Biomedical subjects

W Yan

Publications and source records attributed to W Yan.

At least 127 records · Page 7Linked to original sources

PubMed1997

5-HT1a receptors mediate the neurotrophic effect of serotonin on developing dentate granule cells.

We have previously reported that neonatal (P3) serotonin (5-HT) depletion results in a significant decrease in the number of dendritic spines per 50 microns of dendritic length on dentate granule cells. This effect is specific and permanent. Neither total dendritic length nor the number of dendritic segments is affected by 5-HT depletion. The area dentata contains a dense 5-HT1a receptor population that is present in the at birth. Therefore, 5-HT1a receptors represented a likely candidate for the mediation of the effects of 5-HT on developing granule cells. The present study used the drugs buspirone and NAN-190, which have been shown to be an agonist and antagonist respectively at postsynaptic 5-HT1a receptors in vivo, to test the idea that neurotrophic actions of 5-HT result from 5-HT1a receptor stimulation. Following 5-HT depletion with PCA, pups received daily injections of buspirone (1.0 mg/kg) from P5 to P14. Granule cell morphology was then studied using intracellular filling with Neurobiotin on P14, P21 and P60. Buspirone treatment prevented the loss of dendritic spines previously shown to follow 5-HT depletion with PCA. No other morphological parameters were significantly changed by buspirone treatment. Naive pups received daily injections of NAN-190 from P3 to P14. One group received 1.0 mg/kg while a second group received 3.5 mg/kg. Both doses of NAN-190 resulted in dendritic spine loss comparable to that obtained with neonatal PCA treatment. This loss was permanent suggesting that the first two postnatal weeks may represent a critical period for the action of 5-HT on developing granule cells. Significant, dose-dependent changes in total dendritic length and number of dendritic segments reminiscent of the effects of norepinephrine depletion were also observed in NAN-190-treated rats. We suspect that this change is the result of the action NAN-190 at alpha receptors and is therefore distinct from the specific effect of 5-HT on the number of dendritic spines. The NAN-190 experiment also shows that the loss of dendritic spines is a function of decreased stimulation of 5-HT1a receptors and not the loss of 5-HT terminal membrane.

Animals↗

PubMed1997

Effects of neonatal serotonin depletion on the development of rat dentate granule cells.

The appearance of serotonergic (5-HT) neurons and projections early in central nervous system (CNS) development has resulted in the hypothesis that 5-HT is an important factor in neuronal differentiation and synaptogenesis. Studies of the effects of 5-HT on the development of molluscan and mammalian neurons in vitro support this hypothesis, but mammalian in vivo studies have produced equivocal results. The present study reinvestigated the role of 5-HT in CNS development using the dentate granule cell as a model. Dentate granule cells were chosen for this study of the effects of 5-HT depletion on neuronal development because they are generated in the early postnatal period. Thus, 5-HT depletion could be effected by the treatment of rat pups with either parachloroamphetamine (PCA) or 5,7-dihydroxytryptamine (5,7-DHT) thereby avoiding problems inherent in maternal treatment paradigms. The morphology of Neurobiotin-filled granule cells was studied on P14, P21, P60 and P120 (P0 = day of birth). The parameters measured were total dendritic length, number of dendritic segments and dendritic spine density (number of spines/50 microns dendritic length). Granule cells from vehicle-treated controls were similar to those previously reported in studies of normal granule cell development in all respects. In particular, the decrease in dendritic spine density from P14 to P120 observed in Golgi preparations was verified in our population of intracellularly filled granule cells. Transient depletion of 5-HT by neonatal PCA treatment resulted in a decrease dendritic length that was not statistically different from control values. However, dendritic spine density was reduced by about 27% at all ages studied. 5,7-DHT treatment produces a permanent, severe depletion of 5-HT. Spine densities in granule cells from 5,7-DHT-treated pups were also about 38% lower than controls. Total dendritic length in cells from 5,7-DHT-treated rats was reduced to a degree comparable to that observed in PCA-treated pups. The number of granule cell dendritic segments was also less than that observed in control and PCA-treated rats but this difference was not statistically significant. These observations suggest that reduction of 5-HT in the early postnatal period can result in changes in the morphology of dentate granule cells, particularly at the level of the synapse as reflected by the permanent reduction in synaptic spine density. The comparison of results from cases with permanent and transient reduction of 5-HT indicates that the developmental influence of 5-HT is most important during the first three postnatal weeks.

5,7-Dihydroxytryptamine↗

PubMed1997

Enhancement of cartilage matrix protein synthesis in arthritic cartilage.

OBJECTIVE: To investigate whether the synthesis of cartilage matrix protein (CMP) is enhanced in arthritic cartilage. METHODS: The content of CMP in human and pig cartilage was determined by immunoblotting, and CMP-producing chondrocytes in osteoarthritic (OA) and rheumatoid arthritic (RA) joints were immunostained. RESULTS: CMP was undetectable in the condylar cartilage and disc of pigs, whereas it was abundant in the rib and tracheal cartilage of the same animals. By immunohistochemical analysis, CMP was localized in only a few chondrocytes (5%) in normal human joints, whereas numerous chondrocytes (>60%) were immunostained in RA joints. The number of CMP-producing cells was also increased in OA cartilage (>40%). Immunoblotting analyses confirmed that the CMP content in the cartilage from OA and RA patients was much higher than that in normal cartilage. CONCLUSION: These findings demonstrate that articular chondrocytes can synthesize CMP, although it is suppressed under physiologic conditions. The results also suggest that articular chondrocytes express CMP in response to arthritic stimuli.

Adult↗

PubMed1997

Up-regulation of urokinase plasminogen activator messenger ribonucleic acid and protein in hen granulosa cells by transforming growth factor alpha in vitro during follicular development.

The aim of the present study was to examine the regulatory role of transforming growth factor alpha (TGF alpha) on urokinase plasminogen activator (uPA) gene expression and protein levels in hen granulosa cells from different stages of ovarian follicular development in vitro. Granulosa cells from the first (F1), the second and third (F2-3), and the fourth, fifth, and sixth (F4-6) largest preovulatory follicles were cultured for 21 h in the absence and presence of TGF alpha (10 ng/ml). The uPA mRNA abundance and protein content were determined by Northern and Western blot analysis, respectively. Cell-associated and secreted PA activity was measured by a fibrinolysis assay and characterized by zymography. Hen granulosa cells produce a uPA with a molecular mass of about 35 kDa and a transcript size of approximately 2.5 kb. Basal uPA mRNA abundance, protein content, and activity were highest in granulosa cells from F4-6 follicles and decreased with follicular maturation. Granulosa cell uPA mRNA levels, protein content, and activity were increased in the presence of TGF alpha, reaching maximal levels in granulosa cells from less mature follicles, although the percentage of stimulation was higher in cells from late stages of follicular development. These findings clearly demonstrate specific expression of uPA in proliferatively active granulosa cells and responsiveness of uPA to TGF alpha at both transcriptional and translational levels. They support the concept that PA of the urokinase type plays an important role in extracellular matrix remodeling during TGF alpha-induced granulosa cell proliferation and ovarian follicular growth.

Animals↗

PubMed1997

The importance of delta and kappa opioid receptors in the property of thyrotropin-releasing hormone against hemorrhagic shock.

Many studies have demonstrated that thyrotropin-releasing hormone (TRH) produces various beneficial effects in the treatment of shock. TRH has been proposed to reverse the cardiovascular depression of endogenous opioid peptides. Nevertheless, it remains unknown whether opioid receptors are truly involved in this process. We designed experiments to study the importance of delta and kappa opioid receptors in the beneficial effects of TRH in hemorrhagic shock in rabbits and on opiate receptors following hemorrhagic shock in rats. The results indicated that TRH (50 micrograms, i.c.v.) significantly improved the mean arterial pressure (MAP), left ventricular systolic pressure (LVSP), and the maximal rate of ventricular systolic pressure changes (+/- dp/dtmax) during hemorrhagic shock in rabbits. This TRH effect was abolished by pretreatment with ICI174,864 (50 micrograms, i.c.v.), a highly selective delta opioid receptor antagonist, but not by pretreatment with nor-binaltorphimine (Nor-BNI, 50 micrograms, i.c.v.), a highly selective kappa opioid receptor antagonist. The maximal binding capacity (Bmax) of brain delta and kappa opioid receptors significantly increased following hemorrhagic shock, but the receptor affinity (Kd) did not change. TRH (5 mg/kg, i.v.) decreased the number (Bmax) of brain delta opioid receptors significantly, but it did not influence the receptor affinity. TRH did not influence the Bmax or affinity of brain kappa opioid receptors. These findings suggest that opioid receptors play an important role in mediating the antishock property of TRH. TRH-induced down-regulation of the number of brain opioid receptors may be one of the important mechanisms by which TRH exercises its protective effects in the treatment of shock.

Animals↗

PubMed1997

Specific detection and confirmation of Campylobacter jejuni by DNA hybridization and PCR.

Conventional detection and confirmation methods for Campylobacter jejuni are lengthy and tedious. A rapid hybridization protocol in which a 1,475-bp chromogen-labelled DNA probe (pDT1720) and Campylobacter strains filtered and grown on 0.22-micron-pore-size hydrophobic grid membrane filters (HGMFs) are used was developed. Among the environmental and clinical isolates of C. jejuni, Campylobacter coli, Campylobacter jejuni subsp. doylei, Campylobacter lari, and Arcobacter nitrofigilis and a panel of 310 unrelated bacterial strains tested, only C. jejuni and C. jejuni subsp. doylei isolates hybridized with the probe under stringent conditions. The specificity of the probe was confirmed when the protocol was applied to spiked skim milk and chicken rinse samples. Based on the nucleotide sequence of pDT1720, a pair of oligonucleotide primers was designed for PCR amplification of DNA from Campylobacter spp. and other food pathogens grown overnight in selective Mueller-Hinton broth with cefoperazone and growth supplements. All C. jejuni strains tested, including DNase-producing strains and C. jejuni subsp. doylei, produced a specific 402-bp amplicon, as confirmed by restriction and Southern blot analysis. The detection range of the assay was as low as 3 CFU per PCR to as high as 10(5) CFU per PCR for pure cultures. Overnight enrichment of chicken rinse samples spiked initially with as little as approximately 10 CFU/ml produced amplicons after the PCR. No amplicon was detected with any of the other bacterial strains tested or from the chicken background microflora. Since C. jejuni is responsible for 99% of Campylobacter contamination in poultry, PCR and HGMF hybridization were performed on naturally contaminated chicken rinse samples, and the results were compared with the results of conventional cultural isolation on Preston agar. All samples confirmed to be culture positive for C. jejuni were also identified by DNA hybridization and PCR amplification, thus confirming that these DNA-based technologies are suitable alternatives to time-consuming conventional detection methods. DNA hybridization, besides being sensitive, also has the potential to be used in direct enumeration of C. jejuni organisms in chicken samples.

Animals↗

PubMed1997

High incidence of T-cell tumors in E2A-null mice and E2A/Id1 double-knockout mice.

The basic-helix-loop-helix (bHLH) proteins encoded by the E2A gene are broadly expressed transcription regulators which function through binding to the E-box enhancer sequences. The DNA binding activities of E2A proteins are directly inhibited upon dimerization with the Id1 gene product. It has been shown that disruption of the E2A gene leads to a complete block in B-lymphocyte development and a high frequency of neonatal death. We report here that nearly half of the surviving E2A-null mice develop acute T-cell lymphoma between 3 to 10 months of age. We further show that disruption of the Id1 gene improves the chance of postnatal survival of E2A-null mice, indicating that Id1 is a canonical negative regulator of E2A and that the unbalanced ratio of E2A to Id1 may contribute to the postnatal death of the E2A-null mice. However, the E2A/Id1 double-knockout mice still develop T-cell tumors once they reach the age of 3 months. This result suggests that E2A may be essential for maintaining the homeostasis of T lymphocytes during their constant renewal in adult life.

Animals↗

PubMed1997

Polymorphism of short tandem repeat (STR) loci PLA2, D3S2459, D8S315 (kw38), CYP19, D3S1359, FGA, and D8S1132 in the Japanese and Chinese populations.

We report a study of polymorphism for seven short tandem repeat (STR) loci in Japanese and Chinese populations. Among 104 to 134 individuals in the both population samples, eight alleles were revealed for locus PLA2, thirteen for D3S1359, eleven for FGA, eight for D8S315 (kw38), ten for D8S1132, five for CYP19, and seven for D3S2459. They correspondingly constituted 10 to 39 genotypes therein. For most of the STRs, there was only a single allele active as the most frequent one among the others, except locus D3S1359 in Chinese samples (two alleles, 206 bp and 210 bp, frequency = 0.273 each). Also, the population genotype configurations were locus specific, varying in the patterns of commonest genotypes on each locus, e.g., one pattern for loci CYP19, D3S1359, and D8S315, one and two for loci PLA2 and D3S2459, two for locus D8S1132, and one and four for locus FGA. The distributions of observed genotypes were in Hardy-Weinberg Equilibrium. Furthermore, the seven STRs were exhibited highly polymorphic and informative for the both populations, and the alleles could be easily separated in electrophoresis and correctly interpreted with side-to-side allelic ladders. Together, the results suggest that the tri- and tetra-meric STRs are useful genetic markers for forensic practice.

Alleles↗

PubMed1997

[A three-year clinical evaluation of five light-cured composite resins in fillings of posterior teeth].

In order to study the clinical performance and the evaluation method of light-cured composite resin in filling for posterior teeth, two evaluation methods were used to evaluate 5 light-cured posterior composite resin fillings in 169 adult posterior class I cavity. Results showed that each evaluation method has its own advantages. The curative effect was declined with time in this study. Failures and defects were mainly occurred after 3 years. Secondary caries, loss of fillings and marginal stainings were the main reasons of failures. Compared with the effect of 1 year, the success rate after 3 years declined significantly, and further long-term clinical observation is needed.

Adolescent↗

PubMed1997

[Effects of IFN-alpha on the expressions of perforin and granzymes in IL-2 activated lymphocytes].

OBJECTIVE: To study the effect of IFN-alpha on the expressions of perforin and granzymes in IL-2-activated-lymphocytes. METHODS: NK and LAK activities were assayed by 4 hour standard 51Cr release test, the activity of perforin was detected by hemolysis method, expression of granzyme B was measured by ABC immunohistological method, expression of granzyme A was measured by BLT method. RESULTS: IFN-alpha significantly augmented the activities of NK and LAK in IL-2 activated peripheral blood lymphocytes (PBL) after 1 day culture. Perforin activity in lymphocytes was increased after 1 day exposure to IL-2 or IFN-alpha, and was enhanced when exposed to the combination of IL-2 and IFN-alpha. After 3 day culture, the perforin activity remained high in lymphocytes activated by IL-2 alone or in combination with IFN-alpha, while declined to control level in IFN-alpha exposed group. IL-2 and IFN-alpha alone or in combination had no effect on expression of granzyme A and B. CONCLUSION: IFN-alpha enhances the cytotoxicity of lymphocytes activated by IL-2. The mechanism might be that IFN-alpha upregulates the perforin expression.

Gene Expression Regulation↗

PubMed1997

[In vitro reversal of homoharringtonine resistance by the combination of tamoxifen and verapamil].

OBJECTIVE: To investigate the reversal of homoharringtonine (HHT)-resistance by tamoxifen (TAM) or verapamil (VER) alone or in combination. METHODS: The drug-sensitivity test was performed with semisolid agar culture. RESULTS: The cytotoxicity of HHT to K562/S cells was not enhanced by TAM or VER alone or in combination,but HHT resistance in HHT resistant cells (K562/H20) was reversed by VER and TAM at nontoxic doses (4micromol/L or 8micromol/L). The IC50 of K562/H20 for HHT decreased from 446.8 +/- 0.08microg/L to 45.1 +/- 0.02microg/L in the presence of 4micromol/L of VER, to 22.4 +/- 0.03microg/L in 8micromol/L of VER, to 85.1 +/- 0.03microg/L in 4micromol/L of TAM and to 26.4 +/- 0.02microg/L in 8micromol/L of TAM. In the presence of combinations of 2micromol/L VER and 4micromol/L TAM and of 2micromol/L VER and 8micromol/L TAM, IC50 of K562/H20 decreased to 30.4 +/- 0.02microg/L and 4.3 +/- 0.04microg/L, respectively. CONCLUSION: HHT-resistance could be reversed by VER or TAM alone, and the combination of the two drugs showed a synergistic effect.

Animals↗

PubMed1997

[Effect of bone marrow transplantation conditioning regimen on thyroid and adrenocortical functions in patients with blood diseases].

OBJECTIVE: In order to investigate the life quality of patients with hematological diseases after bone marrow transplantation (BMT). METHODS: Pituitary-thyroid and adrenocortical function were de tected in 29 patients with hematological diseases before and after BMT. RESULTS: All patients had normal thyroid and adrenocortical functions before BMT. As compared with pre-BMT,the median serum TSH levels were significantly increased at 3, 6, 12 (P<0.01), 24-60 (P<0.05) months post-BMT. The adrenocortical function had no change in all patients, and thyroid dysfunction were found in 6 of 24 patients detected at a median time of 6 month post-BMT. Five of the 6 thyroid dysfuntion patients developed hypothyroidism, and one hyperthyroidism. CONCLUSION: There was little effect of conditioning regimen on adrenocortical function, while thyroid dysfunction was common after BMT. Long term follow up on thyroid function in patients after BMT is necessary.

Adolescent↗

PubMed1997

[The killing effect of IL-2 and IFN-alpha activated bone marrow on K562 leukemic cell].

OBJECTIVE: To evaluate the killing effect of IL-2 and IFN-alpha activated bone marrow cells on K562 cells. METHODS: Semi-solid colony assay was used. RESULTS: Bone marrow from leukemia patients in remission was activated in vitro with IL-2 for 3 days. The activated bone marrow (ABM) displayed killing effects of 0.31 approximately 2.30 logs on K562 cells, this killing effects was further increased to 0. 30 approximately > 3.15 logs when IFN-alpha added with IL-2 to the marrow for activation. IL-2 alone or in combination with IFN-alpha showed no inhibition of CFU-GM and K562 cells. Compared with IL-2 or IFN-alpha alone, the combination of the two cytokines could more effectively maintain the killing effect of ABM on leukemic cells. CONCLUSION: IFN-alpha can augment the purging effect of IL-2 ABM and combination of the two cytokines can effectively maintain the cytotoxicity of ABM.

Bone Marrow Cells↗

PubMed1997

[Studies on expansion ex vivo of murine bone marrow cells and its hematopoietic reconstitution capacity].

OBJECTIVE: To investigate the effects of stem cell factor (SCF) in combination with interleukin-1 (IL-1) or/and interleukin-3 (IL-3) on ex vivo expansion of 5FU treated bone marrow cells and hematopoietic recovery in lethally irradiated mice transplanted with the expanded cells. METHODS: 5FU treated bone marrow cells (d3-5FU-BMC) were cultured in a cytokines-containing medium, and the net increments of CFU-GM and high proliferative potential colony forming cell (HPP-CFC) were evaluated. RESULTS: CFU-GM increased by 33.7 +/- 18.1- or 18.1 +/- 6.3- fold, and HPP-CFC by 17.8 +/- 10.5- or 12.7 +/- 9.1- fold, respectively, in cultures containing SCF with IL- or IL-3, as compared with that in control; while SCF alone had little effect. Compared with fresh d3-5FU-BMC, transplantation of the expanded bone marrow cells accelerated the recovery of recipients' peripheral blood cell counts by 1 approximately 3 days and increased the survival rate of the transplanted animals (d3-5FU-BMC group 50% vs expansion group 8U approximately 100%). CONCLUSION: SCF in combination with IL-1 or IL-3 synergetically ex vivo expands hematopoietic cells. Transplantation of the expanded bone marrow cells accelerates the recipient's hematopoietic reconstitution.

Animals↗

PubMed1997

[Identification and expression of ribulose 1,5-bisphosphate carboxylase/oxygenase gene from Thiobacillus versutus].

The chromosomal DNA of Thiobacillus versutus was hybridized with various heterologous ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) gene as probes. Only Rhodobacter sphaeroides form I RubisCO gene showed homology with T. versutus. The RubisCO gene fragment of T. versutus was isolated using the RubisCO gene of R. sphaeroides as a probe. And the RubisCO gene of T. versutus can express in E. coli cell.

DNA, Bacterial↗

PubMed1997

[Homology analysis of RubisCO gene of Thiobacillus versutus with extremelly acidophilic thiobacilli].

The chromosomal DNA of Thiobacillus thiooxidans and T. versutus was digested with restriction enzymes, blotted to nylon membrane by the way of Southern, and hybridized with the gene probe of ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) from T. ferrooxidans. The result showed that T. thiooxidans exhibited high homology with the probe anc T. versutus was less homology with it. However T. versutus can hybridize with the gene probe of RubisCO from Rhodobacter sphaeroides, which indicated that they had high homology with each other. As RubisCO was highly reserved in the evolutionary, they should be divided into different group.

DNA, Bacterial↗

PubMed1996

A tRNA identity switch mediated by the binding interaction between a tRNA anticodon and the accessory domain of a class II aminoacyl-tRNA synthetase.

Identity elements in tRNAs and the intracellular balance of tRNAs allow accurate selection of tRNAs by aminoacyl-tRNA synthetases. The histidyl-tRNA from Escherichia coli is distinguished by a unique G-1.C73 base pair that upon exchange with other nucleotides leads to a marked decrease in the rate of aminoacylation in vitro. G-1.C73 is also a major identity element for histidine acceptance, such that the substitution of C73 brings about mischarging by glycyl-, glutaminyl-, and leucyl-tRNA synthetases. These identity conversions mediated by the G-1.C73 base pair were exploited to isolate secondary site revertants in the histidyl-tRNA synthetase from E. coli which restore histidine identity to a histidyl-tRNA suppressor carrying U73. The revertant substitutions confer a 3-4 fold reduction in the Michaelis constant for tRNAs carrying the amber-suppressing anticodon and map to the C-terminal domain of HisRS and its interface with the catalytic core. These findings demonstrate that the histidine tRNA anticodon plays a significant role in tRNA selection in vivo and that the C-terminal domain of HisRS is in large part responsible for recognizing this trinucleotide. The kinetic parameters determined also show a small degree of anticooperativity (delta delta G = -1.24 kcal/mol) between recognition of the discriminator base and the anticodon, suggesting that the two helical domains of the tRNA are not recognized independently. We propose that these effects substantially account for the ability of small changes in tRNA binding far removed from the site of a major determinant to bring about a complete conversion of tRNA identity.

Anticodon↗

PubMed1996

Development of an avian model for restenosis.

Recurrence of atherosclerotic plaque growth after interventional therapy, restenosis, is a significant clinical problem occurring in 20%-50% of cases. We have developed a new avian model for the investigation of restenosis after arterial injury in cholesterol fed White Leghorn roosters. Atherosclerotic plaque growth 1-30 weeks after angioplasty balloon mediated endothelial injury in the abdominal aorta was studied in 37 roosters. Roosters were maintained on either normal poultry diet or high cholesterol diet. Twelve cholesterol fed roosters were also fed a hormone supplemented diet in order to modify plaque morphology. The procedural success rate was high. Angiographic stenoses (mean 36% with maximum of 74%) were detectable in cholesterol fed roosters after balloon angioplasty with associated histological evidence of plaque growth (P < 0.017). Cholesterol feeding enhanced fatty plaque growth; hormone manipulation increased calcific and ulcerated plaque but with high associated morbidity. Three interventional devices were subsequently examined in 32 roosters (16 laser angioplasty, 7 atherectomy, and 9 stent implant). Plaque development was again assessed by contrast angiography and histological analysis. We conclude that balloon mediated arterial injury in cholesterol fed roosters produces early proliferative and late, complex atherosclerotic lesions providing an inexpensive model for plaque development after intimal injury.

Angioplasty, Balloon↗