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Biomedical subjects

M Giles

Publications and source records attributed to M Giles.

At least 19 recordsLinked to original sources
PubMed2005

What is the best screening method to detect Serratia marcescens colonization during an outbreak in a neonatal intensive care nursery?

Serratia marcescens can cause outbreaks in neonatal intensive care units (NICUs), but the optimum method of screening for carriage has not been determined in this group of patients. During an outbreak of S. marcescens infections across two geographically distinct NICUs, babies were screened for both respiratory and gastrointestinal carriage. A total of 58 babies were colonized (N = 47) or infected (N = 11) with S. marcescens over a nine-month period. Forty-four colonized babies had paired respiratory and gastrointestinal tract specimens collected. Of these, 39% were positive from the gastrointestinal tract and 22% from respiratory tract specimens alone, and 39% had growth from both sites. Enrichment prior to inoculation on to solid media increased the detection of respiratory tract carriers. During an outbreak of S. marcescens, both respiratory and gastrointestinal samples should be collected in order to maximize the identification of colonized infants. Broth enrichment adds an additional day to obtaining results but increases the yield of positive results from respiratory specimens.

Australia↗
PubMed2005

Bidirectional cross talk between ERalpha and EGFR signalling pathways regulates tamoxifen-resistant growth.

We have previously demonstrated that oestrogen receptor alpha (ERalpha) modulates epidermal growth factor receptor (EGFR)/mitogen-activated protein kinase (MAPK) signalling efficiency in a tamoxifen-resistant MCF-7 breast cancer cell line (Tam-R). In the present study we have investigated whether this cross-talk between EGFR/MAPK and ERalpha signalling pathways is bidirectional by examining the effects of EGFR/MAPK activity on ER functionality in the same cell line. Elevated expression levels of phosphorylated serine 118 (S118) ERalpha were observed in the Tam-R compared to the parental wild type MCF-7 cell line (WT-MCF-7) under basal growth conditions. Phosphorylation of ERalpha at S118 was regulated by the EGFR/MAPK pathway in Tam-R cells being increased in response to amphiregulin (AR) and inhibited by the selective EGFR tyrosine kinase inhibitor, gefitinib and the MEK1/2 inhibitor, PD184352. Recruitment of the co-activators p68 RNA helicase and SRC1 to ERalpha, oestrogen response element (ERE) activity and Tam-R cell growth were similarly EGFR/MAPK-regulated. Chromatin immunoprecipitation (ChIP) studies revealed that in Tam-R cells the ERalpha assembled on the AR gene promoter and this was associated with elevated basal expression of AR mRNA. Furthermore, AR mRNA expression was under the regulation of the EGFR/MAPK and ERalpha signalling pathways. Neutralising antibodies to AR inhibited EGFR/ERK1/2 activity, reduced S118 ERalpha phosphorylation and reduced AR mRNA expression in TAM-R cells. These findings suggest that ERalpha function in Tam-R cells is maintained as a consequence of EGFR/MAPK-mediated phosphorylation at serine residue 118 resulting in the generation of a self-propogating autocrine growth-regulatory loop through the ERalpha-mediated production of AR.

Antineoplastic Agents, Hormonal↗
PubMed2005

Ion cyclotron production by a four-wave interaction with a helicon pump.

Ion cyclotron waves at approximately 0.7 the ion gyrofrequency have been observed experimentally in the large volume helicon reactor WOMBAT. These waves are highly localized along the axis of the device where a 8 cm diameter, 2 m long. Ar II plasma column is produced. Spectral measurements reveal a four-wave interaction where energy is down-converted to the ion cyclotron mode from the helicon pump. The experimental results are explained in terms of a filamentation type instability.

Journal Article↗
PubMed2005

Condom use in African adolescents: the role of individual and group factors.

This study set out to assess the ability of the Theory of Planned Behaviour (TPB) to predict and explain condom use in a traditional African context and in particular to assess the relative contributions of individual and normative constructs. A questionnaire survey was administered to 152 young adults (48% male, 52% female) at two points in time. Key constructs contained within the TPB were measured at Time 1. A short follow-up set of items was administered one week later at Time 2, thereby allowing for the measurement of actual behaviour. The results not only provide strong support for the predictive power of the TPB, since 67% of the variance in intention was explained, but also highlight the extent to which sexual behaviour in a rural location is governed by family/social influences. Subjective norm not only proved to be one of the most significant elements of the TPB model, together with self-efficacy (neither attitude nor perceived control were significantly involved), but 'my family' emerged as the most significant other. As such, the findings offer empirical evidence to support interventions that penetrate community networks.

Adolescent↗
PubMed2005

Breast milk pasteurisation in developed countries to reduce HIV transmission. Do the benefits outweigh the risks?

BACKGROUND: Transmission of HIV through breastfeeding is well documented. The World Health Organisation advise HIV-infected women in developed countries to use alternatives to breastfeeding together with highly active antiretroviral therapy and optimal management of delivery to prevent transmission of HIV to their infant. CASE REPORT: We present the case of an HIV-infected woman electing to exclusively breastfeed for six months and applying milk pasteurisation techniques without transmission to her infant. Two paired samples of her breast milk were tested for HIV RNA prior to and after pasteurisation. The first pair of specimens reported no change in HIV RNA copy number, the second pair of specimens reported an increase in copy number. DISCUSSION: This technique, the evidence for HIV inactivation and the effects pasteurisation has on nutritional and immunological components of breast milk are discussed. CONCLUSION: In conclusion, we believe there is currently insufficient data to recommend this technique either as a safe alternative to formula feeding in resource-rich countries or as a method for providing intact immunological components of breast milk to the infant.

Acquired Immunodeficiency Syndrome↗
PubMed2005

Growth factor signalling and resistance to selective oestrogen receptor modulators and pure anti-oestrogens: the use of anti-growth factor therapies to treat or delay endocrine resistance in breast cancer.

De novo insensitivity and acquired resistance to the selective oestrogen receptor modulator tamoxifen and the pure anti-oestrogen fulvestrant (faslodex) severely limit their effectiveness in breast cancer patients. This is a major clinical problem, since each year upward of 1 million women are dispensed anti-oestrogenic drugs. In order to investigate the phenomenon of anti-oestrogen resistance and to rapidly screen drugs that target the resistance mechanism(s), we have previously established several in vitro breast cancer models that have acquired resistance to anti-hormones. Such cells commonly develop an ability to proliferate after approximately 3 months of exposure to 4-hydroxytamoxifen or fulvestrant, despite an initial endocrine-responsive (i.e. growth-suppressive) phase. The current paper explores the role that growth factor signalling plays in the transition of oestrogen receptor-positive endocrine-responsive breast cancer cells to anti-oestrogen resistance or insensitivity and how we might, in the future, most effectively use anti-growth factor therapies to treat or delay endocrine-resistant states.

Breast Neoplasms↗
PubMed2004

An application of the Theory of Planned Behaviour to blood donation: the importance of self-efficacy.

Given that self-efficacy has emerged as a key construct in health psychology, this study set out to explore its utility in the context of blood donation as defined within the Theory of Planned Behaviour (TPB). An Ajzen and Fishbein-type questionnaire was administered to 100 undergraduate students at the University of Ulster, Coleraine. A hierarchical multiple regression analysis provided strong support for the role of self-efficacy as a major determinant of intention. It not only helped to explain some 73% of the variance, but also made a greater contribution to the prediction of intention than the other main independent variables of the model-past behaviour and self-identity. Demonstrating the utility of self-efficacy in the context of blood donor behaviour not only has several important practical implications, but serves to further highlight its importance within the TPB.

Adult↗
PubMed2004

Echocardiography and the general physician.

Doctors from many medical specialties request echocardiography as part of their assessment of patients with a wide range of pathology. Recent advances in the technology and techniques of echocardiography are discussed. The role of echocardiography in acute medicine is reviewed and its place in general medicine is also discussed.

Autoimmune Diseases↗
PubMed2000

Cerebellopontine angle lymphoma presenting as chronic mastoiditis.

Middle-ear tumours are not uncommonly mistaken for mastoiditis on presentation. We report a case of cerebellopontine angle non-Hodgkin's B-cell lymphoma originally presenting as a middle-ear inflammatory process. In mastoiditis not resolving with conventional treatment it is important to look for an underlying cause.

Aged↗
PubMed1999

Vascular surgical society of great britain and ireland: contribution of malnutrition to postoperative morbidity in vascular surgical patients

BACKGROUND: In an elderly population of surgical patients, poor mobility, poor diet and chronic disease contribute to a significant risk of malnutrition. Malnutrition is associated with muscle weakness, fatigue, poor wound healing and immunological dysfunction. The aim of the study was to establish the prevalence of malnutrition in vascular surgical patients and to compare postoperative infection rates in well nourished and malnourished patients. METHODS: A nutritional assessment was performed on 71 patients (49 men; median age 65 (range 26-85) years) attending preassessment for vascular surgical procedures. Nutritional status was measured using validated indicators of malnutrition: estimated weight changes over 3 months; body mass index; mid-arm muscle circumference (MAMC) calculated using triceps skin fold thickness (TSF) and mid-arm circumference (MAC) (MAMC = MAC - (3.14 x TSF)); and serum albumin concentration. Fifty-nine patients were followed after vascular surgery. The incidence of postoperative infections was related to preoperative nutritional status. RESULTS: Nineteen patients (27 per cent) had normal values for all nutritional indicators examined. The remaining 52 patients (73 per cent) had one (37), two (12), three (two) or four (one) nutritional indicators within the range for malnutrition. Among the 59 patients who underwent surgery there were five chest infections, seven wound infections, one urinary tract infection and one infected central line in 13 patients following six femorodistal bypasses, four abdominal aortic aneurysm repairs and three miscellaneous arterial procedures. The incidence of septic complications was zero in 14 patients with normal nutritional indicators and 41 per cent (13 of 32) in patients with indicators of malnutrition (P < 0.05, Fisher's exact test). CONCLUSION: Malnutrition is prevalent among vascular patients and may contribute to postoperative morbidity. Malnourished patients should be identified and referred to the dietician at the earliest opportunity to minimize the morbid effects of undernutrition.

Journal Article↗
PubMed1999

Chronic central infusion of growth hormone secretagogues: effects on fos expression and peptide gene expression in the rat arcuate nucleus.

Growth hormone (GH) secretagogues induce GH release, in part, by direct actions upon anterior pituitary somatotropes and, in part, by actions upon the neuroendocrine circuitry that regulates GH secretion. In particular, acute systemic administration of GH secretagogues results in increased neuronal activity and Fos protein expression in the arcuate nucleus of the hypothalamus. Prolonged administration of GH secretagogues has been reported to have long-lasting effects upon GH release, promoting increased pulsatile secretion. Here, we investigated how chronic central infusion of GH secretagogues affects the response of arcuate nucleus neurons to acute systemic administration of GH secretagogues. In male rats, after central infusion of GH secretagogues for 5 days, there was no sustained expression of Fos in the arcuate nucleus, no significant induction of Fos expression in response to acute GH secretagogue challenge, and a greatly attenuated secretion of GH in response to acute GH secretagogue challenge, all reflecting loss of funtional responsiveness to GH secretagogues. In situ hybridisation revealed that, in the arcuate nucleus of GH secretagogue-infused rats, mRNA levels for GH-releasing hormone, neuropeptide Y and somatostatin were not different than in saline-infused animals. However, somatostatin mRNA levels in the periventricular nuclei of GH secretagogue-infused rats were significantly higher than those of saline-infused rats, indicating that this nucleus may play an important role in mediating the effects of chronic GH secretagogue administration.

Animals↗
PubMed1999

Reduction of left ventricular mass index with blood pressure reduction in chronic renal failure.

AIM: We have reported previously in a study of 85 non-diabetic patients with chronic renal failure (CRF) that 24-h ambulatory blood pressure (ABP) recording and echocardiography are required for accurate diagnosis of inadequate blood pressure (BP) control and early left ventricular hypertrophy (LVH). In this study we found that the only independent determinants of left ventricular (LV) mass were hypertension, male sex, body mass index (BMI) and anemia. Little is known about the progression of LVH in patients as they progress from moderate to end-stage renal failure. PATIENTS AND METHODS: We undertook a follow-up observational study in a cohort of 65 (26 male, 12 black Afro-Caribbean and 7 Asian) of those patients originally investigated. Patients who had reached end-stage renal failure (ESRF) were not studied. RESULTS: A statistically significant correlation was found between change in left ventricular mass index (LVMI) and change in mean ABP parameters (r = 0.27 (p<0.03) for 24-h systolic, r = 0.21 (p<0.05) for 24-h diastolic, r = 0.29 (p<0.02) for mean arterial pressure (MAP), r = 0.24 (p<0.05) for daytime systolic, r = 0.30 (p<0.02) for nocturnal systolic and r = 0.26 (p<0.05) for nocturnal diastolic BP). Hemoglobin concentration and BMI changed little between the two studies and no other statistically significant correlations were found in respect of any other parameters studied, which has allowed us to isolate the effect of one determinant - adequacy of BP control-upon LVH. CONCLUSION: In patients with moderate chronic renal impairment, reduction in BP is associated with reduction of LVMI over time. Among the antihypertensive agents ACE inhibitors appeared to have the greatest ability to reduce LV mass in the subjects with LVH at baseline. Larger interventional studies are needed to determine whether ACE inhibitors are superior to other anti-hypertensive agents in LVH regression in chronic renal failure patients.

Adult↗
PubMed1998

Mapping attractor fields in face space: the atypicality bias in face recognition.

A familiar face can be recognized across many changes in the stimulus input. In this research, the many-to-one mapping of face stimuli to a single face memory is referred to as a face memory's 'attractor field'. According to the attractor field approach, a face memory will be activated by any stimuli falling within the boundaries of its attractor field. It was predicted that by virtue of its location in a multi-dimensional face space, the attractor field of an atypical face will be larger than the attractor field of a typical face. To test this prediction, subjects make likeness judgments to morphed faces that contained a 50/50 contribution from an atypical and a typical parent face. The main result of four experiments was that the morph face was judged to bear a stronger resemblance to the atypical face parent than the typical face parent. The computational basis of the atypicality bias was demonstrated in a neural network simulation where morph inputs of atypical and typical representations elicited stronger activation of atypical output units than of typical output units. Together, the behavioral and simulation evidence supports the view that the attractor fields of atypical faces span over a broader region of face space that the attractor fields of typical faces.

Face↗
PubMed1998

Prevalence of HIV, syphilis and genital chlamydial infection among women in north-west Ethiopia.

The prevalence of sexually transmitted diseases (STD) among women visiting antenatal (ANC) and gynaecological clinics in Gondar, north-west Ethiopia, was investigated. Between April and August 1995, 728 women consented to enter the study. Prevalence rates were 5.9% (41/693) for chlamydial antigen in cervix, 18.8% (113/600) for syphilis (Treponema pallidum haemagglutination assay [TPHA]) and 25.3% (150/593) for HIV. Active syphilis (RPR)+, TPHA+ was detected in 74% (44/597). HIV infection rate was higher among women with higher age of first marriage and low gravidity. It was significantly associated with young age, urban residence, and presence of genital ulcer (odds ratio [OR] = 6.3), and lymphadenopathy (OR = 2.8) on examination. Women seropositive for syphilis had married at an earlier age, were significantly older and had changed husbands. Low gravidity and age < 30 were independently significant risk factors for cervical chlamydial antigen positivity which was predominantly asymptomatic. Significant association was observed between HIV infection and syphilis (OR = 2.6). Active syphilis was associated with chlamydial (OR = 3.4) and HIV infection (OR = 4.1). The rate of 23.4% and 15.1% of HIV seropositivity among ANC attenders and rural women respectively is an indicator of the rapid progression of the HIV epidemic in the area.

Adolescent↗
PubMed1998

Calcified plaque is common in the carotid and femoral arteries of dialysis patients without clinical vascular disease.

BACKGROUND: Cardiac and vascular mortality are common in end-stage renal disease (ERSD) and are often attributed to accelerated atherosclerosis. SUBJECTS AND METHODS: We studied 24 non-diabetic ESRD patients without cardiac or vascular disease (M = 12, F = 12) and 24 age-, sex- and race-matched healthy controls. All underwent B-mode ultrasound for carotid and femoral intima media thickness (IMT) and plaque (% stenosis) together with blood pressure (BP), and echocardiograms to determine left ventricular mass. RESULTS: Both BP and mean IMT were similar in patients and controls. However, discrete plaque was present in 71% (17/24) of patients compared with 21% (5/24) of controls (P = 0.001), and % stenosis was greater in patients (carotid 12.2 +/- 11% vs 2.3 +/- 5.9%, P < 0.0004; femoral 16.4 +/- 19.1% vs 3.1 +/- 6.4%, P < 0.003). Plaque was soft/atheromatous in 3 of the 5 controls, but not in any of the 17 patients (P = 0.007), all of whom had calcified lesions. BP and cholesterol were not correlated with IMT or plaque in patients, but in control subjects carotid IMT was correlated with systolic BP (r = 0.66, P < 0.0005) and diastolic BP (r = 0.45, P < 0.03). In patients, the only independent variables related to vascular morphology were serum albumin which was inversely related to IMT (P < 0.03) and to plaque (carotid P < 0.05, femoral P < 0.02) and age, which was related to femoral plaque only (P < 0.04). Left ventricular end-diastolic internal dimension, not LVMI, correlated positively with carotid IMT (P < 0.04). CONCLUSION: Our results show that calcified plaque is common in ESRD patients and hypoalbuminaemia may be an associated factor.

Adult↗