On the group theoretical background of assigning stepwise mutations onto phylogenies

Recently one step mutation matrices were introduced to model the impact of substitutions on arbitrary branches of a phylogenetic tree on an alignment site. This concept works nicely for the four-state nucleotide alphabet and provides an efficient procedure conjectured to compute the minimal number of substitutions needed to transform one alignment site into another. The present paper delivers a proof of the validity of this algorithm. Moreover, we provide several mathematical insights into the generalization of the OSM matrix to multi-state alphabets. The construction of the OSM matrix is only possible if the matrices representing the substitution types acting on the character states and the identity matrix form a commutative group with respect to matrix multiplication. We illustrate this approach by looking at Abelian groups over twenty states and critically discuss their biological usefulness when investigating amino acids

Effect of essential oils on properties of film forming emulsions and films based on HPMC and chitosan

[EN] Film-forming dispersions (FFD) and films, prepared by incorporating different concentrations of bergamot (BO), lemon (LO) and tea tree (TTO) essential oils into hydroxyproplymethylcellulose (HPMC) and chitosan (CH) were obtained and their physico-chemical properties were characterised. Results showed that the increment of essential oil (EO) content promoted significant changes in the size and surface charge of the FFD particles. As regards the film properties, the higher the EO content, the lower the water vapour permeability and the moisture sorption capacity. In general, the addition of EO into the HPMC or CH matrix leads to a significant decrease in gloss, transparency, tensile strength and elastic modulus of the composite films. Discriminant analyses of obtained data revealed that the polymer type was the main factor which defined the FFD and composite film behaviour. For a given polymer, although both the nature and concentration of the EO influenced FFD behaviour, the concentration played a more important role. In film properties, the discriminant analyses did not reveal different groups associated to the different nature or concentration of the essential oils, although composite films with BO appeared to differ slightly from the rest. (C) 2011 Elsevier Ltd. All rights reserved.The authors acknowledge the financial support provided by Ministerio de Educacion y Ciencia (Project AGL2007-65503). Author L. Sanchez-Gonzalez thanks Ministerio de Educacion y Ciencia (Spain) for a FPU Grant (AP2006-026)Sánchez González, L.; Chiralt, A.; González Martínez, MC.; Cháfer Nácher, MT. (2011). Effect of essential oils on properties of film forming emulsions and films based on HPMC and chitosan. Journal of Food Engineering. 105(2):246-253. https://doi.org/10.1016/j.jfoodeng.2011.02.028S246253105

Isolation, Characterization, and Stability of Discretely-Sized Nanolipoprotein Particles Assembled with Apolipophorin-III

Background: Nanolipoprotein particles (NLPs) are discoidal, nanometer-sized particles comprised of self-assembled phospholipid membranes and apolipoproteins. NLPs assembled with human apolipoproteins have been used for myriad biotechnology applications, including membrane protein solubilization, drug delivery, and diagnostic imaging. To expand the repertoire of lipoproteins for these applications, insect apolipophorin-III (apoLp-III) was evaluated for the ability to form discretely-sized, homogeneous, and stable NLPs. Methodology: Four NLP populations distinct with regards to particle diameters (ranging in size from 10 nm to.25 nm) and lipid-to-apoLp-III ratios were readily isolated to high purity by size exclusion chromatography. Remodeling of the purified NLP species over time at 4uC was monitored by native gel electrophoresis, size exclusion chromatography, and atomic force microscopy. Purified 20 nm NLPs displayed no remodeling and remained stable for over 1 year. Purified NLPs with 10 nm and 15 nm diameters ultimately remodeled into 20 nm NLPs over a period of months. Intra-particle chemical cross-linking of apoLp-III stabilized NLPs of all sizes. Conclusions: ApoLp-III-based NLPs can be readily prepared, purified, characterized, and stabilized, suggesting their utilit

On a global differential geometric approach to the rational mechanics of deformable media

In the past the rational mechanics of deformable media was largely concerned with materials governed by linear constitutive equations. In recent years, the theory has expanded considerably towards covering materials for which the constitutive equations are inherently nonlinear, and/or whose mechanical properties resemble in some respects those of a fluid and in others those of a solid. In the present article we formulate a satisfactory global mathematical theory of moving deformable media, which includes all these aspects

Hepatobiliary and pancreatic tuberculosis: A two decade experience

<p>Abstract</p> <p>Background</p> <p>Isolated hepatobiliary or pancreatic tuberculosis (TB) is rare and preoperative diagnosis is difficult. We reviewed our experience over a period two decades with this rare site of abdominal tuberculosis.</p> <p>Methods</p> <p>The records of 18 patients with proven histological diagnosis of hepatobiliary and pancreatic tuberculosis were reviewed retrospectively. The demographic features, sign and symptoms, imaging, cytology/histopathology, procedures performed, outcome and follow up data were obtained from the departmental records. The diagnosis of tuberculosis was based on granuloma with caseation necrosis on histopathology or presence of acid fast bacilli.</p> <p>Results</p> <p>Of 18 patients (11 men), 11 had hepatobiliary TB while 7 had pancreatic TB. Two-thirds of the patients were < 40 years (mean: 42 yrs; range 19–70 yrs). The duration of the symptoms varied between 2 weeks to 104 weeks (mean: 20 weeks). The most common symptom was pain in the abdomen (n = 13), followed by jaundice (n = 10), fever, anorexia and weight loss (n = 9). Five patients (28%) had associated extra-abdominal TB which helped in preoperative diagnosis in 3 patients. Imaging demonstrated extrahepatic bile duct obstruction in the patients with jaundice and in addition picked up liver, gallbladder and pancreatic masses with or without lymphadenopathy (peripancreatic/periportal). Preoperative diagnosis was made in 4 patients and the other 14 were diagnosed after surgery. Two patients developed significant postoperative complications (pancreaticojejunostomy leak <abbrgrp><abbr bid="B1">1</abbr></abbrgrp> intraabdominal abscess <abbrgrp><abbr bid="B1">1</abbr></abbrgrp>) and 3 developed ATT induced hepatotoxicity. No patient died. The median follow up period was 12 months (9 – 96 months).</p> <p>Conclusion</p> <p>Tuberculosis should be considered as a differential diagnosis, particularly in young patients, with atypical signs and symptoms coming from areas where tuberculosis is endemic and preoperative tissue and/or cytological diagnosis should be attempted before labeling them as hepatobiliary and pancreatic malignancy.</p

Mechanisms Involved in Nicotinic Acetylcholine Receptor-Induced Neurotransmitter Release from Sympathetic Nerve Terminals in the Mouse Vas Deferens

Prejunctional nicotinic acetylcholine receptors (nAChRs) amplify postganglionic sympathetic neurotransmission, and there are indications that intraterminal Ca2+ stores might be involved. However, the mechanisms by which nAChR activation stimulates neurotransmitter release at such junctions is unknown. Rapid local delivery (picospritzing) of the nAChR agonist epibatidine was combined with intracellular sharp microelectrode recording to monitor spontaneous and field-stimulation-evoked neurotransmitter release from sympathetic nerve terminals in the mouse isolated vas deferens. Locally applied epibatidine (1 µM) produced ‘epibatidine-induced depolarisations’ (EIDs) that were similar in shape to spontaneous excitatory junction potentials (SEJPs) and were abolished by nonselective nAChR antagonists and the purinergic desensitizing agonist α,β-methylene ATP. The amplitude distribution of EIDs was only slightly shifted towards lower amplitudes by the selective α7 nAChR antagonists α-bungarotoxin and methyllcaconitine, the voltage-gated Na+ channel blocker tetrodotoxin or by blocking voltage-gated Ca2+ channels with Cd2+. Lowering the extracellular Ca2+ concentration reduced the frequency of EIDs by 69%, but more surprisingly, the Ca2+-induced Ca2+ release blocker ryanodine greatly decreased the amplitude (by 41%) and the frequency of EIDs by 36%. Ryanodine had no effect on electrically-evoked neurotransmitter release, paired-pulse facilitation, SEJP frequency, SEJP amplitude or SEJP amplitude distribution. These results show that activation of non-α7 nAChRs on sympathetic postganglionic nerve terminals induces high-amplitude junctional potentials that are argued to represent multipacketed neurotransmitter release synchronized by intraterminal Ca2+-induced Ca2+ release, triggered by Ca2+ influx directly through the nAChR. This nAChR-induced neurotransmitter release can be targeted pharmacologically without affecting spontaneous or electrically-evoked neurotransmitter release