Histogram-Based Densitometry Index to Assess the Severity of Interstitial Lung Disease in Systemic Sclerosis in Standard and Low-Dose Computed Tomography

OBJECTIVE

Mean lung attenuation, skewness, and kurtosis are histogram-based densitometry variables that quantify systemic sclerosis-associated interstitial lung disease (SSc-ILD) and were recently merged into a computerized integrated index (CII). Our work tested the CII in low-dose 9-slice (reduced) and standard high-resolution computed tomography (CT) scans to evaluate extensive SSc-ILD and predict mortality.

METHODS

CT scans from patients with SSc-ILD were assessed using the software Horos to compute standard and reduced CIIs. Extensive ILD was determined following the Goh staging system. The association between CIIs and extensive ILD was analyzed with a generalized estimating equation regression model, the predictive ability of CIIs by the area under the receiver-operation characteristic curve (AUC), and the association between CIIs and death by Kaplan-Meier analysis.

RESULTS

Among 243 patients with standard and reduced CT scans available, 157 CT scans from 119 patients with SSc-ILD constituted the derivation cohort. The validation cohort included 116 standard and 175 reduced CT scans. Both CIIs from standard (odds ratio [OR] 0.53, 95% CI 0.37-0.75; AUC 0.77, 95% CI 0.68-0.87) and reduced CT scans (OR 0.54, 95% CI 0.35-0.82; AUC 0.78, 95% CI 0.70-0.87) were significantly associated with extensive ILD. A threshold of CII ≤ -0.96 for standard CT scans and CII ≤ -1.85 for reduced CT scans detected extensive ILD with high sensitivity in both derivation and validation cohorts. Extensive ILD according to Goh staging (OR 2.94, 95% CI 1.10-7.82) and standard CII ≤ -0.96 (OR 1.78, 95% CI 1.24-2.56) significantly predicted mortality; a marginal P value was observed for reduced CII ≤ -1.85 (OR 1.27, 95% CI 0.93-1.75).

CONCLUSION

Thresholds for both standard and reduced CII to identify extensive ILD were developed and validated, with an additional association with mortality. CIIs might help in clinical practice when radiology expertise is missing.

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.

Quantitation of Mucin by Densitometry of an Alcian Blue-Stained Membrane

It is a challenging task to quantify mucin using conventional protein quantification methods due to the large number of glycans attached to the peptide, which make up approximately 50-90% of its molecular weight. To address this issue, we propose a simple quantification method that involves spotting mucins onto a membrane and staining them with Alcian blue.

Diagnostic Efficacy of High-Resolution Computed Tomography Densitometry for Diagnosing Otosclerosis

OBJECTIVES

The purpose of this study is to evaluate the reliability of temporal bone density measurements for diagnosing otosclerosis.

MATERIALS AND METHODS

A retrospective case-control study is presented. Bone density was measured in Hounsfield units (HUs) by using high-resolution computed tomography in eight regions of interest (ROI) where otosclerotic foci are usually localized. The density of 113 otosclerotic ears was compared with that of 33 nonotosclerotic ears to determine sensitivity and specificity. Furthermore, the binormal receiver operating characteristic curve of each ROI's density was calculated to estimate the diagnostic value for osteosclerosis. In addition, the radiological density of seven cases-where radiological visual examination exhibited no findings but surgery confirmed stapes fixation-was compared with nonotosclerotic controls.

RESULTS

ROI densities were significantly lower in otosclerotic patients compared with nonotosclerotic controls. The area under the curve of the fissula ante fenestram (FAF) presented the highest diagnostic performance: 1,871 HU cut-off value (area under the curve = 0.986), 96.64% sensitivity, and 100% specificity. Significantly lower densities in the FAF area were observed in the seven cases with negative radiology but intraoperatively confirmed otosclerosis.

CONCLUSION

The high-resolution computed tomography density of the FAF is a reliable measurement for diagnosing otosclerosis. A value less than 1,871 HU exhibited the highest sensitivity and specificity in a European Caucasian population.

Effect of smoking on corneal and lens clarity: a densitometric analysis

PURPOSE

To assess the effect of chronic cigarette smoking on corneal and lens densitometry measurements using Pentacam HR and to compare the results obtained with those in non-smokers.

MATERIALS AND METHODS

This cross-sectional comparative study included 40 chronic-smokers and 40 age-matched healthy non-smokers between 18-40 years. After general ophthalmic examination, the Pentacam HR imaging system was used to evaluate corneal and lens densitometry measurements of smokers and non-smokers.

RESULTS

The mean corneal densitometry values were not statistically significantly different in all the concentric zones and layers in the eyes of the smokers and non-smokers (p > 0.05, for all). However, the mean values of zone 1, zone 2, zone 3 and average lens densitometry measurements of the smokers were statistically significantly higher compared to non-smokers (p < 0.05, for all). Additionally, significant positive correlations were detected between the number of pack-years smoked and lens densitometry measurements.

CONCLUSION

Lens densitometry measurements of smokers were significantly increased while corneal densitometry measurements were not significantly altered compared to non-smokers. Smoking may contribute to cataractogenesis and smoking and age-related changes may act synergistically to cataract development among smokers.

Corneal densitometry patterns in Descemet membrane endothelial keratoplasty and Descemet stripping automated keratoplasty

PURPOSE

To compare corneal densitometry in a consecutive series of 52 endothelial keratoplasties (DMEK/DSAEK) using a Scheimpflug-based device after six months of follow-up.

METHODS

Corneal densitometry (CD) values of 102 eyes were divided into three main groups: 33 DMEKs, 19 DSAEKs, and 50 healthy eyes without previous ocular surgery. The CD values were then analyzed and compared between the groups. We measured three main layers in depth and four different concentric zones at 1, 3, and 6 months postoperatively.

RESULTS

In the DMEK group, total CD significantly decreased from 38.02 ± 10.21 grayscale units (GSU) to 31.13 ± 9.25 GSU (P < 0.01) between the first and the sixth month postoperative. In the DSAEK group, we found significant changes only between the first and three months after surgery (from 42.62 ± 9.31 GSU to 38.71 ± 10.53 GSU (P < 0.01). Regarding the concentric zones, CD in the DMEK group significantly decreased in the central zone from 33.55 ± 12.07 GSU to 30.63 ± 10.15 GSU (P < 0.01) and significantly increased in the periphery from 30.63 ± 10.15 GSU to 36.72 ± 9.37 GSU, (P < 0.01). The DSAEK group showed no changes in the central zone (from 36.91 ± 13.80 GSU to 36.14 ± 11.47 GSU, P = 0.52) and CD significantly increased in the periphery (41.91 ± 9.28 GSU, P < 0.01).

CONCLUSION

When comparing CD values in DMEK versus DSAEK, we found no differences by layers or at central-paracentral concentric zones, although CD differences in the peripheral zones were statistically significant. This finding may be attributed to the thicker graft at periphery with a delayed clearance and less anatomical interphase in DSAEK.

Visual outcomes and corneal densitometry after allogenic and autologous lenticule intrastromal keratoplasty for the correction of moderate-to-high hyperopia

AIM

This study aimed to evaluate the visual outcomes and corneal densitometry (CD) after allogenic lenticule intrastromal keratoplasty (AL-LIKE) and autologous lenticule intrastromal keratoplasty (AU-LIKE) for the correction of moderate-to-high hyperopia.

METHODS

Ten subjects (14 eyes) underwent AL-LIKE and eight (8 eyes) underwent AU-LIKE. Patients were examined preoperatively and 1 day, 1 month, and 6 months postoperatively. The visual outcomes and CD for both surgical methods were evaluated.

RESULTS

No postoperative complications were observed with either method. The efficacy index was 0.85±0.18 and 0.90±0.33 in the AL-LIKE and AU-LIKE groups, respectively. The safety indices were 1.07±0.21 and 1.25±0.37 in the AL-LIKE and AU-LIKE groups, respectively. The CD values of the anterior, central, and posterior layers in the AL-LIKE group increased significantly at 1 day postoperatively (all P < 0.05). The CD values of the anterior and central layers remained significantly higher than the preoperative values at 6 months postoperatively (all P < 0.05). The CD values of the anterior layer in the AU-LIKE group increased significantly 1 day postoperatively (all P < 0.05) and decreased to preoperative values (all P > 0.05) 1 month postoperatively.

CONCLUSION

Both AL-LIKE and AU-LIKE exhibit good efficacy and safety in correcting hyperopia. However, AU-LIKE may have a smaller affected area and faster recovery time than those associated with AU-LIKE related to changes in corneal transparency.

How Does Pupil Size Affect Lens and Corneal Densitometry Measured by Scheimpflug Tomography?

Objectives

To investigate the effects of pupil diameter on the evaluation of lens and corneal densitometry measured by Scheimpflug tomography.

Materials and Methods

This cross-sectional and comparative study used the right eyes of 32 participants. Corneal and lenticular optical densitometries, corneal volume, anterior segment volume, and anterior chamber depth measurements were taken with the Scheimpflug imaging system when the pupils were mid-dilated and fully dilated. The results were statistically compared.

Results

The mean lens density was 19.20±3.05 when the pupils were mid-dilated (mean pupil diameter 2.98±0.89 mm) and 23.25±3.88 at full dilation (mean pupil diameter 5.01±0.92 mm) (p<0.001). The mean corneal density was 16.15±0.99 with mid-dilated pupils and 16.38±0.95 with fully dilated pupils (p=0.065). Anterior chamber depth and anterior segment volume measurements increased with larger pupil diameter (p<0.05).

Conclusion

The lens densitometry values increased with an increase in pupil diameter. The corneal density measurements increased minimally but the differences were not statistically significant. This study revealed that lens densitometry was significantly affected by pupil diameter.

Seven-year corneal densitometry changes after small incision lenticule extraction and femtosecond laser-assisted in situ keratomileusis

This study aims to investigate the 7-year changes in corneal densitometry (CD) after small incision lenticule extraction (SMILE) and femtosecond laser-assisted in situ keratomileusis (FS-LASIK). Forty-two eyes undergoing SMILE and thirty-one undergoing FS-LASIK were included in this retrospective study. CD was measured preoperatively and at 3 and 7 years postoperatively. Three concentric radial zones (0-2, 2-6, and 6-10 mm) of three different corneal depths (anterior 120 μm, posterior 60 μm, and central layer) were analyzed. In all three zones of the three corneal layers, no significant difference in CD was found between the two groups preoperatively and at 3 and 7 years postoperatively (all P > 0.05). All CD values in the three zones of the anterior and central layers significantly declined at 3 years postoperatively (all P < 0.001), and then increased at 7 years postoperatively compared to corresponding 3-year values (all P < 0.01). In the posterior layer, CD values in the 0-2-mm and 2-6-mm zones decreased at 3 years postoperatively (all P < 0.01) and continued to decrease at 7 years postoperatively (all P < 0.01). Similar CD trends were observed after SMILE and FS-LASIK. Posterior layer CD showed a decrease throughout the study period. In the anterior and central layers, CD values decreased and then increased at 7 years postoperatively. The transparency changes might have been due to age-related three-dimensional growth of collagen fibers and wound-healing reactions.

Cost-effectiveness of selective bone densitometry using the osteoporosis self-assessment tool for Asians in multi-ethnic Asian population

Early detection and treatment of osteoporosis can help to prevent debilitating fractures in the elderly. The osteoporosis self-assessment tool for Asians can be used as a screening tool to stratify patients for bone densitometry. It is most cost-effective for post-menopausal women aged 70 and males aged 75.

PURPOSE

To determine the cost-effectiveness of selective bone densitometry (SBD) using the Osteoporosis Self-Assessment Tool for Asians (OSTA) as a risk-stratifying tool for the three predominant races (Chinese, Malay and Indian) in Singapore.

METHODS

Decision analytical models were developed using a Markov model. Three scenarios were compared: no bone densitometry, SBD using the OSTA as a pre-screening tool and universal bone densitometry. Those diagnosed with osteoporosis were treated with five years of alendronate therapy. Data sources were from Singapore epidemiological studies, healthcare cost figures and published literature. Measurements include life years, quality-adjusted life years (QALYs), costs and incremental cost-effectiveness ratios (ICER).

RESULTS

Compared to no bone densitometry, SBD using the OSTA would cost between $40,679 and $73,909 per QALY gained for men aged 75-80 and $22,386 to $58,185 per QALY gained for post-menopausal women aged 70-80. Universal bone densitometry would cost $157,955 to $177,127 per QALY gained for men aged 75-80 and $40,179 to $66,112 per QALY gained for post-menopausal women aged 70 to 80 compared to SBD.

CONCLUSION

In general, osteoporosis screening was the most cost-effective for Malays and the least cost-effective for Indians. However, a general guideline should still be applied to the Singaporean population, as further explained later. Overall, the most cost-effective strategy for males would be using OSTA as a risk-stratifying tool at age 75. For post-menopausal women, SBD should be used for women aged 70, while universal bone densitometry should be used for women aged 75-80.

Suspect glaucoma detection from corneal densitometry supported by machine learning

PURPOSE

To discriminate suspect glaucomatous from control eyes using corneal densitometry based on the statistical modeling of the pixel intensity distribution of Scheimpflug images.

METHODS

Twenty-four participants (10 suspect glaucomatous and 14 control eyes) were included in this retrospective study. Corneal biomechanics was assessed with the commercial Scheimpflug camera Corvis ST (Oculus). Sets of 140 images acquired per measurement were exported for further analysis. After corneal segmentation, pixel intensities corresponding to different corneal depths were statistically modeled for each image, from which corneal densitometry in the form of parameters α (brightness) and β (homogeneity) was derived. After data pre-processing, parameters α and β were input to six supervised machine learning algorithms that were trained, tested, and compared.

RESULTS

There exists a statistically significant difference in α and β parameters between suspect glaucomatous and control eyes (both, P < 0.05/N, Bonferroni). From the implemented supervised machine learning algorithms, the K-nearest neighbors (K-NN) algorithm reached 83.93% accuracy to discriminate between groups only using corneal densitometry parameters (α and β).

CONCLUSION

Densitometry of the anterior cornea including epithelium on its own has the potential to serve as a clinical tool for early glaucoma risk assessment.

Bone densitometry in children with idiopathic nephrotic syndrome on prolonged steroid therapy: A tertiary multicenter study

Long-term glucocorticoids administration inhibits bone mineralization and has a negative impact on basic cellular mechanisms that are critical in the development and maintenance of bone strength. Steroids can cause osteoporosis in children and have a negative impact on bone mineral content (BMC) and bone mineral density (BMD). We aim to determine the BMD of children with idiopathic nephrotic syndrome (INS) who are on corticosteroids therapy. This cross-sectional study included 90 patients on corticosteroids therapy and 50 apparently healthy age and sex-matched children served as a control group. Renal functions, bone biochemistry, and parathyroid hormone (PTH) were measured in patients and controls. BMD was measured at the lumbar spinal region (L2-L4) using Dual-energy X-ray absorptiometry (DEXA) scan in both patients and controls groups. Serum PTH, phosphorous, and alkaline phosphatase levels were significantly higher in patients than in controls. There was a statistically significant reduction in blood calcium levels in patients compared to controls. Osteopenia was diagnosed by DEXA scan in 24 patients (26.7%) and osteoporosis in 12 patients (13.3 %). There was a statistically significant decline in BMD-z score, BMD, and BMC in patients compared to the healthy group. Patients with INS on corticosteroids treatment have a lower BMD than their peers. Pediatric INS patients had a high prevalence of osteopenia and osteoporosis as measured by DEXA. Steroid therapy has a deleterious impact on bone mineralization in children with INS.

A Rare Pitfall in Bone Mineral Densitometry: Gaucher Disease

ABSTRACT

We report a rare case of type 3 Gaucher disease presenting with calcified mesenteric lymph nodes that interfere with bone mineral densitometric measurements.

Quantitative CT lung densitometry as an obstructive marker for the diagnosis of bronchiolitis obliterans in children

The purpose of this study is to evaluate the quantitative diagnostic performance of computed tomography (CT) densitometry in pediatric patients with bronchiolitis obliterans (BO). We measured the mean lung density (MLD) and represented the difference of MLD in inspiratory and expiratory phases (MLDD), the ratio of the MLD (E/I MLD), and the relative volume percentage of lung density at 50-Hounsfield unit (HU) interval threshold (E600 to E950). We calculated the sensitivity, specificity, and diagnostic accuracy of the lung density indices for the diagnosis of BO. A total of 81 patients, including 51 patients with BO and 30 controls, were included in this study. In the BO patients, expiratory (EXP) MLD and MLDD were significantly lower, and E/I MLD and expiratory low attenuation areas below the threshold of −850 HU to −950 HU (E850, E900, and E950) were statistically significantly higher than controls. Multivariate logistic regression analysis showed that MLDD (odds ratio [OR] = 0.98, p < .001), E/I MLD (OR = 1.39, p < .001), and E850 to E950 were significant densitometry parameters for BO diagnosis. In a receiver-operating characteristic analysis, E900 (cutoff, 1.4%; AUC = 0.920), E/I MLD (cutoff, 0.87; AUC = 0.887), and MLDD (cutoff, 109 HU; AUC = 0.867) showed high accuracy for the diagnosis of BO. In conclusion, the lung CT densitometry can serve as a quantitative marker providing additional indications of expiratory airflow limitation in pediatric patients with BO.

Atlas-Based Lung Segmentation Combined With Automatic Densitometry Characterization In COVID-19 Patients: Training, Validation And First Application In A Longitudinal Study

Purpose

To develop and validate an automated segmentation tool for COVID-19 lung CTs. To combine it with densitometry information in identifying Aerated, Intermediate and Consolidated Volumes in admission (CT1) and follow up CT (CT3).

Materials and Methods

An Atlas was trained on manually segmented CT1 of 250 patients and validated on 10 CT1 of the training group, 10 new CT1 and 10 CT3, by comparing DICE index between automatic (AUTO), automatic-corrected (AUTOMAN) and manual (MAN) contours. A previously developed automatic method was applied on HU lung density histograms to quantify Aerated, Intermediate and Consolidated Volumes. Volumes of subregions in validation CT1 and CT3 were quantified for each method.

Results

In validation CT1/CT3, manual correction of automatic contours was not necessary in 40% of cases. Mean DICE values for both lungs were 0.94 for AUTOVsMAN and 0.96 for AUTOMANVsMAN. Differences between Aerated and Intermediate Volumes quantified with AUTOVsMAN contours were always < 6%. Consolidated Volumes showed larger differences (mean: −95 ± 72 cc). If considering AUTOMANVsMAN volumes, differences got further smaller for Aerated and Intermediate, and were drastically reduced for consolidated Volumes (mean: −36 ± 25 cc). The average time for manual correction of automatic lungs contours on CT1 was 5 ± 2 min.

Conclusions

An Atlas for automatic segmentation of lungs in COVID-19 patients was developed and validated. Combined with a previously developed method for lung densitometry characterization, it provides a fast, operator-independent way to extract relevant quantitative parameters with minimal manual intervention.

Poor Attendance for bone densitometry in patients at high risk of subsequent fragility fractures

Fracture Liaison Services (FLS) are considered the most effective model for the prevention of subsequent fractures however, the uptake of these services has shown to be suboptimal. 6,528 patients were identified and referred on for bone densitometry assessment over a 6 yr period, however, 21% of these patients did not attend, with a trend towards a higher re-fracture rate in those that did not attend compared to those that did. The presence of a fragility fracture increases the risk of further fractures. Fracture Liaison Services (FLS) are considered the most effective model for the prevention of subsequent fractures, although the uptake amongst patients invited for bone densitometry assessment has shown to be suboptimal. The UK has one of the most comprehensive numbers of FLS, however the proportion and characteristics of patients identified through the FLS that do not respond to bone densitometry invitation, in the UK, remains unclear. We report the 6 yr. findings from the Nottingham FLS. The Nottingham Fracture Liaison Service (N-FLS) systematically identifies those adults aged 50 yr. and older with fragility fractures presenting to the fracture clinic and where appropriate, arranges referral for bone densitometry assessment. Routine clinical data is collected onto the N-FLS database. Patient characteristics, between January 2012 and December 2017, were examined of those referred for bone densitometry examination, comparing those that attended to those that did not attend (DNA). Deprivation scores for each patient were calculated using the English indices of deprivation 2015 (1-Most deprived; 5- Least deprived). Follow up data was available for those attending from 2016 onwards, which allowed an assessment of re-fracture. Over the 6 yr period, 6,528 patients as identified by the N-FLS were referred on for bone densitometry assessment. 1,386 patients (21%) did not attend (DNA) for bone densitometry assessment. The proportion was similar for each of the years. High prevalence of non-attendance was in females [1032 patients (74%)] and the most deprived individuals [398 patients (29%), which were significant when compared to those that did attend, p=0.042]. 826 patients were referred in 2016. Median follow-up time was 2.46 yr. (IQR 0.16-3.00 yr.). 52 (7%) patients, in this group, sustained a subsequent fracture (35 patients in the group that did not attend for bone density assessment and 17 in those that attend, p=0.092). Nottingham FLS have identified patients with fragility fractures that are at high-risk of further fractures. Despite a dedicated FLS, 21% of those invited for bone densitometry assessment, did not attend for their appointment, over the 6 yr. period, similar proportion each year. There was a significantly higher proportion of those identified as 'most deprived' not attending for a bone densitometry, compared to those who attended. Sub-analysis in those aged 75 yr. and over, showed a high non-attendance in this group. Further qualitative studies are necessary to explore this patient group in detail, who remain at high risk of re-fracture.

Analysis of Corneal Scheimpflug Densitometry and Ocular Wavefront Aberrations Post Descemet Stripping Automated Endothelial Keratoplasty

PURPOSE

To assess the role of corneal densitometry and wavefront aberrations post Descemet stripping automated endothelial keratoplasty (DSAEK) and their correlation with visual acuity.

METHODS

Twenty-seven eyes of 25 patients with nonresolving corneal edema for more than 3 months as a result of Fuchs endothelial corneal dystrophy, pseudophakic bullous keratopathy, or secondary endothelial dysfunction were enrolled in a prospective interventional study and underwent DSAEK. Postoperative evaluation for corneal aberrations, including Higher order aberrations (HOAs) and corneal densitometry (CD), was performed using anterior-segment optical coherence tomography (Avanti RTvue XR; Optovue) and Scheimpflug imaging (Pentacam, Oculus Optikgeräte GmbH, Wetzlar, Germany) at 6 months. A correlation analysis of corneal aberrations, including HOAs and CD, with postoperative best-corrected visual acuity at 6 months was performed.

RESULTS

Mean best-corrected visual acuity (BCVA) improved from 1.67±0.53 log of minimum angle of resolution (logMAR) to 0.2±0.22 logMAR post DSAEK at 6 months (P≤0.0001). At 6 months, mean root-mean-square (RMS) total corneal aberrations (includes HOA and low-order aberration [LOA]), RMS total HOA, and RMS LOA of the central 6-mm zone were 4.99±2.64, 1.80±0.9, and 4.55±2.64, respectively. The mean corneal densitometry from anterior, central, and posterior zones were 39.12±12.77, 23.9±7.2, and 13.54±2.04 gray scale units, respectively. Total anterior aberrations (r=0.051; P=0.006), anterior LOA (r=0.049; P=0.009), total corneal aberrations (r=0.051; P=0.001), total HOAs (r=0.095; P=0.057) and LOAs (r=0.050; P=0.002), and total CD from 0 to 2 mm (r=0.010; P=0.038) and 2 to 6 mm (r=0.014; P=0.018) showed a significant inverse correlation with postoperative BCVA.

CONCLUSION

There was an inverse relationship between post DSAEK BCVA and total corneal HOAs and full-thickness densitometry at 6 months. Scheimpflug imaging with added tools for corneal aberration and densitometry analysis gives further insight into the suboptimal vision achieved despite transparent corneas post DSAEK.

Scheimpflug Corneal Densitometry Values and Severity of Guttae in Relation to Visual Acuity in Fuchs Endothelial Corneal Dystrophy

PURPOSE

The purpose of this study was to investigate the association between corneal densitometry (CD) values from Scheimpflug tomography imaging, severity of guttae, and visual acuity in eyes with Fuchs endothelial corneal dystrophy (FECD).

METHODS

This was a retrospective, cross-sectional study. Patients with FECD were examined at the Bascom Palmer Eye Institute from January 2015 to September 2019. We extracted CD values at central annuli of 0-2, 2-6, 6-10 and 10-12 mm from Scheimpflug tomography images. We investigated the association of corrected distance visual acuity (CDVA) with CD values, severity of guttae, central corneal thickness (CCT), cataract grade, refractive error, corneal edema grade, age, and gender using multivariate generalized estimating equation regression models.

RESULTS

One hundred ninety-two eyes from 110 patients were included in this study. Increase in central CD values at the 0 to 2 mm zone (P < 0.001), severity of guttae (P = 0.046), age (P < 0.001), cataract grade (P < 0.001), corneal edema grade (P < 0.001), and type of refractive error (P = 0.008) were significantly associated with decreased CDVA. Central corneal thickness, sex, and the peripheral CD values (2-6, 6-10, and 10-12 mm) were not significantly associated with CDVA (P > 0.05) in the final multivariate regression model.

CONCLUSIONS

Our study demonstrates that central CD values at 0 to 2 mm and severity of guttae are each associated with decreased CDVA in FECD. These findings carry implications for patients with FECD considering surgical intervention for phacoemulsification alone, Descemet stripping only, or endothelial cell transplantation and provide a multifactorial perspective on vision loss in FECD.

Optical bone densitometry robust to variation of soft tissue using machine learning techniques: validation by Monte Carlo simulation

SIGNIFICANCE

To achieve early detection of osteoporosis, a simple bone densitometry method using optics was proposed. However, individual differences in soft tissue structure and optical properties can cause errors in quantitative bone densitometry. Therefore, developing optical bone densitometry that is robust to soft tissue variations is important for the early detection of osteoporosis.

AIM

The purpose of this study was to develop an optical bone densitometer that is insensitive to soft tissue, using Monte Carlo simulation and machine learning techniques, and to verify its feasibility.

APPROACH

We propose a method to measure spatially resolved diffuse light from three directions of the biological tissue model and used machine learning techniques to predict bone density from these data. The three directions are backward, forward, and lateral to the direction of ballistic light irradiation. The method was validated using Monte Carlo simulations using synthetic biological tissue models with 1211 different random structural and optical properties.

RESULTS

The results were computed after a 10-fold cross-validation. From the simulated optical data, the machine learning model predicted bone density with a coefficient of determination of 0.760.

CONCLUSIONS

The optical bone densitometry method proposed in this study was found to be robust against individual differences in soft tissue.

Assessment of Corneal Densitometry in Big-Bubble Dissection Versus Manual Dissection Deep Anterior Lamellar Keratoplasty

PURPOSE

The aim of this study was to assess corneal densitometry and visual outcomes after big-bubble deep anterior lamellar keratoplasty (BB-DALK) and manual dissection deep anterior lamellar keratoplasty in patients with keratoconus.

METHODS

This retrospective comparative observational study included 40 keratoconic patients who underwent DALK surgery: 22 eyes had BB-DALK (group I) and 18 eyes had failed BB technique and DALK was completed by manual dissection (group II). Best -corrected visual acuity (BCVA), corneal topographic parameters, residual stromal tissue thickness, and endothelial cell count were recorded at 1, 3, 6, and 12 months postoperatively. Densitometric analysis of different corneal layers and zones was performed using Scheimpflug tomography at each visit; values were recorded and compared between the 2 groups.

RESULTS

At 1 and 6 months postoperatively, BCVA was better in group I than in group II, but with no statistically significant difference. At 12 months, the visual acuities became nearly similar in both groups (0.30 ± 0.13 vs. 0.30 ± 0.14 logarithm of the minimum angle of resolution, P = 0.888). Regarding corneal densitometric analysis, the recorded values for the posterior corneal layer were significantly higher in group II compared with group I at 3, 6, 9, and 12 months postoperatively in the 0- to 2-mm zone (P < 0.001) and the 2- to 6-mm zone (P = 0.029, 0.028, 0.001, and <0.001).

CONCLUSIONS

Manual dissection DALK after failed BB technique may affect the interface stromal reflectivity up to 12 months postoperatively. However, this does not significantly affect the visual acuity in comparison with successful BB-DALK.

Density Analysis of Enterovirus D68 Shows Viral Particles Can Associate with Exosomes

Enterovirus D68 (EV-D68) is an emerging pathogen which causes respiratory disease and is associated with an acute flaccid myelitis that predominately affects children. EV-D68 can infect motor neurons, causing cell death and a loss of motor control leading to flaccid paralysis. However, it remains unknown how viral particles gain entry into the central nervous system (CNS). Here, we show that three distinct densities of EV-D68 particle can be isolated from infected muscle and neural cell lines (RD and SH-SY5Y) using high-speed density centrifugation to separate cell supernatant. The lowest-density peak is composed of viral particles, which have adhered to the exterior surface of a small extracellular vesicle called an exosome. Analysis of prototypic (historic) and contemporary EV-D68 strains suggests that binding to exosomes is a ubiquitous characteristic of EV-D68. We further show that interaction with exosomes increases viral infectivity in a neural cell line. Analysis of the two higher-density peaks, which are not associated with exosomes, revealed that a significant amount of viral titer in the modern (2014) EV-D68 strains is found at 1.20 g/cm3, whereas this density has a very low viral titer in the prototypic Fermon strain. IMPORTANCE Despite the strong causal link between enterovirus D68 (EV-D68) and acute flaccid myelitis (AFM), it remains unclear how EV-D68 gains entry into the central nervous system and what receptors enable it to infect motor neurons. We show that EV-D68 particles can adhere to exosomes, placing EV-D68 among a handful of other picornaviruses which are known to interact with extracellular vesicles. Uptake and infection of permissive cells by virally contaminated exosomes would have major implications in the search for the EV-D68 receptor, as well as providing a possible route for viral entry into motor neurons. This work identifies a novel cellular entry route for EV-D68 and may facilitate the identification of genetic risk factors for development of AFM.

Quantitative investigation of the effect of surgically induced hypoparathyroidism on cataract development

INTRODUCTION

Although cataract formation is known in hypoparathyroidism, lens clarity and its correlation with clinical parameters have not been investigated quantitatively before in patients with hypoparathyroidism. The aim of this study was to compare the crystalline lens clarity of patients with surgically induced hypoparathyroidism and healthy subjects.

MATERIALS AND METHODS

Forty female patients with surgically induced hypoparathyroidism and 38 age-matched healthy female subjects were enrolled in this study. Scheimpflug corneal topography was performed to measure lens density (LD) and thickness (LT). Serum calcium, inorganic phosphorus, parathyroid hormone (PTH) levels, and disease duration were recorded.

RESULTS

No statistically significant difference was observed between the hypoparathyroidism and control groups in the Pentacam densitometry zones 1-2-3, LT, and average and maximum LD (p > 0.05 for all). Nine blue-dot-like, two cortical, and two posterior subcapsular cataracts were detected in the hypoparathyroidism group. The frequency of total and blue-dot-like cataracts was significantly higher in the hypoparathyroidism group than in the control group (p = 0.008 and p = 0.002, respectively). In the hypoparathyroidism group, a significant correlation was observed between the maximum LD and the hypoparathyroidism duration (ß = 0.420, p = 0.017), and the maximum LD and serum PTH level (ß = -0.332, p = 0.049).

CONCLUSION

The clarity of the crystalline lens may decrease in surgically induced hypoparathyroidism patients depending on the disease duration and PTH levels. Additionally, this study detected an increased frequency of blue-dot-like cataract in the patient group, which may be due to the effect of hypoparathyroidism.

Hippocampal Sclerosis in Pilocarpine Epilepsy: Survival of Peptide-Containing Neurons and Learning and Memory Disturbances in the Adult NMRI Strain Mouse

The present experiments reveal the alterations of the hippocampal neuronal populations in chronic epilepsy. The mice were injected with a single dose of pilocarpine. They had status epilepticus and spontaneously recurrent motor seizures. Three months after pilocarpine treatment, the animals were investigated with the Barnes maze to determine their learning and memory capabilities. Their hippocampi were analyzed 2 weeks later (at 3.5 months) with standard immunohistochemical methods and cell counting. Every animal displayed hippocampal sclerosis. The neuronal loss was evaluated with neuronal-N immunostaining, and the activation of the microglia was measured with Iba1 immunohistochemistry. The neuropeptide Y, parvalbumin, and calretinin immunoreactive structures were qualitatively and quantitatively analyzed in the hippocampal formation. The results were compared statistically to the results of the control mice. We detected neuronal loss and strongly activated microglia populations. Neuropeptide Y was significantly upregulated in the sprouting axons. The number of parvalbumin- and calretinin-containing interneurons decreased significantly in the Ammon’s horn and dentate gyrus. The epileptic animals displayed significantly worse learning and memory functions. We concluded that degeneration of the principal neurons, a numerical decrease of PV-containing GABAergic neurons, and strong peptidergic axonal sprouting were responsible for the loss of the hippocampal learning and memory functions.

Lens densitometry for assessment and prediction of cataract progression after pars plana vitrectomy with C3F8-gas for retinal detachment

Purpose

Lens opacification is a common complication after pars plana vitrectomy (PPV) and knowing its progression would facilitate consulting patients. The purpose of this study was to evaluate a quantitative model for lens-status-monitoring after PPV with C3F8 gas. Our model was evaluated in rhegmatogenous retinal detachment (RRD) patients of various age and lens densitometry (LD).

Methods

Data between March 2018 and March 2020 were evaluated retrospectively. LD measurements of the PentacamHR® Nucleus Staging mode (PNS) were used to quantify lens opacification over time. A mixed-effect regression model was designed, to enable LD predictions at any time postoperatively. Calculations were based on patient’s age and baseline LD as dependent variables. Six patients were randomly excluded during model development, to be used for testing its power afterwards.

Results

34 patients (male 19 [55.9%], female 15 [44.1%]) matched the inclusion criteria. Average age was 58.5 years (32–77;±4.3) and average follow-up was 7.2 months (3,4–23.1;±1,8). Mean baseline LD of the treated and fellow eye before surgery were 10.9% (8.7%-14.8%;±0.8) and 10.7% (8.5%-14.1%;±0.6), respectively. Using our prediction model, LD values for the six pre-selected patients closely match the observed data with an average deviation of 1.07%.

Conclusions

Evaluation of age and baseline LD using a mixed-effect regression model might predict cataract progression in RRD patients treated with PPV and C3F8-gas. Such a tool could be considered during cataract surgery consultation in these patients.

Evaluation of corneal densitometry changes in patients with lichen planus

PURPOSE

To investigate the corneal topography and densitometry changes in patients with lichen planus (LP).

METHODS

Anterior segment parameters and corneal densitometry of patients with LP and age- and gender-matched individuals with healthy eyes were evaluated using Scheimpflug corneal topography. A 12 mm corneal area was divided into 4 annular zones and 3 regions-in-depth anterior, central and posterior-for densitometry evaluation.

RESULTS

The study included 45 patients with LP and 50 individuals with healthy eyes. The two groups were similar in age and gender, and they showed no significant differences in anterior segment corneal topography parameters. Schirmer's I test results were significantly lower in the patients with LP than in the control group (P ˂ .001). The total corneal densitometry was higher in patients with LP than in the control group (P = .030). The anterior, central and posterior corneal densitometry in the 0-2 mm and 2-6 mm annular zones was higher in the LP group than in the control group. Correlation analysis between disease duration and corneal densitometry values showed a strong positive correlation in the anterior segment and a moderate positive correlation in the central and posterior segments (r = 0.632, P ˂ .001; r = 0.572, P ˂ .001; and r = 0.562, P ˂ .001, respectively).

CONCLUSIONS

Corneal densitometry values were higher in patients with LP than in individuals with healthy eyes, even if the patients had a clinically transparent cornea. More studies are needed to evaluate the changes that may occur in corneal transparency in patients with LP and other autoimmune dermatologic diseases that may affect the eye.

Evaluation of Corneal Densitometry and Endothelial Layer in Soft Contact Lens Users

SIGNIFICANCE

Soft contact lens wear may lead to physiological changes in the cornea. Corneal densitometry is a new software tool that may detect these physiological changes by monitoring their effects on corneal transparency.

PURPOSE

This study aimed to assess corneal densitometry values and corneal endothelium in patients using soft contact lenses.

METHODS

The study included 36 eyes of 36 subjects with soft contact lens use (group 1) and 36 eyes of 36 healthy control subjects (group 2). Anterior segment parameters and corneal densitometry of all subjects were evaluated using Scheimpflug corneal topography (Pentacam; Oculus Inc., Wetzlar, Germany). A total corneal area of 12 mm was divided into four annular zones (0 to 2, 2 to 6, 6 to 10, and 10 to 12 mm) and into three regions as anterior, central, and posterior for densitometry examination. Cell density, cell distribution, and cell morphology (quadrangular, pentagonal, hexagonal, and other cell percentages) of the endothelial layer were examined in both groups using specular microscopy (Nidek CEM 530; Nidek Co., Gamagori, Aichi, Japan).

RESULTS

In group 1, the mean duration of contact lens wear was 4.45 ± 2.15 years. The anterior segment parameters were not significantly different between the two groups (P > .05). The anterior 0- to 2- and 2- to 6-mm corneal densitometry values were significantly higher in group 1 compared with group 2 (23.2 ± 4.7 for group 1 and 17.3 ± 5.6 for group 2 [P = .03]; 22.4 ± 6.4 for group 1 and 17.8 ± 1.4 for group 2 [P = .03], respectively). There were no significant differences between the groups for corneal densitometry values between 6 and 12 mm, or for cell density, cell distribution, and cell morphology (P > .05).

CONCLUSIONS

Although the cornea remains transparent in soft contact lens wearers, corneal densitometry may increase in the 0- to 6-mm annular zone of the anterior region.

Microglia and Inhibitory Circuitry in the Medullary Dorsal Horn: Laminar and Time-Dependent Changes in a Trigeminal Model of Neuropathic Pain

Craniofacial neuropathic pain affects millions of people worldwide and is often difficult to treat. Two key mechanisms underlying this condition are a loss of the negative control exerted by inhibitory interneurons and an early microglial reaction. Basic features of these mechanisms, however, are still poorly understood. Using the chronic constriction injury of the infraorbital nerve (CCI-IoN) model of neuropathic pain in mice, we have examined the changes in the expression of GAD, the synthetic enzyme of GABA, and GlyT2, the membrane transporter of glycine, as well as the microgliosis that occur at early (5 days) and late (21 days) stages post-CCI in the medullary and upper spinal dorsal horn. Our results show that CCI-IoN induces a down-regulation of GAD at both postinjury survival times, uniformly across the superficial laminae. The expression of GlyT2 showed a more discrete and heterogeneous reduction due to the basal presence in lamina III of 'patches' of higher expression, interspersed within a less immunoreactive 'matrix', which showed a more substantial reduction in the expression of GlyT2. These patches coincided with foci lacking any perceptible microglial reaction, which stood out against a more diffuse area of strong microgliosis. These findings may provide clues to better understand the neural mechanisms underlying allodynia in neuropathic pain syndromes.

Bone densitometry categories as a salient distracting feature in the modern clinical pathways of osteoporosis care: A retrospective 20-year cohort study

BACKGROUND

It is unknown as to what factors typically drive osteoporosis therapy decisions in real-world practice.

METHODS

Retrospective, 20-year cohort study within the government health system of Manitoba including all women having bone densitometry (BMD) tests between 1996 and 2017. Osteoporosis prescription data was linked to registry data on fractures, clinical risk factors and BMD tests. We defined 6 possible treatment decisions by prescription data: no treatment, starting, stopping, continuing, drug hiatus and re-starting. For each decision, we tested the association between salient patient factors (age, glucocorticoid use, recent fracture, BMD hip or spine T-score ≤ -2.5, FRAX major osteoporotic fracture probability ≥20%) using multivariable logistic regression. The factors were rank-ordered by decreasing Wald χ² statistic to determine the relative importance.

RESULTS

There were 64,181 women, 33.8% of whom started osteoporosis therapy. For patients who begin therapy after a first BMD, the rank-ordered multivariable logistic regression factor most strongly associated was the T-score ≤ -2.5 [OR of 7.59(95%CI 7.19-8.01, p < 0.001)]. This was followed by glucocorticoid use [OR 2.89(95%CI 2.59-3.22, p < 0.001)]. Increasing age and recent fracture (within 2 years) were weak predictors of therapy and high FRAX score associated with reduced odds of therapy [OR 0.80 (95%CI 0.74-0.88, p < 0.001)]. T-scores were the strongest factor predicting therapy stop/continuation/re-starting; age and prior fracture had weak or no associations.

CONCLUSIONS

Despite recommendations for fracture-risk-based approach to osteoporosis therapy, BMD T-score continues to be the dominant factor in actual practice. Age, prior fracture or global fracture risk are much less associated; it is possible that BMD T-score categories are therefore acting as a clinically salient distracting factor.

Analysis of Corneal Densitometry and Endothelial Cell Function in Fuchs Uveitis Syndrome

OBJECTIVES

To evaluate corneal densitometry and endothelial cell properties in patients with unilateral Fuchs uveitis syndrome (FUS), and to compare results with unaffected contralateral eyes and healthy control subjects.

METHODS

A total of 90 participants were included in this prospective cross-sectional study. Forty-five affected eyes of patients with FUS were regarded as group 1 (FUSa), 45 fellow eyes were regarded as group 2 (FUSf), and 45 healthy-control eyes were regarded as group 3. Corneal densitometry was measured with densitometry software of Scheimpflug Corneal Topography (Pentacam HR, Oculus GmbH, Wetzlar, Germany), whereas endothelial cell measurement was evaluated with specular microscopy (Tomey, EM4000, GmbH, Germany).

RESULTS

The mean corneal densitometry values were higher in the midstromal (zones; 2-6, 6-10 mm), posterior (all zones), and total thickness (zones; 2-6, 6-10 mm) layers in the FUSa compared with FUSf and control eyes (P<0.05 for all comparisons). The mean values of average cell area and cell size characteristics (minimum, maximum, SD, and coefficient of variation) were higher; endothelial cell density and percentage of hexagonal cells were lower in the FUSa than in the other two groups (P<0.05 for all comparisons). There was a significantly strong correlation between specular microscopy parameters and posterior corneal densitometry values in the FUSa group.

CONCLUSIONS

Impairment of endothelial cell function in affected eyes of patients with FUS resulted in increased values of corneal densitometry, especially posterior layer.

Assessment of Corneal Haze After PRK and the Effect of Sutureless Amniotic Membrane Graft by Corneal Densitometry

PURPOSE

To assess whether densitometry analysis appropriately monitors the development of haze in myopic patients after photorefractive keratectomy (PRK) when compared to subjective slit-lamp haze grade examinations, and whether sutureless cryo-preserved amniotic membrane reduced postoperative haze development when compared to the standard bandage contact lens.

METHODS

In this retrospective cohort at the Center for Refractive Surgery, Walter Reed National Military Medical Center, a secondary analysis of prospectively collected data was performed. In the prospective study, participants underwent PRK for myopia. Postoperatively, a standard bandage contact lens was applied to the dominant eye and a sutureless cryo-preserved amniotic membrane graft to the nondominant eye. Participants were evaluated at 1, 3, and 6 months postoperatively for haze formation and corneal densitometry using slit-lamp biomicroscopy and Scheimpflug imaging, respectively.

RESULTS

Densitometry measurements at 6 months postoperatively were positively and significantly associated with the presence or absence of haze as assessed by slit-lamp examination in 39 patients (78 eyes; age range: 21 to 44 years). Eyes with increased densitometry measurements had 2.3 to 3.4 times the odds (P ⩽ .014) of having clinical haze on slit-lamp examination. Eyes with the amniotic membrane graft showed a positive correlation with increased corneal densitometry throughout most layers of the cornea.

CONCLUSIONS

Densitometry analysis appears to be a useful tool to supplement slit-lamp examination in monitoring haze development after PRK. The amniotic membrane failed to show a reduction in corneal densitometry in myopic eyes after PRK. [J Refract Surg. 2020;36(5):293-299.].

Come Back Skinfolds, All Is Forgiven: A Narrative Review of the Efficacy of Common Body Composition Methods in Applied Sports Practice

Whilst the assessment of body composition is routine practice in sport, there remains considerable debate on the best tools available, with the chosen technique often based upon convenience rather than understanding the method and its limitations. The aim of this manuscript was threefold: (1) provide an overview of the common methodologies used within sport to measure body composition, specifically hydro-densitometry, air displacement plethysmography, bioelectrical impedance analysis and spectroscopy, ultra-sound, three-dimensional scanning, dual-energy X-ray absorptiometry (DXA) and skinfold thickness; (2) compare the efficacy of what are widely believed to be the most accurate (DXA) and practical (skinfold thickness) assessment tools and (3) provide a framework to help select the most appropriate assessment in applied sports practice including insights from the authors' experiences working in elite sport. Traditionally, skinfold thickness has been the most popular method of body composition but the use of DXA has increased in recent years, with a wide held belief that it is the criterion standard. When bone mineral content needs to be assessed, and/or when it is necessary to take limb-specific estimations of fat and fat-free mass, then DXA appears to be the preferred method, although it is crucial to be aware of the logistical constraints required to produce reliable data, including controlling food intake, prior exercise and hydration status. However, given the need for simplicity and after considering the evidence across all assessment methods, skinfolds appear to be the least affected by day-to-day variability, leading to the conclusion 'come back skinfolds, all is forgiven'.

Skeletal pathology and bone mineral density changes in wild muskrats (Ondatra zibethicus) and red squirrels (Tamiasciurus hudsonicus) inhabiting arsenic polluted areas of Yellowknife, Northwest Territories (Canada): A radiographic densitometry study

The City of Yellowknife is a known hotspot of arsenic contamination and there is a growing body of evidence suggesting that local wildlife in the vicinity of the abandoned Giant Mine site may be at risk of decreased bone mineralization and various bone disorders. The purpose of this study was to preliminarily measure bone mineral density (BMD) changes and investigate the incidence, pattern, and severity of bone lesions in wild muskrats and red squirrels breeding in three (3) catchment areas at different distances from the Giant Mine Site in Yellowknife, Northwest Territories (Canada): ~2 km (location 1), ~18 km (location 2), and ~40-100 km (location 3). Full femoral bones of 15 muskrats and 15 red squirrels were collected from the three sampling locations (5 from each location) and subjected to radiographic analysis and densitometric measurements. The patterns and severities of bone lesions, including changes in bone mineral density, were evaluated and compared between groups. As levels were significantly higher in the bones of muskrats caught from location 1 and 2, relative to location 3. Further, As and Cd levels were significantly higher in the bones of squirrels caught from locations 1 and 2 relative to squirrels caught from location 3. The preliminary results from bones revealed that radiographic abnormalities such as bone rarefaction, osteopenia, and thinning of the femoral shafts with significant ossific cystic lesions and bowing were the most common skeletal pathologies found in bones of red squirrels from the three locations. Radiographic appearances of massive sclerosis and dysplasia, including severe osteocondensation and osteopathia striata-like abnormalities, were found in the bones of muskrats from all the sampling locations. Densitometric evaluation showed no significant differences between the three locations in the bone parameters measured. However, there was a statistically significant correlation between As content in the bones of muskrats and percent fat content in the femur samples, which suggests that accumulation of As could have been a causal factor for a change in percent fat in femurs of muskrats.

A new analysis method for evaluating bacterial growth with microplate readers

Growth curve measurements are commonly used in microbiology, while the use of microplate readers for such measurements provides better temporal resolution and higher throughput. However, evaluating bacterial growth with microplate readers has been hurdled by barriers such as multiple scattering. Here, we report our development of a method based on the time derivatives of the optical density (OD) and/or fluorescence (FL) of bacterial cultures to overcome these barriers. First, we illustrated our method using quantitative models and numerical simulations, which predicted the number of bacteria and the number of fluorescent proteins in time as well as their time derivatives. Then, we systematically investigated how the time derivatives depend on the parameters in the models/simulations, providing a framework for understanding the FL growth curves. In addition, as a demonstration, we applied our method to study the lag time elongation of bacteria subjected to treatment with silver (Ag⁺) ions and found that the results from our method corroborated well with that from growth curve fitting by the Gompertz model that has been commonly used in the literature. Furthermore, this method was applied to the growth of bacteria in the presence of silver nanoparticles (AgNPs) at various concentrations, where the OD curve measurements failed. We showed that our method allowed us to successfully extract the growth behavior of the bacteria from the FL measurements and understand how the growth was affected by the AgNPs.

In situ, high-resolution measurement of labile phosphate in sediment porewater using the DET technique coupled with optimized imaging densitometry

Obtaining two-dimensional distributions of reactive phosphorus in sediment porewater is very important for understanding fine-scale phosphorus mobilization and sequestration processes in sediments. In this study, the diffusive equilibrium in thin films (DET) measurement based on computer imaging densitometry (CID) was studied in detail with optimal conditions described. This study focuses on evaluating the two-dimensional colorimetric DET method coupled with CID (DET-CID method) for porewater labile phosphate measurements. The result shows that the red channel filter is the optimum channel for sensitivity to process the image. Additionally, staining time and temperature have great influence on the method, and 20 min staining time and ≥25 °C staining temperature were recommended. The minimum detection limit of labile phosphate of this method was 0.300 mg P/L, and the maximum detection limit could reach 50.00 mg P/L. The DET-CID technique can be used to measure labile phosphate in a wide range of acidic and alkaline water bodies (pH = 2-10 and water hardness from 0 to 2000 mg/L as CaCO₃). The linear regression analysis shows that this technique presents very similar results compared with other two existing methods (R² = 0.999). Our results would give insights into the precisely measurements of labile phosphate in field applications.

Measurements of scleral thickness and corneal optic densitometry in patients with systemic lupus erythematosus

BACKGROUND

This study aimed to evaluate the scleral thickness and corneal parameters of patients with systemic lupus erythematosus (SLE).

METHODS

Forty-seven eyes of 47 SLE patients and 44 eyes of healthy controls were included in this cross-sectional study. Anterior segment optical coherence tomography (AS-OCT) was used to measure the corneal and scleral thickness. Scleral thickness (ST) was measured based upon the segmentation at 1000 to 5000 μm from the scleral spur. Pentacam HR was used to measure corneal parameters.

RESULTS

There was no statistically significant difference between SLE group and control group according to age and sex (P > .05). The ST measurements at all distances from scleral spur were found to be thicker in patients with SLE (P < .05). Central corneal thickness (CCT), cornea volume (CV), corneal densitometry (CD), and peripheral corneal thickness (PCT) measurements were similar between the groups (P > .05).

CONCLUSION

ST was thicker in SLE patients compared with healthy controls. AS-OCT seems helpful in selecting optimal sites for pharmaceutical or surgical intervention in SLE patients, since it shows thickness variations in anterior sclera.

Relationship of CT densitometry to lung physiological parameters and health status in alpha-1 antitrypsin deficiency: initial report of a centralised database of the NIHR rare diseases translational research collaborative

OBJECTIVES

To establish a database network for the study of alpha-1 antitrypsin deficiency (AATD) and compare the results to CT lung density as the most direct measure of emphysema.

DESIGN

A central electronic database was established to permit the upload of anonymised patient data from remote sites. Prospectively collected CT data were recorded onto disc, anonymised, analysed at the coordinating centre and compared with the clinical features of the disease.

SETTING

Tertiary referral centres with expertise in the management of AATD focused on academic Biomedical Research Units and Wellcome Clinical Research Facilities.

PARTICIPANTS

Data were collected from 187 patients over 1 year from eight UK academic sites. This included patient demographics, postbronchodilator physiology, health status and CT. Analysis was undertaken at the coordinating centre in Birmingham.

RESULTS

Patient recruitment in the 12 months reached 94% of target (set at 200) covering the whole spectrum of the disease from those with normal lung function to very severe chronic obstructive lung disease. CT scan suitable for analysis was available from 147 (79%) of the patients. CT density, analysed as the threshold for the lowest 15% of lung voxels, showed statistically significant relationships with the objective physiological parameters of lung function as determined by spirometric Global Initiative for Chronic Obstructive Lung Disease (GOLD) severity staging (p<0.001) and carbon monoxide gas transfer (p<0.01). Density also correlated with subjective measures of quality of life (p=0.02).

CONCLUSIONS

Establishment of the network for data collection and its transfer was highly successful facilitating future collaboration for the study of this rare disease and its management. CT densitometry correlated well with the objective clinical features of the disease supporting its role as the specific marker of the associated emphysema and its severity. Correlations with subjective measures of health, however, were generally weak indicating other factors play a role.

Oxone®-Mediated TEMPO-Oxidized Cellulose Nanomaterials form I and form II

The 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) oxidation of cellulose, when mediated with Oxone^® (KHSO₅), can be performed simply and under mild conditions. Furthermore, the products of the reaction can be isolated into two major components: Oxone^®-mediated TEMPO-oxidized cellulose nanomaterials Form I and Form II (OTO-CNM Form I and Form II). This study focuses on the characterization of the properties of OTO-CNMs. Nanoparticle-sized cellulose fibers of 5 and 16 nm, respectively, were confirmed through electron microscopy. Infrared spectroscopy showed that the most carboxylation presented in Form II. Conductometric titration showed a two-fold increase in carboxylation from Form I (800 mmol/kg) to Form II (1600 mmol/kg). OTO-CNMs showed cellulose crystallinity in the range of 64–68% and crystallite sizes of 1.4–3.3 nm, as shown through XRD. OTO-CNMs show controlled variability in hydrophilicity with contact angles ranging from 16 to 32°, within or below the 26–47° reported in the literature for TEMPO-oxidized CNMs. Newly discovered OTO-CNM Form II shows enhanced hydrophilic properties as well as unique crystallinity and chemical functionalization in the field of bio-sourced material and nanocomposites.

proMAD: semiquantitative densitometric measurement of protein microarrays

BACKGROUND

Protein microarrays are a versatile and widely used tool for analyzing complex protein mixtures. Membrane arrays utilize antibodies which are captured on a membrane to specifically immobilize several proteins of interest at once. Using detection antibodies, the bound protein-antibody-complex is converted into visual signals, which can be quantified using densitometry. The reliability of such densitometric assessments depends on a variety of factors, not only sample preparation and the choice of acquisition device but also the selected analysis software and the algorithms used for readout and processing data. Currently available software packages use a single image of a membrane at an optimal exposure time selected for that specific experimental framework. This selection is based on a user's best guess and is subject to inter-user variability or the acquisition device algorithm. With modern image acquisition systems proving the capacity to collect signal development over time, this information can be used to improve densitometric measurements. Here we introduce proMAD, a toolkit for protein microarray analysis providing a novel systemic approach for the quantification of membrane arrays based on the kinetics of the analytical reaction.

RESULTS

Briefly, our toolkit ensures an exact membrane alignment, utilizing basic computer vision techniques. It also provides a stable method to estimate the background light level. Finally, we model the light production over time, utilizing the knowledge about the reaction kinetics of the underlying horseradish peroxidase-based signal detection method.

CONCLUSION

proMAD incorporates the reaction kinetics of the enzyme to model the signal development over time for each membrane creating an individual, self-referencing concept. Variations of membranes within a given experimental set up can be accounted for, allowing for a better comparison of such. While the open-source library can be implemented in existing workflows and used for highly user-tailored analytic setups, the web application, on the other hand, provides easy platform-independent access to the core algorithm to a wide range of researchers. proMAD's inherent flexibility has the potential to cover a wide range of use-cases and enables the automation of data analytic tasks.

[Forecast of the metrological characteristics of the method of the quantitative determination of verapamil in blood in forensic chemical analysis]

The aim of the work is to test theoretical prognosis of metrological characteristics of methods of quantitative determination in forensic chemical analysis on the example of method of determination of verapamil content in blood by thin layer chromatography with computer densitometry. The algorithm of prognostic determination of relative error for methods of quantitative analysis in forensic chemical examination using computer program «ChemMetrEvaluation 1.0» is offered. The implementation of the algorithm is based on a detailed analysis of error estimation of measurements at the stages of sample preparation, measuring the value of the analytical signal.

Assessment of Risk Factors for Fractures in Patients with Type 2 Diabetes over 60 Years Old: A Cross-Sectional Study from Northeast China

AIMS

Previous evidence has demonstrated an increased fracture risk among the population with type 2 diabetes mellitus (T2DM). This study investigated the prevalence of bone fractures in elderly subjects (with and without type 2 diabetes) and identified any fracture risk factors, especially the risk factors for common known fractures in particular diabetic populations.

METHODS

This cross-sectional study was conducted with community-dwelling people over 60 years old in nine communities from the city of Shenyang, which is the capital of Northeast China's Liaoning Province. A total of 3430 elderly adults (2201 females, mean ± standard deviation age 68.16 ± 6.1 years; 1229 males, 69.16 ± 6.7 years) were included. Our study measured the heel bone mineral density (BMD) and used the timed "up and go" (TUG) test and other indicators. In addition, we performed logistic regression analysis to explore the risk factors for fractures in the general population and the diabetic population and to analyze the differences.

RESULTS

The results revealed that a total of 201 elderly persons (5.8%), with an average age of 70.05 ± 6.54 years, suffered from a history of fragility fractures, which affected more females (74.6%) than males (p = 0.001). The prevalence of fractures in the T2DM population was 7.3%, which was much higher than the 5.2% in non-T2DM population (p = 0.001). The prevalence of fractures in the T2DM population was 7.3%, which was much higher than the 5.2% in non-T2DM population (p = 0.001). The prevalence of fractures in the T2DM population was 7.3%, which was much higher than the 5.2% in non-T2DM population (p = 0.001). The prevalence of fractures in the T2DM population was 7.3%, which was much higher than the 5.2% in non-T2DM population (T-score≤-2.5 (OR 1.750) were independent risk factors for fragility fractures in the non-T2DM population, but they were not risk factors in the T2DM population.

CONCLUSIONS

This study found that low BMD and slow TUG time were independent risk factors for fractures in non-T2DM patients, while no associations were found in the T2DM population. Patients with T2DM have a higher risk for fractures even when they have sufficient BMD and a short TUG time. TUG and BMD underestimated the risk for fractures in the T2DM population.

[Research of the structure of the mineral component of tooth enamel in connective tissue dysplasia by densitometry and atomic force microscopy in the early postpartum ontogenesis period]

OBJECTIVE

To give a quantitative and qualitative characteristic of the structure of the enamel's mineral component structure of impacted teeth with or without connective tissue dysplasia in different periods of early postnatal human ontogenesis using densitometry and atomic force microscopy.

MATERIALS AND METHODS

The study involved 120 males with and without connective tissue dysplasia (CTD), which were divided into 3 equal subgroups (60 people with CTD and 60 people without CTD), 20 people in each, according to age: 15-20, 21-30, 31-40 years old. Each of the examined was removed either 3.8 or 4.8 tooth. To study the inorganic component of tooth enamel, a densitometric assessment of enamel's optical density was carried out using computed tomography in the Kodak Dental Systems software (Trophy 2000) and preparation of thin sections of tooth samples 3.8 or 4.8 for atomic force microscopy (AFM) according to the methods of Omsk State Medical University.

RESULTS

The structure of tooth enamel in connective tissue dysplasia in the early postpartum period of ontogenesis is characterized by pronounced polymorphisms and an insufficient level of maturity. The ordering and orientation of the enamel prisms are disturbed due to insufficient packing density and a large distance between the enamel prisms at the age of 15-20, 21-30. The established changes indicate the incomplete nature of amelogenesis with connective tissue dysplasia at the indicated ages.

CONCLUSIONS

In case of connective tissue dysplasia in the early postnatal period of ontogenesis, an incomplete amelogenesis is observed. This process is manifested by lower values of the mineral component's optical density, low packing of enamel prisms, a large distance between enamel prisms and their irregular shape.

Single Cell Densitometry and Weightlessness Culture of Mesenchymal Stem Cells Using Magnetic Levitation

Magnetic levitation methodology enables density-based separation of microparticles/cells and sustains cell culture in different media. Levitation process can be accomplished via negative magnetophoresis (diamagnetophoresis), where the applied magnetic force compensates gravitational acceleration and the density of the diamagnetic object (e.g., cell) determines its levitation height. Here we describe a portable, sensitive, and cost-effective technology that uses the principles of magnetic levitation to measure single cell density and cell culture under desired conditions.

Palm Fruit Bioactives augment expression of Tyrosine Hydroxylase in the Nile Grass Rat basal ganglia and alter the colonic microbiome

Tyrosine hydroxylase (TH) catalyzes the hydroxylation of L-tyrosine to L-DOPA. This is the rate-limiting step in the biosynthesis of the catecholamines - dopamine (DA), norepinephrine (NE), and epinephrine (EP). Catecholamines (CA) play a key role as neurotransmitters and hormones. Aberrant levels of CA are associated with multiple medical conditions, including Parkinson's disease. Palm Fruit Bioactives (PFB) significantly increased the levels of tyrosine hydroxylase in the brain of the Nile Grass rat (NGR), a novel and potentially significant finding, unique to PFB among known botanical sources. Increases were most pronounced in the basal ganglia, including the caudate-putamen, striatum and substantia nigra. The NGR represents an animal model of diet-induced Type 2 Diabetes Mellitus (T2DM), exhibiting hyperglycemia, hyperinsulinemia, and insulin resistance associated with hyperphagia and accelerated postweaning weight gain induced by a high-carbohydrate diet (hiCHO). The PFB-induced increase of TH in the basal ganglia of the NGR was documented by immuno-histochemical staining (IHC). This increase in TH occurred equally in both diabetes-susceptible and diabetes-resistant NGR fed a hiCHO. PFB also stimulated growth of the colon microbiota evidenced by an increase in cecal weight and altered microbiome.  The metabolites of colon microbiota, e.g. short-chain fatty acids, may influence the brain and behavior significantly.

A novel algorithm to predict bone changes in the mouse tibia properties under physiological conditions

Understanding how bone adapts to mechanical stimuli is fundamental for optimising treatments against musculoskeletal diseases in preclinical studies, but the contribution of physiological loading to bone adaptation in mouse tibia has not been quantified so far. In this study, a novel mechanistic model to predict bone adaptation based on physiological loading was developed and its outputs were compared with longitudinal scans of the mouse tibia. Bone remodelling was driven by the mechanical stimuli estimated from micro-FEA models constructed from micro-CT scans of C57BL/6 female mice (N = 5) from weeks 14 and 20 of age, to predict bone changes in week 16 or 22. Parametric analysis was conducted to evaluate the sensitivity of the models to subject-specific or averaged parameters, parameters from week 14 or week 20, and to strain energy density (SED) or maximum principal strain (ε_maxprinc). The results at week 20 showed no significant difference in bone densitometric properties between experimental and predicted images across the tibia for both stimuli, and 59% and 47% of the predicted voxels matched with the experimental sites in apposition and resorption, respectively. The model was able to reproduce regions of bone apposition in both periosteal and endosteal surfaces (70% and 40% for SED and ε_maxprinc, respectively), but it under-predicted the experimental sites of resorption by over 85%. This study shows for the first time the potential of a subject-specific mechanoregulation algorithm to predict bone changes in a mouse model under physiological loading. Nevertheless, the weak predictions of resorption suggest that a combined stimulus or biological stimuli should be accounted for in the model.

Advanced X-ray CT scanning can boost tree ring research for earth system sciences

BACKGROUND AND AIMS

Tree rings, as archives of the past and biosensors of the present, offer unique opportunities to study influences of the fluctuating environment over decades to centuries. As such, tree-ring-based wood traits are capital input for global vegetation models. To contribute to earth system sciences, however, sufficient spatial coverage is required of detailed individual-based measurements, necessitating large amounts of data. X-ray computed tomography (CT) scanning is one of the few techniques that can deliver such data sets.

METHODS

Increment cores of four different temperate tree species were scanned with a state-of-the-art X-ray CT system at resolutions ranging from 60 μm down to 4.5 μm, with an additional scan at a resolution of 0.8 μm of a splinter-sized sample using a second X-ray CT system to highlight the potential of cell-level scanning. Calibration-free densitometry, based on full scanner simulation of a third X-ray CT system, is illustrated on increment cores of a tropical tree species.

KEY RESULTS

We show how multiscale scanning offers unprecedented potential for mapping tree rings and wood traits without sample manipulation and with limited operator intervention. Custom-designed sample holders enable simultaneous scanning of multiple increment cores at resolutions sufficient for tree ring analysis and densitometry as well as single core scanning enabling quantitative wood anatomy, thereby approaching the conventional thin section approach. Standardized X-ray CT volumes are, furthermore, ideal input imagery for automated pipelines with neural-based learning for tree ring detection and measurements of wood traits.

CONCLUSIONS

Advanced X-ray CT scanning for high-throughput processing of increment cores is within reach, generating pith-to-bark ring width series, density profiles and wood trait data. This would allow contribution to large-scale monitoring and modelling efforts with sufficient global coverage.

Histochemical quantification of collagen content in articular cartilage

Background

Articular cartilage (AC) is mainly composed of water, type II collagen, proteoglycans (PGs) and chondrocytes. The amount of PGs in AC is routinely quantified with digital densitometry (DD) from Safranin O-stained sections, but it is unclear whether similar method could be used for collagens.

Objective

The aim of this study was to clarify whether collagens can be quantified from histological AC sections using DD.

Material and methods

Sixteen human AC samples were stained with Masson’s trichrome or Picrosirius red. Optical densities of histological stains were compared to two commonly used collagen parameters (amide I and collagen CH₂ side chain peak at 1338cm^-1) measured using Fourier Transform Infrared (FTIR) spectroscopic imaging.

Results

Optical density of Modified Masson’s trichrome staining, which included enzymatic removal of PGs before staining, correlated significantly with FTIR-derived collagen parameters at almost all depths of cartilage. The other studied staining protocols displayed significant correlations with the reference parameters at only few depth layers.

Conclusions

Based on our findings, modified Masson’s trichrome staining protocol is suitable for quantification of AC collagen content. Enzymatic removal of PGs prior to staining is critical as us allows better staining of the collagen. Further optimization of staining protocols may improve the results in the future studies.

[INFORMATIVITY OF COMPUTER DENSITOMETRY FOR ASSESSING THE DEGREE OF ACTIVITY OF THE INFLAMMATORY PROCESS IN PULMONARY TUBERCULOMAS]

In order to establish the levels of densitometric indicators of CT of the chest for various degrees of activity of a specific inflammatory process, the histopathological findings of the resected material were analyzed in 65 patients aged 24 to 60 years, 39 of them men, 25 women operated on pulmonary tuberculosis with a measurement of their densitometric indicators on CT of the chest. It is proved that computer densitometry is an objective non-invasive research method that allows you to establish with high confidence the degree of activity of a specific inflammatory process. The study of the average, minimum and maximum values of the density indicator on a fixed area of the axial section of the CT scan actually reflects the histological structure of the focus and allows you to identify areas with high activity of a specific inflammatory process.