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Biomedical subjects

Ling Wang

Publications and source records attributed to Ling Wang.

At least 163 records · Page 9Linked to original sources
PubMed2002

Determination of betamethasone disodium phosphate in the in vitro media of PLGA microspheres by high-performance liquid chromatography.

Betamethasone disodium phosphate is a kind of corticosteroid, which is commonly used in the intralesional treatment of keloids. In this work, polymeric microspheres loaded with betamethasone disodium phosphate were fabricated to design a sustained-release system. A validated HPLC technique for determination of betamethasone disodium phosphate in in vitro media of the polymeric microspheres has been developed. The operation conditions were optimized. The analytical column was ZORBAX Bonus-RP column with 4.6 x 150 mm ID and a particle size of 5 microm. The mobile phase consisted of acetonitrile-0.01% phosphoric acid water solution (40:60, v/v). The flow rate was 1.0 ml/min and injection volume was 50 microl. The elutes were detected at 240 nm. Linearity, repeatability, inter- and intra-assay precision and accuracy of the method were evaluated. The liner range was obtained in a concentrated range of 20-1000 microg/ml, with a coefficient of correlation r=0.999978. The limit of detection for betamethasone disodium phosphate in the in vitro test samples was 0.25 microg. Recovery of betamethasone disodium phosphate from the in vitro test samples was 99.7+/-5.2% (mean+/-SD). Stability of betamethasone disodium phosphate at different pH values and temperatures were also investigated.

Anti-Inflammatory Agents↗
PubMed2002

Role of Ca(v) 2.3 (alpha1E ) Ca2+ channel in ischemic neuronal injury.

We investigated the role of the Ca(v)2.3 (alpha1E) channel in ischemic neuronal injury using Ca(v)2.3 mutant mice. In focal ischemia model with a complete occlusion of the middle cerebral artery in vivo, infarct at 24 h was significantly larger in Ca(v)2.3 mutant mice compared with that in wild-type controls. In vitro Ca2+ imaging studies using hippocampal slices revealed that oxygen-glucose deprivation induced a [Ca2+]i increase in the hippocampal CA1 region more vigorously in Ca(v)2.3 mutant mice than in wild-type controls, and that tetrodotoxin or bicuculline application abolished the difference between the genotypes. These results suggest that the Ca(v)2.3 channel plays a protective role in ischemic neuronal injury by a mechanism in which GABAergic neuronal actions are involved.

Animals↗
PubMed2002

Catalytic inhibitors of topoisomerase II are DNA-damaging agents: induction of chromosomal damage by merbarone and ICRF-187.

Merbarone is a catalytic inhibitor of topoisomerase II (topo II) that has been proposed to act primarily by blocking topo II-mediated DNA cleavage without stabilizing DNA-topo II-cleavable complexes. In this study merbarone was used as a model compound to investigate the genotoxic effects of catalytic inhibitors of topo II. The clastogenic properties of merbarone were evaluated using in vitro and in vivo micronucleus (MN) assays combined with CREST staining. For the in vitro MN assay, ICRF-187, a different type of catalytic inhibitor, and etoposide, a topo II poison, were used for comparison. Treatment of TK6 cells with all three of these drugs resulted in highly significant dose-related increases in kinetochore-lacking MN and, to a lesser extent, kinetochore-containing MN. In addition, a good correlation between p53 accumulation and MN formation was seen in the drug-treated cells. A mouse MN assay was performed to confirm that similar DNA-damaging effects would occur in vivo. Bone marrow smears from merbarone-treated B6C3F1 mice showed a dose-related increase in micronucleated polychromatic erythrocytes with a mean of 26 MN per 1000 cells being seen at the 60 mg/kg dose. Almost all MN lacked a kinetochore signal, indicating that merbarone was predominantly clastogenic under these conditions in vivo. The present study clearly shows that merbarone is genotoxic both in vitro and in vivo, and demonstrates the inaccuracy of earlier statements that merbarone and other catalytic inhibitors block the enzymatic activity of topo II without damaging DNA.

Animals↗
PubMed2002

Effect of soy protein on endogenous hormones in postmenopausal women.

BACKGROUND: The long-term clinical effects of soy protein containing various concentrations of isoflavones on endogenous hormones are unknown. OBJECTIVE: We examined the effects of ingestion of soy protein containing various concentrations of isoflavones on hormone values in postmenopausal women. DESIGN: Seventy-three hypercholesterolemic, free-living, postmenopausal women participated in a 6-mo double-blind trial in which 40 g protein as part of a National Cholesterol Education Program Step I diet was provided as casein from nonfat dry milk (control), isolated soy protein (ISP) containing 56 mg isoflavones (ISP56), or ISP containing 90 mg isoflavones (ISP90). Endogenous hormone concentrations were measured at baseline and at 3 and 6 mo. RESULTS: The concentration of thyroxine and the free thyroxine index were higher in the ISP56 group, and the concentration of thyroid-stimulating hormone was higher in the ISP90 group than in the control group at 3 and 6 mo (P < 0.05). Triiodothyronine was significantly higher in the ISP90 group only at 6 mo. Thyroxine, free thyroxine index, and thyroid-stimulating hormone at 6 mo were inversely associated with measures of baseline estrogenicity. No significant differences were found for endogenous estrogens, cortisol, dehydroepiandrosterone sulfate, insulin, glucagon, or follicle-stimulating hormone after baseline hormone values were controlled for. CONCLUSIONS: This study does not provide evidence that long-term ingestion of soy protein alters steroid hormone values, but it suggests that soy protein may have small effects on thyroid hormone values that are unlikely to be clinically important. The thyroid effects are, however, consistent with previous findings in animals and highlight the need for future research investigating possible mechanisms of action.

Bone Density↗
PubMed2002

Molecular cloning, gene organization, and expression of mouse Mpi encoding phosphomannose isomerase.

Phosphomannose isomerase (PMI) interconverts fructose-6-P (Fru-6-P) and mannose-6-P (Man-6-P), linking energy metabolism to protein glycosylation. We have cloned the mouse Mpi cDNA, analyzed its genomic organization, and studied the expression in different tissues. The Mpi gene has eight exons covering 7.2 kb. The structure and intron-exon boundaries are essentially the same as its human ortholog with 85% amino acid identity. Mpi is alternatively spliced at the 3' end, resulting in three messages with different 3'-untranslated regions. Mpi expression is regulated at both the transcription and translation levels, with the highest expression level in testis. Rabbit antibodies prepared against mouse PMI expressed in E. coli recognize a single 47-kDa band. Immunohistochemistry of mouse tissues shows general cytosolic staining in all cells. In testis, staining is intense in round spermatids and residual bodies, moderate in pachytene spermatocytes, and weak in spermatogonia and spermatozoa. In contrast, northern blot analysis shows comparable transcripts of 1.8 and 1.6 kb in pachytene spermatocytes and round spermatids, suggesting delayed translation of PMI. The stage-specific expression of PMI in testis may be important for KDN synthesis, which requires Man-6-P, or it may be needed to ensure sufficient glycosylation precursors in cells that do not utilize glucose and instead rely on lactate and pyruvate.

Amino Acid Sequence↗
PubMed2002

Identification of programmed cell death in situ in individual plant cells in vivo using a chromosome preparation technique.

A simple procedure, which combines a chromosome preparation technique with an in situ labelling technique modified from fluorescence in situ hybridization (FISH), has been developed for in situ detection of plant programmed cell death (PCD) at the single-cell level. After exposure of chromosomes and nuclei on slides by enzymolysis, Klenow or TdT was used to incorporate Bio-dUTP or fluorescein-dUTP at sites of DNA breaks. After Klenow-mediated labelling, the signals were amplified by a cascade of antigen-antibody reaction according to the detection system of FISH. This method enables in situ detection of plant PCD in vivo morphologically and biochemically at the chromosome, nuclear and DNA levels without cell culture and histological sectioning. This technique permits labelling of DNA breaks with high sensitivity due to increased chromosome and nucleus exposure to the labelling solutions, as well as due to the immunological amplification of the signals. Moreover, the changes in the cells were easier to be observed because the spatial obstacle of the cell wall and its autofluorescence were eliminated. It is potentially useful for in situ detection of PCD in plant root meristematic cells triggered by various environmental abiotic factors. It is proposed that the root tip is a versatile in vivo system for studying PCD induced by environmental abiotic factors.

Apoptosis↗
PubMed2002

Involvement of androgen receptor in 17beta-estradiol-induced cell proliferation in rat uterus.

Although it is known that, in the uterus, estrogen receptor alpha (ERalpha) is involved in proliferation and progesterone receptor in differentiation, the role of the two other gonadal-hormone receptors expressed in the uterus, androgen receptor (AR) and estrogen receptor beta (ERbeta), remains undefined. In this study, the involvement of AR in 17beta-estradiol (E(2))-induced cellular proliferation in the immature rat uterus was investigated. AR levels were low in the untreated immature uterus, but 24 h after treatment of rats with E(2), there was an increase in the levels of AR and of two androgen-regulated genes, IGF-I and Crisp (cysteine-rich secretory protein). As expected, E(2) induced proliferation of luminal epithelial cells. These actions of E(2) were all blocked by both the antiestrogen tamoxifen and the antiandrogen flutamide. The E(2)-induced AR was found by immunohistochemistry to be localized exclusively in the stroma, mainly in the myometrium, where it colocalized with ERalpha but not with ERbeta. ERbeta, detected with two different ERbeta-specific antibodies, was expressed in both stromal and epithelial cells either alone or together with ERalpha. Treatment with E(2) caused down-regulation of ERalpha and ERbeta in the epithelium. The data suggest that, in E(2)-induced epithelial cell proliferation, ERalpha induces stromal AR and AR amplifies the ERalpha signal by induction of IGF-I. Because AR is never expressed in cells with ERbeta, it is unlikely that ERbeta signaling is involved in this pathway. These results indicate an important role for AR in proliferation of the uterus, where estrogen and androgen do not represent separate pathways but are sequential steps in one pathway.

Androgen Antagonists↗
PubMed2002

BAC library of T. pallidum DNA in E. coli.

Treponema pallidum subspecies pallidum (Nichols) chromosomal DNA was used to construct a large insert bacterial artificial chromosome (BAC) library in Escherichia coli DH10B using the pBeloBAC11 cloning vector; 678 individual insert termini of 339 BAC clones (13.9 x coverage) were sequenced and the cloned chromosomal region in each clone was determined by comparison to the genomic sequence. A single 15.6-kb region of the T. pallidum chromosome was missing in the BAC library, between bp 248727 and 264323. In addition to the 12 open reading frames (ORFs) coded by this region, one additional ORF (TP0596) was not cloned as an intact gene. Altogether, 13 predicted T. pallidum ORFs (1.25% of the total) were incomplete or missing in the library. Three of 338 clones mapped by restriction enzyme digestion had detectable deletions and one clone had a detectable insertion within the insert. Of mapped clones, 19 were selected to represent the minimal set of E. coli BAC clones covering 1026 of the total 1040 (98.7%) predicted T. pallidum ORFs. Using this minimal set of clones, at least 12 T. pallidum proteins were shown to react with pooled sera from rabbits immunized with T. pallidum, indicating that at least some T. pallidum genes are transcribed and expressed in E. coli.

Animals↗
PubMed2002

Involvement of PhoP-PhoS homologs in Enterococcus faecalis virulence.

Eleven PhoP-PhoS homolog pairs were identified by searching the Enterococcus faecalis V583 genome sequence database at The Institute for Genomic Research with the Bacillus subtilis PhoP-PhoS sequences. Each pair appears to be a potential two-component system composed of a response regulator and a sensor kinase. Seven of the homologs were disrupted in E. faecalis strain OG1RF. TX10293, a mutant disrupted in one of these genes (etaR, the first gene of the gene pair designated etaRS), showed delayed killing and a higher 50% lethal dose in a mouse peritonitis model. The predicted EtaR protein sequence showed greatest similarity to LisR of Listeria monocytogenes (77%) and CsrR of Streptococcus pyogenes (70%); EtaS is 53% similar to LisK and 54% similar to CsrS. When grown in vitro, the TX10293 mutant was more sensitive to low pH (pH 3.4) and more resistant to high temperature (55 degrees C) than wild-type OG1RF. In conclusion, many potential two-component systems are identified for E. faecalis, one of which, EtaRS, was shown to be involved in stress response and virulence.

Amino Acid Sequence↗
PubMed2002

Deletion of the laminin alpha4 chain leads to impaired microvessel maturation.

The laminin alpha4 chain, a component of laminin-8 and -9, is expressed in basement membranes, such as those beneath endothelia, the perineurium of peripheral nerves, and around developing muscle fibers. Laminin alpha4-null mice presented with hemorrhages during the embryonic and neonatal period and had extensive bleeding and deterioration of microvessel growth in experimental angiogenesis, as well as mild locomotion defects. Histological examination of newborn mice revealed delayed deposition of type IV collagen and nidogen into capillary basement membranes, and electron microscopy showed discontinuities in the lamina densa. The results demonstrate a central role for the laminin alpha4 chain in microvessel growth and, in the absence of other laminin alpha chains, in the composition of endothelial basement membranes.

Anemia↗
PubMed2002

Control of temperature-responsive synthesis of the phytotoxin coronatine in Pseudomonas syringae by the unconventional two-component system CorRPS.

The phytopathogen Pseudomonas syringae produces the phytotoxin coronatine (COR) as a major virulence factor. COR and its precursor, coronafacic acid, function as molecular mimics of the plant signaling molecule jasmonate. A 32.8-kb plasmid-borne gene cluster mediates COR biosynthesis, which is optimal at 18 degrees C and non-detectable at 28 degrees C, the optimal growth temperature for P. syringae. The thermoregulation is mediated at the transcriptional level by an unconventional two-component regulatory system consisting of a histidine protein kinase, CorS, and two transcriptional activators, CorR and CorP. Dissection of this regulatory triad revealed that CorR binds to its target sequences in a thermoresponsive manner and that its DNA-binding activity is controlled by CorS. A Preliminary model for thermo-sensing by CorS is proposed based on its membrane topology and the analysis of translational fusions of CorS to reporter enzymes at different temperatures. CorP lacks a typical helix-turn-helix motif but possibly functions as a modulator of CorR or CorS activity. The thermoregulation of COR biosynthetic genes is widespread among various COR-producing P. syringae strains. Post-translational processes also contribute to the thermo-responsiveness of COR production. Additionally, COR synthesis in P. syringae is influenced by nutrient availability, rpoN encoding the alternative sigma factor sigma54, and HrpV, a negative regulator of hrp gene expression, suggesting a complex regulatory network governing phytotoxin synthesis.

Amino Acids↗
PubMed2002

[Assessment of autonomic nervous function during orthostatic stress in pilots with history of syncope].

OBJECTIVE: To assess the role of autonomic nervous function during orthostatic tolerance tests (OTT) in pilots with history of G-induced loss of consciousness (G-LOC) or vasovagal syncope (VVS). METHOD: The relation between heart rate variability (HRV) and outcome of OTT result were compared among 3 groups of cases: 1) 30 patients with history of syncope and positive OTT as patient group (PG); 2) 20 cases with history of syncope but negative OTT result as negative group (NG); 3) 15 age-, sex-, flight plane model-, flight time-matched healthy pilots as healthy control (HC). OTT results and HRV, heart rate (HR), systolic blood pressure (SBP) and diastolic blood pressure (DBP) before and after OTT and their time and frequency domain were compared and analyzed among the three groups. RESULT: HR, SBP, and DBP were not significantly different (P>0.05) among the three groups before OTT. But during OTT, HR in PG was higher than those in NG and HC (P<0.01), SBP and DBP in PG were lower than those in NG and HC (P<0.01). 24 h continuous RR interval standard difference (SDNN), HRV triangle index (HRVI), and interval average value in PG were significantly lower than those in NG and HC; Power spectrum analysis of mean 1 h value for low frequency part (LF) and high frequency part (HF) were not significantly different among three groups, but LF/HF ratio in PG was higher than that in NG or HC (P<0.05). CONCLUSION: It is suggested that G-LOC and VVS may be due to increase in sympathetic tone and decrease in parasympathetic tone during orthostatic stimulation, as resulted from autonomic nervous dysfunction.

Adult↗
PubMed2002

Multiplexed, targeted gene expression profiling and genetic analysis on electronic microarrays.

BACKGROUND: Electronic microarrays comprise independent microelectrode test sites that can be electronically biased positive or negative, or left neutral, to move and concentrate charged molecules such as DNA and RNA to one or more test sites. We developed a protocol for multiplexed gene expression profiling of mRNA targets that uses electronic field-facilitated hybridization on electronic microarrays. METHODS: A multiplexed, T7 RNA polymerase-mediated amplification method was used for expression profiling of target mRNAs from total cellular RNA; targets were detected by hybridization to sequence-specific capture oligonucleotides on electronic microarrays. Activation of individual test sites on the electronic microarray was used to target hybridization to designated subsets of sites and allow comparisons of target concentrations in different samples. We used multiplexed amplification and electronic field-facilitated hybridization to analyze expression of a model set of 10 target genes in the U937 cell line during lipopolysaccharide-mediated differentiation. Performance of multiple genetic analyses (single-nucleotide polymorphism detection, gene expression profiling, and splicing isoform detection) on a single electronic microarray was demonstrated using the ApoE and ApoER2 genes as a model system. RESULTS: Targets were detected after a 2-min hybridization reaction. With noncomplementary capture probes, no signal was detectable. Twofold changes in target concentration were detectable throughout the ( approximately 64-fold) range of concentrations tested. Levels of 10 targets were analyzed side by side across seven time points. By confining electronic activation to subsets of test sites, polymorphism detection, expression profiling, and splicing isoform analysis were performed on a single electronic microarray. CONCLUSIONS: Microelectronic array technology provides specific target detection and quantification with advantages over currently available methodologies for targeted gene expression profiling and combinatorial genomics testing.

Alternative Splicing↗
PubMed2002

[Changes in heart rate and blood pressure under push pull maneuver simulated on a tilt table].

Objective. Push-pull maneuver (PPM) was simulated using a tilt table to assess detailed cardiovascular responses and the simulation model. Method. Ten healthy fighter pilots were exposed to 3 times transition of body position of head-up tilt (HUT) for 1 min-->head-down tilt (HDT) for 10 s, 15 s and 20 s respectively-->HUT for 1 min in randomized sequences. The rate of tilt table rotation was 45 degrees /s. Heart-level arterial blood pressure was monitored with 4 s intervals, and HR was continuously monitored by ECG. Result. HR and BP fell significantly during HDT compared with those during HUT; upon subsequent HUT, HR and BP were significantly less than those during previous HUT, except BP at 11-15 s. Conclusion. Cardiovascular responses to PPM can be simulated with a tilt table. It is suggested that the tilt table model is valid in simulating the PPM.

Adaptation, Physiological↗
PubMed2002

[Coexpression of vascular endothelial growth factor and its receptors in human tumor cell lines].

BACKGROUND & OBJECTIVE: Vascular endothelial growth factor (VEGF) play an important role in tumor angiogenesis through a paracrine mechanism, but the importance of its autocrine has not been fully elucidated. This study was designed to explore the gene coexpression pattern of VEGF and its receptors (Flt-1 and KDR) in variety of human malignant cell lines. METHODS: After isolation of RNA from thirty tumor cell lines and four endothelial cells, gene expressions of VEGF and its receptors were measured by semi-quantitative reverse transcriptase polymerase chain reaction using the transcriptional level of the house-keeping gene for internal calibration. RESULTS: VEGF transcript was detected in the majority of tumor cell lines (29/30) and in all endothelial cell lines at moderate or high level, while the expression of VEGF was low in human umbilical vein endothelial cell (HUVEC). Moreover, Flt-1 gene expression was found in 50% of hematopoietic malignancies (6/12), 28% of solid tumors (5/18), and endothelial cells (EA. hy926 and HUVEC). In contrast, the expression of KDR gene was found in 2 (16.7%) hematopoietic cell lines and 6 (33.3%) solid tumor lines. In endothelial cells, KDR gene expression was detectable in HMEC-1 and HUVEC only. However, ECV304 cells express neither Flt-1 nor KDR gene. CONCLUSION: Overexpression of VEGF gene in all tumor cell lines provides a potential biological marker for malignancies and the coexpression of VEGF with its receptors suggesting an autocrine pathway exists in tumor cells.

Cell Line, Tumor↗
PubMed2002

[Effect of folium ginkgo extract on the erythrocyte immunity function and serum lipid peroxide in asphyxia neonate].

OBJECTIVE: To observe the changes of erythrocyte immunity and serum lipid peroxide in asphyxia neonate, and to study the effect of Folium Ginkgo extract (FGE) on them. METHODS: Thirty asphyxia neonates were randomly divided into 2 groups, the treated group and the control group, 15 in each group. Erythrocyte C3b receptor rosette rate (E-C3bRR), erythrocyte immune complex rosette rate (E-ICR), blood superoxide dismutase (SOD) activity and serum lipid peroxide (LPO) level were determined at 24 hrs after birth. Conventional treatment was given to both groups and FGE (15 mg/kg.d) was given to the treated group additionally for 7-8 days, then the above-mentioned parameters were re-examined and neonatal behavioral neurological assessment (NBNA) was measured as well. RESULTS: E-C3bRR and SOD lowered, E-ICR and serum LPO increased in the asphyxia neonate significantly (P < 0.05). After treatment, comparison between the two groups showed that E-C3bRR and SOD were higher, E-ICR and serum LPO were lower in the treated group than those in the control group, and NBNA scoring was obviously higher in the former than that in the latter (all P < 0.05). CONCLUSION: Decrease of erythrocyte immunity in asphyxia neonate is related to the declined anti-oxidation ability and lipid peroxidase injury. FGE could suppress the free radical production, scavenge free radicals, antagonize the lipid peroxidation injury of cell membrane and up-regulate erythrocyte immunity. It displays the effects of nerve tissue protection and hypoxia-ischemic brain injury alleviation.

Asphyxia Neonatorum↗
PubMed2002

[A new model of choroidal neovascularization in mice].

OBJECTIVE: To investigate the feasibility of inducing choroidal neovascularization (CNV) in mice by diode laser. METHODS: Two hours, 3 days, 1 week, 2 weeks and 4 weeks after photocoagulation, the effect of diode laser for inducing CNV by fundus fluorescein angiography (FFA), light microscopy and transmission electron microscopy. RESULTS: Two hours and 3 days after laser treatment, there were no CNV and fluorescent leakage observed in mice. The first signs of leakage in FFA associated with CNV appeared 1 week after the postphotocoagulation, (48/90 lesions, or 53.3%). Four weeks after laser treatment, there were still 33 lesions appearing leakage (36.67%). Histological sections proved the existence of CNV, but the rate of CNV was not in accord with that of fluorescence leakage. CONCLUSIONS: This animal model is very useful for in vivo studies of angiogenesis and its modulation via various therapy.

Animals↗