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M Callanan

Publications and source records attributed to M Callanan.

12 recordsLinked to original sources
PubMed1996

Regulation of the iron uptake genes in Pseudomonas fluorescens M114 by pseudobactin M114: the pbrA sigma factor gene does not mediate the siderophore regulatory response.

The iron-regulated PbrA sigma factor dictates the production of the siderophore, pseudobactin M114, and its cognate outer membrane receptor, PbuA, in Pseudomonas fluorescens M114. However, the siderophore molecule also has a role in regulating the expression of the siderophore biosynthetic and siderophore receptor genes in P. fluorescens M114. This is based on the fact that beta-galactosidase levels from lacZ fusions of M114 siderophore promoters (biosynthetic and receptor) were reduced in M114 siderophore biosynthetic mutants compared to wild-type M114. Expression of both promoters was increased by the addition of pseudobactin M114 to the growth medium. This effect was widespread and applicable to all but one of the siderophore negative strains of M114 tested. Furthermore, it was demonstrated that transcription of the pbr A sigma factor gene was not reduced in the siderophore biosynthetic mutants. This excludes the possibility that reduced expression of the siderophore biosynthetic and receptor promoters in the siderophore biosynthetic mutants is mediated at the level of expression of the pbr A gene itself. In addition, it was noted that the siderophore regulated response was applicable to promoters with and without the DNA sequence motif, (G/C)CTAAATCCC, which is required for iron-regulated expression of some pseudomonad promoters.

Bacterial Proteins↗
PubMed1996

Molecular diagnosis of t(11;14) in mantle cell lymphoma using two-colour interphase fluorescence in situ hybridization.

t(11;14) is observed in up to 70% of mantle cell lymphoma (MCL) cases and is therefore an important diagnostic element. In routine practice, detection of t(11;14) by conventional cytogenetic techniques is hindered by the low yield and quality of tumour metaphases. Molecular techniques (Southern blot, PCR) are unable to detect a large number of 11q13 breakpoints due to scattering over distances up to 1 Mb. Using 23 MCL patients with karyotypically determined t(11;14) and eight negative controls, we have devised a two-colour interphase FISH assay for detection of the 14q + chromosome. We chose an 11q13 probe telomeric to the major 11q13 translocation cluster sites and an IGH probe centromeric of the 14q32 breakpoints. This method detected the translocation in all 23 t(11;14) positive patients, with an overall average of 60% nuclei showing colocalized signals. Widespread application of this technique will constitute an important diagnostic aid in clinical management of MCL patients. Since FISH is a convenient method for retrospective analysis of large numbers of patient specimens, this method should contribute to an accurate estimation of t(11;14) frequency in MCL and other chronic B-cell malignancies and consequently to their better nosological characterization.

Chromosomes, Human, Pair 11↗
PubMed1995

Construction of a rhizosphere pseudomonad with potential to degrade polychlorinated biphenyls and detection of bph gene expression in the rhizosphere.

The genetically engineered transposon TnPCB, contains genes (bph) encoding the biphenyl degradative pathway. TnPCB was stably inserted into the chromosome of two different rhizosphere pseudomonads. One genetically modified strain, Pseudomonas fluorescens F113pcb, was characterized in detail and found to be unaltered in important parameters such as growth rate and production of secondary metabolites. The expression of the heterologous bph genes in F113pcb was confirmed by the ability of the genetically modified microorganism to utilize biphenyl as a sole carbon source. The introduced trait remained stable in laboratory experiments, and no bph-negative isolates were found after extensive subculture in nonselective media. The bph trait was also stable in nonselective rhizosphere microcosms. Rhizosphere competence of the modified F113pcb was assessed in colonization experiments in nonsterile soil microcosms on sugar beet seedling roots. F113pcb was able to colonize as efficiently as a marked wild-type strain, and no decrease in competitiveness was observed. In situ expression of the bph genes in F113pcb was found when F113pcb bearing a bph'lacZ reporter fusion was inoculated onto sugar beet seeds. This indicates that the bph gene products may also be present under in situ conditions. These experiments demonstrated that rhizosphere-adapted microbes can be genetically manipulated to metabolize novel compounds without affecting their ecological competence. Expression of the introduced genes can be detected in the rhizosphere, indicating considerable potential for the manipulation of the rhizosphere as a self-sustaining biofilm for the bioremediation of pollutants in soil. Rhizosphere bacteria such as fluorescent Pseudomonas spp. are ecologically adapted to colonize and compete in the rhizosphere environment. Expanding the metabolic functions of such pseudomonads to degrade pollutants may prove to be a useful strategy for bioremediation.

Bacterial Proteins↗
PubMed1995

Effect of sucralfate on Helicobacter pylori and severity of gastritis in patients with duodenal ulcer.

BACKGROUND: Duodenal ulcer relapse rates have been reported to be lower following healing with sucralfate. The question arises whether this is related to an effect on Helicobacter pylori. METHODS: In order to investigate this possibility, 43 patients with active duodenal ulcer were entered into a study. Endoscopy was performed at entry, following 6 weeks' treatment with sucralfate 1 g q.i.d., and at 4 and 12 weeks of post-documented healing. Antral and gastric corpus biopsies were taken for assessment of H. pylori status (CLOtest), density of infection, and severity of gastritis. In addition, 14C urea breath tests (UBT) were performed. RESULTS: Sucralfate therapy induced a significant decrease in the density of H. pylori infection, with a trend to improvement of the gastritis in the antrum, but not in the corpus. However, all patients remained CLOtest positive, and the overall gastric urease activity was unchanged following therapy. These effects did not appear to influence either initial duodenal ulcer healing or subsequent relapse rates. CONCLUSION: Sucralfate has a suppressive effect on H. pylori infection in the gastric antrum but the clinical relevance of this is uncertain.

Adolescent↗
PubMed1994

Back from 'beyond'.

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Attitude to Death↗
PubMed1994

Breaking the silence.

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Adaptation, Psychological↗
PubMed1987

Magnetic resonance imaging after corpus callosotomy.

Magnetic resonance imaging (MRI) can visualize the extent of corpus callosotomy performed for medically intractable epilepsy not amenable to focal surgery. Five patients underwent complete callosotomy and one an anterior callosotomy, aged 19 to 24 years, 21 to 53 months (prior to scanning). T1 images showed complete absence of the callosal shadow in five cases and visualization of the genu and splenium in the sixth case. T2-weighted pulse sequence spin-echo MRI showed intense image throughout the region of the entire callosum in the two cases with the longest postoperative course. The two middle cases showed intense T2 signal from the splenium, and the two latest showed no increase in T2 signal. We believe the increase in T2 signal in the transected callosum may represent an in vivo example of anisomorphic gliosis. T1 images demonstrate the anatomic extent of transection, while T2 images demonstrate the chemical and pathophysiologic sequence of transection. Thus, MRI is the imaging test of choice to evaluate callosotomy patients.

Adolescent↗
PubMedDate not supplied

Aura phenomena and psychopathology: a pilot investigation.

We investigated a possible relation between aura phenomena and psychopathology in patients with seizure disorders. Twenty-one patients with a variety of seizure types (90% with generalized seizures, 72% with complex partial seizures, CPS) were studied. Aura phenomena were evaluated with the Silberman-Post Psychosensory Phenomena Scale; psychopathology was assessed with the Schedule for Affective Disorders and Schizophrenia-Lifetime Version (SADS-L), the Minnesota Multiple Personality Inventory (MMPI), and the Washington Psychosocial Seizure Inventory (WPSI). Psychosensory symptoms occurring in the absence of frank seizures, but not those occurring with seizures, were related to increased psychopathology (primarily mood and anxiety related) and greater time in psychiatric treatment. Psychosensory symptoms may reflect ongoing neurophysiologic dysfunction related to epilepsy and may therefore be a useful subject for further study.

Adaptation, Psychological↗