Showing papers by "University of Hertfordshire published in 1985"
TL;DR: The Euclidean distance matrix D of order n is symmetric with elements − 1 2 d ij 2, where dii=0 as discussed by the authors, and the dimensionality of D is defined as the least value of p=rank(X) of any generating X; in general p+1 and p+2 are also acceptable but may include imaginary coordinates.
305 citations
TL;DR: PYY concentrations in the circulation similar to those seen after the ingestion of food cause a marked reduction in gastric secretion, and this peptide should be considered as one of the possible candidates for the classical enterogastrone.
296 citations
TL;DR: Characteristic features included hypoalbuminaemia, increased alpha and beta plasma globulin levels and neutrophilia without left shift, and eosinophilia and anaemia were not features.
Abstract: Summary
Clinical and laboratory findings are recorded from a series of 15 cases (aged one to 16 years) of sudden-onset chronic diarrhoea with weight loss, progressing in many cases to emaciation and death, associated with the emergence of fourth stage cyathostome (trichoneme) larvae in large numbers through the colonic and caecal mucosae. Apart from a single incident in mid-October, disease only occurred in winter and spring (January to May). Characteristic features included hypoalbuminaemia, increased α and β plasma globulin levels and neutrophilia without left shift. Faecal egg counts were frequently negative and eosinophilia and anaemia were not features. Horses treated in the early stages responded well to larvicidal doses of fenbendazole (60 mg/kg bodyweight) but in cases where this therapy was delayed for weeks or months the prognosis was poor.
133 citations
125 citations
TL;DR: It is concluded that prostanoid-induced contractions of guinea-pig trachea can be mediated by both EP1- and TP-receptors.
91 citations
TL;DR: In this paper, hydrogen fluoride and tetrabutylammonium fluoride have been used to selectively deprotect alcoholic and phenolic silyl ethers respectively, respectively.
87 citations
TL;DR: An in vitro assay is described which simultaneously tests for the superoxide dismutase-like activity of low-molecular-weight copper chelates and their stability in the presence of excess EDTA and shows that antirheumatic drugs of the D-penicillamine type are clearly distinguished both from nonsteroidal anti-inflammatories and from some drugs which chelate copper but lack antIRheumatic activity.
Abstract: An in vitro assay is described which simultaneously tests for the superoxide dismutase-like activity of low-molecular-weight copper chelates and their stability in the presence of excess EDTA. The EDTA is introduced to simulate the competitive endogenous ligands a copper-chelating drug will encounter in plasma and other body fluids. Under the conditions of the assay, antirheumatic drugs of the D-penicillamine type are clearly distinguished both from nonsteroidal anti-inflammatories and from some drugs which chelate copper but lack antirheumatic activity.
72 citations
TL;DR: It is suggested that D1‐receptor agonists are unlikely to be effective in the treatment of Parkinson's disease.
Abstract: Chronic administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) induced parkinsonian symptoms, predominantly bradykinesia and tremor, in marmosets These symptoms were reduced by L-DOPA plus benserazide but the putative D1-receptor agonist SKF 38393-A did not affect tremor and increased the bradykinesia Neither treatment affected behaviour in normal marmosets It is suggested that D1-receptor agonists are unlikely to be effective in the treatment of Parkinson's disease
68 citations
TL;DR: In this article, the proportional hazards model is described, and its application to accelerated life testing and reliability growth testing illustrated by use of previously published and simulated data is advocated due to its generality and flexibility.
66 citations
TL;DR: This article observed candidates' use of notes and textbooks during an open-book examination and found that those who devoted more examination time to using notes and texts obtained less good scores and had obtained low scores on previous assessments.
Abstract: Summary Candidates’ use of notes and textbooks during an open‐book examination was systematically observed. The amounts of use were related to candidates’ previously measured abilities in the area, to their scores on the examination and to their responses to a questionnaire. The results indicated that, of the 30 candidates observed, those who devoted more examination time to using notes and texts obtained less good scores and had obtained low scores on previous assessments. The questionnaire led to findings about candidates’ preparation for the examination and negative experiences with notes and texts during the examination.
66 citations
TL;DR: A stock culture of isolate CP of potato virus X (PVX) maintained by serial subculture in plants of Nicotiana glutinosa was found to contain PVX strain group four in addition to the original strain group two, indicating that spontaneous appearance of groupFour in cultures of group two strains may occur readily.
Abstract: A stock culture of isolate CP of potato virus X (PVX) maintained by serial subculture in plants of Nicotiana glutinosa was found to contain PVX strain group four in addition to the original strain group two. The group four strain was separated from the mixture by sap-inoculation to potato cultivars Maris Piper and Pentland Dell, both of which carry PVX hypersensitivity genes Nx and Nb, by graft-inoculation to Maris Piper and by sap-inoculation to cultivar Pentland Ivory which carries Nb but not Nx. Strain group four seemed to be a minor component of the strain mixture in N. glutinosa as few potato plants became infected with it when insusceptible plants were sap-inoculated or when sap inoculum was diluted 500 times. The group four strain passed readily through tubers of infected potato plants and was stable on serial sub-culture in N. glutinosa. When stock cultures of PVX group two isolates B and EX kept in N. glutinosa were tested on cultivar Pentland Dell, they also proved to be mixtures of group two and group four, indicating that spontaneous appearance of group four in cultures of group two strains may occur readily.
When group four strains derived from isolate CP and from PVX common strain isolate DX were graft-inoculated to many plants of cultivar Cara, which carries PVX immunity gene Rx, there was no evidence of selection of a strain like HB which overcomes this gene. In mixed infection with isolate DX, HB was still present after passage through two generations of progeny tubers of cultivar Pentland Crown which lacks any resistance genes, indicating that HB is a fully competitive strain.
TL;DR: Cell leakage from the matrix was closely related to cell growth within the matrix, and leakage of cells from calcium alginate beads stocked with 1–16% cells was little different.
TL;DR: W worms are a valuable potential source of animal feed if they can be produced economically and machinery for harvesting worms, methods of processing them into animal feed and successful feeding trials with fish and chickens are described.
Abstract: The 84 Mt of cattle waste, 9 Mt of pig waste and 4-5 Mt of poultry waste produced annually in the U.K. create serious disposal problems. Research at Rothamsted since 1980 has shown that the earthworm Eisenia foetida and other species can break down these wastes rapidly under controlled conditions to provide valuable horticultural composts and high-grade protein suitable for animal feed. The conversion of animal wastes into earthworm tissue is very efficient, a tonne of suitable animal wastes producing up to 100 kg of worms, equivalent on a dry-mass basis to a conversion efficiency of the order of 10%. Earthworm dry matter is 60-70% protein with a higher content of essential amino acids, such as lysine and methionine, than either meat or fish meal. The other constituents of worms are 6-11% fat, 5-21% carbohydrate, 2-3% minerals and a range of vitamins, of which niacin and vitamin B $_{12}$ are of particular value. Thus worms are a valuable potential source of animal feed if they can be produced economically. Machinery for harvesting worms, methods of processing them into animal feed and successful feeding trials with fish and chickens are described.
TL;DR: The atypical profiles of action of some agonists and antagonists suggest that two subtypes of each broad receptor group of peripheral dopamine receptors may exist, and one of these subtypes can be found in the CNS.
TL;DR: The length of root hairs of wheat (Triticum aestivum L.) growing in Long Ashton nitrate nutrient solution was affected mainly by pH and the concentrations of calcium and nitrate, and buffering at pH 6-5 was found to affect the relationship between nutrient solution strength and the length ofroot hairs.
Abstract: The length of root hairs of wheat (Triticum aestivum L.) growing in Long Ashton nitrate nutrient solution was affected mainly by pH and the concentrations of calcium and nitrate. Root hair length was decreased by high pH (> 7 0) and by low calcium concentrations but was increased by nitrate. Buffering at pH 6-5 was found to affect the relationship between nutrient solution strength and the length of root hairs. The interactions between calcium, nitrate and buffering were determined. Phos phate concentration did not affect the length of root hairs of wheat, although low concentrations have been reported to stimulate root hair growth in other plants. The mechanisms by which pH, calcium and nitrate may affect root hair length are discussed.
TL;DR: The effect of the age of roots on their susceptibility to infection by a vesicular-arbuscular mycorrhizal fungus was compared in leek and clover and one clover plant was not colonized by G. mosseae despite the formation of many entry points.
Abstract: Summary
The effect of the age of roots on their susceptibility to infection by a vesicular-arbuscular mycorrhizal fungus was compared in leek (Allium porrum L.) and clover (Trifolium parviflorum Ehrh.). Plants were grown in soil lacking mycorrhizal fungi for up to 21 d (clover) or 32 d (leek) and then transplanted into soil infested with Glomus mosseae (Nicol. and Gerd.) Gerdemann and Trappe. The pattern of infection which occurred was compared with that in plants grown continuously in infested soil.
Leek roots up to 32 d old retained their susceptibility to infection whereas clover roots as young as 5 d old had become almost completely immune to penetration by G. mosseae and those which were 21 d old did not become infected at all. The most proximal part of the roots (9 mm in leek and 21 mm in the main root of clover) always remained uninvaded.
A difference between leek and clover was also observed in the distance of the most distal entry point from the root tip (10 and 1 mm, respectively). Some examples of host resistance to infection are described. One clover plant was not colonized by G. mosseae despite the formation of many entry points.
TL;DR: Neurobioassays of R larvae showed a consistently lower sensitivity of the neuromuscular system to pyrethroids when compared with the S larvae, thus confirming the indication from metabolic studies of the additional (site-insensitive) mechanism.
Abstract: The penetration, degradation and excretion of [3H]transpermethrin were examined in susceptible and field-collected pyrethroid-resistant strains of the tobacco budworm Heliothis virescens. No consistent differences in labelled materials excreted or recovered in cuticle rinses were found between the resistant (R) and susceptible (S) larvae. Considerably lower levels of the parent compound were present internally in R compared with S larvae after 24h (P <0.01), clearly identifying a metabolic resistance mechanism in Meloland and Westmorland larvae. Moderate levels of absorbed permethrin accompanied by an absence of poisoning symptoms were observed in certain individuals of both R strains, suggesting a second resistance mechanism. Neurobioassays of R larvae showed a consistently lower sensitivity of the neuromuscular system to pyrethroids when compared with the S larvae, thus confirming the indication from metabolic studies of the additional (site-insensitive) mechanism. Toxicity values suggest a cross-resistance to other pyrethroids.
TL;DR: The Pollination of Swede Rape (Brassica Napus L.) Bee World: Vol. 66, No. 1, pp. 16-22, 1985 as discussed by the authors.
Abstract: (1985). The Pollination of Swede Rape (Brassica Napus L.) Bee World: Vol. 66, No. 1, pp. 16-22.
TL;DR: A range of Rh(II) carboxylates and cis-Pt( II) complexes have been examined for their ability to increase the radiation sensitivity of aerobic and hypoxic V79 cells in vitro and it was not possible to demonstrate a similar effect in tumours in mice given the combination of Rh- methoxyacetate and the misonidazole analogue RSU 1070.
Abstract: A range of Rh(II) carboxylates and cis-Pt(II) complexes have been examined for their ability to increase the radiation sensitivity of aerobic and hypoxic V79 cells in vitro. The transition metal complexes sensitize in both air and nitrogen, with the greater effect generally occurring in nitrogen. The cis-Pt(II) complexes only show small levels of sensitization with dose modification factors (DMFs) of no more than 1.2. In contrast, the Rh(II) complexes can give DMFs of 2.0. Radiation chemical experiments show the transition metal complexes to have substantially lower redox potentials than metronidazole and, in addition, neither type of complex undergoes electron transfer reaction or adduct formation on interaction with radicals derived from DNA bases. Thus, the inorganic complexes do not operate by mechanisms similar to those occurring with electron affinic or stable free radical sensitizers. The increase in radiation sensitivity for cells treated with the Rh(II) carboxylates, but not the cis-Pt(II) complexes, is attributed to the ability of the Rh compounds to deplete intracellular thiols. Further, the efficiency of sensitization by the Rh(II) complexes and their ability to interact with cellular thiols depends upon the nature of the carboxylate ligand and follows the order butyrate greater than propionate greater than acetate greater than methoxyacetate. The differences between the carboxylates may be due to differences in drug uptake. A combination of the Rh(II) complexes with misonidazole given to hypoxic cells irradiated in vitro gives an additive response. However, it was not possible to demonstrate a similar effect in tumours in mice given the combination of Rh(II) methoxyacetate and the misonidazole analogue RSU 1070.
TL;DR: The potency of the thromboxane mimetic U‐46619 as an inhibitor of histamine‐induced acid secretion was markedly reduced in the presence of indomethacin, suggesting that U‐46519 may release endogenous antisecretory prostanoids.
Abstract: The effects of the cyclo-oxygenase inhibitors indomethacin and piroxicam have been investigated on histamine- and dibutyryl cyclic AMP-induced acid secretion in the rat isolated gastric mucosa. The relative potencies of a number of prostanoids as inhibitors of histamine-induced acid secretion were determined in an attempt to classify the prostaglandin receptor mediating this response. Indomethacin (8 X 10(-9) - 2.7 X 10(-6) M) and piroxicam (3 X 10(-6) M) potentiated the secretory responses elicited by histamine. This effect might be due to inhibition of the biosynthesis of antisecretory prostanoids. Indomethacin (2.7 X 10(-6) M) and piroxicam (3 X 10(-6) M) also potentiated the secretory response to dibutyryl cyclic AMP, but since prostaglandin E2 (PGE2, 10(-5) M) did not inhibit this secretory response, the mechanism of the potentiation may differ from that of histamine. The potency of the thromboxane mimetic U-46619 as an inhibitor of histamine-induced acid secretion was markedly reduced in the presence of indomethacin, suggesting that U-46619 may release endogenous antisecretory prostanoids. In the presence of indomethacin (2.7 X 10(-6) M) all the prostanoids tested produced concentration-related inhibitions of histamine-induced gastric acid secretion. PGE-analogues were the most potent compounds, the rank order of potency being 16, 16 dimethyl PGE2 greater than PGE2 greater than PGF2 alpha greater than U-46619 greater than PGD2 greater than PGI2. This order of potency is very similar to that obtained in smooth muscle preparations containing 'EP' receptors, suggesting that this receptor type also mediates inhibition of histamine-induced acid secretion in the rat.
TL;DR: An investigation was carried out to test the hypothesis that stutterers who achieved fluent speech during two weeks of intensive treatment would be less likely to relapse if they were also helped to reconstrue themselves as fluent people.
Abstract: An investigation was carried out to test the hypothesis that stutterers who achieved fluent speech during two weeks of intensive treatment would be less likely to relapse if they were also helped to reconstrue themselves as fluent people. Forty eight stutterers were randomly allocated to a technique or a construct group. By means of a form of behaviour modification they were helped to speak fluently. Then the treatment of the technique group focused on the practice of fluent speech in many situations while the construct group were helped to reconstrue this fluency along the lines of personal construct therapy. The treatment proved to be effective in reducing stuttering behaviour and the relapse rate was low. A comparison of the groups showed that the construct group had a significantly lower relapse rate than the technique group.
TL;DR: In this article, a study was made of growth and N concentrations of field-grown crops of spring barley (Hordeum vulgare L. cv. Georgie or Triumph).
Abstract: A study was made of growth and N concentrations of field-grown crops of spring barley (Hordeum vulgare L. cv. Georgie or Triumph). Nitrogen concentrations were calculated on the basis of both dry matter and tissue water because previous research had indicated that K concentrations expressed on the basis of tissue water were better for assessing the K status of crops. The aim was to see whether this was also the case for N.
When supplies of P and K were adequate, the addition of N fertilizer stimulated growth in all crops except when sufficient N was already supplied as farmyard manure. Percentage N in dry matter declined as plants grew and was higher in plants given N than in plants grown without N, although the difference diminished with time. Nitrogen concentrations calculated on the basis of tissue water were very similar for both N-sufficient and N-deficient crops despite large differences in growth rates. Nitrogen concentrations in tissue water also declined but only until anthesis, thereafter they increased. This pre-anthesis decline was due to the increase in the amount of stem tissue which had lower N concentrations in tissue water than leaves. Similarly the post-anthesis increase in N concentrations was due to the development of the ears which had high concentrations of N in tissue water.
The effects of deficiencies of P or K or water on N concentrations in tissue water of the cultivars Georgie or Julia were studied also in field experiments at Rothamsted. Lack of P and K inhibited growth of crops given 144 kg N/ha. Crops grown without N grew more slowly than those given N but their growth was not further inhibited by lack of P or K. Deficiencies of either P or K increased N concentrations calculated on the basis of tissue water in crops given 144 kg N/ha but not in crops grown without N. The increase in concentration was not due to changes in the proportions of leaves and stems but to real increases in N concentrations in leaves, stems and ears. Drought decreased growth and also resulted in higher N concentrations in tissue water.
In the absence of other limiting factors, N concentrations expressed on the basis of tissue water were very similar for both N-sufficient and N-deficient crops. They increased only when growth was limited by factors other than N. The implications of this for the control of N concentrations by crops is discussed.
It is concluded that N concentrations expressed on the basis of tissue water are unlikely to be useful for determining the N requirements of barley. Percentage N in dry matter might be more useful for this purpose.
TL;DR: The honeybee alarm pheromones 2·heptanone and isopentyl acetate were repellent to honeybee foragers when applied to plots of oil-seed rape and field beans and to sunflower heads.
Abstract: The honeybee alarm pheromones 2·heptanone and isopentyl acetate were repellent to honeybee foragers when applied to plots of oil-seed rape and field beans and to sunflower heads Their possible use to repel bees from crops before insecticide application is discussed
TL;DR: A group of drugs, including nalorphine, butorphanol and proxorphan, which produce an agonist action via κ receptors in the guinea-pig ileum and mouse vas deferens, were antagonists in the rabbit vas deferenns, suggesting that this tissue will only respond to high efficacy κ agonists.
TL;DR: Many insecticide/formulation/surface combinations lose effectiveness rapidly and the consequence of this in relation to the recovery of cockroach populations are discussed using mathematical models and field observations.
Abstract: Features of the evolution of synthetic pyrethroid insecticides are reviewed and related to the target function in control. The factors affecting residual activity are discussed and related to the surfaces to which different formulations are applied. Many insecticide/formulation/surface combinations lose effectiveness rapidly. The consequence of this in relation to the recovery of cockroach populations are discussed using mathematical models and field observations.
TL;DR: It is proposed that the materials, method of manufacture and the use to which the cannula is put are more important in the genesis of the minor complications of iv cannulation than the type of dressing.
TL;DR: A rapid, accurate and sensitive method for the determination of salbutamol in plasma and urine is described and provides data in good agreement with that obtained by gas chromatography--mass spectrometry.
TL;DR: A collaborative exercise involving twelve laboratories was organized for the European Economic Community to check the validity of an enclosed respirometric method for assessing the ready biodegradability of test chemicals, including insoluble substances, and it is proposed that the method be accepted.
TL;DR: Three groups of four calves treated intramuscularly with parvaquone (Clexon; Wellcome) were clinically cured while one in each group died of theileriosis, and total parasitological cure was not achieved in any of the calves.