bluuebunny/crossref_metadata_2025 huggingface dataset:
Preconditions for Requisite Holism of Information Bases for the Invention-Innovation Process Management
Authors: Mulej Matjaž , Potocan Vojko , Ženko Zdenka
Published: May 2010

Innovation belongs to main open issues of the modern business. Information for the invention-innovation process is an even more open issue, because informed guessing about the future needs of future potential customers is a best case scenario. This is especially true in SMEs with their limited human resources, but the market provides no allowances for them anyway. SMEs are 99% of all organizations in EU or Slovenia. They provide +50% of jobs and +70% of new jobs. But they can hardly survive with no or poor innovation capacity, including a requisitely holistic consideration of the entire invention-innovation-diffusion process. The information system must be adapted to this fact in order to support business quality in line with the demands of the modern rather global than local market. But the usual enterprise information systems cover better the daily routine and past performance than future and innovation issues.
Virtual Organizing Professional Learning Communities through a Servant-Leader Model of Appreciative Coaching
Authors: Hou Vat Kam
Published: May 2010

This case investigates a set of empowerment concerns in the context of transforming classes of student and teacher learners (considered as department-wide learning units in higher education) into professional learning communities (PLCs). In particular, we are interested in enhancing student learning through designing a collaborative learning environment in support of problem-based learning, based on the concept of virtual organizing the various PLCs distributed throughout a higher educational institute. Of specific interest in our exploration is the generative potential of a servant-leader model of student-centered education in support of the PLCs nurtured by the development practice of appreciative coaching adapted from the established positive change paradigm of appreciative inquiry.
ERP Systems Supporting Lean Manufacturing in SMEs
Authors: Halgeri Pritish , McHaney Roger , Pei Z. J.
Published: May 2010

Small and medium enterprises (SMEs), more than ever, are being forced to compete in a global economy with increasingly complex challenges. This new economy has forced SMEs to become more responsive and agile in operational, tactical and strategic areas while requiring thoughtful integration between business functions and manufacturing/ production/ service operations. Enterprise Resource Planning (ERP) and Lean manufacturing are two production control methodologies that have been implemented in various ways. In early incarnations, ERP systems were considered a hindrance to Lean manufacturing efforts and were criticized for encouraging large inventories and slower production. The explosive growth of e-business methodologies and the resulting pressure to become nimble and embrace rapid change forced many SMEs to rethink their production approaches, particularly in regard to where they stand in relation to these two methodologies. Over time, ERP vendors recognized the power and advantages of Lean manufacturing and developed ways to incorporate Lean-related features into their software. The main objective of this chapter is to explore how ERP and Lean methodologies can coexist in SMEs. The chapter discusses misconceptions about the fit between ERP and Lean then summarizes differences and synergies between the two methodologies. The chapter emphasizes how linking ERP and Lean methods can lead to competitive advantage then explores key Lean toolsets available in leading ERP systems used by SMEs. Further focus is provided with additional insight on several leading ERP vendors offering Lean-enabled software modules. These include Oracle, TTW WinMan and Pelion Systems.
Software for Small-to- Medium Enterprises
Authors: Král Jaroslav , Žemlicka Michal
Published: May 2010

Small-to-medium enterprises (SME) have specific requirements on the software systems (SWS) they use. SME have a limited possibility to design stable business processes as they have limited resources and data to design the processes properly. Moreover, SME must be able to adapt itself dynamically to changing business conditions and must, due to limited resources, reuse legacy systems and third-party products. SME cannot apply the higher levels of CMM and to define precisely its business processes, as SME cannot have enough data and experience. The solution of this issue or weakening of its consequences can be based on the variant of service-oriented architecture (SOA) discussed next. A proper use of modern software systems depends on the skills and knowledge of (end) users of the systems. The extent of a new software-oriented knowledge of the users needed to specify, install, and use the systems depends on the architecture of the system. We further show that a properly used SOA can substantially reduce the need to learn new knowledge at users’ side. The kernel of the solution should be based on the SOA-based generalization of the concept of usability and on a technical turn enabling agility of business processes. The solution can simplify the development of tools enabling the activation of inhibited user knowledge via flexible prototyping supporting agile business processes and learning by doing. The solution further enables new business turns and has many technical advantages. Our solution is especially preferable for small-to-medium enterprises, but it should be applied in very large enterprises for different reasons.
Towards a Wider Application of the Systems Approach in Information Systems and Software Engineering
Authors: Petkov Doncho , Edgar-Nevill Denis , Madachy Raymond , O’Connor Rory
Published: May 2010

The chapter provides possible directions for the wider application of the systems approach to information systems development. Potential improvement of software development practices is linked by some leading experts to the application of more systemic ideas. However, the current state of the practice in software engineering and information systems development shows the urgent need for improvement through greater application of systems thinking.
Forming Trust in Virtual Writing Teams
Authors: Williams Sean D.
Published: May 2010

This chapter explores collaborative writing in virtual teams, and, particularly, trust formation in virtual writing teams, to help those who create or work in virtual writing teams to understand the importance of trust. In order to build the case for trust as the key component in teams, the chapter presents important background on teams as a general concept. In particular, it considers the constituents of quality teams, which include small team size, diverse team membership, interdependent relationships, shared team vision, articulated processes, and performance orientation. The chapter then elaborates on the role of trust in teams, presenting it as the key feature for any type of team environment. Based on this background, the chapter then differentiates the general concept of teams from virtual teams in particular, arguing that virtual teams must address specific considerations in order to build trust. Such considerations include the composition of the team, where team members possess a propensity to trust; the proper use of technology in the virtual team, so that the medium matches the communicative need; and social presence, or the ways that virtual teams can build trust by using communication behaviors to demonstrate to others that they share understanding. The chapter combines the general team considerations with the virtual team considerations into a rubric for building strong virtual teams based upon four major categories: team traits, team actions, individual traits, and environment traits. The chapter concludes with suggestions for future study.
Trends in long-term gaseous mercury observations in the Arctic and effects of temperature and other atmospheric conditions
Authors: Cole A. S. , Steffen A.
Published: May 2010

Abstract. Gaseous elemental mercury (GEM) measurements at Alert, Canada, from 1995 to 2007 were analyzed for statistical time trends and for correlations with meteorological and climate data. A significant decreasing trend in annual GEM concentration is reported at Alert, with an estimated slope of −0.0086 ng m−3 yr−1 (−0.6% yr−1) over this 13-year period. It is shown that there has been a shift in the month of minimum mean GEM concentration from May to April due to a change in the timing of springtime atmospheric mercury depletion events (AMDEs). These AMDEs are found to decrease with increasing local temperature within each month, both at Alert and at Amderma, Russia. These results support the temperature dependence suggested by previous experimental results and theoretical kinetic calculations on both bromine generation and mercury oxidation and highlight the potential for changes in Arctic mercury chemistry with climate. A correlation between total monthly AMDEs at Alert and the Polar/Eurasian Teleconnection Index was observed only in March, perhaps due to higher GEM inputs in early spring in those years with a weak polar vortex. A correlation of AMDEs at Alert with wind direction supports the origin of mercury depletion events over the Arctic Ocean, in agreement with a previous trajectory study of ozone depletion events. Interannual variability in total monthly depletion event frequency at Alert does not appear to correlate significantly with total or first-year northern hemispheric sea ice area or with other major teleconnection patterns. Nor do AMDEs at either Alert or Amderma correlate with local wind speed, as might be expected if depletion events are sustained by stable, low-turbulence atmospheric conditions. The data presented here – both the change in timing of depletion events and their relationship with temperature – can be used as additional constraints to improve the ability of models to predict the cycling and deposition of mercury in the Arctic.
Comprehensive description of the carbon cycle of an ancient temperate broadleaved woodland
Authors: Fenn K. , Malhi Y. , Morecroft M. , Lloyd C. , Thomas M.
Published: May 2010

Abstract. There exist very few comprehensive descriptions of the productivity and carbon cycling of forest ecosystems. Here we present a description of the components of annual Net Primary Productivity (NPP), Gross Primary Productivity (GPP), autotrophic and heterotrophic respiration, and ecosystem respiration (RECO) for a temperate mixed deciduous woodland at Wytham Woods in southern Britain, calculated using "bottom-up" biometric and chamber measurements (leaf and wood production and soil and stem respiration). These are compared with estimates of these parameters from eddy-covariance measurements made at the same site. NPP was estimated as 7.0±0.8 Mg C ha−1 yr−1, and GPP as 20.3+1.0 Mg C ha−1 yr−1, a value which closely matched to eddy covariance-derived GPP value of 21.1 Mg C ha−1 yr−1. Annual RECO was calculated as 18.9±1.7 Mg C ha−1 yr−1, close to the eddy covariance value of 19.8 Mg C ha−1 yr−1; the seasonal cycle of biometric and eddy covariance RECO estimates also closely matched. The consistency between eddy covariance and biometric measurements substantially strengthens the confidence we attach to each as alternative indicators of site carbon dynamics, and permits an integrated perspective of the ecosystem carbon cycle. 37% of NPP was allocated below ground, and the ecosystem carbon use efficiency (CUE, = NPP/GPP) calculated to be 0.35±0.05, lower than reported for many temperate broadleaved sites.
Carbon dioxide fluxes over an ancient broadleaved deciduous woodland in southern England
Authors: Thomas M. V. , Malhi Y. , Fenn K. M. , Fisher J. B. , Morecroft M. D. , Lloyd C. R. , Taylor M. E. , McNeil D. D.
Published: May 2010

Abstract. We present results from a study of canopy-atmosphere fluxes of carbon dioxide from 2007 to 2009 above a site in Wytham Woods, an ancient temperate broadleaved deciduous forest in southern England. Gap-filled Net Ecosystem Exchange (NEE) data were partitioned into Gross Primary Productivity (GPP) and ecosystem respiration (Re) and analysed on daily, monthly and annual timescales. Over the continuous 24 month study period annual GPP was estimated at 21.1 Mg C ha−1 yr−1 and Re at 19.8 Mg C ha−1 yr−1; Net Ecosystem Productivity (NEP) was 1.2 Mg C ha−1 yr−1. These estimates are very consistent with independent bottom-up estimates derived from Net Primary Productivity (NPP) and flux chamber measurements in 2008 (GPP=20.3±1.0 Mg C ha−1 yr−1, Re=18.9±1.7 Mg C ha−1 yr−1, biomass increment =~1.4 Mg C ha−1 yr−1). Interannual variability of seasonal NEP was predominantly driven by changes in ecosystem respiration, whereas GPP remained similar for equivalent months in different years. Although solar radiation was the largest influence on daytime CO2 fluxes (R2=0.53 for the summer months), interannual variation in Re appeared to be driven by temperature. Our findings suggest that this ancient woodland site is currently a substantial sink for carbon, resulting from continued growth that is probably a legacy of past management practices abandoned over 40 years ago. Our GPP and Re values are generally higher than other broadleaved temperate deciduous woodlands and may represent the influence of the UK's maritime climate, or the particular species composition of this site. The carbon sink value of Wytham Woods supports the protection and management of temperate deciduous woodlands (including those managed for conservation rather than silvicultural objectives) as a strategy to mitigate atmospheric carbon dioxide increases.
Telerehabilitation: State-of-the-Art from an Informatics Perspective
Authors: Parmanto Bambang , Saptono Andi
Published: May 2010

Abstract to follow --please check back
The Impact of an Application of TelerehabilitationTechnology on Caregiver Burden
Authors: Tindall Lyn R. , Huebner Ruth A.
Published: May 2010

The objective of this research was to assess the effects of an application of telerehabilitation reducing time and financial obligation on caregiver burden among eleven caregivers of elderly persons with Parkinson’s disease. Clients (care receivers) participated in speech therapy delivered via videophones in their homes; the protocol required 16 treatments delivered four times a week for four weeks. At the conclusion of treatment, caregivers completed a structured interview about the impact of telerehabilitation on time and financial aspects of the burden of care. On average, this speech therapy protocol delivered by videophones saved 48 hours of time, more than 92 hours of work time, and $1024 for each caregiver. Savings were significant and previous research demonstrated nearly equal outcomes using the videophone delivery method. Implications for practice and research are discussed.Keywords: Telerehabilitation, Speech Therapy, Parkinson’s Disease.
A Pilot Telerehabilitation Program: Delivering Early Intervention Services to Rural Families
Authors: Cason Jana
Published: May 2010

The enTECH Telerehabilitation Program explored the use of telerehabilitation as an alternative service delivery model for early intervention therapy services. Utilizing the Kentucky Telehealth Network, two families living in rural Kentucky received occupational therapy services over a 12-week period. Following program implementation, qualitative data was collected using participant journals and interviews. Data analysis identified three thematic categories related to the program: benefits/strengths, challenges/weaknesses, and recommendations for program improvement. Results of the program evaluation indicated that telerehabilitation has the potential to cost-effectively meet the therapeutic needs of children living in rural areas where provider shortages exist. The enTECH Telerehabilitation Program serves as a model for how telerehabilitation can be used to deliver early intervention services to ameliorate health disparities and improve access to rehabilitation services. Keywords: Telerehabilitation, Occupational Therapy, Rural, Early Intervention, Children, Program Evaluation, Cost Analysis
Telerehabilitation: Policy Issues and Research Tools
Authors: Seelman Katherine D. , Hartman Linda M.
Published: May 2010

The importance of public policy as a complementary framework for telehealth, telemedicine, and by association telerehabilitation, has been recognized by a number of experts. The purpose of this paper is to review literature on telerehabilitation (TR) policy and research methodology issues in order to report on the current state of the science and make recommendations about future research needs. An extensive literature search was implemented using search terms grouped into main topics of telerehabilitation, policy, population of users, and policy specific issues such as cost and reimbursement. The availability of rigorous and valid evidence-based cost studies emerged as a major challenge to the field. Existing cost studies provided evidence that telehomecare may be a promising application area for TR. Cost studies also indicated that telepsychiatry is a promising telepractice area. The literature did not reference the International Classification on Functioning, Disability and Health (ICF). Rigorous and comprehensive TR assessment and evaluation tools for outcome studies are tantamount to generating confidence among providers, payers, clinicians and end users. In order to evaluate consumer satisfaction and participation, assessment criteria must include medical, functional and quality of life items such as assistive technology and environmental factors. Keywords: Telerehabilitation, Telehomecare, Telepsychiatry, Telepractice
Telerehabilitation Clinical and Vocational Applications for Assistive Technology: Research, Opportunities, and Challenges
Authors: Schmeler Mark R. , Schein Richard M. , McCue Michael , Betz Kendra
Published: May 2010

Rehabilitation service providers in rural or underserved areas are often challenged in meeting the needs of their complex patients due to limited resources in their geographical area. Recruitment and retention of the rural clinical workforce are beset by the ongoing problems associated with limited continuing education opportunities, professional isolation, and the challenges inherent in coordinating rural community healthcare. People with disabilities who live in rural communities also face challenges accessing healthcare. Traveling long distances to a specialty clinic for necessary expertise may be troublesome due to inadequate or unavailable transportation, disability specific limitations, and financial limitations. Distance and lack of access are just two threats to quality of care that now being addressed by the use of videoconferencing, information exchange, and other telecommunication technologies that facilitate telerehabilitation. This white paper illustrates and summarizes clinical and vocational applications of telerehabilitation. We provide definitions related to the fields of telemedicine, telehealth, and telerehabilitation, and consider the impetus for telerehabilitation. We review the telerehabilitation literature for assistive technology applications; pressure ulcer prevention; virtual reality applications; speech-language pathology applications; seating and wheeled mobility applications; vocational rehabilitation applications; and cost effectiveness. We then discuss external telerehabilitation influencers, such as the positions of professional organizations. Finally, we summarize clinical and policy issues in a limited context appropriate to the scope of this paper. Keywords: Telerehabilitation, Telehealth, Telemedicine, Telepractice
Telerehabilitation Technologies: Accessibility and Usability
Authors: Pramuka Michael , Van Roosmalen Linda
Published: May 2010

In the fields of telehealth and telemedicine, phone and/or video technologies are key to the successful provision of services such as remote monitoring and visits. How do these technologies affect service accessibility, effectiveness, quality, and usefulness when applied to rehabilitation services in the field of telerehabilitation? To answer this question, we provide a overview of the complex network of available technologies and discuss how they link to rehabilitation applications, services, and practices as well as to the telerehabilitation end-user. This white paper will first present the numerous professional considerations that shape the use of technology in telerehabilitation service and set it somewhat apart from telemedicine. It will then provide an overview of concepts essential to usability analysis; present a summary of various telerehabilitation technologies and their strengths and limitations, and consider how the technologies interface with end users’ clinical needs for service accessibility, effectiveness, quality, and usefulness. The paper will highlight a conceptual framework (including task analyses and usability issues) that underlies a functional match between telerehabilitation technologies, clinical applications, and end-user capabilities for telerehabilitation purposes. Finally, we will discuss pragmatic issues related to user integration of telerehabilitation technology versus traditional face-to-face approaches. Key Words: Remote, Technology, Usability, Accessibility, Decision Factors, Decision Support
Synaptic Integration
Authors: Etherington Sarah J , Atkinson Susan E , Stuart Greg J , Williams Stephen R
Published: May 2010

Neurons in the brain receive thousands of synaptic inputs from other neurons. Synaptic integration is the term used to describe how neurons ‘add up’ these inputs before the generation of a nerve impulse, or action potential. The ability of synaptic inputs to effect neuronal output is determined by a number of factors, including the size, shape and relative timing of electrical potentials generated by synaptic inputs, the geometric structure of the target neuron, the physical location of synaptic inputs within that structure, as well as the expression of voltage‐gated channels in different regions of the neuronal membrane. The process of synaptic integration is therefore modulated at multiple levels, contributing to the diverse and complex computational powers of the functioning brain.

Key Concepts:

Neurons within a neural network receive information from, and send information to, many other cells, at specialised junctions called synapses.

Synaptic integration is the computational process by which an individual neuron processes its synaptic inputs and converts them into an output signal.

Neurons are specialised for electrical signalling, with the main neuronal input signal (synaptic potentials) and the main neuronal output signal (action potentials) both involving transient changes in the size of the electrical potential across the neuronal membrane.

Synaptic potentials occur when neurotransmitter binds to and opens ligand‐operated channels in the dendritic membrane, allowing ions to move into or out of the cell according to their electrochemical gradient.

Synaptic potentials can be either excitatory (increasing the probability of action potential firing) or inhibitory (reducing the probability of action potential firing) depending on the direction and charge of ion movement.

Action potentials occur if the summed synaptic inputs to a neuron reach a threshold level of depolarisation and trigger regenerative opening of voltage‐gated ion channels.

Synaptic potentials are often brief and of small amplitude, therefore summation of inputs in time (temporal summation) or from multiple synaptic inputs (spatial summation) is usually required to reach action potential firing threshold.

Nonlinear summation of synaptic potentials occurs when a synaptic potential changes the driving force for ion movement and therefore the amplitude of subsequent synaptic potentials.

The impact of a synaptic input on neuronal output depends on its location within the dendritic tree, because synaptic potentials are attenuated as they spread passively through neuronal processes.

Dendritic voltage‐gated ion channels may open or close in response to the membrane potential change during a synaptic potential, thereby altering (amplifying or attenuating) the potential's amplitude or time course.
Cytochrome
c
Oxidase
Authors: Wikström Mårten
Published: May 2010

Cytochrome
c
oxidase

is the key enzyme of cell respiration in all eukaryotes and many prokaryotes. The

cytochrome
c
oxidases

belong to the haem–copper superfamily of structurally and functionally related enzymes; though related in structure, some bacterial variants lack amino acid residues that are known to be obligatory for the function of the members of the main family. All
haem–copper oxidases
have a unique bimetallic active site catalysing reduction of dioxygen (O
2
) to water and an adjacent second haem group that donates electrons to this site. Here, the mechanism of O
2
reduction is reviewed. The membrane‐bound enzyme couples this reaction to translocation of protons across the membrane, and thus functions as a primary energy transducer that contributes to the formation of ATP (adenosine triphosphate) in aerobic life. The most recent knowledge of the function of this ‘proton pump’ is discussed. It is concluded that

cytochrome
c
oxidase

is an electrostatic energy‐transducing machine with high efficiency.

Key Concepts:

Cytochrome
c
oxidase is an electrostatically coupled energy transducer.

The high affinity for O
2
is due to kinetic ligand trapping.

O
2
reduction in cell respiration yields no reactive oxygen species.
Starch and Starch Granules
Authors: Smith Alison M
Published: May 2010

Starch is the main form in which plants store carbon. It occurs as semi‐crystalline granules composed of two polymers of glucose, called amylose and amylopectin. Depending on the plant organ, it can act as a store of carbon for lengths of time as short as a day (e.g. in leaves) or as long as many years (e.g. in dormant seeds). Starch granules are characterised by internal growth rings. There is enormous variation in granule size and shape between plant organs, and between species. Starch is the major carbohydrate of nutritional importance in the diet: it is degraded to glucose by amylases in the mouth and small intestine. When cooked in water, starch forms gels or pastes that have a wide range of industrial applications in both food and nonfood industries.

Key Concepts:

Starch is the main form in which plants store carbon.

Starch occurs as semicrystalline granules, composed of branched and linear polymers of glucose.

Starch granules vary in size and shape between plant organs and between species.

The distinctive morphology and anatomy of starch granules enables the identification of plant remains in food, forensic and archaeological samples.

Starch is the main component of the harvested parts of many crops, including cereals, peas and beans, potatoes and cassava.

Starch is the main carbohydrate of nutritional importance in the human diet.

When cooked in water, starch granules swell to form gels or pastes that are widely used in food and nonfood industries.

Major uses for starch include a thickener in processed foods, and in the manufacture of paper, biodegradable plastics and adhesives.

Starch is often modified after extraction to generate properties desirable for specific industrial purposes: there is interest in breeding new crops in which the native starch already has these properties.
Protein–Ligand Interactions: Thermodynamic Basis and Mechanistic Consequences
Authors: Fisher Harvey F
Published: May 2010

It is difficult to imagine any biological process that is not initiated by the binding of some chemical entity (or ‘ligand’) to a protein. Thus, enzymatic catalysis, signal transduction, ion channel activity, immune responses and the various events involved in genetic expression are all obvious examples of events which, at the molecular level, must begin with the binding of some ligand to a specific binding site on a protein molecule. Furthermore, as each one of these processes proceeds along its reaction pathway, modulation of the affinities of such ligands, positive and negative interactions caused by the binding of other ligands and the release of these ligands either in their original or in altered form constitute obligatory steps in the driving forces and controlling restraints that adapt them to their specific tasks. We extend the basic conceptions set forth in this article to a more detailed level focused on the fundamental nature of ligand–ligand interactions of a protein–ligand complex and the energetic mechanistic consequences to which they lead.

Key Concepts:

Every biological reaction is initiated by a protein–ligand binding step.

Such reactions never involve the binding of only a single ligand or a single step.

The binding of two ligands to the same protein always involves a mutual interaction.

The product of a ligand‐binding reaction is a new entity in itself; its structure and its properties may differ substantially from the simple sum of those of its initial components.

The concept of G Weber's ‘thermodynamic square’ permits the evaluation of a variety of interaction parameters.

Patterns of interaction parameters provide a basis for exploring ligand‐binding energy transduction.

Measurement of ligand‐binding heat by techniques using higher levels of mathematical integration provide more detailed dissection into parameters such as enthalpy, entropy, heat capacity and their corresponding interaction terms.

The ‘fluctuating protein’ concept suggests that protein reactions proceed as multiple traces on multidimensional free‐energy landscapes.

Consequences of the thermodynamic complexity of ligand binding suggest new views of such processes as enzymatic catalysis, signalling events and evolutionary aspects.
Silica
Authors: Perry Carole C
Published: May 2010

The element silicon (Si) is used by all living organisms either in molecular processes or in the formation of the mineral silica. The mineral is found in single cell organisms (e.g. radiolarian, diatoms, dinoflagellates and algae) through molluscs (e.g. limpets) to higher plants and primitive animals such as sponges. It is formed from an environment that is undersaturated with respect to Si and under conditions of around neutral pH and low temperature,
c
. 4–40°C. The mineral can be formed both intra‐ or extracellularly and specific biochemicals involved with mineral deposition include lipids, proteins (including heavily posttranslationally modified proteins), long‐change polyamines and carbohydrates. Knowledge of the complete genome for some species is providing opportunities to uncover the precise mechanisms of element uptake, transport and deposition although much still remains to be understood.

Key Concepts:

Silicon is an essential element for many if not all organisms.

A range of biomolecules/biopolymers are used to control and regulate silica precipitation in the natural environment.

The presence of biogenic silica in an organism confers functional properties on that organism which may include structural/mechanical support and/or defence against biotic or abiotic environmental stresses.

Much remains to be understood in respect of how the element is transported, concentrated and spatially organised within organisms as well as the effect the presence of the element/mineral has on other cellular functions.
Acute Myelogenous Leukaemia
Authors: Lichtman Marshall A
Published: May 2010

Acute myelogenous leukaemia is the result of a malignant transformation of a single primitive multipotential marrow haematopoietic cell, converting it to a leukaemic stem cell. This neoplastic transformation imparts a growth and survival advantage to the cell clone that emerges. Leukaemic cells fill the haematopoietic cords of marrow. The functional result of this alteration is to impair normal blood cell production in the marrow, leading to a profound decrease in normal red cells (anaemia), white cells (leucopaenia) and platelets or thrombocytes (thrombocytopaenia) in the blood. The disease is rapidly progressive, unless treated promptly. Therapy usually consists of at least two drugs, cytosine arabinoside and an anthracycline antibiotic (e.g. daunomycin). The response of the disease to treatment is dependent on several factors but the two most compelling are the age at diagnosis and the cytogenetic and genetic features of the cells with older age and unfavourable chromosomal karyotypes decreasing the proportion of long‐term remissions.

Key Concepts:

Cancer of any type is the result of a series of gene mutations in a single tissue cell.

Acute myelogenous leukaemia, like all cancers, originates in a single tissue cell, in this case within haematopoietic tissue.

The incidence of acute myelogenous leukaemia can be increased by the inheritance of predisposition genes that are unapparent (nonsyndromic familial cases) or apparent as manifest by syndromic cases, such as Fanconi anaemia.

Leukaemic cells accumulate because they have a proliferative and survival advantage compared to normal cells.

It is estimated that approximately one trillion leukaemic cells are present at diagnosis.

Very small proportions of these cells are leukaemic stem cells, which sustain leukaemic haematopoiesis.

Acute myelogenous leukaemia stem cells have multipotential haematopoietic lineage potential. Thus, they can differentiate into leukaemic precursor cells of all haematopoietic lineages. The predominance of one or two leads to the phenotypic classification of acute myelogenous leukaemia (e.g. erythroid, monocytic, megakaryocytic and myelomonocytic).

The accumulation of leukaemic cells in the marrow secondarily suppresses normal blood cell development.

Chemotherapy is predicated on the coexistence of normal haematopoietic stem cells and leukaemic stem cells in the marrow.

Suppression of leukaemic cell accumulation by at least three logs by chemotherapy can, in many cases, result in the release of inhibition of normal stem cells and a return of normal haematopoiesis for a variable time.
Permeabilised Mammalian Cell Systems for Protein Synthesis
Authors: Tavender Timothy J
Published: May 2010

The use of semipermeabilised cells allows the study of complex intracellular processes such as protein translocation, folding, glycosylation, disulfide bond formation and degradation in a system amenable to experimental manipulation. Semipermeabilised cells can be combined with an

in vitro

translation system to synthesise endoplasmic reticulum (ER) targeted proteins from custom made messenger
ribonucleic acid
(mRNA). The ability to manipulate the translated protein means that the effect of changes to the primary amino acid sequence on protein folding and assembly can be readily assessed. Semipermeabilised cells can be prepared from cell lines expressing elevated or diminished levels of ER‐resident proteins and can also be pretreated with chemical modifiers of ER processes. Using such approaches, it is possible to examine the influence of various ER pathways on folding and posttranslational modification of individual secretory proteins.

Key concepts:

Semipermeabilised cells possess an intact, functional endoplasmic reticulum and are free of cytosol and endogenous mRNA.

Secretory proteins translated in the presence of semipermeabilised cells are translocated and posttranslationally modified as in intact cells.

Use of an
in vitro
translation system allows complete user manipulation of translated protein sequences.
Watson–Crick Base Pairs and Nucleic Acids Stability
Authors: Marky Luis A , Lee Hui‐Ting , Garcia Angel
Published: May 2010

Watson–Crick base pairs are crucial in the formation of double‐helical
deoxyribonucleic acid
(DNA) and in the storage of genetic information. They comprise two of the most common geometries involving the pairing of deoxyadenosine (dA) with deoxythymidine (dT) and deoxyguanosine (dG) with deoxycytidine (dC) through the formation of two and three hydrogen bonds, respectively. The complementarity of the antiparallel strands forming a double helix is crucial in DNA replication since the complementary strand is synthesised by adding the Watson–Crick complementary bases of the parent strand. The hybridisation of DNA or DNA–RNA (
ribonucleic acid
) strands is widely used in biotechnology and molecular biology for multiple purposes. The stability of a nucleic acid helix depends on its sequence, conformation, hydration and solution conditions, and it is measured by temperature‐dependent techniques, such as UV (ultraviolet) melting. Examples of oligonucleotide helices with chemical modifications are provided to indicate how these modifications affect the overall stability of a DNA molecule.

Key Concepts:

Base pairs are two nucleotide bases interacting via hydrogen bonding.

Bulge is a nonpaired nucleotide base in a double‐stranded nucleic acid.

Hybridisation is a process where two complementary strands interact via base pairing.

Nucleic acid conformation is the three‐dimensional structural arrangement of a double‐helical nucleic acid.

Nucleic acid modification is the incorporation, removal or substitution of a chemical group on the natural occurring nucleic acids.

Melting curves are the optical changes of a nucleic acid or protein‐like molecules as a function of temperature.

Stability of nucleic acids is the resistance of nucleic acid duplex to undergo unfolding, proportional to the magnitude of Δ
G
.

Thermal stability is the ability of a nucleic acid duplex to resist temperature denaturation.

Unfolding thermodynamic profile is the free energy (Δ
G
∘
), enthalpy (Δ
H
) and entropy (Δ
S
) parameters associated with the unfolding of a nucleic acid or protein molecule.

Cooperativity refers to the number of base pairs that are broken simultaneously in the unfolding of a nucleic acid or protein.
Evolution of Ecosystems: Terrestrial
Authors: Elias Scott A
Published: May 2010

As life has evolved on Earth, it has been organised into biological communities of increasing complexity. The earliest evidence of true terrestrial ecosystems comes from the Ordovician Period, about 460 million years ago. During the Paleozoic, terrestrial animal life progressed from the earliest arthropods and tetrapod vertebrates through many of the modern invertebrate orders, amphibians and reptiles. The extinction event at the end of the Permian allowed new groups of plants and animals to dominate, including gymnosperms and dinosaurs. The mass extinction at the end of the Cretaceous likewise allowed angiosperms and mammals to come to dominance in the Cenozoic. From an ecological perspective, perhaps the most significant evolutionary event during the Quaternary Period was the rise of our own species,

Homo sapiens

, as we have reshaped the biotic world during the time since the last glaciation. The fossil evidence clearly shows that biological communities are temporary associations of species that shift in response to environmental disturbances.

Key Concepts:

The history of life on Earth has been punctuated by a series of mass extinctions that have ended the prominence of more primitive groups and given new groups the opportunity to flourish.

Biological communities are temporary associations of species that shift in response to environmental disturbances.

The important time scales of ecological change are centuries and millennia: intervals too long to be observed by one generation of scientists.

Biodiversity adds to the stability of ecosystems.
Plant Nitrogen Nutrition and Transport
Authors: Miller Anthony J
Published: May 2010

Nitrogen (N) is a major plant nutrient and is available in soil chiefly as nitrate (NO
3
−
), ammonium and amino acids. N is acquired through roots and then transported around the plant or it can be combined with carbon to produce amino acids (assimilation) before being redistributed. Most plant cells can assimilate N and any not required for growth is stored as protein. Reserve N can be accumulated as the photosynthetic enzyme
Rubisco
and species‐specific storage proteins in vegetative tissue or seed endosperm. Cellular storage of NO
3
−
occurs in the vacuole, where it is important for driving osmotic expansion growth. The amount of these stored forms defines a plant's N status. Some structural materials like lignin contain a high proportion of N, but this is not stored and is not remobilised. Some plants form a symbiotic relationship with bacteria in specialised nodules to enable the direct assimilation of gaseous N.

Key Concepts:

Nitrogen supply limits plant growth in almost all natural environments.

The soil available form of N depends on factors like soil type, weather and temperature with NO
3
−
dominating temperate climates.

Some plants form a specialised symbiosis with bacteria to fix atmospheric N.

Agriculture includes the addition of N fertiliser to optimise yield.

Regulation of plant carbon and N metabolism is carefully coordinated for normal growth and development.

Changes in plant N supply trigger alterations in a huge number of genes resulting in changes in morphology, growth rate and development.

A change in the phosphorylation status of some plasma membrane NO
3
−
and ammonium transporter proteins provides a receptor mechanism that links uptake to external availability.
Evolution of C2H2 Zinc‐finger Gene Families in Mammals
Authors: Dhwani Tadepally Hamsa , Aubry Muriel
Published: May 2010

The C2H2 zinc‐finger encode the largest class of transcription factors and second largest gene family in the human genome. Based on the presence or absence of an
N
‐terminal effector domain, they are grouped into different subfamilies. The KRAB (Kruppel‐associated box) C2H2‐ZNF subfamily, found specifically in tetrapods, constitutes about half of these genes in human and mouse. Often found in clusters, the C2H2‐ZNF genes have evolved independently in various species at the level of genes, effector motifs and the zinc‐finger region. More specifically, in recent times there has been an unprecedented expansion of these genes in mammalian genomes. Cross‐species comparisons reveal a series of dynamic duplications and gene loss events that led to rapid and lineage‐specific evolution of these genes in different vertebrate genomes. Both lineage‐specific variation in the number, sequence and subfamilies of C2H2‐ZNF genes and differential expansion in genomes may be determinant for functions related to speciation.

Key Concepts:

C2H2‐ZNF genes are ubiquitously present in all organisms ranging from bacteria to human and are often arranged in a clustered organisation.

A massive expansion in the number of C2H2‐ZNF genes occurred from yeast to primates.

Besides gene duplication, loss and to a certain extent pseudogenisation are contributing factors in the evolution of the C2H2‐ZNF gene family.

C2H2‐ZNF genes follow the ‘Birth and Death’ model of evolution contributing to differential and independent evolution of the C2H2‐ZNF genes in different genomes.

C2H2‐ZNF genes encode DNA‐ and RNA‐binding proteins presumably involved in gene expression as transcription factors or possibly RNA regulators.

Members of the C2H2‐ZNF family are characterised by tandemly repeated zinc‐finger motifs involved in nucleic acid binding and are grouped into different subfamilies based on their
N
‐terminal regulatory domains which include SCAN, KRAB, BTB, HOMEO and SET domains.

Because of their tandemly repeated zinc‐finger motifs, members of the C2H2‐ZNF family are named multifingered C2H2‐ZNF genes. These motifs are prone to be duplicated, lost or to degenerate during evolution.

The KRAB and SCAN domains are solely confined to vertebrates. In all vertebrates, the KRAB domain is found within C2H2‐ZNF proteins.

The KRAB domain‐encoding C2H2‐ZNF genes define the largest and a rapidly evolving C2H2‐ZNF subfamily in vertebrates and particularly in mammals.

The study of the evolution of the C2H2‐ZNF genes in various genomes may help to elucidate their possible role in functions associated with speciation.
Drosophila
Innate Immunity
Authors: Moule Madeleine G , Schneider David S
Published: May 2010

Drosophila melanogaster

is a useful model for studying innate immunity that has been used to identify and characterise the role of the Toll pathway and nuclear factor‐κB (NFκB) signalling in both insects and mammals. When flies encounter a pathogen, two pattern recognition pathways, Toll and imd, induce a humoral immune response consisting primarily of antimicrobial peptide production.

Drosophila

also has a cellular immune response in which phagocytic cells engulf and destroy foreign invaders; a melanisation response that generates reactive oxygen species; and an antiviral RNAi (
ribonucleic acid
interference) response. Application of

Drosophila

model has already taught us much about innate immunity. As we expand our research to take a more comprehensive look at how a host responds to infection and what determines the outcome of that infection we can continue to learn more about this complex system from the simple fruitfly.

Key Concepts:

Drosophila
can be used as a model system to study the innate immune system.

The
Drosophila
immunity consists of humoral, cellular and melanisation responses.

The humoral immune response involves antimicrobial peptide production, which is induced by the recognition of pathogen‐associated molecular patterns (PAMPs) by patter recognition receptors (PRRs).

Two NFκB signalling pathways, Toll and imd, regulate the AMP response to fungal, bacterial and viral pathogens.

The cellular immune response is enacted by phagocytic cells known as hemocytes.

The melanisation response encapsulates foreign invaders with melanin and produces reactive oxygen species to kill microbes.

The fly also has barrier epithelia, native intestinal flora and an RNAi antiviral response which contribute to innate immunity.

Physiological and environmental factors can affect the outcome of an infection, including sleep and additional immune challenges.

The susceptibility of a fruitfly to bacterial infection depends both on its ability to resist a pathogenic infection and prevent bacterial growth and also its ability to tolerate the bacteria and the consequences of its own immune response.
Mutation, Selection and Genetic Interactions in Bacteria
Authors: Gordo Isabel , Sousa Ana
Published: May 2010

Mutation is the ultimate source of genetic variation. The rate at which new mutations typically occur, their effects on fitness and the strength and type of genetic interactions between different mutations are key for understanding the evolution of any population. Estimates of these parameters in organisms such as bacteria will have a profound impact on our understanding of their biology, diversity, rate of speciation and in our health. Experimental evolution with bacteria presents us with the opportunity to directly measure these parameters and to test theoretical predictions about the genetic basis of adaptive evolution. Evidence has been increasing to support the view that bacterial adaptation can be extraordinary fast, that competition between different adaptive mutations may be pervasive in bacterial populations and that epistasis is very common and possibly biased towards antagonism in bacteria.

Key Concepts:

The distribution of the effects of beneficial mutations shows the relative abundance of large versus small effect mutations contributing to adaptation.

Clonal interference leads to the loss of beneficial mutations with small effects.

Interaction between different alleles implies that the fitness of a genotype is dependent on the genetic background where it arises, this is termed epistasis.

Adaptation by compensatory evolution is particularly important in bacteria.