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Biomedical subjects

P Stone

Publications and source records attributed to P Stone.

At least 19 recordsLinked to original sources
PubMed2005

Traffic related pollution and heart rate variability in a panel of elderly subjects.

BACKGROUND: Particulate air pollution has been associated with increased cardiovascular deaths and hospital admissions. To help understand the mechanisms, the types of particles most involved, and the types of persons most susceptible, the association between exposure to summertime air pollution and heart rate variability (HRV) was examined in a panel study of 28 elderly subjects. METHODS: Subjects were seen once a week for up to 12 weeks and HRV (SDNN, r-MSSD, PNN50, low frequency/high frequency ratio (LFHFR)) was measured for approximately 30 minutes at each session using a defined protocol. Temperature, day of the week, and hour of the day were controlled, and dummy variables for each subject were controlled for subject specific risk factors. RESULTS: PM2.5 was associated with r-MSSD (-10.1% change for an interquartile range (IQR) increase in exposure (95% CI -2.8 to -16.9)) and PNN50, but stronger associations were seen with black carbon, an indicator of traffic particles, which was also associated with SDNN (-4.6% per IQR (95% CI -2.0 to -7.2)) and LFHFR. Secondary particles were more weakly associated with r-MSSD, as was ozone. No associations were seen with SO2 or NO2. CO had similar patterns of association to black carbon, which disappeared after controlling for black carbon. Black carbon had a substantially higher effect on SDNN in subjects who had had a previous myocardial infarction (-12.7%, 95% CI -5.7 to -19.25). CONCLUSIONS: Particles, especially from traffic, are associated with disturbances of autonomic control of the heart.

Aged↗
PubMed2004

The structure and reactivity of anchored nanoparticles on a reducible support.

We have used scanning tunnelling microscopy (STM) to study the structure and reactivity of metal nanoparticles on a TiO2(110) surface. We have deposited two metals (Pt and Ru) using different techniques, metal vapour deposition (MVD) for Pt and metal organic chemical vapour deposition (MOCVD) for Ru. Pt was deposited onto a (1 x 3) reconstructed surface and is found to sinter at temperatures above 873 K, where the onset of nanoparticle mobility is expected. The effect that Pt has on the rate of re-oxidation of a more reduced titania sample with a (1 x 1) terminated surface was studied. At 673 K no preferential re-growth around the particles is observed and this has been attributed to the desorption characteristics of oxygen from Pt surfaces. The results are compared to those obtained from Pd covered TiO2 where such preferential growth has previously been observed. Ru was deposited using a carbonyl precursor, Ru3(CO)12, and is found to adsorb preferentially on the (1 x 2) rows of a surface consisting of both (1 x 1) and (1 x 2) added row structures. Upon annealing the compound is initially de-carbonylated to leave Ru nanoparticles on the surface, which can then sinter with increasing temperature. These particles have been alloyed with Pt and their re-oxidation characteristics studied. The alloy particles alter the oxygen desorption characteristics from that of the constituent elements (Pt and Ru) and consequently an enhancement in the rate of re-oxidation of a TiO2(110) surface at 673 K is observed.

Microscopy, Scanning Tunneling↗
PubMed2004

Portable method for the determination of snoring site by sound analysis.

It has been shown that computerized sound frequency analysis can be used to distinguish between different snoring sites. The aim of this study was to investigate whether a portable recording method using audiotapes and digital minidisc formats could produce waveforms similar to a computer recording. The snores of 12 subjects in their natural sleep were recorded onto audiotape, minidisc and directly onto a computer. For each snorer and recording method 30 snore samples were analysed and their power ratio was calculated indicating the relative amount of sound below and above a set frequency. It was found that the power ratios from audiotape recordings were significantly different to those from computer recordings for all snoring sites (p = 0.0007), whereas there was no significant difference between minidisc and computer recordings (p = 0.41). These results indicate that it would be possible to base a portable snore analysis system for site determination on minidisc, but not on audiotape recordings.

Adult↗
PubMed2003

Cancer-related fatigue--a difference of opinion? Results of a multicentre survey of healthcare professionals, patients and caregivers.

UNLABELLED: The objective of this study was to investigate the perceptions of patients with cancer, their caregivers and healthcare professionals (HCPs) about fatigue and its impact on quality of life. It was a cross-sectional survey, the respondents were patients with cancer attending three UK regional cancer centres (n = 1,370), their informal caregivers (n = 1,370) and a random selection of HCPs (oncologists/nurses/radiographers/haematologists; n = 1,098). The response rates for patients, caregivers and HCPs were 42%, 33% and 34% respectively. Fatigue was reported to affect 56% of patients and to have a considerable impact on quality of life. Caregivers also recognized that fatigue was a common problem, with significant effects on patients' quality of life and impact on themselves. Healthcare professionals recognized that fatigue was a common problem for their patients but overestimated its impact on some aspects of patients' daily lives. Although most HCPs reported that they prescribed/recommended treatment for over half of their patients, only 14% of patients reported receiving any such treatment. The most common advice was to take more rest and relaxation. CONCLUSIONS: patients with cancer report that fatigue is a common and distressing symptom and the importance of this symptom is generally recognized by both HCPs and lay-carers. Healthcare professionals need more information about the effectiveness of existing interventions for cancer-related fatigue and further research is required to improve the current management of this debilitating symptom.

Attitude of Health Personnel↗
PubMed2002

Sound frequency analysis and the site of snoring in natural and induced sleep.

The aim of this study was to compare the snoring sounds induced during sleep nasendoscopy, and to compare them with those of natural sleep using sound frequency spectra. The snoring of 16 subjects was digitally recorded during natural and induced sleep, noting the site of vibration during sleep nasendoscopy. Patients with palatal snoring during sleep nasendoscopy had a median peak frequency at 137 Hz (118 snore samples). The peak frequency of tongue-base snoring was 1243 Hz (10 snore samples), and simultaneous palate and tongue was 190 Hz (six snore samples). The median power ratios were 7, 0.2 and 5 respectively. The centre frequencies were 371, 1094 and 404 Hz respectively. Epiglottic snores had a peak frequency of 490 Hz (five snore samples). Comparison of the induced (n = 118) and natural (n = 300) snore samples of the 12 palatal snorers showed a significant difference in both the power ratio and centre frequencies (P = 0.031 and P = 0.049). The peak frequency position was similar (P = 0.34). Our results indicate that induced snores contain a higher frequency component of sound, not evident during natural snoring. This is consistent with an element of tongue-base snoring. Although there is good correlation generally, sleep nasendoscopy may not accurately reflect natural snoring.

Endoscopy↗
PubMed2001

A novel system for investigating the ability of smooth muscle cells and fibroblasts to regulate adhesion of flowing leukocytes to endothelial cells.

Stromal cells may contribute to the inflammatory processes which lead to the recruitment of circulating leukocytes. Here, we describe a multicellular model in which chosen cellular elements of tissue can be cocultured with endothelial cells (EC). Cocultures can be incorporated into a novel parallel plate flow chamber to determine if stromal cells influence the patterns of leukocyte adhesion to the EC. As an example relevant to the pathology of atherosclerosis, EC were cultured with arterial smooth muscle cells (SMC) of the 'secretory' phenotype. EC and secretory SMC were cultured on the opposite faces of commercially available porous polyethylene terepthalate (PET) culture inserts, which fitted into a parallel plate flow chamber. Binding of flowing purified lymphocytes, labelled with the fluorochrome calcein-AM, to cocultured EC was assessed by fluorescence microscopy. Lymphocyte adhesion was negligible on unstimulated EC cultured alone or cocultured with SMC. However, when tumour necrosis factor-alpha (TNF) was added to cocultures, the EC supported greatly increased levels of lymphocyte adhesion compared to TNF-treated EC cultured alone. Additionally, cocultured EC responded to TNF at concentrations far below those at which EC cultured alone responded. This priming was specific in that skin fibroblasts cocultured with EC did not modify lymphocyte adhesion induced by TNF. Thus, we have developed a coculture model to determine the ability of tissue stromal cells to modify leukocyte recruitment. This may have wide applications in the study of the cellular pathology of inflammation by allowing the contribution of the local microenvironment to be assessed.

Arteriosclerosis↗
PubMed2001

Comparison of the effects of radiographic contrast media on dehydration and filterability of red blood cells from donors homozygous for hemoglobin A or hemoglobin S.

Iodinated radiographic contrast media have traditionally been contraindicated in patients with sickle cell disease because their high osmolality may induce osmotic shrinkage of red blood cells, impair blood flow through the microcirculation, and precipitate or exacerbate a sickle cell crisis. This study investigated that concept by comparing the hematological and rheological effects in vitro of four X-ray contrast media of differing osmolalities: Visipaque (290 mOsm/kg), Hexabrix (600 mOsm/kg), Omnipaque (844 mOsm/kg), and RenoCal-76 (1940 mOsm/kg). Blood was tested from 10 normal and 10 sickle cell donors at drug concentrations of 0, 1, 10, and 30% w/v in an attempt to approximate the relative concentrations of contrast medium to blood that might occur during the bolus-injection and circulation-diluted phases of drug administration. Parameters evaluated included hematology, red cell morphology, and red cell flow resistance through a micropore filter to approximate the microcirculatory effects. Significant hematological effects for both normal and sickle cell donors included a concentration dependent decrease in hematocrit and MCV, and increase in MCHC, all of which varied directly with the osmolality of the contrast media in the order of RenoCal-76 > Omnipaque > Hexabrix > Visipaque. The contrast media had minor effects on red blood cell morphology except for RenoCal-76, 10-30% in which marked echinocytosis was observed. There was no significant increase in the number of irreversibly sickled cells in donors with hemoglobin S. Filterability of red cell suspensions through capillary size pores was impaired in both normal and sickle cell samples in direct proportion to the osmolality of the contrast media, as listed above. Filterability effects were greater for sickle cells than for normal red cells. Visipaque, which was closest to isotonicity, had little effect on red cell volume and had no significant effect on filterability of normal or sickle cells. These results suggest that microcirculatory impairment following infusion of contrast media may occur in sickle patients because of the unusual rheological sensitivity of HbSS red cells, and may be avoided by choice of an isotonic medium.

Anemia, Sickle Cell↗
PubMed2001

Fatigue in patients with cancers of the breast or prostate undergoing radical radiotherapy.

To determine the prevalence, severity, and correlates of fatigue among patients with cancers of the prostate or breast receiving high dose radiotherapy with curative intent, a prospective, questionnaire-based study evaluated a convenience sample of 62 patients who were about to start a course of radiotherapy. Patients were assessed immediately prior to treatment, and again within a week of finishing. Fatigue was assessed using the Fatigue Severity Scale (FSS) and the Bidimensional Fatigue Scale (BFS). Quality of life was assessed using the European Organisation for Research and Treatment of Cancer 30-item Quality of Life Questionnaire (EORTC QLQc30). Psychological distress was assessed using the Hospital Anxiety and Depression Scale (HADS). Personality Traits were assessed using the Eysenck Personality Inventory (EPI). Fatigue severity increased significantly on 3 out of the 5 assessment instruments used. Radiotherapy was associated with a decline in global quality of life, role, cognitive and social functioning, and an increase in nausea/vomiting, pain, insomnia, diarrhea, and financial difficulty. At baseline, 39% of the variation in fatigue scores among the patients could be explained by a combination of measures of their global quality of life and physical functioning. A combination of fatigue and anxiety scores at baseline was able to predict 54% of the variation in fatigue scores at the completion of radiotherapy. These data indicate that fatigue is a significant problem for patients receiving radical radiotherapy, although its severity is relatively modest.

Adult↗
PubMed2001

Characteristics of staff victims of patient assault: ten year analysis of the Assaulted Staff Action Program (ASAP).

Patient assaults on staff have been a continuing risk for inpatient and community-based psychiatric healthcare providers. This study presents a ten-year analysis of the characteristics of staff victims of patient assaults in one public mental health system of care, a period which included the transition to managed care initiatives within this system. Assault data was gathered within the context of the Assaulted Staff Action Program (ASAP), a voluntary, system-wide, peer-help, crisis intervention program that is designed to assist employees with the psychological sequelae of these patient events. In general, the findings were consistent with previously reported inpatient and community studies. Less experienced, less formally trained employees remain at high risk. The impact of managed care initiatives was found in community residences where younger female staff were most at risk. The implications of the findings and possible risk management strategies are discussed.

Adult↗
PubMed2001

A prospective survey of the use of dexamethasone on a palliative care unit.

One hundred and six consecutive patients started on glucocorticosteroids (steroids) according to a defined prescription policy were surveyed each week to document the indications for use, any beneficial effect, any toxicity incurred and the reason for stopping. All patients had advanced malignant disease and survived for a median of 40.5 days (range 1-398+ days) from the start of steroid treatment. Fifty-seven per cent of patients completed three or more assessments. The most common specific indications for starting steroids were spinal cord compression, cerebral metastases, lymphangitis carcinomatosa and intestinal obstruction. The most common non-specific indications were anorexia, nausea, low mood, pain and vomiting. The median duration of steroid use was 21.5 days (range 1-89 days). The most common reason for the discontinuation of steroids was death or deteriorating condition. Symptom scores improved at some stage for the majority of patients started on steroids for anorexia, nausea, pain, low mood, vomiting and weakness but not in patients complaining of dyspnoea or poor mobility. The most common side-effects that were most probably attributable to steroid therapy were oral candidosis and proximal myopathy. The benefits of steroids when used according to defined guidelines were thought to outweigh toxicity.

Anti-Inflammatory Agents↗
PubMed2001

Māori women and menopause.

Māori are the indigenous people of New Zealand who in total make up 14.5% of the population. Although this group has a significantly lower life expectancy than non-Māori, coupled with increased rates of mortality and morbidity, very little is known about the menopausal health needs of older Māori women. As the first step in addressing the health needs of this group, older Māori women's definitions, attitudes, symptoms, expectations and health needs at menopause need to be identified and described. The study Ngā Ruahine or "Māori in Menopause" is the foundation study of the Aotearoa Women's Health Initiative (AWHI). AWHI is a women's health programme being developed by the Wellington School of Medicine, which involves a suite of studies. The objective is to describe the journey of older Māori women through menopause and beyond and to compare and contrast the experience of Māori women from both traditional and contemporary upbringings, with reference to the Pākehā (European) population. It is hoped that this work could lead to further studies such as, for example, a longitudinal observational study looking at older New Zealand women. The potential significance of this approach is discussed.

Age Factors↗
PubMed2000

An investigation into the incidence of toxoplasmosis in pregnancy in New Zealand.

AIM: To estimate the incidence of toxoplasmosis in pregnancy in New Zealand and consider whether there is a case for screening women in pregnancy. METHODS: The risk of maternal and fetal infection with toxoplasmosis was derived by first determining the rate of maternal seroconversion based on seroprevalence studies. The age-specific number of seroconversions in pregnancy was then estimated from the birth rate. Using reported fetal infection rates after primary maternal infection, the expected number of congenitally infected infants in one year was estimated. These incidences were compared with the number of recognised cases of toxoplasmosis infection in pregnancy and the actual number of positive IgM results at the Wellington Hospital laboratory. Using national births data, this incidence was extrapolated to estimate the number of expected cases in New Zealand. RESULTS: The annual seroconversion rate was 0.62% (95% confidence interval 0.39-0.86). On this basis, 164 primary maternal infections are expected annually with 66 fetuses being infected. Ten patients tested positive for IgM in Wellington, which averaged only one case per year being identified over the time examined in this study. CONCLUSIONS: Very few of the expected cases in pregnancy are diagnosed. Reporting rates were low when toxoplasmosis was a notifiable disease. Other means of improving detection, reporting and the avoidance of infection are discussed. More information is required before screening can be recommended in New Zealand.

Adolescent↗
PubMed2000

Circadian heart rate response to chronotherapy versus conventional therapy in patients with hypertension and myocardial ischemia.

BACKGROUND: Changes in heart rate (HR) may contribute to the higher incidence of cardiovascular events in the morning. HYPOTHESIS: The objectives of this analysis were to assess HR patterns in two populations (patients with chronic stable angina or stage I to III hypertension) and to compare the effects of various antianginal and antihypertensive treatments on HR. METHODS: This was a retrospective analysis of HR data from two clinical trials evaluating the efficacy of controlled-onset, extended-release (COER)-verapamil. The effects of COER-verapamil were compared with placebo, nifedipine gastrointestinal therapeutic system (GITS), amlodipine, and the combination of amlodipine and atenolol. RESULTS: In patients with angina (n = 498), the change from baseline in HR following 4 weeks of treatment was -6.7 +/- 10.5 beats/min in the COER-verapamil group, -10.8 +/- 10.8 beats/min in the amlodipine/atenolol group, + 2.5 +/- 9.1 beats/ min in the amlodipine monotherapy group, and -1.3 +/- 10.5 beats/min in the placebo group (p<0.001). Data were stratified based on whether patients experienced asymptomatic ischemia during baseline ambulatory electrocardiographic monitoring. The circadian HR pattern was morphologically similar in all groups; however, differences in the magnitude of HR response were evident. In the subset of patients with asymptomatic ischemia (n = 101), treatment with amlodipine monotherapy increased HR compared with placebo. In this same subset of patients, HR reductions were achieved with COER-verapamil and amlodipine/atenolol. In patients with hypertension (n = 557), the change in HR following 10 weeks of treatment was -3.3 beats/min for patients treated with COER-verapamil compared with + 2.0 beats/min for patients treated with nifedipine GITS (p < 0.0001, between-group differences). CONCLUSION: This analysis demonstrates that morphologically similar circadian patterns of HR occur in both hypertensive patients and those with angina. In addition, significant variation exists among antianginal and antihypertensive agents regarding HR effects.

Adrenergic beta-Antagonists↗
PubMed2000

Fatigue in patients with prostate cancer receiving hormone therapy.

The aim of this study was to determine the prevalence, severity and correlates of fatigue in a convenience sample of outpatients with prostate cancer prior to and following 3-months treatment with first-line hormone therapy (cyproterone acetate and goserelin). 'Severe fatigue' in the patients (n=62) was defined as a score on the Fatigue Severity Scale (FSS) greater than the 95th percentile of a group of elderly volunteers without cancer. Subjects also completed other questionnaires about fatigue and about quality of life, anxiety/depression and personality. Subjects underwent a nutritional assessment, tests of voluntary muscle function and attention. The prevalence of 'severe fatigue' at baseline was 8/58 (14%). Median FSS scores increased significantly after 3 months treatment. On multivariate analysis psychological distress explained 28% of the variance in fatigue scores. Treatment was associated with a reduction in voluntary muscle function, loss of muscle bulk, a decline in virility and potency, an improvement in pain and a reduction in nausea/vomiting. Fatigue is an important but under-recognised side-effect of hormone therapy.

Aged↗
PubMed2000

Cancer-related fatigue: inevitable, unimportant and untreatable? Results of a multi-centre patient survey. Cancer Fatigue Forum.

OBJECTIVES: To investigate cancer patients' experience of fatigue and their perceptions about the causes, management and impact of this symptom. DESIGN: Cross-sectional, questionnaire-based survey. SETTINGS: Three regional cancer centres; Glasgow, Birmingham and Southampton. PARTICIPANTS: One thousand three hundred seven outpatients with cancer attending the three units over a 30-day period. MAIN OUTCOME MEASURES: Investigator designed questionnaire and the fatigue sub-scale of the Functional Assessment of Cancer Therapy Fatigue (FACT-F) questionnaire. RESULTS: The response rate was 576 of 1307 (44%). Fatigue was reported to affect 58% of patients 'somewhat or very much'. The comparable figures for pain and nausea/vomiting were 22% and 18%, respectively. Fatigue had never been reported to the hospital doctor by 52% (281 of 538) of patients with this symptom. Only 75 patients (14%) had received treatment or advice about the management of their fatigue. Fatigue was reported to be not well-managed by 33% (180 of 538) of patients with this symptom. The comparable figures for pain and nausea/vomiting were 9% (46 of 538) and 7% (37 of 538), respectively. The median FACT-F score was 18 (range 0-52). On multivariate analysis 54% of the variation in FACT-F scores could be explained by the combination of quality of life, depression, dyspnoea, weight loss/anorexia and use of analgesics in the previous month. CONCLUSIONS: Fatigue has been identified as an important problem by patients with cancer. It affects more patients for more of the time than any other symptom and is regarded by patients as being more important than either pain or nausea/vomiting. Research into the aetiology and management of this symptom should be regarded as a priority.

Adolescent↗
PubMed2000

A study to investigate the prevalence, severity and correlates of fatigue among patients with cancer in comparison with a control group of volunteers without cancer.

BACKGROUND: Determining the prevalence of fatigue among cancer patients is complicated by the high prevalence of fatigue symptoms in the general population. The aim of this study was to determine the prevalence, severity and correlates of fatigue among both cancer patients and control subjects without cancer. PATIENTS AND METHODS: A total of 227 cancer patients and 98 control subjects were recruited to the study. They completed a number of questionnaires about fatigue, quality of life and psychological symptoms. The majority of subjects also underwent assessment of voluntary muscle function and nutritional status. Severe fatigue in the patients was defined as a score on the Fatigue Severity Scale in excess of the 95th percentile of the control group. RESULTS: The prevalence of severe fatigue was 15% among patients with recently diagnosed breast cancer, 16% among patients with recently diagnosed prostate cancer, 50% among patients with inoperable non small cell lung cancer and 78% among patients receiving specialist inpatient palliative care. In the patients a combination of dyspnoea, psychological distress, pain, and a measure of overall disease burden accounted for 56% of the variance in fatigue scores. CONCLUSIONS: Severe fatigue is a common problem among cancer patients, particularly those with advanced disease. Fatigue is significantly associated with the severity of psychological symptoms (anxiety and depression) and with the severity of pain and dyspnoea.

Adult↗
PubMed2000

Do oral appliances enlarge the airway in patients with obstructive sleep apnoea? A prospective computerized tomographic study.

This study evaluated the effect of an anterior mandibular positioning appliance (AMPA) on minimum pharyngeal cross-sectional area (MPCSA) in 32 conscious supine obstructive sleep apnoea (OSA) subjects. The change in MPCSA was measured using low dose computerized tomography, with and without an AMPA in situ. The results showed that the mean presenting respiratory disturbance index (RDI) was 26.6 events/hour, with a body mass index of 28.6 kg/m2 and mean age of 51.5 years. There was a statistically significant increase in MPCSA of 28.34 mm2 on appliance insertion (SD = 59.06 mm2; range -145 to +190 mm2; P = 0.011). The mean mandibular displacement was 5.73 mm (SD = 2.51 mm) in protrusion and 8.27 mm (SD = 4.51 mm) inferiorly. A poor correlation was found between the size of the mandibular displacement and the change in MPCSA (protrusion r = 0.268; inferiorly r = 0.240, P > 0.05). In conclusion, the AMPA significantly increased MPCSA, suggesting that it may be an effective therapy for OSA. There was, however, a wide but unpredictable individual variation of response. As a small number of patients may worsen in their condition with temporary mandibular advancement (TMA), it is essential that all patients treated with TMA should be investigated by polysomnography both before and after treatment.

Adult↗