Bone-specific physical activity questionnaire-derived skeletal loading score predicts bone geometry, density, and strength indices: a cross-sectional study.

INTRODUCTION: The bone-specific physical activity questionnaire (BPAQ) provides a bone-relevant index of physical activity participation according to the mechanical loads experienced across the life span. MATERIALS AND METHODS: We aimed to examine relationships between historical bone-relevant physical activity and pQCT-derived parameters of bone strength. We recruited 532 healthy volunteers (277 males, 255 females) across a broad age range (4-97 years). Peripheral quantitative computed tomography (XCT-3000, Stratec, Germany) was used to examine volumetric bone density, area, and strength indices of the non-dominant tibia and radius. Exercise loading history from birth was determined using the past BPAQ (pBPAQ) score. Pearson correlation analysis was used to examine relationships between pBPAQ scores and pQCT parameters. RESULTS: Independent of sex, pBPAQ scores were associated with total density at the 38% and 66% tibial sites and the 66% radial site (r = 0.145-0.261, p ˂ 0.05), total area at the 38% tibial site and 4% and 66% radial sites (r = 0.129-0.156, p ˂ 0.05), and strength indices at all measured sites (r = 0.123-0.234, p < 0.05). CONCLUSION: We conclude that, independent of sex, historical bone-relevant physical activity is associated with pQCT-derived indices of bone strength, indicating that pBPAQ captures the characteristics of bone loading history that are likely to be relevant adaptive stimuli. A larger sample is required to examine the influence of age on this relationship.

Influence of Metal Identity in Bipyridine-Based Metal-4N Complexes With Formate.

We present the vibrational spectra of a series of dicationic, organometallic complexes consisting of a transition metal center (Co, Ni, or Cu) coordinated by 4,4'-di(tert-butyl)-2,2'-bipyridine (DTBbpy) ligands and a formate adduct. Spectral features are analyzed and assigned through comparison with density functional theory calculations, and structures are reported. Natural population analysis shows that the DTBbpy ligands serve as flexible charge reservoirs in each complex. Shifts in the vibrational signatures of the formate moiety reveal that the nature of the metal center plays a crucial role in the charge distribution and formate-metal binding motif in each complex, illustrating the impact of the metal center on the structural and electronic properties of these complexes.

Effects of Formate Binding to a Bipyridine-Based Cobalt-4N Complex.

We report the vibrational spectrum of a metal-organic complex consisting of a Co center surrounded by two bipyridine-based ligands and explore the change of the spectrum upon addition of a formate ligand to the complex. We assign the spectra using density functional theory. The infrared response encodes the binding motif of the formate to the metal, and the calculated charge distributions highlight the ability of the organic ligand framework to act as charge reservoirs modulating the redox properties of the metal center.

Synthesis and characterization of tritylthioethanamine derivatives with potent KSP inhibitory activity.

Assembly of a bipolar mitotic spindle requires the action of class 5 kinesins, and inhibition or depletion of this motor results in mitotic arrest and apoptosis. S-Trityl-l-cysteine is an allosteric inhibitor of vertebrate Kinesin Spindle Protein (KSP) that has generated considerable interest due to its anti-cancer properties, however, poor pharmacological properties have limited the use of this compound. We have modified the triphenylmethyl and cysteine groups, guided by biochemical and cell-based assays, to yield new cysteinol and cysteamine derivatives with increased inhibitory activity, greater efficacy in model systems, and significantly enhanced potency against the NCI60 tumor panel. These results reveal a promising new class of conformationally-flexible small molecules as allosteric KSP inhibitors for use as research tools, with activities that provide impetus for further development as anti-tumor agents.

Lessons From a Quality Improvement Project to Standardize the Process of Gastric Biopsy Culture for Helicobacter pylori.

Despite expert recommendations, clinician's adherence to pediatric societal clinical practice guidelines is variable, particularly with respect to the use of gastric biopsy culture in the initial diagnosis of Helicobacter pylori infection. In addition, the implementation of routine use of gastric biopsy culture has been challenging with several factors affecting the rate of successful primary H pylori culture. Methods: We conducted a quality improvement (QI) project with the aims of increasing the rate of successful primary culture. The QI project involved educational efforts among our gastroenterologists, endoscopy suite personnel, and laboratory personnel. We compared the frequency of gastric biopsy culture sent in patients with international classification of diseases 9th revision code 041.86, and 10th revision codes B96.81 evaluated by pediatric gastroenterologists at Boston Children's Hospital during the 9 months before the QI intervention (February 1, 2019 to October 31, 2019) and 9 months after the QI intervention (November 1 2019 to July 31 2020). We also compared the rate of culture growth in patients with positive histology (culture positivity), and antimicrobial susceptibilities before and after November 1, 2019. Results: We observed an increased frequency of gastric biopsy acquisition by any gastroenterologist, obtained in 39% (28 of 71) preintervention patients compared with 67% (36 of 54) intervention patients (P = 0.004). There was an increase in the percentage of culture positivity across study periods from 21% (3 of 14) preintervention to 45% (5 of 11) postintervention (P = 0.39; 95% confidence interval, 0.64-7.00). Conclusion: Educational initiatives and collaborative work with staff physicians, endoscopy personnel, and hospital laboratory appear to be effective tools to increase usage of gastric biopsy culture as a diagnostic tool for H pylori infection and to increase culture positivity. Improving the surveillance of local resistance rates will improve the selection of the most effective primary treatment in specific geographic areas.

Measuring Photoexcited Free Charge Carriers in Mono- to Few-Layer Transition-Metal Dichalcogenides with Steady-State Microwave Conductivity.

Photoinduced generation of mobile charge carriers is the fundamental process underlying many applications, such as solar energy harvesting, solar fuel production, and efficient photodetectors. Monolayer transition-metal dichalcogenides (TMDCs) are an attractive model system for studying photoinduced carrier generation mechanisms in low-dimensional materials because they possess strong direct band gap absorption, large exciton binding energies, and are only a few atoms thick. While a number of studies have observed charge generation in neat TMDCs for photoexcitation at, above, or even below the optical band gap, the role of nonlinear processes (resulting from high photon fluences), defect states, excess charges, and layer interactions remains unclear. In this study, we introduce steady-state microwave conductivity (SSMC) spectroscopy for measuring charge generation action spectra in a model WS2 mono- to few-layer TMDC system at fluences that coincide with the terrestrial solar flux. Despite utilizing photon fluences well below those used in previous pump-probe measurements, the SSMC technique is sensitive enough to easily resolve the photoconductivity spectrum arising in mono- to few-layer WS2. By correlating SSMC with other spectroscopy and microscopy experiments, we find that photoconductivity is observed predominantly for excitation wavelengths resonant with the excitonic transition of the multilayer portions of the sample, the density of which can be controlled by the synthesis conditions. These results highlight the potential of layer engineering as a route toward achieving high yields of photoinduced charge carriers in neat TMDCs, with implications for a broad range of optoelectronic applications.

Geometric constraints during epithelial jamming.

As an injury heals, an embryo develops, or a carcinoma spreads, epithelial cells systematically change their shape. In each of these processes cell shape is studied extensively whereas variability of shape from cell-to-cell is regarded most often as biological noise. But where do cell shape and its variability come from? Here we report that cell shape and shape variability are mutually constrained through a relationship that is purely geometrical. That relationship is shown to govern processes as diverse as maturation of the pseudostratified bronchial epithelial layer cultured from non-asthmatic or asthmatic donors, and formation of the ventral furrow in the Drosophila embryo. Across these and other epithelial systems, shape variability collapses to a family of distributions that is common to all. That distribution, in turn, is accounted for by a mechanistic theory of cell-cell interaction showing that cell shape becomes progressively less elongated and less variable as the layer becomes progressively more jammed. These findings suggest a connection between jamming and geometry that spans living organisms and inert jammed systems, and thus transcends system details. Although molecular events are needed for any complete theory of cell shape and cell packing, observations point to the hypothesis that jamming behavior at larger scales of organization sets overriding geometrical constraints.

Proponen una herramienta útil para analizar los efectos de la actividad física a nivel óseo / A useful tool for analysing the effects of bone-specific physical activity

La escala Bone-specific Physical Activity Questionnaire (BPAQ) fue diseñada expresamente para rastrear la actividad física osteogénica llevada a cabo en el pasado. Se elaboraron algoritmos que otorgan un puntaje a las respuestas del cuestionario con el fin de registrar los parámetros específicos de actividad física que generan la adaptación ósea. Dichos puntajes fueron considerados de acuerdo con la edad y la duración de la participación con el objetivo de identificar las diferencias específicas según la edad en la respuesta esquelética a la carga mecánica. Se creó un calculador informático de libre acceso para simplificar el procesamiento de información y generar puntajes de actividad previa, actual y total. Con anterioridad, demostramos que los puntajes de la escala BPAQ son capaces de predecir la varianza en parámetros de masa ósea de adultos jóvenes sanos, donde otras herramientas convencionales de medición de la actividad física no logran hacerlo. Recientemente, nuestro grupo determinó puntajes promedio de la escala BPAQ para hombres y mujeres a lo largo de la vida y evaluó la confiabilidad de sus mediciones. En el presente artículo, informamos estos hallazgos. Específicamente, presentamos la información sobre la confiabilidad interoperador e intraoperador y los valores promedio del cuestionario para hombres y mujeres en grupos etarios divididos cada 10 años desde los 5 hasta los 83 años.