Independent and combined effects of obesity and traumatic joint injury to the structure and composition of rat knee cartilage.

Osteoarthritis (OA) is a multifactorial joint disease characterized by articular cartilage degradation. Risk factors for OA include joint trauma, obesity, and inflammation, each of which can affect joint health independently, but their interaction and the associated consequences of such interaction were largely unexplored. Here, we studied compositional and structural alterations in knee joint cartilages of Sprague-Dawley rats exposed to two OA risk factors: joint injury and diet-induced obesity. Joint injury was imposed by surgical transection of anterior cruciate ligaments (ACLx), and obesity was induced by a high fat/high sucrose diet. Depth-dependent proteoglycan (PG) content and collagen structural network of cartilage were measured from histological sections collected previously in Collins et al.. (2015). We found that ACLx primarily affected the superficial cartilages. Compositionally, ACLx led to reduced PG content in lean animals, but increased PG content in obese rats. Structurally, ACLx caused disorganization of collagenous network in both lean and obese animals through increased collagen orientation in the superficial tissues and a change in the degree of fibrous alignment. However, the cartilage degradation attributed to joint injury and obesity was not necessarily additive when the two risk factors were present simultaneously, particularly for PG content and collagen orientation in the superficial tissues. Interestingly, sham surgeries caused a through-thickness disorganization of collagen network in lean and obese animals. We conclude that the interactions of multiple OA risk factors are complex and their combined effects cannot be understood by superposition principle. Further research is required to elucidate the interactive mechanism between OA subtypes.

Understanding the Korean Dialysis Cohort for Mineral, Vascular Calcification, and Fracture (ORCHESTRA) Study: Design, Method, and Baseline Characteristics.

INTRODUCTION: End-stage renal disease (ESRD) is a growing disease worldwide, including Korea. This is an important condition that affects patient outcome. To provide optimal management for mineral disturbance, vascular calcification, and bone disease in ESRD patients, the Korean dialysis cohort for mineral, vascular calcification, and fracture (ORCHESTRA) study was conducted by enrolling Korean dialysis patients. METHODS: Sixteen university-affiliated hospitals and one Veterans' Health Service Medical Center participated in this study. This prospective cohort study enrolled approximately 900 consecutive patients on dialysis between May 2019 and January 2021. Enrolled subjects were evaluated at baseline for demographic information, laboratory tests, radiologic imaging, and bone mineral densitometry (BMD) scans. After enrollment, regular assessments of the patients were performed, and their biospecimens were collected according to the study protocol. The primary outcomes were the occurrence of major adverse cardiovascular events, invasive treatment for peripheral artery disease, and osteoporotic fractures. The secondary outcomes were hospitalization for cerebrovascular disease or progression of abdominal aortic calcification. Participants will be assessed for up to 3 years to determine whether primary or secondary outcomes occur. RESULTS: Between May 2019 and January 2021, all participating centers recruited 900 consecutive dialysis patients, including 786 undergoing hemodialysis (HD) and 114 undergoing peritoneal dialysis (PD). The mean age of the subjects was 60.4 ± 12.3 years. Males accounted for 57.7% of the total population. The mean dialysis vintage was 6.1 ± 6.0 years. The HD group was significantly older, had a longer dialysis vintage, and more comorbidities. Overall, the severity of vascular calcification was higher and the level of BMD was lower in the HD group than in the PD group. CONCLUSION: This nationwide, multicenter, prospective cohort study focused on chronic kidney disease-mineral and bone disorder and aimed to provide clinical evidence to establish optimal treatment guidelines for Asian dialysis patients.

Performance of Progressive Generations of GPT on an Exam Designed for Certifying Physicians as Certified Clinical Densitometrists.

BACKGROUND: Artificial intelligence (AI) large language models (LLMs) such as ChatGPT have demonstrated the ability to pass standardized exams. These models are not trained for a specific task, but instead trained to predict sequences of text from large corpora of documents sourced from the internet. It has been shown that even models trained on this general task can pass exams in a variety of domain-specific fields, including the United States Medical Licensing Examination. We asked if large language models would perform as well on a much narrower subdomain tests designed for medical specialists. Furthermore, we wanted to better understand how progressive generations of GPT (generative pre-trained transformer) models may be evolving in the completeness and sophistication of their responses even while generational training remains general. In this study, we evaluated the performance of two versions of GPT (GPT 3 and 4) on their ability to pass the certification exam given to physicians to work as osteoporosis specialists and become a certified clinical densitometrists. The CCD exam has a possible score range of 150 to 400. To pass, you need a score of 300. METHODS: A 100-question multiple-choice practice exam was obtained from a 3rd party exam preparation website that mimics the accredited certification tests given by the ISCD (International Society for Clinical Densitometry). The exam was administered to two versions of GPT, the free version (GPT Playground) and ChatGPT+, which are based on GPT-3 and GPT-4, respectively (OpenAI, San Francisco, CA). The systems were prompted with the exam questions verbatim. If the response was purely textual and did not specify which of the multiple-choice answers to select, the authors matched the text to the closest answer. Each exam was graded and an estimated ISCD score was provided from the exam website. In addition, each response was evaluated by a rheumatologist CCD and ranked for accuracy using a 5-level scale. The two GPT versions were compared in terms of response accuracy and length. RESULTS: The average response length was 11.6 ±19 words for GPT-3 and 50.0±43.6 words for GPT-4. GPT-3 answered 62 questions correctly resulting in a failing ISCD score of 289. However, GPT-4 answered 82 questions correctly with a passing score of 342. GPT-3 scored highest on the "Overview of Low Bone Mass and Osteoporosis" category (72 % correct) while GPT-4 scored well above 80 % accuracy on all categories except "Imaging Technology in Bone Health" (65 % correct). Regarding subjective accuracy, GPT-3 answered 23 questions with nonsensical or totally wrong responses while GPT-4 had no responses in that category. CONCLUSION: If this had been an actual certification exam, GPT-4 would now have a CCD suffix to its name even after being trained using general internet knowledge. Clearly, more goes into physician training than can be captured in this exam. However, GPT algorithms may prove to be valuable physician aids in the diagnoses and monitoring of osteoporosis and other diseases.

Fracture Risk Assessment Tool-Based Screening for Osteoporosis in Older Adults in Resource-Limited Settings.

PURPOSE: Osteoporosis is a pressing public health concern among older adults, contributing to substantial mortality and morbidity rates. Low- to middle-income countries (LMICs) often grapple with limited access to dual-energy X-ray absorptiometry (DXA), the gold standard for early osteoporosis detection. This study aims to assess the performance of the FRAX® score as a population-wide screening tool for predicting osteoporosis risk, rather than fracture, in individuals aged 50 and above within an LMIC context. METHODS: This retrospective cohort study (n=864) assessed the performance of the FRAX® score for predicting osteoporosis risk using comparative c-statistics from Receiver Operating Characteristic (ROC) curves. Hazard ratios (HR) and 95 % confidence intervals (CI) were calculated, with p-values <0.05 indicating statistically significant. RESULTS: The 10-year FRAX® probability for hip fracture, calculated without bone mass density (BMD), exhibited significantly superior performance compared to the 10-year FRAX® probability for major fracture in predicting osteoporosis risk (AUROC: 0.71 versus 0.67, p<0.001). Within 2 to 10 years of follow-up, the 10-year FRAX® probability for hip fracture showed both greater predictive performance and net benefit in the decision curve compared to the FRAX® 10-year probability for major fracture. A newly established cutoff of 1.9 % yielded a negative predictive value of 92.9 % (95 %CI: 90.4-94.8 %) for the 10-year FRAX® probability for hip fracture. CONCLUSION: The 10-year FRAX® probability for hip fracture estimated without BMD emerges as an effective 10-year screening tool for identifying osteoporosis risk in aged 50 and older, especially when confronted with limited access to DXA scans in LMICs. MINI ABSTRACT: The Fracture Risk Assessment Tool score performance as an osteoporosis screening tool was assessed in areas with limited dual-energy X-ray access. The hip fracture probability showed better performance than major fracture probability within 2 to 10 years. The tool emerges as effective for screening osteoporosis risk in individuals over 50.

Lumbar spine densitometry in people with spinal cord injury: Investigation of potential sources of errors.

PURPOSE: People with spinal cord injury (SCI) experience a considerable loss of bone after the injury. Lumbar spine (LS) bone mineral density (BMD) has been reported to be within the normal range, or even higher when assessed with DXA, in people with SCI; hence, it has been hypothesized that sources of error may spuriously increase LS BMD. The aim of this study was to describe the frequency of potential sources of error that may alter LS BMD measurement in a cohort of individuals with chronic SCI at baseline and over a 2-year period. METHODS: We analyzed baseline and 2-year follow up DXA scans (Hologic Discovery QDR 4500, Hologic Inc., MA, USA) previously performed from a cohort of males and females with chronic SCI. Two physicians independently reviewed each scan, commented on whether the scan was appropriate for BMD analysis, should be re-analyzed, or be removed from the dataset, and reported on the presence of potential sources of error in LS BMD measurement. RESULTS: We reviewed 115 lumbar spine DXA scans from 58 participants, and 107 (93.0 %) scans from 52 participants presented at least one potential source of error. At baseline, the average number of potential sources of error per scan was 5.5 ± 1.7 and 5.7 ± 1.5 according to rater 1 and rater 2, respectively. Follow-up scans presented an average of 5.6 ± 1.6 and 5.7 ± 1.4 potential sources of error according to rater 1 and rater 2, respectively. Facet sclerosis, osteophytes and difficulty in detecting bone edges were the most prevalent sources of error. CONCLUSION: The high frequency of potential sources of error is consistent with current recommendations against the use of LS BMD for fracture risk assessment in people with SCI.

Osteopenia and Osteoporosis Screening Detection: Calcaneal Quantitative Ultrasound with and without Calibration Factor Comparison to Gold Standard Dual X-ray Absorptiometry.

BACKGROUND: osteoporosis is a worldwide major health problem that normally diagnosed in advanced stages. So, an early detection at preclinical stage is now an interesting issue. A key factor to early diagnosis the disease is the used of noninvasive bone densitometry. Dual energy x-ray absorptiometry (DXA) is the gold standard techniques for the proposed. However, the high cost, non-widely available and exposed to ionizing radiation are still a drawback of the machine. Therefore, a cheaper, smaller and non-ionizing device such quantitative ultrasound (QUS) is now a favor alternative method, but the possibility of used QUS measurement instead of DXA is still limited due to their uncertainties. So, the aim of our study was to calibrated the QUS with the DXA to allowing the possible to establish a calibration factor (CF) to improve the measured value closer to the standard method. METHODOLOGY: 135 healthy men and women aged 30-88 years were recruited for lumbar spine/femoral neck DXA and calcaneal QUS scanning. The Pearson's correlation between T- and Z-score from the two systems were studied. Moreover, the sensitivity, specificity and percentage of diagnosed accuracy for both with and without CF were calculated. RESULTS: The significant correlation between the two systems showed a positive trajectory in highly correlation (r = 0.784-0.899). Analyses showed a higher sensitivity, specificity and reduced the misdiagnosed rates when applied the CF in QUS values. CONCLUSIONS: QUS results showed a significantly correlated with DXA results for both lumbar spine and femoral neck sites with some percentage differences. These differences can be reduced by applied an individual specific machine CF to improve a QUS results. As identification of high risk of osteopenia and osteoporosis to reduce the demand of DXA propose, using a QUS alternative method can be a reliable that provide a cheaper and lack of ionizing radiation.

Monitoring the transition from corneal ulceration to healed scar using a Scheimpflug tomography-based densitometry.

PURPOSE: To compare corneal haze between active ulcer and healed scarring using a Scheimpflug densitometry. MATERIALS AND METHODS: A prospective longitudinal study enrolled 30 patients (30 eyes) with ulcerative keratitis (UK). Each subject's corneal optical density (COD) was measured with a Scheimpflug corneal densitometry, Pentacam® AXL (Oculus GmbH, Wetzlar, Germany), at the active ulcerative and complete scarring stage. The COD data were analyzed through distinct methods (inbuilt, sorted annular partitions, and ulcer-matching densitometric maps). We compared different CODs to select the better index for clinically monitoring the transition from corneal ulceration to healed scar. RESULTS: The CODs of the periphery (P = 0.0024) and outside of the active ulcer (P = 0.0002) significantly decreased after scarring. Partitioning the cornea into different depths and annular zones, the anterior layer, center layer, and the 2-6 mm annular zone had a more remarkable COD decrease after scar formation. The 3rd-sorted COD in the anterior layer revealed the highest area under the receiver-operating characteristic curves (0.709), in which 90% of subjects had COD reduction during the ulcer-to-scar transition. CONCLUSIONS: Aside from subjective judgment based on clinical signs, the Scheimpflug tomography-based densitometry could provide objective and efficient monitoring of the corneal opacity evolution in UK patients. Because the 3rd-sorted annular COD is a better index than the inbuilt or mapping CODs in differentiating active ulcers from healed scars, this COD could be a clinically promising parameter to monitor the progression of UK patients.

Corneal densitometry in Chinese adults with healthy corneas: associations with sex, age, ocular metrics, and optical characteristics.

BACKGROUND: Standardized corneal densitometry (CD) values in large samples of healthy Chinese individuals are scarce. Therefore, we aimed to determine the standard CD values using a Scheimpflug camera in healthy corneas, investigate the correlations of sex, age, and ocular parameters with corneal density, and explore the impact of corneal density on the forward scattering and optical quality of the eye. METHODS: This retrospective observational study involved 990 healthy Chinese individuals, including 494 males and 496 females (mean age: 23.88 ± 6.90 years). The CD values at various depths and radial areas of 0-12 mm were measured using a Scheimpflug camera. Densitometric measurements were expressed in standardized grayscale units (GSU). The optical scatter index (OSI), modulation transfer function cutoff values (MTFcutoff), and Strehl's ratio (SR) were also determined using an optical quality analysis system. RESULTS: The average CD within a 12 mm diameter area was 16.26 ± 1.35 GSU. The highest and lowest optical densities at different depths were observed in the anterior (21.41 ± 2.16 GSU) and posterior (12.00 ± 1.01 GSU) layers, respectively (P < 0.001). Similarly, the maximum and minimum optical densities at different radial areas were observed in the 10-12 mm (14.09 ± 0.93 GSU) and 2-6 mm (25.93 ± 4.77 GSU) circles, respectively (P < 0.001). There was no significant difference in the average CD within a 12 mm diameter area between males and females (P > 0.05). However, upon adjusting for age, central corneal thickness (CCT), corneal curvature, white-to-white (WTW) corneal diameter, and axial length, females exhibited a greater average CD within the 12 mm diameter and in the 6-10 mm and 10-12 mm circles than males. Age-related changes in CD were evident, except in the 2-6 mm circle. CCT, corneal curvature, WTW corneal diameter, and partial depth correlated with CD in the radial area, and CD in different areas correlated with the OSI, MTFcutoff, and SR (P < 0.05). CONCLUSIONS: This study provides the normative CD measurement data of Chinese adults with healthy corneas, emphasizing the significance of sex, age, CCT, corneal curvature, and WTW corneal diameter in CD evaluation. Notably, elevated CD can lead to increased forward scattering within the eye, thereby affecting the optical quality.

Visual pigment concentration and photoreceptor outer segment length in the human retina.

PURPOSE: The Beer-Lambert law suggests that visual pigment optical density (OD) should be linearly related to the length of photoreceptor outer segments (POSs). Mammalian studies indicate that visual pigment concentration increases with POS length, but the nature of this relationship may vary due to factors such as visual pigment packing density or retinal eccentricity, and may not necessarily be linearly related. The purpose of this study was to establish the relationship between OD and POS length in humans. METHODS: Spectral domain optical coherence tomography (OCT) was used to image POS, and imaging retinal densitometry (IRD) was used to measure OD at corresponding locations in 19 healthy participants (age range 25-82 years). POS length and OD measurements were extracted from OCT and IRD images at 23 discrete locations spanning the central 9° of the retina. The averaged data from all participants were fitted with models based on the Beer-Lambert law to establish the relationship between OD and POS length. RESULTS: Visual pigment OD increased monotonically with POS length, but the relationship was non-linear, and a straight-line fit, based on a simple interpretation of the Beer-Lambert law, provided a poor description. A model allowing for different rod and cone visual pigment concentrations provided a superior fit. Specifically, the data were well described by a model where the molar concentration of visual pigment in cones and rods were 3.8 × 10-3 mol/L and 1.8 × 10-3mol/L, respectively. CONCLUSIONS: In accordance with the Beer-Lambert law, the results indicate that OD increases monotonically with POS length in humans, but the precise relationship is dependent on photoreceptor type. These results suggest that visual pigment concentration in rods is only about 48% of that found in cones. This may be due to the ubiquitous nature of artificial light that works to reduce the concentration of rhodopsin in rod photoreceptors.

Paediatric dominant and non-dominant handgrip reference curves and the association with body composition.

BACKGROUND: Lack of paediatric reference data limits the utility of handgrip strength as a measure of fitness and well-being. AIM: To develop paediatric handgrip reference curves and evaluate associations with body size and composition and race/ethnicity group. SUBJECTS AND METHODS: Handgrip, body size and composition data were obtained from National Health and Nutrition Examination Survey 2011-2014 participants aged 6-20 years. Densitometry-derived fat and appendicular lean soft tissue mass index Z-scores (FMIZ, ALSTMIZ) were generated in participants >8 years. Dominant and non-dominant handgrip reference curves were created using the LMS method. Analyses included sample weights to produce nationally representative estimates. RESULTS: Differences in handgrip strength according to hand dominance increased with age. Handgrip strength was associated with height and arm length Z-scores (R = 0.42 to 0.47) and ALSTMIZ (R = 0.54). Handgrip strength was higher in the non-Hispanic Black group and lower in the Mexican American compared to non-Hispanic White group. Group differences were attenuated when adjusted for height, arm length or ALSTMIZ. CONCLUSION: Paediatric handgrip reference curves were generated from which individual Z-scores can be calculated separately for dominant versus non-dominant hand and adjusted for body size. Association with ALSTMIZ suggests handgrip Z-score may be used as a measure of functional body composition.

Selection of X-ray Tube Settings for Relative Bone Density Quantification in the Knee Joint of Cats Using Computed Digital Absorptiometry.

Bone mineral density (BMD) varies with aging and both systemic and local diseases; however, such evidence is lacking in feline medicine. This may be due to the need for general anesthesia in cats for direct BMD measurements using dual-energy X-ray absorptiometry (DXA) or quantitative computed tomography (QCT). In this study, computed digital absorptiometry (CDA), an indirect relative BMD-measuring method, was optimized to select an X-ray tube setting for the quantitative assessment of the feline knee joint. The knee joints of nine cats were radiographically imaged and processed using the CDA method with an aluminum density standard and five X-ray tube settings (from 50 to 80 kV; between 1.2 and 12 mAs). The reference attenuation of the X-ray beam for ten steps (S1-S10) of the density standard was recorded in Hounsfield units (HU), compared between X-ray tube settings, and used to determine the ranges of relative density applied for radiograph decomposition. The relative density decreased (p < 0.0001) with an increase in kV and dispersed with an increase in mAs. Then, the percentage of color pixels (%color pixels), representing ranges of relative density, was compared among S1-S10 and used for the recognition of background artifacts. The %color pixels was the highest for low steps and the lowest for high steps (p < 0.0001), regardless of X-ray tube settings. The X-ray tube setting was considered the most beneficial when it effectively covered the lowest possible HU ranges without inducing background artifacts. In conclusion, for further clinical application of the CDA method for quantitative research on knee joint OA in cats, 60 kV and 1.2 mAs settings are recommended.

Lung densitometry in postmortem computed tomography - comparison across different fatal asphyxia groups.

Asphyxia as a cause of death poses a diagnostic challenge in forensic medicine due to both the diversity of underlying mechanisms, and lack of specific markers. Acute emphysema or acute alveolar dilation have long been debated as potential findings in these asphyxia cases. To further explore the supplementary findings in our forensic asphyxia cases, this study applied lung densitometry to pulmonary postmortem computed tomography (PMCT) data. Twenty asphyxia cases (including hanging (n = 9), manual strangulation (n = 4), ligature strangulation (n = 1), smothering (n = 3), and choking (n = 3)) and 21 matched control cases were analysed using lung densitometry parameters - specifically quantification of low attenuation areas (LAA) and the 15th percentile point of lung density (Perc15). Our data revealed statistically significantly higher lung % volume falling within LAA at -950HU (p = 0.04) and - 910HU (p = 0.043) in the asphyxia cases compared to matched controls. The Perc15 values observed were trending towards a lower attenuation corresponding to a lower density in the asphyxia group, although this result was not statistically significant (p = 0.13). A subgroup analysis highlighted potential differences within the asphyxia categories, notably, higher Perc15 values were observed in the choking cases. In conclusion the results from the study support the existing evidence of low pulmonary density as a potential finding in asphyxia cases and demonstrate the potential of applying lung densitometry on pulmonary postmortem computed tomography data.

Diagnostic value of corneal optical densitometry in keratoconus.

PURPOSE: To investigate the clinical significance of the correlation between optical densitometry and both biomechanical and morphological parameters in keratoconus (KC) and to verify the diagnostic value of optical densitometry in KC. METHOD: This cross-sectional study included 436 eyes of 295 patients with KC. Corneal optical densitometry, morphological parameters and biomechanical parameters were measured. Spearman's correlation analysis was employed to investigate the association between optical densitometry and both biomechanical and morphological parameters. RESULT: Optical densitometry of the anterior (0-2 mm and 2-6 mm), central (0-2 mm), posterior (2-6 mm) and total (2-6 mm) layers correlated positively with SPA1, while the posterior layer (0-2 mm) correlated negatively. Optical densitometry of the anterior layers 2-6 mm, 6-10 mm, and the central layer 6-10 mm negatively affected AL1, while the posterior layer 0-2 mm positively affected it. Optical densitometry of the anterior, central, and posterior layers 0-2 mm and 2-6 mm positively influenced the morphological parameters K1F, K2F, KmF and the absolute values of K1B, K2B, KmB. Optical densitometry of the center (0-2 mm) and posterior (2-6 mm) layers negatively influenced TCT. Optical densitometry of the anterior (0-2 mm and 2-6 mm), center (0-2 mm), posterior (2-6 mm) and total (2-6 mm) layers correlated positively with ACE and PCE, whereas the posterior layer (0-2 mm) correlated negatively. CONCLUSION: Optical densitometry was correlated with biomechanical and morphological parameters in keratoconus, suggesting its potential as a diagnostic indicator for assessing keratoconus progression and treatment efficacy.

Accelerated Method for Determining Ischemic Brain Damage in Rats and Assessment the Neuroprotective Effect of a Complex Herbal Remedy.

The severity of ischemic injury was evaluated by densitometry of brain samples stained with 2,3,5-triphenyltetrazolium chloride (TTC) on a rat model of cerebral ischemia/reperfusion (common carotid artery occlusion) and the neuroprotective activity of an extract of Astragalus membranaceus, Scutellaria baicalensis, and Phlojodicarpus sibiricus was assessed. Occlusion of the common carotid arteries led to a weakening of TTC staining of the brain tissue: densitometric indicators of the staining intensity for the cortex and striatum were lower than the corresponding indicators of sham-operated rats by 18.3 and 10.4%. The mean intensity of staining of brain samples did not differ in rats treated with the extract and sham-operated animals, which attested to its neuroprotective effect. The applied method is convenient for evaluation of the severity of ischemic brain damage at the early stages and screening potential neuroprotective agents.

Corneal densitometry measurements comparison between anterior segment OCT and scheimpflug imaging.

PURPOSE: To evaluate and compare the repeatability of corneal densitometry (CD) measurements obtained using both an anterior-segment optical coherence tomography (AS-OCT) device and a Scheimpflug camera system, while also assessing the level of agreement. The study also sought to investigate the correlation of CD with age, gender, and central corneal thickness (CCT) in normal eyes. METHODS: CD measurements were obtained using the Casia 2 and the Pentacam AXL Wave. Data were collected on Total Corneal Densitometry and 4 concentric corneal annular areas, these are referred to as zone 1, denoting the central area, through to zone 4, designating the outermost peripheral region. Repeatability was assessed using intra-session test-retest variability, coefficient of variation (CoV), and intraclass correlation coefficient (ICC). The agreement was evaluated using Bland-Altman plots. Correlation analysis was performed between CD, age, gender, and CCT. RESULTS: The study included 96 healthy volunteers. The Casia 2 demonstrated high repeatability with ICC values exceeding 0.9 in all the corneal zones and lower CoV values compared to the Pentacam AXL Wave (ranging from 1.07% to 2.25% for Casia 2 and from 1.91% to 6.89% for Pentacam).95% LoA were within ± 2 standard deviation from the average mean except from zone 1 (± 2.42).However, the measurements showed a consistent bias among all the corneal zones. CD values were positively correlated with age, except for zone 1 with the Pentacam (p = 0.083). CONCLUSIONS: The findings suggest that the Casia 2 can be a reliable tool for assessing corneal transparency in healthy individuals, however its measurements are not interchangeable with those provided by the Pentacam. The AS-OCT device may be more sensitive in detecting subtle age-related changes in CD within the central zone.

The comparison of corneal densitometry in cases with glaucoma following childhood cataract surgery and juvenile glaucoma.

PURPOSE: To compare the corneal densitometry (CD) in pediatric cases with glaucoma following childhood cataract surgery and juvenile open-angle glaucoma (JOAG). METHODS: This prospective comparative study involved 13 eyes with JOAG, 12 eyes with pseudophakic glaucoma, 13 eyes with aphakic glaucoma, and 15 control subjects. Pentacam HR Scheimpflug corneal topography was employed to evaluate corneal thickness (CCT) and CD values. RESULTS: The mean intraocular pressure (IOP) and CCT were significantly higher in aphakic glaucoma cases than the other groups (p = 0.001). In aphakic eyes, the mean CD values were higher in most of the anterior, center, and posterior layers of 0-2 mm, 2-6 mm, 6-10 mm, and total zones (p < 0.001 for all). In pseudophakic eyes, the mean CD values were statistically similar with that of aphakic eyes and higher than that of JOAG and control eyes in all layers of 0-2 mm zone and in anterior layer of 10-12 mm and anterior and total layers of 2-6 mm zones (p < 0.05 for all). The CD values demonstrated significant correlations with CCT values in both aphakic and pseudophakic eyes. However, a significant correlation of CD values with IOP was only demonstrated in aphakic eyes (p = 0.01 for all). CONCLUSION: The probable effects of childhood cataract surgery especially aphakia might cause corneal backscatter of light and increased CD in all layers in all zones of the cornea. Increased CD values and its correlation with CCT and IOP in aphakic glaucoma eyes may be of importance in clinical management.

Densitometry of STR-PAGE for donor chimerism in acute leukemia's: A simple method for routine use.

Objective: To evaluate a PCR based method of polyacrylamide gel electrophoresis of short tandem repeats and its quantification for detecting donor chimerism after haematopoietic stem cell transplantation in acute leukaemias. Methods: The descriptive study was conducted at Genetic Resource Centre (GRC) Lab Rawalpindi from Feb 2018 - Nov 2020. A total of twenty patients with acute leukaemias having undergone HSCT were selected and assessed for the analysis of chimerism status. DNA extraction from the whole blood was done by chelex method and short tandem repeats were amplified by using conventional STR- PCR assay. Electrophoresis was carried out and 6% polyacrylamide gels were used for the resultant amplified DNA products and then followed by their densitometry. These patients had undergone HSCT from Pakistan Institute of Medical Science and Armed Forces Bone Marrow Transplant Centre. Results: The peaks in the PAGE densitometry represented the donor chimerism in all post transplant samples of the patients. Conclusion: Our study showed that densitometry of STR PCR PAGE is a useful and cheaper method for demonstration of donor chimerism in acute leukaemia patients having undergone HSCT. Hence this method can be a valuable option in the monitoring of chimerism status in these patients and therefore helps in preventing graft failure by fast and early treatment strategies for these patients.

[Analysis of indocyanine green plasma disappearance rate in clinical practice]. / Vybor metodiki opredeleniya skorosti plazmennoi eliminatsii indotsianina zelenogo v klinicheskoi praktike.

OBJECTIVE: To justify the optimal method for determining indocyanine green plasma disappearance rate (PDRICG). MATERIAL AND METHODS: We analyzed PDRICG in intensive care units. Indocyanine green was administered intravenously at a dose of 0.25 mg/kg. PDRICG was analyzed simultaneously by using of three methods: 1) PDD (PiCCO2 LiMON device), 2) SBS with analysis of plasma samples on precise spectrophotometer, 3) SBS with analysis of plasma samples on simple experimental photometer. RESULTS: PDD method was used for 346 PDRICG tests in 256 patients. Of these, 14.3% of measurements were erroneous. Paired tests using PDD and SBS methods were performed in 299 cases. SBS method resulted erroneous data in 0.6% of cases. Certain correlation (r=0.79, p<0.001) was found between the reference method (SBS with spectrophotometry) and the PDD method. Bland-Altman plot for these two methods showed that proportional bias of mean difference was caused by extremely high PDRICG of the PDD method (for example, more than 30%/min). Comparison of two SBS variants (spectrophotometer and experimental photometer) revealed good correlation (r=0.91, p<0.001). CONCLUSION: SBS method for measuring PDRICG ensures accurate results under mechanical interferences in patients with impaired capillary blood flow. This eliminates the need for redo measurement. Duplication of the PDD and SBS methods is recommended when repeating the test is not possible (organ donors).

Estimation of Hydration and Density of Fat-Free Mass in Indian Children Using a 4-Compartment Model: Implications for the Estimation of Body Composition Using 2-Compartment Models.

BACKGROUND: Accurate methods are needed to measure body fat mass (FM), particularly in South Asian children who are thought to have greater adiposity for a given body size. The accuracy of simple 2-compartment (2C) models of measuring FM depends on the primary measurement of the fat free mass (FFM) and the validity of assumed constants for FFM hydration and density. These have not been measured in this particular ethnic group. OBJECTIVES: To measure FFM hydration and density in South Indian children using a 4-compartment (4C) model and to compare FM estimates from this 4C-model with 2C-model-based estimates from hydrometry and densitometry, using literature-reported FFM hydration and density in children. METHODS: This study included 299 children (45% boys), aged 6-16 y from Bengaluru, India. Total body water (TBW), bone mineral content (BMC), and body volume were measured using deuterium dilution, dual-energy X-ray absorptiometry, and air displacement plethysmography, respectively, to calculate the FFM hydration and density, and the FM using 4C and 2C models. The agreement between FM estimates from 2C and 4C models was also evaluated. RESULTS: Mean FFM hydration and density were 74.2% ± 2.1% and 71.4% ± 2.0% and 1.095 ± 0.008 kg/L and 1.105 ± 0.008 kg/L in boys and girls respectively, which were significantly different from published values. Using the presently estimated constants, the mean hydrometry-based FM (as % body weight) estimates decreased by 3.5% but increased by 5.2% for densitometry-based 2C methods. When 2C-FM (using previously reported FFM hydration and density) were compared with 4C-FM estimates, the mean difference was -1.1 ± 0.9 kg for hydrometry and 1.6 ± 1.1 kg for densitometry. CONCLUSIONS: Previously published constants of hydration and density of FFM may induce errors of -12% to +17% in FM (kg) when using different 2C models in comparison to the 4C models in Indian children. J Nutr 20xx;x:xx.

Cross-Calibration of iDXA and pQCT Scanners at Rural and Urban Research Sites in The Gambia, West Africa.

Between-scanner differences in measures of bone and body composition can obscure or exaggerate physiological differences in multi-site studies or the magnitude of changes in longitudinal studies. We conducted a cross-calibration study at two bone imaging centres in The Gambia, West Africa where DXA (dual-energy X-ray absorptiometry) and pQCT (peripheral Quantitative-Computed Tomography) are routinely used. Repeat scans were obtained from 64 Gambian adults (58% Male) aged Mean(SD) 30.9 (13.5) years with Mean(SD) body mass index (BMI) 21.7 (4.0) kg/m2, using DXA (GE Lunar iDXA, whole body [WB], total hip [TH], lumbar spine [LS]) and pQCT (Stratec XCT2000L/XCT2000, tibia 4%, 50% sites). Between-scanner differences were tested using paired t tests (p < 0.05). Between-scanner correlation was explored with linear regression, and cross-calibration equations derived. Bland-Altman analysis investigated machine trend/bias. When differences were detected (p < 0.05), cross-calibration equations were applied to urban values, with t tests and Bland Altman analysis repeated. Between-scanner differences exceeded the predefined level of statistical significance (p < 0.05) for WB aBMD and BA; all pQCT measures vBMD, BMC, cortical cross-sectional area (CSA) and stress-strain index (SSI). Between-scanner correlation was high (R2:0.92-0.99), except pQCT Mu.Den (R2 = 0.51). Bland Altman plots indicated bias increased with increasing BMD. Cross-calibration equations attenuated all between-scanner differences and systematic bias. Cross-calibration, particularly of pQCT scanners, is an important consideration in multi-site studies particularly where between population comparisons are intended. Our experiences and findings may be generalisable to other resource-limited settings where the logistics of sourcing parts and in-country repair may result in lengthy scanner downtime.