Biomedical subjects

J Yuan

Publications and source records attributed to J Yuan.

At least 127 records · Page 7Linked to original sources

PubMed2000

Three-dimensional analysis of the proximal part of the humerus: relevance to arthroplasty.

BACKGROUND: Recreation of normal anatomical relationships may be important to optimize the outcome of proximal humeral arthroplasty. With use of computerized tomographic data and three-dimensional computer modeling, we concurrently studied both extramedullary and intramedullary humeral morphology, including canal shape, and related these findings to the design of proximal humeral prostheses. METHODS: Sixty cadaveric humeri (thirty pairs: fifteen from male donors and fifteen from female donors) were studied. Three-dimensional computer models were built from canal and periosteal contours extracted from computerized tomographic data and multiple measured anatomical parameters, including humeral canal axis, humeral head center, and hinge point offset; greater tuberosity and bicipital groove offset; humeral head center, radius, thickness, retroversion, and inclination; and size and torsion of sections of the canal. RESULTS: On the average, the humeral head center was offset both medially (seven millimeters) and posteriorly (two millimeters) from the humeral axis. The humeral head hinge point did not line up with the axis but instead was laterally offset by an average of seven millimeters. The average humeral head thickness was nineteen millimeters. The humeral head thickness and length were proportionately linked. There was marked variability in all of these parameters. Humeral head inclination averaged 41 degrees but was less variable than previously described, with 95 percent of our sample within the range of 35 to 46 degrees. The proximal section of the humeral canal was retroverted, and the retroversion was found to be similar to that of the humeral head on statistical analysis. Version of the middle and distal sections of the canal, however, was dissimilar to that of the proximal section of the canal. Proximal humeral retroversion was found to be extremely variable and averaged 19 degrees. The accuracy, reliability, and repeatability of the computer-based-model measurements were found to be excellent. CONCLUSIONS: Measurements of external proximal humeral morphology made with three-dimensional computer models of cadaveric specimens derived from the Midwestern United States agreed, in general, with those described for different populations evaluated with different measuring techniques. Proximal humeral morphology was extremely variable as highlighted by the large ranges of measurements seen for all variables. Examination of the intramedullary morphology showed that there is an internal version, with measurements dependent on the canal distance distal to the anatomical neck. CLINICAL RELEVANCE: Because of the marked variabilities seen in proximal humeral morphology, newer prosthetic designs are now allowing surgeons to control multiple prosthetic variables. An understanding of the normal values for proximal humeral morphology can serve as an important guideline for component selection, especially when the normal anatomy is distorted. Additionally, variations in intramedullary version may have important consequences for future designs of press-fit proximal humeral replacement.

Arthroplasty, Replacement↗

PubMed2000

Toward development of an in vitro model of methamphetamine-induced dopamine nerve terminal toxicity.

To develop an in vitro model of methamphetamine (METH)-induced dopamine (DA) neurotoxicity, striatal synaptosomes were incubated at 37 degrees C with METH for different periods of time (10-80 min), washed once, then tested for DA transporter function at 37 degrees C. METH produced time- and dose-dependent reductions in the V(max) of DA uptake, without producing any change in K(m). Incubation of synaptosomes with the DA neurotoxins 1-methyl-4-phenyl-pyridinium ion, 6-hydroxydopamine, and amphetamine under similar conditions produced comparable effects. In contrast, incubation with fenfluramine, a serotonin neurotoxin, did not. METH-induced decreases in DA uptake were selective, insofar as striatal glutamate uptake was unaffected. Various DA transporter blockers (cocaine, methylphenidate, and bupropion) afforded complete protection against METH-induced decreases in DA uptake, without producing any effect themselves. METH's effects were also temperature dependent, with greater decreases in DA uptake occurring at higher temperatures. Tests for residual drug revealed small amounts (0.1-0.2 microM) of remaining METH, but kinetic studies indicated that decreases in DA uptake were not likely to be due to METH acting as a competitive inhibitor of DA uptake. Decreases in the V(max) of DA uptake were not accompanied by decreases in B(max) of [(3)H]WIN 35,428 binding, possibly because there is no mechanism for removing damaged DA nerve endings from the in vitro preparation Collectively, these results give good support to the development of a valid in vitro model that may prove helpful for elucidating the mechanisms underlying METH-induced DA neurotoxicity.

Animals↗

PubMed2000

Cytochalasin E, an epoxide containing Aspergillus-derived fungal metabolite, inhibits angiogenesis and tumor growth.

Several previously identified inhibitors of angiogenesis have been epoxide-containing fungus-derived metabolites. We therefore hypothesized that novel epoxide-containing low molecular weight compounds structurally resembling known antiangiogenic agents may also exhibit antiangiogenic activity. Cytochalasin E was found to be a potent and selective inhibitor of bovine capillary endothelial (BCE) cell proliferation. Cytochalasin E differed from other cytochalasins by the presence of an epoxide. The epoxide was required for activity, because acid-catalyzed hydrolysis of the epoxide abrogated the specificity and potency of cytochalasin E. Phalloidin staining indicated that disruption of actin stress fibers by cytochalasin E occurred only at relatively high concentrations. Lower concentrations of cytochalasin E preferentially inhibited BCE cell proliferation without disrupting actin stress fibers. In vivo, cytochalasin E inhibited angiogenesis induced by basic fibroblast growth factor by 40% to 50% in the mouse cornea assay and inhibited the growth of Lewis lung tumors by approximately 72%. Cytochalasin E is a potent antiangiogenic agent that may hold promise for the treatment of cancer and other types of pathologic angiogenesis.

3T3 Cells↗

PubMed2000

Effects of dihydroartemisinin on fine structure of erythrocytic stages of Plasmodium berghei ANKA strain.

AIM: The fine structural changes of Plasmodium berghei ANKA strain after treatment with the dihydroartemisinin (DATM) were observed. METHODS: DATM 180 mg.kg-1.d-1 was given ig to outbreed NIH mice infected with P. berghei ANKA strain. Blood samples were collected, embedded and examined by electron microscopy. RESULTS: In P. berghei ANKA strain, 1 h after drug administration, the parasites food vacuole membranes were destroyed, and the pigment grains showed some changes. The nucleus membrane, cytomembrane, and food vacuole membranes were stratified 2 h after administration. At the same time, swelling and separation of the outer and inner membrane or shrinking of the mitochondria were seen. Stripped nuclear and cytoplasm membrane were developed and vacuolizations were seen 4 h later. Eight hours after administration, a large number of parasite structures were destroyed except for a few parasite autophagic vacuoles. CONCLUSION: DATM was a fast-acting and effective antimalarial drug. Its primary target is the membrane system. No obvious resistant characteristics were found upto 24 generations after resistant induction test for 4 months.

Animals↗

PubMed2000

HLA alleles in patients with Guillain-Barre syndrome.

OBJECTIVE: To determine whether genetic factors may work in concert with autoimmune factors in the pathogenesis of Guillain-Barre syndrome (GBS). METHODS: We determined the differences in the distribution of HLA alleles between GBS patients and normal controls. HLA-DQA, -DQB and -DRB alleles were typed by the sequence specific primer polymerase chain reaction (PCR-SSP) methods in 47 GBS, 7 patients with Campylobacter jejuni (CJ) enteritis and 50 normal controls. RESULTS: There were no differences in the frequency of HLA-DQA, -DQB and -DRB among GBS group, CJ group, normal controls and GBS subgroups with respect to recent CJ infection, GM1 IgG and GM1 IgM antibodies (P > 0.05). There was an increasing tendency of DQA1 * 0301 (P = 0.056, RR = 2.991) in the subgroup with GM1 IgG antibodies and DQA1 * 0302 (P = 0.087, RR = 3.587) in the subgroup with recent CJ infection. No difference was found among GBS, CJ enteritis patients and normal controls. CONCLUSIONS: The increasing tendency of the two alleles suggests that there may be some relation between genetic factors and immunological factors, but a definite conclusion waits for more cases.

Alleles↗

PubMed2000

[Fiberoptic ductoscopy for patients with intraductal papillary lesions].

OBJECTIVE: To investigate the clinical significance of fiberoptic ductoscopy in patients with intraductal papillary lesions. METHODS: Fiberoptic ductoscopy was applied to patients with nipple discharge. The characteristics of those with intraductal papillary lesion were analysed. RESULTS: 92 patients were found to have intraductal papillary lesions. 68 patients were revealed to have single papillomas and 21 multiple papilloma. Three patients were diagnosed with papillomatosis. A total of 114 lesions were observed. 29.8% of these lesions were located in the segmental duct. 43.9% lesions were located in the first branch of the segmental duct and 17.5% in the second branch. Only 7.9% and 0.9% lesions were located in the third and the fourth branch. The average distance from lacteous pore to papillary lesion was 2.7 cm. Fiberoptic ductoscopy did not find lesions in 5 patients. CONCLUSIONS: Fiberoptic ductoscopy can be used to diagnose and locate intraductal papillary lesions. It is an effective diagnostic method for nipple discharge.

Adult↗

PubMed2000

[An experimental study on F-heparin surface modified IOLs implanted into the Rhesus monkeys' eyes].

OBJECTIVE: To evaluate the biocompatibility of F-heparin surface modified IOLs. METHODS: 13 monkeys were divided into 3 groups, and implanted with different surface modified and non-modified IOLs into their eyes. All of the eyes were examined by slitlamp microscope and Schiötz tonometer at postoperative 15, 30, 60, 90 and 180 days. Postoperatively, at different periods the aqueous was aspirated from the anterior chamber to calculate cells. RESULTS: F-heparin surface modified IOLs induced milder inflammatory reaction and less dense posterior capsula opacification (PCO) than non-modified IOLs. CONCLUSION: F-heparin surface modified IOL has a better biocompatibility.

Animals↗

PubMed2000

[The change of intestinal microcirculation blood flow and its relationship with bacterial translocation in burned rats receiving delayed fluid resuscitation].

OBJECTIVE: To investigate the change of intestinal microcirculation blood flow and its relationship with bacterial translocation in burned rats receiving delayed fluid resuscitation. METHODS: Twenty-four Wistar rats inflicted by 30% TBSA III degree followed by delayed fluid resuscitation were taken as the model. The rats were randomly divided into four groups, i.e. burn shock without resuscitation (BSNR), delayed resuscitation (fluid given from 8 hours postburn, DR), immediate resuscitation (IR), and sham operation (SO). The incidence of bacterial translocation, intestinal microcirculation blood flow volume of intestinal wall at terminal ileum as well as the change of systemic mean arterial pressure were monitored. RESULTS: The incidence of bacterial translocation in DR group (54.2%) was significantly higher than that in IR group (P < 0.01), but no remarkable difference with that in BS group (P < 0.05). In addition, microcirculation blood flow of intestinal wall recovered to some degree at 4 hours after delayed fluid resuscitation but far below that in IR group at the same time point. Nevertheless, the systemic mean arterial blood pressure had restored to the normal range at that time. CONCLUSION: The incidence of intestinal bacterial translocation sustained at high level after burn shock with delayed fluid resuscitation, which might be the result of delayed improvement of microcirculation blood flow of the intestinal wall.

Animals↗

PubMed2000

[Study on the mechanism of pulmonary edema after seawater drowning in rabbit].

To study the mechanism of pulmonary edema after seawater drowning (PE-SWD), the indexes of blood-gas and acid-base in rabbits artery blood were measured by the blood-gas analyser. The activity of Na(+)-K(+)-ATPase, cytochrome oxidase(CYTO) and alkaline phospharase(ALP) in the lungs were measured and analysed by computer image system. C-fos mRNA and Fos protein in the lungs were respectively determined by situ hybrioization and immunohisto chemical techniques. The distribution of phospholipid and Ca2+ of rabbits lungs was quantitatively analysed by ultrastructural location method. The results showed that, five parameters of PaO2, oxygen saturation(SaO2), pH, actual bicarbonite(AB) and base excess(BE) and the activity of Na(+)-K(+)-ATPase and CYTO decreased remarkably in PE-SWD. Both c-fos mRNA and Fos protein expression in pulmonary epithelial cells in PE-SWD were significantly elevated compared with the normal controls(P < 0.01). The phospholipids products in the pulmonary alveolar type II epithelial cells were decreased, however, the Ca2+ precipitate pellets inside the lung capillary endothelial cells and the pulmonary alveolar type I and II epithelial cells increased obviously. The arthors suggest that the injuny action of the seawater, hypoxia and metabolic acidosis may be the mian three mechanisms of the pulmonary edema induced seawater drowning. The lowering activity of Na(+)-K(+)-ATPase and CYTO in the lungs and calcium overload in the cells are not only evil consequence resulted from above three factors, but also the importent causes leading to the worse of PE-SWD. The transmiting line of Ca(2+)-fos may be also a key link to bring about the worse of PE-SWD.

Acidosis↗

PubMed2000

[Thyroidectomy and injury of recurrent laryngeal nerve].

OBJECTIVE: To study factors related to recurrent laryngeal nerve (RLN) paralysis, a major complication of thyroidectomy. METHOD: Retrospective study of outcome of patient's medical records in Xijing Hospital and Tumor Hospital of Liaoning Province. Records of 1,563 patients who underwent thyroidectomy by departments of general surgery, ENT and head & neck surgery at these two hospitals were reviewed for RLN paralysis. MAIN OUTCOME MEASURES: RLN injury was analyzed in relation to types of surgery, RLN identification, and histopathology. RESULT: The incidence of RLN paralysis was 7.8%, and significantly related to the histopathologic findings of malignancy (P < 0.01). The positive identification and prevention of RLN would not be in either permanent RLN paralysis or temporary RLN paralysis, and the types of surgery were not found to be significant factors in both paralysis. CONCLUSION: RLNs should be identified to avoid iatrogenic injury and subsequent paralysis, and meticulous surgical technique should be applied in patients whose results of biopsy suggested malignancy.

Adolescent↗

PubMed2000

[Differentiation of human glioma cells BT-325 induced by sodium butyrate].

OBJECTIVE: To study the differentiation of human glioma cells BT-325 induced by sodium butyrate in vitro. METHODS: BT-325 cells were treated with 1 mmol/L sodium butyrate. Flow cytometry was used to analyze the cell cycle. Cell differentiation was identified by flow cytometry and Western blot analysis. RESULTS: After 6-8 days of sodium butyrate treatment, the differentiation characters could be observed distinctively, such as the reduced cell density, the increased cell size and the marked increase in cell process formation and cell-to-cell connection. At the same time, Western blot showed that the amount of glial fibrillary acidic protein was elevated after the sodium butyrate treatment. CONCLUSION: Human glioma cells BT-325 could be induced to differentiation by sodium butyrate.

Brain Neoplasms↗

PubMed2000

[The identification and cloning of human ubiquitin binding enzyme cDNA].

OBJECTIVE: To identify and clone the gene encoding human ubiquitin binding enzyme and study its expression spectrum. METHODS: According to the sequence of human EST, which is highly homologous to the mouse ubiquitin conjugating enzyme (E2), primers used for library screening were synthesized to screen the human fetal brain cDNA library. The gene was analyzed by making use of bioinformatics and its expression spectrum was studied by using multiple-tissue Northern blot. RESULTS: Two cDNA clones encoding human ubiquitin conjugating enzyme were isolated and identified. Both containing the ubiquitin conjugating domain, they were 88% identical in amino acid sequences and found to be isoforms of each other with only an exon excised from the short sequence. They belonged to a highly conserved, and widely expressed E2 enzyme family. Northern blot showed that they were expressed exclusively in heart, placenta, and pancreas while no transcripts could be detected in brain, lung, liver, skeletal muscle, or kidney. CONCLUSIONS: The gene encoding human ubiquitin binding enzyme is expressed under both temporal and spatial control. As a key enzyme in the degradation of proteins, ubiquitin conjugating enzymes play a central role in the expression regulation on the level of post-translation.

Amino Acid Sequence↗

PubMed2000

Isolation and identification of cDNA fragments and full-length cDNA differentially expressed in human glioblastoma cell line BT-325 versus all-trans retinoic acid induction .

OBJECTIVE: To investigate the differentiation process of the human glioblastoma cells. METHODS: Differential display reverse transcribed-PCR (DDRT-PCR) was used to isolate the genes differentially expressed in control and all-trans retinoic acid treated human glioblastoma cell line BT-325. Routine method of cDNA library screening was performed to clone full-length cDNA. RESULTS: Thirty-six RT-PCR reactions were performed and 64 differentially expressed fragments were recovered, amplified and cloned. Of them, 46 ESTs were sequenced and delivered into the GenBank. The homology comparison using BLAST algorithm revealed that 22ESTs are highly homologous with the known genes and many of them play important roles in the cell differentiation progress. A dot-blot hybridization was conducted to certify the differentiation expression. The result showed that 27 EST clones are expressed at different level in control and all-trans retinoic acid treated BT-325 cells. A full-length cDNA was cloned using the EST-HGBB098. CONCLUSION: DDRT-PCR was a simple and effective method to serially analyze the differentially expressed genes.

Amino Acid Sequence↗

PubMed1999

Expression cloning of protein targets for 3-phosphorylated phosphoinositides.

The phosphatidylinositol 3-kinase (PI 3'-K) family of lipid kinases play a critical role in cell proliferation, survival, vesicle trafficking, motility, cytoskeletal rearrangements, and oncogenesis. To identify downstream effectors of PI 3'-K, we developed a novel screen to isolate proteins that bind to the major products of PI 3'-K: phosphatidylinositol-3,4-bisphosphate (PtdIns-3,4-P(2)) and PtdIns-3,4,5-trisphosphate (PtdIns-3,4,5-P(3)). This screen uses synthetic biotinylated analogs of these lipids in conjunction with libraries of radiolabeled proteins that are produced by coupled in vitro transcription/translation reactions. The feasibility of the screen was initially demonstrated using avidin-coated beads prebound to biotinylated PtdIns-3,4-P(2) and PtdIns-3,4,5-P(3) to specifically isolate the pleckstrin homology domain of the serine/threonine kinase Akt. We then demonstrated the utility of this technique in isolating novel 3'-phosphorylated phosphatidylinositol (3'-PPI)-binding proteins through the preliminary screening of in vitro transcribed/translated cDNAs from a small pool expression library derived from mouse spleen. Three proteins were isolated that bound specifically to 3'PPIs. Two of these proteins have been previously characterized as PIP3BP/p42(IP4) and the PtdIns-3,4,5-P(3)-dependent serine/threonine kinase phosphoinositide-dependent kinase 1. The third protein is a novel protein that contains only a Src homology 2 domain and a pleckstrin homology domain; this protein has a higher specificity for both PtdIns-3,4,5-P(3) and PtdIns-3,4-P(2) than for PtdIns-4, 5-bisphosphate. Transcripts of this novel gene are present in every tissue analyzed but are most prominently expressed in spleen. We have renamed this new protein PHISH for 3'-phosphoinositide-interacting Src homology-containing protein. This report demonstrates the utility of this technique for isolating and characterizing 3'-PPI-binding proteins and has broad applicability for the isolation of binding domains for other lipid products.

Adaptor Proteins, Signal Transducing↗

PubMed1999

Simultaneous determination of alpha-fetoprotein and carcinoembryonic antigen in human serum by time-resolved fluoroimmunoassay.

A novel simultaneous measurement method for alpha-fetoprotein (AFP) and carcinoembryonic antigen (CEA) in human sera by time-resolved fluoroimmunoassay (TR-FIA) is described. The proposed approach combines the use of europium-labeled anti-AFP antibody for AFP TR-FIA and biotinylated anti-CEA antibody complexed to samarium-labeled streptavidin for CEA TR-FIA. A 96-well microtiter plate coated with a mixture of anti-AFP and anti-CEA monoclonal antibodies was used for the assay. After it was reacted with a solution containing AFP and CEA, a mixture of anti-AFP antibody labeled with BHHCT-Eu(3+) and biotinylated anti-CEA antibody was added. The AFP concentration was determined by measuring the solid-phase fluorescence of the europium-labeled anti-AFP antibody at 615 nm. Then a BHHCT-Sm(3+)-labeled streptavidin-bovine serum albumin conjugate (SA-BSA) was added to react with the biotinylated anti-CEA antibody. After the reaction, the unreacted SA-BSA was washed out, and a 0.1 M NaOH solution containing 1.0 x 10(-5) M TOPO and 0.05% SDS was added to dissociate the samarium-labeled SA-BSA in the immune complex on the surface of the well into the solution. The CEA concentration was determined by measuring the solution fluorescence of 643 nm from the samarium-labeled SA-BSA. The present method gives detection limits of 0.07 ng/ml for AFP and 0.3 ng/ml for CEA. The coefficient variations of the method are less than 7%, and the recoveries are in the range of 90-110% for serum samples. The AFP and CEA concentrations in 27 human serum samples were determined by the present method as well as by single assay for comparison. A good correlation was obtained with the correlation coefficients of 0.990 for AFP and 0.973 for CEA.

Animals↗

PubMed1999

A cyclic antimicrobial peptide produced in primate leukocytes by the ligation of two truncated alpha-defensins.

Analysis of rhesus macaque leukocytes disclosed the presence of an 18-residue macrocyclic, tridisulfide antibiotic peptide in granules of neutrophils and monocytes. The peptide, termed rhesus theta defensin-1 (RTD-1), is microbicidal for bacteria and fungi at low micromolar concentrations. Antibacterial activity of the cyclic peptide was threefold greater than that of an open-chain analog, and the cyclic conformation was required for antimicrobial activity in the presence of 150 millimolar sodium chloride. Biosynthesis of RTD-1 involves the head-to-tail ligation of two alpha-defensin-related nonapeptides, requiring the formation of two new peptide bonds. Thus, host defense cells possess mechanisms for synthesis and granular packaging of macrocyclic antibiotic peptides that are components of the phagocyte antimicrobial armamentarium.

Amino Acid Sequence↗

PubMed1999

Solution structure of Apaf-1 CARD and its interaction with caspase-9 CARD: a structural basis for specific adaptor/caspase interaction.

Direct recruitment and activation of caspase-9 by Apaf-1 through the homophilic CARD/CARD (Caspase Recruitment Domain) interaction is critical for the activation of caspases downstream of mitochondrial damage in apoptosis. Here we report the solution structure of the Apaf-1 CARD domain and its surface of interaction with caspase-9 CARD. Apaf-1 CARD consists of six tightly packed amphipathic alpha-helices and is topologically similar to the RAIDD CARD, with the exception of a kink observed in the middle of the N-terminal helix. By using chemical shift perturbation data, the homophilic interaction was mapped to the acidic surface of Apaf-1 CARD centered around helices 2 and 3. Interestingly, a significant portion of the chemically perturbed residues are hydrophobic, indicating that in addition to the electrostatic interactions predicted previously, hydrophobic interaction is also an important driving force underlying the CARD/CARD interaction. On the basis of the identified functional residues of Apaf-1 CARD and the surface charge complementarity, we propose a model of CARD/CARD interaction between Apaf-1 and caspase-9.

Amino Acid Sequence↗

PubMed1999

Cloning and expression of bovine neutrophil beta-defensins. Biosynthetic profile during neutrophilic maturation and localization of mature peptide to novel cytoplasmic dense granules.

beta-Defensins are microbicidal peptides implicated in host defense functions of phagocytic leukocytes and certain surface epithelial cells. Here we investigated the genetic structures and cellular expression of BNBD-4, -12, and -13, three prototypic bovine neutrophil beta-defensins. Characterization of the corresponding cDNAs indicated that BNBD-4 (41 residues) derives from a 63-amino acid prepropeptide and that BNBD-12 (38 residues) and BNBD-13 (42 residues) derive from a common 60-amino acid precursor (BNBD-12/13). The peptides were found to be encoded by two-exon genes that are closely related to bovine epithelial beta-defensin genes. BNBD-4 and BNBD-12/13 mRNAs were most abundant in bone marrow, but were expressed differentially in certain non-myeloid tissues. In situ hybridization and immunohistochemical studies demonstrated that BNBD-4 synthesis is completed early in myelopoiesis. BNBD-12 was localized exclusively to the novel dense granules, organelles that also contain precursors of cathelicidins, antimicrobial peptides that undergo proteolytic processing during phagocytosis. In contrast to cathelicidins, Western blot analyses revealed that mature beta-defensins are the predominant organellar form in myeloid cells. Stimulation of neutrophils with phorbol myristate acetate induced secretion of BNBD-12, indicating that it is co-secreted with pro-cathelicidins. The exocytosis of BNBD-12 by activated neutrophils reveals different mobilization pathways for myeloid alpha- and beta-defensins.

Amino Acid Sequence↗