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Biomedical subjects

D D Stuart

Publications and source records attributed to D D Stuart.

5 recordsLinked to original sources
PubMed1992

Methionine intake in rainbow trout (Oncorhynchus mykiss), relationship to cataract formation and the metabolism of methionine.

Young rainbow trout were given diets containing graded levels of methionine for 16 wk. Analysis of the weight gain and food efficiency data showed the methionine requirement to be not more than 0.76% of the diet (1.9% of dietary protein). Activities of regulatory enzymes of the transulfuration pathway, methionine adenosyltransferase and cystathionine synthase in trout liver were not altered by changes in methionine intake. Concentrations of free serine in liver and plasma of the trout were high at low levels of methionine intake but fell as dietary methionine increased. This implied decreased flux through cystathionine synthase at low methionine intakes. Large increases in liver and plasma taurine occurred at high methionine intakes, implying enhanced transulfuration activity. Liver ornithine decarboxylase activity was reduced at the lowest level of dietary methionine used but the activity of S-adenosylmethionine decarboxylase was unchanged. Eye lenses of the trout given these diets were examined by a scanning lens monitor. Analysis of focal length variability with this equipment demonstrated that, if abnormality of the lens is to be avoided, a higher concentration of dietary methionine (0.96% or 0.6% methionine + 0.36% cystine) is needed than that required to maximize growth.

Amino Acids↗
PubMed1991

UV-B radiation and the optical properties of cultured bovine lenses.

The effect of UV-B radiation on the crystalline lens was examined by subjecting bovine lenses in culture to varying low exposures at 300 nm. Lens optical quality was monitored on a long-term basis (to 1000 hrs.) with an automated scanning laser system that recorded both change in relative scatter and focal length across each lens. Data were collected for 20 lens positions at each scan. Radiant exposure levels consisted of 0.5, 0.25, 0.125, 0.06 and 0.03 Jcm-2. Twenty irradiated lenses were compared to twelve untreated controls. All of the irradiated lenses showed changes in scatter and focal length relative to the controls. Most (about 75%) of the treated lenses showed significant increases in scatter (200-400%) and focal length (10-20%) at 40 to 60 hours after exposure. A similar time frame for lens damage was noted by visual inspection. Exposure to UV-B at the above doses did not affect culture longevity.

Animals↗
PubMed1989

An improved radiolabeling technique of ivalon and its use for dynamic monitoring of complications during therapeutic transcatheter embolization.

Transcatheter embolization by Ivalon particles for treatment of arteriovenous malformations has been an accepted therapeutic technique for many years. We describe a new and efficient radiolabeling technique of Ivalon particles using [99mTc]sulfur colloid. Continuous and dynamic monitoring of injected radiolabeled Ivalon particles is made possible by viewing the persistence scope of a portable gamma camera whose head is positioned over the patient undergoing therapeutic embolization. Therefore, if inadvertent pulmonary embolism or reflux migration of radiolabeled Ivalon particles has occurred, the angiographer is immediately aware of this potentially serious or fatal complication and can take corrective action. We describe two patients, each with an arteriovenous malformation, who had therapeutic embolization with radiolabeled Ivalon particles, one resulting in reflux migration and the other resulting in inadvertent pulmonary embolism.

Adult↗