Biomedical subjects

E Wells

Publications and source records attributed to E Wells.

At least 19 recordsLinked to original sources

PubMed2006

The monitoring of opportunistic macroalgal blooms for the water framework directive.

Among the various quality elements which the Water Framework Directive requires should be monitored are macroalgae. One aspect of these is the presence, in transitional waters particularly, of large blooms of opportunistic macroalgae, such as Ulva and Enteromorpha. Within the United Kingdom (UK) and Republic of Ireland (RoI) there are currently no set ecological quality objectives or standards for macroalgae. Nor are there standard methods for monitoring macroalgal blooms, although various combinations of aerial photography, remote sensing and measurements on the ground are used. This paper attempts to set a logical framework for the prioritisation of sites for monitoring, the development of a tiered monitoring procedure and the derivation of thresholds for classification. Draft threshold limits for percentage cover and biomass of macroalgae have been derived from the literature. The importance of secondary effects and physico-chemical parameters is discussed.

Biomass↗

PubMed2005

Radiation exposure and the urologist: what are the risks?

PURPOSE: Endourology is established in urology practice with routine use of fluoroscopic guidance. Medical personnel are rarely exposed to direct radiation exposure but secondary exposure occurs via radiation scatter. There are few reports on scatter radiation exposure and the subsequent risk to medical personnel involved in urological fluoroscopic procedures. We review the risks of scatter radiation exposure to medical personnel with reference to the routine use of fluoroscopic imaging in urological practice. MATERIALS AND METHODS: We measured staff radiation exposure during a series of ureteral endourological procedures using LiF:Mg,Ti thermoluminescent dosimeters placed at the extremities of the operating surgeon, the assistant and the scrub nurse. Doses for percutaneous nephrolithotomy (PCNL) procedures were calculated by extrapolating from the ureteral procedure thermoluminescent dosimeter data. Theoretical scattered radiation dose rates were also calculated. RESULTS: The average ureteral procedure fluoroscopy time was 78 seconds with an exposure rate of 71 kV, 2.4 mA. The surgeon received the highest radiation exposure with the lower leg (11.6 +/- 2.7 microGy) and foot (6.4 +/- 1.8 microGy) receiving more radiation than the eyes (1.9 +/- 0.5 microGy) and hands (2.7 +/- 0.7 microGy). For a predicted annual caseload of 50 ureteral cases, the dose received does not exceed 0.12% of the Ionising Radiations Regulations 1999 annual dose limit for adult workers. Radiation exposure during PCNLs is higher but does not exceed 2% of the annual dose limits even if 50 PCNLs are performed annually. CONCLUSIONS: Fluoroscopic screening results in radiation exposure of medical personnel. The estimate of maximum scatter radiation exposure to the surgeon for 50 PCNL procedures a year did not exceed 10 mGy. This amount is less than 2% of permissible annual limits of equivalent dose to the extremities. Medical personnel should be aware of scatter radiation risks and minimize radiation exposure when involved in fluoroscopic screening procedures.

Fluoroscopy↗

PubMed2005

The use of digital 'virtual slides' in the quality assessment of haematological morphology: results of a pilot exercise involving UK NEQAS(H) participants.

We report the results of a pilot study assessing the use of digital 'virtual slides' in haematological quality assessment. Conducted together with the UK National External Quality Assessment Scheme for General Haematology, the study involved 166 separate participants, using the format of a typical assessment exercise. The results revealed substantial concordance of observations made using digital slides with those reported in previous glass slide surveys that used identical cases. Participant feedback strongly supported the use of electronic slides in teaching and assessment roles. Our results suggest roles for this new electronic resource in external quality assessment (EQA), education and continuing professional development.

Attitude of Health Personnel↗

PubMed2004

Ionization of atoms by the spatial gradient of the pondermotive potential in a focused laser beam.

Ionization of atoms by the spatial gradient of the pondermotive potential in a focused laser beam is investigated. Rydberg ions, formed during the interaction of noble gas atoms with an intense laser pulse, are used to probe the gradient field. Rydberg ion species with higher ionization potentials are produced at locations where the gradient field is largest. The measured Rydberg ion yields differ dramatically from estimates that ignore gradient-field ionization, but are in good agreement with predictions that include the effect.

Journal Article↗

PubMed2001

Ratiometric comparison of intense field ionization of atoms and diatomic molecules.

Intense-laser ionization rates for rare gas atoms and diatomic molecules have been precisely compared by making simultaneous measurements of ionization yield vs laser intensity for mixed atomic and molecular targets. At a given laser intensity, the N (2) and F (2) ionization yields are slightly greater than that of Ar. Conversely, comparison of O (2) and S (2) with Xe indicates significant ionization suppression in these molecules. Recent molecular ionization models that successfully describe ionization suppression in O (2) and its absence in N (2) fail to explain our observations in F (2) and S (2).

Journal Article↗

PubMed2001

Kinematically complete charge exchange experiment in the Cs(+)+Rb collision system using a MOT target.

Charge exchange is examined with unprecedented precision using the newly developed magneto-optical trap-target recoil ion momentum spectroscopy (MOTRIMS) technique. Initial and final state selective, charge exchange cross sections are obtained for 6 keV Cs+ colliding with rubidium in 5s and 5p states. For each charge transfer channel, cross sections differential in scattering angle are measured. These data are used to overturn previous long-standing conjecture as to the origin of oscillations seen in total charge exchange cross section measurements, and compare well with an enhanced Demkov model calculation.

Journal Article↗

PubMed2001

Charge transfer and elastic scattering in very slow H(+)+D(1s) half collisions.

Charge transfer and elastic scattering probabilities were measured for half collisions between very slow protons and atomic deuterium. Collision energies down to a few meV, lower by more than an order of magnitude and with better energy resolution than previous measurements, were studied using the dissociation of the HD+ electronic ground state. The collision energy is determined a posteriori from the measured momentum vector of the dissociating charged fragments. The experimental results are in good agreement with our coupled channel calculations.

Journal Article↗

PubMed2001

Nonrandom distribution of interspersed repeat elements in the BCR and ABL1 genes and its relation to breakpoint cluster regions.

The Philadelphia translocation, t(9;22)(q34;q11), is the microscopically visible product of recombination between two genes, ABL1 on chromosome 9 and BCR on chromosome 22, and gives rise to a functional hybrid BCR-ABL1 gene with demonstrated leukemogenic properties. Breakpoints in BCR occur mostly within one of two regions: a 5 kb major breakpoint cluster region (M-Bcr) and a larger 35 kb minor breakpoint cluster region (m-Bcr) towards the 3' end of the first BCR intron. By contrast, breakpoints in ABL1 are reported to occur more widely across a >200 kb region which spans the large first and second introns. The mechanisms that determine preferential breakage sites in BCR, and which cause recombination between BCR and ABL1, are presently unknown. In some cases, Alu repeats have been identified at or near sequenced breakpoint sites in both genes, providing indications, albeit controversial, that they may be relevant. For the present study, we carried out a detailed analysis of genomic BCR and ABL1 sequences to identify, classify, and locate interspersed repeat sequences and to relate their distribution to precisely mapped BCR-ABL1 recombination sites. Our findings confirm that Alu are the most abundant class of repeat in both genes, but that they occupy fewer sites than previously estimated and that they are distributed nonrandomly. r-Scan statistics were applied to provide a measure of repeat distribution and to evaluate extremes in repeat spacing. A significant lack of Alu elements was observed across the major and minor breakpoint cluster regions of BCR and across a 25-kb region showing a high frequency of breakage in ABL1. These findings counter the suggestion that occurrence of Alu at BCR-ABL1 recombination sites is likely by chance because of the high density of Alu in these two genes. Instead, as yet unidentified DNA conformation or nucleotide characteristics peculiar to the preferentially recombining regions, including those Alu elements present within them, more likely influence their fragility.

Alu Elements↗

PubMed2001

Differences by gender and sexual experience in adolescent sexual behavior: implications for education and HIV prevention.

Researchers examined individual characteristics and peer influences related to adolescents' sexual behavior, taking gender and sexual experience into account. As part of a larger, longitudinal study investigating youth health awareness, 8th, 9th, and 10th graders reported their intentions to engage in sexual activity and use condoms in the next year, the amount of pressure they felt to engage in sexual activity, and their perceptions about the number of their peers engaging in sexual activity. Findings suggest intentions to engage in sexual behavior and use condoms, feelings of pressure to have sex, and perceptions about the number of friends engaging in sexual intercourse differ by gender and sexual experience status. Implications of these findings for health and sexuality education, as well as HIV prevention programs targeted at adolescents, are discussed.

Adolescent↗

PubMed2000

Symmetry breakdown in ground state dissociation of HD+

Experimental studies of the dissociation of the electronic ground state of HD+ following ionization of HD by fast proton impact indicate that the H++D(1s) dissociation channel is more likely than the H(1s)+D+ dissociation channel by about 7%. This isotopic symmetry breakdown is due to the finite nuclear mass correction to the Born-Oppenheimer approximation which makes the 1ssigma state 3.7 meV lower than the 2psigma state at the dissociation limit. The measured fractions of the two dissociation channels are in agreement with coupled-channels calculations of 1ssigma to 2psigma transitions.

Journal Article↗

PubMed2000

Smoking, oral contraceptives, and cardiovascular reactivity to stress.

OBJECTIVE: To investigate the effects of smoking and oral contraceptive (OC) formulation on hemodynamic responses to stress in women. METHODS: Twenty-three smokers and 23 nonsmokers taking different OC formulations (ie, containing higher or lower androgenic progesterones) were tested for cardiovascular reactivity during mathematic, speech preparation, speech, and cold pressor stress. RESULTS: During mental stress, smokers, regardless of OC formulation, had lower systolic blood pressure (BP) (eg, 10.2 versus 15.1 mmHg, P < .05), heart rate (eg, 7.5 versus 15.0 beats per minute, P < .01), and cardiac index reactivity (eg, 0.08 versus 0.48 L/minute/M2, P < .01) but greater vascular resistance index responses (eg, 115.6 versus -51.9 dyne-sec x cm(-5) x M2, P < .05). Women who took higher androgen OCs, regardless of smoking status, showed greater vascular resistance index increases during speech stress than those who took lower androgen OCs (215.8 versus 9.4 dyne-sec x cm(-5) x M2, P < .05). Smokers who took more androgenic OCs had greater systolic BP responses to speech preparation compared with nonsmokers who took the same OCs (12.1 versus 6.1 mmHg, P < .05), and smokers who took lower androgen OCs (12.1 versus 4.4 mmHg, P < .05). Least-squares means examination found that smokers who took higher androgen OCs had greater vascular resistance index increases to all mental stressors than nonsmokers who took lower androgen OCs. CONCLUSION: Higher androgen OCs might be linked to greater vascular and BP increases during stress, especially in smokers. Given that increased vascular resistance and BP contribute to cardiovascular mortality, those results suggest that androgenic profiles of synthetic progesterones might be an important consideration in OC choice.

Adult↗

PubMed1999

Urinary incontinence in pregnancy and the puerperium: a prospective study.

OBJECTIVE: Pregnancy and childbirth are commonly thought to be associated with the development of urinary incontinence and lower urinary tract symptoms. The purpose of this study was to assess the relationship, if any, between pregnancy and the development of lower urinary tract symptoms. STUDY DESIGN: A prospective study of lower urinary tract symptoms was carried out in a cohort of pregnant women who answered a series of symptom questionnaires and kept a 24-hour bladder chart on which frequency of urination and volumes voided were recorded throughout pregnancy and for 8 weeks after birth. RESULTS: A total of 123 women participated in the study. Mean daily urine output (P =.01) and the mean number of voids per day (P =.01) increased with gestational age and declined after delivery. Episodes of urinary incontinence peaked in the third trimester and improved after birth (P =.001). White women had higher mean voided volumes and fewer voiding episodes than did black women. Ingestion of caffeine was associated with smaller voided volumes and greater frequency of urination. CONCLUSION: Pregnancy is associated with an increase in urinary incontinence. This phenomenon decreases in the puerperium. Pregnancy and childbirth trauma are important factors in the development of urinary incontinence among women. These findings warrant further investigation.

Female↗

PubMed1998

Responses of thenar muscles to transcranial magnetic stimulation of the motor cortex in patients with incomplete spinal cord injury.

OBJECTIVE: To investigate changes in electromyographic (EMG) responses to transcranial magnetic stimulation (TMS) of the motor cortex after incomplete spinal cord injury in humans. METHODS: A group of 10 patients with incomplete spinal cord injury (motor level C3-C8) was compared with a group of 10 healthy control subjects. Surface EMG recordings were made from the thenar muscles. TMS was applied with a 9 cm circular stimulating coil centred over the vertex. The EMG responses to up to 50 magnetic stimuli were rectified and averaged. RESULTS: Thresholds for compound motor evoked potentials (cMEPs) and suppression of voluntary contraction (SVC) elicited by TMS were higher (p < 0.05) in the patient group. Latency of cMEPs was longer (p < 0.05) in the patient group in both relaxed (controls 21.3 (SEM 0.5) ms; patients 27.7 (SEM 1.3) ms) and voluntarily contracted (controls 19.8 (SEM 0.5) ms; patients 27.6 (SEM 1.3) ms) muscles. The latency of SVC was longer (p < 0.05) in the patients (51.8 (SEM 1.8) ms) than in the controls (33.4 (SEM 1.9) ms). The latency difference (SVC-cMEP) was longer in the patients (25.3 (SEM 2.4) ms) than in the controls (13.4 (SEM 1.6) ms). CONCLUSION: The longer latency difference between cMEPs and SVC in the patients may reflect a weak or absent early component of cortical inhibition. Such a change may contribute to the restoration of useful motor function after incomplete spinal cord injury.

Adult↗

PubMed1996

Cerebellar vermis measurement at cranial sonography for assessing gestational age in the newborn weighing less than 2000 grams.

Prognosis of the very low birth weight infant depends more on gestational age than birth weight, but clinical assessment of gestational age of very low birth weight infants is inaccurate. We wished to determine how well cerebellar vermis dimensions might predict gestational age in infants of birth weight less than 2000 g. We obtained suitable midline sagittal images of the cerebellar vermis at cranial sonography, performed via the anterior or posterior fontanelle, in 41 infants, from the regional neonatal intensive care unit whose gestational age was known. We measured the cerebellar vermis area and diameter on the hard-copy image provided the margins of the vermis were clearly visible, the cerebellar tonsils were excluded from the image, and the anterior and posterior divisions of the corpus medullare were visible on the image. Vermis diameter was measured from the base of the fourth ventricle to the junction of folium and tuber vermis. Vermis area was calculated using a stereological method using a test system of regularly spaced points randomly placed over a magnified image of the cerebellar vermis. We generated regression equations for estimating gestational age using combinations of birth weight, vermis area, or vermis diameter for the 26 infants with birth weight of less than 2000 g for whom the cerebellar vermis measurements were obtained within one week of birth. Vermis area and diameter correlated very highly. They both can be used for predicting gestational age. The addition of either vermis area or diameter to birth weight improves accuracy of gestational age assessment. If birth weight was presumed to be unknown, cerebellar vermis area or diameter allow prediction of gestational age to within +/- 1.3 weeks (1 standard error) or +/- 2.5 weeks, using a 95% prediction interval. If the same method of reporting is applied to the New Ballard Score, the New Ballard Score predicts gestational age +/- 1.7 weeks (1 standard error) or +/- 3.4 weeks, using a 95% prediction interval.

Birth Weight↗

PubMed1996

Assessment of pelvic floor function: a series of simple tests in nulliparous women.

The aim of the study was to assess normal ranges, variations, test-retest reliability and correlations between tests for a battery of simple, minimally invasive tests of pelvic floor function in nulliparous asymptomatic women. Women were recruited by advertisement and underwent dipstick urinalysis, simple cystometrics, provocative tests for incontinence, Q-tip test and surface electromyography with acrylic plug electrodes. Subjects were retested at a later date. Nineteen subjects underwent initial testing and 12 were retested. A wide range of normal values was obtained. Cystometric measures of first and strong urge to void the maximum bladder capacity, Q-tip test and rectal perineometry had significant correlations between the two visits. There were no significant between-test correlation coefficients. It was concluded that the simple tests used demonstrate a mixed ability to follow pelvic floor function longitudinally.

Adolescent↗

PubMed1996

The development and evaluation of a computer-aided diabetes education program.

This paper describes the development and evaluation of a computer-aided learning (CAL) program. The program was tested in a trial that involved 36 people with diabetes; 20 received CAL lessons in diabetes management and 16 attended conventional diabetes classes conducted by diabetes educators. When measurements taken before and three months after the education were compared, both groups showed significant improvement in their knowledge; the blood glucose levels of the CAL group were significantly lower but those of the conventional education group were higher. This means that the CAL program was as effective as conventional education in imparting knowledge but it was more likely to motivate people to control their glucose levels. The CAL program allows diabetes educators to spend less time on education in basic knowledge and to concentrate more on motivational and social factors that are important determinants of patient compliance. It can also benefit people with diabetes whose access to health professionals and/or conventional diabetes education is restricted.

Adult↗

PubMed1994

Directional coronary atherectomy can be successfully performed in the elderly.

The influence of age on the clinical and angiographic outcome of directional coronary atherectomy is evaluated. Results demonstrate that DCA can be performed successfully in the vast majority (78.7-90%) of patients in all age groups. However, there is a non-statistical trend toward decreased success rates in the elderly (P > .05). Major ischemic complications and groin complications tend to be more common in the elderly (P > .05). Blood transfusions are required significantly more often in the elderly (P < .05). Directional coronary atherectomy is a useful method of coronary artery revascularization in all age groups, including the elderly.

Aged↗

PubMed1994

Directional coronary atherectomy in women compared with men.

The influence of gender on the procedural outcome of directional coronary atherectomy (DCA) is controversial. This study of 373 consecutive patients (418 lesions) undergoing DCA demonstrates that the procedural success rate of DCA is significantly lower in women compared with men (72.7 vs. 82.9%, p = 0.011). Women have significantly smaller coronary arteries than men (2.5 mm vs. 2.7 mm, p = 0.028) and were older than men (66 vs. 61 years, p = 0.0001). Multivariate analysis identifies small coronary vessel size rather than female gender per se as an independent predictor of poor procedural outcome. Procedural success rates in women with coronary vessel size > or = 2.5 mm is significantly higher (92.2%) than in women with coronary vessel size < 2.5 mm (73.1%), and parallels that in men with vessel size > or = 2.5 mm (89.3%). Inability to engage the ostium of the coronary artery adequately with the guiding catheter and to cross the lesion with the atherectomy device is significantly more common in women compared with men. Major ischemic complication rates are similar in women and men (8.5 vs. 8.7%). Groin complications are significantly more common in women compared with men (13.5 vs. 2.9%). We conclude that procedural success rates in women may be improved by careful patient selection, with particular attention to small vessel size. DCA is best performed in vessels > 2.5 mm in diameter.

Aged↗