Biomedical subjects

C Yu

Publications and source records attributed to C Yu.

At least 145 records · Page 8Linked to original sources

PubMed2000

[IL-8 and IL-10 levels in endometriosis and regulated role of neiyifang on them].

OBJECTIVE: To investigate the IL-8 and IL-10 levels in endometriosis and the regulated role of Neiyifang (NYF) on them. METHODS: Animal models with endometriosis after Cummings method was established. IL-8 and IL-10 levels were determined in using double antibody sandwich ELISA. RESULTS: The IL-8 levels of serum and peritoneal fluid, and peritoneal macrophage amounts were markedly higher in the untreated group than those in the control group. The weights of endometriotic tissue and peritoneal macrophage amounts were markedly lower in the treated group of NYF, compared with the untreated group. The lipopolysaccharide stimulated IL-10 secretion in peritoneal macrophages from the untreated group were significantly lower compared with the control group and the treated group of NYF. CONCLUSION: The abnormality of IL-8 and IL-10 levels in endometriosis may be related to the pathogenesis of the disease. The therapeutical mechanism of NYF was mediated by promotion of IL-10 secretion, and further restrained the composition of inflammatory media and the growth of endometriotic tissue.

Animals↗

PubMed2000

[Microsurgical treatment of giant pituitary adenomas (reports of 56 cases)].

OBJECTIVE: To introduce a microsurgical operative experience with 56 cases of huge pituitary adenomas. METHODS: Fifty-six cases of huge pituitary adenomas were studied retrospectively. The tumors were classified into four types according to their configuration and extensive direction. The tumors were removed by various approaches, such as transsphenoidal, transsubfrontal, extended transsphenoidal, extended subfrontal extradual and subfrontal-transperitonal method. All patients were treated by 10 types of surgical approaches. The choice of surgical approach and operative care were introduced. RESULTS: Total removal was achieved in 29 cases, subtotal in 20, without any severe complications. CONCLUSION: Choosing appropriate approach can improve the rate of total tumor removal and can decrease the mortality and recurrent rate.

Adenoma↗

PubMed2000

[Diagnosis and management of recurrent pituitary adenoma].

OBJECTIVE: To discuss the clinical features, diagnosis and management of recurrent pituitary adenoma. METHODS: 38 cases of recurrent pituitary adenoma presented in our hospital during a period from January 1997 to May 1999 were analyzed retrospectively, and the relative references were reviewed. RESULTS: All cases were confirmed by surgery and pathology. The average recurrent interval of pituitary adenoma was 5.1 years, ranging from 3 months to 18 years. The main clinical manifestations were visual interference, pituitary dysfunction and headache. CT and MRI showed masses in the sellar region with contrast enhancement. Repeated surgeries were performed in 25 cases via transfrontal approach, 13 cases via transsphenoidal. Twenty-nine of 35 cases with visual interference were resolved, no improvement was achieved in 6 cases. Ten of 13 cases with PRL above normal level recovered within one week after surgery and no death was seen. 31 cases were followed up, and showed satisfying results. CONCLUSIONS: The diagnosis of recurrent pituitary adenoma mainly relies on the analysis of clinical manifestations, endocrinological and neuroradiological examinations. Operative management, medical treatment and radiation therapy are all treatment of choice for recurrent pituitary adenoma; while surgery is a main and effective method.

Adenoma↗

PubMed2000

[Comparison of atrio-ventricular and total cavo-pulmonary connections versus atrio-pulmonary anastomosis for repair of tricuspid atresia in dogs].

OBJECTIVE: To compare the hemodynamic effect and energy loss of atrio-ventricular and total cavo-pulmonary connections versus atrio-pulmonary anastomosis for modified Fontan in dogs. METHODS: Fifteen adult mongrel dogs were divided into three groups. Group I underwent right atrium to right ventricle (using 50% and 25% right ventricular chamber, respectively) connection with the flap of valved homo-pulmonary artery (modified Bjoerk procedure). Group II underwent total cavo-pulmonary connection. Group III received atrio-pulmonary anastomosis. Right atrium pressure, pulmonary artery pressure, and cardiac output were measured by Swan-Ganz catheter. The volumes of the right pulmonary artery, left pulmonary artery, superior vena cava and inferior vena cava were measured by electromagnetic flowmeter. The flow-rate of the right pulmonary artery, left pulmonary artery, superior vena cava and inferior vena cava were measured echocardiographically. The fluid energy loss was calculated. RESULTS: The postoperative right atrium pressure in group I was lower than in group III (P < 0.05). The postoperative stroke index in group I and group II was higher than in group III (P < 0.01). The fluid energy loss was decreased when 50% or 25% right ventricle chamber was used (P < 0.01) and the fluid energy less in group II was less than in group III. CONCLUSIONS: Our experience suggested that atrio-ventricular connection and total cavo-pulmonary connection would be better than atrio-pulmonary anastomosis for modified Fontan repair of tricuspid valve atresia.

Animals↗

PubMed2000

[Arthroscopically assisted anterior cruciate ligament reconstruction using patellar tendon autograft fixed with interference screw].

OBJECTIVES: To evaluate the optimal position of bony tunnel, the firmness of tendon graft fixation and the effectiveness of postoperative function recovery in an arthroscopic approach for the minimally invasive reconstruction of anterior cruciate ligament (ACL). METHODS: In a single arthroscopic approach, the ACL was reconstructed by the bone-tendon-bone compound patellar tendon autograft with the fixation of an interference screw. RESULTS: ACL reconstruction was performed in 49 patients, of whom 20 were followed up for over one year (average 1 year and 5 months). Among the 20 patients, 13 were rated as excellent, 5 good, and 2 fair. The excellent and good rate went up to 90%. Reconstructed ACLs were reevaluated arthroscopically in 9 patients, in whom, 6 had good remodeling of ACLs. CONCLUSIONS: Our results indicated that this method has the advantages of less injury, optimal positioning of bone tunnel, firm graft fixation, and early rehabilitation. Compound bone-tendon-bone autograft allows firm fixation and biologic healing with good shape and tension remodeling.

Adolescent↗

PubMed2000

[Early arthroscopic reconstruction in treatment of acute complete rupture of anterior cruciate ligament].

OBJECTIVE: To early reconstruct acute and complete rupture of anterior cruciate ligament (ACL) and treat combined injuries for the recovery of knee joint stability. METHODS: Ten cases of acute complete rupture of anterior cruciate ligament and medial collateral ligament were treated arthroscopically by anterior cruciate ligament reconstruction using patellar tendon autograft fixed with interference screw from February 1998 to March 1999. RESULTS: Follow-up ranged from 5 months to 1 year and 3 months (average 10 months). Clinical results showed that the stability of knee joint was satisfactory in the early stage. CONCLUSIONS: Acute the ACL rupture can be reconstructed arthroscopically in the early stage and the injuries were moderate, combined injuries could be treated at the same time, and the stability of knee joint could recover in the early stage after operation.

Adolescent↗

PubMed2000

[Three-dimensional reconstruction of internal auditory meatus and anatomical study of the inner structures].

OBJECTIVE: To provide anatomical basis for surgical operation in internal auditory meatus (IAM). METHODS: Structures of cerebellopontine angle (CPA) and IAM in 25 temporal bone specimens (50 sides) fixed in formalin were measured. Three-dimensional reconstruction (3DR) of IAM in 13 normal adults (26 sides) was conducted using spiral CT scanning. RESULTS: IAM took a conic shape with larger inside and smaller outside. The average width of IAM was (4.16 +/- 1.23) mm(2.87-6.83 mm) in horizontal dimension, the average height was (3.14 +/- 1.01) mm(2.23-4.45 mm) in vertical dimension, the average length was (8.67 +/- 2.31) mm (6.77-11.22 mm), the average volume was (98.23 +/- 16.56) mm3(67.44-133.21 mm3). There were 1-4 internal auditory arteries branched from the anterior-inferior cerebellar artery, which formed a vascular ansa near the opening of IAM. The average length of the facial nerve in IAM was (0.98 +/- 0.03) mm (0.89-1.07 mm), the average diameter of vestibulocochlear nerve was (1.67 +/- 0.05) mm (1.42-1.97 mm), the average diameter of the intermediate nerve (0.23 +/- 0.02) mm (0.19-0.26 mm). CONCLUSION: It is necessary to pay attention to types of vascular ansa and relative nerve location in IAM during operation.

Adult↗

PubMed2000

[Effect of alginate purity on microencapsulated hepatocyte overgrowth in peritoneal transplantation].

OBJECTION: To study the effect of alginate purity on microcapsule overgrowth in peritoneal transplantation. METHODS: Alginate was purified by filtration and chloroform/butanol extraction. Using purified and crude alginate to make two kinds of microencapsulated hepatocytes (MHs), we transplanted 5 ml of each kind of MHs into the peritoneal cavities of rats. After 2 weeks, 1, 2, and 6 months, MHs were washed out to study overgrowth of MH, histology, enzyme and albumin of hepatocytes. Human lymphocytes transformation was measured by 3H-TdR incorporation with two kinds of alginate solutions. RESULTS: The amount of retrieved MHs was larger in the purified than in the crude ( P < 0.01). In the purified groups, most hepatocytes had normal features of morphology, enzymatic histochemistry, and albumin immunohistochemistry staining after one month of transplantation, but were damaged in the crude groups only 2 weeks later. Microcapsules were smooth, regular and had no overgrowth during 6 months in the purified but overgrowth one month later after transplantation in the crude. The liquid scintillation counting (cpm) was lower in the purified than in the crude. CONCLUSION: The purified alginate could reduce the overgrowth of MH and improve the function of hepatocytes significantly.

Alginates↗

PubMed1999

Human acyl-CoA:cholesterol acyltransferase-1 is a homotetrameric enzyme in intact cells and in vitro.

Acyl-CoA:cholesterol acyltransferase (ACAT) is a key enzyme in cellular cholesterol homeostasis and in atherosclerosis. ACAT-1 may function as an allosteric enzyme. We took a multifaceted approach to investigate the subunit composition of ACAT-1. When ACAT-1 with two different tags were co-expressed in the same Chinese hamster ovary cells, antibody specific to one tag caused co-immunoprecipitation of both types of ACAT-1 proteins. Radioimmunoprecipitations of cells expressing the untagged ACAT-1 or the 6-histidine-tagged ACAT-1 yielded a single radiolabeled band of predicted size on SDS-polyacrylamide gel electrophoresis. These results show that ACAT-1 exists as homo-oligomers in intact Chinese hamster ovary cells. We solubilized HisACAT-1 with the detergent deoxycholate or CHAPS (3-[(3-cholamidopropyl)-dimethylammonio]-1-propanesulfonic acid), performed gel filtration chromatography and sucrose density gradient centrifugations in H(2)O and D(2)O, and determined the Stokes radii and sedimentation coefficients of the HisACAT1-detergent complexes. The estimated molecular mass of HisACAT-1 is 263 kDa, which is 4 times that of the HisACAT-1 monomer (69 kDa). Finally, cross-linking experiments in intact cells and in vitro show that the increase in cross-linker concentrations causes an increase in size of the HisACAT-1-positive signals, forming material(s) 4 times the size of the monomer, supporting the conclusion that ACAT-1 is a homotetrameric enzyme.

Animals↗

PubMed1999

Differential expression of carbohydrate blood-group antigens on rat taste-bud cells: relation to the functional marker alpha-gustducin.

An afferent nerve fiber supplying a taste bud receives input from several taste receptor cells, yet is predominantly responsive to one of the classic taste qualities (salt, acid, sweet, or bitter). This specificity requires recognition between taste receptor cells and nerve fibers that may be mediated by surface markers correlating with function. In an effort to identify potential markers, we used immunofluorescence and confocal microscopy to examine expression of the oligosaccharide blood-group antigens Lewis(b), A, and H type 2 in taste buds of the rat oral cavity. We compared the distributions of these antigens with that of alpha-gustducin, a G-protein subunit implicated in responses to sweet- and bitter-tasting substances. The A and Lewis(b) antigens were present only on spindle-shaped cells whose apical processes reached the taste pore. These antigens were not present on epithelial cells surrounding taste buds, and Lewis(b) was not found elsewhere in the digestive tract. Lewis(b) and A were not removed by lipid extraction, suggesting that they are present on glycoproteins rather than glycolipids. All Lewis(b)-positive cells expressed alpha-gustducin, but only a fraction of alpha-gustducin-positive cells expressed Lewis(b). The fraction of taste-bud cells expressing Lewis(b) decreased in the order: vallate papillae > foliate papillae > nasoincisor duct. The epiglottis had almost no taste-bud cells that expressed Lewis(b). The A antigen appeared on taste-bud cells that also expressed alpha-gustducin in the order: foliate and vallate papillae > nasoincisor duct and epiglottis > fungiform papillae. In addition, the A antigen was present on many cells that lacked alpha-gustducin in foliate and vallate papillae. In vallate papillae, cells expressed either A or Lewis(b), but not both. Lewis(b) appears to be restricted to differentiated light cells that also express alpha-gustducin and may be involved in intercellular interactions of these cells.

Animals↗

PubMed1999

Diminished aqueous microviscosity of tumors in murine models measured with in vivo radiofrequency electron paramagnetic resonance.

Using very low frequency in vivo electron paramagnetic resonance (EPR), we have compared, for the first time, the average microviscosity of the total aqueous compartment of murine fibrosarcomas and that of normal leg tissue in a living animal. EPR spectra from dissolved nitroxide spin probes report the solvent microviscosity. The tumor aqueous microviscosity, 1.8 +/- 0.1 centipoise, was significantly lower than that of the corresponding normal tissue, 2.9 +/- 0.3 centipoise, a difference of 38 +/- 7%. These results confirm the commonly observed increase in the water proton transverse relaxation times (T2) in magnetic resonance imaging of hyperproliferative states, for example, malignancy. The specificity of the localization of the EPR signal indicates a substantial portion of the T2 increase seen in magnetic resonance imaging derives from decreased bulk-water viscosity. The effect of this microviscosity differences may be the basis of several physiological differences between tumors and normal tissues which could confer a growth rate advantage to tumor tissue.

Animals↗

PubMed1999

Dosimetric comparison of three photon radiosurgery techniques for an elongated ellipsoid target.

PURPOSE: To examine the dosimetric differences among three radiosurgery techniques: gamma knife, linac multiple arcs, and conformally-shaped static fields. METHODS AND MATERIALS: A simulated target was taken to be a prolate ellipsoid, 25 mm in diameter, 35 mm in length, centrally located in a three-dimensional (3D) model of a patient head taken from MR images. Single isocenter linac treatment plans were developed, 9 portals for the static shaped field technique, and a 7-arc plan for the multiple arc method. A total of 13 isocenters with 3 different collimators were used in the gamma knife plan. RESULTS: At dose levels from 25% to 50% of the reference dose, multiple arc and shaped-field plans treated a greater volume than the gamma knife plan. The linac plans, however, delivered the dose more homogeneously across the target volume as compared to the gamma knife plan. For the dose levels between 50-100%, the shaped fields and gamma knife plan have a similar dose distribution, and treated slightly less volume than the multiple arc plan. CONCLUSION: For a target of limited volume and essentially any shape, one can obtain closely conformal dosimetry with the gamma knife. For a regular-shaped target, the single isocenter multiple arc technique gives a more homogenous dose distribution within the target. Static shaped fields offer an alternative radiosurgery technique, with dosimetry similar to the multiple arc method, applicable to targets of any shape.

Head↗

PubMed1999

Stable mixed hematopoietic chimerism in dogs given donor antigen, CTLA4Ig, and 100 cGy total body irradiation before and pharmacologic immunosuppression after marrow transplant.

Stable mixed chimerism can be established in dogs given a sublethal dose of 200 cGy total body irradiation (TBI) before and immunosuppression with mycophenolate mofetil (MMF) and cyclosporine (CSP) for 28 and 35 days, respectively, after dog leukocyte antigen-identical marrow transplantation. Most likely, the role of pretransplant TBI was to provide host immunosuppression, since stable mixed chimerism was also achieved in MMF/CSP-treated dogs when 450 cGy irradiation, targeted to cervical, thoracic, and upper abdominal lymph nodes, was substituted for TBI. When TBI was reduced from 200 to 100 cGy, all grafts were rejected within 3 to 12 weeks. Here, we asked whether stable engraftment after 100 cGy TBI could be accomplished by first reducing the intensity of host immune responsiveness with help of the fusion peptide CTLA4Ig, which blocks T-cell costimulation through the B7-CD28 signal pathway. Accordingly, recipient T cells were activated with intravenous (IV) injections of 10(6) donor peripheral blood mononuclear cells (PBMC)/kg per day on days -7 to -1 before 100 cGy TBI, with concurrent administration of CTLA4Ig 4 mg/kg/d IV. All 7 dogs so treated showed initial mixed chimerism. Two rejected their allografts after 8 and 20 weeks, respectively, and survived with autologous marrow recovery; 1 mixed chimera was unevaluable because of death at 3 weeks from intussusception; and 4 showed persisting mixed chimerism, including unirradiated marrow and lymph node spaces, for now more than 46 to 70 weeks after transplant. Data support the hypothesis that stable marrow allografts can be established by combining nonmyeloablative pretransplant host immunosuppression with posttransplant host and donor cell immunosuppression using MMF/CSP.

Abatacept↗

PubMed1999

Mutations of human topoisomerase II alpha affecting multidrug resistance and sensitivity.

Two mutations, R450Q and P803S, in the coding region of the human topoisomerase II alpha gene have been identified in the atypical multidrug resistant (at-MDR) cell line, CEM/VM-1, which exhibits resistance to many structurally diverse topoisomerase II-targeting antitumor drugs such as VM-26, doxorubicin, m-AMSA, and mitoxantrone. The R450Q mutation mapped in the ATP utilization domain, while the P803S mutation mapped in the vicinity of the active site tyrosine of human topoisomerase II alpha. However, the roles of these two mutations in conferring multidrug resistance are unclear. To study the roles of these two mutations in conferring multidrug resistance, we have characterized the recombinant human DNA topoisomerase II alpha containing either single or double mutations. We show that both R450Q and P803S mutations confer resistance in the absence of ATP. However, in the presence of ATP, the R450Q, but not the P803S, mutation can confer multidrug resistance. The R450Q enzyme was shown to exhibit impaired ATP utilization both for enzyme catalysis and for its ability to form the circular protein clamp. Interestingly, an unrelated mutation, G437E, which is also located in the same domain as the R450Q mutation, exhibited multidrug hypersensitivity in the absence of ATP. However, in the presence of ATP, the G437E enzyme is only minimally hypersensitive to various topoisomerase II drugs. In contrast to the R450Q enzyme, the G437E enzyme exhibited enhanced ATP utilization for enzyme catalysis. In the aggregate, these results support the notion that the multidrug resistance and sensitivity of these mutant enzymes are due to a specific defect in ATP utilization during enzyme catalysis.

Adenosine Triphosphate↗

PubMed1999

Investigation of the structural stability of cardiotoxin analogue III from the Taiwan cobra by hydrogen-deuterium exchange kinetics.

The conformational stability of a small ( approximately 7 kDa), all beta-sheet protein, cardiotoxin analogue III (CTX III), from the venom of the Taiwan cobra has been investigated by hydrogen-deuterium (H/D) exchange using two-dimensional NMR spectroscopy. The H/D exchange kinetics of backbone amide protons in CTX III has been monitored at pD 3.6 and 6.6 (at 25 degrees C), for over 5000 h. Examination of H/D exchange kinetics in the protein showed that a number of slowly exchanging residues are in the hydrophobic core of the protein. The average protection factor of the amide protons of residues belonging to the triple-stranded beta-sheet domain is about 20 times greater than that of those in the double-stranded beta-sheet segment. The residues in the C-terminal tail of the molecule, though structureless, have been found to exhibit significant protection against H/D exchange. Comparison of the quenched-flow H/D exchange data on CTX III with those obtained in the present study reveals that the most slowly exchanging portion constitutes the folding core of the protein.

Amides↗

PubMed1999

Stable mixed hematopoietic chimerism in dog leukocyte antigen-identical littermate dogs given lymph node irradiation before and pharmacologic immunosuppression after marrow transplantation.

Stable mixed donor/host hematopoietic chimerism can be accomplished in dog leukocyte antigen (DLA)-identical littermate dogs given sublethal (200 cGy) total-body irradiation (TBI) before and immunosuppression with mycophenolate mofetil (MMF) and cyclosporine (CSP) after transplant (Blood 89:3048, 1997). Studies were based on the hypothesis that drugs that prevent graft-versus-host disease (GVHD) after transplant also suppress host-versus-graft (HVG) reactions and thereby enhance engraftment. Here, we asked whether pretransplant TBI provided marrow space for the graft to home or caused host immunosuppression. To address the questions, recipients were given pretransplant irradiation to cervical, thoracic, and abdominal lymph nodes (except pelvis), DLA-identical littermate marrow grafts, and MMF/CSP posttransplant. Six dogs that received 450 cGy irradiation showed initial engraftment. Two rejected their grafts after 8 and 18 weeks, 1 died with GVHD and engraftment, and 3 are alive as mixed chimeras after 57 to 97 weeks. Four dogs given 200 cGy irradiation also showed initial engraftment, but rejected their grafts after 10 to 18 weeks. Mixed chimerism was present in nonirradiated marrow and lymph node spaces and involved granulocytes, T cells, and monocytes. While other explanations are possible, results seem consistent with the hypothesis that pretransplant radiation provides host immunosuppression, and grafts can create their own marrow space. These data set the stage for the development of novel transplant regimens that substitute immunosuppressive for cytotoxic agents.

Animals↗

PubMed1999

Cloning and mapping of the XRN2 gene to human chromosome 20p11.1-p11.2.

The Dhm1 gene is the mouse homologue of the dhp1(+) gene of Schizosaccharomyces pombe, which is involved in homologous recombination and RNA metabolism, such as RNA synthesis and RNA trafficking, in S. pombe. Complementation analysis showed the Dhm1 gene on a multicopy plasmid can rescue the temperature-sensitivity mutation of dhp1(ts) and the lethality of the dhp1 null mutation. This finding suggests that Dhm1 has a function in mouse similar to that of dhp1(+). The human homologue of this gene, XRN2, has been identified. A 3.6-kb transcript of XRN2 was detected in 16 tissues examined and was more abundant in testis. By radiation hybrid panel mapping, the XRN2 gene was localized to chromosome 20p11.1-p11.2 between markers D20S180 and D20S871.

Adult↗

PubMed1999

GATA-1 and erythropoietin cooperate to promote erythroid cell survival by regulating bcl-xL expression.

The transcription factor GATA-1 is essential for normal erythropoiesis. By examining in vitro-differentiated embryonic stem cells, we showed previously that in the absence of GATA-1, committed erythroid precursors fail to complete maturation and instead undergo apoptosis. The mechanisms by which GATA-1 controls cell survival are unknown. Here we report that in erythroid cells, GATA-1 strongly induces the expression of the anti-apoptotic protein bcl-xL, but not the related proteins bcl-2 and mcl-1. Consistent with a role for bcl-xL in mediating GATA-1-induced erythroid cell survival, in vitro-differentiated bcl-xL-/- embryonic stem cells fail to generate viable mature definitive erythroid cells, a phenotype resembling that of GATA-1 gene disruption. In addition, we show that erythropoietin, which is also required for erythroid cell survival, cooperates with GATA-1 to stimulate bcl-xL gene expression and to maintain erythroid cell viability during terminal maturation. Together, our data show that bcl-xL is essential for normal erythroid development and suggest a regulatory hierarchy in which bcl-xL is a critical downstream effector of GATA-1 and erythropoietin-mediated signals.

Animals↗