Pathological complete response in a patient with pleural mesothelioma treated with immunotherapy: a case report.

The role of immunotherapy in the multimodal treatment for pleural mesothelioma (PM) is still under investigation, particularly in the preoperative setting. Pathological complete response (pCR) has been previously described after chemotherapy and immunotherapy; however, there is no prior experience reported with immunotherapy alone before surgery. We report the case of a 58-year-old male with biphasic PM treated with immunotherapy, resulting in a major clinical partial response. Following a multidisciplinary evaluation between thoracic surgeons, medical oncologists, pathologists, radiologists and radiation oncologists, the patient underwent surgery with radical intent through a right extended pleurectomy/decortication (eP/D). Histopathological examination of the specimen confirmed a pathological Complete Response (pCR). This case supports the feasibility and potential efficacy of combining preoperative immunotherapy with surgery in the management of advanced PM.

Roneparstat: Development, Preclinical and Clinical Studies.

A growing interest around heparanase and its role in cancer, inflammation and other diseases prompted the identification of specific inhibitors of this enzyme and the exploration of their potential therapeutic role. Roneparstat, a 15-25 kDa N-acetylated and glycol split heparin, is one of the most potent and widely studied heparanase inhibitors. These studies generated a large body of data, which allowed to characterize Roneparstat properties and to endorse its potential therapeutic role. Multiple Myeloma represents the indication that most of the studies, including the phase I clinical trial, addressed. However, Roneparstat antitumor activity activity has been documented in other cancers, and in non-oncological conditions.In addition, assessing Roneparstat activity in different experimental models contributed to understanding heparanase role and the biological factors that may be affected by heparanase inhibition in more detail. Finally, some studies elucidated the molecular mechanisms regulating the enzyme-inhibitor kinetics, thus providing important data for the identification and design of new inhibitors.The objective of this chapter is to provide a comprehensive overview of the most significant studies involving Roneparstat and discuss its potential role in therapy.

Totally robotic soave pull-through procedure for Hirschsprung's disease: lessons learned from 11 consecutive pediatric patients.

INTRODUCTION: Since Hirschsprung's disease (HSCR) already proved to benefit from robotic surgery, we aimed at describing a wider series of patients with this rare disease who were operated on with a robotic approach. PATIENTS AND METHODS: All consecutive HSCR patients who underwent totally robotic soave pull-through (TRSPT), between October 2015 and June 2019, have been included. Ethical Committee approval was obtained. Data regarding clinical features, technical details, complications, hospital stay, and functional outcome have been prospectively collected for each patient. RESULTS: Eleven patients have been included. Mean age at surgery was 29 months. Median length of surgery was 420 min. Median console time was 180 min. Six patients suffered from rectosigmoid aganglionosis, three from long HSCR (extending up to the hepatic flexure), two from total colonic aganglionosis. No major intraoperative complications occurred. Four patients (three of whom carrying a stoma) experienced minor mucosal tearing during dissection. One anastomotic stricture required dilatation under general anesthesia and two cuff strictures required cuff release (both occurring in patients who experienced intraoperative mucosal tearing). Follow-up lasted a median of 12 months. One patient experienced mild postoperative enterocolitis. Continence scored excellent-to-good in all patients who could be assessed on that regard (7 out of 11). CONCLUSIONS: Provided a number of technical key points are respected, the outcome of TRSPT for HSCR is promising. Younger patients, particularly those carrying a stoma, proved to be technically demanding and deserve a longer learning curve. Accurate preoperative bowel preparation, correct trocar placement and patient positioning proved to be crucial aspects of treatment. To conclude, TRSPT is particularly suitable for older HSCR patients, even those requiring a redo, and represents a valid alternative to available surgical option for this delicate subgroup of HSCR patients.

Deinococcus radiodurans' SRA-HNH domain containing protein Shp (Dr1533) is involved in faithful genome inheritance maintenance following DNA damage.

BACKGROUND: Deinococcus radiodurans R1 (DR) survives conditions of extreme desiccation, irradiation and exposure to genotoxic chemicals, due to efficient DNA breaks repair, also through Mn2+ protection of DNA repair enzymes. METHODS: Possible annotated domains of the DR1533 locus protein (Shp) were searched by bioinformatic analysis. The gene was cloned and expressed as fusion protein. Band-shift assays of Shp or the SRA and HNH domains were performed on oligonucleotides, genomic DNA from E. coli and DR. shp knock-out mutant was generated by homologous recombination with a kanamycin resistance cassette. RESULTS: DR1533 contains an N-terminal SRA domain and a C-terminal HNH motif (SRA-HNH Protein, Shp). Through its SRA domain, Shp binds double-strand oligonucleotides containing 5mC and 5hmC, but also unmethylated and mismatched cytosines in presence of Mn2+. Shp also binds to Escherichia coli dcm+ genomic DNA, and to cytosine unmethylated DR and E. coli dcm- genomic DNAs, but only in presence of Mn2+. Under these binding conditions, Shp displays DNAse activity through its HNH domain. Shp KO enhanced >100 fold the number of spontaneous mutants, whilst the treatment with DNA double strand break inducing agents enhanced up to 3-log the number of survivors. CONCLUSIONS: The SRA-HNH containing protein Shp binds to and cuts 5mC DNA, and unmethylated DNA in a Mn2+ dependent manner, and might be involved in faithful genome inheritance maintenance following DNA damage. GENERAL SIGNIFICANCE: Our results provide evidence for a potential role of DR Shp protein for genome integrity maintenance, following DNA double strand breaks induced by genotoxic agents.

Unicystic high-grade intraductal carcinoma of the parotid gland: cytological and histological description with clinic-pathologic review of the literature.

Intraductal carcinoma of the salivary glands is a rare, not well-characterized tumor. We reviewed the literature and report the first case of a high-grade unicystic intraductal carcinoma of the parotid. Formalin-fixed/paraffin-embedded blocks were sectioned and stained for hematoxylin and eosin and immunostains (CAM5.2, EMA, CK5, p53, p63, SMA, S100 protein, DOG1, mammaglobin, AR, ER, PR, Her-2, and Ki67). A 72-year-old man showed a painless nodule (2 cm) in the right parotid region. A 'tumor of uncertain malignant potential' (low grade) was diagnosed by fine-needle aspiration cytology (FNAC). Preoperative magnetic resonance imaging revealed a well-delimited, oval cyst without evidence of parenchymal invasion (T1-scans: homogeneously isointense with hypointense thin peripheral ring; T2-scans: strongly hyperintense). Histological examination confirmed a unilocular cyst lined by a multistratified epithelium arranged in solid, pseudopapillary, cribriform, and 'incomplete cribriform/microcystic' patterns. Tumor cells were CAM5.2+, EMA+, mammaglobin+, AR+, p63+ (focal), CK5+ (focal), p53 (+, 20%), ER-, PR-, S100 protein-, DOG1-, and Her-2-. A continuous peripheral layer of p63+/CK5+/SMA+ myoepithelial cells proved the 'in situ' nature of the tumor. The evidence of focal severe nuclear atypia, high mitotic index (12 mitoses/10HPFs), and high proliferation index (40%) favored a high-grade intraductal carcinoma. Preoperative FNAC and clinic-pathologic correlation are very helpful. Discrepancy in dysplasia grade between FNAC and resected specimen can occasionally occur (especially in case of focal high-grade features). Total sampling should exclude invasive areas or other cystic malignancies.

Response to photo-oxidative stress of Pseudomonas aeruginosa PAO1 mutants impaired in different functions.

Clinicians often have to deal with infections that are difficult to control because they are caused by superbugs resistant to many antibiotics. Alternatives to antibiotic treatment include antimicrobial photodynamic therapy (aPDT). The photodynamic process causes bacterial death, inducing oxidative stress through the photoactivation of photosensitizer molecules in the presence of oxygen. No PDT-resistant bacteria have been selected to date, thus the response to photo-oxidative stress in non-phototrophic bacteria needs further investigation. The opportunistic pathogen Pseudomonas aeruginosa, in particular, has been shown to be more tolerant to PDT than other micro-organisms. In order to find any genetic determinants involved in PDT-tolerance, a panel of transposon mutants of P. aeruginosa PAO1 involved in the quorum sensing signalling system and membrane cytoplasmic transport were photoinactivated as part of this study. Two pseudomonas quinolone signalling (PQS) knock-out mutants, pqsH- and pqsC-, were as PDT-sensitive as the PAO1 wild-type strains. Two PQS hyperproducer variants, pqsA- and rsaL-, were shown to be more tolerant to photo-oxidative stress than the wild-type strain. In the pqsA- mutant, the hyperpigmentation due to the presence of phenazines could protect cells against PDT stress, while in rsaL- no pigmentation was detectable. Furthermore, a mutant impaired in an ATP-binding cassette transport involved in maintaining the asymmetry of the outer membrane was significantly more tolerant to photo-oxidative stress than the wild-type strain. These observations support the involvement of quorum sensing and the importance of the bacterial cell envelope when dealing with photo-oxidative stress induced by photodynamic treatment.

Oral Rehabilitation of a Patient With Ectodermal Dysplasia Treated With Fresh-Frozen Bone Allografts and Computer-Guided Implant Placement: A Clinical Case Report.

Ectodermal dysplasia (ED) is an inherited disorder characterized by abnormality of ectodermally derived structures. A recurrent oral finding is oligodontia, which in turn leads to a severely hypotrophic alveolar process with typical knife-edge morphology and adverse ridge contours. This unfavorable anatomy can seriously hamper proper implant placement. Fresh-frozen bone (FFB) allografts recently have been proposed to augment the residual bone volume for implant placement purposes; however, scientific evidence concerning the use of FFB to treat ED patients is absent. Similarly, data reporting computer-aided template-guided implant placement in medically compromised patients are limited. Thus the purpose of this report is to illustrate the oral rehabilitation of a female patient affected by ED and treated with appositional FFB block grafts and consecutive computer-guided flapless implant placement in a 2-stage procedure. Fixed implant-supported dental prostheses were finally delivered to the patient, which improved her self-esteem and quality of life. During the follow-up recall 1 year after the prosthetic loading, the clinical examination showed healthy peri-implant soft tissues with no signs of bleeding on probing or pathologic probing depths. The panoramic radiograph confirmed the clinical stability of the result. Peri-implant marginal bone levels were radiographically stable with neither pathologic bone loss at the mesial and distal aspects of each implant nor peri-implant radiolucency. Within the limitations of this report, the use of FFB allografts in association with computer-aided flapless implant surgery might be considered a useful technique in patients affected by ED.

Honey-sensitive Pseudomonas aeruginosa mutants are impaired in catalase A.

The antimicrobial power of honey seems to be ascribable to several factors, including oxidative and osmotic stress. The aim of this study was to find genetic determinants involved in the response to honey stress in the opportunistic pathogen Pseudomonas aeruginosa, chosen as model micro-organism. A library of transposon mutants of P. aeruginosa PAO1 was constructed and only four mutants unable to grow in presence of fir honeydew honey were selected. All four mutants were impaired in the major H2O2-scavenging enzyme catalase A (KatA). The knockout of katA gene caused sensitivity, as expected, not only to hydrogen peroxide but also to different types of honey including Manuka GMO 220 honey. Genetic complementation, as well as the addition of PAO1 supernatant containing extracellular catalase, restored tolerance to honey stress in all the mutants. As P. aeruginosa PAO1 catalase KatA copes with H2O2 stress, it is conceivable that the antimicrobial activity of honey is, at least partially, due to the presence of hydrogen peroxide in honey or the ability of honey to induce production of hydrogen peroxide. The katA-deficient mutants could be used as tester micro-organisms to compare the power of different types of natural and curative honeys in eliciting oxidative stress mediated by hydrogen peroxide.

Chemotherapy induces expression and release of heparanase leading to changes associated with an aggressive tumor phenotype.

High heparanase expression is associated with enhanced tumor growth, angiogenesis, and metastasis in many types of cancer. However, the mechanisms driving high heparanase expression are not fully understood. In the present study, we discovered that drugs used in the treatment of myeloma upregulate heparanase expression. Frontline anti-myeloma drugs, bortezomib and carfilzomib activate the nuclear factor-kappa B (NF-κB) pathway to trigger heparanase expression in tumor cells. Blocking the NF-κB pathway diminished this chemotherapy-induced upregulation of heparanase expression. Activated NF-κB signaling was also found to drive high heparanase expression in drug resistant myeloma cell lines. In addition to enhancing heparanase expression, chemotherapy also caused release of heparanase by tumor cells into the conditioned medium. This soluble heparanase was taken up by macrophages and triggered an increase in TNF-α production. Heparanase is also taken up by tumor cells where it induced expression of HGF, VEGF and MMP-9 and activated ERK and Akt signaling pathways. These changes induced by heparanase are known to be associated with the promotion of an aggressive tumor phenotype. Importantly, the heparanase inhibitor Roneparstat diminished the uptake and the downstream effects of soluble heparanase. Together, these discoveries reveal a novel mechanism whereby chemotherapy upregulates heparanase, a known promoter of myeloma growth, and suggest that therapeutic targeting of heparanase during anti-cancer therapy may improve patient outcome.

Targeting heparanase overcomes chemoresistance and diminishes relapse in myeloma.

In most myeloma patients, even after several rounds of intensive therapy, drug resistant tumor cells survive and proliferate aggressively leading to relapse. In the present study, gene expression profiling of tumor cells isolated from myeloma patients after sequential rounds of chemotherapy, revealed for the first time that heparanase, a potent promoter of myeloma growth and progression, was elevated in myeloma cells that survived therapy. Based on this clinical data, we hypothesized that heparanase was involved in myeloma resistance to drug therapy. In several survival and viability assays, elevated heparanase expression promoted resistance of myeloma tumor cells to chemotherapy. Mechanistically, this enhanced survival was due to heparanase-mediated ERK signaling. Importantly, use of the heparanase inhibitor Roneparstat in combination with chemotherapy clearly diminished the growth of disseminated myeloma tumors in vivo. Moreover, use of Roneparstat either during or after chemotherapy diminished regrowth of myeloma tumors in vivo following therapy. These results provide compelling evidence that heparanase is a promising, novel target for overcoming myeloma resistance to therapy and that targeting heparanase has the potential to prevent relapse in myeloma and possibly other cancers.

Pigments influence the tolerance of Pseudomonas aeruginosa PAO1 to photodynamically induced oxidative stress.

Pseudomonas aeruginosa is an opportunistic pathogen known to be resistant to different classes of antibiotics and disinfectants. P. aeruginosa also displays a certain degree of tolerance to photodynamic therapy (PDT), an alternative antimicrobial approach exploiting a photo-oxidative stress induced by exogenous photosensitizers and visible light. To evaluate whether P. aeruginosa pigments can contribute to its relative tolerance to PDT, we analysed the response to this treatment of isogenic transposon mutants of P. aeruginosa PAO1 with altered pigmentation. In general, in the presence of pigments a higher tolerance to PDT-induced photo-oxidative stress was observed. Hyperproduction of pyomelanin makes the cells much more tolerant to stress caused by either radicals or singlet oxygen generated by different photosensitizers upon photoactivation. Phenazines, pyocyanin and phenazine-1-carboxylic acid, produced in different amounts depending on the cultural conditions, are able to counteract both types of PDT-elicited reactive oxygen species. Hyperproduction of pyoverdine, caused by a mutation in a quorum-sensing gene, rendered P. aeruginosa more tolerant to a photosensitizer that generates mainly singlet oxygen, although in this case the observed tolerance to photo-oxidative stress cannot be exclusively attributed to the presence of the pigment.

Antimicrobial and anti-biofilm effect of a novel BODIPY photosensitizer against Pseudomonas aeruginosa PAO1.

Photodynamic therapy (PDT) combines the use of organic dyes (photosensitizers, PSs) and visible light in order to elicit a photo-oxidative stress which causes bacterial death. GD11, a recently synthesized PS belonging to the boron-dipyrromethene (BODIPY) class, was demonstrated to be efficient against planktonic cultures of Pseudomonas aeruginosa, causing a 7 log unit reduction of viable cells when administered at 2.5 µM. The effectiveness of GD11 against P. aeruginosa biofilms grown in flow-cells and microtiter trays was also demonstrated. Confocal laser scanning microscopy of flow-cell-grown biofilms suggests that the treatment has a biocidal effect against bacterial biofilm cells.

The current management of mycosis fungoides and Sézary syndrome and the role of radiotherapy: Principles and indications.

AIM: To evaluate the current treatment of mycosis fungoides (MF) and Sézary syndrome (SS) focusing on the role of radiotherapy (RT), its principles and indications, and the perspectives of the novel irradiation technologies. BACKGROUND: MF and SS are rare lymphoproliferative diseases whose incidence is increasing. For a long time RT has been used as a single modality or in integrated treatment programs for these diseases. MATERIALS AND METHODS: The latest systematic reviews, primary studies and new diagnostic and treatment guidelines on MF and SS were analyzed. Clinical outcomes together with the technical aspects and the role of RT were also evaluated. RESULTS: New data are available on pathogenesis, diagnostic criteria, classification and staging procedures for MF and SS and several local and systemic therapies are proposed. Localized RT can cure "minimal stage" MF while total skin electron beam irradiation (TSEI) may cure initial-stage disease and may offer important symptom relief (itch, erythroderma) in a more advanced setting. Despite its efficacy, RT is not largely used, mainly because of some technical difficulties but new RT technologies may be proposed to treat large skin surfaces. CONCLUSIONS: New treatment programs offer good results, with median survival of more than 12 years in early-stage MF, but the median survival of 2.5 years or less in advanced stages is still a challenge. RT remains an option for all stages with a good cost/effectiveness ratio in a curative or palliative setting. New RT technologies can overcome some technical problems of treating large skin surfaces.

Photoinduced antibacterial activity of two dicationic 5,15-diarylporphyrins.

Antimicrobial photodynamic treatment combines the use of photosensitizers (PSs) and visible light to kill bacterial cells. Cationic porphyrins are PSs largely used against bacteria and, among them, those featuring one positive charge on each of the 5,10,15,20-tetraaryl substituent (tetracationic) are the most used. The aim of this study was to synthesize two dicationic 5,15-di(N-alkyl-4-pyridyl)porphyrins, bearing methyl (PS 3) and benzyl (PS 4) N-alkylating groups, and to compare the efficiency in antibacterial photodynamic treatment, upon irradiation with a halogen-tungsten white lamp. The killing efficiency of the PS 4 was constantly found higher than that of the PS 3 against both pure and mixed cultures of laboratory model microorganisms as well as against wild wastewater microflora. The two PSs are comparable as regards singlet oxygen generation, but show a different repartition coefficient; the more lipophilic benzylated PS 4 shows a better interaction with the bacterial cells than the methylated one (PS 3). The data support the hypothesis that an efficient PS-cell binding is required to obtain significant effects. A correlation among cell binding, photoinactivation and PS lipophilicity is suggested.

Effect of organic matter on the in vitro photoeradication of Pseudomonas aeruginosa by means of a cationic tetraaryl-porphyrin.

Photodynamic therapy is emerging as an antimicrobial alternative approach; the concomitant presence of a photosensitizer (PS), O(2) and visible light induces lethal oxidative damages to bacterial cells. Among Gram-negative bacteria, Pseudomonas aeruginosa seems to be one of the least susceptible to photodynamic treatment. In this study, we evaluated the influence of several experimental conditions on photoeradication of a planktonic culture of P. aeruginosa PAO1 by means of a tetracationic meso-arylsubstituted porphyrin (RM24). Our findings suggest that the photo-oxidative stress induced by RM24 is strictly correlated to the amount of PS bound to the cells that in turn decreases with the increasing concentrations of organic compounds in the medium. The photoeradication is dependent on PS concentrations, cellular density and light dose. RM24 was able to induce oxidative stress by means of singlet oxygen formation, although ROS formation cannot be ruled out. The standardized experimental conditions of the photospot test allowed us to evidence intraspecific PDT sensitivity differences among three strains of P. aeruginosa.

Unawareness of memory deficit in amnestic MCI: FDG-PET findings.

To unveil the brain metabolic correlates of (un)awareness of memory deficit in subjects with amnestic mild cognitive impairment (aMCI), forty-two outpatients underwent brain 18F-FDG-PET. Awareness of memory deficit was assessed with the Memory Complaint Questionnaire (MAC-Q), identifying two groups: low (MCI/unaware; 17 patients) and good (MCI/aware; 25 patients) aMCI awareness. Twenty-nine age-matched healthy subjects represented the control group. SPM2 was used to assess the correlation between brain metabolism and MAC-Q score, for comparisons between each patient group and controls, and between aMCI/unaware and aMCI/aware groups. The two aMCI groups were comparable in terms of age, gender, education, depression, and neuropsychological tests scores. In the whole 42-patient group, a positive correlation was found between MAC-Q score and metabolism in posterior cingulate cortex in both hemispheres and in inferior parietal lobule, middle cingulate cortex, precuneus and angular gyrus in the left hemisphere. Compared to controls, hypometabolism was found in aMCI/unaware in three large clusters, including precuneus, inferior parietal lobule and superior occipital gyrus, in the left hemisphere, and in inferior parietal lobule, angular gyrus and middle temporal gyrus in the right hemisphere. Smaller clusters of hypometabolism were found in bilateral temporal lobe in aMCI/aware. Hypometabolism in inferior parietal lobule, angular gyrus and superior temporal gyrus in the left hemisphere was highlighted in aMCI/unaware versus aMCI/aware. The significant correlation in all 42 aMCI patients points to posteromedial cortex as a key node of the network being involved in awareness of memory deficit. Patients with low awareness show a more severe hypometabolic pattern, typical of Alzheimer's disease and therefore could be more at risk of developing dementia.

Cloning of the Arthrobacter sp. FG1 dehalogenase genes and construction of hybrid pathways in Pseudomonas putida strains.

An Arthrobacter strain, able to utilize 4-chlorobenzoic acid as the sole carbon and energy source, was isolated and characterized. The first step of the catabolic pathway was found to proceed via a hydrolytic dehalogenation that leads to the formation of 4-hydroxybenzoic acid. The dehalogenase encoding genes (fcb) were sequenced and found highly homologous to and organized as those of other 4-chlorobenzoic acid degrading Arthrobacter strains. The fcb genes were cloned and successfully expressed in the heterologous host Pseudomonas putida PaW340 and P. putida KT2442 upper TOL, which acquired the ability to grow on 4-chlorobenzoic acid and 4-chlorotoluene, respectively. The cloned dehalogenase displayed a high specificity for para-substituted haloaromatics with affinity Cl > Br > I >> F, in the order.

Antibacterial activity of tetraaryl-porphyrin photosensitizers: an in vitro study on Gram negative and Gram positive bacteria.

BACKGROUND: Photodynamic therapy exploits visible light and photosensitizers to inactivate cells and this methodology is currently used for the treatment of several types of malignancy. Although various tumours are successfully treated with PSs and light, the application on microorganisms (photodynamic antimicrobial chemotherapy) has not yet found specific medical applications and still remains an open field of fundamental research. PURPOSE: The assessment of the effect of a panel of seven tetraaryl-porphyrins, two commercial (PS 1 and 2) and five synthetic (PS 3-7) in in vitro experiments against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. METHODS: Three of the new photosensitizers (PS 3, 4 and 5) are tetracationic porphyrins and were prepared by N-alkylation of 5,10,15,20-tetra-4-pyridylporphyrin with a large excess of different benzyl chlorides; compound 7 is a dicationic porphyrin and was obtained in a similar way using a lower excess of 4-methoxybenzyl chloride. The neutral porphyrin (PS 6) was previously described. Dose-response curves were obtained titrating the survivors of cell suspensions (10(8)cfu/ml) exposed to the PSs and irradiated with visible light (total fluence rate 266 J/cm2). RESULTS: The non ionic porphyrin 6 was the least active PS against all the tested bacteria. Cationic PSs 3, 4, 5 and 7 were more active than the commercial 1 and 2. The Gram positive S. aureus was more sensitive to all the PSs than the Gram negative E. coli and P. aeruginosa, the latter being the more resistant one. Compound 7 was found particularly efficient against P. aeruginosa, causing a 7 log units reduction of survivors at a concentration of 8 microM. CONCLUSIONS: The reported results confirm that the presence of positively charged groups on porphyrin frame is fundamental for PSs antibacterial activity, however our data suggest that a moderate degree of lipophilicity, achievable by the introduction of aromatic hydrocarbon side chains on the pyridyl moieties, may improve PSs efficiency. Furthermore dicationic porphyrin 7 seems to be more efficient than the corresponding tetracationic derivatives thus emphasizing an interesting feature involved in the PSs activity.

Genotypic characterization and phylogenetic relations of Pseudomonas sp. (Formerly P. stutzeri) OX1.

Pseudomonas sp. OX1, an aromatic compound-degrading bacterium that was tentatively identified by conventional biochemical methods as P. stutzeri, has now been investigated at the molecular level to clarify its taxonomic position. Amplified ribosomal DNA restriction analysis and multiple enzyme restriction fragment length polymorphism (MERFLP) analysis suggested that Pseudomonas sp. OX1 could not be classified as P. stutzeri. Phylogenetic analyses based on 16S rRNA and gyrB genes further confirmed that this strain belongs to the Pseudomonas (sensu stricto) genus, but not to the stutzeri species. The data obtained demonstrated that Pseudomonas sp. OX1 belongs to intrageneric cluster II and is related to the P. fluorescens-P. syringae complex.