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At least 181 records · Page 10Linked to original sources
PubMed1992

On-line quantification of ventricular function during dobutamine stress echocardiography.

To develop an approach for on-line quantification of left ventricular size and function during pharmacological stress testing we employed echocardiographic automatic edge detection via integrated backscatter imaging during dobutamine infusion in 27 patients. Ventricular cavity areas, fractional area change and rate of cavity area change were obtained on-line with instantaneous graphic display of the data. When compared to baseline image data, patients with a normal response exhibited modest (15%) reduction in end-diastolic cavity areas at peak dobutamine level, but marked (33%) reduction in systolic areas yielding a 52% increase in fractional area change (n = 13; P < 0.001). The second group of patients (n = 14) had an abnormal response characterized by limited changes in measured parameters of ventricular function and reduced fractional area change (P < 0.05). On-line quantification during pharmacological stress echocardiography is a promising addition to the test for surveillance and objective instantaneous evaluation of global cardiac responses.

Adult↗
PubMed1985

Noninvasive quantification of the aortic valve area in aortic stenosis by Doppler echocardiography.

To develop a noninvasive approach to the quantification of the stenotic aortic valve area, Doppler echocardiography and cardiac catheterisation were performed in 24 patients with pure aortic stenosis. The transmitral volumetric flow was measured by Doppler echocardiography and calculated as the product of the corrected mitral orifice area (CMA) and the diastolic velocity integral (DVI). The maximal aortic jet velocities were recorded by Doppler technique and integrated to obtain the systolic velocity integral (SVI). Assuming that the aortic and mitral volumetric flows are equal, the aortic valve area (AVA) was calculated as: AVA = CMA X DVI/SVI. Mean pressure gradient and cardiac output were measured during catheterisation and the aortic valve area was calculated by the Gorlin formula. Comparison between the aortic valve area determined by Doppler technique and catheterisation yielded a close correlation (r = 0.92, P less than 0.001), and there was no significant difference between the two measurements. Good correlations of the instantaneous pressure gradient and the stroke volume were also obtained between the two techniques (r = 0.91 and r = 0.90, respectively, P less than 0.001). These results demonstrate that our Doppler echocardiographic method provides a promising approach to the noninvasive quantification of the aortic valve area in aortic stenosis.

Adult↗
PubMed1983

Detection and quantification of regional wall motion abnormalities using phase analysis of equilibrium gated cardiac studies.

Phase images obtained from equilibrium gated cardiac studies were evaluated for qualitative and quantitative information and correlated with contrast angiography in 33 patients. The left ventricular region of interest was obtained by a semiautomatic procedure which avoided underestimation of size but also eliminated extraventricular pixels. Phase images and phase distribution histograms were arranged in three standard displays which included the whole heart, isolated left ventricle, isolated abnormal areas, and quantification of maximum phase shift in the whole free border and in the inferolateral and posterolateral segments. Only the free left ventricular border was evaluated. According to contrast angiography results, four categories were obtained: normal, hypokinetic, akinetic, and dyskinetic. The best correlation with contrast angiography was found with the results obtained by dividing the left ventricular free border in two segments (r = 0.91). Scheffe's test for multiple comparisons showed significant differences between each of the four categories. Expressed in phase shifts from the histogram mode, the lower limits for the three abnormal categories were established at 30 degrees, 78 degrees, and 156 degrees respectively for hypokinetic, akinetic, and dyskinetic segments. For distinguishing normal from abnormal segments, sensitivity = 83%, specificity = 94%, and accuracy = 89%. The main reasons for discrepant results appeared to be small hypokinetic areas in an otherwise normal ventricle, very large area of hypokinesia, segments adjacent to an area of marked abnormality, and ventricles with asynchrony (wave-like motion). The method described provides an image which characterizes myocardial synchrony, generates clear boundaries for abnormal areas, and lends itself to quantification.

Adolescent↗
PubMedDate not supplied

Radioisotopic techniques for noninvasive detection of platelet deposition in bovine-tissue mitral-valve prostheses and in vitro quantification of visceral microembolism in dogs.

Platelet deposition on bovine pericardial-tissue mitral-valve prostheses in 11 dogs was observed noninvasively by use of 111In-labeled platelets and quantified after sacrifice at one (n = 3), 14 (n = 3), and 30 (n = 5) days postimplantation (300-400 microCi of labeled platelets having been injected 24 hours previously). Thrombosis on the sewing ring and pericardial leaflets at one and 14 days and on the leaflets at 30 days was delineated in scintiphotos. In vitro quantification (% injected dose) indicated that the leaflets, sewing ring, and perivalvular tissue retained 0.904% of labeled platelets at one day postimplantation, 0.198% at 14 days, and 0.040% at 30 days. Platelet half-life was reduced to 38 hours at 21 days postimplantation but returned toward the normal (50 hours) with fibrous ingrowth in the sewing ring. Microembolism in lung and kidney, as measured by tissue/blood radioactivity ratio, also was decreased significantly at 30 days. 111In-labeled platelets thus provide a sensitive marker for noninvasive imaging and in vitro quantification of platelet deposition on valvular prostheses and microemboli trapped in viscera, although histochemical confirmation will be necessary to correlate the increase in tissue/blood ratio with the presence of microembolism.

Animals↗
PubMed1987

A preliminary study of MRI quantification of simulated calcified pulmonary nodules.

The potential of magnetic resonance imaging (MRI) quantification of calcium for the evaluation of pulmonary nodules was investigated in simulated nodules. Calcium salts do not contain mobile protons and thus have no signal on MR proton images. To determine whether the absence of signal from partially calcified nodules could be quantified, we studied simulated nodules containing known quantities of calcium salts. The soft tissue equivalent material was an agar-gelatin mixture (T1:1100-1500 msec; T2: 59-62 msec). In the first experiments, glass tubes were filled with the mixture, which contained suspensions of calcium carbonate (CaCO3) or silica dioxide (Si02), and were subjected to computed tomography (CT) scanning and MR imaging. In a second series of studies CaCO3 particles of various sizes (and therefore different surface-to-volume ratios) were similarly suspended and subjected to CT scanning and MR imaging. In a third series hydroxyapatite (HA) suspensions of different sizes were similarly studied. CaCO3 produced a significant reduction in MR hydrogen density and signal intensity of the agar-gelatin mixture. Reduction in T1 and T2 relaxation times was inconsistent and not related to particle size. CaCO3 produced its effect by soft-tissue displacement. HA (and Si02) caused a more marked fall in MR hydrogen density, signal intensity, and T1 and T2 relaxation times. The degree of the T1 and T2 effects was related to particle size, indicating a hydrophilic surface effect. The authors conclude that MRI quantification of calcium within pulmonary nodules (or other tissues) will be complex and will relate to the precise composition of the calcium salt and to the particle size of the aggregates.

Calcinosis↗
PubMed1992

Noninvasive liver-iron quantification by computed tomography in iron-overloaded rats.

RATIONALE AND OBJECTIVES: The benefit of computed tomography (CT) for the noninvasive determination of liver-iron concentration in human iron-overload diseases is a controversy in the literature. To study the sensitivity of CT for liver-iron quantification under experimental conditions, the authors measured single- and dual-energy CT numbers in vivo in the livers of iron-overloaded rats. METHODS: Thirty-five rats were subjected to an iron-rich diet for various periods, from 1 to 20 weeks, then scanned by single- and dual-energy CT. CT absorption was correlated to liver-iron content, which was determined by wet ashing and spectrophotometry. RESULTS: Whereas a good correlation (r = 0.99 at 96 kV; r = 0.95 at 125 kV) between CT numbers and liver-iron concentration was found, CT was insensitive to low concentrations of iron. Dual-energy CT scanning results showed greater scattering in liver-iron quantification compared with single-energy CT. CONCLUSIONS: In rats, the sensitivity of single- and dual-energy CT is too low to quantify liver iron in the diagnostically most relevant region of mild liver siderosis (1-3 mg iron/g wet weight [w.wt]).

Animals↗
PubMed1981

Quantification of trabecular bone with low dose computed tomography.

Computed tomography (CT) has the potential of providing a precise quantification of trabecular bone. A special purpose low dose CT system for applications at peripheral measuring sites has been developed. With this system, the quantification of trabecular bone can be achieved with a reproducibility on the order of 0.3%. It has been used successfully in pilot studies of immobilization osteoporosis in children and adults on a week by week basis. Currently, the method is being used in a preliminary investigation of bone loss in women in an attempt to differentiate normal changes from changes due to postmenopausal osteoporosis. Results obtained so far indicate that intervals of 3 months are adequate for following the natural course of osteoporosis or its response to therapy on an individual basis.

Adult↗
PubMed1989

A technique for using CT images in attenuation correction and quantification in SPECT.

A technique is described for using computed tomography (CT) images for attenuation correction and quantification in SPECT. The CT images are aligned with the corresponding SPECT slices and the Hounsfield units are converted to linear attenuation coefficient values for the SPECT radionuclide. The attenuation coefficient map thus produced is used to provide the attenuation correction required in the SPECT reconstruction. The technique has been evaluated in both a non-anatomical and an anatomical phantom giving a mean accuracy in quantifying activity of various features in the phantoms of 2.6% (range 0.3%-4.0%). The value of performing scatter correction prior to attenuation correction in obtaining accurate quantification is demonstrated. The practicalities of applying the technique in patient studies are discussed.

Abdomen↗
PubMed1989

Numerical evaluation of symptoms in cervical myelopathy by quantification theory III (Hayashi).

The authors applied Hayashi's quantification theory III, a mathematical approach for quantification of qualitative data to evaluate cervical myelopathy in 81 patients who had been surgically treated. More of these patients recovered from sensory disturbances than from motor disturbance. The size of the spinal canal was correlated with the severity of the preoperative symptoms of the myelopathy, but not with the surgical results. The surgical results were correlated with the duration of the disease but not with the age of the patient. The most predictable surgical result obtained by the use of multiple regression analysis was that of the leg motor symptom.

Adult↗
PubMed1983

Quantification of the antiviral effect of interferon by immunoassay of vesicular stomatitis virus proteins.

A simple solid-phase immunoassay for quantification of vesicular stomatitis virus (VSV) is described. Infected cultures are lysed with deoxycholate. Samples of the lysates are transferred to PVC immunoassay plates and the amount of virus protein adsorbed to the plates is then quantified by sequential incubation with antiserum against VSV proteins and 125I-labelled Protein A. The decrease of VSV protein in interferon (IFN)-treated cultures is correlated with inhibition of formation of infectious virions; its quantification therefore allows accurate measurement of the antiviral effect. The applicability of the immunoassay for measuring the virus yield is not restricted to cells exhibiting a virus cytopathic effect. Moreover, since the decrease of virus protein is obtained at IFN concentrations lower than those that reduce cell killing by the virus, the assay provides a more sensitive measure for the IFN effect than that obtained by 'cytopathic effect inhibition' assays.

Cell Line↗
PubMed1992

Quantification of human cytomegalovirus DNA using the polymerase chain reaction.

The important goal of developing quantitative assays for viral nucleic acids in clinical samples has been achieved for human cytomegalovirus (HCMV) by using a modified polymerase chain reaction (PCR). A control PCR target sequence was constructed by PCR mutagenesis to allow the post-amplification quantification of HCMV DNA. The control region was identical to a naturally occurring sequence within the glycoprotein B (gB) coding part of the virus genome, except that a unique restriction site, introduced by the aforementioned mutagenesis step, allowed post-amplification differentiation of control/non-control target amplified product. This technique was initially validated using known amounts of cloned control/non-control target DNA, and was found to be sufficiently sensitive to allow the quantification of a range of 10 to 10(6) genome equivalents of virus. The method was applied to urine samples of congenitally infected infants for which infectious virus titres were available. The results obtained demonstrated that the number of infectious virions determined by conventional cell culture represented a small proportion of the HCMV genome present in the samples, as assessed by the quantitative PCR methodology.

Base Sequence↗
PubMed1989

Quantification of urinary growth hormone (GH) excretion by centrifugal ultrafiltration and radioimmunoassay: appraisal of the relationship between 24 h urinary GH and mean 24 h serum GH levels in normal and abnormal states of GH secretion.

We have applied a simple method for the quantification of 24 h urinary GH excretion (24 h UGH), combining centrifugal ultrafiltration and radio-immunoassay (RIA), to an appraisal of the relationship between 24 h UGH and mean 24 h serum GH levels in normal and abnormal states of GH secretion. Forty-four subjects, comprising 13 normal adults, 12 short-statured subjects and 19 subjects with active acromegaly, underwent blood sampling at 20-min intervals and concurrent urine collection for 24 h. Mean 24 h serum GH and 24 h UGH were also determined in four post-menopausal women before and during cyclical oestrogen replacement therapy, and 24 h UGH was measured in six normal men prior to and following the subcutaneous administration of biosynthetic GH (0.2 IU/kg). Each subject's mean 24 h serum GH level was determined by assaying a 'pooled' sample, derived from equal aliquots of the 73 serum samples obtained during the 24 h study. The method for quantification of 24 h UGH employs centrifugal microconcentrators, and involves a 50-fold concentration of urine, followed by dialysis and RIA. Surface adsorptive hormone loss during sample collection and ultrafiltration is minimized by the prior addition of bovine serum albumin to the urine collection container. Immunoreactive GH in ultrafiltered urine dilutes in parallel with the RIA standard curve. GH is stable in urine stored at - 20 degrees C for at least 12 months. There was a highly significant correlation between 24 h UGH and mean 24 h serum GH values obtained from the combined population of normal adults (including the post-menopausal women during oestrogen therapy) and short-statured subjects (r = 0.69, P less than 0.0001). A significant correlation was also found in short-statured subjects alone (r = 0.63, P less than 0.05). In contrast, there was no significant correlation between 24 h UGH and mean 24 h serum GH in subjects with active acromegaly, and their 24 h UGH values were not distinguishable from those of the 'non-acromegalic' subjects. A significant increase in 24 h UGH occurred in the post-menopausal women given cyclical oestrogen replacement therapy (9.7 +/- 2.6 (mean +/- SE) to 24.6 +/- 1.0 muIU/mmol creatinine, P less than 0.02), reflecting the increase in their mean 24 h serum GH levels (0.8 +/- 0.3 to 5.3 +/- 0.7 mIU/l, P less than 0.01). Twenty-four hour UGH increased from 4.6 +/- 0.6 to 17.1 +/- 2.1 muIU/mmol creatinine (P less than 0.002) in the men given biosynthetic GH. Twenty-four hour UGH measurements reflect mean 24 h serum GH levels in normal adults and short-statured subjects. While the measurement of 24 h UGH shows promise as an investigative tool, our results cast doubt on its use in the diagnosis of acromegaly.

Acromegaly↗
PubMed1991

Gap-junction quantification in biological tissues: freeze-fracture replicas versus thin sections.

The relative efficiency of freeze-fracture replicas versus thin sections for the visualization and quantification of gap junctions in biological tissues has been evaluated. Both methods may underestimate gap-junction number--thin sections for reasons of tissue resolution and freeze-fracture replicas due to the mechanics of the fracturing process. Freeze-fracture misses gap junctions in regions of plasma membrane which are highly contoured, such as the overlapping basal cell processes of Drosophila imaginal wing discs and the interdigitating lateral membrane plications of intercalated discs in cardiac tissue. If the missed gap junctions are relatively large, as they are in both of these examples, freeze-fracture significantly underestimates the total gap-junctional area. Thin sections may miss small gap junctions, but in tissues which contain a range of gap-junction sizes the lost junctions constitute a relatively small fraction of the total junctional area. In neoplastic imaginal wing discs, thin sections were as efficient as freeze-fracture replicas in identifying even the smallest gap junctions. Although freeze-fracture may be the better technique for the qualitative and quantitative documentation of small gap junctions in tissues with relatively flat to gently contoured plasma membranes and thin sections may be the superior method for gap-junction quantification in tissues containing a range of gap-junctional sizes and highly contoured cellular processes, the data suggest that a combination of the two approaches should be utilized whenever possible.

Animals↗
PubMed1992

The quantification of fluorescent emission from biological samples using analysis of polarization.

The quantification of fluorescent emission from biological specimens can only be carried out in cellular regions where the relationship between fluorophore concentration and fluorescent emission is linear. Using a confocal scanning laser microscope, we show that quantification of fluorescent emission from biological samples labelled with fluorescein and fluorescein analogues mounted in a viscous medium can be readily achieved. Where the distribution of fluorophore is highly localized, for example in cells labelled for immunofluorescence analysis, we demonstrate that analysis of fluorescence depolarization can identify regions in which fluorophore concentration exceeds the range in which the relationship to fluorescent emission is linear. We also demonstrate that, under the conditions examined, depth-dependent effects, fading and quenching are either small enough to be ignored or can be corrected for mathematically when quantifying fluorescent emission.

Animals↗
PubMed1979

Quantification of the pregnancy-specific beta1-glycoprotein (SP1) by immunoprecipitation techniques: the influence of a cross-reacting high molecular weight alpha2-protein.

Two serum proteins with SP1 determinants were separated by means of size chromatography and preparative zone electrophoresis. One of the proteins had beta1 electrophoretic mobility and an estimated molecular weight of 90,000, and the other had alpha2-mobility and a molecular weight around 400,000. When available antibody preparations to SP1 were used, the high molecular weight protein formed immunoprecipitates only when polyethyleneglycol (PEG) was added to the agarose. It is shown that the high molecular weight protein has a pronounced effect on quantification of SP1 by rocket immunoelectrophoresis, whereas the effect was less pronounced but still considerable when quantification was performed by radial immunodiffusion.

Antigens↗
PubMed1988

Quantification of the genetic risk of environmental mutagens.

Screening methods are used for hazard identification. Assays for heritable mutations in mammals are used for the confirmation of short-term test results and for the quantification of the genetic risk. There are two main approaches in making genetic risk estimates. One of these, termed the direct method, expresses risk in terms of the expected frequency of genetic changes induced per unit dose. The other, referred to as the doubling dose method or the indirect method, expresses risk in relation to the observed incidence of genetic disorders now present in man. The indirect method uses experimental data only for the calculation of the doubling dose. The quality of the risk estimation depends on the assumption of persistence of the induced mutations and the ability to determine the current incidence of genetic diseases. The difficulties of improving the estimates of current incidences of genetic diseases or the persistence of the genes in the population led us to the development of an alternative method, the direct estimation of the genetic risk. The direct estimation uses experimental data for the induced frequency for dominant mutations in mice. For the verification of these quantifications one can use the data of Hiroshima and Nagasaki. According to the estimation with the direct method, one would expect less than 1 radiation-induced dominant cataract in 19,000 children with one or both parents exposed. The expected overall frequency of dominant mutations in the first generation would be 20-25, based on radiation-induced dominant cataract mutations. It is estimated that 10 times more recessive than dominant mutations are induced. The same approaches can be used to determine the impact of chemical mutagens.

Animals↗
PubMed1982

A method for the quantification of cellular composition in lymphoma biopsies.

A method for the classification and quantification of lymphoma cells in non-Hodgkin lymphomas is described. Lymphoma-cell types were defined and used in differential counts of haematoxylin and eosine stained paraffin-embedded sections. The following cell types were distinguished: small lymphoid cells (small lymphocytes and small plasma cells), medium-sized lymphoid cells (round, cleaved and cerebriform lymphocytes, and medium-sized plasma cells), and large lymphoid cells (lymphoblastic, round triple-nucleolated, and pleomorphic types). The intra-observer agreement in the classification of cell types was 43-85%. The agreement in distinguishing small, medium-sized, and large lymphoid cells was 85-92%. In differential counts in contrast to conventional histologic classification all cellular profiles were classified regardless of possible tangential cutting. 92% of the cellular profiles at different sectional planes of the same cells were consistently classified, indicating that tangential cutting of cells only influenced the differential counts to a minor degree. By the quantification of cellular composition in multiple, randomly selected areas, classified as representative at low power magnification, only small intra-lymphoma variations were observed in contrast to marked inter-lymphoma variations. The high reproducibility of lymphoma-cell types in combination with the small intra-lymphoma variation makes the quantifiable method suitable in the histological evaluation of non-Hodgkin lymphomas.

Biopsy↗
PubMed1990

A new sensitive bioassay for precise quantification of interferon activity as measured via the mitochondrial dehydrogenase function in cells (MTT-method).

A biological method for precise quantification of interferons has been developed. The method is based upon the dehydrogenase system of the intact target cells, which will normally convert an artificial substrate, MTT, into formazan (blue), which, in turn, can be measured spectrophotometrically. This conversion is greatly reduced by cytocidal viruses in a dose-dependent manner. The protection of target cells by interferon against challenge virus is reflected in a diminished reduction in the production of formazan, thus giving a very precise method for quantification of interferon. The lowest level of detection is around 0.10 international units. The intra- and inter-assay variability appear to be below 10%. The assay, which makes no use of expensive ingredients, is performed in 96-well micro-trays and read in an inexpensive ELISA-scanner.

Biological Assay↗