Showing papers by "University College Dublin published in 1968"
TL;DR: In this paper, the binding energies of light hypernuclei were studied based on a sample of 2008 uniquely identified π − mesonic decays. And the problems of the calibration procedure and the selection criteria are discussed.
79 citations
TL;DR: In this paper, the constitution of melannein was established, and the synthesis of O-dimethylmelannein and O-diethylmelanein were described.
66 citations
TL;DR: An investigation to establish the role of fungi in the disease termed ulcerative dermal necrosis (UDN) which affects freshwater fish, particularly salmon.
Abstract: As part of the research programme on fish disease mentioned before1, we have undertaken an investigation to establish the role of fungi in the disease termed ulcerative dermal necrosis (UDN) which affects freshwater fish, particularly salmon. The fact that fungi are associated in some way with this disease is indisputable; indeed, diseased fish in the rivers are recognized chiefly by the presence of white fungoid patches.
44 citations
TL;DR: In this article, the chromium-oxygen stretching and deformation modes in Cr2O3 have been assigned on the basis of an octahedrally co-ordinated chromium ion.
44 citations
TL;DR: Choline O-sulphate acted as a source of choline for cholineless strains of Neurospora crassa, suggesting that cholineO-sULphate breakdown occurred by simple hydrolysis involving a choline sulphatase.
Abstract: 1. The position of the enzyme blocks in a number of parathiotrophic mutants of Aspergillus nidulans A 69 and mutants A and C of a biotinless mutant of Aspergillus nidulans were examined by nutritional and heterokaryosis experiments and by assay in vitro of enzyme systems and specific enzymes. 2. The mutants were in five groups: A and C blocked at sulphate transport; gamma at ATP sulphurylase; iota at adenosine 5′-sulphatophosphate kinase; eta at the adenosine 3′-phosphate 5′-sulphatophosphate reductase system; alpha, beta and zeta between sulphite and thiosulphate. 3. The ability of the various mutants to synthesize choline O-sulphate in vivo and in vitro and to utilize choline O-sulphate as a source of sulphur indicated that the utilization of endogenously formed choline O-sulphate involved the splitting off of inorganic sulphate, which was then reduced. 4. Choline O-sulphate acted as a source of choline for cholineless strains of Neurospora crassa, suggesting that choline O-sulphate breakdown occurred by simple hydrolysis involving a choline sulphatase. 5. After de-repression of mycelia by growing for a period on a sulphur-free medium the presence of choline sulphatase in physiologically significant amounts was demonstrated in all the A. nidulans strains tested. 6. Choline O-sulphate is transported across the mycelial wall by a mechanism different to that responsible for inorganic sulphate transport.
36 citations
TL;DR: Evidence on cleavage stages attained, and on the location of eggs in the Fallopian tubes and uterus, suggests that a majority of eggs were capable of normal development.
Abstract: SUMMARY Eighty-nine cattle were treated to induce high superovulation with 3000 i.u. PMSG on day 16 of the cycle and slaughtered shortly after breeding and injection of 2000 i.u. HCG. In the 79 cattle that came in oestrus, the mean number of ovulations was 9.0. The percentage of follicles ovulating and the mean ovulation rate increased markedly as the interval between PMSG and oestrus increased from 2 to 5 days. Seventy-one percent of eggs shed were recovered; 68% of eggs recovered were cleaved. Evidence on cleavage stages attained, and on the location of eggs in the Fallopian tubes and uterus, suggests that a majority of eggs were capable of normal development.
31 citations
TL;DR: In this article, attempts have been made to detect gamma radiation, or other neutral particles, from the source CP 1133 using the Cerenkov night sky technique4 in the energy region above 1012 eV.
Abstract: FOLLOWING the observations1–3 of sources of pulsed radio emission, attempts have been made to detect gamma radiation, or other neutral particles, from the source CP 1133 using the Cerenkov night sky technique4 in the energy region above 1012 eV.
24 citations
TL;DR: Inhibition of choline sulphatase activity in vivo was demonstrated with cysteine as the sulphur source for growth and Circumstantial evidence suggests that the co-repressor is Cysteine.
Abstract: 1. Choline O-sulphate is taken up from the growth medium to the same extent by sulphur-deficient and sulphur-sufficient mycelia of Aspergillus nidulans, but hydrolysis of the transported sulphate ester in vivo only occurs in the sulphur-deficient mycelia. 2. Choline sulphatase activity could not be detected in vitro in sulphur-sufficient mycelia of wild-type and sulphur mutants of A. nidulans, but after sulphur starvation all strains showed appreciable activity of this enzyme. 3. Optimum activity of choline sulphatase in an ultrasonically treated preparation of sulphur-deficient mycelia was at pH7·5. The optimum substrate concentration was in excess of 25mm and Km was 0·035m. The enzyme was completely inhibited by 10mm-SO32−, PO43−, CN− and cysteine. 4. Growth of sulphur-deficient mycelia on various sulphur sources resulted in a decrease of choline sulphatase activity in vitro. The decrease appeared to be due to a repression of choline sulphatase synthesis rather than to inhibition of activity. De-repression by growth on a sulphur-deficient medium was prevented by cycloheximide. Unlike the choline sulphatase of bacteria the fungal enzyme did not need to be substrate-induced. 5. By using sulphur mutants the identity of the co-repressor was limited to S2O32−, cysteine-S-sulphonate, cysteine or compounds derived directly from them. Circumstantial evidence suggests that the co-repressor is cysteine. 6. Inhibition of choline sulphatase activity in vivo was demonstrated with cysteine as the sulphur source for growth.
21 citations
TL;DR: In this article, a method for measuring disorder in complex decision types of systems is proposed, and used in the analysis of complex decision type of systems, where disorder frequently appears in the form of queues.
Abstract: Every system, left unto itself, tends towards disorder. Disorder frequently appears in the form of queues-machines, materials or customers waiting for service or waiting to be served. This article suggests a method of measuring disorder, and shows how this may be used in the analysis of complex decision type of systems.
20 citations
TL;DR: In this paper, it was shown that at a frequency greater than 100 MHz, the highly idealized model of Kahn and Lerche imposes a limiting frequency, because of coherence conditions, of about 75 MHz, while Colgate predicts a maximum emission at 1 MHz.
Abstract: RADIO pulses at frequencies below 100 MHz have been detected in association with extensive air showers at the zenith by many workers1–6, and subsequently at large zenith angles7,8. Current theories do not predict a detectable flux of radio frequency power at frequencies greater than 100 MHz—the highly idealized model of Kahn and Lerche9 imposes a limiting frequency, because of coherence conditions, of about 75 MHz, while Colgate10 predicts a maximum emission at 1 MHz. Tentative evidence supporting these predictions has been found in several experiments1,2,5. Because of the nature of the theoretical models used and the possibility of other mechanisms contributing strongly in the ultra high frequency region of the spectrum, an investigation at a frequency greater than 100 MHz was undertaken.
19 citations
TL;DR: In this article, the atmospheric Cherenkov technique was used to detect high energy (~ 10^(14) eV) neutral cosmic rays from CP 1133, using the atmospheric CHN technique.
Abstract: Several proposed models for pulsars, involving shock waves and high magnetic fields, suggest the possibility that high energy γ-rays may be emitted by such objects. We have therefore attempted to detect high energy (~ 10^(14) eV), neutral cosmic rays from CP 1133, using the atmospheric Cherenkov technique.
TL;DR: In vivo culture technique has facilitated the long distance transport of sheep ova and it is suggested that a similar technique may be applied to cattle ova.
Abstract: FERTILIZED sheep ova have been shown to continue cleavage to the early blastocyst stage after transfer to the reproductive tract of the female rabbit1. This in vivo culture technique has facilitated the long distance transport of sheep ova2. This report suggests that a similar technique may be applied to cattle ova.
TL;DR: An increased K(+) concentration was found to increase the Na(+) efflux by raising the saturation value, which is similar to observations made by Harris (1965) with frog muscle, and the curves obtained with yeast resembled those similarly obtained with frog sartorius muscle.
Abstract: 1. The activity of the Na(+) pump in an Na(+)-rich yeast was compared with that in an Na(+)-rich frog sartorius muscle, and found to be very similar to it over the first hour if both were immersed in fluid containing 104mm-Na(+) plus 10mm-K(+). 2. The efflux of labelled Na(+) from an Na(+)-rich yeast into an Na(+)-free medium was investigated. In this Na(+)-free medium, Li(+) or choline replaced the Na(+), and the efflux-content curves obtained with either of these ions were very similar. The curves were sigmoid, reaching or approaching a saturation at the higher internal Na(+) concentrations. 3. The curves obtained with yeast resembled those similarly obtained with frog sartorius muscle by Keynes & Swan (1959), Mullins & Frumento (1963), Harris (1965) and Keynes (1965). The slope of the plot of the logarithm of the Na(+) efflux against the logarithm of the Na(+) concentration in the cells reached its highest value at an internal Na(+) concentration of 15m-equiv./kg. (27m-equiv./l. of cell water). 4. The effect of external K(+) concentration on the efflux-content relationship was examined. An increased K(+) concentration was found to increase the Na(+) efflux by raising the saturation value, which is similar to observations made by Harris (1965) with frog muscle. 5. The effect of increasing the external carbon dioxide concentration was investigated. No effect on the slope of the plot of the logarithm of the Na(+) efflux against the logarithm of the Na(+) content was noticed even when the yeast suspension was equilibrated with 100% carbon dioxide. There was, however, a decrease in the amount of Na(+) efflux on equilibrating the solution with carbon dioxide.
TL;DR: The findings indicate that the homogenates and cell particles from these human cells can cause platelet aggregation, and it has been established that the highest coagulative activity is in the ‘microsomal’ fraction and probably associated with the endoplasmic reticulum.
Abstract: Haemostasis or the arrest of bleeding is a fundamental physiological mechanism, which prevents the leakage of blood after vessel injury by platelet clumping, vasoconstriction and fibrin formation. The haemostatic plug is composed primarily of platelets. The process of thrombosis involves mainly platelet clumping, and thrombi are very similar in composition to the haemostatic plug. There is accumulating evidence that recurrent thrombi forming on the walls of arteries may become absorbed into the wall and degenerate into atheromatous plaques. In this lecture some of the links have been drawn between the disease, atheroma and thrombosis and also between thrombosis and that vital phenomenon, haemostasis. Since cell injury is one of the earliest events in both haemostasis and thrombosis, we have broken open human cells and separated the intracellular components by differential centrifugation into ‘nuclear’, ’mitochondrial’, ‘microsomal’ and soluble fractions. The homogenates and individual cell fractions have been tested for their effect on platelet aggregation, coagulation and fibrinolysis. The findings indicate that the homogenates and cell particles from these human cells can cause platelet aggregation. It has also been established that the highest coagulative activity is in the ‘microsomal’ fraction and probably associated with the endoplasmic reticulum. These investigations on cell injury may have a relevance to the pathogenesis of shock, surgical trauma, acquired afibrinogenaemia of pregnancy, etc. as well as to the earliest lesions following cell injury at the vascular level.
TL;DR: Extraction of the heartwood of Dalbergia cochinchinensis gave R-5-O-methyllatifolin and the known R-latifolin, R-4-Methoxydalbergione, benzoic and salicylic acids.
TL;DR: A follow-up study of fasting plasma glucose, insulin and cortisol levels was carried out on nine patients following acute myocardial infarction, finding Hypoglycaemia accompanied by hyper-insulinism persisted while the glucose values returned to normal.
Abstract: A follow-up study of fasting plasma glucose, insulin and cortisol levels was carried out on nine patients following acute myocardial infarction. They were matched with hospital in-patients with reference to sex, height, age and weight. Hypoglycaemia accompanied by hyper-insulinism was observed in period one (0–7 days). These observations were statistically highly significant. In the subsequent stages the hyperinsulinism persisted while the glucose values returned to normal. No significant alterations in plasma cortisol, nor in 24-hour urinary V.M.A. excretion in period one were observed. The possible mechanisms are briefly discussed.
TL;DR: The cyclamigenins A 1 and C are 30β- (IXa) and 30α-(IXb) ethoxy-28.30-epoxyolean-12-en 3β,16α-diol, respectively as discussed by the authors.
TL;DR: In the course of a study on the gibberellin induced release of hydro lytic enzymes by barley endosperm, it was found that treatment with gibBerellic acid induced the production of substantial quantities of peroxidase.
Abstract: Gibberellins stimulate the release of reducing sugars and hydrolytic enzymes from barley endosperm (Paleg, 1960; Yomo, 1960; McLeod etal., 1962; Jones and Vabneb, 1967). The release of reducing sugars, which was shown to be proportional to the logarithm of applied gibberel lin concentration, has been used as a bioassay for gibberellins (Coombe et al., 1966). Vabneb and his co-workers have found the release of a amylase by isolated barley aleurone layers to be a more convenient method of bioassay (Jones and Vabneb, 1967). Both methods have been well documented and extensively used. In the course of a study on the gibberellin induced release of hydro lytic enzymes by barley endosperm, it was found that treatment with gibberellic acid induced the production of substantial quantities of peroxidase. The ease of measurement of peroxidase activity led us to investigate the sensitivity of production of this enzyme to added gibbe rellic acid, with a view to using the response as a bioassay for gibberellins. Barley seeds, var. Beorna were dehusked in 50% sulphuric acid, halved, and the endosperm halves hydrated at 5° C for 20 hours. Twenty half seeds were set up in a crystallising basin containing 5 ml of test solution. Smaller seed numbers and volumes of test solution may be used without any decrease in sensitivity. The seed halves in test solution were incubated at 30° C for 24 hours, after wich the ambient medium was collected and the seeds discarded or retained if needed for electrophoretic studies. The peroxidase activity of the medium was then assayed by the O-dianisidine method (Maehly and Chance, 1954). All operations were carried out under sterile conditions.
TL;DR: In this paper, the mass spectra of aegicerin acetate (XI), cyclamigenin B (VIII), and the methyl ester acetate X are discussed.
TL;DR: In this article, the authors present a brief synopsis of the early life of the winner in the Canterbury-York dispute, and a brief account of the loser's early introduction to the dispute and his eventual part in it.
Abstract: The immediate purpose of this article is narrative, in particular its aim is to draw attention to two little-known incidents in the early life of William of Corbeil, archbishop of Canterbury (1123–36) and to a rearrangement of the chronology of the Canterbury-York dispute in the 1120s, and, in general, to tell part of the story of that dispute again. The story is worth telling because it is colourful and dramatic and crowded with incident, because it is almost all that we know of a remote and thinly-documented period of English Church history, and because it marks an entirely new interest in English affairs on the part of the popes, who took part in the dispute with an energy and effect unparallelled since the seventh century. Despite (or perhaps because of) the excellence of the sources—Eadmer, monk of Canterbury, and Hugh, precentor of York—the story has only once been told at all fully for its most important period, that from 14 August 1114 to 9 December 1128—by Mr. Nicholl, in his recently published ‘Life’ of Thurstan, archbishop of York (1114–40). Naturally, he concentrated on Thurstan, the greater man of the two, the man with the better case, the victor in the dispute, of whom much more is known. This article is intended to give a brief synopsis of the early life of the loser, to tell of his early introduction to the dispute and his eventual part in it.
TL;DR: It is proposed that demodicosis is capable of eradication in pedigree dogs as well as in vitro and in vivo.
Abstract: — A brief review of the literature on various aspects of demodicosis in dogs is followed by a suggested pathogenesis. Some of the effects of Demodex on hosts other than dogs are then mentioned. Reasons why Demodex canis is easily destroyed in vitro but not in vivo are put forward. Finally it is proposed that demodicosis is capable of eradication in pedigree dogs.
TL;DR: Adenosine diphosphoglucose has been identified as the major component of nucleotide extracts of potato starch grains and it is suggested that, as in the case of the leaf-starch enzyme, it is the in vivo substrate for the glucosyltransferase of reserve starch synthesis.
TL;DR: Protection from monoamine oxidase increases; N‐substitution decreases; and hydroxyl groups at the β‐carbon and ring positions 3 and 4 increase the capabilities of a sympathomimetic amine to restore the chronotropic response to tyramine are concluded.
Abstract: 1. The restoration by various sympathomimetic amines of the chronotropic response to tyramine was studied on the isolated atria of rats pretreated with reserpine. The atria were exposed to the “restorative” sympathomimetic amine for 10 min, washed over a period of 1 hr and then tested with 10 μM tyramine. The effect of noradrenaline, dopamine and norphenylephrine before and after inhibition of monoamine oxidase by 0.5 mM iproniazid were compared with their α-methyl and N-alkyl analogues in their ability to restore the chronotropic response to tyramine.
2. Noradrenaline and adrenaline restored the chronotropic response to tyramine, the degree of restoration depending on the concentration of the restorative amine used. Noradrenaline after iproniazid and α-methylnoradrenaline were equipotent and were about 1,000 times more active than noradrenaline where monoamine oxidase was not inhibited. Dopamine, epinine, norphenylephrine, phenylephrine, octopamine, synephrine and isoprenaline in the absence of monoamine oxidase inhibition had no effect. Dopamine after iproniazid and α-methyldopamine were equipotent and were about 1/10 as active as α-methylnoradrenaline. Norphenylephrine after iproniazid and metaraminol were equipotent and were about 1/500 as active as α-methylnoradrenaline. Octopamine after iproniazid was even less active. The N-methylated analogues were about 1/10 as active as their nor-compounds but the N-isopropyl analogue, isoprenaline, was devoid of activity.
3. Dopamine after iproniazid and α-methyldopamine were inactive if a dopamine-β-hydroxylase inhibitor, disulphiram or sodium diethyldithiocarbamate, was present.
4. It is concluded that, in atria of reserpinized rats, (a) protection from monoamine oxidase increases; (b) N-substitution decreases; and (c) hydroxyl groups at the β-carbon and ring positions 3 and 4 increase the capabilities of a sympathomimetic amine to restore the chronotropic response to tyramine.
TL;DR: The difficulties of accounting for the powerful emission of energy from quasars can be resolved if the emission is assumed to be concentrated in one direction as mentioned in this paper, which is not the case here.
Abstract: The difficulties of accounting for the powerful emission of energy from quasars can be resolved if the emission is assumed to be concentrated in one direction.