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Women's Health (London, England) Jan 2008The relationship between declining bone density and increasing fracture risk is firmly established; the relationship between increasing bone density and decreasing...
The relationship between declining bone density and increasing fracture risk is firmly established; the relationship between increasing bone density and decreasing fracture risk is less clear. Because of this, the clinical utility of assessing the therapeutic efficacy of prescription therapies to reduce fracture risk by measuring changes in bone density has been called into question. However, there is substantial clinical trial data to support this approach. Nevertheless, an apparent increase or decrease in the bone density may be misinterpreted without an understanding of the statistical concepts of precision and least significant change. These concepts are not difficult and are of profound clinical importance. If the least significant change is not known, serial measurements of bone density cannot be interpreted. These concepts will be discussed and illustrated, and the rationale for the importance of changes in bone mineral density on therapy will be explored.
Topics: Bone Density; Bone Density Conservation Agents; Densitometry; Female; Fractures, Bone; Humans; Meta-Analysis as Topic; Models, Statistical; Monitoring, Physiologic; Osteoporosis; Risk Factors
PubMed: 19072454
DOI: 10.2217/17455057.4.1.89 -
Journal of Bone and Mineral Research :... Jan 2006The fracture of bone plays a key role in osteoporosis. BMD measurement, however, is only an indirect parameter of this phenomenon. We therefore developed a highly... (Comparative Study)
Comparative Study
UNLABELLED
The fracture of bone plays a key role in osteoporosis. BMD measurement, however, is only an indirect parameter of this phenomenon. We therefore developed a highly sensitive three-point bending test for the metaphyseal tibias in rats to evaluate stiffness and strength. This was validated in a right-left comparison and a bioassay with soy-free food, estradiol, raloxifene, and testosterone in orchidectomized rats.
INTRODUCTION
Osteoporosis becomes manifest predominantly in the metaphyseal rat tibia. The anti-osteoporotic character of substances should, therefore, be tested (mechanically) in this bone area.
MATERIALS AND METHODS
We evaluated a new three-point bending test for the metaphyseal tibia in rats in a right-left trial. In an animal experiment, we studied the change of bone quality under estradiol (E)-, raloxifene (R)-, and testosterone (T)-supplemented food and compared it with trabecular BMD (qCT).
RESULTS
In the right-left comparison, the mean difference between the metaphyseal loads of both tibias in 37 rats was 8.43% for the maximum load (Fmax) and 6.46% for the failure load (fL). These results show the high reproducibility of the test, because they are close to the usual intraindividual difference of the two extremities. In a second experiment, four groups of 11 3-month-old male orchidectomized rats were fed with soy-free food only (C) or with the additives E, T, or R for 12 weeks. E and R were similar for Fmax and fL. There were significant differences in the stiffness (E = 406.92 N/mm versus R = 332.08 N/mm), the yield load (yL; E = 99.17 N versus R = 83.33 N), and the ratio between yL and Fmax (E = 86.33% versus R = 76.37%). T was similar to the controls concerning F(max), fL, and stiffness. There were significant differences in yL (T = 49.00N versus C = 39.5N) and the ratio between yL and Fmax (T = 64.28% versus C = 51.28%).
CONCLUSIONS
Estradiol is superior to raloxifene concerning stiffness and yield load, and both are superior to testosterone. We conclude that the described three-point bending test for the metaphyseal tibia is a highly sensitive method to study hormones and substances with regard to their osteoprotective character. The precision and the low SD of the presented results are superior to the data from qCT and the calculated index of stiffness (SSI).
Topics: Androgens; Animals; Bone Density; Bone Density Conservation Agents; Densitometry; Estradiol; Female; Male; Osteoporosis; Raloxifene Hydrochloride; Rats; Rats, Sprague-Dawley; Rats, Wistar; Stress, Mechanical; Testosterone; Tibia
PubMed: 16355277
DOI: 10.1359/JBMR.050913 -
Critical Care (London, England) 2011
Review
Topics: Algorithms; Blood Pressure Monitors; Cardiac Output; Cardiography, Impedance; Catheterization, Swan-Ganz; Critical Illness; Densitometry; Echocardiography, Doppler; Heart Function Tests; Hemodynamics; Humans
PubMed: 21457508
DOI: 10.1186/cc9996 -
Indian Journal of Ophthalmology Jan 2023Corneal densitometry analysis provides an objective measurement of corneal transparency in patients undergoing photorefractive keratectomy (PRK). To date, no study that...
PURPOSE
Corneal densitometry analysis provides an objective measurement of corneal transparency in patients undergoing photorefractive keratectomy (PRK). To date, no study that focuses on determining the reliability and smallest real difference (SRD), specifically in PRK candidates, has been published.
METHODS
The study was conducted at Clínica de Oftalmología Sandiego, Medellín, Colombia. This was a prospective and analytical study. Refractive surgery candidates underwent Pentacam measurements twice with five minutes of difference. Repeatability of measurements was evaluated for every area using Wilcoxon signed-rank test, Spearman's rank-order correlation, and the intraclass correlation coefficient, followed by a within-subjects factor (S) finishing with a determination of the SRD for all areas. Bland-Altman plots were created and analyzed.
RESULTS
A total of 110 eyes were included. The mean total densitometry was 18.67 ± 1.56 grayscale units (GSU) and 18.65 ± 1.49 GSU for the first and second measurements, respectively. Wilcoxon was non-significant (P > 0.05) while the intraclass correlation coefficient demonstrated an excellent agreement. SRD ranged from 0.21 GSU (posterior × 6-10 mm) to 1.79 GSU (total × 10-12 mm). Anterior depths and 10-12 mm annulus had consistently more variability and greater (worse) SRD. The 10-12 mm annulus showed great dispersion on the Bland-Altman plots.
CONCLUSION
Corneal densitometry has an excellent repeatability in refractive surgery candidates for areas below 10 mm. Any densitometry change ≥1.0 GSU in areas under 10 mm should be considered as well above measurement noise and corresponding to a real change in measured parameters. The 10-12 mm area does not seem to be reliable enough in refractive surgery candidates to warrant surveillance after corneal-based surgery.
Topics: Humans; Prospective Studies; Reproducibility of Results; Densitometry; Cornea; Photorefractive Keratectomy; Corneal Topography
PubMed: 36588209
DOI: 10.4103/ijo.IJO_1121_22 -
The British Journal of Nutrition Mar 1994Body composition was measured in nine healthy, normal-weight, weight-stable subjects in three different research centres. In each centre the usual procedures for the... (Comparative Study)
Comparative Study
Body composition was measured in nine healthy, normal-weight, weight-stable subjects in three different research centres. In each centre the usual procedures for the measurements were followed. It revealed that the measurement procedures in the three centres were comparable. Body composition was measured in each centre between 09.00 and 13.00 hours after a light breakfast by densitometry (underwater weighing) and bio-electrical impedance. A single, total-body-water determination by D2O dilution was used as a reference value. Body fat determined by densitometry was significantly lower in one centre, which, however, could be completely explained by a lower body weight, probably due to water loss (the subjects refrained for a longer time from food and drinks before the measurements in that centre) and, thus, by violation of the assumptions of Siri's (1961) formula. Also, body impedance was slightly higher in that centre, indicating a lower amount of body water. Mean body fat from densitometry was also slightly lower in that centre compared with body fat determined by D2O dilution. Individual differences between body fat from densitometry and from total body water were relatively large, up to 7% body fat. The relationship between fat-free mass from densitometry and bio-electrical impedance was not different between the centres. It is concluded that differences in the relationship between body composition and bio-electrical impedance, as reported in the literature, may be due to differences in standardization procedures and/or differences in reference population.
Topics: Adipose Tissue; Adult; Body Composition; Body Water; Densitometry; Electric Impedance; Female; Humans; Male; Middle Aged; Radioisotope Dilution Technique; Reference Values
PubMed: 8172862
DOI: 10.1079/bjn19940140 -
Annals of Biomedical Engineering Feb 2024Optical bone densitometry (OBD) has been developed for the early detection of osteoporosis. In recent years, machine learning (ML) techniques have been actively...
Optical bone densitometry (OBD) has been developed for the early detection of osteoporosis. In recent years, machine learning (ML) techniques have been actively implemented for the areas of medical diagnosis and screening with the goal of improving diagnostic accuracy. The purpose of this study was to verify the feasibility of using the combination of OBD and ML techniques as a screening tool for osteoporosis. Dual energy X-ray absorptiometry (DXA) and OBD measurements were performed on 203 Thai subjects. From the OBD measurements and readily available demographic data, machine learning techniques were used to predict the T-score measured by the DXA. The T-score predicted using the Ridge regressor had a correlation of r = 0.512 with respect to the reference value. The predicted T-score also showed an AUC of 0.853 for discriminating individuals with osteoporosis. The results obtained suggest that the developed model is reliable enough to be used for screening for osteoporosis.
Topics: Humans; Bone Density; Osteoporosis; Absorptiometry, Photon
PubMed: 37882922
DOI: 10.1007/s10439-023-03387-8 -
Acta Pharmaceutica (Zagreb, Croatia) Mar 2020A TLC-densitometric method for determination of allantoin in Symphytum officinale root was developed. Densitometric quantification of allantoin was carried out on TLC... (Comparative Study)
Comparative Study
A TLC-densitometric method for determination of allantoin in Symphytum officinale root was developed. Densitometric quantification of allantoin was carried out on TLC Si60 plates with butanol-50 % methanol/formic acid, 66.5:33.2:0.3 (V/V/V) as developing solvent, at a wavelength of 190 nm. The method was preliminarily validated in terms of specificity, linearity, precision, limit of detection, limit of quantification, recovery and robustness. The results of TLC quantification were compared with HPLC analysis carried out on a HILIC Luna NH2 100A column, with mobile phase consisting of acetonitrile/water 80:20 (V/V) and UV detection at 190 and 210 nm. Allantoin content was determined in two herbal products and it varied from 0.94 to 2.09 %, depending on the producer, and was in agreement with literature reports.
Topics: Allantoin; Chromatography, High Pressure Liquid; Chromatography, Thin Layer; Comfrey; Densitometry; Limit of Detection; Plant Roots
PubMed: 31677368
DOI: 10.2478/acph-2020-0014 -
Investigative Ophthalmology & Visual... Oct 2014Retinal densitometry provides objective information about retinal function. But, a number of factors, including retinal reflectance changes that are not directly related...
PURPOSE
Retinal densitometry provides objective information about retinal function. But, a number of factors, including retinal reflectance changes that are not directly related to photopigment depletion, complicate its interpretation. We explore these factors and suggest a method to minimize their impact.
METHODS
An adaptive optics scanning light ophthalmoscope (AOSLO) was used to measure changes in photoreceptor reflectance in monkeys before and after photopigment bleaching with 514-nm light. Reflectance measurements at 514 nm and 794 nm were recorded simultaneously. Several methods of normalization to extract the apparent optical density of the photopigment were compared.
RESULTS
We identified stimulus-related fluctuations in 794-nm reflectance that are not associated with photopigment absorptance and occur in both rods and cones. These changes had a magnitude approaching those associated directly with pigment depletion, precluding the use of infrared reflectance for normalization. We used a spatial normalization method instead, which avoided the fluctuations in the near infrared, as well as a confocal AOSLO designed to minimize light from layers other than the receptors. However, these methods produced a surprisingly low estimate of the apparent rhodopsin density (animal 1: 0.073 ± 0.006, animal 2: 0.032 ± 0.003).
CONCLUSIONS
These results confirm earlier observations that changes in photopigment absorption are not the only source of retinal reflectance change during dark adaptation. It appears that the stray light that has historically reduced the apparent density of cone photopigment in retinal densitometry arises predominantly from layers near the photoreceptors themselves. Despite these complications, this method provides a valuable, objective measure of retinal function.
Topics: Animals; Dark Adaptation; Densitometry; Female; Macaca; Male; Ophthalmoscopy; Retina; Rhodopsin
PubMed: 25316726
DOI: 10.1167/iovs.13-13795 -
Journal of Digital Imaging Oct 2010Studies reported in the literature indicate that the increase in the breast density is one of the strongest indicators of developing breast cancer. In this paper, we...
Studies reported in the literature indicate that the increase in the breast density is one of the strongest indicators of developing breast cancer. In this paper, we present an approach to automatically evaluate the density of a breast by segmenting its internal parenchyma in either fatty or dense class. Our approach is based on a statistical analysis of each pixel neighbourhood for modelling both tissue types. Therefore, we provide connected density clusters taking the spatial information of the breast into account. With the aim of showing the robustness of our approach, the experiments are performed using two different databases: the well-known Mammographic Image Analysis Society digitised database and a new full-field digital database of mammograms from which we have annotations provided by radiologists. Quantitative and qualitative results show that our approach is able to correctly detect dense breasts, segmenting the tissue type accordingly.
Topics: Algorithms; Breast; Breast Neoplasms; Densitometry; Female; Humans; Models, Statistical; Pattern Recognition, Automated; Radiographic Image Enhancement; Radiographic Image Interpretation, Computer-Assisted
PubMed: 19506953
DOI: 10.1007/s10278-009-9217-5 -
Molecules (Basel, Switzerland) Jun 2021Metronidazole is a drug widely used in the prevention and treatment of bacterial infections. Due to its possibility of the formation of stable metal complexes, it was...
Metronidazole is a drug widely used in the prevention and treatment of bacterial infections. Due to its possibility of the formation of stable metal complexes, it was decided to broaden its activity spectrum by introducing the silver(I) coordination compounds i.e., [Ag(MTZ)NO] and [(Ag(MTZ))]SO, which have significant antibacterial properties. The paper presents a description of a new qualitative and quantitative analysis of metronidazole in bulk and possible pharmaceutical preparations by thin-layer chromatography with densitometric detection. Optimal separation conditions were selected, and the analytical procedure was validated according to the ICH guidelines. The obtained data indicate that the method is sufficiently sensitive, precise, and accurate. The stability of the metronidazole solutions obtained from tablets, pure metronidazole, and its silver(I) complexes was tested. The research was carried out in various environments, at different temperatures, in HO solution, and during exposure to radiation (UV, sunlight). The greatest degradation was found in the alkaline environment and at higher temperatures. The silver(I) complexes exhibited relatively high stability under analyzed conditions that are higher than standard metronidazole solutions and tablets. The observations were confirmed by the kinetic and thermodynamic analysis. The described studies of new metronidazole silver(I) complexes increase the potential for their application in infections both in humans and animals.
Topics: Animals; Anti-Bacterial Agents; Chromatography, Thin Layer; Coordination Complexes; Densitometry; Drug Stability; Humans; Hydrogen Peroxide; Kinetics; Metronidazole; Silver Compounds; Tablets
PubMed: 34208193
DOI: 10.3390/molecules26123582