Biomedical subjects

L Yuan

Publications and source records attributed to L Yuan.

At least 91 records · Page 5Linked to original sources

PubMed2000

[Effects of bite force lost on the expression of IL-6 in the rat periodontium].

OBJECTIVE: In order to explain the molecular mechanism of periodontium remodeling the expression of IL-6 in the rat periodontal ligament fibroblasts (PDLC) and the alveolar bone osteoblasts under normal and bite force lost was studied. METHODS: To establish a rat model of different bite force for the study, left maxillary molars of rats were extracted and the left mandibular molar area was used as the bite force lost. The animals were sacrificed after 6 hours, 1, 2, 3 days and 1, 2, 3, 4 weeks. The prepared tissue specimens were processed for the study of the change in the histologic morphology and the expression of IL-6 protein in PDLC and osteoblasts with HE staining and immunohistochemistry techniques. RESULTS: In the group of bite force lost, the loosely arrangement of periodontal ligaments and the resorption of alveolar bone were observed in histological study, the expression of IL-6 in PDLC and osteoblasts was enhanced apparently than that in the group of normal bite force by using immunohistochemistry techniques. In the group of lost bite force, the expression of IL-6 in PDLC enhanced with time regularly: The expression of IL-6 was strengthened after 3 days, and reached the peak after 2 weeks, then, decreased after that and restored to normality in 4 weeks. While in osteoblasts of the group of bite force lost, the expression of IL-6 was strengthened just after 2 weeks. CONCLUSION: Bite force lost induce the expression of IL-6 enhanced apparently in PDLC and osteoblasts, it suggests that IL-6 may play important roles in the effect of bite force on periodontium remodeling. It approaches initially the molecular mechanism of periodontium remodeling, demonstrates that the histologic morphology is closely related to the mechanical condition.

Alveolar Bone Loss↗

PubMed2000

[The influence of external stimulation on content and quality of volatile oil in Lignun Santali albi].

The authors analyzed the quality of Ligmum Santali Albi formed by the external stimulation of hormone and windburn by GC-MS-DS. The results showed that the content of volatile oil is 2.34% in the heart wood formed in 10 years tree age of Santalum album (SA) after 2 years stimulation continuously with a definite concentration of hormone, which is near to the 25 years tree age of SA in the same place. The GC-MS analysis showed that the content of santalol and other chemical components in volatile oil are similar to the 25 years tree age of SA. It is indicated that a definite concentration of hormone stimulated the SA may shorten the formation of the heart wood. The heart wood can be also formed by the broken branches after 2 years windburn, but its content of volatile oil is only 1/2 of the heart wood formed by hormone stimulation.

Age Factors↗

PubMed2000

[The study and manufacture of multifunctional brain microsurgery operation dilator].

The dilator consists of fixative clasp-handle, fixative platform, support arm, spatula and handle. The dilator may be fixed on the edge of bone window easily in the brain operation. The functions of the dilator include localization, dilation, expose, washing, lighting and suction. The spatula of the dilator may be prepared according to the different depth and width of the operation field.

Brain↗

PubMed2000

[Survival motor neuron gene and neuronal apoptosis inhibitory protein gene deletion in patients with spinal muscular atrophy].

OBJECTIVE: To investigate the frequencies of gene deletion survival motor neuron telomere (SMNTel) exon 7 and neuronal apoptosis inhibitory protein gene (NAIP) exon 5 in 55 Chinese spinal muscular atrophy (SMA) patients, and compare the relationship between these two candidate genes and the disease. METHODS: PCR-SSCP method was used to detect the deletion of SMNTel exon 7, direct visualization of PCR products by agarose electrophoresis was used to detect the deletion of NAIP exon 5 in 55 SMA patients with type I and type II. 40 normal individuals were involved in the study as controls. RESULTS: Homozygous deletion of the SMNTel exon 7 was identified in 92% (23/25) of SMA type I patients and 90% (27/30) of SMA type II patients. The same deletion was found in two mothers and one father of SMA patients. There was no homozygous deletion found in normal controls. None of the homozygous deletion of NAIP exon 5 was found in 55 SMA patients and normal controls. Only two patients were found to have the heterozygous deletion. CONCLUSIONS: The frequency of homozygous deletion of SMNTel exon 7 was 90.1%. Our data support that SMN gene is strongly associated with SMA.

Adult↗

PubMed2000

[Luminescence of zinc and europium composite alpha-thiophene carboxylate].

Zinc and europium composite alpha-thiophene carboxylate with very strong red luminescence was prepared from zine oxide, europium oxide, and alpha-thiophene carboxylic acid by a rheologic phase reaction method. The thermal stability and X-ray diffraction pattern were measured. The IR, UV, excitation and emission spectra were studied. The influence of zinc ion and thiophene on luminescence intensity was discussed. In zinc and europium composite alpha-thiophene carboxylate, zinc ion can reduce the concentration quenching and effectively enhance the luminescence of Eu3+ ion, thiophene ring can increase the luminescence efficiency.

Carboxylic Acids↗

PubMed2000

[Studies on synthesis and IR spectrum of nickel salicylates complexes].

Nickel salicylates complexes were synthesized with the rheologic phase reaction method. The composition of these complexes were confirmed by elemental analysis, TG and IR, the principal infrared absorption peaks were assigned for the region 4,000-400 cm-1. The IR spectra indicated that a hydroxyl group on Ni atom was occurred and so absorption peaks of hydroxyl group were shifted obviously to higher frequency in nickel monosalicylates.

Chelating Agents↗

PubMed1999

Isolation of a novel gene, TSP50, by a hypomethylated DNA fragment in human breast cancer.

A novel gene, testes-specific protease 50 (TSP50), was isolated from a human testes cDNA library by using a genomic DNA probe, BR50. BR50 was isolated by a modified representational difference analysis (RDA) technique due to its hypomethylated feature in a breast cancer biopsy. This altered DNA methylation status was also detected by BR50 in other breast and some ovarian cancer tissues. The TSP50 gene product is a homologue to several human proteases, which indicates that it may encode a protease-like protein. Northern analysis of 16 different types of normal human tissues suggests that TSP50 was highly and specifically expressed in human testes, which indicates that it might possess a unique biological function(s) in that organ. Methylation status analysis in normal human testes and other tissues showed a correlation between DNA methylation and gene expression. Most importantly, reverse transcription-PCR analysis of 18 paired breast cancer tissues found that in 28% of the cancer samples, the TSP50 gene was differentially expressed. The possibility that TSP50 may be an oncogene is presently under investigation.

Amino Acid Sequence↗

PubMed1999

Accelerated release and production of orphanin FQ in brain of chronic morphine tolerant rats.

Orphanin FQ has been shown to possess anti-opioid activity at supraspinal level. Our previous work revealed that chronic morphine tolerance could be reversed by intracerebroventricular (i.c.v.) injection of OFQ IgG to rats. In this study, we used radioimmunoassay (RIA) to assess the changes of Orphanin FQ immunoreactivity (OFQ-ir) in cerebroventricular perfusate, periaqueductal gray (PAG) and amygdala of rats made tolerance to morphine (10-60 mg/kg, s.c., t.i.d., for 5 days). The results indicated that: (1) In rats administrated with morphine for 3 and 5 days, the content of OFQ-ir in cerebroventricular perfusate increased by 25% and 52% over the NS control group. (2) The content of OFQ-ir in PAG of rats receiving 1d, 3d and 5d injections of morphine showed an increase of 17%, 48% and 81% respectively over NS group. (3) The content of OFQ-ir in amygdala of rats given 3d and 5d of morphine showed a 36% and 55% increase compared with corresponding control group. It is suggested that continuous use of high doses of morphine accelerated the release and biosynthesis of OFQ in rat brain to antagonize the effect of opioids, which may play a role in the development of morphine tolerance, and that brain OFQ may serve as a delayed negative feedback control on opioid analgesia.

Amygdala↗

PubMed1999

Outcome of pulmonary tuberculosis treatment in the tertiary care setting--Toronto 1992/93. Tuberculosis Treatment Completion Study Group.

BACKGROUND: Completion of treatment of active cases of tuberculosis (TB) is the most important priority of TB control programs. This study was carried out to assess treatment completion for active cases of pulmonary TB in Toronto. METHODS: Consecutive cases of culture-proven pulmonary TB were obtained from the microbiology laboratories of 5 university-affiliated tertiary care centres in Toronto in 1992/93. A standard data-collection tool was used to abstract information from inpatient and outpatient charts. For patients who were transferred to other treatment centres or lost to follow-up, the local health unit was contacted for information about treatment completion. If incomplete information was obtained from these sources, data from the provincial Reportable Disease Information System were also reviewed. The main outcome analysed was treatment outcome, with cases classified as completed (record of treatment completion noted), transferred (patient transferred to another centre but no treatment results available), defaulted (record of defaulting in patient chart but no record of treatment completion elsewhere, or patient still receiving treatment more than 15 months after diagnosis) or dead (patient died before treatment completion). RESULTS: Of the 145 patients 84 (58%) completed treatment, 25 (17%) died, 22 (15%) defaulted and 14 (10%) were transferred. The corresponding values for the 22 patients with HIV coinfection were 6 (27%), 5 (23%), 8 (36%) and 3 (14%). Independent predictors of failure to complete treatment were injection drug use (adjusted odds ratio [OR] 5.7, 95% confidence interval [CI] 1.5 to 22.0), HIV infection (adjusted OR 4.6, 95% CI 1.4 to 14.7) and adverse drug reaction (adjusted OR 2.9, 95% CI 1.1 to 7.9). Independent predictors of death included age more than 50 years (adjusted OR 16.7, 95% CI 2.6 to 105.1), HIV infection (adjusted OR 16.1, 95% CI 3.9 to 66.4), immunosuppressive therapy (adjusted OR 8.0, 95% CI 1.9 to 34.4) and infection with a multidrug-resistant organism (adjusted OR 30.7, 95% CI 1.5 to 623.0). INTERPRETATION: Treatment completion rates in tertiary care hospitals in Toronto in 1992/93 were below the rate recommended by the World Health Organization. Careful surveillance of treatment completion is necessary for the management of TB in metropolitan centres in Canada.

Adult↗

PubMed1999

Prevalence of Mycobacterium tuberculosis infection among injection drug users in Toronto.

BACKGROUND: Injection drug users are at increased risk of Mycobacterium tuberculosis infection and active tuberculosis (TB). The primary objective of this study was to determine the prevalence of M. tuberculosis infection among injection drug users in Toronto, as indicated by a positive tuberculin skin test result. An additional objective was to identify predictors of a positive skin test result in this population. METHODS: A cross-sectional study was carried out involving self-selected injection drug users in the city of Toronto. A total of 171 participants were recruited through a downtown Toronto needle-exchange program from June 1 to Oct. 31, 1996. RESULTS: Of 167 subjects tested, 155 (92.8%) returned for interpretation of their skin test result within the designated timeframe (48 to 72 hours). Using a 5-mm cut-off, the prevalence rate of positive tuberculin skin test results was 31.0% (95% confidence interval 23.8% to 38.9%). Birth outside of Canada and increasing age were both predictive of a positive result. INTERPRETATION: There is a high burden of M. tuberculosis infection in this population of injection drug users. The compliance observed with returning for interpretation of skin test results indicates that successful TB screening is possible among injection drug users.

Adult↗

PubMed1999

Hypoxia alters iron-regulatory protein-1 binding capacity and modulates cellular iron homeostasis in human hepatoma and erythroleukemia cells.

Ferritin and transferrin receptor expression is post-transcriptionally regulated by a conserved mRNA sequence termed the iron-responsive element (IRE), to which a transacting protein called the iron-regulatory protein (IRP) is bound. Our data demonstrate that hypoxia powerfully enhances IRE/IRP-1 binding in human cell lines. Using the human hepatoma cell line Hep3B as a model, we found that 16 h in a 1% oxygen atmosphere markedly increases IRE/IRP-1 binding as assessed by electromobility shift assay. Hypoxia also decreased cytosolic aconitase activity. The hypoxia-enhanced IRE/IRP-1 binding stabilized the transferrin receptor message, increased the cellular mRNA content by over 10-fold, and doubled surface receptor expression. Simultaneously, hypoxia suppressed ferritin message translation. Hypoxia's effect was most strikingly depicted by the absence of ferritin synthesis in cells challenged with inorganic iron. Our results contrast with previously reported data (Hanson, E. S., and Leibold, E. A. (1998) J. Biol. Chem. 273, 7588-7593) in which a 3% oxygen atmosphere reduced IRE/IRP-1 binding in rat hepatoma cells. We discuss some possible reasons for the differences. In aggregate with other investigations involving responses to hypoxia, iron, or nitric oxide, our data indicate that cellular iron metabolic responses are complex and that IRE/IRP-1 interactions vary between cell lines and perhaps between species.

Animals↗

PubMed1999

Adoptive immunotherapy prevents prostate cancer in a transgenic animal model.

Cancer-related mortality can be decreased by prevention, early detection and improved therapies. Although animal models should be used to evaluate the success of cancer therapies, their usefulness is controversial. Many cancer therapies that have cured tumors in mice have not met with similar success when attempted in humans. Current animal models rely mainly on inoculating cell lines into animals, a method that does not reproduce the natural development of the tumor, both for the kinetics of induction and the anatomical site concerned. In this study, we have used an SV40 T-antigen-transgenic mouse model of prostate cancer in which the tumor spontaneously develops orthotopically with a disease progression that closely resembles the progression of human prostate cancer. We have used this model to test the suitability of adoptive cellular immunotherapy. Transfer of naive cells obtained from a T-antigen-negative congenic animal had significant but partial effects: it prevented development of malignant tumors, leaving just minor foci of residual tumor and/or hyperplasia. Adoptive transfer of memory lymphocytes specific for T-antigen, which is a prostatic self antigen in this model, prevented tumor development and progression without affecting the morphology and function of involved tissues. Treated animals were able to breed, and their survival was greatly increased. These results strongly suggest that adoptive immunotherapy should be successful in treating early stages of human prostate cancer.

Adenocarcinoma↗

PubMed1999

Dislocation after total hip arthroplasty.

Hip dislocation has long been one of the major complications after total hip arthroplasty (THA). From 1980 to 1994, we performed 2728 THAs (including primary and revision cases). There were 97 hips (3. 6%) with the complication of dislocation, 62 of which were followed up for at least 2 years (mean 5.3 years; range 2-12 years). Single dislocations occurred in 40% and recurrent dislocations in 60%. More than half of the dislocations (58%) occurred within 3 months after the index operation. The dislocation rate was not related to sex, age, previous revision surgery, or types of prosthesis, but was related to a smaller size of the femoral head. The rate of recurrent dislocation was not related to a history of previous surgery, but was related to a smaller femoral head, late onset of dislocation (> 3 months), soft-tissue imbalance, and cup malposition in both anteversion and inclination. If the size of the femoral head was 26 mm or smaller, a posterior approach was not recommended. Closed reduction followed by 1-2 weeks of skin traction was the treatment of choice. The success rate for the first attempt at closed reduction for the treatment of dislocation was 41%; the success rate decreased gradually with the number of attempts. For the recurrent dislocation group, bracing for 4-6 weeks with training was recommended for the postural type and bracing for 3 months with muscle training for the soft-tissue imbalance type. Only 15% of the dislocated hips needed re-operation, and most of the patients resolved the problem after being informed and undergoing muscle training.

Age Distribution↗

PubMed1999

Cloning of delta12- and delta6-desaturases from Mortierella alpina and recombinant production of gamma-linolenic acid in Saccharomyces cerevisiae.

Two cDNA clones with homology to known desaturase genes were isolated from the fungus Mortierella alpina. The open reading frame in one clone encoded 399 amino acids and exhibited delta12-desaturase activity when expressed in Saccharomyces cerevisiae in the presence of endogenous fatty acid substrate oleic acid. The insert in another clone contained an open reading frame encoding 457 amino acids and exhibited delta6-desaturase activity in S. cerevisiae in the presence of exogenous fatty acid substrate linoleic acid. Expression of the delta12-desaturase gene under appropriate media and temperature conditions led to the production of linoleic acid at levels up to 25% of the total fatty acids in yeast. When linoleic acid was provided as an exogenous substrate to the yeast cultures expressing the delta6-desaturase activity, the level of gamma-linolenic acid reached 10% of the total yeast fatty acids. Co-expression of both the delta6- and delta12-desaturase cDNA resulted in the endogenous production of gamma-linolenic acid. The yields of gamma-linolenic acid reached as high as 8% of total fatty acids in yeast.

Amino Acid Sequence↗

PubMed1999

Improved stearate phenotype in transgenic canola expressing a modified acyl-acyl carrier protein thioesterase.

The engineering of crops for selected fatty acid production is one of the major goals of plant biotechnology. The Garm FatA1, an acyl-acyl carrier protein (ACP) thioesterase isolated from Garcinia mangostana, generates an elevated stearate (18:0) phenotype in transgenic Brassica plants. By site-directed mutagenesis, we generated seven mutants that showed up to a 13-fold increase in specific enzyme activity toward 18:0-ACP in vitro. The seed-specific expression of mutant S111A/V193A in Brassica plants results in transgenic plants that accumulate 55-68% more stearate than plants expressing the wild-type enzyme. Our results demonstrate that a thioesterase can be engineered to increase specific activity and that its improved function demonstrated in vitro is retained in vivo.

Amino Acid Sequence↗

PubMed1999

Multipoint analysis of human chromosome 11p15/mouse distal chromosome 7: inclusion of H19/IGF2 in the minimal WT2 region, gene specificity of H19 silencing in Wilms' tumorigenesis and methylation hyper-dependence of H19 imprinting.

WT2 is defined by maternal-specific loss of heterozygosity (LOH) on chromosome 11p15.5 in Wilms' tumors (WTs). The imprinted H19 gene, in this region, is silenced and hypermethylated in most WTs, and this is linked to pathological biallelic expression of IGF2. However, H19 and IGF2 lie within a larger imprinted domain, and the gene specificity of H19 epimutation has been a persistent question. To address this, we assessed LOH, gene expression and DNA methylation at multiple sites in and around the imprinted domain. LOH mapping showed that the entire domain, including IGF2/H19, is within the minimal WT2 region. Genes within the domain, including IPL/TSSC3/BWR1C, IMPT1/ORCTL2/BWR1A/TSSC5, KvLQT1/KCNA9 and TAPA1/CD81, as well as the zinc finger gene ZNF195/ZNFP104 near the centromeric border, were expressed persistently in many WTs. DNA hypermethylation was not detected with 5" upstream probes for IPL, IMPT1, KvLQT1 and ZNF195 in WTs or WT-associated kidneys. Fully developed WTs showed variable hypomethylation at an imprinted CpG island in a KvLQT1 intron, but this was only complete in the cases with LOH and was not observed in pre-neoplastic WT-associated kidneys with H19 epimutation. Analysis of the corresponding region of mouse chromosome 7 using methyltransferase-hypomorphic mice showed that the H19 imprint was fully erased, but that the allelic bias at Ipl, Impt1, p57 Kip2 and, to a lesser extent, Kvlqt1, persisted. Pre-existing massive allelic asymmetry for DNA methylation and hyper-dependence of transcription on methylation status may underlie the mechanism of gene-specific silencing of H19 in Wilms' tumorigenesis.

Animals↗

PubMed1999

Regulation of HOXA-10 and its expression in normal and abnormal endometrium.

HOXA-10 is a member of a family of genes that serve as transcription factors during development and have been shown to be important for uterine function. Using immunohistochemistry and RNAse protection assays (RPA), HOXA-10 was shown to be expressed in both epithelial and stromal cells with increased expression during the window of implantation. By in-vitro culture of isolated endometrial epithelium or stroma, HOXA-10, expression was increased after treatment with oestradiol (10(-8) mol/l) with or without progesterone (10(-6) mol/l). In stromal cells, oestradiol and progesterone both appeared to increase HOXA-10 expression and were additive. Relaxin (30 ng/ml) appeared to further increase stromal HOXA-10 expression. HOXA-10 expression during the window of implantation was compared in normal menstrual cycles to endometrium from women with endometriosis and suspected defects in uterine receptivity. Little or no difference was seen in luminal, glandular or endothelial HOXA-10 expression but a significant reduction in stroma HOXA-10 expression was noted in women with endometriosis. In conclusion, HOXA-10 is a hormone-regulated endometrial transcription factor that appears to be responsive to both ovarian steroids and relaxin. The appearance of this nuclear protein during the window of implantation in epithelium and stroma may offer new insight into the regulation of uterine receptivity and assist in the identification of other genes that are critical to the establishment of a successful pregnancy.

Cells, Cultured↗

PubMed1999

Serum and intestinal isotype antibody responses to Wa human rotavirus in gnotobiotic pigs are modulated by maternal antibodies.

The effects of passive antibodies on protection and active immune responses to human rotavirus were studied in gnotobiotic pigs. Pigs were injected at birth with saline or sow serum of high (immunized) or low (control) antibody titre and subsets of pigs were fed colostrum and milk from immunized or control sows. Pigs were inoculated at 3-5 days of age and challenged at 21 days post-inoculation (p.i.) with virulent Wa human rotavirus. Pigs receiving immune serum with or without immune colostrum/milk were partially protected against diarrhoea and virus shedding after inoculation, but had significantly lower IgA antibody titres in serum and small intestinal contents at 21 days p.i. and lower protection rates after challenge compared with pigs given control or no maternal antibodies. IgG antibody titres were consistently higher in small than in large intestinal contents. Pigs given control serum with control colostrum/milk had lower rates of virus shedding after inoculation than those given control serum alone. In summary, high titres of circulating maternal antibodies with or without local (milk) antibodies provided passive protection after inoculation but suppressed active mucosal antibody responses. These findings may have implications for the use of live, oral rotavirus vaccines in breast-fed infants.

Animals↗