A general law for animal locomotion?

The propulsion system of animals that fly or swim are quite different from each other in their morphology and function, yet the propulsive efficiency could be maximized by a surprising similarity in the fine tuning of flapping frequency, amplitude and forward speed, according to a new study by Taylor et al. This conclusion was based on an analysis of the Strouhal number, which is a dynamic similarity index relevant to propulsion that relies on vortex shedding for thrust generation. Such fine-tuning of the propulsive system suggests possible consequences for physiological and ecological adaptations related to, for example muscle operating frequency and optimal speed of muscle contraction.     

Streaming potential—a general affinity sensor

Electrokinetic phenomena, such as streaming potential or streaming current, have so far been used for studies of unspecific adsorption of ionic compounds on various materials. This paper shows that streaming potential measurements can also be used for studies of biospecific interactions.Several different interactions were studied, e.g. lectin-carbohydrate, IgG-Protein A. Regardless of the type of interaction an increasing change in streaming potential was obtained with increasing concentration of the interacting molecule. The authors also observed a correlation between streaming potential and affinity constants for carbohydrate-induced desorption of Concanavalin A from partially hydrolyzed Sephadex G50. In conclusion, it is shown that streaming potential measurements can be used to study molecular interactions, and to determine concentrations and relative binding constants of interacting molecules.     

Progress in bioleaching: fundamentals and mechanisms of bacterial metal sulfide oxidation—part A

Bioleaching of metal sulfides is performed by a diverse group of microorganisms. The dissolution chemistry of metal sulfides follows two pathways, which are determined by the mineralogy and the acid solubility of the metal sulfides: the thiosulfate and the polysulfide pathways. Bacterial cells can effect this metal sulfide dissolution via iron(II) ion and sulfur compound oxidation. Thereby, iron(III) ions and protons, the metal sulfide-attacking agents, are available. Cells can be active either in planktonic state or in forming biofilms on the mineral surface; however, the latter is much more efficient in terms of bioleaching kinetics. In the case of Acidithiobacillus ferrooxidans, bacterial exopolymers contain iron(III) ions, each complexed by two uronic acid residues. The resulting positive charge allows an electrostatic attachment to the negatively charged pyrite. Thus, the first function of complexed iron(III) ions is the mediation of cell attachment, while their second function is oxidative dissolution of the metal sulfide, similar to the role of free iron(III) ions in non-contact leaching. In both cases, the electrons extracted from the metal sulfide reduce molecular oxygen via a redox chain forming a supercomplex spanning the periplasmic space and connecting both outer and inner membranes. In this review, we summarize some recent discoveries relevant to leaching bacteria which contribute to a better understanding of these fascinating microorganisms. These include surface science, biochemistry of iron and sulfur metabolism, anaerobic metabolism, and biofilm formation. The study of microbial interactions among multispecies leaching consortia, including cell-to-cell communication mechanisms, must be considered in order to reveal more insights into the biology of bioleaching microorganisms and their potential biotechnological use.     

113Cd-1H hetero TOCSY: A method for determining metal—protein connectivities

Summary ¹¹³Cd-¹H NMR correlation experiments have been extremely useful for determining the amino acid ligands that form metal-binding sites in proteins. To date, the majority of these methods have used heteronuclear multiple-quantum transfer as the basis for establishing correlations. In this paper, we demonstrate the feasibility of using correlation methods that employ heteronuclear cross-polarization (hetero TOCSY) as viable alternatives. Additionally, we couple hetero TOCSY with selective excitation and transfer procedures to take advantage of the small number of heteronuclei usually present in metalloprotein systems. One- and two-dimensional experiments are presented as examples of these techniques.     

Chelation in metal intoxication—Principles and paradigms

The present review provides an update of the general principles for the investigation and use of chelating agents in the treatment of intoxications by metals. The clinical use of the old chelators EDTA (ethylenediamine tetraacetate) and BAL (2,3-dimercaptopropanol) is now limited due to the inconvenience of parenteral administration, their own toxicity and tendency to increase the neurotoxicity of several metals. The hydrophilic dithiol chelators DMSA (meso-2,3-dimercaptosuccinic acid) and DMPS (2,3-dimercapto-propanesulphonate) are less toxic and more efficient than BAL in the clinical treatment of heavy metal poisoning, and available as capsules for oral use. In copper overload, DMSA appears to be a potent antidote, although d-penicillamine is still widely used. In the chelation of iron, the thiols are inefficient, since iron has higher affinity for ligands with nitrogen and oxygen, but the new oral iron antidotes deferiprone and desferasirox have entered into the clinical arena. Comparisons of these agents and deferoxamine infusions are in progress. General principles for research and development of new chelators are briefly outlined in this review.     

A general mathematical performance model for wormhole-switched irregular networks

Irregular topologies are desirable network structures for building scalable cluster systems and very recently they have also been employed in SoC (system-on-chip) design. Many analytical models have been proposed in the literature to evaluate the performance of networks with different topologies such as hypercube, torus, mesh, hypermesh, Cartesian product networks, star graph, and k-ary n-cube; however, to the best of our knowledge, no mathematical model has been presented for irregular networks. Therefore, as an effort to fill this gap, this paper presents a comprehensive mathematical model for fully adaptive routing in wormhole-switched irregular networks. Moreover, since our approach holds no assumption for the network topology, the proposed analytical model covers all the aforementioned models (i.e. it covers both regular and irregular topologies). Furthermore, the model makes no preliminary assumption about the deadlock-free routing algorithm applied to the network. Finally, besides the generality of the model regarding the topology and routing algorithm, our analysis shows that the analytical model exhibits high accuracy which enables it to be used for almost all topologies with all traffic loads.     

RINGS — a general program to build ring systems

RINGS is a computer program for the general and rapid construction of ring skeletons. Prestored molecules are connected together by various operations, such as joining along one bond, fusion of one or more bonds, spiro joining, and carbon-bridge building. RINGS uses full 3D molecular structure information from the outset and offers the user full control of all geometrical features at each step of construction. The program is user-friendly, with a graphical man-machine interface (PLOT10-compatible) and extensive checking for possible input errors.     

A general reaction–diffusion model of acidity in cancer invasion

We model the metabolism and behaviour of a developing cancer tumour in the context of its microenvironment, with the aim of elucidating the consequences of altered energy metabolism. Of particular interest is the Warburg Effect, a widespread preference in tumours for cytosolic glycolysis rather than oxidative phosphorylation for glucose breakdown, as yet incompletely understood. We examine a candidate explanation for the prevalence of the Warburg Effect in tumours, the acid-mediated invasion hypothesis, by generalising a canonical non-linear reaction–diffusion model of acid-mediated tumour invasion to consider additional biological features of potential importance. We apply both numerical methods and a non-standard asymptotic analysis in a travelling wave framework to obtain an explicit understanding of the range of tumour behaviours produced by the model and how fundamental parameters govern the speed and shape of invading tumour waves. Comparison with conclusions drawn under the original system—a special case of our generalised system—allows us to comment on the structural stability and predictive power of the modelling framework.     

Radiofrequency tissue ablation inside of metal stent – A thermographic study

Biliary stents are used to treat obstructions that occur in the bile ducts. The stents can be blocked by new tissue in a few months after their implanting. This complication can be solved by using radiofrequency ablation. The present article deals with monitoring of the process of monopolar thermoablation of a metal stent by using an infrared camera ex vivo. The metallic EGIS Biliary stents 10 mm × 80 mm were used in experiments; radiofrequency ablation due by catheter EndoHPB 8F at 460 kHz was used. The Flir B200 thermocamera was used for monitoring. The results show an increase in temperature of the stent's material during thermoablation process. It is believed that the metal stent becomes an active electrode. The results show an increase in temperature of the stent and the surrounding tissue during the treatment. Temperature distribution measured on stent was affected by power applied and obviously non-homogeneous. The maximum temperature values were observed at the ends of the stent. The temperature value of the stent during termoablation depended also on the position of the second (inactive) surface electrode. Results of this study have shown that there are many factors able to affect the final temperature or process of tissue ablation inside of the stent and around the stent. Infrared camera seems to be an appropriate instrument for observing the distribution and changes in temperature during ex vivo radiofrequency ablation.     

干旱胁迫条件下发菜Ferritin差异表达与基因克隆

发菜(Nostoc flagelliforme)是一种陆生固氮蓝藻,具有强烈的旱生生态适应性.运用双向电泳技术、凝胶图像分析、MALDI-TOF-TOF/MS质谱鉴定和数据库检索,发现发菜Ferritin在干旱胁迫条件下表达量逐渐降低.根据鉴定的Ferritin已知氨基酸序列设计简并性引物克隆该基因,获得了长度为540 bp的DNA,GenBank登陆号为HM854287.序列比较显示该基因具有较高的保守性,蛋白质二级结构主要由α螺旋和随机卷曲构成.RT-PCR分析表明,Ferritin mRNA在干旱胁迫条件下表达量逐渐降低,与Ferritin的表达趋势一致.将Ferritin基因在大肠杆菌中表达,获得符合预期的外源重组蛋白(22.4 kD).实验结果可为进一步研究发菜耐旱的分子机理及探讨发菜对极端干旱环境的适应和保护机制奠定基础.     

Do physicians assess lifestyle health risks during general medical examinations? A survey of general practitioners and obstetrician-gynecologists in Quebec

BACKGROUND: In Canada several guidelines have been published for the screening of lifestyle health risks during general medical examinations. The authors sought to examine the extent to which such screening practices have been integrated into medical practice, to measure physicians'' perceived level of difficulty in assessing these risks and to document physicians'' evaluation of their formal medical training in lifestyle risk assessment. METHODS: An anonymous mail survey was conducted in 1995 in Quebec with a stratified random sample of 1086 general practitioners (GPs) and with all 241 obstetrician-gynecologists (Ob-Gyns). The authors evaluated the proportion of physicians who reported routine assessment (with 90% or more of their patients) of substance use, family violence and sexual history during general medical examinations of adult and adolescent patients; the proportion of those who find inquiring about these issues difficult; and the proportion of those who evaluated their medical training in lifestyle risk assessment as adequate or excellent. RESULTS: The overall response rate was 72.6%. Among adult patients, 82.2% of the GPs reported routinely assessing tobacco use, 67.2% alcohol consumption, 34.2% illicit drug use and 3.2% family violence; the corresponding proportions for assessment among adolescent patients were 77.1%, 61.8%, 52.9% and 5.6%. Comparatively fewer Ob-Gyns reported routinely assessing these issues (56.1%, 28.6%, 20.4% and 1.3% respectively among adults and 62.7%, 35.2%, 26.8% and 2.8% respectively among adolescents). In the area of sexual history, condom use was routinely assessed by more Ob-Gyns than GPs (47.0% v. 28.2%); however, the proportion of Ob-Gyns and GPs was equally low for assessing number of partners (24.8% and 23.1%), sexual orientation (18.8% and 16.9%) and STD risk (26.2% and 21.2%). The vast majority of GPs and Ob-Gyns reported finding it difficult to assess family violence (86.5% and 93.0%) and sexual abuse (92.7% and 92.4% respectively). Over 80% of the physicians felt that they had had adequate or excellent medical training in assessing risk behaviours for heart disease and STD risk. The proportion who felt this way about their training in screening for illicit drug use, family violence and sexual abuse ranged between 12.7% and 31.6%. INTERPRETATION: Although morbidity and mortality associated with smoking, alcohol consumption, illicit drug use, unsafe sexual practices, family violence and sexual abuse have been well documented, routine screening for these risk factors during general medical examinations has yet to be integrated into medical practice.     

The general secretory pathway: a general misnomer?

The term general secretory pathway (GSP) has been usurped and misused in the literature over the past few years. The concept of GSP is discussed from an historical perspective, and the definitions of the general export pathway (GEP), the main terminal branch (MTB) of the GSP, the unified GSP nomenclature and the type II, IV and V secretion pathways are also described to show how they have fuelled the confusion. By putting the record straight and using novel findings within the field of bacterial protein secretion, we hope to bring clarity to this area of science and prevent further promulgation of incorrect terminologies.     

Extended role for general practitioners in obstetrics? A medical audit.

A study was designed to evaluate provision of services, process of medical care, and outcome in four general-practitioner obstetric units in isolated areas (Berwick, Whitby, Guernsey, and Brecon). All units were equipped to induce labour; to perform instrumental vaginal delivery and selected breech deliveries; and to remove placentas manually. All had some fetal monitoring equipment. Caesarean sections could not be performed at Berwick and Whitby. Proportions of normal deliveries during 1976-7 varied from 75% to 93%. Perinatal mortality was acceptably low, as were transfer rates for neonates and mothers in labour. With specialist help and particular attention to training and broadening local doctors'' experience of abnormal obstetrics, such units should be able to provide an excellent obstetric service.