Comparison of different internal fixation models in ankle arthrodesis using 3D finite-element analysis.

BACKGROUND: The purpose of this study is to use three-dimensional finite-element analysis to better understand the biomechanical features of various internal fixators for ankle arthrodesis. METHODS: We used finite-element analysis to compare four different types of internal fixations in ankle arthrodesis: Group A had three crossed screws (Ø6.5 mm); Group B had two crossed screws (Ø6.5 mm) and an anterior plate (Ø2.7 mm); Group C only had an anterior anatomical plate (Ø3.5 mm); Group D had one anterior anatomical plate (Ø3.5 mm) and one posterior-lateral screw (Ø6.5 mm). We adopted Ansys 21.0 software to analyze and compare the four types in terms of the displacement of the arthrodesis surface and the stress peak and stress distribution of these models under intorsion, extorsion, dorsiflexion torque, and neutral vertical load. RESULTS: ① Displacement of the arthrodesis surface: In Group A, the maximum displacement was larger than Group D under neutral vertical load and dorsiflexion torque but less than it under intorsion and extorsion torque. In Group B, the maximum displacement against dorsiflexion, neutral vertical load, intorsion, and extorsion was less than that in the other three fixation models. In Group C, the maximum displacement against the above four loading patterns were significantly higher than that in another three fixation models. ② Stress peak and stress distribution: based on the stress distribution of the four models, the peak von Mises stress was concentrated in the central sections of the compression screws, plate joints, and bending parts of the plates. CONCLUSIONS: The fixation model consisting of two crossed screws and an anterior outperformed the other three fixation models in terms of biomedical advantages; thus, this model can be deemed a safe and reliable internal fixation approach for ankle arthrodesis.

The Treatment Experience of Different Types of Flaps for Repairing Soft Tissue Defects of the Heel.

OBJECTIVE: To summarize the clinical application effects of three different types of flaps for repairing soft tissue defects of the heel, and to discuss the importance of tissue repair and heel reconstruction. METHODS: A total of 46 cases with skin tissue defects of the heel with deep tissue exposure were treated. The reasons for the defect were trauma (n = 26), burns and electric shocks (n = 12), chronic ulcers (n = 2), postoperative infection of the calcaneus and Achilles tendon (n = 5), and tumor resection (n = 1). The scope of wound defect was 2.0×2.5 to approximately 15.0×20.0 cm. The flaps used were medial plantar island flaps (n = 9), distal pedicled sural neurovascular island flaps (n = 23), and free anterolateral thigh (perforator) flaps (n = 14). The flap cutting range was 3.0×3.5 to approximately 16.0×22.0 cm. RESULTS: After surgery, all 46 flaps survived. In two cases, patients experienced partial epidermal necrosis at the distal end of the flap that healed after local dressing exchange, and after this treatment, the complete skin grafts survived. Follow-up was conducted in 40 cases, with an average follow-up duration of 8.2 months (3-44 months) and the two-point discrimination of 5-14 mm. The average American Orthopaedic Foot and Ankle Society scale was 89.2 points with good flap color and texture, satisfactory appearance, and normal gait. CONCLUSION: The repair method should be selected according to the"5-zone method": The plantar medial island flap is suitable for small area (<5 cm) of medial, posterior and plantar defects. The distal pedicled sural neurovascular flap is suitable for lateral, posterior, and medium-range (6-10 cm) joint area defects. The free anterolateral thigh perforator flap is suitable for large-scale (>10 cm) joint area defects.

Changes of Anti-tuberculosis Herbs Formula During Past Three Decades in Contrast to Ancient Ones.

OBJECTIVE: To investigate the evolution of herbal medicine in treating tuberculosis (TB) and encourage anti-TB drug discovery and development. METHODS: In this study, 477 ancient traditional Chinese medicine formulae were collected from the Dictionary of Traditional Chinese Medicine Prescriptions and 172 modern Chinese medicine formulae (from 1986 to 2016) were collected by searching 4 databases: WanFang Data Knowledge Service Platform, China National Knowledge Infrastructure Database (CNKI), China Science and Technology Journal Database (VIP) and Chinese Bio-medical Literature and Retrieval System (SinoMed) in Chinese. We restricted the search to publications in Chinese. Further data analysis was done using the Traditional Chinese Medicine Inheritance Support System version 2 Software. RESULTS: There were 425 herbs in the 477 ancient formulae and 257 herbs in the 172 modern formulae. Half of the top 30 herbs were shared by both modern and ancient prescriptions. They are Radix Ophiopogonis, Astragalus membranaceus, Fritillaria cirrhosa, Dried rehmannia glutinosa, Poria cocos, Angelica sinensis, Prepared rehmannia glutinosa, Platycodon Root, Radix paeoniae alba, Schisandra chinensis, Bighead atractylodes rhizome, Rhizoma anemarrhenae, Cortex lycii radicis and Radix Scutellariae. Only two groups of herbs with a high correlation coefficient were found in both modern and ancient prescriptions, the Dried rehmannia glutinosa with Radix ophiopogonis, and Radix ophiopogonis with Prepared rehmannia glutinosa. There were 9 and 15 core herb combinations in modern and ancient prescriptions, respectively, but no one was found simutaniously in both modern and ancient prescriptions. CONCLUSIONS: Although there were wide variations in the herb groups and herb combinations in the formulae, half of the top 30 herbs were found in both modern and ancient prescriptions. The core herb combinations in modern and ancient prescriptions could help us to improve the priscription for treatment of TB.

Monocyte chemotactic protein-inducing protein 1 negatively regulating asthmatic airway inflammation and mucus hypersecretion involving γ-aminobutyric acid type A receptor signaling pathway in vivo and in vitro.

BACKGROUND: Mounting evidence, consistent with our previous study, showed that γ-aminobutyric acid type A receptor (GABAAR) played an indispensable role in airway inflammation and mucus hypersecretion in asthma. Monocyte chemotactic protein-inducing protein 1 (MCPIP1) was a key negative regulator of inflammation. Recent studies showed that inflammation was largely suppressed by enhanced MCPIP1 expression in many inflammatory diseases. However, the role and potential mechanism of MCPIP1 in airway inflammation and mucus hypersecretion in asthma were still not well studied. This study was to explore the role of MCPIP1 in asthmatic airway inflammation and mucus hypersecretion in both mice and BEAS-2B cells, and its potential mechanism. METHODS: In vivo, mice were sensitized and challenged by ovalbumin (OVA) to induce asthma. Airway inflammation and mucus secretion were analyzed. In vitro, BEAS-2B cells were chosen. Interleukin (IL)-13 was used to stimulate inflammation and mucus hypersecretion in cells. MCPIP1 Lentiviral vector (LA-MCPIP1) and plasmid-MCPIP1 were used to up-regulate MCPIP1 in lung and cells, respectively. MCP-1, thymic stromal lymphopoietin (TSLP), mucin 5AC (MUC5AC), MCPIP1, and GABAARß2 expressions were measured in both lung and BEAS-2B cells. Immunofluorescence staining was performed to observe the expression of GABAARß2 in cells. RESULTS: MCPIP1 was up-regulated by LA-MCPIP1 (P < 0.001) and plasmid-MCPIP1 (P < 0.001) in lung and cells, respectively. OVA-induced airway inflammation and mucus hypersecretion, OVA-enhanced MCP-1, TSLP, MUC5AC, and GABAARß2 expressions, and OVA-reduced MCPIP1 were significantly blunted by LA-MCPIP1 in mice (all P < 0.001). IL-13-enhanced MCP-1, TSLP, MUC5AC, and GABAARß2 expressions, and IL-13-reduced MCPIP1 were markedly abrogated by plasmid-MCPIP1 in BEAS-2B cells (all P < 0.001). CONCLUSION: The results of this study suggested that OVA and IL-13-induced airway inflammation and mucus hypersecretion were negatively regulated by MCPIP1 in both lung and BEAS-2B cells, involving GABAAR signaling pathway.

Differences in the population of genetics of Mycobacterium tuberculosis between urban migrants and local residents in Beijing, China.

BACKGROUND: Currently, migration has become one of the risk factors of high burden of tuberculosis in China. This study was to explore the influence of mass migration on the dynamics of Mycobacterium (M.) tuberculosis in Beijing, the capital and an urban area of China. METHODS: Three hundred and thirty-six M. tuberculosis strains from the Changping district, where the problem of urban migrants was more pronounced than in other Beijing regions, were genotyped by Spoligotyping, large sequence polymorphisms (LSPs 105 and 181), and variable number tandem repeat (VNTR) typing. Based on the genotype data, the phylogeny of the isolates was studied. RESULTS: In Changping district, the proportion of Beijing lineage M. tuberculosis isolates amounted to 89.0% (299/336), among which 86.6 % (252) belonged to the modern lineage. The frequency of modern Beijing lineage strains is so high (around 75% (252/336)) that associated risk factors affecting the tuberculosis epidemic cannot be determined. The time to the most recent common ancestor (TMRCA) of the Beijing lineage strains was estimated to be 5073 (95% CI: 4000-6200) years. There was no significant difference in the genetic variation of Beijing isolates from urban migrants and local residents. CONCLUSIONS: The clone of modern Beijing lineage M. tuberculosis, which is dominant in the Beijing area, most likely started to expand with the five thousand-year-old Chinese civilization. In the future, with the urbanization in the whole of China, modern Beijing lineage M. tuberculosis may gain the larger geographical spread.

Theoretical analysis for spherical aberration induction with low-order correction in refractive surgery.

A theoretical foundation for the analysis of ocular aberration correction is developed. It enables a comparative study for two different refractive surgical approaches, namely, the conventional and the Q-preserved treatment modalities. A refractive surgical factor is identified that leads to a simple cubic function for the postoperative asphericity factor for the conventional treatment. A formulation is developed that paves the way for the calculation of the induction of spherical aberration for low-order aberration correction in refractive surgery. Opposite to the general belief, the Munnerlyn shape makes myopic LASIK more prolate, not oblate. A Monte Carlo simulation was conducted for 1000 eyes for these two refractive surgical modalities. It was found that, although the postoperative spherical aberration is similar for these surgical modalities, for the induction of spherical aberration from the ablation target shape, the conventional modality appears to be slightly more predictable.

[Evaluation of the mycobacterium efficacy of linezolid in vitro].

OBJECTIVE: To evaluate the mycobacterium efficacy of linezolid to Mycobacterium tuberculosis bacilli and Non-tuberculous mycobacteria (NTM) in vitro, and to analyze the interaction between linezolid and other anti-TB drugs in vitro. METHODS: The minimum inhibition concentrations (MICs) of 121 Mycobacterium tuberculosis clinical isolates and 30 non tuberculosis Mycobacteria isolates and the corresponding standard strains to linezolid were tested by Microplate Alamar Blue assay (MABA). The interactions between linezolid and rifampicin, isoniazid, streptomycin, ethambutol, kanamycin, ofloxacin, and rifabutin were also tested in vitro by fractional inhibitory concentration index (FICI) method. RESULTS: 94.2% (114/121) of the Mycobacterium tuberculosis isolates were inhibited by linezolid at concentrations ≤ 1 mg/L. There was no statistical difference in the MIC values of sensitive strains, MDR strains, and drug resistant strains other than MDR (χ(2) = 0.481, P > 0.05). Only Mycobacterium kansasii was totally sensitive to linezolid among the 5 tested NTM strains. In vitro drug combination testing displayed overall non-association between linezolid and 7 other anti-TB drugs among 8 clinical isolates and H(37) Rv. CONCLUSIONS: Linezolid showed great mycobacterium efficacy to Mycobacterium tuberculosis clinical isolates in vitro, regardless of the strains' drug resistant parameters. This study also showed non-association of the interactions between linezolid and 7 other anti-TB drugs in vitro.

Validity of scaling zernike coefficients to a larger diameter for refractive surgery.

PURPOSE: To investigate the validity of a Zernike rescaling algorithm to a larger wavefront diameter. METHODS: Using 4256 preoperative wavefront examinations, the variability of inter-examination wavefront root-mean-square (RMS) was compared to the error induced due to scaling Zernike coefficients to a larger diameter. The validity of scaling Zernike coefficients was set when the error due to the scaling was the same as the variability of the inter-examination wavefronts. The inter-examination variability was calculated from eyes having at least 3 same-day, preoperative examinations over the same diameters. Error from scaling Zernike coefficients to a larger diameter was calculated by comparing the wavefront for a (scaled-up) set of Zernike coefficients to the wavefront of the average of Zernike coefficient sets at a larger diameter for the same eye. Wavefront diameters of 5, 5.5, 6, 6.5, and 7 mm were considered. RESULTS: No significant difference was found for the variability for different pupil sizes. The error due to scaling Zernike coefficients to a larger pupil size was generally smaller than the inter-examination variability when the new diameter was 0.25 mm larger than the original diameter. The error was comparable to the inter-examination variability when the new diameter was 0.5 mm larger. The error became larger when the new diameter was >0.75 mm larger than the original diameter. CONCLUSIONS: Rescaling Zernike coefficients from a smaller diameter to a larger one has practical applications in optical zone extension for wavefront-guided refractive surgery.

Spherical aberrations of human astigmatic corneas.

PURPOSE: To evaluate whether the average spherical aberration of human astigmatic corneas is statistically equivalent to human nonastigmatic corneas. METHODS: Spherical aberrations of 445 astigmatic corneas prior to laser vision correction were retrospectively investigated to determine Zernike coefficients for central corneal areas 6 mm in diameter using CTView (Sarver and Associates). Data were divided into groups according to cylinder power (0.01 to 0.25 diopters [D], 0.26 to 0.75 D, 0.76 to 1.06 D, 1.07 to 1.53 D, 1.54 to 2.00 D, and >2.00 D) and according to age by decade. Spherical aberrations were correlated with age and astigmatic power among groups and the entire population. Statistical analyses were conducted, and P<.05 was considered statistically significant. RESULTS: Mean patient age was 42.6±11 years. Astigmatic corneas had an average astigmatic power of 0.78±0.58 D and mean spherical aberration was 0.25±0.13 µm for the entire population and approximately the same (0.27 µm) for individual groups, ranging from 0.23 to 0.29 µm (P>.05 for all tested groups). CONCLUSIONS: Mean spherical aberration of astigmatic corneas was not correlated significantly with cylinder power or age (P>.05). Spherical aberrations are similar to those of nonastigmatic corneas, permitting the use of these additional data in the design of aspheric toric intra-ocular lenses.

Wavefront propagation from one plane to another with the use of Zernike polynomials and Taylor monomials.

In wavefront-driven vision correction, ocular aberrations are often measured on the pupil plane and the correction is applied on a different plane. The problem with this practice is that any changes undergone by the wavefront as it propagates between planes are not currently included in devising customized vision correction. With some valid approximations, we have developed an analytical foundation based on geometric optics in which Zernike polynomials are used to characterize the propagation of the wavefront from one plane to another. Both the boundary and the magnitude of the wavefront change after the propagation. Taylor monomials were used to realize the propagation because of their simple form for this purpose. The method we developed to identify changes in low-order aberrations was verified with the classical vertex correction formula. The method we developed to identify changes in high-order aberrations was verified with ZEMAX ray-tracing software. Although the method may not be valid for highly irregular wavefronts and it was only proven for wavefronts with low-order or high-order aberrations, our analysis showed that changes in the propagating wavefront are significant and should, therefore, be included in calculating vision correction. This new approach could be of major significance in calculating wavefront-driven vision correction whether by refractive surgery, contact lenses, intraocular lenses, or spectacles.

Orthonormal polynomials in wavefront analysis: error analysis.

Zernike circle polynomials are in widespread use for wavefront analysis because of their orthogonality over a circular pupil and their representation of balanced classical aberrations. However, they are not appropriate for noncircular pupils, such as annular, hexagonal, elliptical, rectangular, and square pupils, due to their lack of orthogonality over such pupils. We emphasize the use of orthonormal polynomials for such pupils, but we show how to obtain the Zernike coefficients correctly. We illustrate that the wavefront fitting with a set of orthonormal polynomials is identical to the fitting with a corresponding set of Zernike polynomials. This is a consequence of the fact that each orthonormal polynomial is a linear combination of the Zernike polynomials. However, since the Zernike polynomials do not represent balanced aberrations for a noncircular pupil, the Zernike coefficients lack the physical significance that the orthonormal coefficients provide. We also analyze the error that arises if Zernike polynomials are used for noncircular pupils by treating them as circular pupils and illustrate it with numerical examples.

Orthonormal polynomials in wavefront analysis: analytical solution.

Zernike circle polynomials are in widespread use for wavefront analysis because of their orthogonality over a circular pupil and their representation of balanced classical aberrations. In recent papers, we derived closed-form polynomials that are orthonormal over a hexagonal pupil, such as the hexagonal segments of a large mirror. We extend our work to elliptical, rectangular, and square pupils. Using the circle polynomials as the basis functions for their orthogonalization over such pupils, we derive closed-form polynomials that are orthonormal over them. These polynomials are unique in that they are not only orthogonal across such pupils, but also represent balanced classical aberrations, just as the Zernike circle polynomials are unique in these respects for circular pupils. The polynomials are given in terms of the circle polynomials as well as in polar and Cartesian coordinates. Relationships between the orthonormal coefficients and the corresponding Zernike coefficients for a given pupil are also obtained. The orthonormal polynomials for a one-dimensional slit pupil are obtained as a limiting case of a rectangular pupil.

Nonrecursive determination of orthonormal polynomials with matrix formulation.

A general theoretical approach has been developed for the determination of orthonormal polynomials over any integrable domain, such as a hexagon. This approach is better than the classical Gram-Schmidt orthogonalization process because it is nonrecursvie and can be performed rapidly with matrix transformations. The determination of the orthonormal hexagonal polynomials is demonstrated as an example of the matrix approach.

Zernike annular polynomials and atmospheric turbulence.

Imaging through atmospheric turbulence by systems with annular pupils is discussed using the Zernike annular polynomials. Fourier transforms of these polynomials are derived analytically to facilitate the calculation of variance and covariance of the aberration coefficients. Zernike annular shape functions are derived and used to calculate the Strehl ratio and the residual phase structure and mutual coherence functions when a certain number of modes are corrected using, say, a deformable mirror. Special cases of long- and short-exposure images are also considered. The results for systems with a circular pupil are obtained as a special case of the annular pupil.

Comparison of wavefront reconstructions with Zernike polynomials and Fourier transforms.

PURPOSE: To make a direct comparison between Fourier and Zernike reconstructions of ocular wavefronts using a newly available analytical theory by which Fourier coefficients can be converted to Zernike coefficients and vice versa. METHODS: Noise-free random wavefronts were simulated with up to the 15th order of Zernike polynomials. For each case, 100 random wavefronts were simulated separately. These wavefronts were smoothed with a low-pass Gaussian filter to remove edge effects. Wavefront slopes were calculated, and normally distributed random noise was added within the circular area to simulate realistic Shack-Hartmann spot patterns. Three wavefront reconstruction methods were performed. The wavefront surface error was calculated as the percentage of the input wavefront root mean square. RESULTS: Fourier full reconstruction was more accurate than Zernike reconstruction from the 6th to the 10th orders for low-to-moderate noise levels. Fourier reconstruction was found to be approximately 100 times faster than Zernike reconstruction. Fourier reconstruction always makes optimal use of information. For Zernike reconstruction, however, the optimal number of orders must be chosen manually. The optimal Zernike order for Zernike reconstruction is lower for smaller pupils than larger pupils. CONCLUSIONS: Fourier full reconstruction is faster and more accurate than Zernike reconstruction, makes optimal use of slope information, and better represents ocular aberrations of highly aberrated eyes.

Orthonormal polynomials for hexagonal pupils.

The problem of determining the orthonormal polynomials for hexagonal pupils by the Gram-Schmidt orthogonalization of Zernike circle polynomials is revisited, and closed-form expressions for the hexagonal polynomials are given. We show how the orthonormal coefficients are related to the corresponding Zernike coefficients for a hexagonal pupil and emphasize that it is the former that should be used for any quantitative wavefront analysis for such a pupil.

Wavefront expansion basis functions and their relationships.

Wavefront expansion basis functions are important in representing ocular aberrations and phase perturbations due to atmospheric turbulence. A general discussion is presented for the conversions of the coefficients between any two sets of basis functions. Several popular sets of basis functions, namely, Zernike polynomials, Fourier series, and Taylor monomials, are discussed and the conversion matrices between any two of these basis functions are derived. Some analytical and numerical examples are given to demonstrate conversion of coefficients of different basis function sets.

Optical surface optimization for the correction of presbyopia.

Presbyopia, the gradual loss of accommodation that accompanies aging, can be corrected by creating asphericity in the optical path of the eye. Bifocal and aspheric contact lenses, intraocular lenses, spectacle lenses, and laser refractive surgery are all widely used to alleviate the symptoms of presbyopia. These types of corrective surfaces try to concentrate vision in limited peaks over the full range of vergences. The methodology described in this paper is designed to correct presbyopia by optimizing vision over the entire target range of near to distant. A corrective surface was created by employing an iterative function minimization algorithm to optimize an optical metric. In most cases, it is possible to obtain an optical surface that will optically compensate for presbyopia.