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Biomedical subjects

H Morgan

Publications and source records attributed to H Morgan.

At least 19 recordsLinked to original sources
PubMed2003

Dielectric spectroscopy of Tobacco Mosaic Virus.

The dielectric properties of the Tobacco Mosaic Virus (TMV) have been measured using time domain dielectric spectroscopy (TDDS) in the temperature range from 1 to 40 degrees C. A single dielectric dispersion is observed in the MHz range. The activation energy of the process is found to be in the range 1-2 kcal/mol. The experimental data could not be completely accounted for by current theoretical models, but evidence indicates that the dielectric loss arises from polarisation of charge on and around the virus.

Electric Conductivity↗
PubMed2003

Pumping of liquids with ac voltages applied to asymmetric pairs of microelectrodes.

The net flow of electrolyte induced by an ac electric potential applied to an array of asymmetric pairs of microelectrodes has recently been reported. The interaction between the oscillating electric field and the oscillating induced charge at the diffuse double layer on the electrodes results in a steady electro-osmotic velocity distribution on top of the electrodes. This slip velocity distribution is anisotropic and produces a net flow of fluid. This paper presents a theoretical analysis of the pumping phenomena based upon an electro-osmotic model in ac fields. The electrical equations are solved numerically using the charge simulation method. The bulk flow generated by the electro-osmotic slip velocity is calculated. The dependence of the fluid flow on voltage and frequency is described and compared to experiments.

Journal Article↗
PubMed2002

The imPaCT study: a randomised controlled trial to evaluate a hospital palliative care team.

A randomised controlled trial was undertaken to assess the effectiveness of a hospital Palliative Care Team (PCT) on physical symptoms and health-related quality of life (HRQoL); patient, family carer and primary care professional reported satisfaction with care; and health service resource use. The full package of advice and support provided by a multidisciplinary specialist PCT ('full-PCT') was compared with limited telephone advice ('telephone-PCT', the control group) in the setting of a teaching hospital trust in the SW of England. The trial recruited 261 out of 684 new inpatient referrals; 175 were allocated to 'full-PCT', 86 to 'telephone-PCT' (2 : 1 randomisation); with 191 (73%) being assessed at 1 week. There were highly significant improvements in symptoms, HRQoL, mood and 'emotional bother' in 'full-PCT' at 1 week, maintained over the 4-week follow-up. A smaller effect was seen in 'telephone-PCT'; there were no significant differences between the groups. Satisfaction with care in both groups was high and there was no significant difference between them. These data reflect a high standard of care of patients dying of cancer and other chronic diseases in an acute hospital environment, but do not demonstrate a difference between the two models of service delivery of specialist palliative care.

Activities of Daily Living↗
PubMed2002

Fluid flow induced by nonuniform ac electric fields in electrolytes on microelectrodes. III. Observation of streamlines and numerical simulation.

The application of a nonuniform ac electric field to an electrolyte using coplanar microelectrodes results in steady fluid flow. The flow has its origin in the interaction of the tangential component of the nonuniform field with the induced charge in the electrical double layer on the electrode surfaces. Termed ac electro-osmosis, the flow has been studied experimentally and theoretically using linear analysis. This paper presents experimental observations of the fluid flow profile obtained by superimposing images of particle movement in a plane normal to the electrode surface. These experimental streamlines demonstrate that the fluid flow is driven at the surface of the electrodes. Experimental measurements of the impedance of the electrical double layer on the electrodes are also presented. The potential drop across the double layer at the surface of the electrodes is calculated numerically using a linear double layer model, and also using the impedance of the double layer obtained from experimental data. The ac electro-osmotic flow at the surface of the electrodes is then calculated using the Helmholtz-Smoluchowski formula. The bulk fluid flow driven by this surface velocity is numerically calculated as a function of frequency and good agreement is found between the numerical and experimental streamlines.

Journal Article↗
PubMed2002

First-trimester, three-dimensional transvaginal ultrasound volumetry in normal pregnancies and spontaneous miscarriages.

OBJECTIVE: The aim of this study was to perform three-dimensional ultrasound volumetry of intrauterine contents in cases of normal and failed pregnancies and correlate these with conventional two-dimensional measurements. METHODS: This was a cross-sectional observational study. Three-dimensional volumetric data were collected from a total of 111 patients with first-trimester singleton pregnancies together with conventional two-dimensional measurements. A single investigator performed all ultrasound scans and volume measurements. RESULTS: Among 111 participants, 30 had an ongoing pregnancy and 81 had a miscarriage (anembryonic pregnancy 30, missed miscarriage 30, and incomplete miscarriage 21). There were no significant differences in age, parity, or gestational age between groups. A positive linear correlation was demonstrable between the crown-rump length and gestational sac volume in normal pregnancies (r = 0.962) and between gestational sac volume and gestational age, but the correlation was weaker in cases of missed miscarriage (r = 0.561). The volume of the retained products of conception as measured by three-dimensional ultrasound volumetry in cases of incomplete miscarriage also showed a strong linear correlation (r = 0.938) to their maximum anterior-posterior diameter. There was an exponential correlation between the mean gestational sac diameter and gestational sac volume and the crown-rump length and embryonic volume in cases of both normal and failed pregnancies. The mean gestational sac diameter:crown-rump length ratio (P = 0.008) and gestational sac volume:embryonic volume ratio (P = 0.023) in missed miscarriages were significantly higher than those in ongoing pregnancies. CONCLUSION: Three-dimensional ultrasound volumetry of intrauterine contents in normal and failed pregnancies correlates well with conventional two-dimensional measurements. Volumetric assessment does not seem to improve the diagnosis of miscarriage. However, its potential to predict pregnancies that will fail and determine the appropriate management regime for individual patients merits further research.

Abortion, Spontaneous↗
PubMed2002

Evaluation of the impact of current antismoking advice in the UK on women with planned pregnancies.

Smoking during pregnancy (active or passive) is associated with increased health risks to the unborn child. Current policy on antismoking advice for pregnant women in the United Kingdom is based essentially on written information by means of leaflets given to them at the first antenatal visit. We evaluated the impact of this policy on the smoking habits of pregnant women. A sample of 180 women with planned pregnancies attending antenatal clinics at two teaching hospitals in North London was recruited over a 6-month period. All women were provided with the current antismoking counselling at their first visit at the end of the first trimester and asked to fill in a questionnaire around mid-gestation. The study population included 117 (65%) women who did not currently smoke (non-smokers) and 63 (35%) who were active smokers at the beginning of their pregnancy. Thirty-nine non-smokers were found to be passive smokers. Three women took up smoking during pregnancy. Among the smokers, 53 (84.1%) women made no change in their smoking behaviour during pregnancy, seven (11.1%) reduced their cigarette consumption and only three (4.8%) gave up smoking during the first half of pregnancy. None of the partners changed their smoking habits. All women were aware that smoking in pregnancy could be deleterious to their health and that of their fetus. Despite awareness of dangers of smoking, the prevalence of smoking among pregnant women remains very high after the first antenatal visit and the current antismoking policy based essentially on leaflets is not effective. Health-care professionals should spend more time to inform women adequately about the dangers of smoking and help them to quit before pregnancy.

Attitude to Health↗
PubMed2001

The dielectrophoretic levitation and separation of latex beads in microchips.

A linear travelling wave dielectrophoretic (twDEP) microchip was fabricated and used to investigate both the levitation and the twDEP motion of latex beads as a function of applied potential and frequency, suspending medium conductivity, bead size, and surface characteristics. The surface conductance of the latex beads was characterised by measurement of the dielectrophoretic (DEP) crossover frequency. Collection of sample prior to initiation of twDEP was achieved using positive DEP forces generated by an integrated pair of parallel electrodes positioned in front of the twDEP array within the microfluidic channel. The principle of linear twDEP separation is shown using latex beads and rabbit heart cells.

Algorithms↗
PubMed2001

Sequencing, high-level expression and phylogeny of the pyrophosphate-dependent phosphofructokinase from the thermophilic spirochete Spirochaeta thermophila.

The full-length gene encoding a 554-amino-acid, active pyrophosphate-dependent phosphofructokinase from Spirochaeta thermophila was cloned and sequenced using a combination of degenerate and inverse PCR, and the enzyme expressed to a high level in Escherichia coli. The recombinant enzyme, with a calculated molecular mass of 61 kDa, was purified to near homogeneity and found to be similar to the purified native enzyme for most properties examined. Phylogenetic analysis demonstrated a close relationship between the thermophilic S. thermophila phosphofructokinase and the large beta-subunits of the phosphofructokinases from Borrelia burgdorferi and Treponema pallidum.

Amino Acid Sequence↗
PubMed2001

Dielectrophoretic manipulation and characterization of herpes simplex virus-1 capsids.

The dielectrophoretic behaviour of the capsids of herpes simplex virus type-1 has been measured over a range of conductivities of KCl solutions, with and without the addition of mannitol. The dielectrophoretic response of the capsids was recorded by measuring the frequency corresponding to zero dielectrophoretic force. The data were analysed using a multi-shelled model, and the permittivity and conductivity of the particles estimated. The capsid was modelled as a porous protein shell through which suspending medium passes, an inner chamber containing suspending medium in equilibrium with the outside, and a central core of protein (the scaffold). Capsids suspended in KCl without mannitol exhibited a different behaviour to those suspended in KCl with mannitol.

Biophysical Phenomena↗
PubMed2001

Pseudotumor deltoideus: a previously undescribed anatomic variant at the deltoid insertion site.

A spectrum of eccentric bone irregularities were observed in the humeral deltoid tuberosity region of five patients. Patients were referred for associated pain or for the incidental radiographic findings. The lesions are characterized radiographically by a relative lucency at or adjacent to the deltoid tuberosity, variably increased uptake on the bone scan, and mild cortical irregularity or adjacent eccentric marrow abnormality on MRI and CT. The term pseudotumor deltoideus is coined for these previously undescribed anatomic variants. Imaging studies and extended clinical follow-up in these patients support an inactive or indolent process that may be managed conservatively. The potential etiology and role of these cortical irregularities as tumor simulators is emphasized.

Adult↗
PubMed2001

Ambulatory blood pressure monitoring after renal transplantation in children.

Hypertension occurs commonly following renal transplantation and may cause end organ damage, such as cardiac hypertrophy. This study seeks to determine which features of hypertension are related to cardiac hypertrophy in children after renal transplantation. Ambulatory blood pressure monitoring (ABPM) was performed in 45 pediatric patients, 4.9+/-3.0 years after renal transplantation. ABPM data were related to clinical features and echocardiographic measurements. Hypertension was demonstrated in 33% of patients by casual blood pressure (BP) measurement and in 40% by ABPM. The mean percentage nighttime decline in BP (dipping) was 8.9+/-5.0% for systolic and 13.9+/-7.7% for diastolic BP. Abnormal dipping (<10%) was seen in 58% of patients. BP load (percentage of BP recordings above 95th percentile) was >30% in 44% of patients. Patients taking antihypertensive medication had more abnormal dipping and greater nighttime BP load. The prevalence of left ventricular hypertrophy was 72% before transplantation, 75% after transplantation, and 54% near to ABPM. Left ventricular mass (LVM) indexed to height(3) decreased significantly after transplantation. (40.2+/-14.7 vs. 35.0+/-8.3 g/m(3), P=0.0002). There was no significant relationship between ABPM data and LVM. ABPM was not able to differentiate those patients with persistently elevated LVM. The results suggest that hypertension is not always associated with cardiac hypertrophy following pediatric renal transplantation.

Adolescent↗
PubMed2001

Use of ultrasound to improve the safety of postgraduate training in obstetrics and gynaecology.

Supervised clinical work is perhaps the most valuable component of postgraduate training and has a long-term impact. Senior clinicians not only take the responsibility of teaching and supervising junior doctors but also most of them take the consequences of any clinical failures or mistakes associated with the training. Despite the introduction of simulators and computer-assisted learning, practice on real patients is still required to learn many skills in obstetrics and gynaecology. Training must be safe, because trainees or trainers must not put our patients at risk as part of the process of learning to heal others. Ultrasound can be used to demonstrate and guide several procedures that have been performed 'blindly' in the past. This technology can reduce the risks associated with training and supervision of junior doctors.

Education, Medical, Continuing↗
PubMed2001

Depression in men.

BACKGROUND: The suicide rate is five times higher for men compared with that for women, yet the rate of depression is twice as great in women compared with men. Men are less likely than women to present to their doctors with concerns about physical and psychological problems. Men seem to be more vulnerable to becoming depressed in the context of social and economic change compared with women. OBJECTIVE: To raise awareness regarding detection and treatment of depression in men in a primary care setting. DISCUSSION: General practitioners are ideally suited to diagnose and treat depression early. By increasing GPs' awareness of depression, utilising screening instruments in everyday clinical practice, and having psychoeducation materials available, GPs can help to destigmatise and effectively treat depression in men. Encouraging men to talk about their problems with the use of open ended questions and engaging a partner or family member helps to encourage treatment adherence.

Adult↗
PubMed2000

Dielectric relaxation measurements of 12 kbp plasmid DNA.

The dielectric properties of 12 kbp plasmid DNA have been measured as a function of temperature in the range 5 degrees C to 40 degrees C. Time domain reflectometry was used to obtain dielectric data over the frequency range from 200 kHz to 3 GHz. Values of the frequency dependent polarisability per DNA macromolecule have been determined from the measurements. Possible mechanisms that could account for the dielectric dispersion are also discussed, in particular the counterion fluctuation model of Manning-Mandel-Oosawa.

Electric Conductivity↗