Showing papers by "University of London published in 1982"
TL;DR: It is reported that, in addition to a spatial discrimination impairment, total hippocampal lesions also cause a profound and lasting placenavigational impairment that can be dissociated from correlated motor, motivational and reinforcement aspects of the procedure.
Abstract: Electrophysiological studies have shown that single cells in the hippocampus respond during spatial learning and exploration1–4, some firing only when animals enter specific and restricted areas of a familiar environment. Deficits in spatial learning and memory are found after lesions of the hippocampus and its extrinsic fibre connections5,6 following damage to the medial septal nucleus which successfully disrupts the hippocampal theta rhythm7, and in senescent rats which also show a correlated reduction in synaptic enhancement on the perforant path input to the hippocampus8. We now report, using a novel behavioural procedure requiring search for a hidden goal, that, in addition to a spatial discrimination impairment, total hippocampal lesions also cause a profound and lasting placenavigational impairment that can be dissociated from correlated motor, motivational and reinforcement aspects of the procedure.
6,143 citations
TL;DR: It is reported here that spontaneous firing of all the neurones recorded in the slice increased, consistent with the known effects of Ca2+ on membrane properties and synaptic transmission6–10, but the synchronous ‘field bursts’, and presumably their underlying mechanisms, were restricted to the population of pyramidal neurones in the hippocampal CA1 region.
Abstract: The synchronization of neuronal firing, seen at its most dramatic in the epilepsies, has generally been attributed to synaptic interactions1–5. We have now discovered a rhythmic spontaneous bursting activity produced by non-synaptic mechanisms. It develops in rat hippocampal slices after chemical synaptic transmission has been blocked by incubation in low Ca2+, increased Mg2+ solutions, and persists with almost clockwork regularity for several hours. We report here that spontaneous firing of all the neurones recorded in the slice increased, consistent with the known effects of Ca2+ on membrane properties and synaptic transmission6–10, but the synchronous ‘field bursts’, and presumably their underlying mechanisms, were restricted to the population of pyramidal neurones in the hippocampal CA1 region. Thus, these low Ca2+ field bursts are different from the Ca2+-dependent synchronous bursts induced in slices by penicillin which originate in the population of pyramidal cells of the CA3 region1–3.
453 citations
TL;DR: The marked increase in whole-body synthesis on feeding largely reflects the changes in protein synthesis in muscle, which doubles on feeding, compared with a 40% increase in that of the rest of the body.
Abstract: 1. Measurements have been made of whole-body and skeletal muscle protein synthesis in fed and fasted adults with L-[1-13C]leucine. 2. The marked increase in whole-body synthesis on feeding largely reflects the changes in protein synthesis in muscle, which doubles on feeding, compared with a 40% increase in that of the rest of the body. 3. Skeletal muscle in fed man contributes more than half to total protein synthesis occurring in the whole body.
448 citations
TL;DR: In this article, a reparameterization of a model introduced by D. G. Clayton for association in bivariate life-tables is discussed and an alternative non-parametric estimator based on Kendall's coefficient of concordance is proposed and its asymptotic variance evaluated.
Abstract: SUMMARY A reparameterization of a model introduced by D. G. Clayton for association in bivariate life-tables is discussed. Inference for the parameter governing the association is con- sidered when the marginal distributions are specified up to Lehmann alternatives. The information matrix is derived explicitly and it is shown that the parameterization is moderately successful in introducing orthogonality between the association parameter and the two scale parameters. The likelihood proposed by Clayton for the case that the marginal distributions are completely unknown is criticized. An alternative non- parametric estimator based on Kendall's coefficient of concordance is proposed and its asymptotic variance evaluated. IF G(s) = Pr(S>s) and H(t) = Pr(T>t) are continuous univariate survivor functions with G(O) = H(O) = 1 and 0 > 1, then the function F(s, t) = Pr (S > s, T > t) given by F(s, t) = {G )} +{H()} -1) (1) is a bivariate survivor function with G and H as marginals. This paper considers inference about the parameter 0 governing the association between S and T, given a sample of size n from their bivariate distribution. We suppose first that the marginals G(s) and H(t) are known up to Lehmann alternatives, and secondly that they are completely unknown. The model (1) is a reparameterization of a model introduced by Clayton (1978) for association in bivariate life-tables. Section 2 describes some properties of the family, including the limits as 0 -+1 and 0 > oo, a simple interpretation of 0 in terms of hazard functions and a random-effects derivation of the model. This section leans heavily on Clayton's work. Section 3 discusses parametric inference for 0, including tests of the hypothesis 0 = 1 of independence between S and T. We assume that the marginal survivor functions G(s) and H(t) are specified up to Lehmann alternatives. Asymptotic variance formulae are derived in Section 4, which also explores the extent to which the parameterization achieves orthogonality. Clayton (1978) proposed an ingenious method for estimating 0 in the absence of knowledge of the marginal distributions. Unfortunately there are difficulties with his proposed con- ditional likelihood function; in particular the estimated variance from the second derivative appears to be incorrect. Clayton's derivation is described and criticized in our Section 5. In principle, rank invariance properties of (1) when G(s) and H(t) are completely unknown yield a marginal likelihood for 0. Although this likelihood appears to be intractable in general, in Section 6 it is evaluated when n = 3 and shown to differ from Clayton's likelihood. A simpler non-parametric estimator of 0, based on the coefficient of concordance, is proposed in Section
444 citations
TL;DR: It is deduced that in bullfrog sympathetic neurones IC is a fast current which can contribute a substantial fraction to the repolarizing current during an action potential, and is highly sensitive to external tetraethylammonium.
Abstract: Many neurones, when depolarized, exhibit two components of outward K+ current—the voltage-sensitive delayed rectifier current originally described in squid axons by Hodgkin and Huxley1, and an additional current triggered by the entry of Ca2+ ions2. These two currents have been termed IK and IC, respectively3. Previous experiments have indicated that both forms of K+ current are also present in vertebrate sympathetic neurones4–6. We have now studied the properties of IC in bullfrog sympathetic neurones, uncontaminated with IK, by injecting Ca2+ ions into the cells and measuring the resultant outward currents under voltage-clamp, in the manner previously used for large molluscan neurones7,8. We find three interesting properties of IC in these vertebrate neurones. First, it shows strong voltage sensitivity independent of the voltage sensitivity of the Ca2+ channels (which have been bypassed by the injection technique). Second, IC activates and deactivates very rapidly (τC≤20 ms at 0 mV), with stepped changes in membrane potential. Current fluctuation analysis and patch-clamp records of single-channel currents yielded evidence for appropriate short-lifetime ionic channels with a maximum conductance of ∼100 pS. Finally IC in ganglion cells is highly sensitive to external tetraethylammonium. We deduce that in these neurones IC is a fast current which can contribute a substantial fraction to the repolarizing current during an action potential.
408 citations
TL;DR: In this paper, the 1939 populations of Shipham, a village in Somerset with high soil-cadmium levels, and a nearby control village have been followed for 40 years, and the mortality rates were compared with those for England and Wales.
398 citations
TL;DR: Examination of the weekly measles notifications for England and Wales, 1950-1979, reveals a regular biennial pattern of major and minor epidemics before the national immunization programme began in 1968, followed by an annual cycle ofMinor epidemics, suggesting that the national measles vaccination programme has not lowered the total number of individuals susceptible to measles.
Abstract: Examination of the weekly measles notifications for England and Wales, 1950-1979, reveals a regular biennial pattern of major and minor epidemics before the national immunization programme began in 1968, followed by an annual cycle of minor epidemics. Each year the reported incidence reaches its annual low between weeks 36 and 39, very close to the opening of primary schools. Analysis of these data with a simple mass action model reveals that the underlying transmission parameter has had a similar annual pattern in years of major and minor epidemics. The transmission parameter rises three times each year, coinciding with opening of school terms, and falls with school term and mid-term holidays. This pattern of the transmission parameter has been maintained in the decade since national vaccination began, indicating that the importance of schools in the annual dynamics of measles has not changed. The analysis further suggests that the national measles vaccination programme has not lowered the total number of individuals susceptible to measles in England and Wales.
393 citations
TL;DR: Japanese now have trunk/leg proportions much more similar to those of North Europeans than was the case 20 years ago, but their adult height remains about one standard deviation lower.
Abstract: The secular trends in height, sitting height and leg length in Japanese children have been studied by fitting Preece-Baines Model I curves to the annual mean values from ages five to 17 of school data collected in 1957, 1967 and 1977. The method provides estimates of final adult value, and of age of maximum annual increment. Between 1957 and 1977 the maximal increments in height, sitting height and leg length all became earlier, by about a year in boys and a little less in girls. Japanese now mature about a year earlier than North Europeans. Adult height increased by 4.3 cm in boys and 2.7 cm in girls between 1957 and 1977, the increment being less in the second decade than in the first. Sitting height showed practically no increase whatever; almost the whole secular trend was due to change in leg length. Japanese now have trunk/leg proportions much more similar to those of North Europeans than was the case 20 years ago, but their adult height remains about one standard deviation lower.
380 citations
TL;DR: A microscope system based on the principles of computerized axial tomography is described for determining the distribution of the X‐ray absorption coefficient in a slice from a solid object without cutting sections.
Abstract: SUMMARY
A microscope system based on the principles of computerized axial tomography is described for determining the distribution of the X-ray absorption coefficient in a slice from a solid object without cutting sections. An application is given to determining the distribution at a resolution of about 15 μm through a shell of about 0·5 mm diameter.
345 citations
TL;DR: In this article, a collaboration between teachers and parents was organized so that every child in two randomly chosen top infant classes at two schools (one class at each school), randomly allocated from six multiracial inner-city schools, was regularly heard reading at home from books sent by the class teacher.
Abstract: Summary. A collaboration between teachers and parents was organised so that every child in two randomly chosen top infant classes at two schools (one class at each school), randomly allocated from six multiracial inner-city schools, was regularly heard reading at home from books sent by the class teacher. The intervention was continued for two years, i.e., until the end of the first year in the junior school. Comparison was made with the parallel classes at the same schools, and with randomly chosen classes at two schools, again randomly allocated, where children were given extra reading tuition in school. This report presents cross-sectional analyses which show a highly significant improvement by children who received extra practice at home in comparison with control groups, but no comparable improvement by children who received extra help at school. The gains were made consistently by children of all ability levels.
330 citations
TL;DR: The levels of prostacyclin in the plasma of 20 healthy volunteers determined by this assay were much lower than any previously reported and confirms that prostacy Clin is not a circulating hormone in man under normal physiological conditions.
TL;DR: C‐reactive protein levels corresponded closely with clinical and pathological indices of relapse, remission and response to therapy in patients with Crohn's disease and provides an objective criterion of inflammatory activity, which may be useful in the assessment, management and study of Crohns disease.
Abstract: Prospective measurements were made of serum C-reactive protein levels and erythrocyte sedimentation rate in sixty-four patients with Crohn's disease and fifty with ulcerative colitis. The results were related to clinical assessment of disease activity. C-reactive protein levels were raised in both groups but were significantly higher in Crohn's disease than ulcerative colitis for all categories of disease severity: with mild disease the median and range of C-reactive protein concentration were 4, 0-65 mg/l in Crohn's disease v. 0, 0-15 mg/l in ulcerative colitis, P less than 0.01; in moderate disease the values were 15, 1-100 mg/l v. 3, 0-29 mg/l respectively, P less than 0.05 and in cases of severe disease, 85, 15-183 mg/l v. 12, 2-33 mg/l respectively, P less than 0.001. Erythrocyte sedimentation rate was also higher in Crohn's disease but did not closely reflect disease activity in individual patients. C-reactive protein levels corresponded closely with clinical and pathological indices of relapse, remission and response to therapy in patients with Crohn's disease. The precise assay of serum C-reactive protein provides an objective criterion of inflammatory activity, which may be useful in the assessment, management and study of Crohn's disease.
TL;DR: Two benzodiazepine antagonists were tested in an animal model of anxiety, the social interaction test and the implications for the understanding of the pharmacological basis of anxiety and for the existence and nature of an endogenous ligand for the benzodiazine binding site are discussed.
TL;DR: The identification for the first time of the weak oestrogen equol [7-hydroxy-3-(4'-hydroxyphenyl)chroman] in human urine is described and preliminary results of its quantitative excretion in urine are reported.
Abstract: The identification (by gas chromatography–mass spectrometry and n.m.r.) for the first time of the weak oestrogen equol [7-hydroxy-3-(4′-hydroxyphenyl)chroman] in human urine is described. Preliminary results of its quantitative excretion in urine are reported and the potential significance of the occurrence of this compound is discussed.
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TL;DR: The class S(λ;) is strictly smaller than the class of F for which the distribution function ∫x0eλλdF(y)∫∞ 0 eλλDF(Y)<∞ as discussed by the authors.
TL;DR: There is a large literature on the topic of sport and personality, much of which is, unfortunately, of an unacceptably low scientific standard as discussed by the authors. Many of the results reported are contradictory and difficult to interpret, particularly because of the small sample sizes often involved.
TL;DR: Synovial fluid from rheumatoid patients and normal cerebrospinal fluid contains micromolar concentrations of non-protein-bound iron salts that can promote lipid peroxidation and also the superoxide-dependent formation of hydroxyl radicals from hydrogen peroxide.
Abstract: Synovial fluid from rheumatoid patients and normal cerebrospinal fluid contains micromolar concentrations of non-protein-bound iron salts that can promote lipid peroxidation and also the superoxide-dependent formation of hydroxyl radicals from hydrogen peroxide. These iron catalysts of oxygen radical reactions cannot be detected by conventional assays unless interfering high-molecular-weight substances, probably proteins, are removed by ultrafiltration or inactivated by exposure to low pH values. The bleomycin assay for `catalytic' iron [Gutteridge, Rowley & Halliwell (1981) Biochem. J. 199, 263–265] does not suffer from these artifacts.
TL;DR: In this paper, a series of laboratory tests were performed to measure the boundary shear stresses in a compound channel consisting of a main channel and associated shallow floodplains and four different floodplain roughnesses were used.
Abstract: A series of laboratory tests were performed to measure the boundary shear stresses in a compound channel consisting of a main channel and associated shallow floodplains. Four different floodplain roughnesses were used. From these results apparent shear stresses across three different assumed main channel/floodplain interface planes (vertical, horizontal and diagonal) were calculated. The data was used with data from previous studies to derive a statistical relationship between the apparent shear stress on the vertical interface and several easily calculated parameters of the channel geometry and hydraulic characteristics. The accuracies of different methods of discharge calculation were shown to be dependent upon the assumptions they make regarding the magnitude of the apparent shear stress on the particular interface chosen. An apparent shear stress ratio was proposed which was found to be a useful yardstick in selecting the best method of discharge calculation for particular channel and flow conditions. Generally it was found that at low floodplain depths using the horizontal or diagonal interfaces gave better discharge results than the vertical.
TL;DR: The occurrence of potential pathogens and the levels of contamination at individual sites, particularly in the kitchen, toilet and bathroom is described and the implications for hygiene practices in the home discussed.
Abstract: An investigation of the bacterial flora in over 200 homes is reported. The occurrence of potential pathogens and the levels of contamination at individual sites, particularly in the kitchen, toilet and bathroom is described and the implications for hygiene practices in the home discussed.
TL;DR: It has been suggested that the damaging effects of O;--generating systems are due to the O;-dependent formation of hydroxyl radicals, OH’, a reaction which also requires HzOz and traces of non-protein-bound iron salts [S-8].
TL;DR: There is definite evidence of engraftment, the enzyme activity of the recipient's leucocytes reaching heterozygote levels within 37 days of the BMT, and deterioration in the child's development seems to have been arrested.
Abstract: A one-year-old boy with type I H mucopoly saccharidosis (Hurler's disease) was given a bone-marrow transplant (BMT) from his mother in an attempt to replace the deficient enzyme, alpha-L-iduronidase (iduronidase). There is definite evidence of engraftment, the enzyme activity of the recipient's leucocytes reaching heterozygote levels within 37 days of the BMT. Graft-versus-host disease (GVHD) developed but was partially controlled by steroids. From 3-4 months after graft until the present (13 months after the graft) iduronidase activity has been present in the serum and the urine and there has been evidence of considerable degradation of glycosaminoglycans excreted in the urine. The hepatosplenomegaly has disappeared, corneal clouding has cleared, and deterioration in the child's development seems to have been arrested.
TL;DR: Exposure to fluorescent light at work was associated with a doubling of melanoma risk and could explain many of the paradoxical features of the epidemiology of melanomas.
TL;DR: Geological, diatom, pollen and archaeological studies, supported by 24 original radiocarbon dates, provide new evidence to illustrate the Holocene history of Lake Turkana, Kenya as discussed by the authors.
Abstract: Geological, diatom, pollen and archaeological studies, supported by 24 original radiocarbon dates, provide new evidence to illustrate the Holocene history of Lake Turkana, Kenya. High and intermediate lake levels are recorded between 10,000 and about 3,000 yr BP, with a general regression during the later Holocene. Archaeological finds document the transition from a fishing-based economy to pastoralism.
TL;DR: The Moine and Outer Isles Seismic Traverse (MOIST) as mentioned in this paper is a deep reflection profile shot at sea off the north coast of Scotland in 1981, where spectacular reflections are observed from the Moho and from thrust zones within the Caledonian fold belt and foreland.
Abstract: The Moine and Outer Isles Seismic Traverse (MOIST) is a deep crustal reflection profile shot at sea off the north coast of Scotland in 1981. Spectacular reflections are observed from the Moho and from thrust zones within the Caledonian fold belt and foreland. Deep reflection profiling of the continental crust of the United States under the direction of the COCORP group, has amply demonstrated the value of this technique when applied to suitable geological problems (see, for example, refs 1,2). A similar group, the British Institutes Reflection Profiling Syndicate (BIRPS), has now been set up in the UK to organize such projects. Funds are provided by the Natural Environment Research Council (NERC) through the core group based at Cambridge University. However, a preliminary experiment, of which MOIST is the result, was organized through the Institute of Geological Sciences (IGS).
TL;DR: Though overall pertussis incidence fell in England and Wales subsequent to the introduction of vaccination on a national scale in the 1950s, pertussi epidemics have continued to occur regularly every 3-4 years, surprising that the interepidemic period did not decrease after the 1974 fall in vaccine uptake.
TL;DR: In this article, an arrow-firing experiment using copies of English Mesolithic points slotted into arrowshafts and shot into an animal carcass is described, and the impact fractures on the experimental flint points are compared with breakages observed on several microliths from the Powell Mesolithic site at Hengistbury Head in Dorset.
Abstract: The first part of this paper describes arrow‐firing experiments using copies of English Mesolithic points slotted into arrowshafts and shot into an animal carcass. ‘Impact fractures’ on the experimental flint points are compared with breakages observed on several microliths from the Powell Mesolithic site at Hengistbury Head, in Dorset. In the second part, the authors examine artefact distribution patterns from the Mace/Campbell Upper Palaeolithic site at Hengistbury and compare them briefly with those from the Belgian site of Meer, also in sands. In addition, some recent flint‐scatter experiments in sands are described and their relevance to site formation processes discussed.
TL;DR: Conditions for the use of desferrioxamine as a probe for the role of iron salts in the formation of hydroxyl radicals in biochemical systems are discussed.
TL;DR: Re-examined both leishmania and salmonella resistance in larger numbers of these putative recombinant strains and in various hybrid and backcross generations, and results indicate that BXD-18 and BxD-20 retype as Lshs and B XD-29 as Itys, meaning there is no longer any discordance between Lsh and Ity typings for the RI strains.
Abstract: Ity, a gene controlling natural resistance to Salmonella typhimurium infection1,2, and Lsh, which controls innate resistance to Leishmania donovani infection3, are both located on chromosome 1 of the mouse4,5 and it has been suggested6 that they might be identical. O'Brien et al.7 examined salmonella resistance in recombinant inbred (RI) strains of mice, and observed discordant responses in three strains (BXD-18, BXD-20, BXD-29) from one progenitor strain combination (C57BL/6J × DBA/2J) when compared with the published Lsh typing5. On the basis of this and additional information on salmonella resistance in (C57BL/6J × BXD-18)F1 and [(C57BL/6J × DBA/2J) × BXD-29] backcross mice, it was concluded that Ity and Lsh are closely linked but distinct genetic loci. We have now re-examined both leishmania and salmonella resistance in larger numbers of these putative recombinant strains and in various hybrid and backcross generations, and our results indicate that BXD-18 and BXD-20 retype as Lshs and BXD-29 as Itys. Hence there is no longer any discordance between Lsh and Ity typings for the RI strains. The results do, however, suggest additional modifying genetic control of salmonella resistance in BXD strains involving at least two other genetic loci. There is therefore no clear evidence to demonstrate that Ity and Lsh are not the same genetic locus.