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Biomedical subjects

B Su

Publications and source records attributed to B Su.

At least 109 records · Page 6Linked to original sources
PubMed1994

Human granzyme B is essential for DNA fragmentation of susceptible target cells.

We have partially characterized the granules of the human NK cell line, YT-INDY, and assessed granule-mediated lysis and DNA fragmentation of assorted targets. Biochemical studies demonstrated significant quantities of granzyme B (asp-ase) and a heretofore undescribed chymase but no tryptase (i.e., granzyme A or 3) or distinct met-ase. YT-INDY expressed mRNA for granzyme B, perforin and CCPX. The existence of perforin was confirmed by immunoblot. The granules lysed both human and murine NK-sensitive and NK-resistant targets. YT-INDY and NK3.3, two human cytotoxic cells, were also lysed. EGTA reduced lysis by only 50%, suggesting that a perforin-independent lytic pathway is associated with the granules. In addition, 4-(2-aminoethyl) benzenesulfonylfluoride hydrochloride (AEBSF), an inhibitor that selectively blocked the chymase and 3,4-dichloroisocoumarin (DCI), an inhibitor that inactivated both chymase and asp-ase activities, marginally affected lysis. By gel electrophoresis and 125I-labeled deoxyuridine release assay, only murine cells (SP2/0 and YAC-1) underwent DNA fragmentation, and cleavage was completely inhibited by DCI, whereas EGTA, AEBSF and aurintricarboxylic acid (ATA) had no effect. The results, therefore, underscore the central role of granzyme B in granule-mediated DNA fragmentation, emphasize that the protease acts via an ATA-resistant endonuclease pathway and stress that nucleolysis does not invariably accompany granule-mediated cytolysis. Finally, ATA inhibited the asp-ase activity of isolated but not granule-associated granzyme B. ATA, therefore, is not a specific endonuclease inhibitor and results obtained with ATA should be viewed cautiously.

Animals↗
PubMed1994

Butyrate increases colonocyte protein synthesis in ulcerative colitis.

Butyrate promotes epithelial cell healing and improves symptoms when administered rectally in patients with distal ulcerative colitis (UC). It was hypothesized that butyrate may enhance healing in patients with UC by stimulating colonocyte proliferation and/or protein production. Mucosa from the descending colon was obtained from patients with UC (n = 5), Crohn's disease (n = 8), diverticulitis (n = 6), and cancer (normal tissue 10 cm from tumor; n = 10). Epithelial cells were isolated using dispase/collagenase and differential sedimentation and incubated for 4 hr at 37 degrees C with either Na butyrate (10 mM) or NaCl (10 mM). Protein synthesis was assessed by [14C]leucine incorporation and proliferation was determined with [3H]thymidine. Mean viability and purity were >88%. Spontaneous proliferation was significantly increased in UC when compared to diverticulitis and normal controls. Butyrate significantly increased protein synthesis in UC epithelial cells when compared to saline control. The therapeutic effects of butyrate in patients with UC may be due to its use by epithelial cells as a metabolic fuel to increase protein production and promote healing.

Aged↗
PubMed1994

Genetic diversity in the Chinese pangolin (Manis pentadactyla) inferred from protein electrophoresis.

We examined protein polymorphism of Chinese pangolins (Manis pentadactyla) from Yunnan Province of China, including two forms of three brown and nine dusky Chinese pangolins. Sixty-two genetic loci were screened; 12 loci were found to be polymorphic. The percentage of polymorphic loci (P) is 0.194, the mean individual heterozygosity (H) is 0.078, and the mean number of alleles (A) is 1.258. Furthermore, we calculated the genetic distance (D) between the two forms and found a low level of genetic divergence (D = 0.0206) between them, which indicates an almost-indistinguishable divergence at the level of proteins.

Alleles↗
PubMed1994

Multiple genotypes of mitochondrial DNA within a horse population from a small region in Yunnan Province of China.

mtDNA genotypes of six domestic horses (three adult short horses whose heights are under 1 m and three common domestic horses) from a small region of 15 km2 in Malipo county of Yunnan province of China were investigated by the technique of restriction fragment length polymorphism (RFLP) with 16 restriction endonucleases which recognize 6-bp sequences. An average of 56 fragments for an individual was obtained. Unlike other domestic animals, this population of horses exhibits high mtDNA genetic diversity. Each of the six horses has a specific mtDNA genotype showing a pattern of multiple maternal origins, as suggested by fossil and literature records. We think the population of horses is an amazing seed-resource pool of horses and hence deserves to be paid more attention from the view of conservation genetics. However, it is also remarkable that we did not find any typical mtDNA genetic markers which would discriminate between short horses and common domestic horses.

Animals↗
PubMed1994

Could the cytokeratin molecule be modulated during tumor transformation in hepatocellular carcinoma?

The stability of cytokeratin during tumor transformation in hepatocellular carcinoma was studied. We applied biochemical methodology to look into the switching of cytokeratin molecules in tumor transformation. First, by centrifugation the cytokeratin molecules were extracted from both liver and hepatoma tissues. The extracts were then soaked with cyanogen bromide-activated Sepharose 4B beads previously coated by monoclonal anti-cytokeratin antibody. The bound molecules were then released from the resin with salt. Second, the isolated molecules of both were treated with lysosomal enzyme and analyzed on two-dimensional gels. The results demonstrated that there was a modulation in cytokeratin molecules, and the hepatoma cytokeratin was generated from the hepatocyte cytokeratin.

Blotting, Western↗
PubMed1994

Isolation and characterization of early pregnancy factor.

Early pregnancy factor (EPF) was purified from the pooled sera of 210 pregnant women at 3-8 weeks of gestation. Sera from healthy nonpregnant women were used as control. The samples (G-II, G-III and G-IV) obtained from pregnant women had EPF activity but no HCG activity. Polyacrylamide gel electrophoresis showed that the major bands in pregnant G-III and G-IV were at similar positions in tube gels. The results of SDS-PAGE showed 3 bands in pregnant G-IV: 57.0 kD, 38.0 kD and 19.0 kD. The basic active form of EPF may be a small peptide of 19.0 kD. The isoelectric points of pregnant G-IV were 6.45 and 8.20.

Chaperonin 10↗
PubMed1993

Identification of a putative tumor marker in breast and colon cancer.

Application of a recently developed phospholipid saponification procedure to malignant colon or breast tissue produces an unidentified phosphodiester resonance in the 31P nuclear magnetic resonance spectrum which appears to correlate with malignancy. Glycerol phosphodiesters were prepared from a malignant breast tumor by a Folch extraction of the tissue followed by saponification of the resulting phospholipids. These compounds were separated by ion exchange chromatography and the compound responsible for this new resonance was isolated and identified as glycerol 2-phosphoglycerol by high resolution nuclear magnetic resonance spectroscopy. Confirmation of this structure was achieved by chemical synthesis of glycerol 2-phosphoglycerol. Attempts to isolate the phospholipid responsible for this resonance showed that it is not derived from a new class of phospholipids but is most likely an artifact of the new saponification procedure used. Glycerol 2-phosphoglycerol is formed via glycerol 2,3-(cyclic) phosphate derived from phosphatidylcholine followed by reaction with glycerol. Malignant tissue is more prone to produce this compound than is nonmalignant tissue and the differences between these tissue types may be a form of phosphatidylcholine that is present in higher concentrations in malignant tumor membranes than in those of normal tissue.

Biomarkers, Tumor↗
PubMed1991

Neuronal specific protein NP185 is enriched in nerve endings: binding characteristics for clathrin light chains, synaptic vesicles, and synaptosomal plasma membrane.

The neuronal specific protein NP185, found associated with brain clathrin-coated vesicles, formed a complex with unphosphorylated, but not with phosphorylated, clathrin light chains. The NP185-clathrin light chain complex was associated with casein kinase II activity, which, in the presence of polylysine, phosphorylated clathrin light chain b but not the NP185. The dissociation of this complex with 50% ethylene glycol pH 11.5 suggests that NP185 binds to hydrophobic domains of clathrin light chains. When NP185 molecules were retained by monoclonal antibody-linked Sepharose beads, they bound synaptic vesicles, decoated vesicles and synaptosomal plasma membrane. Immunohistochemistry on mouse cerebellar tissue sections using 8G8, a monoclonal antibody raised against NP185, showed neuronal specific labeling closely following synaptic distribution. In immunoblots, NP185 shares similar epitopes to those detected in another assembly polypeptide, AP-180, an indication that both proteins are identical. It appears that NP185 plays a specific role in nerve ending functions through its ability to induce clathrin to polymerize into cages, its interaction with synaptic vesicles, with the plasma membrane and with clathrin coat components.

Adaptor Proteins, Vesicular Transport↗
PubMed1991

The glycosyl phosphatidylinositol anchor is critical for Ly-6A/E-mediated T cell activation.

Ly-6E, a glycosyl phosphatidylinositol (GPI)-anchored murine alloantigen that can activate T cells upon antibody cross-linking, has been converted into an integral membrane protein by gene fusion. This fusion product, designated Ly-6EDb, was characterized in transiently transfected COS cells and demonstrated to be an integral cell surface membrane protein. Furthermore, the fusion antigen can be expressed on the surface of the BW5147 class "E" mutant cell line, which only expresses integral membrane proteins but not GPI-anchored proteins. The capability of this fusion antigen to activate T cells was examined by gene transfer studies in D10G4.1, a type 2 T cell helper clones. When transfected into D10 cells, the GPI-anchored Ly-6E antigen, as well as the endogenous GPI-anchored Ly-6A antigen, can initiate T cell activation upon antibody cross-linking. In contrast, the transmembrane anchored Ly-6EDb antigen was unable to mediate T cell activation. Our results demonstrate that the GPI-anchor is critical to Ly-6A/E-mediated T cell activation.

Amino Acid Sequence↗
PubMed1991

Lateral diffusion of membrane-spanning and glycosylphosphatidylinositol-linked proteins: toward establishing rules governing the lateral mobility of membrane proteins.

In the plasma membrane of animal cells, many membrane-spanning proteins exhibit lower lateral mobilities than glycosylphosphatidylinositol (GPI)-linked proteins. To determine if the GPI linkage was a major determinant of the high lateral mobility of these proteins, we measured the lateral diffusion of chimeric membrane proteins composed of normally transmembrane proteins that were converted to GPI-linked proteins, or GPI-linked proteins that were converted to membrane-spanning proteins. These studies indicate that GPI linkage contributes only marginally (approximately twofold) to the higher mobility of several GPI-linked proteins. The major determinant of the high mobility of these proteins resides instead in the extracellular domain. We propose that lack of interaction of the extracellular domain of this protein class with other cell surface components allows diffusion that is constrained only by the diffusion of the membrane anchor. In contrast, cell surface interactions of the ectodomain of membrane-spanning proteins exemplified by the vesicular stomatitis virus G glycoprotein reduces their lateral diffusion coefficients by nearly 10-fold with respect to many GPI-linked proteins.

Animals↗
PubMed1990

Changes in the distribution of mouse oocyte cortical granules and ability to undergo the cortical reaction during gonadotropin-stimulated meiotic maturation and aging in vivo.

Mouse oocyte cortical granule (CG) activation and distribution were investigated during in vivo meiotic maturation to determine the onset of competence to undergo the cortical reaction, which is considered responsible for the block to polyspermy. In the present study, the resumption of oocyte maturation was stimulated by hCG administration. Competence to undergo the cortical reaction (assessed with calcium ionophore A23187) was undetectable (0% loss) in germinal vesicle-stage oocytes 0.5 h after hCG administration. When germinal vesicle breakdown and metaphase I had taken place (3 and 7 h post hCG, respectively), approximately 30% CG loss was observed. Maximal (A23187-inducible) levels of CG loss, 67% and 72%, were present at 10 and 13 h, respectively, during metaphase II. Cortical granule distribution changed dramatically during metaphase I, polar body formation, metaphase II, and post-ovulatory aging in vivo. A stable metaphase II distribution was present from 13 to 18 h. After 24 and 32 h, 28% and 83% of the eggs, respectively, exhibited major alterations in the cortical distribution of CGs, some of which did not appear to be susceptible to release by A23187. These data support the hypothesis that just before ovulation the egg cortex completes the development of its normal structure and physiological competence, which are maintained for only a brief period of time afterward. The implications are discussed for normal fertilization and polyspermy in mammals, including humans.

Aging↗
PubMed1989

Biosynthesis of a phosphatidylinositol-glycan-linked membrane protein: signals for posttranslational processing of the Ly-6E antigen.

The Ly-6E/A protein is a murine cell surface protein expressed at high levels on activated peripheral T cells. The only linkage known to be responsible for its association with the plasma membrane is a phosphatidylinositol-glycan (PI-G) moiety. To examine the biosynthesis of this structure, we constructed a series of mutants of Ly-6E that were expressed in COS cells by using transient-transfection procedures. When 12 or 20 carboxy-terminal residues were deleted from the primary translation product, the PI-G modification was completely abolished and the mutant proteins became secreted. Addition of the PI-G tail was partially inhibited when the charged 12-amino-acid peptide found as a cytoplasmic tail on the transmembrane form of LFA-3 was added to the COOH terminus of the Ly-6E protein. Proteolytic cleavage occurred on this mutant protein, but the PI-G moiety was added to only 50% of the molecules. Changing an Asn residue to a Lys at the hypothetical cleavage site resulted in a PI-G-linked protein having a detectable alteration in electrophoretic mobility. This finding raises the possibility that proteolytic cleavage at other amino acid sites may occur and that PI-G attachment can occur at this new site. A model identifying two regions that may act as necessary signals for the biosynthesis of the PI-G tail is presented.

Amino Acid Sequence↗
PubMed1985

Introital adenosis associated with Stevens-Johnson syndrome.

A 23-year-old woman presented with vulvar pain and dyspareunia 1.5 years after a Stevens-Johnson syndrome. A red friable lesion was identified at the vestibule and lower third of the vagina. The histologic diagnosis was adenosis with a tubal glandular epithelium. The possible histogenesis of this lesion is discussed with a review of the embryology of the lower genital tract.

Adult↗