Biomedical subjects

R Anderson

Publications and source records attributed to R Anderson.

At least 19 recordsLinked to original sources

PubMed2007

Clarithromycin alone and in combination with ceftriaxone inhibits the production of pneumolysin by both macrolide-susceptible and macrolide-resistant strains of Streptococcus pneumoniae.

OBJECTIVES: To investigate the effects of clarithromycin (0.01-0.5 mg/L) alone or in combination with ceftriaxone (0.1 and 0.25 mg/L) on pneumolysin production by both macrolide-susceptible and -resistant [2 erm(B) positive and 2 mef(A) positive] strains of Streptococcus pneumoniae. METHODS: The bacteria were cultured for 6 h at 37 degrees C/5% CO(2) in tryptone soy broth, washed, enumerated and resuspended to 0.5-3 x 10(8) cfu/mL in tissue culture medium, RPMI 1640. After 16 h of incubation at 37 degrees C / 5% CO(2), pneumolysin was assayed in the bacteria-free supernatants, as well as in lysates, using a functional assay based on the influx of calcium into human neutrophils. RESULTS: Exposure of not only macrolide-susceptible strains, but also the macrolide-resistant strains, of S. pneumoniae to sub-MICs of clarithromycin resulted in dose-related inhibition of the pneumolysin production, whereas production of the toxin was unaffected by ceftriaxone. CONCLUSIONS: These observations demonstrate that even in the setting of macrolide resistance the production of pneumolysin, a key virulence factor of the pneumococcus, is attenuated by exposure of this microbial pathogen to clarithromycin.

Anti-Bacterial Agents↗

PubMed2006

Hyaluronidase augments pneumolysin-mediated injury to human ciliated epithelium.

OBJECTIVES: The main objective of this study was to investigate the effects of pneumococcal hyaluronidase (0.1-10microg/ml), alone and in combination with pneumolysin (50 and 100ng/ml), on human ciliated epithelium. METHODS: Ciliary beat frequency (CBF) and structural integrity of human ciliated respiratory epithelium in vitro were studied using a phototransistor technique and a visual scoring index, respectively. RESULTS: Hyaluronidase per se did not affect either CBF or the structural integrity of the epithelium. However, preincubation of the epithelial strips with hyaluronidase (10microg/ml) for 30min at 37 degrees C significantly potentiated pneumolysin-mediated ciliary slowing and epithelial damage. Hyaluronan, a substrate of hyaluronidase, had no effects on the ciliated respiratory epithelium in concentrations up to 100microg/ml and did not antagonize the injurious effects of pneumolysin on the epithelium. However, preincubation of the epithelial strips with hyaluronan (100microg/ml) was associated with attenuation of the ciliary slowing and epithelial damage induced by incubation of the strips with hyaluronidase (10microg/ml) for 30min at 37 degrees C followed by addition of pneumolysin (50ng/ml). CONCLUSIONS: Although having no direct effects alone, hyaluronidase may contribute to pneumolysin-mediated damage and dysfunction to respiratory epithelium, thereby favoring colonization and subsequently extra-pulmonary dissemination of the pneumococcus.

Bacterial Proteins↗

PubMed2006

Immunogenicity and protective efficacy of a recombinant filamentous haemagglutinin from Bordetella pertussis.

Bordetella pertussis is the causative agent of whooping cough, a major childhood pathogen; acellular vaccines consisting of purified B. pertussis antigens such as filamentous haemagglutinin (FHA) are commonly used to prevent pertussis. Despite the importance of FHA in B. pertussis pathogenesis and its inclusion in most acellular vaccines, the functional importance of individual domains in the induction of protective immunity is largely unknown. In this study, we have purified a recombinant FHA protein from Escherichia coli consisting of a 42 kDa maltose binding domain of E. coli and the 43 kDa type I immunodominant domain of FHA. The fusion protein (Mal85) was purified from E. coli cell lysates via affinity chromatography with an amylose column. Mal85 was then delivered to BALB/c mice intranasally encapsulated in liposomes, formulated with Protollin(TM) or in conjunction with an immunostimulatory CpG oligonucleotide. Mice were also vaccinated intraperitoneally with alum-adsorbed Mal85. Sera from all treatment groups showed strong IgG responses to Mal85 and recognized native FHA. Specific salivary IgA was induced in mice vaccinated with Mal85 in liposomes, Protollin(TM) and delivered with CpG. Vaccination with Mal85 encapsulated in liposomes or formulated with Protollin(TM) provided protection against aerosol challenge with B. pertussis in BALB/c mice. These data indicate that the type I domain of FHA is a protective antigen in mice and may serve as a candidate for inclusion in new acellular pertussis vaccines.

Adhesins, Bacterial↗

PubMed2006

Effects of alveolar macrophage depletion on liposomal vaccine protection against respiratory syncytial virus (RSV).

Little is known about the identities and roles of antigen-presenting cells upon exposure to antigens of respiratory syncytial virus (RSV). Here, we focused on elucidating the importance of alveolar macrophages in conferring protective immunity in mice administered a liposome-encapsulated recombinant fragment of the RSV G protein. Mice were depleted of alveolar macrophages by intranasal inoculation of liposome-encapsulated dichloromethylenediphosphonic acid (DMDP). Mice depleted of alveolar macrophages prior to immunization developed reduced levels of serum RSV-neutralizing antibody and showed dramatically impaired protection against RSV challenge. The severity of interstitial inflammation was also markedly reduced in macrophage-depleted mice. In conclusion, this study demonstrates a pivotal role for alveolar macrophages during exposure to liposome-encapsulated RSV antigen in initiating both protective and histopathological responses against RSV.

Animals↗

PubMed2006

Determination of the prevalence of drug misuse by meconium analysis.

In a pilot study to determine the local prevalence of maternal drug misuse, meconium from 400 infants was analysed for metabolites of eight controlled drugs. Cannabinoids were found in 13.25%, cocaine in 2.75%, and amphetamine in 1.75%. The prevalence of opiate and benzodiazepine misuse was masked by the presence of prescribed drugs so was undeterminable.

Cannabinoids↗

PubMed2005

Effects of clofazimine on potassium uptake by a Trk-deletion mutant of Mycobacterium tuberculosis.

OBJECTIVES: This study was designed to investigate the effects of the membrane-active, anti-mycobacterial agent, clofazimine, on potassium (K+)-uptake by a mutant of Mycobacterium tuberculosis (MTB), in which the Trk system, the major K+ transporter of this microbial pathogen, had been selectively inactivated. METHODS: The ceoB and ceoC genes of MTB, which encode the TrkA proteins, CeoB and CeoC, were deleted by homologous recombination, and the double-knockout mutant and wild-type strains compared with respect to K+ uptake and growth in the presence and absence of clofazimine (0.015-2.5 mg/L) using radioassay procedures. RESULTS: Surprisingly, the magnitudes of K+ uptake and rate of growth of the ceoBC-knockout mutant were significantly (P < 0.05) greater than those of the wild-type strain, due, presumably, to induction of a back-up transporter. Exposure of both the wild-type strain and ceoBC-knockout mutant of MTB to clofazimine was accompanied by dose-related decreases in K+ uptake, as well as growth, which were of comparable magnitude for both strains. CONCLUSIONS: These observations demonstrate that the major K+ transporter of MTB, Trk, as well as an uncharacterized inducible back-up system, is equally sensitive to the inhibitory actions of clofazimine.

Anti-Bacterial Agents↗

PubMed2005

Sonic hedgehog is required for cardiac outflow tract and neural crest cell development.

The Hedgehog signaling pathway is critical for a significant number of developmental patterning events. In this study, we focus on the defects in pharyngeal arch and cardiovascular patterning present in Sonic hedgehog (Shh) null mouse embryos. Our data indicate that, in the absence of Shh, there is general failure of the pharyngeal arch development leading to cardiac and craniofacial defects. The cardiac phenotype results from arch artery and outflow tract patterning defects, as well as abnormal development of migratory neural crest cells (NCCs). The constellation of cardiovascular defects resembles a severe form of the human birth defect syndrome tetralogy of Fallot with complete pulmonary artery atresia. Previous studies have demonstrated a role for Shh in NCC survival and proliferation at later stages of development. Our data suggest that SHH signaling does not act directly on NCCs as a survival factor, but rather acts to restrict the domains that NCCs can populate during early stages (e8.5-10.5) of cardiovascular and craniofacial development.

Animals↗

PubMed2005

The effectiveness of out-of-hours dental services: II. patient satisfaction.

OBJECTIVE: To compare patients' satisfaction with four types of out-of-hours emergency dental service, including both 'walk-in' and telephone-access services. BASIC DESIGN: Postal questionnaire survey of patients who had attended weekend emergency dental services. Patient satisfaction measured using an adapted version of a questionnaire developed for assessing out-of-hours medical services. SETTING: Two health authorities in South Wales, UK. SUBJECTS: The 411 patients who saw a dentist and completed the patient satisfaction questionnaire. RESULTS: The quality of the dentist-patient encounter was similar across services, with most patients being satisfied with the dentist's attitude and manner, the explanations and advice given, and having to see an unfamiliar dentist. Satisfaction was lower, and differed more across services in relation to service accessibility and delays in getting to see a dentist out-of-hours. The walk-in services were perceived as the least accessible: around 40% said they had problems contacting a dentist when the surgery was closed (compared with 16% and 29% in the other two, telephone-access services). Only 12-14% of telephone-access patients said they would be 'happy with advice plus a reliable appointment when surgeries re-opened', whereas almost half of walk-in patients thought this. CONCLUSIONS: Despite overall satisfaction with the dentist-patient encounter, there was relative dissatisfaction with the accessibility of all services, especially the walk-in services. Out-of-hours dental services should be better designed to reflect patients' needs: the need for telephone advice as well as face-to-face consultations, and greater awareness that theoretically available services may be difficult to access unless public expectations and awareness are raised.

After-Hours Care↗

PubMed2005

The effectiveness of out-of-hours dental services: I. Pain relief and oral health outcome.

OBJECTIVE: To compare the effectiveness of four types of out-of-hours emergency dental service, including both 'walk-in' and telephone-access services. BASIC DESIGN: Questionnaire survey of patients attending weekend emergency dental services, with measurement of self-reported oral health status and dental pain (at attendance and follow-up) and retrospective judgements of change in oral health status. SETTING: Two health authorities in South Wales, UK. SUBJECTS: A total of 783 patients who completed questionnaires at attendance, and 423 who completed follow-up questionnaires. RESULTS: For patients who saw a dentist there were no consistent differences in the effectiveness of the four services, whether measured as pain relief, oral health gain or using patients' retrospective transition judgements about feeling better after their episode of emergency dental care. The proportion of patients reporting no improvement (transition judgements), either an hour after or the day after seeing the dentist, was surprisingly high (30-40% and 23-38% respectively). Although the 'rotas for all' - a telephone-access GDP-provided service for both registered and unregistered patients - achieved both the highest reductions in pain scores and the greatest improvements in dental health status between attendance and follow-up, this effect may reflect health gains due to care received after the episode of emergency dental care. CONCLUSIONS: Neither the setting where emergency dental patients are seen, nor the type of dentist who sees them, appear to have any significant effect on patient-reported health outcomes. Although further exploration of the factors that predict poor pain relief or low oral health gain is required, future research on these services should focus on the process of care and accessibility.

Adolescent↗

PubMed2005

Evaluation of Salmonella enteritidis in molting hens after administration of an experimental chlorate product (for nine days) in the drinking water and feeding an alfalfa molt diet.

The method most commonly used to induce molting and stimulate multiple egg-laying cycles in laying hens for commercial egg production is to fast the hens. Unfortunately, increased risk of Salmonella enteritidis (SE) infection may result from the use of this method. Methods to stimulate multiple egg-laying cycles without increasing the risk of SE infection are needed. Hens over 50 wk of age were divided into 12 groups of 11 hens each and placed in individual laying cages. One week prior to dietary changes, hens were placed on an 8-h light and 16-h dark photoperiod that continued for the 9-d molt. All hens were challenged orally with 10(6) cfu of SE on the fourth day of the molt. Treatments were nonfed hens with distilled water (NFD), nonfed hens with the experimental chlorate product (ECP, which provided 15 mM chlorate ion) water (NFECP), alfalfa diets with distilled water (ALD), and alfalfa diets with ECP water (ALECP). In the NFD hens, 67% (log10 2.74) of the crops and 94% (log10 5.62) of the ceca were colonized, whereas for the NFECP hens significant reductions to 22% (log10 1.05) of the crops and 61% (log10 2.44) of the ceca were observed. In the ALD hens, 61% (log10 2.52) of the crops and 94% (log10 4.06) of the ceca were colonized. In the ALECP hens, highly significant reductions to 11% (log10 1.26) of the crops and 39% (log10 1.12) of the ceca were observed. When compared with the NFD hens, significant reductions in SE invasion of the ovary, liver, and spleen occurred in all other treatments, except the ovary in the ALD hens. The low alfalfa intake is probably a factor in our lowered protection against SE when compared with previous results. For several parameters, these results suggest that ECP or the combination of ECP and alfalfa may be a useful tool to reduce the risk of SE during an induced molt.

Animal Feed↗

PubMed2005

Pneumolysin-mediated activation of NFkappaB in human neutrophils is antagonized by docosahexaenoic acid.

This study was designed to investigate the relationship between influx of extracellular Ca(2+), activation of NFkappaB and synthesis of interleukin-8 (IL-8) following exposure of human neutrophils to subcytolytic concentrations (8.37 and 41.75 ng/ml) of the pneumococcal toxin, pneumolysin, as well as the potential of the omega-3 polyunsaturated fatty acid, docosahexaenoic acid, to antagonize these events. Activation and translocation of NFkappaB were measured using a radiometric electrophoretic mobility shift assay, while influx of extracellular Ca(2+) and synthesis of IL-8 were determined using a radioassay and an ELISA procedure, respectively. Exposure of neutrophils to pneumolysin was accompanied by influx of Ca(2+), activation of NFkappaB, and synthesis of IL-8, all of which were eliminated by inclusion of the Ca(2+)-chelating agent, EGTA (10 m m), in the cell-suspending medium, as well as by pretreatment of the cells with docosahexaenoic acid (5 and 10 microg/ml). The antagonistic effects of docosahexaenoic acid on these pro-inflammatory interactions of pneumolysin with neutrophils were not attributable to inactivation of the toxin, and required the continuous presence of the fatty acid. These observations demonstrate that activation of NFkappaB and synthesis of IL-8, following exposure of neutrophils to pneumolysin are dependent on toxin-mediated influx of Ca(2+) and that these potentially harmful activities of the toxin are antagonized by docosahexaenoic acid.

Adult↗

PubMed2005

Taming the neutrophil: calcium clearance and influx mechanisms as novel targets for pharmacological control.

Neutrophils are relatively insensitive to the anti-inflammatory actions of conventional chemotherapeutic agents, including corticosteroids, emphasizing the requirement for novel pharmacological strategies to control the potentially harmful proinflammatory activities of these cells. In the case of commonly-occurring inflammatory diseases of the airways, the neutrophil is the primary mediator of inflammation in conditions such as chronic obstructive pulmonary disease, cystic fibrosis, acute respiratory distress syndrome, bronchiectasis and non-eosinophilic bronchial asthma. Recent insights into the mechanisms utilized by neutrophils to restore Ca(2+) homeostasis following activation with Ca(2+)-mobilizing, proinflammatory stimuli have facilitated the identification of novel targets for anti-inflammatory chemotherapy in these cells. The most amenable of these from a chemotherapeutic perspective, is the cyclic AMP-dependent protein kinase-modulated endomembrane Ca(2+)-ATPase which promotes clearance of the cation from the cytosol of activated neutrophils. Second generation type 4 phosphodiesterase inhibitors and adenosine receptor agonists operative at the level of subtype A2A adenosine receptors, which are currently undergoing clinical and preclinical assessment respectively, hold promise as pharmacologic modulators during the restoration of Ca(2+) homeostasis. If this promise is realized, it may result in novel chemotherapeutic strategies for the control of hyperacute and chronic inflammatory conditions in which neutrophils are primary offenders. Alternative, potential future targets include the Na(+), Ca(2+)-exchanger and store-operated Ca(2+) channels, which cooperate in the refilling of intracellular Ca(2+) stores.

Anti-Inflammatory Agents↗

PubMed2004

Patient expectations of emergency dental services: a qualitative interview study.

OBJECTIVE: To describe the expectations of walk-in patients seeking emergency dental care out-of-hours. BASIC DESIGN: Consecutive patients attending two emergency dental clinics at weekends were interviewed prior to seeing the dentist. The audio-recorded interview transcripts were analysed using the "framework" method of applied qualitative data analysis. SUBJECTS AND SETTING: Forty-four walk-in emergency dental patients at a community-based dental clinic and a dental hospital emergency clinic at the weekend. RESULTS: In addition to symptom relief, the main desired outcome for emergency dental patients may be informational and psychological--especially reassurance that the problem is not serious, and reduced uncertainty about the cause of the pain. In general, patients' stated expectations for specific treatments (such as antibiotics, or tooth extraction) were not absolute: rather, they implied these expectations were conditional upon the dentist deciding they were necessary. CONCLUSIONS: Emergency dental services, some of which are still dominantly treatment-focused, should reflect that many emergency dental attenders want advice and reassurance as much as relief from symptoms. This reinforces the importance of effective and sympathetic dentist-patient communication within emergency or out-of-hours consultations. It also implies that dentists' skills in listening, explaining and reassuring should be captured in any patient satisfaction or outcome measure designed for this patient group.

Adolescent↗

PubMed2004

Antimicrobial activity of clofazimine is not dependent on mycobacterial C-type phospholipases.

We have used a phospholipase C (PLC)-deletion mutant (plcABC) of the H37Rv strain of Mycobacterium tuberculosis (MTB), as well as a plcA-insertion mutant of Mycobacterium smegmatis, to investigate the possible involvement of PLCs in clofazimine-mediated inhibition of mycobacterial K(+) transport and growth. Inactivation of the PLCs of MTB and insertion of the plcA gene into M. smegmatis resulted in a substantial reduction and increase in hydrolysis of phosphatidylcholine (PC), respectively. However, both the mutant and wild-type strains of MTB and M. smegmatis were equally sensitive to the inhibitory effects of clofazimine on K(+) uptake and growth. These observations demonstrate that the PLCs of MTB are not involved in the antimicrobial activity of clofazimine.

Anti-Infective Agents↗

PubMed2004

Itraconazole antagonizes store-operated influx of calcium into chemoattractant-activated human neutrophils.

We have investigated the effects of itraconazole (0.1-10 micro m), an antimycotic which is often used prophylactically in primary and secondary immunodeficiency disorders, including chronic granulomatous disease, on mobilization of Ca(2+) and restoration of Ca(2+) homeostasis following activation of neutrophils with FMLP or PAF. Transmembrane fluxes of Ca(2+), as well as cytosolic concentrations of the cation were measured using a combination of spectrofluorimetric and radiometric procedures. The abruptly occurring increases in cytosolic Ca(2+) following activation of the cells with either FMLP (1 micro m) or PAF (200 nm) were unaffected by itraconazole. However, the subsequent store-operated influx of the cation was attenuated by itraconazole at concentrations of 0.25 micro m and higher. The itraconazole-mediated inhibition of uptake of Ca(2+) was not associated with detectable alterations in the intracellular concentrations of cyclic AMP, ATP or inositol triphosphate, and appeared to be compatible with antagonism of store-operated Ca(2+) channels. Although a secondary property, this anti-inflammatory activity of itraconazole, if operative in vivo, may be beneficial in conditions associated with dysregulation of neutrophil Ca(2+) handling such as CGD.

Antifungal Agents↗

PubMed2004

IgA antibodies of coeliac disease patients recognise a dominant T cell epitope of A-gliadin.

BACKGROUND: In coeliac disease (CD) patients, the dominant DQ2-Alpha-I-gliadin peptide recognised by CD4 T cells is contained within peptide sequence 57-73 (p57-73) of Alpha-gliadin. This peptide sequence is also located within a 33-mer protease resistant gliadin fragment and therefore is likely to play an important role in the pathogenesis of CD. AIMS: Our aim was to determine whether a B cell epitope was present within the immunodominant T cell epitope of Alpha-gliadin and, if so, to elucidate its sequence and determine the importance of deamidation and/or modification of the amino acid at position 65 for IgA binding. PATIENTS AND METHODS: A cohort of CD patients, disease controls, and healthy individuals were examined. Serum IgA antibodies to the native and modified p57-73 fragment of Alpha-gliadin were analysed using enzyme linked immunosorbent assays. Peptide scanning experiments were further used to elucidate the B cell epitope. RESULTS AND CONCLUSION: IgA antibodies to p57-73 were found in 29/72 (40.2%) endomysial antibody positive patients, all of whom had CD. The peptide antibody appeared to be present when patients were on a diet containing gluten and declined on a gluten free diet. The p57-73 antibody was very specific for CD (98%) and had a sensitivity of 56%. The amino acid at position 65 was not important for IgA binding but was crucial for T cell recognition of p57-73. Pentapeptide PXPQP emerges as a potentially strong candidate for the IgA binding motif in this region of Alpha-gliadin. This study shows that a significant proportion of newly diagnosed CD patients have an antibody response to the immunodominant T cell epitope.

Amino Acid Sequence↗

PubMed2004

Screening for syphilis among men who have sex with men in various clinical settings.

OBJECTIVES: To assess the prevalence of syphilis infections among men who have sex with men (MSM) accessing the Brisbane Sexual Health Clinic during the period 1997 up to May 2003, data were collated through three clinical programmes conducted by the service-a large inner city mainstream sexual health clinic and two small outreach sessional clinics conducted on the site of male sex on premises venues (SOPV). Data analysis also provided the opportunity to evaluate the effectiveness of the smaller outreach clinics to access populations of MSM less likely to attend or identify at the larger mainstream clinic, and therefore enhance the detection of previously undiagnosed sexually transmissible infections. METHODS: Computerised records from 1997-2003 were collated for a statistical analysis of syphilis and other STI pathology results for all MSM accessing the mainstream clinic, and two outreach clinics. RESULTS: A review of client charts showed that 16 new syphilis diagnoses were made over the previous 5 years, but only two of these infections (both through the mainstream clinic) were early syphilis and therefore transmissible. All other cases were latent infections. A higher proportion of bisexual men was identified with positive syphilis serology but this was just below significance (p=0.06). Significantly, almost a third of syphilis diagnoses (all latent) were made at SOPV outreach clinics, despite the much lower proportion of clients seen overall through the SOPV clinics. For other sexually transmissible infections, the mainstream clinic demonstrated greater efficiency at case detection. CONCLUSION: Outreach clinics located in male saunas may serve an effective function in syphilis screening by facilitating access for a particular subpopulation of MSM (bisexual, married men). These outreach clinics may provide important outlets for education and opportunistic screening of asymptomatic MSM and foster a greater willingness for men to honestly self identify. However, larger, mainstream clinics serve a more anonymous venue for the testing of symptomatic men.

Adolescent↗

PubMed2004

The attribute rating test for sensory analysis.

This new sensory method evaluates the intensity of an odorant by using a modified "paired-comparison" format. It can be applied to any situation for which the odor-causing agent is known and a purified standard is available. The attribute rating test requires that a standard solution of the odorant be prepared at a concentration that is both readily recognized by most individuals and likely to evoke customer complaints. Within an hour individuals can be trained to compare the odor type and intensity of the standard to water samples, then rate the odor in the sample as "not detected," "less than the standard," "equal to standard," or "greater than the standard." The attribute rating test was successfully used by a full-scale water treatment facility to monitor the intensity of geosmin in the source water and to determine the effectiveness of powdered activated carbon for controlling its earthy-odor in treated water.

Carbon↗