The use of guided wave ultrasonography as a means to assess cortical bone quality has been a significant practice in bone quantitative ultrasound for more than 20 years. In this article, the key ...developments within the technology of ultrasonic guided waves (UGW) in long bones during the past decade are documented. The covered topics include data acquisition configurations available for measuring bone guided waveforms, signal processing techniques applied to bone UGW, numerical modeling of ultrasonic wave propagation in cortical long bones, formulation of inverse approaches to extract bone properties from observed ultrasonic signals, and clinical studies to establish the technology's application and efficacy. The review concludes by highlighting specific challenging problems and future research directions. In general, the primary purpose of this work is to provide a comprehensive overview of bone guided-wave ultrasound, especially for newcomers to this scientific field.
Noninvasive characterization of cortical long bones using axial transmission ultrasound is a promising diagnostic technology for osteoporotic cortical thinning assessment. However, the soft ...tissue-bone coupling effect remains to be a challenge and an ambiguity especially in vivo . The influence of the overlying soft tissue layer with a varying thickness on the propagation of ultrasonic guided waves in cortical bone is studied experimentally and theoretically in this article. The wave propagation is characterized based on waveform comparison, spectral density and decomposition, dispersion energy imaging, and particle displacement analysis. Good agreement between experimental observations with theoretical predictions by semi-analytical finite element simulations is observed. The sensitivity of propagation characteristics in response to the coupled tissue thickness is elucidated. As the thickness of the loading soft tissue grows, the guided wave signals exhibit greater attenuated amplitude and delayed arrival time; more complex dispersive wave patterns emerge; and the modal number and density increase. The research findings advance the fundamental comprehension of ultrasonic-guided-wave excitation and interaction in long bones and facilitate further technical development and clinical utility of quantitative guided-wave ultrasonography in routine healthcare services as a nondestructive imaging modality for cortical bone examination.
In this study, a nonlinear grid-search inversion has been developed to estimate the thickness and elastic velocities of long cortical bones, which are important determinants of bone strength, from ...axially-transmitted ultrasonic data. The inversion scheme is formulated in the dispersive frequency-phase velocity domain to recover bone properties. The method uses ultrasonic guided waves to retrieve overlying soft tissue thickness, cortical thickness, compressional, and shear-wave velocities of the cortex. The inversion strategy requires systematic examination of a large set of trial dispersion-curve solutions within a pre-defined model space to match the data with minimum cost in a least-squares sense. The theoretical dispersion curves required to solve the inverse problem are computed for bilayered bone models using a semi-analytical finite-element method. The feasibility of the proposed approach was demonstrated by the numerically simulated data for a 1 mm soft tissue-5 mm bone bilayer and
ex-vivo
data from a bovine femur plate with an overlying 2 mm-thick soft-tissue mimic. The bootstrap method was employed to evaluate the inversion uncertainty and stability. Our results have shown that the cortical thickness and wave speeds could be recovered with fair accuracy.
Vietnam is among 11 countries in the Western Pacific region that has developed a National Action Plan for Antimicrobial Resistance (NAPCA).
This scoping review characterises health system barriers to ...the implementation of the Vietnam NAPCA, with reference to the WHO Health Systems Framework.
Over 7 years, between 2013 and 2020, the Ministry of Health (MOH) of Vietnam has been implementing activities to achieve the six NAPCA objectives. They include revision of regulations needed for antimicrobial resistance (AMR) prevention programs; formation and operation of national management bodies; improvement of antimicrobial stewardship (AMS) in hospitals; maintenance of surveillance systems for AMR; provision of trainings on AMR and antibiotics use to doctors and pharmacists; and organization of nation-wide educational campaigns. Limited cooperation between MOH management bodies, shortages of human resource at all health system levels, a low degree of agreement between national and hospital guidelines on antibiotic use, low capability in the domestic supply of standardised drugs, and unequal training opportunities for lower-level health professionals present ongoing challenges. Actions suggested for the next period of the NAPCA include a final review of what has been achieved by the plan so far and evaluating the effectiveness of the different components of the plan. Different options on how to improve coordination across sectors in the development of a new NAPCA should be put forward.
The 6-year implementation of the Vietnam NAPCA has yielded valuable lessons for AMS in Vietnam, guiding the development of future national plans, with a central focus on scaling up AMS in hospitals and promoting community AMS programs to combat AMR.
The fundamental ultrasonic guided modes are consistently observed in long bones ex vivo and in vivo. However, the responses of ultrasonic guided waves to the changes of cortical thickness, cortical ...elastic parameters, and thickness of the overlying soft tissues are not comprehensively understood. This paper systematically presents a sensitivity analysis of leaky Lamb modes to the geometry and material characteristics of layered bone model by means of semi-analytical finite element modeling. The stratified bone model is consisted of a transversely isotropic cortex with an overlying soft tissue and underlying marrow. The study is important as it offers guidance to the parameter inversion process about the optimal selection of guided modes and regions of sensitivity for better inversion results.
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•Based on spectroscopic analysis, the chemical structure of two new acridones and two new coumarins were elucidated.•The α-glucosidase inhibitory activity of isolated compounds were ...evaluated.•The plausible biosynthetic pathways of cyclized geranyl acridones and coumarins were proposed.
Two acridones, paratrimerins C (1) and D (2), and two coumarins, paratrimerins E (3) and F (4), were isolated from the CHCl3 and EtOAc extracts of Paramignya trimera (Rutaceae), together with twelve known compounds (5–16). Their structures were elucidated on the basis of spectroscopic data. All isolated compounds possessed significant α-glucosidase inhibitory activity in a concentration-dependent manner, and showed more potent inhibitory activity, with IC50 values ranging from 14.6 to 112.2μM, than the positive control acarbose (IC50, 214.5μM). The biosynthesis of the isolated coumarins and acridones was proposed.
From an EtOAc-soluble extract of the roots of Taxus wallichiana, six new (1–6) and 11 known lignans were isolated. The structures of the new compounds were elucidated based on interpretation of ...spectroscopic data. (+)-7′-epi-Tsugacetal (1) is a rare aryltetralin-type lignan having a cis-orientation of H-7′ and H-8′. Compounds 3–6 were identified as the first naturally occurring tetrahydrofuranoid lignans having a cis-orientation of H-7 and H-8. All tested compounds were found to possess α-glucosidase inhibitory activity, with formosanol (9) showing the most potent effect with an IC50 value of 35.3 μM.
A methanolic extract of the rhizomes of Boesenbergia rotunda showed potent preferential cytotoxicity against PANC-1 human pancreatic cancer cells under nutrient deficiency conditions with a PC50 ...value of 6.6 μg/mL. Bioactivity-guided phytochemical investigation of the rhizomes of B. rotunda led to the isolation of nine undescribed dimeric metabolites, panduratins Q–Y. Their structures were elucidated based on NMR, MS, and ECD spectroscopic data interpretation. Panduratins Q–S and U–W exhibited potent cytotoxicity towards PANC-1 cell line with the PC50 values ranging from 0.8 to 6.3 μM. Panduratin W, which possessed a cyclohexenylchalcone-linked flavanone skeleton, showed the most cytotoxicity with a PC50 value of 0.8 μM under nutrient-deprived medium.
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•Chemical structures of nine undescribed dimeric metabolites were elucidated.•Preferential cytotoxicity against PANC-1 cells of all isolated compounds were tested.•Panduratin W showed the most preferential cytotoxicity against PANC-1 cells.
BackgroundRotavirus disease causes a significant health and economic burden worldwide. Several rotavirus vaccines may soon be available for use. A country’s decision to introduce these vaccines will ...depend on its rotavirus disease burden, on the cost of the vaccine, and on the results of an economic assessment of the cost and effectiveness of a rotavirus vaccination program MethodsData on medical and nonmedical direct costs and indirect costs were established in Khanh Hoa Province, Vietnam, and extrapolated to national estimates on the basis of the birth cohort in 2004. The main outcome measures were economic burden and cost-effectiveness ratio (United States dollars per disability-adjusted life-year averted and dollars per life saved) of vaccination ResultsThe disease burden is equivalent to an economic burden of an estimated $3.1 million in medical direct costs, $685,000 in nonmedical direct costs, and $1.5 million in indirect costs. From a societal perspective, treatment of rotavirus disease costs an estimated $5.3 million per year. From the health care system perspective, universal vaccination of infants at a cost of ⩽$7.26/vaccine dose would be a cost-effective public health intervention, according to the World Bank cost-effectiveness standard for low-income countries ($140/disability-adjusted life-year) ConclusionsVaccination can effectively reduce the disease burden and health care costs of rotavirus-specific diarrhea in Vietnam
Two new stilbene derivatives, named strebluses C and D, were isolated from the EtOAc-soluble fraction of the stems of Streblus ilicifolius (Moraceae). Its absolute configuration was elucidated based ...on NMR spectroscopic data interpretation and optical rotation calculation. Streblus C possesses strong tyrosinase inhibitory activity with an IC50 value of 0.01 μM. Docking studies of 1 and 2 with oxy-tyrosinase were carried out to analyze their interactions. The analysis of the docked poses confirmed that 1 showed better binding affinity for oxy-tyrosinase than that of 2.
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