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M R Suresh

Publications and source records attributed to M R Suresh.

At least 55 records · Page 3Linked to original sources
PubMed1987

T cell recognition of a tumor-associated glycoprotein and its synthetic carbohydrate epitopes: stimulation of anticancer T cell immunity in vivo.

The Thomsen, Friedenreich (TF) and Tn carbohydrate antigens are expressed on the vast majority of human adenocarcinomas and are associated with aggressive behavior of certain tumors. TF and Tn antigens are also expressed on certain murine cancer cell lines including TA3-Ha, a highly lethal, transplantable mammary adenocarcinoma. TF and Tn cancer-associated carbohydrate haptens were synthesized, conjugated to protein carriers and used to demonstrate that delayed-type hypersensitivity (DTH) effector T cells can specifically recognize and respond to carbohydrate determinants on the TA3-Ha tumor-associated glycoprotein, epiglycanin. The effector cells were shown to have the helper DTH phenotype (Lyt1+, Lyt2-, Thy1+) and it was demonstrated that they respond to specific carbohydrate determinants in an MHC-restricted fashion. These experiments provide the rationale for the use of synthetic tumor-associated glycoconjugates (S-TAGs) to stimulate anticancer T cell immunity. In support of this hypothesis, it was shown that preimmunization with the appropriate S-TAGs could provide a degree of protection against a subsequent tumor transplant and that antitumor effector Lyt1+, Lyt2- T cells could be generated in vitro using the appropriate S-TAGs as antigens.

Adenocarcinoma↗
PubMed1987

A molecular approach to immunoscintigraphy: a study of the T-antigen conformation on the surface of tumors.

The role of glycoconjugates in tumor cell differentiation has been well documented. We have examined the expression of the two anomers of the Thomsen-Friedenreich antigen on the surface of human, canine and murine tumor cell membranes both in vitro and in vivo. This has been accomplished through the synthesis of the disaccharide terminal residues in both alpha and beta configuration. Both entities were used to generate murine monoclonal antibodies which recognized the carbohydrate determinants. The determination of fine specificities of these antibodies was effected by means of cellular uptake, immunohistopathology and immunoscintigraphy. Examination of pathological specimens of human and canine tumor tissue indicated that the expressed antigen was in the beta configuration. More than 89% of all human carcinomas tested expressed the antigen in the above anomeric form. The combination of synthetic antigens and monoclonal antibodies raised specifically against them provide us with invaluable tools for the study of tumor marker expression in humans and their respective animal tumor models.

Animals↗
PubMed1987

Monoclonal antibodies and synthetic tumor-associated glycoconjugates in the study of the expression of Thomsen-Friedenreich-like and Tn-like antigens on human cancers.

Synthetic carbohydrate haptens, which are conjugated to carrier human serum albumin molecules [synthetic tumor-associated glycoconjugates (S-TAGs)], were used to immunize mice for monoclonal antibody (MoAb) production. Two of the S-TAGs were composed of haptens related to the Thomsen-Friedenreich (TF) antigen, and their structures are beta Gal(1----3)-beta GalNAc (TF-beta) and beta Gal(1----3) alpha GalNAc (TF-alpha) (Gal = galactose; GaNAc = N-acetylgalactosamine). The third S-TAG was made up of Tn hapten groups of the structure alpha GalNAc-O-serine. MoAbs specific for TF-alpha and Tn were able to be generated. All MoAbs generated against TF-beta cross-reacted with TF-alpha but not with Tn. None of the TF-alpha-specific MoAbs reacted with human carcinomas, whereas several TF-beta and Tn MoAbs were found to react with most human lung, colon, and breast carcinomas. It is believed that this is the first report of the use of synthetic carbohydrate cancer antigens for the production of anticancer MoAbs.

Antibodies, Monoclonal↗
PubMed1986

Advantages of bispecific hybridomas in one-step immunocytochemistry and immunoassays.

A chemical selection procedure has been used to prepare a hybrid hybridoma cell line (P4C1) following fusion of two previously established hybridomas secreting antiperoxidase and antisubstance P, respectively. P4C1 secretes bispecific monoclonal antibody alongside the two parental antibodies, with no visible inactive heterologous heavy-light chain pairs. The bispecific monoclonal antibody is thus easy to purify in excellent yields. The advantage of its monovalency for one antigen and simultaneous binding of a marker enzyme has been explored for its potential use in competitive immunoassays. Its use in immunocytochemistry led to major improvements in sensitivity, signal-to-noise ratio, simplification of staining procedures, and ultrastructural preservation of subcellular elements. Particularly remarkable was that, unlike conventional procedures, the immunoreaction with the bispecific monoclonal antibody was homogeneously distributed across the entire thickness of a 50-micron section.

Antibodies, Monoclonal↗
PubMed1986

Renal tubular receptor imaging with iodine-131-labeled peanut lectin: pharmacokinetics and renal clearance mechanism in animals.

Intravenously administered peanut lectin (PNA), iodinated with 131I ([131I]PNA), is rapidly cleared from the plasma by the kidneys in dogs (clearance [total body] = 17.52 +/- 8.74 ml/min). Dynamic gamma camera renal scintigraphy demonstrated renal accumulation and excretion phases of the [131I]PNA renogram in dogs and rabbits (% injection dose-at-peak = 21.8 +/- 3.3% and 19.6 +/- 4.3%, time-to-peak = 44.6 +/- 4.8 min and 37.2 +/- 6.9 min, respectively). Immunoperoxidase staining of kidney sections, following i.v. administered PNA, demonstrated predominant accumulation by the proximal tubules of mice, rabbits, and dogs. The basement membrane was intensely stained at early times p.i. while intracellular and luminal PNA was evident within 1 hr. Urine analysis confirmed the presence of intact [131I]PNA in the bladder contents, while protein degradation products, and a small percentage of the free iodide (less than 5%) were noted within 1 hr p.i. The relative proportion of free iodide increased at later times p.i. (greater than 6 hr). A receptor mediated excretion mechanism is proposed for the clearance of PNA and may be useful for the study of renal tubular function.

Animals↗
PubMed1986

Transport of folate compounds in L1210 cells: kinetic evidence that folate influx proceeds via the high-affinity transport system for 5-methyltetrahydrofolate and methotrexate.

Folate is transported into L1210 mouse leukemia cells by the same system that mediates the uptake of methotrexate and reduced folate compounds. This conclusion is supported by the following observations: (a) methotrexate competitively inhibits the influx of folate and the Ki is comparable to the Kt for methotrexate influx; (b) the profile for inhibition of folate influx by methotrexate is monophasic and complete inhibition is achieved at high concentrations of the competitor; (c) folate inhibits the influx of methotrexate and the Ki is comparable to the Kt for folate influx; (d) the N-hydroxysuccinimide ester of methotrexate, a potent and specific irreversible inhibitor of the reduced folate system, also blocks the influx of folate; (e) folate and methotrexate influx are both inhibited by low concentrations of p-chloromercuriphenylsulfonate; and (f) folate influx fluctuates with the anionic composition of the medium in the same fashion as the influx of methotrexate. Measurements of folate influx can be complicated by the fact that the 3H-labeled substrate is susceptible to decomposition and that labeled breakdown products at concentrations as low as 1% contribute appreciably to the observed uptake. Of these products, 6-hydroxymethylpterin appears to account for most of the extraneous uptake. Impurities can be eliminated by subjecting the [3H]folate to preparative thin-layer chromatography immediately prior to use.

Animals↗
PubMed1985

A direct antigen-binding assay to screen hybridoma supernatants.

A simple and convenient method of directly assaying hybridoma supernatants for the desired monoclonal antibodies is described which obviates the need for labeled second or third antibody conjugates. Culture supernatants (1-5 microliters) were directly spotted onto a nitrocellulose sheet, and additional protein binding sites blocked with bovine serum albumin and incubated with enzyme-labeled, radioactive, or fluorescent antigen. Positive hybridoma supernatants were identified after washing and detection of bound antigen by appropriate means.

Antibodies, Monoclonal↗
PubMed1985

Radioimmunodetection of murine mammary adenocarcinoma (TA3/Ha) lung and liver metastases with radioiodinated PNA.

Organ-specific lung and liver metastatic variants of the murine TA3/Ha mammary adenocarcinoma cell line were selected by sequential in vivo growth with intervening in vitro cell culture. These variants readily formed specific lung or liver metastatic lesions upon i.v. injection into A/J mice. TA3/Ha cells produce a large cell surface glycoprotein called epiglycanin, which contains a high proportion of Thomsen-Friedenreich (TF) antigenic structures. The presence of non-cryptic TF has been associated with malignancy in humans and animals. We used peanut lectin agglutinin (PNA), which has a preferential affinity for TF antigenic structures, to determine whether these selected metastatic variants retained the TF antigen expression. In vitro, the TA3/Ha metastatic variant lines exhibited strong PNA binding similar to that seen with human RBC after neuraminidase treatment to expose the cryptic TF antigen. In contrast, the non-epiglycanin-producing TA3/St subline did not bind PNA appreciably. Autoradiography of liver sections with TA3/Ha metastatic lesions after 125I-PNA i.v. indicated an avid uptake throughout the viable tumor mass and FITC-PNA staining of these tissue sections readily identified the metastatic tumors under fluorescence microscopy. Tissue biodistribution studies revealed that lung or liver containing the TA3/Ha metastatic variant nodules retained about 7 to 8 times as much of an i.v. dose of radioiodinated PNA as did controls, allowing for clear delineation of tumor-infiltrated lung or liver by gamma scintigraphy. These in vitro and in vivo tests confirm that the selected organ-specific TA3/Ha variants retained the binding characteristics of the parent TA3/Ha line. These observations illustrate the potential utility of radiolabelled PNA for the detection of TF-antigen-expressing tumors and metastases. This murine system with organ-specific TA3/Ha metastatic variants also provides a model for evaluation of various other macromolecular probes for tumor radioimmunodetection of metastatic lesions.

Adenocarcinoma↗
PubMed1985

In vivo localization of radioiodinated peanut lectin in a murine TA3/Ha mammary carcinoma model.

Peanut lectin (PNA) binds avidly to oligosaccharides containing the terminal sequence beta-D-Gal(1----3)alpha-D-GAlNAc. This disaccharide is the immunodeterminant group of the Thomsen-Friedenreich (T) antigen which is present in an exposed form on a number of human and animal adenocarcinomas and can be identified in tumor tissue sections by histochemical PNA staining techniques. We have studied the in vivo uptake of radioiodinated PNA in a murine TA3/Ha mammary adenocarcinoma model to evaluate the potential applications of radiolabeled PNA for the immunodetection of T antigen expressing carcinoma. We have found that PNA has a high in vitro binding affinity for the TA3/Ha tumor cells as well as for epiglycanin, a glycoprotein fraction shed by the TA3/Ha cells. Tissue biodistribution studies after IV 125I-PNA injection into TA3/Ha tumor-bearing mice indicated tumor:blood ratios of 7:1 and 55:1 at 24 and 48 h with corresponding tumor:muscle ratios of 33:1 and 77:1. The high tumor uptake and rapid blood clearance allowed clear scintigraphic delineation of tumor by 24 and 48 h without the necessity for background subtraction techniques. Rapid in vivo deiodination of 125I-PNA also contributed to localization of radioactivity in the stomach, salivary glands, thyroid, and kidney.

Adenocarcinoma↗
PubMed1984

Monoclonal antibody against a cryptic carbohydrate antigen of murine and human lymphocytes. I. Antigen expression in non-cryptic or unsubstituted form on certain murine lymphomas, on a spontaneous murine mammary carcinoma, and on several human adenocarcinomas.

This paper describes an IgM monoclonal antibody (49H.8) which was produced following immunization of BALB/c mice with human neuraminidase-treated erythrocytes (NE-RBC). 49H.8 reacts with NE-RBC, neuraminidase-treated T lymphocytes (NE-T) and NE B lymphocytes of both human and murine origin. Little or no reactivity with untreated T or B cells could be detected. Thus the 49H.8 antigen is "cryptic" in most normal lymphocytes of both humans and mice. In contrast, the 49H.8 antigen was detected in non-cryptic or unsubstituted form on many non-treated murine lymphomas of both B- and T-cell origin, on the spontaneous murine mammary carcinoma, TA3-HA and on several human adenocarcinomas. The 49H.8 antigen appears to be related to the previously described 49H.24 antigen as shown by sugar inhibition experiments. 49H.24 reacts most strongly with the synthetic disaccharide (betaGa1 (I leads to 3)alpha Ga1NAc) but not at all with beta Ga1(I leads to 3)beta Ga1Nac. 49H.24 does not react with any of the murine or human tumors tested. 49H.8 reacts with both the alpha and beta forms of the disaccharide but reacts most strongly with phenyl-beta-galactoside-containing compounds. In contrast, phenyl-alpha-galactoside-containing compounds produced no reaction. The natural determinant detected by this antibody was not determined but various possibilities are considered. 49H.8 was used to detect antigen apparently shed from growing TA3-Ha cells into the serum and ascites of tumor-bearing mice. These observations suggest that the 49H.8 monoclonal antibody will be valuable as a specific reagent for a common tumor-associated antigen shared by certain murine and human tumors, and as a means of assaying shed tumor antigen in circulation as in the TA3-Ha mammary adenocarcinoma model.

Adenocarcinoma↗
PubMed1984

Radiolabelled peanut lectin for the scintigraphic detection of cancer.

To investigate the role of intravenously administered, radioiodinated peanut lectin (131I-PNA) in the non-invasive detection of cancer, the pharmacokinetics and scintigraphic distribution of this novel tumor-seeking compound were studied in 8 patients with metastatic cancer of the colon, breast or lung. Scintigraphic localization of 131I-PNA was apparent at certain anatomical sites of known metastases in 2 patients and in a further 2 patients an adjacent malignant pleural effusion was visualized. The rapid clearance of radioactivity from the whole body and plasma with marked renal concentration and rapid urinary excretion of significant amounts of intact 131I-PNA (mol. wt. 107,000, pI 5.95) implied that this molecule was excreted selectively by the renal tubules. PNA or other lectins may find a role in the scintigraphic detection of selected types of cancer.

Arachis↗
PubMed1982

Transport of folate compounds, pterins and adenine in L1210 mouse leukemia cells.

L1210 mouse leukemia cells provide a convenient model for examining the mechanisms and components involved in the active transport of various metabolites and drugs. One of these transport systems exhibits a broad specificity for folate compounds, including 4-amino antagonists such as methotrexate. The primary substrate for this system is 5-methyltetra-hydrofolate (Kt = 1 microM), the principal circulating form of the vitamin in mammals. 5-Formyltetrahydrofolate (Kt = 5 microM) and Methotrexate (Kt = 5 microM) are also taken up efficiently, but folate (Kt = 100 microM) is a relatively poor substrate. Vmax for this system is ca. 15 pmoles/min/mg protein. Energy for substrate internalization is provided by an anion-exchange mechanism, and regulation appears to be mediated by cyclic AMP. The system can be inhibited irreversibly by treatment of the cells with photo-activated azido AMP or carbodiimide-activated folate compounds. The latter method allows the membrane-associated binding protein to be labeled in situ, thereby providing a means for identifying it during subsequent solubilization and purification. Guidance for this latter project is provided by previous experience in the purification to homogeneity of a similar folate-binding protein from Lactobacillus casei. L1210 cells also contain an efficient system for the transport of adenine (Kt = 20 microM; Vmax = 200 pmoles/min/mg protein). Uptake of adenine is linked with its conversion to AMP via PRPP-dependent adenine phosphori-bosyltransferase. Pterins, which have a close structural similarity to adenine (as well as to a portion of the folate molecule), are also transported into L1210 cells. Transport of [3H] 6-hydroxymethylpterin (Kt = 20 microM) was inhibited by 6-formylpterin, 6-methylpterin and 6-carboxypterin with Ki values of 42, 100 and 350 microM, respectively. Adenine (Ki = 20 microM) and various other purines were also good inhibitors of pterin transport. Present evidence indicates that adenine and pterins use separate transport systems, but isolation of the components of these systems may further delineate their interrelationships.

Adenine↗
PubMed1978

Absence of parallelism between polyamine and nucleic acid contents during induced growth of cucumber cotyledons.

The cytokinins (benzyladenine or benzyladenosine) decreased spermidine and spermine contents despite increasing putrescine content, when administered to isolated cotyledons of Cucumis sativus L. var. Guntur in organ culture. KCl decreased putrescine contents, although marginally increasing polyamine contents. The cytokinins and/or KCl augmented nucleic acid biosynthesis and accumulation, resulting in enhanced growth and differentiation of the isolated cotyledons. These observations show that polyamine accumulation and growth are not always coupled.

Cytokinins↗
PubMed1977

Putrescine-sensitive (artifactual) and insensitive (biosynthetic) S-adenosyl-L-methionine decarboxylase activities of Lathyrus sativus seedlings.

The crude extracts of 3-day-old etiolated seedlings of Lathyrus sativus contained two S-adenosyl-L-methionine decarboxylase activities. The artifactual putrescine-dependent activity was due to the H2O2 generated by diamine oxidase (EC 1.4.3.6) of this plant system and was inhibited by catalase. This observation was confirmed by using an electrophoretically and immunologically homogeneous preparation of L. sativus diamine oxidase. In the presence of putrescine, diamine oxidase, in addition to S-adenosylmethionine, decarboxylated L-lysine, L-arginine, L-ornithine, L-methionine and L-glutamic acid to varying degrees. The decarboxylation was not metal-ion dependent. The biosynthetic S-adenosylmethionine decarboxylase (EC 4.1.1.21) was detected after removing diamine oxidase specifically from the crude extracts by employing an immunoaffinity column. This Mg2+-dependent decarboxylase was not stimulated by putrescine or inhibited by catalase. The enzyme activity was inhibited by semicarbazide, 4-bromo-3-hydroxybenzoylamine dihydrogen phosphate and methylglyoxal-bis (guanylhydrazone). It was largely localized in the shoots of the etiolated seedlings and was purified 40-fold by employing a p-hydroxymercuribenzoate/AH-Sepharose affinity column, which also separated the decarboxylase activity from spermidine synthase.

Adenosylmethionine Decarboxylase↗
PubMedDate not supplied

Bispecific antibodies as novel bioconjugates.

Bispecific antibodies are unique macromolecular heterobifunctional cross-linkers with two different binding specificities within a single molecule. As ideal bioconjugates, they can specifically glue any two different molecules together without the need for chemical conjugation. With this unique feature, they have immense potential in biological and immunological fields. Their applications range from immunohistochemistry, immunoassays, radioimmunodiagnosis, radioimmunotherapy, and immunotherapy. Recently, a new second generation of bispecific molecules, bispecific single chain Fv and diabodies, has been produced by DNA recombinant technology. They can be considered as the ultimate magic bullets for in vivo applications. They may theoretically improve tumor or pathogen targeting and minimize side effects, eventually replacing the full-length bispecific antibodies. Emphasizing on developmental methodology and clinical applications of bispecific antibodies, this review gives a bird's-eye view of these unique bioconjugates.

Animals↗