Quantification of the virus-host interaction in human T lymphotropic virus I infection

Background

Cellular infection with human immunodeficiency virus (HIV) both in vitro and in vivo requires a member of the chemokine receptor family to act as a co-receptor for viral entry. However, it is presently unclear to what extent the interaction of HIV proteins with chemokine receptors generates intracellular signals that are important for productive infection.

Results

In this study we have used a recently described family of chemokine inhibitors, termed BSCIs, which specifically block chemokine-induced chemotaxis without affecting chemokine ligands binding to their receptors. The BSCI termed Peptide 3 strongly inhibited CCR5 mediated HIV infection of THP-1 cells (83 ± 7% inhibition assayed by immunofluoresence staining), but had no effect on gp120 binding to CCR5. Peptide 3 did not affect CXCR4-dependent infection of Jurkat T cells.

Conclusion

These observations suggest that, in some cases, intracellular signals generated by the chemokine coreceptor may be required for a productive HIV infection.     

The Incidence and Prevention of Folate Deficiency in a Pregnant Clinic Population

Non-anemic women attending a public antenatal clinic were given, daily, a multivitamin tablet containing 78 mg. of elemental iron. The follow-up studies included an analysis of their diets. A total of 311 patients were included, of which one group received a supplement of 0.5 mg. folic acid and 0.005 mg. vitamin B₁₂. The incidence of megaloblastic bone marrow change in the unsupplemented group was 26% and of low blood folates approximately 50%. The incidence of megaloblastic changes was sharply reduced in the supplemented group and the blood folates were elevated to supranormal levels, indicating that the dose of folic acid used may have been above the minimal requirement. Formiminoglutamic acid (FIGLU) excretion could not be correlated with other parameters of folate deficiency. Neutrophil lobe counts did not relate to megaloblastic changes or low folate levels unless there was more than 5% hypersegmentation. The dietary intake was suboptimal in total calories, iron and food folate.     

Speciation through the lens of biomechanics: locomotion,prey capture and reproductive isolation

Speciation is a multifaceted process that involves numerous aspects of the biological sciences and occurs for multiple reasons. Ecology plays a major role, including both abiotic and biotic factors. Whether populations experience similar or divergent ecological environments, they often adapt to local conditions through divergence in biomechanical traits. We investigate the role of biomechanics in speciation using fish predator–prey interactions, a primary driver of fitness for both predators and prey. We highlight specific groups of fishes, or specific species, that have been particularly valuable for understanding these dynamic interactions and offer the best opportunities for future studies that link genetic architecture to biomechanics and reproductive isolation (RI). In addition to emphasizing the key biomechanical techniques that will be instrumental, we also propose that the movement towards linking biomechanics and speciation will include (i) establishing the genetic basis of biomechanical traits, (ii) testing whether similar and divergent selection lead to biomechanical divergence, and (iii) testing whether/how biomechanical traits affect RI. Future investigations that examine speciation through the lens of biomechanics will propel our understanding of this key process.     

Chemoprophylaxis with oral amoxycillin against bacterial endocarditis: when should second doses be administered after dentistry?

The adequacy of serum bactericidal activity after oral amoxycillin given as prophylaxis against infective endocarditis was studied using a double blind randomised protocol in healthy volunteers having dentistry. One hour before their procedure 38 patients received 3 g amoxycillin syrup and 12 received matching placebo. Venous blood samples were drawn before and one and nine hours after dosing and serum amoxycillin concentrations determined using a standard bioassay. Samples containing amoxycillin had inhibitory titres measured against two reference isolates of viridans streptococci known to have caused infective endocarditis. The susceptibility to amoxycillin of one strain was high and the other low, respective minimal bactericidal and inhibitory concentrations being 0.08 and 0.04 mumol/l (0.03 and 0.015 microgram/ml) and 2.74 and 1.37 mumol/l (1 and 0.5 microgram/ml). Amoxycillin was detected in only post-treatment samples of patients given the active drug. There were no significant correlations between one or nine hour drug concentrations and age or physical characteristics, nor was there any relation to preceding food consumption. Correlations between drug concentrations at one and nine hours were weak (r = 0.34; p less than 0.05), but between corresponding drug concentrations and serum inhibitory titres there were consistent correlations (r = 0.46-0.48; p less than 0.005). Against the low susceptibility reference isolate bactericidal amoxycillin concentrations were encountered in only 20 of the 38 nine hour samples (95% confidence limits 34% and 66%). When repeat doses of amoxycillin are indicated after dentistry they should be given about four hours later, not eight hours later as commonly practised.     

Atavisms and the homology of hyobranchial elements in lower vertebrates

The homology of branchial arch segments in salamanders has been a matter of controversy since the last century. Many investigators term the most medial paired elements of salamander branchial arches “ceratobranchials” and the next distal paired elements “epibranchials.” This suggests that the first two segmental elements of the salamander branchial arch are not homologous with elements occupying the same position in ray-finned fishes, Latimeria, “rhipidistians,” and lungfishes, in which these bones are called hypobranchials and ceratobranchials, respectively. Three lines of evidence suggest that it is more parsimonious to interpret urodele branchial arch segments as being homologous with those of other vertebrate clades?(1) comparative osteology, (2) comparative myology, and (3) the discovery of cartilaginous structures forming a third segmental unit that we interpret as atavistic epibranchials of the branchial arch in one population of the salamander Notophthalmus viridescens. These structures possess all the defining attributes of atavisms, and illustrate the special role that atavistic features play in resolving questions of homology recognition.     

Complex temporal decay: a complete analysis

Relaxation dynamics is universal in science and engineering; its study serves to parameterize a system's response and to help identify a microscopic model of the processes involved. When measured data for a phenomenon cannot be fitted using one exponential, the choice of an alternative function to describe the decay becomes nontrivial. Here, we contrast two different, but fundamentally related approaches to fitting nontrivial decay curves; exponential decomposition and the gamma probability density function. Copyright © 2013 John Wiley & Sons, Ltd.     

Locomotion with flexible propulsors: II. Computational modeling of pectoral fin swimming in sunfish

This paper describes a computational fluid dynamics (CFD) based investigation of the pectoral fin hydrodynamics of a bluegill sunfish. The pectoral fin of this fish undergoes significant shape-change during its abduction-adduction cycle and the effect of this deformation on the thrust performance remains far from understood. The current study is part of a combined experimental-numerical approach wherein the numerical simulations are being used to examine features and issues that are not easily amenable to the experiments. These numerical simulations are highly challenging and we briefly describe the computational methodology that has been developed to handle such flows. Finally, we describe some of the key computational results including wake vortex topologies and hydrodynamics forces.