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Biomedical subjects

M Maher

Publications and source records attributed to M Maher.

At least 37 records · Page 2Linked to original sources
PubMed2001

Evaluation of clarithromycin resistance and cagA and vacA genotyping of Helicobacter pylori strains from the west of Ireland using line probe assays.

The prevalence of clarithromycin resistance-associated mutations, the cytotoxin-associated gene (cagA), and the various vacuolating cytotoxin (vacA) genotypes was determined in 50 gastric biopsy specimens from Helicobacter pylori-infected patients, using line probe assays. The clarithromycin resistance-associated mutation A2143G was detected in H. pylori strains from 26% of the specimens, which suggested that the high rate of H. pylori treatment failure in Ireland may be partly attributable to the presence of these mutations. All strains examined carried the vacA s1 genotype, and 76% were cagA positive. Of these 50 specimens, 13 (26%) carried H. pylori strains with vacA midregion genotype m1, 29 (58%) carried strains that were m2, 1 (2%) was infected by a strain that was positive for both m1 and m2, and 7 (14%) carried strains that could not be typed.

Anti-Bacterial Agents↗
PubMed2001

PCR-ELISAs for the detection of Campylobacter jejuni and Campylobacter coli in poultry samples.

Campylobacter species, primarily Campylobacter jejuni and Campylobacter coli, are regarded as a major cause of human gastrointestinal disease, commonly acquired by eating undercooked chicken. We describe a PCR-ELISA for the detection of Campylobacter species and the discrimination of C. jejuni and C. coli in poultry samples. The PCR assay targets the 16S/23S ribosomal RNA intergenic spacer region of Campylobacter species with DNA oligonucleotide probes designed for the specific detection of C. jejuni, C. coli, and Campylobacter species immobilized on Nucleo-Link wells and hybridized to PCR products modified with a 5' biotin moiety. The limit of detection of the PCR-ELISA was 100-300 fg (40-120 bacterial cells) for C. jejuni and C. coli with their respective species-specific oligonucleotide probes and 10 fg (4 bacterial cells) with the Campylobacter genus-specific probe. Testing of poultry samples, which were presumptive positive for Campylobacter following culture on the Malthus V analyzer, with the PCR-ELISA determined Campylobacter to be present in 100% of samples (n = 40) with mixed cultures of C. jejuni/C. coli in 55%. The PCR-ELISA when combined with culture pre-enrichment is able to detect the presence of Campylobacter and definitively identify C. jejuni and C. coli in culture-enriched poultry meat samples.

Animals↗
PubMed2001

[Pulmonary metastasis from a glioblastoma. A case report].

Glioblastoma is a primary malignant astrocyte tumor of the central nervous system. Extraneural metastasis is uncommon. We report a case of spontaneous lung metastasis from a glioblastoma without prior surgery. Positive diagnosis was achieved from histology and immunohistochemistry

Adult↗
PubMed2001

Power Doppler ultrasound assessment of rheumatoid hand synovitis.

OBJECTIVE: To evaluate power Doppler ultrasound (PD) as a technique in assessing response to treatment with steroids in rheumatoid hand synovitis. METHODS: Twelve patients with rheumatoid hand synovitis were assessed before and after treatment with steroids. Variables used to assess synovitis activity in each patient included patient visual analog scale (VAS) score for pain, physician assessment score (PAS), erythrocyte sedimentation rate (ESR), and PD of the metacarpophalangeal joints. RESULTS: Nine female and 3 male patients were studied; mean age was 53.3+/-6.5 yrs and mean disease duration 6.5+/-4.5 yrs. All patients had a good clinical response to steroid treatment and there was a significant improvement in the synovitis activity assessments. Wilcoxon signed-rank test using the exact method was applied to the change in disease activity variables. For PD signal, p < 0.002; VAS, p < 0.0016; ESR, p < 0.031; PAS, p < 0.008. CONCLUSION: PD quantifies synovitis and may be a useful adjunct to disease assessment and the response to treatment in RA.

Adult↗
PubMed2001

Central nervous system tumors in Morocco. Retrospective analysis of 2374 cases.

BACKGROUND: No epidemiological data about central nervous system tumors in Morroco have been published. The objective of the present study is to assess topographic and demographic patterns of a large series of histologically confirmed tumors of central nervous system (CNS), skull and vertebral column, examined in the main neuropathology laboratory of the country. METHODS: No. 2363 tumors have been collected in the department of Neuropathology in Hôpital des spécialités oto-neuro-ophtalmiques, Rabat, between 1988 and 1997. Data concerning age, sex, tumor location and histological type were retrieved from the laboratory files. Histological typing was based on the World Health Organization (WHO) classification of central nervous system tumors and grading on the Kernohan and Mayo Clinic-St. Anne systems. RESULTS: No. 1454 intraparenchymatous and 904 extraparenchymatous tumors were studied. The topographic repartition of these tumors presented no differences when compared to the literature data. The main differences were noted for malignant astrocytomas and glioblastomas which were less frequent than in Western countries and occurred in younger people. The young age of Morrocan population probably explains these findings. Childhood tumors repartition was similar to Western series. CONCLUSIONS: These results emphazise the need for a population based registry in order to verify our findings and adapt efficient health intervention.

Adult↗
PubMed2000

Detection and differentiation of Campylobacter jejuni and Campylobacter coli in broiler chicken samples using a PCR/DNA probe membrane based colorimetric detection assay.

Campylobacter enteritis in humans has been linked to consumption of poultry meat. Surveys show that 30-100% of poultry harbour Campylobacter as normal flora of the digestive tract which indicates a need to identify prevalent organism types in flocks and trace their epidemiology. In this study we describe a Campylobacter genus specific polymerase chain reaction (PCR) assay, amplifying the 16 S-23 S rRNA intergenic spacer region with an internal Campylobacter genus specific DNA probe and species specific probes for Campylobacter jejuni and Campylobacter coli designed for confirmation of the amplified PCR products by Southern blot and colorimetric reverse hybridization assays. The specificity of this assay was established by testing a range of food pathogens. Broiler chicken samples were tested following presumptive positive identification by the Malthus System V analyser (Malthus Instruments, UK). The combined PCR and colorimetric reverse hybridization assay is easy to perform and faster than conventional methods for confirmation and identification of Campylobacter species.

Animals↗
PubMed2000

Genotyping of cagA and vacA, Lewis antigen status, and analysis of the poly-(C) tract in the alpha(1,3)-fucosyltransferase gene of Irish Helicobacter pylori isolates.

Much work has focused on trying to identify markers in Helicobacter pylori that might allow the eventual disease outcome of an infection to be predicted. In this study we examined the cagA and vacA genotype, and Lewis status in a panel of 43 Irish H. pylori clinical isolates, and investigated a possible correlation with disease pathology. In addition, differences in the poly-(C) tract of the alpha(1,3)-fucosyltransferase gene were examined to identify a possible correlation with gene expression. Only three of 43 isolates were cagA-negative, whereas the remaining 40 isolates, independent of pathology, were cagA-positive. In all the strains we examined, the vacA signal-sequence was type s1a. For the vacA mid-region 12/43 isolates were type m1 and 31/43 isolates were type m2. These data, and examination of isolates from different pathology groups, suggests that there is no correlation between virulence and vacA genotype in the Irish population of H. pylori isolates. Western blotting of whole cell lysates from 32 H. pylori isolates showed 3/32 displayed only the Le(x) epitope, 12/32 only the Le(y), 13/32 both epitopes and 4/32 neither epitope. No apparent association between Lewis phenotype and disease pathology was evident. A range of lengths of poly-(C) tract were observed in the alpha(1, 3)-fucosyltransferase gene, however the length of the tract in an isolate did not correlate with the Lewis structures present. We conclude that future studies on H. pylori pathogenesis should not alone focus on the importance of molecular markers, but also on the host response, including genetic background and immune responsiveness.

Antigens, Bacterial↗
PubMed2000

Development of a PCR-based line probe assay for identification of fungal pathogens.

We report on a reverse-hybridization line probe assay (LiPA) which when combined with PCR amplification detects and identifies clinically significant fungal pathogens including Candida, Aspergillus, and Cryptococcus species. DNA probes have been designed from the internal transcribed-spacer (ITS) regions of Candida albicans, Candida parapsilosis, Candida glabrata, Candida tropicalis, Candida krusei, Candida dubliniensis, Cryptococcus neoformans, Aspergillus fumigatus, Aspergillus versicolor, Aspergillus nidulans and Aspergillus flavus. The probes were incorporated into a LiPA for detection of biotinylated ITS PCR products, and the specificity of the probes was evaluated. We established LiPA detection limits for ITS 1 and for full ITS amplicons for genomic DNA from C. albicans, A. fumigatus, and C. neoformans. Further evaluation of the LiPA was carried out on clinical fungal isolates. One hundred twenty-seven isolates consisting of dimorphic yeasts and dermatophytic and filamentous fungi were tested by the LiPA, which correctly identified 77 dimorphic yeasts and 23 of the filamentous isolates; the remaining 27 isolates represented species of fungi for which probes were not included in the LiPA. The fungal-PCR-LiPA technology was applied to blood samples inoculated with Candida cells which were pretreated by minibead beating to mechanically disrupt the cells, with the DNA extracted by either a previously described guanidium thiocyanate-silica method or the commercially available QIAmp tissue kit. PCR amplification of the extracted DNA and subsequent DNA probe hybridization in the LiPA assay yielded detection limits of 2 to 10 cells/ml. An internal standard control was included in the PCR amplification to monitor for PCR inhibition. This fungal PCR-LiPA assay is robust and sensitive and can easily be integrated into a clinical-testing laboratory with the potential for same-day diagnosis of fungal infection.

DNA Primers↗
PubMed2000

Rapid polymerase chain reaction/DNA probe membrane-based assay for the detection of Listeria and Listeria monocytogenes in food.

We describe the development of polymerase chain reaction (PCR)/DNA probe membrane-based colorimetric assays for the detection and identification of Listeria and L. monocytogenes. PCR primers designed from the 16S to 23S rRNA intergenic spacer region amplified products that were reverse hybridized to membrane-bound oligonucleotide probes specific for Listeria and L. monocytogenes with a detection limit of 1 to 10 CFU/25 ml in inoculated raw and pasteurized milk samples. These qualitative assays have the potential to be integrated into testing laboratories for monitoring the microbiological quality of foods.

Animals↗
PubMed2000

Desmoplastic non-infantile ganglioglioma. Case report.

Desmoplastic gangliogliomas are rare mixed glial and neuronal cerebral tumors, especially described in infants below 4 years of age but exceptional cases have been reported in young adults. These tumors are generally localised in parietal or temporal lobes, present as a large cystic lesion with peripheral contrast enhancement. They also have characteristic histological features: extensive desmoplasia and tumoral cells of variable size exhibiting immunohistochemical and ultrastructural features of glial and neuronal differentiation. Total surgical removal is sufficient for the treatment of these tumors and no radiotherapy or chemotherapy are indicated if complete resection is achieved. We report a case of desmoplastic ganglioglioma in a 19-year-old male. This tumor presented as a large parieto- temporal cystic lesion with rimmed contrast enhancement. At histological examination, this tumor exhibited extensive desmoplasia and comprised 2 types of tumoral cells: small cells with round nuclei, positive for NSE, neurofilaments and synaptophysin and sometimes presenting typical morphological features of neuronal differentiation, and large cells with abundant eosinophilic strongly staining for GFAP. This observation emphazises on the fact that desmoplastic ganglioglioma can no more be considered as a specific entity of infancy and must be well recognised even in young adults because it may be misdiagnosed as malignant glioma.

Adult↗
PubMed1999

Microsatellite instability in sporadic colorectal carcinoma is not an indicator of prognosis.

Fifty sporadic colorectal carcinomas diagnosed in 1991 were analysed for microsatellite instability at four loci. Five of 50 (10 per cent) tumours showed replication errors (RERs) at two or more loci and were classed as RER-positive (RER+). A further five showed RERs at one locus only. A significant association (Fisher exact test) was found between RER+ tumours and location in the proximal colon, exophytic shape, size >5 cm, histological margin, lymphoid reaction, and near-diploid DNA content. There was no significant difference for age, sex, grade, mucin production, p53 protein overexpression or Duke's stage. There was no significant difference in survival as measured over a 60-month follow-up period. The findings, though limited by the small case numbers involved, show an association between RER positivity in sporadic colorectal tumours and certain clinico-pathological features. They do not suggest a better clinical outcome for sporadic RER+ tumours.

Adenocarcinoma↗
PubMed1999

Relative validity of a food frequency questionnaire among tin miners in China: 1992/93 and 1995/96 diet validation studies.

OBJECTIVE: Diet validation research was conducted to compare the respondents' reporting of dietary intake in a food frequency questionnaire (FFQ) with intake reported in food recalls. Because the population received annual salary increments that could modify food intake, diet validation studies (DVSs) were conducted during two time intervals. DESIGN: A 99-item FFQ was administered by an interviewer twice in a 1-year interval, and responses to each FFQ item were compared with 28 days of interviewer-administered food recalls that were collected in four 1-week intervals during each season of 1992/93. The second validation study in 1995/96 had a similar design to the earlier one. SETTING: A prospective cohort study of lung cancer among tin miners in China was initiated in 1992, with dietary and other risk factors updated annually. SUBJECTS: Among a cohort of high risk tin miners for lung cancer, two different samples (n = 141 in 1992/93, and n = 113 in 1995/96) for each diet validation study were randomly selected from four mine units, that were representative of all worker units. RESULTS: Miners reported a significantly higher average frequency of intake of foods in the food recalls than the FFQ, with few exceptions. Deattenuated Pearson correlation coefficients of the frequency of food intake between the FFQ and food recalls were in the range of -0.40 to 0.72 in both studies, with higher positive correlations for beverages and cereal staples than for animal protein sources, vegetables, fruits and legumes. The percentage of individuals with exact agreement in the extreme quartiles of intake in the food recalls and FFQ ranged from 0 to 100% in both studies. CONCLUSIONS: Among Chinese miners, the range in correlations between the food recalls and the FFQ were due to: (i) market availability of foods during the food recall weeks compared to their annual reported intake in the FFQ; (ii) cultural perception of time; and (iii) differences in how the intake of mixed dishes and their multi-ingredient foods were reported in the recalls vs. the FFQ. The range in the percentage of agreement in the same quartiles and the changes in food intake over time may have implications for the analysis of the diet-disease relationship in this cohort.

Analysis of Variance↗
PubMed1998

Construction, expression, and characterization of a novel fully activated recombinant single-chain hepatitis C virus protease.

Efficient proteolytic processing of essential junctions of the hepatitis C virus (HCV) polyprotein requires a heterodimeric complex of the NS3 bifunctional protease/helicase and the NS4A accessory protein. A single-chain recombinant form of the protease has been constructed in which NS4A residues 21-32 (GSVVIVGRIILS) were fused in frame to the amino terminus of the NS3 protease domain (residues 3-181) through a tetrapeptide linker. The single-chain recombinant protease has been overexpressed as a soluble protein in E. coli and purified to homogeneity by a combination of metal chelate and size-exclusion chromatography. The single-chain recombinant protease domain shows full proteolytic activity cleaving the NS5A-5B synthetic peptide substrate, DTEDVVCCSMSYTWTGK with a Km and k(cat) of 20.0 +/- 2.0 microM and 9.6 +/- 2.0 min(-1), respectively; parameters identical to those of the authentic NS3(1-631)/NS4A(1-54) protein complex generated in eukaryotic cells (Sali DL et al., 1998, Biochemistry 37:3392-3401).

Amino Acid Sequence↗
PubMed1998

The influence of trend on estimates of accidents at junctions.

While reliable estimates of expected accidents can be achieved by combining observed accidents and accident model predictions using an empirical Bayes approach, there are a number of obstacles to the widespread adoption of the method. This paper concentrates on problems associated with the available predictive models. Of particular concern is the effect on model predictions of accident trends over time resulting from, for instance, traffic growth or national road safety programmes. Since accident models invariably include traffic flow as an explanatory variable, the effects of flow changes can be included provided that account is taken of the nonlinear relationship between accidents and exposure. It is, however, common to assume that accident risk per unit of exposure is constant over time, whereas national data imply that accident risk is declining. In addition, there is a need, in practice, to rank and evaluate remedial sites in terms of the specific accident types or severities which might be targeted by treatment (for example, wet road accidents in the case of surface treatment). This then raises the question of whether the proportions of accidents of various types varies over time or with traffic flow and site characteristics. Generalized linear modelling was used to develop regression estimates of expected junction accidents (both in total and disaggregated by severity, road surface condition and lighting condition) which allow for the possibility of accident risk varying over time. Accident risk at the sample of some 500 junctions was shown to be declining annually by an average of 6%, with no significant difference in the value of trend between accident types. The factors which affected the proportions of accidents of various types included the method of junction control, speed limit and traffic flow.

Accidents, Traffic↗