PubMed Health⌕ Search

Biomedical subjects

K Bajaj

Publications and source records attributed to K Bajaj.

8 recordsLinked to original sources
PubMed2001

Direct antigen capture by soluble scFv antibodies. A method for detection, characterization, and determination of affinity.

For ease of detection, soluble forms of phage-displayed scFv antibodies are usually expressed with a tag, e.g., c-myc or His (Histidine). The binding is then assayed by a monoclonal antibody to the tag. In this article, we describe the use of biotinylated antigen for detecting soluble scFv antibodies without utilizing the peptide tag detection system. The scFv antibodies were against the oncoplacental antigen heat-stable alkaline phosphatase (HSAP). The method essentially consisted of either reverse Western or antigen capture enzyme-linked immunosorbent assay (ELISA). In the reverse Western, periplasmic extract was electrophoresed, and binding to biotinylated antigen was detected by the detection system based on streptavidin-horseradish peroxidase. The antigen capture ELISA utilized the binding of periplasmic extract to a polystyrene plate. We have also demonstrated the use of antigen capture ELISA for studying specificity and affinity of the selected clones. Although these techniques have been developed for antibodies to HSAP, they have general utility for phage expression systems without a peptide tag.

Alkaline Phosphatase↗
PubMed2000

Mutations in the HIV type 1 integrase of patients receiving long-term dideoxynucleoside therapy do not confer resistance to zidovudine.

Metabolites of AZT can inhibit HIV-1 integrase in vitro (Mazumder A, et al., Proc Natl Acad Sci USA 1994;91:5771-5775). To determine if long-term dideoxynucleoside therapy can lead to the emergence of HIV-1 AZT-resistant variants containing mutations in the integrase, we have sequenced the proviral DNA encoding the HIV-1 integrase of nine HIV-1-infected patients at different time points during treatment. Four of the nine patients developed mutations during the course of treatment. Although most mutations occurred at nonconserved amino acids, one patient developed a mutation at codon (R166T), a residue that is conserved among all integrases from known HIV-1 isolates. This mutation was introduced in the recombinant HIV-1 integrase protein to determine if it could confer resistance to AZT in vitro. We show that the R166T integrase mutant is still proficient at carrying 3'-processing and 3' end-joining but that the enzyme is not resistant to AZT-TP. Our results suggest that it is unlikely that integrase inhibition contributes to the antiviral activity of AZT.

Amino Acid Sequence↗
PubMed1997

Magnetic bead enzyme-linked immunosorbent assay (ELISA) detects antigen-specific binding by phage-displayed scFv antibodies that are not detected with conventional ELISA.

An efficient means for the detection of antigen-specific binding by phage-displayed antibodies would facilitate the selection of such phage, especially from libraries with large repertoires of V-genes. We report the development and characterization of a magnetic bead phage ELISA which detects antigen binding phage which could not be detected by conventional ELISA. We were attempting to select phage binding to the oncodevelopmental antigen, heat-stable alkaline phosphatase (HSAP). Although there was an obvious enrichment in the phage titers after successive rounds of selection, we were unable to detect antigen-binding phage by ELISA on a plastic surface. However, ELISA with a suspension of superparamagnetic particles covalently conjugated to HSAP effectively identified antigen-binding phage after the fourth round of selection. This method could also detect antigen-specific binding of individual phage clones. Some of the phage clones bound to either amino- or carboxy-terminal-conjugated HSAP, perhaps reflecting the differences in the exposed epitopes. It is suggested that a sensitive method such as magnetic bead phage ELISA be tried before declaring a phage selection as unsuccessful or concluding that a phage clone does not bind antigen.

Alkaline Phosphatase↗
PubMed1984

Primary mediastinal seminoma.

Three new cases of primary mediastinal seminoma are presented, and 124 other cases in the literature are reviewed. These tumors primarily affect white males in the third decade. Chest pain is the most common symptom, but 20 per cent of the patients can be asymptomatic. Testicular atrophy occurred in only 7 patients. In one of these a testicular seminoma developed seven years after treatment of a primary mediastinal tumor. Supraclavicular adenopathies were found in 10 patients. Chest x-ray films typically show an anterior mediastinal noncalcified mass with smooth lobulated borders. Twenty-eight of 74 surgical resections attempted were successful; 13 of these received adjuvant irradiation. Of 64 cases in which radiation therapy was the primary mode of treatment, local failures occurred only in 7 cases. These tumors spread primarily by distant metastases. Theories of tumoral origin and patterns of spread are discussed. A dose of 3,000 rad in three weeks and 4,500 rad in four and one-half weeks to the mediastinum and supraclavicular areas is recommended for minimal and bulky disease. Primary mediastinal seminoma is as radiosensitive as its testicular counterpart.

Adult↗