bluuebunny/crossref_metadata_2025 huggingface dataset:
Peptide hormone purification
Authors: Mclean C
Published: November 2023

Peptide and polypeptide hormones are purified in order to provide information about their physical and chemical properties, to obtain sufficient amounts of pure hormone for further studies or because they are not available in a synthetic or biosynthetic form. Classically, hormones are synthesized by specific organs, and these tissues remain the primary source, e.g. the pituitary gland (1). However, improvements in the sensitivity and specificity of assay systems have resulted in the localization of various hormones in tissues not previously associated with those hormones. Apart from these known sources there are potential sources such as tumours and more obvious possibilities such as blood and urine.
The in vitro bioassay of peptide hormones
Authors: Robertson W R , Bidey S P
Published: November 2023

The laboratory determination of peptide hormones in biological fluids has become an indispensable guide to endocrine function in Experimental and Clinical Medicine, and has been dependent upon the development of two distinct forms of hormone measurement, i.e. immunoassay and bioassay. However, much of our understanding of polypeptide hormone physiology has arisen directly from the development of a new generation of kit-based immunoassay techniques, which are capable of measuring the concentration of hormones in serum and other biological fluids with a high level of sensitivity and precision. Despite this the immunoassay of serum hormones has indicated levels which are inappropriate in a number of clinical situations (1, 2), whereas a determination of the biological activity of the hormone (i.e. by bioassay) correlates more closely with the observed clinical state. Such observations have led to a resurgence of interest in the further development of biological assays and such techniques continue to assume fundamental importance in modern investigative endocrinology, in addition to their classical role in the estimation of the potency of hormones for use as International Reference Preparations.
Radiotracers in lipid analysis
Authors: Taylor Colin G
Published: November 2023

Radiolabelled organic compounds may be detected at very low levels and quantified easily and accurately; the most common radionuclides used for such labelling being 14C, tritium (3H), 32P, and 35S. Species labelled with these nuclides have found extensive use in studies of chemical and biochemical pathways including those involving lipids. Forty years ago, radiochemical techniques played an important part in the elucidation of the tricarboxylic acid cycle, the common biochemical path for the oxidation of fuel molecules. By labelling carboxylic acids and their esters with 14C in specific positions, steps in the cycle were defined and it was also demonstrated that certain symmetric molecules (prochiral ones) such as citric acid, when bound to a substrate, may react asymmetrically to form optically active (chiral) molecules (1). In one early application of radiotracers to lipid analysis, microgram amounts of fatty acids were first separated by paper chromatography and then converted to their radiocobalt salts by treatment of the chromatogram with a solution containing 6°Co. The acids were located and measured by counting separate pieces of the chromatogram and the separated fractions were finally treated with Wij’s iodine containing 1311 to obtain iodine values by measurement of activity (2).
Geminiviruses (wheat dwarf virus)
Authors: Mullineaux Philip
Published: November 2023

Episomal (i.e. autonomously replicating) vectors derived from animal DNA viral sequences, and which can be maintained either transiently or permanently in cultured cells, are widely used in studies of transcriptional regulation in animals. The geminiviruses are a group of plant DNA viruses (for reviews see refs 1 and 2) from which episomal vectors for plant cells could be developed. Three properties of these viruses are relevant for vector development.
Fungi
Authors: Clarkson John M
Published: November 2023

Fungi are heterotrophic eukaryotic microbes which depend on a saprophytic, mutualistic, or parasitic mode of existence. Plant pathogenic fungi represent the most economically important group of microbial pathogens and can be divided into two broad categories on the basis of their nutritional relationship with the host (1). Necrotrophs usually cause extensive tissue damage and derive their nutrition from dead or dying cells. These fungi are able to grow, and often complete their life cycle, in axenic culture on simple laboratory media. Because they are capable of a purely saprophytic existence they are referred to as facultative necrotrophs but it is doubtful that this capacity for saprotrophy is fully expressed in the wild, as many pathogens persist as resting structures in the absence of a susceptible host. Biotrophs have a more subtle relationship with their hosts, deriving nutrients from living host cells and often causing only minor tissue damage in early infection. They include the downy and powdery mildews, rusts, and smuts and represent many of the most commercially significant pathogens. Structural adaptation to this mode of nutrition is typified by the formation of haustoria specialized hyphae which penetrate the host cell wall and invaginate the plasma membrane. Although all these pathogens are ecologically obligate biotrophs, the haploid sporidial stage of smut fungi can be readily cultured on simple laboratory media and limited axenic growth of some rusts is possible (2). Some fungi, such as Phytophthora infestans and Colletotrichurn lindernuthianurn exhibit a short biotrophic phase of development prior to obtaining nutrients necrotrophically and are referred to as hemibiotrophs.
Gene transformation in plant pathogenic fungi
Authors: Hargreaves John , Turner Geoffrey
Published: November 2023

Gene transformation of filamentous fungi is a relatively new but rapidly developing area (1). The first report of DNA-mediated transformation of a filamentous fungus was with Neurospora crassa (2) and was soon followed by the demonstration of gene transfer in another ascomycete, Aspergillus nidulans (3, 4). Since then a number of genes have been isolated by expression from these and other fungi, and molecular genetic techniques are now being extended to a wide range of commercially and agriculturally important fungal species. This chapter aims to provide a guide for the development of transformation systems for plant pathogenic fungi. Emphasis is placed on (a) choice of genes as selectable markers, (b) development of cloning vectors, and (c) procedures used to make fungal cells permeable to large DNA molecules.
Nematodes
Authors: Atkinson Howard J
Published: November 2023

Plant parasitic nematodes are either ecto-or endoparasites of plants with the majority of species attacking roots. They develop from an egg, through four juvenile stages (Jl-14), to a mature adult in a lifecycle lasting from a few weeks to several months. Most species are less than 2 mm in length and use a hollow stylet both to pierce plant cell walls and to withdraw cell contents. Only the stylet is inserted by ectoparasites whereas endoparasites either migrate intracellularly using the stylet to perforate cell walls or they move bodily between cells. Some endoparasites migrate short distances before feeding whereas others move continually or rely on host growth to assist their distribution within the plant.
The polymerase chain reaction
Authors: Mcpherson Michael J , Oliver, Richard J , Gurr Sarah Jane
Published: November 2023

The polymerase chain reaction (PCR), now a key tool in molecular biology, provides a rapid and powerful technique for the in vitro amplification of DNA sequences (see refs 1-3 for reviews). The PCR is now routinely used for gene cloning, analysis, and manipulation in many molecular biology laboratories. It has also found wide application in medicine; including diagnosis of genetic disease, mutational analysis, forensic pathology, and is proving important in such programmes as the mapping and sequencing of the human genome. The PCR has great potential for the study of plant-pathogen interactions in facilitating both gene cloning and genome analysis. Indeed, in biotrophic interactions where the host-pathogen interface is restricted to a small number of specialized cells, the PCR may provide the only mechanism for the investigation of changes in gene expression.
Distinguishing between multiple calcium channel types
Authors: Nowycky Martha C
Published: November 2023

The use of electrophysiological techniques to distinguish unique pathways for ion flow across biological membranes dates back to the pioneering work of Hodgkin, Huxley, and Katz. They successfully defined the changes in conductance which underlie action potentials and postulated the existence of independent, discrete channels for rapid Na+ influx and a slightly delayed K+ efflux.
Stability properties of microbial populations
Authors: Bazin M , Gray S , Rashit E
Published: November 2023

The stability of a dynamic system is a measure of its capacity to resist perturbation. In this chapter we are concerned with what happens to microbial populations after they have been perturbed. The sorts of perturbation we discuss include changes in environmental variables, such as the rate of nutrient supply to a population or the concentration of the food supplied. Ecosystems can also be perturbed by adding or subtracting species from them. We treat such situations in theoretical terms by approximating the population dynamics of microbial ecosystems with sets of differential equations, the solution of which can be characterised in mathematical terms. We begin by considering the stability properties of the Monod function applied to a single-species population in chemostat culture and then discuss two multispecies systems. The first of these is a simple predator-prey interaction in repeated fed-batch culture. We then review two problems in general ecology, and outline ways in which theoretical methods and experiments with microorganisms have been used to study them.
PCR in genetic diagnosis
Authors: Ivinson Adrian J , Taylor Graham R
Published: November 2023

The PCR has revolutionized the way genetic diagnosis can be performed. Previously, the diagnosis of many genetic diseases involved taking a 10- or 20 ml blood sample followed by a lengthy protocol over a minimum of four or five days to produce an autoradiograph displaying the results. With the PCR it is possible in many cases (see Table 1) to perform the same test in less than 10 h starting from samples as innocuous as a mouthwash or a pinprick blood spot (1, 2). This advance is of importance to any diagnostic laboratory both in terms of streamlining the experimental aspect of the work and improving the service offered to the patient.
Detection of deletions and point mutations
Authors: Rossiter Belinda J F , Grompe Markus , Caskey C Thomas
Published: November 2023

Many human disorders result from the disruption of a single gene by mutation. In some genetic diseases, such as sickle cell anaemia, the same mutation is found in many individuals and can be detected by relatively simple screening methods. In other genetic disorders, such as those resulting from defective X-linked genes, mutations are heterogeneous and therefore require different, scanning, approaches for their detection.
Genome amplification using primers directed to interspersed repetitive sequences (IRS-PCR)
Authors: Ledbetter Susan A , Nelson David L
Published: November 2023

The polymerase chain reaction (PCR) has revolutionized the isolation and analysis of specific nucleic acid fragments from a wide variety of sources (1). However, application of the PCR to isolate and analyse a particular DNA region has required knowledge of DNA sequences flanking the region of interest. This limits amplification to regions of known DNA sequence. We sought to amplify human DNA of unknown sequence specifically from somatic cell hybrids retaining human chromosome fragments in rodent cell backgrounds. This allows the isolation and characterization of sequences from specific human regions retained in hybrids, obviating the requirement for cloned DNA libraries and isolation of human clones through the use of human-specific repeat sequence probes (2). It also allows the characterization of hybrid cell lines for quantity and quality of the human sequences retained.
Hybridomas: production and selection
Authors: Harbour Colin , Fletcher Anne
Published: November 2023

The first monoclonal antibody (mAb) that we produced immobilized a motile suspension of the bacterium Salmonella typhimurium. It was an exhilarating moment when, almost immediately following the addition of our mouse mAb to a highly motile culture of bacteria, we witnessed the rapid cessation of motility. Ten years on, and after the production of hundreds of different mAbs, it is still an exciting moment when a new antibody specificity is detected. The major aim of this chapter is to ensure that the reader can share in a similar feeling of genuine achievement. The generation of mAbs can be an expensive, extremely labour-intensive, and often frustrating task but, providing the immunized mouse has produced antibodies to the chosen antigen, mAbs should be generated using the protocols we describe. We have found, however, that the production of stable cell lines producing human mAbs is much more difficult than in the mouse system. Thus, although the protocols described have proved successful, it is much more difficult to succeed in the production of human rather than mouse mAbs.
Monitoring and control of bi ore actors
Authors: Kilburn Douglas G
Published: November 2023

The increased commercial demand for proteins produced in animal cell cultures has highlighted the need for better, more economical production methods. Experience in the fermentation industry indicates that the performance of a biological process can often be vastly improved by a better understanding of the influence of environmental factors on cell productivity. A considerable expertise has been built up on methods to regulate the culture environment. These methods have been applied to mammalian culture with considerable success. New methods have been develped for high-intensity culture which achieve cell concentrations in bioreactors up to two orders of magnitude higher than the maximum seen in flask cultures. These high cell concentrations are totally dependent on the maintenance of a controlled culture environment. This chapter outlines the monitoring and control procedures which are most frequently used in mammalian cell bioreactors. The technology has been adapted from the process control systems commonly used for microbial cultures (Figure I). The terminology used to describe these standard methods of process control is summarized in Table 1.
Fibronectin and fibronectin fragments
Authors: Akiyama Steven K , Yamada Kenneth M
Published: November 2023

The adhesive glycoprotein fibronectin has provided an important model system for investigating mechanisms of cell-adhesive interactions. Fibronectin binds to a number of biological macromolecules including heparin, collagen, fibrin, and cell surface receptors. These binding activities are contained in distinct, protease-resistant domains that can be released from the intact molecule by proteolysis and purified by chromatographic techniques. Although studies are often carried out using intact fibronectin, it is often necessary to use purified fragments of defined binding activities in order to derive molecular mechanisms (1, 2).
Structural analysis of glycosaminoglyeans
Authors: Lyon. J E Turnbull M , Gallagher J T
Published: November 2023

Glycosaminoglycans (GA Gs) are negatively-charged polysaccharides of differing degrees of complexity which are ubiquitous components of the extracellular matrix and plasma membranes. The GAG chains are largely made up of a repeat disaccharide unit which consists of an amino sugar and a hexuronic acid (Hex A), the exception being keratan sulphate (KS) in which galactose (Gal) replaces Hex A (Table I). The disaccharides may be substituted with ester or amino-linked sulfate groups and the numbers of disaccharides per chain can vary enormously. from about 15 in keratan sulphates, to 50-200 in heparan sulphates/ chondroitin sulphates and over 4000 in hyaluronate (HA). HA has a uniform primary structure and is composed entirely of N-acetylated disaccharides (GlcNAc 13 1,4 GlcA) which are not sulfated. At the opposite extreme are the heparan sulfates (HS) in which differential sulfation and variations in the Hex A isomers (glucuronate, GlcA or iduronate, IdoA) produce complex domains which represent a considerable problem in qualitative structural analysis.
NMR Studies Of Protein— Ligand Interactions
Authors: Feeney J , Birdsall B
Published: November 2023

Over the last few years there has been an increasing interest in studying interactions between proteins and other molecules in solution. Such non-covalent interactions are of crucial importance in many molecular recognition processes in biology, typical examples being found in complexes of enzymes with substrates and inhibitors, of drugs with their receptors, and of transcription factors with DNA duplexes.
The insulin gene
Authors: Clark Andrew R , docherty kevin
Published: November 2023

Insulin is a member of a superfamily of structurally related peptides which includes the ovarian hormone relaxin, and insulin-like growth factors I and II (IGF-1 and IGF-11) (Steiner et al. 1985; Bell and Seino 1990). Insulin is also related to two insect hormones (prothoraciotrophic hormone of the silkworm Bombyx mori (Nagasawa et al. 1986) and LIRP, or locust insulin-related peptide (Lagueux et al. 1990)), and a molluscan insulin-related peptide (MIP), which is synthesized by the cerebral light green cell of the pond snail (Lymnea stagnatis) (Smit et al. 1988). It seems likely that the various members of the insulin gene family evolved from a common ancestral gene through a process of gene duplication and diversification (Steiner et al. 1985). The structure and evolution of the insulin gene have been previously reviewed in detail (Steiner 1990; Steiner et al. 1985; Bell and Seino 1990). However, since this subject was reviewed a number of important advances have been made on the regulation of expression of the insulin gene (Selden et al. 1987; Walker 1990), and this will form the major topic of this chapter.
Video imaging of neuronal activity
Authors: Haglund Michael M , Blasdel Gary G
Published: November 2023

Recent studies of the central nervous system have combined different techniques in an attempt to understand the relationship between anatomy and physiology. The functional organization of the cortex has become much more familiar through advances in imaging techniques such as 2-deoxyglucose autoradiography (DG), Computerized Tomography (CT), Magnetic Resonance Imaging (MRI), Positron Emission Tomography (PET), and Single Photon Emission Computerized Tomography (SPECT). The idea of direct optical imaging has occurred to many workers and was first tried more than 40 years ago (1), but has resurfaced recently on account of the many advantages that it has over other techniques.
Programming languages
Authors: Parslow Graham R
Published: November 2023

The choice of a computer language is likely to be influenced greatly by what is on the shelf, what a consultant programmer recommends, or what the user is already familiar with. Any computer language is simply a shell hiding the fact that a computer can only understand machine instructions, which are a series of numbers passed to the central processing unit (CPU). The means at hand to write a program can always be adapted to one’s vision, and are effectively hidden from an end user regardless of programming subtlety or magnitude of labour. If FORTRAN or BASIC allows rapid execution of a task, then they are obvious choices. You cannot be intrinsically assured of speed advantages, high portability, or easily maintained code simply because a program is written in C. Programming itself is at risk of becoming an outmoded skill, like the task of making a ‘cat’s whisker’ rectifier for a primitive radio, because offthe-shelf software has filled many of the niches for which a user might choose to create a program. The ascendency of object-oriented programming even promises the end of programming as it is commonly understood.
Balanced chromosome rearrangements
Authors: Young Ian d.
Published: November 2023

Balanced chromosome rearrangements are those in which there is no overall loss or gain of chromosome material. Unlike single gene disorders for which precise calculation of risks to offspring is usually possible, the segregation of chromosome rearrangements does not readily conform to any mathematical model which permits exact risk figures to be derived. Therefore the genetic counsellor faces a difficult task when presented with a patient known to carry a balanced chromosome rearrangement. To some extent the counsellor’s role is eased by the widespread availability of prenatal diagnostic cytogenetic services, so that the provision of a precise risk for malsegregation might be seen as of minor importance and very much subsidiary to a discussion of the hazards and limitations of chorion villus sampling and/or amniocentesis. Nevertheless many patients, particularly those for whom selective termination of pregnancy is unacceptable, will wish to be given some idea of the likelihood that a pregnancy might result in an abnormal baby.
Autosomal recessive inheritance
Authors: Young Ian d.
Published: November 2023

Before discussing individual examples, it is necessary to dwell briefly on a fundamental principle which is frequently used in risk calculation. Stated simply, Hardy-Weinberg equilibrium relates to the fact that in a large randomly mating population, in which two alleles N and A (N = normal or wild, A = abnormal or mutant) are segregating, the frequency of the three genotypes NN, NA (or AN) and AA can be obtained from the binomial expression (p + q)2 where p and q(p + q = 1) represent the frequencies of the normal and abnormal genes respectively. (The binomial distribution is discussed at length in Appendix 2). Thus the frequencies of the different genotypes will be as indicated in Table 4.1.
The use of linked markers
Authors: Young Ian d.
Published: November 2023

Recent years have witnessed an explosion in molecular biology which has revolutionized counselling and risk assessment for many of the common single gene disorders in which the basic defect at the protein level is unknown. However, for many of these conditions recourse has to be made to the use of polymorphic DNA markers known to be genetically linked to the disorder in question. The use of this approach can generate some remarkably difficult counselling calculations. This chapter offers an approach to the solution of some of the less complex arithmetic which can confront the unwitting genetic counsellor. More complex situations require access to purpose-built computer programs.1
Other mechanisms of inheritance
Authors: Young Ian d.
Published: November 2023

It is both conventional and convenient to consider modes of inheritance under the headings of chromosomal, single gene (autosomal dominant, autosomal recessive, sex-linked recessive) and multifactorial, a classification which, to a large extent, has been followed in Chapters 2–6. Whilst most disorders encountered at a genetics clinic conform to one or other of these established patterns, very occasionally situations arise in which the family pedigree is not readily consistent with any of them. Alternatively information from the medical literature may suggest that a much rarer genetic mechanism should be considered. In this chapter brief details of some of these alternative genetic processes are outlined along with key references which can be consulted for fuller information.
Gas chromatography in clinical biochemistry
Authors: Chakraborty Jagadish
Published: November 2023

During the past two decades advances in the detection systems, column technology and automation in sampling and data processing resulted in virtually universal acceptance of gas chromatography (GC), particularly in combination with mass spectrometry (MS), as an indispensable analytical tool in biomedical research. For multicomponent analyses of complex biological specimens, GC uniquely combines high resolution of components with detectors that offer high sensitivity, and simultaneous characterization and quantification of analytes.
Environmental analysis using gas chromatography
Authors: Best Gerry A , Dawson J Paul
Published: November 2023

In the past decade, there has been a marked increase in public awareness of pollution of the environment. This has put pressure on regulating authorities and research organizations to produce information about the levels of con-tamination and their significance. As a result, a greater amount of analysis is being carried out on all types of environmental samples. Probably the most rapid development in the analytical measurements of pollutants has taken place in the quantification of organic constituents. This is largely because of the great advances that have taken place in the technique of gas chromatography. For many years, the concentration of organic matter was assessed using only non-specific tests such as chemical oxygen demand (COD) or biochemical oxygen demand (BOD). These techniques are, however, no longer sufficient to investigate modern day pollution problems because of the vast range of artificial contaminants that are entering the environment.
Food Hydrocolloids: an end user’s viewpoint
Authors: Lillford P J , Norton Lt.
Published: November 2023

In recent years, consumers have become particularly concerned about the use of "additives" in manufactured foods. As a result, manufacturers have become very resistant to the introduction of new ingredients and conservative about the use of established ones despite their obvious advantages in stabilizing processing and product qualities. Despite this pressure, the use of hydrocolloids is at least stable, if not increasing. This appears to be due to the facts that hydrocolloids are ‘natural’, have no significant health risk associated with them, and can demonstrate obvious advantages in improving the quality of foods, either texturally and possibly nutritionally. The known physical and structural roles of various hydrocolloids are reviewed, together with comparisons with the current ingredients with which they compete. Some guidelines for the future uses of hydrocolloids in foods are discussed.
Food applications of hydrocolloids in Western Europe in the 90s
Authors: Gordon Ian R
Published: November 2023

The food ingredient market in W. Europe is in a period of change. Hydrocolloids providing thickening, stabilizing, suspending and gelling functions in food systems are in intense competition and many have lost or gained volume and share in the 80s. GIRACT has examined the forces of change and forecasts the development of these ingredients/additives to 1995 in the context of legislation and consumer pressure both EEC and national; development of key EEC food markets by sector; competition between hydrocolloids. The different hydrocolloids have different sectors of application, thus competition is only partial; for example, gum Arabic and modified starches in sugar confectionery. A striking element is the strong cultural differences between countries. Both food products consumed and the ingredients used are very different between the three cultural types (anglosaxon, germanic, Latin).
Effects of soluble non-starch polysaccharides on plasma cholesterol and liver lipoprotein receptor activity
Authors: Topping David L , Abbey Mavis , Triantafilidis Calliope
Published: November 2023

Raised plasma cholesterol is a major risk factor for coronary heart disease and many water-soluble non-starch polysaccharides (NSP) used by the food industry as thickeners and stabilizers lower cholesterol significantly both as whole foods and as isolates. The reduction is thought to occur through enhanced faecal steroid excretion causing a fall in plasma cholesterol. However, other mechanisms involving fat digestion may be involved also.
Retrogradation of concentrated starch gels
Authors: Keetels C J A M , Vliet T van
Published: November 2023

The effect of retrogradation of concentrated starch gels during storage on the rheological behaviour at large deformations and on fracture properties has been studied. During ageing the modulus and the stress at fracture increased and the strain at fracture decreased. The extent of these changes was dependent on the starch concentration and on the botanical source of the starch.
Designing polysaccharides for synergistic interactions
Authors: J.Morris V
Published: November 2023

Certain ‘synergistic’ mixtures of polysaccharides show an enhanced or even a new capacity to gel. Until recently most synergistic interactions between polysacccharides were considered to arise from intermolecular binding. Experimental studies on common synergistic mixtures will be reviewed and the evidence for intermolecular binding discussed in detail. For systems such as xanthan + carob, xanthan + tara and xanthan + konjac mannan, where intermolecular binding has been established, the chemical and stereochemical nature of the binding will be discussed. The implications of such stereochemistry upon the modification or design of new polysaccharides to improve synergistic interactions will be discussed. In particular the design and modification of polysaccharides to replace xanthan will be described.
Observations on retrogradation of starch polymers in the presence of wheat and rye arabinoxylans
Authors: Biliaderis Costas G , Izydorczyk Marta S
Published: November 2023

The effect of addition of wheat and rye water-soluble arabinoxylans on the retrogradation kinetics of concentrated amylose (20% w/w), wheat, and waxy maize starch (40% w/w) gels was investigated. Arabinoxylans added at a low concentration (1-2% w/w of total a-D-glucan) increased the crystallization rate of amylopectin, as evidenced by X-ray diffraction and calorimetry. For the amyloseand wheat starch-arabinoxylan mixtures, the storage modulus (G’) was clearly higher than the respective amylose and starch gels alone. In contrast, arabinoxylan retarded the gelation rate (G’ evolution) of waxy maize starch gels suggesting that this polysaccharide interferes with intermolecular cross-linking processes responsible for the rigidity of amylopectin gels; this effect was less pronounced with gels of increasing amylopectin concentration.
Gelation of soybean 11S globulin by glucono-deltalactone
Authors: Kohyama Kaoru , Nishinari Katsuyoshi
Published: November 2023

Dynamic viscoelasticity studies on the gelation of soybean llS globulin by glucono-delta-lactone (GDL) have been done in order to analyze the gelation process of tofu. Observed gelation curves at constant temperatures were approximated by first order reaction kinetics. The saturated storage modulus depended mainly on the concentration of llS protein. Mechanical loss tangents at the final stage of gelation were independent of GDL concentration. The rate constant of the gelation increased with increasing gelling temperature and was mainly governed by the concentration of GDL. The latent time at which the shear modulus began to deviate from the base-line became shorter with increasing concentration of GDL. However, the latent time was not shortened by an increase in protein concentration, in contrast to previous findings for many other protein gels.
The use of anti-oxidants to control viscosity and gel strength loss on heating of galactomannan systems
Authors: R.Mitchell J , E.Hill S , Jumel K , E.Harding S , Aidoo M
Published: November 2023

Viscosity loss on autoclaving guar gum solutions can be substantially reduced by the addition of mixtures of the antioxidants, sodium sulphite and propyl gallate. There appears to be a strong synergistic interaction between the two materials with the maximum affect occurring at ratios of sulphite to gallate of about 3:1. Total antioxidant levels required for substantial protection at pH 7.0 are of the order 1ooppm. The antioxidant combination is also effective in reducing the loss in gel strength which results from autoclaving mixtures of carrageenan and locust bean gum. The similar optimum ratio of sulphite to gallate to that found with the guar system and the small influence of the antioxidants on carrageenan alone suggests that in this mixed system the antioxidants function primarily by protecting the locust bean gum. The results favour a specific interaction rather then "phase separated" model for the mixed gel system. It is possible some of the reported interactions between polysaccharides and other food ingredients can be understood in terms of the antioxidant properties of the ingredients rather then biopolymer association or phase separation.
The effect of calcium ions on the competitive displacement of proteins
Authors: Hunt Josephine A , Dickinson Eric
Published: November 2023

Competitive displacement at pH 7 has been investigated at the emulsion droplet surface for the egg-yolk protein, phosvitin, and the milk protein, fl-casein. In particular, the effect of calcium ions on the protein exchange behaviour has been studied. Fast protein liquid chromatography analysis of the aqueous phase of phosvitin-stabilised n-tetradecane-in-water emulsions, containing fl-casein added after emulsification, is used to assess the extent of protein exchange at the droplet surface. We find that, in the absence of calcium ions, fl-casein displaces 70 % of adsorbed phosvitin within a few minutes, and then a further 10 % over a period of 48 hours. This is in contrast to the situation where calcium ions (5 mM) are present: here phosvitin is not at all competitively displaced by fl-casein, d˜spite virtually all the milk protein adsorbing.
Gelatin-maltodextrin interactions and synergies, applications in 25% low fat spreads
Authors: Muyldermans G , Vanhoegaerden R
Published: November 2023

In preliminary experiments, lower gel strengths of gelatin hide 180 bl./maltodextrin mixed gels showed that the compatibility of these hydrocolloids was lower with a low dextrose equivalent (25) maltodextrin (Cerestar C*PUR01906) than with higher dextrose equivalent products. A systematic study of the texture parameters (gel strength, rupture force, distance and energy) measured with the Stevens texture analyser on mixed gels of pigskin 260, 180 and 100 bl., hide 260, 180 and 100 bl. gelatins and maltodextrin C*PUR01906 showed that pigskin 260 and 100 bl. give compatible gels over the full 0-10% maltodextrin concentration range, with a synergy at 8-10%. Thermodynamic incompatibility was observed with pigskin 180 bl. and hide gelatins between 4 and 10% maltodextrin, and with all the gelatins at 9 % of the polysaccharide in presence of a low salt concentration. In spite of this, salt containing 25% low fat spreads were successfully produced with pigskin 260 and 120 bl. gelatins and maltodextrin C*PUR01906. Texture parameters determinations showed essentially comparable products were obtained, the pigskin 120 bl. product being somewhat more sticky.
Strategies for the diagnosis of parasitic infections
Authors: Gillespie S H , Hawkey P M
Published: November 2023

The organisms which are characteristically referred to as parasites are a heterogeneous group which range in size from microsporidia to complex multicellular organisms, such as Taenia saginata. Parasitic infections are found in all geographic areas and several, such as toxoplasmosis and toxocariasis, are common in temperate countries. Protozoa and helminths have historically been diagnosed and treated by a different group of doctors and scientists than other human pathogens, i.e. parasitologists and tropical disease specialists, rather than clinical microbiologists or infectious disease specialists. This division has arisen, in part, because of the tropical orientation of much parasitological investigation. Development of individual travel in the modern world has broken down the time barrier which used to stand between the developed and developing world. Increased numbers of journeys made to tropical countries have made infections, which might once have been thought of as exotic, commonplace. There is, therefore, a need for a greater awareness of the diagnosis of parasitological conditions amongst clinical microbiologists and infectious disease specialists.
Trichomonads
Authors: Ackers J P
Published: November 2023

Trichomonas vagina/is and Pentatrichomonas hominis (previously classified as Trichomonas hominis )are two of the three trichomonad parasites infecting humans, the third being the uncommon and little studied oral parasite Tricho-monas tenax All three are closely related flagellate protozoa with simple life cycles which do not include a resistant cyst stage. T. vagina/is is sexually transmitted, and the most common protozoan infection in Europe and North America, but with an even higher prevalence in many developing countries. P. hominis inhabits the large bowel and is much less common; it is usually regarded as a non-pathogen although it can probably cause mild gastro-intestinal symptoms when present in large numbers. It is transmitted by the ingestion of trophozoites derived from the faeces of infected patients, and is unusual in being sufficiently resistant to gastric acid despite the absence of a cyst. Because of their very different epidemiology and clinical presentation, these two organisms will be dealt with separately.
Schistosomiasis
Authors: Marshall Ian
Published: November 2023

Schistosomes are digenetic trematodes belonging to the phylum Platyhelminthes (flatworms) and infect more than 200 million people in 76 countries in the tropics and subtropics. Although 18 species of the genus Schistosoma are currently recognized, the majority are parasites of animals other than humans. Most infections in humans can be accounted for by Schistosoma haematobium, S. japonicum, and S. mansoni, together with a minor contribution from S. intercalatum and S. mekongi. The distribution of the clinically significant species of Schistosoma is shown in Figure 1.
Purification of protein (tyrosine) kinases
Authors: Stewart Alexander a.
Published: November 2023

This chapter describes the general principles involved in the purification of protein (tyrosine) kinases (PTKs). The importance of PTKs, and reasons for purifying them are briefly described. The best sources for protein (tyrosine) kinase purification, and methods for their assay are discussed. Purification techniques which are either unique or particularly appropriate for PTKs as a group of enzymes are described, with examples from the purification of three of these enzymes: c-src,epidermal growth factor (EGF) receptor, and platelet-derived growth factor (PDGF) receptor kinases.
Homology-based approaches for identifying cDNAs that encode eukaryotic protein (serine/threonine) and protein (tyrosine) kinases
Authors: Hanks Steven K , Lawton michael A
Published: November 2023

In eukaryotes, protein kinases that phosphorylate serine, threonine, and tyrosine residues make up a large family of related enzymes (1–3). The members of this family are of interest because of the critical roles they play in regulating cellular processes such as the transduction of extracellullar signals, oncogenesis, and cell cycle progression. The list of known protein-kinases is expanding rapidly. To date, well over 100 different protein kinases, encoded by distinct genes, have been identified from mammalian species alone. Many more have been recognized from a wide variety of other eukaryotes, including life-forms as diverse as coelenterates, slime moulds, fungi, and lower and higher plants. There is no doubt that a great many more members of this important enzyme family remain to be discovered.
Chromosome analysis and sorting by flow cytometry
Authors: Monard S , Kearne L , Young B D
Published: November 2023

Univariate chromosome analysis can be performed on most flow cytometers equipped with an argon ion laser (10). Chromosomes are usually stained with ethidium bromide which can be excited with the 514 nm line, or more usually with the 488 nm line of an argon ion laser. The emission signal can be collected using a 580 nm long pass filter or equivalent band pass filter. Other fluorochromes can be used for univariate analysis and sorting if they give a clearer separation of the chromosome peak of interest.
Lignin and Associated Phenolic Acids in Cell Walls
Authors: Friend John
Published: November 2023

Many types of phenolic compounds are found in cell wall preparations or as insoluble residues remaining after the extraction of metabolites soluble in organic solvents. This chapter describes procedures for the isolation and analysis of lignin and other phenolic compounds from plant material. Since most analytical methods for phenolic compounds are specific for phenolic hydroxy-groups, it is essential that all soluble phenolic compounds are extracted from the tissue during the preparation of the insoluble residue or cell wall fraction. Many simple phenolic compounds may not be completely extracted by nonaqueous organic solvents. Indeed, the removal of water by acetone or methanol may cause hydrogen-bonding of phenolic compounds, such as chlorogenic acid, to the insoluble residue leading to spurious results. Moreover, it is possible for phenolic compounds to be oxidized by endogenous phenolases, during the extraction procedure. The oxidation products of compounds, such as chlorogenic acid, can then chemically react with freeNH2 or -SH groups on amino acid side chains to yield complex oxidation products bound to protein. This may be cell wall protein itself, or protein which is hydrogen bonded to the cell wall during the extraction procedure.
Analysis of Components of the Plant Phosphoinositide System
Authors: Drobak Bjorn K , Roberts Keith
Published: November 2023

A key-role for Ca2+ as an intracellular messenger is now well established in a vast number of organisms ranging from slime-moulds to humans. Both mammalian and plant research in the Ca2+ field has, until recently, been somewhat hampered by the lack of understanding of how external signals initiate the responses mediated by the Ca2+ ion. This situation has rapidly changed with the discovery, in the early 1980s, by Berridge, Irvine, Michell, and their coworkers, that in many cell types a discrete pool of inositol-containing phospholipids constitute the missing link between extracellular signals and the modulation of intracellular Ca2+ fluxes (1-3). The pioneering work on this system (now known as the phosphoinositide signal transducing system-or the ‘PIsystem’) carried out in mammalian cells and tissues has inspired plant scientists to investigate whether a similar system is involved in the transduction of signals in plant cells. A brief outline of how this system functions is given in Section 1.1. When certain agonists (extracellular signals) arrive at the surface of the plasma membrane they bind to specific receptors. The agonist-receptor association activates phospholipase(s) C (phosphoinositidase C, PIC)-probably via interaction with one or more guanine nucleotide binding proteins (Gproteins) associated with the membrane. The primary target for PIC action is phosphatidylinositol (4,5) bisphosphate (Ptdlns (4,5) P2) a phosphorylated form of phosphatidylinositol (Ptdlns) which resides in the inner leaflet of the plasma membrane.
Metabolic Changes Following Infection of Leaves by Fungi and Viruses
Authors: Leegood Richard C , Scholes Julie D
Published: November 2023

Pathogenic organisms can broadly be divided into two categories, based on their mode of nutrition. Nectrotrophic pathogens, such as the damping-off fungi and soft-rot bacteria, rapidly kill and degrade the host tissue by the production of large quantities of toxins and cell-wall degrading and proteolytic enzymes. These pathogens derive the majority of their nutrients from the dead host tissue and subtle changes in the regulation of metabolism will be transient. In contrast, the biotrophs (for example viruses, rust fungi, downy and powdery mildews) are highly specialized pathogens. They require a continual supply of nutrients from the host in order to develop and reproduce. They therefore co-exist with the host for a certain period of time. This coexistence must be accompanied by regulated changes in the physiology and metabolism of the host.
Novel gene transcription in response to growth factors: gene isolation by differential plaque hybridization
Authors: Reddy P Sanjeeva , Cochran Brent H
Published: November 2023

Differential cDNA cloning can be used to identify differences in gene expression between any two populations of cells. This method has been used in a variety of experimental situations, but has been especially successful in allowing for the isolation of genes which are regulated by growth factors. These screens have identified genes which are regulated by PDGF (1), TPA (2), IL-2 (3), serum (4, 5), and NGF (6) to name only a few. This analysis has increased our knowledge not only about the types of genes which are regulated by different growth factors, but also helped identify entirely new gene families such as the bZIP proteins and novel cytokines (7, 8). These growth factor regulated genes are often referred to as immediate early genes, or early response genes since many of them can be induced by growth factors in the absence of new protein synthesis. For review, see Herschman, 1991 (9).
Localization of growth factor mRNA in tissue sections by in situ hybridization
Authors: Akhurst Rosemary J
Published: November 2023

It is becoming clear that, in vivo, the majority of growth factor bio-activities are effective locally, exerted via autocrine, paracrine, and (possibly?) intracrine mechanisms. To investigate molecular mechanisms of action it is therefore important to identify both sites of synthesis and sites of action for each growth factor. The development of in situ hybridization for detection of cellular mRNAs in tissue sections has provided a very powerful and precise tool with which to address the first of these issues. Using this technique, individual cells possessing RNA transcripts for a given gene can be unequivocally identified.
Introduction
Authors: Dyer Philip , Middleton Derek
Published: November 2023

This book aims to set out tried and tested protocols that will be used in a histocompatibility laboratory in support of both clinical service and research work. The techniques have been established by the chapter authors in their own laboratories but the reader is encouraged to amend and develop as necessary. The early chapters set out the serological and molecular techniques which are common in many histocompatibility laboratories. Later chapters deal with more specialized techniques which those keen to develop their range of services will find useful. The debate over the future of serological testing with the advent of molecular techniques continues but it must be remembered that the donor/recipient cross match remains of fundamental importance. The design of this book and others in the series is to facilitate use at the bench. The field of histocompatibility is rapidly moving and the chapter authors have provided their most up-to-date methods. A direct enquiry to authors will give access to further modifications.