An in-depth look at pressure sores using monolithic silicon pressure sensors

Three-dimensional scalar pressure distributions were measured in solid tissue near bony prominences in vitro in meat and in vivo in pigs using silicon pressure sensors. Data are in accord with previous theoretical models and indicate that pressure is three to five times higher internally near a bony prominence than it is at the skin over the prominence. Pressure sores are thus thought to begin internally; by the time they are evident at the skin, the sore has worked its way completely from bone to skin. This conclusion is in accord with previous clinical data. Future measurement of local vector forces is needed to fully characterize the force distribution in vivo.     

Interaction between bovine trypsin and a synthetic peptide containing 28 residues of the bait region of human alpha 2-macroglobulin.

The time course of the interaction between trypsin and a synthetic peptide corresponding to a segment (residues 676-703) of the bait region (residues 666-706) of human alpha 2-macroglobulin (alpha 2M) was studied by measuring the generation of cleavage products as a function of time by HPLC. Three primary cleavage sites for trypsin were present in the synthetic peptide. The fastest cleavage occurred at the bond corresponding to Arg696-Leu in alpha 2M with an estimated kcat/Km = 1-2 x 10(6) M-1.s-1. This value is of the same magnitude as that characterizing the interaction of alpha 2M and trypsin when taking into account the fact that alpha 2M is a tetramer, kcat/Km = 5 x 10(6) M-1.s-1 [Christensen, U. & Sottrup-Jensen, L. (1984) Biochemistry 23, 6619-6626]. The values of kcat/Km for cleavage at bonds corresponding to Arg681-Val and Arg692-Gly in alpha 2M were 1.5 x 10(5) M-1.s-1 and 1.3 x 10(5) M-1.s-1, respectively. Cleavage of intermediate product peptides was slower, with kcat/Km in the range 13-1.3 x 10(6) M-1.s-1. The value of Km determined for fast cleavage in the synthetic peptide was 8-10 microM. 1H-NMR spectroscopy indicated no ordered structure of the peptide. Hence, the very fast cleavage of the peptide is compatible with a loose structure that readily adopts a conformation favorable for recognition and cleavage by trypsin.     

Spectrophotofluorometric evidence of negatively cooperative binding of warfarin and phenylbutazone to human serum albumin

Competition between drugs for common binding sites on plasma proteins is an often discussed mechanism of drug interaction. In this study, the validity of the concept that phenylbutazone displaces warfarin from human serum albumin (HSA) by direct competition for the same sites was investigated. The fluorescence enhancement titration procedure of Kolb & Weber, Biochemistry $\text{14}$, 4471–4476 (1975) was used to characterise the warfarin-HSA interaction under the following conditions: excitation and emission wavelenghts - 310 & 390 nm respectively; buffer 0.1 M phosphate, pH 7.0 (25°C) and [HSA] - 10^?6M. The titrations were then repeated in the presence of varying concentrations of phenylbutazone (10^?6M ? 5 × 10^?4M). Bjerrum plots of the data showed a shift of the warfarin-HSA binding curves to higher free levels of warfarin with increasing concentrations of phenylbutazone. However this shift was saturable, contrary to expectation for directly competitive antagonism. Together with indirect evidence from the literature, the results suggest that displacement of warfarin by phenylbutazone is via a negatively cooperative mechanism rather than by direct competition.     

Avian Influenza Seroprevalence and Biosecurity Risk Factors in Maryland Backyard Poultry: A Cross-Sectional Study

Major implications on a country''s economy, food source, and public health. With recent concern over the highly pathogenic avian influenza outbreaks around the world, government agencies are carefully monitoring and inspecting live bird markets, commercial flocks, and migratory bird populations. However, there remains limited surveillance of non-commercial poultry. Therefore, a cross-sectional study was conducted in backyard poultry flocks using a convenience sampling method across three regions of Maryland from July 2011 to August 2011. The objective of this study was to develop a better understanding of the ecology and epidemiology of avian influenza by investigating the prevalence and seroprevalence in this potentially vulnerable population and by evaluating biosecurity risk factors associated with positive findings. Serum, tracheal, and cloacal swabs were randomly collected from 262 birds among 39 registered premises. Analysis indicated bird and flock seroprevalence as 4.2% (11/262) and 23.1% (9/39), respectively. Based on RT-qPCR analysis, none of the samples were found to be positive for AI RNA and evidence of AI hemagglutinin subtypes H5, H7, or H9 were not detected. Although no statistically significant biosecurity associations were identified (p≤0.05), AI seroprevalence was positively associated with exposure to waterfowl, pest control, and location. AI seropositive flocks exposed to waterfowl were 3.14 times as likely to be AI seropositive than those not exposed (p = 0.15). AI seropositive flocks that did not use pest control were 2.5 times as likely to be AI seropositive compared to those that did and AI seropositive flocks located in the Northern region of Maryland were 2.8 times as likely to be AI seropositive than those that were located elsewhere.     

Diallyl di-, tri- and tetrasulphide from Adenocalymma alliaceae

The essential oil from flowers and leaves of Adenocalymma alliaceae (Bignoniaceae) consists almost entirely of diallyl di-, tri-and tetra-sulphide, a mixture formerly encountered within the Allium genus but never before convincingly recognized within the class of dicotyledonous angiosperms.