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Biomedical subjects

C Flaherty

Publications and source records attributed to C Flaherty.

18 recordsLinked to original sources
PubMed2001

Galactan biosynthesis in Mycobacterium tuberculosis. Identification of a bifunctional UDP-galactofuranosyltransferase.

The cell wall of Mycobacterium tuberculosis and related genera is unique among prokaryotes, consisting of a covalently bound complex of mycolic acids, D-arabinan and D-galactan, which is linked to peptidoglycan via a special linkage unit consisting of Rhap-(1-->3)-GlcNAc-P. Information concerning the biosynthesis of this entire polymer is now emerging with the promise of new drug targets against tuberculosis. Accordingly, we have developed a galactosyltransferase assay that utilizes the disaccharide neoglycolipid acceptors beta-d-Galf-(1-->5)-beta-D-Galf-O-C(10:1) and beta-D-Galf-(1-->6)-beta-D-Galf-O-C(10:1), with UDP-Gal in conjunction with isolated membranes. Chemical analysis of the subsequent reaction products established that the enzymatically synthesized products contained both beta-D-Galf linkages ((1-->5) and (1-->6)) found within the mycobacterial cell, as well as in an alternating (1-->5) and (1-->6) fashion consistent with the established structure of the cell wall. Furthermore, through a detailed examination of the M. tuberculosis genome, we have shown that the gene product of Rv3808c, now termed glfT, is a novel UDP-galactofuranosyltransferase. This enzyme possesses dual functionality in performing both (1-->5) and (1-->6) galactofuranosyltransferase reactions with the above neoglycolipid acceptors, using membranes isolated from the heterologous host Escherichia coli expressing Rv3808c. Thus, at a biochemical and genetic level, the polymerization of the galactan region of the mycolyl-arabinogalactan complex has been defined, allowing the possibility of further studies toward substrate recognition and catalysis and assay development. Ultimately, this may also lead to a more rational approach to drug design to be explored in the context of mycobacterial infections.

Bacterial Proteins↗
PubMed1999

Identification of a lipoarabinomannan-like lipoglycan in Gordonia rubropertincta.

Lipoarabinomannans are well characterised lipoglycans present in the cell envelopes of mycobacteria and closely related bacteria. To define further the distribution of these lipoglycans we have investigated the mycolic acid-containing bacterium Gordonia rubropertincta and, by analysis of carbohydrate composition and antigenic cross-reactivity, demonstrated the presence of a lipoarabinomannan-like lipoglycan. A fraction that appeared to contain higher phosphatidylinositolmannosides was also isolated.

Actinomycetales↗
PubMed1998

Temporal dynamics of corticosterone elevation in successive negative contrast.

A negative contrast effect in consummatory behavior that occurred when rats were shifted from 32% to 4% sucrose was accompanied by elevations in corticosterone that were measurable at 10 and 20 min but not at 40 min after the second postshift day. No corticosterone elevations were found to accompany contrast at 10 or 15 min after the first postshift day in these experiments nor immediately after the first postshift day in an earlier experiment. The present study also found an anticipatory elevation in plasma corticosterone in shifted animals just before their placement in the apparatus on the second postshift day. These results are discussed in terms of a multistage hypothesis of successive negative contrast. The anticipatory elevation is discussed in terms of uncontrollability and unpredictability of aversive events.

Animals↗
PubMed1996

A chemotaxonomic study of the lipoglycans of Rhodococcus rhodnii N445 (NCIMB 11279).

Rhodococcus rhodnii N445 was investigated for the presence of macroamphiphilic lipoglycan. Purification of a hot phenol-water extract by hydrophobic interaction chromatography allowed the resolution of three lipoglycan fractions. The two main preparations contained lipoglycans with carbohydrate compositions consistent with the presence of lipoarabinomannan and lipomannan, whilst the minor fraction appeared to contain a mixture of these two lipoglycans. The fatty acid composition of the lipoglycans resembled that of the whole cells except that the relative proportion of unsaturated fatty acids was decreased. Although lipoarabinomannan and structurally-related lipomannan lipoglycans from representatives of the genus Mycobacterium have been extensively studied, this is the first report of the lipoglycan composition of a representative of the genus Rhodococcus as presently defined. These findings provide further chemotaxonomic evidence that lipoarabinomannan-type lipoglycans are widely distributed throughout the mycolic acid-containing actinomycetes.

Lipopolysaccharides↗
PubMed1993

Photodynamic action of aluminium phthalocyanine tetrasulphonate (A1PcS4) on smooth muscle: effects of thiols and a cyclic GMP analogue.

1. The smooth muscle system of the guinea-pig taenia caeci has been used in vitro to characterize the photodynamic action of aluminium phthalocyanine tetrasulphonate (A1PcS4) in the presence or absence of the thiol reductants L-cysteine (Cys), N-acetyl-L-cysteine (NAC), DL-dithiothreitol (DTT) or reduced glutathione (GSH). 2. In all photodynamic experiments the muscle was exposed to A1PcS4 (10(-5) M) for 30 min, followed by a 30 min washout period before photon irradiation at 32,000 lux (lambda > 570 nm) for 30 min. Photodynamic contractions were measured relative to the contractile response to carbachol (5 x 10(-5) M) and relaxation responses were determined in muscle precontracted with either carbachol 5 x 10(-5) M or KCl 23.5 mM. 3. Photon-activation of A1PcS4-sensitized smooth muscle evoked a triphasic response: an initial transient contraction and subsequent relaxation followed by a secondary sustained contraction. Cys 10 mM, NAC 10 mM and DTT 5 mM had no effect on the initial photodynamic contraction but significantly decreased the magnitude of the sustained contraction from mean values of 98% to 18%, 95% to 72% and 93% to 6% of the standard carbachol contraction (5 x 10(-5) M), respectively; GSH 10 mM was without significant effect on either the initial or sustained contraction. 4. In the absence of extracellular calcium the A1PcS4-sensitized smooth muscle did not respond to photon activation but re-introduction of calcium after cessation of illumination produced a sustained contraction which was markedly inhibited by Cys 10 mM. 5. In precontracted AlPcS4-treated muscle preparations photon activation produced a triphasic relaxation response, i.e. a rapid relaxation followed by a transient contraction and a secondary more sustained relaxation. The sustained phase of photodynamic relaxation was potentiated significantly by Cys 10 mM,NAC 10 mM, DTT 5 mM and GSH 10 mM, the relaxation being approximately doubled in magnitude from mean values of 34% to 68%, 30% to 73%, 34% to 68%, and 48% to 77%, respectively, relative to the standard carbachol (5 x l0-5 M) response.6. The cyclic GMP analogue, 8-(4-chlorophenylthio)-guanosine-3':5'-cyclic monophosphate (8-PCPTcGMP)(2 x 10-4 M) alone caused a triphasic relaxation response similar to that produced by photon activation of an AIPcS4-sensitized precontracted preparation in the presence of thiol reductants. The pattern of 8-PCPT-cGMP-induced relaxation was similar in muscle precontracted with carbachol 5 x 10-5M or KCI 23.5 mM.7. It is concluded that the rapid generation of reactive intermediates by photon-activation of boundAlPcS4 leads to membrane permeabilization, calcium entry and muscle contraction. These effects may be opposed by a direct stimulatory action of singlet oxygen on guanylate cyclase which is enhanced by the action of thiol reagents and mimicked by the cyclic GMP analogue, 8-PCPT-cGMP.

Animals↗
PubMed1992

AraC protein contacts asymmetric sites in the Escherichia coli araFGH promoter.

AraC protein regulates the transcription of arabinose transport and catabolic operons in Escherichia coli through interaction with specific DNA sequences in the promoter regions of the operons. The interaction of AraC protein with two binding sites in the araFGH promoter was determined and compared to previously studied AraC binding sites in the araBAD promoter. Methylation and ethylation interference assays show that AraC protein binds along one side of the DNA to four adjacent major groove regions at each of the araFG1 and araFG2 sites. Mutations within any of the four regions of araFG1 greatly reduce protein binding in vitro. The promoter function in vivo is also greatly reduced, indicating that all four regions of the binding site are required. The chemical interference and genetic data, combined with the consensus sequence for AraC protein binding to ara promoters, support a binding motif in which two directly repeated units each span two adjacent turns of the DNA helix. The function of the two AraC binding sites was also examined. The proximal araFG1 site is required for promoter activation, whereas the distal araFG2 site has only a slight effect on the promoter activity.

Alkylation↗
PubMed1992

Sequence elements in the Escherichia coli araFGH promoter.

The Escherichia coli araFGH operon codes for proteins involved in the L-arabinose high-affinity transport system. Transcriptional regulation of the operon was studied by creating point mutations and deletions in the control region cloned into a GalK expression vector. The transcription start site was confirmed by RNA sequencing of transcripts. The sequences essential for polymerase function were localized by deletions and point mutations. Surprisingly, only a weak -10 consensus sequence, and no -35 sequence is required. Mutation of a guanosine at position -12 greatly reduced promoter activity, which suggests important polymerase interactions with DNA between the usual -10 and -35 positions. A double mutation toward the consensus in the -10 region was required to create a promoter capable of significant AraC-independent transcription. These results show that the araFGH promoter structure is similar to that of the galP1 promoter and is substantially different from that of the araBAD promoter. The effects of 11 mutations within the DNA region thought to bind the cyclic AMP receptor protein correlate well with the CRP consensus binding sequence and confirm that this region is responsible for cyclic AMP regulation. Deletion of the AraC binding site nearest the promoter, araFG1, eliminates arabinose regulation, whereas deletion of the upstream AraC binding site, araFG2, has only a slight effect on promoter activity.

Arabinose↗
PubMed1992

Dysfunctional grieving.

Dysfunctional grieving represents a failure to follow the predictable course of normal grieving to resolution (Lindemann, 1944). When the process deviates from the norm, the individual becomes overwhelmed and resorts to maladaptive coping. The process implies movement toward assimilation to or accommodation of the loss, resulting in progression toward social, psychological, and medical morbidity. Nurses will better assess the needs of the client with adequate information about the client's recent losses and perception of those losses. Such an assessment, in conjunction with an understanding of the signs, symptoms, and predisposing factors of complicated bereavement, will enable the nurse to develop a plan of effective intervention. Both case examples illustrate unresolved grief. In Case Example 1, the patient denied the importance of the relationship, which became masked with displaced anger and therefore delayed the grieving process. In Case Example 2, the patient's attempts at grieving over the loss of her son were complicated by her long-standing struggle with her husband's infidelity at the time of her pregnancy. The revelation of secondary loss is common in dysfunctional grieving. Resolution of grief encompasses not only accommodation to object loss, but also change in the pathological behaviors incorporated into the patient's self-image as a result of the loss (Lazare, 1979). The maladaptive operations employed by these patients to preserve self-image were discarded as the grief resolved. The focus of therapy included the loss of those behaviors as they were relinquished to prevent the patient from experiencing further anxiety and sense of loss (Zisook, 1987).(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Psychological↗
PubMed1986

Clinical measures to assess the practice and efficiency of breast self-examination.

If women examine their breasts thoroughly and regularly they may promptly recognize abnormal tissue changes. The level of skill and motivation required for effective breast self-examination (BSE), however, is very high. In a prospective study of 304 patients with newly diagnosed breast cancer, 165 (54%) claimed to practice BSE. On comparison with the remaining 139, the BSE practitioners reported their symptoms sooner than the nonpractitioners, and presented more often with clinically early tumors. There was, however, no difference in tumor size, and pathologic status of axillary nodes between the two groups. There were 60 patients who discovered the abnormalities during self-examination. On comparison with the remaining 244, significantly more BSE discoverers had shorter patient delay in presentation, but there was no significant difference in tumor size, clinical stage, and nodal status. It is concluded that these or similar clinical measures must be used in assessing the effectiveness of population-based BSE campaigns.

Age Factors↗
PubMed1986

Breast screening clinic versus health education session as outlets for education in breast self-examination.

A population based programme to educate women in breast self-examination (BSE) was organised as part of the UK Trial of Early Detection of Breast Cancer. Women who responded to an invitation to a meeting were educated in groups and were not routinely screened. Open access clinics offered x ray and clinical examination to all women in the study age group of 45 to 64. Women who presented for screening without prior BSE education were taught individually by clinic staff. Women taught by the two methods were surveyed by post and their BSE practice since education was compared. It was hypothesised that the women taught in clinics, who had been reassured of their breast normality, would practice BSE more regularly and correctly. Results did not confirm this hypothesis. Lower standards of practise and a higher level of anxiety at the time of survey were found in the group who presented at a free access clinic and had received individual teaching at the time of screening.

Breast↗
PubMed1984

Breast self-examination: clinical results from a population-based prospective study.

As part of the Department of Health's National Breast Screening Trial a seven year study is in progress in Huddersfield to assess the effect of an educational programme in Breast Self Examination (BSE) on the mortality due to breast cancer among women aged 45-64. The initial cohort of 22,484 women have completed 3 years in the study and show a higher than expected annual incidence rate of breast cancer. There is no significant difference in the incidence rates between those who attended meetings for BSE instruction and those who did not. Similarly there is no difference in stages of presentation of cancers between attenders and non-attenders at these meetings and also between cancers detected in the first, second and third years. Those who discovered abnormalities during self examination, however, presented with smaller lumps compared to other women. Assessment of prognostic factors do not at this time provide sufficient evidence to show that a community-base BSE campaign will result in a significant improvement in the stage of breast cancer presentation.

Breast Neoplasms↗
PubMed1984

The long-term effects of human sexuality training programs for public school teachers.

The current study evaluated long-term effects of a training model in human sexuality on public school teachers' knowledge and attitudes. The data indicated that, although significant changes were found from the pretest to posttest assessment of knowledge and attitudes on two standardized measures, attitudinal changes for teachers could not be maintained over time. In addition, knowledge decreased with most drastic changes occurring in the educator who, while trained, did not teach the material in a classroom setting. The results of this model staff development program suggest factors that may alter sex education training effects for professionals who work in public school settings.

Adult↗