Assessment of post extraction complications in Indians

Extraction is one of the commonest procedures in dentistry. Therefore, it is of interest to evaluate the post extraction complications in patients undergoing extractions of permanent teeth. A total of 70 adult patients who had undergone dental extractions and presented with post -operative complications were included in the study and evaluated. Data collected was statistically analyzed using SPSS software and results obtained. Most of the patients with post extraction complications were in the age group of 31-40 years (21.6%), followed by 21-30 (20.2%) and 61-70 years (20.2%). Dry socket (39.19%) was the common post extraction complication in our study especially in the age group of 31-40 years. There was a statistically significant association between age of the patients and the post extraction complications (p<0.001). In our study, post extraction complications were commonly observed in age group of 31-40 years with a predilection for males. Dry socket was the most common post extraction complication. Age of the patient has a significant effect on post extraction complications. However, gender, smoking habits and systemic diseases have no influence on post extraction complications.     

Postfire population dynamics of a fire-dependent cypress

Plant Ecology - Tecate cypress (Hesperocyparis forbesii) is a rare species restricted to four metapopulations in southern California, USA and a few isolated populations in northern Baja California,...     

The glideosome: a molecular machine powering motility and host-cell invasion by Apicomplexa

The apicomplexans are obligate intracellular protozoan parasites that rely on gliding motility for their migration across biological barriers and for host-cell invasion and egress. This unusual form of substrate-dependent motility is powered by the "glideosome", a macromolecular complex consisting of adhesive proteins that are released apically and translocated to the posterior pole of the parasite by the action of an actomyosin system anchored in the inner membrane complex of the parasite. Recent studies have revealed new insights into the composition and biogenesis of Toxoplasma gondii myosin-A motor complex and have identified an exciting set of small molecules that can interfere with different aspects of glideosome function.     

Structural determinants of cross-linking and hydrophobic domains for self-assembly of elastin-like polypeptides

Elastin is a major structural protein found in large blood vessels, lung, ligaments, and skin, imparting the physical properties of extensibility and elastic recoil to these tissues. To achieve the required structural durability of the elastic matrix, the elastin monomer, tropoelastin, undergoes ordered assembly into a covalently cross-linked, fibrillar polymeric structure. Human tropoelastin consists of 34 exons coding for alternating hydrophobic and cross-linking domains. Using a series of well-defined recombinant polypeptides based on human elastin sequences mimicking native elastin, we have previously investigated the role of sequence and context of hydrophobic domains in elastin self-assembly. Here, we demonstrate that the structure of both cross-linking and hydrophobic domains have significant effects on the assembly of these polypeptides. Removing a putative flexible hinge region in the center of a cross-linking domain substantially increased the alpha-helical content and strongly promoted their self-aggregation. However, while trifluoroethanol (TFE) promoted and urea inhibited self-assembly of these polypeptides, these effects were not predominantly due to altered alpha-helicity of the polypeptides. Our results suggest that, while increased alpha helicity also favors this process, the major effect of TFE to promote organized self-assembly of elastin-like polypeptides is likely related to direct effects of this cosolvent on hydrophobic domains. Such simple elastin polypeptide models can provide an important tool for understanding the relationships between sequence, structure, and polymeric assembly of elastin.     

Hypoxia/reoxygenation reduces microvascular endothelial cell coupling by a tyrosine and MAP kinase dependent pathway

Communication of electrical signals along the microvascular endothelium plays a key role in integrating microvascular function required for local regulation of blood flow. The aim of the present study was to examine the effect of a short-term hypoxia (0.1% O(2), 1 h) plus reoxygenation (H/R) on electrical coupling in cultured monolayers of microvascular endothelial cells (rat skeletal muscle origin). To assess coupling, we used a current injection technique and a Bessel function model to compute the intercellular resistance (an inverse measure of coupling) and cell membrane resistivity (a measure of resistance to current leakage across the cell membrane). H/R resulted in rapid (within 4 min after reoxygenation) and sustained (up to 100 min) reduction in intercellular coupling, but it did not alter membrane resistivity. H/R did not alter gap junction protein connexin 43 expression nor its tyrosine phosphorylation as determined by immunoblot and immunoprecipitation analyses. Inhibition of mitochondrial respiration (1 mM NaCN) did not mimic the effect of H/R. However, pre-treatment of monolayers with tyrphostin A48 (1.5 microM), PP2 (10 nM) (tyrosine kinase inhibitors), U 0126 (20 microM), and PD 98059 (5 microM) (MEK1/2 inhibitors) inhibited the H/R-induced reduction in coupling. These results indicate that endothelial cell coupling was reduced quickly after reoxygenation, via activation of a tyrosine and MAP kinase dependent pathway. We predict that a short-term H/R can rapidly compromise microvascular function in terms of reduced cellular communication along the vascular wall.     

Oxidative and Nitrosative Modifications of Tropoelastin Prevent Elastic Fiber Assembly in Vitro

Elastic fibers are extracellular structures that provide stretch and recoil properties of tissues, such as lungs, arteries, and skin. Elastin is the predominant component of elastic fibers. Tropoelastin (TE), the precursor of elastin, is synthesized mainly during late fetal and early postnatal stages. The turnover of elastin in normal adult tissues is minimal. However, in several pathological conditions often associated with inflammation and oxidative stress, elastogenesis is re-initiated, but newly synthesized elastic fibers appear abnormal. We sought to determine the effects of reactive oxygen and nitrogen species (ROS/RNS) on the assembly of TE into elastic fibers. Immunoblot analyses showed that TE is oxidatively and nitrosatively modified by peroxynitrite (ONOO⁻) and hypochlorous acid (HOCl) and by activated monocytes and macrophages via release of ONOO⁻ and HOCl. In an in vitro elastic fiber assembly model, oxidatively modified TE was unable to form elastic fibers. Oxidation of TE enhanced coacervation, an early step in elastic fiber assembly, but reduced cross-linking and interactions with other proteins required for elastic fiber assembly, including fibulin-4, fibulin-5, and fibrillin-2. These findings establish that ROS/RNS can modify TE and that these modifications affect the assembly of elastic fibers. Thus, we speculate that oxidative stress may contribute to the abnormal structure and function of elastic fibers in pathological conditions.     

Carbon,oxygen and hydrogen isotope abundances inStylites reflect its unique physiology

Summary Natural abundances of oxygen-18, carbon-14, carbon-13 and deuterium were measured inStylites andicola, a terrestrial vascular plant lacking stomates, and two terrestrial plant species having stomates that grew nearby. No substantial differences in oxygen-18 and carbon-13 abundances were observed among the three species. The deuterium concentration inStylites was much higher than in the other species, confirming a previous report of CAM inStylites. Stylites was depleted in carbon-14 relative to the present day atmosphere, consistent with the proposal that it fixes CO₂ derived from decomposing peat.