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Biomedical subjects

G Esther

Publications and source records attributed to G Esther.

At least 19 recordsLinked to original sources
PubMed1993

[The trend distribution quotient, a new tool for evaluating renal perfusion scintigraphy using 99mTc-DTPA following renal transplantation].

We developed a new quantitative concept in dynamic renal transplant imaging, the Trend Distribution Ratio, and tested its diagnostic usefulness in 137 examinations. This ratio is an expression of the distribution of blood flow velocity in different areas of the kidney. With regard to the differential diagnosis between acute tubular necrosis and the various forms of rejection we arrived at a sensitivity of 0.83 and a specificity of 0.54. A differentiation between the various histological types of rejection has not yet been possible.

Blood Flow Velocity↗
PubMed1991

Theoretical basis and experimental verification of the impact of ultrafiltration on dialyzer clearance.

Dialyzer clearance K is usually presented as K = K0 + Tr Qu, were Qu is ultrafiltration rate, K0 is clearance for Qu = 0, and Tr is transmittance coefficient. Although a simple and accurate mathematical description of K0 is widely used, only a somewhat inaccurate formula for Tr that predicts a linear relationship between Tr and K0 has been proposed before. In this study the detailed investigation of Tr using a one-dimensional theory of a dialyzer is presented. In general, the application of a one-dimensional theory requires sophisticated numerical methods, but for small and middle molecular weight solutes an analytical formula for K can be derived. Tr predicted by the developed theory in comparison to Tr predicted by the previous linear formula is higher for small molecular weight solutes and lower for middle and large molecular weight solutes. These theoretical results were confirmed in experiments carried out in vitro for hollow-fiber dialyzers and small molecular weight solutes (urea, creatinine, sodium, TcO4) as well as middle molecular weight solutes (vitamin B12).

Hemofiltration↗
PubMed1990

[Simultaneous determination of the GRF and the ERPF (effective renal plasma flow) using a single blood sample in the slope clearance with 99mTc-DTPA and I 131-hippurate].

In patients with various indications to renal split function diagnostics the plasma slope clearance of the Tc99m-DTPA and J131-Hippurate to the estimation of GFR and ERPF were performed with two or three blood samples in the monocompartment model (1 KM). In comparison these functional parameters were calculated on the basis of the only least blood sample (single-point procedure--EPV). The results of linear regression GFR (1 KM) = 12.7 + 0.978 * GFR (EPV), r = 0.986, N = 102 or ERPF (1 KM) = 22 + 1.13 * ERPF (EPV), r = 0.889, N = 68 may recommend the use as patient-safe procedure especially in poor venous access. Two short BASIC programs for estimation of GFR and ERPF are presented and the error ranges discussed.

Adult↗
PubMed1988

[Standardization of methods and assessment of conventional and radionuclide clearance investigations: recommendations of the Renal Diagnostics Study Group of the Society of Nephrology, GDR].

Recommendations of the Study Group "Renal Function Diagnostics" of the Society of Nephrology to the performance of the steady state clearance using inulin or PAH and the slope clearance with radionuclides for estimation of effective renal plasma flow are presented. These investigations are indicated in the early recognition and follow-up of latent or residual disturbance of the renal function in the creatinine-blind area. Recommendations have been done on selection and dosage of test substances, timing of examination and evaluation of results.

Blood Pressure↗
PubMed1983

Heparin binding and release properties of DEAE cellulose membranes.

Two cellulose-based membranes, containing 5 and 20% N, N-diethyl-aminoethyl cellulose (DEAE) respectively, were investigated for ionic attachment of heparin and heparin release. Heparinization was achieved by recirculation of a heparin-containing glycine buffer over each membrane. Heparin was determined by chemical analysis or by 99mTc labelling. The heparin uptake was shown to be linearly dependent on the heparin content in the contacting fluid. Heparin release was studied by contacting heparinized membranes with saline, glycine buffer, phosphate buffer and plasma. Incubation with plasma brought about the release of 50% of the attached heparin. Crosslinking of the heparinized membrane with glutaraldehyde reduced the heparin release by one half. The release reaction is more critical in the case of increased heparin uptake and a more efficient immobilization of heparin appears necessary.

Cellulose↗
PubMed1983

[Comparative estimation of monocompartmental methods of analyzing 99m-Tc-diethylenetriamine pentaacetic acid clearance by declining plasma levels with special reference to long term studies].

Plasma slope clearance estimation with 99m-Tc-DTPA corresponds to total clearance determination. When activity is measured directly in cumulative serum samples, determination of the plasma slope clearance is suitable for practical applications only if simplified analytic procedures are used. Monocompartmental analytic procedure that take the late slope of the disappearance curve into account are particularly useful for GFR estimation. The A3k3-slope-clearance analysis method is a monocompartmental procedure for determining slope clearance that is based on activity measurements between the 100th (120th) and 240th minute after injection. Compared with other monocompartmental procedures, the A3k3-clearance method shows a highly significant hyperbolic correlation with serum creatinine, a highly significant linear correlation with inulin total clearance, is age dependent and yields reproducible results. The sensitivity (frequency of correct function results in the case of disturbed glomerular function) of the A3k3-slope-clearance method with 99m-Tc-DTPA is particularly good. The practically important predictability of pathological A3k3-clearance results (frequency of correct results when the kidney function is truly reduced) is on the average 85%. The mean efficiency of the method is 88% (65-97% at the 95% confidence-level).

Animals↗
PubMed1983

[Results of the determination of enteral calcium absorption and calcium kinetics with 47Ca in patients with chronic recurring urolithiasis].

In the context of the classification of hypercalciuria in urolithiasis, the measurement of enteral calcium absorption is very important. A precise method is that of oral load with 47Ca and measurement of its activity by means of a human body counter; 47Ca activity in serum, urine and stools in simultaneously measured. To date 47 patients with chronically recidive calcium lithiasis (with between 3 and over 100 stone episodes) and an average age of 43.2 years have been examined. Calcium absorption lay between 42.7% and 90.0% of the dose, the average was 59.3% with a standard deviation of +/- 12.9. This is higher than in persons with healthy kidneys, but not significantly so. Calcium absorption is significantly lower in patients with renal insufficiency. The studies on calcium kinetics revealed turnover rates and pool sizes within the normal range.

Adult↗
PubMed1982

In vitro assessment of charcoal and resin hemoadsorbents.

An in vitro assessment has been made of the blood compatibility and efficiency of different charcoal and resin hemoadsorbents. The charcoals vary in source, shape, size, nature and amount of polymer coating. The resins are the macroreticular adsorbents XAD-4 and Y56 and a carbonized resin. The effect on Y56 of albumin coating has been studied. The assessment has demonstrated that a reduction in platelet drop is accompanied by a decrease in the adsorption of fibrinogen. The results confirm the potential advantages of spherical charcoal and that coating with an ultrathin layer of polymer or with albumin does not seriously reduce efficiency. For Y56 resin, treatment with an albumin solution of 1-2 g/100 ml appears to be a suitable procedure if clinical use is considered.

Antigen-Antibody Complex↗
PubMed1982

Tc-99m-DTPA--a new test substance for detoxification devices.

Tc99m labeled diethylenetriaminepentaacetic acid (Tc-99m-DTPA) is an appropriate in vivo test solute for all extracorporeal detoxification procedures. The molecular weight of the Tc-99m-DTPA complex is within the biologically relevant middle molecular range of 400 to 700 daltons. Tc-99m-DTPA is distributed in the extracellular space in the same way as inulin. Regarding its localization in the gel filtration spectra and plasma clearance, Tc-99m-DTPA corresponds to middle molecule peak 2. The evaluation of elimination rate and plasma clearance CP of Tc-99m-DTPA is possible by measuring the pulse rates before and after the detoxification device. Taking into account the corrections for Ht and UFR, the Tc-99m-DTPA plasma clearances were calculated for different dialyzers, high flux dialyzers, hemofilters and a hemoperfusion device. The continuous measurement of pulse rates and the use of a UFR-controller (A2008) allow an exact tracking of CP vs. time, the estimation of CP (QB), CP(UFR) and of the sieving coefficient. Examples are given for these cases. It was shown that an increase in plasma clearance to more than about 100 ml/min does not greatly increase the Tc-99m-DTPA elimination rate.

Humans↗
PubMed1981

[Compartment analysis of potassium metabolism--mathematical modelling of 42-K tracer kinetics].

The possibility of application of the theoretical concept of the compartment analysis in the modelling of the potassium balance was demonstrated. A use of the compartment analysis of the potassium balance in the clinical routine diagnostics in the sense of a highly specialised functional diagnostics seems according to recent experiences reasonable only in closest cooperation with clinicians. The diagnostics and the control of therapy of the chronic syndrome of potassium deficit as well as metabolically conditioned disturbances of the distribution of potassium were to be seen as possible indication. At the same time the establishment of reference values for the demarcation of relative disturbances of distribution as well as for the establishment of the normal region of the turnover rates were necessary.

Body Fluid Compartments↗
PubMed1981

[Compartment analysis in the diagnosis of iron metabolism disorders].

The principle of the ferrokinetics according to the catenary model and to the multilocular system of Pollycove and Mortimer is described in short. The most important results of the investigation of the iron metabolism of 15 patients with chronic myelosis, 31 with osteomyelofibrosis and 68 with chronic liver diseases according to the catenary model are reported. According to the multicompartment model the ferrokinetic investigations of 18 patients with chronic liver disease as well as of one patient each with chronic myelosis and panmyelopathy were evaluated. An increased depot iron metabolism and a decreased effective erythropoiesis could particularly clearly stated in the latter patient. The statements to various parameters according to the two model demonstrations are compared.

Adult↗
PubMed1981

Continuous measurement of DTPA-clearance in extracorporeal detoxification circuits.

A new method for investigating clearances is described. DTPA labelled with technetium 99m (MW: 496 daltons) is used as an agent to be measured. Continuous determination of the DTPA-clearance is possible in extracorporeal detoxification circuits including dialyzers, hemofilters and hemoperfusion columns. As an example, DTPA-clearances are given for two different dialyzers. In comparison to clearance measurements of peak 7, DTPA-clearance was very similar to that obtained for peak 7.

Autoanalysis↗
PubMed1980

[Developmental tendencies of hemadsorption in uremia treatment].

After at first having dealt with the present stage of haemoperfusion in the therapy of chronic renal insufficiency, the developmental tendencies for the haemoadsorbers to be expected are mentioned which in future allow to think of a diminution of the artificial kidney. Own results concerning the behaviour of blood compatibility and the effectivity of different active charcoals show that it is to be reckoned with the further development of unstratified adsorbents or such ones with ultra-thin layer. Comparative examinations of 4 patients from the chronic haemodialytic programme, who were treated for 4 months with the CDAK 1.8 and then for 4 months with the sorbent dialyser 1.3, could not show any essential differences in the behaviour of the low-molecular substances urea, creatinine and uric acid and of the clinical condition of the patients.

Creatinine↗
PubMed1980

[Physiological-pathophysiological evaluation of possibilities and limits of unilateral renal function tests].

1. Issuing from the clinical method of proceeding in side-separated diagnosis of the renal function under theoretical aspect a survey orientation for the renal global function is tried. 2. The method orientation is done according to semiquantitative and quantitative valuation. The isotope and contrast remedy urography, the functional tests after Howard, Rapoport and Stamey, the conventional side-separated estimation of the clearance, the isotope sequence scintigraphy as well as the diagnostics of the renal and intrarenal haemodynamics (renin determination, measuring of the renal plasma flow by means of PAH and other indicators [133-xenon-wash-our-technique]). 3. Finally a valuation of the method concerning the side-separated diagnostics of the renal elimination function as well as of the stenosis of the renal arteries is done taking into consideration the performability of the investigation methods in the clinic.

Acid-Base Equilibrium↗