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Biomedical subjects

M H Edwards

Publications and source records attributed to M H Edwards.

At least 37 records · Page 2Linked to original sources
PubMed1999

Anatomical and physiological models for surgical simulation.

A considerable amount of effort has been aimed towards developing real-time deformable objects for surgical simulation, but very little work has been aimed towards including physiology within the soft tissue models. A simulator that links the structural and functional aspects of the human body would allow the user to develop a better understanding of the intrinsic link between anatomy and physiology. This positional paper discusses the challenges facing the creation of and the development of an integrated physiological and anatomical soft tissue model for use in surgical simulators. It explores the artificial dichotomy between anatomy and physiology and the issues it raises, by considering a suturing simulator capable of modelling ischaemia.

Animals↗
PubMed1998

Effect of parental myopia on the development of myopia in Hong Kong Chinese.

A representative sample of Hong Kong Chinese children was followed from 7 to 12 years of age. Refractive error was measured every year (n = 123 at age 7 years and n = 83 at age 12 years), the axial length of the eye was measured at age 12 years (n = 81) and the refractive status of the parents was also determined. Thirty-one percent of the parents in the sample were myopic and at the age of 12 years 53% of the children were myopic. There was no association between the refractive status of the parents and whether or not a child had myopia. The probability of a 12-year-old child with early-onset myopia having at least one myopic parent was 0.55 and the probability of myopic parents having a myopic child was 0.6. There was no difference in the refractive error or the axial length of 12-year-old children according to whether neither, one or both parents were myopic. The genetic influence on myopia may be different in Caucasian and Chinese children, although it is also possible that non-expression of the genotype in the parents may have confounded the determination of the inheritance pattern of myopia in Hong Kong Chinese children.

Adolescent↗
PubMed1998

Investigation of multifocal visual evoked potential in anisometropic and esotropic amblyopes.

PURPOSE: To investigate the variation of visual evoked potential (VEP) function at different eccentricities of the visual field in esotropic amblyopes and anisometropic amblyopes. METHODS: Data from 5 esotropic amblyopic eyes, 6 anisometropic amblyopic eyes, and 45 control eyes were analyzed. A VERIS system was used to generate a stimulus matrix containing 61 hexagons on a computer monitor. Each hexagon of the display contained a number of small black and white hexagonal patches that reversed in polarity during stimulation according to a pseudorandom binary m-sequence. The VERIS system extracted the local responses by cross-correlating the input and output signals. The latencies and amplitudes of the responses from the central 8.6 degrees of arc in the visual field were analyzed. RESULTS: In esotropic amblyopia, the multifocal VEP latency is prolonged, and the amplitude is reduced in the central region of the visual field. The mean amplitude is significantly smaller, and the mean latency is significantly longer in the temporal visual field than in the nasal visual field. In anisometropic amblyopia, latencies are markedly prolonged, and the amplitudes of multifocal VEP are attenuated in the central region of the visual field, and these effects are lessened in the periphery. CONCLUSIONS: The results are in agreement with psychophysical studies reporting a greater foveal deficit in amblyopia and a greater visual loss in the temporal field than in the nasal field in esotropic amblyopia.

Adolescent↗
PubMed1997

Hydroxychloroquine reverses thrombogenic properties of antiphospholipid antibodies in mice.

BACKGROUND: Previous studies have demonstrated that human monoclonal and polyclonal anticardiolipin antibodies have thrombogenic properties in vivo. Using such a model in which these antibodies have been shown to increase both the size of an induced thrombus and the duration of time in which such a clot lasts, we investigated whether hydroxychloroquine alters the dynamics of such thrombus formation. METHODS AND RESULTS: Three groups of nine mice were injected with purified immunoglobulin G (IgG) from a patient with the antiphospholipid syndrome (IgG-APS) and then fed with hydroxychloroquine at various doses (100, 6, and 3 mg/kg body wt). Three control groups of mice were also studied, including mice injected with IgG-APS and then fed with placebo, as well as two other groups injected with IgG from normal human serum and fed either hydroxychloroquine or placebo. A standardized thrombogenic injury was subsequently induced in the femoral vein of each mouse and the area (size) of thrombus measured as well as the total period of time that thrombus was present. Mice treated with hydroxychloroquine and IgG-APS showed significantly smaller thrombi that persisted for a shorter period of time compared with animals treated with IgG-APS and placebo. CONCLUSIONS: Hydroxychloroquine significantly diminished both thrombus size and total time of thrombus formation in mice previously injected with IgG-APS.

Animals↗
PubMed1996

SopE, a secreted protein of Salmonella dublin, is translocated into the target eukaryotic cell via a sip-dependent mechanism and promotes bacterial entry.

The entry of Salmonella into cultured epithelial cells is dependent on genes located in several adjacent chromosomal loci. One of these loci encodes the recently identified secretory proteins, denoted Sips (Salmonella invasion proteins). SipB, C,D proteins are essential for the ability of the pathogen to invade epithelial cells. To examine if additional invasion-associated proteins were secreted by Salmonella dublin, the genes encoding already characterized secretory proteins were inactivated to facilitate this analysis. The proteins produced and secreted by a double fIIM/polar sipB mutant of S. dublin were analysed; this revealed a set of novel secreted proteins. These proteins, which we denoted Sops (Salmonella outer proteins), formed large filamentous aggregates in the medium of bacterial culture growing at 37 degrees C. These aggregates contained five predominant proteins. Here we report the identification and characterization of one of these proteins, SopE, which is a novel invasion-associated secretory protein of S. dublin. A specific sopE mutant of S. dublin was found to be defective for invasion into epithelial cells. Upon interaction of Salmonella with HeLa cells, SopE was found to be translocated into the cytoplasm of the target cell by extracellular bacteria. The translocation of SopE was shown to be dependent on the Sip proteins because a polar sipB mutant did not translocate SopE across the HeLa cell membrane.

Amino Acid Sequence↗
PubMed1996

Do variations in normal nutrition play a role in the development of myopia?

BACKGROUND: A number of papers have reported an association between diet and myopia; however, these studies have generally considered the diet of children already myopic. This study compared the nutritional intake and some simple body measurements for a group of children who subsequently became myopic with that of a group who did not become myopic. METHODS: The nutritional data for 24 subjects who developed myopia between the ages of 7 and 10 years were compared with data for 68 subjects who were still not myopic at the age of 10 years. RESULTS: Children who developed myopia had a generally lower intake of many of the food components than children who did not become myopic. The differences were statistically significant for energy intake, protein, fat, vitamins B1, B2 and C, phosphorus, iron, and cholesterol. Despite these differences, children who became myopic were neither shorter nor lighter, at the age of 7 years, than children who did not become myopic. CONCLUSIONS: There is no evidence that the incident myopes were in any way undernourished and it therefore seems that their energy requirements were less than those of the control subjects.

Anthropometry↗
PubMed1996

Animal models of myopia. A review.

The discovery that myopia can be induced in animals has resulted in renewed interest in the condition and it is hoped that information gained about the production, manipulation and prevention of myopia in animals might provide information about naturally occurring myopia in humans. Early experimental work was carried out using monkeys as subjects, but the high cost involved, and the difficulty of obtaining monkeys in adequate numbers for good experimental design and control, made researchers look for more suitable experimental animals. Myopia has also been induced in other animals species such as the domestic cat, the tree shrew, the marmoset, the guinea pig and, most successfully, the domestic chicken. The parallels between experimentally induced myopia, which can only be induced in infant animals, and human myopia which typically develops well after infancy, have still to be established.

Animals↗
PubMed1996

IOP in myopic children: the relationship between increases in IOP and the development of myopia.

Intraocular pressure (IOP) was measured at yearly intervals, from age 7 to 9 years, in 106 Chinese children. The sample had been selected from newborn children for participation in a growth and nutrition study, and all children remaining in this study took part in the myopia study. As part of an ongoing prospective study to examine factors which may be associated with the development of myopia, IOP was compared according to whether the subjects had become myopic or remained non-myopic during the time-frame of the study. During the course of the study 13 children became myopic. There was no difference in the IOP of the incident compared with control groups at age 7 years. The IOP of the incident group was higher following onset of myopia than it was prior to onset whereas there was no difference in the IOP of the control groups over the same period. A high IOP therefore follows the onset of myopia and cannot cause myopia. It is still unknown whether or how myopia causes a high IOP.

Analysis of Variance↗
PubMed1995

Is there a difference in dental caries between myopic and nonmyopic children?

A number of authors have reported that myopia is associated with high amounts of dental caries. Collagen is a major constituent of dentine and it is possible that the association between myopia and dental caries is a sign of a common collagen defect. Dental caries was quantified in an unselected sample of 9-year-old Hong Kong Chinese children, of whom 22 were subsequently classified as myopic and 80 as nonmyopic. Dental and refractive examinations were carried out independently of each other. No association was found between the presence of dental caries and the refractive state of the eye.

Child↗
PubMed1993

Intraocular pressure in a selected sample of myopic and nonmyopic Chinese children.

The intraocular pressure (IOP) measurements for 30 myopic and 30 nonmyopic children between 6 and 9 years of age were extracted from eye examination records. The mean IOP of 30 myopic children was 13.69 mm Hg (SD 3.4) and that of 30 nonmyopic children was 11.55 mm Hg (SD 2.06). The difference between the two is significant. These results suggest that IOP may play a role in the determination of refractive error.

Child↗
PubMed1993

Clinical norms for amplitude of accommodation in Chinese.

Amplitude of accommodation was measured in 121 Hong Kong Chinese subjects between the ages of 11 and 65 years, using the 'push-up' method and the results compared with those previously obtained for Caucasian subjects. The results confirm and quantify clinical experience that Chinese people have lower amplitudes of accommodation than Caucasians. If presbyopia is considered to commence when the amplitude of accommodation declines to less than 5 D, then presbyopia in the Chinese race occurs between the ages of 36 and 40 years. By early in the second decade of life the amplitude of accommodation in the Chinese is already lower than that of Caucasians. This suggests that reduced amplitude of accommodation may be due, at least in part, to factors other than longterm environmental effects.

Accommodation, Ocular↗
PubMed1990

Satisfying patients' needs for surgical information.

Patients facing operation need good information. This is implicit in informed consent but it is often lacking. A solution is a comprehensive set of leaflets covering 65 different general surgical operations. The leaflets describe the illness, operation, exact management regimen, some complications and outlook, in a deliberately simple style. Master copies are stored on a wordprocessor to allow unlimited expansion and updating. A retrospective survey of 200 patients showed that those receiving leaflets were significantly more satisfied with information (72 per cent overall) than those not receiving leaflets (42 per cent overall) (P less than 0.01). This was especially apparent for information about postoperative progress, both in hospital (92 per cent versus 52 per cent) and after discharge from hospital (88 per cent versus 39 per cent). The system is effective, cheap and popular with patients and medical and nursing staff. The wordprocessor allows extensive modifications of the information to suit other surgeons' requirements.

Comprehension↗
PubMed1986

Computer aided diagnosis of acute abdominal pain: a multicentre study.

A multicentre study of computer aided diagnosis for patients with acute abdominal pain was performed in eight centres with over 250 participating doctors and 16,737 patients. Performance in diagnosis and decision making was compared over two periods: a test period (when a small computer system was provided to aid diagnosis) and a baseline period (before the system was installed). The two periods were well matched for type of case and rate of accrual. The system proved reliable and was used in 75.1% of possible cases. User reaction was broadly favourable. During the test period improvements were noted in diagnosis, decision making, and patient outcome. Initial diagnostic accuracy rose from 45.6% to 65.3%. The negative laparotomy rate fell by almost half, as did the perforation rate among patients with appendicitis (from 23.7% to 11.5%). The bad management error rate fell from 0.9% to 0.2%, and the observed mortality fell by 22.0%. The savings made were estimated as amounting to 278 laparotomies and 8,516 bed nights during the trial period--equivalent throughout the National Health Service to annual savings in resources worth over 20m pounds and direct cost savings of over 5m pounds. Computer aided diagnosis is a useful system for improving diagnosis and encouraging better clinical practice.

Abdomen↗
PubMed1986

Education and training programs at the National Cancer Institute: 1938-1982.

The National Cancer Institute (NCI) has supported cancer research training and clinical cancer education since 1938, the latter in a variety of forms. These include direct clinical fellowships, followed by institutional grants designed to improve the education of students concerning cancer in medical and dental schools, and subsequently in teaching hospitals. The institutional grants went through three stages between 1948 and 1982, and have recently entered a fourth. Undergraduate Cancer Training Grants supported cancer teaching for medical and dental students. Clinical Cancer Training Grants expanded teaching activities to include post-resident trainees and medical and dental practitioners. Clinical Cancer Education Grants further extended cancer education and emphasized goals, objectives and evaluation, and focused on areas of weakness in cancer teaching such as epidemiology and cancer, cancer prevention and the role of radiation therapy. The various pressures within and without NCI that have influenced the development of these grant programs are discussed. Some cancer education activities supported by Cancer Control programs, both at NCI and another agency of the Public Health Service, are briefly mentioned. Aspects of the grant review process, program monitoring, and the impact of a professional organization developed in direct response to the first institutional cancer education grant program are described.

Cancer Care Facilities↗
PubMed1985

The association between lowest palpable pulse and wound healing in below knee amputations.

A retrospective study of 191 patients undergoing 203 Burgess type below knee amputations for end-stage peripheral vascular disease showed that the only clinical feature which associated significantly with wound healing was the lowest palpable pulse. The pulse level was noted preoperatively and was compared with the healing rates in the amputation stumps. When the femoral pulse was absent, 79% of below knee amputations failed. When the femoral pulse was palpable, only 29% wound breakdown occurred. When the popliteal or more distal pulses were palpable, only 10% failure was recorded.

Adult↗
PubMed1983

Early results of subcutaneous mastectomy with immediate silicone prosthetic implant for carcinoma of the breast.

Surgery for carcinoma of the breast is becoming less radical even to the extent of breast conservation. Subcutaneous mastectomy and implant offers itself as an alternative, retaining a breast shape and removing almost all breast tissue. Forty-four consecutive patients who had this procedure for breast carcinoma were studied with a follow-up of 5-44 months (mean 25.3 months). Only 4 patients (9 per cent) had local recurrences, i.e. recurrence in the skin flap or scar. This compares favourably with other series and other forms of treatment. Removal of the prosthesis was necessary in 10 patients due to local factors. The cosmetic result as assessed by the patients was almost universally pleasing. Twenty-six of 27 patients with prostheses in situ who were interviewed in person or by postal questionnaire were pleased with the results of their surgery. The absence of high recurrence rates locally and high patient acceptance makes this a definite surgical alternative.

Adult↗