Mechanism of lipid bilayer perturbation by bactericidal membrane-active small molecules.

Membrane-active small molecules (MASMs) are small organic molecules designed to reproduce the fundamental physicochemical properties of natural antimicrobial peptides: their cationic charge and amphiphilic character. This class of compounds has a promising broad range of antimicrobial activity and, at the same time, solves some major limitations of the peptides, such as their high production costs and low in vivo stability. Most cationic antimicrobial peptides act by accumulating on the surface of bacterial membranes and causing the formation of defects when a threshold is reached. Due to the drastically different structures of the two classes of molecules, it is not obvious that small-molecule antimicrobials act in the same way as natural peptides, and very few data are available on this aspect. Here we combined spectroscopic studies and molecular dynamics simulations to characterize the mechanism of action of two different MASMs. Our results show that, notwithstanding their simple structure, these molecules act just like antimicrobial peptides. They bind to the membrane surface, below the head-groups, and insert their apolar moieties in the core of the bilayer. Like many natural peptides, they cause the formation of defects when they reach a high coverage of the membrane surface. In addition, they cause membrane aggregation, and this property could contribute to their antimicrobial activity.

Nipah virus: a narrative review of viral characteristics and epidemiological determinants.

OBJECTIVES: The objectives of this article are to highlight the properties of the Nipah virus (NiV) and discuss its epidemiological determinants. STUDY DESIGN: A review of conjectures, epidemiological and clinically related studies, and identification and discussion of preventive approaches is conducted. METHODS: A review of the current literature is performed going through online search engines: PubMed and Google Scholar. The search strategy was focused on two main components, first on the NiV ('Nipah' OR 'Nipah Virus') and subsequently on its epidemiology, including determinants and preventive measures ('Epidemiology/determinants' OR 'Epidemiology/prevention'). RESULTS: NiV infection is an emerging zoonotic infectious disease causing sporadic outbursts in many developing countries within Asia, Africa, and South America. Pteroid bats are the natural reservoirs, but human-to-human transmission is possible. Clinical course ranges from non-specific influenza-like symptoms to rapidly progressive respiratory and neurologic complications. Vector control has been challenging because of its widely distributed ecological niche. Currently, no definitive treatment protocols are available in humans, but profound breakthrough in vaccine technology and successful equine vaccines has shown the way for the development of NiV vaccine and immunization in the near future. CONCLUSIONS: The NiV poses a significant public health risk because of its intricate transmission cycle, unpredictable viral course, murky management protocol, and unavailability of vaccine. Complicated by emergence and subsequent reemergence, prevention and containment are the two most important public health promotion strategies. Early anticipation, intergovernmental preparedness and cooperation, and surveillance of zoonotic infections still remain the key to mitigate the risk.

Complete Right Ovarian Vein Thrombosis Extending to the Inferior Vena Cava during Early Postpartum Period in a Low Risk Patient.

Postpartum ovarian vein thrombosis is rare but life-threatening complication of puerperium. It predominantly occurs in the right side of the abdomen, mimicking various other conditions like acute appendicitis, ureteral stones or tubo-ovarian abscess. It is imperative to envisage the possibility of this rare disease even in an uncomplicated pregnancy. Here, we reported a 28-year-old female with no significant underlying risk factors who presented with high-grade fever and right lower abdominal pain after four days of an uncomplicated cesarean delivery. A right-sided complete ovarian vein thrombosis extending to the inferior vena cava was diagnosed and subsequently managed with long-term anticoagulant therapy. She had an uneventful recovery, with repeat imaging after three months showing complete resolution of thrombus.

Effect of thermal annealing on the thermoluminescent properties of nano-calcium fluoride and its dose-response characteristics.

Nano-CaF2, prepared by the co-precipitation method, was annealed under different annealing conditions to improve its thermoluminescence (TL) characteristics. Different annealing parameters, such as temperature (400-700°C), duration (1-4 h) and environment (vacuum and air), were explored. The effect on TL sensitivity, peak position (Tm) and full-width at half-maximum (FWHM) with respect to the different annealing conditions are discussed as they are the measure of crystallinity of the material. Annealing temperature of 500°C with annealing duration of two and a half hours in vacuum provided the highest luminescence response (i.e. maximum sensitivity, minimum peak temperature and FWHM). Wide detectable dose range (5 mGy to 2 kGy), absence of thermal quenching and sufficient activation energy (1.04 eV) of this phosphor make it suitable for dosimetric applications.

Compact light-emitting-diode sun photometer for atmospheric optical depth measurements.

A new compact light-emitting diode (LED) sun photometer, in which a LED is used as a spectrally selective photodetector as well as a nonlinear feedback element in the operational amplifier, has been developed. The output voltage that is proportional to the logarithm of the incident solar intensity permits the direct measurement of atmospheric optical depths in selected spectral bands. Measurements made over Ahmedabad, India, show good agreement, within a few percent, of optical depths derived with a LED as a photodetector in a linear mode and with a LED as both a photodetector and a feedback element in an operational amplifier in log mode. The optical depths are also found to compare well with those obtained simultaneously with a conventional filter photometer.

Nd:YAG backscatter lidar at Ahmedabad (23° N, 72.5° E) for tropical middle atmospheric studies.

A backscatter Nd:YAG laser radar, the first of this type in India to our knowledge, was developed at the Physical Research Laboratory, Ahmedabad (23° N, 72.5° E), for middle atmospheric studies. The system has been operational since April 1992. The system details and sample results on the Mt. Pinatubo volcanic aerosol layer and its decay as observed over this tropical site are presented and discussed. The future augmentation of the system and planned activities are also outlined.