Nitrogen fertilizer rate but not form affects the severity of Fusarium wilt in banana

Nitrogen (N) fertilizers are routinely applied to bananas (Musa spp.) to increase production but may exacerbate plant diseases like Fusarium wilt of banana (FWB), which is the most economically important disease. Here, we characterized the effects of N rate and form on banana plant growth, root proteome, bacterial and fungal diversity in the rhizosphere, the concentration of Fusarium oxysporum f.sp. cubense (Foc) in the soil, and the FWB severity. Banana plants (Musa subgroup ABB) were grown under greenhouse conditions in soil with ammonium or nitrate supplemented at five N rates, and with or without inoculation with Foc. The growth of non-inoculated plants was positively correlated with the N rate. In bananas inoculated with Foc, disease severity increased with the N rate, resulting in the Foc-inoculated plant growth being greatest at intermediate N rates. The abundance of Foc in the soil was weakly related to the treatment conditions and was a poor predictor of disease severity. Fungal diversity was consistently affected by Foc inoculation, while bacterial diversity was associated with changes in soil pH resulting from N addition, in particular ammonium. N rate altered the expression of host metabolic pathways associated with carbon fixation, energy usage, amino acid metabolism, and importantly stress response signaling, irrespective of inoculation or N form. Furthermore, in diseased plants, Pathogenesis-related protein 1, a key endpoint for biotic stress response and the salicylic acid defense response to biotrophic pathogens, was negatively correlated with the rate of ammonium fertilizer but not nitrate. As expected, inoculation with Foc altered the expression of a wide range of processes in the banana plant including those of defense and growth. In summary, our results indicate that the severity of FWB was negatively associated with host defenses, which was influenced by N application (particularly ammonium), and shifts in microbial communities associated with ammonium-induced acidification.

Extraction of metals from mildly acidic tropical soils: Interactions between chelating ligand, pH and soil type

Naturally occurring and synthetic chelating ligands can act as suppressants for fungal pathogens, nematodes and weeds, based on their ability to alter micronutrient bioavailability in soil, particularly iron. Chelators are also used as detergents, for remediation of heavy metal contamination and for supplying metals as fertiliser. The aim of this work was to test the ability of chelators to solubilise metals, in particular iron, in tropical soils over an environmentally relevant pH range. Six topsoils from farms in North Queensland, Australia were adjusted to pH 5, 6 and 7 and then extracted with CaCl₂, EDTA, DTPA, EDDHA and mimosine. The extracts were analysed for concentrations of aluminium, copper, iron, magnesium, manganese, potassium, strontium and zinc. EDDHA solubilised iron effectively under all of the conditions tested, indicating its likely suitability for pest suppression. The concentration of aluminium in EDDHA extracts was positively correlated with pH, and at pH 7 the concentration of aluminium was far greater than that of iron. An increase in the mobility of aluminium from EDDHA application to soil may lead to aluminium toxicity in plants, which should be considered further in any practical application of EDDHA. Mimosine, which is also a strong chelator, was a poor extractor of all metals, possibly due to adsorption to the soil.

Publisher Correction: Farming with crops and rocks to address global climate, food and soil security

In the version of this Perspective originally published, 'acidification' was incorrectly spelt as 'adification' in Fig. 4. This has now been corrected.

Farming with crops and rocks to address global climate, food and soil security

The magnitude of future climate change could be moderated by immediately reducing the amount of CO₂ entering the atmosphere as a result of energy generation and by adopting strategies that actively remove CO₂ from it. Biogeochemical improvement of soils by adding crushed, fast-reacting silicate rocks to croplands is one such CO₂-removal strategy. This approach has the potential to improve crop production, increase protection from pests and diseases, and restore soil fertility and structure. Managed croplands worldwide are already equipped for frequent rock dust additions to soils, making rapid adoption at scale feasible, and the potential benefits could generate financial incentives for widespread adoption in the agricultural sector. However, there are still obstacles to be surmounted. Audited field-scale assessments of the efficacy of CO₂ capture are urgently required together with detailed environmental monitoring. A cost-effective way to meet the rock requirements for CO₂ removal must be found, possibly involving the recycling of silicate waste materials. Finally, issues of public perception, trust and acceptance must also be addressed.

The effects of biochar, compost and their mixture and nitrogen fertilizer on yield and nitrogen use efficiency of barley grown on a Nitisol in the highlands of Ethiopia

The effects of organic amendments and nitrogen (N) fertilizer on yield and N use efficiency of barley were investigated on a Nitisol of the central Ethiopian highlands in 2014. The treatments were factorial combinations of no organic amendment, biochar (B), compost (Com), Com+B and co-composted biochar (COMBI) as main plots and five N fertilizer levels as sub-plots, with three replicates. Application of organic amendment and N fertilizer significantly improved yield, with grain yield increases of 60% from Com+B+69kgNha(-1) at Holetta and 54% from Com+92kgNha(-1) at Robgebeya, compared to the yield from the maximum N rate. The highest total N uptake was obtained from Com+B+92kgNha(-1) at Holetta (138kgha(-1)) and Com+92kgNha(-1) at Robgebeya (101kgha(-1)). The agronomic efficiency (yield increase per unit of N applied, AE), apparent recovery efficiency (increase in N uptake per unit of N applied, ARE) and physiological efficiency (yield increase per unit of N uptake, PE) responded significantly to organic amendments and N fertilizer. Mean AE and ARE were highest at B+23kgNha(-1) at Holetta and at B+23 and B+46kgNha(-1) at Robgebeya. The PE ranged from 19 to 33kggrainkg(-1) N uptake at Holetta and 29-48kggrainkg(-1) N uptake at Robgebeya. The effects of organic amendments and N fertilizer on AE, ARE and PE were greater at Robgebeya than at Holetta. The enhancement of N use efficiency through application of organic amendments emphasizes the importance of balanced crop nutrition, ensuring that barley crops are adequately supplied with N and other nutrients. Overall, the integration of both organic and inorganic amendments may optimize N uptake efficiency and reduce the amount of N fertilizer required for the sustainable barley production in the long-term.

The role of molecular mimicry and other factors in the association of Human Endogenous Retroviruses and autoimmunity

Human Endogenous Retroviruses (HERVs) have been implicated in autoimmune and other diseases. Molecular mimicry has been postulated as a potential mechanism of autoimmunity. Exogenous viruses have also been reported to be associated with the same diseases, as have genetic and environmental factors. If molecular mimicry were to be shown to be an initiating mechanism of some autoimmune diseases, then therapeutic options of blocking antibodies and peptides might be of benefit in halting diseases at the outset. Bioinformatic and molecular modelling techniques have been employed to investigate molecular mimicry and the evidence for the association of HERVs and autoimmunity is reviewed. The most convincing evidence for molecular mimicry is in rheumatoid arthritis, where HERV K-10 shares amino acid sequences with IgG1Fc, a target for rheumatoid factor. Systemic lupus erythematosus is an example of a condition associated with several autoantibodies, and several endogenous and exogenous viruses have been reported to be associated with the disease. The lack of a clear link between one virus and this condition, and the spectrum of clinical manifestations, suggests that genetic, environmental and the inflammatory response to a virus or viruses might also be major factors in the pathogenesis of lupus and other autoimmune conditions. Where there are strong associations between a virus and an autoimmune condition, such as in hepatitis C and cryoglobulinaemia, the use of bioinformatics and molecular modelling can also be utilized to help to understand the role of molecular mimicry in how HERVs might trigger disease.

Benefits of biochar, compost and biochar-compost for soil quality, maize yield and greenhouse gas emissions in a tropical agricultural soil

Soil quality decline represents a significant constraint on the productivity and sustainability of agriculture in the tropics. In this study, the influence of biochar, compost and mixtures of the two on soil fertility, maize yield and greenhouse gas (GHG) emissions was investigated in a tropical Ferralsol. The treatments were: 1) control with business as usual fertilizer (F); 2) 10 t ha(-1) biochar (B)+F; 3) 25 t ha(-1) compost (Com)+F; 4) 2.5 t ha(-1) B+25 t ha(-1) Com mixed on site+F; and 5) 25 t ha(-1) co-composted biochar-compost (COMBI)+F. Total aboveground biomass and maize yield were significantly improved relative to the control for all organic amendments, with increases in grain yield between 10 and 29%. Some plant parameters such as leaf chlorophyll were significantly increased by the organic treatments. Significant differences were observed among treatments for the δ(15)N and δ(13)C contents of kernels. Soil physicochemical properties including soil water content (SWC), total soil organic carbon (SOC), total nitrogen (N), available phosphorus (P), nitrate-nitrogen (NO3(-)N), ammonium-nitrogen (NH4(+)-N), exchangeable cations and cation exchange capacity (CEC) were significantly increased by the organic amendments. Maize grain yield was correlated positively with total biomass, leaf chlorophyll, foliar N and P content, SOC and SWC. Emissions of CO2 and N2O were higher from the organic-amended soils than from the fertilizer-only control. However, N2O emissions generally decreased over time for all treatments and emission from the biochar was lower compared to other treatments. Our study concludes that the biochar and biochar-compost-based soil management approaches can improve SOC, soil nutrient status and SWC, and maize yield and may help mitigate greenhouse gas emissions in certain systems.

Rheumatoid Arthritis is Associated with IgG Antibodies to Human Endogenous Retrovirus Gag Matrix: A Potential Pathogenic Mechanism of Disease?

Objective.

Human endogenous retrovirus (HERV)-K10 has been implicated in the etiology and pathogenesis of rheumatoid arthritis (RA). A secondary immune response to this virus might suggest an antigen-driven response in patients. The Gag region of HERV-K10 could provide a key epitope important for immunological reactivity. We investigated the presence of IgG antibodies to this region and assessed its significance in RA.

Methods.

We determined an antigenic peptide on the matrix segment of HERV-K10 and developed an ELISA system to detect IgG antibodies in patients with RA and controls. The presence of antibodies to the matrix peptide (denoted as MAG1: RIGKELKQAGRKGNI) was correlated with patient details.

Results.

On screening patients’ serum, we found a significantly higher mean IgG antibody response to MAG1 in 30 patients with RA as compared to 23 patients with inflammatory bowel disease (p = 0.003), 29 patients with osteoarthritis (p = 0.001), and 43 healthy individuals (p = 0.002). Reactivity was not observed to a control peptide possessing a nonhomologous amino acid sequence. On evaluating clinical details with serological activity, no correlation with disease duration (p = 0.128), sex (p = 0.768), or rheumatoid factor status (p = 0.576) was found.

Conclusion.

A significantly elevated IgG antibody response to an HERV-K10 Gag matrix peptide was observed in patients with RA, suggesting that the exposure of HERV-K10 may cause a secondary, antigenic driven immune response in RA.

Molecular composition of recycled organic wastes, as determined by solid-state 13C NMR and elemental analyses

Using solid state (13)C NMR data and elemental composition in a molecular mixing model, we estimated the molecular components of the organic matter in 16 recycled organic (RO) wastes representative of the major materials generated in the Sydney basin area. Close correspondence was found between the measured NMR signal intensities and those predicted by the model for all RO wastes except for poultry manure char. Molecular nature of the organic matter differed widely between the RO wastes. As a proportion of organic C, carbohydrate C ranged from 0.07 to 0.63, protein C from <0.01 to 0.66, lignin C from <0.01 to 0.31, aliphatic C from 0.09 to 0.73, carbonyl C from 0.02 to 0.23, and char C from 0 to 0.45. This method is considered preferable to techniques involving imprecise extraction methods for RO wastes. Molecular composition data has great potential as a predictor of RO waste soil carbon and nutrient outcomes.

The state of antibody therapy

Therapeutic antibodies are widely used in the treatment of various diseases and disease conditions, including cardiovascular diseases, autoimmune disorders, malignancies, and infections. With at least 23 therapeutic agents currently in clinical use and a successful business generating large revenues, major technological advances are now in place to improve the specificity and efficacy of those antibodies already in the market and also generate new, safe and effective macromolecules for the treatment of other ailments. This review provides a summary of the current state of antibody therapy, highlights and discusses recent developments in the field of antibody-based therapeutics production, combination therapy and shows the status of some of the agents that are in clinical trial.

A role for human endogenous retrovirus-K (HML-2) in rheumatoid arthritis: investigating mechanisms of pathogenesis

Human endogenous retroviruses (HERVs) are remnants of ancient retroviral infections within the human genome. These molecular fossils draw parallels with present-day exogenous retroviruses and have been linked previously with immunopathology within rheumatoid arthritis (RA). Mechanisms of pathogenesis for HERV-K in RA such as molecular mimicry were investigated. To clarify a role for HERVs in RA, potential autoantigens implicated in autoimmunity were scanned for sequence identity with retroviral epitopes. Short retroviral peptides modelling shared epitopes were synthesized, to survey anti-serum of RA patients and disease controls. A novel real-time polymerase chain reaction (PCR) assay was also developed to quantify accurately levels of HERV-K (HML-2) gag expression, relative to normalized housekeeping gene expression. Both serological and molecular assays showed significant increases in HERV-K (HML-2) gag activity in RA patients, compared to disease controls. The real-time PCR assay identified significant up-regulation in HERV-K mRNA levels in RA patients compared to inflammatory and healthy controls. Exogenous viral protein expression and proinflammatory cytokines were also shown to exert modulatory effects over HERV-K (HML-2) transcription. From our data, it can be concluded that RA patients exhibited significantly elevated levels of HERV-K (HML-2) gag activity compared to controls. Additional factors influencing HERV activity within the synovium were also identified. The significant variation in RA patients, both serologically and transcriptionally, may be an indication that RA is an umbrella term for a number of separate disease entities, of which particular HERV polymorphisms may play a role in development.

Meta-analysis on the effect of dopexamine on in-hospital mortality

The objective of the study was to determine whether dopexamine alters in-hospital mortality. The following databases were searched, Embase (1974-July 2007), Medline (1950-July 2007), CINAHL, PubMed and Cochrane Clinical Register of Controlled Trials (CENTRAL). Two reviewers independently checked the quality of the studies and extracted data. Six randomised controlled trials totalling 935 patients were included. Mortality was not significantly different with dopexamine treatment (relative risk 0.75, 95% confidence interval 0.48-1.18, p = 0.22). In conclusion, dopexamine does not improve in-hospital mortality in patients undergoing major abdominal surgery and in the critically ill.

Comparison of Antigenic Regions Identified on IgG1Fc Using Bioinformatics vs Pepscan Analysis

Epitope mapping allowed the location of antigenic determinants on a protein macromolecule to be identified. In particular, pepscan techniques that utilize a series of overlapping peptides, help detect key amino acid residues that are important in antibody recognition and binding. In a previous study, we employed 15-mer peptides spanning the entire length of IgG1Fc to ascertain successfully the target epitopes of isotypic/allotypic monoclonal reagents.

As an extension to this work we have used these peptides to evaluate the location of epitope targets of five IgM rheumatoid factor antibodies (RFAbs). Overall, 2 antibodies, RFAb TS2 and TS1, detected a similar epitope within the CH3 domain (360-KNQVSLTCLVKGFYP-374), whilst 1 (RFAb SJ1) recognised an epitope in the CH2 domain (294-EQYNSTYRVVSVLTV-308). In contrast, 2 RFAbs, PRSJ2 and PRTS1 detected four and five epitopes respectively within the Fc region. RFAb PRSJ2 recognised epitopes detected by RFAB TS2 and TS1 but also further epitopes in the CH2 domain (256-TPEVTCVVVDVSHED-270) and CH3 domain (418-QQGNVFSCSVMHEAL-432). Similarly, RFAb PRTS1 detected all four epitopes plus a fifth in the CH3 domain (382-ESNGQPENNYKTTPP-396). In essence there was a consensus of target epitopes identified by these rheumatoid factor antibodies. Interestingly, two epitopes (256–270, CH2 domain and 360–374, CH3 domain) were novel in that they had not been identified in previous pepscan studies. The other epitopes recognised, either overlapped or were immediately adjacent to previous epitopes detected by poly/monoclonal rheumatoid factor antibodies.

Molecular modelling (PCImdad) of IgG1Fc showed that all five epitopes were exposed and surface accessible for antibody interaction. In addition, a bioinformatics analysis of the Fc region using ExPASy was employed to identify key antigenic determinants. This ‘in silico’ approach may provide a means of determining key regions without the need to develop overlapping peptides spanning the entire length of a macromolecule.

Phytoestrogens: perpetrators or protectors?

Phytoestrogens are estrogen-like substances produced by plants that account for some of the constituents present in vegetation that may be responsible for the health benefits of a diet rich in fruit and vegetables. Phytoestrogens have a plethora of different actions that they are capable of exerting on cellular metabolism. This review will focus on some of the major non-estrogen receptor-mediated cellular effects used by phytoestrogens and will draw attention to the fact that while they may have a number of beneficial effects, particularly in offering a protective effect against some hormone-dependent cancers, such as breast and prostate cancer, they may also have possible unfavorable effects by interfering with the functioning of normal cellular activities such as receptor-mediated signal transduction and DNA replication, as well as being genotoxic, mutagenic and promoting the proliferation of some cancer cells.

Does an apple a day keep the doctor away because a phytoestrogen a day keeps the virus at bay? A review of the anti-viral properties of phytoestrogens

From dengue to herpes and influenza to AIDS, the phytoestrogens that are present in many fruits and vegetables have been shown to exert anti-viral properties. Here we review the various different anti-viral mechanisms employed by phytoestrogens.

The potential role of human endogenous retrovirus K10 in the pathogenesis of rheumatoid arthritis: a preliminary study

OBJECTIVE

To examine whether human endogenous retrovirus K10 is associated with autoimmune rheumatic disease.

DESIGN

A novel multiplex reverse transcription polymerase chain reaction (RT-PCR) system was developed to investigate HERV-K10 mRNA expression in patients with rheumatoid arthritis.

METHODS

40 patients with rheumatoid arthritis, 17 with osteoarthritis, and 27 healthy individuals were recruited and total RNA was extracted from peripheral blood mononuclear cells (PBMCs) and analysed using multiplex RT-PCR for the level of HERV-K10 gag mRNA expression. Southern blot and DNA sequencing confirmed the authenticity of the PCR products.

RESULTS

Using the histidyl tRNA synthetase (HtRNAS) gene as a housekeeping gene in the optimised multiplex RT-PCR, a significantly higher level of HERV-K10 gag mRNA expression was found in rheumatoid arthritis than in osteoarthritis (p = 0.01) or in the healthy controls (p = 0.02).

CONCLUSION

There is enhanced mRNA expression of the HERV-K10 gag region in rheumatoid arthritis compared with osteoarthritis or healthy controls. This could contribute to the pathogenesis of rheumatoid arthritis.

Characterization of Anti-Myosin Monoclonal Antibodies

The characterization of monoclonal antibodies (MAbs) with regard to reactivity and specificity is important for the successful application as a molecular probe and/or diagnostic reagent. Furthermore, it is recognized that some monoclonal reagents perform well in some assay systems but not others. In this study, the reactivity profiles of two anti-myosin MAbs (H1 and DH2, raised against human cardiac myosin) were evaluated in enzyme-linked immunosorbent assay (ELISA), slot-blotting, and immunocytochemistry. Both antibodies performed well in slot-blotting against myosin heavy chain preparations from cardiac and skeletal muscle and from non-human sources. In general, MAb H1 demonstrated strong to moderate reactivity in all assay systems, whilst MAb DH2 faired poorly in ELISA. MAb H1 also showed reactivity to synthetic peptides of myosin, one of which possessed a motif (ERRDA, single amino acid code) that was found in other human and nonhuman myosin protein sequences that could explain its cross-reactive profile. Intriguingly, this motif was found on viral and other pathogenic agents associated with myocarditis. Hence, it is speculated that this region could give some credence to the mechanism of molecular mimicry associated with some cardiac diseases. Overall, MAb H1 may serve as a useful probe of myosin structure.

Longitudinal Modeling of Adiposity in Periadolescent Greek Schoolchildren

PURPOSE

Obesity has an etiology that is multidimensional in nature. Given the dearth of longitudinal data, we examined changes in adipose tissue (Ad) in relation to physical activity levels (PA), aerobic fitness (AF), and energy intake (EI) in Greek schoolchildren, as they progressed from age 12 to 14 yr.

METHODS

This was a 2-yr and three-time-point (TP) study. Participants (N=210 (TP1); =204 (TP2); =198 (TP3)) were assessed for anthropometry, maturity status, Ad, PA, AF, and EI. Mean values were used for exploratory analyses, whereas two generalized estimating equations (GEE) models examined for longitudinal associations between the studied parameters. The first (GEE1) aimed to extract inherent associations between the dependent (Ad) and independent (PA, AF, EI) variables for the entire study period. For further evidence of association, the second analysis (GEE2) used the independent variables at TP1 and TP2 to predict the dependent variables at TP3.

RESULTS

Levels of Ad in boys decreased significantly (P<0.05) from TP1 to TP3, whereas the same variable demonstrated a nonsignificant increase (P>0.05) in girls. GEE1 revealed that longitudinal changes in Ad were significantly associated only with PA (beta=-0.16; P<0.001) and AF (beta=-0.09; P<0.05) for all schoolchildren. Similarly, GEE2 revealed that the main factors (at TP1 and TP2) predicting the development of Ad (at TP3) were PA (beta=-0.14; P<0.001) followed by AF (beta=-0.10; P<0.05).

CONCLUSION

With respect to data presented, we established that longitudinal changes in Ad are mainly accompanied by changes in PA and, to a lesser extent, AF levels.

The prevalence and clinical significance of autoantibodies to plasminogen activator inhibitor 1 in systemic lupus erythematosus

We have recently described the novel autoantigen plasminogen activator inhibitor (PAI-1) in systemic lupus erythematosus (SLE). The aim of this study was to determine the prevalence and clinical significance of anti-PAI-1 autoantibodies in patients with SLE. Autoantibodies to recombinant PAI-1 were measured in retrospective sera of 48 lupus patients by immunoassay in order to assess their clinical significance. This showed that 71% of sera from 48 lupus patients had significantly elevated anti-PAI-1 autoantibodies as compared with normal control subjects (P < 0.0001). There was a weak but significant (P < 0.043) correlation with anti-dsDNA autoantibodies. In longitudinal studies, autoantibodies against PAI-1 correlated with clinical parameters measured by the BILAG disease activity index including global clinical score. Our study demonstrates the high frequency of novel autoantibodies to PAI-1 in patients with lupus. The serial clinical correlations with anti-PAI-1 autoantibodies also support the hypothesis that these autoantibodies may play a pathogenic role in lupus.

Human endogenous retroviruses: transposable elements with potential?

Human endogenous retroviruses (HERVs) are a significant component of a wider family of retroelements that constitute part of the human genome. These viruses, perhaps representative of previous exogenous retroviral infection, have been integrated and passed through successive generations within the germ line. The retention of HERVs and isolated elements, such as long-terminal repeats, could have the potential to harm. In this review we describe HERVs within the context of the family of known transposable elements and survey these viruses in terms of superantigens and molecular mimics. It is entirely possible that these mechanisms provide the potential for undesired immune responses.

Demystified...recombinant antibodies

Recombinant antibodies are important tools for biomedical research and are increasingly being used as clinical diagnostic/therapeutic reagents. In this article, a background to humanized antibodies is given, together with details of the generation of antibody fragments--for example, single chain Fv fragments. Phage antibody fragments are fast becoming popular and can be generated by simple established methods of affinity enrichment from libraries derived from immune cells. Phage display methodology can also be used for the affinity enrichment of existing antibody fragments to provide a reagent with a higher affinity. Here, phage antibodies are demystified to provide a greater understanding of the potential of these reagents and to engage clinicians and biomedical scientists alike to think about potential applications in pathology and clinical settings.

A novel multiplex RT-PCR system detects human endogenous retrovirus-K in breast cancer

Human endogenous retrovirus HERV-K like-sequences have been implicated in certain cancers. We developed a novel multiplex RT-PCR system for HERV-K that yielded a 533 bp product together with a smaller sized product (319 bp) of the house keeping gene, histidyl tRNA synthetase (HtRNAS). The latter spanned an intron that also served to validate target cDNA. PCR amplicons of HERV-K and HtRNAS were visualised using a gel documentation system and the pixel intensity used to derive semi-quantitative levels of viral expression. Our data showed that HERV-K10 was significantly elevated in MCF-7 cells treated with estrogen. Interestingly, HERV-K expression was higher in MCF-7 cells selected with adriamycin. RT-PCR combined with Southern blotting also detected HERV-K from breast cancer tissue using laser capture microscopy. This study highlights the presence of HERV-K in the breast cancer cell lines MCF-7 and MCF-7 ADR and confirms HERV-K10 transcripts in the cell line T47D. We believe this study to be a novel approach in determining levels of HERV-K expression and for detecting this virus in cancer cell lines and tissues.

Lipopolysaccharide induces nitric oxide synthase expression and platelet-activating factor increases nitric oxide production in human fetal membranes in culture

BACKGROUND

Platelet-activating factor and nitric oxide may be involved in the initiation of human labour as inflammatory mediators. The aim of this study was to test whether platelet-activating factor and lipopolysaccharide were able to induce nitric oxide synthase expression and stimulate the production of nitric oxide in human fetal membrane explants in culture.

METHODS

Fetal membranes were collected from Caesarean sections at term. RNA was extracted from membranes and subjected to a qualitative RT-PCR to assess the baseline expression of iNOS. Discs of fetal membranes were cultured for 24 hours in the presence of platelet-activating factor at a dose range of 0.1 nanomolar--1 micomolar or 1 microgram/ml lipopolysaccharide. Nitric oxide production was measured via nitrite ions in the culture medium and mRNA for iNOS was detected by RT-PCR.

RESULTS

Culturing the membrane discs in medium containing serum induced nitric oxide synthase expression and platelet-activating factor significantly stimulated the production of nitric oxide under these conditions. When cultured without serum inducible nitric oxide synthase expression was induced by lipopolysaccharide, but not by platelet-activating factor.

CONCLUSION

Platelet-activating factor may have a role in the initiation of labour, at term or preterm, via the increased local production of nitric oxide as an inflammatory mediator. In this model of intrauterine infection, lipopolysaccharide was found to induce iNOS expression by fetal membranes, and this mechanism could be involved in preterm labour.

Characterisation of epitopes of pan-IgG/anti-G3m(u) and anti-Fc monoclonal antibodies

The characterisation of monoclonal antibodies (MAbs) and their epitopes is important prior to their application as molecular probes. In this study, Western blotting using IgG1 Fc and pFc' fragments was employed to screen seven MAbs before pepscan analysis to determine their reactivity to potentially linear epitopes. MAbs PNF69C, PNF110A, X1A11 and MAbs WC2, G7C, JD312, 1A1 detected epitopes within the C(H)3 and C(H)2 domains, respectively. However, only four MAbs showed pepscan profiles that highlighted likely target residues. In particular, MAbs PNF69C and PNF110A that have previously been characterised with pan-IgG and anti-G3m(u) specificity, detected the peptide motif 338-KAKGQPR-344 which was located within the N-terminal region of the C(H)3 domain. Furthermore the majority of residues were present in all four IgG subclasses. Consequently the peptide identified was consistent with the pan-IgG nature of these antibodies. By using PCImdad, a molecular display programme, this sequence was visualised as surface accessible, located in the C(H)2/C(H)3 inter-domain region and proximal to the residue arginine(435). It is speculated that this residue may be important for phenotypic expression of G3m(u) and specificity of these reagents. Pepscan analysis of MAbs G7C and JD312 (both pan-IgG) highlighted the core peptide sequence 290-KPREE-294, which was present in the C(H)2 domain and was common to all four IgG subclasses. PCImdad also showed this region to be highly accessible and was consistent with previous bioinformatic and autoimmune analysis of IgG. Overall these MAbs may serve as useful anti-IgG or anti-G3m(u) reagents and probes of immunoglobulin structure.

Demystified. Human endogenous retroviruses

Human endogenous retroviruses (HERVs) are a family of viruses within our genome with similarities to present day exogenous retroviruses. HERVs have been inherited by successive generations and it is possible that some have conferred biological benefits. However, several HERVs have been implicated in certain cancers and autoimmune diseases. This article demystifies these retroviruses by providing an insight into HERVs, their means of classification, and a synopsis of HERVs implicated in cancer and autoimmunity. Furthermore, the biological roles of HERVs are explored.

Reactivity and isotype profiling of monoclonal antibodies using multiple antigenic peptides

The characterisation of monoclonal antibodies (MAbs) is essential for the development of assay systems particularly where antigens have been developed using synthetic peptides. Indeed some peptide-carrier conjugates fail to induce immune responses and may not generate antibodies that bind to native protein. As an alternative to peptide-carrier conjugates, multiple antigenic peptides (MAPs) have been used for immunization strategies, but with little regard to the characteristics of the MAbs produced. In this study, we used 3 MAPs of Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1) to immunise BALB/c mice. Overall, the polyclonal antibody responses from tail bleeds showed that MAPs evoked B-cell responses. However, on screening 144 hybridomas, 24 MAb supernatants exhibited weak to moderate reactivity in enzyme-linked immunosorbant assay (ELISA) and against cell cytospin preparations (B95.8 and AG876 LCL), respectively. Isotype profiling of hybridoma supernatants also showed that 11 out of 24 were IgM. Further characterization of 6 MAbs in Western blotting showed reactivity to recombinant LMP1 and only one MAb (B28D) showed weak reactivity to the malignant cells (Hodgkin/Reed-Sternberg; HRS cells) of an EBV+ Hodgkin's lymphoma using paraffin-embedded tissue. It is probable that these MAPs failed to augment T-cell help and contributed to the production of low affinity (IgM) antibodies. These observations may be of importance to future immunization strategies, where MAPs are used in the production of monoclonal reagents.

Acid phosphatases

Acid phosphatases (APs) are a family of enzymes that are widespread in nature, and can be found in many animal and plant species. Mystery surrounds the precise functional role of these molecular facilitators, despite much research. Yet, paradoxically, human APs have had considerable impact as tools of clinical investigation and intervention. One particular example is tartrate resistant acid phosphatase, which is detected in the serum in raised amounts accompanying pathological bone resorption. This article seeks to explore the identity and diversity of APs, and to demonstrate the relation between APs, human disease, and clinical diagnosis.

Generation and characterization of monoclonal antibodies to the neural crest

The generation of monoclonal antibodies (MAbs) specific for quail neural crest may provide valuable tools for studying the differentiation of embryonic precursor cells. Unfortunately, relatively few antibodies are available because of the difficulty in obtaining sufficient cells for in vivo immunization strategies. We have overcome this problem by using intrasplenic immunization with formaldehyde-fixed cells harvested from neural crest cultures. In addition, booster injections of cultured whole-embryo cells were administered intraperitoneally. Following two fusions, a total of 18 hybridomas were generated with antibody reactivity to the cytoplasm of neural crest cells. Furthermore, 32 were reactive against both somite (a noncrest mesodermal control) and crest cultures, whilst 15 were not reactive. Out of those hybridomas reactive with neural crest, six designated 160D, 164D, OE, 12E, 120E and 124E were further characterized. Interestingly MAb supernatants OE, 12E, 120E, and 124E exhibited reactivity against some but not all neural crest cells suggesting that they might recognise subpopulations. Immunoglobulin isotyping of supernatants revealed that 4 (160D, 164D, OE, and 120E) were IgM and 2 (12E and 124E) were IgG(2b). On assessing their reactivity against human tissue sections, all six hybridoma supernatants cross-reacted with neuroendocrine cells within appendix, colon and rectum. These MAbs could provide novel reagents for the understanding of neural crest development.

Expression of the matrix metalloproteinase 9 in Hodgkin's disease is independent of EBV status

BACKGROUND

In vitro the Epstein-Barr virus (EBV) encoded latent membrane protein 1 (LMP-1) has been shown to upregulate expression of matrix metalloproteinase 9 (MMP-9), a member of a family of zinc dependent endopeptidases that is believed to facilitate tumour invasion and metastasis by degradation of the extracellular matrix.

AIM

To test whether the expression of MMP-9 in Hodgkin's disease correlates with EBV status and survival and to investigate whether LMP-1 expression affects MMP-9 concentrations in the Hodgkin's disease cell line, L428.

METHODS

MMP-9 expression was measured by means of immunohistochemistry in a series of Hodgkin's disease tumours and this expression was correlated with EBV status and survival. The influence of LMP-1 on MMP-9 expression was also investigated in the Hodgkin's disease cell line, L428.

RESULTS

MMP-9 expression was demonstrated in the malignant Hodgkin and Reed-Sternberg cells of all (n = 86) formalin fixed, paraffin wax embedded Hodgkin's disease tumours examined. Although the intensity of MMP-9 immunostaining varied between cases, there was no correlation between MMP-9 expression and EBV status or survival. MMP-9 expression was also detected in a variety of non-malignant cells, including fibroblasts. MMP-9 was detected by zymography in the L428 and KMH2 Hodgkin's disease cell lines, whereas low or undetectable amounts of MMP-9 were found in the L591 Hodgkin's disease cell line. Induction of LMP-1 expression in the Hodgkin's disease cell line L428 did not result in a detectable increase in the values of MMP-9 as measured by zymography.

CONCLUSIONS

These results demonstrate that MMP-9 is consistently expressed by the Hodgkin and Reed-Sternberg cells of Hodgkin's disease tumours and by the Hodgkin's disease cell lines, L428 and KMH2. However, this expression does not appear to be related either to LMP-1 values or to survival.

Monoclonal antibodies

Monoclonal antibodies are essential tools for many molecular immunology investigations. In particular, when used in combination with techniques such as epitope mapping and molecular modelling, monoclonal antibodies enable the antigenic profiling and visualisation of macromolecular surfaces. In addition, monoclonal antibodies have become key components in a vast array of clinical laboratory diagnostic tests. Their wide application in detecting and identifying serum analytes, cell markers, and pathogenic agents has largely arisen through the exquisite specificity of these unique reagents. Furthermore, the continuous culture of hybridoma cells that produce these antibodies offers the potential of an unlimited supply of reagent. In essence, when compared with the rather limited supply of polyclonal antibody reagents, the feature of a continuous supply enables the standardisation of both the reagent and the assay technique. Clearly, polyclonal and monoclonal antibodies have their advantages and disadvantages in terms of generation, cost, and overall applications. Ultimately, monoclonal antibodies are only produced when necessary because their production is time consuming and frustrating, although greatly rewarding (at least most of the time!). This is especially apparent when a monoclonal antibody can be applied successfully in a routine pathology laboratory or can aid in the clinical diagnosis and treatment of patients. In this article, the generation and application of monoclonal antibodies are demystified to enable greater understanding and hopefully formulate novel ideas for clinicians and scientists alike.

Reactivity and assay restriction profiles of monoclonal and polyclonal antibodies to acid phosphatases: a preliminary study

The development of secure diagnostic immunoassays requires, among others, rigorous characterisation of potential antibody reagents. The reactivity profiles of seven antibodies (six monoclonal [MAb] and one polyclonal [PAb]) with putative specificity for tartrate-resistant acid phosphatase (TRAP) and/or osteoclasts were evaluated in enzyme-linked immunosorbent assay (ELISA) and/or immunocytochemistry. MAbs 2H1, 4E6 and 5Cl demonstrated assay restriction: exhibiting reactivity only in ELISA. The remaining three MAbs (G211D, G312G and V35B) and the PAb 8023 recognised recombinant TRAP (rTRAP) in ELISA and native acid phosphatases in selected tissues and cell lines. The latter were cytochemically assessed for both tartrate-sensitive acid phosphatase (TSAP) and TRAP. V35B showed reactivity against the monocytic leukaemia cell line U937 and guinea pig kidney tissue (both TSAP+ and TRAP+) and ECV304 (TSAP+) cells. Interestingly, the reactivity of MAb G211D co-localised with TRAP activity in the membrane of osteoclasts but also detected cytoplasmic components in U937 cells and human embryonic lung fibroblasts (TRAP+ and TRAP+). G211D exhibited immunoreactivity against placental trophoblasts (positive for total AP). Intriguingly, MAbs 2H1, 4E6, 5Cl and PAb 8023 cross-reacted with potato acid phosphatase in ELISA, suggesting reactivity to conformationally similar epitopes. Thus, some of these reagents could be used in the development of standardised diagnostic immunoassays or as drug-targeting agents for conditions in which the pathological process involves bone resorption, the MAbs G211D, 2H1, 4E6, 5Cl and PAb 8023 being useful in ELISA but not immunocytochemical detection of TRAP.

Effect of Epstein-Barr virus infection on response to chemotherapy and survival in Hodgkin's disease

We have analyzed paraffin sections from 190 patients with histologically confirmed Hodgkin's disease (HD) for the presence of Epstein-Barr virus (EBV) using in situ hybridization to detect the EBV-encoded Epstein-Barr virus early RNAs (EBERs) and immunohistochemistry to identify latent membrane protein-1 (LMP1) expression. EBV was present in the tumor cells in 51 HD cases (27%) and was mainly confined to the mixed cellularity and nodular sclerosis subtypes. There was no difference between EBV-positive and EBV-negative HD patients with regard to age, clinical stage, presentation, and the number of alternating chemotherapy cycles of ChIVPP and PABIOE received. The complete remission rate after study chemotherapy was 80% in EBV-positive patients versus 69% in EBV-negative patients (P =.05). The 2-year failure-free survival rate was significantly better for EBV-positive patients when compared with the EBV-negative HD group (P =.02). Although 2-year and 5-year overall survival rates were better for EBV-positive HD patients, the differences were not statistically significant (P =.18 and P =.40, respectively). In conclusion, the results confirm the favorable prognostic value of EBV in the tumor cells of HD patients and suggest important differences in response to chemotherapy between EBV-positive and EBV-negative patients.

Molecular investigations implicate human endogenous retroviruses as mediators of anti-retroviral antibodies in autoimmune rheumatic disease

Polymerase chain reaction using specific primers, failed to detect HTLV-I amplicons in patients with rheumatic diseases previously shown to possess antibodies to retroviral products. However, by employing broad spectrum oligonucleotide primers, 135 bp amplicons were generated from peripheral blood mononuclear cells and synovial fluid cells. Subsequent cloning and DNA sequencing revealed homology to a number of exogenous and human endogenous retroviruses (HERVs). Furthermore, in combining the presence of type B and C related endogenous retroviruses, a significant association (p=0.014) was apparent for chronic autoimmune rheumatic diseases as compared to controls. Reverse transcription polymerase chain reaction of RNA derived from patients, healthy controls and cell lines (U937, BJAB, human endothelial lung fibroblasts) demonstrated ubiquitous expression of HERV-K10 and RTVL-H2. Furthermore messenger RNA expression of HERV-K10 was enhanced in fibroblasts infected with human cytomegalovirus. It is plausible that subsequent production of HERV peptides could explain the presence of anti-retroviral antibodies in cohorts of patients with autoimmune rheumatic diseases.

Demystified ... the polymerase chain reaction

Since its initial description over twenty years ago the PCR has become one of the most valuable and flexible tools available to biomedical research. Subsequently, refinements and modifications to the basic approach, many of which have been described in this review, have enabled the application of the PCR to many areas of diagnostic medicine and have ensured its rapid acceptance as a routine test in many pathology disciplines. The growing importance of molecular approaches to the diagnosis of disease, particularly in histopathology, will continue to secure an ever expanding role for the PCR in diagnostic pathology.

A polymerase chain reaction to detect a spliced late transcript of human cytomegalovirus in the blood of bone marrow transplant recipients

A reverse transcription (RT) nested polymerase chain reaction (PCR) procedure is described for detecting RNA to a spliced late gene (SLG) of human cytomegalovirus (CMV), the product of which (175 bp) is easily differentiated in agarose gels from the product when the target is unspliced viral RNA or DNA (258 bp). The SLG-RT-PCR has been compared against a semi-quantitative PCR for CMV DNA in buffy-coat specimens collected weekly after bone marrow transplantation from 3 patients and against the results of culturing these specimens for CMV both by conventional virus isolation, based on the detection of cytopathic effect, and by the early detection of infected cells by staining with virus-specific monoclonal antibodies. The detection of CMV RNA by SLG-RT-PCR correlated well with the detection of infective virus but only when the results of both culture methods were combined, in that neither culture method alone was as sensitive as the SLG-RT-PCR. The presence of SLG RNA in the circulation is of value as a marker of active CMV infection.

Utilization of activated U937 monocytic cells as a model to evaluate biocompatibility and biodegradation of synthetic calcium phosphate

The use of calcium phosphate biomaterials as a bone substitute necessitates the use of normative biocompatibility and biodegradation techniques which must be fast, simple and reproducible. In the present study, we have developed an in vitro model to study and to compare different calcium phosphate ceramics. After activation with 1,25-dihydroxy-vitamin D3 and phorbol 12,13-dibutyrate, the monoblastic U937 cells became multinucleated, expressed tartrate-resistant acid phosphatase and several markers of monocyte/macrophage differentiation. Activated U937 cells did not express the vitronectin receptor (VNR) (as revealed using monoclonal antibodies 23C6 or 13C2) but around 25% of the cells were strongly reactive with 211D, a novel monoclonal antibody that recognizes an osteoclast-specific membrane antigenic determinant. These cells remain active/viable with hydroxyapatite (HA) or beta-tricalcium phosphate (beta-TCP) ceramics. In conclusion, activated U937 cells are good candidates to use in a normative in vitro method to evaluate new biomaterials.

Generation and characterization of putative monoclonal and polyclonal antibodies against tartrate-resistant acid phosphatase

The generation of monoclonal antibodies (MAbs) specific for tartrate-resistant acid phosphatase (TRAP) may aid development of a serological immunoassay for this marker of bone resorption. The lack of MAbs to TRAP largely reflects the difficulty in obtaining sufficient antigen for in vivo immunization strategies. We have circumvented this problem by using in vitro immunization, requiring a small amount of TRAP isolated from osteoclastoma tumor. Two MAbs designated 312D and 310A were generated that exhibited weak anti-TRAP activity in enzyme-linked immunosorbent assay and immunocytochemistry. A polyclonal antibody to TRAP (Ab8023) was also raised in rabbit, using synthetic peptide. Ab8023 and MAbs 310A and 312D exhibited no activity against TRAP in dot-blotting experiments. Further characterization in enzyme-liked immunosorbent assay showed that Ab8023 was remarkably specific for TRAP whereas MAb 312D cross-reacted with another metalloenzyme, human prostatic acid phosphatase.

Polymerase chain reaction fails to incriminate exogenous retroviruses HTLV-I and HIV-1 in rheumatological diseases although a minority of sera cross react with retroviral antigens

OBJECTIVES

To investigate the presence of antibodies to HTLV and HIV retroviral antigens in the rheumatological diseases rheumatoid arthritis (RA), polymyositis/dermatomyositis (PM/DM), primary Sjögren's syndrome (pSS), and systemic lupus erythematosus (SLE), and to use polymerase chain reaction (PCR) to seek these exogenous retroviruses in proviral form in cellular DNA from these patients.

METHODS

Thirty patients with active RA, 13 with PM, 14 with pSS and five with SLE were recruited and their sera tested for antibodies to HTLV-I in enzyme linked immunosorbent assay (ELISA) and Western blot analysis. Seropositivity to HIV-1 was also sought. DNA was extracted from peripheral blood lymphocytes, synovial tissue and muscle biopsies and tested by polymerase chain reaction using consensus primers for HTLV-I and HIV-1.

RESULTS

In HTLV-I ELISA, nine rheumatological sera (4/30 RA, 3/13 PM/DM and 2/5 SLE patients) were considered positive; 14 from pSS patients and 30 from normal subjects were negative. In a control group which included osteoarthritis, Crohn's disease and bacterial endocarditis patients, only two of 80 proved positive in this system. Validation of these sera by Western blotting generally revealed weak reactivity against a variety of HTLV-I antigens. PCR of genomic DNA derived from patients' peripheral blood mononuclear cells did not reveal the presence of HTLV-I and HIV-1 target sequences.

CONCLUSIONS

This study shows that PCR precludes HTLV-I and HIV-1 infection as causative agents in these rheumatological diseases although a minority of patients possess antibodies that are weakly cross-reactive with retroviral antigens.

Characterisation of putative monoclonal anti-G3m(u) and anti-G3m(g) reagents and their antigenic determinants

Monoclonal antibodies (MAbs) against IgG3 allotypic markers were evaluated in haemagglutination inhibition and IgG3 capture ELISA. MAbs PNF69C and 200D1 exhibited G3m(u) and G3m(g) specificity respectively. In HAI target epitopes detected by MAbs were remarkably stable to physiochemical degradation. Western blotting revealed that MAb 200D1, bound to intact IgG3 heavy chain disease protein and not its pFc' fragment; a result consistent with the CH2 domain location of the G3m(g) allotope. The G3m(u) allotope is also located within this domain. Surprisingly anti-G3m(u) MAb PNF69C bound to the pFc' of IgG3-related protein, HW, and to the pFc' of IgG1-related protein, PR, in Western blot.

Production and characterization of new monoclonal antibodies to human osteoclasts

Two monoclonal antibodies raised against human osteoclastoma were found to show antiosteoclastic activity on frozen sections of tumor. Immunoreactivity was localized on the membrane surface. These antibodies exhibited no activity against tissue macrophages and human visceral tissue except kidney, where they stained tubules but not glomeruli. In addition, no activity was observed against rabbit or rat osteoclasts, suggesting that they might react with unique epitopes on human osteoclasts.

Assay restriction profiles of three monoclonal antibodies recognizing the G3m(u) allotype. Development of an allotype specific assay

Three monoclonal antibodies raised against a purified human IgG3 paraprotein were found to exhibit a restriction profile for IgG3/G3m(u) and pan-IgG specificity which was dependent on the assay system. When adapted to an IgG3 subclass capture ELISA, all three McAbs discriminated between paraproteins expressing G3m(u) and antithetical markers G3m(st). One of the antibodies (PNF69C) was selected and conditions were optimised for Gm typing purposes. Using this system G3m(u) could be detected on captured IgG3 derived from human sera. This system may prove useful in the elucidation of Gm allotype profiles.