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Biomedical subjects

Y Song

Publications and source records attributed to Y Song.

At least 397 records · Page 22Linked to original sources
PubMed1994

Characterization of a monoclonal antibody directed against the carboxyl-terminus of human factor XIII. An epitope exposed upon denaturation and conserved across species lines.

By deriving an anti-peptide monoclonal antibody, mAb 7A4, we characterized the relatively unstudied carboxyl-terminal end of the a-chain of human factor XIII, the plasma transglutaminase. MAb 7A4 was directed against the last eight amino acids (Gln-Ile-Gln-Arg-Arg-Pro-Ser-Met) and bound with a dissociation constant of 3.4 x 10(-8)M. In a solid assay format, mAb 7A4 bound equally well to factor XIII obtained from human plasma, platelets or placenta. However, in a solution-phase assay format, the epitope was largely unavailable but could be readily exposed by heat denaturation. Immunoblotting showed that this epitope is conserved among all species of plasma factor XIII tested except rabbit suggesting that the carboxyl-terminus might be an important structural element. Other competitive binding experiments with synthetic peptides as inhibitors pointed toward the final carboxyl-terminal amino acid, Met-731, as an immunochemically important determinant. This was used advantageously to confirm the finding that the carboxyl-terminal Met-731 is largely absent from placental factor XIII (1) as compared to platelet or plasma factor XIII.

Amino Acid Sequence↗
PubMed1994

Electrochemical therapy in the treatment of malignant tumours on the body surface.

From November 1988 to May 1991, 113 patients with malignant tumours on their body surface, who were at great operative risk or had refused surgery, underwent local treatment with electrochemical therapy (ECT). After 2.6 years' follow up, total effective rate of the cure was 79.7%. The clinical results were considered satisfactory.

Adolescent↗
PubMed1994

Ultrastructural study of the hemopoietic microenvironment in human fetal spleen.

Reciprocal interactions between hemopoietic stromal cells and immature hemopoietic cells in human spleens obtained from 20 fetuses of 10-28 weeks gestation were observed by transmission electron microscopy and scanning electron microscopy. The close association of stromal cells with immature hemopoietic cells was confirmed under the electron microscope and a presumptive HIM (Hemopoietic inductive microenvironment) was visualized. In regions of immature hemopoietic cell-reticular cell, endothelial cell, macrophage and interdigitating cell contact, some communicating structures were found between the plasma membranes of adjacent cells; moreover, the cytoplasm of these four stromal cells were full of various kinds of organelles. These results suggest that reticular cells, endothelial cells, macrophages and interdigitating cells are component parts of the HIM of human fetal spleen and that these cells have a nurturing function in relation to hemopoietic cells.

Animals↗
PubMed1994

[The effect of trichosanthin on immunoregulatory T lymphocytes].

The effect of trichosanthin (TCS) on immune system has drawn attentions of the investigators both at home and abroad. The purpose of this study is to evaluate the prospects of TCS on autoimmune diseases and immunodeficiency diseases by detecting the immunoregulatory T lymphocytes (T8, 2H4, 4B4) count and cellular DNA content under the influence of TCS with flow cytometer using indirect immunofluorescence technique and lymphocyte culture in normal subjects and systemic lupus erythematosus patients. The results showed that the percentage of T8+ cells decreased, 4B4+ cells increased, 2H4+ cells did not markedly change after adding TCS. The raise of DNA content in S stage was dose-dependent to TCS, especially in large doses. It is concluded that TCS could selectively inhibit T8+ cells and could obviously increase the number of 4B4+ cells. It is suggested that TCS could enhance humoral immunity through the ratio of immunoregulatory T cells. So TCS might help immunodeficiency patients such as AIDS to reestablish their immune system.

Adjuvants, Immunologic↗
PubMed1994

[Transplantation of a minute artery to bridge over the defect of an artery of significantly larger calibre. An experimental study].

Based on our clinical experience for years of "unequal bite" suturing technique to perform end-to-end anastomosis of vessels with great discrepancy in diameter, the animal experimental study was carried out. An artery defect, 1.0-1.4 mm in diameter, was reunited with, an autogenous arterial graft of 0.3-0.4 mm in diameter. A high patency rate (96% in total) was obtained postoperatively. Histological examination by light microscope and scanning electron microscope showed that the unequal bite suturing technique can produce very smooth anastomotic junction and the minute arterial grafts healed well on a large artery. The unequal bite suturing technique is a very valuable development of the basic end-to-end anastomotic technique. A small autogenous arterial graft may be used to repair defect of an artery with large calibre clinically.

Anastomosis, Surgical↗
PubMed1994

[Retinal S-antigen and retinoblastoma--an immunohistochemical study].

A strain of monoclonal antibody, MabAgC6, which defines an epitope in S-antigen, was used to study S-antigen expression in 10 cases of retinoblastoma, where S-antigen immunoactivity was observed in different patterns: the "normal" photoreceptor elements incorporated in 3 cases of growing tumors, 3 of 4 fleurettes and E-W rosettes, and scattered tumor cells in 50% of the cases were stained positive. The results suggest that the expression of S-antigen in retinoblastoma may be used to assess the degree of tumor differentiation, as another of the tumor markers.

Antibodies, Monoclonal↗
PubMed1994

An in vitro study of femoral intramedullary pressures during hip replacement using modern cement technique.

Five femora (four cadaveric and one plastic) were used to measure the intramedullary pressures simultaneously at two different locations along the proximal femur during the insertion of bone cement and the femoral component using modern cement technique. The pressures were monitored by transducers located at the midpoint of each femoral stem (P1), and just beyond the tip of the femoral stem proximal to a cement plug (P2). Transient increases in intramedullary pressure were noted during the initial compaction of the bone cement using a conventional device. However, during insertion of the femoral component, the pressures at P1 and P2 increased dramatically to peak pressures exceeding 2385 mm Hg at P1 and 3710 mm Hg at P2 respectively. These pressure elevations were not sustained; eight to 10 minutes after prosthesis insertion, the pressures decreased to below baseline levels in all five femora. This probably resulted from contraction of the cement during the curing phase. Transient elevations of intramedullary pressure to levels greater than 100 times capillary pressure are produced during hip replacement using modern cement technique. The highest pressures are generated during insertion of the femoral component rather than during the cement compaction step. These findings suggest that the use of a cement compactor to improve intrusion of the cement into bone is probably unnecessary.

Bone Cements↗
PubMed1993

Structure of novel gangliosides, deaminated neuraminic acid (KDN)-containing glycosphingolipids, isolated from rainbow trout ovarian fluid.

Two acidic glycosphingolipids were isolated and purified from rainbow trout ovarian fluid. They were designated as ovarian fluid gangliosides ofg-2a and ofg-2b. Both of these glycolipids were found to contain glucose, galactose, and N-acetylgalactosamine in a molar ratio of 1:2:1, but they differ by the presence of 2 mol of deaminated neuraminic acid (KDN; 2-keto-3-deoxy-D-glycero-D-galacto-nononic acid) in ofg-2a and 1 mol each of KDN and 9-O-acetyl-KDN in ofg-2b. On the basis of composition analysis, methylation analysis, mild acid hydrolysis, fast atom bombardment mass spectrometry (FABMS), 400-MHz 1H nuclear magnetic resonance spectroscopy, and immunochemical analysis using a monoclonal antibody (mAb.kdn3G), the complete structures of these gangliosides were determined to be KDN alpha 2-->3Gal beta 1-->3GalNAc beta 1-->4(KDN alpha 2-->3)Gal beta 1-->4Glc beta 1-->Cer for ofg-2a [(KDN)GD1a] and 9-O-AcKDN alpha 2-->3Gal beta 1-->3GalNAc beta 1-->4(KDN alpha 2-->3)Gal beta 1-->4Glc beta 1-->Cer for ofg-2b [(KDN)GD1a(OAc+)]. The ceramide moieties (Cer) in both ofg-2a [(KDN)GD1a] and ofg-2b [(KDN)GD1a(OAc+)] were found by combining of the results from fatty acid analysis and FABMS measurements to be made up of 4-sphingenine and mainly a C24:1 fatty acyl chain (nervonate). The structures of ofg-2a and ofg-2b are novel, and they represent the second example of naturally occurring KDN-gangliosides. Mild acid hydrolysis of both ofg-2a and ofg-2b resulted in formation of (KDN)GM1a.

Animals↗
PubMed1993

Ionic channel currents in cultured neurons from human cortex.

Ionic channels in human cortical neurons have not been studied extensively. HCN-1 and HCN-1A cells, which recently were established as continuous cultures from human cortical tissue, have been shown by histochemical and immunochemical methods to exhibit a neuronal phenotype, but expression of functional ionic channels was not demonstrated. For the present study, HCN-1 and HCN-1A cells were cultured in Dulbecco's modified Eagle's medium with 15% fetal calf serum, in some cases supplemented with 10 ng/ml nerve growth factor, 10 microM forskolin, and 1 mM dibutyryl cyclic adenosine monophosphate to promote differentiation. Cells or membrane patches were voltage clamped using conventional patch clamp techniques. In HCN-1A cells, we identified a tetrodotoxin-sensitive Na+ current, two types of Ca2+ channel current, including L-type current and a second type that in some respects resembled N-type current, and four types of K+ current, including a delayed outward rectifier that showed voltage-dependent inactivation, two types of noninactivating Ca(2+)-activated K+ channels with slope conductances of 146 and 23 pS (K+i/K+o 145 mM/5 mM), and less frequently, a noninactivating, intermediate conductance channel that was not sensitive to internal Ca2+. When HCN-1A cells were examined after 3 days of exposure to differentiating agents, pronounced morphological changes were evident but no differences in ionic currents were apparent. HCN-1 cells also exhibited K+ and Ca2+ channel currents, but Na+ currents were not detected in these cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium Channels↗
PubMed1993

Role of secretin in negative feedback regulation of postprandial pancreatic secretion in dogs.

BACKGROUND: A negative feedback regulation of pancreatic exocrine secretion has been observed in fasting rats, pigs, and humans, but this phenomenon could not be found in fasting dogs. The aims of the present study were to investigate whether or not postprandial pancreatic secretion is regulated by a negative feedback mechanism and to determine if the mechanism is mediated by secretion and/or cholecystokinin (CCK) in dogs. METHODS: In eight dogs prepared with gastric and Herrera's pancreatic cannulas, pancreatic juice was collected for 3 hours after feeding a mixed meal to measure volume, bicarbonate, and trypsin output. Peripheral venous blood was obtained to determine plasma immunoreactive secretin and CCK levels. Four groups of experiments were performed while pancreatic juice was diverted from the duodenum: (1) diversion of pancreatic juice alone, (2) intraduodenal infusion of fresh pancreatic juice while pancreatic juice was diverted, (3) intraduodenal infusion of 150 mg/h of trypsin and 300 mg/h of chymotrypsin, and (4) intraduodenal infusion of 0.1 mol/L NaHCO3. RESULTS: Pancreatic secretion during diversion of pancreatic juice was significantly greater than that obtained while pancreatic juice was returned. Diversion-induced pancreatic hypersecretion was significantly suppressed by intraduodenal administration of pancreatic proteases, but it was not influenced significantly by 0.1 mol/L NaHCO3. The suppression by either pancreatic juice or proteases paralleled the decrease in plasma secretin response, whereas the CCK response remained unchanged. The inhibitory effect of pancreatic proteases on pancreatic secretion was blocked by a physiological dose of exogenous secretin, 0.06 clinical U.kg-1.h-1. CONCLUSIONS: In dogs, postprandial pancreatic secretion is controlled by a negative feedback mechanism mediated mainly by the release of secretin, but not by CCK.

Animals↗
PubMed1993

Immunocytochemical study with anti-muscle actin antibody (HHF35) on myocardial ischaemia and reperfusion injury in rats.

Myocardial ischaemia and reperfusion injury in 16 anaesthetized Sprague-Dawley rats, eight of which were pretreated with morphine (5 mg/kg, intraperitoneally) to prevent arrhythmias, were studied immunocytochemically with anti-muscle actin specific monoclonal antibody (HHF35). Eight cases of simple ischaemia and eight cases of sham-operated rats were used as controls. With HHF35 ABC immunocytochemical method, the left ventricular myocardium in the reperfusion group (without morphine) showed large areas of staining loss, but no loss of staining was seen in controls. No significant changes were seen with H&E stain in all hearts. Compared with HBFP, acridine orange (AO), eosin-fluorescence, HHF35 ABC staining best demonstrated myocardial reperfusion injury. The results indicate that the degree of myocardial damage may be related to the arrhythmias.

Animals↗
PubMed1993

Monoclonal antibody specific to alpha-2-->3-linked deaminated neuraminyl beta-galactosyl sequence.

Fusion of spleen cells from a BALB/c mouse immunized with KDN alpha 2-->3Gal beta 1-->4Glc beta 1-->1Cer ((KDN)GM3) with P3-X63 Ag8.U1 (P3U1) mouse myeloma cells yielded a hybrid cell line that produced monoclonal antibody that bound to (KDN)GM3, but not to Neu5Ac alpha 2-->3Gal beta 1-->4Glc-beta 1-->1Cer ((Neu5Ac)GM3). The specificity of the monoclonal antibody was determined chiefly by the enzyme-linked immunosorbent assay procedure. This antibody was found to react most strongly with (KDN)GM3 and less strongly with a glycoprotein containing a number of KDN alpha 2-->3Gal beta 1-->3-GalNAc alpha 1-->3[8KDN alpha 2-->)n-->6]GalNAc alpha 1-->chains (< n > av = approximately 3). The results indicated that the monoclonal antibody (designated mAb.kdn3G) specifically and effectively recognized a disaccharide structure, KDN alpha 2-->3Gal beta 1-->, and specifically discriminated (KDN)GM3 from (Neu5Ac)GM3. The mAb.kdn3G was used to localize (KDN)GM3 in rainbow trout sperm by the indirect immunofluorescence procedure and the antigen was shown to be mostly, if not completely, associated with the external surface of the entire plasma membrane of rainbow trout sperm. The potential utility of mAb.kdn3G is addressed in searching for KDN-glycoconjugates which contain glycan units having the KDN alpha 2-->3Gal beta 1-->epitope structure.

Animals↗
PubMed1993

Characterization of a virG mutation that confers constitutive virulence gene expression in Agrobacterium.

Transformation of plants by Agrobacterium tumefaciens is mediated by a set of virulence (vir) genes that are specifically induced by plant signal molecules through the VirA/VirG two-component regulatory system. The plant signal is transmitted from VirA to VirG by a cascade of phosphorylation reactions followed by the sequence-specific DNA binding of the VirG protein to the vir gene promoters which then activates their transcription. In this report, we describe a VirG mutant which is able to activate vir gene expression independently of the VirA molecule and the two plant signal molecules, acetosyringone and monosaccharides. A strain of Agrobacterium containing this virG gene but lacking a functional virA gene was able to induce tumours on all three plants that were tested. A single amino acid change of asparagine (N) to aspartate (D) at position 54, adjacent to the site of VirG phosphorylation, aspartate 52, resulted in this constitutive phenotype. In vitro phosphorylation experiments showed that the mutant protein cannot be phosphorylated by VirA, suggesting that the negative charge resulting from the N to D switch mimics the phosphorylated conformation of the VirG molecule. The same amino acid change in the virG gene of the supervirulent strain A281 also resulted in a constitutive phenotype. However, the vir genes were not induced to high levels when compared with the levels of the constitutive virG of strain A348.

Agrobacterium tumefaciens↗