1.Evaluation of low-dose dual energy computed tomography for in vivo assessment of renal/ureteric calculus composition.
Harshavardhan MAHALINGAM ; Anupam LAL ; Arup K MANDAL ; Shrawan Kumar SINGH ; Shalmoli BHATTACHARYYA ; Niranjan KHANDELWAL
Korean Journal of Urology 2015;56(8):587-593
PURPOSE: This study aimed to assess the accuracy of low-dose dual-energy computed tomography (DECT) in predicting the composition of urinary calculi. MATERIALS AND METHODS: A total of 52 patients with urinary calculi were scanned with a 128-slice dual-source DECT scanner by use of a low-dose protocol. Dual-energy (DE) ratio, weighted average Hounsfield unit (HU) of calculi, radiation dose, and image noise levels were recorded. Two radiologists independently rated study quality. Stone composition was assessed after extraction by Fourier transform infrared spectroscopy (FTIRS). Analysis of variance was used to determine if the differences in HU values and DE ratios between the various calculus groups were significant. Threshold cutoff values to classify the calculi into separate groups were identified by receiver operating characteristic curve analysis. RESULTS: A total of 137 calculi were detected. FTIRS analysis differentiated the calculi into five groups: uric acid (n=17), struvite (n=3), calcium oxalate monohydrate and dihydrate (COM-COD, n=84), calcium oxalate monohydrate (COM, n=28), and carbonate apatite (n=5). The HU value could differentiate only uric acid calculi from calcified calculi (p<0.001). The DE ratio could confidently differentiate uric acid, struvite, calcium oxalate, and carbonate apatite calculi (p<0.001) with cutoff values of 1.12, 1.34, and 1.66, respectively, giving >80% sensitivity and specificity to differentiate them. The DE ratio could not differentiate COM from COM-COD calculi. No study was rated poor in quality by either of the observers. The mean radiation dose was 1.8 mSv. CONCLUSIONS: Low-dose DECT accurately predicts urinary calculus composition in vivo while simultaneously reducing radiation exposure without compromising study quality.
Adult
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Apatites/analysis
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Calcium Oxalate/analysis
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Female
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Humans
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Image Interpretation, Computer-Assisted/methods
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Kidney Calculi/chemistry/pathology/*radiography
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Magnesium Compounds/analysis
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Male
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Middle Aged
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Phosphates/analysis
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Prospective Studies
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Radiation Dosage
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Tomography, X-Ray Computed/methods
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Ureteral Calculi/chemistry/pathology/*radiography
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Uric Acid/analysis
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Waist Circumference
;
Young Adult
2.Temporal Modulation of DNA Methylation and Gene Expression in Monolayer and 3D Spheroids of Dental Pulp Stem Cells during Osteogenic Differentiation: A Comparative Study
Shalini RAIK ; Reetu THAKUR ; Vidya RATTAN ; Navin KUMAR ; Arnab PAL ; Shalmoli BHATTACHARYYA
Tissue Engineering and Regenerative Medicine 2022;19(6):1267-1282
BACKGROUND:
Human mesenchymal stem cells are being used for various regenerative applications in past decades.This study chronicled a temporal profile of the transcriptional pattern and promoter methylation status of the osteogenic related gene in dental pulp stem cells (DPSCs) derived from 3-dimensional spheroid culture (3D) vis a vis 2-dimensional (2D) monolayer culture upon osteogenic induction.
METHODS:
Biomimetic properties of osteogenesis were determined by alkaline phosphatase assay and alizarin red staining. Gene expression and promoter methylation status of osteogenic genes such as runt-related transcription factor-2, collagen1α1, osteocalcin (OCN), and DLX5 (distal-homeobox) were performed by qPCR assay and bisulfite sequencing, respectively. Furthermore, μ-Computed tomography (micro-CT) was performed to examine the new bone formation in critical-sized rat calvarial bone defect model.
RESULTS:
Our results indicated a greater inclination of spheroid culture-derived DPSCs toward osteogenic lineage than the monolayer culture. The bisulfite sequencing of the promoter region of osteogenic genes revealed sustenance of low methylation levels in DPSCs during the progression of osteogenic differentiation. However, the significant difference in the methylation pattern between 2D and 3D derived DPSCs were identified only for OCN gene promoter. We observed differences in the mRNA expression pattern of epigenetic writers such as DNA methyltransferases (DNMTs) and methylcytosine dioxygenases (TET) between the two culture conditions. Further, the DPSC spheroids showed enhanced new bone formation ability in an animal model of bone defect compared to the cells cultivated in a 2D platform which further substantiated our in-vitro observations.
CONCLUSION
The distinct cellular microenvironment induced changes in DNA methylation pattern and expression of epigenetic regulators such as DNMTs and TETs genes may lead to increase expression of osteogenic markers in 3D spheroid culture of DPSCs which make DPSCs spheroids suitable for osteogenic regeneration compared to monolayers.