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Biomedical subjects

S L Waters

Publications and source records attributed to S L Waters.

31 records · Page 2Linked to original sources
PubMed1977

The measurement of spleen perfusion in man: a non-invasive method using the ratio between Rubidium-81 and its decay product Krypton-81m.

A non-invasive method has been developed for measuring spleen perfusion in man. This involves recording the gamma-ray energy spectra over the spleen following the localisation of Rubidium-81 within the organ by injecting intravenously labelled heat denatured red cells. The spectra are analysed to provide the ratio of Rubidium-81 to its radioactive decay product Krypton-81 m. This ratio is dependent on the rate of perfusion through the organ. The difficulties encountered in applying this steady state method for monitoring tissue perfusion are illustrated and practical means for their solution presented. The results of applying this method to patients with various splenic disorders are presented and compared with those obtained by other workers using different monitoring techniques.

Humans↗
PubMed1977

Investigations into the use of 77Br labelled 5alpha-dihydrotestosterone for scanning the prostate.

The potential use of a potent androgen labelled with a gamma emitting radionuclide for scanning the prostate was investigated. 2alphabromo 5alpha-dihydrotestosterone was synthesized and subsequently labelled with 77Br. The distribution of this compound was studied in rat and human tissues. The maximum concentration of radioactivity in the rat prostate at 1-4 h following the injection was found to be between 0.5-0.8% of the injected dose per gram of the tissue. In the human however, that value was 0.002-0.003%. Considering the overall results it was concluded that this compound is not appropriate for scanning the prostate.

Animals↗
PubMed1976

The use of 123I labelled oestradiol in detecting the human prostate using a gamma camera.

123I labelled oestradiol was administered into patients with either benign hypertrophy or malignancy of the prostate, in order to detect the prostate. Using a gamma camera the results showed considerable radioactivity in the bladder-prostate region. The exact anatomical position of the prostate was determined by emptying the bladder and introducing 123I labelled sodium iodide into the balloon of the catheter already inserted in the bladder. The results demonstrated that the detected radioactivity in this region was in the bladder rather than the prostate. This conclusion was later confirmed by the presence of high level of the radioactivity in the urine and the extremely low concentration of the radioactivity in the prostate after the removal of the gland.

Estradiol↗
PubMed1976

The assay of iodine-123.

Compounds labeled with 123I are becoming more common in scintillation imaging due to the convenient combination of the 13.3-hr half-life and the 159-keV gamma radiation. Here attention is drawn to the particularly large summing effects observed when 123I is counted in a well counter. These could lead to errors in the assay of doses if the analyzer windows used are too narrow.

Iodine Radioisotopes↗
PubMedDate not supplied

Examination of the mechanisms of action of diverse cytoprotectants in renal cell death.

Glycine, strychnine, muscimol, allopregnanolone, and pregnenolone sulfate act in the late phase of renal cell injury, block Cl- influx and cell lysis induced by the mitochondrial inhibitor antimycin A, and promote the recovery of respiration and ion transport following hypoxia/reoxygenation. However, the mechanism of action of these compounds has not been completely elucidated. Recently, we have shown that calpains are critical mediators of renal cell death produced by diverse toxicants and that antimycin A exposure results in calpain translocation from the cytosol to the membrane fraction that is temporally associated with Cl- influx and precedes cell death/lysis. The current study examined the effects of a group of diverse cytoprotectants on calpain activity and determined if calpain inhibition plays a role in the cytoprotection produced by these compounds. The cytoprotection produced by glycine, strychnine, muscimol, allopregnanolone, and pregnenolone sulfate in rabbit renal proximal tubules exposed to antimycin A was associated with the inhibition of antimycin A-induced calpain translocation. None of the cytoprotectants had a direct effect on calpain activity. All of the cytoprotectants decreased calcium-ionophore-induced cell death. Glycine, strychnine, and muscimol also blocked antimycin A mediated extracellular Ca2+ influx. These data suggest that the cytoprotective mechanism of action of glycine, strychnine, and muscimol involves the inhibition of antimycin A mediated extracellular Ca2+ influx as well as calpain translocation and associated Cl- influx. In contrast, the mechanism of action of the neurosteroids results only from the blockade of calpain translocation and associated Cl- influx.

Animals↗