Validity of height loss as a predictor for prevalent vertebral fractures, low bone mineral density, and vitamin D deficiency.

Many osteoporosis-related vertebral fractures are unappreciated but their detection is important as their presence increases future fracture risk. We found height loss is a useful tool in detecting patients with vertebral fractures, low bone mineral density, and vitamin D deficiency which may lead to improvements in patient care. INTRODUCTION: This study aimed to determine if/how height loss can be used to identify patients with vertebral fractures, low bone mineral density, and vitamin D deficiency. METHODS: A hospital database search in which four patient groups including those with a diagnosis of osteoporosis-related vertebral fracture, osteoporosis, osteopenia, or vitamin D deficiency and a control group were evaluated for chart-documented height loss over an average 3 1/2 to 4-year time period. Data was retrieved from 66,021 patients (25,792 men and 40,229 women). RESULTS: A height loss of 1, 2, 3, and 4 cm had a sensitivity of 42, 32, 19, and 14% in detecting vertebral fractures, respectively. Positive likelihood ratios for detecting vertebral fractures were 1.73, 2.35, and 2.89 at 2, 3, and 4 cm of height loss, respectively. Height loss had lower sensitivities and positive likelihood ratios for detecting low bone mineral density and vitamin D deficiency compared to vertebral fractures. Specificity of 1, 2, 3, and 4 cm of height loss was 70, 82, 92, and 95%, respectively. The odds ratios for a patient who loses 1 cm of height being in one of the four diagnostic groups compared to a patient who loses no height was higher for younger and male patients. CONCLUSIONS: This study demonstrated that prospective height loss is an effective tool to identify patients with vertebral fractures, low bone mineral density, and vitamin D deficiency although a lack of height loss does not rule out these diagnoses. If significant height loss is present, the high positive likelihood ratios support a further workup.

Clinical height measurements are unreliable: a call for improvement.

UNLABELLED: Height measurements are currently used to guide imaging decisions that assist in osteoporosis care, but their clinical reliability is largely unknown. We found both clinical height measurements and electronic health record height data to be unreliable. Improvement in height measurement is needed to improve osteoporosis care. INTRODUCTION: The aim of this study is to assess the accuracy and reliability of clinical height measurement in a university healthcare clinical setting. METHODS: Electronic health record (EHR) review, direct measurement of clinical stadiometer accuracy, and observation of staff height measurement technique at outpatient facilities of the University of Wisconsin Hospital and Clinics. We examined 32 clinical stadiometers for reliability and observed 34 clinic staff perform height measurements at 12 outpatient primary care and specialty clinics. An EHR search identified 4711 men and women age 43 to 89 with no known metabolic bone disease who had more than one height measurement over 3 months. The short study period and exclusion were selected to evaluate change in recorded height not due to pathologic processes. RESULTS: Mean EHR recorded height change (first to last measurement) was -0.02 cm (SD 1.88 cm). Eighteen percent of patients had height measurement differences noted in the EHR of ≥2 cm over 3 months. The technical error of measurement (TEM) was 1.77 cm with a relative TEM of 1.04 %. None of the staff observed performing height measurements followed all recommended height measurement guidelines. Fifty percent of clinic staff reported they on occasion enter patient reported height into the EHR rather than performing a measurement. When performing direct measurements on stadiometers, the mean difference from a gold standard length was 0.24 cm (SD 0.80). Nine percent of stadiometers examined had an error of >1.5 cm. CONCLUSIONS: Clinical height measurements and EHR recorded height results are unreliable. Improvement in this measure is needed as an adjunct to improve osteoporosis care.

Periodic model of LTA framework containing various non-tetrahedral cations.

A simplified periodic model of Linde Type A zeolite (LTA) structure with various selected mono- and di-valent extra-framework cations was formulated. Ab initio calculations (geometry optimization and vibrational spectra calculations) using the proposed model were carried out by means of Crystal09 program. The resulting structures and simulated spectra were analyzed in detail and compared with the experimental ones. The presented results show that in most cases the proposed model agrees well with experimental results. Individual bands were assigned to respective normal modes of vibration and the changes resulting from the selective substitution of extra framework cations were described and explained.

Periodic model of an LTA framework.

Zeolites are a group of microporous aluminosilicate frameworks with numerous applications in, for example, catalysis and ion-exchange and sorption processes. One of the most important tools for analyzing the properties of zeolite structures is vibrational spectroscopy. However, the complexity of these structures often leads to difficulties when attempting to interpret the resulting spectra, so an additional complementary tool is required: computational methods. The aim of this study was to formulate a simplified periodic model of an LTA framework containing alkali metal cations (either Li(+), Na(+), K(+), Rb(+), or Cs(+)) and to perform a set of ab initio calculations aimed at assessing the influence of these cations on the properties of the vibrational spectra of the LTA framework. Additionally, chemical bonding was analyzed by means of electron density topology analysis. Results obtained were compared with experimental spectra for alkali metal forms of zeolite A. It was found that the vibrational spectra obtained using the proposed model agree well with the corresponding experimentally derived spectra, meaning that the model can be used to analyze real spectra in detail.

The influence of the long-range order on the vibrational spectra of structures based on sodalite cage.

Zeolites are a group of tecto-aluminosilicates with numerous practical applications, e.g. gas separators, molecular sieves and sorbents. The unique properties result from porous structure of channels and cages which are built from smaller units - the so-called Secondary Building Units (SBU), and sometimes also larger groups (Breck, 1974; Ciciszwili et al., 1974; Mozgawa, 2008; Cejka and van Bekkum, 2005). The aim of this study was the examination of the influence of long-range order on vibrational spectra of sodalite and zeolite A. Ab initio calculations (geometry optimizations and vibrational spectra calculations) of sodalite cage and selected SBU were carried out by means of Gaussian09 (Frisch et al., 2009) (in the case of isolated clusters) and Crystal09 (Dovesi et al., 2005, 2009) (for periodic structures). The obtained results were compared with the experimental spectra of sodalite and zeolite A crystal structures, synthesized under hydrothermal conditions. These results allowed analyzing of the long-range ordering influence on the vibrational spectra, as well as the identification of the characteristic vibrations in ß cage based frameworks. It has been found, that based on small structural fragment (SBU) models a characteristic vibrations can be identify. However, full spectra analysis and especially the interpretation of far-infrared region of the spectra require using periodic models under the influence of translational crystal lattice.

Thermodynamic investigations of ternary liquid alloys.

A review of different methods for determining thermodynamic quantities is given. The electromotive force (EMF) method with a liquid and solid electrolyte, the calorimetric and differential scanning calorimetry (DSC) methods, and vapour pressure experiments like the isopiestic and Knudsen effusion methods are discussed.

Ultrastructure of Gentiana tibetica proembryogenic cells before and after cooling treatments.

The influence of increased concentrations of sucrose, 0.4 M sorbitol, DMSO and vitrification solution (PVS2) on the ultrastructure of non-frozen and frozen suspensions of Gentiana tibetica King ex Hook. F.tissue cells was investigated. Embryogenic aggregates were composed of three groups of cells of different size with various types of plastids. The ultrastructural changes resulting from increasing the sucrose concentration in the medium from 3 to 6 percent for 4 weeks and from treatment with 0.4 M sorbitol for 48 h were similar. Observations showed replacement of large vacuoles by numerous small ones, condensation of cytoplasm, accumulation of starch, and fragmentation of endoplasmic reticulum. Treatment with PVS2 led to degradation of starch, coalescence of amyloplasts and to shrinking of nucleoli from the third group of cells when originating from 6 percent sucrose medium. The mitochondria initially had various shapes, but after PVS2 treatment showed only spherical shapes with sparse cristae. After programmed freezing of tissue protected by sorbitol and DMSO, lethal damage was observed: membrane and nuclei degradation, and cell destruction. Reversible changes after freezing were observed in tissue pretreated with vitrification solution: dilation of cell membranes, mitochondria with electron-lucent vessels, aggregation of numerous vesicles, and degradation of starch in amyloplasts. In cells cooled by a vitrification method, cell organelles appeared normal as early as 5 h after thawing, and anomalies were not observed after 48 h of post-thawing culture.

Whole-genome comparison of Mycobacterium tuberculosis clinical and laboratory strains.

Virulence and immunity are poorly understood in Mycobacterium tuberculosis. We sequenced the complete genome of the M. tuberculosis clinical strain CDC1551 and performed a whole-genome comparison with the laboratory strain H37Rv in order to identify polymorphic sequences with potential relevance to disease pathogenesis, immunity, and evolution. We found large-sequence and single-nucleotide polymorphisms in numerous genes. Polymorphic loci included a phospholipase C, a membrane lipoprotein, members of an adenylate cyclase gene family, and members of the PE/PPE gene family, some of which have been implicated in virulence or the host immune response. Several gene families, including the PE/PPE gene family, also had significantly higher synonymous and nonsynonymous substitution frequencies compared to the genome as a whole. We tested a large sample of M. tuberculosis clinical isolates for a subset of the large-sequence and single-nucleotide polymorphisms and found widespread genetic variability at many of these loci. We performed phylogenetic and epidemiological analysis to investigate the evolutionary relationships among isolates and the origins of specific polymorphic loci. A number of these polymorphisms appear to have occurred multiple times as independent events, suggesting that these changes may be under selective pressure. Together, these results demonstrate that polymorphisms among M. tuberculosis strains are more extensive than initially anticipated, and genetic variation may have an important role in disease pathogenesis and immunity.