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Biomedical subjects

R K Gupta

Publications and source records attributed to R K Gupta.

At least 721 records · Page 40Linked to original sources
PubMed1979

The detection and clinical significance of antibodies to tumor-associated antigens in patients with renal cell carcinoma.

Antibodies against renal carcinoma cells were detected by a microcomplement fixation assay in the sera of 94 per cent of 75 patients with recently resected, localized or metastatic disease, and in 20 per cent of normal controls. Absorption of sera with pooled normal kidney cells abrogated reactivity against normal kidney cells but did not decrease reactivity significantly against the renal carcinoma cells. Analyses of sequential serum samples revealed that after nephrectomy in 9 of 10 patients free of tumor but a high risk for recurrence antibody levels decreased or disappeared by 1 year. However, these levels remained elevated in 2 patients who subsequently were found to have occult persistent tumor. Antibody titers in patients with metastatic renal cell carcinoma declined as the disease progressed. Patients with persistently elevated titers had the longest survival. Although the antibodies detected by this assay may not be specific for renal cell carcinoma, their detection may be of clinical significance with regard to the prognosis of the disease.

Adenocarcinoma↗
PubMed1979

Isolation and immunochemical characterization of antibodies from the sera of cancer patients which are reactive against human melanoma cell membranes by affinity chromatography.

Immunoglobulins were isolated by affinity chromatography from sera of two patients with melanoma, one with sarcoma, and one with carcinoma. The affinity columns were prepared by covalently linking the membrane-rich fraction of biopsied melanoma cells to cyanogen bromide-activated agarose beads. The membrane-rich fractions were prepared by two methods: (a) hypotonic cell lysis, and (b) homogenization and differential centrifugation. Melanoma sera were autologous to melanoma membrane preparations. The isolated immunoglobulins showed immunoreactivity against antigens prepared from melanoma, sarcoma, and carcinoma cells by complement fixation but not against antigens prepared from normal human liver and lung tissues. Absorption of the isolated immunoglobulins with rabbit anti-human immunoglobulin immunobeads resulted in complete elimination of the complement-fixing antibody titer in one instance, whereas reduction occurred in other samples. Similar absorption with rabbit anti-human immunoglobulin M immunobeads resulted in reduction, but not complete elimination, of the antibody titers against target tumor cell preparations. These results suggest the presence of immunoreactive immunoglobulin G in all immunoglobulins and immunoglobulin M in some. Absorption of the isolated immunoglobulins with cultured sarcoma cells reduced but did not completely abolish antibody activity against autologous or allogeneic melanoma target antigen, whereas it did completely abolish activity against sarcoma target antigen. However, absorption with cultured allogeneic melanoma cells abolished the antibody activity against melanoma as well as sarcoma target antigens. The antibody titers of the isolated immunoglobulins were not affected by absorption with cultured lymphoblastoid cells. Since cultured melanoma and sarcoma cells were known to contain oncofetal antigen(s), these results suggest that the isolated immunoglobulins from cancer sera by melanoma membrane affinity chromatography were of at least two specificities: (a) antioncofetal; and (b) antitumor associated. The former group may be comprised of antibody to cross-reactive antigens associated with different histological types of tumors. However, it was apparent that a portion of the antibody activity was against common tumor-associated antigen(s). These results provide further evidence for the presence of common antigen(s) associated with biopsy specimens of human malignant melanoma.

Adult↗
PubMed1979

Double-antibody method and the protein-A-bearing Staphylococcus aureus cells method compared for separating bound and free antigen in radioimmunoassay.

We compared the protein-A-bearing Staphylococcus aureus immunoadsorbent to the double-antibody precipitation method for separating bound and free radiolabeled antigen in a radioimmunoassay. With human albumin (antigen) and rabbit anti-human albumin (antibody) as a model, our results indicate that formalin-fixed, heat-killed S. aureus cells could be substituted for the double-antibody precipitation method. Ease of preparation and high adsorption capacity of protein-A-bearing S. aureus for most mammalian IgG make this method economical and time saving.

Antibodies↗
PubMed1978

The determination of the free magnesium level in the human red blood cell by 31P NMR.

The phosphorus NMR spectra of intracellular ATP in glycolyzing human red blood cells maintained at 37 degrees C in an atmosphere containing 5% CO2 have been obtained and quantitated under completely aerobic and anaerobic conditions. A comparison of the separation between the alphaP and betaP resonances and the alpha-beta and beta-gamma 31P spin-spin coupling constants of intracellular ATP with appropriate controls directly reveals that 84 +/- 4% and 78 +/- 4% of the total ATP are complexed to Mg2+ in the aerobic and anaerobic states of the cell, respectively. This determination does not differentiate between molecules free in solution and those bound to hemoglobin due to rapid exchange on the NMR time scale of free and complexed ATP. From these data and the prior knowledge of the interactions of various phosphorylated metabolites with hemoglobin and Mg2+, the intracellular concentration of free Mg2+ is determined to be 0.25 +/- 0.07 mM in the aerobic and 0.67 +/- 0.15 mM in the anaerobic state in a sample of normal red blood cells. Knowledge of free Mg2+ permitted a calculation of the distribution of ATP, ADP, glycerate-2,3-P2, and hemoglobin among their free and complexed forms. The results indicate that approximately 40% of the glycerate-2,3-P2 and ATP are complexed to hemoglobin even in aerobic cells and approximately 90% and approximately 60%, respectively, in completely anaerobic cells. The level of free ATP decreases 3-fold anaerobically whereas the MgATP changes very little. The intracellular level of MgADP increases about 2-fold upon deoxygenation. Since the Mg2+ in the red cell is largely complexed, the 3-fold increase in free Mg2+ under fully anaerobic conditions would significantly affect the rates of enzymatic reactions.

Adenine Nucleotides↗
PubMed1978

Phytobezoars.

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Adult↗
PubMed1978

Uptake of metabolites by germinating blastospores of Histoplasma capsulatum.

The uptake of radioactive L-leucine, L-glutamic acid, and guanine was monitored during blastospore germination of Histoplasma capsulatum. Blastospores of H. capsulatum, grown in Salvin's medium at 37 degrees C for 48 h and shifted to 23 degrees C, germinated within 24 h. Metabolite uptake was faster in mycelial cells at 23 degrees C than it was in yeast cells at 37 degrees C. During the yeast to mold transition, the initial rate of uptake was first markedly depressed and then increased and achieved a level characteristic of the mycelial phase of growth. Estimates of macromolecular synthesis occurring during transitional morphological events might be influenced by these differences in the rate of uptake.

Culture Media↗