QCT/FEA predictions of femoral stiffness are strongly affected by boundary condition modeling

Quantitative computed tomography-based finite element models of proximal femora must be validated with cadaveric experiments before using them to assess fracture risk in osteoporotic patients. During validation, it is essential to carefully assess whether the boundary condition (BC) modeling matches the experimental conditions. This study evaluated proximal femur stiffness results predicted by six different BC methods on a sample of 30 cadaveric femora and compared the predictions with experimental data. The average stiffness varied by 280% among the six BCs. Compared with experimental data, the predictions ranged from overestimating the average stiffness by 65% to underestimating it by 41%. In addition, we found that the BC that distributed the load to the contact surfaces similar to the expected contact mechanics predictions had the best agreement with experimental stiffness. We concluded that BC modeling introduced large variations in proximal femora stiffness predictions.     

Phenology of plants in relation to ambient environment in a subalpine forest of Uttarakhand,western Himalaya

Observations on phenology of some representative trees, shrubs, under-shrubs and herbs in a subalpine forest of Uttarakhand, western Himalaya were recorded. With the commencement of favorable growth season in April, occurrence of leaf fall was indicatory growth phenomenon in Quercus semecarpifolia, Q. floribunda and Abies spectabilis. However, active vegetative growth in herbaceous species starts onward April and fruit maturation and seed dehiscence are completed from mid of September to October. In general, vegetative growth and reproductive stages in majority of the studied species seems to be dependent on adequate moisture content and also flowering and fruiting in subalpine plants correlate ambient temperature.     

Developmental History Provides a Roadmap for the Emergence of Tumor Plasticity

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Western Diet Triggers NLRP3-Dependent Innate Immune Reprogramming

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An Uniquely Purified HCV NS3 Protease and NS4A21–34 Peptide Form a Highly Active Serine Protease Complex in Peptide Hydrolysis

The N-terminal domain of the hepatitis C virus (HCV) polyprotein containing the NS3 protease (residues 1027 to 1206) was expressed in Escherichia coli as a soluble protein under the control of the T7 promoter. The enzyme has been purified to homogeneity with cation exchange (SP-Sepharose HR) and heparin affinity chromatography in the absence of any detergent. The purified enzyme preparation was soluble and remained stable in solution for several weeks at 4°C. The proteolytic activity of the purified enzyme was examined, also in the absence of detergents, using a peptide mimicking the NS4A/4B cleavage site of the HCV polyprotein. Hydrolysis of this substrate at the expected Cys–Ala scissile bond was catalyzed by the recombinant protease with a pseudo second-order rate constant (k_cat/K_M) of 205 and 196,000 M⁻¹ s⁻¹, respectively, in the absence and presence of a central hydrophobic region (sequence represented by residues 21 to 34) of the NS4A protein. The rate constant in the presence of NS4A peptide cofactor was two orders of magnitude greater than reported previously for the NS3 protease domain. A significantly higher activity of the NS3 protease–NS4A cofactor complex was also observed with a substrate mimicking the NS4B/5A site (k_cat/K_M of 5180 ± 670 M⁻¹ s⁻¹). Finally, the optimal formation of a complex between the NS3 protease domain and the cofactor NS4A was critical for the high proteolytic activity observed.     

Pollen production and release in <Emphasis Type="Italic">Mesua ferrea</Emphasis> Linn. (Guttiferae): a spatio-temporal pattern

Based on a five-year study of pollen production and release in two different natural populations of Mesua ferrea from Indo-Burma region of Northeast India, we determined that pollen output follows a spatio-temporal pattern. Pollen productivity determinations considered various sources of variability, including the number of flowers per branch, flowers per tree, anthers per tree and pollen grains per tree. Each of these parameters revealed significant year-to-year and population effects. Anthesis follows a forenoon pattern, whereas anther dehiscence pursues the diurnal pattern. The former was significantly correlated with the timing of floral visitation and pollen deposition on stigmas. The latter, however, had significant relationship with the deposition of pollen grains on microscopic slides. The Apis and Xylocopa bees are the efficient pollinators to achieve the reproductive success in M. ferrea. Annual production of pollen per tree varied from averages of 1.07 ± 0.10 × 10¹⁰ and 3.24 ± 0.16 × 10¹⁰ in years of low production, with alternate high years, producing 3.85 ± 0.34 × 10¹⁰ and 8.22 ± 0.76 × 10¹⁰ pollen grains per tree.     

iNOS activity is critical for the clearance of Burkholderia mallei from infected RAW 264.7 murine macrophages

Burkholderia mallei is a facultative intracellular pathogen that can cause fatal disease in animals and humans. To better understand the role of phagocytic cells in the control of infections caused by this organism, studies were initiated to examine the interactions of B. mallei with RAW 264.7 murine macrophages. Utilizing modified kanamycin-protection assays, B. mallei was shown to survive and replicate in RAW 264.7 cells infected at multiplicities of infection (moi) of ≤ 1. In contrast, the organism was efficiently cleared by the macrophages when infected at an moi of 10. Interestingly, studies demonstrated that the monolayers only produced high levels of TNF-α, IL-6, IL-10, GM-CSF, RANTES and IFN-β when infected at an moi of 10. In addition, nitric oxide assays and inducible nitric oxide synthase (iNOS) immunoblot analyses revealed a strong correlation between iNOS activity and clearance of B. mallei from RAW 264.7 cells. Furthermore, treatment of activated macrophages with the iNOS inhibitor, aminoguanidine, inhibited clearance of B. mallei from infected monolayers. Based upon these results, it appears that moi significantly influence the outcome of interactions between B. mallei and murine macrophages and that iNOS activity is critical for the clearance of B. mallei from activated RAW 264.7 cells.