2006～2010年革兰阴性菌对碳青霉烯类抗生素耐药性分析

目的调查分析我院20ff6～2010年临床分离的革兰阴性菌对碳青霉烯类抗生素的耐药性。方法采用纸片扩散法进行抗菌药物敏感实验,采用WHONET5．4软件及SPSS13．0软件进行数据分析。结果大肠埃希菌和肺炎克雷伯菌对亚胺培南和美罗培南的耐药率呈上升趋势,但最高不超过4．5％。铜绿假单胞菌对亚胺培南的耐药率2006年和2007年监测显示为21．3％和41％。2008年达到44．8％,在2009年下降为12．4％,但2010年爽迅速增加到30．1％。鲍曼不动杆菌对亚胺培南耐药率的逐年上升更为显著,从2006年9．1％上升到2010年的68％,差异具有统计学意义（P〈0．01）。嗜麦芽窄食单胞菌对碳青霉烯类抗生素天然耐药,2006年对亚胺培南耐药率为30％,但自2007年起就增加到80．8％,最高达100％。结论肠杆菌科细菌对碳青霉烯类敏感性高,近年耐药率有上升趋势。铜绿假单胞菌和鲍曼不动杆菌对碳青霉烯类耐药率高,尤其是鲍曼不动杆菌的分离率逐年增加,耐药形势严峻。临床应合理使用抗生素,减少多重耐药株的产生。     

The growth plate’s response to load is partially mediated by mechano-sensing via the chondrocytic primary cilium

Mechanical load plays a significant role in bone and growth-plate development. Chondrocytes sense and respond to mechanical stimulation; however, the mechanisms by which those signals exert their effects are not fully understood. The primary cilium has been identified as a mechano-sensor in several cell types, including renal epithelial cells and endothelium, and accumulating evidence connects it to mechano-transduction in chondrocytes. In the growth plate, the primary cilium is involved in several regulatory pathways, such as the non-canonical Wnt and Indian Hedgehog. Moreover, it mediates cell shape, orientation, growth, and differentiation in the growth plate. In this work, we show that mechanical load enhances ciliogenesis in the growth plate. This leads to alterations in the expression and localization of key members of the Ihh-PTHrP loop resulting in decreased proliferation and an abnormal switch from proliferation to differentiation, together with abnormal chondrocyte morphology and organization. Moreover, we use the chondrogenic cell line ATDC5, a model for growth-plate chondrocytes, to understand the mechanisms mediating the participation of the primary cilium, and in particular KIF3A, in the cell’s response to mechanical stimulation. We show that this key component of the cilium mediates gene expression in response to mechanical stimulation.     

Complementarity and the selection of nature reserves: algorithms and the origins of conservation planning, 1980–1995

This paper reconstructs the history of the introduction and use of iterative algorithms in conservation biology in the 1980s and early 1990s in order to prioritize areas for protection as nature reserves. The importance of these algorithms was that they led to greater economy in spatial extent (“efficiency”) in the selection of areas to represent biological features adequately (that is, to a specified level) compared to older methods of scoring and ranking areas using criteria such as biotic “richness” (the number of features of interest). The development of these algorithms was critical to producing a research program for conservation biology that was distinct from ecology and eventually led to what came to be called systematic conservation planning. Very similar algorithmic approaches were introduced independently in the 1980–1990 period in Australia, South Africa, and (arguably) the United Kingdom. The key rules in these algorithms were the use of rarity and what came to be called complementarity (the number of new or under-represented features in an area relative to those that had already been selected). Because these algorithms were heuristic, they were not guaranteed to produce optimal (most “efficient”) solutions. However, complementarity came to be seen as a principle rather than a rule in an algorithm and its use was also advocated for the former reason. Optimal solutions could be produced by reformulating the reserve selection problem in a mathematical programming formalism and using exact algorithms developed in that context. A dispute over the relevance of full optimality arose and was never resolved. Moreover, exact algorithms could not easily incorporate criteria determining the spatial configuration of networks of selected areas, in contrast to heuristic algorithms. Meanwhile metaheuristic algorithms emerged in the 1990s and came to be seen as a credible more effective alternative to the heuristic algorithms. Ultimately what was important about these developments was that the reserve selection problem came to be viewed a complex optimal decision problem under uncertainty, resource, and other constraints. It was a type of problem that had no antecedent in traditional ecology.     

Developments in biotechnology

This issue of EXPERIENTIA on ‘Developments in Biotechnology’ is dedicated to Professor Armin Fiechter who celebrated his 65th birthday in October. He is one of the most eminent promoters of biotechnology in Switzerland and he was instrumental in establishing the Institute for Biotechnology at ETH in 1982 of which he is still director. By pioneering the combination of fundamental and applied aspects he has greatly influenced the advancement of biotechnology in teaching and research in Switzerland. Distinguished scientists from various countries were invited to contribute to this special issue of EXPERIENTIA to review aspects of yeast physiology, process optimization and control, analytics, and applications. We are well aware that the articles presented here are only a narrow selection of the current activities in biotechnology but since Professor Fiechter has devoted most of his scientific career to research on yeast physiology, process development and instrumentation it is appropriate to focus this issue on these aspects. We thank all the authors who have contributed to mark this special event. Professor Fiechter continues to actively stimulate progress in biotechnology with a still lively awareness of future developments. May he continue to persue his objectives and, together with Mrs. Fiechter, enjoy the time to come.     

Three-dimensional structure of motor molecules

Images, calculated from electron micrographs, show the three-dimensional structures of microtubules and tubulin sheets decorated stoichiometrically with motor protein molecules. Dimeric motor domains (heads) of kinesin and ncd, the kinesin-related protein that moves in the reverse direction, each appeared to bind to tubulin in the same way, by one of their two heads. The second heads show an interesting difference in position that seems to be related to the directions of movement of the two motors. X-ray crystallographic results showing the structures of kinesin and ncd to be very similar at atomic resolution, and homologous also to myosin, suggest that the two motor families may use mechanisms that have much in common. Nevertheless, myosins and kinesins differ kinetically. Also, whereas conformational changes in the myosin catalytic domain are amplified by a long lever arm that connects it to the stalk domain, kinesin and ncd do not appear to possess a structure with a similar function but may rely on biased diffusion in order to move along microtubules.     

Endothelium-derived nitric oxide and vascular physiology and pathology

In 1980, Furchgott and Zawadzki demonstrated that the relaxation of vascular smooth muscle cells in response to acetylcholine is dependent on the anatomical integrity of the endothelium. Endothelium-derived relaxing factor was identified 7 years later as the free radical gas nitric oxide (NO). In endothelium, the amino acid L-arginine is converted to L-citrulline and NO by one of the three NO synthases, the endothelial isoform (eNOS). Shear stress and cell proliferation appear to be, quantitatively, the two major regulatory factors of eNOS gene expression. However, eNOS seems to be mainly regulated by modulation of its activity. Stimulation of specific receptors to various agonists (e.g., bradykinin, serotonin, adenosine, ADP/ATP, histamine, thrombin) increases eNOS enzymatic activity at least in part through an increase in intracellular free Ca²⁺. However, the mechanical stimulus shear stress appears again to be the major stimulus of eNOS activity, although the precise mechanisms activating the enzyme remain to be elucidated. Phosphorylation and subcellular translocation (from plasmalemmal caveolae to the cytoskeleton or cytosol) are probably involved in these regulations. Although eNOS plays a major vasodilatory role in the control of vasomotion, it has not so far been demonstrated that a defect in endothelial NO production could be responsible for high blood pressure in humans. In contrast, a defect in endothelium-dependent vasodilation is known to be promoted by several risk factors (e.g., smoking, diabetes, hypercholesterolemia) and is also the consequence of atheroma (fatty streak infiltration of the neointima). Several mechanisms probably contribute to this decrease in NO bioavailability. Finally, a defect in NO generation contributes to the pathophysiology of pulmonary hypertension. Elucidation of the mechanisms of eNOS enzyme activity and NO bioavailability will contribute to our understanding the physiology of vasomotion and the pathophysiology of endothelial dysfunction, and could provide insights for new therapies, particularly in hypertension and atherosclerosis.     

Protein intrinsic disorder as a flexible armor and a weapon of HIV-1

Many proteins and protein regions are disordered in their native, biologically active states. These proteins/regions are abundant in different organisms and carry out important biological functions that complement the functional repertoire of ordered proteins. Viruses, with their highly compact genomes, small proteomes, and high adaptability for fast change in their biological and physical environment utilize many of the advantages of intrinsic disorder. In fact, viral proteins are generally rich in intrinsic disorder, and intrinsically disordered regions are commonly used by viruses to invade the host organisms, to hijack various host systems, and to help viruses in accommodation to their hostile habitats and to manage their economic usage of genetic material. In this review, we focus on the structural peculiarities of HIV-1 proteins, on the abundance of intrinsic disorder in viral proteins, and on the role of intrinsic disorder in their functions.     

Introduction: lipid-binding proteins: novel aspects

Lipid-binding proteins function to transport lipids across membranes and aqueous phases and act to solubilise their cargo, protect it from chemical damage and probably also to define its destination. As such, they have been adapted to carry out a broad spectrum of biological functions in addition to their classical roles in energy metabolism and the transmission or blocking of retinoid-based signalling. The set of reviews in this issue of CMLS is designed to draw attention to some newly understood aspects and principles of their biology and structure, and concentrates on the proteins involved in transport of fatty acids and retinoids.     

Zinc,copper and selenium in reproduction

Of the nine biological trace elements, zinc, copper and selenium are important in reproduction in males and females. Zinc content is high in the adult testis, and the prostate has a higher concentration of zinc than any other organ of the body. Zinc deficiency first impairs angiotensin converting enzyme (ACE) activity, and this in turn leads to depletion of testosterone and inhibition of spermatogenesis. Defects in spermatozoa are frequently observed in the zinc-deficient rat. Zinc is thought to help to extend the functional life span of the ejaculated spermatozoa. Zinc deficiency in the female can lead to such problems as impaired synthesis/secretion-of (FSH) and (LH), abnormal ovarian development, disruption of the estrous cycle, frequent abortion, a prolonged gestation period, teratogenicity, still-births, difficulty in parturition, pre-eclampsia, toxemia and low birth weights of infants. The level of testosterone in the male has been suggested to play a role in the severity of copper deficiency. Copper-deficient female rats are protected against mortality due to copper deficiency, and the protection has been suggested to be provided by estrogens, since estrogens alter the subcellular distribution of copper in the liver and increase plasma copper levels by inducing ceruloplasmin synthesis. The selenium content of male gonads increases during pubertal maturation. Selenium is localized in the mitochondrial capsule protein (MCP) of the midpiece. Maximal incorporation in MCP occurs at steps 7 and 12 of spermatogenesis and uptake dereases by step 15. Selenium deficiency in females results in infertility, abortions and retention of the placenta. The newborns from a selenium-deficient mother suffer from muscular weakness, but the concentration of selenium during pregnancy does not have any effect on the weight of the baby or length of pregnancy. The selenium requirements of a pregnant and lactating mother are increased as a result of selenium transport to the fetus via the placenta and to the infant via breast milk.     

Herbivory in holometabolous and hemimetabolous insects: contrasts between Orthoptera and Lepidoptera

Summary Adaptation to a phytophagous diet involves physiological compromises that may be influenced by developmental constraints. In this review, we compare patterns of hostplant utilization with respect to nutrition and allelochemistry in representative holometabolous (lepidopteran) and hemimetabolous (orthopteran) species in order to identify those potential constraints. Overall in Lepidoptera greater molting efficiency and gut permeability, which enhance nutritional efficiency, result in higher exposure to allelochemicals and are associated with greater activity and inducibility of cytochrome P450 monoxygenase detoxication enzymes. In contrast, in Orthoptera, relative impermeability to allelochemicals due to the peritrophic membrane and cuticular sclerotization is associated with reduced nutritional efficiency and lower detoxication enzyme activity.     

Antoni van Leeuwenhoek and measuring the invisible: The context of 16th and 17th century micrometry

This article explores the impact of 16th and 17th-century developments in micrometry on the methods Antoni van Leeuwenhoek employed to measure the microscopic creatures he discovered in various samples collected from his acquaintances and from local water sources. While other publications have presented Leeuwenhoek's measurement methods, an examination of the context of his techniques is missing. These previous measurement methods, driven by the need to improve navigation, surveying, astronomy, and ballistics, may have had an impact on Leeuwenhoek's methods. Leeuwenhoek was educated principally in the mercantile guild system in Amsterdam and Delft. He rose to positions of responsibility within Delft municipal government. These were the years that led up to his first investigations using the single-lens microscopes he became expert at creating, and that led to his first letter to the Royal Society in 1673. He also took measures to train in surveying and liquid assaying practices existing in his time, disciplines that were influenced by Pedro Nunes, Pierre Vernier, Rene Descartes, and others. While we may never know what inspired Leeuwenhoek's methods, the argument is presented that there were sufficient influences in his life to shape his approach to measuring the invisible.     

Genotypic variation in foraging responses to environmental stimuli by honey bees,Apis mellifera

We experimentally tested a model predicting that colony-level genotypic diversity contributes to colonylevel foraging flexibility in honey bees. We established a colony into which we placed individually marked workers from three genetically distinct groups. The colony was placed in an enclosure that contained feeding stations with pollen and sugar syrup. Foraging resources, stores of pollen and the quantity of brood within the colony were varied temporally. Individual foragers switched between resource types in response to changes in relative resource quality and colony need, demonstrating flexibility in resource choice at the individual level. However, genetic groups within the colony varied in their tendency to collect pollen versus nectar, and in lability of response to changes in foraging stimuli. Our data suggest that within-colony genotypic diversity contributes to a resilient foraging response to environmental variation.     

Heat shock proteins and infection: interactions of pathogen and host.

Invasive microorganisms encounter defensive attempts of the host to starve, destroy and eliminate the infection. In experimental model systems aiming to imitate defensive actions of the host, microorganisms respond by the rapid acceleration in the rate of expression of heat shock and other stress proteins. Heat shock proteins (hsp) of most if not all pathogens are major immune targets for both B- and T-cells. Host cells involved in the defensive action cannot avoid exposure to their own reactive compounds, such as oxygen radicals, resulting in premature cell death and tissue damage. Long-term consequences to the host may include cancer. In cells in tissue culture, induction of host-specific hsps occurs upon exposure to oxidants and in viral infections. Drugs that bind to members of the hsp70 family induce peroxisome proliferation and hepatocarcinoma, but may open the way for the development of novel drugs in support of antimetabolite treatment of infections and cancer.     

Water or ice?--the challenge for invertebrate cold survival

The ecophysiology of cold tolerance in many terrestrial invertebrate animals is based on water and its activity at low temperatures, affecting cell, tissue and whole organism functions. The normal body water content of invertebrates varies from 40 to 90% of their live weight, which is influenced by water in their immediate environment, especially in species with a water vapour permeable cuticle. Water gain from, or loss to, the surrounding atmosphere may affect animal survival, but under sub-zero conditions body water status becomes more critical for overwinter survival in many species. Water content influences the supercooling capacity of many insects and other arthropods. Trehalose is known to maintain membrane integrity during desiccation stress in several taxa. Dehydration affects potential ice nucleators by reducing or masking their activity and a desiccation protection strategy has been detected in some species. When water crystallises to ice in an animal it greatly influences the physiology of nearby cells, even if the cells remain unfrozen. A proportion of body water remains unfrozen in many cold hardened invertebrates when they are frozen, which allows basal metabolism to continue at a low level and aids recovery to normal function when thawing occurs. About 22% of total body water remains unfrozen from calculations using differential scanning calorimetry (compared with ca 19% in food materials). The ratio of unfrozen to frozen water components in insects is 1:4 (1:6 for foods). Such unfrozen water may aid recovery of freezing tolerant species after a freezing exposure. Rapid changes in cold hardiness of some arthropods may be brought about by subtle shifts in body water management. It is recognised that cold tolerance strategies of many invertebrates are related to desiccation resistance, and possibly to mechanisms inherent in insect diapause, but the role of water is fundamental to them all. Detailed experimental studies are needed to provide information which will allow a more complete and coherent understanding of the behaviour of water in biological systems and aid the cryopreservation of a wide range of biological material.     

Circular proteoglycans from sponges: first members of the spongican family

Species-specific cell adhesion in marine sponges is mediated by a new family of modular proteoglycans whose general supramolecular structure resembles that of hyalectans. However, neither their protein nor their glycan moieties have significant sequence homology to other proteoglycans, despite having protein subunits equivalent to link proteins and to proteoglycan monomer core proteins, and glycan subunits equivalent to hyaluronan and to the glycosaminoglycans of hyalectans. In some species, these molecular components are assembled into a structure with a circular core formed by the link protein- and hyaluronan-like subunits. Besides their involvement in cell adhesion, these sponge proteoglycans, for which we propose the term spongicans, participate in signal transduction processes and are suspected to play a role in sponge self-nonself recognition. Their in vivo roles and the mild methods used to purify large amounts of functionally active spongicans make them ideal models to study the functions and possible new applications of proteoglycans in biomedical research. Received 21 May 2002; received after revision 5 July 2002; accepted 10 July 2002 RID="*" ID="*"Corresponding author.     

The epistemological virtues of assumptions: towards a coming of age of Boltzmann and Meinong’s objections to ‘the prejudice in favour of the actual’?

Two complementary debates of the turn of the nineteenth and twentieth century are examined here: the debate on the legitimacy of hypotheses in the natural sciences and the debate on intentionality and ‘representations without object’ in philosophy. Both are shown to rest on two core issues: the attitude of the subject and the mode of presentation chosen to display a domain of phenomena. An orientation other than the one which contributed to shape twentieth-century philosophy of science is explored through the analysis of the role given to assumptions in Boltzmann’s research strategy, where assumptions are contrasted to hypotheses, axioms, and principles, and in Meinong’s criticism of the privileged status attributed to representations in mental activities. Boltzmann’s computational style in mathematics and Meinong’s criticism of the confusion between representation and judgment give prominence to an indirect mode of presentation, adopted in a state of suspended belief which is characteristic of assumptions and which enables one to grasp objects that cannot be reached through direct representation or even analogies. The discussion shows how assumptions and the movement to fiction can be essential steps in the quest for objectivity. The conclusion restates the issues of the two debates in a contemporary perspective and shows how recent developments in philosophy of science and philosophy of language and mind can be brought together by arguing for a twofold conception of reference.     

Inhaled and exhaled nitric oxide

Inhaled nitric oxide (NO) is used to treat various cardiopulmonary disorders associated with pulmonary hypertension. The rationale is based on the fact that NO, given by inhalation, only dilates those pulmonary vessels that perfuse well-ventilated lung units. As a result, pulmonary gas exchange is improved while pulmonary vascular resistance is reduced and pulmonary blood flow is increased. Inhaled NO has been succesfully applied to treat persistent pulmonary hypertension of the newborn, reducing the need for extracorporeal life support. Although pulmonary hypertension and altered vasoreactivity contribute to profound hypoxaemia in adult and paediatric acute respiratory distress syndrome (ARDS), the benefit of inhaled NO still remains to be established in patients with ARDS. ARDS is a complex response of the lung to direct or indirect insults, leading to pulmonary vasoconstriction and various inflammatory responses. Recent randomized trials suggest that inhaled NO only causes a transient improvement in oxygenation. Whether this effect is important in the long-term management of ARDS remains to be established. NO, measured in the exhaled breath, is an elegant and non-invasive means to monitor inflammation of the upper and lower respiratory tract. In the normal upper airways, the bulk of exhaled NO originates from the paranasal sinuses. Exhaled NO is increased in nasal allergy and decreased in cystic fibrosis, nasal polyposis and chronic sinusitis. That NO production is increased in asthmatic airways is also well established. However, several questions still need to be addressed, in particular evaluation of the sensitivity and specificity of the measurement techniques, and assessment of the bronchodilator action of endogenous NO.     

Molecular basis for differences between human joints

The molecular program of a cell determines responses including induction or inhibition of genes for function and activity, and this is true of the cells within articular cartilage, a major functional component of the joint. While our studies have previously focussed on differences in the molecular programs of the cells within the superficial and deep zones, we have recently begun to focus on relative differences between joints, such as the knee and ankle. In the human, these joints vary greatly in their susceptibility to joint diseases, such as osteoarthritis (OA). We have predicted that there would be a molecular basis for differences between joints that could lead to differences in susceptibility to OA, if inherent pathways locked into the resident cells induce differences in their response to their environment. We have been able to show that there are differences between the matrix components and water content; these properties correspond to a higher equilibrium modulus and dynamic stiffness but lower hydraulic permeability and serve to make the ankle cartilage stiffer, slowing movement of molecules through the cartilage. In addition to these biochemical differences in the cartilage matrix, we have also identified relative differences in the strength of the response to stimulation of chondrocytes from knee and ankle. The stronger response of the knee chondrocytes includes factors that increase damage to the cartilage matrix, such as a depression of matrix synthesis and increased enzyme activity. This response by the knee chondrocytes results in enzyme damage to the matrix that the cells may not be able to repair, while the weaker response of the ankle chondrocytes may allow the cells to repair their matrix damage.     

Re-situating fieldwork and re-narrating disciplinary history in global mega-geomorphology

In 1985, more than thirty geomorphologists, planetary scientists, and remote sensing specialists gathered at a conference center in Oracle, Arizona, to discuss an emerging area of research that they called “mega-geomorphology.” Building on a conference of the same name held in London in 1981, they argued that new techniques of remote sensing and insights emerging from the study of extraterrestrial planets had created opportunities for geomorphology to broaden its spatial and temporal scope. This new approach was, however, neither unproblematic nor uncontested. In the discussions around mega-geomorphology that took place in the mid-1980s, the perceived conflict between the use of remote-sensing techniques to observe phenomena on vast spatial scales, on one hand, and the disciplinary centrality of fieldwork and field experience to geomorphology, on the other, was a recurrent theme. In response, mega-geomorphologists attempted to re-situate fieldwork and re-narrate disciplinary histories in such a way as to make remote sensing and planetary science not only compatible with geomorphological traditions but also means of revitalizing them. Only partially successful, these attempts reveal that the process of adopting a planetary perspective in geomorphology, as in other earth sciences, was neither straightforward nor inevitable. They also show how the field and fieldwork could remain central to geomorphology while also being extensively revised in light of new technical possibilities and theoretical frameworks.