Showing papers by "Medical Research Council published in 1968"
TL;DR: The brain scans from 50 cases of proven dementia in old age were examined and various features objectively assessed, and compared with similar features in a group of non-demented (controls) old people.
1,853 citations
TL;DR: This report is based on an analysis of 52,004 legitimate, single births which took place in the City of Aberdeen during the years 1948--64, and is of exceptional value for the following reasons.
680 citations
TL;DR: A simple reasoning test involving the understanding of sentences of various levels of syntactic complexity is described, which correlates with intelligence and has proved to be sensitive to a number of stresses.
Abstract: A simple reasoning test involving the understanding of sentences of various levels of syntactic complexity is described. It is short, easily administered, and reliable. Performance correlates with intelligence (+.59) and has proved to be sensitive to a number of stresses.
628 citations
TL;DR: Increased difficulty of recognition of speech through noise may interfere with other activities, (conveniently termed “rehearsal”) which may be necessary to efficiently retain data in memory.
Abstract: When subjects try to remember lists of digits played to them through pulse-modulated white noise the number of errors they make is greater than would be expected if digitrecognition errors and imme...
412 citations
TL;DR: The results are discussed in connexion with the organ distribution of tumours induced by the compounds under study and in relation to the possible importance of alkylation of cellular components for the induction of cancer.
Abstract: 1. N[(14)C]-Methyl-N-nitrosourea, [(14)C]dimethylnitrosamine, [(14)C]dimethyl sulphate and [(14)C]methyl methanesulphonate were injected into rats, and nucleic acids were isolated from several organs after various time-intervals. Radioactivity was detected in DNA and RNA, partly in major base components and partly as the methylated base, 7-methylguanine. 2. No 7-methylguanine was detected in liver DNA from normal untreated rats. 3. The specific radioactivity of 7-methylguanine isolated from DNA prepared from rats treated with [(14)C]dimethylnitrosamine was virtually the same as that of the dimethylnitrosamine injected. 4. The degree of methylation of RNA and DNA produced in various organs by each compound was determined, and expressed as a percentage of guanine residues converted into 7-methylguanine. With dimethylnitrosamine both nucleic acids were considerably more highly methylated in the liver (RNA, about 1% of guanine residues methylated; DNA, about 0.6% of guanine residues methylated) than in the other organs. Kidney nucleic acids were methylated to about one-tenth of the extent of those in the liver, lung showed slightly lower values and the other organs only very low values. N-Methyl-N-nitrosourea methylated nucleic acids to about the same extent in all the organs studied, the amount being about the same as that in the kidney after treatment with dimethylnitrosamine. In each case the RNA was more highly methylated than the DNA. Methyl methanesulphonate methylated the nucleic acids in several organs to about the same extent as N-methyl-N-nitrosourea, but the DNA was more highly methylated than the RNA. Dimethyl sulphate, even in toxic doses, gave considerably less methylation than N-methyl-N-nitrosourea in all the organs studied, the greatest methylation being in the brain. 5. The rate of removal of 7-methylguanine from DNA of kidneys from rats treated with dimethylnitrosamine was compared with the rate after treatment of rats with methyl methanesulphonate. No striking difference was found. 6. The results are discussed in connexion with the organ distribution of tumours induced by the compounds under study and in relation to the possible importance of alkylation of cellular components for the induction of cancer.
361 citations
TL;DR: 5-H.A.T., noradrenaline, and 5-hydroxyindoleacetic acid levels were not significantly different, but 5- H.I.A.'s levels was significantly lower in the hindbrains of the suicides.
299 citations
TL;DR: Clinical and chemical studies on a brother and sister with severe mental defect showed that both excreted abnormal amounts of 2-acetamido-1-(β'-L-aspartamido)-1, 2-dideoxyglucose, but the enzyme responsible for hydrolysing this compound was apparently absent from that of the brother.
252 citations
TL;DR: Evidence is presented that the tumour was producing insulin, gastrin and glucagon, and that production of these hormones was diminished following treatment with the drug streptozotocin.
228 citations
TL;DR: All three experiments show a parallel rate of forgetting for acoustically similar and control sequences, suggesting that the acoustic similarity effect does not occur during storage and is due to the overloading of retrieval cues.
Abstract: This study attempts to discover why items which are similar in sound are hard to recall in a short-term memory situation. The input, storage, and retrieval stages of the memory system are examined ...
217 citations
TL;DR: Primary gonadal failure may be part of a polyendocrinopathy of which idiopathic Addison's disease is an integral part and which is characterised by the formation of autoantibodies to the respective tissues.
202 citations
TL;DR: The procedure is rapid and more sensitive than established procedures; an accurate assay can be performed on a single tissue sample containing 20 ng of noradrenaline, 30 ng of serotonin, and 100 ng of dopamine.
TL;DR: The implication that subjects can correct errors because they know what response they should have made allows some comments on the constraints which must be met by various models which have been proposed to explain error-correction.
Abstract: During serial self-paced choice response tasks mean reaction times (RTs) for responses which are made in order to correct errors are faster than mean RTs for other correct responses. Experiment I showed that subjects can accurately correct errors in a four-choice task by making the response which they should have made, even though they are given no indication that an error has occurred. Experiment 2 showed that subjects correct their errors faster and more accurately when they use correction procedure than when they make a common response to all errors. The implication that subjects can correct errors because they know what response they should have made allows some comments on the constraints which must be met by various models which have been proposed to explain error-correction. Now at Institute of Experimental Psychology, University of Oxford.
TL;DR: In this article, the concentrations of conjugated bile salts in the upper jejunal fluid of six fasting patients with steatorrhoea due to the stagnant-loop syndrome were reduced, all being under 5 mmoles per litre.
TL;DR: It is suggested that the contractile apparatus of muscle behaves as a colloid in which the separation of the filaments is determined by the balance of electrostatic double-layer repulsive forces and van der Waals' attractive forces.
TL;DR: It was concluded that body-temperature was as effective a predictor of overall mental efficiency in most industrial-tournament performance trends as sleep deprivation.
Abstract: Thirty-one subjects were employed in an experiment to determine whether the relationship between efficiency at mental tasks and the circadian rhythm of body temperature observed in an earlier study was affected by an increase in the length of the duty-spell from 4 to 8 hours. Subjects wore assigned either to a control ‘ day ’ shift (O800–1600), a ‘ night ’ shift (2200–0600) or a ( morning ) shift (0400–1200), and were tested for a period of 12 consecutive days on the same shift. The control shift-workers showed no consistent effects of fatigue due to the increased length of the duty-spell. Adaptation of temperature rhythm to work on the night shift was only partial, but was relatively closely reflected in the recorded performance trends. Very little adaptation to work on the morning shift was observed, and performance was thought to have been affected by partial sleep deprivation. It was concluded that body-temperature was as effective a predictor of overall mental efficiency in most industrial-t...
TL;DR: Several of the disease states in which red‐cell fragments appear in the peripheral blood have features suggestive of intravascular coagulation with fibrin deposition in vessels, and the interaction of rapidly moving red cells withfibrin strands was investigated.
Abstract: Summary. Several of the disease states in which red-cell fragments appear in the peripheral blood have features suggestive of intravascular coagulation with fibrin deposition in vessels. As this process might be a cause of red-cell fragmentation the interaction of rapidly moving red cells with fibrin strands was investigated.
Red cells arrested on fibrin strands while moving through a loose fibrin clot at the velocity of arterial blood flow were bent over the strands by the force of blood flow and eventually fragmented. The shape of the fragments which resulted depended upon the position and plane in which the red cells were arrested, the point at which the membrane ruptured, the distribution of haemoglobin and membrane between the resulting fragments and finally on whether or not crenation of the fragments supervened.
Systems in which red cells perfused artificial ‘clots’ of glass fibre and nylon also caused the red cells to fragment. The fragmentation process seems to depend, therefore, on a rapid blood flow and the arrest of individual red cells by any obstruction of small dimensions, e. g. by strands or spikes less than I p in diameter. It was concluded that these conditions were most likely to obtain in vivo as the result of intravascular deposits of fibrin in the lumen of small arterioles.
TL;DR: Efficiency at ‘ mental ’ tasks was observed when performed according to a time schedule imposed by following one of two different 4-hour shift systems for a period of 12 consecutive days.
Abstract: Efficiency at ‘ mental ’ tasks was observed when performed according to a time schedule imposed by following one of two different 4-hour shift systems for a period of 12 consecutive days. Twenty-eight subjects were assigned either to a ‘ rotating ’ system, in which each 4-hour period of the 24 hours was worked once every 72 hours in a repeating cycle, or to a ‘ stabilized ’ system, in which the work periods were from 1230 to 1630 and 2400-0400 each day. In the rotating system, alterations in the level of several aspects of performance at different times of day were found to be related quite closely to concurrent fluctuations in body temperature arising from its natural circadian rhythm. A shift in the phase of this rhythm in response to the now sleep/waking cycle imposed by the stabilized system was accompanied by a corresponding change in the relative levels of performance observed in the two work periods. Thus in both systems body temperature was, in effect, a predictor of performance efficienc...
TL;DR: A suite des recommandations faites en 1964 par le Groupe de travail "amiante et cancer" de l'UICC and dont l'application avait ete examinee par un Comite special en 1965, des echantillons-etalons des cinq principaux types d'amiantes ont ete prepares par des chercheurs d'Afrique du Sud et du Royaume-Uni, avec l'aide des entreprises minieres interessees de
Abstract: ECHANTILLONS-TYPES D'AMIANTE DE L'UICC
A la suite des recommandations faites en 1964 par le Groupe de travail „amiante et cancer” de l'UICC et dont l'application avait ete examinee par un Comite special en 1965, des echantillons-etalons des cinq principaux types d'amiante ont ete prepares par des chercheurs d'Afrique du Sud et du Royaume-Uni, avec l'aide des entreprises minieres interessees de divers pays.
Plusieurs laboratoires en etudient actuellement les proprietes physiques et chimiques. Les echantillons (en sachets de plastique de 500 g ou moins) peuvent ětre obtenus sur demande a la Pneumoconiosis Research Unit, Johannesburg, Afrique de Sud, ou a la P. R. U. de Penarth, Royaume-Uni.
TL;DR: In this paper, a study was made of reproductive performance and embryonic mortality in XO and XX females, and it was concluded that there was probably an abnormally low segregation of nullo-X gametes from XO females.
Abstract: A study was made of reproductive performance and embryonic mortality in XO and XX females. In the stock used, the mean litter size of XO females (4·46) was greatly below that of XX ones (8·17). One series of pregnant females of both karyotypes was dissected after 15 days' gestation, and another series after 3½days' gestation. In the former, there was a significantly greater amount of embryonic mortality in XO females both before implantation and at the small and large mole stages. By far the greater amount occurred before implantation. The data from dissections after 3½ days' gestation concerned pre-implantation embryos, since normal embryos at this point are at the late morula or early blastocyst stage. The embryos from XO females contained a large group of obviously and characteristically abnormal ones; they comprised 60/280 of the embryos from XO females, compared with 4/189 of the XX ones. They appeared to have developed abnormally from a very early stage, probably the two-cell stage, and were considered to represent the missing OY class of zygotes. In addition, it was concluded that there was probably an abnormally low segregation of nullo-X gametes from XO females.
TL;DR: The exhalation of (14)CO(2) after an intragastric dose of N[(14)C]-methyl-N-nitrosourea (100mg./kg. body wt.) is appreciably slower than after an intravenous dose, from which it is estimated that the lifetime in the rat is 2-3hr.
Abstract: 1. The rates of decomposition of methyl methanesulphonate, dimethyl sulphate and N-methyl-N-nitrosourea in the rat were measured. 2. Dimethyl sulphate is no longer detectable in the blood of the rat 3min. after an intravenous dose (75mg./kg. body wt.). Methyl methanesulphonate is only just detectable in the blood 1(1/2)hr. after an intravenous dose (100mg./kg. body wt.). N-Methyl-N-nitrosourea is no longer detectable in the blood 15min. after an intravenous dose (100mg./kg. body wt.). 3. The exhalation of (14)CO(2) after an intragastric dose of N[(14)C]-methyl-N-nitrosourea (100mg./kg. body wt.) is appreciably slower than after an intravenous dose, from which it is estimated that the lifetime in the rat is 2-3hr.
TL;DR: Observations suggest that glycochenodeoxycholate or glycode oxygencholate would be the bile-salt of choice for replacement therapy.
TL;DR: An isoprenaline aerosol supplying 0·44 mg.
TL;DR: It appears that glucagon possesses no difined tertiary structure in solution, but may be regarded as being in a state of α-helix ⇌ random coik equilibrium, near the high-temperature end of the transition range.
Abstract: glucagon is a polypetide of 29 residues, which can be crystallised. Optical rotatory dispersion in dilute neutral, acid and alkaline solution suggests that the polypeptide chain is largely random, but contains about one turn of α-helix, which is eliminated in 6 M guanidine hydrochloride. Using thermal difference spectra, nuclear magnetic resonance, and the temperature-dependence of the optical retatory dispersion as criteria, it appears that glucagon possesses no difined tertiary structure in solution, but may be regarded as being in a state of α-helix ⇌ random coik equilibrium, near the high-temperature end of the transition range. That there is no steric objection to the formation of a highly α-helical conformation is demonstrated by optical rotatory dispersion measurements in 2-chloroethanol solution, in which the protein becomes largely helical. A rough calculation indicates that in aqueous solution at pH 2 the transition mid-point is at about –40%%. From changes in the proton magnetic resonance spectrum when glucagon is transferred from an aqueous environment into 6 M guanidine hydrochloride, it is deduced that the short helical segment in the chain in the aqueous state contains most of the long aliphatic side chains, and since the sequence is known it has been possible to identify such as segment uniquely near the C-terminal end. On standing in acid solution the vicosity increases and a birefringent gel is formed. Sedimentation studies indicate the formation of large aggregates. On further standingor warming, a precipitate appears which has the appearance of long fibrils in the electron microscope. Infrared spectra of the gel, of solid films and of the precipitated material show that in all these states the glucagon is in the form of antiparallel β-chains.
TL;DR: In patients with coeliac disease there was malabsorption of folic acid in the proximal jejunum but absorption in the distal je junum was comparable to that in controls, suggesting an active transport mechanism.
TL;DR: The effect of dose-rate on the induction of reciprocal translocations in mouse A type spematogonia by 600 RX- and γ-irradiation was studied by scoring multivalent configurations in descendant spermatocytes by finding that frequencies of 0, 1, 2 translocations per sperMatocyte did not fit a Poisson distribution.
Abstract: The effect of dose-rate on the induction of reciprocal translocations in mouse A type spematogonia by 600 RX- and γ-irradiation was studied by scoring multivalent configurations in descendant spermatocytes. With X-irradiation over a range of dose-rates from 0.8 to 913 R/min there was no significant change in the frequency of affected spermatocytes, which averaged 12.8%. With γ-irradiation, however, there was a steady increase in frequency from 1.4% at 0.02 R/min to 12.1% at 86 R/min, the points fitting a straight line on a semi-log plot. At 0.08 R/min the X-ray yield was twice that for γ-rays. Possible reasons for these differences are discussed. Frequencies of 0, 1, 2 translocations per spermatocyte did not fit a Poisson distribution since there were less then expected in the 1-class, but more in higher classes. This was probably a consequence of differential radiosensitivity of the irradiated spermatogonia, although preferential clonal proliferation may also be involved.
TL;DR: The characteristics of the generation cycle of the subependymal layer of the adult rat brain have been studied by the autoradiographic method and a mean generation time of 18 hr, with a DNA synthesis period of 8 I 2 hr, and a postsynthetic phase of 1 I 2 hrs was found for the cells of the layer.
TL;DR: Electron micrographs of sections through the heterochromatin of erythrocytes from chicken and lamprey reveal alternate equispaced electron-dense and relatively less dense bands lying adjacent and parallel to, and extending considerable distances along, the nuclear envelope, indicating that the heterchromatin contains a well-defined structural unit which can form ordered regions, namely layers in contact with thenuclear envelope.
Abstract: Electron micrographs of sections through the heterochromatin (condensed chromosomes) of erythrocytes from chicken and lamprey reveal alternate equispaced electron-dense and relatively less dense bands lying adjacent and parallel to, and extending considerable distances along, the nuclear envelope. Frequently a triple-structured band (average half-width 183 A), consisting of a less dense band, a dense band (width 130-170 A), and a second less dense band is encountered; sometimes there are many (10-12) bands. The dense bands have a variable structure; they may appear continuous or consist of equispaced granules about 220 A apart, which sometimes have a less dense centre. Similar but shorter dark bands and granules appear throughout the chromatin. Tilting the section in the microscope causes the micrographs to change, bands and granules disappearing and reappearing elsewhere, demonstrating that the images are produced by superposition of structures small in dimensions compared with the thickness of the section. Tilting about an axis normal to the band may resolve it into granules. These data indicate that the heterochromatin contains a well-defined structural unit which can form ordered regions, namely layers in contact with the nuclear envelope. The possibility of errors in interpreting the substructure of the bands due to complexity of superposition effects is stressed. The simplest hypothesis to account for the images is that the units are microtubes of outside diameter 130-170 A, perhaps microhelices formed by coiling DNA with protein, spaced apart equally, perhaps by spacing elements. Microtubes parallel to the optic axis would appear as hollow granules, several one above another in a plane parallel to the axis appearing as a dark band. A similar triple-structured band of average half-width 224 A is found in cells from newt spleen, lymphocytes, polychromatophil erythroblasts, mature erythrocytes, basophilic granulocytes, reticular cells and macrophages. A survey of published micrographs shows a similar triple-structured band of average half-width 212 A to be a common feature of many cell types. A triple-structured band probably gives rise to the sheets of chromatin, now shown to have a similar triple-layered structure, limited on both sides by nuclear envelope, previously found attached to interphase nuclei and mitotic chromosomes in certain polychromatic erythroblasts from the newt. The effects of tilting the section were studied on objects of known geometry, membranes and cytoplasmic microtubules.
TL;DR: It is shown that in principle a stable balance can be achieved between the attractive force and the repulsive force for hexagonally-packed, charged cylinders in the ionic solution.