Modification of a two blood sample method used for measurement of GFR with 99mTc-DTPA

BACKGROUND Measurements of GFR may be performed with a slope/intercept method (S/I), using only two blood samples taken in strictly defined time points. The aim of the study was to modify this method in order to extend time intervals suitable for blood sampling. Modification was based on a variation of a Russel et al. model parameter, selection of time intervals suitable for blood sampling and assessment of uncertainty of calculated results. MATERIAL AND METHODS Archived values of GFR measurements of 169 patients with different renal function, from 5.5 to 179 mL/min, calculated with a multiple blood sample method were used. Concentrations of a radiopharmaceutical in consecutive minutes, from 60th to 190th after injection, were calculated theoretically, using archived parameters of biexponential functions describing a decrease in 99mTc-DTPA concentration in blood plasma with time. These values, together with injected activities, were treated as measurements and used for S/I clearance calculations. Next, values of S/I clearance were compared with the multiple blood sample method in order to calculate suitable values of exponent present in a Russel’s model, for every combination of two blood sampling time points. A model was considered accurately fitted to measured values when SEE ≤ 3.6 mL/min. Assessments of uncertainty of obtained results were based on law of error superposition, taking into account mean square prediction error and also errors introduced by pipetting, time measurement and stochastic radioactive decay. RESULTS The accepted criteria resulted in extension of time intervals suitable for blood sampling to: between 60 and 90 minutes after injection for the first sample and between 150 and 180 minutes for the second sample. Uncertainty of results was assessed as between 4 mL/min for GFR = 5–10 mL/min and 8 mL/min for GFR = 180 mL/min. CONCLUSIONS Time intervals accepted for blood sampling fully satisfy nuclear medicine staff and ensure proper determination of GFR. Uncertainty of results is entirely acceptable and for high GFR values even comparable with uncertainty of multi-sample measurements.BACKGROUND Measurements of GFR may be performed with a slope/intercept method (S/I), using only two blood samples taken in strictly defined time points. The aim of the study was to modify this method in order to extend time intervals suitable for blood sampling. Modification was based on a variation of a Russel et al. model parameter, selection of time intervals suitable for blood sampling and assessment of uncertainty of calculated results. MATERIAL AND METHODS Archived values of GFR measurements of 169 patients with different renal function, from 5.5 to 179 mL/min, calculated with a multiple blood sample method were used. Concentrations of a radiopharmaceutical in consecutive minutes, from 60th to 190th after injection, were calculated theoretically, using archived parameters of biexponential functions describing a decrease in 99mTc-DTPA concentration in blood plasma with time. These values, together with injected activities, were treated as measurements and used for S/I clearance calculations. Next, values of S/I clearance were compared with the multiple blood sample method in order to calculate suitable values of exponent present in a Russel’s model, for every combination of two blood sampling time points. A model was considered accurately fitted to measured values when SEE ≤ 3.6 mL/min. Assessments of uncertainty of obtained results were based on law of error superposition, taking into account mean square prediction error and also errors introduced by pipetting, time measurement and stochastic radioactive decay. RESULTS The accepted criteria resulted in extension of time intervals suitable for blood sampling to: between 60 and 90 minutes after injection for the first sample and between 150 and 180 minutes for the second sample. Uncertainty of results was assessed as between 4 mL/min for GFR = 5–10 mL/min and 8 mL/min for GFR = 180 mL/min. CONCLUSIONS Time intervals accepted for blood sampling fully satisfy nuclear medicine staff and ensure proper determination of GFR. Uncertainty of results is entirely acceptable and for high GFR values even comparable with uncertainty of multi-sample measurements

Comparison of 99mTc-HEPIDA and 99mTc-MBrIDA from the standpoint of hepatic clearance determination - preliminary communication

BACKGROUND. In order to evaluate the functional capacity of the liver by means of clearance determination, the derivative of iminodiacetic acid (99mTc-HEPIDA) has been used in recent decades. Because of recent problems with manufacturing and delivery of 99mTc-HEPIDA, an investigation was undertaken with the aim of testing whether a more widely available 99mTc-MBrIDA could be used for clearance determination and whether hepatic clearance measured with the use of this compound provides a similarly useful test of hepatic function. MATERIAL AND METHODS. Comparative investigations were performed in 73 patients of both sexes. The state of the efficiency of liver parenchyma was determined based on seven widely used biochemical tests, i.e. levels of: bilirubin, albumin, and gamma globulin; activity of AST, ALT, GGTP, and prothrombin index. The clearances of both radiopharmaceuticals, 99mTc-HEPIDA and 99mTc-MBrIDA, were determined by means of multisample technique. The results of determination were correlated among themselves and with the results of biochemical tests. The set of results of all estimations allowed a factorial analysis to be performed to find a common factor and to compute the values of factor loadings in particular tests. RESULTS. Obvious correlation between plasma and hepatic clearances of both radiopharmaceuticals was obtained and between plasma clearance of 99mTc-MBrIDA and hepatic clearance of 99mTc-HEPIDA. Correlation coefficients of 99mTc-MBrIDA clearance and the biochemical test results attained somewhat lower values than for 99mTc-HEPIDA clearance. Similarly, values of χ2 test of independence of 99mTc-MBrIDA clearances and test results were also less close than for 99mTc-HEPIDA clearances. Factorial analysis showed that common factor loading is greatest for hepatic clearance of 99mTc-HEPIDA; the values of two loadings of 99mTc-MBrIDA clearances are very close, but somewhat lower than those for 99mTc-HEPIDA. CONCLUSIONS. From the performed investigations it is possible to conclude that 99mTc-MBrIDA clearances may be used for the evaluation of liver parenchyma performance, even if the results may not be as certain as those obtained using 99mTc-HEPIDA

The problem of series of days without rainfall in a view of efficiency of agricultural output under climate change

Modelling future is key issue in studying CC impacts on agriculture across disciplines and scales. Improving models basing on empirical data coming from diverse micro regions let obtain synergic effects important in shaping food security. Especially, rainfall distribution is most important factor determining agricultural output.The amount of cereal yield depends on an occurrence of long series of days without rain during a growing season. Based on statistical analysis of daily totals it was found that in Central Poland the length of series of days without rainfall during growing season is 40 days. Statistical analysis was done for years 1971-2015. The data allowed finding empirical probability distribution of a length of the series. Average value of the length of series is 4.31 while SD is 4.41. Values of parameters of gamma distribution estimated by the likelihood method are: α=0.9542, β=4.5150. Value of the parameter α (shape parameter) suggests that distribution of the length of series is similar to exponential distribution.Goodness of fit test with gamma distribution was carried out using λ-Kolmogorov and χ2-Pearson tests. Both prove high conformity between empirical and gamma distribution. Based on assumption that gamma distribution can be accepted as distribution of the length of rainless series, further is determined distribution of the length of the longest series in n-element random sample. On the theory of distributions of asymptotic order statistics it is known that the random variable T(n) with appropriate normalization has asymptotic double exponential distribution. Based on that one can conclude that probability to occur 30-day rainless series or longer equals approx. to 0.48. This is useful in forecasting agricultural output depended on rainfall distribution

Mass and radius estimation for the neutron star in X-ray burster 4U 1820-30

We present a new method for determining masses and radii of neutron stars residing in thermo-nuclear X-ray burst sources. To illustrate this method we apply it to a burst from the source 4U 1820-30 recorded by the Rossi X-Ray Timing Explorer. Fits of the observed X-ray spectra to grids of Comptonised model atmospheres yield estimates for the mass and radius of the neutron star, M=1.3 \pm 0.6 M_sol and R=11^+3_-2 km, respectively.Comment: MNRAS in prin

X-ray bursting neutron star atmosphere models using an exact relativistic kinetic equation for Compton scattering

Theoretical spectra of X-ray bursting neutron star (NS) model atmospheres are widely used to determine the basic NS parameters such as their masses and radii. We construct accurate NS atmosphere models using for the first time an exact treatment of Compton scattering via the integral relativistic kinetic equation. We also compare the results with the previous calculations based on the Kompaneets operator. We solve the radiation transfer equation together with the hydrostatic equilibrium equation accounting exactly for the radiation pressure by electron scattering. We thus construct a new set of plane-parallel atmosphere models in LTE for hot NSs. The models were computed for six chemical compositions (pure H, pure He, solar H/He mix with various heavy elements abundances Z = 1, 0.3, 0.1, and 0.01 Z_sun, and three log g = 14.0, 14.3, and 14.6. For each chemical composition and log g, we compute more than 26 model atmospheres with various luminosities relative to the Eddington luminosity L_Edd computed for the Thomson cross-section. The maximum relative luminosities L/L_Edd reach values of up to 1.1 for high gravity models. The emergent spectra of all models are redshifted and fitted by diluted blackbody spectra in the 3--20 keV energy range appropriate for the RXTE/PCA. We also compute the color correction factors f_c. The radiative acceleration g_rad in our luminous, hot-atmosphere models is significantly smaller than in corresponding models based on the Kompaneets operator, because of the Klein-Nishina reduction of the electron scattering cross-section, and therefore formally "super-Eddington" model atmospheres do exist. The differences between the new and old model atmospheres are small for L / L_Edd < 0.8. For the same g_rad / g, the new f_c are slightly larger (by approximately 1%) than the old values.Comment: 16 pages, 16 figures, A&A, in press. Tables containing spectra and color corrections are available by downloading the source file via Other formats fiel

Morphotectonics of the Solinka and Wetlinka water gaps in the light of field studies and interpretation of aerial photographs (High Bieszczady Mts)

Przełomowe doliny Solinki i Wetlinki w dorzeczu górnego Sanu są interesującym obiektem geoturystycznym ze względu na wyraźne związki rzeźby z ewolucją i tektoniką skomplikowanych struktur geologicznych przedpola jednostki dukielskiej w Bieszczadach. Wyróżniają je także malownicze krajobrazy i rozległe odsłonięcia wychodni piaskowców otryckich (młodszy oligocen), ogniwa typowego dla bieszczadzkiego podregionu facjalnego płaszczowiny śląskiej. Szczegółowe badania kartograficzno-strukturalne autora wykazały, że synkliny zbudowane z grubych kompleksów piaskowców otryckich nasunięte są wstecznie na elewacje strukturalne, co nie znalazło odbicia we wcześniejszych ujęciach kartograficznych. Z formowaniem się dysharmonijnych struktur tektonicznych związany jest inwersyjny charakter rzeźby i geneza przełomów Solinki i Witlinki. Pomiary hipsometryczne reliktów powierzchni zrównań pogórskiego i przydolinnego, wykonane na stereoskopowych zdjęciach lotniczych, dokumentują ich znaczne zdeformowanie i oscylacyjny charakter plioczwartorzędowych wypiętrzeń neotektonicznych. Największe deniwelacje powierzchni spłaszczeń korelują się z intersekcją nasunięć wstecznych, które miały istotny wpływ na tektoniczną przebudowę struktur, a także na rozwój rzeźby, prowadząc do powstania antecedentnych przełomów i wciętych meandrówGorge-type valleys of the Solinka and Wetlinka rivers within the Upper San drainage basin represent an interesting geotouristic object in respect of distinct relationship between relief, and evolution and tectonics of complex geological structures in the foreland of the Dukla Unit in the Bieszczady Mts. They also distinguish themselves by picturesque landscapes and vast exposures of the Otryt Sandstone outcrops; this Late Oligocene member is typical of the Bieszczady facies subregion of the Silesian Nappe. Detailed cartographic and structural investigations made by the author have proved that synclines, composed of thick complexes of the Otryt Sandstones, are backward overthrust onto subsurface structural elements, a feature which has not been reflected in previous cartographic elaborations. With formation of the disharmonic tectonic structures, the inversional character and origin of the Solinka and Wetlinka water gaps are connected. Hypsometric measurements of relics of the foothill and riverside planation surfaces, carried out on stereoscopic aerial photographs, have documented significant deformation of the surfaces and oscillatory character of the Pliocene-Quaternary neotectonic uplift. The greatest denivelations of the planation surfaces correlate with the intersection of the backward overthrusts which had crucial effects on tectonic reshaping of the structures, as well as on the relief development; this resulted in the origin of the antecedent water gaps and incised meander

Diagnostic efficacy of optimised evaluation of planar MIBI myocardium perfusion scintigraphy: a probabilistic approach

Background: The Bayesian (probabilistic) approach to the results of a diagnostic test appears to be more informative than an interpretation of results in binary terms (having disease or not). The aim of our study was the analysis of the effect of an optimised evaluation of myocardium perfusion scintigrams on the probability of CAD in individual patients. Methods: 197 patients (132 males and 65 females) suspected of CAD, with no history of myocardial infarction were examined. Scintigraphic images were evaluated applying two methods of analysis: visual (semiquantitative) and quantitative, and the combination of both. The sensitivity and specificity of both methods (and their combination) in the detection of CAD were determined and optimal methods of scintigram evaluation, separately for males and females, were selected. All patients were subjected to coronary angiography. The pre-test probability of CAD was assessed according to Diamond (1) and the post-test probability was evaluated in accordance with Bayes's theorem. Patients were divided, according to a pre-test probability of CAD, into 3 groups: with low, medium and high probability of the disease. The same subdivision was made in relation to post-test probability of CAD. The numbers of patients in respective subgroups, before and after the test, were compared. Moreover, in order to test the reliability of post-test probability, its values were compared with real percentages of CAD occurrence among the patients under study, as demonstrated by the angiography. Results: The combination of visual and quantitative methods was accepted as the optimal method of male scintigram evaluation (with sensitivity and specificity equalling 95% and 82%, respectively) and a sole quantitative analysis as the optimal method of female scintigram evaluation (sensitivity and specificity amounted to 81% and 84%, respectively). In the subgroup of males the percentage of individuals with medium pre-test CAD probability equalled 52 and after the scintigraphic study it decreased to 21 (p < 0.0001). In the subgroup of females it changed from 60 to 43 (p = 0.05). The verification of the values of post-test probability revealed its high concordance with the real frequencies of CAD, with correlation coefficient being 0.98 and the regression line differing only slightly from the line of identity. Conclusions: The results confirm the high reliability of the values of post-scintigraphic probability of CAD obtained in this way, and support the Bayesian, probabilistic interpretation of the study outcome and its application in the diagnostic process

Subsurface structure of the Carpathians in the zone of the Przemyśl Sigmoid: interpretation of seismic sections and assessment of hydrocarbon prospects

Autorzy eksponują kilka nowych aspektów interpretacji wgłębnej tektoniki pokryw fliszowo- -molasowych i ich autochtonicznego podłoża w powiązaniu z oceną perspektywiczności odkrycia złóż węglowodorów w strefie sigmoidy przemyskiej (SP). Oparte są one na wynikach wierceń i geologicznych interpretacji profili sejsmicznych, poddanych reprocessingowi, którego metodyka przedstawiona jest w odrębnej publikacji. Wyniki interpretacji skłaniają do poglądu, że północny zasięg sedymentacji osadów fliszowych był ukośny w stosunku do nasunięć pokryw jednostek grupy brzeżnej. W tym kontekście uznać można, że przed sedymentacją molas budujących płaszczowinę stebnicką utwory fliszowe wypełniały podłużne przegłębienia skłonu platformy, a pozostałe po erozji płaty zostały odkłute i nasunięte łącznie z osadami miocenu. Przyjęcie tego rozwiązania koresponduje z poglądami o wyklinowywaniu fałdów wgłębnych jednostki borysławsko-pokuckiej wzdłuż SP. W świetle tych wyników i znikomego stopnia przeobrażenia termicznego materii organicznej, perspektywy odkrycia złóż węglowodorów w NE części Karpat polskich nie są optymistyczne. Potencjalne pułapki strukturalne zachowały się jedynie w autochtonicznej serii mioceńskiej, pod uszczelniającym nadkładem pokryw allochtonicznych. Odkrycie nowych złóż gazowych w ich obrębie uzależnione jest przede wszystkim od korzystnych cech zbiornikowych, szczególnie w strefach wyklinowywania się horyzontów piaszczystych autochtonu na wyniesieniach podłoża lub ich ekranowania powierzchniami nasunięć.The authors expose some new aspects of interpretation of the subsurface tectonics of flysch and molasse covers and their autochthonous basement in connection with assessment of prospects for hydrocarbon discoveries in the zone of the Przemyśl Sigmoid (PS). They are based on drilling results and geological interpretation of seismic sections which were reprocessed with application of a methodology presented in another publication. Interpretation results incline towards an opinion that the northern depositional extent of flysch sediments was oblique to overthrusts of the Marginal Group units. In this context, it can be accepted that before the deposition of the molasses that build up the Stebnik Nappe the flysch deposits had filled longitudinal depressions of the platform slope and the post-erosional patches had been detached and thrust together with Miocene sediments. Such a solution corresponds with views on pinching-out of deep-seated folds of the Boryslav-Pokutya Unit along PS. In the light of these results and insignificant thermal transformation of organic matter, prospects for hydrocarbon discoveries in the NE Polish Carpathians are not optimistic. Potential structural traps were preserved only in the autochthonous Miocene series overlain by the sealing overburden of the allochthonous covers. Discovery of new gas fields in the traps will depend mostly on favourable reservoir properties, particularly in zones of pinching-out of sandy horizons of the autochthonous series against the basement highs or in zones of their screening by thrust planes