Search PubMed⌕ Search

Biomedical subjects

C Riley

Publications and source records attributed to C Riley.

69 records · Page 4Linked to original sources
PubMed1977

Effect of structure on the excretion of steroidal acids in human urine and their potential colorimetric assay as 17-oxogenic steroids.

Following the oral administration of tritiated coricosterone, cortisol, deoxycorticosterone and progesterone to human subjects, 14.9%, 12.8%, 3.4% and 2.1% of the dose was recovered in the acidic metabolite fraction of 48 h urines after conventional hydrolysis and solvent partition. Neutral and acidic 17-oxogenic steroids (17-OGS) excreted in 24 h urines were also measured with the Zimmermann color reaction. The acidic 17-IGS accounted for 14.1%, 16.4% and 12.1% of the fractionated 17-OGS in the urines of normal and pregnant females and normal males respectively. From structural considerations, it was concluded that only 17-hydroxylated steroidal acids, with a 20-hydroxy-21-oic acid side chain and derived predominantly from cortisol, would be estimated as 17-OGS after oxidation with sodium periodate. 17-Dexy steroidal acids resemble the neutral 17-deoxycorticosteroids in undergoing side chain oxication to 17-aldehydes which do not form Zimmermann chromogens. The excretion of both neutral and acidic 17-OGS was suppressible with dexamethasone administration.

17-Ketosteroids↗
PubMedDate not supplied

Acetaldehyde-modified lysozyme function: its potential implication in the promotion of infection in alcoholics.

Incubation of lysozyme with acetaldehyde (0.44 M) at room temperature for 2 h produces a 62% inhibition of enzymic activity. Because the active site cleft contains tryptophyls, asparagine, glutamine, and an arginine residue, and because acetaldehyde reacts with indoles, amides, and guanidines, it is suggested that these sites are likely ones for alkylation. The epsilon-amino groups of lysines on the surface of the molecule are also susceptible to covalent modification. Total acetylation of lysozyme has been reported to inactivate the enzyme. These results suggest the possibility that inactivation of a fraction of the lysozyme activity by acetaldehyde may decrease the effectiveness of the enzyme in chronic alcoholics, thereby leading to an increased potential for susceptibility to bacterial infection.

Acetaldehyde↗
PubMedDate not supplied

Development of a fish in vitro cell culture model to investigate oxidative stress and its modulation by dietary vitamin E.

When cultured in Dulbecco's minimal essential medium the established epithelioma papulosum cyprini cell line from carp was found to be vitamin E-deficient due to the very low level of vitamin E in the medium and the foetal calf serum used as supplement. The toxicity of oxidative stressors to this cell line was evaluated by means of the neutral red cytotoxicity assay and it was found that an organic hydroperoxide, t-butylhydroperoxide was extremely cytotoxic and that the redox-cycling agents diquat and menadione were less toxic. When grown under vitamin E supplementation (25 microM), the toxicity of these chemicals was reduced by at least an order of magnitude in concentration demonstrating the protective effect of vitamin E. These data show the importance of vitamin E status for interpretation of in vitro and in vivo data and that this in vitro system is useful for mechanistic studies.

Animals↗
PubMedDate not supplied

A low-cost colorimeter.

A need for a colorimeter with low capital and maintenance costs has been suggested for countries with foreign exchange problems and no local medical instrumentation industry. This paper puts forward a design for such a device based on a domestic light-bulb, photographic filters and photovoltaic cells. The principle of the design is the use of a balancing technique involving twin light paths for test solution and reference solution and an electronic bridge circuit. It is shown that proper selection of the components will allow the cost objectives to be met and also provide acceptable linearity, precision, accuracy and repeatability.

Colorimetry↗
PubMedDate not supplied

Additional extrarenal abnormalities seen in Tc-99m DTPA renal flow study.

During 99mTc-DTPA renal flow studies, extrarenal abnormalities have been found to include aortic abnormalities (aneurysm, ectasia, thrombosis, and abruptly decreased flow), splenic abnormalities (enlarged, small, or absent spleen), hepatic arterialization, and very slow circulation. In addition to the above abnormal findings, we add three more extrarenal pathologies that may be concomitantly found with renal flow study: pleural effusion(s), malignancy of the abdomen, and anemia and/or skeletal metastases.

Abdominal Neoplasms↗