Voltage-activated and spontaneous Cl(-)-channel activity in cultured human melanoma cell-line A2058.

Voltage-activated and spontaneous chloride-channel activity was studied in melanoma cell-line A2058 by patch-clamp technique. Whole-cell and inside-out patch recordings carried out with leak subtraction show voltage-activated chloride-conductance. In addition, a large leak-type conductance typical of epithelial cells was found in whole-cell experiments. This current was carried mostly by chloride-ions but also a leak-type potassium conductance was found showing KCl fluxes to be possible. Cell-attached and inside-out patch recordings showed at least two types of spontaneous chloride-channel activity. Bursting, flickering-type channels were found only in cell-attached recordings. That led to the conclusion that some intracellular factors are needed for that kind of activity. A second spontaneous, 30 pS chloride-channel with slow kinetics was found both in cell-attached and inside-out patch configuration. A voltage-activated chloride-channel found had a conductance of approximately 25 pS. In our experiments these channels did not need external calcium for activation. Voltage ramp recordings in cell-attached configuration gives the intracellular chloride concentration of 163 mM on the basis of chloride reversal potential (extracellular 146 mM in our experiments). Intracellular chloride concentration thus seems to be maintained slightly higher than the extracellular one.

The spin-lattice relaxation time in the blood of healthy subjects and patients with malignant blood disease.

To establish which constituents of blood influence the NMR relaxation time T1 of water protons in malignant blood diseases, 55 blood samples were studied (20 from healthy donors and 35 from patients with leukaemia, myelofibrosis and multiple myeloma). Relaxation time measurements were performed at 19.8 MHz resonance frequency and at a temperature of 33 +/- 1 degree C. There is a significant elevation of T1 over the normal level in whole blood, packed cells, and plasma of patients with blood disease. The relaxation rate R1 (= 1/T1) depends very strongly on the ratio of dry solids to water, which is in accordance with the three-state fast-exchange relaxation model.

Chromosome aberrations in lymphocytes of nurses handling cytostatic agents.

In an evaluation of the possible chromosome damage caused by cytostatic agents 11 nurses with long-term exposure to such agents were studied. Five laboratory workers and 11 hospital clerks served as referents. The number of chromosomally aberrant lymphocytes was significantly higher in the group of nurses than in the group of laboratory workers or hospital clerks. The number of chromosome-type breaks was increased significantly among the nurses as compared to the reference groups. There was no significant difference in the number of chromatid-type breaks between the groups. The observed increase in chromosome-type aberrations may have been due to long-term occupational exposure to cytostatic agents.

NMR relaxation times in NMR imaging.

The T1 and T2 relaxation times of pathological tissues can be different from those of normal tissues. It seems that the NMR relaxation times are of great significance in tissue characterization and tumour localization with help of NMR imaging.

Cytogenetic effects of cardioangiography on blood lymphocytes in children and in vitro effects of contrast medium and low dose radiation.

Structural chromosome aberrations were analysed in the peripheral blood lymphocytes of 15 children, aged 1 to 13 years, before, immediately after, 24 hours after and 6 to 8 months after cardioangiographic examination. Statistically significant increases were only demonstrated in the frequency of gaps (p less than 0.05) and, consequently, in the frequency of aberrant cells (p less than 0.05) immediately after cardioangiography. Most of the chromosome damage clearly disappeared within 24 hours. In addition, whole blood cultures were exposed in vitro to low dose radiation, a contrast medium, and radiation together with the contrast medium. No statistically significant differences could be observed in the chromosome aberration frequencies. It was concluded that the modern radiographic procedure, which uses very low radiation doses and less contrast medium, does not cause a consistent, permanent increase of chromosomal damage in the lymphocytes of children. However, the situation may be different if the child undergoes many radiographic examinations or the radiation doses are high.

Microdosimetric measurements of ionization by some radioisotopes.

Microdosimetry has been a fast growing field in dosimetry during the last years. We have measured and calculated microdosimetric quantities which are important in correlation between the energy deposited in microscopic volumes and the biological effect. We have measured the energy distribution spectra in volumes with diameters of 1 and 2 mum and calculated the dose mean of specific energy and the mean event number per unit absorbed dose for the radioisotopes: 60Co, 137Cs, 99Tcm, 125J and the beta emitter 90Sr.

Microdosimetry and the measurement of 45 MeV betatron radiation.

Different radiation spectra of a 45 MeV betatron have been measured with a microdosimetric system. The possibilities of microdosimetry in the research on radiation biology have been discussed.

Nuclear magnetic relaxation in the cell.

The authors have measured proton relaxation times of gynecological cancer. T1 and T2 of human tumours are longer than proton relaxation times of corresponding normal tissues. Radiotherapy changes also proton relaxation times T1 and T2 in tissue.

Radiation gonad doses received by children in intravenous urography and micturition cysto-urethrography.

Measurements of gonad doses in intravenous urography (IVU) was performed on 47 children and in micturition cysto-urethrography (MCU) on 57 children. Ionization chamber dosimeters were placed rectally in girls and fixed on the scrotum in boys. Gonad dose ranged from 27 mrad to 201 mrad in girls and from 7 mrad to 112 mrad in boys during IVU; during MCU doses ranged from 53 mrad to 1900 mrad in girls and form 24 mrad to 309 mrad in boys. Risk of leukemia and genetic risk were calculated.

Methods for measuring the modulation transfer function of gamma camera systems.

The MTFs of three different gamma camera systems have been measured using two methods. In one method a step function was used as the object and the calculations were made by means of a pocket calculator. This method has been compared with a conventional line source method, where a computer is needed in performing the calculations. The methods give the same results with a fairly good accuracy. Both of the methods are well suited to a regular control of the condition and functioning of a gamma camera, provided that the camera is connected to a data-processing system so that the profile curves measured can be converted into the digital form.

CRE calculations for different combined radiation therapy schemes of uterine cervical carcinoma.

The CRE concept is not applicable to the assessment of the effect of combined radiotherapy when external and intracavitary radiations are given alternately and with unequal doses. Because of the numerous recurrences, we had to change our radiation treatment schemes for carcinoma cervix uteri, and we attempted, on a theoretical basis, to acquire the same biological effects as Joslin with his own method. In the comparison of different schemes we used as slightly modified approximate CRE and the "nominal dose" presented by Kellerer. In this paper we have presented the treatment schemes we used and the methods for calculating the biological effect in combined treatments. Moreover, we have examined the applicability and compatibility of the above methods in comparing the effects of different combined radiation treatment schemes.

Residual activity of Tc-generators.

Owing to contamination by long-lived radio-isotopes, the residual activity of an old 99Mo-99mTc generator may be large enough to prevent its disposal. The long-lived impurities of one generator were determined by energy spectrum and half-life measurements. In this generator 46Sc, 51Cr, 60 Co, 92mNb, 95Nb and 124Sb nuclides were found. Only the half-life of 60Co exceeds 3 months, thus a moderately long storage of the generator reduces the activity, and its disposal is then safe.

Renography in the foetal and newborn lamb.

Hippuran renography indicates kidney function as reflected in a substance handled mainly by the tubules. The working conditions of the kidneys undergo a fundamental change at birth with the cessation of placenta circulation, and these organs become responsible for waste elimination. 131I-hippuran renography was performed on foetal and newborn lambs using a gamma camera and a computer. The intervals of the maximum- and half-time renal activity were determined. These decreased by a half from mean foetal value of Tm=7 mi and T12=19 min in 1 to 1.5 days and reached the full-grown level in 2 to 5 weeks. No sudden change occurred as a result of the first breath.