Networks and plant disease management: concepts and applications

A network is a natural structure with which to describe many aspects of a plant pathosystem. The article seeks to set out in a nonmathematical way some of the network concepts that promise to be useful in managing plant disease. The field has been stimulated by developments designed to help understand and manage animal and human disease, and by technical infrastructures, such as the internet. It overlaps partly with landscape ecology. The study of networks has helped identify likely ways to reduce the flow of disease in traded plants, to find the best sites to monitor as warning sites for annually reinvading diseases, and to understand the fundamentals of how a pathogen spreads in different structures. A tension between the free flow of goods or species down communication channels and free flow of pathogens down the same pathways is highlighted.

Phytophthora ramorum - a pathogen linking network epidemiology, landscape pathology and conservation biogeography

Abstract

Phytophthora ramorum is a generalist plant pathogen that has been subject to a remarkable amount of research activity. One decade after its description, this oomycete now affects a wide range of hosts in both North America and Europe, both in the wild and in ornamental plant trade (e.g., Camellia, Rhododendron, Pieris). Research on the biology, epidemiology and management of P. ramorum has not only rapidly expanded, but has also become increasingly interdisciplinary. In this overview, three examples of interdisciplinary collaboration concerning P. ramorum are presented: (1) network epidemiology (the application of network theory to epidemiology), (2) landscape pathology (the use of landscape ecology tools in the study of regional outbreaks of tree pathogens) and (3) conservation biogeography (a biogeographical perspective in conservation biology). Building on these approaches, three-way collaboration among network epidemiologists, landscape pathologists and conservation biogeographers (as well as e.g., molecular biologists, social and climate change scientists) is now needed to improve our understanding and management of the P. ramorum emergency, and many other challenges to plant health worldwide.

Impact of different concentrations of human recombinant growth hormone on T lymphocytes

The aim of the present study is to evaluate the effects induced by increasing concentrations of human recombinant growth hormone on T lymphocytes. Ten healthy volunteers and twelve subjects with symptomatic allergies were enrolled in the study. Peripheral blood mononuclear cells and purified T lymphocytes were cultured in the presence of graded concentrations of growth hormone. Following appropriate in vitro stimulations, the proportion of apoptotic T cells, the percentage of activated T lymphocyte subpopulations, the phytohemagglutinin responsiveness and the Th2 response were assessed by flow cytometry analysis. Moreover, in order to evaluate the phosphoinositol-3-kinase signaling pathway involvement, cells were also analyzed after treatment with LY294002. The treatment with different concentrations of growth hormone did not influence the activation pattern of un-stimulated T lymphocytes. On the contrary, growth hormone was able to modify the CD38/HLA-DR co-expression of T cells activated with phytohemoagglutinin. A different response was observed when samples obtained from healthy donors and from subjects with symptomatic allergies were analysed. Moreover, growth hormone treatment was able to increase the Th2 response in the samples obtained from healthy donors only. The results of the present study strongly support the hypothesis that growth hormone administration may play an important role in conditions of impaired/activated immune systems. The observation that growth hormone administration at high doses may reverse its effects and that it may promote a Th2-oriented response have significant clinical implications when considering the use of this hormone for artificially enhancing the physical performances of healthy athletes.

Plant health challenges for a sustainable land use and rural economy

Abstract

Plant health is a key condition for a sustainable land use and rural economy. Drawing on a Rural Economy and Land Use (RELU)-funded project on the growing risk of plant diseases in the UK, current and future challenges to plant health are discussed. It is well recognized that farmers have an important role in shaping plant health policies at a time of major structural changes in agricultural industries. However, the role of consumers has also much potential to improve sustainability of plant disease management options. The phytosanitary legislation is catching up with the many recent developments in plant health, but needs to be integrated with policies aimed at achieving animal and human health. Interdisciplinary approaches in research on plant health, as well as an increasing involvement of stakeholders in the management of plant epidemics, are to be welcomed. Plant diseases also influence (and are influenced by) land use and environmental regulations in general. Climate change is likely to increase the frequency and magnitude of new plant disease outbreaks, particularly when combined with globalization of trade, intensification of land use and structural evolution of the agricultural sector. To tackle the many challenges to plant health, it is mandatory to ensure long-term funding for interdisciplinary plant health research and management.

A numerical study of combined use of two biocontrol agents with different biocontrol mechanisms in controlling foliar pathogens

Effective use of biocontrol agents is an important component of sustainable agriculture. A previous numerical study of a generic model showed that biocontrol efficacy was greatest for a single biocontrol agent (BCA) combining competition with mycoparasitism or antibiosis. This study uses the same mathematical model to investigate whether the biocontrol efficacy of combined use of two BCAs with different biocontrol mechanisms is greater than that of a single BCA with either or both of the two mechanisms, assuming that two BCAs occupy the same host tissue as the pathogen. Within the parameter values considered, a BCA with two biocontrol mechanisms always outperformed the combined use of two BCAs with a single but different biocontrol mechanism. Similarly, combined use of two BCAs with a single but different biocontrol mechanism is shown to be far less effective than that of a single BCA with both mechanisms. Disease suppression from combined use of two BCAs was very similar to that achieved by the more efficacious one. As expected, a higher BCA introduction rate led to increased disease suppression. Incorporation of interactions between two BCAs did not greatly affect the disease dynamics except when a mycoparasitic and, to a lesser extent, an antibiotic-producing BCA was involved. Increasing the competitiveness of a mycoparasitic BCA over a BCA whose biocontrol mechanism is either competition or antibiosis may lead to improved biocontrol initially and reduced fluctuations in disease dynamics. The present study suggests that, under the model assumptions, combined use of two BCAs with different biocontrol mechanisms in most cases only results in control efficacies similar to using the more efficacious one alone. These predictions are consistent with published experimental results, suggesting that combined use of BCAs should not be recommended without clear understanding of their main biocontrol mechanisms and relative competitiveness, and experimental evaluation.

Combined use of biocontrol agents to manage plant diseases in theory and practice

Effective use of biological control agents (BCAs) is a potentially important component of sustainable agriculture. Recently, there has been an increasing interest among researchers in using combinations of BCAs to exploit potential synergistic effects among them. The methodology for investigating such synergistic effects was reviewed first and published results were then assessed for available evidence for synergy. Correct formulation of hypotheses based on the theoretical definition of independence (Bliss independence or Loewe additivity) and the subsequent and statistical testing for the independence-synergistic-antagonistic interactions have rarely been carried out thus far in studies on biocontrol of plant diseases. Thus, caution must be taken when interpreting reported "synergistic" effects without assessing the original publications. Recent theoretical modeling work suggested that disease suppression from combined use of two BCAs was, in general, very similar to that achieved by the more efficacious one, indicating no synergistic but more likely antagonistic interactions. Only in 2% of the total 465 published treatments was there evidence for synergistic effects among BCAs. In the majority of the cases, antagonistic interactions among BCAs were indicated. Thus, both theoretical and experimental studies suggest that, in combined use of BCAs, antagonistic interactions among BCAs are more likely to occur than synergistic interactions. Several research strategies, including formulation of synergy hypotheses in relation to biocontrol mechanisms, are outlined to exploit microbial mixtures for uses in biocontrol of plant diseases.

WITHDRAWN: Proteinase 3 (PR3) gene is highly expressed in CBF leukemias and codes for a protein with abnormal nuclear localization that confers drug sensitivity

Core-binding factor (CBF) leukemias are characterized by a high degree of sensitivity to high-dose cytarabine (ARA-C) treatment and by a relatively favorable prognosis compared with most other forms of adult acute myeloid leukemia (AML). The molecular basis of the response to chemotherapy is still being analyzed. The proteinase 3 (PR3) gene codes for a serine protease with a broad spectrum of proteolytic activity. PR3 is involved in the control of proliferation of myeloid leukemia cells, and when it is abnormally expressed, it confers factor-independent growth to hematopoietic cells. In this study, we analyzed the expression levels of PR3 in 113 AML patients. PR3 is highly expressed in AML, mainly in CBF leukemias in which PR3 is not only expressed, but also abnormally localized within the nuclear compartment. Nuclear PR3 results in cleavage of nuclear factor (NF)-kappaB p65 into an inactive p56 subunit lacking any transcriptional activity. The nuclear localization of PR3 is responsible for increased proliferation, apoptosis arrest and increased sensitivity to high-dose ARA-C. This study provides a new molecular mechanism that is responsible for NF-kappaB inactivation and increased sensitivity to chemotherapy in CBF leukemias.Leukemia advance online publication, 14 January 2010; doi:10.1038/leu.2009.207.

A biparametric flow cytometry analysis for the study of reticulocyte patterns of maturation

Automated haematological analysers still represent the gold standard for the study of reticulocyte maturation even if this technique is based on structural properties and staining affinity rather than on functional aspects. On the contrary, flow cytometry allows the simultaneous analysis of multiple cellular characteristics including functional features. Aim was to investigate whether simultaneous analysis of different reticulocyte parameters using flow cytometry may add functional information when considering their pattern of maturation. Thirty-nine healthy donors (H) and 31 haemodialysed patients on treatment with rHuEpo (HDT) were analysed. Reticulocyte counts and their stages of maturation were studied both with ADVIA 2120 and by flow cytometry. TO/CD71 scattergraph reticulocyte analysis designed a peculiar distribution which was similar among the same group of subjects (H or HDT), but different between H and HDT. distribution of the percentage of reticulocytes in low, medium and high boxes calculated by ADVIA 2120 did not show any difference between H and HDT groups, while the analysis using flow cytometry pointed out statistically significant differences between H and HDT groups in the three boxes where the TO+/CD71+ reticulocytes were localized. The present study suggests that TO/CD71 analysis was reproducible and could detect different pattern of maturation of a particular clinical setting.

A peculiar pattern of expression of the transferrin receptor (CD71) by reticulocytes in patients given recombinant human erythropoietin (rHuEPO): a novel marker for abuse in sport?

To overcome the limitation of the currently adopted direct method to detect recombinant Human Erythropoietin (rHuEpo) abuse in sport, indirect analysis of blood parameters are increasingly used as part of the anti-doping strategies. The aim of the present work is to identify whether immunophenotype modifications on erythroid cells may be indicative of previous rHuEPO administration. The study was conducted on dialyzed patients under treatment with rHuEPO (DPT). Dialyzed patients without rHuEPO therapy (DP) and volunteer donors (H) were used as controls. The analysis of erythroid cells immunophenotype, performed using a multiparametric flow cytometry technique, showed a peculiar pattern of CD71 expression following rHuEPO treatment. In particular CD71 showed an increased expression in mature and intermediate reticulocytes and a surprisingly decreased expression in immature reticulocytes. In conclusion, the analysis of reticulocyte maturation stages with TO/CD71 double staining may be considered as a valid alternative indirect method for the detection of rHuEPO abuse.

NF-kB inhibition as a strategy to enhance etoposide-induced apoptosis in K562 cell line

NF-kB is a transcription factor that mediates antiapoptotic signals in several cancer cell lines. Here we have demonstrated that the cytotoxic drug, Etoposide, activates NF-kB in K562, a chronic myeloid leukemia blast crisis cell line. Treatment with the NF-kB inhibitors MG-132, Bay11-7082, and Resveratrol impedes Etoposide-induced NF-kB activation, rendering K562 sensitive to Etoposide-induced apoptosis. Stable expression of mutant form of IkB-alpha, which retains NF-kB inactive in the cytoplasm of cells, confirmed the data obtained with molecular inhibitors. Both inhibitors and stable expression of SR-IkB are associated with down-modulation of the antiapoptotic protein Bcl-xL, suggesting that the survival pathway activated by Etoposide involves NF-kB-mediated Bcl-xL expression.

The NF-κB pathway blockade by the IKK inhibitor PS1145 can overcome Imatinib resistance

Imatinib represents at present the most attractive therapy for BCR-ABL positive leukemias, even though a percentage of CML patients develop resistance to this compound. For these resistant patients a therapeutic approach based on a combination of drugs is more likely to be effective. In the last years, constitutive NF-kappaB/Rel activity has been demonstrated in several hematological malignancies. As a result, NFkB/Rel-blocking approaches have been proposed as antineoplastic strategies. Furthermore, the identification of specific kinases within the NF-kappaB activation pathway offers a selective target to address tailored therapies. In the current study, we show that the IKK inhibitor PS1145 is able to inhibit the proliferation of CML cell lines and primary BM cells. Moreover, the addition of Imatinib increases the effects of PS1145 in resistant cell lines and BM cells from resistant patients, with a further increase of apoptosis and inhibition of proliferation and colony growth. Our data provide the rational for a new therapeutic approach, which combines Imatinib and the IKK inhibitor PS1145 in CML resistant patients.

Monoclonal antibody panels for acute leukemia and myelodysplastic syndrome diagnosis. Results of a co-operative quality control group

The need for standardization criteria and result reproducibility in immunophenotyping hematological diseases has increased along with their clinical importance. Our group "Policentric Study Group on Immunological Markers", is composed of 40 laboratories. Its aim, over recent years, has been to find a standardized way of immunophenotypic analysis applicable to various hematological diseases. The objective of this study is to contribute to the debate concerning standardization of monoclonal antibody panels and immunophenotypic analysis procedures in acute leukemia (AL) and myelodysplastic syndrome (MDS), with the following targets: to improve interlaboratory reproducibility of the immunophenotyping data, and interpretative results; to study, with improved feasibility, correlation between immunophenotype and clinical or biological findings on a large number of AL and MDS cases; to verify the utility of the proposed monoclonal antibody panels for proper AL and MDS classification, and to detect minimal residual disease. In the field of AL and MDS our experience is based on about 1800 and 700 cases respectively analyzed over the last five years. Starting from these experiences and data of the literature we have elaborated the proposed panels of monoclonal antibodies and the methods of analysis. We have suggested a standardized immunophenotypic approach to study AL and MDS. In particular our work has focused on the gating strategy. This aims at drawing a gate of analysis having high purity and recovery, and on the choice of monoclonal antibody combinations for multiparametric analysis, particularly the normal antigen expression on each step of lineage differentiation or their clinically relevant aberrant expressions. A standardized criteria has become a necessary starting point in any kind of analytical process. In the field of acute leukemias and myelodysplastic syndromes the work of this polycentric group has focused on the pre-analytical and analytical steps to be taken in cytometric evaluation of hematological malignancies. The results obtained may contribute to reaching intra and inter-laboratory reproducibility.

Analysis of microsatellite instability in chronic lymphoproliferative disorders

Microsatellite instability (MSI) represents one specific pattern of genomic instability and is one of the genetic lesions most frequently detected in human neoplasia. Although MSI has been found to be associated with a wide variety of solid cancers, its involvement in lymphoid malignancies is virtually unexplored. In this study, we have investigated the presence of MSI in chronic lymphoproliferative disorders by comparing the pattern of nine microsatellite repeats (two tetranucleotides, two trinucleotides, and five dinucleotides) on autologous germline and tumor DNA of 23 patients, including 17 with B-cell chronic lymphocytic leukemia/small lymphocytic lymphoma (B-CLL/SLL), four with hairy cell leukemia, one with lymphoplasmacytoid lymphoma, and one with T-cell chronic lymphocytic leukemia. All samples at diagnosis displayed a germline pattern of the microsatellites examined, thus suggesting that MSI is not involved in the pathogenesis of these lymphoproliferations. Also, no microsatellite alterations were observed in consecutive samples of B-CLL/SLL obtained from the same patient at various stages of the disease both before and after chemotherapy. Conversely, alterations in 3/9 microsatellite repeats were detected in one case of Richter's syndrome which had evolved from a pre-existent B-CLL/SLL phase. Overall, the low frequency of MSI among chronic lymphoproliferative disorders adds further weight to the common view that the mechanisms and patterns of genomic instability in lymphoid neoplasia differ markedly from those commonly observed in solid cancers.

Genetic analysis of chromosome 13 deletions in BCR/ABL negative chronic myeloproliferative disorders

Chromosomal deletions of band 13q14 occur recurrently in BCR/ABL negative chronic myeloproliferative disorders (CMPD), including myelosclerosis with myeloid metaplasia (MMM), polycythemia vera (PV), essential thrombocythemia (ET), juvenile chronic myeloid leukemia (JCML), and the so-called BCR/ABL- chronic myeloid leukemia (CML). The RBI tumor suppressor locus, mapping to 13q14, has long since been hypothesized as the important gene. In this report, we have determined the frequency of 13q14 deletions at the molecular level in a large panel of BCR/ABL- CMPD at different disease stages and performed a detailed genetic analysis of gross rearrangements/deletions and point mutations of the RBI gene in these disorders. Our data show that molecular deletions of 13q14 are detected in a relatively large fraction of BCR/ABL- CMPD (38%), that they appear to be more frequent in MMM than in other BCR/ABL- CMPD, and that they may be present at diagnosis or occur during blastic evolution of the neoplasia. The RBI gene displayed a germline configuration in all BCR/ABL- CMPD tested, suggesting that 13q14 deletions in these disorders affect a tumor suppressor locus distinct from RBI.

Itchy dermatitis from Gynaikothrips ficorum March in a family group

This study reports on the occurrence of an itchy dermatitis in all 4 adult members of a family, 2 men and 2 women, following infestation in the family environment with Gynaikothrips ficorum. The skin manifestations and the environmental study are described.

Efficacy of teicoplanin and imipenem on respiratory infections in high risk patients

The efficacy of teicoplanin and imipenem was assayed on microorganisms, mainly hospital opportunistic organisms, resistant to common therapy, isolated from bronchoaspirates of high risk hospitalized patients. Imipenem has shown remarkable activity against all isolated microorganisms with sensitivities ranging from 91.93% against Acinetobacter calcoaceticus to 75.86% against Pseudomonas sp. Teicoplanin has shown excellent activity against Staphylococcus aureus (sensitivity 83.66%).

[Neoplasms of the floor of the mouth. Case reports]

The authors study a group of 61 patients treated for floor of the mouth neoplasms at the Istituto di Oncologia di Torino. They confirm a high incidence of deaths in the first 2 years after treatment in patients T greater than 2 N+, and better survival in patients with stage I-II tumours. The survival does not tend to fall between 5 and 10 years after treatment.

[Carcinoma of the tonsil. Case contributions]

The authors study a group of 25 patients treated for tonsillar carcinomas mainly in stage IV at the Istituto di Oncologia di Torino. The most part of the deaths are in the first 2 years after treatment, mainly due to distant metastases; a good stabilization of survival follows, obtained by radiation therapy alone or associated with surgery and/or chemotherapy.

[Neoplasms of the tongue. An analysis of cases]

The authors study a group of 295 patients treated for tongue neoplasms at the Istituto di Oncologia di Torino. They point out the influence of many factors on survival particularly referring to tumour size, lymph nodes metastases and tumour stage at the time of first treatment.

[Carcinoma of the palate. Clinical cases]

The paper reports a series of 29 patients treated for advanced neoplasias of the palate at the Oncology Institute in Turin. The study confirms the proportional deterioration of the survival rate in correlation with the advanced stage of the carcinoma. The majority of deaths due to insufficient control occur during the second year following treatment but, after this period, the survival rate tends to stabilise around 40%.