vector pQE-30 at restriction sites BamH I and Sal I which constituted recombinant expression plasmid pQE30-ODC. The sequence of inserted fragment was confirmed by DNA sequencing, the fusion protein including 6His-tag was facilitated for purification by Ni-NTA chromatographic column. RESULTS: ODC expression vector was constructed and confirmed with restriction enzyme digestion and subsequent DNA sequencing. The DNA sequence matching on NCBI Blast showed 99 % affinity. The vector was transformed into E. coli M15 and expressed. The expressed ODC protein was verified with Western blotting. CONCLUSION: The ODC prokaryote expression vector is constructed and thus greatly facilitates to study the role of ODC in colorectal carcinoma.

Cloning, Molecular↗

PubMed2003

[Preliminary analysis on human telomerase reverse transcriptase gene expression in acute leukemia].

OBJECTIVE: To explore the relationship between gene expression of human telomerase reverse transcriptase (hTERT) and its clinical characteristics in leukemia. METHODS: The protocol of RT-PCR was used to detect the hTERTmRNA expressing levels in peripheral blood samples from leukemic patients under primary treatment(n=42), in complete remission(n=21), with recurrent leukemia (n=4); and from normal subjects (n=5), respectively. RESULTS: The positive percentage of hTERTmRNA expression was 73.81% for the primary treatment cases, and 19.05% for the complete remission cases. All of the recurrent cases gave positive results. One of the normal controls presented low level of hTERTmRNA expression. The expressing level of hTERTmRNA in primary treatment cases was 0.64+/-0.21, in complete remission leukemia 0.31+/-0.16, in recurrent cases 0.84+/-0.09, and in normal controls 0.10. CONCLUSION: The activation of telomerase may be an essential factor in the development of leukemia and usually be the late event in its progression. As an indicator of leukemia cell, the detection of hTERT mRNA may be used in clinical analysis, disease monitoring and prognosis judgement.

Acute Disease↗

PubMed2003

[Experimental study of vasoligation in the treatment and prevention of benign prostatic hyperplasia].

OBJECTIVES: To investigate the possibility and efficacy of vasoligation and deferent vein ligation in treating and preventing benign prostatic hyperplasia(BPH). METHODS: 40 male pooches were divided into A, B, C and D groups randomly. Each group has 10 pooches group A and B were made into the model of BPH. Two years later, the pooches in group A and C accepted the operation of vasoligation and deferent vein ligation on both sides. Group B and D only accepted the operation of dissection and relieving its deferent duct. Then continuing to feed the 40 pooches after the operation, they were killed another two years later. After taking out their prostates and calculating their volume and weight, the sections of the prostates were checked by microscope to observe their histology and pathology changes. RESULTS: There were significant differences of weight and volume as well as the changes of histology and pathology between group A and group C (P < 0.01). It was the same with group B and D (hyperplasia changes). CONCLUSIONS: Vasoligation and deferent vein ligation before benign prostatic hyperplasia at pooches grow-up stage can reduce the extent of BPH at old age, and treatment after benign prostatic hyperplasia can make prostatic tissue appear different degrees of atrophy.

Animals↗

PubMed2003

[The effect of high pressure on morphology, expression of alpha-actin and proliferating cell nuclear antigen of vascular smooth muscle cells--a new model of common carotid artery exposed to stress in vivo].

To investigate the role and mechanism of mechanical stress on arterial remodeling, a new model of common carotid artery exposed to stress in vivo was established in rat, in which the change of pressure is the only influencing factor. The effect of high pressure on the morphology and expression of alpha-actin and proliferating cell nuclear antigen (PCNA) of vascular smooth muscle cells (VSMCs) in the artery was assessed. The arteries were perfused by both high pressure (160 mmHg) and normal pressure (80 mmHg) for 6 hours. The changes of morphology, expression of alpha-actin and PCNA in VSMCs were studied by histology and immunohistochemistry. The results showed that the new model could be controlled well in pressure and frequency. The euchromatin was increased and PCNA-positive particles were observed in the nuclei of VSMCs, but the expression of alpha-actin was decreased when the arteries were exposed to the high pressure. The new model has been successfully established, which provides a new tool for studying the effect of mechanical stress on arterial remodeling. In this experiment, VSMCs underwent a transformation from contractile phenotype into synthetic phenotype and tended to proliferate in response to the high pressure.

Actins↗

PubMed2003

[Pharyagoesophageal sphinoter myotomy for voice rehabilitation after total laryngectomy].

OBJECTIVE: In those patients received total laryngectomy, Blom-Singer prosthesis speech appears to be the more effective form of rehabilitation. To reduce the effect of pharyngoesophageal sphincter on the Blom-Singer prosthesis voice restoration following total laryngectomy, the pharyagoesphageal sphincter myotomy was designed and carried out. METHODS: After total laryngectomy, the cricopharyngeus muscle stricture or spasm appears to inhibit the air flowing and prevent the speech. The pharyngoesophageal sphincter is now defined as the area including the cricopharyngeus with a portion of inferior constrictor, as well as some of the upper cervical esophagus. The pharyngoesophageal sphincter were incised intra- and post- operation of total laryngectomy, the dissection was approximately 5 cm in vertical length and 1 cm in width. RESULTS: Among the 33 patients who received pharyngoesophageal sphincter myotomy following total laryngectomy, voice restoration was achieved in 32 cases, the success rate was 97%. 25 patients had survived for 3 years, 18 patients survived for 5 years. CONCLUSION: Pharyagoesophageal sphincter myotomy can raise the success rate of rehabilitation of the voice by Blom-Singer prosthesis.

Aged↗

PubMed2003

[Noninvasive evaluation of liver fibrosis in chronic hepatitis B patients].

OBJECTIVE: To investigate the clinical usefulness of noninvasive diagnostic methods in evaluating liver fibrosis in hepatitis B virus (HBV) patients. METHODS: 102 patients with chronic hepatitis B (CHB) were enrolled from Beijing Friendship Hospital Affiliated to Capital University of Medical Sciences. Noninvasive diagnostic methods including ultrasonography, CT, serum markers of liver function and fibrosis, and HBV DNA were performed and compared with histological fibrotic changes in order to establish a noninvasive method for detecting the degree of liver fibrosis. RESULTS: The total score of liver surface, edge, parenchyma echogenicity, intrahepatic vessels, and the size of spleen had a coefficient of 0.822 with fibrotic stage. By receiver operating curve (ROC) analysis, the sensitivity to distinguish cirrhosis from CHB was 86.1% and the specificity was 95.5% if the total ultrasonic score was more than 10. The CT imaging diagnosed liver cirrhosis with a specificity of 100% and a sensitivity of 48.5%. The change of CT values in cirrhotic patients was lower than that in controls and no cirrhotic patients (F=5.805, P<0.01), when the voltage was increased from 100 KV to 140 KV. Except normal controls and S1 group, S2 and S3 group, the level of HA and collagen IV between the other groups were statistically different. The cut-off value of HA to diagnose cirrhosis was 108 (microg/L) with a sensitivity of 72.2% and a specificity of 80.3%. The cut-off value of collagen IV to diagnose cirrhosis was 188 (microg/L) with a sensitivity of 72.2% and a specificity of 78.8%. When ultrasonography was combined with serum markers, the sensitivity was 72.2% and the specificity was 80.3%. CONCLUSION: Both ultrasonography and serum markers are useful to diagnose cirrhosis. The combination of the two examinations is more valuable than any one alone. The characteristic CT imaging has high specificity but low sensitivity in diagnosing early cirrhosis. HA and collagen IV are correlated more closely with the stage of fibrosis, and can reflect the severity of fibrosis.

Adolescent↗

PubMed2003

[Detection of bcr/abl fusion gene in chronic myeloid leukemia by fluorescence in situ hybridization and nested reverse transcription polymerase chain reaction].

OBJECTIVE: To detect the bcr/abl fusion gene in chronic myeloid leukemia (CML) for assisting in clinical diagnosis. METHODS: Fluorescence in situ hybridization (FISH) and nested reverse transcription polymerase chain reaction (RT-PCR) were used. RESULTS: Out of 16 CML patients, the results of FISH was not consistent with that of nested RT-PCR in 3 cases. When compared with the results of Northern blot, it was found that nested RT-PCR was more sensitive than FISH, but might give false positive results. Moreover, FISH was the easier method for detecting rarer types of bcr/abl transcripts. For detecting the latter occasions nested RT-PCR have to design several specific primers. CONCLUSION: It could take their advantages of applying FISH and nested RT-PCR at the same time to make the results more accurate and reliable for the diagnosis, prognosis and monitor of minimal residual disease.

Adolescent↗

PubMed2003

[A novel method for fabrication of tissue microarray].

BACKGROUND & OBJECTIVE: Tissue chip (tissue microarray, TMA) is one of the most important biochip techniques, just following the gene chip and the protein chip, which is one of the most important functional genomics and proteomics research methods in the post-genomic era. However, the present TMA technology has certain shortcomings, such as lack of advanced instruments, tedious procedure, and low sampling accuracy, etc. This new method was designed to improve the technology of TMA. METHODS: A common microscope was installed with a special holing needle, a sampling needle, and a proper box to fix paraffin blocks on the microscope carrier. With the precise mechanical control of microscope, the holing procedure on the recipient paraffin blocks and sampling procedure of core tissue biopsies were performed with the re-equipped microscope. The precise observation and localization of sampling regions were also performed using the same microscope equipped with a stereoscope. RESULTS: The new method simplified TMA procedure, and the whole process of holing, locating, and sampling was performed with the same instrument on the same platform. The single-use holing and sampling needles were first applied to maintain higher accuracy and to avoid the tissue remains and contamination among different samples. And high-qualified tissue chips of colorectal tumors were produced successfully by the new method. CONCLUSION: Using the re-equipped common microscope to fabricate tissue microarrays is a simple, reliable, cost-effective,and well-applicable technique.

Histocytological Preparation Techniques↗

PubMed2003

Detection of viable myocardium by low dose of dobutamine cine MR imaging in miniswine.

OBJECTIVE: To evaluate the diagnostic value of dobutamine stress magnetic resonance imaging (MRI) for myocardial viability. METHODS: Ten male miniswines underwent left ventriculography and coronary angiography, followed by stenosis of the left circumflex coronary artery (LCX) using ameroid constrictor. More than one month later, left ventriculography and coronary angiography were performed again, followed by cine-MRI at rest and during stress with incremental dose of dobutamine 5 - 20 micro g.kg(-1).min(-1). Traditional and/or breath-hold cine-MRI were used to evaluate regional left ventricular wall motion, corresponding to basal, midventricular and apical short-axis tomograms. Regional wall motion score index (WMSI) was calculated. The miniswines were finally sacrificed for pathological examination. Triphenyl tetrazolium chloride (TTC) delineated myocardial infarction. Microscopy was used to identify myocardial cellular changes. RESULTS: One pig died, one pig suffered from aneurysm and another showed no negative findings. The other seven pigs were found with hypokinetic (n = 4) or akinetic (n = 3) myocardial regions related to stenosed LCX. Their mean WMSI at rest for the lateral and posteroinferior walls (ischemic regions) of the left ventricle was 2.27 +/- 0.32, as compared with 1.00 +/- 0.00 (P < 0.01) for the corresponding nonischemic anteroseptal regions. Further, the mean WMSI for the ischemic regions was 2.27 +/- 0.32 at rest compared with 1.40 +/- 0.39 (P < 0.01) at the dose of dobutamine 5 micro g.kg(-1).min(-1). However, the mean WMSI at the doses of dobutamine 10 and 20 micro g.kg(-1). min(-1) were 1.70 +/- 0.76 and 1.75 +/- 0.83, respectively, with no significant difference as compared with the mean WSCI at rest (P > 0.05). The pathologic examination showed viable myocardium at the ischemic regions. CONCLUSION: Low-dose dobutamine (5 micro g.kg(-1).min(-1)) recovers hypokinetic or akinetic myocardial regions, and dobutamine stress MRI can be used to detect myocardial viability.

Animals↗