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Biomedical subjects

Xin Yu

Publications and source records attributed to Xin Yu.

At least 73 records · Page 4Linked to original sources
PubMed2003

Improved molecular imaging contrast agent for detection of human thrombus.

Molecular imaging of microthrombus within fissures of unstable atherosclerotic plaques requires sensitive detection with a thrombus-specific agent. Effective molecular imaging has been previously demonstrated with fibrin-targeted Gd-DTPA-bis-oleate (BOA) nanoparticles. In this study, the relaxivity of an improved fibrin-targeted paramagnetic formulation, Gd-DTPA-phosphatidylethanolamine (PE), was compared with Gd-DTPA-BOA at 0.05-4.7 T. Ion- and particle-based r(1) relaxivities (1.5 T) for Gd-DTPA-PE (33.7 (s*mM)(-1) and 2.48 x 10(6) (s*mM)(-1), respectively) were about twofold higher than for Gd-DTPA-BOA, perhaps due to faster water exchange with surface gadolinium. Gd-DTPA-PE nanoparticles bound to thrombus surfaces via anti-fibrin antibodies (1H10) induced 72% +/- 5% higher change in R(1) values at 1.5 T (deltaR(1) = 0.77 +/- 0.02 1/s) relative to Gd-DTPA-BOA (deltaR(1) = 0.45 +/- 0.02 1/s). These studies demonstrate marked improvement in a fibrin-specific molecular imaging agent that might allow sensitive, early detection of vascular microthrombi, the antecedent to stroke and heart attack.

Contrast Media↗
PubMed2003

Ku-dependent and Ku-independent end-joining pathways lead to chromosomal rearrangements during double-strand break repair in Saccharomyces cerevisiae.

Chromosomal double-strand breaks (DSBs) can be repaired by either homology-dependent or homology-independent pathways. Nonhomologous repair mechanisms have been relatively less well studied, despite their potential importance in generating chromosomal rearrangements. We have developed a Saccharomyces cerevisiae-based assay to identify and characterize homology-independent chromosomal rearrangements associated with repair of a unique DSB generated within an engineered URA3 gene. Approximately 1% of successfully repaired cells have accompanying chromosomal rearrangements consisting of large insertions, deletions, aberrant gene conversions, or other more complex changes. We have analyzed rearrangements in isogenic wild-type, rad52, yku80, and rad52 yku80 strains, to determine the types of events that occur in the presence or absence of these key repair proteins. Deletions were found in all strain backgrounds, but insertions were dependent upon the presence of Yku80p. A rare RAD52- and YKU80-independent form of deletion was present in all strains. These events were characterized by long one-sided deletions (up to 13 kb) and extensive imperfect overlapping sequences (7-22 bp) at the junctions. Our results demonstrate that the frequency and types of repair events depend on the specific genetic context. This approach can be applied to a number of problems associated with chromosome stability.

Antigens, Nuclear↗
PubMed2003

Randomized, placebo-controlled trial of the effects of donepezil on neuronal markers and hippocampal volumes in Alzheimer's disease.

OBJECTIVE: The authors examined the effect of the acetylcholinesterase inhibitor donepezil on magnetic resonance markers of neurodegeneration in Alzheimer's disease. METHOD: In this randomized, double-blind, placebo-controlled pilot study, 67 patients with mild to moderate Alzheimer's disease received 24 weeks of treatment with donepezil (5 mg/day for the first 28 days and 10 mg/day thereafter) or placebo. Patients were reevaluated at 6-week intervals to measure change from baseline in several outcome measures, including right, left, and total hippocampal volumes, measured with magnetic resonance imaging; brain concentrations of N-acetylaspartate, measured with proton magnetic resonance spectroscopy; and cognition, assessed with the Alzheimer's Disease Assessment Scale cognitive subscale. RESULTS: At some interim assessments, mean normalized measures of N-acetylaspartate concentration tended to be higher in the donepezil-treated patients than in the patients who received placebo, but these differences were not significant at endpoint. At endpoint, the donepezil-treated patients had significantly smaller mean decreases in total and right hippocampal volumes and a smaller, nearly significant mean decrease in left hippocampal volume, compared with the placebo-treated patients. Mean Alzheimer's Disease Assessment Scale cognitive subscale scores were improved after treatment with donepezil, relative to placebo, at weeks 6, 12, 18, and 24. CONCLUSIONS: These preliminary results suggest that donepezil may have a potentially protective effect in Alzheimer's disease. Larger, longer-term confirmatory studies of the medication's effects are warranted.

Aged↗
PubMed2003

Influence of Kupffer cells on hepatic signal transduction as demonstrated by second messengers and nuclear transcription factors.

AIM: To understand the influence of Kupffer cell (KC) on signal transduction pathways in the liver. METHODS: To decrease selectively the number and function of KC, Kunming mice were ip injected with a single dose of gadolinium chloride (GdCl3, 20 mg x kg(-1)), the time-effect relationship assessment was performed after 1 d, 3 d and 6 d. sALT, sGST, liver glycogen content, phagocytic index, and expression of CD68 were assessed as the indexes of hepatotoxicity and functions of KC respectively, and morphology of KC was observed with transmission electron microscopy. Furthermore, cAMP, PGE2 level, nitric oxide (NO) content, and mRNA expression of NFkappaBp65, Erk1, STAT1 were examined. RESULTS: GdCl3 could selectively cause apoptosis of KC and obvious reduction of KC's activity, but no hepatotoxicity was observed. One day after KC blockade, NO, PGE2, cAMP contents in the liver were reduced 21.0%, 6.94-fold, 8.3%, respectively, and mRNA expression of NFkappaBp65 was decreased 3.0-fold. The change tendency of NO, PGE2, and cAMP contents and mRNA expression of NFkappaBp65 were concomitant with recovery of the functions of KC. The contents of NO, PEG2, cAMP were increased when the functions of KC was recovered. However, all of the changes could not return to the normal level except NO content after 6 d Gdcl3 treatment. No obvious changes were found in STAT1 and Erk1 mRNA expression in the present study. CONCLUSION: Hepatic NO, PGE2, cAMP level and mRNA expression of NFkappaBp65 are closely related with the status of KC. It suggests that KC may play an important role in the cell to cell signal transduction in the liver.

Alanine Transaminase↗
PubMed2003

Endoscopic patterns of gastric mucosa and its clinicopathological significance.

AIM: To explore the correlation of magnifying endoscopic patterns and histopathology, Helicobacter pylori (H pylori) infection of the gastric mucosa. METHODS: Gastric mucosal patterns in 140 patients with chronic gastritis were studied using Olympus GIF-Q240Z magnifying endoscope. Histopathological examination, rapid urease test and Warrthin-Starry staining were taken with biopsy samples from the magnified sites of stomach. The magnifying endoscopic patterns were compared with histopathological results and H pylori detection. RESULTS: The pit patterns of gastric mucosa were classified as types A (round spot), B (short rod), C (branched), D (reticular) and E (villus). The detection rate of chronic atrophic gastritis (CAG) by magnifying endoscopy was 94.3% (33/35), which was significantly higher than that by routine endoscopy (22.9%, 8/35) (P<0.01). The pit patterns of 31 cases of intestinal metaplasia (IM) appeared as type E in 18 cases (58.1%), type D in 8 cases (25.8%) and type C in 5 cases (16.1%). Fourteen out of 18 patients (77.8%) with complete type (type I) of IM appeared as type E of pit patterns, whereas only 4 of 13 (30.8%) patients with incomplete type (types II and III) of IM appeared as type E (P<0.05). Collecting venules in the anterior of lower part of gastric corpus were subgrouped into types R (regular), I (irregular) and D (disappeared). H pylori infection was found in 12.2%(9/74), 60%(9/15) and 84.3%(43/51) cases in these types respectively. H pylori infection rate in type R was significantly lower than that in other two types (P<0.01). CONCLUSION: Magnifying endoscopy may have an obvious value in diagnosing chronic atrophic gastritis, intestinal metaplasia and H pylori infection.

Adolescent↗
PubMed2003

Modulation of GdCl3 and Angelica sinensis polysaccharides on differentially expressed genes in liver of hepatic immunological injury mice by cDNA microarray.

AIM: To study the modulating effect of GdCl(3) and Angelica Sinensis polysaccharides (ASP) on differentially expressed genes in liver of hepatic immunological mice by cDNA microarray. METHODS: Hepatic immunological injury was induced by lipopolysaccharide (LPS ip, 0.2 mg/kg(-1)) in bacillus calmetteguerin (BCG ip, 1 mg/kg(-1)) primed mice; A single dose of 20 mg/kg(-1) GdCl(3) was simultaneously pretreated and 30 mg/kg(-1) ASP (ig, qdX7 d) was administrated when the BCG+LPS was primed. The mice were sacrificed at the end of the 7(th) day after ip LPS for 6 h and the liver was removed quickly. The PCR products of 512 genes were spotted onto a chemical material-coated glass plate in array. The DNAs were fixed to the glass plate after series of treatments. The total RNAs were isolated from the liver tissue, and were purified to mRNAs by Oligotex. Both mRNAs from the normal liver tissue and the liver tissue from the mice with hepatic immunological injury or that pretreated with GdCl(3) or ASP were reversely transcribed to cDNAs with the incorporation of fluorescent dUTP to prepare the hybridization probes. The mixed probes were hybridized to the cDNA microarray. After high-stringent washing, the cDNA microarray was scanned for fluorescent signals and showed differences between the two tissues. RESULTS: Among the 512 target genes, 18 differed in liver tissue of hepatic immunological injury mice, and 6 differed in those pretreated by ASP, 7 differed in those pretreated by GdCl(3). CONCLUSION: cDNA microarray technique is effective in screening the differentially expressed genes between two different kinds of tissue. Further analysis of those obtained genes will be helpful to understand the molecular mechanism of hepatic immunological injury and to study the intervention of drug. Both ASP and GdCl(3) can decrease the number of the differentially expressed genes in liver tissue of mice with hepatic immunological injury.

Angelica sinensis↗
PubMed2003

[Phosphorus as a limiting nutrient in drinking water biological treatment].

Bacterial Growth Potential (BGP) method was used to investigate the limiting effect of phosphorus in the biological process for drinking water treatment in a water plant in Huai River basin. BGP was increased by 54% when 50 micrograms.L-1 KH2PO4-P was added to the raw water, while addition of other inorganic nutrients had no significant difference from the addition of phosphorus. The effect of addition of 20 mg.L-1 C6H12O6 to raw water was not so strong as that of 50 micrograms.L-1 KH2PO4-P. The CODMn removal rate of the biological filter was 7.5 percentiles higher than the control one and carbon was the main limiting nutrient in its effluent when phosphorus was added to the raw water, while phosphorus was the main limiting nutrient in the effluent of the control filter. These results suggest that phosphorus was a limiting nutrient and had a stronger limiting effect than carbon on the biological process in this plant thus the removal efficiency of the organic matters could be increased by adding phosphorus to the influent.

Bacteria↗
PubMed2003

Improving removal efficiency of organic matters by adding phosphorus in drinking water biofiltration treatment.

OBJECTIVE: To investigate phosphorus limitation and its effect on the removal efficiency of organic matters in drinking water biological treatment. METHODS: Bacterial growth potential (BGP) method and a pair of parallel pilot-scale biofilters were used for the two objectives, respectively. RESULTS: The addition of phosphorus could substantially increase the BGPs of the water samples and the effect was stronger than that of the addition of carbon. When nothing was added into the influents, both CODMn removals of the parallel biofilters (BF1 and BF2) were about 15%. When phosphate was added into its influent, BF1 performed a CODMn removal, 6.02 percentage points higher than the control filter (BF2) and its effluent had a higher biological stability. When the addition dose was < 20 micrograms.L-1, no phosphorus pollution would occur and there was a good linear relationship between the microbial utilization of phosphorus and the removal efficiency of organic matters. CONCLUSIONS: Phosphorus was a limiting nutrient and its limitation was stronger than that of carbon. The addition of phosphate was a practical way to improve the removal efficiency of organic matters in drinking water biological treatment.

Bacteria↗
PubMed2003

[Complications following gamma knife radiosurgery].

OBJECTIVE: To investigate complication features following gamma knife radiosurgery (GKR), and to assess factors causing complications. METHODS: A retrospective analysis was conducted for 253 patients with intracranial arteriovenous malformation (AVMs), meningiomas, glial neoplasms, germinomas and metastatic cancer, respectively, which were treated with GKR.The incidences of acute, subacute and late complications following GKR were evaluated. Meanwhile, risk factors inducing subacute complications, such as the cell proliferative population of target tissues and location of target in AVM and meningioma, were evaluated, respectively. RESULTS: The subacute complications are the prominent reactions in all the five diseases. There is a significant difference in the incidence rate of subacute complications between early responding tissues and slow responding tissues, central and peripheral AVM, basal and non-basal meningioma. CONCLUSIONS: Subacute complications are the prominent reactions after GKR, and the reactions are almost always reversible. The risk of subacute complications following GKR treatment is correlated to the proliferative cell population in the target tissues and the target location (AVM, meningioma).

Adolescent↗
PubMed2003

Phosphorus limitation in biofiltration for drinking water treatment.

Bacterial growth potential (BGP) method and two parallel pilot-scale biofilters were used to investigate phosphorus limitation and its effect on the removal of organic matters in biofiltration for drinking water treatment. Addition of phosphorus can substantially increase the BGPs of the samples. Its effect was equivalent to that of addition of a mixture of various inorganic nutrients including phosphorus. The biofilter with phosphate added into its influent performed a higher biological stability of the effluent and a higher COD(Mn) removal than the control filter. These results suggested that phosphorus was the limiting nutrient in the biofiltration and the removal efficiency of organic matters could be improved by adding phosphate into the influent.

Bacteria↗
PubMed2002

Targeted antiproliferative drug delivery to vascular smooth muscle cells with a magnetic resonance imaging nanoparticle contrast agent: implications for rational therapy of restenosis.

BACKGROUND: Restenosis is a serious complication of coronary angioplasty that involves the proliferation and migration of vascular smooth muscle cells (VSMCs) from the media to the intima, synthesis of extracellular matrix, and remodeling. We have previously demonstrated that tissue factor-targeted nanoparticles can penetrate and bind stretch-activated vascular smooth muscles in the media after balloon injury. In the present study, the concept of VSMC-targeted nanoparticles as a drug-delivery platform for the prevention of restenosis after angioplasty is studied. METHODS AND RESULTS: Tissue factor-targeted nanoparticles containing doxorubicin or paclitaxel at 0, 0.2, or 2.0 mole% of the outer lipid layer were targeted for 30 minutes to VSMCs and significantly inhibited their proliferation in culture over the next 3 days. Targeting of the nanoparticles to VSMC surface epitopes significantly increased nanoparticle antiproliferative effectiveness, particularly for paclitaxel. In vitro dissolution studies revealed that nanoparticle drug release persisted over one week. Targeted antiproliferative results were dependent on the hydrophobic nature of the drug and noncovalent interactions with other surfactant components. Molecular imaging of nanoparticles adherent to the VSMC was demonstrated with high-resolution T1-weighted MRI at 4.7T. MRI 19F spectroscopy of the nanoparticle core provided a quantifiable approach for noninvasive dosimetry of targeted drug payloads. CONCLUSIONS: These data suggest that targeted paramagnetic nanoparticles may provide a novel, MRI-visualizable, and quantifiable drug delivery system for the prevention of restenosis after angioplasty.

Animals↗
PubMed2002

[Computer-assisted planning for neurosurgery: a clinical study].

OBJECTIVE: To investigate the clinical effect of computer-assisted planning for neurosurgery (CAPN). METHODS: 100 groups of directional targets were randomly sampled. The targets' directional three-dimension coordinates measured with CAPN and those measured by traditional reading device were analyzed statistically. CAPN was actualized in 137 cases of stereotactic operation. RESULTS: The data measured with CAPN and those with traditional reading device were analyzed with two samples. The paired t test showed no statistically significantly difference between the data of targets measured by both methods (t < t(0.05/2,99)=1.984, P >< 0.05). Different kinds of operation based on CAPN were performed upon 137 cases success fully. CAPN was proved reliable. All operations were successful and the clinic effects satisfactory. CONCLUSION: CAPN is accurate and reliable, and has positive effect on the improvement of stereotactic neurosurgery.

Adolescent↗
PubMed2002

[Neuropathy in nearby cranial nerves after acoustic schwannoma gamma knife radiosurgery, a follow-up study].

OBJECTIVE: To investigate the risks of facial, trigeminal and acoustic neuropathies after acoustic schwannoma gamma knife radiosurgery. METHODS: The clinical data of forty-three patients with 46 masses of acoustic schwannoma who underwent gamma knife radiosurgery with the dose of 12 approximately 15 Gy to the tumor margin between January 1997 and October 2000 and were followed up for 6 approximately 24 months (on average 16.9 months) were studied. The tumor diameter was 10 approximately 20 mm in 12 cases, 21 approximately 30 mm in 23 cases, >/= 31 mm in 11 cases, with the average value of 28 mm. RESULTS: The general tumor control rate was 91.3%. The useful hearing preservation rate was 100% immediately after radiosurgery, 87% 6 months later and 78% 2 years later. The hearing preservation rate was high for small tumors. The facial and trigeminal neuropathies began to appear after 6 months. The incidence rates of facial neuropathy was 15.3%, 7.6%, and 3.8% 6 months, 1 year and 2 years after radiosurgery respectively. The incidence rates of trigeminal neuropathy was 11.4%, 3.8%, and 3.8% respectively 6 months, 1 year, and 2 years after radiosurgery. The incidence of neuropathy was 3.8% for tumors with a diameter < 30 mm for both facial and trigeminal nerves. The hearing in 2 out of 15 cases with dysaudia began to improve 6 months after radiosurgery. The incidence of neuropathy for tumors with the diameter > 30 mm was 3.8% for both nerves 2 years after raadiosurgery. The preservation rate of useful hearing for tumors with the diameter < 20 mm was 100% after radiosurgery. CONCLUSION: Stereotactic radiosurgery using gamma knife with a dose of 12 approximately 15 Gy to the tumor margin succeeds in controlling acoustic schwannoma and preserving useful hearing. The incidence of facial and trigeminal neuropathies are low. The neuropathy caused by gamma knife radiosurgery is sub-lethal and can be recovered gradually.

Adolescent↗
PubMed2002

[Stereotactic biopsy for intracranial deep lesions].

OBJECTIVE: To investigate the histological diagnostic efficacy and accuracy of stereotactic biopsy for intracranial deep lesions under computerized tomography (CT) and magnetic resonance imaging (MRI) guidance. METHODS: CT or MRI-guided stereotactic biopsy was performed in 605 cases with intracranial deep lesions. All the procedures were done under local anesthesia with Leksell stereotactic system. CT or MRI film was used to determine the coordinate in 450 cases and the computer-assisted planning for neurosurgery (CAPN) in 155 cases. RESULTS: Brain tumors, inflammatory lesions, and abnormal but nonspecific lesions were diagnosed pathologically in 537 cases (88.75%), 30 cases (4.96%), and 13 cases (2.15%) respectively. In 20 cases (3.31%) the biopsy procedure failed to provide useful pathological evidence. The total positive rate of biopsy was 96.69%. Complications associated with biopsy occurred in 18 patients (2.98%), and 2 patients (0.33%) died following the procedure. CONCLUSION: Stereotactic biopsy using MRI-guided stereotactic approach or CT-guided technique is a safe and reliable method for histological diagnosis of intracranial deep lesions.

Adolescent↗
PubMed2002

Heterogeneous expression and functions of androgen receptor co-factors in primary prostate cancer.

The androgen receptor (AR), a ligand-activated transcription factor of the steroid receptor superfamily, plays an important role in normal prostate growth and in prostate cancer. The recent identification of various AR co-factors prompted us to evaluate their possible roles in prostate tumorigenesis. To this end, we analyzed the expression of AR and eight of its co-factors by quantitative in situ RNA hybridization in 43 primary prostate cancers with different degrees of differentiation. Our results revealed nearly constant expression of AR and heterogeneous expression of AR co-factors, with increased expression of PIAS1 and Ran/ARA24, decreased expression of ELE1/ARA70, and no change in TMF1/ARA160, ARA54, SRC1, or TRAP220. Interestingly, whereas TMF1/ARA160, ELE1/ARA70, ARA54, RAN/ARA24, and PIAS1 were preferentially expressed in epithelial cells, another co-factor, ARA55, was preferentially expressed in stromal cells. Although the changes in levels of these co-activators did not correlate with Gleason score, their occurrence in high-grade prostatic intraepithelial neoplasia, suggests their involvement in initiation (or an early stage) of cancer. In addition, human prostate tumor cell proliferation and colony formation were markedly reduced by ELE1/ATRA70. Together, these findings indicate that changes in levels of expression of AR co-factors may play important, yet different, roles in prostate tumorigenesis.

Base Sequence↗
PubMed2002

Blimp-1 orchestrates plasma cell differentiation by extinguishing the mature B cell gene expression program.

Blimp-1, a transcriptional repressor, drives the terminal differentiation of B cells to plasma cells. Using DNA microarrays, we found that introduction of Blimp-1 into B cells blocked expression of a remarkably large set of genes, while a much smaller number was induced. Blimp-1 initiated this cascade of gene expression changes by directly repressing genes encoding several transcription factors, including Spi-B and Id3, that regulate signaling by the B cell receptor. Blimp-1 also inhibited immunoglobulin class switching by blocking expression of AID, Ku70, Ku86, DNA-PKcs, and STAT6. These findings suggest that Blimp-1 promotes plasmacytic differentiation by extinguishing gene expression important for B cell receptor signaling, germinal center B cell function, and proliferation while allowing expression of important plasma cell genes such as XBP-1.

Animals↗