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PubMed1978

Electroimmunoassay, radioimmunoassay, and radial immunodiffusion assay evaluated for quantification of human apolipoprotein B.

We examined three immunoassay techniques for measuring apolipoprotein B in serum and major lipoprotein density fractions from normolipidemic and hyperlipoproteinemic persons, comparing values by electroimmunoassay, radioimmunoassay, and radial immunodiffusion assay with those determined gravimetrically. Electroimmunoassay is faster and simpler than radioimmunoassay, and equally precise (within- and between-assay coefficients of variation for both were 5 and 7%, respectively). All the immunoassays gave results that agreed with those by gravimetry for normolipidemic sera and the corresponding lipoprotein density fractions, but only electroimmunoassay results agreed with those by gravimetry for apolipoprotein B in lipoproteins of d less than 1.019 g/ml isolated from hypertriglyceridemic patients. Concentrations of apolipoprotein B in plasma, determined by electroimmunoassay in a population of normal persons and patients with primary hyperlipoproteinemias, were: normals, 980 +/- 200; type I, 700 +/- 160; type IIa, 2000 +/- 260; type IIb, 2180 +/- 300; type III, 1300 +/- 340; type IV, 1470 +/- 400; and type V, 1550 +/- 390 mg/liter (mean +/- SD). Lipoprotein density fractions from the hyperlipoproteinemic patients each had a characteristic distribution of free and associated forms of lipoprotein family B. The absolute concentration and distribution of apolipoprotein B between the free and associated forms of lipoprotein B may represent a useful indicator of the underlying biochemical defect(s).

Adult↗

PubMed2005

Estimation of cardiac event risk by MDCT.

Coronary calcifications are specific markers for coronary atherosclerosis. The amount of coronary calcium is related to the likelihood of vulnerable plaques. Vulnerable plaques may rupture and may result in sudden coronary thrombus formation, occlusion, ischemia and ventricular fibrillation and finally cardiac death. Therefore, it is reasonable to believe that the risk of cardiac events can be assessed by the quantification of the extent of coronary calcium. However, until now, the predictive value of coronary calcium and the advantage over conventional risk factors has not yet been proven by any prospective cohort study. In practice uncertainty exists in the group of patients with an intermediate risk for cardiac events. In this particular cohort it is likely that the assessment of coronary atherosclerosis may help in the decision to initiate or discard a specific therapy. For this purpose it has been suggested to replace the Framingham age score by a score corrected by the amount of coronary calcium. Follow-up investigations may be helpful in the short term to determine the efficiency of different therapeutical options. To determine a significant progression of the amount of coronary calcium, the absolute mass should be determined in a period of 1 year.

Age Factors↗

PubMed1976

Quantitative immunoautoradiography at the cellular level. II. Absolute measurements using labeled standard cells as a source of reference.

A quantitative autoradiographic method is presented for determining absolute amounts of 125I-labeled compounds on the surface of individual cells. Autoradiographic evaluation of single cell radioactivity is accomplished by comparing the silver grain densities over the specimen and a radioactive standard being exposed simultaneously. In order to obtain a reference source of comparable physical properties, surface-radioiodinated human erythrocytes are used, the radioactivity of which is determined in a crystal counter. A simple enzymatic method for preparing such standard erythrocytes of very uniform label density is described. Numerous experimental advantages derived from the use of the standard are discussed and demonstrated by examples employing various exposure times and different radioactive standards. Hereby, very similar results were obtained when the number of A-antigenic sites was quantified on single erythrocytes in different experiments. The quantification of membrane-bound IgM on single human lymphocytes is shown as another application of this scheme.

Autoradiography↗

PubMed2002

Quantification of wall shear stress in large blood vessels using Lagrangian interpolation functions with cine phase-contrast magnetic resonance imaging.

Arterial wall shear stress is hypothesized to be an important factor in the localization of atherosclerosis. Current methods to compute wall shear stress from magnetic resonance imaging (MRI) data do not account for flow profiles characteristic of pulsatile flow in noncircular vessel lumens. We describe a method to quantify wall shear stress in large blood vessels by differentiating velocity interpolation functions defined using cine phase-contrast MRI data on a band of elements in the neighborhood of the vessel wall. Validation was performed with software phantoms and an in vitro flow phantom. At an image resolution corresponding to in vivo imaging data of the human abdominal aorta, time-averaged, spatially averaged wall shear stress for steady and pulsatile flow were determined to be within 16% and 23% of the analytic solution, respectively. These errors were reduced to 5% and 8% with doubling in image resolution. For the pulsatile software phantom, the oscillation in shear stress was predicted to within 5%. The mean absolute error of circumferentially resolved shear stress for the nonaxisymmetric phantom decreased from 28% to 15% with a doubling in image resolution. The irregularly shaped phantom and in vitro investigation demonstrated convergence of the calculated values with increased image resolution. We quantified the shear stress at the supraceliac and infrarenal regions of a human abdominal aorta to be 3.4 and 2.3 dyn/cm2, respectively.

Adult↗

PubMed2001

Nondestructive, in vitro quantification of crown margins.

STATEMENT OF PROBLEM: It is important that artificial crowns fit the prepared tooth accurately, as marginal deficiencies are predisposed to plaque accumulation and lead to increased risk of periodontal disease. Various methods of evaluation for marginal fit are described in the literature, but most approaches are limited by destructive methods of assessment and/or small points of measurement. PURPOSE: This study compared, in vitro, the marginal fit of 4 types of complete crowns on human premolar teeth with the use of nondestructive profilometry. This method determined whether fit was influenced by type of crown or surface morphology of the tooth, namely, grooved or ungrooved surfaces. MATERIAL AND METHODS: Four groups of specimens were prepared for complete crowns: group BA, bonding alloy with chamfer finish line; group G, gold alloy with chamfer finish line; group PC, porcelain with a chamfer finish line; and group PS, porcelain with a shoulder finish line. Two profiles of grooved mesial and ungrooved distal surfaces of the teeth were performed: (1) teeth prepared for each type of crown and (2) teeth with crowns seated but not cemented. Marginal fit (absolute marginal discrepancy) from the finish line edge of the tooth preparations to crown edges (CE) and leading edges (LE) of crowns were measured. RESULTS: A 2-way analysis of variance for crown type and tooth surface morphology revealed significant differences between crown types for all measurement parameters, except vertical LE. The effect of surface morphology was not significant, except for vertical LE (P<.05). For all parameters, except vertical LE, the ranking of marginal fit discrepancies from greatest to least was as follows: group PC, G, BA, and PS. For vertical LE distances, the ranking was PS, BA, G, and PC (P<.05). CONCLUSION: Profilometry was used as a nondestructive, accurate method of evaluating the absolute marginal fit of different types of crowns. Marginal fits varied continuously around the circumference of each crown and made clinical assessment of fit accuracy subjective and arduous.

Analysis of Variance↗

PubMedDate not supplied

Contribution to the quantification of two dimensional spaces in endocranial CT and MR in patients with epilepsy.

OBJECTIVE: The aim of this study is to show the connection between the morphometrical analysis of the width of the lateral ventricles measured in CT and MR images and the power of the frequency spectra of EEG signals in a total of 120 patients with epilepsy suffering from complex partial seizures without the clear localization and without the visible lesion. More than 800 CT and MR images of 120 patients with epilepsy were analyzed by the two-dimensional morphometrical analysis according to the methods presented in this study. Indices of the relation between the width of the right and left lateral ventricle were normally distributed. EEG frequency analysis of 8 channels, each of 32 seconds duration, was performed using 128 Hz sampling rate and FFT (Fast Fourie Transform) in 2 groups of patients consisting of 12 patients each: the first group with the significantly greater dimensions of the left lateral ventricle, and the second with the significantly greater size of the right one. Preliminary results of the analysis have shown that the absolute power of the theta frequency band was significantly increased in all brain regions in both groups of patients, and the relative ones in the parietocentral region bilaterally and in the left temporooccipital regions in patients with the wide lateral ventricle in the left hemisphere.

Cerebral Ventricles↗

PubMed2000

Simultaneous, quantitative analysis of UDP-N-acetylglucosamine, UDP-N-acetylgalactosamine, UDP-glucose and UDP-galactose in human peripheral blood cells, muscle biopsies and cultured mesangial cells by capillary zone electrophoresis.

The aim of this study was to develop and evaluate a capillary zone electrophoretic (CE) procedure for the accurate quantification of the UDP-hexosamines as well as for the corresponding UDP-hexoses in samples from various biological origins. Testing different buffer conditions, voltages, capillary dimensions and temperatures, optimal results were achieved with a 90 mM borate buffer, pH 9.0, at 18 degrees C and 15.5 kV in an uncoated fused-silica capillary of 50 cm x 50 microm and a detection wavelength of lambda = 262 nm. The total procedure, i.e., including variations of the sample preparation, showed coefficients of variation for the peak areas between 4. 1% and 10.4% in mesangial cells (n = 7) and between 7.8 and 10.3% (n = 6) in leukocytes for the components of interest. To improve precision, an internal standard was used for calibration. The limit of detection for all compounds is an absolute amount of 180 fmol, sufficient for the precise analysis of UDP-sugars in a limited amount of biological samples, such as human leukocytes (obtained from a 10 mL blood sample), muscle biopsies (< or = 100 mg), and mesangial kidney cells (ca. 2.5 x 10(5) cells). This reproducible, quantitative analysis of all four UDP-sugars from various biomedically relevant origins by CZE is a definite improvement over the generally used high performance liquid chromatography (HPLC) procedures. The CZE method allows the study of the flux through the hexosamine pathway in diabetes mellitus and other diseases in a simple, quantitative and accurate way.

Blood Cells↗

PubMed1983

[Quantification of the function of the left ventricle using 2-dimensional echocardiography].

Left ventricular volumes and the ejection fraction can be determined by two-dimensional echocardiography. Because of methodological problems, cineventriculographic normal values can not be transferred to two-dimensional echocardiography. Therefore, normal values for two-dimensional echocardiographically determined left ventricular volumes and the ejection fraction were established in 55 normal controls. Basing on these volumes, the sensitivity and specificity of two-dimensional echocardiography for detection of impaired left ventricular function was analysed and compared with results from cineventriculography. Sensitivity for detection of a reduced ejection fraction was 84%, specificity 89% and predictive accuracy 98%. Thus, two-dimensional echocardiography can be used as a screening method for analysing left ventricular function. Analysis of beat-to-beat variation revealed that for two-dimensional echocardiography 3 consecutive beats should be analysed because evaluation of 5 instead of 3 beats increased reliability only by less than 1%. It was necessary to analyse the day-to-day variations. To separate a random error from a non-random error for an individual change, an absolute change of volumes of more than 10-12% and of ejection fraction of more than 10% had to be observed. Group changes can of course be smaller and yet significant. Intraobserver variation was not significant and below 5%. However, interobserver variability must be considered. This depends on observer experience. For a 4-chamber view no significant variability was observed, but for the RAO-equivalent view the observer variation was significant for end-diastolic and end-systolic volume. For the ejection fraction no significant difference was found. Two-dimensional echocardiography can be used for pharmacodynamic studies if percentage changes instead of absolute changes are listed.

Cardiac Output↗

PubMed1998

Detection and quantification of group 4 allergens in grass pollen extracts using monoclonal antibodies.

BACKGROUND: Grass pollen extracts are complex mixtures consisting of different major allergenic and non-allergenic components. Phl p 4 is an important allergen, because more than 75% of grass pollen allergic patients produce specific IgE antibodies against group 4 allergens. OBJECTIVE: This study was designed to investigate the specificity of monoclonal antibodies (MoAbs) produced against Phl p 4 and to verify the presence of group 4-like proteins in different grass pollen. Furthermore the usefulness of MoAbs for quantification of group 4 allergens was studied. METHODS: Group 4 analogues were investigated by immunoblotting and ELISA inhibition using three MoAbs. The specificity of antibodies was studied using isolated group 1 and group 5 allergens. Quantification of group 4 allergen was achieved by a two-site solid-phase ELISA. Phl p 4 was purified from whole pollen extract by chromatographic or electrophoretic techniques and used as standard. RESULTS: The MoAbs studied bound strongly to proteins from timothy grass pollen extract at a mw of 55 kDa and a pI of 9.0-9.3. Phl p 4 homologes with similar mw were detected in Dactylis glomerata, Festuca pratensis, Holcus lanatus, Poa pratensis, Lolium perenne. Epitope mapping showed that all three MoAb recognized unrelated regions on Phl p 4. A two-site binding ELISA using MoAbs was developed for determination of Phl p 4 in Phleum pratense extracts. The method was able to evaluate group 4 in mass units with a working range between 150 and 2000 ng/mL. The absolute amounts of group 4 in extracts of several grasses varied considerably but was always-less than 1% of the total protein. CONCLUSION: Group 4 homologes are present in the various grass extracts but to different extents. The group 4 ELISA could be very useful as a additional tool for providing information concerning the composition of grass pollen extracts.

Allergens↗

PubMed1998

Quantitative techniques for lesion load measurement in multiple sclerosis: an assessment of the global threshold technique after non uniformity and histogram matching corrections.

The quantitative assessment of abnormalities on brain MRI (magnetic resonance imaging) in multiple sclerosis (MS) provides a widely used endpoint in monitoring treatment efficacy. Semi-automated intensity thresholding (global thresholding) is an established method of lesion segmentation, but it is limited by the heavy dependence of derived volumes on the chosen intensity threshold. Inconsistency in threshold choice substantially contributes to its suboptimal reproducibility. A potential improvement to global thresholding is to utilize the histogram matching algorithm to correct for variations in scanner sensitivity. This study evaluated whether or not a single intensity threshold could then be applied across multiple histogram matched images. Eight MS patients were scanned at baseline and after nine months. After non-uniformity correction, the histogram matching correction was applied, reducing the mean absolute percentage variation in normal appearing white matter signal intensity from 15.2 to 3.8% for baseline scans and from 11.9 to 2.1% across serial studies. Lesion volumes were measured with the global threshold technique using a single threshold selected from one scan. A local thresholding technique (contouring) was also performed as a gold standard measure. Agreement between techniques for baseline lesion volumes was only moderate with an intra-class correlation coefficient (ICC) of 0.46 and there was little agreement for change in lesion volume (ICC = 0.17), reflecting inconsistencies in the volume of non-lesion regions included by the threshold. Agreement was improved by deleting non-lesion regions, but this was time consuming and less reproducible than contouring method. At present, the contour technique remains a more appropriate method for lesion load quantification.

Journal Article↗

PubMed1995

Measurement of thermally produced volatile alkanes: an assay for plant hydroperoxy fatty acid evaluation.

A new method designed to monitor lipid peroxidation in plants has been set up with soybean hypocotyl/radicles. The hydroperoxy fatty acids present in situ are converted by rapid thermal treatment (80 s and 210 J g-1) of the biological sample into ethane and n-pentane, which are analyzed by gas chromatography. The method has been directly calibrated by quantification of the hydroperoxy fatty acids by silica-phase HPLC analysis of their reduced hydroxy derivatives. Hypocotyl/radicles from the two soybean cultivars Argenta and Soriano were submitted to various chemical oxidative treatments and were analyzed for both thermally produced volatile alkanes and hydroperoxy fatty acid levels. Our results showed that ethane and n-pentane production are in both cases closely correlated with linolenic as well as linoleic acid hydroperoxide levels (P < 0.001). Within a given plant material, thermal conversion of both hydroperoxides into alkanes occurred with yields which were not dependent on the oxidative treatment. These yields are however functions of the biological material since in Soriano and Argenta cultivars they were around 6 and 25%, respectively. Taking into account the last point, the alkane test cannot be used to directly quantify the absolute lipid hydroperoxide levels of plant tissues but it is convenient to monitor the peroxidative phenomenon as it occurs. The assay is easy and rapid to perform (analysis of 50 samples per day) since no sample preparation is needed, and the low detection limit (20 pmol of alkane g-1) permits the analysis of small samples.

Alkanes↗

PubMed2026

A comparative evaluation of multiple enlarged perivascular space segmentation tools.

BACKGROUND: Enlarged perivascular spaces (ePVS) are a marker of cerebral small vessel disease, potentially reflecting reduced waste clearance. Because manual quantification is unfeasible in large datasets, we developed and evaluated an automated tool. METHODS: Detection Of Regions of Enlarged perivascular Spaces (DORES), a 3D nnU-Net-based deep learning algorithm was developed for ePVS segmentation using T1-weighted and fluid-attenuated inversion recovery magnetic resonance imaging (MRI). DORES was developed in two stages: an initial model trained on 35 manually segmented scans and a final model on 1460 pseudo-labeled sessions from the Vanderbilt Memory and Aging Project (VMAP). A subset of VMAP participants with 3 T brain MRI underwent whole-brain manual ePVS tracing (n = 35, 73 ± 9 years, 51% male) and visual rating (n = 388, 71 ± 8 years, 54% male) by a neuroradiologist. DORES was evaluated and compared against three other segmentation tools using Dice and F1 scores, absolute volume and element differences, correlation, and agreement. External validation used an Alzheimer's Disease Neuroimaging Initiative 3 subset with manual tracings (ADNI3, n = 18, 73 ± 9 years, 67% female). RESULTS: DORES achieved Dice scores of 0.61 ± 0.16 (white matter) and 0.72 ± 0.08 (basal ganglia) in VMAP, with strong correlations and agreement for ePVS count and volume. Performances modestly declined in ADNI3 across algorithms. Scanner-stratified analyses showed stronger correlations for Philips versus Siemens images in the basal ganglia, indicating scanner-dependent differences in measurement consistency. CONCLUSIONS: DORES provides a multimodal nnU-Net-based pipeline for ePVS segmentation in older adults. The model demonstrates robust within-cohort performance and reasonable external validity, though scanner-related effects limit application across sites.

Humans↗

PubMed2004

Habituation to galvanic vestibular stimulation.

OBJECTIVE: To examine the response decline that occurs upon repetitive galvanic vestibular stimulation (GVS) and hampers long-term clinical evaluations. MATERIAL AND METHODS: This was a prospective experimental study conducted in a tertiary referral centre. In a previous study we developed a standardized procedure for reproducible quantification of galvanic-induced body sway (GBS). The most reproducible responses were found using a continuous 1-cosinusoidal stimulus (0.5 Hz; 2 mA) preceded by a pre-habituating stimulus. This binaural prestimulation reduced the short-term (<5 min) response decline to a non-significant level. The response decline without prestimulation was interpreted as habituation to the galvanic stimulation. In the present study we evaluated possible long-term habituation to GVS, which may hamper longitudinal clinical evaluations. Possible long-term habituation using the short-term habituating prestimulus concept was studied by quantifying GBS in 40 subjects at 5 consecutive time points. Subjects were subdivided into four equal groups who were tested with four different time intervals between the five measurements, ranging from 1 day to 2 weeks. RESULTS: The absolute test results did not vary with the time interval (p=0.217; repeated measurement test). Irrespective of the time interval between the tests, habituation occurred after the first stimulation and remained stable at all consecutive measurements. GVS habituation did not depend on either the degree of daily life activity (moderate practice of sport) or on gender. CONCLUSION: The current protocol, using a prehabituating binaural stimulus, showed that reproducible assessment of the GVS over a time course of days to weeks was possible starting from the second test.

Adult↗

PubMed1978

A methodological study for the quantification and the control of the physico-chemical processes occurring during cell fixation. I. The development of a new technology.

Fixation in a traditional sense means the immersion of biological material into a chemical fluid. For permanent preservation the fixative is always "offered" (1) in excess of the cell sample, and the process of fixation is influenced by (2) chemical impurities of the fixative fluid. Both factors influence the succeeding dyeing of cells. In order to avoid these uncontrolled criteria, a new technology for controlled cell fixation has been developed, whereby freshly prepared formaldehyde and methanol gas in an "inert" gas-flow of helium was applied to thin membranes by aid of a capillary flow-in technique. The instrumental equipment consists of (1) an ultra-high vacuum flow-apparatus with a total-pressure measuring unit, (2) a gas-supply device, (3) a mass spectrometer including a pump system, and (4) a Teflon and/or glass-gas chamber for the treatment of synthetic (Hostaphan foils) or biological membranes (mesenterium) with formaldehyde as the fixative gas. The amount of "offered", adsorbed, absorbed, diffused, and desorbed fixative gas could be absolutely estimated after the saturation of the membranes with an "on-line" operating "inert" mass spectrometer of the Omegatron type. The gas treatment of the Hostaphan foils with formaldehyde showed that nearly all adsorbed gas molecules could be desorbed. In contrast to native membranes the greatest proportion of the gas molecules adhered to the biological surface, and only a small quantity were desorbable. Physisorption or physisorption and chemisorption occured depending on the adsorber surface property. A monolayer of formaldehyde of 5.10(14) to 1.10(15) molecules per 10(16) A2 surface area can be postulated on the basis of these preliminary results. This value corresponds to a mass of about 5.10(-8) g CH2O. It resulted in an area-coverage ratio of CH2O molecules per cell of 10(9):1. The membrane surface facing the gas side always amounted to 1 cm2. A fixative gas concentration of 10(6) molecules/cm3, and therefore a degree of coverage of less than 1/1000 monolayer can be estimated absolutely. For a precise determination of the degree of fixation, further experiments and the evaluation of additional physico-chemical parameters are necessary.

Adsorption↗

PubMed2005

Protein quantification and its tolerance for different interfering reagents using the BCA-method with regard to 2D SDS PAGE.

Measuring the protein content of a sample is a mandatory and frequently practiced procedure in the lab. Although the procedure is quite simple and convenient to perform with commercially available kits, incompatible reagents in the lysate can cause problems in the quality of measurement. Unfortunately these reagents are cornerstones of high efficiency lysing buffers, e.g. high amounts of urea or beta-mercaptoethanol. In this study we addressed the tolerance of the well-known BCA-assay (bicinchoninic acid) to various reagents in different concentrations, with special regard to a subsequent 2D-gelelectrophoresis. As a result, the kit is incompatible with the recipes of regular 2D-buffers. Also, when mixing two different reagents interfering effects will occur in a non-predictable way. Therefore we established a new method to quantify protein content in lysates ready for 2D-gelelectrophoresis: by mixing an aliquot with SDS, an equilibration is performed to that the sample can be run on a regular 1D SDS PAGE. Image analysis following fluorescence staining (SYPRO Ruby) reveals the absolute protein content in comparison to a BSA dilution curve processed accordingly.

Electrophoresis, Gel, Two-Dimensional↗

PubMed1992

Accuracy of quantification of mandibular condyle displacement in digitally subtracted linear tomograms.

Using a TMJ skeletal phantom, we assessed validity and reliability of digitally subtracted linear tomographic images to quantify condylar position changes. Horizontally corrected frontal and lateral tomographic images were made with the condyle in a 'centred' position and displaced by 1, 2 and 3 mm increments in two of three directions (inferior, and posterior, or lateral). Film images were sequentially subtracted and then randomized so that observers were blinded to the amount and direction of condylar movement. Averages of three measurements of the dark bands representing condylar shifts were made using a digitizing tablet. The study utilized a nested design where the series of film images was subtracted twice and each subtraction was read twice by two examiners. We repeated the study with a second series of films treated in an identical manner. Average differences from expected values were similar for frontal and lateral techniques and all directions and increments of displacement. Typical average difference for any increment was less than 0.1 mm. Standard deviations in measures were similar across techniques and increments and were typically less than 0.1 mm. Significant variation in the absolute value of differences between measured and expected values by direction of condylar displacement was attributed to greater accuracy of registration on the vertical axis for frontal images. A significant source of variation in the study design element 'film set' was attributed to errors in repositioning the phantom.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗

PubMed1996

Quantification of cardiac and tissue iron by nuclear magnetic resonance relaxometry in a novel murine thalassemia-cardiac iron overload model.

OBJECTIVE: To determine whether nuclear magnetic resonance (NMR) relaxation parameters can be used to quantify iron in tissues, the relationship between NMR spectrometric T2 relaxation measurements and tissue iron concentration were verified in a novel murine cardiac iron overload model. METHODS: Congenital heterozygous thalassemic mice and controls were injected with intraperitoneal iron or saline and were sacrificed at three weeks. Samples of liver, heart and peripheral muscle were subjected to NMR relaxation measurements and continuous distribution analysis. Tissue ferritin levels were determined with immunoadsorbance techniques, and elemental iron was assayed by flame atomic absorption. Tissues were analyzed pathologically with hematoxylin and eosin and Prussian blue staining to confirm the localization of iron. RESULTS: This murine iron loading model was uniquely successful in loading iron into the major organs, especially the heart, and produced significant reductions in T1 and T2 NMR relaxation values. There was a good correlation between soluble ferritin and total iron levels (r=0.92), indicating that there is a constant and significant fraction of total iron present in ferritin irrespective of absolute iron concentrations. Regression analysis between total iron content and T2 relaxivity showed a linear relationship (r=0.96), suggesting that the T2 relaxation parameter is related to tissue iron concentration. The regression relationship suggested that NMR can detect iron levels as low as 0.1 mg/g of tissue. CONCLUSIONS: Parenteral iron loading in mice produces unique iron overload in major organs, including the heart. Local iron deposition is detectable by NMR relaxometry at 0.1 mg/g or higher. There is a linear relationship between iron concentration and T2 relaxivity. Thus, NMR may be an important and useful clinical tool to quantify iron excess in various pathobiological states of human disease due to iron overload, including heart disease.

Animals↗

PubMed1986

A new approach to quantification of Sertoli cells that avoids problems associated with the irregular nuclear surface.

A new approach to quantification of Sertoli cells is described. The number of Sertoli cells per testis was calculated from the number of spermatids per testis, the number of spermatids per Sertoli cell apex, and the correction for the lifespan of spermatids enumerated per testis. To evaluate this method under different physiological conditions, testes from 28 adult (4-20-year) stallions obtained in the nonbreeding season (December-January) and from 28 adult stallions in the breeding season (June-July) were compared. Number of Sertoli cells per gram parenchyma was similar between seasons. However, the number of Sertoli cells per testis was significantly greater in the breeding season. In verification of this method, the number of spermatids per Sertoli cell apex was similar to that calculated as the ratio of spermatids to Sertoli cell in the same stallions. Likewise, absolute values similar to those of other approaches further verify the validity of this approach.

Animals↗