Impacts of warming and elevated CO2 on a semi-arid grassland are non-additive, shift with precipitation, and reverse over time.

It is unclear how elevated CO2 (eCO2 ) and the corresponding shifts in temperature and precipitation will interact to impact ecosystems over time. During a 7-year experiment in a semi-arid grassland, the response of plant biomass to eCO2 and warming was largely regulated by interannual precipitation, while the response of plant community composition was more sensitive to experiment duration. The combined effects of eCO2 and warming on aboveground plant biomass were less positive in 'wet' growing seasons, but total plant biomass was consistently stimulated by ~ 25% due to unique, supra-additive responses of roots. Independent of precipitation, the combined effects of eCO2 and warming on C3 graminoids became increasingly positive and supra-additive over time, reversing an initial shift toward C4 grasses. Soil resources also responded dynamically and non-additively to eCO2 and warming, shaping the plant responses. Our results suggest grasslands are poised for drastic changes in function and highlight the need for long-term, factorial experiments.

Age-growth relationships, temperature sensitivity and palaeoclimate-archive potential of the threatened Altiplano cactus Echinopsis atacamensis.

The tall (>4 m), charismatic and threatened columnar cacti, pasacana [Echinopsis atacamensis (Vaupel) Friedrich & G.D. Rowley)], grows on the Bolivian Altiplano and provides environmental and economic value to these extremely cold, arid and high-elevation (~4000 m) ecosystems. Yet very little is known about their growth rates, ages, demography and climate sensitivity. Using radiocarbon in spine dating time series, we quantitatively estimate the growth rate (5.8 and 8.3 cm yr-1) and age of these cacti (up to 430 years). These data and our field measurements yield a survivorship curve that suggests precipitation on the Altiplano is important for this species' recruitment. Our results also reveal a relationship between nighttime temperatures on the Altiplano and the variation in oxygen isotope values in spines (δ18O). The annual δ18O minimums from 58 years of in-series spine tissue from pasacana on the Altiplano provides at least decadal proxy records of temperature (r = 0.58; P < 0.0001), and evidence suggests that there are longer records connecting modern Altiplano temperatures to sea-surface temperatures (SSTs) in the Atlantic Ocean. While the role of Atlantic SSTs on the South American Summer Monsoon (SASM) and precipitation on the Bolivian Altiplano is well described, the impact of SSTs on Altiplano temperatures is disputed. Understanding the modern impact of SSTs on temperature on the Altiplano is important to both understand the impact of future climate change on pasacana cactus and to understand past climate changes on the Altiplano. This is the best quantitative evidence to date of one of the oldest known cactus in the world, although there are likely many older cacti on the Altiplano, or elsewhere, that have not been sampled yet. Together with growth, isotope and age data, this information should lead to better management and conservation outcomes for this threatened species and the Altiplano ecosystem.

Training and the European Working Time Directive: a 7 year review of paediatric anaesthetic trainee caseload data.

BACKGROUND: The implementation of the European Working Time Directive (WTD) has reduced the hours worked by trainees in the UK to a maximum of 56 h per week. With a further and final reduction to 48 h per week scheduled for August 2009, there is concern amongst doctors about the impact on training and on patient care. Paediatric anaesthesia is one of the specialist areas of anaesthesia for which the Royal College of Anaesthetists (RCoA) recommends a minimum caseload during the period of advanced training. METHODS: We conducted a retrospective analysis of theatre logbook data from 62 Specialist Registrars (SpRs) who had completed a 12 month period of advanced training in paediatric anaesthesia in our institution between 2000 and 2007. RESULTS: After the implementation of the WTD 56 h week in 2004, the mean total number of cases performed by SpRs per year decreased from 441 to 336, a 24% reduction. We found a statistically significant reduction across all age groups with the largest reduction in the under 1 month of age group. The post-WTD group did not meet the RCoA recommended total minimum caseload or the minimum number of cases of <1 yr of age. CONCLUSIONS: Since the implementation of the WTD, there has been a significant reduction in the number of cases performed by SpRs in paediatric anaesthesia and they are no longer achieving the RCoA recommended minimum numbers for advanced training.

Relation of mesangial IgA glomerulonephritis to polymorphism of immunoglobulin heavy chain switch region.

We have investigated the switch regions of Ig heavy chain genes of patients with IgA glomerulonephritis (IgA-GN) using restriction fragment length polymorphism (RFLP) analysis. Genomic DNA from patients and controls was digested with the restriction endonuclease Sst I and transferred to nylon membranes using the Southern blot procedure and hybridized with a probe homologous to the switch region of the Ig C mu gene (S mu) which detects RFLPs in both S mu and the switch region of the Ig C alpha 1 gene (S alpha 1). A significant decrease in the frequency of the 2.6;2.1 kb heterozygous S mu phenotype was found in patients with IgA-GN (P = 0.003). With respect to the S alpha 1 region, there was a significant increase in the frequency of the 7.4 kb S alpha 1 phenotype (P = 0.002). In addition, a significant increase in the frequency of the 7.4 kb S alpha 1 allele was found (P = 0.0002). These results suggest that gene(s) within the Ig heavy chain loci may be important in the pathogenesis of IgA-GN.

Metabolic studies of the third component of complement and the glycine-rich beta glycoprotein in patients with hypocomplementemia.

Metabolic studies using radioiodine-labeled third component of complement (C3) and the glycine-rich beta glycoprotein (GBG), a major component of the C3b-feedback pathway, were undertaken in normal subjects, in 22 patients with evidence of complement activation, and in 11 patients with various renal diseases without evidence of complement activation. In seven normal subjects GBG was found to be a rapidly metabolized protein with catabolic rates ranging from 1.7% to 2.2% of the plasma pool/h, synthesis rates from 0.14 to 0.21 mg/kg per h. and extravascular/intravascular distribution ratios from 0.81 to 1.31. In patients with reduced plasma C3, both increased C3 fractional catabolic rates and reduced C3 synthesis rates were observed, and in some patients there was evidence of increased extravascular distribution of the protein. GBG catabolism was usually increased when there was evidence of C3 activation, presumably reflecting activation of the C3b-feedback; but GBG turnover was normal or only slightly accelerated in some patients with accelerated C3 catabolism and profound hypocomplementemia, suggesting that reduced C3 synthesis had limited activation of the C3b-feedback.

Best practice in primary care pathology: review 6.

This sixth best practice review examines four series of common primary care questions in laboratory medicine: (1) laboratory monitoring in hypertension and heart failure abnormalities; (2) markers of inflammatory joint disease; (3) laboratory investigation of chronic diarrhoea; and (4) mumps and chickenpox. The review is presented in question-answer format, referenced for each question series. The recommendations represent a precis of guidance found using a standardised literature search of national and international guidance notes, consensus statements, health policy documents and evidence-based medicine reviews, supplemented by Medline Embase searches to identify relevant primary research documents. They are not standards but form a guide to be set in the clinical context. Most are consensus based rather than evidence based. They will be updated periodically to take account of new information.

Regulated expression of the small nuclear ribonucleoprotein particle protein SmN in embryonic stem cell differentiation.

The SmN protein is a component of small nuclear ribonucleoprotein particles and is closely related to the ubiquitous SmB and B' splicing proteins. It is expressed in a limited range of tissues and cell types, including several undifferentiated embryonal carcinoma cell lines and undifferentiated embryonic stem cells. The protein declines to undetectable levels when embryonal carcinoma or embryonic stem cells are induced to differentiate, producing primitive endoderm or parietal endoderm or yielding embryonal bodies. This decline is due to a corresponding decrease in the level of the SmN mRNA. The potential role of SmN in the regulation of alternative splicing in embryonic cell lines and early embryos is discussed.

Influence of soil texture on hydraulic properties and water relations of a dominant warm-desert phreatophyte.

We investigated hydraulic constraints on water uptake by velvet mesquite (Prosopis velutina Woot.) at a site with sandy-loam soil and at a site with loamy-clay soil in southeastern Arizona, USA. We predicted that trees on sandy-loam soil have less negative xylem and soil water potentials during drought and a lower resistance to xylem cavitation, and reach E(crit) (the maximum steady-state transpiration rate without hydraulic failure) at higher soil water potentials than trees on loamy-clay soil. However, minimum predawn leaf xylem water potentials measured during the height of summer drought were significantly lower at the sandy-loam site (-3.5 +/- 0.1 MPa; all errors are 95% confidence limits) than at the loamy-clay site (-2.9 +/- 0.1 MPa). Minimum midday xylem water potentials also were lower at the sandy-loam site (-4.5 +/- 0.1 MPa) than at the loamy-clay site (-4.0 +/- 0.1 MPa). Despite the differences in leaf water potentials, there were no significant differences in either root or stem xylem embolism, mean cavitation pressure or Psi(95) (xylem water potential causing 95% cavitation) between trees at the two sites. A soil-plant hydraulic model parameterized with the field data predicted that E(crit) approaches zero at a substantially higher bulk soil water potential (Psi(s)) on sandy-loam soil than on loamy-clay soil, because of limiting rhizosphere conductance. The model predicted that transpiration at the sandy-loam site is limited by E(crit) and is tightly coupled to Psi(s) over much of the growing season, suggesting that seasonal transpiration fluxes at the sandy-loam site are strongly linked to intra-annual precipitation pulses. Conversely, the model predicted that trees on loamy-clay soil operate below E(crit) throughout the growing season, suggesting that fluxes on fine-textured soils are closely coupled to inter-annual changes in precipitation. Information on the combined importance of xylem and rhizosphere constraints to leaf water supply across soil texture gradients provides insight into processes controlling plant water balance and larger scale hydrologic processes.

Sprayable microencapsulated sex pheromone formulation for mating disruption of oriental fruit moth (Lepidoptera: Tortricidae) in Australian peach and pear orchards.

Areawide mating disruption treatments have been effective in controlling infestation of oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae), in Australian pome and stone fruit orchards. Although successful, the areawide mating disruption program has been an expensive approach by using hand-applied Isomate dispensers. Sprayable microencapsulated (MEC) pheromone formulations that can be applied with standard spray equipment could substantially reduce the cost of application. Field trials conducted during two consecutive seasons (2002-2004) demonstrated that monthly applications of MEC-OFM phase V (3M Canada, London, Ontario, Canada) at a rate of 125 ml/ha (37.1 g [AI]/ha) in replicated 2-ha blocks of both peaches and pears reduced oriental fruit moth shoot tip and fruit damage as effectively as a single application of Isomate OFM Rosso hand-applied dispensers (500 dispensers per ha) and as or more effectively than standard broad-spectrum insecticide sprays. Fruit protection was achieved despite high oriental fruit moth population densities in both crops as measured by moth catches in terpinyl acetate food and pheromone traps. Similar numbers of oriental fruit moths were captured among all treatments in food traps but captures of males in pheromone traps were disrupted (96-99%) in pheromone-treated blocks relative to controls. The results of this study suggest that microencapsulated formulations of pheromone could be effectively used in areawide mating disruption programs for oriental fruit moth in Australia as a cost-saving alternative to reservoir-style dispensers requiring labor-intensive hand application.

Precocious aging and dementia in patients with Down's syndrome.

Fifty unselected institutionalized patients with Down's syndrome were studied to determine the clinical course of precocious aging and mental and neurological deterioration. In our studies we establish statistically significant differences in neurological and psychiatric abnormalities and mental deterioration in patients below and above age 35, indicating progressive changes in the central nervous system. We demonstrate higher incidence of recent memory loss, impairment of short-term visual retention, frontal release signs, hypertonia, hyperreflexia, long-tract signs, and psychiatric problems. We also note the presence of external features of precocious aging. Down's syndrome appears to be a human chromosomal abnormality in which genetically determined biochemical defects leading to precocious aging and dementia can be studied.

T lymphocytes in patients with Down's syndrome.

Individuals with Down's syndrome (DS) are thought to have abnormalities in their immune system, and a tendency to infection and malignancy. Studies to quantify the number of T lymphocytes in the peripheral blood of 82 unselected institutionalized patients (50 DS, 27 controls matched for sex and age, 2 chronic lymphocytic leukemic, 2 acute leukemic, and 1 Hodgkin's disease) were conducted. The numbers of circulating T cells in DS patients did not differ significantly from the control group, and were in the upper limits of normality. Number of "avid" T cells, however, were significantly higher in the DS than in the control group. The blastogenic response of the T cells to mitogen was significantly depressed. The data did not exclude the existence of qualitative abnormalities. Except for DS patients with congenital heart disease, those older than 15 years were not more prone to upper respiratory infections than other institutionalized mentally retarded patients.

Expression of the SmB' splicing protein in rodent cells capable of following an alternative RNA splicing pathway.

The expression of the SmB and SmB' spliceosome proteins in a variety of cell types and tissues has been investigated. Although SmB is found in all cells studied, the SmB' protein is found only in a small number of rodent cell types. The presence of this protein is correlated with the ability to utilize an alternative pathway of RNA splicing which is not available in most cell types. This is the first demonstration of tissue specific expression of a protein component of the spliceo-some and suggests a role for SmB' in the regulation of some cases of alternative RNA splicing.

Isolation of cDNA clones encoding the human Sm B/B' auto-immune antigen and specifically reacting with human anti-Sm auto-immune sera.

A cDNA clone for the human SmB and B' auto-immune antigens has been isolated by antibody screening of a cDNA expression library. The cDNA clone hybridises with two distinct mRNAs, one of which is expressed in a tissue-specific manner. A fusion protein expressed from the cDNA clone was recognised by a number of sera from systemic lupus erythematosus (SLE) patients containing anti-Sm antibodies but not by sera reactive with other auto-immune antigens. The potential use of this clone in a diagnostic assay for SLE and in elucidating the processes regulating the expression of SmB and B' is discussed.

Comparison of three conjugation procedures for the formation of tracers for use in enzyme immunoassays.

One of the requirements for enzyme immunoassay is the formation of a labelled component of the assay system which can be either the ligand or the binder. Three methods for conjugating alkaline phosphatase to human placental lactogen were investigated, involving water-soluble carbodiimide, glutaraldehyde, and the periodate oxidation technique. Of the 3, the periodate oxidation technique proved superior giving a conjugate with only slight changes in the Michaelis constant (Km) and maximum velocity (Vmax) which could be used for an enzyme immunoassay for human placental lactogen in human plasma.

Preparative isolation of p67, A, B, B' and D from nRNP/Sm and Sm antigens by reverse-phase chromatography. Use in a polypeptide-specific ELISA for independent quantitation of anti-nRNP and anti-Sm antibodies.

The p67 (67 kDa) and A (33 kDa) polypeptides of nRNP/Sm antigen and the B, B' (28 and 29 kda) and D (16 kDa) polypeptides of 'free' Sm antigen were isolated and used in enzyme-linked immunoadsorbent assays (ELISA) for human autoantibodies. ELISA specificity was demonstrated using monoclonal antibodies. The ELISA using HPLC-purified polypeptides was found to be more sensitive than immunoblotting for detecting antibody. 86% of sera with precipitating anti-nRNP antibodies were positive in the ELISA, as were all sera with precipitating anti-Sm antibodies. Patients with rheumatoid arthritis (RA), Sjögrens syndrome (SS) and undifferentiated connective tissue disease (UCTD) had low levels of anti-p67 with a prevalence 11.6% and 18%, respectively, whilst patients with systemic lupus erythematosus (SLE) and mixed connective tissue disease (MCTD) had high levels and prevalence rates of 55.2% and 80%, respectively. Anti-B or anti-D antibodies were detected at high levels in SLE (prevalence 30%) but were found rarely in UCTD and MCTD (prevalence 7% and 10%) and not at all in RA or SS sera.

Anti-type II collagen ELISA. Increased disease specificity following removal of anionic contaminants from salt-fractionated type II collagen.

The purification of type II collagen, for the detection of anti-type II collagen antibodies by ELISA procedures, involves removal of proteoglycans by guanidine-HCl, followed by pepsin solubilisation and salt fractionation. However, type II collagen purified in this way may contain contaminants, despite the apparent purity on SDS-polyacrylamide gels. In this paper we demonstrate how additional purification by DEAE chromatography reduces the degree of background binding in the type II collagen ELISA, leading to an increase in disease specificity. The contaminants included proteoglycan and bound serum IgG from both rheumatoid arthritis (RA) patients and healthy controls in ELISA. Furthermore, positive correlations were observed in the sera (n = 24) between degree of reactivity to the contaminants and to (1) purified proteoglycan (r = 0.50, P = 0.01) and (2) pepsin (r = 0.65, P = 0.001). Thus, inadequate purification of type II collagen produces false positive reactions in the collagen ELISA and gives rise to a high background. A lack of specificity has been frequently associated with this assay.

Antibodies to La, Jo-1, nRNP and Sm detected by multi-track immunoblotting using a novel filter holder: a comparative study with counterimmunoelectrophoresis and immunodiffusion using sera from patients with systemic lupus erythematosus and Sjögren's syndrome.

The use of Western blotting or immunoblotting to detect autoantibodies in the serum of patients with autoimmune connective tissue diseases was investigated. An apparatus suitable for simultaneously screening 16 sera on immunoblots was used to show that a complex pattern of antibody binding polypeptides was present in whole HeLa cells. A simpler and readily interpreted pattern of binding was achieved using affinity-purified rabbit thymus antigens. Seventy-seven patients with systemic lupus erythematosus, 44 with primary Sjögren's syndrome and 50 normals were screened for anti-Sm, anti-La, anti-nRNP and anti-Jo-1 by immunoblotting and the results compared with those obtained by counterimmunoelectrophoresis and immunodiffusion. It was shown that both IgG and IgM antibodies must be analysed on immunoblots to detect the maximum number of positive sera, and that the immunoblot detects many anti-La sera which do not form precipitins.

Monoclonal antibodies to the Sjögren's syndrome associated antigen SS-B (La).

The nuclear autoantigen SS-B (Sjögren's syndrome B antigen) was purified from rabbit thymus extract by immunoaffinity chromatography with human autoantibodies, and used to immunise BALB/c mice for production of monoclonal antibodies. Fusion of spleen cells from an immunised mouse with NS-1 myeloma cells resulted in the isolation of 3 clones secreting anti-SS-B antibody. Subclasses were shown to be IgG2b by immunodiffusion. Specificity of the monoclonal antibodies (MCA) was determined by ELISA and indirect immunofluorescence. By immunoblotting all 3 MCA identified a single 45 K immunoreactive polypeptide in rabbit thymus, identical with the major polypeptide recognised by human sera containing anti-SS-B. Affinity columns prepared from the 3 MCA all bound SS-B from rabbit thymus extract, without binding other nuclear antigens. Immunofluorescence studies on standard substrates showed that SS-B was located predominantly in the nucleoplasm but in cells transformed by EBV or phytohaemagglutinin more prominent nucleolar and cytoplasmic staining was seen.

Idiopathic mesangiocapillary glomerulonephritis. Comparison of types I and II in children and adults and long-term prognosis.

Of 104 patients with idiopathic mesangiocapillary glomerulonephritis studied for at least two years, 69 patients had type I disease and 35 had type II. Forty-five patients were children, and 59 were adults. Type II mesangiocapillary glomerulonephritis was more common in children than in adults, but no other clinical feature distinguished the two types at onset. Complement studies revealed that patients with type II had lower serum C3 concentrations and more frequently showed C3-splitting activity (C3 nephritic factor) in the serum. Children had hypertension or a lowered glomerular filtration rate less frequently at onset than did adults, but children had a higher incidence of a hematuric onset; C3 nephritic factor was also more frequent in the children. During a follow-up period of two to 21 years (mean eight years), only seven patients (five with type I and two with type II) showed clinical remission, whereas 38 percent of patients with type I and 49 percent of patients with type II died or required dialysis; a further 23 percent of patients with type I and 16 percent of patients with type II had continuing disease and reduced glomerular filtration rate. Only the presence and persistence of a nephrotic syndrome in type I predicted renal failure. In both types, the presence of sclerosis or crescents in the initial renal biopsy specimen was associated with a poorer prognosis, but no other feature was of major prognostic value.

Successful removal and prevention of resynthesis of anti-HLA antibody.

The successful removal and prevention of the resynthesis of an anti-HLA antibody by plasma exchange and immunosuppression in a patient awaiting renal transplantation is described. Before treatment, the patient's serum contained a high titer (greater than 1/50) anti-HLA antibody that reacted with 94% of our lymphocyte donor panel and produced positive cross matches with the lymphocytes from 40 cadaver kidneys. Following treatment, her anti-HLA titers fell to less than 1/10 and her sera reacted with 43% of our lymphocyte donor panel and produced negative crossmatches with lymphocytes from the first two cadaver kidney donors she was tested against. She was successfully transplanted with the second of these kidneys and is now well eight months later, with good graft function.