Synthesis and Antibacterial Activity of Benzo[4,5]isothiazolo[2,3-a]pyrazine-6,6-dioxide Derivatives.

Using a routine procedure, a number of derivatives of the benzo[4,5]isothiazolo[2,3-a]pyrazine-6,6-dioxide ring system have been synthesized from readily available starting materials. A series of chalcones were synthesized, which were subsequently reacted with chlorosulfonic acid to generate chalcone sulfonyl chlorides. The chalcone sulfonyl chlorides were then treated with bromine to generate dibromo chalcone sulfonyl chlorides. These were subsequently reacted with 1,2-diaminopropane and 2-methyl-1,2-diaminopropane in boiling ethanol resulting in compounds 2-10 and 11-19 respectively, in 12-80% yields. The products were characterized by spectral analysis and the definitive structure of compound 11 was determined by X-ray crystallography. The synthesized compounds were screened for potential antibacterial properties against Bacillus subtilis, Escherichia coli, Proteus vulgaris and Staphylococcus aureus.

Synthesis and Spectral Characterization of Benzo-[6,7][1,5]diazocino[2,1-a]isoindol-12-(14H)-one Derivatives.

A simple synthetic route affording 27%-85% yields of benzo[6,7][1,5]diazocino[2,1-a]isoindol-12(14H)-one ring systems from readily available 3-(2-oxo-2-phenylethyl) isobenzofuran-1(3H)-ones and 2-(aminomethyl)aniline starting materials in toluene and catalysed by p-toluene-sulfonic acid is developed. The ¹H- and (13)C-NMR spectra of the final products were assigned using a variety of one and two-dimensional NMR experiments. The distinction between the two potential isomers of the final products was made on the basis of heteronuclear multiple bond connectivity (HMBC) NMR spectra.

Synthesis and Antimicrobial Activity of 1,2-Benzothiazine Derivatives.

A number of 1,2-benzothiazines have been synthesized in a three-step process. Nine chalcones 1-9 bearing methyl, fluoro, chloro and bromo substituents were chlorosulfonated with chlorosulfonic acid to generate the chalcone sulfonyl chlorides 10-18. These were converted to the dibromo compounds 19-27 through reaction with bromine in glacial acetic acid. Compounds 19-27 were reacted with ammonia, methylamine, ethylamine, aniline and benzylamine to generate a library of 45 1,2-benzothiazines 28-72. Compounds 28-72 were evaluated for their antimicrobial activity using broth microdilution techniques against two Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus) and two Gram-negative bacteria (Proteus vulgaris and Salmonella typhimurium). The results demonstrated that none of the compounds showed any activity against Gram-negative bacteria P. vulgaris and S. typhimurium; however, compounds 31, 33, 38, 43, 45, 50, 53, 55, 58, 60, 63 and 68 showed activity against Gram-positive bacteria Bacillus subtilis and Staphylococcous aureus. The range of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) was 25-600 µg/mL, though some of the MIC and MBC concentrations were high, indicating weak activity. Structure activity relationship studies revealed that the compounds with a hydrogen atom or an ethyl group on the nitrogen of the thiazine ring exerted antibacterial activity against Gram-positive bacteria. The results also showed that the compounds where the benzene ring of the benzoyl moiety contained a methyl group or a chlorine or bromine atom in the para position showed higher antimicrobial activity. Similar influences were identified where either a bromine or chlorine atom was in the meta position.

A cellulose-based bioassay for the colorimetric detection of pathogen DNA.

Cellulose-paper-based colorimetric bioassays may be used at the point of sampling without sophisticated equipment. This study reports the development of a colorimetric bioassay based on cellulose that can detect pathogen DNA. The detection was based on covalently attached single-stranded DNA probes and visual analysis. A cellulose surface functionalized with tosyl groups was prepared by the N,N-dimethylacetamide-lithium chloride method. Tosylation of cellulose was confirmed by scanning electron microscopy, Fourier transform infrared spectroscopy and elemental analysis. Sulfhydryl-modified oligonucleotide probes complementary to a segment of the DNA sequence IS6110 of Mycobacterium tuberculosis were covalently immobilized on the tosylated cellulose. On hybridization of biotin-labelled DNA oligonucleotides with these probes, a colorimetric signal was obtained with streptavidin-conjugated horseradish peroxidase catalysing the oxidation of tetramethylbenzamidine by H2O2. The colour intensity was significantly reduced when the bioassay was subjected to DNA oligonucleotide of randomized base composition. Initial experiments have shown a sensitivity of 0.1 µM. A high probe immobilization efficiency (more than 90 %) was observed with a detection limit of 0.1 µM, corresponding to an absolute amount of 10 pmol. The detection of M. tuberculosis DNA was demonstrated using this technique coupled with PCR for biotinylation of the DNA. This work shows the potential use of tosylated cellulose as the basis for point-of-sampling bioassays.

A balanced iterative random forest for gene selection from microarray data.

BACKGROUND: The wealth of gene expression values being generated by high throughput microarray technologies leads to complex high dimensional datasets. Moreover, many cohorts have the problem of imbalanced classes where the number of patients belonging to each class is not the same. With this kind of dataset, biologists need to identify a small number of informative genes that can be used as biomarkers for a disease. RESULTS: This paper introduces a Balanced Iterative Random Forest (BIRF) algorithm to select the most relevant genes for a disease from imbalanced high-throughput gene expression microarray data. Balanced iterative random forest is applied on four cancer microarray datasets: a childhood leukaemia dataset, which represents the main target of this paper, collected from The Children's Hospital at Westmead, NCI 60, a Colon dataset and a Lung cancer dataset. The results obtained by BIRF are compared to those of Support Vector Machine-Recursive Feature Elimination (SVM-RFE), Multi-class SVM-RFE (MSVM-RFE), Random Forest (RF) and Naive Bayes (NB) classifiers. The results of the BIRF approach outperform these state-of-the-art methods, especially in the case of imbalanced datasets. Experiments on the childhood leukaemia dataset show that a 7% ∼ 12% better accuracy is achieved by BIRF over MSVM-RFE with the ability to predict patients in the minor class. The informative biomarkers selected by the BIRF algorithm were validated by repeating training experiments three times to see whether they are globally informative, or just selected by chance. The results show that 64% of the top genes consistently appear in the three lists, and the top 20 genes remain near the top in the other three lists. CONCLUSION: The designed BIRF algorithm is an appropriate choice to select genes from imbalanced high-throughput gene expression microarray data. BIRF outperforms the state-of-the-art methods, especially the ability to handle the class-imbalanced data. Moreover, the analysis of the selected genes also provides a way to distinguish between the predictive genes and those that only appear to be predictive.

Tuberculin screening of some selected Fulani lactating cows in North-Central Nigeria.

The prevalence of mycobacterial infection among lactating Fulani cows was investigated in the Federal Capital Territory, Abuja and Kaduna State of Nigeria. Tuberculin testing using single comparative intradermal tuberculin test showed a 14.6 % positive, 4 % doubtful, and 81.4 % negative reactors. Mycobacterial infection was found to be present in the nomadic (constantly moving) and seminomadic (limited movement) management systems studied but management showed no significant effect on the prevalence of the disease. However, the prevalence was significantly higher in older age groups than the younger ones (P < 0.05).

Effect of gamma radiation on microbial safety and nutritional quality of kachri (Cucumis callosus).

Fresh dried and old (6-12 months) dried kachri (Cucumis callosus) were treated with 0, 2.5, 5 and 7 kGy of gamma radiation in a cobalt 60 gamma cell (GC-1200). The irradiated samples of kachri were stored at room temperature (28 ± 2 °C). Total bacterial count and nutrient composition were evaluated immediately after irradiation and at regular intervals of 1 month during 3 months of storage. Results indicated that gamma radiation reduced the total bacterial counts of dried samples of both fresh and old dried kachri. Dose of 5.0 kGy was sufficient to eliminate total bacterial count and there was no microbial growth in 5.0 kGy irradiated samples during the storage period. No significant differences were observed in the proximate composition of both types of kachri at all irradiation doses. It was concluded that irradiation treatments of kachri improves keeping quality of both freshly dried and old dried Kachri.

Clinico-Bacteriological Profile of Typhoid Fever in a Private Sector Hospital in New Delhi.

OBJECTIVE: To describe the demographic, clinical, laboratory and bacteriological profile of children with diagnosis of typhoid fever over a six-year period. METHODS: Case record analysis of hospitalized children (≤5 y) with culture positive typhoid fever. RESULTS: Blood culture was positive in 100 (61%) of 166 suspected cases, with 78 isolates of Salmonella Typhi and 22 Salmonella Paratyphi A. Only 12 children were aged below two years. Hepatomegaly (32), splenomegaly (44), eosinopenia (42), positive widal (15, 21.1%) and positive Typhidot IgM (18, 28.1%) were not consistently observed. High susceptibility to Ampicillin, Chloramphenicol, Cotrimoxazole (87, 89, and 94, isolates, respectively), 100% susceptibility to third generation cephalosporins and Azithromycin, and high resistance to Nalidixic Acid [(S. Typhi 48 (61.5%)], S. Paratyphi A 16 (72.7%)) were observed. CONCLUSIONS: We observed a high isolation rate of salmonella in blood culture, despite prior use of antibiotics. Most salmonella isolates were susceptible in vitro to standard drugs, except nalidixic acid.

RNA isolation and quantitative PCR from HOPE- and formalin-fixed bovine lymph node tissues.

The use of ribonucleic acid (RNA) extracted from Hepes glutamic acid buffer-mediated organic solvent protection effect (HOPE)-fixed tissues in quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) is fairly novel. We compared qRT-PCR analysis of formalin- and HOPE-fixed, paraffin-embedded lymph node tissues from Mycobacterium bovis-infected cattle by extracting total RNA using a commercial kit (Ambion) and a Trizol method. RNA extracted from HOPE-fixed tissues showed comparable quantities between the commercial kit (82.7-107.9 microg/ml total RNA) and the Trizol method (87-161.1 microg/ml total RNA), displaying a high degree of integrity when analyzed by electrophoresis. RNA extracted from formalin-fixed tissues using the commercial kit produced similar concentrations (80.6-145.7 microg/ml total RNA) in comparison to the HOPE tissue; however, the integrity was compromised. Extraction of RNA from the formalin-fixed tissues using Trizol was unsuccessful. Following qRT-PCR for glyceraldehyde-3-phosphate dehydrogenase (GAPDH), total RNA from HOPE-fixed tissues showed higher levels of target messenger ribonucleic acid (mRNA) (4.05 x 10(-2)pg/100 ng total RNA using the commercial kit and 6.45 x 10(-2)pg/100 ng total RNA using Trizol) in comparison to formalin-fixed tissues (5.69 x 10(-4)pg/100 ng total RNA). This could be attributed to RNA degradation by exposure to formalin fixation. In conclusion, the HOPE fixative proved to be a better source for RNA extraction from cattle lymph nodes and subsequent qRT-PCR.

Ensemble Feature Learning of Genomic Data Using Support Vector Machine.

The identification of a subset of genes having the ability to capture the necessary information to distinguish classes of patients is crucial in bioinformatics applications. Ensemble and bagging methods have been shown to work effectively in the process of gene selection and classification. Testament to that is random forest which combines random decision trees with bagging to improve overall feature selection and classification accuracy. Surprisingly, the adoption of these methods in support vector machines has only recently received attention but mostly on classification not gene selection. This paper introduces an ensemble SVM-Recursive Feature Elimination (ESVM-RFE) for gene selection that follows the concepts of ensemble and bagging used in random forest but adopts the backward elimination strategy which is the rationale of RFE algorithm. The rationale behind this is, building ensemble SVM models using randomly drawn bootstrap samples from the training set, will produce different feature rankings which will be subsequently aggregated as one feature ranking. As a result, the decision for elimination of features is based upon the ranking of multiple SVM models instead of choosing one particular model. Moreover, this approach will address the problem of imbalanced datasets by constructing a nearly balanced bootstrap sample. Our experiments show that ESVM-RFE for gene selection substantially increased the classification performance on five microarray datasets compared to state-of-the-art methods. Experiments on the childhood leukaemia dataset show that an average 9% better accuracy is achieved by ESVM-RFE over SVM-RFE, and 5% over random forest based approach. The selected genes by the ESVM-RFE algorithm were further explored with Singular Value Decomposition (SVD) which reveals significant clusters with the selected data.

Genetic diversity of Mycobacterium tuberculosis complex strains isolated from patients with pulmonary tuberculosis in Anambra State, Nigeria.

In this study, we analyzed Mycobacterium tuberculosis complex (MTC) genetic diversity in Anambra State, Nigeria based on spoligotyping followed by 5-loci exact tandem repeats (ETRs). Spoligotyping of 180 MTC strains isolated in 2009-2011 from pulmonary tuberculosis (TB) patients led to a total of 31 distinct patterns. A comparison with the SITVIT2 international database showed that all the 31 patterns could be classified as Shared-types (SITs) in this database; briefly, 26/31 SITs (n=174 isolates) matched a preexisting shared-type in the database, whereas 5/31 SITs (n=6 isolates) were newly created due to 2 or more strains belonging to an identical new pattern within this study (SIT3396) or after a match with an orphan in the database (SIT3397, SIT3398, SIT3399 and SIT3400). A total of 18/31 SITs containing 167 or 92.8% isolates were clustered within this study (2-89 isolates per cluster) while 13/31 SITs contained unique strains. Using VNTR typing, a total of 36 distinct patterns were identified; 27 patterns (n=157 isolates) matched a pattern already reported in the SITVIT2 database. Combination of both the methods generated 47 combined patterns for the 180 strains: 17 belonged to clustered isolates (n=127 isolates or 70.5%) while 30 corresponded to as many unique strains (note 23 strains could not be typed using 5-loci ETRs). No correlation was found between the spoligotyping pattern and the HIV status of the patient or drug sensitivity of the strain. This study showed that the LAM10-CAM prototype SIT61 accounted for highest number of isolates (n=89) in Anambra State, showing its relative contribution to the TB burden in the study.

Case-based retrieval framework for gene expression data.

BACKGROUND: The process of retrieving similar cases in a case-based reasoning system is considered a big challenge for gene expression data sets. The huge number of gene expression values generated by microarray technology leads to complex data sets and similarity measures for high-dimensional data are problematic. Hence, gene expression similarity measurements require numerous machine-learning and data-mining techniques, such as feature selection and dimensionality reduction, to be incorporated into the retrieval process. METHODS: This article proposes a case-based retrieval framework that uses a k-nearest-neighbor classifier with a weighted-feature-based similarity to retrieve previously treated patients based on their gene expression profiles. RESULTS: The herein-proposed methodology is validated on several data sets: a childhood leukemia data set collected from The Children's Hospital at Westmead, as well as the Colon cancer, the National Cancer Institute (NCI), and the Prostate cancer data sets. Results obtained by the proposed framework in retrieving patients of the data sets who are similar to new patients are as follows: 96% accuracy on the childhood leukemia data set, 95% on the NCI data set, 93% on the Colon cancer data set, and 98% on the Prostate cancer data set. CONCLUSION: The designed case-based retrieval framework is an appropriate choice for retrieving previous patients who are similar to a new patient, on the basis of their gene expression data, for better diagnosis and treatment of childhood leukemia. Moreover, this framework can be applied to other gene expression data sets using some or all of its steps.

Cytokine mRNA expression in cattle infected with different dosages of Mycobacterium bovis.

Cytokine mRNA expression of pro-inflammatory cytokines, i.e., interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha) and anti-inflammatory cytokines, i.e., interleukin-4 (IL-4), interleukin-10 (IL-10) was quantified using quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) in cattle infected with different doses (1-1000 colony-forming units (cfu)) of Mycobacterium bovis. RNA was extracted from the Hepes glutamic acid buffer mediated organic solvent protection effect (HOPE) fixed lymph node tissues using Trizol method. The expression levels of all the four cytokines gradually increased in cattle infected with 1 cfu-1000 cfu. Statistical significance (P<0.05) was observed for the cytokines IFN-gamma, IL-4 and IL-10 between the cattle infected with 1 cfu and 1000 cfu. Though there was an increase in the expression levels of TNF-alpha from cattle infected with 1 cfu-1000 cfu, this difference in expression was not statistically significant (P>0.05). The increase in the levels of IFN-gamma indicates that the host may be responding to control the infection and the increased level of IL-4 and IL-10 which are anti-inflammatory cytokines, suggests that these cytokines are trying to protect the host by reducing the inflammation and also by controlling the levels of TNF-alpha (the cytokine that may cause tissue damage).

Comparison between spoligotyping and IS6110 restriction fragment length polymorphisms in molecular genotyping analysis of Mycobacterium tuberculosis strains.

Spoligotyping was compared with RFLP fingerprinting analysis in the identification of Mycobacterium tuberculosis strains. Spoligotyping sensitivity was 97.6% with a specificity of 47%. The global probability for two strains clustered with spoligotyping to be clustered also with RFLP analysis was 33%; the probability for two strains clustered with RFLP analysis to be clustered also with spoligotyping analysis was 95%. However, comparing the two methods in five outbreak episodes, full concordance was evidenced between spoligotyping and RFLP. Moreover, we evaluated the presence of our 17 largest spoligotyping clusters in spoligotyping databases from Caribbean countries, London and Cuba. Only five out of 17 patterns were present in all the cohorts. The conditional probability comparing spoligotyping and RFLP methods related to these patterns resulted in very low concordance (range from 2 to 38%). In conclusion, we confirm that spoligotyping when used alone overestimates the number of recent transmission and does not represent a suitable method for wide clinical practice application. However, it allows to get a first good picture of strain identity in a new setting and in more localized or confined settings, the probability of reaching the same result compared to RFLP was 100% confirming the usefulness of spoligotyping in the management of epidemic events, especially in hospitals, prisons and close communities.

Experimental versus in silico fluorescent amplified fragment length polymorphism analysis of Mycobacterium tuberculosis: improved typing with an extended fragment range.

Whole-genome fingerprinting fluorescent amplified fragment length polymorphism (FAFLP) data were compared with in silico data for the sequenced strains of Mycobacterium tuberculosis (H37Rv and CDC1551). For this G+C-rich genome, many predicted fragments were not detected experimentally. For H37Rv, only 108 (66%) of the 163 predicted EcoRI-MseI fragments between 100 and 500 bp were visualized in vitro. FAFLP was also used to identify polymorphism in 10 clinical isolates of M. tuberculosis characterized previously by IS6110 typing, examining fragments of up to 1,000 bp in size rather than up to 500 bp as was done previously. Five isolates had unique IS6110 profiles and were not known to be epidemiologically related, two isolates were the same single-band IS6110 type but were not known to be epidemiologically related, and the remaining three isolates were epidemiologically related with identical IS6110 profiles. Analysis of fragments in the 500- to 1,000-bp range using nonselective primers differentiated better between strains than analysis of fragments in the 50- to 500-bp range using a set of four selective primers. Seventeen polymorphic fragments were identified between 500 and 1,000 bp in size compared with nine polymorphic fragments between 50 and 500 bp. Using the 500- to 1,000-bp analysis, a level of discrimination similar to that of IS6110 typing was achieved which, unlike the IS6110 typing, was able to differentiate the two M. tuberculosis strains, each of which had only a single copy of IS6110.