Heat shock-induced enhanced susceptibility of barley to Bipolaris sorokiniana is associated with elevated ROS production and plant defense-related gene expression

● Heat stress alters plant defense responses to pathogens. A short-term heat shock (HS) promotes infections by biotrophic pathogens. However, little is known about how HS affects infection by hemibiotrophic pathogens like Bipolaris sorokiniana (teleomorph: Cochliobolus sativus) (BS). We assessed the effect of HS in BS-susceptible barley (Hordeum vulgare cv. Ingrid) by monitoring leaf spot symptoms, BS biomass, reactive oxygen species (ROS) and plant defense-related gene expression following pre-exposure to HS. ● For HS, barley plants were kept at 49 °C for 20 seconds. BS biomass was assessed by qPCR, ROS levels determined by histochemical staining, while gene expression assayed by RT-qPCR. ● HS suppressed defense responses of barley to BS, resulting in more severe necrotic symptoms and increased fungal biomass, as compared to untreated plants. HS-induced increased susceptibility was accompanied by significant increases in ROS (superoxide, hydrogen peroxide). Transient expression of plant defense-related antioxidant genes and a barley programmed cell death inhibitor (HvBI-1) was induced in response to HS. However, HS followed by BS infection caused further transient increases in expression of HvSOD and HvBI-1 correlating with enhanced susceptibility. Expression of the HvPR-1b gene encoding pathogenesis-related (PR) protein-1b increased several fold at 24 hours after BS infection, however, HS further increased transcript levels along with enhanced susceptibility. ● HS induces enhanced susceptibility of barley to BS, associated with elevated ROS levels and expression of plant defense-related genes encoding antioxidants, a cell death inhibitor and PR-1b. Our results may contribute to elucidating the influence of HS on barley defense responses to hemibiotrophic pathogens.

High avidity drives the interaction between the streptococcal C1 phage endolysin, PlyC, with the cell surface carbohydrates of Group A Streptococcus

Endolysin enzymes from bacteriophage cause bacterial lysis by degrading the peptidoglycan cell wall. The streptococcal C1 phage endolysin PlyC, is the most potent endolysin described to date and can rapidly lyse group A, C, and E streptococci. PlyC is known to bind the Group A streptococcal cell wall, but the specific molecular target or the binding site within PlyC remain uncharacterized. Here we report for the first time, that the polyrhamnose backbone of the Group A streptococcal cell wall is the binding target of PlyC. We have also characterized the putative rhamnose binding groove of PlyC and found four key residues that were critical to either the folding or the cell wall binding action of PlyC. Based on our results, we suggest that the interaction between PlyC and the cell wall may not be a high-affinity interaction as previously proposed, but rather a high avidity one, allowing for PlyC's remarkable lytic activity. Resistance to our current antibiotics is reaching crisis levels and there is an urgent need to develop the antibacterial agents with new modes of action. A detailed understanding of this potent endolysin may facilitate future developments of PlyC as a tool against the rise of antibiotic resistance.

Impact of HLA-DR Antigen Binding Cleft Rigidity on T Cell Recognition

The interaction between T cell receptor (TCR) and peptide (p)-Human Leukocyte Antigen (HLA) complexes is the critical first step in determining T cell responses. X-ray crystallographic studies of pHLA in TCR-bound and free states provide a structural perspective that can help understand T cell activation. These structures represent a static “snapshot”, yet the nature of pHLAs and their interactions with TCRs are highly dynamic. This has been demonstrated for HLA class I molecules with in silico techniques showing that some interactions, thought to stabilise pHLA-I, are only transient and prone to high flexibility. Here, we investigated the dynamics of HLA class II molecules by focusing on three allomorphs (HLA-DR1, -DR11 and -DR15) that are able to present the same epitope and activate CD4+ T cells. A single TCR (F24) has been shown to recognise all three HLA-DR molecules, albeit with different affinities. Using molecular dynamics and crystallographic ensemble refinement, we investigate the molecular basis of these different affinities and uncover hidden roles for HLA polymorphic residues. These polymorphisms were responsible for the widening of the antigen binding cleft and disruption of pHLA-TCR interactions, underpinning the hierarchy of F24 TCR binding affinity, and ultimately T cell activation. We expanded this approach to all available pHLA-DR structures and discovered that all HLA-DR molecules were inherently rigid. Together with in vitro protein stability and peptide affinity measurements, our results suggest that HLA-DR1 possesses inherently high protein stability, and low HLA-DM susceptibility.

The Role of Conformational Dynamics in Abacavir-Induced Hypersensitivity Syndrome

Abacavir is an antiretroviral drug used to reduce human immunodeficiency virus (HIV) replication and decrease the risk of developing acquired immune deficiency syndrome (AIDS). However, its therapeutic value is diminished by the fact that it is associated with drug hypersensitivity reactions in up to 8% of treated patients. This hypersensitivity is strongly associated with patients carrying human leukocyte antigen (HLA)-B*57:01, but not patients carrying closely related alleles. Abacavir’s specificity to HLA-B*57:01 is attributed to its binding site within the peptide-binding cleft and subsequent influence of the repertoire of peptides that can bind HLA-B*57:01. To further our understanding of abacavir-induced hypersensitivity we used molecular dynamics (MD) to analyze the dynamics of three different peptides bound to HLA-B*57:01 in the presence and absence of abacavir or abacavir analogues. We found that abacavir and associated peptides bind to HLA-B*57:01 in a highly diverse range of conformations that are not apparent from static crystallographic snapshots, but observed no difference in either the conformations, nor degree of flexibility when compared to abacavir-unbound systems. Our results support hypersensitivity models in which abacavir-binding alters the conformational ensemble of neopeptides, so as to favour exposed peptide surfaces that are no longer recognized as self by circulating CD8+ T cells, and are conducive to TCR binding. Our findings highlight the need to also consider the role of dynamics in understanding drug-induced hypersensitivities at the molecular and mechanistic level. This additional insight can help inform the chemical modification of abacavir to prevent hypersensitivity reactions in HLA-B*57:01+ HIV patients whilst retaining potent antiretroviral activity.

Previously Hidden Dynamics at the TCR-Peptide-MHC Interface Revealed

A structural characterization of the interaction between αβ TCRs and cognate peptide-MHC (pMHC) is central to understanding adaptive T cell-mediated immunity. X-ray crystallography, although the source of much structural data, traditionally provides only a static snapshot of the protein. Given the emerging evidence for the important role of conformational dynamics in protein function, we interrogated 309 crystallographic structures of pMHC complexes using ensemble refinement, a technique that can extract dynamic information from the x-ray data. Focusing on a subset of human pMHC class I systems, we found that in many cases, ensemble methods were able to uncover previously hidden evidence of significant conformational plasticity, thereby revealing additional information that can build upon and significantly enhance functional interpretations that are based on a single static structure. Notable examples include the interpretation of differences in the disease association of HLA subtypes, the relationship between peptide prominence and TCR recognition, the role of conformational flexibility in vaccine design, and the discrimination between induced fit and conformational selection models of TCR binding. We show that the currently widespread practice of analyzing pMHC interactions via the study of a single crystallographic structure does not make use of pertinent and easily accessible information from x-ray data concerning alternative protein conformations. This new analysis therefore not only highlights the capacity for ensemble methods to significantly enrich the interpretation of decades of structural data but also provides previously missing information concerning the dynamics of existing characterized TCR-pMHC interactions.

Alteration of sarcoplasmic reticulum Ca2+ ATPase expression in lower limb ischemia caused by atherosclerosis obliterans

Atherosclerosis is a disease caused by a build-up of fatty plaques and cholesterol in the arteries. The lumen of the vessels is obliterated resulting in restricted blood supply to tissues. In ischemic conditions, the cytosolic Ca²⁺ level of skeletal muscle may increase, indicating the alteration of Ca²⁺ removal mechanisms. Ca²⁺ is transported from cytosol into the sarcoplasmic reticulum by Ca²⁺ ATPase (SERCA), with its 1a isoform expressed in adult, while its 1b isoform in neonatal and regenerating fast-twitch skeletal muscle. To investigate the role of these isoforms in ischemic skeletal muscle, biopsies from musculus biceps femoris of patients who underwent amputation due to atherosclerosis were examined. Samples were removed from the visibly healthy and hypoxia-affected tissue. Significantly increased SERCA1a expression was detected under the ischemic conditions (246 ± 69%; p < 0.05) compared with the healthy tissue. Furthermore, the ratio of SERCA1a-positive fibers was slightly increased (46 ± 4% in healthy tissue and 60 ± 5% in ischemic tissue; p > 0.05), whereas SERCA2a did not change. In addition, in primary cultures derived from hypoxia-affected tissue, the diameter and fusion index of myotubes were significantly increased (30 ± 1.6 µm vs. 41 ± 2.4 µm and 31 ± 4% vs. 45 ± 3%; p < 0.05). We propose that the increased SERCA1a expression indicates the existence and location of compensating mechanisms in ischemic muscle.

Modelling of Thyroid Peroxidase Reveals Insights into Its Enzyme Function and Autoantigenicity

Thyroid peroxidase (TPO) catalyses the biosynthesis of thyroid hormones and is a major autoantigen in Hashimoto's disease--the most common organ-specific autoimmune disease. Epitope mapping studies have shown that the autoimmune response to TPO is directed mainly at two surface regions on the molecule: immunodominant regions A and B (IDR-A, and IDR-B). TPO has been a major target for structural studies for over 20 years; however, to date, the structure of TPO remains to be determined. We have used a molecular modelling approach to investigate plausible modes of TPO structure and dimer organisation. Sequence features of the C-terminus are consistent with a coiled-coil dimerization motif that most likely anchors the TPO dimer in the apical membrane of thyroid follicular cells. Two contrasting models of TPO were produced, differing in the orientation and exposure of their active sites relative to the membrane. Both models are equally plausible based upon the known enzymatic function of TPO. The "trans" model places IDR-B on the membrane-facing side of the myeloperoxidase (MPO)-like domain, potentially hindering access of autoantibodies, necessitating considerable conformational change, and perhaps even dissociation of the dimer into monomers. IDR-A spans MPO- and CCP-like domains and is relatively fragmented compared to IDR-B, therefore most likely requiring domain rearrangements in order to coalesce into one compact epitope. Less epitope fragmentation and higher solvent accessibility of the "cis" model favours it slightly over the "trans" model. Here, IDR-B clusters towards the surface of the MPO-like domain facing the thyroid follicular lumen preventing steric hindrance of autoantibodies. However, conformational rearrangements may still be necessary to allow full engagement with autoantibodies, with IDR-B on both models being close to the dimer interface. Taken together, the modelling highlights the need to consider the oligomeric state of TPO, its conformational properties, and its proximity to the membrane, when interpreting epitope-mapping data.

The Janus face of reactive oxygen species in resistance and susceptibility of plants to necrotrophic and biotrophic pathogens

Plant pathogens can be divided into biotrophs and necrotrophs according to their different life styles; biotrophs prefer living, while necrotrophs prefer dead cells for nutritional purposes. Therefore tissue necrosis caused by reactive oxygen species (ROS) during pathogen infection increases host susceptibility to necrotrophic, but resistance to biotrophic pathogen. Consequently, elevation of antioxidant capacity of plants enhances their tolerance to development of necroses caused by necrotrophic pathogens. Plant hormones can strongly influence induction of ROS and antioxidants, thereby influencing susceptibility or resistance of plants to pathogens. Pathogen-induced ROS themselves are considered as signaling molecules. Generally, salicylic acid (SA) signaling induces defense against biotrophic pathogens, whereas jasmonic acid (JA) against necrotrophic pathogens. Furthermore pathogens can modify plant's defense signaling network for their own benefit by changing phytohormone homeostasis. On the other hand, ROS are harmful also to the pathogens, consequently they try to defend themselves by elevating antioxidant activity and secreting ROS scavengers in the infected tissue. The Janus face nature of ROS and plant cell death on biotrophic and on necrotrophic pathogens is also supported by the experiments with BAX inhibitor-1 and the mlo mutation of Mlo gene in barley. It was found that ROS and elevated plant antioxidant activity play an important role in systemic acquired resistance (SAR) and induced systemic resistance (ISR), as well as in mycorrhiza induced abiotic and biotic stress tolerance of plants.

Suppression of tobacco mosaic virus-induced hypersensitive-type necrotization in tobacco at high temperature is associated with downregulation of NADPH oxidase and superoxide and stimulation of dehydroascorbate reductase

Tissue necroses and resistance during the hypersensitive response (HR) of tobacco to tobacco mosaic virus (TMV) are overcome at temperatures above 28 degrees C and the virus multiplies to high levels in the originally resistant N-gene expressing plants. We have demonstrated that chemical compounds that generate reactive oxygen species (ROS) or directly applied hydrogen peroxide (H(2)O(2)) are able to induce HR-type necroses in TMV-inoculated Xanthi-nc tobacco even at high temperatures (e.g. 30 degrees C). The amount of superoxide (O(2)(*-)) decreased, while H(2)O(2) slightly increased in TMV- and mock-inoculated leaves at 30 degrees C, as compared with 20 degrees C. Activity of NADPH oxidase and mRNA levels of genes that encode NADPH oxidase and an alternative oxidase, respectively, were significantly lower, while activity of dehydroascorbate reductase was significantly higher at 30 degrees C, as compared with 20 degrees C. It was possible to reverse or suppress the chemically induced HR-type necrotization at 30 degrees C by the application of antioxidants, such as superoxide dismutase and catalase, demonstrating that the development of HR-type necroses indeed depends on a certain level of superoxide and other ROS. Importantly, high TMV levels at 30 degrees C were similar in infected plants, whether the HR-type necrotization developed or not. Suppression of virus multiplication in resistant, HR-producing tobacco at lower temperatures seems to be independent of the appearance of necroses but is associated with temperatures below 28 degrees C.

Prognosis of patients with local recurrence after mastectomy or conservative surgery for early-stage invasive breast cancer

Between 1983 and 1987, 1309 women with stage I or II breast cancer underwent mastectomy (n=894) or conservative surgery (CS, n=415). Of these patients, 124 developed an isolated local recurrence (ILR): chest wall, 56 and in-breast, 68. The 10-year actuarial rate of cause-specific survival after treatment for ILR was 52%. On multivariate analysis three independent prognostic factors for the risk of death after ILR were identified: operability of recurrence (operable vs. inoperable, relative risk [RR]: 5.9), age at initial diagnosis (>40 vs. < or = 40 years, RR: 2.2) and time to ILR (>24 vs. < or = 24 months, RR: 2). Initial lymph node stage (negative vs. positive) showed borderline significance (p=0.06), and type of initial surgery (CS vs. mastectomy) and recurrent tumor grade (1-2 vs. 3) were not independent predictors of survival. In the mastectomy group, single surgical scar recurrence with initial node negative stage predicted good prognosis, and the 10-year survival was 85%. In the CS group, the 10-year survival rate was 88% with new primary tumor and 54% with true recurrence (p=0.01), and the type of salvage surgery (mastectomy vs. repeat complete excision) had no significant impact on survival (p=0.2). The majority (n=44) of CS patients developed < or = 2 cm in-breast recurrence, and the 10-year survival was 81% after both salvage excision (n=28) and mastectomy (n=16). The identified unfavorable prognostic factors are pointers of the forthcoming systemic progression. Patients with < or = 2 cm in-breast recurrence might receive a second CS.

Melanoma cells exhibit strong intracellular TASK-3-specific immunopositivity in both tissue sections and cell culture

Amplification of the kcnk9 gene and overexpression of the encoded channel protein (TASK-3) seems to be involved in carcinogenesis. In the present work, TASK-3 expression of melanoma cells has been studied. For the investigation of TASK-3-specific immunolabelling, a monoclonal antibody has been developed and applied along with two, commercially available polyclonal antibodies targeting different epitopes of the channel protein. Both primary and metastatic melanoma cells proved to be TASK-3 positive, showing prominent intracellular TASK-3-specific labelling; mostly concentrating around or in the proximity of the nuclei. The immunoreaction was associated with the nuclear envelope, and with the processes of the cells and it was also present in the cell surface membrane. Specificity of the immunolabelling was confirmed by Western blot and transfection experiments. As TASK-3 immunopositivity of benign melanocytes could also be demonstrated, the presence or absence of TASK-3 channels cannot differentiate between malignant and non-malignant melanocytic tumours.

Distribution and elimination of fumonisin analogues in weaned piglets after oral administration of Fusarium verticillioides fungal culture

The distribution and elimination of fumonisins after oral administration of 50 mg FB(1), 20 mg FB(2) and 5 mg FB(3) per animal day(-1) for 22 days was studied in weaned barrows. At the end of the trial, the lung, heart, liver, kidney, spleen, brain, serum, bile, muscle, fat, urine and faeces samples were collected and their content of fumonisins (FB(1), FB(2)) determined by LC-MS. The highest FB(1) concentrations were found in the liver (99.4 +/- 37.5 ng g(-1)) and kidneys (30.6 +/- 10.1 ng g(-1)), whilst the highest average amount of FB(2) was in the liver (1.4 +/- 2.3 ng g(-1)) and fat (2.6 ng g(-1) +/- 4.8) samples. Comparing the FB(1)/FB(2) ratio in different organs (19/1), it was found that the ratio in the abdominal and subcutaneous fat samples (4/1) was markedly different from those in all other tissues, namely the relative proportion of FB(2) was higher in latter cases. Of the total quantity of FB(1), the 13% taken up during 5 days was excreted unchanged with the faeces and urine. On average, in the urine and faeces, FB(1) was detected in nine- and 14-fold quantities, as compared with FB(2).

Alkane isomers: presence in petroleum ether and complexity

The presence and absence of alkane isomers in petroleum and petroleum derivatives depend on the complexity of these structures. It was assumed that the more complex the structure is the less probable it is that that the molecule can be detected in any petroleum derivative. Complexity is a vague concept, which has not been defined in quantitative terms yet, and therefore there is no experimental method, which could be used to determine 'complexity'. Mass spectrometry and infrared spectroscopy in combination with gas chromatography were used to identify the various structural isomers of alkanes in petroleum ether. The isomers were categorised in quantitative terms by using topological indices and linear discriminant analysis. It was found that alkanes possessing a more complex, highly branched structure are less probable to be detected in petroleum ether than isomers with a simpler backbone structure. It was proposed that the experimental 'measure' of the complexity of isomer(i) should be proportional to 1/C(i), where C(i), denotes the concentration of isomer(i) in a (primary) petroleum derivative.

In vitro study of elements in herbal remedies

Decreased glucose tolerance is a first sign of diabetes mellitus and therefore rigorous control must be taken in carbohydrate and lipid metabolisms. Herbal remedies (lyophilized extracts of Myrtilli folium and Phaseoli fructus sine seminibus (L1), Myrtilli folium, Phaseoli fructus sine seminibus, and Salviae folium (L2) are traditionally used in mid-European folk medicine and in common adjuvant therapy for the prevention of complications in type 2 diabetes. Significant iron (355.7 +/- 13.8 mg/kg) and zinc (84.73 +/- 1.83 mg/kg) concentration was found in L1 and chromium (3.82 +/- 2.71 mg/kg) in L2. Ion concentrations in teas made from L1 and L2 are relatively low because the quantities of metal ions in teas do not cover the daily need, although the teas are good sources for some elements. According to the Recommended Daily Allowances, the tea of L1 is a good source for iron and manganese, whereas for chromium, the tea of L2 is better. For evaluating the element bioavailability, an in vitro dialysis system was applied to determine the element transfer from tea of the lyophilized sample to the plasma (buffer pH=7.4). Measurements showed that the elements transferred between 6.90% (iron from tea of L2) and 90.05% (chromium from tea of L2) through the membrane from teas to the plasma. Metal ions in teas of herbal remedies might contribute to the favorable therapeutic effect of preventing complications, because they might transfer through the membranes in relatively high percentages.

The time-course of metastases from breast cancer after mastectomy and breast-conserving surgery with and without isolated local-regional recurrence

We have examined time intervals between events in 390 metastatic breast cancer (MBC) patients whose distant failure developed within 10 years from initial surgery of Stage I/II disease. All of the patients underwent axillary dissection and mastectomy (n=295) or breast-conserving surgery (BCS, n=95), between 1983 and 1987. Distinctions have been made between distant failure with (n=79) and without (n=311) isolated local-regional recurrence (LRR). The median survival time after first relapse was significantly longer with intrabreast (30 months) and chest wall (24 months) than with distant relapse (15 months), but with axillary (17 months) or with supraclavicular (17 months) relapse survival was similar. The delay between LRR and distant metastasis was shorter with axillary (7 months) and supraclavicular (9 months) than with breast (20 months) and chest wall (12 months) recurrences. The median postmetastatic survival time by site of first relapse was significantly shorter with supraclavicular (6 months) and axillary (9 months) than with distant site relapse (15 months) but with intrabreast (12 months) or with chest wall (11 months) recurrence survival was similar. In MBC, regional recurrences are associated with a shorter interval between events than with local recurrences. The shortened intervals for patients with regional recurrence suggest that metastases existed at the time of initial surgery. The question of whether prevention of local or regional recurrence or both improves cause-specific survival after mastectomy or BCS needs to be answered in randomized studies.

Effect of dietary fumonisin B1 on certain immune parameters of weaned pigs

Only few data are available on the effect of fumonisins on the immune response. The aim of the present study was to examine whether dietary fumonisin B1 (FB1) has any effect on the humoral and cellular immune response in weaned pigs, depending on the dose and the time of toxin exposure. Fusarium moniliforme fungal culture was added to the experimental animals' diet to ensure an FB1 intake of 1, 5 and 10 ppm (first experiment) or 100 mg per animal per day (second experiment). The control animals were fed a toxin-free diet. In order to determine the immune response, the animals were vaccinated against Aujeszky's disease with inactivated vaccine (Aujesping K, Phylaxia-Sanofi, Budapest, Hungary). Specific and nonspecific in vitro cellular immune response was measured by the lymphocyte stimulation test (LST) induced by PHA-P, Con A, LPS and inactivated suspension of the Aujeszky's disease virus. Humoral immune response, e.g. specific antibody titre, was measured by the virus neutralisation (VN) test. None of the immunological parameters examined showed significant differences between groups. It could be concluded that fumonisin B1 had no significant effect on the humoral and cellular specific and nonspecific immune response when fed in a high dose (100 mg/animal/day for 8 days) or in a low concentration even for a longer period (1, 5 and 10 ppm for 3-4 months).

Lens-sparing external beam radiotherapy of intraocular metastases: our experiences with twenty four eyes

Occurrence of uveal metastases is higher, than the number of clinically diagnosed cases, furthermore all cases are not amenable to therapy. Treatment of primary cancer is permanently improving, as a result life prospective is better, with an increasing number of late distant metastases in an unusual location, as e.g. intraocular metastasis. As surgical approach is not suitable, and chemo/hormonal therapy often has a limited effect on intraocular dissemination, other treatment modalities are needed for the maintenance of visual acuity, and prevention of further deterioration of the quality of life. The study was made to evaluate the efficacy of external beam radiotherapy (EBRT) with lens-sparing techniques in the management of patients developing intraocular metastases (IOM). Between March 1994 and March 2002, 24 eyes of 17 patients with tumors metastatic to the eye were treated by EBRT. The female:male ratio was 8.5:1, age ranged between 37 and 74 years (mean: 56 years). The site of the primary tumor was: breast (11), lung (4) and others (2). The visual acuity at the beginning of irradiation was between 0.1-0.7 (mean 0.5) and a mean KPS of 60% was detected. The mean time elapsed from the diagnosis of primary tumor and recognition of metastasis was 38.9 months in case of breast, and 6.7 months in lung cancer. Eyes were treated by 6 MV photon beams, using a modified technique of Schipper's lens-sparing retinoblastoma treatment method. The following parameters were studied: visual acuity changes, local response rate, survival times from irradiation and ocular complications. Mean follow-up time was 24 months. Mean visual acuity improved two lines on the Snellen chart. The mean survival time after treatment of IOM was 21 months in breast and 4.9 months in lung cancer patients. Local response rate was 78%. No radiation cataract was observed. Only one patient developed radiation retinopathy 32 months after the treatment. External beam radiotherapy is recommended for the treatment of intraocular metastases to improve quality of life. In selected cases--especially breast cancer patients--lens-sparing technique is the treatment of choice.

The role of boost irradiation in the conservative treatment of stage I-II breast cancer

In this article, we review the current status, indication, technical aspects, controversies, and future prospects of boost irradiation after breast conserving surgery (BCS). BCS and radiotherapy (RT) of the conserved breast became widely accepted in the last decades for the treatment of early invasive breast cancer. The standard technique of RT after breast conservation is to treat the whole breast up to a total dose of 45 to 50 Gy. However, there is no consensus among radiation oncologists about the necessity of boost dose to the tumor bed. Generally accepted criteria for identification of high risk subgroups, in which boost is recommended, have not been established yet. Further controversy exists regarding the optimal boost technique (electron vs. brachytherapy), and their impact on local tumor control and cosmesis. Based on the results of numerous retrospective and recently published prospective trials, the European brachytherapy society (GEC-ESTRO), as well as the American Brachytherapy Society has issued their guidelines in these topics. These guidelines will help clinicians in their medical decisions. Some aspects of boost irradiation still remain somewhat controversial. The final results of prospective boost trials with longer follow-up, involving analyses based on pathologically defined subgroups, will clarify these controversies. Preliminary results with recently developed boost techniques (intraoperative RT, CT-image based 3D conformal brachytherapy, and 3D virtual brachytherapy) are promising. However, more experience and longer follow-up are required to define whether these methods might improve local tumor control for breast cancer patients treated with conservative surgery and RT.

[Management of the axilla in breast cancer: evidences and unresolved issues]

In this study the evidences governing the management of the axilla were examined and on the base of these evidences, the optimal clinical practice was outlined. Computerized searches for publications, debating specific treatment of axilla, were done of MEDLINE data. Level of evidence was determined using standard criteria: 1. metaanalysis of randomized trials, 2. randomized trial, 3. prospective and retrospective studies, 4. reports and opinion of expert committees and working teams. The probability of lymph node involvement is related directly to the size of the primary tumour, and even with small tumour (up to 10 mm), the risk of nodal metastases is in the order of 10-20%. To date, the best strategy for determining complete lymph node status (qualitative and quantitative information) is through axillary dissection. For an accurate staging, at least ten nodes have to be obtained. Formal axillary sampling does not provide total quantitative data in patients with involved axilla. Sentinel node biopsy is a promising alternative to axillary dissection for staging but it is still under way. Axillary dissection should be omitted in patients with ductal carcinoma in situ since the probability of nodal involvement is less than 1%. In invasive breast cancer, the risk of axillary recurrence in the untreated axilla varies from about 10% to 40%. For women with stage I-II breast cancer at least level I and II axillary node dissection should be offered as the standard procedure to reduce the risk of regional recurrence. Women at high risk of axillary recurrence (> or = 4 involved nodes, < 6 nodes were obtained from a positive axilla) will require axillary irradiation after axillary dissection. However, there is a lack of higher level evidence to support the benefit of post-dissection axillary irradiation. Evidences suggest that axillary irradiation is as effective as axillary dissection in preventing regional recurrence. The following factors have to be considered for decisions regarding dissection or irradiation: patient wishes, general condition, age, the necessity of pathological nodal status for systemic therapy and the risk of post-treatment morbidity. At this time, there is no well defined subgroup of patients in whom axillary intervention can be safely omitted. In selected patients with clinically negative axilla, the decision to observe the axilla rather than use surgery or irradiation should be made jointly between the women and her specialists (surgeon, radiation and medical oncologist). The benefits of axillary treatment in prolonging survival are unclear. Studies have reported different effects on survival. Until evidences remain insufficient, the risk of axillary recurrence has to be minimized, and more and more patients have to be provide to get treatments in randomized clinical trials. Patient should be fully informed about the benefits and the potential side effects of treatments. A combination of radiotherapy and axillary dissection results an increased morbidity rate compared with either alone.

[Breast-conserving treatment for early invasive lobular breast cancer: 15 years results]

BACKGROUND

Infiltrating lobular cancer is biologically different from invasive ductal cancer and there is disagreement regarding appropriate local management of this disease.

PURPOSE

To examine treatment outcomes after breast-saving surgery for patients with invasive lobular breast cancer.

MATERIAL AND METHODS

Between 1983 and 1987, 77 women with early, stage I-II invasive lobular breast cancer were treated with complete gross excision of the tumour and axillary dissection. Fifty-eight of these patients were treated with 50 Gy ipsilateral breast irradiation, and 19 did not receive radiotherapy. During 176 month median follow-up local-regional recurrences, distant metastases, contralateral breast cancers, breast cancer deaths and deaths caused by other disease were scored. The probability of survival was estimated by Kaplan-Meier method. In uni- and multivariate analysis the Cox-model was used. Relative risk (RR) and associated confidence intervals (CI) were calculated from the regression coefficients. Statistical differences in proportions and means were assessed by log rank and Fisher exact-tests.

RESULTS

In the saved breast, the actual rate of local recurrence at 15 years was 13% for irradiated and 53% for non-irradiated patients (RR: 0.1; 95% CI: 0.03-0.31; p: < 0.0001). The incidence of total breast cancer relapses (local-regional recurrences and distant metastases) was also higher for non-irradiated than for irradiated patients (74% vs. 40%; p: 0.0168). In multivariate analysis irradiation (no vs. yes) showed a significant effect on local tumour control (RR: 0.08: 95% CI: 0.02-0.28; p: 0.0001), but menopausal (pre vs. post), T-(T1 vs. T2) and N-(N0 vs. N1) status did not. The breast cancer specific survival at 15 years was 74% without and 62% with local recurrence (RR: 1.45; 95% CI: 0.53-3.96; p: 0.4697). The majority of local recurrences (9 of 14) were curable by salvage surgery. For all patients the rate of contralateral breast cancer was 6.5%.

CONCLUSION

Results of long-term follow-up confirmed that breast-conserving surgery and radiotherapy is a reasonable treatment for patients with early invasive lobular breast cancer. The majority of local recurrences are curable by salvage surgery.

In vivo detection of tobacco mosaic virus-induced local and systemic oxidative burst by electron paramagnetic resonance spectroscopy

This is the first demonstration that tobacco mosaic virus-induced oxidative stress in a necrotic host plant is signalled by an elevated level of monodehydroascorbate (MDA) radicals detected by electron paramagnetic resonance spectroscopy. Furthermore, systemic acquired resistance induced in remote leaves of Xanthi-nc tobacco is also associated with stimulated MDA signals indicative of a microoxidative burst.

The role of STIR MRI sequence in the evaluation of the breast following conservative surgery and radiotherapy

The purpose of the study was to define the value of fat suppressed STIR sequence in the MRI of the conserved breast. To our knowledge, this study is the first clinical evaluation of STIR sequence in post-therapy conditions. Forty patients with early (T1-2, N0-1) invasive breast cancer underwent conservative surgery and postoperative radiotherapy. Routine follow-up examinations, including physical examination and mammography were supplemented with breast MRI in all cases 6-166 months (mean 27.6) after initial treatments. Three patients had bilateral cancer. Including follow-up (9 patients) MRI examinations, altogether 53 MRIs were available for analysis. An 0.5 T MRI (Elscint, Haifa, Israel) was used with double breast coil. Axial T1 and T2 weighted spin echo, STIR and 3D gradient echo dynamic sequences were performed. Pre- and postcontrast slices underwent serial subtraction. Twenty-eight circumscribed lesions were identified. All were well visualised on STIR sequence, regardless of histologic nature of lesions. One low grade DCIS was not detected by any sequence. Differential diagnosis between benign and malignant lesions was not possible by STIR sequence alone. STIR sequence was found to be more sensitive in the detection of treatment related breast edema and fluid collection, than T2 SE (spin-echo) sequence. Even the patients who were not good candidates for subtracted contrast enhanced dynamic studies - because of motion artefacts - could have been examined with satisfactory results. STIR is a very sensitive sequence for depicting circumscribed lesions and post-therapy complications, but not suitable for differentiation. It is a useful tool in the follow-up of patients with conserved breast subjected to radiotherapy.

Modification of a linear accelerator table top for non-coplanar conformal brain radiotherapy

The use of non-coplanar conformal therapy necessitates the use of unusual beam projections that may not be accomplished with a conventional linear accelerator table top. Modification of the table top can increase the available combinations of gantry and couch rotation. A standard Philips table top, supplied with an SL 75-5 linear accelerator, was modified to increase available combinations of gantry and couch rotation. This was accomplished by shortening the length and decreasing the width of the table top. The modified table top increases the combinations of gantry and couch angles significantly, simplifying the delivery of non-coplanar conformal therapy without significant compromise to routine treatment. The modification of a standard linear accelerator table top has increased the available combinations of gantry and couch rotation to accommodate non-coplanar conforrmal radiotherapy.

Postirradiation angiosarcoma of the chest wall and breast: issues of radiogenic origin, diagnosis and treatment in two cases

The authors report two cases of postradiation angiosarcoma (AS) among 5,100 breast cancer patients treated in the period 1980-1994 at the National Institute of Oncology, Budapest. Relevant data in the literature is also reviewed to analyze the questions of radiogenic origin, diagnosis and treatment. Secondary AS occurred in these cases in a previously irradiated field after a 6- and 8-year latency period, respectively. Detailed histopathological and immunohistochemical examinations from the biopsy specimens confirmed the diagnosis as AS. The first patient was treated successfully with radical surgery. The second patient, with unresectable AS, died of rapid local progression within 4 months. The incidence of chest wall and breast AS after radiotherapy was found to be 0.46 per 1,000 in our patient population, which means an estimated odds ratio of 2.9 for secondary AS. Patients treated with radiotherapy for primary breast cancer are at higher risk for developing secondary AS compared to the healthy population. An etiological relationship between radiotherapy and subsequent AS of the chest wall and breast is likely, but still controversial. Initial radical surgery is the only effective treatment for achieving long-term survival. These very rare cases deserve special attention due to the atypical clinical appearance, difficulties of differential diagnosis and poor prognosis.

The impact of radiotherapy on the incidence and time of occurrence of local recurrence in early-stage breast cancer after breast conserving therapy

There is still little information on the delay of local recurrence after conservatively treated and irradiation breast cancer. To evaluate the impact of radiation therapy (RT) on the incidence and on the time of occurrence of ipsilateral breast tumor recurrence (IBTR), we reviewed the treatment results in 415 women with UICC Stage I or II unilateral breast cancer. All underwent breast conserving surgery (BCS) and full axillary dissection between 1983 and 1987. Out of them 309 patients were irradiated and 106 were not. The median dose of RT was 50 Gy in five weeks to the whole breast. Systemic therapy, when it was given, consisted of 6-cycles of CMF for node positive premenopausal women and 20 mg tamoxifen for three years for postmenopausal women. The median follow up time was 120 months in survivors. The 10-year actuarial IBTR rate was 36.6% for the nonirradiated and 9.1% for the irradiated women (p = 0.0000); 48.6% for patients treated with CMF and 4.2% for those treated with CMF plus RT (p = 0.0051); 29.0% for patients treated with tamoxifen and 7.9% for those treated with tamoxifen plus RT (p = 0.0318). The patient's age and the presence of an extensive intraductal component (EIC) were both highly associated with the likelihood of tumor recurrence in the treated breast. Patients under 41 years of age had an actuarial 10-year IBTR rate of 75% without RT and 17. 1% with RT (p = 0.0006). Women with an EIC positive tumor had an IBTR rate of 88.9% when RT was not given and 27.2% when RT was given (p = 0.0003). In invasive lobular cancer, irradiated patients had a IBTR rate of 2.3%, compared to 53.2% for nonirradiated patients (p = 0.0008). RT resulted in a significant delay in the appearance of IBTR (p = 0.0250) and the median time was increased by 20.0 months. We conclude that RT has the property of not only preventing but also delaying IBTR. In invasive lobular tumors the risk of IBTR is very high when RT is omitted, but BCS plus radiation therapy is effective treatment. Patients wih EIC positive tumor are at high risk of IBTR even when a median dose of 50 Gy is given to the whole breast.

[The effect of tumour bed boost on local control after breast conserving surgery. First results of the randomized boost trial of the National Institute of Oncology]

PURPOSE: To evaluate the effect of tumour bed boost on local tumour control (LTC) after breast conserving surgery in a prospective study. METHODS: Between 1995 and 1998, 207 women with early invasive breast cancer who underwent conservative operation were treated by 50 Gy irradiation to the whole breast and then randomly assigned to receive either no further radiotherapy (n=103) or a boost to the tumour bed (n=104) with either 16 Gy electron (n=52) or 12-14.25 Gy high dose rate brachytherapy (n=52). RESULTS: At a median follow-up of 4.25 years the crude rate of local recurrence was 6.7% with and 13.6% without boost. The respective rates of tumour bed relapse were 3.8% vs. 10.7%. The 4 year probability of LTC, relapse-free survival and breast cancer-specific survival was 94.2% vs. 85.1% (p=0.1176), 82.3% vs. 67.2% (p=0.0438) and 84.8% vs. 90.9% (p=0.1111), respectively, in favour of the boost group. Systemic treatments had no significant impact on LTC (88.9% with and 89.6% without systemic treatment, p=0.8858). CONCLUSION: Tumour bed boost decreased the incidence of local and tumor bed relapses with a reduction of 50% and 64%, respectively. Relapse-free survival was improved significantly with boost. However, the influence of boost treatment on breast cancer-specific survival should be tested in further studies. In spite of the higher incidence of late radiation side effects in the boost arm, boost dose is strongly recommended for patients at high risk for local recurrence. The final results of the EORTC trial and other ongoing studies will help to clarify the indication of boost dose according to prognostic subgroups.

[Radiotherapy of early breast cancer. More than loco-regional tumor control]

The authors review the value of radiotherapy in the multidisciplinary treatment of early (stage 0-II) breast cancer and describe past achievements, current scientific evidences and possible future prospects of clinical research. Results of randomized studies proved that conservative surgery with radiotherapy is equally effective to mastectomy for the treatment of in situ and invasive breast cancer, both in terms of local control and overall survival. In the nineties, findings of prospective clinical trials indicate that the use of irradiation in high-risk patients provides both a significant improvement in loco-regional control and survival rate. The magnitude of survival benefit with appropriate patient selection and radiotherapy technique is similar to that seen with adjuvant systemic therapy. Radiotherapy of early breast cancer is based on level I scientific evidences in the vast majority of cases. Remaining controversial issues are subjects of several ongoing international and Hungarian prospective randomized studies.

Barley Mla and Rar mutants compromised in the hypersensitive cell death response against Blumeria graminis f.sp. hordei are modified in their ability to accumulate reactive oxygen intermediates at sites of fungal invasion

The pathogenesis-related accumulation of superoxide radical anions (O2*-) and hydrogen peroxide (H2O2) was comparatively analyzed in a barley line (Hordeum vulgare L. cv Sultan-5) carrying the powdery mildew (Blumeria graminis f.sp. hordei, Speer, Bgh) resistance gene Mla12, and in susceptible mutants defective in Mla12 or in genes "required for Mla12-specified disease resistance" (Rar1 and Rar2). In-situ localization of reactive oxygen intermediates was performed both by microscopic detection of azide-insensitive nitroblue tetrazolium (NBT) reduction or diaminobenzidine (DAB) polymerization, and by an NBT-DAB double-staining procedure. The Mla12-mediated hypersensitive cell death occurred either in attacked epidermal cells or adjacent mesophyll cells of wild-type plants. Whole-cell H2O2 accumulation was detected in dying cells, while O2*- emerged in adjacent cells. Importantly, all susceptible mutants lacked these reactions. An oxalate oxidase, which is known to generate H2O2 and has been implicated in barley resistance against the powdery mildew fungus, was not differentially expressed between the wild type and all mutants. The results demonstrate that the Rar1 and Rar2 gene products, which are control elements of R-gene-mediated programmed cell death, also control accumulation of reactive oxygen intermediates but not the pathogenesis-related expression of oxalate oxidase.

[Evidence-based radiotherapy in the treatment of operable breast cancer: results in the 1990-ies]

The aim of this study was to give information about the evidence based radiation oncology in the treatment of operable breast cancer for specialists involved in the national public health. It was performed a review of the English language clinical studies published in the nineties, in which specific radiotherapy questions of operable breast cancer were debated. Clinical studies were classified according to the level of obtained evidence: randomized study (level I.), cohort study (level II.), retrospective study (level III.) and meta-analysis (mathematical synthesis of results). 1. Findings of one large randomized study indicate that lumpectomy plus irradiation is more beneficial than lumpectomy alone for women with ductal carcinoma in situ. Findings are supported by retrospective studies. 2. There are four complete published randomized studies comparing the outcome of conservative surgery alone to that of conservative surgery plus radiation for patients with stage I-II. breast cancer. The local recurrence rate is unacceptably high when random patients are treated without radiotherapy. Meta-analysis of these studies conferred statistically significant survival advantages on women receiving irradiation. In one randomized clinical trial the delivery of a 10 Gy boost to the tumor bed after 50 Gy to the whole breast significantly reduces the risk of early local recurrence. Additional follow-up evaluation and more evidence will be required to define the indications for boost irradiation. In one randomized trial with unselected patients there was a significant superiority in local control for whole breast irradiation compared to partial breast irradiation, but interim results of prospective studies with carefully selected women appear promising. 3. Findings of three randomized controlled clinical trials indicate that postmastectomy radiotherapy reduces mortality from breast cancer by preventing locoregional recurrences in node positive patients. One study examined the effect of radiation on overall survival by meta-analysis of earlier published randomized studies and demonstrated the reduction of breast cancer deaths in irradiated patients. 4. The value of irradiation of parasternal lymph nodes is uncertain by retrospective studies and is currently being studied in a large European randomized trial. After an adequate axillary lymphadenectomy the incidence of axillary recurrence is low and there is no indication for irradiation. Results of two retrospective studies indicate that irradiation of supraclavicular lymph nodes is beneficial in patients with four or more positive axillary lymph nodes. In summary, thank to the intensive clinical research in radiotherapy, the irradiation of patients with operable breast cancer is based on level I. scientific evidences in the majority of the cases. Results of randomized controlled clinical trials and meta-analyses indicate that radiotherapy is more than locoregional control: breast cancer deaths are reduced among irradiated patients.

[Reexcision and perioperative brachytherapy in the treatment of local relapse after breast conservation: a possible alternative to mastectomy]

Breast conserving surgery and postoperative radiotherapy became widely accepted in the last two decades for the treatment of early invasive breast cancer. In spite of adequate surgery and radiotherapy, the rate of ipsilateral breast tumor recurrence is approximately 10%. In such cases salvage mastectomy is the standard treatment, however wide reexcision of the recurrent tumor is also a reasonable option for selected patients. The risk of second local relapse is higher following further breast conservation compared to mastectomy. The authors report the technique of tumor reexcision combined with intraoperative implantation and perioperative high dose rate (HDR) bracytherapy of the tumor bed for the salvage of recurrence in a previously irradiated breast. One can perform two operative interventions at the same time with this method. Irradiation can be started safely within 48 hours after surgery. A review of the literature is also performed by the authors to demonstrate the role and indication of perioperative brachytherapy in the treatment of breast tumor relapse and other cancer recurrences. Reexcision is a practicable alternative to mastectomy for solitary, parenchymal breast tumor relapse measured 2 cm or less in diameter. Perioperative brachytherapy may decrease the risk of second relapse without increasing radiation side effects. Further prospective study is required to define the value of the prescribed method in comparison with salvage mastectomy.