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Biomedical subjects

H Morgan

Publications and source records attributed to H Morgan.

At least 19 recordsLinked to original sources
PubMed2006

Global endometrial ablation: a modern day solution to an age-old problem.

Menorrhagia remains a significant health issue for women worldwide. Traditionally hysterectomy has been the treatment of choice when excessive menstrual bleeding remains unresolved by hormonal manipulation. In an attempt to provide a less invasive alternative to hysterectomy, traditional techniques such as rollerball endometrial ablation were developed 20 years ago. Although extremely effective, they possessed the potential of significant intra-operative risks and their success depended on high technical proficiency of the surgeon. As surgery and technology evolved, second generation endometrial ablation devices were developed which demonstrated improved safety and efficacy rates that paralleled traditional treatments. Since 1997, the Food and Drug Administration (FDA) has approved five such devices for use in the United States. Each possesses a unique technology profile with supporting level I evidence that allows for the treatment of a wide variety of uterine anatomy.

Endometrium↗
PubMed2006

Controlled delivery of membrane proteins to artificial lipid bilayers by nystatin-ergosterol modulated vesicle fusion.

The study of ion channels and other membrane proteins and their potential use as biosensors and drug screening targets require their reconstitution in an artificial membrane. These applications would greatly benefit from microfabricated devices in which stable artificial lipid bilayers can be rapidly and reliably formed. However, the amount of protein delivered to the bilayer must be carefully controlled. A vesicle fusion technique is investigated where composite ion channels of the polyene antibiotic nystatin and the sterol ergosterol are employed to render protein-carrying vesicles fusogenic. After fusion with an ergosterol-free artificial bilayer, the nystatin-ergosterol channels do not dissociate immediately and thus cause a transient current signal that marks the vesicle fusion event. Experimental pitfalls of this method were identified, the influence of the nystatin and ergosterol concentration on the fusion rate and the shape of the fusion event marker was explored, and the number of different lipid species was reduced. Under these conditions, the -amyloid peptide could be delivered in a controlled manner to a standard planar bilayer. Additionally, electrical recordings were obtained of vesicles fusing with a planar lipid bilayer in a microfabricated device, demonstrating the suitability of nystatin-ergosterol modulated vesicle fusion for protein delivery within microsystems.

Amyloid beta-Peptides↗
PubMed2006

Renal MALToma: an unusual lymphoma in a patient with lupus.

Non-Hodgkin's Lymphomas (NHL) have been reported in association with autoimmune disorders particularly Sjogren's syndrome. We report a case of renal MALToma, an unusual NHL in an 84-year-old Caucasian lady with long-standing, non-aggressive Systemic Lupus Erythematosis with no associated Sjorgen's syndrome and who never received cytotoxics.

Aged, 80 and over↗
PubMed2005

On-chip high-speed sorting of micron-sized particles for high-throughput analysis.

A new design of particle sorting chip is presented. The device employs a dielectrophoretic gate that deflects particles into one of two microfluidic channels at high speed. The device operates by focussing particles into the central streamline of the main flow channel using dielectrophoretic focussing. At the sorting junction (T- or Y-junction) two sets of electrodes produce a small dielectrophoretic force that pushes the particle into one or other of the outlet channels, where they are carried under the pressure-driven fluid flow to the outlet. For a 40 microm wide and high channel, it is shown that 6 microm diameter particles can be deflected at a rate of 300/s. The principle of a fully automated sorting device is demonstrated by separating fluorescent from non-fluorescent latex beads.

Cell Separation↗
PubMed2005

Group B streptococcus disease in neonates: to screen or not to screen?

An audit was undertaken of the prevention of early-onset Group B streptococcus (EOGBS) disease in neonates. The prevention strategy in use involved offering Intra-partum Antibiotic Prophylaxis (IAP) to mothers with identified risk factors, which include maternal fever in labour > 38 degrees C, previous baby with GBS disease, prolonged rupture of membranes > 18 h, pre-term labour, GBS urinary tract infection and known GBS carriage. The most common risk factor identified was GBS carriage (41%) which was known ante-partum but logistical problems prevented these mothers from receiving adequate prophylaxis 4 h before delivery and so were classified as at risk of GBS disease. We found an incidence of GBS in our unit of 0.55 per 1,000 births over the study period. One neonate developed EOGBS disease and the mother had no identifiable risk factor ante-partum/intra-partum. Recent recommendations from the Royal College of Obstetricians and Gynaecologists (RCOG) could reduce the number of babies having sepsis screens performed as the time interval from beginning IAP to delivery has been shortened to 2 h and routine surface cultures or blood cultures are not recommended in well newborns. The evidence is lacking at this point to recommend universal screening for GBS in all pregnant women but patients are increasingly aware of this option and may request anogenital swabs to assess GBS carriage.

Adolescent↗
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↗
PubMed2003

3D focusing of nanoparticles in microfluidic channels.

Dynamic focusing of particles can be used to centre particles in a fluid stream, ensuring the passage of the particles through a specified detection volume. This paper describes a method for focusing nanoparticles using dielectrophoresis. The method differs from other focusing methods in that it manipulates the particles and not the fluid. Experimental focusing is demonstrated for a range of different particle types, and discussed in terms of the operational limits of the device. Dynamic numerical simulations of the particle motion in the device are presented and compared with the experimental results. The potential of the device for nanoparticle control and manipulation in microfluidic chips is discussed.

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

Interconnected reversible lab-on-a-chip technology.

Interconnected lab-on-a-chip modules with minimal dead volume have been developed resulting in the 'plug and play' concept based upon a reversible bonding process. This paper describes the detail of a chip to chip interconnection method, where devices have been aligned and bonded within 15 min and rapidly disassembled in under 5 min. The transport of fluorescein between the chip modules was used as a model microfluidic system and analysed in order to demonstrate the electrophoretic performance of the device and the interconnected junction. Using this technology, in the future different modules for various applications can be developed and interconnected, depending on the required applications. In addition, this simple but rapid method of chip to chip connection overcomes potential problems associated with integrating incompatible materials on one device.

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↗