Biomedical subjects

J Liniecki

Publications and source records attributed to J Liniecki.

At least 19 recordsLinked to original sources

PubMed2003

A generic model for 11C labelled radiopharmaceuticals for imaging receptors in the human brain.

A large number of radiopharmaceuticals labelled with 11C (half-time 0.340 h) are being developed for positron emission tomographic studies of different types of receptor in the human brain. For most of these agents, the available biokinetic data are insufficient to construct realistic compound-specific biokinetic models for calculating the internal radiation dose delivered to persons undergoing investigation. A generic model for brain receptor substances that predicts the internal dose with sufficient accuracy for general radiation protection purposes has, therefore, been developed. Biokinetic data for 13 11C-radiopharmaceuticals used clinically for imaging different brain receptors indicate that, despite differences in chemical structure, their uptake and retention in the human brain and other tissues are broadly similar. The proposed model assumes instantaneous deposition of 5% of the injected radioactivity in the brain, with the remaining radioactivity being rapidly and uniformly distributed throughout all other tissues. Elimination from all tissues is assumed to occur with a half-time of 2 h. It is further assumed that 75% of the injected 11C is excreted in the urine, and 25% via the gall bladder, with a half-time of 2 h. This model yields an effective dose of 4.5 x 10(-3) mSv MBq(-1), with doses of 3.2 x 10(-2), 1.7 x 10(-2), 8.7 x 10(-3), 5.2 x 10(-3), and 3.8 x 10(-3) mGy MBq(-1) to the urinary bladder, gall bladder, kidneys, brain and ovaries, respectively. These doses are well within the range of those reported using compound-specific models for the radiopharmaceutals studied.

Brain↗

PubMed2001

99mTc-HEPIDA plasma clearance as a diagnostic tool. Total plasma v. specific hepatic clearance.

BACKGROUND: (99m)Tc-HEPIDA total plasma clearance has been used for assessment of hepatic parenchyma damage. However, the radiopharmaceutical used is being partly cleared from plasma also by the urinary tract. As the share of the latter route in total elimination of the compound is not well known, the aim of the study was to investigate the percentage of (99m)Tc-HEPIDA eliminated by the kidneys and by the liver. MATERIAL AND METHODS: To this aim total plasma clearance of the compound and urinary part were determined by the methods employed here in 117 patients and in 16 healthy volunteers. The pure hepatic clearance was calculated as the difference between total plasma and the urinary clearance of (99m)Tc-HEPIDA. RESULTS: The urinary clearance in patients amounted from 2.6 to 78% of total clearance; in the healthy volunteers the corresponding range was from 8.6 to 28%. Pronounced spread of the urinary clearance (coefficient of variation = 35%) and lack of correlation between the urinary and total clearance make it necessary to take account of urinary elimination in each patient in whom reasonably accurate assessment of hepatic clearance is required. CONCLUSION: Further studies on the diagnostic efficacy of pure hepatic clearance and its change with age in healthy patients appear necessary.

Journal Article↗

PubMed1999

[Problems in the evaluation of miners' exposure to radon in Poland in view of international organizations recommendations and European Union directives].

Exposure of miners to natural radiation in which radon-222 plays the major role has been studied in Poland since the end of the nineteen sixties. The work environment measurements and personal monitoring methods have been developed for monitoring the exposure. A quite wide range of doses resulting from big differences in radon concentrations in mines is characteristic of miners' exposure. It was estimated that about 16% of miners received doses above 5 mSv per year. This group of miners should be provided with individual dosymentry. In this paper methodological and legal aspects of the situation in mines are analysed. A large number of Polish recommendations and legal regulations must be changed in order to harmonise them with the directives of the European Union.

Europe↗

PubMed1999

Pharmacokinetic characteristics of 99mTc-Ethylene-l-dicysteine (99mTc-EC).

BACKGROUND: Ethylenedicysteine-99mTc (99mTc-EC) has been more and more commonly applied in dynamic studies as well as for clearance determinations. However, it was necessary to investigate in detail the pharmacokinetic characteristics of the radiopharmaceutical which may be important for its applicability in assessment of renal function. RESULTS: Kidney images obtained from renoscintigraphy are characterised by excellent quality without visualisation of the organs adjacent to kidneys (liver, spleen). Renoscintigraphic curves demonstrate typical shapes with TMAX and T1/2 values not differing from the corresponding values obtained for other radiopharmaceuticals (99mTc-MAG3, 131I-OIH). In plasma, 99mTc-EC binds with proteins to a considerably lesser degree (c. 1/3) than 131I-OIH (c. 2/3), or 99mTc-MAG3 (> 9/10). No binding of 99mTc-EC with erythrocytes has been demonstrated, whereas 131I-OIH attaches to or penetrates the red blood cells (10-12%). 99mTc-EC is quickly excreted from the organism: 40 min after i.v. injection up to 70% of the administered radiopharmaceutical is found in urine, and at 1 and 1.5 h after the administration 80% and 95%, respectively. The distribution of 99mTc-EC in the organism can be described in a fully satisfactory way by means of an open two-compartment model, which allows this model to be used for clearance determinations. Comparison of the values of renal plasma clearance without collection of urine with the values determined by means of measurement of activity excreted with urine and mean blood concentration over a finite time interval leads to the conclusion that extrarenal plasma clearance of this compound (via the liver?) is negligible and amounts to c. 17 ml/min (5-6% of the total). The obtained correlation between clearance values for 99mTc-EC and 131I-OIH supports the contention that extrarenal excretion rate of 99mTc-EC (through the liver and bile ducts) is lower than the corresponding rates of either 131I-OIH or 99mTc-MAG3. A very close correlation between clearance values for 99mTc-EC and ERPF (131I-OIH clearance) and between their extraction constants (r = 0.91 and 0.92, respectively), allows for the introduction of 99mTc-EC to the assessment of renal function instead of 131I-OIH. Effective dose to the patient from unit activity of 99mTc-EC is comparable with that resulting from administration of other radiopharmaceuticals labelled with 99mTc.

Journal Article↗

PubMed1995

Quantitative assessment of technetium-99m methoxyisobutylisonitrile planar perfusion heart studies: application of multivariate analysis to patient classification.

A quantified evaluation of planar cardiac perfusion scintigrams (the objective of the study), obtained using technetium-99m methoxyisobutylisonitrile (MIBI) was performed on the basis of an analysis of circumferential profile curves, representing the perfusion as seen in three typical projections. The analysis involved the curves obtained both at rest and after stress, and was based on a comparison of their shape (trend) with the normal trend (normative evaluation). The latter was obtained by means of an original method of iterative fitting of individual curves into the database. The base consisted of curves recorded in 53 patients (separately in males and females) with normal perfusion of the left ventricle (group I, the reference group). A group of 90 patients suspected of having coronary artery disease (group II) was subdivided into two subgroups on the basis of coronary arteriography: (a) those with and (b) those without critical stenosis of at least one artery. Profile curves characterising the LV perfusion were obtained at rest and after stress. Defects of perfusion were quantified by comparison of individual curves with the normal trends. By means of multivariate analysis it was demonstrated that vectors of mean values characterising the scintigraphically assessed defects of LV perfusion in the two subgroups of group II differed very significantly (P < 10(-5)). Applying methods of discriminant analysis, a classification of patients from group II was performed into those with probable defects of perfusion and those free of such defects. The sensitivity, specificity and accuracy of diagnosis of coronary ischaemia, based on quantified planar 99mTc-MIBI scintigraphy, reached 86%, 87% and 87%, respectively.

Adult↗

PubMed1995

Diagnostic value of 169Yb-cis-dichlorodimethionine platinum scintigraphy in patients with malignant lymphomas.

Ytterbium-169 (169Yb) cis-dichlorodimethionine platinum (169Yb-PtCl2Meth2) is a new agent of low toxicity with an affinity for neoplastic tumours. The aim of this study was to assess the diagnostic value of 169Yb-PtCl2Meth2 scintigraphy in patients with malignant lymphomas. 169Yb-PtCl2Meth2 scintigraphy was performed in 67 patients with histologically proven malignant lymphoma. Liver, spleen, kidney and bone were among the normal tissues that showed uptake of the radiopharmaceutical. The compound is excreted in the main through the urinary tract. There was no significant activity in the bowels. For evaluation of the images, uptake of activity was scored according to a 5-point scale. In total, 888 sites were evaluated. The sensitivity, specificity and accuracy of lymphoma detection for the body as a whole was 80, 89 and 87%, respectively. The best results were obtained for the head (sensitivity 91%, specificity 89%), neck (sensitivity 84%, specificity 90%) and chest (sensitivity 82%, specificity 84%). In the sub-diaphragmatic region, sensitivity and specificity were 76 and 84%, respectively. Scintigraphy with 169Yb-PtCl2Meth2 appears to be a sensitive, non-invasive procedure for the staging of malignant lymphomas. The results suggest that it is possible to monitor the therapy of malignant lymphoma by means of 169Yb-PtCl2Meth2 scanning.

Abdominal Neoplasms↗

PubMed1995

Experimental toxic liver damage and hepatic plasma clearance of 99mTc-mebrofenin (iminodiacetate derivative). III. Chronic CCl4-induced liver damage with eventual cirrhosis in rabbits.

Chronic damage to liver parenchyma was induced in rabbits by the long-term administration of carbon tetrachloride. The animals were serially sacrificed 3, 6 and 9 months after the start of intoxication, and examined histopathologically. The biological response was qualitatively assessed from results of histological studies, and measured utilizing series of typical biochemical indices of liver damage, 99mTc-mebrofenin (an-IDA-derivative) plasma clearance by the liver, and quantified indices of uptake and organ transfer of the compound. It was found that the plasma clearance and transfer parameters show association with chronic liver damage. The reduction of plasma 99mTc-mebrofenin clearance in intoxicated rabbits was also associated with changes in the biochemical indices of liver function and damage.

Aniline Compounds↗

PubMed1994

Usefulness of 99Tcm-N,N'-ethylene-1-dicysteine complex for dynamic kidney investigations.

To assess the usefulness of the 99Tcm-N,N'-ethylene-1-dicysteine (99Tcm-EC) complex for examination of kidney function, dynamic kidney scintigraphy with 99Tcm-EC and clearance determinations were performed. During renoscintigraphy the kidney images were of superb quality, with overlying organs (liver, spleen) not visualized. Renograms showed typical shapes, their Tmax and T1/2 values being unsignificantly different from the values obtained with other radiopharmaceuticals used in renoscintigraphy (mercaptoacetyl triglycine, hippuran). Very strict correlations were found between values of 99Tcm-EC and 131I-iodohippurate (OIH) clearances (r = 0.91) and excretion rate constants (r = 0.92) for both radiopharmaceuticals. The correlation enabled the formulation of an equation by which effective renal plasma flow (ERPF) could be established from 99Tcm-EC clearance: ERPFOIH = 1.245 x ClEC + 51.52. On the basis of this equation a lower boundary of the normal 99Tcm-EC clearance was established; it amounts to 300 ml min-1 1.73 m-2.

Animals↗

PubMed1993

Experimental toxic liver damage and hepatic plasma clearance of 99mTc-mebrofenin (iminodiacetate derivative). II. Recovery from the acute, CCl4-induced liver damage.

Liver parenchyma damage was induced in rabbits by the administration of carbon tetrachloride. The animals were serially sacrificed 3, 10, 17 and 31 days post intoxication and examined morphometrically for the extent of necrosis, steatosis and balloon degeneration of hepatocytes. Biochemical indices of the liver damage were studied as well as hepatic clearance of blood plasma from Tc-99m complex of an IDA derivative Tc99m complex (99mTc-mebrofenin--99mTc-MBF) and its uptake and liver transfer characterizing parameters. It was found that toxic effects of CCl4 were conspicuous up to 10 days after administration of carbon tetrachloride. In that period elevated activity of AspAT, ALAT, GGTP and elevated cholesterol and triglycerides were found in the plasma. As in the first paper of this series of works there has been a highly significant statistical association between the Tc-MBF plasma clearance, the uptake and liver transfer of the compound and parenchyma damage in the organ.

Aniline Compounds↗

PubMed1993

Experimental toxic liver damage and hepatic plasma clearance of 99mTc-mebrofenin (iminodiacetate derivative). I. Early, acute CCl4-induced liver damage in rabbits.

Liver damage was induced in rabbits by graded doses of carbon tetrachloride. The damage was assessed by means of quantitative morphometry using necrosis and steatosis of the parenchyma as end points. Biological response was measured utilizing a series of typical biochemical indices of liver damage as well as plasma clearance by the liver 99mTc-mebrofenin (an IDA derivative) and quantified indices of uptake and organ transfer of the compound. No correlation was found between the CCl4 dose and its effect (i.e. degree of necrosis and steatosis of liver). However, a very strong negative correlation was found between the degree of necrosis in individual animals and value of the clearance. The extent of the damage was positively correlated with liver transfer rate of 99mTc-MBF. Plasma activity of ALAT, TG, GGTP and AspAT were higher in the poisoned animals, however, only increments of activity of GGTP, ALAT and LDH showed statistically significant correlation with the individually assessed damage (necrosis).

Aniline Compounds↗

PubMed1992

[Diagnostic value of planar perfusion scintigraphy of the heart using Technetium Tc 99m with methoxy-isobutylisonitrile (MIBI)].

99mTc-MIBI (2 methoxy -isobutylisonitrile) belongs to the new generation of radiopharmaceuticals used for studies of myocardial perfusion. Particularly convenient characteristics of the compound prompted numerous studies of its usefulness for scintigraphic diagnostics of coronary artery disease and myocardial heart infarct (detection, localization, size). In the present paper the diagnostic utility of planar heart scintigraphy with 99mTc MIBI is assessed, the compound had been prepared in the Department of Nuclear Medicine, Medical University of Lódź. The scope of the study included detection of stress induced ischaemia and of permanent perfusion defects, treated as post infarct scars in myocardium. The study was made on 109 patients (78 males, 31 females; age 32-68 years). The first group comprised 56 patients with suspected or diagnosed coronary artery disease, however, without history of previous heart infarct. Results of stress and rest scintigraphy were juxtaposed with those of coronarography, which served as a reference method. In 25 patients the latter revealed critical (greater than 70%) stricture of 1 or 2 coronary arteries. In 31 patients of this group the vessels were either of normal appearance or only marginally stricture. Sensitivity, specificity and accuracy of the scintigraphy in diagnosis of ischaemia due to critical narrowing of coronary arteries amounted to 80, 84 and 82 per cent, respectively. Localisation of perfusion defects was adequate in 20 out of 31 vessels (64 per cent). The second group of patients included 53 individuals with previous heart infarct (25 and 11 had a transmural and nontransmural infarct of the anterior wall, respectively; in 12 and 5 a transmural and nontransmural infarct of the inferior wall was diagnosed, accordingly).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1989

Effects of vinyl chloride on liver function of exposed workers, evaluated by measurements of plasma clearance of the 99mTc-N-2,4-dimethylacetanilido-iminodiacetate complex.

In 77 males exposed occupationally to vinyl chloride (VC), the plasma clearance (Cl) of 99mTc-N(2,4-dimethylacetanilido)iminodiacetate ('HEPIDA' complex) was determined. The results were juxtaposed with a scaled assessment of liver parenchyma performance based upon clinical examination and a series of biochemical tests. Detection of the diagnosable damage of liver parenchyma by means of the reduced clearance was sensitive (90%) at the reasonable specificity of 74%. Probability of exclusion of liver damage in patients with the clearance above 240 ml min-1 1.73 m-2 amounted to 92%. There was a significant correlation between degree of exposure to VC and the frequency of low clearance values. It appears that the periodic determination of the 99mTc-HEPIDA clearance in workers exposed to VC allows the assessment of incipient liver damage and signals the need for prophylactic measures.

Adult↗

PubMed1989

Mortality risk coefficients for radiation-induced cancer at high doses and dose-rates, and extrapolation to the low dose domain.

Risk coefficients for life-long excessive mortality due to radiation-induced cancers are presented, as derived in 1988 by the U.N. Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), principally on the basis of follow-up from A-bomb survivors in Japan, over the period from 1950 through 1985. The data are based on the new, revised dosimetry (DS 86) in the two cities, and reflect the effects of high and intermediate doses of basically low LET radiation delivered instantaneously. The author presents arguments relevant to the extrapolation of the risk to the low dose (dose rate) domain, as outlined by UNSCEAR in its 1986, and the NCRP (USA) in its 1980, (no 64), reports. The arguments are based on models and dose-response relationships for radiation action, derived from data on cellular radiobiology, animal experiments on radiation-induced cancers and life shortening, as well as the available limited human epidemiological evidence. The available information points to the lower effectiveness of sparsely ionizing radiation at low doses and low dose-rates, as compared with that observed for high, acutely delivered doses. The possible range of the reduction values (DREF) is presented. For high LET radiations, the evidence is less extensive and sometimes contradictory; however, it does not point to a reduction of the effectiveness at low doses/dose-rates, relative to the high dose domain. Practical consequences of these facts are considered.

Adult↗

PubMed1987

Estimate of lifetime dose in persons exposed occupationally to x rays in Poland.

Estimates are presented of the magnitude of doses incurred over prolonged periods by individuals exposed occupationally to x rays. The results of individual monitoring in Poland from 1966 to 1978 formed the basis of the estimates. Probability distributions of receiving a certain 40-y lifetime x-ray dose were assigned to several subgroups monitored by applying the method of Markov's chains. Independently, by linear extrapolation of the measured increment rate, the mean life doses were estimated for a number of subgroups. The results seem to demonstrate that occupational exposure to x rays in the subgroups studied is slightly diversified, and its current level is of the same order as the exposure due to background radiation.

Faculty↗

PubMed1987

Radiation doses from 51Cr-bleomycin.

Extensive studies were made of long-term whole-body retention, plasma concentration, urinary excretion and organ retention of 51Cr in rats after intravenous injection of 51Cr-bleomycin. A similar but less extensive investigation was performed on rabbits, and whole-body retention, plasma concentration and urinary excretion was also followed in patients given 51Cr-bleomycin for diagnostic purposes. From an analysis of the collected information it followed that integrated whole-body and organ retention, corrected for radioactive decay, is similar in man and rabbit, and higher by a factor of about 2 in the rat. Doses to organs and whole body in man were calculated using the MIRD methodology and assuming conservatively that the kinetic data derived in rats are applicable to man. The organ and whole-body MIRD doses after 51Cr-bleomycin administration are comparable to those after 67Ga-citrate and the effective dose equivalent from a diagnostic amount of 740 MBq of the 51Cr complex amounts to about 6 mSv. However, the subcellular distribution in the liver of 51Cr, administered in the form of 51Cr-bleomycin, indicated a significant enrichment of 51Cr in the nuclei and in the DNA over mean concentrations in the liver cells. Also, the quality factor for Auger electrons, emitted by 51Cr, when assessed on the basis of the Q vs. LET relationship, as proposed by ICRP, was substantially higher than unity. Doses calculated for cell nuclei and the DNA in the liver cells were higher than the cell-averaged values by a factor 2.5 and 5, respectively, and the corresponding dose equivalents by a factor of 9 and 24. The effective dose equivalent, estimated on the basis of dose equivalents to cell nuclei and the DNA, amounted to 33 and 83 mSv per examination (740 MBq of 51Cr-bleomycin), respectively.

Animals↗

PubMed1986

Comparison in rabbits of chole-scintigraphic properties of several 99mTc-IDA derivatives.

Pathways and kinetics of excretion were compared to four 99mTc-IDA derivatives in healthy rabbits of both sexes. Assessment of differences between the compounds was based upon: plasma clearance, characteristics of time-activity curves measured scintigraphically over the liver (time of the peak Tmax; time for decline of activity to half the peak value-T50%), and hepatocytic mean transit time (MTT) as derived after deconvolution of the hepatic time-activity curve. Hepatocyte transit time was short and similar to 99mTc-complexes of Mebrofenin, 2,4-diethyl IDA (HEPIDA) and 3-iodo-2,6-diethylphenylcarbamoylmethyliminodiacetic acid (JODIDA); it was evidently longer for 99mTc-p-butyl-IDA (BIDA). 99mTc-HEPIDA displayed significant urinary elimination; the remaining three compounds were excreted practically completely via the biliary route. It is concluded that optimal parameters were displayed by 99mTc-Mebrofenin and 99mTc-JODIDA.

Aniline Compounds↗

PubMed1985

51Cr-bleomycin in the diagnosis of tumours of the chest.

51Cr-bleomycin was used for the scintigraphic diagnosis of primary and secondary tumours of the thorax. The study was based on observations in 104 patients. The scintigraphy was performed using a gamma camera coupled to an on-line computer. Active lesions were scored using a semiquantitative scale of scores 0 to 5. Images were subdivided into 222 regions considered. In 72 of these, the presence of disease was diagnosed (64 malignant, 8 non-malignant) and 150 regions were classified as free from disease. At the decision threshold of score 2, over-all sensitivity and specificity of the scintigraphic detection of malignant tumours amounted to 97 and 79%, respectively. Inflammatory changes displayed some detectable accumulation of 51Cr-bleomycin but scores attributed to these lesions did not exceed the value of 2.

Adolescent↗

PubMed1984

Uptake of main fractions of labelled bleomycin by solid Ehrlich ascites tumours in mice.

Concentrations were studied of 58Co in the solid Ehrlich ascites tumour, blood, muscle and bone of male Swiss mice administered as complexed with total bleomycin commercially available and its isolated fractions A2, B2, demethyl A2, A1, A5, B4 and bleomycinic acid. The tumour/non-tumour ratios were determined 24 hrs after injection of the complexes. The ratios for fraction A2, B2 and total bleomycin were very close to each other. The remaining fractions showed lower values of the ratios. These results suggest that it is unlikely that any of the fractions studied are superior to total labelled bleomycin with respect to tumour scintigraphy.

Animals↗