Near-infrared spectroscopy enables quantitative evaluation of human cartilage biomechanical properties during arthroscopy

OBJECTIVE

To investigate the feasibility of near-infrared (NIR) spectroscopy (NIRS) for evaluation of human articular cartilage biomechanical properties during arthroscopy.

DESIGN

A novel arthroscopic NIRS probe designed in our research group was utilized by an experienced orthopedic surgeon to measure NIR spectra from articular cartilage of human cadaver knee joints (ex vivo, n = 18) at several measurement locations during an arthroscopic surgery. Osteochondral samples (n = 265) were extracted from the measurement sites for reference analysis. NIR spectra were remeasured in a controlled laboratory environment (in vitro), after which the corresponding cartilage thickness and biomechanical properties were determined. Hybrid multivariate regression models based on principal component analysis and linear mixed effects modeling (PCA-LME) were utilized to relate cartilage in vitro spectra and biomechanical properties, as well as to account for the spatial dependency. Additionally, a k-nearest neighbors (kNN) classifier was employed to reject outlying ex vivo NIR spectra resulting from a non-optimal probe-cartilage contact. Model performance was evaluated for both in vitro and ex vivo NIR spectra via Spearman's rank correlation (ρ) and the ratio of performance to interquartile range (RPIQ).

RESULTS

Regression models accurately predicted cartilage thickness and biomechanical properties from in vitro NIR spectra (Model: 0.77 ≤ ρ ≤ 0.87, 2.03 ≤ RPIQ ≤ 3.0; Validation: 0.74 ≤ ρ ≤ 0.84, 1.87 ≤ RPIQ ≤ 2.90). When predicting cartilage properties from ex vivo NIR spectra (0.33 ≤ ρ ≤ 0.57 and 1.02 ≤ RPIQ ≤ 2.14), a kNN classifier enhanced the accuracy of predictions (0.52 ≤ ρ ≤ 0.87 and 1.06 ≤ RPIQ ≤ 1.88).

CONCLUSION

Arthroscopic NIRS could substantially enhance identification of damaged cartilage by enabling quantitative evaluation of cartilage biomechanical properties. The results demonstrate the capacity of NIRS in clinical applications.

Comparison of articular manifestations of mixed connective tissue disease and systemic lupus erythematosus on clinical examination and musculoskeletal ultrasound

BACKGROUND

Polyarthritis is common to both mixed connective tissue disease (MCTD) and systemic lupus erythematosus (SLE). Apart from being erosive and deforming in the former, we speculated that it was more common and the extent of joints involved would be higher in MCTD.

METHODS

This was a cross-sectional study that included patients with MCTD aged 18-75 years fulfilling the Kasukawa criteria. An equal number of patients with SLE matched for disease duration and gender were included. Clinical manifestations were compared between patients with MCTD and with SLE. Examination of joints was done for the presence of tenderness or swelling and deformity. Musculoskeletal ultrasound was done on the non-dominant hand for detection of synovitis and tenosynovitis and radiographs of the hands were obtained. The use of methotrexate and non-steroidal anti-inflammatory drugs (NSAIDs) for arthritis was noted. Statistical tests used were non-parametric.

RESULTS

Forty patients with MCTD and forty patients with SLE were included in this study, with patients being slightly older in MCTD than SLE (36 ± 10.2, 31.8 ± 13.3 years, p = 0.01). There were no significant differences in disease duration (4.7 ± 3.1, 3.7 ± 2.3, p = 0.1) or gender (females = 38, 38). Nearly one-half of patients with MCTD had at least one swollen joint compared with only 15% of patients with SLE. Median (95% confidence interval) tender joint count (5 (4.8-10.4), 0 (1.3-7.2), p = 0.01) and swollen joint count (0 (0.9-2.6), 0 (0-1.2), p = 0.002) was significantly higher in patients with MCTD compared with SLE. More patients with MCTD than SLE had tender or swollen proximal interphalangeal joints (12, 4, p = 0.025). More patients with MCTD than SLE had received methotrexate (8,2, p = 0.04) and NSAIDs (39, 32, p = 0.03) for arthritis. There was no difference in the number of patients with MCTD or SLE who had evidence of synovitis or tenosynovitis on ultrasound. There was no difference in erosive disease on hand radiographs, but acro-osteolysis was higher among MCTD patients.

CONCLUSIONS

A higher proportion of patients with MCTD had at least one swollen and tender joint as compared with patients with SLE, as well as higher use of methotrexate and NSAIDs. However, there was no difference in ultrasound detected synovitis or tenosynovitis.

Insights on the interaction of Zn2+ cation with triazoles: Structures, bonding, electronic excitation and applications

At present, we investigate the structures, the stability, the bonding and the spectroscopy of the Zn²⁺-triazole complexes (Zn²⁺-Tz), which are subunits of triazolate based porous materials and Zn-enzymes. This theoretical work is performed using ab initio methods and density functional theory (DFT) where dispersion correction is included. Through these benchmarks, we establish the ability and reliability of M05-2X+D3 and PBE0+D3 functionals for the correct description of Zn²⁺-Tz bond since these DFTs lead to close agreement with post Hartree-Fock methods. Therefore, M05-2X+D3 and PBE0+D3 functionals are recommended for the characterization of larger organometallic complexes formed by Zn and N-rich linkers. For Zn²⁺-Tz, we found two stable σ-type complexes: (i) a planar structure where Zn²⁺ links to unprotonated nitrogen and (ii) an out-of-plane cluster where carbon interacts with Zn²⁺. The most stable isomers consist on a coordinated covalent bond between the lone pair of unprotonated nitrogen and the vacant 4s orbital of Zn²⁺. The roles of covalent interactions within these complexes are discussed after vibrational, NBO, NPA charges and orbital analyses. The bonding is dominated by charge transfer from Zn²⁺ to Tz and intramolecular charge transfer, which plays a vital role for the catalytic activity of these complexes. These findings are important to understand, at the microscopic level, the structure and the bonding within triazolate based macromolecular porous materials and Zn-enzymes.

Identification of mega-environments and rice genotypes for general and specific adaptation to saline and alkaline stresses in India

In the present study, a total of 53 promising salt-tolerant genotypes were tested across 18 salt-affected diverse locations for three years. An attempt was made to identify ideal test locations and mega-environments using GGE biplot analysis. The CSSRI sodic environment was the most discriminating location in individual years as well as over the years and could be used to screen out unstable and salt-sensitive genotypes. Genotypes CSR36, CSR-2K-219, and CSR-2K-262 were found ideal across years. Overall, Genotypes CSR-2K-219, CSR-2K-262, and CSR-2K-242 were found superior and stable among all genotypes with higher mean yields. Different sets of genotypes emerged as winners in saline soils but not in sodic soils; however, Genotype CSR-2K-262 was the only genotype that was best under both saline and alkaline environments over the years. The lack of repeatable associations among locations and repeatable mega-environment groupings indicated the complexity of soil salinity. Hence, a multi-location and multi-year evaluation is indispensable for evaluating the test sites as well as identifying genotypes with consistently specific and wider adaptation to particular agro-climatic zones. The genotypes identified in the present study could be used for commercial cultivation across edaphically challenged areas for sustainable production.

Dynamical Analysis of the Hindmarsh-Rose Neuron With Time Delays

This brief is mainly concerned with a series of dynamical analyses of the Hindmarsh-Rose (HR) neuron with state-dependent time delays. The dynamical analyses focus on stability, Hopf bifurcation, as well as chaos and chaos control. Through the stability and bifurcation analysis, we determine that increasing the external current causes the excitable HR neuron to exhibit periodic or chaotic bursting/spiking behaviors and emit subcritical Hopf bifurcation. Furthermore, by choosing a fixed external current and varying the time delay, the stability of the HR neuron is affected. We analyze the chaotic behaviors of the HR neuron under a fixed external current through time series, bifurcation diagram, Lyapunov exponents, and Lyapunov dimension. We also analyze the synchronization of the chaotic time-delayed HR neuron through nonlinear control. Based on an appropriate Lyapunov-Krasovskii functional with triple integral terms, a nonlinear feedback control scheme is designed to achieve synchronization between the uncontrolled and controlled models. The proposed synchronization criteria are derived in terms of linear matrix inequalities to achieve the global asymptotical stability of the considered error model under the designed control scheme. Finally, numerical simulations pertaining to stability, Hopf bifurcation, periodic, chaotic, and synchronized models are provided to demonstrate the effectiveness of the derived theoretical results.

Ab initio and density functional theory (DFT) studies on triflic acid with water and protonated water clusters

The structure, stability and infrared spectral signatures of triflic acid (TA) with water clusters (W_n) and protonated water clusters (TAH⁺W_n, n = 1 - 6) were computed using DFT and MP2 methods. Our calculations show that a minimum of three water molecules are necessary to stabilize the dissociated zwitterionic form of TA. It can be seen from the results that there is no significant movement of protons in smaller (n = 1 and 2) and linear (n = 1 - 6) types of water clusters. Further, the geometries of TAW_n clusters first form a neutral pair (NP) to contact ion pair (CIP), then form a solvent separated ion pair (SSIP) in a water hexamer. These findings reveal that proton transfer may take place through NP to CIP and then CIP to SSIP. The calculated binding energies (BEs) of ion pair clusters is always higher than that of NP clusters (i.e., more stable than the NP). Existing excess proton linear chain clusters transfer a proton to adjacent water molecules via a Grotthuss mechanism, whereas the same isomers in the branched motifs do not conduct protons. Examination of geometrical parameters and infrared frequencies reveals hydronium ion (H₃O⁺ also called Eigen cation) formation in both TAW_n and protonated TAW_n clusters. The stability of Eigen water clusters is three times higher than that of other non-Eigen water clusters. Our study shows clearly that formation of ion pairs in TAW_n and TAH⁺W_n clusters greatly favors proton transfer to neighboring water molecules and also enhances the stability of these complexes.

It's Even Here! Two Rare Cases of Pyriformis Myocysticercus

Cysticercus, the larval form of Taenia Solium, a tapeworm, can infest various tissues in the human body. Though central nervous system involvement is the most dramatic form of infestation, several other uncommon sites of has been reported in the literature. One such involvement is that of the musculature. The most easily recalled manifestation of myocysticercus is that in the orbit where the patients present with painful proptosis. However, other less common muscular sites of involvement are documented in case reports. To the best of our knowledge, there are no documented cases of pyriformis muscle infestation with cysticercus. We came across two interesting cases, where imaging established the diagnosis of isolated pyriformis cysticercosis. Follow up after one month of antihelminthic treatment imaging revealed disappearance of the lesions.

Color Stability of Heat-cure Acrylic Resin Subjected to Simulated Short-term Immersion in Fast-acting Denture Cleansers

Background:

Regular usage of denture cleansers is recommended in complete denture wearers for effective plaque control, and these cleansers alter the physical properties of acrylic resin over a period of time. Thus, an in vitro study was carried out to assess the effect of denture cleansers on the color stability of heat-cure denture base resin.

Aim:

The aim of the present study was to evaluate the effect of commercially available fast-acting denture cleansers on the color stability of heat-cure denture base resin at different time intervals.

Materials and Methods:

Thirty-six heat-cure acrylic resin (Ivoclar Triplex Hot-V) specimens are randomly allocated into four groups – Group A (distilled water as control); Group B (polident – 3 min); Group C (fixodent scope plus); and Group D (stain away plus) comprising of nine samples each. After recording the baseline values, the specimens were immersed in their respective cleansing solutions for a prescribed time interval. This procedure was repeated daily, and the color change (ΔE) was evaluated after 90 and 180 days interval using a colorimeter in a standard “Commission International de l'Eclairage” color system.

Statistical Analysis Used:

Paired t-test and Dunnett's T3 test.

Results:

All the groups exhibited a variable color change (ΔE) for an immersion period of 90 days. However, significant color differences (P = 0.001) were noticed among the test groups after 180 days.

Conclusion:

The color change of denture base resin was greater for Group D followed by Groups B, C, and A respectively after 180 days of immersion. The ΔE values of all test groups increased with time.

Assessment of premature atherosclerosis in systemic lupus erythematosus patients with and without nephritis

BACKGROUND

Risk of subclinical atherosclerosis is increased in patients with systemic lupus erythematosus (SLE). We correlated carotid intima media thickness (CIMT) and endothelial dysfunction through flow-mediated dilation (FMD) in SLE patients with the SLE Disease Activity Index (SLEDAI).

METHODS

This single-centre cross-sectional study recruited 100 consenting SLE outpatients (ACR 1997 criteria) out of which 50 had nephritis, with disease duration of ≥2 years for SLE and ≥6 months for lupus nephritis. We measured baseline laboratory levels, CIMT and FMD (after brachial BP cuff inflation up to 200 mmHg for five minutes), and calculated SLEDAI.

RESULTS

Mean age was 29.88 ± 6.53 years; 95/100 were female. CIMT showed positive correlation (p = 0.037; rho = 0.209), and FMD showed inverse correlation with patient's age (p = 0.011; rho = -0.252). CIMT and FMD were more deranged in patients aged ≥25 years (p < 0.05). CIMT was not significantly different between SLE patients with and without nephritis (p > 0.05), whereas SLEDAI and FMD were more deranged in nephritis patients (p < 0.05). In patients without nephritis, FMD showed significant inverse correlation with disease duration (p = 0.043; rho = -0.288) and urine albumin (p = 0.045; rho = -0.285). In nephritis patients, the correlation between age of the patient was significantly positive with CIMT (p = 0.001; rho = 0.441) and significantly inverse with FMD (p = 0.028; rho = -0.312).

CONCLUSION

SLE patients with nephritis are at a higher risk to develop arterial stiffening, leading to early end-organ damage. Early aggressive treatment may prevent endothelial dysfunction. FMD using vascular ultrasonography on the brachial artery represents a non-invasive, repeatable and useful method for the assessment of endothelial dysfunction.

Structure, Spectroscopy, and Bonding within the Zn(q+)-Imidazole(n) (q = 0, 1, 2; n = 1-4) Clusters and Implications for Zeolitic Imidazolate Frameworks and Zn-Enzymes

Using density functional theory (DFT) with dispersion correction and ab initio post Hartree-Fock methods, we treat the bonding, the structure, the stability, and the spectroscopy of the complexes between Zn(q+) and imidazole (Im), Zn(q+)Imn (where q = 0, 1 and 2; n = 1-4). These entities are subunits of zeolitic imidazolate frameworks (ZIFs) and Zn-enzymes, which possess relevant roles in industrial and biological domains, respectively. We also investigate the Imn (n = 2-4) clusters for comparison. For each species, we determine several new structures that were not found previously. Our calculations show a competition between atomic metal solvation, by either σ-type interactions or π-stacking type interaction, and proton transfer through hydrogen bonding (H-bonding) in charged species. This results in several geometrical environments around the metal. These are connected with structural properties and the functional role of Zn cation within ZIFs and Zn-enzymes. Moreover, we show that the Zn(2+)Imn subunits do not absorb in the visible domain, which may be related to the photostability of ZIFs. Our findings are important for the development of new applications of ZIFs and metalloenzymes.