Showing papers by "University of Birmingham published in 1982"
TL;DR: In this paper, an alternative approach is presented, formally relating unknown ages of samples to known ages of standards, either by direct comparison of standard and sample track densities, or by repeated calibration of a glass against age standards.
440 citations
TL;DR: The results showed that a period of exposure to deoxyguanosine causes depletion of the lymphoid cells while the stromal elements continue to survive, with many of the cells showing an epithelial morphology and expression of I region products of the major histocompatibility complex (MHC).
Abstract: On the basis of reports that deoxyguanosine is selectively toxic for adult T lymphocytes, the usefulness of this compound in the production of lymphocyte-depleted embryonic thymus rudiments in an in vitro organ culture system was investigated. The results showed that a period of exposure to deoxyguanosine causes depletion of the lymphoid cells while the stromal elements continue to survive, with many of the cells showing an epithelial morphology and expression of I region products of the major histocompatibility complex (MHC). When associated with either fetal liver or another thymus fragment as a source of T cell precursors in transfilter experiments, these "empty" thymuses become recolonized, enabling the production of chimeric thymus with stromal and lymphoid cells of different haplotypes. In combination with functional assays, this system offers an entirely in vitro approach to questions relating to the repertoire potential of T cell precursors from different sources and the role of the thymus in tolerance and MHC restriction.
315 citations
TL;DR: In this paper, the authors used new data on net worth for 12,734 families and showed that there is evidence that wealth declines after retirement provided that they control for differences in permanent income and take account of sample selection bias.
Abstract: Empirical studies of the life cycle savings model have tended to rej ect the hypothesis of a "hump-shaped" pattern for the wealth-age profile. In this paper we show, using new data on net worth for 12,734 families, that there is evidence that wealth declines after retirement provided that we control for differences in permanent income and take account of sample selection bias. The estimated rates of decumulation are consistent with a life cycle model in which there is uncertainty about the date of death.
258 citations
TL;DR: At least parts of both the appetite for a food and the satisfaction from it can be learned from experience of the after-effects of the food’s starch contents, as well as the previously observed differentiation of meal sizes.
245 citations
TL;DR: Systolic blood pressure appears to be an important factor in the pathogenesis of LV hypertrophy, and in hypertensive patients changes in LV mass assessed by echocardiography correlate with changes in blood pressure.
217 citations
TL;DR: Though relatively few people work on these minor, but very active, lipids at present, recent observations should soon attract others into this field and ideas and strictures that might inform future work are collected.
208 citations
01 Jan 1982
203 citations
TL;DR: It is suggested that a direct inhibitory action of GnRH on primate reproductive function is unlikely, and the need for a re-evaluation of certain rodent models designed to investigate primate, and especially human, reproductive physiology is highlighted.
Abstract: The antifertility nature of the hypothalamic peptide gonadotropin releasing hormone (GnRH) and its synthetic agonist analogue (GnRH-A) has been repeatedly demonstrated in rodents, monkeys and humans (see ref. 1 for review). In all species studied, this action of GnRH was initially attributed to ‘desensitization’ of gonadal steroidogenesis due to loss of gonadotropin receptors in the testis and ovary, induced by high circulating levels of endogenous gonadotropins achieved following repeated administration of GnRH or GnRH-A2–5. Recently, an additional, direct inhibitory action of these peptides on ovarian granulosa6,7 and luteal8–10 and testicular Leydig11–13 cells has been defined. This direct inhibition of gonadal steroidogenesis is mediated through specific high-affinity GnRH receptors in the respective target tissues8,9,12,14. These receptors exhibit identical characteristics to GnRH receptors (GnRH-R) in rodent anterior pituitary tissue9,12,14,15. In the search for a naturally occurring ligand for gonadal GnRH-R, a biologically active ‘GnRH-like’ peptide has been isolated from rat ovary16 and testis17,18, and from monkey testis interstitial fluid18. These findings suggest the production in rodent gonads of a GnRH-like peptide which, following interaction with gonadal GnRH-R, serves as a local modulator of steroidogenesis, and hence of reproductive capacity. If a similar situation exists in humans, GnRH-R should be detectable also in the human testis and ovary. We report here that we have been unable to detect any binding of radiolabelled GnRH-A to human corpus luteum or testis, or to the monkey testis. In contrast, GnRH-R were detected in adult and fetal human anterior pituitary tissue. Thus, we suggest that a direct inhibitory action of GnRH on primate reproductive function is unlikely. Furthermore, this important species difference highlights the need for a re-evaluation of certain rodent models designed to investigate primate, and especially human, reproductive physiology.
191 citations
TL;DR: In this article, it was shown that the major and trace-element compositions of the Skye and Mull plateau lavas of N.W. Scotland are variably isotopically contaminated by the Archaean Lewisian continental crust.
Abstract: One of the major puzzles presented by the geochemistry of the Palaeocene plateau lavas of Skye and Mull (N.W. Scotland) is that, although a very strong case can be made that the magmas are variably isotopically contaminated by Archaean Lewisian continental crust, little evidence has been gleaned to date from their major- and trace-element compositions to illuminate this hypothetical process. The combined results of published Sr-, Nd- and Pb-isotope studies of these lavas allow the basalts and hawaiites to be divided into three broad groups: essentially uncontaminated; contaminated with granulite-facies Archaean crust; contaminated with amphibolite-facies Archaean crust. Members of each group show distinctive chondrite-normalised incompatible-element patterns. The processes which gave rise to isotopic contamination of these lavas also affected the abundances and ratios of Ba, Rb, Th, K, Sr and light REE in the magmas, whilst having negligible effects on their abundances and ratios of Nb, Ta, P, Zr, Hf, Ti, Y and middle-heavy REE. Because such a wide range of elements were affected by the contamination process, it is postulated that the contaminant was a silicate melt of one or more distinctive crustal rock types, rather than an aqueous or similar fluid causing selective elemental movements from wall rocks into the magmas. As previous experimental and isotopic studies have shown that the Skye and Mull basic magmas were not constrained by cotectic equilibria at the time when they interacted with sial, the compositions of the contaminated lavas have been modelled in terms of simple magma-crust mixtures. Very close approximations to both the abundances and ratios of incompatible elements in the two groups of contaminated basalts may be obtained by adding 15% to 20% of Lewisian leucogneisses to uncontaminated Palaeocene basalt. Nevertheless, major-element constraints suggest that the maximum amount of granitic contaminant which has been added to these magmas lies between 5% and 10%. These estimates may be reconciled by postulating that the contaminants were large-fraction cotectic partial melts of Lewisian leucogneisses, leaving plagioclase residua. A corollary of this hypothesis is that it is necessary to postulate that the “magma chambers” where the sialic contamination occurred were, in fact, dykes or (more probably) sills. The very large surface-to-volume ratios of such magmas bodies would permit the systematic stripping, by partial melting, of the most-easily-fusible leucogneisses and pegmatites from the Lewisian crust, whilst failing to melt its major rock types. A present-day analogue to this situation may be the extensive sill-like magma bodies detected by geophysical methods within the continental crust beneath the Rio Grande Rift, southwestern U.S.A.
171 citations
TL;DR: In anaesthetized rats the effect of two procedures was studied on antidromically identified sympathetic preganglionic neurones (SPN) in the second thoracic segment of the spinal cord: the application of iontophoresed oxytocin and vasopressin, and bipolar electrical stimulation of the paraventricular nucleus of the hypothalamus (PVN).
170 citations
TL;DR: Coleoptera, Diptera, Homoptera and Arachnida made up the greatest number of animals caught, with Lepidoptera larvae important beneath oak, with the significance of terrestrial invertebrates as food for salmonids discussed.
Abstract: SUMMARY. The input of terrestrial invertebrates from different tree canopies to a trout stream was determined for a 28-week period from April to October, 1980. Sycamore produced the greatest number of animals, followed by oak and alder. Ash was not significantly different from the controls. Coleoptera, Diptera, Homoptera and Arachnida made up the greatest number of animals caught, with Lepidoptera larvae important beneath oak. The input of biomass (g m-2 dry wt) was also greatest beneath sycamore (35.80), followed by oak (27.76), alder (20.39), ash (11.15) and control (9.92). The input of biomass was bimodal. The significance of terrestrial invertebrates as food for salmonids is discussed.
TL;DR: The functional morphology, nervous and hormonal control and coordination of the cardiovascular and ventilatory systems in decapodan crustaceans is reviewed and central and peripheral O 2 receptors may be involved in determining respiratory and cardiovascular responses to hypoxia.
Abstract: The functional morphology, nervous and hormonal control and coordination of the cardiovascular and ventilatory systems in decapodan crustaceans is reviewed Pacemaker function reflects the reliance of crustaceans on small numbers of large, multipolar neurones Respiratory gas exchange and transport may be limited by the potential diffusion barrier presented by chitin on the gills and by the relatively low O 2 capacity of the haemolymph, though this is compensated by the relatively high O 2 affinity of haemocyanin and the large volume of the haemocoel Haemolymph buffering capacity is attributable to haemocyanin and to bicarbonate, including an internal source of fixed base, possibly the exoskeleton The typical hypoxic response includes a bradycardia and hyperventilation resulting in a respiratory alkalosis and resultant increase in O 2 affinity of the haemocyanin Diffusive conductance may increase When O 2 transport is limiting there is a switch to anaerobiosis with normoxic recovery including repayment of an O 2 debt Some species are facultative air-breathers and compensate for a respiratory and metabolic acidosis when in air by elevation of buffer base Central and peripheral O 2 receptors may be involved in determining respiratory and cardiovascular responses to hypoxia and airbreathers may respond to changes in haemolymph pH Exercise induces a rapid increase in ventilation, diffusive conductance improves and O 2 consumption is elevated There is also a major anaerobic contribution causing a metabolic acidosis and recovery includes prolonged repayment of an O 2 debt
TL;DR: Direct observations have been made on the responses of individual vessels of the microcirculation of rat spinotrapezius muscle to stimulation of the sympathetic paravascular nerve fibres and to topically applied catecholamines.
Abstract: 1. Direct observations have been made on the responses of individual vessels of the microcirculation of rat spinotrapezius muscle to stimulation of the sympathetic paravascular nerve fibres and to topically applied catecholamines.2. All arteries and arterioles were constricted by sympathetic stimulation, the maximum response occurring at a stimulus frequency of 8-10 Hz. Primary and secondary arterioles (13-50 mum internal diameter) showed the greatest percentage change in diameter and remained constricted throughout the 1 min stimulation period whilst terminal arterioles (7-13 mum internal diameter) constricted initially but then returned towards their control diameter before the stimulus ceased.3. By contrast the venules and veins showed no response to sympathetic stimulation.4. In accord with these observations, fluorescence histochemical studies revealed a network of noradrenergic nerve fibres on all arterial vessels but showed no innervation of any venous vessels.5. Topically applied noradrenaline or adrenaline (10(-10)-10(-8) g/ml.) dilated the majority of arteries and arterioles while higher concentrations of either agent produced dose-dependent constrictor responses. In addition, many venules dilated in response to adrenaline (10(-9) g/ml.) while others constricted, but concentrations of either noradrenaline or adrenaline greater than 10(-8) g/ml. produced dose-dependent constriction of all venules and veins.6. The behaviour of the more proximal and more distal arterioles during sympathetic stimulation is in accord respectively with the changes in muscle vascular resistance and in capillary surface area recorded in previous studies during sympathetic stimulation.7. The observation that venous vessels are not influenced by sympathetic nerve fibres contrasts with the established view that venous vessels of skeletal muscle are strongly constricted during sympathetic stimulation. However, reappraisal of the evidence used to support this view indicates that such results may have been misinterpreted, while other available evidence supports the proposal that the present findings may be representative of skeletal muscle vasculature in general.
TL;DR: It is shown that chitin, an important component of most fungal cell walls, elicited lignification in wheat leaves when applied as a suspension to wounds as well as the soluble derivatives ethylene glycol, ch itin and chitosan.
Abstract: Chitin, an important component of most fungal cell walls, elicited lignification in wheat leaves when applied as a suspension to wounds. The soluble derivatives ethylene glycol, chitin and chitosan were also active, but glucosamine, N-acetylglucosamine and small chitin oligomers did not elicit the response. The fungal glucan pullulan lacked activity, but laminarin, an algal glucan, was a weak elicitor. The response could also be elicited by fungal cell wall preparations. The possible role of chitin and related wall polymers in inducing host-defence mechanisms in wheat is discussed.
TL;DR: The nature, function and origins of a mayor population of B cells in human and rat spleens which populate the marginal zones are discussed, comparing them with recirculating lymphocytes found in the follicles of all secondary lymphoid tissue.
TL;DR: Immunoglobulin isotype expression in isolated lymph node (LN), spleen and blood lymphocyte suspensions was assessed in rats and showed the cells of the marginal zones to be predominantly μ+δ−, while μ-δ+ B cells were mainly confined to the follicles in both spleens and LN.
Abstract: Immunoglobulin isotype expression in isolated lymph node (LN), spleen and blood lymphocyte suspensions was assessed in rats. The proportion of mu+ delta- B cells in spleen (34%) was approximately twice that in blood and LN. Immunohistological examination of spleens showed the cells of the marginal zones to be predominantly mu+ delta-. On the other hand, mu+ delta+ B cells were mainly confined to the follicles in both spleen and LN. These follicles had a minor mu+ delta- component. The migratory properties of B cells with these two phenotypes were assessed by depleting lymphocytes migrating through the white pulp of rat spleen. This was achieved by placing a 32P-impregnated beta-emitting polythene strip over one half of the spleen. Examination of the nonirradiated half of the spleen, LN and peripheral blood after 12 days irradiation showed selective loss of delta + B cells. The mu + delta- cells of the splenic marginal zone were numerically unaltered. There was also a substantial residual mu + delta- B cell presence in the small lymphocyte compartment of follicles of LN and spleen in depleted animals. In addition, the blood selectively retained a mu + delta- B cell component. This was not derived from the spleen, as mu + delta- blood B cell numbers were sustained even where both halves of the spleen were irradiated. It is concluded that: (a) the major static B cell component of spleen and LN is mu + delta-, (b) that most if not all delta + B cells repeatedly migrate through the spleen and (c) there is a blood-born mu + delta- component which is resistant to depletion by splenic irradiation.,
TL;DR: A Tektronix-31 programmable calculator interfaced to a Perkin Elmer differential scanning calorimeter, model 2, substantially improves the accuracy of measuring the time-dependent development of the degree of crystallinity (× 10) and hence improves the quality of the rate data as mentioned in this paper.
TL;DR: Double labelling studies established that enkephalin and serotonin co-exist within some neurons in NRM and NRP, and beta-Lipotropin-positive cell bodies were found principally within NRP and within the ventrolateral reticular formation in PGL and LRM.
TL;DR: Mortality from all other causes including breast cancer showed no significant difference from that expected in the general population and in man there was a deficit of circulatory system deaths particularly those with early onset ulcerative colitis treated by panproctocolectomy after 40 yr of age.
TL;DR: Infusion of doses of GnRH that induced GnRHR in the intact animals did not affect the GnRH-R, serum LH, or pituitary LH content measured 6 days after orchidectomy, however, the receptor-inducing dose of Gn RH-A dramatically reduced the acute GnRH/GnRH/A responses to castration.
Abstract: To determine whether pituitary gonadotroph desensitization is a consequence of loss of gonadotropin-releasing hormone (GnRH) receptors (GnRH-R), these were analyzed in pituitaries from animals continuously infused with native GnRH or a superagonist analog (GnRH-A). Continuous infusion, for 6 days, of low doses of GnRH (<3.4 μg/day) and GnRH-A (<340 ng/day) to intact male rats resulted in a 37% and 75% increase in GnRH-R, respectively. At the time of sacrifice, basal serum LH levels were either unchanged (GnRH) or doubled (GnRH-A), and plasma concentrations of GnRH and GnRH-A were less than 0.05 nM or undetectable. There was no change in pituitary LH content under these circumstances. Infusion of doses of GnRH that induced GnRHR in the intact animals did not affect the GnRH-R, serum LH, or pituitary LH content measured 6 days after orchidectomy. However, the receptor-inducing dose of GnRH-A (340 ng/day) dramatically reduced the acute GnRH-R, serum LH, and pituitary LH responses to castration. In intact rat...
TL;DR: It was found that increases in arm circumference and Hb levels were associated with significant productivity gains of about 4%, and weight loss during the latter part of the study resulted in no significant final weight change for males.
TL;DR: An investigation to identify the relation between torques at hip, knee and ankle, posture holding time, and perceived discomfort showed that discomfort levels in the body segment immediately superior to the joints studied were significantly related to torque at the joint.
Abstract: An investigation to identify the relation between torques at hip, knee and ankle, posture holding time, and perceived discomfort was carried out. Subjects held four different extents of straight-legged forward bend as long as they could whilst reporting perceived overall and body-part discomforts at regular intervals. The results indicated that changes in postures correlated significantly with changes in holding time and in discomfort. Averaged results showed that discomfort levels in the body segment immediately superior to the joints studied were significantly related to torque at the joint. The relation was strongest for the ankle joint, where the location of the muscles producing the resisting torque could be associated most clearly with the body segment concerned.
TL;DR: In this article, the location and shape of the steady interface in a coastal aquifer discharging fresh water to the sea is determined by the boundary integral method for an abrupt interface model.
TL;DR: In this article, the detection of X ray pulsations with a period of 69.2126 ms from A0538-66 was done from the Einstein Observatory, where a point source was located by the High Resolution Imager and a proportional counter registered a flux of 40 counts/sec over background.
Abstract: The detection of X ray pulsations with a period of 69.2126 ms from A0538-66 was done from the Einstein Observatory. A point source was located by the High Resolution Imager and a proportional counter registered a flux of 40 counts/sec over background. A column spectral density of 2 x 10 to the 23/sq cm identified the object as A0538-66. A persistent periodicity of 0.0692126 sec was observed throughout the event. The outbursts were not detected on three other observations of A0538-66, and a best fit to a change of rotation velocity indicated that the period observed was from a binary star with a Doppler shifted signal. The two stars are separated by less than 39 solar radii, with the larger star having a 40 solar radius. Consideration is given to the possibility that the X rays are due to accretion on a neutron star and that the two stars at times share a common envelope.
TL;DR: Axonal sprouts, first seen 14-16 h post-lesion (pl), continued growing until at least 100 days pl, well beyond the time at which regeneration fails in myelinated CNS regions.
TL;DR: In this paper, a Monte Carlo model was proposed to predict the aspect ratio distribution of boudin segments formed by extension fracture in deformed rocks, based on the assumption that the tensile stress in a layer segment rises from a minimum at the end to a maximum at the centre.
TL;DR: Fission track dating of zircons and apatites from tuffs and bentonites has produced the first isotopic ages for the type sections of the Ordovician and Silurian Systems as mentioned in this paper.
Abstract: Fission-track dating of zircons and apatites from tuffs and bentonites has produced the first isotopic ages for the type sections of the Ordovician and Silurian Systems. In the Ordovician the following ages have been determined: lower Arenig 493 Ma, lower Llanvirn 487 Ma, lower Llandeilo 477 Ma, upper Caradoc 463 Ma and upper Ashgill 434 Ma. In the Silurian, the following: lower Llandovery 437 Ma, lower Wenlock 422 Ma, upper Wenlock 414 Ma and Ludlow 407 Ma. The Ordovician-Silurian boundary is interpreted as occurring at about 436 Ma. Three North American Rocklandian bentonites yielded zircons whose ages average 453 Ma. This is about 10 Ma younger than supposedly correlative units in the British type sections.
TL;DR: In this article, the hard X-ray spectrometer aboard the SMM imaged an extensive arch above the flare region which was found to be the lowest part of a stationary post-flare noise storm recorded at the same time at Culgoora.
Abstract: More than six hours after the two-ribbon flare of May 21, 1980, the hard X-ray spectrometer aboard the SMM imaged an extensive arch above the flare region which was found to be the lowest part of a stationary post-flare noise storm recorded at the same time at Culgoora. The bent crystal spectrometer aboard the SMM confirms that the arch emission was basically thermal. Variations in brightness and energy spectrum at one of the supposed footpoints of the arch are seen as correlation in time with radio brightness, suggesting that suprathermal particles from the radio noise regions dumped in variable quantities onto the low corona and transition layer.