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Biomedical subjects

R D Jones

Publications and source records attributed to R D Jones.

At least 199 records · Page 11Linked to original sources
PubMed1980

The effects of organophosphorus pesticides on estuarine ammonium oxidizers.

The effects of seven thiophosphorus pesticides and their degradation products on estuarine ammonium oxidizers were examined. Using an axenic, closed-culture, high cell density assay, the pesticides caused little inhibition of ammonium oxidation. However, the degradation product of methyl parathion, p-aminophenol, significantly inhibited ammonium oxidation levels as low as 0.01 mg/L. Estuarine sediments containing indigenous ammonium oxidizers were exposed to the pesticides over a 14-day period and activity of the ammonium oxidizers were inhibited after 14 days. Three pesticides were aged in estuarine sediments under aerobic, anaerobic, and microaerophilic conditions, and axenic cultures of ammonium oxidizers were exposed to the resulting metabolites. Ammonium oxidation was inhibited by 10% in the systems containing pesticides aged under aerobic and anaerobic conditions, whereas under microaerophilic conditions, 20% reduction in activity was observed. The data suggest that the parent compounds of the thiophosphorus pesticides have little effect on ammonium oxidation in estuarine sediments, but that certain metabolites which accumulate from the decomposition of these pesticides, especially in sediments under low O2 levels, may significantly reduce ammonium oxidation.

Ammonia↗
PubMed1979

A growth factor from spinal cord.

Mitogenic activity is present at a variety of sites in the central nervous system. A growth factor was purified from neonatal bovine spinal cord. It has a pI of 9.5-9.8 and a molecular weight of about 11,000 daltons. Spinal cord growth factor is a basic polypeptide that is inactivated by extremely acid or basic conditions. Its mobility on SDS polyacrylamide gels suggests that this factor is different from pituitary FGF and brain FGF-1.

Animals↗
PubMed1979

Sulfur base ligation to iron(II) and cobalt(II) porphyrins.

Equilibrium constants for the binding of sulfur bases to cobalt(II) porphyrins were measured in toluene solution by a spectrophotometric method. The order of decreasing binding strength of sulfur ligands to cobalt(II) porphyrins was found to be mercaptide ions >> thioethers > mercaptans. It is suggested that a similar stability order of these sulfur ligands should exist towards iron(II) porphyrins, but formation constants could be obtained only for the mercaptide ions.

Journal Article↗
PubMed1978

An in vivo method to evaluate the effect of materials upon arterial thrombosis.

An in vivo method to evaluate the effect of materials upon arterial thrombosis was developed that minimized the effect of surgical artifacts and provided a test which was critically sensitive to the surface properties of the materials. The procedure has general applicability to elastomers, either solvent cast or mold polymerized, and involves the implantation of segments of the test materials within canine femoral and carotid arteries. The sensitivity of this technique was demonstrated by comparing two surface preparations of a segmented polyurethane: as-cast and ion sputtered. There was a striking difference in the rate of thrombus development on as-cast polyurethane implants compared with sputtered polyurethane implants. After 1 hr. of implantation the surface of the as-cast polyurethane was covered with a monolayer of platelets and leukocytes, whereas thrombus development progressed more rapidly on the sputtered polyurethane surface and at 1 hr. it was covered with pillars of platelets and leukocytes with fibrin accumulation between pillars. The method was also useful for long-term studies, which showed that a thin layer of thrombus developed on both polyurethane surfaces and by 1 wk. after implantation the surfaces of the thrombi became endothelialized.

Animals↗
PubMed1976

Constructing cast crowns to fit existing removable partial denture clasps.

A step-by-step procedure has been presented for fabrication of a cast crown to fit an existing partial denture clasp. The procedure can be accomplished in two appointments, and the patient need not be subjected to the incovenience of being without the partial denture between office visits. It is an accurate and easy technique which gives uniform results and eliminates the need for remaking an adequate removable partial denture.

Crowns↗
PubMed1976

Congenital dislocation of the patella.

In 8 congenital patellar dislocations, in 7 patients, the patella was permanently and laterally dislocated, and irreducible or difficult to reduce. The patella usually was hypoplastic and showed absent facets. The intercondylar groove of the femur also was underdeveloped. In all but one patient, knee function was improved by a surgical procudure which involved lateral release of ptella, medial transpositon of patellar tendon, and plication of medial capsule or advancement of vastus medialis.

Cartilage, Articular↗