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J Xiang

Publications and source records attributed to J Xiang.

At least 145 records · Page 8Linked to original sources
PubMed1994

Development of the early mucosal lesions in experimental inflammatory bowel disease--implications for pathogenesis.

The purpose of this study was to better establish the morphologic basis of the early mucosal lesions of experimental inflammatory bowel disease because understanding the development of these lesions has important pathogenetic implications. Sprague-Dawley rats were given 1.5% hydrolyzed lambda-carrageenan orally for 30 days. This produced small intestinal lesions which were then evaluated. Light microscopy showed an increased amount of inflammatory cells in the gut wall with prominent Peyer's patches, microgranulomas, crypt abscesses, pin-point ulcerations, and a repair reaction. Scanning electron microscopy revealed pin-point ulcerations in relation to Peyer's patches. Transmission electron microscopy, in addition to the above findings, showed disruptions of enterocyte microvilli and terminal webs. Follicle-associated epithelium appeared to be a predictive site for the development of crypt abscesses and pin-point ulcerations. Enzyme-linked immunoadsorbent assays indicated that orally administered carrageenan elicited a systemic antibody response. Our results suggest that damage to enterocyte microvilli and terminal webs may be important early events in the morphogenesis of the lesions.

Animals↗
PubMed1994

Single-chain antibody variable region-targeted interleukin-2 stimulates T cell killing of human colorectal carcinoma cells.

Recombinant DNA techniques were used to clone, construct and express the bifunctional molecule FV/IL-2. The FV/IL-2 is a single-chain 37 kDa fusion protein expressed in Escherichia coli under control of the strong T7 bacteriophage promoter in the expression vector pT7-7-FV-IL-2. The fused gene fragment FV-IL-2 contains a single-chain anti-TAG72 FV gene fragment and the human recombinant cDNA fragment of the IL-2 molecule. The renatured soluble form of FV/IL-2 was purified from E. coli inclusion bodies using hydroxylapatite chromatography. The yield of this fusion protein was estimated at 2.0 mg/L. Our data showed that the FV/IL-2 molecule retained the TAG72 antigen-binding specificity and the IL-2 activity as measured in the standard T cell proliferation as well as cytotoxicity assays. Therefore, it may prove to be useful in targeting the biological effect of IL-2 to tumour cells and stimulating its immune destruction.

Amino Acid Sequence↗
PubMed1994

Alterations in the PITSLRE protein kinase gene complex on chromosome 1p36 in childhood neuroblastoma.

p58cdc2L1, a protein kinase implicated in apoptotic signaling, is one of eight separate kinases encoded by three tandemly duplicated and linked genes, which we have termed PITSLRE A, B and C. One allele of this complex on chromosome 1 was either deleted or translocated in each of 18 neuroblastoma cell lines with cytogenetically apparent 1p alterations. A protein encoded by this locus, PITSLRE gamma 1, was absent in three of the lines and a smaller, apparently truncated, PITSLRE polypeptide was found in another line. These findings identify a novel gene complex on chromosome 1 that encodes a protein kinase subfamily. We suggest that the PITSLRE locus may harbour one or more tumour suppressor genes affected by chromosome 1p36 modifications in neuroblastoma.

Alleles↗
PubMed1994

A heavy-chain grafted antibody that recognizes the tumor-associated TAG72 antigen.

Murine anti-TAG72 antibodies react with more than 85% of human colorectal, gastric and ovarian carcinomas. However, the therapeutic utility of murine antibodies in human is severely restricted by their immunogenicity. The construction of humanized antibodies can potentially circumvent this problem. The latter antibodies can be generated by grafting CDRs from a murine antibody onto human immunoglobulin FRs followed by combining the resultant product with human immunoglobulin constant regions. In this study, we constructed a heavy-chain humanized anti-TAG72 antibody that we designated hmM4. This was achieved by the transplantation of CDRs from the murine VH of the ccM4 antibody into FRs of the human myeloma protein NEWM. The humanized antibody hmM4 retained its binding reactivity for the TAG72 antigen as measured by ELISA and Western blotting analysis respectively. However, it showed considerably less immunoreactivity for the TAG72 antigen than the original chimeric antibody ccM4. These results indicate that the murine anti-TAG72 specificity can be grafted to human immunoglobulin, and that the choice of the human immunoglobulin framework for the grafted antibody may be critical in maintenance of the immunoreactivity.

Amino Acid Sequence↗
PubMed1994

Potassium cotransport at the rat choroid plexus.

The choroid plexuses are involved in cerebrospinal fluid (CSF) secretion and CSF K homeostasis. We examined K transport mechanisms present in the isolated rat choroid plexus that may be involved in these functions, predominantly using 86Rb as a marker for K. The study demonstrates that there are two primary uptake mechanisms. Ouabain-sensitive Na-K-adenosinetriphosphatase and bumetanide-sensitive cotransport, probably of the Na-K-2Cl form, account for 48 and 46% of uptake, respectively. Efflux studies demonstrate that the primary K efflux mechanism is also bumetanide-sensitive cotransport with the other major component probably being by K channels as it is inhibitable by barium or quinidine. Efflux via the cotransporter was not inhibited by R(+)-butylindazone, a KCl cotransport inhibitor, but it was enhanced in the presence of ouabain (P < 0.001) or increased extracellular Na concentration (P < 0.01). Furthermore, Na efflux was bumetanide sensitive (P < 0.05). In all, these data suggest that the efflux cotransporter is also of the Na-K-Cl form and that it is the same transporter as the influx mechanism operating in both directions. The evidence presented leads us to hypothesize that this cotransporter is on the apical membrane of the choroid plexus and that it may have a central role in CSF secretion and perhaps CSF K homeostasis.

Animals↗
PubMed1994

Recombinant mouse/human chimeric anti-colorectal carcinoma antibody cACT19.

A mouse/human chimeric antibody cACT19 derived from the murine ACT19 antibody was constructed; it recognizes an epitope different from the sialosyl-Tn on the TAG72 antigen as defined by the B72.3 antibody. This chimeric cACT19 antibody was constructed by using two expression vectors, the heavy chain expression vector mpSV2neo-EP1-VHC gamma 1 and the light chain expression vector mpSV2gpt-EP1-VKCK. These vectors contain the following: (i) the neo or gpt gene as a selection marker, (ii) the murine immunoglobulin promoter and enhancer (EP1), (iii) the genomic DNA fragments of human immunoglobulin constant region (CK and C gamma 1) and (iv) the murine cDNA fragments of VH or VK region cloned from the murine ACT19 cDNA library. These two vector DNAs were sequentially transfected into the SP2/0Ag14 cell line. Transfectants were selected in media containing both G418 and mycophenolic acid. The chimeric cACT19 antibody was purified from the transfectant supernate by Protein A Sepharose chromatography. We confirmed that the chimeric cACT19 antibody was reactive for an epitope that differed from the sialosyl-Tn on the TAG72 antigen. This was achieved by using the TAG72-binding inhibition ELISA utilizing various monosaccharides and disialyllato-N-tetraose with the latter containing the NeuAc2-6 alpha Ga1NAc structure. The immunohistochemical double-staining technique provided further evidence of the difference between the epitope defined by the chimeric cACT19 antibody and the sialosyl-Tn epitope by illustrating complementary as well as noncomplementary expression of these two epitopes in different areas of colon carcinoma tissues. We also demonstrated that the chimeric cACT19 antibody displayed much more effective ADCC and CDC for the human OVAR3 tumor cells than the murine ACT19 antibody. Therefore, the mouse/human chimeric anti-colorectal carcinoma cACT19 antibody may prove to be useful in cancer immunotherapy in its own right, or especially when used in combination with the chimeric B72.3 antibody.

Amino Acid Sequence↗
PubMed1994

Effect of radix salviae miltiorrhizae on EAA and IAA during cerebral ischemia in gerbils: a microdialysis study.

The concentrations of amino acids (AA), stroke index and infarct area were determined in 26 gerbils which were divided into 3 groups: RSM-treated (n = 8), Saline-treated (n = 10) and sham-operated (n = 8). The levels of AA were measured with microdialysis technique in cerebral cortex. The concentrations of neurotransmitter AA, as Glu and GABA and Asp, were significantly increased during the first 60 min after CCA ligation, while the concentrations of non-neurotransmitter AA, as Thr and Ser, had no significant changes. In RSM-treated gerbils, the level of Glu was significantly lower than that of the saline-treated, but the GABA in RSM-treated was significantly higher than that of the saline-treated. The ratio of Glu/GABA was significantly decreased after ischemia. The RSM could improve the reduction of ratio of Glu/GABA during 0-30 min and 91-120 min after cerebral ischemia. There were statistically significant decrease in terms of stroke index in RSM-treated group when compared with saline-treated group at 24 h and 16 h after CCA ligation respectively. The RSM has a tendency to decrease the size of infarct area, but no statistical difference. The results suggest that the neurotransmitter AA involve in the pathophysiological procedures of cerebral ischemia and the RSM can attenuate dysfunctions of EAA and IAA. Furthermore, the results also imply that there may be an alternate way to treat cerebral ischemia by inhibiting the presynaptic releasing of Glu and stimulating the releasing of GABA.

Amino Acids↗
PubMed1993

Production and characterization of a tumor-specific monoclonal antibody ACT19 recognizing an epitope distinctive from sialosyl-Tn on the TAG72 antigen.

AIMS: A murine monoclonal antibody ACT19 directed at the TAG72 tumor-associated antigen, which was originally defined by the B72.3 antibody, was established. METHODS: This was done by immunizing mice with the bovine mucin followed by the selection of hybridomas secreting antibodies with the desired specificity. In order to better characterize this antibody, its immunoreactivity was compared to that of the B72.3 antibody. RESULTS: The data showed that the ACT19 antibody bound specifically to the TAG72 antigen as the B72.3 antibody did. However, there were some differences between ACT19 and B72.3. Firstly, the immunoreactivity of ACT19 for the bovine mucin was lower than that of B72.3. Secondly, the immunoreactivity of ACT19 for the TAG72 antigen was not inhibited by N-acetylgalactosamine, nor was that of B72.3. Thirdly, ACT19 did not compete the binding reactivity of B72.3 for the TAG72 antigen. This suggests that the epitope defined by ACT19 is different from the siaosyl-Tn epitope recognized by B72.3. Immunoperoxidase staining of various tumors, normal and embryonic tissues for ACT19 was carried out. For the various tumors, only adenocarcinomas from the colon and stomach showed remarkable positivity. All the normal tissues were negative, except for weak positivity involving the zona reticularis of the adrenal cortex, and intestinal goblet cells. Embryonic tissues showed a wide spectrum of positivity with staining of the small and large intestine, stomach and renal tubules. CONCLUSIONS: The ACT19 antibody appears to be a useful marker for colon and stomach cancers, and this additional anti-TAG72 antibody may be useful in conjunction with the B72.3 antibody in pathology and clinical application.

Acetylglucosamine↗
PubMed1993

Potassium transport at the blood-brain and blood-CSF barriers.

Figure 5 gives a summary of K transporters at the BBB based on the available evidence. It appears that the cerebral endothelial cells have an array of potassium channels, although the degree to which each is open under physiological conditions is uncertain. Different channels are present on the luminal and abluminal membranes, and the opening and closing of these channels may allow modulation of the brain K influx and efflux rates and play a role in brain K homeostasis. These channels may also play a role in hyperosmotic brain volume regulation by increasing the entry rate of potassium into brain and may be involved in volume regulation of the endothelial cell itself. The nature of fluid transport at the BBB remains to be fully elucidated, with the presence of a Na/K/2Cl co-transporter being uncertain. The abluminal inwardly-rectifying channel may act as a leak pathway to allow modulation of fluid secretion by the Na/K ATPase without altering the K concentration of that fluid. Finally, there is some evidence that K transport at the BBB is under hormonal and neuronal control. The cerebral capillaries possess receptors for many of the hormones present in blood and brain.

Animals↗
PubMed1993

Differences in antigen-binding affinity caused by a single amino acid substitution in the variable region of the heavy chain.

Site-directed mutagenesis has been used to examine the importance of histidine-99 in the VH CDR3 region of a mouse/human chimeric anti-TAG72 antibody, cB72.3-1-3. The expression vectors mpSV2neo-EP1-V-m4-10C gamma 1, containing seven different mutant VH region fragments (Vm4-10) in association with the immunoglobulin enhancer (E), promoter (P1) and human genomic C gamma 1 region fragments, were transfected into a heavy chain loss mutant cell line B72.3 Mut(K), respectively. Mutant chimeric antibodies cB72.3m4-10 were purified from the transfectant supernates, and their binding affinities for the TAG72 antigen relative to that of the original cB72.3-1-3 antibody were compared. Substitution of histidine-99 by glutamine resulted in a higher affinity antibody (cB72.3m4) whereas substitution by isoleucine resulted in a lower affinity antibody (cB72.3m9). The binding affinity of these mutant antibodies varied nearly eight-fold. It was concluded that the residue at position 99 in the VH CDR3 region is in a 'contact' position in the B72.3/TAG72 antibody-combining site. The polar side-chains of glutamine and asparagine or the ionized side-chains of histidine, arginine or glutamic acid contribute to higher binding affinity, whereas the hydrophobic side-chains of isoleucine, leucine or phenylalanine resulted in a lower binding affinity for the TAG72 antigen.

Amino Acid Sequence↗
PubMed1993

High binding affinity chimeric anti-colorectal carcinoma antibody correlated to enhanced tumor binding and effector function.

The genetically engineered mouse/human chimeric cB72.3m4 and cB72.3m12 antibodies all recognized the tumor-associated TAG72 antigen. The high affinity cB72.3m4 antibody had an approximately 18-fold higher affinity constant for the TAG72 antigen than the low affinity cB72.3m12 antibody. The relationship amongst antibody binding affinity, tumor binding and effector functions was studied by using these two antibodies. The data showed that the high affinity cB72.3m4 antibody was reactive with, on average, 15% more colon adenocarcinoma cells on tissue sections than the low affinity cB72.3m12 antibody, and it did not produce any cross-reactivities with various normal tissues. The high affinity cB72.3m4 antibody was able to mediate more effective ADCC and CDC to the human ovarian cancer cells in vitro than the low affinity cB72.3m12 antibody. This study provides evidence that this high affinity chimeric cB72.3m4 antibody may be useful in both immunodetection and immunotherapy of cancer.

Adenocarcinoma↗
PubMed1993

The tyrosine residue at position 97 in the VH CDR3 region of a mouse/human chimeric anti-colorectal carcinoma antibody contributes hydrogen bonding to the TAG72 antigen.

One amino acid, tyrosine at position 96 and 97 in the VH CDR3 region of a mouse/human chimeric anti-TAG72 antibody cB72.3m4 was substituted by the phenylalanine residue and by a number of amino acids from different amino acid groups by the site-directed mutagenesis technique. The expression vector mpSV2neo-EP1-Vm11-16C1 containing mutant VH region fragments (Vm11-16) as well as the immunoglobulin enhances (E), promoter (P1) and the human genomic C1 region fragments, were transfected into a heavy-chain-loss mutant cell line B72.3Mut(K), respectively. Mutant chimeric cB72.3m11-16 antibodies were purified from the transfectant supernates and compared based upon their binding affinity for the TAG72 antigen relative to that of the original cB72.3m4 antibody. The data showed that a single amino acid substitution of tyrosine by phenylalanine and a number of amino acids including serine, asparagine, histidine and arginine at position 97 in the VH CDR3 region all resulted in approximate 18-fold lower binding affinity, whereas the substitution of tyrosine by phenylalanine at position 96 in the VH CDR3 region did not affect the binding affinity of the cB72.3m4 antibody. This suggests that the tyrosine residue at position 97 in the VH CDR3 region is in a contact position in the B72.3/TAG72 antibody/antigen interaction, and that the terminal hydroxyl group of the position 97 tyrosine side-chain contributes hydrogen bonding to the TAG72 antigen, whereas the position 96 tyrosine side-chain does not.

Animals↗
PubMed1993

Recombinant bifunctional molecule FV/IFN-gamma possesses the anti-tumor FV as well as the gamma interferon activities.

Recombinant DNA techniques were used to clone, construct and express the bifunctional molecule FV/IFN-gamma. The FV/IFN-gamma is a single-chain 42KD fusion protein expressed in E. coli under control of the strong T7 bacteriophage promoter in the expression vector pT7-7-FV-IFN-gamma. The fused gene fragment FV-IFN-gamma containing a single-chain anti-TAG72 FV gene fragment as well as the human recombinant cDNA fragment of IFN-gamma molecule. The renatured soluble form of FV/IFN-gamma was purified from E. coli inclusion bodies using HTPT chromatography. The yield of this fusion protein was estimated at 10mg/L. Our data showed that the FV/IFN-gamma molecule retained the TAG72 antigen-binding specificity and the IFN-gamma activity as measured in ELISA, Western blotting and up-regulation of CEA expression by IFN-gamma. Therefore, it may prove to be useful in targeting the biological effect of IFN-gamma to tumor cells and stimulating its immune destruction.

Antigens, Neoplasm↗
PubMed1993

Production of a bifunctional hybrid molecule B72.3/metallothionein-1 by protein engineering.

A hybrid anti-tumour B72.3 antibody/metallothionein protein B72.3MT-1 was produced by the construction of the expression vector mpSV2neo-EP1-B72.3MT-1. This vector contained the neo gene as a selection marker, the murine immunoglobulin promoter and enhancer, and the hybrid B72.3 heavy chain gene fragment with mouse metallothionein-1 cDNA gene ligated into its CH2 domain. The expression vector was transfected to the heavy chain loss mutant B72.3Mut(K) cell line. The hybrid protein B72.3MT-1 was purified from transfectant supernates using a Protein G column. We showed that the hybrid protein retained the binding reactivity for the TAG72 antigen as the original B72.3 antibody, and the metal-binding capacity of the native metallothionein molecule. Therefore, the bifunctional hybrid protein B72.3MT-1 may be very useful in cancer imaging when labelled with radionuclides such as 99mTc.

Adenocarcinoma↗
PubMed1992

Differentiative changes in fucosyltransferase activity in newborn rat epidermal cells.

An enzymatic activity catalyzing the transfer of L-fucose from GDP-L-fucose to a glycoprotein that is associated with the surfaces of the basal cells has been found in the membranous fraction of the cutaneous epidermis from the newborn rat. This fucosyltransferase which is located in the differentiated cells alters the acceptor glycoprotein's lectin-binding specificity from the Isolectin I-B4 of Griffonia simplicifolia (GS I-B4) to the Agglutinin I of Ulex europeus (UEA) and could be responsible for the same change in lectin-binding specificity that occurs as the epidermal basal cell differentiates. Another membraneous fucosyltransferase that can use asialofetuin--but not the GS I-B4-binding glycoprotein--as an acceptor, is also present in the membraneous fraction.

Animals↗
PubMed1992

Production of hybrid bispecific antibody recognizing human colorectal carcinoma and CD3 antigen.

The present study reports on the use of gene transfer by vector DNA in the generation of hybrid hybridoma, the quadroma secreting the hybrid bispecific antibody. A quadroma B72.3neo/OKT3gpt was simply derived from the fusion of two hybridoma cell lines, B72.3 and OKT3, tagged with vector DNA mpSV2neo and mpSV2gpt, respectively, and selected in the media containing both G418 and mycophenolic acid. The hybrid bispecific antibody B72.3/OKT3 was purified from the quadroma ascites by the use of hydroxylapatite column on high-pressure liquid chromatography. This bispecific antibody contained one binding site for the TAG72 antigen on OVCAR3 tumor cells and the other binding site for the CD3 molecule on human T cells. It was able to target human T lymphocytes to significantly lyse the human ovarian cancer cells and may therefore be useful in immunotherapy of cancer.

Antibodies, Monoclonal↗
PubMed1992

Construction and characterization of a high-affinity chimeric anti-colorectal carcinoma antibody ccM4.

We have produced a high-affinity chimeric anti-colorectal carcinoma antibody, ccM4, chimerized in both heavy and light chains by the construction of two expression vectors, the chimeric heavy-chain expression vector mpSV2neo-EP1-Vm4Cr1 and chimeric light-chain vector mpSV2gpt-EP1-VKCK. These vectors contained the neo or gpt gene as a selection marker, the murine immunoglobulin promoter and enhancer (EP1), the genomic DNA fragments of human immunoglobulin constant region (CK and C gamma 1), and murine cDNA fragments of VH and VK region amplified and cloned directly from the B72.3 hybridoma RNA by the polymer chain reaction technique. These two vector DNAs were sequentially transfected into the SP2/0Ag14 cell line. Transfectants were selected in media containing both G418 and mycophenolic acid. The ccM4 antibody was purified from transfectant supernatants with positive binding reactivity for the TAG72 antigen on a protein A column. We demonstrated that ccM4 antibody retained the same high binding reactivity for the TAG72 antigen as its counterpart, the high-affinity chimeric heavy-chain cB72.3m4 antibody. The ccM4 antibody bound specifically to human colon cancer cells, displayed biodistribution patterns similar to cB72.3m4 antibody, and mediated effective antibody-dependent cellular cytotoxicity to human OVCAR3 tumor cells. Therefore, the high-affinity chimeric ccM4 antibody should be useful in cancer immunotherapy.

Animals↗