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.

The importance of long-term experiments in agriculture: their management to ensure continued crop production and soil fertility; the Rothamsted experience

Long-term field experiments that test a range of treatments and are intended to assess the sustainability of crop production, and thus food security, must be managed actively to identify any treatment that is failing to maintain or increase yields. Once identified, carefully considered changes can be made to the treatment or management, and if they are successful yields will change. If suitable changes cannot be made to an experiment to ensure its continued relevance to sustainable crop production, then it should be stopped. Long-term experiments have many other uses. They provide a field resource and samples for research on plant and soil processes and properties, especially those properties where change occurs slowly and affects soil fertility. Archived samples of all inputs and outputs are an invaluable source of material for future research, and data from current and archived samples can be used to develop models to describe soil and plant processes. Such changes and uses in the Rothamsted experiments are described, and demonstrate that with the appropriate crop, soil and management, acceptable yields can be maintained for many years, with either organic manure or inorganic fertilizers.

Highlights

Long-term experiments demonstrate sustainability and increases in crop yield when managed to optimize soil fertility.Shifting individual response curves into coincidence increases understanding of the factors involved.Changes in inorganic and organic pollutants in archived crop and soil samples are related to inputs over time.Models describing soil processes are developed from current and archived soil data.

Changes in soil organic matter over 70 years in continuous arable and ley-arable rotations on a sandy loam soil in England

The sequestration in soil of organic carbon (SOC) derived from atmospheric carbon dioxide (CO₂) by replacing arable crops with leys, has been measured over 70 years on a sandy loam soil. The experiment was designed initially to test the effect of leys on the yields of arable crops. A 3-year grazed grass with clover (grass + clover) ley in a 5-year rotation with arable crops increased percentage organic carbon (%OC) in the top 25 cm of the soil from 0.98 to 1.23 in 28 years, but with little further increase during the next 40 years with all-grass leys given fertilizer nitrogen (N). In this second period, OC inputs were balanced by losses, suggesting that about 1.3% OC might be near the equilibrium content for this rotation. Including 3-year lucerne (Medicago sativa) leys had little effect on %OC over 28 years, but after changing to grass + clover leys, %OC increased to 1.24 during the next 40 years. Eight-year leys (all grass with N or grass + clover) in 10-year rotations with arable crops were started in the 1970s, and after three rotations %OC had increased to ca. 1.40 in 2000-2009. Over 70 years, %OC declined from 0.98 to 0.94 in an all-arable rotation with mainly cereals and to 0.82 with more root crops. Applications of 38 t ha^-1 farmyard manure (FYM) every fifth year increased %OC by 0.13% by the mid-1960s when applications ceased. Soil treated with FYM still contained 0.10% more OC in 2000-2009. Changes in the amount of OC have been modelled with RothC-26.3 and estimated inputs of C for selected rotations. Little of the OC input during the 70 years has been retained; most was retained in the grazed ley rotation, but 9 t ha^-1 only of a total input of 189 t ha^-1. In other rotations more than 98% of the total OC input was lost. Despite large losses of C, annual increases in OC of 4‰ are possible on this soil type with the inclusion of grass or grass + clover leys or the application of FYM, but only for a limited period. Such increases in SOC might help to limit increases in atmospheric CO₂.

HIGHLIGHTS

Can leys sequester significant amounts of atmospheric CO ₂ in SOM and contribute to the 4‰ initiative?Changes in the percentage and amount of OC were measured and modelled over 70 years and OC losses estimated.Three-year grass or grass + clover leys increased %OC, but only to an equilibrium level that was then maintained.Despite large losses, sequestering CO ₂-C at 4‰ year^-1 by growing grass or grass + clover leys is possible.

Testing the distinctness of shoot ionomes of angiosperm families using the Rothamsted Park Grass Continuous Hay Experiment

• The ionome is the elemental composition of a tissue or organism. Phylogenetic variation in the ionomes of plant shoots has been widely reported based on controlled experiments, vegetation surveys and literature meta-analyses. However, environmental effects on phylogenetic variation in shoot ionomes have not been quantified. This study tests the hypothesis that phylogenetic variation in shoot ionomes is robust to environmental perturbation and that plant families can be distinguished by their shoot ionomes. • Herbage was sampled from six subplots of the Rothamsted Park Grass Experiment. Subplots had received contrasting fertilizer treatments since 1856. Herbage was separated into its constituent species (n = 21) and concentrations of eleven mineral elements were determined in dried shoot material. • Shoot concentrations of calcium (Ca), zinc (Zn), manganese (Mn), magnesium (Mg) and sodium (Na) showed significant variation associated with plant species, and responded similarly to fertilizer treatments in diverse plant species. Species × treatment interactions were indicated for phosphorus (P), potassium (K), nickel (Ni), copper (Cu) and iron (Fe). Plant families could be distinguished by their shoot ionomes. The most informative elements for discriminant analysis were Ca > Mg > Ni > S > Na > Zn > K > Cu > Fe > Mn > P. • Whilst shoot ionomes were sensitive to fertilizer treatment, phylogenetic variation in a subset of the shoot ionome (Ca, Zn, Mn, Mg) was robust to this environmental perturbation.

Reductions and changing patterns of ambient PCDD/Fs in the UK: evidence and implications

Archived herbage samples taken between the mid-1800s and the present day from the Park Grass permanent grassland experiment in the UK were analysed for PCDD/Fs. The concentrations of SigmaP((4-8))CDD/Fs ranged between 15 (in 2003-2004) and 320 pg/g (in 1963) and the SigmaTEQ ranged between 0.11 (2003-2004) and 2.4 pg/g in (1903). The underlying trend from the mid-1970s to the present is of a decline by about factor of 10, indicating a general reduction in the air concentration/deposition fluxes. The homologue pattern in samples from the first half of the 20th century was characterised by the lower (mono- to tri-) PCDFs, indicating the dominance of domestic wood/coal burning on the SigmaP((1-8))CDD/Fs signature. The second half of the 20th century saw a substantial decline in domestic wood/coal burning for space heating in the UK, but also the 'rise and fall' in the production/use of chloroaromatic compounds - notably pentachlorophenol (PCP). The isomer/homologue patterns for the 1960-2004 samples have a much lower contribution from the lower PCDFs and large contributions from the hepta and octa-CDDs. The possibility that these are related to PCP inputs via different routes is discussed. The UK - in line with other countries - has had a policy to reduce the environmental sources and the emissions of PCDD/Fs, by the introduction of new combustion control technologies and emissions standards. However, these were not introduced to specifically address PCDD/F emissions until the 1990s. The declines in PCDD/F levels in these samples: (a) pre-date the introduction of emission control measures on incinerators and other combustion sources in the UK; (b) appear to have been largely unaffected by them.

Comparison of haloacetic acids in the environment of the Northern and Southern Hemispheres

Haloacetic acids (HAAs) are a family of compounds whose environmental concentrations have been extensively studied, primarily in Europe. Depending on the compound, their sources are believed to be both natural and anthropogenic. To better understand possible sources and contribute to the knowledge of the global distribution of these compounds, especially between the Northern and Southern Hemispheres, samples of precipitation, soils, and conifer needles were collected from Canada, Malawi, Chile, and the U.K. Precipitation samples exhibited highest HAA concentrations in collections from Canada, and lowest in those from Malawi. Malawi samples contained measurable levels of monobromoacetic acid (MBA) (56 ng/ L) unlike those from most other locations (< 9 ng/L). Soil HAA concentration levels were highest in the U.K. (e.g., 7.3 ng/g average TCA) and lowest in Malawi (0.8 ng/g average TCA), with Chile having higher levels (4.8 ng/g average TCA) than Canada (3 ng/g average TCA). Malawi soils contained small amounts of MBA (2 ng/g), in common with the two most southern of the 11 Chilean sites. Analysis of soil cores (10-cm depth sliced at 1 cm) from sites in Malawi and Chile showed that trichloroacetic acid (TCA) generally declined with depth while mono- and dichloroacetic acid (MCA and DCA) showed no trend. MCA, DCA, and TCA concentrations in archived U.K. soil samples increased by factors of 2, 4, and 5-fold over 75 years while TFA showed no consistent trend. Monochloroacetic acid (MCA) was detected in pine needles collected from Malawi. U.K. needle samples had the highest concentrations of all chloroacetic acids (CAAs): MCA, 2-18 ng/g; dichloroacetic acid (DCA), 2-38 ng/g; and trichloroacetic acid (TCA), 28-190 ng/g. Conifer needles from Canada and Chile contained CAAs at levels ranging from < 2 to 16 ng/g wet wt. Trifluoroacetic acid concentrations generally declined with increasing elevation in the samples from the Rocky Mountains in western Canada. The results indicate that concentrations of HAAs are greatest in the industrialized Northern Hemisphere but there are significant amounts of these compounds in the less industrialized Southern Hemisphere.

Time trends of atmospheric PBDEs inferred from archived U.K. herbage

Aerial portions of vegetation receive the bulk of their burden of persistent organic pollutants (POPs) from the atmosphere. Vegetation can therefore be a useful indicator of the changing atmospheric burden of POPs. Samples of archived pasture, collected from Rothamsted Experimental Station in the United Kingdom between 1930 and 2004, were analyzed for a range of polybrominated diphenyl ethers (PBDEs). PBDEs could not be routinely detected in the pre-1970 samples. Thereafter, the dominant congeners BDE 28, 47, 49, 99, 100, 153, 154, and 183 were frequently detected. The general trend was (a) a rise through the 1970s; (b) a minipeak in the mid-1980s, strongly influenced by one particularly high sample for 1984; (c) values remaining high through the late 1980s/1990s; (d) an indication of a more recent decline for all congeners (except BDE-28), consistent with recent restrictions on PBDE usage in Europe. These trends were compared to recent modeled estimates of U.K. PBDE emissions. The congener profiles of technical mixtures, U.K. air, soil, and pasture were compared and shown to be broadly similar. The implications for environmental release mechanisms are discussed.

Determinants of species richness in the Park Grass Experiment

The Park Grass Experiment at Rothamsted in southeast England was started in 1856, making it the longest-running experiment in plant ecology anywhere in the world. Experimental inputs include a range of fertilizers (nitrogen, phosphorus, potassium, and organic manures) applied annually, with lime applied occasionally, and these have led to an increase in biomass and, where nitrogen was applied in the form of ammonium sulfate, to substantial decreases in soil pH. The number of species per plot varies from three to 44 per 200 m(2), affording a unique opportunity to study the determinants of plant species richness and to estimate the effect sizes attributable to different factors. The response of species richness to biomass depends on the amount and type of nitrogen applied; richness declined monotonically with increasing biomass on plots receiving no nitrogen or receiving nitrogen in the form of sodium nitrate, but there was no relationship between species richness and biomass on plots acidified by ammonium sulfate application. The response to lime also depended on the type of nitrogen applied; there was no relationship between lime treatment and species richness, except in plots receiving nitrogen in the form of ammonium sulfate, where species richness increased sharply with increasing soil pH. The addition of phosphorus reduced species richness, and application of potassium along with phosphorus reduced species richness further, but the biggest negative effects were when nitrogen and phosphorus were applied together. The analysis demonstrates how multiple factors contribute to the observed diversity patterns and how environmental regulation of species pools can operate at the same spatial and temporal scale as biomass effects.

Observations on historical, contemporary, and natural PCDD/Fs

PCDD/Fs were determined in samples of archived surface soils collected from different locations around the world in the early 1880s, in contemporary surface soils from around the world, in archived subsurface soils collected at Rothamsted Experimental Station in the 1870/1880s, and in sections of peat core deposited between 5000 BP and the present. PCDD/Fs were detected in most of the samples. The potential sources and implications of the levels and mixtures of PCDD/Fs present in the samples are discussed. The homologue and isomer patterns observed in most of the contemporary European surface soils are commonly observed for European air samples and soil samples. The homologue pattern in the Rothamsted surface soils collected in the 1800s was similar, suggesting that similar sources of atmospheric emissions of PCDD/ Fs were operating in the UK in the 1800s as currently. Very different patterns, dominated by OCDD and with contributions of HpCDD and HxCDD, were found in some other samples. It is proposed that the PCDD/Fs present in the subsurface Rothamsted soils, archived (1880s) surface soils from Illinois and the Congo, clay beneath the peat bog (deposited approximately 5000 BP), and possibly surface soil samples from Thailand and Australia are of a natural origin. The most abundant TeCDD/F congeners measured in the peat samples here were also those observed by previous workers who studied a Canadian peat bog and are consistent with the microbially mediated oxidative coupling of chlorophenols. The study provides evidence for the widespread occurrence of PCDD/Fs in the environment prior to 1900 and for a complex array of sources (including natural) and environmental transformation processes.

Polychlorinated naphthalenes in U.K. soils: time trends, markers of source, and equilibrium status

Polychlorinated naphthalenes (PCNs) have been analyzed in archived soil from the U.K. to investigate historical trends. Samples were obtained from the Broadbalk experiment plots (1944-1986) and Luddington experiment station (1968-1990). Luddington samples also include a set of soils that received a one-time sludge treatment in 1968, and duplicate samples of this archived sludge were also analyzed. Peak residues of sumPCN (sum of all PCN congeners quantified) were approximately 9000 pg g(-1) dry weight in 1956, declining to approximately 300 pg g(-1) in contemporary soils. The one-time sludge application resulted in elevated soil residues that were 1.5-6 times higher than the control plot over the time series. This increase is consistent with the known application rate and the amount of sumPCN in the applied sludge (approximately 250,000 pg g(-1) dry wt). Half-lives forthe Luddington control soil and the sludge-amended soil for the period 1972-1990 were 5.3 and 9.9 years, respectively. Investigation of time trends revealed differences between homologue groups with the higher molecular weight congeners peaking earlier in the time series (pre-1950) and the lower molecular weight congeners peaking later, ca. 1970. Time trends of individual congeners were investigated in terms of their relative mass percent contribution to the sum of their homologue group. Significant (p < 0.05) increasing trends were observed for several congeners associated with combustion sources (CN-29, -51, -52/60, -54, and -66/67) suggesting that combustion related sources are more important now than they were in the past. However, no decreasing trend was observed for congeners that were thought to be susceptible to degradation by photolysis suggesting that this may not be a key elimination pathway of PCNs in the environment. A simple calculation of the fugacity status of PCNs in air and soil showed that the tri-CNs are exhibiting net outgassing, while the penta-CNs are still being deposited to soil. Interestingly, the penta-CNs associated with combustion show the largest gradient for air-to-soil transfer, supporting the notion that combustion sources are important contributors to contemporary air burdens of these congeners.

Further evidence for the existence of PCDD/Fs in the environment prior to 1900

PCDD/Fs and PCBs have been analyzed in a series of archived soil samples collected from various depths during the 1800s and early 1900s. PCBs were not found in soil samples collected before 1900, whereas PCDD/Fs were present in concentrations between 43 and 110 pg/g in surface soils, and between 9 and 150 pg/g in soils collected from below the surface. The PCDD/F homologue patterns of all surface soils were consistent with each other. The homologue pattern of deeper soils altered with depth to one that was dominated by highly chlorinated PCDDs. The highest sigma(4-8)PCDD/F concentration (150 pg/g) was found in the deepest soil analyzed (230-250 cm below the surface). The cork from one of the storage bottles contained considerable quantities of both PCBs and PCDD/Fs. However, contamination of the soils, either by diffusion through the cork or by cork particles, was discounted on the basis that no PCBs were evident in the soil, and that the PCDD/F homologue pattern in the cork was very different to that found in the soil. Similar arguments were used to discount contamination of the soil by dust. A sample of ashed vegetation from the archive, that had no cork stopper, contained high concentrations of PCBs (78 ng/g), concentrations of mono- to tri-CDFs that were higher than in any of the soils (190 pg/g), but very low concentrations of sigma(4-8)PCDD/F (12 pg/g). This pattern of analytes was considered to be representative of contamination from store room air and was completely different from the pattern observed in the soils. Taken together these observations indicate that contamination during storage, or subsequent handling, is unlikely to have occurred in archived soil samples that were stored with cork and wax seal intact. The results imply surface soil sigma(4-8)PCDD/F concentrations of around 60 pg/g at Rothamsted (southeast England) in the late 1800s, compared with approximately 300 pg/g reported for rural UK soils in the 1990s.

Organochlorine pesticide residues in archived UK soil

Archived background soils ("Broadbalk', 1944-1986) and sludge-amended soils ("Luddington", 1968-1990), collected from long-term agricultural experiments in the UK, were analyzed for a range of organochlorine (OC) pesticides to establish trends over time. Concentrations typically ranged from 0.1 to 10 ng/g of soil (dry weight), with gamma-hexachlorocyclohexane (gamma-HCH), dieldrin, and p,p'-DDE consistently having the highest concentrations. The trends in the Broadbalk background soils are largely consistent with usage patterns, with peak concentrations occurring in the 1960s for DDTs and between the 1960s and the 1980s for the other OCs. In the Luddington control and sludge-amended soils, several of the OCs show a significant decline in concentrations from the late 1960s to 1990, with half-lives ranging from approximately 7 years (alpha-HCH) to approximately 25 years (dieldrin). The sludge-amended plot received 125 tonnes of sludge per ha in 1968, which was mixed in to a depth of 15 cm. It appears that the sludge treatment had little effect on concentrations in the soil, with no significant difference between control soil and sludge-amended soil for most compounds, except for HCB, p,p'-DDE, and dieldrin. Enantiomeric fractions (EFs) of some chiral pesticides (alpha-HCH, cis- and trans-chlordane, and o,p'-DDT) were determined in the Luddington soils. Results reveal that enantioselective degradation of OC pesticides is occurring in these soils for trans-chlordane (TC) and cis-chlordane (CC). However, the depletion over time is not statistically significant, and there is no statistically significant difference between EFs in the control soil and sludge-amended soil. This indicates that enantioselective microbial degradation was not consistent over time and that the addition of sludge to soil did not significantly alter the enantiomeric preference of the microbial community.

Anaesthetic experience with paediatric interventional cardiology

Anaesthetic and sedation techniques, complications and outcomes were reviewed in 176 children undergoing 184 interventional cardiologic procedures. Techniques included sedation only, and ketamine, inhalational or narcotic anaesthesia. Ketamine infusion was the technique most frequently used. Ketamine was associated with a higher incidence of respiratory complications (P less than 0.05) than the other techniques. The higher incidence of hypercarbia (15.6 per cent), which did not affect outcome, may be attributable to the use of supplemental sedatives. The incidence of upper airway obstruction (7.8 per cent) was similar to that of previous studies. Vascular compromise resulted from the procedure in 33 patients, necessitating surgical correction in 16. Cardiac perforation occurred in four cases, causing one death. Pulmonary valve stenosis was most amenable to balloon dilatation and aortic valve stenosis least amenable. ketamine was the anaesthetic agent preferred by cardiologists for use in the catheterisation suite when general anaesthesia was required. Vigilant monitoring by anaesthetic staff is necessary during the procedure, and avoidance of concomitant narcotics is recommended if a ketamine technique with spontaneous ventilation is used.

Cadmium in cereal grain and herbage from long-term experimental plots at Rothamsted, UK

Crop samples harvested and stored from three long-term agricultural experiments started in the 1840-1850s at Rothamsted Experimental Station (UK) have been analysed recently for Cd. Increased Cd burden in the soils of the experiments, which have had a range of treatments, originates mainly from atmospheric deposition. Soils treated with farmyard manure (FYM) or, in some cases, applications of phosphate fertilisers, have increased Cd levels. Herbage, wheat and barley grain from the three experiments were analysed by neutron activation analysis (NAA) and graphite furnace atomic absorption spectrometry (GFAAS). Samples were bulked for groups of years between 1860 and 1986, from variously treated plots in each experiment (control or 'nil' treatment, P-fertilised, FYM-amended, NPK-fertilised-limed and unlimed). There were marked differences in Cd concentrations between treatments. For example, uptake of Cd into herbage was greater where P fertiliser had been applied than not, and was greater from unlimed than limed soils. Offtake of Cd (mg ha(-1) year(-1)) was affected by large differences in yield and probably also by other factors. These include changes in botanical composition in the permanent grassland experiment; cultivar changes in the wheat and barley experiments; changes in soil organic matter and soil pH of some plots; changes in atmospheric deposition of Cd through time. All of these potentially confounding factors make the interpretation of results complicated. It is concluded, however, that, with one exception, there is little evidence of a long-term increase in crop Cd concentrations at Rothamsted.

Polynuclear aromatic hydrocarbons in an agricultural soil: long-term changes in profile distribution

Soil profile samples collected from the same plot at Rothamsted Experimental Station in southeast England in 1893, 1944 and 1987 have been analysed for polynuclear aromatic hydrocarbons (PAHs). The total PAH burden of the plough layer (0-23 cm) has increased approximately four- to five-fold since the 1890s, with some compounds (notably benzo(b)fluoranthene, benzo(a)pyrene and pyrene) showing substantially greater increases. Average rates of increase in the plough layer for individual PAHs in the Rothamsted plots over the century since c. 1890 vary between 0.01 and 0.67 mg m(-2) year(-1). 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. The total PAH content of the 1893 Rothamsted samples was similar to that observed in soils from contemporary isolated/rural locations in the UK and showed little surface enrichment. By 1987 the surface soil at Rothamsted had been enriched in all PAH compounds measured by a factor of between 1.3 (acenaphthalene) and over 20 (benzo(a)pyrene). Increases in the PAH content of the 23-46 cm subsurface layer indicate migration of PAHs from the plough layer. Net average annual migration rates ranged from 0.01-0.14 mg m(-2) year(-1) for individual PAHs, and the rate appeared to be primarily a function of the plough layer PAH content, rather than physical/chemical properties of the individual compounds. This suggests particle-bound translocation as the dominant mechanism of PAH migration.

The morphology of the right ventricular outflow tract after percutaneous pulmonary valvotomy: long term follow up

Twenty nine patients (19 male, mean (SD) age 6.25 (0.5) years (range 0.16-15 years] with typical pulmonary valve stenosis were treated by balloon dilatation of the pulmonary valve. They were studied by echocardiography before the procedure, immediately after it, and at follow up (mean (SD) 10.2 (5.6) months, n = 18). The morphology of the pulmonary valve, the right ventricular-pulmonary artery gradient, and ratio of the systolic to diastolic endocardial dimensions (infundibular ratio) were examined. No patient had pulmonary regurgitation before the study. The valve gradient was significantly reduced (47%) from a mean (SD) of 72 (31) to 37 (23) mm Hg with no short term change in cardiac index after dilatation with a balloon with a mean (SD) diameter that was 118 (10.8)% of the valve annulus. The infundibular ratio was unchanged by the procedure (0.49 (0.11) (n = 21) before dilatation and 0.47 (0.14) (n = 16) after dilatation). In twenty seven patients the commissure of the pulmonary valve was seen to be torn after dilatation. Two patients with bicuspid valves had flail leaflets. Doppler examination at follow up showed mild pulmonary insufficiency in all 29 patients; the mean (SD) valve gradient (31 (+/- 21) mm Hg) at follow up was no different from the gradient found immediately after the procedure and infundibular ratio (0.58 (0.15) was not abnormal. These data indicate that commissural tears are the primary mechanism of valve disruption and demonstrate that the dynamic right ventricular outflow tract obstruction relaxes and gradient reduction persists at follow up.

Cutaneous mastocytosis in children: anaesthetic considerations

Despite considerable information and discussion about the risk of serious complications in patients with systemic mastocytosis undergoing general anaesthesia, little is known specifically about the risk to patients with isolated cutaneous mastocytosis. The experience of 29 general anaesthetics in 12 children with urticaria pigmentosa and three with solitary cutaneous mastocytoma was reviewed. No major complications were encountered and the four minor problems seen were self-limiting. The data from this study do not suggest that patients with urticaria pigmentosa or solitary cutaneous mastocytoma are at increased risk of life-threatening complications under general anaesthesia.

The influence of dietary unsaturated cis and trans and saturated fatty acids on tissue lipids of swine

A feeding trial was conducted to evaluate the effects of dietary trans unsaturated fatty acids (trans fat) and of the interplay of dietary saturated fatty acids (saturated fat), cis unsaturated fatty acids, (cis fat) and trans fat on tissue lipids, particularly those effects suggestive of angiotoxicity. Swine were fed for 10 months a diet containing 17% added fat. Seven blends of varying proportions of the 3 fat components provided sufficient sample points to permit an examination of the interplay. Parameters under study included weight gain, serum cholesterol and triglyceride concentrations, lipoprotein lipid profile, total lipid and cholesterol concentrations of liver, heart and aorta, fatty acid composition of liver and aorta lipids and hepatic fatty acid synthesis and cholesterol synthesis and oxidation. Fat blends containing disproportionately high levels of saturated or cis fat generally elicited responses consistent with results reported by others. The notable exception was the serum cholesterol concentration. Throughout the study, the swine were hypercholesterolemic. Swine fed the high saturated fat blend had serum cholesterol levels equal to those swine fed the high cis fat blend. Serum cholesterol levels in the swine fed the other fat blends were more elevated. Another apparent anomaly was the lower concentration of lipid in the aortas of swine fed the high-saturated fat diet. The impact of the trans fat was modulated by the relative proportions of saturated and cis fat in the diet. The impact of trans fat was of greater magnitude for most parameters when the fat blend was low in saturated fat. The sole parameter suggestive of trans fat-mediated angiotoxicity was the distribution of lipids in lipoprotein fractions. Swine fed diets containing trans fat had lower relative proportions of the alpha-lipoprotein lipids. Although hypercholesterolemic, the high fat diets were not overtly angiotoxic except when fed to swine that carried a specific immunogenetically-defined low density lipoprotein.