[Gastroenterological nurses' seminar in Sweden].
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Biomedical subjects
H Rossi
Publications and source records attributed to H Rossi.
Norepinephrine in treatment of ocular hypertension and glaucoma.
Norepinephrine (4%) as free base produced a significant fall in intraocular pressure and resistance to outflow. This effect was sustained for up to 20 weeks. No significant difference could be shown between the effect of 2%, 3%, and 4% norepinephrine on the aquious humor dynamics. The effect on pressure and facility was shown in eyes with ocular hypertension and with glaucoma. An additive effect was observed after use of norepinephrine with pilocarpine in the treatment of glaucoma. Crossover studies between epinephrine borate 1% and norepinephrine borate 4% revealed no significant difference. Like epinephrine, norepinephrine produces a conjunctival hyperemia in many patients. However, there is an absence of tachycardia after use of norepinephrine, and one person in this study showed an allergic reaction to epinephrine that cleared promptly and completely when norepinephrine was substituted.
Aged↗
The potential of californium-252 in radiotherapy. Preclinical measurements in physics and radiobiology.
Californium-252 is a man-made radionuclide (half-life 2-65 years) which emits a mixture of neutrons and gamma rays. It is used in radiotherapy as an alternative to radium and extends the potential benefits of neutrons to interstitial and intracavitary applications. Gamma rays account for a variable proportion of the dose (30 to 50 per cent), depending on the source filtration and the distance from the source. Dosimetry is complicated by this mixture of neutrons and gamma rays. However, measurements with paired ion-chambers, together with Monte-Carlo calculations, have produced dosimetric data that are adequate for clinical use. Many determinations of the oxygen enhancement ratio (OER) have been reported. At the low dose-rates characteristic of interstitial implants, the OER is about 1-5. This is essentially the figure for fast neutrons alone, since at very low dose-rates the contribution of the gamma rays to the biological effect is negligible. As the dose increases, there is a corresponding rise in the OER because the gamma ray contribution can no longer be ignored. The OER is likely to be about 1-8 if 252Cf is used in intracavity treatments and 2-0 if used in "acute" exposures in devices such as the Cathetron. The relative biological effectivenesss (RBE) varies with dose-rate, and with the biological system used to measure it. Radiobiological experiments indicate that 6,000 rads of radium gamma rays in seven days is equivalent to 890 rads of 252Cf neutrons delivered in approximately the same overall time. This figure was suggested some years ago as an interim guide-line until sufficient clinical experience is accumulated.
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