2D Markers Research Articles

Target Values for 25-Hydroxy and 1,25-Dihydroxy Vitamin D Based on Their Associations with Inflammation and Calcium-Phosphate Metabolism.

Target values for 25-hydroxy vitamin D and 1,25(OH)2D or 1,25-dihydroxy vitamin D remain a topic of debate among clinicians. We analysed data collected from December 2012 to April 2020 from two cohorts. Cohort A, comprising 455,062 subjects, was used to investigate the relationship between inflammatory indicators (white blood cell [WBC] count and C-reactive protein [CRP]) and 25(OH)D/1,25(OH)2D. Cohort B, including 47,778 subjects, was used to investigate the connection between 25(OH)D/1,25(OH)2D and mineral metabolism markers (phosphate, calcium, and intact parathyroid hormone [iPTH]). Quadratic models fit best for all tested correlations, revealing U-shaped relationships between inflammatory indicators and 25(OH)D and 1,25(OH)2D. Minimal CRP and WBC counts were observed at 1,25(OH)2D levels of 60 pg/mL and at 25(OH)D levels of 32 ng/mL, as well as of 42 ng/mL, respectively. iPTH correlated inversely with both 1,25(OH)2D and 25(OH)D, while phosphate as well as calcium levels positively correlated with both vitamin D forms. Calcium-phosphate product increased sharply when 25(OH)D was more than 50 ng/mL, indicating a possible risk for vascular calcification. Multiple regression analyses confirmed that these correlations were independent of confounders. This study suggests target values for 25(OH)D between 30-50 ng/mL and for 1,25(OH)2D between 50-70 pg/mL, based particularly on their associations with inflammation but also with mineral metabolism markers. These findings contribute to the ongoing discussion around ideal levels of vitamin D but require support from independent studies with data on clinical endpoints.

Mapping lines of non-extension in persons with lower limb amputation to aid comfort-driven prosthetic socket design.

This study aimed to develop a new technique to map the strain field for persons with lower-limb amputations to use for the design of comfortable prostheses. Using a DSLR camera with stenciled 2D markers, we demonstrated a technique to measure skin strain around the residual limb of persons with lower limb amputations. We used open-source software programs to reconstruct a series of cloud points derived from the pictures of the marked residual limb into 3D models, then calculated the minimum, maximum, and non-extension lines from directional strain fields. A DSLR camera was successful in capturing 2D markers. The maximum mean principal strain was 68% ± 14%, observed around the patella. The minimum compressive mean principal strain of -31% ± 4% was observed posteriorly in the popliteal region of the knee. Although lines of non-extension (LoNE) appear separate in different participants, they are anatomically located in regions that could be generalized for the design of prostheses. Marker locations extracted from the video of different poses can be compared to calculate strains from which the position of LoNE can be generated. The use of LoNE could be valuable in reducing discomfort at the socket interface and informing future socket design.

Experimental and Computational Study of Error and Uncertainty in Real-Time Camera-Based Tracking of a Two-Dimensional Marker for Orthopedic Surgical Navigation

Abstract Tracking of the position and orientation of a moving object by a camera can be accomplished by attaching a 2D marker with a specific pattern on the object. Recently, we have developed a projection-based surgical navigation system that can accurately guide in real-time the pre-operative plan of resection in orthopedic surgery, such as joint replacement or wide-resection of osteosarcoma (bone tumor). To this end, it is important to study the accuracy of registration and tracking due to various sources of errors, such as the printing resolution and quality of the 2D marker. In this study, we investigate and provide analysis of error and uncertainty for real-time tracking using a 2D marker with a camera. Experiments and computational simulations were conducted to quantify the estimation of errors in position and orientation due to the printing error of 2D markers using a 600-dpi laser printer. In addition, a theory of uncertainty propagation in a form of congruence transformation was derived for such systems and is illustrated with experimental results.

Mobile based augmented reality for flexible human height estimation using touch and motion gesture interaction

Human height measurement can be achieved by using contact or non-contact techniques. Contact technique is the traditional measuring method which required human resources to perform the measurement. In contrast, for non-contact technique, several kinds of research for measurement have been conducted, mostly with image-processing methods and only a few with the Augmented Reality (AR) approach. The current measuring approaches mostly required external hardware such as laser pointer or artificial fiducial such as 2D markers. In this paper, the world tracking technique and Visual Inertial Odometry is the method used to estimate the human height. The main aim of this paper is to accurately estimate the human height using augmented reality (non-contacted measurements). The methodology used the Apple ARKit plugin, which is the software development tools to build an augmented reality application for IOS device. An algorithm was designed by using Golden Ratio rules to estimate human height from the lower part of human knee; The estimation result is displayed using AR technology to allow the justification of the accuracy of the result. The application is tested with four different measuring methods. The normal full-height measurement result had a 1.13cm (0.73%) bias and a 1.34cm (0.88%) Root Mean Square Error (RMSE); the self-full height measurement had a result of 0.89cm (0.58%) bias and a 1.27cm (0.83%) RMSE; the normal height estimation from the lower part of knee measurement had a result of 0.12cm (0.06%) bias and a 1.34cm (0.89%) RMSE; the self-height estimation from the lower part of knee measurement had a result of 0.15cm (0.09%) bias and a 1.04cm (0.66%) RMSE. The results show that the mobile phone with VIO can be a potential tool for obtaining accurate measurements of human height.

Volumetric Markers of Body Composition May Improve Personalized Prediction of Major Arterial Bleeding After Pelvic Fracture: A Secondary Analysis of the Baltimore CT Prediction Model Cohort.

This work is a retrospective secondary analysis of a single institution cohort used in the development of the Baltimore CT prediction model. The cohort includes 115 consecutive patients that underwent admission contrast-enhanced CT of the abdomen and pelvis for blunt trauma with pelvic ring disruption followed by conventional angiography. Major arterial injury requiring angioembolization served as the outcome variable. Angioembolization was required in 73/115 patients (63% of the cohort). Average age was 46.9 years (±SD 20.4). Body composition measurements were determined as 2-dimensional (2D) or 3-dimensional (3D) parameters and included mid-L3 trabecular bone attenuation, abdominal visceral fat area or volume, and percent muscle fat fraction (as a marker of sarcopenia) measured using segmentation and histogram analysis. Models incorporating 2D (Model B) or 3D markers (model C) of body composition showed improvement over the original Baltimore model (model A) in all parameters of performance, quality, and fit (area under the receiver-operating curve [AUC], Akaike information criterion, Brier score, Hosmer-Lemeshow test, and adjusted-R2). Area under the receiver-operating curve increased from 0.83 (A), to 0.86 (B), and 0.88 (C). The greatest improvement was seen with 3D parameters. Once automated, quantitative visualization tools providing "free" 3D body composition information can be expected to improve personalized precision diagnostics, outcome prediction, and decision support in patients with bleeding pelvic fractures.

За едно приложение за добавена реалност в уеб базирана среда и 2D баркод маркери

The article presents the developed augmented reality software application requiring minimal resources for its development and implementation. The application is developed on a webbased platform and uses 2D markers. The AR.js open source JavaScript library is used as a development environment.

Structural MRI correlates of cognitive function in multiple sclerosis

BackgroundCognitive impairment (CI) has been associated with numerous magnetic resonance imaging (MRI) indices in multiple sclerosis (MS) patients. In this study we investigated the association of a large set of 2D and 3D MRI markers with cognitive function in MS. MethodsA sample of 61 RRMS patients (mean age 41.8 ± 10.6 years old, 44 women, mean disease duration 137.9 ± 83.9 months) along with 51 age and gender matched healthy controls was used in this cross-sectional study. Neuropsychological and other tests, along with a large set of 2D/3D MRI evaluations were made. Results44.3% of patients had CI. CI patients had more disability, physical fatigue than non-CI patients and more psychological distress than non-CI patients and HCs. Also, CI patients had significantly larger third ventricle width and volume, smaller coprus callosum index and larger lesion volume than non-CI patients. These MRI markers also significantly predicted cognitive scores after adjusting for age and education, explaining about 30.6% of the variance of the total cognitive score. ConclusionsSelected linear and volumetric MRI indices predict cognitive function in MS. Future studies should expand these results by exploring longitudinal changes and producing normative data.

Chapter 13 - Live-Cell CLEM of Subcellular Targets: An Optimized Procedure for Polymer-Based Imaging Substrates

Live-cell correlative light and electron microscopy permits the visualization of ultrastructure details associated with dynamic biological processes. On the optical level, fluorescence microscopy can be further combined with functional studies of intracellular processes and manipulation of biological samples using laser light. However, the major challenge is to relocate intracellular compartments in three dimensions after the sample has undergone an extensive EM sample preparation process. Here, we describe a detailed protocol for live-cell CLEM that provides easy guidance for 3D relocalization. Based on the use of the novel polymer film TOPAS as direct imaging substrate, we provide a setup that uses highly visible toner particles for tracking the region of interest in 2D and fiducial markers for the 3D relocation of intracellular structures. An example is given where a single mitochondria is targeted by laser microirradiation in live-cell fluorescence microscopy. After relocating the same structure in 3D in serial EM sections, the changes to the mitochondrial ultrastructure are observed by TEM. The method is suitable for correlation of live-cell microscopy of cells and can be performed using any inverted optical microscope.

Tracking of Markers for 2D and 3D Gait Analysis Using Home Video Cameras

This work presents the development of an affordable optical motion-capture system which uses home video cameras for 2D and 3D gait analysis. The 2D gait analyzer system consists of one camcorder and one PC while the 3D gait analyzer system uses two camcorders, a flash and two PCs. Both systems make use of 25 fps camcorder, LED markers and technical computing software to track motions of markers attached to human body during walking. In the experiment for 3D gait analyzer system, the two cameras are synchronized by using flash. The recorded videos for both systems are extracted into frames and then converted into binary images, and bridge morphological operation is applied for unconnected pixel to facilitate marker detection process. Least distance method is then employed to track the markers motions, and 3D Direct Linear Transformation is used to reconstruct 3D markers positions. The correlation between length in pixel and in the real world resulted from calibration process is used to reconstruct 2D markers positions. To evaluate the reliability of the 2D and 3D optical motion-capture system developed in the present work, spatio-temporal and kinematics parameters calculated from the obtained markers positions are qualitatively compared with the ones from literature, and the results show good compatibility.

Acute response to oral calcium loading in pregnant and lactating women with a low calcium intake: a pilot study

SummaryThis pilot study in women from The Gambia with low habitual calcium intakes showed differences in calciotropic hormones between pregnant, lactating and non-pregnant, non-lactating women similar to those in Western women. The response to oral calcium loading indicates a high degree of calcium conservation independent of reproductive status.IntroductionIn pregnancy and early lactation, parathyroid hormone (PTH) concentrations may be suppressed. Uncertainty exists about how calcium metabolism is regulated, particularly when calcium intake is low.MethodsWe investigated fasting markers of calcium metabolism and the acute calcemic and calciuric responses after an oral calcium load in 30 pregnant, lactating or non-pregnant, non-lactating (NPNL) Gambian women with low habitual calcium intakes. Women received 1 g elemental calcium (CaCO3) at 0 min. Blood was collected at −30 and 180 min. Urine was collected from −60 to 0, 0–120 and 120–240 min. Samples were analysed (blood: ionized calcium (iCa); plasma (p): total calcium (tCa), phosphate (P), creatinine (Cr), PTH, 1,25-dihydroxyvitamin D (1,25(OH)2D), osteocalcin (OC), β C-terminal cross-linked telopeptide of type 1 collagen (βCTX), cyclic adenosine monophosphate (cAMP); urine (u): Ca, P, Cr, cAMP).ResultsPre-loading, groups did not differ significantly in iCa, pP, uCa/Cr and uP/Cr. pOC concentrations were significantly lower and NcAMP and p1,25(OH)2D higher in pregnant women; pPTH and pβCTX in lactating women were higher than in NPNL women. Post-loading, iCa, ptCa and uCa/Cr concentrations increased; pPTH, NcAMP, βCTX and uP/Cr decreased in all groups, but the magnitude of change did not differ significantly between groups.ConclusionDifferences between pregnant, lactating and NPNL Gambian women in pPTH, NcAMP and p1,25(OH)2D and bone markers were similar to Western women. However, the response to calcium loading indicates that there may be no differences in renal and intestinal calcium economy associated with reproductive status, potentially due to a high degree of calcium conservation associated with low intakes.

Species Difference between Cynomolgus Monkeys and Humans on Cytochromes P450 2D and 3A-Dependent Drug Oxidation Activities in Liver Microsomes

Cynomolgus monkeys [Macaca fascicularis (mf)] are widely used to determine pharmacokinetics and toxicological potential of many drug candidates as human models in the drug discovery and development. Cytochrome P450s (P450, CYP), one of the most important enzymes in drug metabolism, in monkey livers are generally similar to corresponding human P450s exhibiting high degrees of homologies in cDNAs and amino acid sequences. Species differences regarding important liver P450 3A and 2D function were examined between cynomolgus monkeys and humans using typical human P450 probe reactions using midazolam (a P450 3A marker), dextromethorphan and bufuralol (P450 2D markers). P450 3A-mediated midazolam 1'-hydroxylation activities in liver microsomes from individual monkey were highly correlated with midazolam 4'-hydroxylation activities but not correlated with dextromethorphan N-demethylation activities. Recombinant monkey CYP2D17 and CYP2D44 catalyzed dextromethorphan O- and N-demethylations as well as monkey mfCYP3A4 and mfCYP3A5 did. On the other hand, contributions of corresponding P450 2D6 and P450 3A4/5 to dextromethorphan N- and O-demethylations, in human liver microsomes were negligible under the present conditions. From these results, monkey P450 2D and 3A enzymes might have broader substrate specificity toward dextromethorphan oxidation than those in human livers. Special attention should be paid when enzymatic and pharmacokinetic data are extrapolated from monkeys to humans.

Ethnic differences in parathyroid hormone secretion and mineral metabolism in response to oral phosphate administration

Ethnic differences in bone metabolism have been reported and it has been suggested that these may be partly due to prolonged exposure to an elevated plasma parathyroid hormone (PTH) concentration or a decreased sensitivity to PTH. We explored ethnic differences in bone and mineral metabolism by 5 days of oral phosphate (P) loading to stimulate PTH secretion. Healthy older people from UK (B), The Gambia (G) and China (C), 15 individuals from each sex and ethnic group, were studied. Blood and urine samples were collected before and 2 h after P dose on days 1, 4 and 5 and on a control day. The induced changes (%) in PTH and markers of mineral and bone metabolism after 2 h and over 5 days were examined.At baseline, PTH, 1,25(OH)2D and bone turnover markers were higher in Gambian subjects than in British and Chinese subjects (P≤0.01).2 h after P loading, ionized calcium (iCa) decreased and PTH and plasma P (P) increased in all groups (P≤0.01, n.s. between groups). Urinary P to creatinine ratio (uP/Cr) increased, the increase being greater in Chinese subjects than in British and Gambian subjects on days 4 and 5 (P≤0.01). By day 5, fasting iCa was decreased and P increased in British and Gambian (P≤0.01) but not in Chinese subjects. Fasting PTH and uP/Cr increased in all groups. There were ethnic differences in changes in bone markers, but the relationship with changes in PTH was comparable between groups.In conclusion, ethnic differences in mineral metabolism in response to 5-day P loading were found. Chinese subjects showed a more rapid renal clearance of P than British and Gambian counterparts and there were differences between the groups in the skeletal response to P loading, but no evidence was found for resistance to the resorbing effects of PTH.

Visual Enhancement for Sports Entertainment by Vision-Based Augmented Reality

This paper presents visually enhanced sports entertainment applications: AR Baseball Presentation System and Interactive AR Bowling System. We utilize vision-based augmented reality for getting immersive feeling. First application is an observation system of a virtual baseball game on the tabletop. 3D virtual players are playing a game on a real baseball field model, so that users can observe the game from favorite view points through a handheld monitor with a web camera. Second application is a bowling system which allows users to roll a real ball down a real bowling lane model on the tabletop and knock down virtual pins. The users watch the virtual pins through the monitor. The lane and the ball are also tracked by vision-based tracking. In those applications, we utilize multiple 2D markers distributed at arbitrary positions and directions. Even though the geometrical relationship among the markers is unknown, we can track the camera in very wide area.

Relationships between bone mineral density, serum vitamin D metabolites and calcium:phosphorus intake in healthy perimenopausal women.

To determine the relationships between serum vitamin D metabolites, bone mass, and dietary calcium and phosphorus in a cohort of 510 healthy Danish perimenopausal women. A population-based cross-sectional study. A total of 510 healthy women aged 45-58 years, with amenorrhoea for 3-24 months. None of the women was using hormone replacement therapy. Measurements of total bone mineral content and regional bone mineral density were performed by dual-energy X-ray absorptiometry. Analyses of serum levels of 25-OHD and 1,25-(OH)2D, intact PTH, ionized calcium and phosphate, as well as biochemical markers of bone turnover in blood and urine. Assessment of calcium and phosphorus intake using dietary records. A consistent inverse relationship between serum 1,25-(OH)2D and bone mineral content/ density was found in whole-body mineral content (P = 0.001), spine (P = 0.005) and femoral neck (P<0.05). There was a positive relationship between levels of 1,25-(OH)2D and biochemical bone markers, indicating that high levels of 1,25-(OH)2D are accompanied by increased bone turnover. The dietary calcium:phosphorus ratio was inversely related to serum 1,25-(OH)2D (P = 0.04) and positively related to bone mineral density (P<0.0005). No relationships could be detected between levels of PTH, serum ionized calcium and phosphate, and serum vitamin D metabolites. Within normal physiological range, elevated levels of 1,25-(OH)2D were associated with decreased bone mineral density and content, reduced calcium:phosphorus ratio in the diet and increased bone turnover.