Biomedical subjects

M Shen

Publications and source records attributed to M Shen.

At least 37 records · Page 2Linked to original sources

PubMed2001

Effect of ethanol and ether in the prevention of calcification of bioprostheses.

BACKGROUND: Lipids play a significant role in the process of calcification of bioprostheses. We assessed whether lipid extraction by ethanol, ether, or a surfactant could mitigate calcification of glutaraldehyde-treated bioprostheses. METHODS: On 200 bovine pericardium samples pretreated with 0.6% glutaraldehyde, lipid extraction was carried out by ethanol, ether, or the tween 80 surfactant, and combinations thereof. The treated tissues were implanted subcutaneously in 50 juvenile rats for 4 and 6 months. Lipids were analyzed by Fourier transform infrared spectrophotometer and chromatography before implantation. Calcium content of implanted tissues was assessed by atomic absorption spectrometer. RESULTS: Ethanol, ether, or surfactant did mitigate calcification. The most efficient pretreatments were the combination of ethanol and surfactant (calcium content: 15.5+/-6.8 microg/mg dry tissue after 6 months implantation) or the combination of ethanol, ether, and surfactant (13.1+/-6.2 microg/mg dry tissue) when compared with surfactant alone (42.9+/-12.7 microg/mg dry tissue). CONCLUSIONS: Ethanol or the combination of ethanol and ether added to the currently used glutaraldehyde-surfactant treatment further mitigates calcification.

Animals↗

PubMed2001

Effect of human immunoglobulins on the immunogenicity of porcine bioprostheses.

BACKGROUND: Glutaraldehyde fixation (GT) is known to reduce immunologic reactions and tissue degeneration after implantation in humans. Sterilization after glutaraldehyde fixation (G-ST) improves the safety and reduces the tendency of GT valves to calcify. Intravenous immunoglobulins (IVIg) have been shown to reduce xenogeneic response against porcine tissue. We have investigated the effect of these fixation procedures combined with and without IVIg on the antigenicity of bioprostheses. METHODS: Lewis adult rats were implanted subcutaneously with a fresh, GT, or G-ST porcine heart valve pre- or posttreated with different amounts of IVIg. We followed by enzyme-linked immunosorbent assay and IgM and IgG titers against protein extracts from the porcine heart valves after implantation. Cellular reactivity was assessed in xenogeneic lymphoendothelial coculture experiments. Calcification content was also examined. RESULTS: Glutaraldehyde fixation partially decreased the humoral response against proteins of the implant but elicited a cellular xenogeneic response. Sterilization reduced these reactivities, but retained antigenicity. Intravenous immunoglobulin postincubated with GT valves before implantation reduced the antigenicity of the tissue to the same extent as G-ST valves, but had no effect on valvular tissue calcification. CONCLUSIONS: Our studies demonstrate that IVIg or the sterilization procedure (ST) reduced the cellular response against glutaraldehyde-fixed valves (GT), whereas reduced calcification was observed only with ST.

Animals↗

PubMed2001

Detection and quantification of depurinated benzo[a]pyrene-adducted DNA bases in the urine of cigarette smokers and women exposed to household coal smoke.

Polycyclic aromatic hydrocarbons (PAH) are metabolized to electrophiles that can bind to DNA bases and destabilize the N-glycosyl bond, causing rapid depurination of the adducted bases. Recent studies support depurination of DNA as a mechanism central to the genesis of H-ras mutations in PAH-treated mouse skin. Depurinating adducts account for 71% of all DNA adducts formed in mouse skin treated with benzo[a]pyrene (BP). This study analyzed urine of cigarette smokers, coal smoke-exposed women, and nonexposed controls for the presence and quantities of the depurinated BP-adducted DNA bases, 7-(benzo[a]pyren-6-yl)guanine (BP-6-N7Gua) and 7-(benzo[a]pyren-6-yl)adenine (BP-6-N7Ade). Since these adducted bases originate from reaction of the BP radical cation with double-stranded DNA and not with RNA or denatured DNA, their presence in urine is indicative of DNA damage. Urine samples were fractionated by a combination of SepPak extraction and reverse-phase HPLC, and then analyzed by tandem mass spectrometry and capillary electrophoresis with laser-induced fluorescence. BP-adducted bases were detected in the urine from three of seven cigarette smokers and three of seven women exposed to coal smoke, but were not detected in urine from the 13 control subjects. Concentrations were estimated to be 60-340 and 0.1-0.6 fmol/mg of creatinine equivalent of urine for coal smoke-exposed women (maximum possible BP intake of ca. 23 000 ng/day) and cigarette smokers (BP intake of ca. 800 ng/day), respectively, exhibiting a sensitive response to BP exposures. BP-6-N7Gua was present at ca. 20-300 times the concentration of BP-6-N7Ade in the urine of coal smoke-exposed women, but was not detected in the urine of cigarette smokers. This difference may be due to the remarkably different BP exposures experienced by the two groups of PAH-exposed individuals. These results justify more extensive studies of depurinated BP-adducted DNA bases as potential biomarkers of PAH-associated cancer risk.

Adult↗

PubMed2001

Chondrocyte-derived ezrin-like domain containing protein (CDEP), a rho guanine nucleotide exchange factor, is inducible in chondrocytes by parathyroid hormone and cyclic AMP and has transforming activity in NIH3T3 cells.

OBJECTIVE: The purpose of this study is to investigate stage- and hormone-dependent expression of chondrocyte-derived ezrin-like domain containing protein (CDEP), a putative guanine nucleotide exchange factor (GEF) for Rho in chondrocytes, and demonstrate the guanine nucleotide exchange activity of this protein in vitro, as well as the transforming activity in NIH3T3 cells. METHODS: The expression of CDEP mRNA in growth plate chondrocytes in vivo and in vitro was examined by RT-PCR Southern analysis. The guanine nucleotide exchange activity was determined using a recombinant CDEP peptide containing the DH and PH domains in Sf9 cell lysates. The transforming activity was examined using NIH3T3 cells transiently transfected with a truncated CDEP cDNA. RESULTS: CDEP mRNA was expressed at the highest level in the hypertrophic (terminal) stage of chondrocytes in vivoand in vitro. Parathyroid hormone (PTH) elicited a biphasic increase of CDEP mRNA in chondrocytes. The CDEP mRNA level increased within 1 h, then decreased nearly to the control level at 3 h. Thereafter the mRNA level started to increase at 6 h, reaching a plateau at 24 h. Dibutyryl cyclic AMP had a similar effect on CDEP expression in chondrocytes. The dissociation of [3H]GDP from RhoA was stimulated dose-dependently by Sf9 cell lysates containing the CDEP peptide. Furthermore, transfection of a truncated CDEP cDNA induced focus formation in NIH3T3 cultures. CONCLUSIONS: CDEP is a novel GEF for Rho family GTPases with the transforming activity. CDEP may play a role in mediating or modulating the action of cAMP-elevating hormones on maturing chondrocytes.

Animals↗

PubMed2001

Induction of basic helix-loop-helix protein DEC1 (BHLHB2)/Stra13/Sharp2 in response to the cyclic adenosine monophosphate pathway.

DEC1 (BHLHB2)/Stra13/Sharp2, a basic helix-loop-helix (bHLH) transcription factor has been suggested to be involved in the control of proliferation and/or differentiation of several cells including nerve cells, fibroblasts and chondrocytes. In the present study, we examined the effect of parathyroid hormone (PTH), dibutyryl cAMP (Bt2cAMP) and forskolin on the expression of DEC1 in various cells. In rabbit chondrocyte cultures, PTH or Bt2cAMP increased the DEC1 mRNA level within 1 h. Thereafter, the DEC1 mRNA level rapidly decreased to the basal level at 3 h, and increased at 6-24 h. In cultures of a mouse embryo prechondrogenic cell line ATDC5, PTH or forskolin, an activator of adenylate cyclase, also increased the DEC1 mRNA level within 1 h. Furthermore, in all evaluated cell lines of human fibroblasts, canine epithelial cells, human carcinoma, human glioblastoma and human melanoma, Bt2cAMP increased the DEC1 mRNA level within 1-3 h. Studies with actinomycin D and cycloheximide indicated that the enhancement of DEC1 mRNA by cAMP was not due to mRNA stabilization and did not require new protein synthesis. These findings suggest that DEC1 is a novel direct target for cAMP in wide types of cells, and that the bHLH protein is involved in the control of gene expression in cAMP-activated cells.

Animals↗

PubMed2001

Classified fingerprinting: A method of comprehensive analysis for comparing megabase genomes.

The objective of the work we describe is to establish elementary methods for investigating the functions of genes; specifically, a fingerprinting method for analyzing entire DNA fragments in a mixture. Our goal is to develop a method for comparing genes with a size of several megabases. We improved a method of amplified fragment length polymorphism (AFLP) so that it could be used to analyze all the restriction fragments in a mixture. This method could be used to detect 90% of the DNA fragments produced from 100-kb model genomes by using a four-base cutter enzyme.

Base Sequence↗

PubMed2001

Gene structure and chromosomal location of a human bHLH transcriptional factor DEC1 x Stra13 x SHARP-2/BHLHB2.

DEC1/BHLHB2 is a novel cAMP-inducible basic helix-loop-helix (bHLH) transcriptional factor isolated from human chondrocyte cultures by the subtraction method [Shen et al. (1997) Biochem. Biophys. Res. Commun. 236, 294--298]. DEC1 seems to be involved in controlling the proliferation/differentiation of some cell lineages. We determined the structure of the human DEC1 gene and its chromosomal locus. Phylogenetic analysis and comparison of the gene structure showed that the DEC1 protein is a member of a new subgroup of the proline bHLH protein family that diverged earlier than other proline bHLH proteins including HES, hairy and E(spl). The human DEC1 gene spans approximately 5.7 kb and contains 5 exons. The putative promoter region contains multiple GC boxes but no TATA box. A primer extension study showed multiple transcriptional initiation sites. In the 5'-flanking region of the DEC1 gene, several transcriptional factor binding sites, including a cAMP-responsive element (CRE), were found using the transcription factor database. The DEC1 gene locates at Chromosome 3p25.3--26 by the FISH method. This is the first study to determine the genomic structure of the DEC1 gene subgroup.

Amino Acid Sequence↗

PubMed2001

Inhibition of monocyte adhesion and fibrinogen adsorption on glow discharge plasma deposited tetraethylene glycol dimethyl ether.

Monocytes and macrophages play important roles in host responses to implanted biomedical devices. Monocyte and macrophage interactions with biomaterial surfaces are thought to be mediated by adsorbed adhesive proteins such as fibrinogen and fibronectin. Non-fouling surfaces that minimize protein adsorption may therefore minimize monocyte adhesion, activation, and the foreign body response. Radio-frequency glow discharge plasma deposition (RF-GDPD) of tetraethylene glycol dimethyl ether (tetraglyme) was used to produce polyethylene oxide (PEO)-like coatings on a fluorinated ethylene-propylene (FEP) surface. Electron spectroscopy for chemical analysis (ESCA) and static time of flight secondary ion mass spectrometry (ToF-SIMS) were used to characterize the surface chemistry of tetraglyme coating. Fibrinogen adsorption to the tetraglyme surface was measured with 125I-labeled fibrinogen and ToF-SIMS. Adsorption of fibrinogen to plasma deposited tetraglyme was less than 10 ng cm(-2), a 20-fold decrease compared to untreated FEP or tissue culture polystyrene (TCPS). Monocyte adhesion to plasma deposited tetraglyme was significantly lower than adhesion to FEP or TCPS. In addition, when the surfaces were preadsorbed with fibrinogen, fibronectin, or blood plasma, monocyte adhesion to plasma deposited tetraglyme after 2 h or 1 day was much lower than adhesion to FEP. RF-GDPD tetraglyme coating provides a promising approach to make non-fouling biomaterials that can inhibit non-specific material-host interactions and reduce the foreign body response.

Blood↗

PubMed2001

Comparison of in vivo dopamine D2 receptor binding of [(123)I]AIBZM and [(123)I]IBZM in rat brain.

[(123)I]AIBZM, (S)-5-[(123)I]-Iodo-N-[(1-ethyl-2-pyrrolidinyl)]methyl-4-amine-2-methoxybenzamide is a derivative with high affinity for the D2 receptor. Labeling was achieved by the Iodogen method. The in vivo affinity for the D2 receptor and the biological characteristics were performed in rats. The brain uptake of [(123)I]AIBZM was significantly lower, however the striatum/cerebellum ratio (2h p.i.) was higher than that of [(123)I]IBZM. Because of the high affinity and its possibly lower unspecific binding compared to [(123)I]IBZM, [(123)I]AIBZM may be a potential imaging agent for the D2 dopamine receptor.

Animals↗

PubMed2001

Liposome-C-erbB2 antisense oligodoxynucleotides in human ovarian cancer cells.

OBJECTIVE: To explore the effects of liposome-C-erbB2 antisense phosphorothioate oligodeoxynucleotides (S-ODNs) on C-erbB2 proto-oncogene expression and cell proliferation in human ovarian cancer cells. METHODS: The effects of liposome-C-erbB2 S-ODNs on C-erbB2 protein expression, cell cycle and cell proliferation in human ovarian cancer cells were studied by means of flow cytometry and 3H-thymidine incorporation. RESULTS: Liposome-C-erbB2 S-ODNs can specifically reduce C-erbB2 protein expression in human ovarian cancer cells, accompanied by a 30% inhibition of cell proliferation. The effectiveness of liposome-C-erbB2 S-ODNs on the expression of C-erbB2 was about 40 times higher than that of C-erbB2 S-ODNs. CONCLUSIONS: The data suggest that antisense therapy might be a useful method of gene therapy in ovarian cancer. The effectiveness of C-erbB2 S-ODNs could be greatly increased by adsorption of S-ODNs by liposomes.

Cell Cycle↗

PubMed2001

[Characteristics of nitrogen and phosphorus pollution in the middle and small creeks, suburban Shanghai].

1. The middle and small creeks in suburban Shanghai were under heavy eutropic condition, with high loadings of nitrogen, phosphorus and organic pollutants. KN, TP and CODCr of the surface water of them were several times greater than the critical values of Types V, the worst level of water. 2. Spatial variations of N and P pollution were observed, as the creeks in different places accepted different types and amounts of pollutants. Affected by domestic sewage, the creeks nearby residential areas were often heavily polluted by NH4+ and P. The creeks in agricultural fields were more easily polluted by NO3- than by NH4+ and phosphorus. The creeks nearby livestock farms often witnessed sudden soaring of NH4+ and P. 3. N and P loadings of the creeks were also affected by the seasonal evolvement of ecological environment. With the increase of temperature and biomass, NH4+ and NO3- in the surface water were largely consumed and decreased as a result; while organic N and particle P increased as the enhancement of suspending biological particles. NO2- in the surface water increased with temperature as nitrifying bacteria became active. Total P and water soluble P also showed the trend of enhancement with the intensification of biological activities, however, they were also controlled by the condition of pH and DO in the water. 4. At the height of the summer, the surface and bottom water of the creeks differed in N and P loadings. NH4+, soluble P and total reactive P in the bottom water were higher than those in the surface; while NO3- and NO2- in the surface were higher than those in the bottom. Such water-quality stratification inevitably resulted from the enhancement of phytoplankton in the surface water and intensified release of NH4+ and P from the sediments. In the autumn, as-the temperature decrease, such phenomenon declined gradually.

China↗

PubMed2001

[Study of distribution and metabolism of methamphetamine in hair of guinea pig].

OBJECTIVE: To study the distribution and metabolism of methamphetamine in the hair of guinea pig. METHODS: Determination of methamphetamine and its metabolite amphetamine in hair was performed by GC/MS and GC/NPD. Concentration-time course of methamphetamine and amphetamine in hair of guinea were recorded. Relationship between hair color, administrated dose and drug concentration in hair were also discussed. RESULTS: The concentration of amphetamine is higher than the concentration of methamphetamine in the hair of guinea administrated a single dose or seven doses of methamphetamine. The concentration of methamphetamine and amphetamine were significantly related with administration dose and the incorporation rate into white and brown hair is much poorer than that of black hair. CONCLUSION: Administration methods, dose and the color of hair affect the concentration of methamphetamine and amphetamine.

Amphetamine↗

PubMed2001

[Spontaneous renal subcapsular or perinephric haematoma].

OBJECTIVE: To improve the diagnosis and treatment of spontaneous renal subcapsular and perinephric haematoma. METHODS: Seventeen cases of spontaneous renal subcapsular or perinephric haematoma were analyzed retrospectively. For imaging diagnosis, we used ultrasonography, computerized tomography (CT) and angiography. Thirteen cases were subjected to nephrectomy and one case was to renal biopsy, whereas the remaining 3 cases were treated conservatively. RESULTS: After follow up for 6-108 months, 3 patients died and 14 patients survived. CONCLUSIONS: For diagnosis, imaging examinations are very valuable. For treatment, most of patients with perinephric haematoma should be operated on.

Adult↗

PubMed2000

[Relationship between vascular endothelial growth factor expression and microvessel density in hepatocellular carcinomas and their surrounding liver tissue].

The relationship between vascular endothelial growth factor (VEGF) expression and microvessel density was studied with immunohistochemical method in hepatocellular carcinoma (HCC) and pericarcinomatous liver tissue. The positive rate of VEGF in HCCs was significantly lower than in surrounding liver tissues (66.7% vs. 85.4%, P < 0.05). There was no significant difference between HCC and pericarcinomatous liver tissue on expressive intensity of VEGF. The positive signal of VEGF was mainly localized in cytoplasma of cancer cells, pericarcinomatous hepatocytes, and vascular endothelial cells. The microvessel density in HCC was higher than in pericarcinomatous liver tissue and closely correlated to differentiated degree of cancer cells (rs = 0.5870; rs = 0.8235). The poorer cancer cell differentiation, the higher microvessel density. The results suggest that VEGF may not be the sole factor that stimulates angiogenesis in HCC genesis and development. To detect microvessel density in judging prognosis and biological behavior of HCC is more important than that of VEGF.

Adult↗

PubMed2000

Effect of spikelet position on rice anther culture efficiency.

The potential of anthers from different parts of the panicle to induce callus was investigated with the japonica rice variety Taipei 309. The results showed that the callusing abilities of anthers from different spikelet positions were significantly different. After plating 4483, 4496, 4348 anthers from the basal, middle and top parts, the percentage of anthers forming calli was 20% in the basal part, 12% in the middle part and 8% in the top part. The anthers of basal parts containing pollen at all uninucleate stages, including early, middle and late, showed higher callus induction frequency than those from middle and top parts. The green plantlet regeneration frequencies of top, middle and basal spikelets were around 18% in all three cases. From the results it would appear that anthers from the basal part of the panicle should be used in anther culture of rice in order to obtain higher efficiencies, and thereby optimise the usefulness of this technique in rice breeding programmes.

Journal Article↗

PubMed2000

Rab37 is a novel mast cell specific GTPase localized to secretory granules.

GTPases regulate a myriad of cellular functions including signal transduction, cytoskeletal organization and membrane trafficking. Rab GTPases act to coordinate the membrane dynamics of cells by organizing and regulating the activity of effector proteins important in vesicle trafficking. Rab37 is a novel Rab GTPase specifically expressed in the MC-9 mast cell line and bone marrow mast cells. Rab37 is 74% identical to Rab26 and 47% identical to Rab8, a GTPase important in Golgi to plasma membrane vesicle trafficking in mammalian cells. When green fluorescent protein tagged Rab37 is expressed in bone marrow mast cells, the secretory granules are labeled. These data suggest that Rab37 may play an important role in mast cell degranulation making this protein a potentially important target for therapeutic intervention in the treatment of allergy.

Amino Acid Sequence↗

PubMed2000

[An improved deresining method for semithin sections embedded-epoxy resin].

Deresining must be performed for HE, specific histochemical staining and immunohistochemical detection on semithin-sections embedded-epoxy resin. The deresining process in general methods had to take 24 hours, and the semithin-sections were easily separated from slides. An improved method was introduced in this paper, by which deresining time was only 5 minutes, and it could also avoid the separation of semithin-sections from the slides. The staining result was very good, and the resolving power of images was high.

Epoxy Resins↗

PubMed2000

Plasma-deposited membranes for controlled release of antibiotic to prevent bacterial adhesion and biofilm formation.

Bacterial infection on implanted medical devices is a significant clinical problem caused by the adhesion of bacteria to the biomaterial surface followed by biofilm formation and recruitment of other cells lines such as blood platelets, leading to potential thrombosis and thromboembolisms. To minimize biofilm formation and potential device-based infections, a polyurethane (Biospan) matrix was developed to release, in a controlled manner, an antibiotic (ciprofloxacin) locally at the implant interface. One material set consisted of the polyetherurethane (PEU) base matrix radiofrequency glow discharge plasma deposited with triethylene glycol dimethyl ether (triglyme); the other set had an additional coating of poly(butyl methyacrylate) (pBMA). Triglyme served as a nonfouling coating, whereas the pBMA served as a controlled porosity release membrane. The pBMA-coated PEU contained and released ciprofloxacin in a controlled manner. The efficacy of the modified PEU polymers against Pseudomonas aeruginosa suspensions was evaluated under flow conditions in a parallel plate flow cell. Bacterial adhesion and colonization, if any, to the test polymers were examined by direct microscopic image analysis and corroborated with destructive sampling, followed by direct cell counting. The rate of initial bacterial cell adhesion to triglyme-coated PEU was 0. 77%, and to the pBMA-coated PEU releasing ciprofloxacin was 6% of the observed adhesion rates for the control PEU. However, the rate of adherent cell accumulation due to cell growth and replication was approximately the same for the triglyme-coated PEU and the PEU controls, but was zero for the pBMA-coated PEU releasing ciprofloxacin.

Anti-Bacterial Agents↗