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Indian Journal of Ophthalmology Mar 2023To evaluate the use of Scheimpflug tomography in corneal densitometry (CD) in comparing the stages of keratoconic eyes.
PURPOSE
To evaluate the use of Scheimpflug tomography in corneal densitometry (CD) in comparing the stages of keratoconic eyes.
METHODS
Keratoconic (KC) corneas (stages 1-3 classified according to the topographic parameters) were examined using the Scheimpflug tomographer (Pentacam, Oculus) using the CD software. CD was measured over three different depths (anterior stromal layer [120 μm], posterior stromal layer [60 μm], and middle stromal layer between these two layers), and concentric annular zones (0.0 to 2.0, 2.0 to 6.0, 6.0 to 10.0, and 10.0 to 12.0 mm diameter area).
RESULTS
The study participants were divided into three groups: keratoconus (KC) stage 1 (KC1) with 64 participants, keratoconus stage 2 (KC2) with 29 participants, and keratoconus stage 3 (KC3) with 36 participants. Comparing CD of all three layers (anterior, central, and posterior) of the cornea over different circular annuli (0-2, 2-6, 6-10, and 10-12 mm) revealed a significant difference in the 6-10 mm annulus between all groups and in all layers (P = 0.3, 0.2, and 0.2, respectively). Area under curve (AUC) was done. It revealed that the central layer showed the highest specificity (93.8%) in comparing KC1 and KC2, whereas CD in the anterior layer between KC2 and KC3 had the highest specificity (86.2%).
CONCLUSION
CD showed increased values in the anterior corneal layer and in the annulus 6-10 mm more than other locations in all stages of KC.
Topics: Humans; Keratoconus; Cornea; Densitometry
PubMed: 36872687
DOI: 10.4103/ijo.IJO_1792_22 -
Molecules (Basel, Switzerland) Jan 2022Determination of valproic acid in the drug was carried out on the aluminum silica gel 60F plates and using acetone-water-chloroform-ethanol-ammonia at a volume ratio of...
Determination of valproic acid in the drug was carried out on the aluminum silica gel 60F plates and using acetone-water-chloroform-ethanol-ammonia at a volume ratio of 30:1:8:5:11 as the mobile phase, respectively. Two methods of detection of valproic acid were used. The first was a 2% aqueous CuSO×5HO solution, and the second was a 2',7'-dichlorofluorescein-aluminum chloride-iron (III) chloride system. The applied TLC-densitometric method is selective, linear, accurate, precise, and robust, regardless of the visualizing reagent used for the determination of valproic acid in Convulex capsules. It has low limits of detection (LOD) and limits of quantification (LOQ), which are equal to 5.8 μg/spot and 17.4 μg/spot using a 2% aqueous CuSO×5HO solution as visualizing agent and also 0.32 μg/spot and 0.97 μg/spot using a 2',7'-dichlorofluorescein-aluminum chloride-iron (III) chloride system as visualizing reagent, respectively. The described analytical method can additionally be used to study the identity of valproic acid in a pharmaceutical preparation. The linearity range was found to be 20.00-80.00 μg/spot and 1.00-2.00 μg/spot for valproic acid detected on chromatographic plates using a 2% aqueous CuSO×5HO solution and the 2',7'-dichlorofluorescein-aluminum chloride-iron (III) chloride system, respectively. A coefficient of variation that was less than 3% confirms the satisfactory accuracy and precision of the proposed method. The results of the assay of valproic acid equal 96.2% and 97.0% in relation to the label claim that valproic acid fulfill pharmacopoeial requirements. The developed TLC-densitometric method can be suitable for the routine analysis of valproic acid in pharmaceutical formulations. The proposed TLC-densitometry may be an alternative method to the modern high-performance liquid chromatography and square wave voltammetry in the control of above-mentioned substances, and it can be applied when other analytical techniques is not affordable in the laboratory.
Topics: Capsules; Chromatography, Thin Layer; Densitometry; Drug Carriers; Drug Compounding; Humans; Limit of Detection; Reproducibility of Results; Sensitivity and Specificity; Valproic Acid
PubMed: 35164016
DOI: 10.3390/molecules27030752 -
The Biochemical Journal Nov 1972
Topics: Automation; Chromatography, Thin Layer; Densitometry; Specimen Handling
PubMed: 4664585
DOI: 10.1042/bj1300058p -
American Journal of Respiratory and... Oct 2022
Topics: Densitometry; Emphysema; Humans; Losartan; Lung; Outcome Assessment, Health Care; Pulmonary Emphysema; Tomography
PubMed: 35653703
DOI: 10.1164/rccm.202205-0927ED -
PloS One 2014Quantitative multidetector computed tomography (MDCT) as a potential biomarker is increasingly used for severity assessment of emphysema in chronic obstructive pulmonary...
OBJECTIVES
Quantitative multidetector computed tomography (MDCT) as a potential biomarker is increasingly used for severity assessment of emphysema in chronic obstructive pulmonary disease (COPD). Aim of this study was to evaluate the user-independent measurement variability between five different fully-automatic densitometry software tools.
MATERIAL AND METHODS
MDCT and full-body plethysmography incl. forced expiratory volume in 1s and total lung capacity were available for 49 patients with advanced COPD (age = 64±9 years, forced expiratory volume in 1 s = 31±6% predicted). Measurement variation regarding lung volume, emphysema volume, emphysema index, and mean lung density was evaluated for two scientific and three commercially available lung densitometry software tools designed to analyze MDCT from different scanner types.
RESULTS
One scientific tool and one commercial tool failed to process most or all datasets, respectively, and were excluded. One scientific and another commercial tool analyzed 49, the remaining commercial tool 30 datasets. Lung volume, emphysema volume, emphysema index and mean lung density were significantly different amongst these three tools (p<0.001). Limits of agreement for lung volume were [-0.195, -0.052 l], [-0.305, -0.131 l], and [-0.123, -0.052 l] with correlation coefficients of r = 1.00 each. Limits of agreement for emphysema index were [-6.2, 2.9%], [-27.0, 16.9%], and [-25.5, 18.8%], with r = 0.79 to 0.98. Correlation of lung volume with total lung capacity was good to excellent (r = 0.77 to 0.91, p<0.001), but segmented lung volume (6.7±1.3-6.8±1.3 l) were significantly lower than total lung capacity (7.7±1.7 l, p<0.001).
CONCLUSIONS
Technical incompatibilities hindered evaluation of two of five tools. The remaining three showed significant measurement variation for emphysema, hampering quantitative MDCT as a biomarker in COPD. Follow-up studies should currently use identical software, and standardization efforts should encompass software as well.
Topics: Aged; Densitometry; Emphysema; Female; Forced Expiratory Volume; Humans; Lung Volume Measurements; Male; Middle Aged; Pulmonary Disease, Chronic Obstructive; Respiratory Function Tests; Retrospective Studies; Software; Tomography, X-Ray Computed
PubMed: 25386874
DOI: 10.1371/journal.pone.0112898 -
Biomechanical background for a noninvasive assessment of bone strength and muscle-bone interactions.Journal of Musculoskeletal & Neuronal... Mar 2004New concepts and methods of study in bone biomechanics defy the prevailing idea that bone strength is determined by a systemically-controlled "mineralized mass" which... (Review)
Review
New concepts and methods of study in bone biomechanics defy the prevailing idea that bone strength is determined by a systemically-controlled "mineralized mass" which grows until reaching a peak and then is lost at individually-specific rates. In case of bones, "mass" represents actually the substratum of a structure, the stiffness of which does not depend on the mass, but on the intrinsic stiffness and the spatial distribution of the mineralized material. A feed-back system called "bone mechanostat" seems to orient the osteoblastic and osteoclastic processes of bone, modeling and remodeling, according to the sensing by osteocytes of strains caused in the structure by mechanical usage of the skeleton, in specific directions as determined principally by the customary contractions of regional muscles and impact forces. The endocrine-metabolic systems, crucial for the normal skeletal development, modulate the work of osteocytes, blasts and clasts in a systemic way (i.e., not related to a specific direction of the stimuli). Therefore, they tend actually to interact with, rather than contribute to, the biomechanical control of bone structure. Furthermore, no feed-back loop enabling a cybernetic relationship of those systems with bone is known. Instead of passively letting hormones regulate their "mass" in order to optimize their strength, bones would actively self-regulate their architecture following an anisotropic pattern in order to optimize their stiffness (the only known variable to be ever controlled in the skeleton) and strength "despite of" the endocrine systems. Three practical questions derive from those ideas: 1. Osteoporoses are not "intense osteopenias" but "osteopenic fragilities". 2. The diagnosis of osteopenia could be solved densitometrically; but that of bone fragility is a biomechanical problem which requires auxiliary resources for evaluating the stiffness and the spatial distribution of the mineralized material. 3. Osteopenias and osteoporoses should be on time evaluated as related to the mass or strength of the regional muscles, respectively, in order to differentiate between the "primary" (intrinsic lesion of the mechanostat) or "secondary" (systemic) etiologies and the biomechanical origin (disuse) in each case, with important therapeutic implications.
Topics: Biomechanical Phenomena; Bone Density; Bone Diseases, Metabolic; Bone and Bones; Densitometry; Endocrine System; Feedback; Humans; Mechanotransduction, Cellular; Muscle, Skeletal
PubMed: 15615073
DOI: No ID Found -
Photodiagnosis and Photodynamic Therapy Apr 2024Examination of corneal densitometry measurements using the Pentacam Scheimpflug imaging system in cases of pseudoexfoliative glaucoma (PEXG) and ocular hypertension...
BACKGROUND
Examination of corneal densitometry measurements using the Pentacam Scheimpflug imaging system in cases of pseudoexfoliative glaucoma (PEXG) and ocular hypertension (OHT).
METHODS
The study included 50 eyes of 29 PEXG patients, 25 eyes of 16 OHT patients, and 76 eyes of 38 healthy control subjects followed in the glaucoma clinic. Corneal densitometry values of all cases were measured using the Scheimpflug imaging system (Pentacam, Oculus, Germany). Corneal densitometry was assessed based on 4 concentric radial zones (0-2 mm, 2-6 mm, 6-10 mm, and 10-12 mm) and depths (anterior, central, posterior, and total) within the Scheimpflug imaging system. The results were statistically analyzed.
RESULTS
Corneal densitometry values examined between the OHT and control groups were higher in OHT and statistically significant (p < 0.05). Corneal densitometry values examined between the PEXG and control groups were higher in PEXG and statistically significant (p < 0.05). In comparison between the PEXG and OHT groups, corneal densitometry values in the central 0-2 mm, 2-6 mm, and 6-10 mm; posterior 0-2 mm and 2-6 mm radial zones were higher in PEXG and statistically significant (p < 0.05).
CONCLUSIONS
It was observed that elevated intraocular pressure levels in OHT cases could lead to changes in the cornea, consequently increasing corneal densitometry values. The higher corneal densitometry values in PEXG cases compared to OHT were attributed to the accumulation of pseudoexfoliative material in the cornea. Based on our study, corneal densitometry could serve as a potential biomarker for early glaucoma detection in OHT cases and could be employed to assess corneal transparency during the follow-up of PEXG cases.
Topics: Humans; Densitometry; Female; Cornea; Ocular Hypertension; Male; Aged; Exfoliation Syndrome; Middle Aged; Case-Control Studies
PubMed: 38368915
DOI: 10.1016/j.pdpdt.2024.103988 -
Respiratory Research Feb 2019We developed a method to calculate a standard score for lung tissue mass derived from CT scan images from a control group without respiratory disease. We applied the... (Comparative Study)
Comparative Study
BACKGROUND
We developed a method to calculate a standard score for lung tissue mass derived from CT scan images from a control group without respiratory disease. We applied the method to images from subjects with emphysema associated with alpha-1 antitrypsin deficiency (AATD) and used it to study regional patterns of differential tissue mass.
METHODS
We explored different covariates in 76 controls. Standardization was applied to facilitate comparability between different CT scanners and a standard Z-score (Standard Mass Score, SMS) was developed, representing lung tissue loss compared to normal lung mass. This normative data was defined for the entire lungs and for delineated apical, central and basal regions. The agreement with D%pred was explored in a data set of 180 patients with emphysema who participated in a trial of alpha-1-antitrypsin augmentation treatment (RAPID).
RESULTS
Large differences between emphysematous and normal tissue of more than 10 standard deviations were found. There was reasonable agreement between SMS and D%pred for the global densitometry (κ = 0.252, p < 0.001), varying from κ = 0.138 to κ = 0.219 and 0.264 (p < 0.001), in the apical, central and basal region, respectively. SMS and D%pred correlated consistently across apical, central and basal regions. The SMS distribution over the different lung regions showed a distinct pattern suggesting that emphysema due to severe AATD develops from basal to central and ultimately apical regions.
CONCLUSIONS
Standardization and normalization of lung densitometry is feasible and the adoption of the developed principles helps to characterize the distribution of emphysema, required for clinical decision making.
Topics: Adult; Densitometry; Female; Humans; Lung; Male; Middle Aged; Predictive Value of Tests; Pulmonary Emphysema; Tomography, X-Ray Computed; alpha 1-Antitrypsin Deficiency
PubMed: 30819163
DOI: 10.1186/s12931-019-1012-3 -
PloS One 2017The Dual Energy X-Ray Absorptiometry (DXA) is the gold standard for measuring BMD and bone mineral content (BMC). In general, DXA is ideal for pediatric use. However,...
BACKGROUND
The Dual Energy X-Ray Absorptiometry (DXA) is the gold standard for measuring BMD and bone mineral content (BMC). In general, DXA is ideal for pediatric use. However, the development of specific standards for particular geographic regions limits its use and application for certain socio-cultural contexts. Additionally, the anthropometry may be a low cost and easy to use alternative method in epidemiological contexts. The goal of our study was to develop regression equations for predicting bone health of children and adolescents based on anthropometric indicators to propose reference values based on age and sex.
METHODS
3020 students (1567 males and 1453 females) ranging in ages 4.0 to 18.9 were studied from the Maule Region (Chile). Anthropometric variables evaluated included: weight, standing height, sitting height, forearm length, and femur diameter. A total body scan (without the head) was conducted by means of the Dual Energy X-Ray Absorptiometry. Bone mineral density (BMD) and the bone mineral content (BMC) were also determined. Calcium consumption was controlled for by recording the intake of the three last days prior to the evaluation. Body Mass Index (BMI) was calculated, and somatic maturation was determined by using the years of peak growth rate (APHV).
RESULTS
Four regression models were generated to calculate bone health: for males BMD = (R2 = 0.79) and BMC = (R2 = 0.84) and for the females BMD = (R2 = 0.76) and BMC = (R2 = 0.83). Percentiles were developed by using the LMS method (p3, p5, p15, p25, p50, p75, p85, p95 and p97).
CONCLUSIONS
Regression equations and reference curves were developed to assess the bone health of Chilean children and adolescents. These instruments help identify children with potential underlying problems in bone mineralization during the growth stage and biological maturation.
Topics: Absorptiometry, Photon; Adolescent; Age Factors; Anthropometry; Body Height; Bone Density; Bone and Bones; Child; Child, Preschool; Chile; Cross-Sectional Studies; Cultural Characteristics; Densitometry; Female; Geography; Humans; Male; Reference Values; Regression Analysis; Sex Factors
PubMed: 28759569
DOI: 10.1371/journal.pone.0181918 -
Journal of Applied Physiology... Sep 2015To investigate the effects of dietary methionine restriction (MetR) and endurance exercise on bone quality under a condition of estrogen deficiency, female...
To investigate the effects of dietary methionine restriction (MetR) and endurance exercise on bone quality under a condition of estrogen deficiency, female Sprague-Dawley rats (36-wk-old) were assigned to a sham surgery group or one of five ovariectomized groups subjected to interventions of no treatment (Ovx), endurance exercise (Exe), methionine restriction (MetR), methionine restriction plus endurance exercise (MetR + Exe), and estrogen treatment (Est). Rats in the exercise groups were subjected to a treadmill running regimen. MetR and control diets contained 0.172 and 0.86% methionine, respectively. After the 12-wk intervention, all animals were killed, and serum and bone tissues were collected for analyses. Compared with estrogen treatment, MetR diet and endurance exercise showed better or equivalent efficiency in reducing body weight gain caused by ovariectomy (P < 0.05). Whereas only the Est group showed evidence for reduced bone turnover compared with the Ovx group, MetR diet and/or endurance exercise demonstrated efficiencies in downregulating serum insulin, leptin, triglyceride, and thiobarbituric acid reactive substances (P < 0.05). Both the Exe and MetR groups showed higher femoral cortical and total volumetric bone mineral density (vBMD), but only the Exe and Est groups preserved cancellous bone volume and/or vBMD of distal femora (P < 0.05) compared with the Ovx group. After being normalized to body mass, femora of the MetR and MetR + Exe groups had relatively higher bending strength and dimension values followed by the Sham, Exe, and Est groups (P < 0.05). In conclusion, both MetR diet and endurance exercise improved cortical bone properties, but only endurance exercise preserved cancellous bone under estrogen deficiency.
Topics: Animals; Biomechanical Phenomena; Bone Density; Bone and Bones; Densitometry; Estrogens; Female; Methionine; Ovariectomy; Physical Conditioning, Animal; Rats; Rats, Sprague-Dawley
PubMed: 26159761
DOI: 10.1152/japplphysiol.00395.2015