Showing papers by "University of Hertfordshire published in 1989"
TL;DR: This article showed that almost all of the nitrate at risk to leaching over the winter period comes from mineralisation of organic N, not from unused fertiliser applied in spring, and that even a drastic reduction in N fertiliser use would have little effect on nitrate leaching.
Abstract: Nitrate present in arable soils in autumn is at risk to leaching during the following winter. To see whether unused nitrogen fertiliser was a major source of this nitrate, 15N-labelled fertiliser was applied to 11 winter wheat crops at rates of between 47 and 234 kg N ha−1in spring. The experiments were on three contrasting soil types in south-east England.
On average, 17′% of the N from spring-applied labelled fertiliser remained in the 0–23 cm soil layer at harvest (range, 7–36%) but only a small proportion was in inorganic forms (ammonium + nitrate). This was never more than 5 kg N ha−1and averaged only 1·3% of the fertiliser N applied (range, 0·4–3·6 %). Between 79 and 98% of the inorganic N in soils at harvest was unlabelled, being derived from the mineralisation of organic N rather than from unused fertiliser. The amount of unlabelled N was much greater where wheat was grown after ploughing up grass or grass/clover leys than where it was grown in all-arable rotations. When wheat was grown without N fertiliser, soil inorganic N content at harvest was no lower than in plots given fertiliser at rates up to 234 kg N ha−1.
This work indicates that, for soil growing winter wheat, almost all of the nitrate at risk to leaching over the winter period comes from mineralisation of organic N, not from unused fertiliser applied in spring. Consequently, even a drastic reduction in N fertiliser use would have little effect on nitrate leaching.
190 citations
TL;DR: The rapid and usually excitement-free recovery of the animals was a valuable feature of anaesthesia with propofol, and no clinical incompatibility was observed between prop ofol and any of the other agents administered during the study.
Abstract: The clinical efficacy and safety of an emulsion containing 10 mg/ml of the intravenous anaesthetic propofol were evaluated in cats and dogs by veterinary surgeons in eight practices in the United Kingdom A total of 290 dogs and 207 cats were anaesthetised with propofol either as a single injection for procedures of short duration, or as an induction agent with maintenance provided by further incremental injections or as an induction agent with maintenance by gaseous agents The mean induction doses of propofol for unpremedicated dogs and cats were respectively 655 mg/kg and 803 mg/kg The mean induction doses after premedication with a tranquilliser were 45 mg/kg and 597 mg/kg for dogs and cats, respectively Mean recovery times ranged, depending on the method of anaesthesia, from 23 to 40 minutes in dogs and from 27 to 38 minutes in cats; recovery was defined as the time at which the animals were alert and able to stand Adverse side effects were infrequent, apnoea during induction being the commonest Acepromazine and atropine were most often used as premedicants although in a few cases diazepam, xylazine and other agents were employed No clinical incompatibility was observed between propofol and any of the other agents administered during the study The rapid and usually excitement-free recovery of the animals was a valuable feature of anaesthesia with propofol
171 citations
Patent•
19 Jun 1989TL;DR: In this paper, a pad supporting a plurality of diamond-tip needles is used for port wine stain treatment. But the tip of each needle is supplied with laser radiation and the tip acts to scatter laser radiation sideways, which creates a laminar radiation profile located below and spaced from the skin surface.
Abstract: Port wine stain treatment apparatus includes a pad supporting a plurality of diamond tipped needles. The tip of each needle is supplied with laser radiation and the tip acts to scatter laser radiation sideways. Thus, when the pad is applied to the skin, the tips penetrate the skin and when laser radiation is supplied the tips create a laminar radiation profile located below and spaced from the skin surface. In this manner, the cause of the port wine stain can be treated without the danger of disfiguring or scarring the skin surface above the stain.
165 citations
TL;DR: The results suggest that the predominant contractile effect of 5- HT in human isolated large coronary arteries is mediated via 5-HT2 receptors but that, in addition,5-HT1-like receptors contribute to some degree to this response in vitro.
159 citations
TL;DR: The results demonstrate that GR43175 produces a selective vasoconstriction in the carotid arterial circulation of anaesthetized dogs via activation of 5‐HT1‐like receptors, which appear similar to those mediating contraction of the dog isolated saphenous vein.
Abstract: 1. GR43175 is a highly selective agonist at 5-HT1-like receptors in the dog saphenous vein. This study describes the haemodynamic effects of GR43175 in barbitone-anaesthetized dogs. 2. GR43175 (1-1000 micrograms kg-1, i.v.) produced dose-dependent decreases in carotid arterial blood flow with little or no change in arterial blood pressure. The decrease in blood flow was associated with an increase in carotid arterial vascular resistance. In preliminary studies, the dose of GR43175 producing 50% of the maximum carotid vasoconstrictor response was 39 +/- 8 micrograms kg-1, i.v. 3. In comparative regional haemodynamic studies, GR43175 (1-1000 micrograms kg-1, i.v.) had little effect on total peripheral resistance or resistance in the mesenteric, vertebral and coronary arterial vascular beds. Low doses of GR43175 decreased, whilst high doses (100 micrograms kg-1, i.v. and above) increased femoral arterial vascular resistance. GR43175 (1-1000 micrograms kg-1, i.v.) had no effect on respiratory inflation pressure. In doses of 100 micrograms kg-1 i.v. and above, GR43175 caused small decreases in heart rate. 4. The carotid arterial vasoconstrictor action of GR43175 was resistant to antagonism by the 5-HT2 receptor, 5-HT3 receptor and alpha-adrenoceptor blocking drugs, ketanserin, MDL72222 and phentolamine respectively, but could be antagonized by the non-selective 5-HT1-like receptor blocking drug methiothepin. Methiothepin had no effect on the carotid vasoconstrictor action of the thromboxane A2 mimetic, U46619. 5. The results demonstrate that GR43175 produces a selective vasoconstriction in the carotid arterial circulation of anaesthetized dogs via activation of 5-HT1-like receptors, which appear similar to those mediating contraction of the dog isolated saphenous vein.
155 citations
144 citations
TL;DR: Analysis of soil profile samples showed that approximately 1% of the metals applied had moved 3.5 cm below the plough layer or less, but there was no evidence of accumulation of metals in deeper horizons down to 46 cm, which is of great relevance to the long-term disposal of metal-contaminated wastes to land.
141 citations
TL;DR: This receptor can be characterized by the high potency of the novel, selective agonist, GR43175, and susceptibility to blockade by methiothepin, and there also appears to be a population of 5‐HT2 receptors in these pre‐pAarations which contribute to the contractile effects of5‐HT.
Abstract: 1. The aim of this study was to characterize the 5-hydroxytryptamine (5-HT) receptor which mediates contraction of canine and primate isolated basilar artery by use of a variety of selective 5-HT agonists and antagonists. 2. 5-HT, alpha-methyl 5-HT and the selective 5-HT1-like receptor agonists, GR43175 and 5-carboxamidotryptamine (5-CT), each caused contraction of canine and primate basilar artery with a rank order of agonist potency of 5-CT greater than or equal to 5-HT greater than GR43175 greater than alpha-methyl 5-HT. The 5-HT1-like receptor agonists, GR43175 and 5-CT, produced maximum effects which were less than that produced by 5-HT or alpha-methyl 5-HT. 3. In canine basilar artery, ketanserin (0.1-1 microM) caused some depression of the maximum effect of 5-HT but produced little or no shift of the concentration-effect curve. The contractile effects of GR43175 were not modified by ketanserin (1 microM), MDL72222 (1 microM) or cyanopindolol (1 microM). However, the effects of 5-HT and GR43175 were specifically antagonized by methiothepin (0.1 microM); the mean agonist concentration-ratios were 33 and 48 respectively. 4. In primate basilar artery, ketanserin (1 microM) again caused a small depression of the 5-HT maximum response but had not effect against GR43175-induced contractions. In contrast, methiothepin (0.1 microM) antagonized both 5-HT- and GR43175-induced contractions; the mean agonist concentration-ratios were 35 for both. 5. These results demonstrate that a large component of the effects of 5-HT in canine and primate basilar artery is produced by stimulation of a 5-HT1-like receptor. This receptor can be characterized by the high potency of the novel, selective agonist, GR43175, and susceptibility to blockade by methiothepin. However, there also appears to be a population of 5-HT2 receptors in these prepAarations which contribute to the contractile effects of 5-HT.
135 citations
TL;DR: It is concluded that atmospheric deposition from natural sources has been augmented in recent years by regional fallout of anthropogenically-generated PAHs derived from the combustion of fossil fuels.
134 citations
TL;DR: Its vasoconstrictor action can be shown to be localized even further to arteriovenous anastomoses (shunts) within the carotid circulation, in such a way that blood flow to the brain as well as to extracerebral capillary beds remains unaffected or may even be increased.
Abstract: We describe the identification of a novel drug, GR43175, for the acute treatment of migraine. GR43175 is a tryptamine analogue with a very selective agonist action at a 5-HT1-like receptor subtype first identified in the dog saphenous vein. Using this drug as a research probe, we have now shown that this 5-HT receptor type predominates in the carotid circulation, which explains the remarkably selective vasoconstrictor action of GR43175 in vivo in the carotid arterial bed of dogs and cats. Its vasoconstrictor action can be shown to be localized even further to arteriovenous anastomoses (shunts) within the carotid circulation, in such a way that blood flow to the brain as well as to extracerebral capillary beds remains unaffected or may even be increased. In the treatment of migraine demonstrated to date, the impressive effectiveness of GR43175 must reinforce the evidence in favour of an important vascular component being involved in the aetiology of the disease. The question is again raised as to whether the opening of carotid shunts is involved, as suggested by Heyck. If not, an alternative vascular locus needs to be identified.
126 citations
TL;DR: Control of winter epidemics of S. tritici had little effect on yield, whereas spray sequences commencing later than growth stage (GS) 31 but immediately prior to the critical periods provided the best disease control and yield benefit.
Abstract: Severe infection with Septoria tritici occurred in four of five experiments designed to create a series of different disease epidemics. These experiments successfully identified periods suitable for infection. They also indicated the effect of sprays, timed before and after these periods, on disease development and yield.
Analysis of disease progress and weather records suggested that critical conditions for initial development of S. tritici occurred during early May at four sites. Heavy rain giving at least 10 mm on 1 day or a total of 10 mm or more on 2 or 3 successive days occurred at all four sites prior to the appearance of symptoms on a particular leaf layer, though less heavy rain may suffice to splash inoculum onto upper leaves in shorter, immature canopies where stem elongation is incomplete. At the fifth site, infection occurred later in May and disease failed to develop to a significant degree. At all sites, the length of the incubation period on any of the top three leaves was found to be between 396 and 496 degree days.
Control of winter epidemics of S. tritici had little effect on yield, whereas spray sequences commencing later than growth stage (GS) 31 but immediately prior to the critical periods provided the best disease control and yield benefit. Regression models incorporating, as independent variables, area under the S. tritici disease progress curve for any of the top three leaves from their emergence (GS 32-37) satisfactorily explained yield loss at the four sites where disease was severe. Consideration of leaf 2 or leaf 3 alone accounted for more than 82% of the variance at each site and a yield loss from infection of leaf 2 related to thermal time is suggested as 0.00265% per C per day from the appearance of symptoms.
TL;DR: There is little evidence of a long-term increase in crop Cd concentrations at Rothamsted, despite changes in botanical composition in the permanent grassland experiment, cultivar changes in the wheat and barley experiments and changes in soil organic matter and soil pH of some plots.
Patent•
06 Dec 1989TL;DR: In this paper, a computer based video/graphics display system includes a computer system (22) having a graphics generator (24), a video signal from a video source (28) is fed through an input stage (26) to an asynchronous converter (30), the converter synchronises the video signal to the graphics generator, and the combined signal output from the fading/mixing matrix is fed to a computer display monitor (14).
Abstract: A computer based video/graphics display system includes a computer system (22) having a graphics generator (24). A video signal from a video source (28) is fed through an input stage (26) to an asynchronous converter (30). The converter (30) synchronises the video signal to the graphics generator (24). The output from the asynchronous converter (30) and the output from the graphics generator (24) are fed to a fading/mixing matrix (34). The combined signal output from the fading/mixing matrix is fed to a computer display monitor (14). The system allows the mixing or windowing of computer graphics and a video image on a common display.
TL;DR: Data indicate that [3H]4DAMP represents a useful ligand for selectively labeling the M1 and M3 muscarinic receptor subtypes.
TL;DR: Some attributes of the egg that are involved in dormancy and survival of nematodes are examined and changes that occur during the hatching process are detailed.
TL;DR: In vitro antibacterial activity was detected in 28 of the organic solvent extracts, primarily those of the hexane, and the extracts were most effective against Staphylococcus aureus and to a lesser extent Bacillus subtilis.
Abstract: Culture supernatants and methanolic and hexane extracts of 132 marine microalgae have been screened against six strains of bacteria. In vitro antibacterial activity was detected in 28 of the organic solvent extracts, primarily those of the hexane. The extracts were most effective against Staphylococcus aureus and to a lesser extent Bacillus subtilis. No antimicrobial activity was detected in the culture supernatants and no extract inhibited the growth of Escherichia coli, Streptococcus faecalis, Klebsiella pneumoniae or Pseudomonas aeruginosa.
TL;DR: This is a book that will show you even new to old thing, and when you are really dying of the nature of information, just pick it.
Abstract: It's coming again, the new collection that this site has. To complete your curiosity, we offer the favorite the nature of information book as the choice today. This is a book that will show you even new to old thing. Forget it; it will be right for you. Well, when you are really dying of the nature of information, just pick it. You know, this book is always making the fans to be dizzy if not to find.
TL;DR: Various lines of evidence indicate that the PAH concentrations in vegetation are an indication of atmospheric deposition directly onto the above-ground plant portions, and that uptake and translocation of soil-bound PAHs is of minor importance.
TL;DR: It is demonstrated that GR43175, unlike ergotamine, has a highly selective vasoconstrictor action on AVAs within the cranial circulation of anaesthetized cats and may be important in its antimigraine activity.
Abstract: The haemodynamic effects of the selective 5-HT1-like agonist GR43175 have been compared with that of ergotamine in anaesthetized cats. Both GR43175 (30-1000 micrograms/kg intravenously) and ergotamine (0.3-30 micrograms/kg intravenously) caused a dose-dependent reduction in the proportion of cardiac output passing through arteriovenous anastomoses (AVAs). However, unlike GR43175, the effect of ergotamine (30 micrograms/kg intravenously) was associated with marked increases in diastolic blood pressure and total peripheral resistance. In further studies, the effect of GR43175 on the distribution of blood flow within the carotid bed has been examined. GR43175 caused a reduction in total carotid arterial blood flow which was entirely due to a reduction in flow through carotid AVAs. These results demonstrate that GR43175, unlike ergotamine, has a highly selective vasoconstrictor action on AVAs within the cranial circulation of anaesthetized cats. Such a mechanism may be important in its antimigraine activity.
TL;DR: A Rothamsted light trap was operated for slightly over 12 months from the end of September 1979 to October 1980 at Genting Sempah, Pahang in Malaysia as discussed by the authors.
Abstract: A standard Rothamsted light trap was operated for slightly over 12 months from the end of September 1979 to October 1980 at Genting Sempah, Pahang in Malaysia. All speci- mens of macrolepidoptera families together with the Pyralidae were identified, counted and recorded. The numbers of species caught were compared with those obtained by a different method at a nearby site for over 10 years. Diversity, biomass and seasonality of the catch were compared with identically sampled populations in Great Britain and New Zealand. The Genting Sempah trap had very high diversity and biomass compared with the temperate samples and exhibited much less seasonality. The Pyralidae and other families (excluding Noctuidae and Geometridae) formed a much higher component of diversity in Genting than in Britain. The log-normal distribution fits the data better than the log-series. So the inter-quartile slope, Q, is the correct parameter for interfaunal comparisons.
TL;DR: Antibody-dependent enhancement ofyellow fever virus neurovirulence, as measured by a reduction in the average survival time of groups of mice, was demonstrated with wild-type or vaccine strains of yellow fever virus and with Japanese encephalitis virus using intraperitoneally administered monoclonal antibodies specific for the viral E glycoprotein of yellow Fever.
Abstract: Antibody-dependent enhancement of yellow fever virus neurovirulence, as measured by a reduction in the average survival time of groups of mice, was demonstrated with wild-type or vaccine strains of yellow fever virus and with Japanese encephalitis virus using intraperitoneally administered monoclonal antibodies specific for the viral E glycoprotein of yellow fever virus. Enhancement of virulence could be induced by neutralizing, non-neutralizing or protective antibodies if the virus was allowed to establish a productive infection in the mouse brain before the antibody was administered. The implications of antibody-dependent enhancement in flaviviruses are discussed.
TL;DR: This review provides a general overview of a range of fluorochromes available with a brief description of their properties, uses and limitations in the study of fungi and other cells.
TL;DR: The location of residue 91 of VP3, and of a number of candidate suppressor mutations, in the atomic structure of the virion suggests that the ts phenotype may result in destabilization of the particle and that the suppressors may function by stabilizing specific interfaces.
Abstract: Summary
The growth of the Sabin strain of type 3 poliovirus is reduced at high temperatures compared to that of its virulent precursor strain Leon. Recombinant viruses have been generated from infectious cDNA clones and demonstrate that the temperature-sensitive (ts) phenotype is mainly attributable to a difference in residue 91 of the virion protein VP3. Examination of non-ts mutants derived in vitro or in vivo reveals the existence of second site mutations some of which are clearly able to suppress the ts phenotype. The location of residue 91 of VP3, and of a number of candidate suppressor mutations, in the atomic structure of the virion suggests that the ts phenotype may result in destabilization of the particle and that the suppressors may function by stabilizing specific interfaces. It is not yet clear whether the ts phenotype is expressed at the level of the particle or in the form of defects in assembly or uncoating of the virion, or all three.
TL;DR: In this article, the authors proposed a sampling scheme for estimating the mean radiation from isolated blocks of land and for mapping the radiation over a region to meet some specified tolerance expressed in terms of standard error.
TL;DR: The development of the retention index over 30 years is summarised and advances that have occurred in recent years are highlighted in this paper, which concludes with a tabulation of recently available compilations of retention indices.
TL;DR: In this article, a modification to the pressure probe is described which allows very rapid extraction of sap samples from single higher plant cells, and the performance of this rapid sampling probe was assessed and compared with the unmodified probe for cells of both wheat and Tradescantia.
Abstract: Abstract. A modification to the pressure probe is described which allows very rapid extraction of sap samples from single higher plant cells. The performance of this rapid-sampling probe was assessed and compared with the unmodified probe for cells of both wheat and Tradescantia. Under some conditions, the unmodified probe operated too slowly to avoid dilution of cell sap during the extraction process. This led to values for apparent sample osmotic pressures that were below the turgor pressures for the same cells. The problem was particularly acute in young wheatleaf epidermal cells which are small, elongate and have high turgor pressure. These exhibited rapid water influx when their turgor was depressed during the sampling of their contents (half-time for pressure recovery in wheat cells was less than 1 s while in Tradescantia cells it was 3–5 s). Dilution during sampling was apparently negligible when the rapid sampling probe was used. The study was complemented by a simple model of the way cells dilute during sampling. Quantitative predictions of the model were consistent with our observed findings. The model is used to assess the major factors which determine a cell's susceptibility to dilution during sampling.
Patent•
08 Jun 1989TL;DR: A process for the production of a lubricating oil additive concentrate having a TBN greater than 300 comprises reacting at elevated temperature as discussed by the authors, where a salicylic acid derivative, an alkaline earth metal base added either in a single addition or in a plurality of additions at internediate points during the reaction, and at least one compound which is (i) water, (ii) a polyhydric alcohol having 2 to 4 carbon atoms, (iii) a di- (C₃ or C₄) glycol, (iv) a tri-
Abstract: A process for the production of a lubricating oil additive concentrate having a TBN greater than 300 comprises reacting at elevated temperature
component (A) a defined salicylic acid derivative,
component (B) an alkaline earth metal base added either in a single addition or in a plurality of additions at internediate points during the reaction,
component (C) at least one compound which is (i) water, (ii) a polyhydric alcohol having 2 to 4 carbon atoms, (iii) a di- (C₃ or C₄) glycol, (iv) a tri- (C₂-C₄) glycol, (iv) a mono- or poly-alkylene glycol alkyl ether of the formula (I)
R(OR¹) x OR² (I)
wherein R is a C₁ to C₆ alkyl group, R¹ is an alkylene group R² is hydrogen or a C₁ to C₆ alkyl group and x is an integer from 1 to 6, (vi) a C₁ to C₂₀ monohydric alcohol, (vii) a C₁ to C₂₀ ketone, (viii) a C₁ to C₁₀ carboxylic acid ester, or (ix) a C₁ to C₂₀ ether,
component (D) a lubricating oil,
component (E) carbon dioxide added subsequent to the, or each, addition of component (B),
component (F) a defined carboxylic acid or derivative, and
component (G) at least one compound which is (i) an inorganic halide of (ii) an ammonium alkanoate or mono-, di-, tri- or tetra-alkyl ammonium formate or alkanoate provided that, when component (G) is (ii), component (F) is not an acid chloride,
the weight ratios of all components being such as to produce a concentrate having a TBN greater than 300.
TL;DR: Preliminary data suggest that under the conditions employed, GR43175, and to a lesser extent 5‐CT, may discriminate between two sub‐populations of 5‐HT1D binding sites in porcine brain.
Abstract: We have examined the binding of 5-carboxamidotryptamine (5-CT) and GR43175 (3-(2-dimethylamino)ethyl-N-methyl-1H-indole-5-methane sulphonamide) to 5-HT1D sites labelled with [3H]-5-hydroxytryptamine [( 3H]-5-HT) in neonatal porcine caudate membranes. In competition studies, 5-CT produced shallow inhibition curves (Ki 138 nM, slope 0.31), indicating binding site heterogeneity, while GR43175 interacted with a single population of binding sites (Ki 251 nM, slope 0.98), producing a maximum of only 52% inhibition of [3H]-5-HT binding compared to 100% for 5-HT or 5-CT. In the presence of excess GR43175 (10 microM), 5-CT produced a monophasic inhibition curve with a Ki value of 800 nM for the remaining sites (slope 0.89). These preliminary data suggest that under the conditions employed, GR43175, and to a lesser extent 5-CT, may discriminate between two sub-populations of 5-HT1D binding sites in porcine brain.
Journal Article•
TL;DR: Ondansetron has been found to significantly delay the onset of emesis, and reduce the number of retches and vomits in ferrets receiving cisplatin, cyclophosphamide, or radiation, at much lower doses than metoclopramide and without the associated side effects.