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Biomedical subjects

R D Evans

Publications and source records attributed to R D Evans.

At least 55 records · Page 3Linked to original sources
PubMed2000

Three-dimensional analysis of the child cleft face.

OBJECTIVE: This study examined the facial surfaces of cleft children and unaffected children aged 8-11 years with the aim of identifying and assessing differences in their facial surface morphology. The investigation was carried out using an Optical Surface Scanner, an instrument that utilizes laser light to construct and archive a three-dimensional image of the face suitable for linear measurement and direct surface comparisons. DESIGN, SETTING, AND PATIENTS: Thirty-nine cleft lip and palate (CLP) patients and 25 unaffected subjects were voluntarily recruited from two southeast England hospitals. A range of linear facial measurements was compared. Three-dimensional differences between the cleft subgroups and the control group were visualized by superimposition of averaged cleft scans over the averaged control group images. RESULTS: Statistically significant dimensional differences (p < or = .05) in interocular width, nose base widths, mouth widths, and nose base/mouth width ratios were found between the cleft group and the control group. Qualitative differences over the whole of the face were readily demonstrated between the groups by superimposition. Face width and submandibular area depth differed consistently between the groups, the cleft face appearing narrower with a deeper submandibular area. CONCLUSION: Significant differences exist between the facial surface morphology of CLP patients and control subjects.

Analysis of Variance↗
PubMed2000

Proximal articular set angle. Radiographic versus intraoperative measurement.

The authors conducted a study to investigate the variability of measurement of the proximal articular set angle. The proximal articular set angle as measured radiographically was compared with the proximal articular set angle as measured intraoperatively. Three groups of evaluators--attending physicians, residents, and third-year podiatric medical students--measured the proximal articular set angle radiographically. The mean measurement, standard deviation, and difference between the mean radiographic measurement and the intraoperative measurement were determined for each group. The authors concluded that the only accurate proximal articular set angle measurement is the intraoperative measurement.

Adult↗
PubMed2000

Cimetidine and a delayed hypersensitivity reaction.

Oral cimetidine for the treatment of verruca continues to be a topic of discussion and controversy. Although its usage has gained popularity because it offers an alternative to conventional topical and surgical verruca therapy, its reported efficacy in managing warts lacks consistency in outcomes. Using high doses of oral cimetidine, therefore, raises concern about possible untoward effects. Cimetidine relies on effecting a change in the immune system to eradicate the verruca, but such a change in the immune system may cause patients to develop responses detrimental to their well being. The authors present an unusual case of severe delayed hypersensitivity with the use of oral cimetidine.

Adjuvants, Immunologic↗
PubMed2000

Preliminary report on a method of human papillomavirus DNA extraction from verruca plantaris for polymerase chain reaction studies.

This preliminary report on the Chelex-based extraction method of HPV DNA from verruca plantaris is the first step in a series of studies on verruca plantaris undertaken, jointly, by the Departments of Podiatric Medicine and Microbiology at Des Moines University-Osteopathic Medical Center, Des Moines, Iowa. Current projects include the development of new primers for PCR studies of HPV, exploration of different viral DNA extraction methods, and surveys concerning treatment, success of therapies, and the epidemiology of verruca plantaris.

DNA, Viral↗
PubMed1999

Effect of omitting regular ACE inhibitor medication before cardiac surgery on haemodynamic variables and vasoactive drug requirements.

Adverse events during coronary artery bypass graft (CABG) surgery have been described in patients receiving angiotensin converting enzyme (ACE) inhibitors, including hypotension on induction of anaesthesia and an increase in vasoconstrictor requirements after cardiopulmonary bypass (CPB). Omitting regular ACE inhibitor medication before surgery may improve cardiovascular stability during anaesthesia. We evaluated prospectively the effect of omitting regular ACE inhibitor medication before CABG surgery on haemodynamic variables and use of vasoactive drugs. We studied 40 patients with good left ventricular function, allocated randomly to omit or continue ACE inhibitor medication before surgery. Arterial pressure, cardiac output, systemic vascular resistance and use of vasoactive drugs were recorded during anaesthesia and in the early postoperative period. Patients who omitted their ACE inhibitors had greater mean arterial pressure during the study and required less vasopressors during CPB. However, these patients required more vasodilators to control hypertension after CPB and in the early postoperative period. There was no difference in hypotension on induction of anaesthesia or in the use of vasoconstrictors after CPB. We conclude that omitting ACE inhibitors before surgery did not have sufficient advantage to be recommended routinely.

Aged↗
PubMed1999

The physical characteristics of neodymium iron boron magnets for tooth extrusion.

Impaction and non-eruption of teeth is a common problem encountered in orthodontics and many techniques have been proposed for the management of this condition. It has been advocated that a system utilizing magnets would supply a continuous, directionally sensitive, extrusive force, through closed mucosa and thus provide not only a physiological sound basis for successful treatment, but also reduce the need for patient compliance and appliance adjustment. This ex vivo investigation examined in detail the physical characteristics of neodymium iron boron magnets employed in attraction in order to assess their usefulness in the clinical situation. Attractive force and magnetic flux density measurements were recorded for nine sets of magnet pairs with differing morphologies. The effect of spatial relationship on force was assessed by varying vertical, transverse and horizontal positions of the magnets relative to each other, and by altering the pole face angles. The data obtained suggest that magnets with larger pole face areas and longer magnetic axes provide the best performance with respect to clinical usefulness. It was possible to formulate a specific relationship between force and flux density for each magnet pair. This relationship can be used in the clinical management of unerupted teeth to predict the force between the magnets by measuring the magnetic flux density present at mucosal level. The results indicate that magnetic systems may, indeed, have a place in the treatment of unerupted teeth.

Biomechanical Phenomena↗
PubMed1999

The durability of parylene coatings on neodymium-iron-boron magnets.

A parylene coating is frequently used to prevent corrosion of neodymium-iron-boron magnets when they are used intra-orally. This in vitro study was designed to test the durability of parylene coating in a simulated oral environment. Single and double parylene-coated magnets were subjected to grinding and crushing forces in an industrial ball mill. The results demonstrate that abrasion and wear was visible around the edges after 1 hour of testing, with a breach of the coating noted under high magnification scanning electron microscopy (SEM). The conclusion of the study is that parylene coating is unlikely to withstand intra-oral forces. The shape of the magnets, the manufacturing process involved in their production, and the thickness of the parylene coating are important factors to consider with respect to the durability of magnets used in the mouth.

Boron↗
PubMed1999

Long-term effect of neonatal endotracheal intubation on palatal form and symmetry in 8-11-year-old children.

Premature and low birth weight infants often require neonatal oral intubation for resuscitation and to relieve respiratory distress. The endotracheal tube exerts pressure on the developing palate, which can result in palatal groove formation, a high-arched palate, and palatal asymmetry. The purpose of this investigation was to determine whether such intubation can have a long-term effect on palatal form and symmetry. Arch widths, palatal widths, and palatal depths were measured from the study casts of 43, 8-11-year-old previously intubated premature and low birth weight children using a reflex microscope, with a fixed rectangular Cartesian co-ordinate system, and compared with a group of non-intubated gender- and age-matched controls. Significant differences were found between the intubated and non-intubated children. The intubated children had significantly narrower palatal widths posteriorly (P < or = 0.001), steeper palatal vaults anteriorly (P < or = 0.01), and exhibited a directional palatal width asymmetry with the left side of the palate measuring consistently wider than the right. These differences did not, however, appear to be affected by the length of intubation. Therefore, it is concluded that an oral endotracheal tube might exert excess force on the developing alveolus anteriorly with the tube being displaced to the right of the palate posteriorly leading to a steep anterior palatal vault and a left-sided palatal asymmetry, which can persist until the age of 11 years of age.

Analysis of Variance↗
PubMed1999

Rare earth magnets in orthodontics: an overview.

Magnets have been used in dentistry for many years. They can be made to push or pull teeth. The force they deliver can be directed, and they can exert their force through mucosa and bone, as well as within the mouth. In orthodontics they are used for intrusion of teeth, tooth movement along archwires, expansion, retention, in functional appliances, and in the treatment of impacted teeth. New 'high energy' magnets are capable of producing very high forces relative to their size. Although magnets are potentially very useful there are a number of problems that severely affect their performance; the force produced between any two magnets falls dramatically with distance, significant irreversible loss in force is seen if the magnets are heated and a dramatic reduction in force is seen if the magnets are not ideally aligned to one another. In addition, magnets corrode badly in the mouth and a robust coating is required to protect them. This paper outlines the background to high energy magnets used in orthodontics, discusses the relevant physical and biological properties of them, and reviews their applications.

Biocompatible Materials↗
PubMed1999

Pilon fractures of the distal tibia.

Pilon fractures are one of the most complicated injuries confronting the lower extremity traumatologist. When faced with the pilon fracture, the surgeon must adhere to the principles of anatomic reduction and rigid stabilization to achieve early range of motion. Open reduction and internal or external fixation or a combination of fixation techniques, expertly placed, ensure the best possible outcome with the least complications. A functional lower extremity following a pilon fracture is possible with meticulous evaluation and repair.

External Fixators↗
PubMed1998

An examination of spatial variation in mercury concentrations in otter (Lutra canadensis) in south-central Ontario.

Hair samples were collected from otter (Lutra canadensis) trapped in several parts of south-central Ontario, Canada. The concentrations of total Hg in hair were compared with methyl mercury concentrations in liver tissues from the same individuals to determine if hair is a suitable monitoring tissue. Hg in the two tissues was significantly correlated. Hair was used to monitor Hg in 51 individuals from four townships. The concentrations of total Hg in hair ranged from 4 to 20 micrograms/g. No significant variation among the four sample regions existed. Generally the highest concentrations were found in the youngest members of the population. Some possible explanations for the observations are presented.

Animals↗
PubMed1998

LVAD power delivery: a percutaneous approach to avoid infection.

BACKGROUND: Driveline infection limits the event-free survival of patients with a left ventricular assist device. With the evolving prospect of improved left ventricular assist devices in the bridge-to-transplantation or recovery setting, we sought to reduce the risk of driveline complications. METHODS: As part of the Oxford Jarvik 2000 research program, we developed a carbon and then titanium pedestal to transmit the electric wires through the skin. In a sheep model, the pedestal was brought out through the skin of the shoulder (n = 10) or the scalp (n = 9) with underlying fixation to the skull. Exit wounds were carefully inspected for healing and infection. Power cable durability tests were performed in 6 additional animals without an implanted pump. RESULTS: The cumulative observation period was 1,491 days (mean time, 78 days; range, 14 days to 198 days). There was no difference in observation period between the two groups. Infection (n = 2) and impaired healing (n = 5) occurred in the mobile tissues at the shoulder. Skull-mounted pedestals were free from infection or healing problems. The electric cables were not interrupted by repeated neck flexion (cumulative observation period, 588 days). The carbon pedestal was replaced by a titanium pedestal when the head butting of the sheep fractured the carbon. CONCLUSIONS: The combination of rigid fixation and highly vascular scalp skin reduces the risk of percutaneous driveline infection and may solve an important outstanding problem in use of left ventricular assist devices.

Animals↗