Self-powered, light-controlled, bioresorbable platforms for programmed drug delivery.

Degradable polymer matrices and porous scaffolds provide powerful mechanisms for passive, sustained release of drugs relevant to the treatment of a broad range of diseases and conditions. Growing interest is in active control of pharmacokinetics tailored to the needs of the patient via programmable engineering platforms that include power sources, delivery mechanisms, communication hardware, and associated electronics, most typically in forms that require surgical extraction after a period of use. Here we report a light-controlled, self-powered technology that bypasses key disadvantages of these systems, in an overall design that is bioresorbable. Programmability relies on the use of an external light source to illuminate an implanted, wavelength-sensitive phototransistor to trigger a short circuit in an electrochemical cell structure that includes a metal gate valve as its anode. Consequent electrochemical corrosion eliminates the gate, thereby opening an underlying reservoir to release a dose of drugs by passive diffusion into surrounding tissue. A wavelength-division multiplexing strategy allows release to be programmed from any one or any arbitrary combination of a collection of reservoirs built into an integrated device. Studies of various bioresorbable electrode materials define the key considerations and guide optimized choices in designs. In vivo demonstrations of programmed release of lidocaine adjacent the sciatic nerves in rat models illustrate the functionality in the context of pain management, an essential aspect of patient care that could benefit from the results presented here.

Advances in Bioresorbable Materials and Electronics.

Transient electronic systems represent an emerging class of technology that is defined by an ability to fully or partially dissolve, disintegrate, or otherwise disappear at controlled rates or triggered times through engineered chemical or physical processes after a required period of operation. This review highlights recent advances in materials chemistry that serve as the foundations for a subclass of transient electronics, bioresorbable electronics, that is characterized by an ability to resorb (or, equivalently, to absorb) in a biological environment. The primary use cases are in systems designed to insert into the human body, to provide sensing and/or therapeutic functions for timeframes aligned with natural biological processes. Mechanisms of bioresorption then harmlessly eliminate the devices, and their associated load on and risk to the patient, without the need of secondary removal surgeries. The core content focuses on the chemistry of the enabling electronic materials, spanning organic and inorganic compounds to hybrids and composites, along with their mechanisms of chemical reaction in biological environments. Following discussions highlight the use of these materials in bioresorbable electronic components, sensors, power supplies, and in integrated diagnostic and therapeutic systems formed using specialized methods for fabrication and assembly. A concluding section summarizes opportunities for future research.

Optimal intersurface stability for unicompartmental femoral component design with two pegs placed on the distal resection surface: 5 mm peg length increment and 10° peg inclination.

PURPOSE: The present study aimed to identify the optimal design of the unicompartmental femoral component through parameter analysis and stability evaluation. METHODS: A finite element (FE) analysis was applied to analyse and adjust the parameter combinations of the anterior tilt angle of the posterior condyle resection surface, the position of the peg, the length of the peg and the inclination angle of the peg, resulting in 10 different FE models. Setting three knee flexion angles of 8.4° (maximum load state during walking), 40° (maximum load state during stair climbing) and 90° (maximum load state during squatting exercise), quantitatively analysing the micromotion values of the bone-prosthesis interface and defining a weighted scoring formula to evaluate the stability of different FE models. The validity of the FE analysis was verified using the Digital Image Correlation (DIC) device. RESULTS: The errors between the FE analysis and the DIC test at three flexion angles were 5.6%, 1.7% and 11.1%. The 10 different femoral component design models were measured separately. The FE analysis demonstrated that the design with a 0° anterior tilt angle of the posterior condyle resection surface, both pegs placed on the distal resection surface, lengthened 5 mm pegs and a 10° peg inclination angle provided the best stability. CONCLUSION: The current study proposed a method for evaluating the stability of the femoral component design. The optimal intersurface stability design of the unicompartmental femoral component was achieved with two pegs placed on the distal resection surface, a 5-mm peg length increment and a 10° peg inclination. These results might provide a reference for the selection of unicompartmental femoral components in clinical practice and therefore improve the survival rate of future unicompartmental knee arthroplasty. LEVEL OF EVIDENCE: Level III.

Clinical value of spectral CT in diagnosis of negative gallstones and common bile duct stones.

OBJECTIVE: To investigate the clinical value of spectral CT in diagnosis of negative gallstones and common bile duct stones primarily. METHODS: All patients diagnosed with negative biliary stones were analyzed and examined by spectral CT scanner retrospectively. Based on acquired raw imaging data, image series were reconstructed as described below: the optimal contrast-to-noise ratio monochromatic energy images, calcium- and fat- based material decomposition images and spectral curve images. All these imaging series were analyzed quantitatively and qualitatively. RESULTS: The contrast between negative stones and adjacent bile was 6.87 ± 5.48 HU on hybrid energy CT images and 47.30 ± 24.05 HU on optimal monochromatic energy CT images. The mean concentration of calcium in bile and negative stones was 19.36 ± 5.12 and 3.88 ± 6.60 mg/mL, and the fat in bile and negative stones was 998.48 ± 11.79 and 1035.68 ± 15.36 mg/mL. Effective atomic number Z of negative stones (6.60 ± 0.45) was lower than that of bile (7.65 ± 0.13). The slopes of the spectral curves for negative stones were k 90-40KeV = 1.43 ± 0.63 and k 140-90KeV = 0.19 ± 0.08, and for bile, they were k 90-40KeV = -0.27 ± 0.09 and k 140-90KeV = -0.04 ± 0.01. The same stone showed different densities in different imaging groups. The positive rate of conventional CT images was lower than that of other imaging groups. CONCLUSION: Spectral CT has a high diagnostic value for negative gallstones or bile duct stones, and material decomposition CT images and spectral curves can make an accurate diagnosis.

[Magnetic resonance imaging study of disc low back pain].

OBJECTIVE: To study the diagnostic value of disc low back pain (DLBP) with lumbar disc high-intensity zone on magnetic resonance imaging (MRI) . METHODS: The 21 patients of pare examination with MRI and CT discography (CTD) must have chronic low back pain without radicular pain and with no disc herniation on the CT or MRI. We have worked out the standard of CTD group and positive disc. The sensitivity, specificity and positive predictive value that the positive disc was diagnosed with MRI was used for statistical analysis in SPSS 15.0. RESULTS: MRI showed 28 abnormal signal discs in 21 patients, including the high-intensity zone of posterior annulus in 12 discs and later- posterior annulus in 3 discs and discs degeneration in other 13 discs. The results of pare examination with MRI and CTD to 28 abnormal signal discs and 5 normal signal discs was (1)MRI showed the high-intensity zone of poster annulus in 12 discs and later- poster annulus in 2 discs and discs degeneration in 5 discs, while CTD showed 19 discs for group 2 with all positive discs. The shape of high-intensity zone showed on MRI was showed no difference with the shape of contrast agent collected under periphery disc on CTD. (2) MRI showed another high-intensity zone of later- poster annulus in 3 discs, while CTD showed one disc for group 5 with positive. (3) MRI showed the discs degeneration, while CTD showed 7 discs for group 3 with negative discs. (4) MRI showed 1 disc degeneration and 5 normal discs, while CTD showed 6 discs for group 1 with negative discs. (5)The sensitivity of diagnosis positive discs was 75%, the specificity and positive predictive value was respectively 100% with MRI. CONCLUSIONS: The high-intensity zone of poster/later- poster annulus on MRI was typical sign of disc disruption and the important clinical role for diagnosing disc low back pain.

Value of High-Resolution MRI in the Diagnosis of Brachial Plexus Injury in Infants and Young Children.

Purpose: To investigate the value of high-resolution MRI based on 3D-short inversion time inversion recovery sampling perfection with application-optimized contrasts (3D-STIR SPACE) sequence for the diagnosis of brachial plexus injury in infants and young children. Methods: Physical examination, electromyography (EMG) and MRI data of 26 children with brachial plexus injury were retrospectively analyzed. Sensitivity, specificity, and accuracy were calculated for the three tests. The agreement among these examinations was analyzed with the Kappa test. P<0.05 was considered statistically significant. Results: Of the 26 children, 3 cases had normal MRIs, 23 cases had unilateral brachial plexus injury diagnosed with MRI, and a total of 73 nerve roots and/or sheaths were involved. Among the 23 cases with aberrant MRI findings, there were 19 cases of nerve root thickening (42 nerve roots), 4 cases of nerve root sleeve expansion (5 nerve roots), 17 cases of pseudomeningeal cysts (34 nerve roots), 2 cases of nerve root loosening (2 nerve roots), 8 cases of nerve root dissection (11 nerve roots), 19 cases with increased nerve signal (43 nerve roots), and 9 cases with an increased signal of the muscles on the affected side. As for the diagnosis of brachial plexus injury, the sensitivity and the accuracy of physical examination, EMG and MRI were 0.92, 0.86, and 0.88, respectively. The agreement between MRI and physical examination was substantial (κ=0.780, P=0.000), as did the agreement between MRI and EMG (κ=0.611, P=0.005). Conclusion: High-resolution MRI based on 3D-STIR SPACE sequence plays a role in the diagnosis and evaluation of brachial plexus injury in infants and young children. It can accurately identify the injured nerve and characterize related pathological alterations. Besides EMG and physical examination, it can be used as a valuable tool for screening and monitoring of brachial plexus injury in infants and children.

Volumetric properties of disodium dihydrogen pyrophosphate aqueous solution from 283.15 to 363.15 K at 101.325 kPa.

The purpose of this exploration was to determine the density and volumetric properties of the aqueous solution of Na2H2P2O7 with the molality varied from 0.08706 to 0.88402 mol·kg-1 measured at temperature intervals of 5 K from 283.15 to 363.15 K at 101.325 kPa using Anton Paar Digital vibrating-tube densimeter. The thermal expansion coefficient (α), apparent molar volume (VΦ), expansibility (ϕE), and partial molar volume (VB) of Na2H2P2O7 (aq) against temperature and molality have been evaluated from density data. On the basis of Pitzer ion-interaction apparent molar volume theory, the Pitzer single-salt parameters (ßM,X0v, ßM,X1v, ßM,X2v and CM,Xv, MX = Na2H2P2O7), and their correlation coefficients ai of the temperature-dependence formula f (i, p, T) = a1 + a2ln(T/298.15) + a3(T - 298.15) + a4/(620 - T) + a5/(T - 227) for Na2H2P2O7 were obtained for the first time. It was revealed that predicted apparent molar volumes agreed well with the experimental values indicating the single salt parameters and the temperature-dependent formula are reliable.

Risk Factors for Different Grades of Lower Respiratory Tract Infections in Children Under Five Years Old with Measles: Based on Chest Radiography.

BACKGROUND: Although measles epidemic has been controlled effectively after measles vaccination being carried out, China is still the focus of measles epidemic. The lower respiratory tract infections (LRTIs) is the most common complication, and also the most common reason for the death of patients with measles. PURPOSE: To analyze what clinical factors could affect the grades of LRTIs in children under five years old with measles. METHODS: Patients' 13 clinical factors and chest radiography were analyzed retrospectively. Based on the chest radiography, the LRTIs were divided into 3 grades. The clinical factors and the grades of LRTIs were analyzed by ordered logistic regression analysis. RESULTS: There were 74 cases in grade 0, 77 cases in grade 1, and 36 cases in grade 2. After univariate logistic regression analysis, there were 5 clinical factors whose P value were no more than 0.1, including the children's course of disease before admission, co-infection other pathogens, vaccination, the first symptoms and gender. After ordinal logistic regression analysis, the difference in the course of disease before admission (OR = 1.134, 95% CI: 1.025 to 1.141), without vaccination (OR = 1.808, 95% CI: 1.065 to 3.065) and co-infected other pathogens other pathogens infections (OR = 1.618, 95% CI: 1.073 to 2.440) during different grades was statistically significant (P < 0.05). CONCLUSION: In our study, there were three clinical factors, including "with a long course of disease before admission", "without measles vaccination" and "with other pathogens infections", as the independent risk factors of the grades of LRTIs in children with measles.