Accurate Weight Measurement Research Articles

Comparison of lesion-to-cerebellum uptake ratios and standardized uptake values in the evaluation of lung nodules with 18F-FDG PET

To evaluate the clinical performance of the lesion-to-cerebellum uptake ratio (LCR), a semiquantitative index for differentiating malignant from benign lung nodules with [F]fluorodeoxyglucose positron emission tomography (F-FDG PET). Thirty-six patients (16 females, 20 males; median age, 73 years; range, 41-87 years) with 42 known or suspected malignant lung nodules underwent whole-body PET imaging after an intravenous injection of a mean dose of 543+/-69 MBq (14.7+/-1.9 mCi) of F-FDG. The standardized uptake value (SUV) and the LCR were calculated for each nodule and receiver operating characteristic (ROC) curves were analysed using the ROCKIT 0.9B software package. Surgical pathology and follow-up with serial computed tomography scans for at least 24 months revealed 18 malignant lung lesions and 24 benign lesions less than 3.0 cm in size. The mean LCR was 0.70+/-0.40 for malignant nodules and 0.23+/-0.12 for benign nodules (P<0.001, two-tailed test). The area under the estimated ROC curve was 0.8660 for SUV data and 0.9197 for LCR data (P=0.2408, two-tailed test). The LCR method appears to be a valuable semiquantitative index for the evaluation of malignancy in pulmonary nodules with F-FDG PET, which is simple to perform clinically and does not require accurate measurements of body weight or the residual activity in the syringe utilized for F-FDG injection.

タンパク質分析のための最新質量分析装置 ハイブリッド型ＦＴ‐ＩＣＲ ＭＳ：ＱＦＴ‐７の特徴とプロテオーム解析への応用

Conventionally “bottom-up” approach has been applied for normal proteome analysis using mass spectrometer. This method has several advantages such as high sensitivity and accuracy in protein identification, because in this method, protein is firstly digested into peptides, which are then analyzed by using mass spectrometer. On the other hand, recently “top-down” proteomics technique is getting popular to analyze intact protein directly. This method does not require prior protein digestion process and it is expected to have usefulness of this method also for post translational modifications. By using Fourier transform mass spectrometer (FT-ICR MS), “top-down” proteomics has a great advantage such as, more accurate measurements of molecular weight of protein by using the feature of more accurate mass and isotope resolution of higher charge state, and much more qualified information by utilizing various internal dissociation methods (SORI-CID, IRMPD, ECD or any combination). This presentation focuses on analyzing intact protein mixture to aim “top-down” proteomics. Mixture of several intact proteins is analyzed using FT-ICR MS with no pretreatment such as sodium dodecyl sulfate polyaclylamide gel electrophoresis or high performance liquid chromatography. The dissociation of intact protein inside of FT-ICR MS can generate a lots of useful information.

Serum Prealbumin: Is It a Marker of Nutritional Status or of Risk of Malnutrition?

Hospitalized patients who are undernourished are more likely to develop clinical complications and have relatively poor outcomes, with increased length of stay (LOS) 1 and higher mortality compared with well-nourished patients. Provision of adequate nutritional support reduces the complication rate and improves outcome (1). Considerable efforts have therefore been made to identify patients at risk of malnutrition, with a view to early provision of nutritional support. A full nutritional assessment is a complex process, involving detailed assessment of nutritional intake, changes in body composition, signs or symptoms of nutritional deficiency or excess, and laboratory tests, and it should include not only protein-energy status but also vitamins and essential trace elements. Because of this complexity, rapid screening tests have been sought to identify patients who may already be malnourished or are at risk of malnutrition, who can then undergo a more detailed nutritional assessment. The screening tools with the most validation for protein-energy malnutrition include body mass index (weight/height2) in conjunction with recent changes in weight and a simple assessment of illness severity (2). In many patients, however, obtaining an accurate measurement of current and previous weight to allow calculation of rate of weight loss may not be possible, so clinicians have sought a rapid, reliable laboratory method, usually involving plasma proteins, to obtain comparable information. Serum albumin is of virtually no value in assessment or monitoring of nutritional status (3) but is mentioned here because, surprisingly, there still remain some clinicians who use it as part of their nutritional assessment. The main factor affecting plasma albumin concentration in patients is the rate of transcapillary escape into the interstitial fluid. This transcapillary escape of albumin is markedly increased in disease [as part of the systemic inflammatory response syndrome (SIRS)], leading to decreased plasma albumin concentrations (4). It is inevitable that …

Recent advances in histopathology and immunohistochemistry of adrenocortical carcinoma

Discerning malignancy in resected adrenocortical neoplasms can pose diagnostic difficulty. Macroscopic examination is the first important step toward diagnosis and should include accurate measurement of weight and dimension of the specimens and description of the cut surface of the tumors. It is also important to sample the specimens for histological diagnosis near foci of hemorrhage and/or necrosis. Histological scoring systems evaluating multiple parameters, especially the criteria of Weiss, have been shown to be reliable in differential diagnosis between adrenocortical adenoma and carcinoma. A tumor is defined as adrenocortical carcinoma when three or more of the following criteria are met; (1) high nuclear grade, (2) mitotic rate six or more per 50 high power fields, (3) atypical mitosis, (4) clear cells less than 25%, (5) a diffuse architecture pattern in more than one-third of the tumor, (6) confluent necrosis, (7) venous invasion, (8) sinusoidal invasion, and (9) capsular invasion. The criteria are relatively straightforward and considered the most effective standard for diagnosis of adrenocortical malignancy. However, great care should be taken in applying the criteria to histological evaluation of two relatively rare and peculiar adrenocortical tumors, adrenocortical oncocytoma and pediatric adrenocortical neoplasms. At this juncture, ancillary biological or molecular markers are of little practical value in terms of differential diagnosis between adrenocortical adenoma and carcinoma but tumors with MIB1 or Ki-67 labeling index more than 2.5 may be considered malignant. Prognostic markers of adrenocortical carcinoma have not been established other than complete respectability of the tumor. There are also no surrogate markers for predicting response to therapy with Mitotane, an adrenolytic agent. It sometimes is important for surgical pathologists to differentiate adrenocortical carcinoma from metastatic malignancies of other sites. An immunohistochemical evaluation of adrenal 4 binding protein (Ad4BP) or SF-1, a transcription factor of all steroidogenesis, can aid in this differential diagnosis because nuclear immunoreactivity for this transcription factor is relatively specific to steroid producing cells.

Validity of Parentally Reported Weight and Height for Preschool-Aged Children in Belgium and Its Impact on Classification Into Body Mass Index Categories

The aim of this study was to evaluate the validity of parentally reported weight and height values for preschool-aged children (3-7 years of age) in Belgium and the accuracy of BMI classifications using those data. The subjects were 297 preschool-aged children (157 boys and 140 girls). A questionnaire with questions about height and weight was distributed to the children and completed by their parents. Nurses of the Centres for Pupils Counselling conducted anthropometric measurements by following standardized procedures. National and international age- and gender-specific BMI cutoff values were used to determine BMI categories. Mean differences between reported and measured values for weight (-0.57 kg) and BMI (-0.51 kg/m2) were statistically significant, although small. For height, the mean difference (0.14 cm) was not statistically significant. When national and international BMI cutoff values for overweight were used, sensitivity values were 47% and 44%, respectively, and specificity values were 94% and 95%. Among all children requiring nutritional advice on the basis of being overweight or obese, more than one half of the overweight children and >75% of the obese children would be missed with the use of parentally reported weight and height values. Conversely, 70% of the children being classified as underweight with the use of these reported data could be encouraged wrongly to gain weight. The bias of parent-reported BMI values was significantly greater when weight and height were both guessed, rather than being measured at home. Our results show the inaccuracy of parentally reported weight and height values in Belgium for classifying preschool-aged children into BMI categories. Therefore, accurate measurements of weight and height should be encouraged in studies in which BMI of children is a variable of interest.

Linear growth and body mass index in pediatric patients with Cushing’s disease or simple obesity

Increasing prevalence of childhood obesity has resulted in an accelerating rate of referrals of overweight patients to pediatric clinics for exclusion of endocrine or metabolic etiologies. The exclusion of Cushing's disease (CD) requires complex and potentially invasive investigations. To evaluate the sensitivity of accurate measurements of height, weight and body mass index (BMI) in discriminating between simple obesity and CD. Height, weight and BMI were measured at diagnosis in 25 patients with CD; 14 males, 11 females, mean age 12.9 yr (6.4-17.8) and 41 patients with simple obesity (SO), defined as BMI >2.0 SD; 20 males, 21 females, mean age 9.4 yr (3.5-15.6). Mean (+/-SE) BMI SDS in the CD patients was 2.41+/-0.5 and in the SO patients 3.71+/-1.3. Height SDS in the CD patients was -1.88+/-0.24 and in the SO patients 1.18+/-0.19 (p<0.05). The mean (+/-SE) BMI SDS to height SDS ratio was significantly decreased in the CD compared with the SO patients; -1.81+/-0.54 vs +0.90+/-1.17 (p<0.0001). Simple, accurate measurement of height and BMI SDS values provides a quick, and sensitive diagnostic discriminator in pediatric patients with CD or SO, thus potentially avoiding complex investigations.

Mass Determination of Phosphoramidites

Nucleoside phosphoramidites are the most widely used building blocks in contemporary solid-phase synthesis of oligonucleotides. The accurate molecular weight measurements of such molecules, which are acid-labile compounds, may be easily determined by mass spectrometry using a matrix system, triethanolamine/NaCl, on a liquid secondary ion mass spectrometer (LSIMS) or fast-atom bombardment (FAB) MS equipped with a double-focusing mass spectrometer. The present method rapidly and easily measures the accurate molecular weights of various phosphoramidites as adduct ions [M+Na]+ with an average mass error smaller than 0.4 ppm, allowing determination of the formulas of the phosphoramidites in place of elemental analysis. Further, it was found that intensities of molecular-related ions could be enhanced to the highest degree by adjustment of the molar ratio of phosphoramidite and NaCl, fixing the amount of triethanolamine on LSIMS, making the present method a powerful tool for identification of phosphoramidites by mass spectrometry.

Protein and Nanoparticle Characterisation Using Light Scattering Techniques

AbstractThe technique of dynamic light scattering is well suited to the measurement of the size of colloidal dispersions. Traditionally, measurements of large particle sizes or particles that are highly scattering would require high dilution of the sample in order to avoid multiple scattering effects. Conversely, measurement of very small and/or poorly scattering particles or samples that are very dilute are difficult unless high‐powered lasers are used. These problems have been addressed in a light scattering instrument incorporating novel non‐invasive backscatter optics (NIBS). This novel optic arrangement maximises the detection of scattered light while maintaining signal quality. In addition to the increased size and concentration range for DLS applications, the increased sensitivity obtained from this optical arrangement also allows for the determination of absolute molecular weight using static light scattering measurements. Accurate molecular weight measurements can be achieved at a single scattering angle for molecules that do not show any angular dependence in their scattering intensity. This paper describes the advantages of using backscatter optics and illustrates the capabilities of the technology by reporting results of measurements from various applications.

Accurate molecular weight measurements of nucleoside phosphoramidites: a suitable matrix of mass spectrometry

Nucleoside phosphoramidites (PAs) are the most widely used building blocks in contemporary solid-phase synthesis of oligonucleotides. The accurate molecular weight (MW) measurements of such molecules, which contain acid-labile moieties, may be easily determined by mass spectrometry using a matrix system, triethanolamine (TEOA)–NaCl, on liquid secondary ion mass spectrometry (LSIMS) equipped with a double-focusing mass spectrometer. The present method measures rapidly and easily the accurate MWs of various PAs as adduct ions [M+Na] + with average mass error smaller than 0.4 ppm, allowing the formulas of various PAs in place of elemental analysis. Further, it was found that intensities of molecular-related ions could be enhanced to the highest degree by adjustment of the mole ratio of PA and NaCl fixing the amount of TEOA on LSIMS, making the present method powerful tool for the MS identification of PAs.

Weighing the world’s heaviest telescope at eight points with corrections for lifting perturbations

Abstract This technical note presents a summary of internal reports [ Parker DH, Anderson R, Egan D, Fakes T, Radcliff B, Shelton J. GBT rolling weight measurements: methods, results, estimation of uncertainty, and auxiliary measurements. GBT Memo 222, The National Radio Astronomy Observatory, 2003 ; Parker DH, Anderson R, Egan D, Fakes T, Radcliff B, Shelton J. GBT rolling weight measurements: methods, results, estimation of uncertainty, and auxiliary measurements. Technical Report A0335, The National Radio Astronomy Observatory, 2003. Includes Appendices ( ≈ 250 pp.) ], on weighing The National Radio Astronomy Observatory (NRAO), Robert C. Byrd Green Bank Telescope (GBT)—the world’s largest (100 m), fully steerable, radio telescope (and involving, possibly, the most accurate large-scale metrology field measurement of weight conducted to date). The measured weight was 74 405 kN (4.448222 N/lbf), with a combined standard uncertainty (level of confidence ≈ 68%) of ± 213 kN, or a relative combined standard uncertainty of 0.3%. Two measurements of a wheel pair (mounter on a common support beam), conducted 15 days apart, reproduced within 24 kN, or 0.3%. The measured weight distribution revealed a maximum wheel pair load of 9781 ± 44 kN, or 46% greater than the original wheel and track design assumptions, and nearly 9% greater than the final symmetric load estimation. Corrections were made for perturbations in the measured forces, due to lifting approximately one-eighth of the structure at a time. The load cells were custom calibrated to more closely match the actual field conditions. Parallel measurements are also presented from the hydraulic jack pressures.

Evaluating short stature in children.

A child's growth reflects his or her general state of health. Growth deceleration therefore may result from processes that ultimately threaten much more than height and weight. Accurate height and weight measurements and routine plotting of growth data on standard growth charts are important elements of pediatric practice. A decrease in length of height percentiles may be physiologic in infancy and in puberty. However, in order to distinguish physiologic from pathologic growth deceleration, a careful history and physical examination needs to be obtained. Quite frequently, laboratory and radiographic studies are needed to distinguish with confidence between causes of slow growth in these phases of life. Such studies are always required to evaluate growth deceleration during childhood, because growth deceleration in this phase is virtually always the result of a pathological process. If constitutional growth delay is diagnosed, reassurance is often adequate treatment, though continued monitoring of growth and bone age is indicated. Growth deceleration due to other processes is often treatable. Delineation of the causes of poor growth is particularly important because these disease processes may produce other serious problems.

Using light scattering to determine the stoichiometry of protein complexes.

The stoichiometry of a protein complex can be calculated from an accurate measurement of the complex's molecular weight. Multiangle laser light scattering in combination with size-exclusion chromatography and interferometric refractometry provides a powerful means for determining the molecular weights of proteins and protein complexes. In contrast to conventional size-exclusion chromatography and analytical centrifugation, measurements do not rely on the use of molecular weight standards and are not affected by the shape of the proteins. The technique is based on the direct relationship between the amount of light scattered by a protein in solution and the product of its concentration and molecular weight. A typical experimental configuration includes a size-exclusion column to fractionate the sample, a light-scattering detector to measure scattered light, and an interferometric refractometer to measure protein concentration. The determination of the molecular weight of an anthrax toxin complex will be examined to illustrate how multiangle laser light scattering can be used to determine the stoichiometry of protein complexes.

Food intake and the kidney: The right amounts at the right times

Food intake and the kidney: The right amounts at the right times

Observation of sodium gel-induced protein modifications in dodecylsulfate polyacrylamide gel electrophoresis and its implications for accurate molecular weight determination of gel-separated proteins by matrix-assisted laser desorption ionization time-of-flight mass spectrometry

Matrix-assisted laser desorption ionization (MALDI) time-of-flight mass spectrometry (TOFMS) can potentially provide accurate molecular weight information of proteins separated by sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE). Several issues related to resolution and accuracy of molecular weight measurement are investigated by using a time-lag focusing MALDI-TOF mass spectrometer. The effects of the gel components SDS, glycerol, and tris buffer on the mass spectral signals are studied systematically. Glycerol and tris buffer are shown to have little or no effect on resolution and mass accuracy, whereas SDS degrades sensitivity, resolution, and mass accuracy even at low concentrations. A simple and fast gel extraction technique is presented which is capable of detecting proteins loaded at the low-picomole level on the gel. The sample preparation procedure used in this work appears to remove most of SDS from the gel, thereby reducing the peak broadening effect caused by SDS and resulting in high resolution and accurate measurement of proteins. However, for proteins containing cysteines, the molecular ions are composed of a distribution of acrylamide-protein adducts likely formed by reaction with unpolymerized acrylamide in the gel during the gel separation process. The implications of gel-induced protein modifications on the accurate molecular weight measurement of gel-separated proteins are discussed.

Comparative Ebulliometry: a Simple, Reliable Technique for Accurate Measurement of the Number Average Molecular Weight of Macromolecules. Preliminary Studies on Heavy Crude Fractions

This article is divided into two parts. In the first part, the authors present a comparison of the major techniques for the measurement of the molecular weight of macromolecules. The bibliographic results are gathered in several tables. In the second part, a comparative ebulliometer for the measurement of the number average molecular weight (Mn) of heavy crude oil fractions is described. The high efficiency of the apparatus is demonstrated with a preliminary study of atmospheric distillation residues and resins. The measurement of molecular weights up to 2000 g/mol is possible in less than 4 hours with an uncertainty of about 2%.

Quantitation of progesterone receptor mRNA in breast carcinoma by branched DNA assay

Expression of progesterone receptor (PR) mRNA is indicative of a normal gene regulation mechanism mediated by functional estrogen receptor (ER). A simple assay which can reliably detect and quantitate PR mRNA levels in a small amount of tissue will be of value for studying functional status of ER. We have developed a quantitative nucleic acid hybridization assay for PR mRNA in breast carcinoma. The assay, which is based on the branched DNA (bDNA) technology, is simple, highly specific, and reproducible, requires 20 mg of tissue, and correlates reasonably well (r = 0.86) with an established methodology. The assay has a dynamic range of 3 x 10(3)-6 x 10(7) copies of PR mRNA per well. PR message as high as 3.9 x 10(5) copies per well could be detected in normal breast tissues. Thus a sensitivity of 3 x 10(3) PR copies per well was sufficient for testing clinical samples. In the present studies, accurate measurement of tissue weight enabled direct reporting of the PR mRNA values as the end point results. The bDNA assay provides a useful tool for the detection and quantitation of PR mRNA in research and routine clinical laboratories.

Quantitation of estrogen receptor mRNA in breast carcinoma by branched DNA assay.

A quantitative nucleic acid hybridization assay for determination of estrogen receptor (ER) mRNA in breast carcinoma is described. The assay, which is based on the branched DNA (bDNA) technology, requires 20 mg of tissue, is simple, highly specific, and reproducible, and correlates reasonably well with an established methodology (r = 0.87). The assay has a dynamic range of 3 x 10(3)-6 x 10(7) copies of ER mRNA per well. ER message as high as 2.5 x 10(6) copies per well could be detected in normal breast tissues. Thus a sensitivity of 3 x 10(3) ER copies per well was sufficient to analyze clinical specimens. In the present studies, accurate measurement of tissue weight enabled direct reporting of the ER mRNA values as the end point results. The bDNA assay provides a useful tool for the detection and quantitation of ER mRNA in research and routine clinical laboratories.

Practical Approaches for Estimating Prepregnant Body Weight

Measurements of prepregnant body weight have important research and clinical applications. In practice, however, they are not always recorded; even when they are, this information is not always readily available. For this reason, researchers and clinicians have to rely on retrospective estimates of prepregnant weight, which can be estimated using: 1) maternal self-reports, 2) retrospective extrapolation, or 3) standardized estimates that correct for weight gained during early pregnancy. The aim of the present study was to examine the relative merits of these three approaches. Maternal self-reports tend to be unreliable and biased, being influenced by a variety of sociodemographic characteristics that generally underestimate true prepregnant body weight. Estimates of prepregnant weight based on retrospective extrapolation are vulnerable to measurement error, transient fluctuations in body weight, and incorrectly assume that the rate of weight gain is constant throughout pregnancy. Standardized estimates that correct for weight gained during early pregnancy incorrectly presume that there is little interindividual variation in gestational weight gain and that weight gain is similar for each woman in consecutive pregnancies. Because none of these techniques can provide a precise measure of prepregnant weight, researchers have little alternative but to recruit and weigh women before they become pregnant, although measurements of body weight recorded during the first trimester of pregnancy may provide a reasonable indication of prepregnant weight. For clinicians, self-reports of prepregnant weight or measurements recorded early in pregnancy are probably sufficiently accurate for practical purposes whenever recent, accurate measurements of prepregnant weight are unavailable.

Confirmation of the structure of lipid A derived from the lipopolysaccharide of Rhodobacter sphaeroides by a combination of MALDI, LSIMS, and tandem mass spectrometry.

The chemical structure of nontoxic diphosphoryl lipid A from Rhodobacter sphaeroides was confirmed using a combination of LSIMS (on a two-sector mass spectrometer) and MALDI (on time-of-flight and ion trap mass spectrometers) in conjunction with tandem mass spectrometry in both positive and negative ion modes. Accurate molecular weight measurement accompanied by the analysis of fragment ion masses yielded the composition of fatty acyl groups. Tandem experiments (collisionally induced dissociation of both quasimolecular and oxonium ions) were also performed, revealing the precise location and nature of the fatty acyl groups on the disaccharide backbone.

The importance of accurate and precise molecular weight measurement in pulsed‐laser polymerization

AbstractMolecular weight distributions generated by pulsed‐laser polymerization have been determined experimentally using multi‐detector size exclusion chromatography (SEC). The conditions for accurate and precise SEC have been defined. The importance of the inter‐detector delay (IDD) is stressed and two different methods of defining IDD are compared. In addition this work highlights the problems associated with the use of Mark‐Houwink constants in constructing a universal calibration curve. Some preliminary results obtained from matrix‐assisted‐laser‐desorption‐ionisation mass spectrometry are also presented.