Biomedical subjects

T Sambandam

Publications and source records attributed to T Sambandam.

5 recordsLinked to original sources

PubMed1998

Ligation of CR1 attenuates Fc receptor-mediated myeloperoxidase release and HOCl production by neutrophils.

Surface adherent immunoglobulins are potent stimuli for inducing neutrophil release of myeloperoxidase and production of hypochlorous acid (HOCl), an oxidant that promotes activity of neutrophil proteases. Opsonization of surface adherent IgG (SAIgG) by complement results in attenuation of these responses, despite augmenting neutrophil production of superoxide and release of specific granule enzymes. The role of complement receptor ligation in modulating Fc receptor-triggered myeloperoxidase release and HOCl production by neutrophils was determined by incubating neutrophils with SAIgG in the presence of complement receptor ligating antibody reagents. Ligation of CR1 by F(ab')2 derived from CR1 specific monoclonal antibody (mAb 543) resulted in significant attenuation of surface-associated IgG (SAIgG)-induced release of myeloperoxidase and HOCl production but did not result in attenuation of SAIgG-induced superoxide or hydrogen peroxide production; ligation of CR1 by mAb 543 F(ab')2 also attenuated surface adherent IgA-induced myeloperoxidase release and HOCl production. HOCl production was not significantly attenuated when neutrophils were activated with SAIgG in the presence of surface adherent C1q or when CR3 was ligated by F(ab')2 derived from mAb having specificity for the CD11b (mAb M1/70) or CD18 (mAb TS1) subunits of CR3. These results indicate that ligation of CR1 on neutrophils by C3b fixed to IgG may alter signal transduction events linking ligation of neutrophil Fc receptors to cellular events required for release of myeloperoxidase and generation of HOCl.

Antibodies, Monoclonal↗

PubMed1993

Purification and properties of calmodulin from Phymatotrichum omnivorum.

Mycelia of Phymatotrichum omnivorum obtained at 10 day intervals during 10 to 50 days of growth were used for isolating calmodulin, and studying its effect on glycogen synthase, phosphorylase, phosphorylase kinase, cyclic AMP phosphodiesterase and Ca++ATPase. Glycogen synthase was inhibited until the 30th day by calmodulin, whereas calmodulin obtained from the 40th day stimulated glycogen synthase activity and the 50th day sample had no effect. cAMP phosphodiesterase and Ca++ATPase of P. omnivorum were stimulated by the respective calmodulin. Molecular weight of the purified fungal calmodulin was approximately 18 kD as revealed by sodium dodecyl sulphate gel electrophoresis. Trifluoperazine, dibucaine and lidocaine inhibited calmodulin activity and calmodulin activation of PDE, respectively.

Calcium-Transporting ATPases↗

PubMed1987

Purification and properties of phosphorylase from Phymatotrichum omnivorum.

The glycogen phosphorylase (EC 2.4.1.1) from the mycelium of Phymatotrichum omnivorum was purified by ammonium sulfate fractionation, gel filtration on Sephacryl S-200, and DEAE-cellulose ion-exchange chromatography to more than 100-fold. The purified enzyme was homogeneous; this was confirmed by polyacrylamide gel electrophoresis. Sodium dodecyl sulfate-gel electrophoresis indicated the relative molecular size of the enzyme was around 145,000. The approximate molecular weight by gel filtration was 116,000. The optimum pH of the enzyme was 7.0 and the enzyme was more specific for glycogen, with a Km value of 0.36 mg/ml. Nucleotides AMP, ADP, and ATP and compounds containing an "SH" group inhibited the enzyme activity. Diethyldithiocarbamate, EDTA, ethylene glycol bis(beta-aminoethyl ether)-N,N'-tetraacetic acid, and Cu2+ were the potent inhibitors of the glycogen phosphorylase activity, Ca2+, Cu2+, Co2+, and Fe2+ stimulated the enzyme activity. The enzyme preparation was stable at 4 degrees C during a period of 30 days.

Cations, Divalent↗

PubMed1986

Rapid diagnostic methods for aspergillosis.

Conventional laboratory methods are always unsatisfactory for the antemortem diagnosis of systemic mycoses, especially aspergillosis, in immunocompromised patients and those with acquired immune deficiency syndrome (AIDS), regardless of their age. There is increasing proof that aspergillosis is not limited to pulmonary, sinus or nasal regions. These facts, plus the high mortality rate, indicate a tremendous need for reliable and rapid methods of diagnosing this infection. Accordingly, refined techniques such as solid-phase radioimmunoassay (SPIRA), crossed-immunoelectrophoresis (CIE), crossed-radioimmunoelectrophoresis (CRIE), radioallergosorbent test (RAST), radioimmunoprecipitation assay (RIPA), paper radioimmunosorbent test (PRIST), computerized enzyme-linked immunosorbent assay (ELISA), biotin avidin enzyme-linked immunosorbent assay and gas-liquid chromatography (GLC) are being considered or used in clinical laboratories for diagnosing aspergillosis. The advantages and limitations of the RIA, ELISA and GLC methods are briefly discussed.

Antibodies, Fungal↗

PubMedDate not supplied

Specificity of the low density lipoprotein-glycosaminoglycan interaction.

There is ample documentation of the binding of chondroitin sulfate/dermatan sulfate proteoglycans to low density lipoprotein (LDL) both in vivo and in vitro. The interaction of these two species may be an early and important step in atherogenesis. Therefore, there is interest in defining the features of both molecules that are critical for their interaction. We employed a recently described competitive microassay that measures initial binding of proteoglycan to immobilized LDL. We confirmed the work of others that it is the apolipoprotein B component and, at least in part, a heparin-binding domain of LDL that are responsible for binding chondroitin sulfate/dermatan sulfate proteoglycans. The principal thrust of our study was concerned with the effects of a glycosaminoglycan's degree of sulfation on the binding to LDL. Initial experiments comparing dermatan sulfate and chondroitin sulfate proteoglycans indicated that the former was more efficient at binding LDL than the latter and that oversulfation, rather than chain length or iduronate content, was the preeminent feature involved. Additional binding studies with dermatan sulfate, chemically sulfated chondroitin-4-sulfate, and naturally occurring oversulfated chondroitin sulfates indicated that the degree of sulfation, not the position of sulfation, determined affinity for LDL. These results suggest that studies should be undertaken to determine whether oversulfated segments of glycosaminoglycans are especially involved in associations with LDL, leading to lipid accumulation, in the artery wall.

Amino Acid Sequence↗