Biomedical subjects

C Sun

Publications and source records attributed to C Sun.

At least 109 records · Page 6Linked to original sources

PubMed1999

Purification and properties of genetic expressing product of thermostable protease from Bacillus stearothermophilus HY-69.

The thermostable metal protease gene from Bacillus stearothermophilus HY-69 had been cloned and expressed in Bacillus subtilis MI113. The genetic expressing product of the enzyme was purified by CM-cellulose chromatography. The product shows homogeneity on PAGE. Its molecular weight is 27,000 +/- 1000 by SDS-PAGE and Sephadex G100 filtration, respectively. The alpha-helix content of the protease is estimated to be about 66%, the beta-turn about 28%, the random coil about 6%, but not beta-sheet, calculated from the circular dichroism data. The optimal temperature of the enzyme was 70 degrees C. When the enzyme was denatured in 3 mol/L of Gdn--HCl in phosphate buffer pH6.0 for 20 min, it remained about 40% of original activity. It shows that it is rather resistant to heat and Gdn-HCl denaturation. Its conformational variety coursed by Gdn-HCl was investigated by the far UV circular dichroism and fluorescence spectra. The results show that the enzyme has more compact conformation and internal hydrophobility.

Amino Acids↗

PubMed1999

Detection of neuroendocrine feature about salivary adenoid cystic carcinoma.

OBJECTIVE: To study the possibility of neuroendocrine feature of salivary adenoid cystic carcinoma (SACC). METHODS: Immunohistochemical staining was operated in SACC with S-100 protein, neurospecific enolase (NSE), chromogranin A, and synaptophysin, which are specific and correlative with neuroendocrine cells and neoplasias. RESULTS: The positive expression of S-100, NSE, chromogranin, and synaptophysin were 42, 32, 8, and 7, respectively, in 50 cases of SACC. CONCLUSION: Neuroendocrine feature in some SACC cells is possibly indicated.

Adolescent↗

PubMed1999

[Gonadotropin releasing hormone agonists in the treatment of adenomyosis with infertility].

OBJECTIVE: To Study the role of gonadotropin releasing hormone agonists (GnRH-alpha) in the treatment of adenomyosis with infertility. METHODS: Adenomyosis was diagnosed under lapososcopy in 4 infertile cases. Meanwhile coexsting endometriosis, pelvic adhesion and adenomyoma were treated by surgery and endocoagulator in 4 and 2 cases respectively. GnRH-alpha (triptorelin or goserelin) therapy was given for six months before laparoscopic surgery in 1 case and after laparoscopic surgery in 3 cases. Their fecundity outcome were followed-up after cessation of GnRH-alpha treatment. RESULTS: All cases became amenorrheic during GnRH-alpha therapy. The enlarged uteri all decreased to normal or near normal size. Menstruation returned in 80-90 days after cessation of treatment. Three cases conceived within four menstrual periods. One of them resulted in the birth of a healthy 3 150 g male at 38 weeks gestation by cesarean section. The second pregnancy resulting after adenomyomectomy was terminated by emergent cesarean section at 30 weeks gestation because of threatened rupture of uterus. The third is now normal at 28 weeks pregnancy. The fourth has had 2 menstrual periods and is still being followed up. CONCLUSION: (1) GnRH-alpha thus used is efficient in reducing the adenomyotic uterine size, and may facilitate fertility. (2) For ademyomata associated with infertility, GnRH-alpha therapy may avoid the risk of rupture of uterus which may occur after adenomyomectomy pregnancy. (3) For infertility, GnRH-alpha treatment before laparoscopic surgery greatly decreases surgical difficulties and blood loss in certain cases.

Adult↗

PubMed1999

Mechanical and histological analysis of bone-pedicle screw interface in vivo: titanium versus stainless steel.

OBJECTIVE: To investigate the differences in bone interface between titanium and stainless steel pedicle screws in the lumbar spine. METHODS: Eighteen adult mini-pigs that underwent total laminectomy, posterolateral spinal fusion (L4-L5) were randomly selected to receive stainless steel (9) or titanium pedicle screw devices (9). In both groups, the devices were CCD (Sofamore Danek) type with the same size and shape. The postoperative observation time was 3 months. Screws from L4 were harvested along their long axis of pedicle for histomorphometric study. Bone-screw interface and bone volume from thread were examined using linear intercept techniques. Mechanical testing (torsional test and pull-out test) was performed on the screws from L5. RESULTS: The titanium screw group had a significantly higher maximum torque (P < 0.05) and angle related stiffness (P < 0.05) measured by torsional test. In the pull-out tests, no differences were found between the two groups in relation to the maximum load, stiffness and energy to failure. Direct bone contact with the screw in percentage was 29.4% for stainless steel and 43.8% for titanium (P < 0.05). No differences in the bone purchase between the vertebral body part and pedicle part were found. CONCLUSION: Pedicle screws made of titanium have a better bone-screw interface binding than screws made of stainless steel. Torsional tests are more informative for bone-screw interface study. Pull-out tests seem less valuable when comparing bone purchase of screws made from different materials.

Animals↗

PubMed1999

[A study on the etiology of Budd-Chiari syndrome].

OBJECTIVE: To investigate the etiology of Budd-Chiari syndrome (BCS) with finding in surgical operation. METHODS: Thirteen patients with BCS undertook direct vision membranectomy and reconstruction of inferior vena cava. The specimens were studied with light microscopy, electron microscope and immunohistochemistry. RESULTS: Membranous occluding changes, which thickness varying from 2 to 20mm, were found in the posthepatic segment of inferior vena cava during the operation. Thrombi in inferior vena cava were found in 7 cases, 3 of them with thrombi evenly extending to the root of hepatic vein. The compromised venous wall showed proliferation of fibrous connective tissue, hyalinization or mucoid degeneration under light microscopy, 9 of the 13 cases showed chronic infiltration of inflammatory cells. Copious collagenous fibers, few endothelial cells and mitochondria swelling were found with electron microscope. No immune complex (IgA, IgG, IgM) was observed by immunohistochemistry. CONCLUSION: It is concluded that in these cases of BCS, occluding and stenosing lesions in the inferior vena cava were the outcome of thrombosis and its sequelae and local inflammation might be one of the reasons of thrombosis. There was no evidence of congenital malformation.

Adult↗

PubMed1999

[Experimental study of radiofrequency thermocoagulation and applied anatomy of posterior rami of lumbar nerves].

OBJECTIVE: To determine points of radiofrequency thermocoagulation of the posterior rami of the lumbar nerves and to choose an effective temperature at which the conduction of painful impulse can be blocked. METHODS: The posterior rami of the lumbar nerves were dissected in 15 corpses of adults. The ultrastructure of nerve fibres, changes of sensary conduction velocity (SCV) and the waveform of the unmedullated fibres which conduct painful impulse (c wave) were observed after the sciatic nerves of rabbits were coagulated at various temperatures (60 degrees C, 70 degrees C, 80 degrees C, 90 degrees C). RESULTS: "Transverse Process Root Area" and "Transverse Process Point" can be regarded as primary marks of thermocoagulation of the posterior rami of the lumbar nerves. Stimulation of square-wave can make the location more accurate. While the temperature of thermocoagulation reached 80 degrees C, none of painful afferent nerve fibres survived. CONCLUSIONS: With accurate location and good control of temperature, radiofrequency thermocoagulation will be an effective therapy for the patients suffering from pain resulted from pathological changes of the posterior rami of the lumbar nerves.

Adult↗

PubMed1999

[Effect of fodder components on the product of obese gene expression--leptin in rats].

OBJECTIVE: To study the effects of different fodder components and levels of caloric uptake on the product of obese gene expression -- leptin and in vivo secretion of insulin and growth hormone, and to study the relationship between them in rats. METHODS: Plasma leptin was determined by Western blot, and serum insulin and growth hormone were determined by radioimmunoassay (RIA). RESULTS: There was no significant effects of fodder components, including high protein, fat and carbohydrate, on the levels of leptin, insulin and growth hormone in rats, with the same caloric uptake in them. However, with the higher caloric uptake, level of obese gene expression increased, showing increased levels of plasma leptin and serum insulin and decreased level of serum growth hormone. CONCLUSION: There could existed an interaction between expression of obese gene and secretions of leptin, insulin and growth hormone, which could be modified by the same metabolic signal.

Adipose Tissue↗

PubMed1999

[Studies on changes in levels of hormone and expression of ob gene during induction of obesity in rats].

OBJECTIVE: To study the rules of changes in ob mRNA and its relation to hormone level in vivo in rats during their dynamic process to obesity induced by high-caloric fodder. METHODS: Level of ob mRNA in adipose tissues of rats was determined with dot-hybridization techniques, and levels of serum insulin and growth hormone were measured with radioimmunoassay. RESULTS: Level of ob mRNA in the fatty tissues and serum insulin level increased, but serum level of growth hormone decreased, with the increase in body weight of rats. CONCLUSION: Increase in expression of ob mRNA could be the result, but not the cause, of obesity. Changes in the levels of ob mRNA, serum insulin and growth hormone indicated that they could affect each other and could be regulated by common metabolic signals.

Adipose Tissue↗

PubMed1999

[Apoptosis of chondrocytes in experimental osteoarthritis].

The right knees of rabbits were immobilized in full extension for up to eight weeks using plaster cast. Specimens of the articular cartilage obtained from tibial plateau were studied by histopathologic and TDT-mediated fluorescein-dUTP nick-end labelling(TUNEL) techniques. The results showed that TUNEL-positive chondrocytes with apoptosis specific morphology were detected on superficial and middle layer of the articular cartilage from one to two weeks after immobilization, and these changes progressed until 4 weeks after immobilization. Six weeks after immobilization, TUNEL-positive chondrocytes were seen through the entire thickness of the articular cartilage. Our findings indicate that apoptosis of chondrocytes could be induced by immobilization and might be responsible for articular cartilage degeneration, and which is one of the pathways involved in the pathophysiological mechanism of osteoarthritis.

Animals↗

PubMed1999

[Determination of nitrite in serum and tissue by oscillopolarography].

A method for determining nitrite in serum and placenta tissue by oscillopolaropgraphy is reported in this paper. Nitrite in 0.10 ml of serum or placenta homogenate reacts with sulfanilmide and N-1 (1-Naphthyl)-ethylendiamindihydrochloride in diluted hydrochloric acid medium to form an azo compound which can produce a sensitive reductive polarographic wave in ammonium alkaline medium. The wave height is directly proportional to the nitrite content, the method has a detection limit of 0.56 microgram/L (corresponding to the nitrite content of 0.61 mumol/L in serum or 0.22 microgram/g), RSD, of 6.1%-7.8% and recoveries of 92.0%-108.0% (mean value 100.6%). The method is sensitive, simple and can determine the nitrite directly without removal of the proteins in the samples.

Humans↗

PubMed1999

[Biological characters of adenoid cystic carcinoma cells transduced with HSV-tk gene].

OBJECTIVE: To study the effects of herpes simplex virus thymidine kinase(HSV-tk) gene transduction on adenoid cystic carcinoma(ACC) cells. METHODS: Gene transduced cells were detected with growth rate, scanning electronic microscope, transmission electronic microscope, cell cycle analysis and the expression of major histocompatibility complex(MHC) class I or II molecules. RESULTS: The parameters detected in gene transduced cells and parental tumor cells were similar. CONCLUSION: The HSV-tk gene transduction would not change the biological characters of tumor cells greatly.

Carcinoma, Adenoid Cystic↗

PubMed1999

[Detection of neuroendocrine feature about salivary adenoid cystic carcinoma].

OBJECTIVE: To study the possibility of neuroendocrine feature of salivary adenoid cystic carcinoma (SACC). METHODS: Immunohistochemical staining was operated in SACC with S-100 protein, Neuron-specific enolase (NSE), chromagranin A and synaptophysin which are specific and correlative with neuroendocrine and neoplasias. RESULTS: The positive expression of S-100, NSE, chromogranin and synaptophysin were respectively 42, 32, 8 and 7 in 50 cases of SACC. CONCLUSION: There is possibility of neuroendocrine feature in some SACC cells.

Adult↗

PubMed1999

[A treatment to serious esophageal cicatrices stenosi by metal and silica gel dilator].

OBJECTIVE: To find an effective method of treating the esophageal cicatricial stenosis. METHOD: Six cases with esophageal cicatricial stenosis were treated by mental and silica gel dilator. RESULT: The effects in all six cases were satisfactory and no any complications were finded. CONCLUSION: The method is safe, effective and of no complications, the treatment time is shorter also.

Adolescent↗

PubMed1998

Partial purification of heparanase activities in Chinese hamster ovary cells: evidence for multiple intracellular heparanases.

Heparanases are mammalian endoglycosidases that cleave heparan sulphate glycosaminoglycans from proteoglycan core proteins and degrade them into shorter chains. The enzymes have been proposed to act in a variety of cellular processes, including proteoglycan catabolism, remodelling of basement membranes and release of heparan sulphate-binding ligands from their extracellular storage sites. Additional functions for heparanases may be to generate short heparan sulphate chains that stabilize or activate other proteins. While heparanase activities have been described in a number of tissues and cell lines, it is not known how many different enzymes are responsible for these activities. Our recent studies characterizing the short glycosaminoglycans produced in Chinese hamster ovary (CHO) cells suggested that multiple heparanases are necessary for the formation of the short heparan sulphate chains [Bame and Robson (1997) J. Biol. Chem. 272, 2245-2251]. We examined whether this is the case by purifying heparanase activity from CHO cell homogenates. Based on their ability to bind ion-exchange resins and their elution from gel-filtration columns, four separate heparanase activities were partially purified. All four activities cleave free glycosaminoglycans over a broad pH range of 3.5-6.0 or 6. 5, suggesting that they act in the endosomal/lysosomal pathway. The sizes of the short heparan sulphate chains generated by the partially purified heparanases ranged from 6 to 9 kDa, and for two of the activities the product size is pH-dependent. Three of the four activities degrade proteoglycans as well as the free glycosaminoglycan chain. Interestingly, all four enzymes generate short glycosaminoglycans with a sulphate-rich, modified domain at the non-reducing end of the newly formed chain. Since our previous studies showed that in CHO cells there is also a population of short heparan sulphates with a modified domain at the reducing end of the chain, this suggests that there may be another heparanase in CHO cells that was not purified. Alternatively, our findings suggest that the formation of short heparan sulphate glycosaminoglycans inside CHO cells may be a result of the concerted action of multiple heparanases, and may depend on the proportions of the different enzymes and the environment in which the chains are degraded.

Animals↗

PubMed1998

The NMR solution structure of human glutaredoxin in the fully reduced form.

The determination of the nuclear magnetic resonance (NMR) solution structure of fully reduced human glutaredoxin is described. A total of 1159 useful nuclear Overhauser effect (NOE) upper distance constraints and 187 dihedral angle constraints were obtained as the input for the structure calculations for which the torsion angle dynamics program DYANA has been utilized followed by energy minimization in water with the AMBER force field as implemented in the program OPAL. The resulting 20 conformers have an average root-mean-square deviation value relative to the mean coordinates of 0.54 A for all the backbone atoms N, Calpha and C', and of 1.01 A for all heavy atoms. Human glutaredoxin consists of a four-stranded mixed beta-sheet composed of residues 15 to 19, 43 to 47, 72 to 75 and 78 to 81, and five alpha-helices composed of residues 4 to 9, 24 to 34, 54 to 65, 83 to 91, and 94 to 100. Comparisons with the structures of Escherichia coli glutaredoxin-1, pig liver glutaredoxin and human thioredoxin were made. Electrostatic calculations on the human glutaredoxin structure and that of related proteins provide an understanding of the variation of pKa values for the nucleophilic cysteine in the active site observed among these proteins. In addition, the high-resolution NMR solution structure of human glutaredoxin has been used to model the binding site for glutathione and for ribonucleotide reductase B1 by molecular dynamics simulations.

Glutaredoxins↗

PubMed1998

Overexpression, purification, and biophysical characterization of the heterodimerization domain of the core-binding factor beta subunit.

Core-binding factors (CBF) are heteromeric transcription factors essential for several developmental processes, including hematopoiesis. CBFs contain a DNA-binding CBF alpha subunit and a non-DNA binding CBF beta subunit that increases the affinity of CBF alpha for DNA. We have developed a procedure for overexpressing and purifying full-length CBF beta as well as a truncated form containing the N-terminal 141 amino acids using a novel glutaredoxin fusion expression system. Substantial quantities of the CBF beta proteins can be produced in this manner allowing for their biophysical characterization. We show that the full-length and truncated forms of CBF beta bind to a CBF alpha DNA complex with very similar affinities. Sedimentation equilibrium measurements show these proteins to be monomeric. Circular dichroism spectroscopy demonstrates that CBF beta is a mixed alpha/beta protein and NMR spectroscopy shows that the truncated and full-length proteins are structurally similar and suitable for structure determination by NMR spectroscopy.

Circular Dichroism↗

PubMed1998

Camptothecin analogues/cisplatin: an effective treatment of advanced bladder cancer in a preclinical in vivo model system.

OBJECTIVE: To evaluate the impact of the camptothecin analogs on human TCC xenograft, both as monotherapy and in combination with cisplatin (CDDP). MATERIALS AND METHODS: Human transitional cell carcinoma (TCC) xenograft tumor line (DU4184) tested by subrenal capsule assay in 112 nude mice(NM-SRCA). CDDP and the camptothecin analogs irinotecan (CPT-11) and 9-aminocamptothecin(9-AC) were evaluated. RESULTS: Both of the camptothecin analogs showed significant short term tumor inhibition which translated into enhanced survival. Maximal tumor inhibition (>95%) was achieved when either of the camptothecin analogs was combined with CDDP with minimal host toxicity. This translated into 400% increase in median survival. While all controls were dead 39 days following tumor implantation, none of the combination treated animals had died. CONCLUSION: The combination of CDDP with these camptothecin analogs is an effective therapy against this model of advanced TCC. These observations suggest potential clinical value.

Animals↗

PubMed1998

Dose profiles in the region of abutting photon and electron fields in the irradiation of head and neck tumors.

In the treatment of head and neck tumors, after excluding the spinal cord from the primary photon beam, en face electron fields are employed to boost the dose to the tissues overlying the spinal cord. The electron fields are "hot-matched" on skin with the posterior edges of the photon fields irradiating the primary tumor. The purpose of this study is to measure the dose distribution in the "hot" matched region between the photon and the en face electron fields. Using film dosimetry, we measured the dose distributions at depths of 1 cm and 3 cm in the junction of the abutting photon (4 MV) and electron (9 MeV) fields for a hot-match setup. Two photon field setups were studied: (1) laterally opposed and, (2) shallow (5 degrees) right and left anterior oblique fields, a configuration sometimes used to avoid treating through the shoulders. To investigate the changes in dose distributions due to setup uncertainties, we also measured dose profiles at the same two depths using a 2 mm overlap and a 2 mm gap between the electron and photon fields. For a perfect hot-match, the dose profile across the junction at 1 cm depth consists of "hot-spots" on both sides of the junction. The minimum and maximum doses across the junction are 15% and 58%, respectively, above the prescribed dose for a parallel opposed setup and 35% and 54%, respectively, for the angled setup. At 3 cm depth, a 10% "cold spot" is observed in the electron field proximal to the junction while a 50% 'hot spot' is observed in the photon field for the opposed lateral setup. With the lateral fields angled 5 degrees anteriorly, hot spots are observed on both sides of the junction. The minimum and maximum doses are 23% and 54%, respectively, above the prescribed dose. With the right and left anterior oblique fields, a 2 mm overlap of the en face electron field with the ipsilateral photon field resulted in a 72% and 65% hot spot at 1 cm and 3 cm depths, respectively, in the photon field adjacent to the junction. A 2 mm gap still resulted in about a 45% hot spot in the same region at both depths. Clinically, if dose to the overlying tissue of the spinal cord is of primary concern, our measurements suggest that 80% normalization in the electron boost, together with a slight angulation of the photon fields would ensure adequate dose to the overlying tissues. If dose inhomogeneity to the superficial tissues is critical in the electron irradiation, 90% dose normalization in the electron boost, together with laterally opposed photon fields would be preferred. The clinical decision can only be made on a patient-by-patient basis.

Electrons↗