Biomedical subjects

H Zhang

Publications and source records attributed to H Zhang.

At least 595 records · Page 33Linked to original sources

PubMed2000

Protein-bound polysaccharide PSK inhibits tumor invasiveness by down-regulation of TGF-beta1 and MMPs.

Transforming growth factor beta1 (TGF-beta1) and matrix metalloproteinases (MMPs) produced by tumor cells play important roles in tumor invasion. PSK, a protein-bound polysaccharide, is widely used in Japan as an immunopotentiating biological response modifier for cancer patients. In this study, we focused on the effects of PSK on invasiveness, TGF-beta1 production, and MMPs expression in two human tumor cell lines, pancreatic cancer cell line (NOR-P1) and gastric cancer cell line (MK-1P3). PSK significantly decreased the invasiveness of both cell lines through Matrigel-coated filters but did not affect cell viability, proliferation, or adhesion. Decreased invasion was associated with the inhibition of TGF-beta1, MMP-2, and MMP-9 at both mRNA and protein levels as assessed by reverse transcriptase-polymerase chain reaction, gelatin zymography, and enzyme-linked immunosorbent assay. Antibody against TGF-beta1 neutralized the MMP activities of both cell lines. PSK also suppressed the expression of urokinase plasminogen activator (uPA) and uPA receptor but did not change plasminogen activator inhibitor-1 (PAI-1) expression. Western blot analysis showed that PSK reduced uPA protein expression but not PAI-1 expression in the both cell lines. These results indicate that PSK suppresses tumor cell invasiveness through down-regulation of several invasion-related factors including TGF-beta1, uPA, MMP-2, and MMP-9.

Adjuvants, Immunologic↗

PubMed2000

Structure characterization of human RalGDS gene, and the identification of its novel variant.

RalGDS is a guanine nucleotide dissociation stimulator for Ral, which is a member of the Ras GTPase superfamily that regulates cellular proliferation, differentiation and transformation by mediating multiple signal transduction pathways. RalGDS can specifically promote the conversion from an inactive GDP-bound state to an active GTP-bound state for Ral. The cDNA of human RalGDS has been cloned recently. In this paper, by comparison between the gene's genomic and cDNA seqence, we determined the structure of the gene, which showed that the reported human RalGDS transcribed from 18 exons. Furthermore, a novel variant of RalGDS that codes for a protein with a different N-terminus was cloned and identified. Northern hybridization revealed that the novel transcript was of 6.0 kb in length while the transcript previously reported is of 4.0 kb. Both transcripts were ubiquitously expressed in human adult tissues examined, albeit with different amounts. In addition, this novel transcript was proved to be caused by employment of a new exon, designated as exon 1a, instead of the one, designated as exon 1b, in the reported cDNA. Thus, the RalGDS gene consists of at least 19 exons and spanned a 44 kb region. The length between exon 1a and exon 2 was 33 kb, while the length between exon 1b and exon 2 was 8.8 kb.

Amino Acid Sequence↗

PubMed2000

Assessing the chromosome copy number in metaphase II oocytes by sequential fluorescence in situ hybridization.

PURPOSE: Aneuploidy in oocytes is the main cause of failed embryo implantation and of miscarriage. At present, only limited data on the prevalence of aneuploidy in freshly collected human oocytes are available and all studies have been performed with conventional methods for karyotyping. In this feasibility study, multiple-hybridization fluorescence in situ hybridization (FISH) was evaluated as an alternative method to determine the number of chromosomes in oocytes. METHODS: Fifty-two spare oocytes were collected from 23 patients treated with gonadotropins for intrauterine insemination or intracytoplasmic sperm injection. A conventional dual color FISH approach using mixtures of chromosome-specific standard alpha-satellite probes was applied consecutively to the chromosomes of the same metaphase II oocyte. Mixtures of three to six probes were designed in order to allow chromosome identification based on signal color and centromeric index. RESULTS: One hybridization cycle was possible in 52 uninseminated metaphase II oocytes, two hybridizations in 43 oocytes (82.7%), three hybridizations in 30 oocytes (57.6%), four hybridizations in 27 oocytes (51.9%), and five hybridizations in 15 oocytes (28.8%). Altogether, 591 chromosomes could be marked (47.4% of the entire chromosome complement, 11.4 chromosomes per oocyte). The most important single factor contributing to technical failure was loss of the oocyte from the slide. CONCLUSION: This feasibility study demonstrates that multiple-hybridization FISH can be used for the assessment of a larger proportion of the chromosome complement in oocyte as compared to previous studies based on FISH.

Adult↗

PubMed2000

A Catharanthus roseus BPF-1 homologue interacts with an elicitor-responsive region of the secondary metabolite biosynthetic gene Str and is induced by elicitor via a JA-independent signal transduction pathway.

Plants respond to pathogen attack by induction of various defence responses, including the biosynthesis of protective secondary metabolites. In Catharanthus roseus, the elicitor-induced expression of the terpenoid indole alkaloid biosynthetic gene Strictosidine synthase (Str) is mediated via the plant stress hormonejasmonate. In the promoters of several defence-related genes, cis-acting elements have been identified that are important for transcriptional regulation upon stress signals. Here we show that an upstream region in the Str promoter confers responsiveness to partially purified yeast elicitor and jasmonate. Yeast one-hybrid screening with this element as a bait identified a MYB-like protein, which shows high homology to parsley box P-binding factor-1 (PcBPF-1). In vitro analyses showed that the Str promoter fragment contained a novel binding site for BPF-1-like proteins with higher binding affinity than the previously described box P. CrBPF-1 mRNA accumulated rapidly in elicitor-treated C. roseus suspension cells, whereas no induction was observed with jasmonate. Inhibitor studies indicated that CrBPF-1 plays a role in an elicitor-responsive but jasmonate-independent signal transduction pathway, acting downstream of protein phosphorylation and calcium influx.

Amino Acid Sequence↗

PubMed2000

Plasminogen activator inhibitor-1 fused with erythropoietin (EPO) mimetic peptide (EMP) enhances the EPO activity of EMP.

Erythropoietin (EPO) mimetic peptide (EMP) encoding sequence was inserted into the gene of plasminogen activator inhibitor-1 (PAI-1) between Ala348 and Pro349 (P2'-P3'), generating a novel gene, PAI-1/EMP (PMP). This was cloned into pET32a expression vector, fused with TrxA peptide in the vector, and a 63-kDa protein was expressed in inclusion bodies with an expression level >50%. The TrxA/PMP protein was purified by Ni-NTA-agarose metal-ligand affinity chromatography to a purity >90%, showing a single, silver-stained band on SDS-PAGE. Using a reticulocyte counting assay, the EPO activity of PMP was determined to be 5,000 IU/mg, 2,500-fold that of EMP.

Amino Acid Sequence↗

PubMed2000

Germline PTEN mutations in three families with Cowden syndrome.

Cowden syndrome (CS) is an autosomal dominant inherited disorder characterized by hamartomas in a variety of tissues including the skin, thyroid, breast, endometrium, and the brain. Individuals with CS are predisposed to development of malignancy in these organs, especially the breast and the thyroid. We describe 3 unrelated individuals with CS associated with germline PTEN mutations. While the frameshift (375insTTTA) and the missense (Gly69Arg) mutations reported herein are novel in CS, the nonsense (Arg130stop) mutation has been described in 2 families with CS and in a single family exhibiting both CS and Bannayan Zonana phenotype.

Adult↗

PubMed2000

The Simon effect and its reversal in three-choice Hedge and Marsh tasks: evidence for irrelevant stimulus-response compatibility and stimulus congruity.

In 2-choice A. Hedge and N. W. A. Marsh (1975) tasks or S. Kornblum's (1992) Type-5 ensembles, irrelevant stimulus-response compatibility (SRC), logical recoding, display control arrangement correspondence (DCC), and stimulus congruity are confounded. By using 3 response alternatives and both compatible and incompatible stimulus-response mappings, irrelevant SRC was pitted against logical recoding and both of them were disentangled from DCC and stimulus congruity. By varying response labels on a trial-by-trial basis and using different stimuli and responses, DCC and stimulus congruity were decoupled. Results from 4 experiments showed that neither logical recoding nor DCC contributes to the Simon effect and its reversal. Irrelevant SRC and stimulus congruity are necessary but neither is sufficient to account for the Simon effect and its reversal. A connectionist model of compatibility incorporating both irrelevant SRC and stimulus congruity appears to account for the results.

Choice Behavior↗

PubMed2000

Ordinal knowledge: number names and number concepts in Chinese and English.

Previous research has demonstrated cross-language variation in early counting associated with linguistic differences in number-naming systems. Ordinal number names are typically learned later than cardinal names, but languages also differ in the regularity with which they form these names. Elementary school children in China and the U.S. showed differences in the acquisition and use of ordinal numbers corresponding to linguistic differences in ordinal names in their native languages. On tasks assessing children's conceptual knowledge of ordinal relations, a more complicated picture emerged. These results suggest that (a) children induce their language's set of ordinal number names by generalization based on rules sanctioned by early examples, and (b) the relation between ordinal names and ordinal concepts is a complex one, with language only one source of difficulty in understanding ordinal relations. Implications for studies of the relation between linguistic structure and cognitive development are discussed, in particular the possibility that effects of linguistic differences may vary for different levels of development and for different aspects of cognition.

Child↗

PubMed2000

Receptor-mediated hydrolysis of plasma membrane messenger PIP2 leads to K+-current desensitization.

Phosphatidylinositol bisphosphate (PIP2) directly regulates functions as diverse as the organization of the cytoskeleton, vesicular transport and ion channel activity. It is not known, however, whether dynamic changes in PIP2 levels have a regulatory role of physiological importance in such functions. Here, we show in both native cardiac cells and heterologous expression systems that receptor-regulated PIP2 hydrolysis results in desensitization of a GTP-binding protein-stimulated potassium current. Two receptor-regulated pathways in the plasma membrane cross-talk at the level of these channels to modulate potassium currents. One pathway signals through the betagamma subunits of G proteins, which bind directly to the channel. Gbetagamma subunits stabilize interactions with PIP2 and lead to persistent channel activation. The second pathway activates phospholipase C (PLC) which hydrolyses PIP2 and limits Gbetagamma-stimulated activity. Our results provide evidence that PIP2 itself is a receptor-regulated second messenger, downregulation of which accounts for a new form of desensitization.

Acetylcholine↗

PubMed2000

Reduction of liver Fas expression by an antisense oligonucleotide protects mice from fulminant hepatitis.

Aberrant apoptosis-mediated cell death is believed to result in a number of different human diseases. For example, excessive apoptosis in the liver can result in fulminant and autoimmune forms of hepatitis. We have explored the possibility that inhibition of Fas expression in mice would reduce the severity of fulminant hepatitis. To do this, we have developed a chemically modified 2'-O-(2-methoxy)ethyl antisense oligonucleotide (ISIS 22023) inhibitor of mouse Fas expression. In tissue culture, this oligonucleotide induced a reduction in Fas mRNA expression that was both concentration- and sequence-specific. In Balb/c mice, dosing with ISIS 22023 reduced Fas mRNA and protein expressions in liver by 90%. The ID50 for this response was 8-10 mg kg-1 daily dosing, and the reduction was highly dependent on oligonucleotide sequence, oligonucleotide concentration in liver, and treatment time. Pretreatment with ISIS 22023 completely protected mice from fulminant hepatitis induced by agonistic Fas antibody, by a mechanism entirely consistent with an oligonucleotide antisense mechanism of action. In addition, oligonucleotide-mediated suppression of Fas expression reduced the severity of acetaminophen-mediated fulminant hepatitis, but was without effect on concanavalin A-mediated hepatitis. Our results demonstrate that 2'-O-(2-methoxy)ethyl containing antisense oligonucleotides targeting Fas can exert in vivo pharmacological activity in liver, and suggest that oligonucleotide inhibitors of Fas may be useful in the treatment of human liver disease.

Animals↗

PubMed2000

Non-NF-kappaB elements are required for full induction of the rat type II nitric oxide synthase in vascular smooth muscle cells.

We have investigated the role of the NF-kappaB binding sites and other promoter elements beyond NF-kappaB in iNOS induction in rat vascular smooth muscle cells (SMC). Rat aortic SMC transfected with iNOS promoter constructs with either mutation or deletion of the downstream NF-kappaB site exhibited about 50% reduction in promoter activity in response to a cytokine mixture, whereas either mutation or deletion of the upstream NF-kappaB site reduced promoter activity by 90%, suggesting that the latter site is the most important, and that co-existence of two NF-kappaB sites is necessary for iNOS induction. Nuclear NF-kappaB activity was robustly induced by TNF-alpha. However, TNF-alpha alone did not induce iNOS promoter activity, protein expression, or nitrite production, indicating that NF-kappaB activation alone is not sufficient for iNOS induction. The construct up to -890 bp, containing the downstream NF-kappaB site, exhibited little response to cytokines. The construct up to -1.0 kb, containing the two NF-kappaB sites exhibited only 22% of full promoter activity. The regions -1001 to -1368 bp and -2 to -2.5 kb contributed an additional 43 and 22% promoter activity, respectively. Internal deletion or reversal of the orientation of -1001 to -1368 bp in the full promoter resulted in 40% reduction in promoter activity. These data suggest that the co-existence of two NF-kappaB sites is essential for core promoter activity, but that full induction of the rat SMC iNOS gene requires other elements located between -1.0 to -1.37 and -2.0 to -2.5 kb of the promoter.

Animals↗

PubMed2000

Vitamin D status and parathyroid hormone concentrations in Chinese women and men from north-east of the People's Republic of China.

STUDY OBJECTIVE: To evaluate vitamin D status of young and old women and men living in Shenyang, north-east People's Republic of China in early spring and to explore the relationship between vitamin D metabolites and parathyroid hormone (PTH) in this population. DESIGN: Cross-sectional study. SETTING: Shenyang, north-east China. SUBJECTS: 194 healthy volunteers: 48 young women and 48 young men aged 25-35 y, and 48 old women and 50 old men aged 65-75 y. RESULTS: Fasting blood samples were used to measure plasma 25-hydroxyvitamin D (25(OH)D), 1,25-dihydroxyvitamin D (1,25(OH)2D) and PTH using radioimmunoassays. The proportion of subjects who could be regarded as vitamin D deficient (<25 nmol/l) was 48%, 29%, 15% and 13% for old men, young men, old women and young women, respectively. There was no association between plasma 1,25(OH)2D and 25(OH)D concentrations. PTH concentrations were elevated in both old women and men compared with young subjects (P<0.01). A negative association between PTH and 25(OH)D was only found in old women (P<0. 001), but not in old men, nor in young subjects. CONCLUSIONS: Vitamin D status was poor in this population in early spring, especially in men. There was no clear evidence to show that the secretion of PTH and the conversion of 1,25(OH)2D were affected by the low 25(OH)D concentration. SPONSORSHIP: Partly supported by the Sandoz Foundation for Gerontological Research and the Nestlé Foundation, Switzerland, and Medical Research Council, UK. European Journal of Clinical Nutrition (2000) 54, 68-72

Adult↗

PubMed2000

Urologic status of 74 spinal cord injury patients from the 1976 Tangshan earthquake, and managed for over 20 years using the Credé maneuver.

OBJECTIVE: To evaluate the urologic safety of long-term Credé maneuver as bladder management in spinal cord injured patients. METHODS: Seventy-four paraplegics were included in this cross-sectional study. They were injured in the Tangshan earthquake in 1976. All patients have large volume (flaccid) bladders and have practiced the Credé maneuver for more than 20 years to expel urine. Current residual urine volume and urologic complications were investigated. RESULTS: 93.2% of patients have residual urine larger than 100 ml and 50% of cases larger than 300 ml. The prevalence of urologic complications is high: pyuria in 82.4%, urinary lithiasis in 31.3%, ureteral dilatation in 59.5%, hydronephrosis in 35.1% and renal damage in 16.2%. Men are more susceptible to upper urinary tract deterioration than women (P<0.05). CONCLUSION: The Credé maneuver is not safe for long-term use in spinal cord injury patients, especially in men.

Adult↗

PubMed2000

The high-sensitivity determination of protein concentrations by the enhancement of Rayleigh light scattering of Arsenazo-DBN.

A new Rayleigh light scattering (RLS) assay of protein is presented in this paper. At the optimum pH 4.10, the weak RLS of Arsenazo-DBN can be greatly enhanced by the addition of proteins due to the interaction between protein and Arsenazo-DBN. Based on this, the reactions of Arsenazo-DBN and proteins, including bovine serum albumin, human serum album, gamma-globulin, egg albumin, lysozyme and trypsin, were studied. A new quantitative determination method for proteins has been developed. The linear range for human serum albumin, for example, is 0.085-34.62 micrograms mL-1 with a detection limit of 44.8 ng mL-1. Besides high sensitivity, the method is characterized by good reproducibility, rapidity of reaction, good stability, and few interfering substances. The determination of the proteins in human serum and urine samples by this method give results very close to those obtained using Coomassie Brilliant Blue G-250 colorimetry, with relative standard deviations of 0.7-2.5%.

Arsenazo III↗

PubMed2000

Preliminary studies of a fast screening method for polycyclic aromatic hydrocarbons in soil by using solvent microextraction-gas chromatography.

Solvent microextraction (SME) was applied to the extraction of polycyclic aromatic hydrocarbons (PAHs) from spiked and real environmental soil samples with different matrices. Soil sample was mixed with 7 mL of acetone and 14 mL of water to allow partitioning of the PAHs from the soil to the liquid phase. A 2 microL octane drop suspended from a microsyringe needle tip was then immersed into the stirred solution-soil mixture for extraction. After an 11 min extraction, the octane drop was withdrawn into the syringe and injected directly into the GC for identification and quantification. The whole analysis procedure took 27 min, with an extraction time of 11 min, and a GC separation time of 16 min. A second extraction could be undertaken whilst the GC is running, hence the GC run time currently limits the sample throughput. In this method, a small amount of organic solvent was used for the extraction process, which produced little waste. The limits of detection for lower molecular weight (< 230) PAHs range from 0.13 to 0.36 mg kg-1, and for higher molecular weight (> 250) PAHs are estimated to be between 0.5 and 1.0 mg kg-1, with RSD values generally under 20%. Due to the small volumes of organic solvent used, the consumable cost per extraction is only US$ 0.12. This is the first report of the application of SME to solid samples, and the first report of the use of SME for the analysis of PAHs.

Acetone↗

PubMed2000

Post-earthquake quality of life and psychological well-being: longitudinal evaluation in a rural community sample in northern China.

This study aims to observe longitudinal change of quality of life (QOL) and psychological well-being in a community sample affected by an earthquake and to examine the relationship between QOL and disaster exposure, post-disaster support and other related variables. The subjects, from two villages at different distances from the epicenter, were assessed using the brief version of the World Health Organization Quality of Life Assessment (WHOQOL-BREF) and three subscales of a symptoms checklist at 3 months (n=335) and 9 months (n=253) after the earthquake, respectively. Exposure to the earthquake was associated with multidimensional impairment in QOL, including physical, psychological and environmental domains at 3 months, and psychological and environmental domains at 9 months. The victims also suffered significantly more psychological distress in terms of depression, somatization and anxiety. At both assessment points the group that experienced lower initial exposure but then received less post-disaster help reported poorer QOL and psychological well-being. The two victim groups also differed significantly in changing trend along time. The group that received more support showed a general improvement in post-disaster well-being from 3 months to 9 months. The results confirm that post-disaster variables could be as important to post-disaster psychosocial outcomes as variables of pre-disaster vulnerability and disaster per se. A comprehensive and prospective assessment of disaster effects is imperative for the better organization of disaster relief programs and psychosocial interventions.

Adolescent↗

PubMed2000

Deficit in conditional visuomotor learning by local infusion of bicuculline into the ventral prefrontal cortex in monkeys.

To explore the role of the ventral prefrontal cortex (PFv) in conditional visuomotor learning, we infused locally bicuculline, a GABAergic antagonist, into the PFv of two monkeys, well trained on a two-problem visuomotor task. The task required the monkeys to execute one of two motor actions (moving a handle to the left or to the right) in response to one of two familiar visual patterns (circle or triangle). The two patterns mapped 1:1 onto the two motor actions: for each pattern one and only one motor action was scored, correct and reinforced. In contrast to these sessions with familiar patterns, in the learning sessions the monkeys were presented with one or two novel patterns and required to learn the arbitrarily determined associations between these patterns and the two motor actions. We found that bilateral infusion of bicuculline into PFv dramatically impaired the monkeys' ability to learn novel pattern-response associations: the trials and errors to criterion (90% correct) increased significantly. The errors were mainly an inability to apply 'Win-Stay', 'Lose-Shift' and 'Change-Shift' strategies. There was no effect on the monkeys' performance in responding to familiar patterns. Similar infusion of bicuculline into the dorsal prefrontal cortex was without effect on either novel-pattern learning or familiar-pattern performance. We conclude that the ventral prefrontal cortex is necessary for learning new visuomotor associations, but has less importance, if any, for performing pre-established ones.

Animals↗

PubMed2000

Novel mode of nitric oxide neurotransmission mediated via S-nitroso-cysteinyl-glycine.

S-nitroso-cysteinyl-glycine, a novel nitric oxide-adduct thiol compound, can be detected in the brain (2.3+/-0.6 pmol/mg protein), and released following stimulation of sensory afferents to the rat ventrobasal thalamus in vivo (resting conditions 17 nM; stimulation: 186 nM). Iontophoretic application of CysNOGly (20-80 nA) onto thalamic neurons in vivo resulted in enhancements of excitatory responses to either NMDA or AMPA (182+/-13.6% and 244+/-27.8% of control values, n = 15). CysNOGly enhanced responses to stimulation of vibrissal afferents to 132+/-2.2% (n = 7) of control values. In contrast, the dipeptide CysGly reduced responses of ventrobasal neurons to NMDA and AMPA (54+/-8.4% and 55+/-10.8% of control, n = 5). CysNOGly was also a potent activator of soluble guanylate cyclase in vitro. Moreover, we found that NMDA elevated CysNOGly levels in vitro and this stimulatory effect was reduced by inhibitors of the neuronal NO synthase and of the gamma-glutamyl transpeptidase, suggesting that production of NO and CysGly is a prelude to CysNOGly synthesis. These findings suggest that the nitrosothiol CysNOGly plays a role in synaptic transmission in the ventrobasal thalamus. We propose a novel synaptic buffering mechanism where S-nitroso-cysteinyl-glycine serves to restrict the locus of action of nitric oxide and so increase its local availability for target delivery. This could lead to a change in neuronal responses favouring sensory transmission similar to that seen in wakefulness or arousal in order to locally enhance transmission of persistent sensory stimuli.

Afferent Pathways↗