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Biomedical subjects

Lei Yu

Publications and source records attributed to Lei Yu.

At least 37 records · Page 2Linked to original sources
PubMed2006

Risk factors for primary hepatocellular carcinoma in black and white Americans in 2000.

BACKGROUND & AIMS: The incidence of primary hepatocellular carcinoma (HCC) is greater in black Americans compared with white Americans. The aim of this study was to better define racial disparity in HCC patients in the United States. METHODS: We compared HCC risk factors in 158 black and 701 white HCC patients > or = 11 years of age in the Nationwide Inpatient Sample for 2000. RESULTS: Black HCC patients were younger than white patients (mean age, 54.1 +/- 17.1 vs. 65.1 +/- 13.7 y; P < .002). Sixty-two percent of black HCC patients were age 60 or younger, whereas 68% of white HCC patients were age 61 or older. Hepatitis C virus (HCV) (25.4%), diabetes (22.1%), alcohol (15.1%), cryptogenic cirrhosis (8.6%), and hepatitis B virus (HBV) (7.3%) were the most prevalent risk factors for HCC overall. HBV (22.8% vs 3.9%, P < .0001; adjusted odds ratio [OR], 5.3; 95% confidence interval [CI], 3.0-9.2), HCV (34.8% vs 23.3%, P = .0003; OR, 1.3; 95% CI .9-1.9), concurrent HBV and HCV (8.2% vs 1.7%, P < .0001; OR, 4.5; 95% CI, 1.9-10.4), HBV plus diabetes (2.5% vs .3%, P = .002; OR, 14.1; 95% CI, 2.2-88.2), and HCV plus diabetes (8.9% vs 4.4%, P < .02; OR, 2.3; 95% CI, 1.2-4.6) were more common in black HCC patients. There was no racial difference in the frequency of alcoholic and cryptogenic liver diseases and diabetes. CONCLUSIONS: Higher rates of HBV, HCV, concurrent HBV and HCV, and viral hepatitis associated with diabetes might explain the greater burden of HCC in black Americans.

Adolescent↗
PubMed2006

Long-term cognitive impact of anticholinergic medications in older adults.

OBJECTIVE: The objective of this study was to determine whether chronic use of medications with anticholinergic (AC) properties impact older adults' cognitive functioning. METHODS: Six years of cognitive test data from two groups of older adults (AC and control) were examined retrospectively (N = 592). RESULTS: Declines over time were found for the AC group on parts A and B of the Trail Making Test. CONCLUSION: Physicians prescribing ACs to older adult patients should be aware of their potential effects on psychomotor speed and executive functioning. These cognitive effects may lead to impairments in daily functioning resulting in the need to reevaluate patient medications.

Aged↗
PubMed2006

Effect of GNTI, a kappa opioid receptor antagonist, on MK-801-induced hyperlocomotion and stereotypy in mice.

AIM: To examine the effect of GNTI [5'-guanidinyl-17-(cyclopropylmethyl)-6,7- dehydro-4,5alpha-epoxy-3,14-dihydroxy-6,7-2',3'-indolomorphinan], a selective antagonist for the kappa opioid receptor, in the MK-801 (dizocilpine maleate)-induced behavioral model of psychosis in schizophrenia as a way to explore the involvement of the kappa opioid receptor in modulating psychotic symptoms of schizophrenia. METHODS: Two doses of MK-801 (0.3 mg/kg and 0.6 mg/kg) were administered by systemic injection in mice to induce psychosis-like behavior as a rodent schizophrenia model, preceded by an injection of different doses of GNTI. Both locomotion and stereotypy were measured as the behavioral endpoints for quantitative analysis. RESULTS: GNTI inhibited MK-801-induced hyperlocomotion and stereotypy. In particular, GNTI showed differential modulation of stereotypy induced by 0.3 mg/kg vs 0.6 mg/kg MK-801. CONCLUSION: Antagonism of kappa opioid receptors attenuates MK-801-induced behavior, suggesting a potential involvement of the kappa opioid receptor in psychosis-like symptoms of schizophrenia. GNTI appears to be a useful pharmacological tool to explore the kappa opioid receptor function in vivo.

Animals↗
PubMed2006

Application of Gleason analogous grading system and flow cytometry DNA analysis in a novel knock-in mouse prostate cancer model.

OBJECTIVE: A new knock-in mouse adenocarcinoma prostate model (KIMAP) was established, which showed a close to human kinetics of tumour development. This study used a new mouse histological grading system similar to the human Gleason grading system and flow cytometry DNA analysis to measure and compare the new KIMAP model with human CaP and transgenic mouse adenocarcinoma prostate (TGMAP) model. METHODS: According to heterogeneity of the clinical standard for prostate cancer diagnosis, a close to human mouse standard for histological grading and scoring system, Gleason analogous grading system, was established in this study. Sixty KIMAP and 48 TGMAP prostate cancer samples were measured and compared with human CaP. Flow cytometry DNA analysis was performed on malignant prostate tissues obtained from both TGMAP and KIMAP models. RESULTS: Mice with CaP from KIMAP (n = 60) and TGMAP (n = 48) models showed a different distribution of histological scores (p = 0.000). KIMAP mice showed higher percentage (53.3%) of compound histological score rate than TGMAP (25%), but closer to the human clinical average (50%), which showed significant correlation with age (p = 0.001), while TGMAP mice showed unbalanced and random score distribution in all age groups. Flow cytometry analyses showed that most tumour tissues in KIMAP were diploid, analogous to the human condition, while all the TGMAP mice showed aneuploid tumours. CONCLUSIONS: Results of this study further show that KIMAP, a new generation of murine prostate cancer model, could be used as a supplementary model in addition to the currently widely used transgenic models.

Adenocarcinoma↗
PubMed2006

Transient reduction of PTI-1 expression by short interfering RNAs inhibits the growth of human prostate cancer cell lines.

The prostate tumor-inducing gene 1 (PTI-1) was originally identified by differential ribonucleic acid (RNA) display in human prostate carcinoma. PTI-1 is expressed in human prostate carcinoma but not in benign prostate hypertrophy or normal prostate tissue. PTI-1 may be a member of oncogenes that could affect protein translation and contribute to carcinoma development in human prostate. To investigate the role of PTI-1 in human prostate carcinoma, we constructed three different short interfering RNA (siRNA) vectors (pSilencer3.1-neo-Yu Lei [YL]1-2, -YL3-4 and -YL5-6), each of which was transfected into DU145 and PC3 human prostate cancer cell lines. Among these siRNAs, only pSilencer3.1-neo-YL1-2 could almost completely block the expression of PTI-1 in these two cell lines. The growth of the cell lines was then evaluated after transfection. The proliferation rate was retarded in DU145 and PC3 cells transfected with pSilencer3.1-neo-YL1-2, compared with the cells transfected with a control vector; namely, about 88.6% of DU145 and 80.2% of PC3 cancer cells were blocked at the G1 phase when transfected with pSilencer3.1-neo-YL1-2, compared to 62.0% in DU145 cells and 51.7% in PC3 cells, transfected with the control vector. Moreover, 68.3% of DU145 cells and 72.3% of PC3 cells were induced into apoptosis, while in control transfection, the population was 26.6% in DU145 cells and 28.4% in PC3 cells. These results indicate that blocking PTI-1 expression can inhibit the growth of certain prostate cancer cell lines. We suggest that PTI-1 may serve as a target for the gene-based therapy of human prostate carcinoma.

Adenocarcinoma↗
PubMed2006

[Effect of Sudan I, III and IV on proliferation of HepG-2 and SGC-7901].

To study the effect of sudan I, III and IV on the growth of HepG-2 and SGC-7901, the ratio of DNA/RNA and 3D image in HepG-2 treated by different dose of sudan I, III and IV was detected by LCM, the content change of DNA and the cell cycle in SGC-7901 treated by different dose of sudan I, III and IV was detected by flow cytometry. Results showed the ratio of DNA/RNA in control group was 1.2232 +/- 0.0844, after treated by sudan I , III and IV the fluorescence intensity of DNA was stronger than RNA, and the low dose group was very marked compared with control group (p < 0.01), the ratio was 1.609 6 +/- 0.1990, 1.4455 +/- 0.1633,and 1.7081 +/- 0.1090. 3D image showed that the DNA fluorescence mostly assembles on nucleolus, which was denser and stronger than RNA. Sudan I, III and IV accelerated the cell cycle from G1 phase to S and G2 phase, the average content of DNA in G1 phase decreased and in S and G2 phase increased, the index of PI and SPF increased. Sudan I, III and IV could affect cell cycle and advanced its differentiation and proliferation.

Apoptosis↗
PubMed2006

[Construction of artificial nerve bridge by three-dimensional culture of interleukin-1beta- activated Schwann cells with human hair keratins].

OBJECTIVE: To culture interleukin-1beta (IL-1beta)-activated Schwann cells (SCs) with human hair keratins (HHKs) for artificial nerve bridge construction. METHODS: SCs purified by primary culture with or without IL-1beta activation were cultured with HHKs decorated by extracellular matrix (ECM), and the artificial nerve bridge was implanted into the defect of rat sciatic nerve. The morphology of the SCs cultured with HHKs was monitored by inverted microscope, scanning electron microscope and evaluated by immunocytochemical staining, and the expression of nerve growth factor (NGF) in the sciatic nerve was observed by in situ hybridization. RESULTS: Activated SCs showed better ability to adhere to the HHKs and grew well. The HHKs component in the artificial nerve bridge underwent degradation in the sciatic nerve defect after 3 to 4 weeks, and IL-1beta activation resulted in enhanced NGF expression in the SCs. CONCLUSION: The constructed artificial nerve bridge by three-dimensional culture of IL-1beta-activiated SCs with HHKs decorated by ECM promotes the repair of sciatic nerve defects and accelerates sciatic nerve regeneration.

Animals↗
PubMed2005

Engineered recombinant single-chain fragment variable antibody for immunosensors.

A recombinant single-chain fragment variable (scFv) antibody (designated A10B) was engineered to contain two histidines within the linker peptide used to join the scFv heavy and light chains. A piezoimmunosensor using the scFv was successfully developed. A10B scFv bound to the gold piezoimmunosensor surface were correctly oriented, retained antigen-binding activity, and coupled at high surface concentration. These results, and results obtained from an earlier study using an scFv containing a linker cysteine, suggest that the location on the linker sequence in which the amino acids were incorporated was well tolerated by the scFv and did not interfere with scFv antigen-binding activity. The scFv-modified QCM sensor was thoroughly characterized and used to specifically detect antigen in crude serum sample and had a sensitivity of 2.3 +/- 0.15 nM (n = 4) with a linear range over 2.3 x 10(-9) - 3.3 x 10(-(8) M. The piezoimmunosensor was also used to study the kinetics and thermodynamics of antigen/scFv antibody binding.

Amino Acid Sequence↗
PubMed2005

Identification of a novel protein for memory regulation in the hippocampus.

Memory formation, maintenance, and retrieval are a dynamic process, reflecting a combined outcome of new memory formation on one hand, and older memory suppression/clearance on the other. Although much knowledge has been gained regarding new memory formation, less is known about the molecular components and processes that serve the function of memory suppression/clearance. Here, we report the identification of a novel protein, termed hippyragranin (HGN), that is expressed in the rat hippocampus and its expression is reduced by hippocampal denervation. Inhibition of HGN by antisense oligonucleotide in area CA1 results in enhanced performance in Morris water maze, as well as elevated long-term potentiation. These results suggest that HGN is involved in negative memory regulation.

Animals↗
PubMed2005

A simple isomeric separation of D5h and Ih Sc3N@C80 by selective chemical oxidation.

Two electrochemical oxidation waves assigned to the D(5h) isomer of Sc(3)N@C(80) have been identified, and a 270-mV difference in the first electrochemical oxidation potentials of the I(h) and D(5h) isomers has been measured. On the basis of this oxidative potential difference, a strategy for isomeric purification involving a selective chemical oxidation of the D(5h) isomer is reported. Variable scan cyclic voltammetry of the resultingly pure Sc(3)N@C(80) I(h) isomer shows evidence of a rapid endohedral chemical reaction following the first reduction process.

Journal Article↗
PubMed2005

Adsorption of 1,10-phenanthroline within a dodecanethiol monolayer: an approach to a switchable electrode surface.

A simple method was used to prepare a "switchable" electrode surface by using self-assembled monolayers of dodecanethiol on a gold electrode. The dodecane-modified electrode was electrochemically inactive until the monolayer was soaked in solutions of 1,10-phenanthroline or 2,2'-bipyridine. The electroactive form of the electrode could be reverted back to the nonelectroactive form by rinsing the electrode. Surface IR results showed that both dodecanethiol and 1,10-phenanthroline exist in the mixed monolayer.

2,2'-Dipyridyl↗
PubMed2005

Ionic liquid high temperature gas sensors.

An ionic liquid piezoelectric gas sensor was demonstrated for detection of polar and nonpolar organic vapors at high temperature with fast linear and reversible response.

Biosensing Techniques↗
PubMed2005

Single-chain fragment variable antibody piezoimmunosensors.

In this paper, we describe a novel nonlabeled biosensor with high diagnostic potential for rapid and sensitive detection of antigens in complex biological samples. The biosensor comprises a piezoimmunosensor (PZ) displaying a specially constructed recombinant antibody on its surface. The recombinant single-chain fragment variable (scFv) antibody contained a cysteine within the linker amino acid sequence used to join the scFv variable heavy and light chains. The presence of cysteine induced the scFv construct to self-assemble as a densely packed rigid monolayer on the gold surface of a quartz crystal microbalance. scFv molecules in this self-assembled monolayer (SAM) exhibited a defined orientation and high areal densities, with scFv-modified microbalance surfaces displaying 35 times as many variable antigen-binding sites per square centimeter as surfaces modified with whole antibody. Experimental data show that the scFv SAM PZ is superior to Fab fragment, Fab fragment containing a free sulfhydryl group (i.e., Fab-SH), and whole antibody PZs regarding sensitivity and specificity. Because of their small uniform size (MW approximately 27000) and the ease with which they can be modified using genetic engineering, scFv's have significant advantages over whole antibodies in microbalance biosensor systems. We demonstrate here that the use of scFv containing a cysteine within the scFv linker sequence (i.e., scFv-cys) for preparation of biosensor surfaces markedly increases the density of available antigen-binding sites, yielding a system that is highly selective, rapid, and capable of detecting low concentrations of antigens in complex samples.

Amino Acid Sequence↗
PubMed2005

Neuropathic pain: early spontaneous afferent activity is the trigger.

Intractable neuropathic pain often results from nerve injury. One immediate event in damaged nerve is a sustained increase in spontaneous afferent activity, which has a well-established role in ongoing pain. Using two rat models of neuropathic pain, the CCI and SNI models, we show that local, temporary nerve blockade of this afferent activity permanently inhibits the subsequent development of both thermal hyperalgesia and mechanical allodynia. Timing is critical-the nerve blockade must last at least 3-5 days and is effective if started immediately after nerve injury, but not if started at 10 days after injury when neuropathic pain is already established. Effective nerve blockade also prevents subsequent development of spontaneous afferent activity measured electrophysiologically. Similar results were obtained in both pain models, and with two blockade methods (200mg of a depot form bupivacaine at the injury site, or perfusion of the injured nerve just proximal to the injury site with TTX). These results indicate that early spontaneous afferent fiber activity is the key trigger for the development of pain behaviors, and suggest that spontaneous activity may be required for many of the later changes in the sensory neurons, spinal cord, and brain observed in neuropathic pain models. Many pre-clinical and clinical studies of pre-emptive analgesia have used much shorter duration of blockade, or have not started immediately after the injury. Our results suggest that effective pre-emptive analgesia can be achieved only when nerve block is administered early after injury and lasts several days.

Action Potentials↗
PubMed2005

A new mitochondrial RNA deletion fragment accelerated by oxidative stress in rat L6 cells.

RNA deletions may be easier to detect and more extensive than DNA deletions. Two large deletion fragments (1120 and 7811 bp) of mitochondrial RNA were observed in rat L6 muscle cells. At the site of the 1120 bp deletion, the remaining RNA fragment was re-linked by a short additional section (GGTATGAAGCT). These kinds of deletions were accelerated by oxidative stress and were not observed in mitochondrial DNA.

Animals↗
PubMed2005

RSEP1 is a novel gene with functional involvement in neuropathic pain behaviour.

Neuropathic pain from nerve injury by trauma, disease or surgery often causes prolonged suffering. To explore the molecular mechanisms that underlie neuropathic pain, we used mRNA from the L4--5 segments of the lumbar spinal cord of rats with chronic constriction injury (CCI)-induced neuropathic pain, and differentially screened a cDNA library from the rat brain. A novel gene, termed RSEP1 (Rat Spinal cord Expression Protein 1), was identified. Northern blots revealed that RSEP1 was expressed mainly in the central nervous system including the cerebral cortex, hippocampus, brainstem and spinal cord, as well as in the kidney and ovary. In situ hybridization showed a high level of RSEP1 expression in the CA1, CA3 and dentate gyrus regions of the hippocampus and the small sensory neurons in the dorsal horn, as well as the large neurons in the ventral horn of the spinal cord. Intrathecal injection of RSEP1 antisense oligonucleotide into the spinal cord lumbar enlargement attenuated neuropathic pain behaviours in CCI rats, suggesting a functional involvement of RSEP1 in neuropathic pain.

Animals↗
PubMed2005

The use of three-dimensional ultrasound micro-imaging to monitor prostate tumor development in a transgenic prostate cancer mouse model.

Longitudinal studies of mouse cancer models required large cohorts since autopsy was the only reliable method to evaluate treatment efficacy. This paper reports the use of high-resolution three-dimensional ultrasound micro-imaging to monitor prostate tumor development in genetically engineered mice. Twenty-nine genetically engineered prostate cancer mice, including castrated and uncastrated mice, were imaged by three-dimensional ultrasound. Qualitative comparisons of three-dimensional ultrasound images with histology sections of prostate tumors demonstrate the ability of ultrasound to accurately depict the size and shape of malignant masses in live mice. The correlation coefficient of tumor diameter measurements performed in vivo with three-dimensional ultrasound and at autopsy was 0.997. Prospective tumor detection sensitivity and specificity were 91.7% and 100%. Representative exponential growth curves constructed via longitudinal ultrasound imaging indicated diameter doubling times from 10 to 37 days for four prostate tumors during an initial period of rapid progression. Three-dimensional ultrasound will likely become the micro-imaging modality most readily adopted for mouse pre-clinical trial studies.

Animals↗