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Biomedical subjects

X Ling

Publications and source records attributed to X Ling.

At least 19 recordsLinked to original sources
PubMed2001

Cephalometric image analysis and measurement for orthognathic surgery.

Automatic identification of landmarks in cephalometry is very important and useful for orthognathic surgery. A computerised automatic cephalometric analysis system (CACAS), based on image processing, is presented. For an original X-ray image, median filtering and histogram equalisation are used to improve image quality. The edge of an X-ray image is detected by a wavelet transform and Canny filter. Seventeen landmarks in cephalometry are successfully identified by knowledge-based edge tracing and changeable templates. Seventy-three measurements based on distances, angles and ratios between landmarks are computed automatically. The reliability of the landmarks and the validity of the measurements are compared for automatic and manual operation. The values of measurements obtained by CACAS are more precise and reliable: the mean error for linear measurements is less than 0.9mm; the mean error for angular measurements is less than 1.2 degrees. The rate of validity is over 80%, even if the image quality is poor. For an image with a high signal-to-noise ratio, the rate of validity of landmarking and measurements using the CACAS system is over 90%.

Cephalometry↗
PubMed2001

Genetic basis for susceptibility to noise-induced hearing loss in mice.

The C57BL/6J (B6) and DBA/2J (D2) inbred strains of mice exhibit an age-related hearing loss (AHL) due to a recessive gene (Ahl) that maps to Chromosome 10. The Ahl gene is also implicated in the susceptibility to noise-induced hearing loss (NIHL). The B6 mice (Ahl/Ahl) are more susceptible to NIHL than the CBA/CaJ (CB) mice (+(Ahl)). The B6xD2.F(1) hybrid mice (Ahl/Ahl) are more susceptible to NIHL than the CBxB6.F(1) mice (+/Ahl) [Erway et al., 1996. Hear. Res. 93, 181-187]. These genetic effects implicate the Ahl gene as contributing to NIHL susceptibility. The present study demonstrates segregation for the putative Ahl gene and mapping of such a gene to Chromosome 10, consistent with other independent mapping of Ahl for AHL in 10 strains of mice [Johnson et al., 2000. Genomics 70, 171-180]. The present study was based on a conventional cross between two inbred strains, CBxB6.F(1) backcrossed to B6 with segregation for the putative +/Ahl:Ahl/Ahl. These backcross progeny were exposed to 110 dB SPL noise for 8 h. All of the progeny were tested for auditory evoked brainstem responses and analyzed for any significant permanent threshold shift of NIHL. Cluster analyses were used to distinguish the two putative genotypes, the least affected with NIHL (+/Ahl) and most affected with PTS (Ahl/Ahl). Approximately 1/2 of the backcross progeny exhibited PTS, particularly at 16 kHz. These mice were genotyped for two D10Mit markers. Quantitative trait loci analyses (log of the odds=15) indicated association of the genetic factor within a few centiMorgan of the best evidence for Ahl [Johnson et al., 2000. Genomics 70, 171-180]. All of the available evidence supports a role for the Ahl gene in both AHL and NIHL among these strains of mice.

Animals↗
PubMed2001

Immunohistochemical distribution and quantitative biochemical detection of advanced glycation end products in fetal to adult rats and in rats with streptozotocin-induced diabetes.

SUMMARY: We used immunohistochemical methods and four monoclonal antibodies for specific molecular structures of advanced glycation end products (AGE)-6D12, KNH-30, 1F6, and 2A2-to examine localization of AGE in fetal, young, and adult rats, and rats with streptozotocin-induced diabetes. 6D12 recognized N(epsilon)-(carboxymethyl)lysine (CML); KNH-30, N(epsilon)-(carboxyethyl)lysine (CEL); and 1F6, fluorolink. The epitope of 2A2 is as yet unknown. Immunoreactivities for these monoclonal antibodies were found in various organs and tissues in postnatal and adult rats, and accumulation increased with aging. In the fetuses, AGE structures were detected at 10 fetal days, and their accumulation increased during ontogeny. Reversed-phase high-performance liquid chromatography revealed CML in fetuses at 13 fetal days and in lungs of 28-week-old rats. In various organs and tissues of fetal, young, and adult rats, CML, CEL, 2A2-positive AGE, and fluorolink accumulated, in that order, which suggests that the accumulation of CML, a nonfluorescent/noncross-linked AGE, occurs earlier than accumulation of fluorolink, a fluorescent/cross-linked AGE. In diabetic rats, hepatocytes, splenic macrophages, renal glomerular endothelial and mesangial cells, testicular Leydig cells, and erythrocytes showed excessive accumulation of AGE, leading to the pathologic changes characteristic of diabetes mellitus. For the induction of these changes, persistent hyperglycemia and hyperketonemia might be important for acceleration of intracellular AGE accumulation in diabetic rats. Thus, AGE accumulation in tissues and cells occurs not only during aging and in diabetes mellitus but also from an early stage of ontogeny.

Aging↗
PubMed2000

An immunosuppressive and anti-inflammatory HLA class I-derived peptide binds vascular cell adhesion molecule-1.

BACKGROUND: A synthetic peptide corresponding to residues 75-84 of HLA-B2702 modulates immune responses in rodents and humans both in vitro and in vivo. METHODS: We used a yeast two-hybrid screening, an in vitro biochemical method, and an in vivo animal model. RESULTS: Two cellular receptors for this novel immunomodulatory peptide were identified using a yeast two-hybrid screen: immunoglobulin binding protein (BiP), a member of the heat shock protein 70 family, and vascular cell adhesion molecule (VCAM)-1. Identification of BiP as a ligand for this peptide confirms earlier biochemical findings, while the interaction with VCAM-1 suggests an alternative mechanism of action. Binding to the B2702 peptide but not to closely related variants was confirmed by ligand Western blot analysis and correlated with immunomodulatory activity of each peptide. In mice, an ovalbumin-induced allergic pulmonary response was blocked by in vivo administration of either the B2702 peptide or anti-VLA-4 antibody. CONCLUSIONS: We propose that the immunomodulatory effect of the B2702 peptide is caused, in part, by binding to VCAM-1, which then prevents the normal interaction of VCAM-1 with VLA-4.

Amino Acid Sequence↗
PubMed2000

Proliferating cell nuclear antigen as the cell cycle sensor for an HLA-derived peptide blocking T cell proliferation.

Synthetic peptides corresponding to structural regions of HLA molecules are novel immunosuppressive agents. A peptide corresponding to residues 65-79 of the alpha-chain of HLA-DQA03011 (DQ65-79) blocks cell cycle progression from early G1 to the G1 restriction point, which inhibits cyclin-dependent kinase-2 activity and phosphorylation of the retinoblastoma protein. A yeast two-hybrid screen identified proliferating cell nuclear Ag (PCNA) as a cellular ligand for this peptide, whose interaction with PCNA was further confirmed by in vitro biochemistry. Electron microscopy demonstrates that the DQ65-79 peptide enters the cell and colocalizes with PCNA in the T cell nucleus in vivo. Binding of the DQ65-79 peptide to PCNA did not block polymerase delta (pol delta)-dependent DNA replication in vitro. These findings support a key role for PCNA as a sensor of cell cycle progression and reveal an unanticipated function for conserved regions of HLA molecules.

Cell Cycle↗
PubMed2000

A novel DNA element mediates transcription of Nkx2.1 by Sp1 and Sp3 in pulmonary epithelial cells.

NKX2.1 is a member of the NK2 family of homeodomain-containing transcription factors whose targeted disruption in mouse results in the absence of thyroid tissue and a severely abnormal lung phenotype. Little is known regarding the mechanisms that control tissue and temporal specificity of Nkx2.1 gene expression. The Nkx2.1 gene has been cloned from a number of species and it is composed of three exons and two introns. Two distinct DNA domains located 5' of exon I and within intron I have been found to exhibit promoter activity in lung and thyroid cells. In the current study we used deletional analysis of the 5' flanking region of exon I and identified a 300 bp TATA-less region that exhibits significant promoter activity in H441 cells. The DNA sequence of this region contains multiple palindromes, composed of G/C-rich elements. DNase I footprinting demonstrates that this promoter region interacts with nuclear factors present in H441 cells. In particular electrophoretic mobility shift assay using antibodies against the Sp family members show that both Sp1 and Sp3 as well as an as yet unknown H441-specific factor interact with the palindromic structure within this promoter region. Co-transfection studies show that this promoter region responds to Sp1 and Sp3 and mutations therein result in a significantly diminished response to these transcriptional factors. Therefore, we have identified a novel DNA structure on the Nkx2.1 gene which participates in transcription of this gene in pulmonary epithelial cells by Sp1 and Sp3 transcription factors.

Base Sequence↗
PubMed2000

Identification of differentiation antigens in mouse testicular germ cells recognized by monoclonal antibody TRA 55.

We have isolated a monoclonal antibody (mAb) TRA 55, which recognizes mouse testicular germ cells from mid-pachytene spermatocytes to the early stages of haploid spermatids during differentiation. Immunohistochemical analysis produced strong positive staining of the nuclei and faint staining in the cytoplasm of germ cells. At meiotic division, when the nuclear membrane disappeared, a specific positive signal could be observed on metaphase chromosomes. When germ cells produced haploid spermatids, antigenicity became suddenly weak and soon disappeared. TRA 55 did not react with testicular somatic cells, such as Sertoli cells or Leydig cells. Western blot analysis of the whole testis showed four positive bands with molecular weights of 43, 46, 49 and 55 kDa. Three bands of 43, 49 and 55 kDa, and a single band of 46 kDa were recovered in cytoplasmic and nuclear fractions of testicular germ cells, respectively. Chronological changes in the Western blot pattern indicated that these antigens became detectable in the testis at the age of 10 days. Furthermore, all antigens were resistant to periodate treatment, suggesting that the epitope was in an amino acid rather than a sugar moiety. These antigen molecules may play important roles in the differentiation of germ cells at the later stages of meiotic prophase and meiotic division in the mouse testis.

Animals↗
PubMed2000

The role of reactive nitrogen species in secondary spinal cord injury: formation of nitric oxide, peroxynitrite, and nitrated protein.

To determine whether reactive nitrogen species contribute to secondary damage in CNS injury, the time courses of nitric oxide, peroxynitrite, and nitrotyrosine production were measured following impact injury to the rat spinal cord. The concentration of nitric oxide measured by a nitric oxide-selective electrode dramatically increased immediately following injury and then quickly declined. Nitro-L-arginine reduced nitric oxide production. The extracellular concentration of peroxynitrite, measured by perfusing tyrosine through a microdialysis fiber into the cord and quantifying nitrotyrosine in the microdialysates, significantly increased after injury to 3.5 times the basal level, and superoxide dismutase and nitro-L-arginine completely blocked peroxynitrite production. Tyrosine nitration examined immunohistochemically significantly increased at 12 and 24 h postinjury, but not in sham-control sections. Mn(III) tetrakis(4-benzoic acid)-porphyrin (a novel cell-permeable superoxide dismutase mimetic) and nitro-L-arginine significantly reduced the numbers of nitrotyrosine-positive cells. Protein-bound nitrotyrosine was significantly higher in the injured tissue than in the sham-operated controls. These results demonstrate that traumatic injury increases nitric oxide and peroxynitrite production, thereby nitrating tyrosine, including protein-bound tyrosine. Together with our previous report that trauma increases superoxide, our results suggest that reactive nitrogen species cause secondary damage by nitrating protein through the pathway superoxide + nitric oxide peroxynitrite protein nitration.

Amino Acids↗
PubMed2000

Vertebral fractures in Beijing, China: the Beijing Osteoporosis Project.

Women in China have much lower risk of hip fracture than women in Europe or North America but their risk of vertebral fractures is not known. Lateral spine radiographs, hip and lumbar spine bone density, and potential risk factors for and consequences of vertebral fractures were assessed in a random sample of 402 women age 50 years or older living in Beijing, China. The prevalence of vertebral fractures, defined by vertebral morphometry, increased from 5% (95% CI, 1-9%) in 50- to 59-year olds to 37% (27-46%) among women age 80 years or older. The age-standardized prevalence of vertebral fractures was 5.5% lower than found by similar methods for women in Rochester, MN, U.S.A. Each SD lower spine bone mineral density (BMD) was associated with a 2.4-fold (1.7-3.5) increased odds of having a vertebral fracture. Women with a history of heavy physical labor had a lower risk of vertebral fractures. Vertebral fractures were associated with decreased height loss and limited physical function but not chronic back pain. Women in Beijing, China have lower bone density and a slightly lower rate of vertebral fracture than white women in the United States. Low bone density and more sedentary occupations increase the risk of fracture in women living in urban China.

Aged↗
PubMed2000

Glycolaldehyde, a reactive intermediate for advanced glycation end products, plays an important role in the generation of an active ligand for the macrophage scavenger receptor.

Long-term incubation of proteins with glucose leads to the formation of advanced glycation end products (AGEs) that are recognized by AGE receptors. Glyoxal, glycolaldehyde (GA), and methylglyoxal are potential intermediates for the formation of AGE structures such as Nomega-(carboxymethyl)lysine (CML). We evaluated the contribution of these aldehydes to the formation of AGE structure(s), particularly the structure important for the receptor-mediated endocytic uptake of AGE proteins by macrophages. GA-modified bovine serum albumin (BSA), methylglyoxal-modified BSA (MG-BSA), and glyoxal-modified BSA (GO-BSA) were prepared, and their physicochemical, immunological, and biologic properties were compared with those of glucose-derived AGE-BSA. CML contents were high in GO-BSA and low in GA-modified BSA (GA-BSA) but did not exist in MG-BSA. The fluorescence patterns of GA-BSA and MG-BSA were similar to those of glucose-derived AGE-BSA but were weak in GO-BSA. Immunochemically, the antibody against non-CML structures of glucose-derived AGE-BSA reacted strongly with GA-BSA and weakly with GO-BSA but did not react with MG-BSA. The negative charge of these ligands increased to a similar extent. However, GA-BSA, but not MG-BSA or GO-BSA, underwent receptor-mediated endocytosis by the macrophage-derived cell line RAW 264.7, which was effectively inhibited by glucose-derived AGE-BSA, acetylated LDL, and oxidized LDL, which are well-known ligands for the macrophage type I and type II class A scavenger receptors (MSR-A). The endocytic uptake of GA-BSA by mouse peritoneal macrophages was also significant, but that by peritoneal macrophages from MSR-A-deficient mice was markedly reduced. Our results suggest that GA serves as an important intermediate for the generation of AGE structure(s) responsible for recognition by MSR-A.

Animals↗
PubMed2000

Clinical observation and experimental study on compound hypoglycemic decoction for hyperglycemia.

PURPOSE: To observe the clinical efficacy of Compound Hypoglycemic Decoction (CHD) and its effect on serum total cholesterol in model mice. METHOD: The paired t test was used to analyze the data recorded before and after administration of drugs for hyperglycemia induced by intraperitoneal injection of 75% egg yolk emulsion in experimental mice. CHD and Fenofibrate were administered as prevention measures. RESULTS: The total effective rate of serum total cholesterol (TC) decrease in 60 cases of hyperglycemia was 86.66% and that of serum total triglyceride (TG) decrease was 81.81%. The total effective rate of high-density lipoprotein-cholesterol (HDL-C) increase was 75%. The decrease in TC and TG, and the increase of HDL-C after treatment by in-group comparison were all significant (P < 0.05). 21.9% and 22.2% decrease in the total cholesterol was respectively found in the CHD and Fenofibrate groups (both P < 0.05), with no significant difference. CONCLUSION: The hypoglycemic action of Compound Hypoglycemic Decoction was remarkable in clinical practice, and it is very effective in preventing hyperglycemia in experimental mice.

Adult↗
PubMed2000

[Preliminary study on the effects of coagulation factor XII on fibrinolysis].

OBJECTIVE: To study the effects of FXII on fibrinolysis in patients with cerebral thrombosis. METHODS: Plasma level of FXII:C, FXII:Ag, FXIIa and beta FXIIa and fibrinolysis activities were examined by ELISA. Screening of FXII gene mutation by MOEA. RESULTS: FXII:C in 22 of 107 patients with cerebral thrombosis decreased, which was similar to the feature of FXII cross-reacting material positive (FXII CRM(+)). There were significant increase in plasma levels of PLG:A and alpha(2)AP:A and decrease in D-dimer, moreover, plasma levels of FXIIa and betaFXIIa were lower in patients than in controls. FXII gene mutation was not found in 22 of 107 patients. CONCLUSION: Decrease of FXII:C may play an important role in cerebral thrombosis by reducing activation of plasminogen. The gene mutation of FXII CRM(+)-like abnormal FXII was different from the known FXII gene mutation. Mutations in the regions of FXII Arg (334) and Arg (353) may be more important for the reducing of FXIIa, beta FXIIa levels and fibrinolysis activities. FXII assay should be included in thrombotic disorder screening.

Adult↗
PubMed2000

[FT-Raman spectroscopic investigation on stomach cancer].

FT-Raman spectroscopy was used to investigate 40 normal and malignant tissues from stomach. Statistic analysis shows that the bands related to OH, NH, C=O stretching and H-O-H bending are stronger in malignant tissues. This phenomenon suggests that the hydrogen bonding systems among water and protein vary in malignant tissues.

Humans↗
PubMed1999

[The experimental and clinical study of inhibitory effects of Re-Du-Qing on human cytomegalovirus (HCMV)].

OBJECTIVE: To study the theurapeutic effect of Chinese medicine Re-Du-Qing on HCMV. METHODS: The expression of the HCMV late-mRNA in infected cells was measured by quantitative RT-PCR and the development of cytopathic effect (CPE) caused by HCMV was observed before and after the treatment of Chinese medicine "Re-Du-Qing". On the basis of its anti-HCMV activity study in vitro, Re-Du-Qing was applied to the child-bearing aged women and to pregnant women who were HCMV-IgM positive which indicated the active HCMV infection, meanwhile the serum levels of tumor necrosis factor-alpha (TNF-alpha) and interleukin-2 (IL-2) were measured before and after the treatment by the ELISA method. RESULTS: The results showed that the Re-Du-Qing had strong inhibition effect both on HCMV-mRNA and CPE. The serum level of the TNF-alpha increased and IL-2 decreased significantly in HCMV-IgM positive cases when compared with normal women. After being treated with Re-Du-Qing, the serum TNF-alpha and IL-2 in patients returned to normal level, and 72.9% of the HCMV-IgM positive cases turned negative which was significantly higher than that (13.6%) in control group. CONCLUSION: It was suggested that serum TNF-alpha level is closely related to the activity of HCMV which has harmful effect on immune system. Re-Du-Qing can enhance immunity of the body and has an obvious inhibition on HCMV in Vitro and Vivo, and can thus serve as safe and effective medicine for treatment of active HCMV infection, especially for the pregnant women.

Adult↗
PubMed1999

Neuronal ERCC6 mRNA expression in rat brain induced by a transient focal cerebral ischemia.

AIM: To study whether the excision repair cross-complementing group 6 (ERCC6) is involved in the neuronal pathophysiological process following cerebral ischemia-reperfusion injury. METHODS: A transient middle cerebral artery occlusion (MCAO) was used to induce cerebral ischemia-reperfusion injury in rat brain. Northern blot was used to check a specific signal for oligonucleotide probe. The expression of ERCC6 mRNA in the rat brain was observed by in situ hybridization. The specific cellular distribution of ERCC6 mRNA in the neuron or glia of the rat brain was analyzed by double staining combined with confocal laser scanning microscopic analysis. RESULT: The expression of ERCC6 mRNA in the penumbra area increased following ischemia and reperfusion with a time-dependent manner. ERCC6 was expressed on d 2, reached peak values on d 3, and kept high level even on d 14 of reperfusion following ischemia. Number of ERCC6 mRNA expressive cell in the penumbra area on d 1, d 2, d 3, d 7, d 14 of reperfusion following ischemia were (0 +/- 0), (253 +/- 56), (816 +/- 355), (341 +/- 185), (128 +/- 95) x 10(6) cells/m2, respectively. Confocal microscopic analysis showed that ERCC6 mRNA coexpressed with phosphopyruvate hydratase in the neurons and with glial fibrillary acidic protein (GFAP) in a few proliferation astrocyte glia. CONCLUSION: The expression of transcription-repair coupling factor ERCC6 mRNA in the neuron and glia was induced by ischemia-reperfusion injury.

Animals↗
PubMed1999

Protective effect of melatonin on injuried cerebral neurons is associated with bcl-2 protein over-expression.

AIM: To study the protective effect of melatonin against neuronal injury and the possible roles of alteration in the expression of bcl-2 and bax following brain ischemia. METHODS: Brain ischemia was induced by left middle cerebral artery occlusion (MCAO) for 60 min in rats. Brain damage was evaluated by the infarct area and the neuronal cell counting. The expression of bcl-2 and bax was analyzed by immunohistochemical method. RESULTS: Melatonin decreased the infarct area and prevented the neuronal death after 24-h reperfusion following 1-h MCAO. Melatonin given before the ischemia enhanced the expression of bcl-2 in the penumbra area and had no significant effect on the expression of bax. CONCLUSION: Melatonin effectively attenuated ischemic brain injury and increased the expression of neuronal bcl-2 in the ischemic brain, indicating that the protective effect of melatonin was associated with up-regulation of bcl-2 in ischemia-induced neuronal death.

Animals↗
PubMed1999

[Diagnostic value of human cytomegalovirus late-mRNA detection for intrauterine active human cytomegalovirus infection].

OBJECTIVE: To study diagnostic value of late-mRNA detection for intrauterine active human cytomegalovirus (HCMV) infection. METHODS: The HCMV late-mRNA in peripheral blood of the pregnant women with HCMV-IgM positive and their fetal appendages (such as chorionic villi, amniotic fluid, umbilical blood and placenta) were detected by reverse transcription polymerase chain reaction(RT-PCR). RESULTS: The late-mRNA was detected in 23 out of 42 HCMV-IgM positive pregnant cases, with the 54.3% of corresponding rate between the results of HCMV-IgM and HCMV late-mRNA. 7 samples out of 13 fetal appendages from m-RNA positive mothers were late-mRNA positive, while in 12 mothers with late-mRNA negative group only one fetal sample was late-mRNA positive, Between two groups there was significant difference in mother-fetus transmission rate. CONCLUSIONS: The positive result of HCMV-IgM can not accurately reflect HCMV activity at the time being detected, which is closely related to the mother-fetus transmission rate. As a symbol of active HCMV infection, late-mRNA can not only reflect the mother-fetus transmission rate during active HCMV infection correctly, but also provide some information about activity of the HCMV in fetal tissue, It also has a great value in prediction for prognosis of infectious fetuses.

Cytomegalovirus↗