Principles and clinical applications of transcutaneous laser-assisted drug delivery: A narrative review.

Introduction: Transcutaneous laser-assisted drug delivery (LADD) is recognized as a developing therapy for skin disorders. Method: Current literature was reviewed to summarize current applications for LADD. Discussion: 12 clinical applications for this therapy are currently reported. Conclusion: LADD has potential for wide application in skin disorder treatment. Lay Summary: Laser assisted drug delivery improves drug bioavailability for treatment of skin disorders. This technique is being assessed clinically in disorders ranging from skin cancers to alopecia.

Biomechanical analysis and clinical observation of 3D-printed acetabular prosthesis for the acetabular reconstruction of total hip arthroplasty in Crowe III hip dysplasia.

Objective: This study aimed to evaluate the biomechanical effectiveness of 3D-printed integrated acetabular prosthesis (IAP) and modular acetabular prosthesis (MAP) in reconstructing the acetabulum for patients with Crowe III developmental dysplasia of the hip (DDH). The results of this study can provide a theoretical foundation for the treatment of Crowe III DDH in total hip arthroplasty (THA). Methods: Finite element (FE) analysis models were created to reconstruct Crowe III DDH acetabular defects using IAP and MAP. The contact stress and relative micromotion between the acetabular prosthesis and the host bone were analyzed by gradually loading in three increments (210 N, 2100 N, and 4200 N). In addition, five patients with Crowe III DDH who underwent IAP acetabular reconstruction were observed. Results: At the same load, the peak values of IAP contact stress and relative micromotion were lower than those of MAP acetabular reconstruction. Under jogging load, the MAP metal augment's peak stress exceeded porous tantalum yield strength, and the risk of prosthesis fracture was higher. The peak stress in the bone interface in contact with the MAP during walking and jogging was higher than that in the cancellous bone, while that of IAP was higher than that of the cancellous bone only under jogging load, so the risk of MAP cancellous bone failure was greater. Under jogging load, the relative micromotion of the MAP reconstruction acetabular implant was 45.2 µm, which was not conducive to bone growth, while under three different loads, the relative micromotion of the IAP acetabular implant was 1.5-11.2 µm, all <40 µm, which was beneficial to bone growth. Five patients with IAP acetabular reconstruction were followed up for 11.8 ± 3.4 months, and the Harris score of the last follow-up was 85.4 ± 5.5. The imaging results showed good stability of all prostheses with no adverse conditions observed. Conclusion: Compared with acetabular reconstruction with MAP, IAP has a lower risk of loosening and fracture, as well as a better long-term stability. The application of IAP is an ideal acetabular reconstruction method for Crowe III DDH.

Finite element analysis of biomechanical effects of mineralized collagen modified bone cement on adjacent vertebral body after vertebroplasty.

Objective: To investigate whether mineralized collagen modified polymethyl methacrylate (MC-PMMA) bone cement impacts the implanted vertebral body and adjacent segments and the feasibility of biomechanical properties compared with common bone cement in the treatment of osteoporotic vertebral compression fractures (OVCF). Methods: A healthy volunteer was selected to perform a three-dimensional reconstruction of the T11-L1 vertebral body to establish the corresponding finite element model of the spine, and the changes in the stress distribution of different types of cement were biomechanically analyzed in groups by applying quantitative loads. Results: The stress distribution of the T11-L1 vertebral body was similar between the two bone types of cement under various stress conditions. Conclusion: Mineralized collagen modified bone cement had the advantages of promoting bone regeneration, good biocompatibility, good transformability, and coupling, and had support strength not inferior to common PMMA bone cement, indicating it has good development prospects and potential.

[Biomechanical research progress of common acetabular reconstruction techniques for Crowe type â ¡ and â ¢ developmental dysplasia of the hip].

Objective: To summarize the characteristics and biomechanical research progress of common acetabular reconstruction techniques in patients with Crowe type Ⅱ and Ⅲ developmental dysplasia of the hip (DDH) undergoing total hip arthroplasty (THA), and provide references for selecting appropriate acetabular reconstruction techniques for clinical treatment of Crowe type Ⅱ and Ⅲ DDH. Methods: The domestic and foreign relevant literature on biomechanics of acetabular reconstruction with Crowe type Ⅱ and Ⅲ DDH was reviewed, and the research progress was summarized. Results: At present, there are many acetabular reconstruction techniques in Crowe type Ⅱ and Ⅲ DDH patients undergoing THA, with their own characteristics due to structural and biomechanical differences. The acetabular roof reconstruction technique enables the acetabular cup prosthesis to obtain satisfactory initial stability, increases the acetabular bone reserve, and provides a bone mass basis for the possible secondary revision. The medial protrusio technique (MPT) reduces the stress in the weight-bearing area of the hip joint and the wear of the prosthesis, and increases the service life of the prosthesis. Small acetabulum cup technique enables shallow small acetabulum to match suitable acetabulum cup to obtain ideal cup coverage, but small acetabulum cup also increases the stress per unit area of acetabulum cup, which is not conducive to the long-term effectiveness. The rotation center up-shifting technique increases the initial stability of the cup. Conclusion: Currently, there is no detailed standard guidance for the selection of acetabular reconstruction in THA with Crowe type Ⅱ and Ⅲ DDH, and the appropriate acetabular reconstruction technique should be selected according to the different types of DDH.

Biomechanical study of internal fixation methods for femoral neck fractures based on Pauwels angle.

Objective: To select the most appropriate internal fixation method based on the Pauwels angle, in order to provide a new concept for clinical accurate treatment of femoral neck fractures (FNFs). Methods: FNFs models of Pauwels 30 ° ; 40 ° ; 50 ° ; 60 ° were created respectively. For Pauwels ≤ 50 ° , 1, 2 and 3 Cannulated Compression Screws (CCS) and Porous Tantalum Screws (PTS) were used to fix the fracture for the models. For Pauwels 60 ° , 3CCS and Medial Buttress Plate (MBP) combined with 1, 2 and 3CCS were used to fix the fracture. Based on the results of the finite element (FE) analysis, the biomechanical properties of each model were compared by analyzing and evaluating the following four parameters: maximal stress of the bone (MBS), maximal stress of the implants (MIS), maximal displacement of bone (MBD), interfragmentary motion (IFM). Results: At Pauwels 30 ° , the larger parameters were found in 1CCS, which was 94.8 MPa (MBS), 307.7 MPa (MIS), 0.86 mm (MBD) and 0.36 mm (IFM). In 2CCS group, the parameters were 86.1 MPa (MBS), 254.4 MPa (MIS), 0.73 mm (MBD) and 0.27 mm (IFM), which were similar to those of PTS. At Pauwels 40 ° ; 50 ° , with the increase of the number of used CCS, accordingly, the parameters decreased. Particularly, the MIS (Pauwels 50 ° ) of 1CCS was 1,195.3 MPa, but the other were less than the yield range of the materials. At Pauwels 60 ° , the MBS of 3CCS group was 128.6 Mpa, which had the risk of failure. In 2CCS + MBP group, the parameters were 124.2 MPa (MBS), 602.5 MPa (MIS), 0.75 mm (MBD) and 0.48 mm (IFM), The model stability was significantly enhanced after adding MBP. Conclusion: Pauwels type Ⅰ (< 30 ° ) fractures can reduce the number of CCS, and PTS is an appropriate alternative treatment. For Pauwels type Ⅱ fractures ( 30 ° ∼ 50 ° ), the 3CCS fixation method is still recommended. For Pauwels type Ⅲ fractures (> 50 ° ), it is recommended to add MBP to the medial femoral neck and combine with 2CCS to establish a satisfactory fracture healing environment.

Treatment of Acetabular Bone Defect in Revision of Total Hip Arthroplasty Using 3D Printed Tantalum Acetabular Augment.

OBJECTIVE: The treatment of acetabular defects is one of the most difficult challenges of revision of total hip arthroplasty (RTHA), and tantalum is regarded as a promising bone substitute material. This study aims to investigate the effectiveness of 3D printed acetabular augment used in RTHA for the treatment of acetabular bone defect. METHODS: A retrospective analysis of the clinical data of seven patients who had undergone RTHA was carried out using 3D printed acetabular augment from January 2017 to December 2018. The CT data of the patients were exported to Mimics 21.0 software (Materialise, Leuven, Belgium), and the acetabular bone defect augment were designed, printed and then implanted during operation. The postoperative Harris score, visual analogue scale (VAS) score and prosthesis position were observed to evaluate the clinical outcome. A I-test was used for preoperative and postoperative comparison of the paired-design dataset. RESULTS: A firm attachment of the bone augment to the acetabulum during operation without any complications was found during the follow-up time 2.8-4.3 years. The VAS score of all patients was found 6.9 ± 1.4 before operation and was 0.7 ± 0.7 at the last follow-up (P ≤ 0.001), and the Harris hip scores, were 31.9 ± 10.3 and 73.3 ± 12.8 before operation, and at the last follow-up (P ≤ 0.001), respectively. Moreover, no loosening sign between the bone defect augment and the acetabulum was observed during the entire implantation period. CONCLUSION: 3D printed acetabular augment is effective in reconstructing the acetabulum following an acetabular bone defect revision, which enhances the hip joint function and eventually makes a satisfactory stable prosthetic.

[Research progress in biomechanics of common internal fixation for femoral neck fracture].

Objective: To summarize the characteristics and biomechanical research progress of common internal fixation for femoral neck fractures in recent years, so as to provide reference to clinical treatment of femoral neck fracture. Methods: The domestic and foreign relevant literature on biomechanics of internal fixation of femoral neck fracture in recent years was reviewed, and the biomechanical research progress was summarized. Results: Among the internal fixations currently used in the treatment of femoral neck fractures, three cannulated screws can provide sliding compression at the end of the fracture, but the shear resistance is weak, and the risk of long-term internal fixation failure is high; dynamic hip screw and proximal femoral locking plate have excellent angle stability and overall strength; medial buttress plate can transform vertical shear force into compressive stress to promote fracture healing and produce a certain anti-rotation effect; femoral neck system can support the fracture in multi-axial direction, with excellent anti-rotation and anti-shortening properties; and cephalomedullary nails have high overall strength and failure load. Different internal fixations have their own indications due to differences in structure and biomechanics. Conclusion: At present, there is no detailed standard guidance of internal fixation selection. Clinically, the appropriate treatment should be selected according to the fracture types of patients.

Assessment of culturable airborne bacteria of indoor environments in classrooms, dormitories and dining hall at university: a case study in China.

University students' health may be adversely affected by exposure to indoor bacterial contaminants on their campuses. This study aims (1) to quantify culturable bacterial concentrations in three indoor environments at a university, (2) to investigate the influence of meteorological factors and gender, to assess the relationship between indoor and outdoor, and (3) to estimate the bacterial dose for university students in different indoor environments. Airborne bacteria samples were collected in 12 classrooms, in 12 living rooms and four bathrooms in two dormitory buildings, and in a dining hall. The results showed that the microenvironment in the female dormitory had the highest mean bacterial concentration (2847 CFU/m3), whereas the lowest mean bacterial concentration was observed in classrooms (162 CFU/m3). Indoor bacterial concentrations in male dormitories were significantly lower than in female dormitories probably because of crowding and increased ventilation. Outdoor weather conditions were associated with the indoor concentrations with regard to insufficient ventilation and varying outdoor concentration. The occupants' activity level was also more closely related to the indoor bacteria concentration in the residential setting. Students experienced about four times higher dose of airborne bacteria in the dormitories than in the classrooms and dining hall.

Partial physicochemical properties and relative stability of polyhydroxylated dibenzofurans: theoretical and experimental study.

Polyhydroxylated dibenzofuran (PHODF) is an important degradation product of polychlorinated dibenzofuran (PCDF). Four types of hydrogen bonds (the one between a hydroxyl and the oxygen atom in the matrix, between hydroxyls at ortho positions, between the oxygen atom of hydroxyl at position 1 and the hydrogen atom of the matrix at position 9, and between hydroxyls at positions 1 and 9) exist in PHODFs. The energies of the hydrogen bonds were ascertained by comparing the two configurational isomers as approximately 8-11 kJ mol⁻¹, 16-21 kJ mol⁻¹, 5-8 kJ mol⁻¹ and 23-25 kJ mol⁻¹, respectively. An experiment was designed to verify the bond energies, and the entrance geometry on main paths was studied by AIM 2000 program. The most stable in each group of configurational isomers was ascertained on the basis of evaluating the effect of hydrogen bonds. Their thermodynamic properties (standard state entropy S°, standard enthalpy Δ(f)H° and standard Gibbs energy of formation Δ(f)G°) were calculated from the combination of density functional theory (DFT) at B3LYP/6-311G** level and isodesmic reactions. Octanol/water partition coefficients (log K(ow)) were calculated on line with molinspiration methodology based on group contributions. The number and position of hydroxyl substitution (N(PHOS)) can be a good indicator of these properties for all stable PHODF congeners. The configurations most likely to form are those with a hydrogen bond (Type IV). How intramolecular hydrogen bond influences ionization was also investigated and the first-order ionization constant for each stable conformation was obtained with the self-consistent reaction field (SCRF) method.

2D and 3D-QSBR study on biodegradation of phenol derivatives.

Eighteen phenol derivatives were optimized with density function theory (DFT) and comparative molecular similarity indices analysis (CoMSIA) respectively. Corresponding 2D and 3D descriptors were obtained to establish QSBR models. The biodegradation of them is mainly related to α and S (Ó©) according to the 2D QSBR, and influenced by the hydrophobicity and hydrogen bonding properties following the 3D QSBR. The 2D model performs better in stability and predictive ability than the 3D one. To some degrees, the two models verify and supplement each other. They can be used in predicting biodegradation of chlorinated, amine, nitro, nitroso and methyl phenol.