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PubMed1995

Higher reproducibility of morphometric analysis over the counting method for interphase AgNOR quantification.

In a series of 40 breast carcinomas, the reproducibility of two different methods for interphase AgNOR quantification was evaluated. Two operators independently defined on each slide the interphase AgNOR quantity both by measuring the area of the silver-stained structures using image cytometry and counting the AgNOR number directly at the microscope. The correlation between the values obtained by the two observers was statistically significant, but the correlation coefficient between AgNOR areas (r = 0.79; P < 0.001) was greater than that between AgNOR numbers (r = 0.38; P = 0.014). On the other hand, when interphase AgNOR area and number values obtained by each observer were compared, no significant correlation was found. This study has demonstrated that the two different methods for interphase AgNOR quantification are not comparable, and that morphometric analysis is more objective and reproducible than the counting method.

Humans↗
PubMed1995

Simple quantification of benzodiazepine receptor binding and ligand transport using iodine-123-iomazenil and two SPECT scans.

UNLABELLED: The feasibility of simplified procedures for the quantification of benzodiazepine receptor binding using [123I]iomazenil and SPECT was assessed. METHODS: Six normal male volunteers were studied. Following intravenous injection of 111 MBq [123I]iomazenil, serial dynamic SPECT scanning was performed for 120 min and the concentration of lipophilic compounds in the arterial plasma was determined by chloroform extraction. Kinetic parameters were estimated by a curve-fitting procedure using the following four models: three-compartment, four-parameter (K1-k4) (3C4P), three-compartment, three-parameter (fixed K1/k2) (3C3P), three-compartment, two-parameter (fixed K1/k2 and k4) (3C2P) and two-compartment, two-parameter (K1 and k2) (2C2P). Kinetic parameters were also calculated by a table look-up procedure with 3C2P using only two SPECT data acquisitions. Parametric images were generated based on the same procedure. RESULTS: In all models, the curve-fitting procedure gave similar outcomes for ligand transport (K1) and receptor density parameters (i.e., binding potential or distribution volume). The 3C4P parameters showed significant correlation between k2 and k3, while 3C3P did not show such a correlation, suggesting the stability of 3C3P. The 3C2P provided parameters essentially identical to those with the 3C3P, indicating the suitability of this model, while 2C2P gave similar distribution volume but obviously low K1. CONCLUSION: Table look-up procedures based on the 3C2P model permit quantification of benzodiazepine receptor binding using [123I]iomazenil with two SPECT scans. This method may be of clinical value in the diagnosis of various diseases.

Adult↗
PubMed1994

[Echocardiographic on-line volumetry using acoustic quantification--comparison with manual echocardiographic analysis and cineventriculography].

Acoustic quantification (AQ) represents an ultrasound imaging system which provides detection and tracking of endocardial blood boundaries based on quantitative assessment of acoustic properties of tissue in real time. To assess on-line quantitation of left ventricular enddiastolic (EDV), endsystolic (ESV) volumes and ejection fractions (EF) AQ measurements were compared with off-line measurements obtained by manual analysis of video-taped images (MAN) and with cineventriculographic data (CV). Calculations by the AQ system were based on an algorithm using the monoplane disc method. One day before undergoing CV, 88 unselected patients were studied with echocardiography in the apical four-chamber view. Seventy (79.5%) patients could be studied by AQ. The regression equations for determination of EDV were y = 0.7x + 25.2; r = 0.87 (AQ vs. MAN) and y = 0.5x + 22.8; r = 0.80 (AQ vs. CV), for determination of ESV they were y = 0.8x + 11.4; r = 0.78 (AQ vs. MAN) and y = 0.7x + 6.9; r = 0.71 (AQ vs. CV), and for determination of EF they were y = 0.7x + 9.5; r = 0.77 (AQ vs. MAN) and y = 0.6x + 15.0; r = 0.71 (AQ vs. CV). Calculations of left ventricular volumes by AQ or MAN led to a systematic underestimation, compared to CV. EF was also underestimated by AQ, whereas no significant difference between the mean values of MAN and CV exists. In a heterogenous population, acoustic quantification based on quantitative assessment of tissue acoustic properties mostly permits on-line quantitation of left ventricular volumes and ejection fractions in real-time.

Adult↗
PubMed1995

Quantification of optic nerve blood flow changes using magnetic resonance imaging.

PURPOSE: To evaluate the possibilities of magnetic resonance imaging (MRI) for quantification of pharmacologically induced changes in optic nerve microcirculation. METHOD: T2-weighted MRI sequences were used to image the eye, optic nerve, and frontal cortex in rats. Two sets of control images before and one set during Gd (DTPA) infusion were recorded. Blood flow values for two regions of the optic nerve (an anterior part, including the optic nerve head, and a more posterior part) and the frontal cortex were calculated by image analysis from the change in signal intensity, as already reported for cerebral blood flow. For each rat, a control experiment before drug administration and a second experiment 30 minutes after subcutaneous injection of either placebo (n = 7), timolol (n = 7), or SDZ GLC-756, a dopamine D-1 antagonist and D-2 agonist (n = 7), were carried out in a double-blind fashion. RESULTS: Mean basal blood flow values were found between 29.4 and 45.6 ml/100 g per minute in the anterior part of the optic nerve, 38.3 and 42.9 ml/100 g per minute in the posterior part of the optic nerve, and 68.0 and 75.0 ml/100 g per minute in the frontal cortex. Placebo and timolol did not cause significant changes. SDZ GLC-756 significantly increased blood flow by 238% +/- 65% in the anterior part and by 87% +/- 40% in the posterior part of the optic nerve. CONCLUSIONS: These results suggest that MRI provides quantification of optic nerve blood flow and that dopaminergic substances increase optic nerve blood flow.

Animals↗
PubMed1994

[Quantification of mitral valve insufficiency by Doppler echocardiography. Correlation with cine-angiography in 60 patients].

Non-invasive quantification of mitral regurgitation remains a clinical problem. The aim of this study was to assess a new methodology of Doppler echocardiographic assessment of the mitral regurgitant fraction. The study included 60 patients (average age 61 years) in sinus rhythm with mitral regurgitation. The cardiac output was measured by Doppler echocardiography at four sites: the aortic, pulmonary and mitral rings and at the tips of the mitral leaflets by a method previously validated and published. Using the average of the aortic and pulmonary cardiac outputs on the hand and the mitral cardiac output on the other, it was possible to calculate the regurgitant fraction: (mean mitral flow-mean aortic/pulmonary flow)/mean mitral flow. This was correlated with the Sellers angiographic grades of regurgitation. The results confirm this validated procedure: the correlation of aortic and pulmonary flows was good: r = 0.94. This also held true for mitral flow at the two sites: r = 0.96. The correlation between the Doppler echocardiographic regurgitant fraction and the angiographic estimation of the severity of mitral regurgitation was good: r = 0.89. There was a statistically significant difference between the Doppler echocardiographic regurgitant fractions corresponding to Sellers Grades I, II and III mitral regurgitation (p = 0.0001). This study shows that Doppler echocardiographic measurements of blood flow at different orifices of the heart applied to the quantification of mitral regurgitation is a reliable method, the use of which, with strict methodological criteria, may be proposed in everyday clinical practice.

Adult↗
PubMed1994

[The accuracy and applicability of different methods in the Doppler technic for the quantification of mitral stenosis].

INTRODUCTION AND OBJECTIVES: We analyse the applicability and accuracy of the various Doppler methods for quantification of mitral stenosis as well as the value of combining measurements. PATIENTS AND METHODS: The study comprised 74 patients with reliable planimetry of mitral orifice. The following Doppler methods were tested: a) pressure half-time; b) color jet width at the mitral valve orifice in the apical long-axis view (short diameter) and its width in the 90 degree rotated view (long diameter), assuming an elliptic mitral orifice; c) proximal isovelocity surface area from the 4-chamber view assuming a hemispheric surface, and d) the continuity equation. The mean value of mitral valve area estimates from all applicable Doppler methods was calculated in each patient. RESULTS: The rates of applicability of each method were, respectively: 85, 97, 97 and 53% (p < 0.01). The correlations--r (SEE)--between each method and planimetry were: 0.86 (0.17 cm2), 0.81 (0.19 cm2), 0.74 (0.21 cm2) and 0.83 (0.18 cm2), respectively. The highest correlation was found with the mean value (r = 0.90; SEE = 0.14 cm2), and only this parameter was selected by stepwise multiple regression analysis (r = 0.93; SEE = 0.12 cm2). CONCLUSIONS: The continuity equation method has the lowest level of obtainable results owing to the high incidence of mitral regurgitation. The mean value of mitral area estimates from all applicable methods in each patient showed the closest correlation with planimetry, thus the performance of these Doppler methods provides improved accuracy in the quantification of mitral stenosis.

Adult↗
PubMed1994

[Quantification of myocardial tomography with thallium in coronary disease. Evaluation of the Cedars-Sinai technique].

OBJECTIVE: The aim of this study is to evaluate the contribution of the Cedars-Sinai quantification tomographic method (CS) in the diagnosis and localization of ischemic areas in coronary artery disease (CAD) and to optimize the threshold values proposed by CS. PATIENTS AND METHODS: Fifty patients with clinical suspicion of CAD performed a maximal stress test by cycloergometer; thallium myocardial tomographic images were obtained; applying the CS program afterwards. The sensitivity and specificity variations obtained by changing the criteria for extent of myocardial hypoperfusion (range 1% to 100%) were used to calculate the new thresholds (CS-I), using the results of coronariographic studies as a reference. The data determined by qualitative analysis were compared with that obtained by quantitative analysis by means of CS and CS-I using coronary angiography as the standard of reference. RESULTS: The coronary angiography showed coronary disease in 37 patients. The sensitivity for the diagnosis of CAD was superior using CS (97%) at the expense of low specificity (15%) which nevertheless improved with CS-I (54%). For the location of CAD, the visual analysis was statistically significant (p < 0.05) in the left anterior descending and right coronary arteries, CS being superior in the diagnosis of 3 vessel disease. CONCLUSIONS: The quantification of tomographic studies with thallium by means of CS needs a readjustment of the thresholds. The tested values (CS-I) improved the CS results, although they require prospective validation. Quantitative study permits the confirmation of visual findings, being a complementary method that can be rapidly and easily interpreted, although it is not recommended as a single technique for the diagnosis of coronary disease.

Adult↗
PubMed1993

Quantification of oncogene dosage in tumours by simultaneous dual-label hybridization.

Gene amplification and allele loss occur in a variety of human tumours and some have prognostic value. Therefore, techniques which facilitate detection and quantification of gene dosage could have wide applicability in cancer research. Using the INT-2 gene as a model system, a quantitative procedure has been developed for measuring gene copy number using dual-label hybridization to DNA dot blots. A probe specific for the INT-2 gene was labelled with [alpha-32P]dCTP and a probe to beta-actin, the control locus, was labelled with [alpha-35S]dATP. Flat-bed scintillation counting was used to detect and separate the emissions resulting from each bound probe, and gene dosage was calculated from the ratio of INT-2 to the beta-actin probe compared with the ratio derived from constitutional DNA. Calculated ratios of greater than 1.22 and less than 0.78 indicated gene amplification and allelic loss respectively, at the 99% confidence limit derived from the population of 35 constitutional DNAs. The results were validated by RFLP analysis. It is expected that this technique will permit precise gene dosage quantification in many areas.

Alleles↗
PubMed1993

In vivo quantification of myocardial echo intensity from logarithmically amplified, demodulated radiofrequency signals.

Clinical application of echocardiographic tissue characterization necessitates measurements through the chest wall. Different distances between transducer and myocardial region of interest result in variable attenuation effects. Therefore, meaningful comparisons of myocardial echo intensity measurements are difficult with current equipment. The present study aims at the quantification and compensation of depth-dependent attenuation effects. Ten normals, 14 patients with mild (n = 7) or moderate (n = 7) hypertensive left ventricular hypertrophy and 10 transplant candidates were examined. Gain-independent logarithmically amplified, demodulated radiofrequency signals of parasternal long axis cross-sections were digitized. Mean myocardial echo intensities were determined in septal and posterior wall regions of interest. The slope of attenuation was determined from these clinically obtained data by plotting the distances between transducer and regions of interest against myocardial echo intensities. An attenuation coefficient derived from this slope was used for compensation of the depth-dependent losses of myocardial echo intensity. Compared with normals, compensated mean myocardial echo intensities were significantly lower in mild or moderate hypertensive left ventricular hypertrophy, but showed no significant difference in transplant candidates. Despite several limitations, the method employed in this study appears to be a possible approach to in vivo quantification and compensation of attenuation.

Adult↗
PubMed1993

Intrasubject variability of selected force-platform parameters in the quantification of postural control.

Platform stabilometry is increasingly applied to monitor or re-educate standing balance in clinical rehabilitation. Consequently, insight is needed into the validity, reliability, and sensitivity of different force-platform parameters. This study focuses on the intrasubject variability as the major source of variance (unreliability) in the study of human motor skills. The intrasubject variability of several, commonly applied force-platform parameters was determined across ten repeated tests of quiet two-legged standing in healthy subjects to identify the most consistent and stable parameters in the quantification of postural control. The variability of the root mean square (RMS) amplitude, peak-to-peak amplitude, mean frequency, and RMS velocity of the fore-aft and lateral components of the center-of-pressure fluctuations was investigated under varying (visual and cognitive) task conditions. The results indicate that all selected parameters show considerable intrasubject variability irrespective of the task context. Nonetheless, both the RMS amplitude and RMS velocity in either direction of sway do not demonstrate a significant trend across repeated tests. Among the selected parameters, the RMS velocity in the fore-aft direction shows the greatest intrasubject consistency, as well as a high sensitivity to, for example, visual deprivation. These findings support the reliability and validity of this parameter in the clinical quantification of postural control.

Adult↗
PubMed1993

Thermal damage quantification utilizing tissue birefringence color image analysis.

Decreased connective tissue or cardiac muscle birefringence in transmission polarizing microscopy is an observable measure of damaged tissue concentration. Accordingly, histologic monochrome images of thermally damaged tissue exhibiting decreased birefringence provide important information about the tissue thermal history. Thus, a damage quantification algorithm based on monochrome tissue images exhibiting decreased birefringence has been developed providing tissue damage values corresponding to estimated temperature distributions. In addition, utilizing 24-bit true color tissue images, epicardial birefringence color variations resulting from thermal exposures may also be observed. Therefore, image segmentation methods are used on the red, green, and blue color image components to isolate the epicardium, similarly allowing damage quantification on this tissue constituent.

Algorithms↗
PubMed1993

Validation of nitrogen-13-ammonia tracer kinetic model for quantification of myocardial blood flow using PET.

Positron emission tomography has been shown to provide quantitative estimates of myocardial blood flow using 13N-ammonia and 15O-water. In a validation study, myocardial blood flow was noninvasively determined in 11 open-chest anesthetized dogs using dynamic positron emission tomography. The radiopharmaceuticals 13N-ammonia and 15O-water were intravenously administered and measurements were carried out at rest and following pharmacological vasodilation to assess blood flow over a range from 53 to 580 ml/100 g/min. Quantification of blood flow based on tracer kinetic modeling of 13N-ammonia data correlated closely with myocardial blood flow determined by microspheres (y = 0.944 x +7.22, r = 0.986) and with the 15O-water injection technique y = 1.054 x -15.8 (r = 0.99). The use of 13N-ammonia with positron emission tomography enables the accurate quantification of myocardial blood flow. Using this technique, uncomplicated study protocols simplify the measurement procedures while providing excellent qualitative and quantitative information.

Ammonia↗
PubMed1993

Quantification of relative biological effectiveness, dose modification factor and therapeutic gain factor.

Some basic aspects of tumor cell radiobiology are reviewed and the classical methods for the quantification of tumor response are outlined. The definition and methods for quantification of the parameters "relative biological effectiveness", "dose modification factor", and "therapeutic gain factor" are discussed. It is concluded that the first two parameters are of little practical use to compare different treatments. Only the therapeutic gain factor enables a reasonable estimation of the benefit that can be obtained from a new treatment modality.

Boron Neutron Capture Therapy↗
PubMed1993

[A simple method of digitizing analog scintigrams for quantification and digital archiving].

This study was undertaken to evaluate a quick, reliable and cheap method of digitizing analog scintigrams. 40 whole-body bone scintigrams were obtained simultaneously in analog and genuine digital format. The analog scans on x-ray film were then digitized secondarily by three different methods: 300 dpi flat-bed scanning, high-resolution camera scanning and camcorder recording. A simple exposure approach using a light box, a cheap camcorder, a PC and image grabber hard- and software proved to be optimal. Visual interpretation showed no differences in clinical findings when comparing the analog images with their secondarily digitized counterparts. To test the possibility of quantification, 126 equivalent ROIs were drawn both in the genuine digital and the secondarily digitized images. Comparing the ROI count to whole-body count percentage of the corresponding ROIs showed the correlation to be linear. The evaluation of phantom studies showed the linear correlation to be true within a wide activity range. Thus, secondary digitalization of analog scintigrams is an easy, cheap and reliable method of archiving images and allows secondary digital quantification.

Analog-Digital Conversion↗
PubMed1996

Quantification of circulating 1,25-dihydroxyvitamin D by radioimmunoassay with 125I-labeled tracer.

We report here the first RIA for 1,25-dihydroxyvitamin D utilizing a radioiodinated (125I) tracer. This is also the first validated RIA for 1,25-dihydroxyvitamin D [1,25(OH)2D] that does not require sample prepurification by HPLC before the binding assay. The assay involves acetonitrile extraction, treatment of the crude extract supernate with sodium periodate, extraction and purification of endogenous 1,25(OH)2D by solid-phase chromatography, and finally, quantification by RIA. Calibrators were prepared in stripped human serum and processed exactly the same as samples, eliminating the need for internal control for procedural losses of endogenous 1,25(OH)2D. The assay consists of a 2-h room temperature incubation with the primary antibody, a 20-min incubation with a second antibody, and separation of bound from free by centrifugation. Assay results can be in hand with 5 h. The detection limit of the assay is 2.4 ng/L 1,25-dihydroxyvitamin D3. Results compare well with those from an accepted radioreceptor assay. Sample pretreatment with sodium periodate is absolutely essential before quantification by RIA; otherwise, concentrations of endogenous 1,25(OH)2D may be greatly overestimated.

Acetonitriles↗
PubMed1996

Quantification of X-chromosome inactivation patterns in haematological samples using the DNA PCR-based HUMARA assay.

Quantification of X-chromosome inactivation patterns (XCIPs) using PCR amplification of the human androgen receptor (HUMARA) locus is potentially valuable in a range of haematological disorders. Of 236 females screened, 203 (86%) were heterozygous. For quantitative XCIPs it was necessary to limit the number of PCR cycles to 20 to reduce preferential amplification of shorter alleles. The optimized PCR method was compared with Southern blotting results using either PGK, HPRT or M27beta in 51 haematologically normal females and blast cells from 27 patients with acute myeloid leukaemia (AML). Reproducible XCIP results were obtained in all 78 samples using digestion with Hpa II prior to amplification (median difference in duplicate values 3%, range 0-17%) and they correlated well with Southern blotting results, r=0.966. Greater variability was observed in the results using Hha I digestion (median difference 4%, range 0-48%). There were marked inconsistencies in repeated analyses of three AML samples and although the HUMARA-Hha I results correlated well overall with Southern blotting in the remaining 75 samples (r=0.922), in nine samples there were still discrepancies with > or = 20% difference between the two values. These results suggest that PCR analysis of the HUMARA locus in Hpa II-digested DNA is suitable for the quantification of XCIPs in haematological samples but results with Hha I should be treated with caution.

Alleles↗
PubMedDate not supplied

Quantification of experimental Salmonella enteritidis carrier state in B13 leghorn chicks.

Quantification of the carrier state of Salmonella enteritidis in chicks (i.e., persistent asymptomatic association of S. enteritidis with the host), should provide an optimized means for further investigations into this problem. We therefore developed an experimental carrier state model by oral inoculation of low doses (10(2)-10(4)) of S. enteritidis in B13 chicks at different ages. Liver, spleen, and ceca colonizations by the challenge strains were measured weekly by enumeration of S. enteritidis colony-forming units (CFU) for 7-12 weeks. High mortality rates, incompatible with the carrier state, were observed in chicks inoculated with 10(2) organisms of either a parental strain of S. enteritidis (5556) or a mutant resistant to streptomycin (Smr) and nalidixic acid (Nalr) (strain 1009) at 1 day old. Both strains colonized organs similarly, allowing us to use subsequently the SmrNalr mutant strain. The selected low doses of S. enteritidis induced no deaths in chicks inoculated at 1 or 3 weeks of age. However, inoculation of 3-week-old chicks did not induce a satisfactory carrier state; organ colonization by S. enteritidis was weak and transient, even after inoculation of 10(8) SE. In contrast, some birds infected at 1 week of age presented the challenge strain in the liver and spleen for 3 weeks after inoculation and in the ceca for 12 weeks postchallenge. Most of these birds were colonized by S. enteritidis in the liver and in the ceca for 3 weeks and 10 weeks, respectively, following inoculation. Generally, CFU levels were highest during the first week(s) after inoculation and then decreased progressively. Levels of S. enteritidis were lower in the liver and spleen than in the ceca. Oral inoculation of 1-week-old birds with 5 x 10(4) S. enteritidis provided the required model, allowing quantification of the carrier state of S. enteritidis in chicks.

Animals↗
PubMed1996

[Quantification of proviral FIV DNA using competitive PCR].

Quantification of provirus copies is important in the context of different biological questions. The most reliable approach for DNA quantification is a PCR based on coamplification of two templates of similar length, the target sequence and the reference template, sharing the same primer recognition sequences. During the amplification, the two templates compete for the same primer set (competitive PCR, or cPCR) AND consequently amplify at the same rate independently of the number of cycles. The amplified products can be distingushed by their different lengths. After densitometrical analysis, the proviral copy number of experimentally feline immunodeficiency virus infected cats could be calculated, since a known amount of reference template was used. The method described here proved to be very sensitive (10 copies for the competitor-DNA) and was used to quantitate the proviral load during several experiments in which the influence of periodical immunestimulations and the effect of vaccines on the virus load was studied.

Animals↗