Ivermectin 20 years on: maturation of a wonder drug

Ivermectin has been on the veterinary market for almost a quarter of a century and has been approved for human use for 18 years. Its use has revolutionized the treatment of nematode and arthropod parasites in animals and has provided hope for the control or even eradication of filariases in humans. Although much remains to be learned about how the drug works and how resistance to it will develop, it has earned the title of "wonder drug".     

What's hot in animal biosafety?

In recent years, the emergence or re-emergence of critical issues in infectious disease and public health has presented new challenges and opportunities for laboratory animal care professionals. The re-emergence of bioterrorism as a threat activity of individuals or small groups has caused a heightened awareness of biosecurity and improved biosafety. The need for animal work involving high-risk or high-consequence pathogens and for arthropod-borne diseases has stimulated renewed interest in animal biosafety matters, particularly for work in containment. Application of these principles to animals retained in outdoor environments has been a consequence of disease eradication programs. The anticipated global eradication of wild poliovirus has prompted the promulgation of new biosafety guidelines for future laboratory and animal work. Increased concern regarding the use of biologically derived toxins and hazardous chemicals has stimulated a new categorization of facility containment based on risk assessment. Recognition that prion disease agents and other high-consequence pathogens require safe handling and thorough destruction during terminal decontamination treatment has led to the development of new biosafety guidelines and technologies. The implementation of these guidelines and technologies will promote state-of-the-art research while minimizing risk to laboratory animals, researchers, and the environment.     

Coding and traceability for cells,tissues and organs for transplantation

Modern transplantation of cells, tissues and organs has been practiced within the last century achieving both life saving and enhancing results. Associated risks have been recognized including infectious disease transmission, malignancy, immune mediated disease and graft failure. This has resulted in establishment of government regulation, professional standard setting and establishment of vigilance and surveillance systems for early detection and prevention and to improve patient safety. The increased transportation of grafts across national boundaries has made traceability difficult and sometimes impossible. Experience during the first Gulf War with miss-identification of blood units coming from multiple countries without standardized coding and labeling has led international organizations to develop standardized nomenclature and coding for blood. Following this example, cell therapy and tissue transplant practitioners have also moved to standardization of coding systems. Establishment of an international coding system has progressed rapidly and implementation for blood has demonstrated multiple advantages. WHO has held two global consultations on human cells and tissues for transplantation, which recognized the global circulation of cells and tissues and growing commercialization and the need for means of coding to identify tissues and cells used in transplantation, are essential for full traceability. There is currently a wide diversity in the identification and coding of tissue and cell products. For tissues, with a few exceptions, product terminology has not been standardized even at the national level. Progress has been made in blood and cell therapies with a slow and steady trend towards implementation of the international code ISBT 128. Across all fields, there are now 3,700 licensed facilities in 66 countries. Efforts are necessary to encourage the introduction of a standardized international coding system for donation identification numbers, such as ISBT 128, for all donated biologic products.     

Bacteriophage defence systems in lactic acid bacteria

The study of the interactions between lactic acid bacteria and their bacteriophages has been a vibrant and rewarding research activity for a considerable number of years. In the more recent past, the application of molecular genetics for the analysis of phage-host relationships has contributed enormously to the unravelling of specific events which dictate insensitivity to bacteriophage infection and has revealed that while they are complex and intricate in nature, they are also extremely effective. In addition, the strategy has laid solid foundations for the construction of phage resistant strains for use in commercial applications and has provided a sound basis for continued investigations into existing, naturally-derived and novel, genetically-engineered defence systems. Of course, it has also become clear that phage particles are highly dynamic in their response to those defence systems which they do encounter and that they can readily adapt to them as a consequence of their genetic flexibility and plasticity. This paper reviews the exciting developments that have been described in the literature regarding the study of phage-host interactions in lactic acid bacteria and the innovative approaches that can be taken to exploit this basic information for curtailing phage infection.     

Bacteriophage applications: where are we now?

Bacteriophages are bacterial viruses and have been used for almost a century as antimicrobial agents. In the West, their use diminished when chemical antibiotics were introduced, but they remain a common therapeutic approach in parts of eastern Europe. Increasing antibiotic resistance in bacteria has driven the demand for novel therapies to control infections and led to the replacement of antibiotics in animal husbandry. Alongside this, increased pressure to improve food safety has created a need for faster detection of pathogenic bacteria. Hence, there has been a resurgence of interest in bacteriophage applications, and this has encouraged the emergence of a large number of biotech companies hoping to commercialize their use. Research in Europe and the United States has increased steadily, leading to the development of a range of applications for bacteriophage agents for the healthcare, veterinary and agricultural sectors. This article will attempt to answer the question of whether bacteriophages are now delivering on their potential.     

Stem cell quest

Chronic Myeloid Leukaemia has been a valuable model system for experimental haematologists for many years. Virtually all patients (>95 %) have the same genetic change which has driven the development of the first targeted therapies, tyrosine kinase inhibitors (TKIs). Since the introduction of TKIs in 2000 it has become clear that this approach has significantly improved the outcome for these patients. Nevertheless drug resistance inevitably develops and it is clear that the disease is controlled rather than eradicated. The recent publication by Herrmann et al. has defined a sub-population of leukaemic stem cells which are responsible for propagating the disease. CD26 now provides a new specific target for the malignant stem cells and offers the possibility of true curative therapy.     

Persistence of bacterial pathogens as a physiological phenomenon

The complex ecosystem of humans and microbes has been presented as an associative symbiosis based on a mutual support of symbionts with different consequences for them. Conditions for the persistence of bacteria have been defined: their resistance to environmental factors, antagonism in biocenosis, and stability to withstand host defense mechanisms. The key role of bacterial peptidoglycan has been defined for their survival in an infected organism, and the classification for persistent mechanisms of pathogens has been given. The group of bacterial secreted protease providing microbial resistance to defense factors of the organism has been described. Host colonizing resistance has been presented as a physiological regulatory system controlling bacterial penetration into an organism. Regulatory mechanisms for bacterial persistence have been discussed.     

The Na,K-ATPase of nervous tissue

The Na,K-ATPase has been only partially purified from nervous tissue, yet it is clear that two forms (and +) of the catalytic subunit are present. is a component subunit of the glial Na,K-ATPase, which has a relatively low affinity for binding cardiac glycosides and + has been identified as a subunit of the Na,K-ATPase which has relatively high affinity for cardiac glycosides. The + form may also be sensitive to indirect modulation by neurotransmitters or hormones. The ratio of + / changes in the nervous system during development, and + appears to be the predominant species in adult neurones. Changes in Na,K-ATPase activity have been associated with several abnormalities in the nervous system, including epilepsy and altered nerve conduction velocity, but a causal relationship has not been definitively established. Although the Na,K-ATPase has a pivotal role in Na⁺ and K⁺ transport in the nervous system, a special role for the glial Na,K-ATPase in clearing extracellular K⁺ remains controversial.     

The purification and characterization of a beta-glucosidase from Alcaligenes faecalis

The beta-glucosidase from Alcaligenes faecalis has been purified to homogeneity (880-fold purification, 11% yield) using a combination of classical techniques and medium pressure ion-exchange chromatography. It is a dimeric enzyme of monomer molecular weight 50,000 and has no specific requirement for divalent metal ions. It has a high specificity for beta-glucosides and hydrolyses a wide variety of different chemical types wit retention of configuration at the anomeric centre. It has no exo-beta-1,4-glucanase activity. It is reversibly inhibited by a variety of sugars which have been shown previously to be very active against glucosidases, suggesting a normal mechanism of action. Measured Km values for cellobiose and p-nitrophenyl beta-D-glucopyranoside are quite low (0.70 and 0.08 mM, respectively), making this a good choice for cocloning into a cellulase system optimized for glucose production.     

Can yeast systems biology contribute to the understanding of human disease?

Saccharomyces cerevisiae is a unicellular eukaryal microorganism that has traditionally been regarded either as a model system for investigating cellular physiology or as a cell factory for biotechnological use, for example for the production of fuels and commodity chemicals such as lactate or pharmaceuticals, including human insulin and HPV vaccines. Systems biology has recently gained momentum and has successfully been used for mapping complex regulatory networks and resolving the dynamics of signal transduction pathways. So far, yeast systems biology has mainly focused on the development of new methods and concepts. There are also some examples of the application of yeast systems biology for improving biotechnological processes. We discuss here how yeast systems biology could be used in elucidating fundamental cellular principles such as those relevant for the study of molecular mechanisms underlying complex human diseases, including the metabolic syndrome and ageing.     

Tetrathiomolybdate anticopper therapy for Wilson's disease inhibits angiogenesis,fibrosis and inflammation

The need for agents to lower body copper in Wilson's disease, a disease which results from copper toxicity has been the driving force for the development of the effective anticopper drugs penicillamine, trientine, zinc, and now tetrathiomolybdate (TM). Because of its rapid action, potency, and safety, TM is proving to be a very effective drug for initial treatment of acutely ill Wilson's disease patients. Beyond this, TM has antiangiogenic effects, because many proangiogenic cytokines require normal levels of copper. This has led to use of TM in cancer, where it is generally effective in animal tumor models, and has shown efficacy in preliminary clinical studies. Most recently, it has been found that TM has antifibrotic and antiinflammatory effects through inhibition of profibrotic and proinflammatory cytokines.     

Importance of scaling exponents and other parameters in growth mechanism: an analytical approach

The growth process of a living organism is studied with the help of a mathematical model where a part of the surplus power is assumed to be used for growth. In the present study, the basic mathematical framework of the growth process is based on a pioneering theory proposed by von Bertalanffy and his work is the main intellectual driving force behind the present analysis. Considering the existence of an optimum size for which the surplus power becomes maximum, it has been found that the scaling exponent for the intake rate must be smaller than the exponent for the metabolic cost. A relationship among the empirical constants in allometric scaling has also been established on the basis of the fact that an organism never ceases to generate surplus energy. The growth process is found to continue forever, although with a decreasing rate. Beyond the optimum point the percentage of shortfall in energy has been calculated and its dependence on scaling exponents has been determined. The dependence of optimum mass on the empirical constants has been shown graphically. The functional dependence of mass variation on time has been obtained by solving a differential equation based on the concept of surplus energy. The dependence of the growth process on scaling exponent and empirical constants has been shown graphically.     

Anidulafungin: a new echinocandin for the treatment of mycosis

The latest antifungal drugs introduced for clinical use are echinocandins; they possess a distinctive mechanism of action based on the inhibition of the beta-1,3-D-glucan sintesis, through the damage of the fungal cell wall without impairment of human cells because these do not contain beta-1,3-D-glucan. Among echinocandins, anidulafungin is the last that has received the FDA approval in the USA for the treatment of candidemia in non-neutropenic patients, intra-abdominal abscesses, peritonitis and esofagitis caused by Candida. In Europe, the EMEA has also approved its use for invasive candidiasis in non-neutropenic patients and for candidal esofagitis. The characteristics of anidulafungin are close to those of the ideal antifungal since it has a wide spectrum, is active at low minimal inhibitory concentrations and it is fungicidal for Candida. In addition, it is well tolerated, has few pharmacological interactions, is active intravenously, has a long half life and is auto-biodegradable. Finally, anidulafungin has shown a higher therapeutic efficiency when compared with the conventional treatment of candidemia, since although it is more expensive, the treatment with anidulafungin is highly cost effective.     

RNA interference for analysis of gene function in trypanosomatids

Gene-specific silencing by RNA interference is a valuable tool for analysis of gene function in the protozoan parasite Trypanosoma brucei. The development of tetracycline-regulated vectors for production of double-stranded RNA has facilitated its widespread use. RNA interference provides a fast and efficient method for determining whether a gene is essential for growth and viability, reveals mechanistic information on gene function, and has greatly enhanced our understanding of complex biological processes. Finally, the creation of an RNA interference-based library has allowed, for the first time, an approach for conducting forward genetic experiments in this organism.     

Chemical modification of enzymes for enhanced functionality.

The explosion in commercial and synthetic applications of enzymes has stimulated much of the interest in enhancing enzyme functionality and stability. Covalent chemical modification, the original method available for altering protein properties, has now re-emerged as a powerful complementary approach to site-directed mutagenesis and directed evolution for tailoring proteins and enzymes. Glutaraldehyde crosslinking of enzyme crystals and polyethylene glycol (PEG) modification of enzyme surface amino groups are practical methods to enhance biocatalyst stability. Whereas crosslinking of enzyme crystals generates easily recoverable insoluble biocatalysts, PEGylation increases solubility in organic solvents. Chemical modification has been exploited for the incorporation of cofactors onto protein templates and for atom replacement in order to generate new functionality, such as the conversion of a hydrolase into a peroxidase. Despite the breadth of applicability of chemically modified enzymes, a difficulty that has previously impeded their implementation is the lack of chemo- or regio-specificity of chemical modifications, which can yield heterogeneous and irreproducible product mixtures. This challenge has recently been addressed by the introduction of a unique position for modification by a site-directed mutation that can subsequently be chemically modified to introduce an unnatural amino acid sidechain in a highly chemo- and regio-specific manner.     

Method for direct discrimination of intra- and intermolecular hydrogen bonds, and characterization of the G(:A):G(:A):G(:A):G heptad, with scalar couplings across hydrogen bonds

Discrimination of intra- and intermolecular hydrogen bonds in a symmetric multimer has not been accomplished yet, although such discrimination would provide a crucial basis for construction of the multimeric architecture of nucleic acids by NMR. We have developed a direct and unambiguous method for such discrimination involving the use of scalar couplings across hydrogen bonds. The method has been validated with a symmetric dimer of d(GGGCTTTTGGGC), for which the structure including both intra- and intermolecular hydrogen bonds was already reported. This has demonstrated that our method can clearly discriminate these two kinds of hydrogen bonds. Then, the method was applied to a symmetric dimer of d(GGAGGAGGAGGA) and has provided decisive information on its multimeric architecture. Additionally, the values for scalar couplings across hydrogen bonds for G:G and G:A base pairs in the G(:A):G(:A):G(:A):G heptad formed by d(GGAGGAGGAGGA) were determined for the first time. This determination has provided an insight into the nature of the heptad.     

Discrimination of tRNALeu isoacceptors by the insertion mutant of Escherichia coli leucyl-tRNA synthetase.

A variant (LeuRS-A) of Escherichia coli leucyl-tRNA synthetase (LeuRS) carrying a 40-residue duplication in its connective peptide 1 (CP1) has a 3-fold lower specificity for than for, whereas wild-type LeuRS has the same specificity for these two isoacceptors. The replacement of the acceptor stem of with yields a chimeric tRNA(Leu) for which wild-type LeuRS has the same specificity as it does for the two normal isoacceptors mentioned, but for which LeuRS-A has a reduced specificity similar to that for, indicating a difference between these two acceptor stems. LeuRS-A is slightly less stable than the native enzyme. Wild-type LeuRS and LeuRS-A have almost same K(d) value for their interaction with as determined by fluorescence quenching. No difference was detected between these two proteins by CD and fluorescence spectroscopy. These results show that LeuRS-A can discriminate between the two isoacceptors of tRNA(Leu).     

Study of a family with Los Angeles,Duarte, and classical galactosemia variants of galactose-1-phosphate uridyl transferase

We have described a family which has a combination of rare genetic alleles for the enzyme erythrocyte galactose-1-phosphate-uridyl transferase. The father has a combination of the Los Angeles and classical galactosemic alleles. The mother has a combination of the Duarte and classical galactosemic alleles. Their five children present various conbinations of these three alleles. One has classical galactosemia but she had, however, an atypical clinical presentation in that she survived for 8 months while being fed a normal diet. Despite this period of galactose ingestion she is of normal intelligence.