bluuebunny/crossref_metadata_2025 huggingface dataset:
Routine assessment of morphology and growth: scoring syste1ns and measurements of size
Authors: Brown Nigel A
Published: November 2023

This chapter describes techniques for the routine assessment of the morphology and growth of postimplantation conceptuses. The aim is to give methods which are quick, easy, objective, and accurate, rather than exhaustive. For example, morphological assessment is made from gross examination of fresh samples, not from histological examination. A recent study (t) showing that routine histological study of postimplantation conceptuses reveals little more than gross morphology supports this approach.
RNA-based viruses
Authors: Kroner Philip , Ahlquist Paul
Published: November 2023

This chapter describes the use of protoplasts to study various aspects of the replication cycle of ( +) strand RNA viruses that infect plants. The genetic analysis of these viruses, which comprise the overwhelming majority of plant viruses, has been accelerated in recent years by the development of methods that produce infectious viral RNA from genetically manipulatable cDNA clones. Using this technology, these viruses can be studied both in vivo and in vitro in a variety of experimental systems using, for example whole plants, protoplasts, and extracts purified from infected tissue. Each of these systems has its own advantages, such as emphasizing aspects of the virus lifecycle. Many important issues relating to the movement of virus infection, for example, require investigation at the level of whole plants or tissues. For many studies, however, protoplasts provide an especially valuable system.
Kinetics of secondary metabolite production
Authors: Trilli A
Published: November 2023

The concept of ‘secondary metabolite’ is a deceptively simple one: most microbiologists and biochemists have little doubt as to what a microbial secondary metabolite is and can readily name several substances over the secondary nature of which there is little controversy, but there is still no universally accepted definition.
Analysis of DNA adducts by mass spectrometry
Authors: Giese Roger W
Published: November 2023

There is increasing concern in our society about the risks to health from human exposure to toxic chemical and physical agents. While chemical exposure studies involving animals are important, there is no complete substitute for direct studies of humans. Since an ultimate target for toxic chemicals in the body is DNA, there is interest in measuring chemicals attached to human DNA. Such measurements including structural elucidation of the adducts can serve not only as an internal dosimeter for human exposure to chemicals, but contribute to our understanding of chemical carcinogenesis and mutagenesis.
Progress in biomonitoring of aromatic carcinogens by determination of thioethers in the urine
Authors: Norpoth K , Muller G
Published: November 2023

Besides DNA-, RNA-, and protein adducts, thioethers which are produced by the reaction of activated carcinogens with glutathione are found to be useful parameters of the biological monitoring of carcinogen exposure. Of importance are S-substituted cysteine and N-acetylcysteine derivatives which are degraded further to thioglycolic acids and sulphoxides (Fig. 29.1). The aim of this work was to study whether the improvement of thioether-analysis can facilitate the calculation of body burden of the activated moiety of incorporated aromatic carcinogens.
Selective alkylation of cells in rat tissues after treatment with N-nitroso compounds: immunohistochemical detection of potential target cells
Authors: O’Connor P J , Fan C -Y , Zaidi S N , Cooper D P
Published: November 2023

The N-nitroso compounds are carcinogenic if they are activated to generate intermediates which undergo reaction with the constituents of cells thereby leading to the initiation of cancers through the formation of promutagenic 0-alkylated bases in DNA.
Immunological monitoring of DNA damage formed in patients by DNA-reactive anticancer drugs
Authors: Tilby M J , Dean C J , Lawley P D , Styles J N , Selby P J
Published: November 2023

The anticancer drug melphalan (phenylalanine mustard), a difunctional nitrogen mustard which is highly cytotoxic, is administered to certain cancer patients (e.g. myeloma) in high doses by intravenous injection. We have developed a monoclonal antibody based immunoassay for the DNA adducts fonned by melphalan in order to carry out clinical investigations related to cancer chemotherapy. Because the patients receive a single, accurately known, high dose of this drug, an opportunity is available for studying the molecular dosimetry of an alkylating agent in man and for assessing the variation between patients in their susceptibility to DNA damage formation under these circumstances.
Lipoprotein turnover and metabolism
Authors: Gaw Allan , Packard Christopher J , Shepherd James
Published: November 2023

The study of lipoprotein kinetics has added significantly to our understanding of the regulation of the plasma lipid transport system and the aberrations that give rise to hyperlipidaemia. Lipoprotein metabolism can be divided into three inter-related pathways (Figure 1). The first, associated with the synthesis and catabolism of chylomicrons, is responsible for the absorption of dietary fat and delivery of triglyceride to peripheral tissues (such as adipose tissue and skeletal muscle) and cholesterol to the liver. The second involves the production of very low density lipoproteins (VLDL) from liver and their remodelling to intermediate and low density lipoproteins (IDL, LDL). By this pathway triglyceride and cholesterol are transported in the fasting state. The third is concerned primarily with the return of cholesterol from peripheral sites to the liver and is mediated by the high density lipoproteins (HDL). The kinetics of these processes have been followed using both lipid and apolipoprotein markers. The former were used in early experiments and provided information on total body turnover rates of cholesterol and triglyceride. The latter have yielded data on the behaviour of individual lipoprotein fractions. Chylomicrons, VLDL, IDL, and LDL contain apolipo protein B as their major structural protein. This high molecular weight polypeptide exhibits an extended secondary structure that intercalates into the lipoprotein surface and remains there throughout the lifetime of the particle in the plasma. Hence it acts as a marker of a particle ‘s metabolic fate, whereas all other lipoprotein constituents including the A, C, and E apolipoproteins exchange freely between particles, complicating inter pretation of their metabolic properties.
PCR with highly degenerate primers
Authors: Mcpherson Michael J , Jones Kerrie M , Gurr Sarah Jane
Published: November 2023

Primers for use in the polymerase chain reaction are usually unique oligo-nucleotides designed from a known DNA sequence. However, for an uncloned gene, where obviously no DNA sequence data are available, the PCR may be used in cloning strategies by designing highly degenerate primers from protein sequence data (1–3). Such degenerated primers have been used successfully to isolate members of multigene families and genes from diverse species. The amplified DNA represents part of the gene of interest and can therefore be used as a homologous hybridization probe, allowing high stringency screening of gene libraries to isolate corresponding cDNA or genomic clones. The PCR amplified DNA may also be used to probe Southern or Northern blots.
The fidelity of DNA polymerases used in the polymerase chain reactions
Authors: Eckert Kristin A , Kunkel Thomas A
Published: November 2023

Purified DNA polymerases are one of the primary tools for molecular biology. Yet choosing the most appropriate DNA polymerase for any particular application requires an understanding of the substantial biochemical differences between the available enzymes. One aspect of interest for PCR is the fidelity of DNA polymerization, i.e. the number of errors produced per nucleotide synthesized. We begin this chapter by discussing the enzymology of error discrimination by DNA polymerases during DNA synthesis in vitro. We then describe the fidelity of several prokaryotic DNA polymerases using a simple assay for scoring DNA polymerase errors. Next we examine the parameters that affect the fidelity of the polymerase most often used for PCR, the Taq DNA polymerase isolated from Thermus aquaticus.
Intracellular trafficking in fission yeast
Authors: Armstrong John , Fawell Erica , Pidoux Alison
Published: November 2023

The analysis of protein targeting and membrane traffic in eukaryotic cells has benefited greatly from the use of genetic methods in the budding yeast Saccharomyces cerevisiae. The approach was introduced by Novick and Schekman, whose sec mutants define a collection of genes which function at different stages of the secretory pathway. These gene products are now the object of intense study (reviewed in reference 1); already it is clear that the general characteristics of membrane traffic are conserved between yeast and higher eukaryotes, and that several of the sec genes have homologues in mammalian cells. Genetic screens in yeast have since been used to identify mutants in other processes of membrane traffic, such as protein targeting to the vacuole (2, 3) and retention of proteins in the endoplasmic reticulum (4). Given the accumulation of biochemical and genetic tools now available, it is likely that S. cerevisiae will continue to be popular for studies of different aspects of protein targeting. Several excellent collections of protocols for genetics, cell biology, and biochemistry in budding yeast are now available (e.g. 5, 6).
In vitro reconstitution of endocytic vesicle fusion
Authors: Gruenberg Jean , Gorvel Jean-Pierre
Published: November 2023

It is now well established that, after internalization by clathrin-coated pits, solutes and receptors first appear in early endosomes at the cell periphery, then in late endosomes in the perinuclear region, and eventually in lysosomes (reviews in references 1-3). We have observed that tracers leaving the early endosomes appear in large spherical vesicles before they reach late endosomes (4). These large vesicles resemble one of the subpopulations of multivesicular endosomes described by Dunn et al. (5). Tracers internalized after microtubule depolymerization pass through early endosomes and reach these large vesicles but they do not appear in the late endosomes. We thus proposed that these vesicles are involved in the microtubule-dependent transport between early and late endosomes and may correspond to the vesicles observed to move in vivo between the cell periphery and the perinuclear region. In this chapter we will refer to these vesicles as endosomal carrier vesicles.
The extracellular matrix—an overview
Authors: Haralson Michael A , Hassell John R
Published: November 2023

The extracellular matrix (ECM) has been traditionally thought of as the structurally stable material that provides support for cells and tissues. However, a number of discoveries over the past two decades have changed this perspective and established the importance of the ECM in modern biology. First, both biochemical and molecular biological investigations have documented that four major classes of macromolecules—the collagens, proteoglycans, structural glycoproteins, and elastin—collectively comprise the ECM of animal cells (1—6). Furthermore, with the exception of elastin, each class of matrix macromolecules has been found to contain families of related proteins with each member being a unique gene product. Second, individual members of each class and family of ECM molecules were found to exhibit a degree of tissue-specific distribution implicating the matrix in development and tissue function (7—9). Third, specific cell surface receptors for ECM components were identified, which provided a rational basis for linking the ECM with the biology of the cell (10—16). From these discoveries we now appreciate that the extracellular matrix is a complex ordered aggregate composed of a number of different macromolecules whose structural integrity and functional composition are important in maintaining normal tissue architecture, in development, and in tissue specific function (2, 4, 6, 8, 17). Finally, in conjunction with these studies has come the recognition of the importance that dysfunctional matrix components and abnormalities in ECM biosynthesis and catabolism have in both inherited and acquired diseases and in normal wound healing (2, 3, 5, 6, 9, 18).
Elastin
Authors: Davidson Jeffrey M , Giro Maria Gabriella , Mecham Robert P
Published: November 2023

Elastin, when mature, is the most insoluble protein in the vertebrate body. It is synthesized as an Mr= 70 000 precursor from a 3.5 kb mRNA encoded by a single gene into a protein termed tropoelastin, which is cross-linked sub-sequent to secretion by the copper-dependent enzyme, Iysyl oxidase (1). Therefore, for most purposes elastin purification simply requires the solubil ization and removal of other protein components from connective tissue to leave elastin as the remaining residue. The elastic.fibre, however, consists of insoluble elastin plus other structural macromolecules, collectively referred to as microfibrillar components (2). Since these molecules are also relatively insoluble, their isolation is also accomplished by selective extraction of the elastic fibre under denaturing and reducing conditions. This chapter will not detail the isolation of these other components.
Use of extracellular matrix and its components in culture
Authors: Kleinman Hynda K , Kibbey Maura C , Cannon Frances B , Weeks Benjamin S , Grant Derricks
Published: November 2023

The interaction of cells with the extracellular matrix is an important determinant of cell behaviour (1). Extracellular matrices not only provide structural support but also elicit biological responses which are mediated by specific components of the matrix through interactions with cell surface receptors. Matrices contain collagens, proteoglycans, and glycoproteins. The type and amount of each component depend on the cell type with which it is associated. Our understanding of the biological activity of the extracellular matrix and its components has been enhanced by the ability to purify the components and to examine their effects on cells in culture. From these studies, it is clear that components such as collagen types I and IV, laminin, and fibronectin influence cell behaviour in a cell specific manner. Cells adhere, grow, migrate, and differentiate on matrix components, and, in many cases, do so better than on plastic or glass surfaces. Specific sites on matrix molecules are being defined for these processes with distinct domains, and synthetic peptides having been shown to possess biological activity (2). Specific cellular receptors for each matrix macromolecule have also been defined. This chapter focuses on the use of basement membrane preparations and the components laminin and collagen in cell culture (3, 4). Many of the techniques described herein can be directly adapted to the other matrix glycoproteins including fibronectin, entactin, vitronectin, thrombospondin, tenascin, osteopontin, and osteonectin.
Isolation and analysis of RNA from connective tissues and cells
Authors: Sandell Linda J
Published: November 2023

Extraction of intact functional RNA from connective tissues presents special challenges. Most extracellular matrix (ECM) molecules are very large and consequently their mRNAs are among the longest known. The difficulty in isolating these large mRNAs is compounded by the large amount of ECM surrounding the cells. In addition, the number of ECM mRNAs per cell may be quite low due to the low turnover rate of the protein. In some connective tissues, however, where the ratio of cells to matrix is high, RNA can be isolated from the tissue directly. In other cases where the matrix is resistant to denaturation or where the matrix is particularly abundant, better results are achieved when the matrix is removed from the cells before isolation of RNA. In this chapter methods will be described that have been used successfully to isolate RNA from cartilage and a variety of other connective tissues, such as bone, tendon, and smooth muscle, and from connective tissue cells in culture.
Generation of cosmid DNA libraries and screening for extracellular matrix genes
Authors: Toman David , Crombrugghe Benoit De
Published: November 2023

The application of molecular biological techniques to study the structure, function, and transcriptional regulation of extracellular matrix genes has provided a wealth of knowledge at the DNA level. A nine base pair repeat encoding Gly-X-Y at the amino acid level has been implicated as the ancestor of the collagen molecule. This repeat has been assembled into a 54 base pair exon which has been duplicated and combined with other functional groups to generate at least part of the family of collagen genes. Individual members of the collagen family show tissue specificity and provide different structural roles in many multicellular organisms. Analyses of the role of collagens in human connective tissue diseases have shown a wide spectrum of phenotypic effects which are currently studied in order to more fully understand their functional role in an organism. Mouse transgenic models are probing structure/function relationships with other components of the extracellular matrix. Identification and characterization of specific transcription factors and cis-acting elements are unravelling the regulatory pathways which determine the tissue- and developmental-regulation of expression of these genes.
Stable Isotope Labelling and Resonance Assignments In Larger Proteins
Authors: Markley John L , Kainosho Masatsune
Published: November 2023

This chapter introduces the general principles of isotope-assisted NMR spectroscopy of proteins and presents descriptions of several specific procedures. The rationale and methodology of protein labelling are discussed, and NMR experiments that exploit various patterns of labelling are surveyed.
Insulin synthesis
Authors: Yes Elaine M Bail , Guest, Paul C , Hutton John C
Published: November 2023

The structure of insulin has been highly conserved throughout higher vertebrate evolution. The hormone consists of an A-chain (21 amino acids) and a B-chain (30 amino acids), connected by two intermolecular disulphide bonds (A7-B7, A20-Bl9), with an intramolecular bond between A6 and All. Invariant features include the positions of the three disulphide bonds, the N- and C-terminal regions of the A-chain, and the hydrophobic residues in the C-terminal region of the B-chain. In the presence of zinc, at acid pH, most insulins form crystals composed of insulin hexamers. The hexamer consists of three dimers arranged roughly in a plane. The central axis perpendicular to the plane passes through two zinc ions; each is co-ordinated with the imidazole groups of three BIO histidine residues with one located above and one below the plane of the hexamer. The insulin dimers are held together in the crystal by hydrogen bonds between amino acid B24 and amino acid B26, forming an antiparallel 13-pleated sheet structure (Steiner et al. 1989).
The insulin receptor
Authors: Siddle Kenneth
Published: November 2023

It has been widely accepted for many years that the metabolic effects of insulin are initiated by the binding of insulin to cell-surface receptors. It has become clear that there is only one type of insulin receptor, encoded by a single gene. The structure and activity of this receptor is understood in considerable detail, although many important aspects remain to be eludicated, from the mechanism of receptor activation at the molecular level to its involvement in pathophysiological processes in vivo.
Introduction to diabetes
Authors: Turner Robert , Neil Andrew
Published: November 2023

Diabetes is the name given to the clinical description of patients with a number of symptoms arising from raised glucose levels. The syndrome can occur from many specific ‘secondary causes’, including pancreatectomy, iron overload of the !3-cells resulting from haemochromatosis, excess cortisol production in Cushing’s syndrome, and excess growth hormone secretion in acromegaly and insulin-resistant syndromes, including insulin-receptor defects. The majority of patients do not, however, have any of these identified defects and are said to have ‘idiopathic’ diabetes. The metabolism of glucose involves many organs, in each of which several important metabolic steps occur. Key regulatory points include hepatic regulation of glucose uptake and release, muscle utilization of fuels, control by pancreatic production of insulin and glucagon, and neurogenic controls. Diabetes may arise from abnormalities at one or several sites in the complex feedback loops in this system. Two main types of diabetes can be distinguished. Different nomenclatures for these types have arisen because overlap between the types makes a strict, simple classification covering all patients impossible.
Aetiology of type II diabetes
Authors: Cerasi Erol
Published: November 2023

Type II diabetes is certainly the most common form of the disease, even in Scandinavia where the prevalence of type I diabetes is remarkably high. The past decades have seen an increase in type II diabetes in Western societies, which cannot be accounted for solely by improved diagnostic procedures or increased longevity (Everhart et al. 1985). In addition, the traditionally low prevalence of type II diabetes in the Far East and in developing countries is rapidly becoming a feature of the past, due to the ongoing improvement in standards of living. It seems certain, therefore, that humanity will enter the twenty-first century with at least twice as many type II diabetics as today, unless curative measures can be established during this decade.
Development, technology, and utilization of capillary columns for gas chromatography
Authors: Dawes Peter A
Published: November 2023

The concept of using hollow tubes as chromatography separation columns stemmed from a theoretical mathematical investigation and later experimental work by Marcel Golay in 1957. The more correct terminology for this invention is open tubular capillary column but the shortened and more general terminology of ‘capillary column’ has found its way into common use. The most obvious benefit of capillary columns over packed columns was the increased resolving capacity. An examination of the van Deemter equation will yield several reasons why a capillary column can have higher resolving power than a packed column. A large contributing factor is, however, simply the increased length.
Gas chromatography in analytical toxicology: principles and practice
Authors: Flanagan Robert j.
Published: November 2023

Analytical toxicology is the detection, identification and, if appropriate, measurement of drugs and other poisons in biological and other relevant specimens to aid the diagnosis, treatment, prognosis, and in some cases the prevention of poisoning. The specimens encountered may range from the relatively simple, such as expired air, to amongst the most complex of samples, the residue from a decomposed body. This being said, most work is performed on commonly available samples such as blood and urine. In analytical toxicology, gas chromatography (GC) has three principal advantages over other widely-used techniques such as high-performance liquid chromatography (HPLC) and immunoassay. First, GC has a range of sensitive detectors [‘universal’: flame ionization detector (FID); selective: nitrogen/phosphorus detector (NPD), electron capture detector (ECD)] which can be used in parallel. Second, high efficiency (capillary) GC columns are now widely available. Third, GC is easy to interface with techniques giving direct information about compound identity such as mass spectrometry (MS) and Fourier-transform infrared spectrometry (FTIR). With GC, as with HPLC, qualitative and quantitative information can often be obtained simultaneously.
Gene promoter analysis of malting enzymes
Authors: Skriver K , Olsen F L , Leah R , Mundy J
Published: November 2023

Malt hydrolase production is primarily determined by the rate of hydrolase gene expression, which is controlled by the antagonistic hormones gibberellin (GA) and abscicic acid (ABA). We have studied this mechanism in aleurone cells transformed with gene constructs which are responsive to GA (a-amylase), ABA (rab), or which are insensitive to the hormones (chitinase & lipid transfer protein). We have thereby defined gene regulatory regions determining hormone sensitivity, and those which confer constitutive, high level expression in aleurone cells. These DNA elements may be used to design malting varieties with novel patterns of hydrolase production by genetic engineering.
Non conventional methods for rapid production and malting/brewing quality evaluation of new barley varieties
Authors: Orive M , Batalla G , Cerveró J A , Torrent J
Published: November 2023

Increased efficiency in barley breeding programs would offer maltsters and brewers a wider, high quality range of brewing varieties. Thus ANTHER CULTURE is optimized for routine application in commercial breeding providing pure line field material 1^ years after crossing. For quality screening of this scarce seed, rapid and highly discriminative barley/malt analyses (NIR, HPLC, SMALL SCALE METHODS) are developed and validated. RFLP’s, ISOZYMES and HORDEINS would allow selection 1 year after crossing. Therefore isozyme and protein capillary electrophoretic, HPLC patterns are obtained. Since they maximize discriminatory power of hordein electrophoresis, rapid, objective identification of individual varieties is achieved.
Advances in the fermentation of high gravity wort
Authors: D’Amore Tony , Celotto Guy , Stewart Graham G
Published: November 2023

The fermentation of high gravity wort (16°P to 34°P) by a lager yeast strain has been investigated. As the wort gravity is increased, stress effects such as high osmotic pressure and elevated ethanol levels become more apparent, resulting in reduced yeast viability and incomplete fermentation. The fermentation of 25°P wort on a pilot plant scale (30 1 to 16 hl) was successfully performed by altering such parameters as the fermentation temperature, wort oxygen level and yeast pitching rate. Differences in the production of acetaldehyde, esters, higher alcohols and intracellular trehalose were observed. The resulting beers were found to be comparable to commercial products.
Present and future legislation of food hydrocolloids
Authors: Gray P S , Penning W
Published: November 2023

The development of the EC legislative system and programme of food law harmonisation is described and the roles of the various institutions the Commission, the Council, the Parliament and the Court of Justice is explained. The numerous judgements of the Court of Justice on food are briefly dealt with giving special attention to their effect on national food law and the way in which the are complementary to the harmonisation programme.
Gel profile star diagrams as a technique for the visualisation of gel texture
Authors: Sworn Graham
Published: November 2023

Nine key characteristics of alginate gels have been measured using Texture Profile Analysis. These are; Modulus, Hardness and Brittleness at acid and neutral pH, Hardness with high and low methoxyl pectin, and Gel Strength Build-up. Syneresis has also been measured. From this data 8 point Gel Profile Star Diagrams have been constructed which illustrate the effects of mannuronic/guluronic acid ratio, degree of calcium conversion, pH, and type of pectin.
Rheological and sensory properties of lemon pie filling
Authors: Hill Margaret A
Published: November 2023

A range of lemon pie fillings containing the ingredients corn starch, sugar, lemon juice, egg yolk and water have been prepared using a constant weight mixture design. There were five ingredients in the system and four ratio variables Xl to X4 were used. A central composite design was employed resulting in 25 formulations. Dynamic rheological measurements were made on the formulations using the Carri-Med Controlled Stress Rheometer. Multiple regression analysis of the results has produced models which predict the effect of each ratio variable Xl, X2, X3 and X4 on the rheological parameters , and G’. Linear, squared and interaction terms were included fn the models. Sensory analysis using magnitude estimation evaluated the characteristics of thickness, sweetness and lemon flavour; statistical analysis (multiple regression) was used in the same way as for the rheological data yielding again three predictive models. Perceived sweetness at an approximately constant level of sugar to water is depressed by the addition of lemon juice and corn starch but enhanced by egg yolk.
Calcium-dependent solubility and rheological properties of some plant polysaccharides
Authors: Stephen Alistair M , Linder Peter W , Churms Shirley C
Published: November 2023

Extraction of pectic material from the leaves of Aloe ferox is largely dependent on the removal of calcium ions. Juice squeezed from leaf, and hot-water extracts of the residual pulp, contain mineral salts and polysaccharides low in uronic acid residues. Treatment with aqueous oxalate, citrate or phosphate permits the extraction from pulp of good yields of polysaccharide that forms viscous solutions and, on restoration of Ca2+ ion, gels. Dialysis of the ammonium salt of the pectic polysaccharide ( 50% -GalEA content) against flowing tap water yielded a gel inside the membrane, the metal ion content of which, in comparison with that in the exterior aqueous medium, showed the relative selectivity coefficients for Ca:Mg:Na:K to be in the approximate ratio 100:20:7:20. Further dialysis against distilled water lowered the percentages of ions present in dried gel to Ca2+ 8.7, Mg2+ 0.14, Na+ 0.32 and K+ 0.23. Steric-exclusion chromatography showed a value of 40 000 for the molecular weight of the soluble pectic salt, raised to 330 000 on addition of Ca2+; this was followed by gel formation. Exudate from Cycad cones, a mannoglucuronoglycan with ramified acidic rhamnoarabinogalactan attached to Man in the core, consists of a weak gel from which a low molecular weight (10 000) fraction is extractable with aqueous ethanol. The residual gel is readily dispersed in aqueous sodium carbonate and then has mol. wt. 180 000, not increased on Ca2+ addition although viscosity lowering does result. The solution properties of the two types of polysaccharide, which resemble those of Khaya grandifoliola gum and gum ghatti respectively, are dependent on the relative dispersions of uronic acid groups in the different molecular structures.
Rheological behaviour and sol-gel transition of galactomannan/kappa-carrageenan blends
Authors: B.Fernandes P , Alves M P Gon , L.Doublier J
Published: November 2023

The sol-gel transition zone of mixtures of a galactomannan(locust bean gum or guar gum) with JC-carrageenan has been studied by oscillatory shear and viscosity measurements at 1s0c. Phase diagrams were established for these blends, relating the total polymer concentration of the mixed system to the JC-carrageenan/galactomannan ratio. From these phase diagrams, the JC-carrageenan content at which the sol-gel transition takes place can be estimated. This was found to be constant, whatever the total polymer concentration investigated and was lower than in the case of JC-carrageenan alone.
Kappa carrageenan-mannan interaction: a theoretical approach
Authors: Tvaroska I , Rochas C , R.Taravel F , Turquois T
Published: November 2023

A computer program SAINT has been developed for the investigation of the structure and for the prediction of minimum-energy structure of polysaccharide polysaccharide complexes. The energy minimization is carried out on internal geometrical parameters, namely bond angles, torsional angles and five parameters describing the mutual orientations of polysaccharide chains. For this purpose, the non-derivative method of conjugated directions is used. This procedure was applied to computer modeling of the interactions between models of kappa carrageenan and mannan. It is shown that the interaction between two chains influences the structure of the individual polysaccharide molecule and that in the minimum-energy structures of the complex, the conformation of the chains does not correspond to the lowest energy.
The texture of short dough biscuits produced from reconstituted flours
Authors: Oliver G
Published: November 2023

A soft wheat flour was subjected to a series of fractionation/reconstitution experiments. Reconstituted flours were used in the production of short dough biscuits and their quality was compared to those from original unfractionated flour. The aim was to produce biscuits from the reconstituted flour with similar characteristics to those from the original (control} flour. The main quality parameter was taken as biscuit texture as this is of major importance in the consumer acceptance of biscuits. Biscuits produced from a flour reconstituted after a fractionation procedure that did not include a lipid-depletion step were of similar dimensions and colour to control biscuits. Biscuits from this reconstituted flour, however, were twice as hard as those from the control flour. In order to produce biscuits with similar texture to those from control flour it was necessary to adopt a fractionation procedure in which the flour was first depleted in lipid, by extraction with petroleum ether, prior to further (aqueous} fractionation. Biscuits from flour produced in this way were of similar colour and dimensions to those from control flour and were only slightly harder.
Effect of non-adsorbing polymer on dispersion stability
Authors: M.Clegg S , J.Snowden M , A.Williams P , D.Robb I
Published: November 2023

This paper describes work carried out on the behaviour of model silica particles dispersed in water containing non-adsorbing (carboxymethyl cellulose and polystyrene sulphonate) polymers. The pair potentials of the particles have been calculated using current quantitative models of depletion flocculation and DLVO theory, with the depth of the secondary minima in the energy curves being used as an index for the onset of flocculation. The depletion flocculation of the particles by polystyrene sulphonate shows excellent agreement between theory and experimental observations, but this was not the case for carboxymethyl cellulose. The discrepancies between theory and experiment may be explained in terms of the high polydispersi!Y of the carboxymetbyl cellulose samples, particularly with respect to the charge distribution as a function of chain length.
Preparation, physical properties and potential food applications of enzymically-debranched araban from sugar-beet
Authors: M.Cooper J , .Mccleary B V , R.Morris E , K.Richardson R , M.Marrs W , J.Hart R
Published: November 2023

Enzymic debranching of sugar beet arabinan yields essentially linear chains of 50-80 1,5-linked a-L-arabinofuranosyl residues. Solutions of this material ("araban") at sufficiently high concentration (typically 10-20% w/w) develop a cohesive, but spreadable, gel-like structure on storage at or below ambient temperature. Electron microscopy shows a network of randomly oriented microfibrils around 200 nm in length. Gel strength (storage modulus, G’) rises dramatically with concentration (c), 20% samples being about 80 times stronger than those prepared at 10% w/w. The onset of gelation occurs far more rapidly at higher concentrations, with gel-times (at 20’C) decreasing from about 15 hours at 10% w/w to about 30 minutes at 20%. Reduction in temperature also accelerates gel formation (by just over a factor of two between 25’C and l0’C). The gels are stable to comparatively high temperature, with final loss of cohesion occurring at ∼7oc for the weakest samples, increasing to ∼9oc for the strongest. The potential of araban for use in fat replacement, and in other food and non-food applications is discussed.
Microgels, superswelling gels and macrogels from alginates. New possibilities for an old polymer?
Authors: Smidsrod Olav , Moe Storker T , Draget Kurt , Skjak-Braek Gudmund
Published: November 2023

In the last decade there has been an increasing interest in the use of alginates in biotechnological, biomedical and pharmaceutical applications. The use of alginate as an immobilization material for cells and biocatalysts is an example of this trend (1). These new applications set new specifications on alginates with respect to purity, chemical composition, molecular weight and molecular weight distribution. In addition, a detailed understanding of the gelling mechanism is necessary for manipulation of the gelling process to obtain gels of the right strength, porosity, size, shape and homogeneity. In this paper we shall review some of our recent research in this field and explore if some of the new findings could have an impact on the use of alginate as food additive and see if they point towards possibilities for new applications.
Turbidity study of casein micelles
Authors: Sano Yoh , Niki Ryoy A , Ama Kaoru Kohy , Nishinari Katsuyoshi
Published: November 2023

Casein micelles of different sizes were prepared by centrifugation and the distribution of particle sizes was analyzed by turbidity measured with a conventional visible spectrophotometer. The molecular weight and the diameter of casein micelles determined by turbidity correlated fairly well to the centrifugation speeds. The higher the speed the smaller the casein micelles. Aggregation and gelation of casein micelles in the presence of rennet was studied as a function of micelle sizes. The smallest micelle had the shortest gelation time, the largest rate constant and also the largest saturated elastic modulus of three size micelles.
Chain associations of konjac mannan in fibres and gels
Authors: P.Millane R , L.Hendrixson T , J.Morris V , Cairns P
Published: November 2023

The crystal structure of native (acetylated) konjac glucomannan has been studied using x-ray fiber diffraction. The polysaccharide packs isomorphously with the crystal structure of mannan II. Molecular modelling, and measurements of the crystallite size in moist fibers, indicate that the crystal structure incorporates only acetate free segments of the glucomannan. These results suggest a role for such structures in junction zones of konjac mannan gels.
Routine analysis of acacia gums by dynamic light scattering
Authors: White Roger , W.Anderson Douglas M , Claes Paul
Published: November 2023

Dynamic Light Scattering (DLS) can be used on-line in conjunction with the liquid chromatography of molecules to determine translational diffusion coefficients (Dt) and hydrodynamic radii (Rh) . From this data, relative molecular weights can also be calculated. Laser light scattered by molecules moving in solution under Brownian motion fluctuates in intensity as the motion proceeds. The time scale of this fluctuation is related to Dt for the molecules under observation and can be computed. The Dt measurement is fundamental and does not rely on any form of calibration. The Rh of the molecule is obtained from the Stokes-Einstein equation and the molecular weight calculated by means of an empirically derived algorithm.
Cytogenetics in acute lymphoblastic leukaemia
Authors: Gibbons B , Czepulkowski B H
Published: November 2023

In the past, cytogenetic analysis of acute lymphoblastic leukaemia (ALL) has been hampered by the difficulty of obtaining good quality chromosomes. Poor spreading, fuzzy chromosomes, and indistinct bands meant that only about 50% of analysed cases were classified as having an abnormal clone. In addition, a number of cases also had metaphase spreads which were classified as unanalysable, and consequently failed.
Use of protein phosphatase inhibitors in intact cells
Authors: Hardie D Grahame
Published: November 2023

A widely used approach for studying the roles of protein phosphorylation is the pharmacological one, i.e. to study the effects of cell-permeable inhibitors or activators of the enzymes which catalyse changes in phosphorylation. In the case of protein kinases, such compounds have been available for some time, and their use is described in Chapter 4. Recently, a variety of very potent, cell-permeable inhibitors of serine/threonine-specific protein phosphatases have been discovered, and their impact has been considerable.
Immunoassays for growth factors
Authors: Capper Stephen J
Published: November 2023

The term growth factors is typically applied to those proteins that are involved in cellular proliferative responses such as epidermal growth factor (EGF), platelet-derived growth factor (PDGF), and fibroblast growth factor (FGF). Although immunoassays for these and several other growth factors have been described, there are also many immunoassays described for cytokines and lymphokines such as the interleukins, (e.g. IL-1), and tumour necrosis factors (TNF). They can also be regarded as having proliferative or growth promoting actions. Furthermore, from an immunoassay point of view there are no real differences between developing an assay to a growth factor or a cytokine, and so I will refer to principles and examples applicable to both types of protein in this chapter.
Antibodies and crossmatching for transplantation
Authors: Martin Susan , Claas Frans
Published: November 2023

Alloantibodies directed against HLA antigens can be produced in response to three different types of stimuli: • pregnancy • blood transfusion • transplantation The method of antigen presentation, the dose of antigen, and hence the nature of the response differs for each of these stimuli which can all have occurred in a potential transplant recipient.
Isolation and culture of factordependent haemopoietic cell lines
Authors: Spooncer E , Boettiger D , Dexter Mdt.M
Published: November 2023

Our ability to stimulate proliferation and development of haemopoietic progenitor cells in vitro in clonal assays has led to a greater understanding of the hierarchical nature of the haemopoietic system, and an appreciation of the relationships between different cell lineages (see Appendix 1). These assays provided the means for the development of methods to enrich, and therefore to characterize, the various colony-forming cells, and to purify and isolate growth factors that are essential for the survival, growth, and differentiation of both multipotent and more developmentally restricted progenitor cells. Once these factors have been cloned, questions related to their interactions with target cells and target cell responses are raised. For example: what determines whether or not cells undergo self-renewal rather than differentiation? Following receptor binding, how are signals transduced that lead to the complex events seen upon addition of growth factors? What are the molecular mechanisms underlying the choice of developmental options that manifests as lineage committment? With normal bone marrow cells, these questions are very difficult to approach since self-renewal ability and multipotentiality are characteristics of stem cells that are few in number, and which (so far) have proved refractory to attempts to induce self-renewal in vitro as a ‘pure’ cell population.
Compositional analysis of glycoproteins
Authors: Manzi Adriana E , Varki Ajit
Published: November 2023

Once a protein has been purified to homogeneity (or radiochemical purity in the case of metabolically-labelled molecules), it is of interest to know if it is a glycoprotein. Several indirect methods can be used to detect the presence of sugars on the protein (e.g. lectin blotting, periodate oxidation/biotin hydrazide coupling, metabolic-labelling with radioactive monosaccharides). This chapter concerns itself with the next step: obtaining an accurate compositional analysis of a glycoprotein in terms of the molar ratios of the various monosaccharides present on it. In some cases, the techniques described in this chapter may serve as the first indication that oligosaccharides are indeed present on a protein. This chapter is primarily focussed on glycoproteins from animal sources, which tend to have a restricted number of types of monosaccharides: o-galactose, o-mannose, o-glucose, L-fucose, oxylose, N-acetyl-o-glucosamine, and N-acetyl-o-galactosamine, uronic acids, and non-ulosonic acids (sialic acids).
The biological and molecular basis for cell tropism in HIV
Authors: Planelles Vicente , Li Qi-Xiang , Chen Irvin S Y
Published: November 2023

Human immunodeficiency virus (HIV) is the primary etiologic agent for the acquired immunodeficiency syndrome (AIDS). HIV exhibits high genetic variation, which results in a wide variety of biological phenotypes displayed by different strains of this virus. Phenotypic heterogeneity of HIV is found in replication kinetics, susceptiblity to serum neutralization, antiviral drug resistance, induction of cytopathicity, and host range specificity. The host range of HIV, also termed ‘tropism’, constitutes a complicated scenario. Different strains of this virus show varying abilities to infect a spectrum of cell types in vivo as well as in vitro. The ability of HIV isolates to infect certain tissues and cell types has been associated with different pathologic manifestations. Tropism can arise from viral sequence variation in combination with environmental selection mechanisms. This chapter will discuss the current knowledge of tropism of HIV and its molecular determinants.
7 The molecular biology of human T-cell leuketnia viruses
Authors: Gitlin Scott D , dittmer Jürgen , Reid Robert L , Brady John N
Published: November 2023

The human I-cell leukemia virus (HTLV) was first described in the early 1980s following the isolation of the virus from cell lines established from an American patient with a cutaneous I-cell lymphoma (1). At approximately the same time, a similar virus (adult I-cell leukemia retrovirus; ATLV) was independently isolated from a Japanese patient with adult T-cell leukemia/lymphoma (ATL) (2). Based on the homology between the viral genome and viral antigens, the name HTLV-1 was proposed for viruses previously designated HTLV or ATLV. Another member of the HTLV subfamily, HTLV-11, was first isolated from the transformed I-lymphocytes of a patient with a relatively benign T-cell variant of hairy cell leukemia and later from a second patient with both a T-cell lymphoproliferative disease and hairy cell leukemia with a B-cell phenotype (3, 4). Recently, HTLV-11 has also been isolated from Guaymi indians in Panama (5).
The molecular biology of the human spumavirus
Authors: Flugel Rolf M
Published: November 2023

Twenty years after the first isolation and morphological characterization of a human spumaretrovirus (HSRV) from the lymphoblastoid cells of a nasopharyngeal carcinoma patient (1) and 5 years after the first molecular-biological characterization of this isolate (2, 3), spumaviruses have begun to attract significant research interest. The spumaviruses are of interest for several reasons: 1. Spumaviruses, also called foamy viruses, occupy a biological niche that sets them significantly apart from other retroviruses and, in particular, from the intensely studied oncoviruses (4, 5).
Proline Isomerization as a Rate-Limiting Step
Authors: Nall Barry T
Published: November 2023

For our generation the deduction of the form, function, and biological consequences encoded by a protein's primary structure is the major challenge in biophysics. An understanding of the protein folding code is needed to bridge the gap between information-bearing molecules and the functional chemistry of the three-dimensional world in living systems. As the means of gathering sequence information outstrips our ability to determine structures experimentally, the problem of learning how to infer three-dimensional structure from amino acid sequence is gaining in importance. A priori approaches demonstrate the necessity of a close interaction between experiment and theory. Faced with almost overwhelming complexity, theoreticians need experimental information to narrow the focus of theoretical solutions. To avoid becoming unwieldy and to maximize the potential for success, solutions to the folding problem must include only required aspects of the sequence-structure relationship. Thus, theoretical attempts at solving the folding problem rely increasingly on an experimentally-determined mechanistic understanding of the details of structure reformation in refolding.