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Biomedical subjects

M Armstrong

Publications and source records attributed to M Armstrong.

At least 19 recordsLinked to original sources
PubMed2006

Use of rapid diagnostic tests for diagnosis of malaria in the UK.

BACKGROUND: Malaria is currently diagnosed almost exclusively by microscopy in clinical laboratories. The introduction of rapid diagnostic tests (RDTs) may be useful in achieving rapid detection of malaria parasites, especially in situations where malaria is not often seen or where staff are inexperienced. AIM: To explore the use of RDT in UK laboratories. METHODS: The current use of RDTs was surveyed in UK laboratories subscribing to the United Kingdom National External Quality Assessment Scheme blood parasitology and haematology schemes. RESULTS: An overall survey response rate of 60.3% was seen. RDTs were found to be the preferred choice, either alone or in conjunction with microscopy in 31.2% of the samples examined during normal working hours and in 44.3% of the specimens examined on call. CONCLUSIONS: During on-call hours, the use of RDTs was observed to increase and RDTs changed the diagnosis in 12% of laboratories. No established protocol for RDT use was, however, observed in the UK. A protocol that needs to be validated in the laboratory setting is suggested.

After-Hours Care↗
PubMed2005

The mitochondrial genome of Xiphinema americanum sensu stricto (Nematoda: Enoplea): considerable economization in the length and structural features of encoded genes.

The complete sequence of the mitochondrial genome of the plant parasitic nematode Xiphinema americanum sensu stricto has been determined. At 12626bp it is the smallest metazoan mitochondrial genome reported to date. Genes are transcribed from both strands. Genes coding for 12 proteins, 2 rRNAs and 17 putative tRNAs (with the tRNA-C, I, N, S1, S2 missing) are predicted from the sequence. The arrangement of genes within the X. americanum mitochondrial genome is unique and includes gene overlaps. Comparisons with the mtDNA of other nematodes show that the small size of the X. americanum mtDNA is due to a combination of factors. The two mitochondrial rRNA genes are considerably smaller than those of other nematodes, with most of the protein encoding and tRNA genes also slightly smaller. In addition, five tRNAs genes are absent, lengthy noncoding regions are not present in the mtDNA, and several gene overlaps are present.

Animals↗
PubMed2005

Clinical features and diagnosis of 42 travellers with cutaneous leishmaniasis.

BACKGROUND: Leishmania species that occur within different geographical areas may cause different clinical manifestations, virulence and drug sensitivity. Patients/Methods. All patients with a clinical diagnosis of cutaneous leishmaniasis seen at the Hospital for Tropical Diseases from 1997 to 2000 were identified and clinical details recorded onto a database, with emphasis on clinical presentation, risk factors, travel history and laboratory diagnosis. RESULTS: Forty-two patients were identified, 23 of whom had travelled to New World and 19 to Old World countries. Clinical presentation typically consisted of a single nodule with ulceration. In 50% infection was caused by L. (Viannia) braziliensis. PCR was performed in specimens from 34 patients and species identification was possible in 32 cases (sensitivity 94%), the two PCR negative patients had amastigotes demonstrated by histology and culture. Patients were treated with established therapies. Seventy one percent were cured by treatment, 12% had a spontaneous cure, 7% were lost to follow-up and the remaining 10% required a second-line therapy. No relapses were reported during a mean follow-up period of 27 months. CONCLUSIONS: Our study highlights the need for comprehensive investigations and the advantages of PCR in the diagnosis of patients with suspected leishmaniasis in non-endemic regions of the world.

Adolescent↗
PubMed2005

External ocular infections due to methicillin-resistant Staphylococcus aureus (MRSA).

PURPOSE: To determine the prevalence and clinical characteristics of external ocular infections caused by methicillin-resistant Staphylococcus aureus (MRSA) in an ophthalmic hospital in the UK. METHODS: A retrospective analysis of the case notes of patients who had culture proven external ocular Staphylococcal infections during a 44-month period was undertaken. RESULTS: There were a total of 548 external eye infections caused by Staphylococcus aureus. Of these, 17 (3%) were MRSA positive. The most common presentation was conjunctivitis seen in six patients. All MRSA isolates were sensitive to chloramphenicol. Ofloxacin resistance was observed in all isolates from patients over the age of 50 years. All patients had an underlying history of either an ocular surface disease, malignancy, or a debilitating medical illness. CONCLUSIONS: MRSA is as yet an infrequent cause of external ocular infections. Patients typically have underlying ocular risk factors and/or are medically debilitated. Different strains infect young and old age groups with characteristic antimicrobial sensitivity. This study highlights the need for more work to establish the role of MRSA commensals and ocular infections.

Adolescent↗
PubMed2005

PAR-1 genotype influences platelet aggregation and procoagulant responses in patients with coronary artery disease prior to and during clopidogrel therapy.

Genetic variations of the protease-activated receptor-1 (PAR-1) have been associated with platelet receptor density and linked to thrombin receptor-activating peptide (TRAP)-induced phenotypes of platelet aggregation and P-selectin expression. We investigated whether the PAR-1 intervening sequence-14 A>T dimorphism influences platelet procoagulant activity. We also determined whether the P2Y12 antagonist clopidogrel could offset any observed functional polymorphism of the PAR-1 receptor by inhibiting P2Y12-mediated amplification of TRAP-induced responses. We studied 54 patients listed for elective percutaneous coronary intervention assessing TRAP-induced platelet aggregation and markers of procoagulant activity. Platelet responses were measured at baseline, 4 h post clopidogrel 300 mg, and 10 and 28 days following clopidogrel 75 mg daily. Each patient was genotyped for the PAR-1 intervening sequence-14 A/T dimorphism. Increased platelet aggregation and procoagulant responses were observed with PAR-1 A allele homozygotes. Clopidogrel significantly inhibited these platelet responses regardless of PAR-1 genotype, but did not offset the hyper-reactivity associated with the A/A homozygotes. We conclude that a common sequence variation within the PAR-1 gene influences TRAP-induced platelet procoagulant activity as well as aggregation. Higher platelet reactivity associated with PAR-1 IVSn-14 A allele homozygotes persists despite clopidogrel therapy. These individuals may be at higher risk of thromboembolic events and may require additional anti-platelet medication.

Alleles↗
PubMed2004

Falciparum malaria in malaria-naive travellers and African visitors.

BACKGROUND: Patients from malaria-endemic areas who present in non-endemic countries with Plasmodium falciparum malaria are often assumed to have some degree of immunity. If this were reliably true, it would simplify their management. AIM: To determine whether being born and resident in a malaria-endemic country is a predictor of clinical course in UK admissions for malaria. DESIGN: Prospective observational study. METHODS: We compared clinical and laboratory parameters between two groups of adult patients with acute P. falciparum malaria, admitted to the Hospital for Tropical Diseases in London: one born and resident in non-endemic countries (n=167); the other born and resident in malaria-endemic countries of Africa (n=93). Patients were excluded if they had taken prophylaxis or prior treatment. RESULTS: There were no differences between these two groups in terms of peak parasitaemia or time to parasite clearance. There was a significantly higher risk of malaria-naive patients having peak parasitaemia >5% (OR 4.5, 95%CI 1.5-13.2). Of those usually resident in Africa, 31% required parenteral treatment compared to 41% of the malaria-naive group. Of the visitors from Africa, 4.3% needed admission to the Intensive Therapy Unit (ITU), although there was a tendency for more malaria-naive patients to require ITU care (OR 2.69, 95%CI 0.9-8.1). DISCUSSION: While there are differences in presentation between those who are malaria-naive and those who live in malaria-endemic African countries, making assumptions about the immunity or clinical course of an individual patient with malaria presenting in the UK on the basis of presumed history of exposure is unwise.

Adolescent↗
PubMed2004

Self-harm in young people: a perspective for mental health nursing care.

AIMS: This paper addresses the assessment and management of self-harm in young people by a nurse consultant-led self-harm service in the UK. The purpose of the paper is to present some of the theoretical perspectives of the service and how these have influenced current practice with this group of young people. BACKGROUND: Self-harm in young people continues to be a serious concern for health services globally. Rates of self-harm in teenagers in the UK are among the highest in Europe. The current literature offers information on the nature of self-harm and some evidence of specific interventions mainly from a 'psychiatric perspective'. This paper examines the development of a locally based nurse-led self-harm team involved in the care of this group of young people. A sociological view of children and young people is applied in examining the way society construes self-harm and the formation of the behaviour as a deviant act. Self-harm is considered in the context of transition through adolescence and the growth of self-identity. CONCLUSION: The locally based child and adolescent mental health service has drawn together the evolving nurse consultant role, mental health nursing and medical sociology. This integration of people and theory will enhance the services understanding of self-harm in young people. At an international level, there is a need to consider the sociological dimensions of self-harm in young people as a way forward for mental health nurses who are involved in working with this group of people.

Adolescent↗
PubMed2004

Serological speciation of human schistosome infections by ELISA with a panel of three antigens.

AIMS: To find out whether serology can reliably speciate human schistosomiasis using a simple enzyme linked immunosorbent assay (ELISA) technique. METHODS: Stored sera from 66 patients with microscopically confirmed schistosomiasis were subjected to ELISA using a panel of three antigens, namely: unfractionated Schistosoma mansoni soluble egg antigen (SEA); CEF6, a cationic fraction of SEA; and crude S margrebowiei egg antigen, prepared from an animal schistosome closely related to S haematobium. RESULTS: The optical densities (ODs) obtained using CEF6 as antigen were significantly higher in sera from S mansoni infected patients than in sera from S haematobium infected patients (median OD, 0.810 v 0.595). Using S margrebowiei egg antigen, the optical densities were significantly higher in S haematobium sera than in S mansoni sera (median OD, 0.794 v 0.544). There was no significant difference in optical densities between S mansoni and S haematobium sera using SEA (median OD, 0.725 v 0.737). The ratio of ODs (CEF6 to S margrebowiei egg antigen) was calculated: a ratio of >1 indicated S mansoni infection (sensitivity, 88%) and a ratio of <1 indicated S haematobium infection (sensitivity, 84%). The odds ratio for S haematobium having an OD ratio of <1 was 36.8 (95% confidence interval, 7.0 to 194). CONCLUSIONS: The identity of the infecting species of schistosome can be determined using the panel of antigens described. SEA should be used to screen serum samples, and the CEF6 : S margrebowiei egg antigen ELISA optical density ratio can be used where serological speciation is required.

Animals↗
PubMed2003

Investigation of tropical eosinophilia; assessing a strategy based on geographical area.

OBJECTIVES: Patients with eosinophilia are an important clinical problem. This study aimed to assess the most efficient manner of investigating patients with peripheral eosinophilia (eosinophil count >0.5x10(9)ml(-1)) presenting from the tropics. METHODS: Patients attending the Hospital for Tropical Diseases, London, from October 1997 to March 2002 for investigation of eosinophilia were identified prospectively. Laboratory, clinical and demographic data were recorded from laboratory and clinical records. An investigation set was proposed prospectively and assessed for all geographical areas (stool microscopy, strongyloides culture and serology), all of Africa (additional schistosomal serology, terminal urine microscopy and filarial serology) and West Africa (additional day-bloods for microfilaria). RESULTS: Data was analysed for 261 patients. At least one helminthic cause for eosinophilia was found in 64% of patients (median eosinophilia 1.2x10(9)ml(-1)). Seventeen per cent of patients had more than one helminth species found. Median eosinophilia increased with number of diagnoses per patient. The proposed investigation sets were validated, with high yield for all proposed tests apart from filarial serology outside West Africa, and good sensitivity. CONCLUSIONS: Initial investigation of eosinophilia in patients presenting from the tropics may be guided by a simple investigation set depending on broad area of travel which has high sensitivity and yield. Patients frequently have more than one helminthic cause of eosinophilia.

Adolescent↗
PubMed2003

Phased upgrading for nitrogen removal--a low cost approach.

A phased approach has been adopted for upgrading the Luggage Point WWTP for nitrogen removal. Luggage Point WWTP (900,000 EP) is the largest plant operated by Brisbane Water. Management actions recommended by the South East Queensland Wastewater Management Strategy require the effluent total nitrogen levels to be reduced to less than 5 mg/L (50th percentile) by 2005. Luggage Point WWTP originally featured primary settling and a completely nitrifying activated sludge process. Effluent total nitrogen levels from the plant averaged 27 mg/L. Characteristics of the wastewater are highly variable, with primary settled wastewater having a COD/BOD5 ratio averaging 2.5, a TKN/COD ratio averaging 0.12 and effluent non-ammonia TKN averaging 1.8 mg/L (but up to 5 mg/L). The upgrade presented a substantial challenge, due to the limited available substrate for denitrification, a significant level of unbiodegradeable nitrogen and the low existing bioreactor HRT. The phased upgrading strategy was adopted to overcome these challenges most effectively and at low cost. The first stage of the upgrade included modifications to the existing plant infrastructure, without constructing new tankage. The existing bioreactors have been retrofitted using a five stage Bardenpho nutrient removal process, incorporating significant flexibility. The first phase upgrade has been commissioned and preliminary results indicate that the effluent total nitrogen has been reduced below the required first phase target of 8 mg/L. This represents a reduction of 3 tonnes of nitrogen per day entering Moreton Bay. The process is also operating with good stability and with excellent sludge settleability. The first phase of the upgrade will be completed for 25M AUS dollars, which represents a low cost of 28 dollars per equivalent person. Further upgrade works are likely to include separate treatment of the digested sludge dewatering centrate and advanced control of the biological process. The upgrade of Luggage Pt WWTP has shown that low effluent nitrogen can be achieved at low cost, through optimum utilisation of existing assets and a phased approach to modifications.

Bioreactors↗
PubMed2002

Caring for the chronically ill: a clinic for final-year medical students.

In 2000 the Diabetes Centre and the Medical Oncology Department of St Vincent's Hospital, Sydney established a joint clinic for the teaching of final-year medical students. The clinic was established amid concerns that hospitals are increasingly focused on acute care and have few resources available for teaching about chronic conditions. The clinic aimed to improve both patient care and learning opportunities by engaging students in useful activities with chronically ill patients. The students met with their patients regularly to monitor progress, adjust medication (under supervision) and arrange support services. The students and staff from both units met once a week in a coordination meeting where cases were reviewed and learning issues discussed. Students had informal interactions with medical and allied health staff at other times. Overall the clinic provided a rich learning environment for students with a focus on the development of the integrated skills required in the care of chronically ill people, rather than on the specific medical disciplines involved.

Adult↗
PubMed2001

Bacterial contamination of human organ-cultured corneas.

PURPOSE: The aim of this study was to detect and identify bacterial contaminants in human corneoscleral tissue after organ culture storage. METHODS: Seventy-two corneoscleral rims and corneal buttons trephined from organ cultured corneoscleral discs using aseptic technique and 45 organ-cultured donor corneoscleral rims postpenetrating keratoplasty) were subjected to a mechanical extraction technique using a Stomacher laboratory blender. As a control, 28 of the corneoscleral rims and buttons were halved; one half of each corneoscleral rim and button was decontaminated in formalin for 48 hours before thorough washing in balanced salt solution. Corneal specimens, culture medium, and transport (5% dextran) medium were cultured in brain-heart infusion broth at 37 degrees C for 5 days. Bacterial isolates were identified after culture of turbid enrichment broth. RESULTS: Bacterial contamination was demonstrated in 29% (21 of 72) of the corneoscleral rims and 15% (11 of 72) of the corneal buttons that were trephined aseptically from corneoscleral discs and in 29% (13 of 45) of postkeratoplasty corneoscleral rims. Bacterial contaminants were not isolated from controls. Isolated microorganisms included coagulase-negative Staphylococcus, Staphylococcus aureus, Streptococcus viridans, Pseudomonas sp, and Bacillus sp. A correlation was not demonstrated between contamination and cause of death, death to enucleation, death to culture time, or time in culture. Postkeratoplasty endophthalmitis was not evident in the patients who had received corneal buttons from those corneoscleral discs that had contaminated corneoscleral rims. CONCLUSIONS: Bacterial contamination exists in corneoscleral tissue after organ culture storage. The difference in distribution of bacteria and percentage of contamination between the peripheral and central corneas causes us to question the value of routine postpenetrating keratoplasty corneoscleral rim cultures.

Bacteria↗