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C Lewis

Publications and source records attributed to C Lewis.

At least 109 records · Page 6Linked to original sources
PubMed1998

Establishing minimum performance standards, calibration intervals, and optimal exposure values for a whole breast digital mammography unit.

Methods are developed to establish minimum performance standards, calibration intervals, and criteria for exposure control for a whole breast digital mammography system. A prototype phantom was designed, and an automatic method programmed, to analyze CNR, resolution, and dynamic range between CCD components in the image receptor and over time. The phantom was imaged over a 5 month period and the results are analyzed to predict future performance. White field recalibration was analyzed by subtracting white fields obtained at different intervals. Exposure effects were compared by imaging the prototype phantom at different kVp, filtration (Mo vs Rh) and mAs. Calcification detection tests showed that phantom images, obtained at 28 kVp with a Mo/Mo anode/filter and low mAs technique, often could not depict Al2O3 specks 0.24 mm in diameter, while a 28 kVp Mo/Rh, higher mAs technique usually could. Stability of the system tested suggests that monthly phantom imaging may suffice. Differences in CCD performance are greater (12%) than differences in a single CCD over time (6%). White field recalibration is needed weekly because of pixel variations in sensitivity which occur if longer intervals between recalibration occur. When mean glandular dose is matched, Rh filtration gives better phantom performance at 28 kVp than Mo filtration at 26 kVp and is recommended for clinical exposures. An aluminum step wedge shows markedly increased dynamic range when exit exposure is increased by using a higher energy spectrum beam. Phantoms for digital mammography units should cover the entire image receptor, should test intersections between components of the receptor, and should be automatically analyzed.

Female↗
PubMed1998

A collaborative audit of the management of hypertension in general practice.

We carried out an audit of the management of essential hypertension in general practice, against standards based on current guidelines. We examined the records of 882 hypertensive subjects (on medication) in whom hypertension had been diagnosed between January 1989 and December 1993, from 14 general practices in the Portsmouth and South East Hampshire Health Authority. The overall prevalence of hypertension was 3.5%. Pretreatment blood pressure had been measured on three or more occasions in 87% of patients. Pretreatment blood pressure was equal to or greater than 150/95 mmHg in 96% and 160/100 mmHg in 86.5% of patients. A thiazide diuretic was the initial drug of choice in 30% of patients, with beta-blockers being the most popular initial treatment. Ninety per cent of patients had had their blood pressure measured at least once during the preceding year. In 82.5% of patients, current blood pressure was less than 150/95 mmHg, while 44% achieved a current blood pressure less than 140/90 mmHg. We conclude that the prevalence of hypertension in this population was lower than expected, suggesting the need for improved screening. We also propose that the initial treatment choice should be a thiazide in the majority, which would result in significant cost saving. The blood pressure control was suboptimal compared to current guidelines.

Adrenergic beta-Antagonists↗
PubMed1998

Discrete domains within the hyaluronan receptor CD44 regulate membrane localization and cell migration.

CD44 is the principle transmembrane receptor for the extracellular matrix glycosaminoglycan, hyaluronan. This receptor: ligand interaction is required for many normal cellular processes including lymphocyte homing into inflammatory sites, assembly of a pericellular matrix during chondrogenesis, wound healing and tissue morphogenesis during development. In order to mediate these diverse events, CD44 expressing cells must be able to regulate, and respond to, interactions with hyaluronan. The mechanisms responsible have been subject to scrutiny over the past few years as it has become clear that their disruption can underlie the progression of both metastatic tumours and chronic inflammatory diseases. Here we describe recent data identifying discrete regions within the transmembrane and cytoplasmic domains of CD44 which regulate this important adhesion receptor.

Animals↗
PubMed1998

Preschool sibling interaction in separated and married families: are same-sex pairs or older sisters more sociable?

Two factors have been associated with the quality of sibling relationships: the sex of the children and their family circumstances. Yet the data on each issue are complex. This study examines the sex constellations of sibling pairs in two groups, one of which had experienced a major family disruption (parental separation), with the aim of assessing both influences more fully. Two 1-hour home observations were conducted on 20 preschool sibling dyads of separated parents and 24 pairs in which the parents were married. In both groups the sex configuration of the sibling pairs was important--same-sex pairs seemed to show closer patterns of interaction, and sister-sister dyads were particularly prosocial. These results suggests that previous research showing that older sisters or same-sex pairs interact more are both partly correct. In addition, preschoolers from separated families interacted more. The results suggest that negative life experiences might promote greater closeness between siblings.

Adult↗
PubMed1998

Does day case surgery generate extra workload for primary and community health service staff?

We have audited the effects of day surgery on the workload of primary and community care teams in Portsmouth. A modified version of the Audit Commission's 'Patients' Experiences of Surgery' questionnaire was given to all patients admitted for an elective surgical procedure from 16 general practices to the two local hospitals between February and November 1996; 487 completed replies were received. In all, 50% patients consulted primary or community health care staff within 21 days of discharge from hospital. The average total patient contact rate with these staff increased with length of hospital stay from 0.39 contacts/patient for day case to 1.83 contacts/patient for longer stay admissions. Contacts with most members of the primary and community health teams increased with length of hospital stay. The postoperative visit rate by general practitioners and district nurses to day case patients was very low. We conclude that day case surgery at its present level in Portsmouth appears to create less workload for primary and community health services than inpatient surgery.

Aftercare↗
PubMed1997

Gender differences in physician-patient communication. Evidence from pediatric visits.

OBJECTIVE: To determine whether physician gender and patient gender influence the process of communication and parent and child satisfaction during pediatric office visits. DESIGN: Content analysis of videotaped pediatric office visits. SETTING: University-based pediatric primary care practice. SUBJECTS: Videotaped communication between 212 children, ages 4 to 14 years, parents, and physicians. Thirty-eight percent were child health supervision visits, and 62% were for the management of minor or chronic illnesses. MAIN OUTCOME MEASURES: An established coding system of physician-patient communication and measures of parent and child satisfaction with medical care. RESULTS: Female physician visits were 29% longer than those of male physicians (P < .001). Compared with male physicians, female physicians engaged in more social exchange (P < .01), more encouragement and reassurance (P < .01), more communication during the physical examination (P < .05), and more information gathering (P < .01) with children. Male and female physicians engaged in similar amounts of discussions regarding illness management. Children were more satisfied with physicians of the same gender (P < .05), while parents were more satisfied with female physicians (P < .05). CONCLUSIONS: Children communicate more with female than with male physicians and show preferences for physicians of the same gender. These findings are consistent with communication patterns in adult patients and may have a significant influence on gender disparities in health care. Efforts at improving the process and outcome of medical care should address gender differences.

Adolescent↗
PubMed1997

The cystic fibrosis delta F508 gene mutation and cancer.

Following the observation that relatives of cystic fibrosis (CF) patients have an increased mortality due to leukaemia, a study was initiated to determine whether leukaemia patients had an increased prevalence of the delta F508 CF mutation. No increase in carriers were found among leukaemias; however the carrier frequency of the delta F508 mutation appeared to be reduced in patients with malignant melanoma analysed as a control group compared to the normal population. This paper extends our previous study and investigates several other common human tumours, including those of the colon, breast, and lymphoma tissue. Fewer than expected carriers remained among the melanoma group from South Wales. There were fewer than expected carriers among patients with colon cancer compared to the normal population. The prevalence of the delta F508 mutation was normal in lymphomas and leukaemias.

Alleles↗
PubMed1997

The use of povidone iodine in exit site care for patients undergoing continuous peritoneal dialysis (CAPD).

Exit site infection is a major risk factor for the development of peritonitis in continuous ambulatory peritoneal dialysis. The frequency of infection can be reduced by scrupulous exit site care with or without topical antiseptics. A randomized trial was performed of 149 catheters in 130 patients to assess any additional benefits conferred by the use of povidine iodine dry powder spray at dressing changes over an existing strict protocol of exit care. Exit infections occurred in 14 (18%) of 77 patients using spray and in 15 (21%) of 72 patients not using spray. The risk of peritonitis was also similar in each group. The proportion of infections caused by Staphylococcus aureus was reduced in the spray group, but those caused by Pseudomonas aeruginosa were increased. Rash occurred in 6% of those using the spray. The use of the spray did not therefore seem justified.

Aged↗
PubMed1997

Application of NASA's advanced life support technologies in polar regions.

NASA's advanced life support technologies are being combined with Arctic science and engineering knowledge in the Advanced Life Systems for Extreme Environments (ALSEE) project. This project addresses treatment and reduction of waste, purification and recycling of water, and production of food in remote communities of Alaska. The project focus is a major issue in the state of Alaska and other areas of the Circumpolar North; the health and welfare of people, their lives and the subsistence lifestyle in remote communities, care for the environment, and economic opportunity through technology transfer. The challenge is to implement the technologies in a manner compatible with the social and economic structures of native communities, the state, and the commercial sector. NASA goals are technology selection, system design and methods development of regenerative life support systems for planetary and Lunar bases and other space exploration missions. The ALSEE project will provide similar advanced technologies to address the multiple problems facing the remote communities of Alaska and provide an extreme environment testbed for future space applications. These technologies have never been assembled for this purpose. They offer an integrated approach to solving pressing problems in remote communities.

Alaska↗
PubMed1997

Evaluation of a programming algorithm for the third tachycardia zone in a fourth-generation implantable cardioverter-defibrillator.

The clinical efficacy of electrical algorithms for termination of slow ventricular tachycardia (VT) and ventricular fibrillation (VF) in implantable cardioverter-defibrillators (ICDs) is well established. Such algorithms have not been equally well defined for fast VT reversion. We report the testing of a prospectively designed algorithm for ICDs to treat fast VT that is inherently less responsive to antitachycardia pacing than slow VT. Fourth-generation ICD devices were programmed to three prospectively defined tachycardia detection zones as follows: cycle lengths < or = 260 ms for VF, 270-330 ms for fast VT, and > 330 ms for slow VT. The initial selected therapy for the VF zone was a high-energy biphasic shock (> 15 J), while a 3- or 5-J biphasic shock was usually administered for fast VT, and antitachycardia pacing was initially attempted for slow VT. Initial therapy was followed by backup therapy with high-energy shocks. Twenty-eight patients, 24 of whom were males, all with organic heart disease, with a mean age of 65 +/- 9 years, received either a Medtronic 7219D (23 patients), 7219C (2 patients), 7218SP1 (2 patients), or 7218C (1 patient) ICD with a nonthoracotomy lead system. The defibrillation threshold was 10 +/- 5 J. At predischarge electrophysiologic testing, a single 3- or 5-J shock terminated all episodes of fast VT tested. During a follow-up of 18 +/- 9 months, there were four nonarrhythmic deaths. Fourteen patients (50%) had a total of 21 VF, 44 fast VT, and 202 slow VT episodes. Twenty-three of 24 (96%) VF, 33 of 39 (84%) fast VT, and 193 of 202 (95.5%) slow VT episodes were terminated with the first delivered therapy in each therapy algorithm (p = NS). The overall efficacy of the entire electrical therapy algorithm was 100% for VF, 100% for fast VT, and 98% for slow VT episodes (p = NS). No patient experienced syncope or presyncope during fast VT or VF in this study. We conclude that a third detection and therapy zone can be successfully programmed in ICDs to define a range of fast VT episodes that can be effectively terminated with lower energy cardioversion shocks with comparable success and freedom from arrhythmic symptoms to electrical therapies used for slow VT and VF.

Aged↗
PubMed1997

The factors associated with effective folic acid prophylaxis in the peri-conceptional period in women attending an ante-natal clinic.

The aim of this study was to examine whether folic acid supplements had been taken and dietary folate intake increased in 662 pregnant women attending the antenatal clinic at St Mary's Hospital, Portsmouth. An assessment was also made of the factors that influenced correct compliance with the recommendations of the Expert Advisory Group on folic acid. Thirty-seven percent (245/662) women had taken folic acid supplements and 26.4% (175/ 662) increased their dietary folate before or during early pregnancy. The majority of women who commenced folic acid supplements after conception did so after the neural tube had closed (220/247). Women were more likely to have adhered to the Expert Advisory Group's recommendations if the pregnancy was planned, the woman was primiparous, there was no past or family history of neural tube defect and the patient had the correct existing knowledge of folic acid prophylaxis. The relevance of these findings to the current Health Education Authority's folic awareness campaign is discussed.

Journal Article↗
PubMed1997

Value of an orthopaedic pre-admission clinic for total knee and hip replacements in a rural health service.

The emphasis on orthopaedic pre-admission clinics within hospital settings is very recent in Australia. Tamworth Base Hospital, a large rural hospital, started a compulsory clinic in mid-1995. The purpose of this study was to determine the value of orthopaedic education in a pre-admission clinic for patients who were undergoing total knee and total hip replacements. Regarding total knee replacement patients, the average length of stay for those who attended the clinic after it had become compulsory, compared with before, was 3.8 days shorter. For total hip replacement patients, the reduction was 1.1 days. This study found that the major value of the clinic was not so much in reduced lengths of stay, rather it related more to increased patient satisfaction, and perhaps more so in the rural setting where patients are disadvantaged in many cases by the large distances they travel for services.

Adult↗
PubMed1997

Interaction between electronic article surveillance systems and implantable defibrillators: insights from a fourth generation ICD.

We present a case report of an inappropriate discharge from a fourth generation implantable cardioverter defibrillator (ICD) as a result of exposure to electromagnetic interference. A 60-year-old man implanted with a Medtronic 7219D defibrillator experienced shocks without preceding symptoms while walking through an electronic surveillance system in a store. Though this has been reported, the mechanism of the interaction remains unexplained. The electrogram storage capabilities of this particular device enabled us to establish that this resulted from inappropriate sensing of the electromagnetic interference.

Defibrillators, Implantable↗