The Postural Tachycardia Syndrome (POTS): Pathophysiology, Diagnosis & Management

Postural tachycardia syndrome (POTS), characterized by orthostatic tachycardia in the absence of orthostatic hypotension, has been the focus of increasing clinical interest over the last 15 years 1. Patients with POTS complain of symptoms of tachycardia, exercise intolerance, lightheadedness, extreme fatigue, headache and mental clouding. Patients with POTS demonstrate a heart rate increase of ≥30 bpm with prolonged standing (5-30 minutes), often have high levels of upright plasma norepinephrine (reflecting sympathetic nervous system activation), and many patients have a low blood volume. POTS can be associated with a high degree of functional disability. Therapies aimed at correcting the hypovolemia and the autonomic imbalance may help relieve the severity of the symptoms. This review outlines the present understanding of the pathophysiology, diagnosis, and management of POTS

New Phosphated Poly(methyl Methacrylate) Polymers for the Prevention of Denture-induced Microbial Infection: an In Vitro Study

Purpose: Poly(methyl methacrylate) (PMMA) has been widely used as a denture-base acrylic resin due to its excellent physical and mechanical properties. However, the material is highly prone to microbial fouling that often leads to Candida-associated denture stomatitis. Incorporation of phosphate groups into PMMA could facilitate adsorption of salivary antimicrobials and inhibit microbial adherence on the polymer surface. An in vitro study evaluated PMMA polymers containing varying amounts of phosphate group for their efficacy to inhibit Candida albicans adhesion, adsorb salivary histatin 5, and exhibit candidacidal activity. Methods: Six PMMA polymers containing 0%, 5%, 15%, 10%, 20%, and 25% of phosphate group were synthesized by bead (suspension) polymerization technique using mixtures of methyl methacrylate and methallyl phosphate as monomers. The efficacy of the polymers to inhibit the adherence of C. albicans was examined by using human saliva-coated polymer beads and radio-labeled C. albicans cells, as compared with that of PMMA. The potency of the phosphated PMMA polymers to adsorb histatin 5 was determined by measuring the radioactivity of the adsorbed labeled-peptide on the polymer surface. The candidacidal activity of the histatin 5-adsorbed polymers was assessed by using the fluorescence technique. The percent release of the fluorescent probe calcein from the C. albicans membrane caused by the disruption of the cell membrane was determined. The data were analyzed statistically by one-way ANOVA followed by Scheffé’s test (α = 0.05 and n = 6). Results: The presence of ≥15% phosphate content in PMMA significantly reduced the saliva-mediated adhesion of C. albicans. Phosphated PMMA polymers showed significantly enhanced adsorption of histatin 5 in a phosphate density-dependent manner. The candidacidal activity of the histatin 5-bound polymers increased significantly with the increase in the phosphate content of the polymer. Conclusion: Phosphated PMMA polymers have the potential to serve as novel denture-base resins, which may reduce C. albicans colonization and prevent denture stomatitis

On the investigation of cascade and turbomachinery rotor wake characteristics

The objective of the investigation reported in this thesis is to study the characteristics of a turbomachinery rotor wake, both analytically and experimentally. The constitutive equations for the rotor wake are developed using generalized tensors and a non-inertial frame of reference. Analytical and experimental investigation is carried out in two phases; the first phase involved the study of a cascade wake in the absence of rotation and three dimensionality. In the second phase the wake of a rotor is studied. Simplified two- and three-dimensional models are developed for the prediction of the mean velocity profile of the cascade and the rotor wake, respectively, using the principle of self-similarity. The effect of various major parameters of the rotor and the flow geometry is studied on the development of a rotor wake. Laws governing the decay of the wake velocity defect in a cascade and rotor wake as a function of downstream distance from the trailing edge, pressure gradient and other parameters are derived

Current Status of Defensins and Their Role in Innate and Adaptive Immunity

Naturally occurring antimicrobial cationic polypeptides play a major role in innate and adaptive immunity. These polypeptides are found to be either linear and unstructured or structured through disulfide bonds. Among the structured antimicrobial polypeptides, defensins comprise a family of cysteine-rich cationic polypeptides that contribute significantly to host defense against the invasion of microorganisms in animals, humans, insects and plants. Their wide-spread occurrence in various tissues of these diverse organisms, and their importance in innate and adaptive immunity have led to their identification, isolation and characterization. A large volume of literature is available on defensins’ occurrence, structural characterization, gene expression and regulation under normal and pathological conditions. Much has also been published regarding their antimicrobial, antiviral and chemoattractive properties, and their molecular and cellular interactions. In this review, we describe the current status of our knowledge of defensins with respect to their molecular, cellular and structural biology, their role in host defense, future research paradigms and the possibility of their utilization as a new class of non-toxic antimicrobial agents and immuno-modulators

Does Openness to Trade Make Countries More Vulnerable to Sudden Stops, or Less? Using Gravity to Establish Causality

Openness to trade is one factor that has been identified as determining whether a country is prone to sudden stops in capital inflows, crashes in currencies, or severe recessions. Some believe that openness raises vulnerability to foreign shocks, while others believe that it makes adjustment to crises less painful. Several authors have offered empirical evidence that having a large tradable sector reduces the contraction necessary to adjust to a given cut-off in funding. This would help explain lower vulnerability to crises in Asia than in Latin America. Such studies may, however, be subject to the problem that trade is endogenous. Using the gravity instrument for trade openness, which is constructed from geographical determinants of bilateral trade, this paper finds that openness indeed makes countries less vulnerable, both to severe sudden stops and currency crashes, and that the relationship is even stronger when correcting for the endogeneity of trade.