Technical factors in fractal analysis of periapical radiographs

OBJECTIVES: Fractal analysis quantifies complex geometric structures by generating a fractal dimension, which can measure trabecular bone density. The use of non-standardized radiographic techniques potentially limits the reliability of fractal analysis. The objective of this study was to determine how variations in radiographic technique affect fractal dimension. METHODS: Periapical radiographs of maxillary incisors taken on eight dry human skulls at varying angulation, tube potential and impulse settings were subjected to Fourier transform fractal analysis. RESULTS: A significant (p < 0.05) difference in fractal dimension, ranging from 2.5 to 2.9, was found between the skulls, potentially reflecting variations in bone trabeculation. However, variations in angulation, tube potential or impulse did not have a statistically significant effect (p > 0.05) on fractal dimension, with the standard deviation of the fractal dimension ranging from +/- 0.005 to +/- 0.062 at various radiographic machine settings. CONCLUSIONS: This study indicates that non-standardized periapical radiographs may provide a reliable method for determining fractal dimensions, which could be useful in analysing changes in alveolar bone density in various bone disorders.     

Preparation and bioevaluation of a Tc-labeled chlorambucil analog as a tumor targeting agent

Chlorambucil belongs to a group of nitrogen mustards which are used for the treatment of variety of cancers. Hence, a chlorambucil derivative has been radiolabeled with [^99mTc(CO)₃(H₂O)₃]⁺ core and its efficacy as a tumor targeting agent has been evaluated. Radiochemical yield of the complex was >98% as observed by HPLC. The in vitro studies in MCF-7 breast cancer cells showed about 30% inhibition of the radiolabeled complex in presence of the cold chlorambucil derivative. Biodistribution studies in Swiss mice bearing fibrosarcoma tumor showed an uptake of 3.2±0.3% ID/g at 3 h.p.i.     

Assessment of intervertebral disc degeneration with magnetic resonance single‐voxel spectroscopy

This study examined the feasibility of using short‐echo water‐suppressed point‐resolved spectroscopy (PRESS) on a clinical 3T magnetic resonance (MR) scanner for evaluating biochemical changes in degenerated bovine and cadaveric human intervertebral discs. In bovine discs (N = 17), degeneration was induced with papain injections. Degeneration of human cadaveric discs (N = 27) was assessed using the Pfirrmann grading on T₂‐weighted images. Chemicals in the carbohydrate region (Carb), the choline head group (Cho), the N‐acetyl region (N‐acetyl), and the lipid and lactate region (Lac+Lip) were quantified using ¹H PRESS, and were compared between specimens with different degrees of degeneration. The correlation between the spectroscopic findings and glycosaminoglycan (GAG) quantification using biochemical assays was determined. Significant differences were found between the ratios (N‐acetyl/Cho, N‐acetyl/Lac+Lip) acquired before and after papain injection in bovine discs. For human cadaveric discs, significant differences in the ratios (N‐acetyl/Carb, N‐acetyl/Lac+Lip) were found between discs having high and low Pfirrmann scores. Significant correlations were found between N‐acetyl/Lac+Lip and GAG content in bovine discs (R = 0.77, P = 0.0007) and cadaveric discs (R = 0.83, P < 0.0001). Significant correlation between N‐acetyl/Cho and GAG content was also found in cadaver discs (R = 0.64, P = 0.0039). This study demonstrates for the first time that short‐echo PRESS on a clinical 3T MR scanner can be used to noninvasively and can reproducibly quantify metabolic changes associated with degeneration of intervertebral discs. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.     

Apoptosis induction by Maackia amurensis agglutinin in childhood acute lymphoblastic leukemic cells

Malignant transformation is known to be associated with changes in cell surface carbohydrate-architecture, which can be detected by lectins. In the present study, Maackia amurensis agglutinin (MAA), specific for NeuNAcalpha(2-->3)Gal/GalNAc showed strong binding with lymphoblasts of children having acute lymphoblastic leukemia (ALL) as compared to cells from children with non-hematological disorders ("Controls"). MAA recognized a 66 kDa sialoglycoprotein present in membrane fraction of ALL cells. Moreover, MAA induced apoptosis in ALL cells was found to be reduced significantly in presence of GM2/IgG(MAA). Thus, MAA has a potential to be used as diagnostic and therapeutic agent in case of childhood-ALL.     

Total or subtotal replacement of tarsal plate by novel silicone plate for upper eyelid reconstruction in malignant tumors

Purpose:To evaluate the cost, safety, surgical outcome, and efficacy of modified Cutler–Beard eyelid reconstruction utilizing a novel silicone plate as a tarsal plate replacement in the repair of 60% to 100% eyelid defects following the excision of large malignant tumors.Methods:A prospective, noncomparative, interventional study of 30 eyes was done over 3 years. Fourteen patients were female, and 16 patients were male. In all the cases, a silicone plate, the synthetic, artificial tarsal plate, was utilized for a total or subtotal replacement of the tarsal plate. The created defect was measured in mm (length and width) and later expressed in percentage. Pre- and postoperative action of levator palpebrae superioris (LPS) was measured. Pre- and postoperative measurements of the margin-to-margin reflex distance (MRD1) were noted.Results:Preoperative LPS action was 1.23 ± 1.35 mm, whereas postoperative LPS actions at the end of 1 week and 18 months were 11. 8 ± 0.88 mm and 13.53 ± 0. 73 mm, respectively. Preoperative MRD1 was − 3.0 ± 1.144 mm, whereas postoperative MRD1 values at the end of 1 week and 18 months were 2.18 ± 0.27 mm and 4.16 mm ± 0.35, respectively. The mean created defect after the removal of the tumor was 87.3% ±11.10. The mean length of the silicone plate implanted in this study was 27.53 ± 2.48 mm. The follow-up period for the study participants was 18 months.Conclusion:The synthetic novel silicone plate was successful as a tarsal plate replacement. A second surgical site for ear cartilage harvesting is avoided. Cadaver transfer of Achilles tendon carries the risk of transmission of communicable diseases, for example, hepatitis B and HIV. Silicone is an inert, nonreacting, and tissue-tested material, thus eliminating the possibility of graft rejection. This material is readily available and cost-effective. The novel silicone plate is considered to be the most promising alternative material as a tarsal replacement in the future generation.     

Comparison of eyecare utilization at two service delivery levels during the COVID-19 pandemic as a measure of their impact: A multicentric retrospective analysis across four North Indian high-volume eyecare organizations

Purpose:The purpose of this study was to assess the performance of the tertiary centers (TCS) and vision centers (VCs) of the four organizations participating in this research, once the lockdown was lifted, and to compare it with the performance during the same period of the previous year.Methods:This was a cross-sectional study assessing eyecare utilization in the first 2 months after resumption of services post the lockdown in 2020 and comparing that across the same time period in 2019. Anonymized data containing basic demographic details, proportions of patient visits and their reasons, as well as referral information was collected. The drop percentage method was used, and P values were calculated using paired t-tests.Results:Four TCs and 60 VCs were included. Overall, outpatient attendance dipped 51.2% at TCs and 27.5% at VCs, across the 2 years. At both levels of care delivery, the percentage drop in females was more than that in males; however, the overall drop at VCs was less than that at TCs, for both sexes. Eyecare utilization in pediatric populations dropped significantly more than in adult populations, across the overall sample. There was no significant change in referrals for refractive error as a proportion of total outpatients, although there was a significant decline in the same for cataract and specialty treatment.Conclusion:VCs are valuable and successful model for eyecare delivery especially in the continued aftermath of the COVID-19 pandemic.     

QT Dispersion and Viable Myocardium in Patients with Prior Myocardial Infarction and Severe Left Ventricular Dysfunction

Background: QT dispersion (QTd) has been found to correlate to the amount of viable myocardium in patients with Q‐wave myocardial infarction and well‐preserved LV function. However, this relationship is unknown in patients with severe left ventricular dysfunction. Methods: Thirty‐four patients with prior large myocardial infarction and severe left ventricular dysfunction underwent Tc‐99m sestamibi single photon emission cardiac tomography (SPECT) and F‐18 fluorodeoxyglucose (FDG) SPECT. Viability was defined as a defect relative count density (DCD) of at least 20% greater on FDG SPECT. QTd, corrected QT dispersion (QTcd), and QT coefficient of variation (cv) in patients with viable myocardium was compared to those without viable mvocardium in the infarct area. Results: Thirteen patients were excluded from analysis for poor FDG images or inadequate ECG tracings. Of the remaining patients, 10 (48%) were found to have viability on FDG SPECT. QTd, QTcd, and QTcv in patients with viability were: 58 ± 22 ms, 61 ± 23 ms, and 4.81 ± 1.76%, respectively, which did not differ significantly from those in patients without viability (QTd = 56 ± 14 ms, QTcd = 70 ± 16 ms and Qtcv = 5.06 ± 1.20% (P = NS]). Moreover, neither FDG defect size, nor LVEF correlated with QTd. Conclusions: This study indicates no relationship between QTd and viability in patients with myocardial infarction and severe left ventricular dysfunction. A.N.E. 2002;7(1):53–59     

SGLT-2 Inhibitors and Peripheral Artery Disease: A Statistical Hoax or Reality?

Inhibitors of sodium-glucose cotransporters type-2 are the most recent addition to the armamentarium of oral antidiabetic agents. This class of drugs has shown promising results in glycemic control and most importantly to reduce cardiovascular disease (CVD) mortality risk. Despite the encouraging data, there is concern regarding their potential for causing or worsening peripheral artery disease (PAD), which may increase the risk of lower extremity amputations. Following the publication of results of CANVAS and CANVAS-R trials, which revealed that leg and mid-foot amputations occurred about twice as often in patients treated with canagliflozin compared to placebo, the Food and Drug Administration (FDA) in the United States issued a black box warning of leg and foot amputations associated with canagliflozin use. In this article, our main aim is to review the available evidence in preclinical and clinical studies regarding SGLT-2 inhibitors and PAD events, the possible mechanisms related to increased risk of amputation, to evaluate whether it is a class effect or individual drug effect, and most importantly, implications for their continued use as antidiabetic agents. It also raises the issue of including PAD events among the end-points when assessing future antihyperglycemic agents. Thus, we also tried to analyze whether outcomes of SGLT2 inhibitors trials mostly focused on stroke, myocardial infarction, heart failure, and peripheral vascular disease-related outcomes remained underrated.     

A report on a series of nanophthalmos with histopathology and immunohistochemistry analyses using light microscopy

We aimed to study the histopathological and immunohistochemistry features in clinically diagnosed cases of nanophthalmos using light microscopy. This was an observational comparative study. We enrolled four eyes of four consecutive patients with nanophthalmos and visually significant cataract, who underwent cataract surgery with prophylactic posterior sclerostomy. Histological analysis of the excised scleral tissue was done and compared with age-matched cadaver controls between January 2021 and October 2021. Hematoxylin and Eosin (H&E) stains were used for histological analysis, and was further supplemented with immunohistochemistry (IHC) and immunofluorescence (IF) analyses using a simple light microscope. The immunostained sections were analyzed using confocal microscope for the fibronectin expression level. The main outcome measure was demonstration of histological changes of sclera in nanophthalmic eyes undergoing cataract surgery. Light microscopic features of nanophthalmos revealed thick fibers with fraying and lightly stained cores, irregular serrated edges, and randomly interspersed fibroblasts compared to regular arrangement of collagen fibers seen in cadaver controls. Immunohistochemistry analysis with anti-fibronectin antibody showed strong positivity in clustered fibers in nanophthalmos, and less intense diffuse staining in cadaver tissue. Histoclinical correlation was observed in one nanophthalmic scleral tissue with axial length less than 17 mm showing severe disorganization with diffuse collagenization, loss of fibrillary architecture compared to another specimen with axial length more than 17 mm. Simple, cost-effective light microscopy using basic stains was effective in identifying the characteristic histopathological features in nanophthalmic eyes, and this was further highlighted by immunohistochemistry and immunofluorescence analyses.     

Phase-separating RNA-binding proteins form heterogeneous distributions of clusters in subsaturated solutions

Macromolecular phase separation is thought to be one of the processes that drives the formation of membraneless biomolecular condensates in cells. The dynamics of phase separation are thought to follow the tenets of classical nucleation theory, and, therefore, subsaturated solutions should be devoid of clusters with more than a few molecules. We tested this prediction using in vitro biophysical studies to characterize subsaturated solutions of phase-separating RNA-binding proteins with intrinsically disordered prion-like domains and RNA-binding domains. Surprisingly, and in direct contradiction to expectations from classical nucleation theory, we find that subsaturated solutions are characterized by the presence of heterogeneous distributions of clusters. The distributions of cluster sizes, which are dominated by small species, shift continuously toward larger sizes as protein concentrations increase and approach the saturation concentration. As a result, many of the clusters encompass tens to hundreds of molecules, while less than 1% of the solutions are mesoscale species that are several hundred nanometers in diameter. We find that cluster formation in subsaturated solutions and phase separation in supersaturated solutions are strongly coupled via sequence-encoded interactions. We also find that cluster formation and phase separation can be decoupled using solutes as well as specific sets of mutations. Our findings, which are concordant with predictions for associative polymers, implicate an interplay between networks of sequence-specific and solubility-determining interactions that, respectively, govern cluster formation in subsaturated solutions and the saturation concentrations above which phase separation occurs.

Phase separation of RNA-binding proteins with disordered prion-like domains (PLDs) and RNA-binding domains (RBDs) is implicated in the formation and dissolution of membraneless biomolecular condensates such as RNA–protein (RNP) granules (1–9). Macroscopic phase separation is a process whereby a macromolecule in a solvent separates into a dilute, macromolecule-deficient phase that coexists with a dense, macromolecule-rich phase (10, 11). In a binary mixture, the soluble phase, comprising dispersed macromolecules that are well mixed with the solvent, becomes saturated at a concentration designated as c_sat. Above c_sat, for total macromolecular concentrations c_tot that are between the binodal and spinodal, phase separation of full-length RNA-binding proteins and PLDs is thought to follow classical nucleation theory (12–15).In classical nucleation theories, clusters representing incipient forms of the new dense phase form within dispersed phases of supersaturated solutions defined by c_tot > c_sat (16, 17). In the simplest formulation of classical nucleation theory (16–18), the free energy of forming a cluster of radius a is ΔF=−4π3a3Δμρn+4πa2γ. Here, Δµ is the difference in the chemical potential between the one-phase and two-phase regimes (see discussion in SI Appendix), which is negative in supersaturated solutions and positive in subsaturated solutions; ρ_n is the number of molecules per unit volume, and γ is the interfacial tension between dense and dilute phases. At temperature T, in a seed-free solution, the degree of supersaturation s is defined as s≡ΔμRT=ln(ctotcsat), where R is the ideal gas constant. Here, s is positive for c_tot > c_sat, and, as s increases, cluster formation becomes more favorable. Above a critical radius a*, the free energy of cluster formation can overcome the interfacial penalty, and the new dense phase grows in a thermodynamically downhill fashion. Ideas from classical nucleation theory have been applied to analyze and interpret the dynamics of phase separation in supersaturated solutions (12, 13, 15). Classical nucleation theories stand in contrast to two-step nucleation theories that predict the existence of prenucleation clusters in supersaturated solutions (19–22). These newer theories hint at the prospect of there being interesting features in subsaturated solutions, where c_tot < c_sat and s < 0.The subsaturated regime, where s is negative, corresponds to the one-phase regime. Ignoring the interfacial tension, the free energy of realizing clusters with n molecules in subsaturated solutions is: ΔF = –nΔµ. Therefore, the probability P(n) of forming a cluster of n molecules in a subsaturated solution is proportional to exp(sn). Accordingly, the relative probability P(n)/P(1) of forming clusters with n molecules will be exp(s(n – 1)). This quantity, which may be thought of as the concentration of clusters with n molecules, is negligibly small for clusters with more than a few molecules. This is true irrespective of the degree of subsaturation, s. Is this expectation from classical nucleation theories valid? We show here that subsaturated solutions feature a rich distribution of species not anticipated by classical nucleation theories. We report results from measurements of cluster size distributions in subsaturated solutions of phase-separating RNA-binding proteins from the FUS-EWSR1-TAF15 (FET) family. We find that these systems form clusters in subsaturated solutions, and that the cluster sizes follow heavy-tailed distributions. The abundant species are always small clusters. However, as total macromolecular concentration (c_tot) increases, the distributions of cluster sizes shift continuously toward larger values. We discuss these findings in the context of theories for associative polymers (9, 23–30).