Phosphorus in Agriculture: A Review of Results from 175 Years of Research at Rothamsted, UK.

Insight into the role of phosphorus (P) in soil fertility and crop nutrition at Rothamsted, UK, and its involvement in associated environmental issues, has come from long-term field experiments initially started by J. B. Lawes in 1843 and continued by others, together with experiments on different soils. Results from the 1940s confirmed that residues of P applied in fertilizers and manures build up reserves of P in soil. There is a strong relationship between crop yield and plant-available P (Olsen P), and a critical level of Olsen P can be determined. For soils near the critical level, P-use efficiency is high when the P applied and offtake by the crop is nearly equal. Soil inorganic P is associated with various soil components and is held there with a range of bonding energies so that when no P is applied, the decline in Olsen P follows a smooth curve. We conceptualize inorganic soil P as being in four pools of vastly varying size, availability for uptake, and extractability by reagents used in routine soil analysis, and with reversible transfer of P between pools. For very disparate soils at Rothamsted and in the United States, there is a strong relationship between the change in Olsen P and P removal/input ratios, suggesting an underlying similarity in inorganic P behavior. Maintaining soil near the critical level should optimize yield and the use of the global P resource while minimizing the risk of transfer of large amounts of P to the aquatic environment.

Application of PERALS™ alpha spectrometry and gamma spectrometry for analysis and investigation of environmental spills at ISL uranium mining projects.

Radiation protection and environmental monitoring in mining requires effective and reliable radionuclide analysis at all stages of the mine project-prior to mining, during operation and through to remediation and decommissioning. The approach presented in this paper was specially developed for the monitoring of radioactive waste resulting from spills during mining and mineral processing operations and uses a combination of high resolution gamma spectrometry, and PERALS™ alpha spectrometry to identify and reliably quantify the activity of the major members of the U-238 decay chain at activities down to 10 mBq g(-1) by direct radionuclide counting and by assessment of the activity of their decay products. This approach has reduced sample preparation and analysis time while providing effective analysis and quantification of naturally occurring radionuclides in environmental samples. It has been successfully applied to several in situ leach (ISL) mining-related projects involving investigations of process material spill impacts and also to routine environmental monitoring.

An energy budget agent-based model of earthworm populations and its application to study the effects of pesticides.

Earthworms are important organisms in soil communities and so are used as model organisms in environmental risk assessments of chemicals. However current risk assessments of soil invertebrates are based on short-term laboratory studies, of limited ecological relevance, supplemented if necessary by site-specific field trials, which sometimes are challenging to apply across the whole agricultural landscape. Here, we investigate whether population responses to environmental stressors and pesticide exposure can be accurately predicted by combining energy budget and agent-based models (ABMs), based on knowledge of how individuals respond to their local circumstances. A simple energy budget model was implemented within each earthworm Eisenia fetida in the ABM, based on a priori parameter estimates. From broadly accepted physiological principles, simple algorithms specify how energy acquisition and expenditure drive life cycle processes. Each individual allocates energy between maintenance, growth and/or reproduction under varying conditions of food density, soil temperature and soil moisture. When simulating published experiments, good model fits were obtained to experimental data on individual growth, reproduction and starvation. Using the energy budget model as a platform we developed methods to identify which of the physiological parameters in the energy budget model (rates of ingestion, maintenance, growth or reproduction) are primarily affected by pesticide applications, producing four hypotheses about how toxicity acts. We tested these hypotheses by comparing model outputs with published toxicity data on the effects of copper oxychloride and chlorpyrifos on E. fetida. Both growth and reproduction were directly affected in experiments in which sufficient food was provided, whilst maintenance was targeted under food limitation. Although we only incorporate toxic effects at the individual level we show how ABMs can readily extrapolate to larger scales by providing good model fits to field population data. The ability of the presented model to fit the available field and laboratory data for E. fetida demonstrates the promise of the agent-based approach in ecology, by showing how biological knowledge can be used to make ecological inferences. Further work is required to extend the approach to populations of more ecologically relevant species studied at the field scale. Such a model could help extrapolate from laboratory to field conditions and from one set of field conditions to another or from species to species.

Evaluation of iron ochre from mine drainage treatment for removal of phosphorus from wastewater.

Treatment of polluting discharges from abandoned coal mines in the UK currently produces ca 30,000 t y(-1) of hydrous iron oxides ("ochre"), for which there is no major end-use, but which has previously been shown to have potential for removing P from wastewater and agricultural runoff. The efficiency of ochre for P removal from wastewater was investigated in experiments at two sites in the UK: Leitholm in Scotland and Windlestone in England. The three-year experiment at Leitholm involved diverting secondary-treated wastewater effluent through a trough which contained granular and pelletized ochre at different times. In the nine-month experiment at Windlestone, beds of ochre pellets in horizontal and vertical flow configurations were tested. The ochre treatment systems at Leitholm reduced influent concentrations of total P (TP) and TP mass by ca 80% and 50%, respectively, during optimal flow conditions, and achieved a removal rate of up to 65+/-48 mg TP kg(-1) ochre d(-1). There was no detectable release of potentially toxic metals from the ochre during the experiments. P removal rates by concentration were inversely related to flow and declined during the different phases of the experiments, probably due to clogging. At Windlestone, higher removal rates up to 195 mg TP kg(-1) ochre d(-1) were achieved for short periods of time following cleaning of the experimental system. Ochre has considerable potential to remove P from wastewater in a multi-stage treatment system and has a lifetime estimated to be 10 times longer than other substrates tested for P removal.

Study of a combined percutaneous local anaesthetic and the TDS system for venepuncture.

Transdermal Delivery System (TDS) is a liquid formulation which can be applied to the skin via a metered pump spray to deliver drug across skin. This placebo controlled, double blind trial compared anaesthetic properties of two TDS systems (TDS alpha and TDS beta) with placebo. The active and placebo treatments were applied to the dorsum of the hands, bilaterally and simultaneously for 5 min on 100 healthy volunteers. Following cannulation, pain perception was measured using the verbal rating score (VRS) and visual analogue score (VAS). Lidocaine plasma levels were assessed at 0 and 2 h. The VRS and VAS results show that TDS beta significantly decreased pain score compared to placebo (p < 0.02). Blood lidocaine at 2 h post application was also higher for TDS beta than for TDS alpha, suggesting that a 5 min application of TDS beta was effective in delivering local anaesthetic and accelerating the onset of skin anaesthesia prior to venous cannulation in adults.

Time for tea, anyone?

There have been suggestions that urine samples positive for benzoylecognine, the diagnostic metabolite of cocaine, may be the result of consumption Mate de Coca, a commercially available tea made from coca (Erythroxylon coca) leaves. The Jockey Club in Great Britain commissioned research into this subject as several jockeys have tested positive for benzoylecognine over the past few years. Urine samples collected at various time points within 24 h after ingestion of a 250 ml infusion of Mate de Coca tea were analysed using three different methods. All samples tested positive for benzoylecognine.

Serum cortisol and 17-hydroxyprogesterone interrelation in classic 21-hydroxylase deficiency: is current replacement therapy satisfactory?

One of the main aims in the management of patients with congenital adrenal hyperplasia due to 21-hydroxylase deficiency is to achieve adequate suppression of the adrenal cortex with the smallest possible dose of glucocorticoid substitution. To evaluate the administration schedule of current replacement therapy regimens, we investigated the cortisol-17-hydroxyprogesterone interrelation in 36 patients (13 males and 23 females; median age, 12.3 yr; range, 6.1-18.8 yr) with salt-wasting congenital adrenal hyperplasia. As sufficient variation in 17-hydroxyprogesterone concentrations was required to allow analysis of the cortisol-17-hydroxyprogesterone interrelation, patients were divided into 2 groups depending on the adequacy of hypothalamic-pituitary-adrenal axis suppression. The first group consisted of 17 patients with suppressed 17-hydroxyprogesterone concentrations (group 1), and the second group consisted of 19 patients with nonsuppressed 17-hydroxyprogesterone concentrations (group 2). We determined serum cortisol and 17-hydroxyprogesterone concentrations at 20-min intervals for a total of 24 h while patients were receiving their usual replacement treatment with hydrocortisone and 9alpha-fludrocortisone. We also determined the lowest dose of dexamethasone required to suppress the 0800 h serum ACTH concentrations when administered as a single dose (0.3 or 0.5 mg/m(2)) the night before. Mean 24-h cortisol and 17-hydroxyprogesterone concentrations were 3.9 microg/dl (SD = 2.1) and 66.2 ng/dl (SD = 92.7), respectively, in group 1 and 4.1 microg/dl (SD = 2.5) and 4865.7 ng/dl (SD = 6951) in group 2. The 24-h 17-hydroxyprogesterone concentrations demonstrated circadian variation, with peak values observed between 0400-0900 h. In group 2, 17-hydroxyprogesterone concentrations decreased gradually in response to the rise in cortisol concentrations during the day, but remained low during the night despite the almost undetectable cortisol concentrations between 1600-2000 h. Mean 0800 h androstenedione concentrations correlated strongly with integrated 17-hydroxyprogesterone concentrations (r = 0.81; P < 0.0001), but not with integrated cortisol concentrations. There was a significant negative correlation between cortisol and 17-hydroxyprogesterone at lag time 0 min (r = -0.187; P < 0.0001), peaking at lag time 60 min (r = -0.302; P < 0.0001), with cortisol leading 17-hydroxyprogesterone by these time intervals. Finally, 0800 h serum ACTH concentrations were sufficiently suppressed after a dexamethasone dose of 0.3 mg/m(2) in all but three patients. These findings indicate that in classic 21-hydroxylase deficiency, hydrocortisone should be administered during the period of increased hypothalamic-pituitary-adrenal axis activity, between 0400-1600 h, with the biggest dose given in the morning. Blood investigations performed as part of monitoring of congenital adrenal hyperplasia patients should include androstenedione and 17-hydroxyprogesterone concentrations determined in the morning before the administration of hydrocortisone. It should also be emphasized that blood investigations are only complementary to the overall assessment of these patients, which is primarily based on the evaluation of growth and pubertal progress.

Prevalence, age of onset and demographic relationships of different areca nut habits amongst children in Tower Hamlets, London.

OBJECTIVE: To examine prevalence and demographic relationships of different areca nut habits amongst children. DESIGN: Self-administered questionnaire. SUBJECTS: Children aged between 11 and 15. Of 800 questionnaires distributed, 704 were fully completed (88%). SETTING: Two secondary schools in the London district of Tower Hamlets. MEASURES: Demographic, areca nut habits used, age first used, still using, frequency of use. RESULTS: Users of any areca nut habit were exclusively from the South Asian population. Of this population, 77% had engaged in a habit, and dependent upon habit between 54 and 92% of these still remained current users. The highest prevalence of current use for boys and girls respectively was for areca nut alone (36%, 43%), followed by mistee pan (35%, 29%), betel-quid (27%, 26%) and pan masala (14%, 16%). Of the current users, 44% engaged in one habit only, 24% two, 20% three and 13% all four. The highest period of risk for starting to use areca nut alone, betel-quid and mistee pan was between ages 5 and 12, whilst for pan masala it was after 10. Boys had a significantly higher risk of beginning use before 10 (P < .001) and a higher frequency of use for pan masala (P< .01), areca nut alone (P< .05) and betel-quid (P = .06) than girls. The frequency of using each habit was between 3 and 5 episodes per week, however boys use pan masala approximately 10 times per week. CONCLUSION: South Asian children may already be experienced users of areca nut. Greater attention should be directed towards identifying signs of oral submucous fibrosis, oral cancer and other potentially malignant lesions within the South Asian population.

Rapid analysis of 226Ra in waters by gamma-ray spectrometry.

Techniques for the determination of 226Ra in waters by gamma-ray spectrometry are examined, with an emphasis on methods capable of completion within 1-3 days of sample collection. Methods discussed utilise either: (i) the 186 keV 226Ra gamma ray, with the contribution from 235U being subtracted after a separate uranium determination, or (ii) measurement of ingrowing 222Rn progeny. An analysis of the statistical and systematic errors associated with each technique is presented. Examples are given of their application to analysis of uranium mine process waters.

Influence of the beta-agonist salbutamol on claw horn lesions and walking soundness in finishing pigs.

The effects of feeding the beta-adrenergic agonist salbutamol to pigs at levels between 0.5 and 5.0 mg/kg feed for different periods were studied in six experiments. The feet and ability to walk of pigs weighing 30 to 100 kg were examined at intervals. False sand-crack, white-line and heel erosion lesions were classified as mild or severe, and corns and wall haemorrhages were also recorded. At each examination the pig was given a grade for the overall severity of its foot lesions. Salbutamol fed at 1.0 to 5.0 mg/kg feed, for as little as 21 to 28 days, increased the frequency (P < 0.05 to 0.001) and often the severity (P < 0.05) of the foot lesions, the higher doses tending to produce more severe lesions, and the overall foot grades deteriorated (P < 0.001). The effects on both sexes were similar. No changes were observed when 0.5 mg/kg was fed for 56 days. Despite the severity of many of the foot lesions, the pigs became lame in only one experiment. Electron microscopy indicated that salbutamol was interfering with horn production, but light microscopy revealed no changes in skin sections. These findings suggested that salbutamol was not directly affecting the function of keratinocytes. Supplementing the diet of the pigs with biotin and methionine did not delay, or prevent, the effects of salbutamol.

Lack of effect of interferon alpha 2a upon fluorouracil pharmacokinetics.

The disposition of 5-fluorouracil (FUra) was studied in 19 colorectal cancer patients during treatment with FUra and high-dose leucovorin (LV) with or without interferon alpha 2a (IFN-alpha). All received LV 200 mg m-2 over 2 h, then FUra 400 mg m-2 over 5 min then FUra 400 mg m-2 over 22 h, repeated on day 2, on a 14 day cycle. Nine patients also received IFN-alpha 6 MU every 48 h, starting at least 2 weeks before the study. Series of 14 blood samples were assayed for FUra by reversed-phase high-performance liquid chromatography (HPLC). Minimum Akaike information criterion estimation was used to determine the simplest effective pharmacokinetic model. This consisted of a single compartment with first-order (linear) and Michaelis-Menten (non-linear) components to drug elimination. This model gave r2 > 0.98 in 19/20 data sets. With the Michaelis constant (KM) set at 15 microM, values were derived for the volume of distribution (Vd), the maximum rate of non-linear elimination (Vmax) and the first-order elimination rate constant (K1.e). Mean (+/- s.d.) values in control (no IFN-alpha) patients were: Vd 10.4 (+/- 1.9) l m-2, Vmax 182 (+/- 59) mumol l-1 h-1 and k1.e 4.35 (+/- 0.58) h-1. No significant differences were detected in patients receiving IFN-alpha, in whom the equivalent mean values were Vd 10.0 (+/- 0.9) l m-2, Vmax 141 (+/- 27) mumol l-1 h-1 and k1.e 3.96 (+/- 0.5) h-1. Mean trapezoidal AUC0-22 h was similar in the two groups (control patients 116 microM h, IFN-alpha patients 125 microM h). No significant correlations with renal or hepatic function were detected. These results, while not inconsistent with previous reports of a reduced rate of FUra elimination at higher IFN-alpha doses, suggest that any clinical effect of this moderate dose of IFN-alpha on FUra toxicity or activity is due to modulation at target cells, not to pharmacokinetic interaction.

Reliability of the Barlow and Ortolani tests for neonatal hip instability.

OBJECTIVE: To investigate if those responsible for screening for neonatal hip instability are using acceptable manual hip stress tests as described by Ortolani and Barlow. METHOD: A video camera was used to record the technique of 35 personnel who were responsible for screening. They examined both a baby and a simulator. The study comprised five groups, classified by experience and practice: senior orthopaedic surgeons, senior paediatric staff, junior paediatric staff, nurses, community staff. RESULTS: The seven authors together with six independent expert observers viewed the video and marked the performance with the aid of a specially designed proforma. Although there was some variation between these expert observers, the results showed differences in the scores obtained by the different groups of examiners over all aspects of the test procedure. CONCLUSION: Video recording for critical analysis and feedback is a useful technique in this situation. Overall, the results suggest that testing for neonatal hip instability was inadequate. A variety of hip stress manoeuvres were being performed. The ability of each subject to perform satisfactory tests seemed to depend on their experience and education. More "hands on" training and experience of testing might provide the necessary competency for screening.

Effects of flavonoids released naturally from bean (Phaseolus vulgaris) on nodD-regulated gene transcription in Rhizobium leguminosarum bv. phaseoli.

Nine flavonoid aglycones released from black bean (Phaseolus vulgaris 'PI165426CS') seeds and roots induced nodC::lacZ transcription in Rhizobium leguminosarum bv. phaseoli strains containing extra cloned copies of the regulatory genes nodD1, nodD2, or nodD3 from that biovar. Individual flavonoids generally induced highest levels of nodC::lacZ transcription (Imax) with extra copies of nodD2, and the concentration required for half-maximum induction (I50) was lowest with extra copies of nodD1 genes. One apparently unique feature of R. l. bv. phaseoli is that naturally released flavonoids with very diverse structures induce nod genes. For all three nodD genes, two compounds exuded from roots, genistein and naringenin, produced much higher levels of nodC::lacZ transcription than other flavonoids, but this fact was not explained by increased transcription of the nodD genes themselves. The remaining seven flavonoid aglycones showed reproducibly different capacities to induce nodC::lacZ transcription, but all were considerably less powerful inducers than genistein and naringenin in strains with extra copies of each of the nodD genes. Tests with glycosides of the nod-gene inducers showed that glycosides, which are normally released by bean, had lower I50 values than the corresponding aglycones with all nodD genes. Additive interactions observed between the strong nod-gene inducer genistein and the weak inducer eriodictyol remain to be explained at the molecular level.

Predeposit autologous blood transfusion in patients with colorectal cancer: a feasibility study.

Over a 2-year period, a predeposit autologous blood transfusion service was provided for all patients undergoing elective surgery for left-sided colonic or rectal cancer in one hospital. Of 129 such patients, 28 were suitable for autologous donation. Eight of these received autologous blood only, 13 required no transfusion, and seven needed additional homologous blood. Thus, although predeposit autologous transfusion for patients with colorectal cancer is possible, only a very small proportion are likely to derive any benefit which it might confer.

The products of Rhizobium genes, psi and pss, which affect exopolysaccharide production, are associated with the bacterial cell surface.

Translational fusions between a mutant phoA (lacking its promoter, ribosomal binding site and signal peptide sequence) and Rhizobium 'symbiotic' genes were isolated. Since these fusions expressed alkaline phosphatase (AP), the product of phoA, the genes into which phoA was inserted apparently specify proteins located in the bacterial periplasm or cell membrane, the compartment in which AP has activity. These genes were psiA and genes upstream of psiA (psiA is required for normal nodule development and strains with multicopy psiA fail to make exopolysaccharide (EPS) and to nodulate). Fusions between phoA and pss (exo) genes, which are required for EPS production, also resulted in the expression of AP indicating that products of these pss genes were located at the cell surface. Using gus fusions to psiA and pssA, we found that the former was expressed in N2-fixing bean root nodules but the latter was not.

Regulatory functions of the three nodD genes of Rhizobium leguminosarum biovar phaseoli.

The three nodD genes of a strain of Rhizobium leguminosarum biovar phaseoli were cloned to study their effects on transcription of themselves and of the nodC genes of biovars phaseoli and viciae. Efficient transcription of nodD1 required nodD1 and was enhanced by exposure of the cells to bean exudate consistent with the presence of a nod-box preceding the noIE-nodD1 operon. Transcription of nodD2 and nodD3 was constitutive. nodC of R. leguminosarum biovar phaseoli was activated by each of the nodD genes of that biovar in the absence of inducers but expression was enhanced in cells grown with bean exudate or the flavonoids genistein or naringenin. A mutant of nodD2, lacking 60 bp at its 3' end, activated nodC in the presence of inducer, but was defective in regulating certain of the nodD genes. The nodC gene of R. leguminosarum biovar viciae responded differently to the various nodD genes of R. leguminosarum biovar phaseoli than did the nodC of the latter biovar.

A Rhizobium leguminosarum mutant defective in symbiotic iron acquisition.

Iron acquisition by symbiotic Rhizobium spp. is essential for nitrogen fixation in the legume root nodule symbiosis. Rhizobium leguminosarum 116, an ineffective mutant strain with a defect in iron acquisition, was isolated after nitrosoguanidine mutagenesis of the effective strain 1062. The pop-1 mutation in strain 116 imparted to it a complex phenotype, characteristic of iron deficiency: the accumulation of porphyrins (precursors of hemes) so that colonies emitted a characteristic pinkish-red fluorescence when excited by UV light, reduced levels of cytochromes b and c, and wild-type growth on high-iron media but low or no growth in low-iron broth and on solid media supplemented with the iron scavenger dipyridyl. Several iron(III)-solubilizing agents, such as citrate, hydroxyquinoline, and dihydroxybenzoate, stimulated growth of 116 on low-iron solid medium; anthranilic acid, the R. leguminosarum siderophore, inhibited low-iron growth of 116. The initial rate of 55Fe uptake by suspensions of iron-starved 116 cells was 10-fold less than that of iron-starved wild-type cells. Electron microscopic observations revealed no morphological abnormalities in the small, white nodules induced by 116. Nodule cortical cells were filled with vesicles containing apparently normal bacteroids. No premature degeneration of bacteroids or of plant cell organelles was evident. We mapped pop-1 by R plasmid-mediated conjugation and recombination to the ade-27-rib-2 region of the R. leguminosarum chromosome. No segregation of pop-1 and the symbiotic defect was observed among the recombinants from these crosses. Cosmid pKN1, a pLAFR1 derivative containing a 24-kilobase-pair fragment of R. leguminosarum DNA, conferred on 116 the ability to grow on dipyridyl medium and to fix nitrogen symbiotically. These results indicate that the insert cloned in pKN1 encodes an element of the iron acquisition system of R. leguminosarum that is essential for symbiotic nitrogen fixation.

Rate of claw horn growth and wear in biotin-supplemented and non-supplemented pigs.

The growth and wear rate of claw horn was measured in 42 commercial hybrid pigs. Half received a ration supplemented with 1 mg d-biotin/kg food daily, while the others acted as controls. The start weights of three replicates of 10 pigs averaged 25 kg and their mean finishing weight was 85 kg. Twelve pigs averaged 18 kg at the start and 118 kg at the end of the experiment. No differences in horn growth and wear rates were found between the biotin-supplemented pigs and the controls, or between the front and hind claws, although horn growth and wear both decreased with age. Claw horn grew at an average of 10 mm/28 days in the pigs taken from 25 to 85 kg bodyweight and at 11 mm/28 days in the pigs taken from 18 to 118 kg. The mean rate of wear of claw horn was 6 mm/28 days.

Influence of biotin supplementation on pig claw horn: a scanning electron microscopic study.

Observations made with a scanning electron microscope of the claw horn and underlying soft tissues of young pigs fed a normal diet supplemented with 1 mg d-biotin/kg of feed were compared with observations on a similar group receiving no additional biotin. Supplementary biotin affected the structure of the coronary epidermis; there was an increase in the density of the horn tubules in the stratum medium, the horny squames in the stratum medium were more tightly packed and the tubules were more clearly defined in the pigs receiving biotin. The width of the band of intertubular horn adjacent to the laminae was greater in the claws of control pigs.