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PubMed1982

Calculation factors and reference values for quantitative lipoprotein electrophoresis in childhood.

Agarose gel electrophoresis of lipoproteins combined with quantitative densitometry (Lipidophor) and total cholesterol determination enables the calculation of alpha-, pre-beta-and beta cholesterol. This method is quick, precise and requires less than 100 microliters serum. The calculation factors originally derived from adults were re-evaluated and corrected for children. This was achieved by iterative calculation of the results obtained by quantitative densitometry and by enzymatic determination of the cholesterol contents in electrophoretically separated lipoprotein bands. Thus, calculation factors for children were obtained, which were used for the evaluation of reference values for alpha-, pre-beta- and beta-cholesterol and for the beta/alpha-lipoprotein ratio based on a reference group of 575 healthy children of 5-18 years of age.

Adolescent↗
PubMed1991

A rapid method for the estimation of prostaglandin E2 in intestinal tissues using fluorescence derivatization.

A sensitive spectrofluorimetric method is described to determine small quantities of prostaglandin E2 in complex biological systems as intestinal tissues. The method is based on a solid phase extraction combined with a coupling with a fluorescent marker and measuring the derivatization product by fluorescence densitometry. After mixing the tissue with an ice-cold perchloric acid solution, adjusting the pH, centrifugation and filtration steps, the prostaglandins are retained on a solid phase extraction C18 disposable column. They are eluted with diethylether, derivatized with 4-bromomethyl-7-methoxy-coumarin using potassium carbonate as condensating agent and finally analysed using fluorescence densitometry on silica gel TLC plates. Applying this method, amounts down to 5 ng (per gram wet tissue) could be measured in intestinal tissues, the s.e.m. for replicated total analysis being less than 15%. The foregoing method is applied for the determination of PGE2 released in the intestinal wall under the influence of laxatives.

Animals↗
PubMed1995

A novel quantitative receptor autoradiography and in situ hybridization histochemistry technique using storage phosphor screen imaging.

A new technique of image acquisition for quantitative receptor autoradiography and in situ hybridization histochemistry was developed using storage phosphor screen imaging. This method was at least 4-5 times faster than conventional film densitometry. Two of the advantages of the phosphor screen method are high sensitivity and wide linear range of response. Other aspects of this method were compared with those of conventional densitometry. Use of storage phosphor screen imaging will allow greatly increased speed of pharmacological screening procedures that utilize quantitative autoradiography.

Animals↗
PubMed1982

On the relationship of CSF pleocytosis to immunoglobulin levels as estimated by different techniques.

One might expect a positive correlation between the number of CSF lymphocytes and the relative amount of CSF IgG, especially in cases of local synthesis of IgG within the CNS. However, previous attempts at correlating the number of CSF lymphocytes with IgG levels have yielded varying results. Since it is known that the estimation of CSF IgG levels can vary according to the method of immunoglobulin determination used, we decided to perform the analyses by three separate methods: (1) the commonly used, immunoprecipitation technique of radial immunodiffusion; (2) physico-chemical separation on the basis of hydrated size/charge using alkaline electrophoresis through the molecular sieving effects of polyacrylamide gels, followed by densitometry of the gamma region of Coomassie Blue-stained proteins; (3) separation into constituent Ig heavy chains and light chains on the basis of unfolded chain lengths by molecular sieving using sodium dodecyl sulphate (SDS), followed by densitometry of heavy chains of immunoglobulins having been labelled with the fluorescent dye dansyl chloride. Our results show a correlation of white count with the latter two techniques but not the former. Possible reasons for discrepancies in the literature are discussed with regard to the peculiar physical properties of the selected CSF IgG molecules.

Cerebrospinal Fluid↗
PubMed1996

Effects of continuous percutaneous estradiol administration on skeletal turnover in postmenopausal women: a 1-year prospective controlled study.

The aim of this study was to investigate the short and long term effects of continuous percutaneous administration of estradiol (E2) cream on skeletal turnover in women in surgical postmenopause. Forty women were randomly divided into two groups, one treated with a single daily application of 3 mg/day E2 cream continuously for 12 months, the other receiving placebo cream. Forearm densitometry was performed before and at the end of treatment. Serum E2, osteocalcin (BGP), alkaline posphatase (AP) and urinary N-telopeptide of type I collagen (NTX) were also measured at baseline, month 4 and 12 of the protocol. At month 4, bone turnover was also assessed by evaluating 99mtechnetium-methylene diphosphonate (99mTc-MDP) skeletal uptake. Changes in E2, BGP, AP and NTX as well as 99mTc-MDP skeletal uptake in hormone group vs. placebo were significant after 4 months of treatment. At month 12, proximal site densitometry showed no variation in either group whereas the percentage of variation in distal site measurements resulted significantly different with an increase in the hormone group and a reduction in the placebo group. In conclusion continuous percutaneous administration of E2 cream was effective in rapidly reducing bone turnover in postmenopausal women and in counteracting the accelerated postmenopausal bone loss.

Absorptiometry, Photon↗
PubMed1988

Thermotolerance and heat shock protein induction by slow rates of heating.

The magnitude of thermotolerance and the level of heat shock protein (HSP) expression have been measured in Chinese hamster ovary cells after gradual temperature transients from 37 degrees or 39 degrees to 42 degrees or 43 degrees C. When the level of thermotolerance was measured by clonogenic survival after challenging temperatures between 42 degrees and 43 degrees, substantial thermotolerance was observed. However, when the challenging temperature was raised to 45 degrees C, proportionally less thermotolerance was apparent. Heat shock proteins were quantitated by scanning densitometry of radiographs and, in the case of HSP 70, by immunoassay. Scanning densitometry revealed that low levels of heat shock proteins were synthesized during the heating gradients, but less than after a heat shock at 45 degrees C that delivered an equivalent heat dose. The immunoassay of HSP 70 levels measures both pre-existing and newly synthesized protein, and showed that there was net increase in HSP 70 during two of the heating gradients tested, despite the increase in synthesis noted on the gels. Higher turnover of HSP 70 at the elevated temperatures possibly accounted for the failure to detect a net gain in total protein. In contrast, the total amount of HSP 70 doubled during the 6 hr following a heat shock of 45 degrees for 10 min, an equivalent heat dose to one of the gradients where no net increase in HSP 70 was measured by immunoassay. It appears, then, that tolerance to hyperthemia at 43 degrees C or below may occur under some conditions in the absence of elevated levels of HSP 70, but tolerance to higher temperatures is more closely correlated with increased levels of heat shock proteins. However, even at higher temperatures, our data show disparities between the levels of HSP measured and the thermotolerance expressed.

Animals↗
PubMed2005

Osteoporosis and measurement of bone mass in children and adolescents.

Osteoporosis increasingly is recognized as a pediatric concern. Fragility fractures occur in children and adolescents with genetic disorders and those with a variety of chronic diseases. Others may not fracture in childhood but reach adulthood with a reduced peak bone mass and increased lifelong risk of osteoporosis. This article reviews the indications for pediatric bone density testing, the strengths and limitations of densitometry methods, and the challenges of interpreting the results. The goals are to demystify the densitometry report and to clarify the role of bone density tests in assessing and managing skeletal health in children.

Absorptiometry, Photon↗
PubMed2005

Alternative light source (polilight) illumination with digital image analysis does not assist in determining the age of bruises.

The age of a bruise may be of interest to forensic investigators. Previous research has demonstrated that an alternative light source may assist in the visualisation of faint or non-visible bruises. This project aimed to determine if an alternative light source could be utilised to assist investigators estimate the age of a bruise. Forty braises, sustained from blunt force trauma, were examined from 30 healthy subjects. The age of the bruises ranged from 2 to 231 h (mean = 74.6, median = 69.0). Alternative light source (polilight) illumination at 415 and 450 nm was used. The black and white photographs obtained were assessed using densitometry. A statistical analysis indicated that there was no correlation between time and the mean densitometry values. The alternative light source used in this study was unable to assist in determining the age of a bruise.

Adolescent↗
PubMed2004

Changes of 2-deoxyglucose uptake in the rat auditory pathway after bilateral ablation of the cochlea.

It has been reported that the area of decreased glucose metabolism in the FDG-PET of prelingually deaf children correlates significantly with speech performance after cochlear implantation. In this study, we undertook to confirm changes of glucose metabolism in the cerebral cortex using an animal model with age-matching groups to completely exclude the influence of age differences between the deaf and normal-hearing groups. The cochlea was ablated bilaterally at a postnatal 10-14 days in the deaf groups; 3-4 deaf and normal rats were included at each time point at 1, 2, 4 and 8 weeks and 7 months after ablation. After injecting 2-deoxyglucose intraperitoneally, digitalized autoradiographic images were obtained, and analyzed by using two different methods; 3-dimensional voxel-wise statistical analysis and conventional 2-dimensional densitometry. The hypometabolic area analyzed using 3-dimensional analysis and the differences of optical density between normal and deaf as determined by densitometry were widest and most prominent between 4 and 8 weeks after ablation. Differences were not significant before 2 weeks or after 7 months after ablation. This result shows that the hypometabolic area becomes prominent after a critical period and it decreases as the duration of deafness increases. We believe that cross-modal plasticity may be the mechanism of changes in glucose metabolism and that this result reinforced the usefulness of evaluating hypometabolic area using FDG-PET in deaf children.

Animals↗
PubMed2006

Cross-calibration and minimum precision standards for dual-energy X-ray absorptiometry: the 2005 ISCD Official Positions.

The International Society for Clinical Densitometry (ISCD) Committee on Standards of Bone Measurement (CSBM) consists of experts in technical aspects of bone densitometry. The CSBM recently reviewed the scientific literature on cross-calibration and precision assessment. A report with recommendations was presented at the 2005 ISCD Position Development Conference (PDC). Based on a thorough review of the data by the ISCD Expert Panel during the conference, the ISCD adopted Official Positions with respect to (1) cross-calibration when changing or replacing hardware; (2) the approach to cross-calibration when an entire system is changed to one made by either the same or a different manufacturer; (3) when no cross-calibration study or bone mineral density (BMD) comparison is done between facilities; and (4) the minimum acceptable precision for an individual technologist. We present here the ISCD Official Positions on these topics that were established as a result of the 2005 PDC, together with the associated rationales and supportive evidence.

Absorptiometry, Photon↗
PubMed2005

Soluble alpha2-macroglobulin receptor is increased in endotracheal aspirates from infants and children after cardiopulmonary bypass.

OBJECTIVE: Cytokine dysregulation contributes to the systemic inflammatory response after cardiopulmonary bypass. Clearance of cytokine binding proteins may be important in the resolution of inflammation. Our aim was to determine whether the cytokine binding protein alpha 2 -macroglobulin and its soluble receptor were upregulated in endotracheal aspirates from infants and children undergoing cardiopulmonary bypass. METHODS: Seventy tracheal aspirates were collected before and after cardiopulmonary bypass from 35 infants and children undergoing surgical correction of congenital heart defects. alpha 2 -Macroglobulin and the soluble alpha 2 -macroglobulin receptor were identified by Western blot. With the use of multi-analyte cytokine profiling, pro-inflammatory and anti-inflammatory cytokines were quantified, normalized to total protein, and expressed as ratios. Paired t tests and Wilcoxon signed-rank tests were performed between prebypass and postbypass samples. Correlations were examined among alpha 2 -macroglobulin, soluble alpha 2 -macroglobulin receptor, cytokine ratios, and the clinical variables of cardiopulmonary bypass, aortic crossclamp, and circulatory arrest times. RESULTS: alpha 2 -Macroglobulin increased by 50% (mean densitometry increase 82,683 +/- 184,594, P = .012), and soluble alpha 2 -macroglobulin receptor increased by 17% (mean densitometry increase 506,148 +/- 687,037, P = .0001) after cardiopulmonary bypass. The ratio of interleukin-8/interleukin-4 increased by 136% ( P = .0001), and interleukin-8/interleukin-10 increased by 102% ( P = .001). The increase in soluble alpha 2 -macroglobulin receptor was positively correlated with the ratios of interleukin-8/interleukin-4 and interleukin-8/interleukin-10. There were no statistically significant positive correlations between the increase in alpha 2 -macroglobulin or soluble alpha 2 -macroglobulin receptor and measured clinical variables. CONCLUSIONS: We report for the first time the upregulation of alpha 2 -macroglobulin and soluble alpha 2 -macroglobulin receptor in tracheal aspirates after cardiopulmonary bypass in infants and children. Soluble alpha 2 -macroglobulin receptor correlates with increased alpha 2 -macroglobulin and a disproportionate increase in pro-inflammatory to anti-inflammatory cytokine ratios.

Age Factors↗
PubMed1999

An ordered metastable phase in hydrated phosphatidylethanolamine: the Y-transition.

By using time-resolved X-ray diffraction, differential scanning calorimetry and scanning densitometry, we observed rapid formation at low temperature of a metastable ordered phase, termed LR1 phase, in fully hydrated dihexadecylphosphatidylethanolamine (DHPE). The LR1 phase has the same lamellar repeat period as the gel Lbeta phase but differs from the latter in its more ordered, orthorhombic hydrocarbon chain arrangement. It forms at about 12 degrees C upon cooling and manifests itself as splitting of the sharp, symmetric wide-angle X-ray peak of the DHPE gel phase into two reflections. This transition, designated the 'Y-transition', is readily reversible and proceeds with almost no hysteresis between cooling and heating scans. Calorimetrically, the LR1-->Lbeta transition is recorded as a low-enthalpy (0.2 kcal/mol) endothermic event. The formation of the LR1 phase from the gel phase is associated with a small, about 2 microl/g, decrease of the lipid partial specific volume recorded by scanning densitometry, in agreement with a volume calculation based on the X-ray data. The formation of the equilibrium Lc phase was found to take place from within the LR1 phase. This appears to be the only observable pathway for crystallisation of DHPE upon low-temperature incubation. Once formed, the Lc phase of this lipid converts directly into Lbeta phase at 50 degrees C, skipping the LR1 phase. Thus, the LR1 phase of DHPE can only be entered by cooling of the gel Lbeta phase. The data disclose certain similarities between the low-temperature polymorphism of DHPE and that of long-chain normal alkanes.

Calorimetry, Differential Scanning↗
PubMed1999

Slow relaxation of the sub-main transition in multilamellar phosphatidylcholine vesicles.

The influence of ionic strength and equilibration time on the appearance of the sub-main transition in fully hydrated multilamellar vesicles composed of phosphatidylcholines has been investigated by means of calorimetry and densitometry. The heat capacity measurements show that the transition enthalpy of the sub-main transition is affected by both salt concentration (KCl) and equilibration time. The small heat capacity peak appearing in vesicles made in pure water is significantly increased upon addition of salt. Furthermore, equilibration of the multilamellar vesicles at low temperatures for several weeks results in a pronounced enhancement of the transition enthalpy of the sub-main transition. Neither salt concentration nor equilibration time affected the transition temperature of the sub-main transition. In the densitometry measurements a small volume change is detectable for high salt concentrations. In order to gain further insight into the physical mechanisms involved in the sub-main transition, a Monte Carlo computer simulation study has been carried out using a microscopic model. The combined experimental and simulation results suggest that the sub-main transition involves an acyl chain disordering of phospholipids in lipid bilayer regions that are characterized by a locally decreased lateral pressure most likely caused by a curvature stress.

Calorimetry, Differential Scanning↗
PubMed1987

Analysis of lipids by one-dimensional thin-layer chromatography.

A high-efficiency silica gel, (type HLF) thin-layer chromatography plate (HETLC), linear high-performance thin-layer chromatography plate (HPTLC) and densitometry method has been devised in order to resolve the major lipid classes obtained from rat brain tissues. This methodology, which has largely overcome prior problems, enhances the opportunity for assessing the glycerophospholipid and glycolipid compositions of tissues. DEAE-Sephadex column chromatography was used to separate the crude lipids extract into neutral and acidic lipid fractions. The lipid fractions were then spotted on separate HPTLC and HETLC plates and chromatographed in one dimension using one solvent system. Quantitation was by in situ densitometry with the absolute quantity of the lipid classes determined from co-chromatographed standards. Sensitivity was increased by using cupric sulfate reagent, which was found to be more sensitive than the conventional cupric acetate reagent. This method is applicable to a broader separation of lipid classes and has improved sensitivity.

Animals↗
PubMed1987

Long-term follow-up of lens changes with Scheimpflug photography in diabetics.

This study was designed to document and quantify changes in lens clarity over 24 months in a group of diabetic patients. One hundred thirty-four type I and type II diabetics of 3 months' to 45 years' duration with an average age of 53.5 +/- 7 years volunteered to participate in this prospective study. Patients were evaluated upon entry and at 6-month intervals. Scheimpflug lens photographs (Topcon SL45) were taken at each visit. All photographs were evaluated by densitometry which allowed quantification of the light scattering in the various lens layers. A significant and progressive (4-7% every 6 months) increase in light scattering was observed in the lens anterior superficial lens cortex over 24 months. The rate of change in lens clarity was similar in all patients regardless of the clinically observable lens change type (nuclear, cortical, posterior subcapsular, or mixed). Patients who were younger at enrollment, having diabetes of shorter duration and higher glycosylated hemoglobin values (a measure of long-term glucose control), were identified to be at greater risk of having increased densitometry values in the anterior superficial lens cortex. Only a few patients had significant changes in visual acuity during 24 months, and the correlation of superficial cortical lens clarity changes to clinical cataract formation and visual impairment remains to be established.

Adolescent↗
PubMed2000

Discrete reduction of type I collagen thermal stability upon oxidation.

The oxidation of acid-soluble calf skin collagen type I caused by metal-dependent free radical generating systems, Fe(II)/H2O2 and Cu(II)/H2O2, was found to bring down in a specific, discrete way the collagen thermal stability, as determined by microcalorimetry and scanning densitometry. Initial oxidation results in splitting of the collagen denaturational transition into two components. Along with the endotherm at 41 degrees C typical for non-oxidized collagen, a second, similarly cooperative endotherm appears at 35 degrees C and increases in enthalpy with the oxidant concentration and exposure time, while the first peak correspondingly decreases. The two transitions at 35 and 41 degrees C were registered by densitometry as stepwise increases of the collagen-specific volume. Further oxidation results in massive collagen destruction manifested as abolishment of both denaturational transitions. The two oxidative systems used produce identical effects on the collagen stability but at higher concentrations of Cu(II) in comparison to Fe(II). The discrete reduction of the protein thermal stability is accompanied by a decrease of the free amino groups, suggestive of an oxidation attack of the side chains of lysine residues. Since the denaturation temperature of collagen shifts from above to below body temperature (41 degrees C-35 degrees C) upon oxidation, it appears important to account for this effect in a context of the possible physiological implications of collagen oxidation.

Animals↗
PubMed2003

Bone mineral density--clinical use and application.

Clinical application of bone densitometry has led to increased patient awareness of this increasingly prevalent disease. With bone densitometry, it is possible for clinicians to diagnose osteoporosis before the first fracture has occurred; predict risk for fracture in men, postmenopausal women, and in patients receiving glucocorticoids; and can be used as a surrogate marker to follow the efficacy of therapies and to examine those patients who might be osteoporosis-specific therapeutic non-responders.

Aging↗
PubMed2002

Advanced fibre optical scanning in thin-layer chromatography for drug identification.

A systematic toxicological analysis procedure using high-performance thin layer chromatography in combination with fibre optical scanning densitometry for identification of drugs in biological samples is presented. Two examples illustrate the practicability of the technique. First, the identification of a multiple intake of analgesics: codeine, propyphenazone, tramadol, flupirtine and lidocaine, and second, the detection of the sedative diphenhydramine. In both cases, authentic urine specimens were used. The identifications were carried out by an automatic measurement and computer-based comparison of in situ UV spectra with data from a compiled library of reference spectra using the cross-correlation function. The technique allowed a parallel recording of chromatograms and in situ UV spectra in the range of 197-612 nm. Unlike the conventional densitometry, a dependency of UV spectra by concentration of substance in a range of 250-1000 ng/spot was not observed.

Chromatography, Thin Layer↗