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At least 73 records · Page 4Linked to original sources
PubMed1999

Piriformospora indica: a new biological hardening tool for micropropagated plants.

Piriformospora indica is a novel plant growth promoting root endophyte. Regenerated plantlets of tobacco subjected to two different biological hardening techniques showed 88-94% survival when inoculated with P. indica as compared to 62% survival of uninoculated controls under similar conditions. The tendency of the plantlet to overcome the stress in terms of revival capacity was maximal in the case of P. indica as compared to the control. The fungus has the potential to render protection to the micropropagated plantlets and help them escape the 'transient transplant shock'.

Fungi↗
PubMed1991

Molecular biology: new tools for studying microbial ecology.

The general aim of studies in microbial ecology is to determine the activities of particular groups of organisms in the natural environment. Current developments in molecular biology are providing methods that can be adopted for investigations in microbial ecology. Presently, molecular techniques are being used to determine population and community structures in samples. Following on from this, methods are needed to determine the activities of these organisms in their natural state. This review describes the application of molecular techniques to the study of micro-organisms in environmental samples.

Bacteria↗
PubMed1988

Analysis of finite mixture of distributions: a statistical tool for biological classification problems.

A microcomputer program to analyze finite mixtures of normal, binomial, Poisson or exponential distributions by a maximum likelihood estimation procedure is described. The program is coded in Turbo Pascal. Some theoretical and practical aspects of the compound distributions are discussed, mainly mathematical characteristics, fitting procedures and tests of hypotheses. The statistical tool, which is a cluster analysis technique, is presented in a general context for applications in biology. In particular an ecological example is briefly described: the age class structure resolution of a white-tailed deer population. To improve the usefulness for classification purposes, the link with discriminant analysis is examined. For a successful analysis of finite mixture of distributions the need for a large sample size is emphasized.

Age Factors↗
PubMed2005

Usefulness of L-[methyl-11C] methionine-positron emission tomography as a biological monitoring tool in the treatment of glioma.

OBJECT: The authors retrospectively analyzed the data obtained in patients who had undergone L-[methyl-11C] methionine (MET)-positron emission tomography (PET) studies to clarify the relationship between MET uptake and tumor biological features and to discuss the clinical usefulness of MET-PET studies. METHODS: One hundred ninety-four patients with cerebral glioma or suspected glioma underwent PET scanning 20 minutes after injection of MET, whose uptake into the tumor was expressed as a ratio to contralateral healthy brain tissue (T/N ratio). Analyses were performed to determine how MET uptake correlated with tumor pathological features and prognosis. The T/N ratios before and after various treatments were also examined. There were significant differences in the T/N ratio among the nonneoplastic lesions, low-grade gliomas, and malignant gliomas. Furthermore, there were significant correlations between patient survival and pretreatment T/N ratios. Among patients with malignant gliomas, a significant difference in survival was observed between cases with and without postoperative tumor remnant based on elevated MET uptake. The MET uptake was heterogeneous even among the homogeneous tumor areas demonstrated on MR imaging. Malignant pathological features were detected in the areas with the highest MET uptake. The effectiveness of radiotherapy or chemotherapy was expressed as a significantly decreased T/N ratio in some of the tumor types. CONCLUSIONS: The ability of MET-PET to reflect the biological nature of gliomas makes it an excellent method for monitoring active tumor tissue, and treatments based on its findings should provide a powerful clinical protocol in the course of glioma therapy.

Brain Neoplasms↗
PubMed2003

[DNA, 50 years of the double helix: from the concept of molecular hybridization to microarrays].

The discovery of the double helix structure of DNA 50 years ago by J.D. Watson and F.H.C. Crick laid the foundation for modern molecular biology. This opened the way of 50 years of research resulting in the elucidation of gene expression mechanisms, in the development of molecular biology tools allowing analyzing and manipulating genes and in medical and forensic applications now routinely used. The discovery of the double helix structure allowed to evidence the DNA property of molecular hybridization on which are based most of the molecular biology tools, from the old Southern blot method to the recently developed microarrays.

DNA↗
PubMed1995

Bromodeoxyuridine: a diagnostic tool in biology and medicine, Part I: Historical perspectives, histochemical methods and cell kinetics.

Bromodeoxyuridine (BrdUrd), a thymidine analogue incorporated into DNA, can be quantified by fluorescent or chromophoric quenching of dyes bound to DNA or with antibodies to BrdUrd. These technologies have been used since the 1970s as tools for measuring DNA synthesis in isolated chromosomes and in cells and tissues. This paper is Part I of a three-part comprehensive review of the literature over the last 20 years (to the end of 1993) describing the histochemical methods for measuring BrdUrd in cells and tissues. Fixation, denaturation and staining procedures are compared for quantifying BrdUrd for microscopy and flow cytometry. Non-immunochemical methods related to the quenching of fluorescent DNA stains by BrdUrd are also described. Methods are described for the comparative assay of cell kinetic parameters by tritiated thymidine and bromodeoxyuridine. The multivariate BrdUrd/DNA assay of Ts and Tc, and a comparison of recent methods based on the single biopsy bivariate analysis of Tpot, is presented. Recent developments in the use of double halopyrimidine label to determine kinetic parameters are also reviewed.

Animals↗
PubMed1993

Diagnostic tools and biologic models for studying osteoporosis and oral bone loss: tissue sampling.

Study of oral tissues to understand the mechanisms of osteoporosis and oral bone loss includes histologic, biochemical, and molecular assessments of the tissue itself, as well as in vivo analysis of the biology of resident cells. Tissue sampling is limited by the nature of the defect and the use of appropriate controls (contralateral site vs same site, different subjects vs repeated measures of the same sites). Experimental parameters may include histomorphometrics, histochemistry, immunohistochemistry, and in situ hybridization. Molecular and biochemical technology also can be used to study the tissue in vivo. The presence of mineral is a confounding variable. To understand the underlying mechanisms of oral bone loss, cell culture is a powerful tool. The location in the oral cavity, the type of tissue (periosteum/cortical bone/trabecular bone), and the presence of pathology (periodontal disease) affect the biology of the cultured cells. Enzymatic release of cells from their extracellular matrix yields heterogeneous cell populations. Migratory cells from explant cultures are more homogeneous but less differentiated. Fibroblastic and bacterial contamination may be problems. Although cell culture data must be considered in the context of the intact tissue, the potential exists for developing bone cell function tests with diagnostic use in the treatment of bone disease.

Alveolar Bone Loss↗
PubMed1999

Limitations of molecular biological techniques for assessing the virological safety of foods.

Enteric viruses, including hepatitis A, Norwalk, and Snow Mountain viruses, Hawaii agent, and rotaviruses have been associated with outbreaks of foodborne illness. Classical culturing procedures are available for poliovirus; however, hepatitis A, Norwalk, and many of the other viruses and agents cannot be propagated in cell culture, therefore, molecular biological tools have emerged as a possible means to detect enteric viruses in foods and environmental samples. There are limitations however in the application of polymerase chain reaction and reverse transcription polymerase chain reaction that restrict their usefulness for measuring the virological safety of foods. The most serious limitation is that molecular techniques fail to discriminate between viable and inactivated viruses even though inactivated viruses pose no threat to the consumer and may be present at levels substantially higher than the virulent forms. Other disadvantages include a lack of assay sensitivity and specificity, high assay costs, and a level of technical expertise not available in most food-testing laboratories. Overall, scientific advances in the development of molecular biological tools have outpaced the demonstration of their validity in assessing the virological safety of foods.

Food Microbiology↗
PubMed1996

[A new tool for biological study: hair analysis. Value in medical practice].

Testing hair has been used since two hundred years for arsenic determination. Fifteen years ago, Baumgartner published the first report on the detection of morphine in the hair of heroin abusers by radio-immuno-assay. Today the development of new methods like gas chromatography/mass spectrometry has permitted numerous applications based on the analysis of organic substances trapped in hair. Personal observations and a review of the literature are presented in this paper to document the following clinical applications: hair as a screening procedure of psychiatric patients; hair and epileptic management; hair as a tool for monitoring neuroleptics; hair as evidence of gestational drug exposure; hair nicotine as a marker of passive exposure to tobacco; detection and clinical survey of heroin addict; evaluation of pharmaceutical exposure; hair analysis as a tool of clinical diagnosis; hair analysis for compliance monitoring.

Adult↗
PubMed2005

Immunotherapy of inflammatory diseases, 2005.

The management of inflammatory diseases has entered a new era, marked by the rise of new immunotherapy strategies. This concept was born thanks to the increasingly precise comprehension of their mechanism and the development of new therapeutic biological tools; progress that is probably as important as the discovery of steroids half a century ago. The use of biotherapies is now widespread, and, to date, approximately 1 million patients in the world have been treated with anti-TNF. Large-scale immunotherapy has requirements of which one should be aware. It is essential that users acquire a very high level of qualification. For handling biotherapies well, it is necessary to know the characteristics of biological tools (monoclonal antibodies, soluble receptors); in particular, their mode of action and their pharmacokinetic and pharmacodynamic properties. To optimise the use of these molecules, it is essential to know not only their characteristics but also the individual factors which make it possible to predict effectiveness and tolerance. Various approaches will allow a true 'pharmacoprediction' in order to determine 'the right drug for the right patient'. Thus, if this objective is achieved, it might be possible, in the immediate future, to propose à la carte therapeutic strategies, which avoid the most severe effects associated with the successive use of empirical immunosuppressor treatments. Lastly, it is essential for experts to identify new therapeutic strategies. This can be done only by mastering the most relevant advances of immunopathology, beyond the experimental models which are often difficult to extrapolate in humans. Thanks to this, original strategies, such as the modulation of costimulation pathways or the inhibition of mast cells, can be explored. This supplement is the synthesis of a conference on immunotherapies which gathered biologists and doctors of different horizons, all experts in biotherapies. The objective of this meeting can be summarised in two keywords: to understand and anticipate. These two concepts are essential for a specialist in immunomodulatory therapeutics. Thus, we hope that the information, brought by acknowledged experts, will enable you to enhance your knowledge on immunotherapies for the benefit of patients. Thank you for having allowed us to discover with enthusiasm these original aspects of modern immunotherapies of inflammatory diseases. See you soon at the 2006 conference.

Antibodies, Monoclonal↗
PubMed2003

Monoclonal IgE antibodies against birch pollen allergens: novel tools for biological characterization and standardization of allergens.

BACKGROUND: IgE antibodies are key players in immediate hypersensitivity reactions. Allergen characterization and standardization is usually based on the sera of allergic patients, whereas monoclonal IgE antibodies specific for clinically relevant allergens are very rare. OBJECTIVE: The aim of this study was to establish IgE mAbs specific for birch pollen allergens, because these are important inhalant allergens. METHODS: IgE-producing hybridomas were identified by using the highly sensitive rat basophilic leukemia cell mediator release assay with enhanced allergen stimulation by additional cross-linking with birch pollen-specific IgG antibodies. The obtained IgE mAbs were characterized by immunologic methods and by cDNA sequencing. RESULTS: Seven IgE mAbs specific for the birch pollen allergens Bet v 1 or Bet v 6 were obtained and were all biologically active in mast cell-based assays. Mediator release experiments with mAb combinations indicated that 2 different epitope regions were recognized on Bet v 1, whereas the 2 Bet v 6-specific mAbs bound to the same epitope region. After sensitization of rat basophilic leukemia cells with IgE mAbs, different amounts of Bet v 1 or Bet v 6 were detected in commercial diagnostic allergen reagents, whereas sensitization with polyclonal IgE resulted in similar allergenic potency of all products. CONCLUSIONS: IgE mAbs represent promising novel tools for allergen characterization and component-resolved standardization of allergen extracts.

Allergens↗
PubMed1993

Bioencapsulation: a biotechnological tool for biological life support for manned missions by the European Space Agency.

ESA (European Space Agency) decision in 1987 to acquire the capability needed to support man living and working in space, was the trigger for initiating the development of space life support technologies in Europe. The discipline of life support covers basically all the techniques that ensure the biological autonomy of man when isolated from his original biosphere. Biological life support technologies are presently under development at ESA either for their intrinsic ability to better achieve specific tasks than the currently available physico-chemical processes, or because only they can achieve these tasks. Moreover, a global integration of these biotechnologies leads us to the important notion of closed ecological life support system (CELSS). Indeed, a CELSS is the ultimate form of life support system we currently foresee for long-term space missions (over 2 years). Among those biotechnologies, immobilisation processes such as bioencapsulation are considered as potentially potent tools. They are detailed and presented in their life support context as they are currently standing along with their possible future time course in the ESA life support space program.

Ammonia↗
PubMed2005

The silent revolution: RNA interference as basic biology, research tool, and therapeutic.

RNA interference (RNAi) is an evolutionarily conserved mechanism for silencing gene expression. In primitive organisms, RNAi protects the genome from viruses and other insertable genetic elements and regulates gene expression during development. The antisense (guide) strand of short double-stranded RNAs is incorporated into an RNA-induced silencing complex that can either suppress protein expression or direct degradation of messenger RNAs that contain homologous sequence(s). The discovery that RNAi works in mammalian cells has sparked intense investigation into its role in normal mammalian cell function, its use as a tool to understand or screen for genes functioning in cellular pathways in healthy and diseased cells and animals, and its potential for therapeutic gene silencing. RNAi may provide an important new therapeutic modality for treating infection, cancer, neurodegenerative disease, and other illnesses, although in vivo delivery of small interfering RNAs into cells remains a significant obstacle.

Animals↗
PubMed1989

N-acetyl-S-(2-hydroxyethyl)-L-cysteine as a potential tool in biological monitoring studies? A critical evaluation of possibilities and limitations.

In mammalian species, including man, N-acetyl-S-(2-hydroxyethyl)-L-cysteine (2-HEMA) is a common urinary metabolite of a large number of structurally different xenobiotic chemicals. It is a common urinary end product of glutathione pathway metabolism of a variety of chemicals possessing electrophilic properties and, in most cases, also a genotoxic potential. Five different chemically reactive intermediates, with different electrophilic properties, may be involved in the formation of 2-HEMA. An inventory of chemicals known to lead to the formation of 2-HEMA, or based on their chemical structure expected to do so, is presented. Furthermore, an attempt is made to evaluate the possibilities and limitations in terms of the potential use of urinary 2-HEMA as a tool in biomonitoring studies. Two other related, sulfur-containing urinary metabolites, i.e. N-acetyl-(S-carboxymethyl)-L-cysteine and thio-diacetic acid, are proposed as possible alternatives to urinary 2-HEMA. It is suggested that 2-HEMA might be seen as a potentially useful and sensitive signal parameter for the assessment of exposure of animals and man to a variety of electrophilic and therefore potentially toxic xenobiotic chemicals.

Acetylcysteine↗
PubMed1996

Bromodeoxyuridine: a diagnostic tool in biology and medicine, Part III. Proliferation in normal, injured and diseased tissue, growth factors, differentiation, DNA replication sites and in situ hybridization.

This paper is a continuation of parts I (history, methods and cell kinetics) and II (clinical applications and carcinogenesis) published previously (Dolbeare, 1995 Histochem. J. 27, 339, 923). Incorporation of bromodeoxyuridine (BrdUrd) into DNA is used to measure proliferation in normal, diseased and injured tissue and to follow the effect of growth factors. Immunochemical detection of BrdUrd can be used to determine proliferative characteristics of differentiating tissues and to obtain birth dates for actual differentiation events. Studies are also described in which BrdUrd is used to follow the order of DNA replication in specific chromosomes, DNA replication sites in the nucleus and to monitor DNA repair. BrdUrd incorporation has been used as a tool for in situ hybridization experiments.

Animals↗
PubMedDate not supplied

In vitro reconstituted skin as a tool for biology, pharmacology and therapy: a review.

Various culture procedures, suitable to maintain the differentiated phenotype of various types of cells in vitro, have been devised during the past decade. These culture systems use macromolecular components extracted from extracellular matrixes or synthetic polymers which provide cells with a three-dimensional, spatially structured support. Substantial information has come from the use of collagen lattices. Many types of cells, of mesenchymal or other origin, are able to organize collagen fibrils in these models and to form a connective tissue-like structure. Prerequisites for this process are active function of the cytoskeleton and the expression of alpha(2)beta(1) integrin collagen receptors. Interaction of cells with such a matrix has profound effects on morphologic status, proliferation, cellular metabolism, and state of differentiation. The in vitro procedures reviewed and described in this article offer the possibility to combine different types of cells to approximate the in vivo environment and to investigate such physiologic processes as cell-cell and cell-matrix interactions which are otherwise not easily accessible. In pathologic conditions of the skin, these models have proven to be useful tools in investigating diseases relating to impaired recognition of extracellular matrix structures or alterations of cytoskeletal assembly. In pharmacologic and toxicologic studies, activity of drugs and potentially useful therapeutic substances has been evaluated. The use of cells and matrix components derived from skin has lead to refined systems which could be adapted and extended to other organs in an attempt to better understand pathophysiologic mechanisms.

Journal Article↗
PubMed1997

Evaluation of Caribbean strains of Macrocyclops and Mesocyclops (Cyclopoida:Cyclopidae) as biological control tools for the dengue vector Aedes aegypti.

Fifteen Caribbean strains of copepods were assessed for their predation ability against mosquito larvae. Macrocyclops albidus from Nariva. Mesocyclops aspericornis from Oropouche, and Mesocyclops longisetus from E1 Socorro, Trinidad, were most effective against Aedes aegypti but not against Culex quinquefasciatus. Mesocyclops longisetus and Me. aspericornis prevented any mosquito survival over 25 wk of observation despite weekly challenges with Ae. aegypti. The copepods were tolerant to dosages of the insecticide temephos that are usually toxic to mosquito larvae. This indicated that copepods could be incorporated into an integrated control system. To determine whether pathogenic microbes might be introduced with copepods into drinking water, microbial studies were done on the copepods. These showed the presence of only Aeromonas sobria, Pseudomonas sp., Alcalignes sp., and gram-positive bacilli. Although none of these are highly pathogenic to humans, the application of these copepods has not yet been recommended for use in drinking water.

Aedes↗