Showing papers by "University College Cork published in 1990"

Localization of the malignant hyperthermia susceptibility locus to human chromosome 19q12-13.2.

Abstract: MALIGNANT hyperthermia (MH) is an inherited human skeletal muscle disorder and is one of the main causes of death due to anaesthesia1. The reported incidence of MH varies from 1 in 12,000 in children to 1 in 40,000 in adults2,3. MH is triggered in susceptible people by all commonly used inhalational anaesthetics; it is characterized by a profoundly accelerated muscle metabolism, contractures, hyperthermia and tachycardia1,4,5. Susceptibility to MH (MHS) is predicted by contracture tests on muscle tissue obtained by biopsy6,7. An almost identical disorder known as porcine MH exists in pigs8,9. The genetics of the porcine syndrome have been extensively studied10; the locus controlling expression of porcine MH is genetically linked to the glucose phosphate isomerase locus (GPI)11. In man, GPI has been mapped to the q12–13.2 region of chromosome 19 (refs 10–12). We have now investigated genetic linkage in several extended Irish pedigrees in which MHS is segregating as an autosomal dominant trait. Here we show linkage between MHS and DNA markers from the GPI region of human chromosome 19 with a maximum log likelihood ratio (lod score) of 5.65 at the CYP2A locus. These results indicate that human and porcine MH are most probably due to mutations in homologous genes, and also provide a potentially accurate and noninvasive method of diagnosis for MHS.

Glycolysis and related reactions during cheese manufacture and ripening

Abstract: Fermentation of lactose to lactic acid by lactic acid bacteria is an essential primary reaction in the manufacture of all cheese varieties. The reduced pH of cheese curd, which reaches 4.5 to 5.2, depending on the variety, affects at least the following characteristics of curd and cheese: syneresis (and hence cheese composition), retention of calcium (which affects cheese texture), retention and activity of coagulant (which influences the extent and type of proteolysis during ripening), the growth of contaminating bacteria. Most (98%) of the lactose in milk is removed in the whey during cheesemaking, either as lactose or lactic acid. The residual lactose in cheese curd is metabolized during the early stages of ripening. During ripening lactic acid is also altered, mainly through the action of nonstarter bacteria. The principal changes are (1) conversion of L‐lactate to D‐lactate such that a racemic mixture exists in most cheeses at the end of ripening; (2) in Swiss‐type cheeses, L‐lactate is meta...

Equivalence class formation in non-hearing impaired children and hearing impaired children.

Abstract: The relationship between verbal behavior and stimulus equivalence was examined using three sets of children differing in chronological age and verbal ability: (1) non-hearing impaired three and four year olds who had verbal skills generally consistent with their chronological ages; (2) partially hearing (severe to profoundly deaf) children who were rated with verbal ages of above 2 years; and (3) partially hearing children (also severely to profoundly deaf) who were rated with verbal ages of below 2 years. All children were taught a series of four conditional discriminations using unfamiliar stimuli. The children were then tested to determine whether classes of equivalent stimuli had formed. Although all the children were able to learn the conditional discriminations equally well and all the verbally-able children (normal and partially hearing) formed equivalence classes, only one of the verbally-impaired children reliably demonstrated stimulus equivalence formation. These results are consistent with the suggestion that stimulus equivalence and human verbal behavior are closely related.

Identification of the Minimal Replicon of Lactococcus lactis subsp. lactis UC317 Plasmid pCI305.

Abstract: Replication functions of the stable, cryptic 8.7-kilobase (kb) plasmid pCI305 from multi-plasmid-containing Lactococcus lactis subsp. lactis UC317 were studied. Analysis of this replicon was facilitated by the construction of replication probe vectors that consisted of the pBR322 replication region, a pUC18-derived multiple cloning site, and either the cat gene of pC194 (pCI341; 3.1 kb) or the erm gene of pAMβ1 (pCI3330; 4.0 kb). Plasmid pCI305 was introduced into plasmid-free L. lactis subsp. lactis MG1363Sm, a streptomycin-resistant derivative of MG1363, by a transformation procedure with the 75-kb lactose-proteinase plasmid pCI301 of UC317 as a marker plasmid. A combination of transposon Tn5 mutagenesis and subcloning in pCI341 and pCI3330 with individual Tn5 insertions around the replication region facilitated the identification of a 1.6-kb minimal replicon on pCI305. This region was separable into two domains: (i) a 1.3-kb region (repB) encoding a trans-acting function (in vitro transcription-translation studies suggested the involvement of a 48-kilodalton protein); and (ii) a 0.3-kb region (repA) sufficient to direct replication when provided with repB in trans and thus probably containing the origin of replication. Lactococcus-Escherichia coli shuttle vectors based on the pCI305 replication region were constructed.

Localization of the malignant hyperthermia susceptibility locus to human chromosome 19q12-q13.2.

Abstract: Malignant hyperthermia (MH) is an inherited human skeletal muscle disorder and is one of the main causes of death due to anaesthesia. The reported incidence of MH varies from 1 in 12,000 in children to 1 in 40,000 in adults. MH is triggered in susceptible people by all commonly used inhalational anaesthetics; it is characterized by a profoundly accelerated muscle metabolism, contractures, hyperthermia and tachycardia. Susceptibility to MH (MHS) is predicted by contracture tests on muscle tissue obtained by biopsy. An almost identical disorder known as porcine MH exists in pigs. The genetics of the porcine syndrome have been extensively studied; the locus controlling expression of porcine MH is genetically linked to the glucose phosphate isomerase locus (GPI). In man, GPI has been mapped to the q12-13.2 region of chromosome 19 (refs 10-12). We have now investigated genetic linkage in several extended Irish pedigrees in which MHS is segregating as an autosomal dominant trait. Here we show linkage between MHS and DNA markers from the GPI region of human chromosome 19 with a maximum log likelihood ratio (lod score) of 5.65 at the CYP2A locus. These results indicate that human and porcine MH are most probably due to mutations in homologous genes, and also provide a potentially accurate and noninvasive method of diagnosis for MHS.

Effect of Ingredients on Physical/Structural Properties of Extrudates

Abstract: The influence of three ingredients (bran, sucrose, magnesium carbonate) commonly used in extrusion-cooking of wheat flour-type formulations was studied. Extrusion-cooking was carried out in a twin-screw corotating extruder. The effects of the ingredients were analyzed by determining extrusion parameters, physical properties (apparent density, modulus of deformability and breaking stress) and structural properties (computerized image analysis of the transverse cut of extrudate). An increase in apparent density occurred when concentration of any ingredient increased. Cell number per pixel area increased greatly while average cell size decreased as bran concentration increased from 0 to 16%. Average cell size increased as magnesium carbonate increased from 0 to 0.4%, but cell size decreased above 0.4%.

Effects of Dietary Oils and α‐Tocopherol Supplementation on Membranal Lipid Oxidation in Broiler Meat

Abstract: The effects of different dietary oils and α-tocopherol on the fatty acid composition of mitochondrial and microsomal lipids of broiler muscle and their lability to NADPH-induced peroxidation were investigated. Fatty acid composition of both neutral lipids and phospholipids of mitochondria and microsomes was influenced by dietary oil composition. Supplementation of the diet with α-tocopherol only appeared to increase the α-tocophcrol concentration in the microsomal membranes in the dark meat. The rate of NADPH-induced lipid peroxidation in microsomes and mitochondria was dependent primarily on the fatty acid composition of the membrane lipids, and, to a lesser extent, on the α-tocopherol content.

Observations on plasmin activity in cheese

Abstract: Levels of plasmin activity in various commercial cheeses are reported. The effects of some processing conditions (pH, cooking temperature and method of salting) on plasmin activity in cheese were investigated. Neither draining pH nor method of salting affected the activity. However, plasmin activity in cheese, rennet curd and micellar casein dispersions increased with increasing cooking temperature. The results suggest that plasmin activity in cheese depends on cooking temperature used during manufacture.

Sodium-calcium inter-relationships with specific reference to osteoporosis

Abstract: INTRODUCTION . . 101 PHYSIOLOGICAL BASIS FOR THE RELATIONSHIP BETWEEN URINARY SODIUM A N D CALCIUM . . 102 EFFECT O F SALT SUPPLEMENTATION O N CALCIUM METABOLISM I N T H E R A T . . . 102 RELATIONSHIP BETWEEN U R I N A R Y SODIUM A N D CALCIUM EXCRETION IN M A N . . . 104 STUDIES ON FREE-LIVING I N D I V I D U A L S . . 104 STUDIES WITH CONTROLLED SODIUM I N T A K E . . . 106 MAGNITUDE OF SODIUM-INDUCED C A L C l U R l A . . 107

Objective indices of cheese ripening

Abstract: Cheese ripening is a complex process. Attempts to understand the process have led to the development of objective measurements which, hopefully, will be able to predict the final quality of cheese when it is offered for sale. Sensory evaluation of cheese relies on the ability of a grader to examine a small random sample from a batch of cheese and predict the quality of the cheese at a later date. Unfortunately, the results of sensory evaluation of cheese are subjective, and various objective chemical and rheological approaches to evaluating cheese ripening have been developed and assessed.

The MERMAID Approach to software cost estimation

Abstract: Despite the large supply of methods and tools for cost estimation, estimating the costs of a software development project remains a non-trivial activity. Research [Heemstra 1989, Mermaid 1989] has shown that the accuracy of such tools is low. It has also been shown that only a limited group of organizations uses systematic methods for drawing up a cost estimate for project-based software development. For many years, various lines of industry (for example the building industry and the catering industry) have used experience figures when drawing up cost estimates for projects. Cost estimates for software projects often lack such a basis, partly because there are no adequate tools for recording and analysing historical project data. This paper presents an analysis of the problems in the field of software cost models and describes the MERMAID approach to cost estimation. The MERMAID approach makes intensive use of local historical project data and is applicable in all sectors where project data can be collected.

Personality disorder and psychiatric illness in general practice.

Abstract: In a one-year prevalence study of conspicuous psychiatric morbidity in two group general practices, one urban and the other rural, personality disorder was diagnosed in 5.3% by the GP and in 5.6% by the psychiatrist, but this increased to 28% when personality disorder was assessed using a structured interview. The prevalence of personality disorder was higher in the urban practice than in the rural one but there was no consistent association between personality disorder and mental state disorder, with the exception of alcohol abuse and dependence. The high rate of personality disorder found using the interview schedule is likely to be a true finding, and failure to recognise this hidden morbidity is important in both general and psychiatric practice.

Changes in the starch content during organogenesis in in vitro cultured Begonia rex stem explants

Abstract: Stem explants, excised from greenhouse-grown Begonia rex plants, were cultured on basal medium (T Murashige and F Skoog, Physiol Plant 15: 473–497, 1962) contained in sterile Petri dishes The medium was supplemented with benzyladenine (01 mg 1−1) naphthaleneacetic acid (001 mg 1−1) and, according to experimental requirements, with either sucrose (3%) or mannitol (3%) Histochemical and biochemical examination of the starch content of the explant was carried out over several days There was no starch deposition or organogenesis in tissue cultured on mannitol and carbohydrate-free growth medium The most dramatic finding was the heavy accumulation of starch in tissue cultured on sucrose medium This copious accumulation preceded any organ formation and was mainly in regions which ultimately gave rise to shoot primordia The heavy build-up of starch preceding organogenesis was also observed when explants previously cultured on mannitol medium were transferred to medium containing sucrose During shoot primordia development there was a decrease in the starch content of the cultured tissue indicating the utilization of the polyglucan in the organogenic process

Thymidylate synthase gene from Lactococcus lactis as a genetic marker: an alternative to antibiotic resistance genes.

Abstract: The potential of the thymidylate synthase thyA gene cloned from Lactococcus lactis subsp. lactis as a possible alternative selectable marker gene to antibiotic resistance markers has been examined. The thyA mutation is a recessive lethal one; thyA mutants cannot survive in environments containing low amounts of thymidine or thymine (such as Luria-Bertani medium) unless complemented by the thyA gene. The cloned thyA gene was strongly expressed in L. lactis subsp. lactis, Escherichia coli, Rhizobium meliloti, and a fluorescent Pseudomonas strain. In addition, when fused to a promoterless enteric lac operon, the thyA gene drove expression of the lac genes in a number of gram-negative bacteria. In transformation experiments with thyA mutants of E. coli and conjugation experiments with thyA mutants of R. meliloti, the lactococcal thyA gene permitted selection of transformants and transconjugants with the same efficiency as did genes for resistance to ampicillin, chloramphenicol, or tetracycline. Starting from the broad-host-range plasmid pGD500, a plasmid, designated pPR602, was constructed which is completely free of antibiotic resistance genes and has the lactococcal thyA gene fused to a promoterless lac operon. This plasmid will permit growth of thyA mutant strains in the absence of thymidine or thymine and has a number of unique restriction sites which can be used for cloning.

Tissue distribution of a coliphage and Escherichia coli in mussels after contamination and depuration.

Abstract: Experiments were undertaken to determine the tissue distribution of Escherichia coli and a coliphage after contamination of the common mussel (Mytilus edulis). Mussels were contaminated with high levels of feces-associated E. coli and a 22-nm icosahedral coliphage over a 2-day period in a flowing-seawater facility. After contamination, individual tissues were carefully dissected and assayed for E. coli and the coliphage. Contaminated mussels were also analyzed to determine the tissue distribution of the contaminants after 24- and 48-h depuration periods. The majority of each contaminant was located in the digestive tract (94 and 89% of E. coli and coliphage, respectively). Decreasing concentrations were found in the gills and labial palps, foot and muscles, mantle lobes, and hemolymph. Our results indicate that contamination above levels in water occurred only in the digestive tract. Contaminated mussels were depurated in a commercial-scale recirculating UV depuration system over a 48-h period. The percent reductions of E. coli occurred in the following order: digestive tract, hemolymph, foot and muscles, mantle lobes, and gills and labial palps. The percent reductions of the coliphage were different, occurring in the following order: hemolymph, foot and muscles, gills and labial palps, mantle lobes, and digestive tract. Our results clearly demonstrate that E. coli and the coliphage are differentially eliminated from the digestive tract. The two microorganisms are eliminated at similar rates from the remaining tissues. Our results also clearly show that the most significant coliphage retention after depuration for 48 h is in the digestive tract. Thus, conventional depuration practices are inappropriate for efficient virus elimination from mussels.

Cloning and characterization of the thymidylate synthase gene from Lactococcus lactis subsp. lactis.

Abstract: The thymidylate synthase (thyA) gene has been isolated from Lactococcus lactis subsp. lactis. The cloned gene was strongly expressed in Escherichia coli both in vivo and in vitro (maxicells and cell-free transcription and translation systems) and complemented E. coli thyA mutants. DNA-DNA hybridizations demonstrated that the thyA gene is encoded by the chromosome of L. lactis subsp. lactis. By sequential deletion of DNA outside the complementing region, the thyA gene was localized to a 1.1-kilobase DNA fragment. The nucleotide sequence of the lactococcal thyA gene was determined by the dideoxy-chain termination technique. The derived amino acid sequence indicated a protein size of 32,580 daltons, which is in good agreement with results obtained from maxicell and in vitro transcription and translation experiments. The primary sequence is homologous to 12 other thyA proteins from a variety of other organisms. Upstream from the structural gene, -10 and -35 promoter sequences which were almost canonical sigma-70 promoter sequences were identified, which may explain the strong expression of the thyA gene observed in E. coli. An A-T-rich sequence characteristic of gram-positive promoters was also noted adjacent to the -35 region. The thyA gene has potential as a marker for plasmid maintenance and selection in food systems.

Alluvial sedimentation patterns in the Munster Basin, Ireland

Abstract: Post-Caledonian southern Ireland witnessed the development of a NE-SW orientated half-graben known as the Munster Basin. More than 7 km of non-marine sediments accumulated in the basin during the late Middle and Late Devonian. Marine conditions became established in the southern part of the basin at the end of the Devonian. In this paper, a model for the evolving style of sedimentation in the basin and its periphery is constructed with the aim of identifying the major factors which controlled sedimentation patterns and the architecture of the basin fill. The depositional history of the basin is considered in terms of four successive episodes. During Episode I, gravelly alluvial fans flanked upland areas around the northeastern and northern basin perimeter. These graded southwestwards to a floodplain dominated by sheet-floods. In the western part of the basin, the first of three major fluvial influxes into the basin commenced. During Episode II, the first influx developed into a large sandy braided complex. The sediment was derived from a distant source area located to the north and west of the basin and was transported diagonally across the basin towards the southeast. Episode III witnessed a second influx which drained into the basin from the northeast and north. River channels were of low sinuosity and graded distally to an ephemeral playa lake. Episode IV was marked by a third fluvial influx from the west and northwest. This was confined to the southern half of the basin and drainage was directed towards the east. The fluvial distributaries were flanked by permanently flooded overbank areas. This influx coincided with the first marine transgression which advanced westwards. The end of Episode IV coincided with the beginning of the Carboniferous and was marked by a major marine transgression. Sediment input to the basin was influenced by stable areas occupied by granitic plutons on either side of the basin and a southward downthrowing fault along its northern margin. The drainage direction was principally controlled by E-W trending within-basin faults and an E-W trending stable area located to the south. The basin was fundamentally of the axial transport type, the main drainage having been directed towards the east though there was also a strong lateral influx from the north, northwest and northeast. Stable areas around the, basin periphery resulted in either no sediment preservation or sequences of multistorey channel deposits while thick sequences dominated by fine-grained floodplain or overbank deposits characterized areas of higher subsidence rate within the basin. Movement on the northern basin-margin fault was probably the major cause of the first fluvial influx, while regional subsidence of the basin and its northern periphery resulted in the second influx. The third influx was a response to local subsidence in the southern part of the Munster Basin. This also contributed to the simultaneous westward marine transgression in this area towards the end of the Devonian. Source area denudation and retreat in association with a sea-level rise were ultimately responsible for terminating the alluvial regime in the Munster Basin.

On maximal surfaces in asymptotically flat space-times

Abstract: Existenc of maximal and “almost maximal” hypersurfaces in asymptotically flat space-times is established under boundary conditions weaker than those considered previously. We show in particular that every vacuum evolution of asymptotically flat data for the Einstein equations can be foliated by slices maximal outside a spatially compact set and that every (strictly) stationary asymptotically flat space-time can be foliated by maximal hypersurfaces. Amongst other uniqueness results, we show that maximal hypersurfaces can be used to “partially fix” an asymptotic Poincare group.

Relative growth and maturation of axon size and myelin thickness in the tibial nerve of the rat. 1. Normal animals.

Abstract: Morphometric observations have been made on the medial plantar division of the tibial nerve (MPD) and on the motor branches of the tibial nerve to the calf muscles (MBC) in rats ranging in age from weaning (3 weeks) to 12 months. Axon size, assessed by measurements of circumference and cross-sectional area, increased rapidly until 3 months with further slight increases between 3 and 9 months and a slight fall between 9 and 12 months. Axon size distributions were unimodal throughout in the MPD but bimodal for the MBC except at 3 weeks. Distributions of myelin thickness were bimodal throughout for both nerves. Scatter plots of g ratios (axon diameter:total fibre diameter) confirmed the presence of two fibre populations: a group of small fibres with relatively thin myelin sheaths, and a group of larger fibres within which sheath thickness was relatively less on the larger than on the smaller axons. These two fibres populations were less easily separable in the MBC than in the MPD nerves. These results document morphometrically the normal growth changes in the rat tibial nerve and also provide control data for the analysis of the effects of experimental procedures on the growth and maturation of peripheral nerve fibres.