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Biomedical subjects

T Azuma

Publications and source records attributed to T Azuma.

At least 253 records · Page 14Linked to original sources
PubMed1990

Idiotypical identity of IgG myeloma protein with monoclonal IgM, Bence Jones protein, and Fv derived from one patient.

Serum from a patient (KK) with IgG2-lambda myeloma was shown to contain multiple paraproteins corresponding to an IgM-lambda monoclonal protein (MMP), a lambda-type Bence Jones protein (BJP), and a 30 kDa component in addition to the IgG2 myeloma protein (GMP). These proteins possessed common idiotypic determinants, as judged by their monoclonal reactivity with rabbit anti-GMP idiotype antibody (aId) in the immunofixation electrophoresis. Analysis with aId absorbed with either H or L chain of GMP revealed that the 30 kDa component shared both VH and VL with GMP and MMP, while BJP carried only the VL idiotype. The 30 kDa component, however, failed to react with antibody to either the mu, gamma, alpha, kappa, or lambda isotype, indicating that it had an Fv-like molecular composition. These results suggest that myeloma cells of KK had diverged from the same precursor B cell clone to produce MPs of different isotypes and altered molecular constructions.

Aged↗
PubMed1990

Assignment of cathepsin E (CTSE) to human chromosome region 1q31 by in situ hybridization and analysis of somatic cell hybrids.

A full length cathepsin E (CTSE) cDNA clone was used to assign the corresponding gene to human chromosome region 1q31 by in situ hybridization. Southern blot analysis of DNA from three independent human x rodent somatic cell hybrids containing X;1 translocations confirmed the assignment of the CTSE gene to the distal region of the long arm of chromosome 1.

Blotting, Southern↗
PubMed1990

Enhancing effect of C1q on IgG monoclonal antibody binding to hapten.

We have previously demonstrated that IgG antibody binding to microfilariae of Dirofilaria immitis increased in the presence of purified C1q. The present study was designed to examine the mechanism of the C1q effect using a system with an antihapten monoclonal antibody (MoAb) and a hapten as an antigen. Microtiter plates were coated with 4-hydroxy-3-nitrophenyl-acetyl (NP)-bovine serum albumin (BSA), and mouse anti-NP MoAb (IgG) was added in the presence of C1q. The amount of IgG which bound to NP-BSA increased with the addition of C1q (p less than 0.01) when the antibody had both specificity to the antigen and ability to fix C1q. The C1q effect, examined using two anti-NP MoAbs with different affinities, was more apparent with the low-affinity antibody (LAMoAb) than with the high-affinity (HAMoAb; percent enhancement of IgG binding was 19 vs. 12%). The C1q effect on LAMoAb binding was doubled when a small amount of HAMoAb was incubated with LAMoAb. The C1q effect on IgG binding might be operative in the early phase of infection, where a small amount of high-affinity antibody and a relatively large amount of low-affinity antibody are produced in the host.

Adjuvants, Immunologic↗
PubMed1990

[A case of synchronous multiple primary cancers of the stomach and kidney].

In line with an increase in the incidence of multiple primary cancers, we have encountered a case of synchronous multiple primary cancers of the stomach and the left kidney. The patient, a 69-year-old male, visited our hospital after experiencing epigastric discomfort for three months. An advanced gastric cancer, Borrmann III type, was detected by endoscopic examination. Preoperative abdominal computed tomography also revealed a large low density mass occupying the upper part of the left kidney. On angiography, the left kidney showed a hypervascular mass, showing pooling and tumoral stains, thereby suggesting a renal cell carcinoma. The patient thus underwent a subtotal gastrectomy with an R2 lymph node dissection and a left radical nephrectomy. Histologically, the gastric lesion was a poorly-differentiated adenocarcinoma and the left renal lesion was a renal cell carcinoma of the clear cell type.

Adenocarcinoma↗
PubMed1989

Human gastric cathepsin E. Predicted sequence, localization to chromosome 1, and sequence homology with other aspartic proteinases.

The predicted sequence of human gastric cathepsin E (CTSE) was determined by analysis of cDNA clones isolated from a library constructed with poly(A+) RNA from a gastric adenocarcinoma cell line. The CTSE cDNA clones were identified using a set of complementary 18-base oligonucleotide probes specific for a 6-residue sequence surrounding the first active site of all previously characterized human aspartic proteinases. Sequence analysis of CTSE cDNA clones revealed a 1188-base pair open reading frame that exhibited 59% sequence identity with human pepsinogen A. The predicted CTSE amino acid sequence includes a 379-residue proenzyme (Mr = 40,883) and a 17-residue signal peptide. The predicted CTSE amino acid composition was consistent with that of purified material from gastric mucosa and gastric adenocarcinoma cell lines. Additional evidence for the identification of the CTSE cDNA clones was obtained by analysis of poly(A+) RNA isolated from CTSE-producing and -nonproducing gastric adenocarcinoma cell subclones. Three RNA transcripts (3.6, 2.6, and 2.1 kilobases) were identified in poly(A+) RNA isolated from a gastric adenocarcinoma cell line that produced CTSE that were absent from nonproducing subclones. CTSE contains 7 cysteine residues, of which 6 were localized by comparative maximal alignment analysis with pepsinogen A to conserved residues that form intrachain disulfide bonds. The seventh cysteine residue of CTSE is located within the activation peptide region of the proenzyme. We suspect that this residue forms an interchain disulfide bond and thereby determines the dimerization of CTSE proenzyme molecules that is observed under native conditions. The CTSE gene was localized to human chromosome 1 by concurrent cytogenetic and cDNA probe analyses of a panel of human x mouse somatic cell hybrids.

Amino Acid Sequence↗
PubMed1989

Tolerance induction of allo-class II H-2 antigen-reactive L3T4+ helper T cells and prolonged survival of the corresponding class II H-2-disparate skin graft.

The present study investigates the effects of i.v. presensitization with class II H-2-disparate allogeneic cells on various L3T4+ T cell functions including the capability of rejecting the corresponding allogeneic skin graft. C57BL/6 (B6) mice were i.v. presensitized with class II H-2 disparate B6-C-H-2bm12 (bm12) spleen cells. Such presensitization did not affect the bm12-specific L3T4+ T cell-mediated proliferative and interleukin 2 (IL-2)-producing capacities. A single cell suspension of (B6 x bm12)F1 spleen cells was depleted of APC by two round-passages over Sephadex G-10 columns. This APC-depleted fraction of (B6 x bm12)F1 cells failed to stimulate B6 responding cells in mixed lymphocyte reactions (MLR). The addition of recombinant IL-1 to the MLR restored anti-bm12 MLR responses, indicating that APC-depleted (B6 x bm12)F1 cells bear bm12 alloantigens but are unable to stimulate B6 anti-bm12 L3T4+ T cells. A single i.v. administration of APC-depleted (B6 x bm12)F1 cells into B6 mice resulted in almost complete abrogation of the capacity of recipient B6 lymphoid cells to give anti-bm12 MLR and IL2 production. This suppression was bm12 alloantigen-specific and attributed to the elimination or functional impairment of anti-bm12 T cell clones rather than the induction of suppressor cells. The tolerance was also observed in graft-rejection responses. The strikingly prolonged survival of bm12 skin grafts was produced when grafts were implanted into B6 mice which had been presensitized with APC-depleted, but not with untreated (B6 x bm12)F1 spleen cells. These results indicate that allo-class II H-2 antigen-reactive L3T4+ T cells are rendered tolerant by i.v. presensitization with APC-depleted fraction of the corresponding allogeneic cells.

Animals↗
PubMed1989

Tolerance induction of allo-class I H-2 antigen-reactive Lyt-2+ helper T cells and prolonged survival of the corresponding class I H-2-disparate skin graft.

C57BL/6 (B6) mice were i.v. presensitized with class I H-2-disparate B6-C-H-2bm1 (bm1) spleen cells. Such presensitization resulted in almost complete abrogation of bm1-specific Lyt-2+ T cell-mediated proliferative and IL-2-producing capacities as measured by MLC of lymphoid cells from presensitized B6 mice with stimulating bm1 cells. In contrast, comparable magnitude of CTL responses was generated in bulk cultures from presensitized B6 lymphoid cells to that obtained in unpresensitized B6 responding cultures. These differential influences of Lyt-2+ T cell functions were also demonstrated by limiting dilution assays; frequencies of proliferative and IL-2-producing T cell precursors were as low as undetectable in presensitized B6 lymphoid cells, whereas an appreciable frequency of CTL precursors in a portion of the same lymphoid cells was observed. When bm1 skin grafting was performed in B6 mice i.v. presensitized with bm1 cells, the strikingly prolonged survival of bm1 skin grafts was observed. It was also demonstrated that the bm1 skin graft-bearing B6 mice which had been presensitized with bm1 cells not only exhibited a continuing suppressive state of bm1-specific helper (proliferative and IL-2-producing) function but also failed to generate anti-bm1 CTL responses. These results indicate that 1) i.v. presensitization with class I H-2 alloantigens results in selective tolerance of Lyt-2+ Th cells which is adequate for inducing prolonged graft survival, 2) the induction of complete abrogation of CTL potential is not absolute requirement for the prolongation of graft survival, and 3) residual CTL potential is attenuated after grafting so far as Th cells are rendered tolerant.

Animals↗
PubMed1989

Bispecific F (ab')2 monomer prepared with anti-CD3 and anti-tumor monoclonal antibodies is most potent in induction of cytolysis of human T cells.

Induction of cytolytic activity of peripheral blood mononuclear cells towards target cells was studied by preparing bispecific F(ab')2 which was composed of two Fab' fragments, one of which was derived from anti-CD3 monoclonal antibody and the other from anti-tumor monoclonal antibody. After reduction of the interchange disulfide bonds of these fragments by dithiothreitol, a thiol-disulfide interchain reagent, 5,5'-dithiobis-2-nitrobenzoic acid, was added to convert the free SH groups of one of the Fab' fragments to mixed disulfide derivatives. These were then coupled with the other Fab' fragment bearing free SH groups, producing a bispecific hybrid F(ab')2 monomer of high yield. The bispecific F(ab')2 monomers were able to render nonactivated peripheral blood mononuclear cells cytotoxic against natural killer-resistant tumor cell lines at doses as low as 1 microgram/ml. The polymeric forms of the F(ab')2 fragments prepared by use of cross-linking reagents such as N-succinimidyl-3-(2-pyridyldithiol)-propionate (SPDP) or S-acetylmercaptosuccinic acid anhydride (SAMSA) were less efficient for induction of cytolytic activity than the monomeric one. It may be feasible to use bispecific F(ab')2 monomers in cancer immunotherapy because of the ease of preparation, as well as the efficiency in inducing cytolytic activity and their high tissue permeability due to their small size (100-110 kDa). In addition, redirected cytolytic activity towards peripheral blood mononuclear cells by reticuloendothelial system cells, resulting from linking these two types of cells through Fc-Fc receptor interactions, does not occur.

Antibodies, Neoplasm↗
PubMed1989

Gastrin is a major mediator of the gastric phase of acid secretion in dogs: proof by monoclonal antibody neutralization.

We developed a monoclonal antibody, 28.2, that binds specifically to the amidated carboxyl terminal region common to gastrin and cholecystokinin. This immunoglobulin G1 antibody has high affinity (ID50 = 30-70 pM for gastrin and cholecystokinin peptides), binds labeled gastrin similarly at 37 degrees C and 4 degrees C, and shows minimal inhibition of binding in the presence of 40% canine serum. Antibody 28.2 was used to carry out in vivo immunoneutralization studies in 8 dogs previously prepared with chronic gastric fistulas. Preliminary studies revealed that a single intravenous dose of 0.75 mg of partially purified immunoglobulin G of monoclonal antibody 28.2 completely inhibited the acid stimulatory effect of exogenous gastrin-17 given intravenously at 200 pmol/kg.h, a physiologic dose, and inhibited by 70% the acid response to a supraphysiologic dose, 800 pmol/kg.h. The same dose of antibody decreased the acid secretory response obtained during distention of the stomach with 300 ml of 5.8% glucose solution by 98% and decreased the response to distention with 300 ml of 8% peptone solution by 68%. A 10-fold higher dose of antibody decreased the acid response to peptone by 96%. The gastrin antibody had no effect on the acid response to exogenous histamine. A control antibody, specific for the biologically inactive glycine-extended gastrin/cholecystokinin peptapeptide region, had no significant effect on gastric acid secretion stimulated by gastrin or by gastric distention with nutrients. These studies indicate that circulating gastrin is of major importance in the gastric phase of gastric acid stimulation caused by distention of the stomach with nutrients.

Animals↗
PubMed1989

Human pepsinogen C (progastricsin) polymorphism: evidence for a single locus located at 6p21.1-pter.

A series of six clones containing the entire human pepsinogen C gene (PGC) was identified in a cosmid vector library by using cDNA and oligonucleotide probes. The 10.7-kb PGC gene includes nine exons and exhibits a high degree of sequence identity (60%) with the functionally related pepsinogen A genes. The predicted amino acid sequence was identical with the partial amino-terminal and carboxyl-terminal sequences of purified pepsinogen C. An informative restriction fragment length polymorphism was detected with several restriction enzymes and involved an insertion or deletion of 100 bp of intron sequence located between exons 7 and 8. Evidence that there is only a single PGC gene in humans is presented. The PGC gene and the prolactin gene were regionally localized to 6p21.1-pter by analysis of mouse X human somatic cell hybrids.

Amino Acid Sequence↗
PubMed1989

Experimental drug-induced allergic nephritis mediated by antihapten antibody.

Experimental drug-induced allergic nephritis (DIAN) was mediated by an antihapten antibody. It has been postulated that DIAN is induced by cellular and humoral mechanisms. We tried to induce DIAN in mice, where the mechanism depends on humoral immunity. The first attempt was made in mice actively producing antibodies against cephem antibiotics, i.e. cephalothin (CET). Acute interstitial nephritis (AIN), morphologically similar to human disease, was obtained by injection of a CET-protein conjugate into the renal cortex in mice producing anti-CET-IgE and IgG antibodies. AIN could also be induced when normal mice, passively given anti-CET IgG antibody, received a subsequent intrarenal challenge with CET-protein conjugate. These preliminary results indicate that IgG antibody has an important role in the genesis of DIAN. Further experiments were performed with monoclonal antibodies directed against haptens instead of antibiotics in order to clarify the Ig isotype concerned. In mice passively given anti-Dansyl-IgG2a or anti-NP-IgG2a monoclonal antibodies, a challenge with an appropriate hapten-protein conjugate into the renal cortex resulted in AIN. However, transfer of anti-Dansyl-IgE or anti-DNP-IgE monoclonal antibodies, followed by challenge, did not induce AIN. In the experimental systems described, the involvement of a cellular immune mechanism is excluded. The results suggest that IgG, but not IgE antibody, is essential for the induction of DIAN by humoral immune mechanism.

Animals↗