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Biomedical subjects

K Kiviniitty

Publications and source records attributed to K Kiviniitty.

At least 19 recordsLinked to original sources
PubMed1995

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.

Cell Membrane↗
PubMed1992

Proton nuclear magnetic resonance lineshape studies on human blood plasma lipids from newborn infants, healthy adults, and adults with tumors.

The usefulness of proton NMR spectroscopy of human blood plasma for cancer research has been extensively studied in recent years. Two main starting points have been offered by Fossel et al. (N. Engl. J. Med. 315, 1369 (1986)) and Mountford et al. (FEBS Lett. 203, 164 (1986)). In this work the experimental proton NMR spectra of blood plasma were analyzed with the aid of the multivariate lineshape fitting method. An appropriate model structure, in terms of the various lipoprotein (VLDL, LDL, and HDL) signals, for the methylene region was used. Neonates, healthy adults, and adults with nonmalignant and malignant tumors were studied. The linewidth of the methylene region was found to be linearly dependent on the relative concentrations of the lipoproteins. The correlation coefficient was -0.89 (P less than 0.001) for VLDL and 0.88 (P less than 0.001) for HDL. A correlation between VLDL concentration and age, 0.76 (P less than 0.001), was also established. VLDL was modeled using two components. The half-linewidth of the lower field component was slightly elevated for the adults with large metastases. This might be in association with the fucose-containing proteolipid complex detected earlier in cancer cells or in sera of cancer patients. Some signals of this complex may fall in the same region of the spectra. The spectra for the neonates were indicated to be totally different from the adults. This and other related questions were explained by means of the model parameters and the relative concentrations of the lipoproteins VLDL, LDL, and HDL. The presented technique can be used as a rapid research tool for figuring out the relative concentrations of the lipoproteins in blood plasma and explaining the reasons behind the changes in the spectra.

Adult↗
PubMed1991

A lineshape fitting model for 1H NMR spectra of human blood plasma.

A lineshape fitting model was constructed for classifying the overlapping information in the 1H NMR spectrum of human blood plasma. A reliable assignment of the overlapping fatty acid (-CH2-)n and -CH3 resonances of the various lipoproteins (VLDL, very low density lipoprotein; LDL, low density lipoprotein; HDL high density lipoprotein) is introduced, and for the first time detailed characteristics (chemical shifts, half linewidths, and relative intensities) of the individual lipoprotein components were obtained directly from the whole plasma spectrum. This was achieved by combining the constructed lineshape fitting model and the proper 400 MHz proton NMR measurements from blood plasma of a healthy donor, from fractions of the different lipoproteins, and from plasma samples in which the lipoprotein fractions were separately added. The results suggest fair promise of future applications of the rapid and easy NMR analysis of lipoprotein distribution in various research and clinical situations.

Chemical Fractionation↗
PubMed1989

1H NMR studies on human plasma lipids from newborn infants, healthy adults, and adults with tumors.

The 1H NMR spectra of the lipid region of human plasma from healthy adults, neonates, and patients with malignant and nonmalignant tumors have been recorded on a JNM-GX400 FT spectrometer operating at 399.6 MHz for protons. The chemical shifts of methylene and methyl groups of plasma lipids were measured with respect to the higher field component of the methyl proton resonance of the lactate molecule. The results show that there are changes in the chemical shifts of the methylene proton resonances among the plasma from healthy adults, adults with tumors, and neonates. The shifts observed in the case of cancer patients and neonates are in the direction opposite to the shift measured from the plasma of healthy adults. Thus, the observed changes cannot be explained by the activity in the cell proliferation of tissues which is high in the cases of both healthy neonates and patients with malignant tumors, but they most probably reflect the different lipoprotein compositions of neonates, healthy adults, and adults with tumors.

Adult↗
PubMed1984

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.

Adult↗
PubMed1984

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.

Body Water↗
PubMed1982

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.

Blood Physiological Phenomena↗
PubMed1981

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.

Radioactive Waste↗
PubMed1981

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.

Brachytherapy↗
PubMed1980

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.

Gamma Rays↗
PubMed1979

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.

Adolescent↗
PubMed1979

Accuracy of computerized radiation treatment planning.

The accuracy of computerized dose planning depends essentially on the computer program. The quickest and simplest way to assess the accuracy of a commercial program is to compare the results of the computer calculations with measured values. The present report deals with the accuracy of the RADPLAN dose planning program in different situations easy to control. The test methods are also applicable to other corresponding systems.

Computers↗
PubMed1979

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.

Cesium Radioisotopes↗
PubMed1978

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.

Animals↗