Biomedical subjects

X Yu

Publications and source records attributed to X Yu.

At least 73 records · Page 4Linked to original sources

PubMed2001

Immune responses to the expressed products of the CSP antigen gene of plasmodium falciparum southern China isolate FCC1/HN in Hela cell.

OBJECTIVE: To construct a eukaryotic expression system with pcDNA3-PfCSP/Hela for the Circumsporozoite protein (CSP) gene of Plasmodium falciparum (P. falciparum), to observe the immune responses in BALB/c mice induced by the expressed proteins. METHODS: The recombinant plasmid pcDNA3-PfCSP was transformed into the Hela cell line. The expressed protein was isolated and analyzed by using SDS-PAGE and used for immunization of BALB/c mice by subcutaneous, intravenous, and intraperitoneal administration. Enzyme-linked immunosorbent assay (ELISA), Dot-ELISA, Western blot, T lymphocyte proliferation test, natural killer cell (NKC) activity assay, and CD4+ and CD8+ T cell detection were used for observation of humoral and cellular immune responses. RESULTS: Immune sera strongly reacted with the expressed protein, antibody titer was up to 1:6400 as detected by ELISA. Western blot analysis revealed a specific band at 38.3 Kda. When the spleen cells of normal and immunized BALB/c mice were specifically stimulated with expressed protein, the optical densities were 0.12 +/- 0.03 and 0.34 +/- 0.04, respectively. The latter were significantly higher than the former (P < 0.01). We used the MTT colorimetric assay to measure NKC activity of mice spleen. The results showed that the NKC activity of immunized BALB/c mice was remarkably higher than that of the controls (P < 0.05). CD4+ and CD8+ T cells were detected by using monoclonal antibody immunofluorescence methods. The results showed that the percentage of CD4+ and CD8+ T cells of immunized group were significantly higher than that of control group (P < 0.05). CONCLUSIONS: The humoral and cell-mediated immune responses and elevated NKC activity to products made with a eukaryotic expression system could be specifically detected in BALB/c mice. These findings indicate that the expressed protein could enhance the immune function in mice.

Animals↗

PubMed2001

Vitamin D receptor and PCNA expression in severe parathyroid hyperplasia of uremic patients.

OBJECTIVE: To clarify the role of vitamin D receptor (VDR) expression in parathyroid proliferation and resistance of parathyroid glands to 1,25(OH)2D3 with secondary hyperparathyroidism (SHPT). METHODS: This study used archive parathyroid with 7 uremic patients. The expression of proliferation cell nuclear antigen (PCNA) and VDR was evaluated in nineteen-surgically excised parathyroid tissues, including 11 diffuse hyperplasia (DH-type) and 8 nodular hyperplasia (NH-type) of parathyroid glands, by immunohistochemistry (avidin-biotin complex method). RESULTS: The weight of parathyroid in SHPT was remarkably increased by 16.1 times. The numbers of parathyroid cells were increased by 1.86 times. The rate of PCNA was remarkably increased in parathyroid hyperplasia with SHPT compared with that in control group [(6.35 +/- 3.36)@1000 vs (1.73 +/- 1.31)@1000, P < 0.001]. The number of PCNA in DH-type was lower than that in NH-type (P < 0.001). The density of VDR in the parathyroid with SHPT was significantly decreased [(40.28 +/- 13.13)% vs (83.79 +/- 3.77)%, P < 0.001], VDR immunoreactivity expression in NH-type was lower than that in DH-type [(27.14 +/- 4.12)% vs (49.84 +/- 7.33)%, P < 0.001]. A significantly negative correlation was found between VDR density and the weight of the parathyroid (r = -0.46, P < 0.05), the same as VDR and PCNA (r = -0.75, P < 0.001). CONCLUSION: VDR density was significantly decreased in parathyroid tissue of uremic patients showing nodular hyperplasia compared with that in diffuse hyperplasia and there was significantly negative correlation between VDR density and the weight of the parathyroid, and this may contribute to the progression of SHPT. Furthermore, VDR deficiency may cause the resistance of parathyroid cells to 1,25(OH)2D3, in part.

Adult↗

PubMed2001

[Appraisal of renal failure reversing therapies in lupus nephritis].

OBJECTIVE: This study aimed to explore the therapies of reversing renal failure in lupus nephritis. METHODS: The research strategy was a retrospective cohort study. 173 patients were included in the study. All of them were consecutive in-patients of newly diagnosed renal failure (serum creatinine > 180 micromol/L) with lupus nephritis from 1991 to 1999 in the university hospital. The research factors included steroids, cyclophosphamide and cyclosporin. Steroids were divided to oral prednisone, intravenous dexamethasone and intravenous methylprednisolone pulse; cyclophosphamide dose intensity was divided into three grades: none, low dose (average dose 0.25 g/m(2) body surface area per week). 51 demographic, clinical and laboratory data were included in the study as possible confounding factors. The study end-point was recovery of renal function that was defined as a level of serum creatinine <or= 116 micromol/L in the azotemia patients or a 50% reduction of serum creatinine and discontinuation of dialysis in the uremic patients. The improvement had to be maintained for at least three months. Collection of the study factors and outcome variable was conducted by two separate, blinded groups of clinical specialists with two structured abstracting forms. RESULTS: The number of complete following up patients was 142 (82.1%). After over 6 months of following up, 93 cases (65.5%) recovered their renal function and 17 cases (12.0%) died. In COX proportional hazard regression model, cyclophosphamide therapy was significantly associated with the recovery of renal function. The adjusted hazard ratio (HR) to recovery of renal function was 4.41, 95% CI = 1.03 - 18.94 in low dose; and the HR was 13.29, 95% CI = 3.11 - 56.82 in high dose cyclophosphamide therapy. The gender, duration of renal dysfunction, small renal size, severe anemia and serum creatinine were also significantly associated with renal function recovery. Cyclophosphamide therapy was not significantly associated with death. The variables associated with death were low level of serum albumin and edema. CONCLUSION: Cyclophosphamide pulse was an efficient therapy in reversing renal failure of lupus nephritis, especially in the patients with short duration of renal failure, non-small in renal size, and non-severe anemia.

Administration, Oral↗

PubMed2001

[Effects of seed coating formulation on seedling characters of Atractylodes macrocephala].

The effects of seed coating formulation (SCF) of Atractylodes macrocephala Koidz. on seedling in two experimental plots located in Hangzhou and Jiande were studied, and desinged with L9(3(4)) orthogonal comparison. The results showed that the SCF with paclobutrazol (pp333) had a significant effect on the rate of germination at Hangzhou plot, all factors had no significant effects on length of seedlings in both plots, and both atonik (sodium O-nitrophenolate) and PP333 on the fresh or dry seedling weight had significant effects.

Asteraceae↗

PubMed2001

Diagnosis and treatment of spinal fractures combined with paraplegia and diaphragm injury.

OBJECTIVE: To study the mechanism and treatment principle of spinal fractures combined with paraplegia and diaphragm injury. METHODS: A total of 16 patients (14 males and 2 females, aged from 18 to 50 years) with spinal fractures combined with paraplegia and diaphragm injury, receiving emergency treatment and admitted to our hospital in the past 20 years, were retrospectively analyzed in this study. RESULTS: The injuries were caused by direct or indirect violence. Six cases were of fractures of cervical spine combined with paraplegia and diaphragm injury, 2 of fractures of thoracic vertebra combined with paraplegia and diaphragm injury, and 8 of thoracolumbar fractures combined with paraplegia and diaphragm injury. Six cases received non-operative treatment, but died finally. Ten cases received spine surgical treatment, of which 4 died and 6 were improved. The total mortality rate was 62.5%. CONCLUSIONS: Spinal fractures combined with paraplegia and diaphragm injury are one of the most severe traumas in departments of orthopaedics. Paraplegia can be found easily, but diaphragm injury is often neglected and missed. When a patient suffers from both of them, he is in danger of death. What measures should be taken to rescue the patient's life depends on the severity of the wounds.

Adolescent↗

PubMed2001

Treatment of distal femoral nonunion and delayed union by using a retrograde intramedullary interlocking nail.

OBJECTIVE: To analyze the causes of distal femoral nonunion and delayed union and assess the outcome of the corresponding treatment, retrograde intramedullary interlocking nail (RIIN). METHODS: From June 1995 to December 1998, 15 patients (9 males and 6 females) with distal femoral nonunion and delayed union were treated with RIIN. The average age of the patients was 34.5 years (23-46 years). Bone grafting was performed in 10 patients, closed reaming was done in the other 5 patients. Correction osteotomy was performed in 2 patients, and intra-articular release of knee adhesion in 11 patients. X-ray examination and knee society clinical rating system (KSS) were used to evaluate the results. RESULTS: All fractures were followed up for at least 9 months with average follow-up duration of 14.5 months (9-33 months). Solid union was documented in all patients at 6.4 months on average. There were no infections or malunions in this series. Based on the final follow-up data, acceptable functional range of motion (ROM) of over 90 degrees was achieved in most patients. The average ROM was 93.5 degrees with significant improvement of 28 degrees (42.7%, P<0.05) compared with the preoperative ROM. The average knee score was 96. Excellent ROM emerged in 13 patients. The knee function score was 90.5 on average. CONCLUSIONS: The main causes of distal femoral nonunion and delayed union are improper indications and improper use of the implants. RIIN is an effective alternative for treatment of distal femoral nonunion and delayed union because it can provide a stable and reliable fixation which is beneficial for early functional exercise of knee. Bone grafting, closed reaming and intra-articular release of knee adhesion should be considered in order to enhance the bone healing and improve ROM and the knee function.

Adult↗

PubMed2001

[Preliminary study on the time of first appearance of "lanhousha" (scarlet fever)].

There are controversies about the problem of the source of "lanhousha" (scarlet fever) in the field of modern medical history, whether it is an epidemic appeared from the ancient time in our country or imported from other countries. Now, almost all researches were carried out around the classic medical books, especially "Medical Records of Ye Tianshi", and hardly dealing it in a historical context at that time. Through contrastive analysis between the records in medical books and historical facts, it is concluded that Ye Tianshi's records of scarlet fever have nothing to do with Ye Tianshi himself, and is by author of allonym. It perhaps was exogenous cold diseases spread when a severe epidemic diseases happened at Southern Jiangsu in the 11th year of Yongzheng reign. Even though there was some scarlet fever, it was not the first spread of scarlet fever in fact. Actually, in late Kangxi reign, scarlet fever was regarded as an epidemic disease seldom seen at Southern Jiangsu.

China↗

PubMed2001

[Research and establishment of the computerized orthodontic and orthopedic prediction system].

OBJECTIVE: The aim of this study was to develop a computerized orthopedics and orthodontics interactive prediction system and verify its reliability. METHODS: 24 cases of Angel II division I patients were selected in the study. All of them had been treated by activator or Frankel functional appliance, and had the satisfied therapy result. Both pre and post-treatment cephalogram of them were used verifying veracity of therapy prediction. RESULTS: All of cephalometric measure items include 11 angle measure items and 14 distance measure items. There were 9 coincidence indicators in angle measure items and 7 in distance measure items. CONCLUSION: The results indicate it is liable and effective to use the computerized orthopedics and orthodontics system for prediction.

Activator Appliances↗

PubMed2001

[Establishment and research of the computerized profile and photo prediction system].

OBJECTIVE: The study aims to develop a lateral oral facial profile and photo prediction system and then to verify its reliability. METHODS: 24 paired lateral cepholagrams in both pre- and post-treatment were selected and analyzed by three soft tissue cephalometric analysis methods in this study. All cases were of the angel II division I malocclusion, and had been successfully treated with the orthopedics therapy by activator or Frankel appliance. Soft tissue profile prediction had been automatically completed, following the hard tissue interactive orthopedics prediction approach in the pretreatment lateral cephalogram, and the predictive results were compared to the same cepholametric analysis in post-treatment cephalogram. RESULTS: There are 19 coincidence indicators in 30 measurements of three soft tissue cephalometric analysis, and 7 in 9 angel measurements, 10 in 18 instance measurements, 2 in 3 instance ratio measurements is consistency, respectively. CONCLUSION: The results indicate that the lateral oral facial profile and photo prediction system is effective in profile prediction.

Activator Appliances↗

PubMed2001

[Preparation of restricted-access media--alkyl-diol silica (ADS) by an improved method].

Alkyl-diol silica (ADS) is a kind of restricted-access media, which can be used for direct injection and analysis of complex biological samples containing bio-macromolecules. A new economical procedure has been developed to prepare ADS packing. At first gamma-glycidoxypropyl group was coupled onto the surface of microporous silica gel (Develosil 60-5 mu) to form epoxy-silica. Prepared epoxy-silica can react with stearic acid in organic solvent to prepare C18 ester-bonded reversed-phase packing. The packing was packed into a column and then the solution of pancreatic lipase was pumped into the column to create enzymoloysis reaction. The stearyl groups on the surface of packing can be removed by the enzymolysis to form a hydrophilic surface. At the same time, inner surface of micropore remains hydrophobic nature due to size exclusion effect of micropore to enzyme molecules. Chromatographic evaluations were carried out and the typical ADS behavior was confirmed.

Chromatography, High Pressure Liquid↗

PubMed2001

[The influence of type I collagen on the cell behavior of human embryonic periosteous osteoblasts].

OBJECTIVE: To study the influence of type I collagen (COL I) on the cell behavior of human periosteous osteoblasts (OB) and the application of type I collagen in constructing bioactive artifical bone. METHODS: OB were cultured on dishes coated with bovine type I collagen in different final concentrations. The cell adhesion was examined by the methods of cell count, the proliferation of OB was studied by 3H-TdR, and the osteoblastic ability was assessed by the synthesis of collagen, osteocalcin and alkaline phosphatase (ALP). RESULTS: OB cultured on type I collagen layer had the following characteristics: 1. The amounts of adhesive cells were maximal top in 25 micrograms/ml final concentration; 2. The proliferation of OB was decreased above 12.5 micrograms/ml final concentration (P < 0.05); 3. The synthesis of type I collagen was reduced slightly (above 25 micrograms/ml, P < 0.05); 4. The secretion of osteocalcin was increased markedly (above 6.25 micrograms/ml, P < 0.05, which reached maximally in 25 micrograms/ml); 5. The ALP activity was also increased (above 12.5 micrograms/ml, P < 0.05). CONCLUSION: Type I collagen promotes the expression of osteoblastic phenotype and cell adhesion. When the scaffold materials for bone tissue engineering are coated with type I collagen, the osteogenesis of OB is enhanced to accelerate the transformation course from artificial bone to biological bone, the best final concentration is 25 micrograms/ml.

Alkaline Phosphatase↗

PubMed2000

Erythropoietin stimulates proliferation and interferes with differentiation of myoblasts.

Erythropoietin (Epo) is required for the production of mature red blood cells. The requirement for Epo and its receptor (EpoR) for normal heart development and the response of vascular endothelium and cells of neural origin to Epo provide evidence that the function of Epo as a growth factor or cytokine to protect cells from apoptosis extends beyond the hematopoietic lineage. We now report that the EpoR is expressed on myoblasts and can mediate a biological response of these cells to treatment with Epo. Primary murine satellite cells and myoblast C2C12 cells, both of which express endogenous EpoR, exhibit a proliferative response to Epo and a marked decrease in terminal differentiation to form myotubes. We also observed that Epo stimulation activates Jak2/Stat5 signal transduction and increases cytoplasmic calcium, which is dependent on tyrosine phosphorylation. In erythroid progenitor cells, Epo stimulates induction of transcription factor GATA-1 and EpoR; in C2C12 cells, GATA-3 and EpoR expression are induced. The decrease in differentiation of C2C12 cells is concomitant with an increase in Myf-5 and MyoD expression and inhibition of myogenin induction during differentiation, altering the pattern of expression of the MyoD family of transcription factors during muscle differentiation. These data suggest that, rather than acting in an instructive or specific mode for differentiation, Epo can stimulate proliferation of myoblasts to expand the progenitor population during differentiation and may have a potential role in muscle development or repair.

Animals↗

PubMed2000

Ischemic inactivation of G protein-coupled receptor kinase and altered desensitization of canine cardiac beta-adrenergic receptors.

BACKGROUND: G protein-coupled receptor kinases (GRKs) modulate myocardial beta-adrenergic receptor (betaAR) signaling. We examined whether GRK activity was altered 6, 24, and 96 hours after left anterior descending coronary artery ligation (LAD CAL) in the dog. METHODS AND RESULTS: GRK activity was measured in arrhythmogenic subepicardial border zone (EBZ) tissue overlying the infarct and from nonischemic remote-site (RS) subepicardial tissue from the same animal. GRK activity in the ischemic EBZ was 15% of RS (P:=0.03, n=6) 24 hours after CAL and appeared to start as early as 6 hours through 96 hours. GRK activity and immunoblot data demonstrated a marked decrease of GRK2 but not GRK5 at 24 hours. EBZ tissue exhibited high-affinity binding for (-)-isoproterenol (K:(i) of 0. 076+/-0.026 nmol/L [SEM]) at 24 hours, which was not significantly different from control tissue from nonoperated animals (1.2+/-0.8 nmol/L, P:>0.05, n=6). A significantly lower K:(i) of 13.8+/-2.8 nmol/L (P:<0.001, n=6) was observed for RS taken from the ischemic animals. This was reflected by a 4-fold increase in the EC(50) of isoproterenol-stimulated adenylyl cyclase activity from 18 nmol/L in EBZ tissue to 73 nmol/L in RS (P:<0.05, n=4). CONCLUSIONS: There is a selective decrease in GRK2 activity and a loss of the ability of the arrhythmia-prone EBZ tissue to desensitize to beta-adrenergic stimulation 24 hours after CAL. This correlates temporally with a second (late) peak in sudden cardiac death previously observed between 6 and 24 hours in dog and rat models of myocardial infarction.

Adenylyl Cyclases↗

PubMed2000

Characterization of the promoter of human leukocyte-specific transcript 1. A small gene with a complex pattern of alternative transcripts.

The gene for the human leukocyte-specific transcript 1 (LST1) encodes a small protein that modulates immune responses and cellular morphogenesis. The LST1 transcripts are expressed at high levels in dendritic cells. Because of the complex splicing pattern, use of alternative 5'-untranslated exons, and a biologically interesting pattern of expression of LST1 mRNA, we studied the human LST1 gene promoter and regulatory elements. We identified an additional upstream 5'-untranslated exon in U937 monocytic cells. Transient transfection studies demonstrated that the combination of regions from -1363 to -621 with -112 to -54, relative to the translation start codon, produced the highest level of transcripts from among the various constructs tested, but the pattern of transcripts produced was only a subset of those produced from the endogenous gene. DNase I footprinting analysis and electrophoretic mobility shift assays showed that oligonucleotide probes corresponding to three regions, -1171 to -1142 (BI), -1136 to -1111 (BII), and -783 to -751 (BIV), bound proteins in U937 nuclear extracts. Competition and supershift electrophoretic mobility shift assay did not identify any known transcription factors responsible for BII probe binding. These studies suggest that a novel DNA-binding site and interaction of multiple regulatory elements may be involved in mediating the expression of the various forms of LST1 mRNA.

Alternative Splicing↗

PubMed2000

Production and processing of erythropoietin receptor transcripts in brain.

The expression of erythropoietin receptor (EpoR) in brain and neuronal cells, and hypoxia-responsive production of erythropoietin (Epo) in the brain suggests that the function of Epo as a survival or viability factor may extend beyond hematopoietic tissue and erythroid progenitor cells. Epo, produced by astrocytes and neurons, can be induced by hypoxia by severalfold, and in animal models Epo administration is neuroprotective to ischemic challenge. We characterized the human EpoR transcript in brain and neuronal cells to determine its contribution in regulating the Epo response in brain. Screening of a human brain cDNA library and quantitative analysis of EpoR transcripts indicate that the EpoR gene locus is transcriptionally active in brain. In addition to the proximal promoter that is active in hematopoietic cells, a significant proportion of transcripts originates far upstream from the EpoR coding region. Unlike erythroid cells with efficient splicing of EpoR transcripts to its mature form, brain EpoR transcripts are inefficiently or alternately processed with a bias towards the 3' coding region. In human EpoR transgenic mice, anemic stress induces expression of the transgene and endogenous EpoR gene in hematopoietic tissue and brain. In culture of neuronal cells, hypoxia induces EpoR expression and increases sensitivity to Epo. Induction of EpoR expression appears to be a consequence of increased transcription from the upstream region and proximal promoter, and a shift towards increased processing efficiency. These data suggest that in contrast to erythropoiesis where erythroid progenitor cells express high levels of EpoR and are directly responsive to Epo stimulation, the neuroprotective effect of Epo and its receptor may require two molecular events: the induction of Epo production by hypoxia and an increase in EpoR expression in neuronal cells resulting in increased sensitivity to Epo.

Adult↗

PubMed2000

The polarity and magnitude of ambient charge influences three-dimensional neurite extension from DRGs.

Sulfated proteoglycans have inhibitory effects on neurite extension, and the negative charge of the glycosaminoglycan side chains may be involved in the inhibitory process. The main goal of this study is to investigate the effects of charge on three-dimensional neurite extension. Various concentrations of dermatan sulfate (DS), a chondroitin sulfate glycosaminoglycan, and consequently, various degrees of negative charge were presented on three-dimensional agarose hydrogels and the effect of charge on neurite extension from primary neurons was investigated. Dose-response experiments were also performed with the polycationic (positively charged) polysaccharide chitosan covalently coupled to agarose. The amount of DS or chitosan coupled to the agarose gel was quantified via metachromatic dye or Fourier transform infrared spectroscopy methods, respectively. The length of embryonic day 9 (E9) chick dorsal root ganglia neurites extended through charged agarose gels is dependent on the polarity and quantity of ambient charge. The inhibitory effects of the sulfated DS and the enhancing effects of the polycationic chitosan on neurite extension decrease as the amount of DS or chitosan coupled to agarose is decreased. These findings indicate that primary neural process extension is influenced by the polarity of ambient charge in a dose-responsive manner.

Animals↗

PubMed2000

Three-dimensional reconstruction of transcription termination factor rho: orientation of the N-terminal domain and visualization of an RNA-binding site.

The Escherichia coli rho transcription termination protein is a hexameric helicase, and is believed to function by separating an RNA-DNA hybrid. Unlike hexameric DNA helicases, where a single strand of DNA passes through the central channel, it has been proposed that the RNA wraps around the outside of the ring. We have generated a three-dimensional reconstruction of rho, and localized a tRNA molecule bound to the primary RNA-binding site to the outside of the ring. An atomic structure of the N-terminal domain of rho fits into our reconstruction uniquely, with the residues involved in RNA-binding on the outside of the ring. Although rho shares a common structural core with the F1-ATPase and other hexameric helicases, there has been a divergence in function due to rho's N-terminal domain, which has no homology to other helicases.

Binding Sites↗

PubMed2000

Nuclear localization and cell cycle-specific expression of CtIP, a protein that associates with the BRCA1 tumor suppressor.

The BRCA1 tumor suppressor has been implicated in a diverse spectrum of cellular processes, including transcriptional regulation, DNA repair, and cell cycle checkpoint control. CtIP was recently identified as a protein that associates with BRCA1 and two other nuclear factors, CtBP1 and Rb1. To understand the functions of CtIP, we have evaluated its biological properties with respect to those of BRCA1. Our results show that CtIP, like its associated factors, is predominantly a nuclear protein. A subset of the endogenous pool of CtIP polypeptides exists in a protein complex that includes both BRCA1 and the BRCA1-associated RING domain protein (BARD1). At the protein level, CtIP expression varies with cell cycle progression in a pattern identical to that of BRCA1. Thus, the steady-state levels of CtIP polypeptides, which remain low in resting cells and G(1) cycling cells, increase dramatically as dividing cells traverse the G(1)/S boundary. In contrast to BRCA1, however, the G(1)/S induction of CtIP expression is mediated primarily by post-transcriptional mechanisms. Finally, the interaction between CtIP and BRCA1 is shown to be stable in the face of genotoxic stress elicited by treatment with UV light, adriamycin, or hydrogen peroxide. Together, these results indicate that CtIP can potentially modulate the functions ascribed to BRCA1 in transcriptional regulation, DNA repair, and/or cell cycle checkpoint control.

Animals↗