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C McDevitt

Publications and source records attributed to C McDevitt.

4 recordsLinked to original sources
PubMed2000

Aerobic nitrate respiration in a nitrite-oxidising bioreactor.

The ability of heterotrophic bacteria in a nitrite-oxidising bioreactor to respire with nitrate as an electron acceptor was examined. Approximately 70% of 1000 heterotrophic isolates were able to express a nitrate reductase. A detailed survey of 15 isolates showed that five expressed the azide-insensitive nitrate reductase encoded by the napA gene. A two-round PCR amplification of the napA gene using degenerate PCR primers and DNA sequence analysis of these products confirmed the presence of this gene in the positive isolates. Partial 16S rDNA products and napA products were amplified from the biomass in the bioreactor and denaturing gradient gel electrophoresis of these products identified 21 distinct ribotypes and 12 distinct napA sequences. The results show that the ability to respire with nitrate as an electron acceptor under aerobic conditions is widespread among the heterotrophic population of this bioreactor.

Aerobiosis↗
PubMed1984

Identification of the Raji cell membrane-derived C1q inhibitor as a receptor for human C1q. Purification and immunochemical characterization.

We have shown previously that an activity which is capable of precipitating purified C1q and inhibiting some of the C1q-dependent biologic reactions could be solubilized from the membranes of both normal human peripheral B lymphocytes and a B cell-derived lymphoblastoid cell line (Raji), both of which are known to possess receptors for human C1q. In this report we present evidence that this membrane-associated C1q inhibitor is a chondroitinase-insensitive macromolecule and is the receptor for human C1q. The receptor was solubilized from membranes of Raji cells with Nonidet P-40 and purified to homogeneity using C1q-Sepharose 4B affinity chromatography. Equilibrium density gradient centrifugation analysis revealed that the complex could be resolved into a protein-rich, low density fraction and a carbohydrate-rich, high density fraction. The large hydrodynamic size, coupled with the high buoyant density, suggests that a proteoglycan is a constituent of the complex and indicates that the receptor might be a macromolecular complex of a proteoglycan portion noncovalently linked to a 60-70 kD glycoprotein. The glycoprotein moiety, in turn, consists of two or more identical (70,000 mol wt) polypeptide chains held together by disulfide bonds and constitutes the C1q receptor (C1qR). Sucrose density ultracentrifugation analysis showed that the isolated receptor sediments with an apparent rate of 4.2 S. Immunochemical analyses demonstrated that a typical preparation of the C1qR complex consists of approximately 23% uronic acid and approximately 21% galactosamine with a galactosamine-to-glucosamine ratio of 3.2. Binding of C1q to the receptor was found to be optimal at low ionic strength and neutral or near-neutral pH (7-7.4). The isolated receptor was found to inhibit C1q hemolytic function, abrogate C1q-dependent rosette formation, and block the C1q-dependent, cell-mediated cytotoxicity, all of which are activities mediated by the receptor.

Amino Acids↗
PubMed1977

An experimental model of osteoarthritis; early morphological and biochemical changes.

An experimental model of osteoarthritis resulting from laxity of the joint was induced in eighteen mature dogs (at least two years old) by sectioning the anterior cruciate ligament of the right knee (stifle) with a stab incision, the left knee providing a control. A sham operation was also performed in three other dogs, in which a stab incision was made but the ligament left intact. The dogs were killed at various intervals from one to forty-eight weeks later. Morphological changes in bone, cartilage, synovial membrane and joint capsule were examined in all the joints and biochemical changes in the cartilage of three dogs killed after two, eight, and sixteen weeks. All the changes resulting from the operation progressed with time and became indistinguishable from those found in three dogs with natural osteoarthritis of the knee. There were no changes in the joints which had sham operations. As the time of onset is known, this experimental model in a larger species enables a study to be made of the biochemical as well as the morphological changes in the early stages of osteoarthritis.

Animals↗