Comparative antimicrobial susceptibility of biofilm versus planktonic forms of Salmonella enterica strains isolated from children with gastroenteritis.

In the present study, 194 Salmonella enterica strains, isolated from infected children and belonging to various serotypes, were investigated for their ability to form biofilms and the biofilm forms of the isolated strains were compared to their corresponding planktonic forms with respect to the antimicrobial susceptibility. For the biofilm-forming strains, the minimum inhibitory concentration for bacterial regrowth (MICBR) from the biofilm of nine clinically applicable antimicrobial agents was determined, and the results were compared to the respective MIC values of the planktonic forms. One hundred and nine S. enterica strains out of 194 (56%) belonging to 13 serotypes were biofilm-forming. The biofilm forms showed increased antimicrobial resistance compared to the planktonic bacteria. The highest resistance rates of the biofilm bacteria were observed with respect to gentamicin (89.9%) and ampicillin (84.4%), and the lowest rates with respect to ciprofloxacin and moxifloxacin (2.8% for both). A remarkable shift of the MICBR(50) and MICBR(90) toward resistance was observed in the biofilm forms as compared to the respective planktonic forms. The development of new consensus methods for the determination of the antimicrobial susceptibility of biofilm forms seems to be a major research challenge. Further studies are required in order to elucidate the biofilm antimicrobial resistance mechanisms of the bacterial biofilms and their contribution to therapeutic failure in infections with in vitro susceptible bacteria.

Investigation of possible cytokine induction in peripheral blood mononuclear cells by heat-stable serotypes of Campylobacter jejuni.

Several Campylobacter jejuni heat-stable (HS) serotypes have been associated with the autoimmune Guillain-Barre neurological syndrome (GBS). In order to examine the possible involvement of cytokines in this phenomenon, the levels of three pro-inflammatory cytokines (interleukin (IL)-2sRa, IL-6 and interferon (IFN)-gamma) and one anti-inflammatory cytokine (IL-10) were measured in peripheral blood mononuclear cells after induction by different C. jejuni serotypes. No differences were found for IL-6, IFN-gamma and IL-10, but the non-sialylated serotype HS:3 was associated with decreased production of IL-2sRa. The results raise the possibility that absence of sialylation might be associated with the inability to induce inflammatory factors such as cytokines.

Prevalence of Yersinia plasmid-encoded outer protein (Yop) class-specific antibodies in patients with Hashimoto's thyroiditis.

OBJECTIVE: To investigate the prevalence of class-specific antibodies (IgG, IgA) to Yersinia enterocolitica plasmid-encoded outer proteins (Yops) in patients with diagnosed Hashimoto's thyroiditis. METHODS: Seventy-one patients with Hashimoto's disease, 464 healthy blood donors and 250 patients with non-postinfectious rheumatic disorders (matched controls) were tested for class-specific antibodies to Yops. Anti-Yop antibodies were determined by ELISA and Western blot. RESULTS: The prevalence of class-specific antibodies to Yops as determined by ELISA was 14-fold higher (20 of 71; 28.2%) in people with Hashimoto's thyroiditis than in the two control groups. These results were confirmed by the Western blot, with 16 positive sera, three equivocal and one negative. CONCLUSIONS: There is strong clinical and seroepidemiologic evidence for an immunopathologic causative relationship between Yersinia enterocolitica infection and Hashimoto's thyroiditis. Further investigation concerning the mechanisms involved and the possible effects of antibacterial chemotherapy on the outcome of Hashimoto's disease is warranted.

Campylobacter jejuni O:19 serotype-associated Guillain-Barré syndrome in a child: the first case reported from Greece.

We present a case of Guillain-Barré syndrome (GBS) following Campylobacter jejuni HS serotype O:19 infection in a child. Antibodies against C. jejuni and autoantibodies to the peripheral nerve gangliosides GM1 were positive, a pattern correlating well with the existence of an inflammatory neuropathy like GBS. The patient shared the HLA-B35 and HLA-DR8 antigens, which have been found to be increased in GBS patients with previous C. jejuni infection. As this is the first diagnosed C. jejuni-associated GBS case reported from Greece, further clinical and epidemiologic investigations are warranted.

Prevalence of cerebrospinal fluid oligoclonal IgG bands in Greek patients with clinically isolated syndrome and multiple sclerosis.

UNLABELLED: Lower prevalence of cerebrospinal fluid oligoclonal IgG bands (IgG-OCBs) has been reported in multiple sclerosis (MS) patients from Southern Europe compared to other western countries. OBJECTIVES: We aimed to determine the prevalence of CSF OCBs in Greek MS patients and to examine their relation with some selected clinical and demographical features. METHODS: Included patients fulfilled the 2005 McDonald criteria for definite MS (CDMS) or clinically isolated syndrome (CIS) and had a spinal tap performed between 2006 and 2010. Paired CSF and plasma samples were analyzed using isoelectric focusing followed by IgG-specific immunofixation. A pattern of two or more bands present only in the CSF was defined as positive. OCB status was correlated with age at disease onset, initial symptomatology, relapse rate, disease subtype, disease duration, medication, EDSS score and MSSS. RESULTS: Of the 231 included patients (53.2% with CDMS and 48.6% with CIS) 67.5% had OCBs. The prevalence of positive patterns did not differ between CIS and CDMS patients (67.6% vs. 67.5%, respectively). OCB-positive patients were younger than OCB-negative patients (35.2±10.3 vs. 38.7±11.8 years respectively, p=0.022) and had more frequently cervical spinal cord lesions (x2=7.08, p=0.008). No difference was observed between the two subgroups in the other studied disease parameters. CONCLUSION: Despite the lower frequency of positive IgG-OCB patterns in our patients, both subgroups were mostly similar with regard to their clinical and demographic characteristics suggesting that the OCB status lacks prognostic significance in MS.

Multi-objective optimization methods in de novo drug design.

De-novo drug design (DND) is a complex procedure, requiring the satisfaction of many pharmaceutically important objectives. Several computational methodologies employing various optimization approaches have been developed to search for satisfactory solutions to this multi-objective problem varying from composite methods, which transform the problem to a single objective one to Pareto methods searching for numerous solutions compromising the objectives. In this review we initially focus on the DND problem and the challenges it poses to computational methods, followed by an examination of the reported methodologies and specific applications. Emphasis is placed on the multiobjective nature of the problem, related considerations and the solutions proposed by the drug discovery community.

An unusual case of insomnia associated with Whipple encephalopathy: first case reported from Greece.

Whipple disease is a relapsing systemic illness caused by Tropheryma whippelii. Central nervous system involvement occurs in 5%-40% of all patients. Hypothalamic manifestations occur in 31% of Whipple encephalopathy, including polydipsia, hyperphagia, change in libido and insomnia. We report a case of a 48-year-old man with severe insomnia, depression, dementia, dysarthria, myoclonic movements of the limbs and ophthalmoplegia. The diagnosis of Whipple encephalopathy was confirmed by PCR analysis of blood and faeces. He received a full dose of antibiotic treatment. Despite clinical improvement, resolution of the lesions detected in MRI scan of the brain and negative results of the PCR in blood, faeces and cerebrospinal fluid six months later, insomnia persisted and finally subsided after the administration of carbamazepine (600 mg/day). Our case supports the finding that carbamazepine might be useful in the treatment of insomnia associated with Whipple encephalopathy.

Ties in proximity and clustering compounds.

Hierarchical clustering algorithms such as Wards or complete-link are commonly used in compound selection and diversity analysis. Many such applications utilize binary representations of chemical structures, such as MACCS keys or Daylight fingerprints, and dissimilarity measures, such as the Euclidean or the Soergel measure. However, hierarchical clustering algorithms can generate ambiguous results owing to what is known in the cluster analysis literature as the ties in proximity problem, i.e., compounds or clusters of compounds that are equidistant from a compound or cluster in a given collection. Ambiguous ties can occur when clustering only a few hundred compounds, and the larger the number of compounds to be clustered, the greater the chance for significant ambiguity. Namely, as the number of "ties in proximity" increases relative to the total number of proximities, the possibility of ambiguity also increases. To ensure that there are no ambiguous ties, we show by a probabilistic argument that the number of compounds needs to be less than 2(n 1/4), where n is the total number of proximities, and the measure used to generate the proximities creates a uniform distribution without statistically preferred values. The common measures do not produce uniformly distributed proximities, but rather statistically preferred values that tend to increase the number of ties in proximity. Hence, the number of possible proximities and the distribution of statistically preferred values of a similarity measure, given a bit vector representation of a specific length, are directly related to the number of ties in proximities for a given data set. We explore the ties in proximity problem, using a number of chemical collections with varying degrees of diversity, given several common similarity measures and clustering algorithms. Our results are consistent with our probabilistic argument and show that this problem is significant for relatively small compound sets.

Analysis of large screening data sets via adaptively grown phylogenetic-like trees.

As the use of high-throughput screening systems becomes more routine in the drug discovery process, there is an increasing need for fast and reliable analysis of the massive amounts of the resulting data. At the forefront of the methods used is data reduction, often assisted by cluster analysis. Activity thresholds reduce the data set under investigation to manageable sizes while clustering enables the detection of natural groups in that reduced subset, thereby revealing families of compounds that exhibit increased activity toward a specific biological target. The above process, designed to handle primarily data sets of sizes much smaller than the ones currently produced by high-throughput screening systems, has become one of the main bottlenecks of the modern drug discovery process. In addition to being fragmented and heavily dependent on human experts, it also ignores all screening information related to compounds with activity less than the threshold chosen and thus, in the best case, can only hope to discover a subset of the knowledge available in the screening data sets. To address the deficiencies of the current screening data analysis process the authors have developed a new method that analyzes thoroughly large screening data sets. In this report we describe in detail this new approach and present its main differences with the methods currently in use. Further, we analyze a well-known, publicly available data set using the proposed method. Our experimental results show that the proposed method can improve significantly both the ease of extraction and amount of knowledge discovered from screening data sets.

Antimicrobial susceptibility patterns of Campylobacter jejuni strains isolated from hospitalized children in Athens, Greece.

The antimicrobial susceptibility of 129 Campylobacter jejuni strains, isolated from hospitalized children with gastroenteritis, to five antimicrobials, including nalidixic acid, ciprofloxacin, erythromycin, ampicillin and co-amoxiclav, was determined. Isolates belonged to two time periods: group A contained strains isolated in 1987-1988; and group B 1998-2000. Antimicrobial susceptibility patterns differed significantly between the two groups with respect to quinolones, with an increase in the percentage of resistant strains in group B (30.6% versus 0% in group A), whereas erythromycin, ampicillin and co-amoxiclav were effective drugs in both groups.