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PubMedDate not supplied

[Cobalt radioisotope teletherapy of patients with metastases to the brain].

The results are presented of palliative telecobaltotherapy in patients with metastases to the brain. The patients received a dose of 30 Gy in 10 fractions during 2 weeks. Clinical improvement was achieved in 28 out of 33 treated patients (85%). The survival time after the completion of radiotherapy was from 1 to 15 months, mean 5 months.

Adult↗
PubMed1988

Measurements of transfer coefficients for 137Cs, 60Co, 54Mn, 22Na, 131I and 95mTc from feed into milk and beef.

The transfer in cattle of the radionuclides 137Cs, 60Co, 54Mn, 22Na, 131I and 95mTc was studied experimentally to determine transfer coefficients from feed to milk and meat. Special interest was kept on normal feeding and maintenance conditions used in Germany. The radionuclides were incorporated into fodder plants through root uptake and thus available in a chemical form resulting from the contamination of agricultural soil. This permitted realistic simulation of the soil-plant-animal food chain. The equilibrium transfer coefficients for milk were calculated to be 22Na: 0.016 +/- 0.002 d/l, 60Co: less than or equal to 0.0002 d/l, 54Mn: less than or equal to 0.0005 d/l, and 137Cs: 0.0022 +/- 0.0002 d/l. The equilibrium transfer coefficients for meat were calculated to be 22Na: 0.01 +/- 0.002 d/kg, 60Co: less than or equal to 0.00013 d/kg, 54Mn: less than or equal to 0.0005 d/kg, and 137Cs: 0.0062 +/- 0.0006 d/kg. A single dose of 131I was orally administered three times in the chemical form of iodide. Models were applied to obtain parameters for a quantitative description of the iodine metabolism. The equilibrium transfer factor for 131I in this chemical form to milk was calculated to be 0.009 +/- 0.0014 d/l. For 95mTc only an upper limit of the transfer factor of 1.7.10(-4) d/l could be estimated because of the small amount of radioactivity available.

Animal Feed↗
PubMed1988

Effect of microbial biomass reduction by gamma-irradiation on the sorption of 137Cs, 85Sr, 139Ce, 57Co, 109Cd, 65Zn, 103Ru, 95mTc, I by soils.

Six soils, two Sphagnum peat samples and a clay mineral were irradiated with 40 and 80 kGy (4 and 8 Mrad) from a 60Co source. As a result the microbial biomass, determined separately for each sample, decreased considerably. Depending on the radionuclide, the sorption, as characterised by the distribution coefficient, decreased, increased or remained unchanged. The effect of the irradiation on the sorption of the radionuclides depended, in general, also on the type of the sample, especially whether well humified soils, (e.g. crop soils), poorly humified samples (Sphagnum peat, O-horizon from woodland), or a clay mineral was employed. The data reveal that irradiation produces, besides sterilization, also other effects in soils, which can change their sorption properties.

Adsorption↗
PubMed1991

Evaluation of portal-systemic shunting in rats from mesenteric and splenic beds.

In rats with partial portal vein ligation, 95 +/- 0.9% of the splenic blood flow is shunted from the portal to the systemic circulation when an intrasplenic injection of microspheres is used to determine the degree of shunting. Despite this magnitude of portal-systemic shunting, several biochemical and endocrine consequences of portal-systemic shunting occur at levels below what is expected for the degree of shunting found. In an effort to resolve these discordant findings, shunting from both the splenic and the mesenteric bed was studied in anesthetized portal hypertensive rats with various degrees and/or duration of portal vein stenosis. The shunting from the mesenteric bed averaged 66.7 +/- 29.9% (range 5.1-99.1%) and was influenced both by the degree and duration of portal vein stenosis. In contrast, shunting from the splenic bed averaged 97.3 +/- 4.0% (range 79-99.9%) and demonstrated no variation between groups determined by the degree of portal vein stenosis. The shunting from the splenic bed was consistently greater than that found from the mesenteric bed. Mesenteric but not splenic shunting correlated with serum bile acid levels. Mesenteric shunting was related inversely to the weight-adjusted liver mass and to serum testosterone levels. Based upon these data obtained in portal hypertensive rats, it is concluded that splenic injections of microspheres overestimate portal-systemic shunting. In contrast, mesenteric injections of microspheres yield values for shunting that correlate well with independently determined biochemical and endocrine consequences of shunting. These observations support the validity of the mesenteric shunting measurements obtained.

Animals↗
PubMed1986

Gastric emptying and gastrointestinal absorption of alcohol ingested with a meal.

We have measured, by an intubation method, gastric evacuation and gastrointestinal absorption of alcohol ingested with a meal in seven healthy nonalcoholic subjects. A homogenized meal containing [14C]PEG and ethanol (1 g/kg body wt) was given intragastrically while saline containing [57CO]vitamin B12 was perfused into the duodenum. Of the ingested alcohol, 39.4 +/- 4.1% was absorbed through the stomach wall during the first postprandial hour and 73.2 +/- 4.2% during the total postcibal period, whereas only 24 +/- 3% was absorbed during the same time in the duodenum. Thus alcohol ingested with a meal is mainly and rapidly absorbed in the stomach; the contribution of the small intestine below the angle of Treitz to alcohol absorption is negligible.

Adult↗
PubMed1982

Effect of ionizing irradiation on the physiological activity of cyclic adenosine monophosphate on smooth muscle preparations.

The effect of ionizing irradiation on the physiological activity of cyclic adenosine monophosphate (cAMP) in smooth muscle preparations from frog lung was studied. cAMP, given as dibutyryl salt (dib-cAMP) inhibited the radiation induced contractions of the muscle in a manner similar to the action of theophylline. In vitro irradiation of dib-cAMP resulted in an alteration of the chemical structure of this substance, i.e., formation of monobutyryl-cAMP and further derivatives as well as a decomposition of the purine structure. There was also a loss of the relaxing activity of irradiated cAMP on the muscle tone of frog lung preparations. The physiologically measured inactivation of dib-cAMP was far more pronounced than the chemical alteration. An inhibitory effect of the reaction products is postulated.

Animals↗
PubMed1991

Radiolytic reduction of protein and nonprotein disulfides in the presence of formate: a chain reaction.

We have reported recently that the disulfide groups in bovine serum albumin can be reduced by a radiolytic chain reaction which occurs in deoxygenated solutions containing formate ions. This reaction, which involves the reduction of disulfide groups by hydrated electrons and carbon dioxide radical anions, has now been studied in greater detail and compared with an analogous reaction in small, disulfide containing molecules over a range of pH values and substrate concentrations. A two-step reaction is proposed to account for the reduction of disulfides in reactions which can have chain lengths of 20 or more. Thiols produced by the disulfide reduction are stable to the conditions of the reaction. For example, a biological assay showed that the integrity of glutathione was maintained even at radiation doses much larger than those required to achieve complete reduction of glutathione disulfide. It was found that the extent of disulfide reduction could easily be controlled by varying the radiation dose delivered to the solutions. Radiolytic reduction is a very useful way of reducing protein and low molecular weight disulfides without the use of excess quantities of reagents such as dithiothreitol. In many cases, the reaction solutions could be used directly for subsequent reactions and this may be of considerable value in modifying the structure of hormones, enzymes, membrane receptors, and other disulfide containing proteins. If ammonium formate is used, freeze drying is an effective way to remove the formate salt, should this be required.

Cesium Radioisotopes↗
PubMed1987

Comparison of 59Fe3+ uptake in vitro and in vivo by mouse duodenum.

Initial rates of 59Fe3+ uptake by mouse duodenal fragments (in vitro) and tied-off duodenal segments (in vivo) have been characterised for control and hypoxic animals. 59Fe3+ uptake by duodenal fragments was rapid, selective and dependent on medium Fe3+-nitrilotriacetate concentration. Most of the 59Fe3+ uptake (70-75%) occurred via the mucosal route and was dependent on the metabolic state of the tissue. Mucosal uptake showed an adaptive increase following exposure of animals to 3 days hypoxia; the enhancement was due to a 2-3-fold increase in Vmax app, without any significant changes in the Km app. Studies of upper small intestine transit times showed a mean residence time of 4-5 min for 59Fe-labelled mouse chow, emphasising the importance of initial uptake measurements. Time courses for in vivo total mucosal uptake exhibited linearity over a wide variety of absorption rates after correction for the permeation by intact metal-chelate complex. The corrected uptake showed a hyperbolic dependence on medium Fe3+-nitrilotriacetate concentration. Kinetic studies revealed a 2-3-fold increase in total mucosal uptake in hypoxia. Mucosa-to-carcass transfer of 59Fe was also markedly increased by chronic hypoxia. The in vitro system exhibits similar qualitative and quantitative kinetics for Fe3+ transport via the mucosal membrane to those obtained in vivo. The results observed in vitro are thus valid and provide a convenient method for further studies on Fe3+ transport in animals and in man.

Animals↗