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At least 163 records · Page 9Linked to original sources
PubMed1987

Measurement of the turnover of substrates of carbohydrate and protein metabolism using radioactive isotopes.

The rate of turnover of glucose or leucine can be measured in the steady state by using the radioactive isotopes 14C or 3H to 'trace' these metabolites. The tracer can either be injected or infused intravenously and its metabolism followed by monitoring levels of the tracer in blood, breath and urine. If a 14C labelled metabolite is used the oxidation rate may sometimes be determined by measuring the expiry rate of 14CO2. If the single injection technique is used the specific activity curve is fitted with an exponential function and the area under the curve calculated. Turnover rate is calculated from dose of isotope injected/area under the specific activity time curve. This technique can be used to construct a compartmental model to describe the behaviour of the metabolite. If the constant infusion technique is used, tracer is infused until a steady state level of tracer is achieved. This plateau is used to calculate the turnover of the metabolite from infusion rate of tracer/specific activity at steady state. While this latter method provides the simplest method of calculating turnover it cannot be used to model the data. The infusion technique can be used to measure changes in turnover and oxidation in the non-steady state. Tracer is infused to a steady state level and the system is then perturbed by for example, the infusion of a hormone. The changes in Ra and Rd can be determined either by using the Steele equation which assumes a single pool or by using compartmental analysis.

Amino Acids↗
PubMed1975

[Contribution to the early diagnosis of splenic rupture using radioactive isotopes (author's transl)].

Among the methods of early diagnosis of rupture and trauma of the spleen, fixation of radioactive isotopes is one of the most interesting. An experimental study in the dog of B.M.H.P. metabolism, using B.M.H.P. labelled with Hg-203 and its rate of elimination by the kidney, gives information on lesions of the spleen, in particular, sub-capsular rupture. Splenic trauma reduces the capacity of uptake of mercury by this organ. Excretion in the urine then increases very definitely. This simple and inoffensive method should be used in man.

Animals↗
PubMed1989

[Implantation of radioactive isotopes in intracranial tumors].

From may 1986 to July 1988 ten patients have been treated by interstitial implantation of radioactive isotopes using Yttrium 90 colloidal solution (9 cases) and Aurum 198 grains (1 case). There were 7 cystic out of 8 craniopharyngiomas, one malignant pituitary adenoma and one hemispheric Astrocytoma grade III-IV. In all but one patient the tumors were recurrent after one or more reductive or palliative operations. To external radiation undervent preoperatively two cases (one craniopharyngioma and one pituitary adenoma). Target volume was established by CT data and X-ray studies after stereotaxic injection of contrast medium (one case). Doses for intracystic irradiation were calculated using the Backlund's formula. The lowest activity was calculated to be 3.84 mCi, and the highest 12.9 mCi (m 6.8 mCi or 252 MBq). The delivered activity was 100-200 Gy of Y90 (m 140 Gy). The activity of Au198 was determined using the producers dosimetric tables. The radionuclide implantation was performed by stereotaxic techniques with Leksell's system in 5 patients. In 5 patients the surgical procedures were open: 3 osteoplastic supratentorial and 2 craniectomies for direct instillation of Y90 into the craniopharyngiomatous cavities spread to posterior fossa. Early short lasting side effects of endocavitary irradiation were observed in 5 patients (headache and somnolence; adynamy, pseudobulbar symptoms and rigor; insomnia and agressiveness; lack of orientation and increased mental irritability). The longest follow up was 26 months. The clinical response to intracystic instillation of Y90 was very favorable in 8 cases: 7 craniopharyngiomas and one pituitary adenoma. A satisfactory anatomical result with diminution or retraction of cystic cavities was evident in all cases. The more pronounced achievement of intracystic irradiation therapy in our series were the effects on stabilization or recuperation of vision and on improvement of visual field finding. The recovery of endocrine insufficiency was also noted. Two patients died: the 3-year old child, one year after implantation of Au198 grains in a huge calcified craniopharyngioma, and a woman, 67 old, twelve days after Y90 instillation to a hemispheric glioma grade III-IV.

Adolescent↗
PubMed1976

The treatment of chronic knee joint synovitis with radioactive isotops (author's transl).

On the basis of 77 cases report is given on the treatment of chronic synovitis of the knee in rheumatoid arthritis with radioactive isotopes. Gold 198 and Yttrium90 have been applicated. During an observation period up to 6 years a follow-up on 46 knee joints has been carried out. Very good and good results could be achieved in 50% of these cases.

Arthritis, Rheumatoid↗
PubMedDate not supplied

[The significance of the radioactive isotope potassium-40 for the normal development of the animal organism].

21-day-old rats subjected to nourishing by KCl (20-30 mg per day) without radioactive isotope 40K. Besides the decrease of 40K content in animal tissue (30-50%) a reducing of body weight was obtained. In the second set of experiments in the lead (9 cm thick) chamber with low (20 times) background radiation the trustworthy decrease of young mouse development was observed under the simultaneous reducing other components of background radiation (radon, products of its disintegration, gamma, beta radiation, cosmic radiation). Possible mechanisms of necessity of 40K natural concentration for the normal development of the animal organism are discussed.

Animals↗
PubMed1982

Assessment of glucose turnover in normal man with the use of a non-radioactive isotopically labelled preparation, [6,6-2H]glucose, as tracer.

1. Glucose kinetics were assessed in seven normal adult male subjects by an intravenous bolus technique with the use of a non-radioactive isotopically labelled preparation, [6,6-2H]glucose, as tracer. Tracer enrichment in plasma was assessed by gas chromatography-mass spectrometry. For comparison five subjects also received a simultaneous intravenous bolus of [6-3H]glucose and kinetics were assessed by conventional means. 2. Administration of [6,6-2H]glucose did not alter circulating glucose or insulin concentrations. 3. Glucose turnover, assessed by the use of [6,6-2H]glucose, was 11.4 (+/- 0.9) micromol min-1 kg-1 and 11.6 (+/- 0.5) micromol min-1 kg-1 with rate of glucose was 2.3 (+/- 0.3) ml min-1 kg-1 with both isotopically labelled tracers. Estimates of mean residence time, glucose pool and glucose space were also similar by each technique. 4. [6,6-2H]Glucose is therefore an effective tracer and allows investigation of glucose kinetics without administration of a radioactive label.

Adult↗
PubMed1991

[Radioactive isotope evaluation of apical seal of two types of thermoplasticized gutta-percha at high and low temperature].

The aim of this study was to evaluate the apical seal obtained using root canal filling techniques based on low and high temperature thermoplasticized gutta-percha, comparing them with the lateral condensation technique. The roots of thirty permanent upper canines and incisors were used, they were instrumented and obturated using each of the above techniques. The apical leakage was measured using a radioactive isotope and an external detection technique. No significant difference was found in the apical seal obtained by the three techniques.

Cuspid↗