Search PubMed⌕ Search

Biomedical subjects

M McGee

Publications and source records attributed to M McGee.

14 recordsLinked to original sources
PubMed1991

Chronic forced swim stress produces subsensitivity to nicotine.

Twice daily injections of saline reduce the thermic response to nicotine in the rat. The authors hypothesized that this was due to the stress of twice-daily handling and injection. However, the injection of saline is not a classic stressor. The hypothesis that stress blunts thermic responsiveness to nicotine was, therefore, tested using a classic form of chronic inescapable stress. Rats (n = 12) were subjected to a 14-day, twice daily course of inescapable cold water swim stress using a repeated measures design. Thermic responsiveness of nicotine was measured at baseline and every 7 days thereafter for 49 days. The mean response to nicotine (1.0 mg/kg IP) differed significantly across time, F(7,88) = 10.6, p less than 0.0001. Mean thermic responsiveness (+/- SEM) decreased from -0.75 +/- 0.09 at baseline to -0.41 +/- 0.18 degrees C (54.7% of baseline) following 14 days of forced swim stress. This change was not significant. However, the thermic response to nicotine was -0.14 +/- 0.13 degrees C (p less than 0.05), +0.55 +/- 0.12 degrees C (p less than 0.05), and +0.04 +/- 0.11 degrees C (p less than 0.05) 7, 14, and 21 days following the discontinuation of forced swim stress. The mean response did not differ from baseline 28 days following the last session of forced swim stress. The data suggest that in the recovery phase the animals ceased to be sensitive to nicotine. These findings support the hypothesis that a chronic stressor can produce subsensitivity to nicotine.

Animals↗
PubMed1991

Peripheral wear of Wagner resurfacing hip arthroplasty acetabular components.

One hundred nine Wagner resurfacing arthroplasty acetabular components retrieved at revision surgery were examined for type, depth, and extent of wear at the periphery of the components. Ninety-two components were found to have evidence of peripheral wear caused by impingement of the femoral neck on the edge of the component. The thickness of the wall loss due to this impingement wear was found to be less the farther that measurements were taken from the edge of the component. Thus, when those components with any evidence of impingement wear were analyzed, it was found that significantly fewer components had evidence of impingement at depths of 3 mm and 5 mm in from the edge of the component. It is suggested that future designs of resurfacing hip arthroplasty acetabular components should be at least 3 mm and possibly 5 mm less than a hemisphere. This is likely to lead to less impingement on the femoral neck and therefore less cause for mechanical loosening and less production of wear debris.

Acetabulum↗
PubMed1990

Neutrophil functional and arachidonic acid metabolic correlates and clinical disease activity in pirazolac-treated rheumatoid arthritis patients.

Neutrophils from 20 medication-free rheumatoid arthritis patients were chemotactically hyporesponsive to 2 x 10(-8) M formyl-methionyl-leucyl-phenylalanine (f-MLP) as compared to 20 normal controls. They were relatively high producers of 5-hydroxyeicosatetraenoic acid (5-HETE) and low producers of leukotriene C4 (LTC4). Neutrophils from 10 patients treated with pirazolac (4-(4-chlorophenyl)-1-(4-fluorophenyl)-5-pyrazole acetic acid) showed increased chemotactic responsiveness concomitantly with normalization of 5-HETE and LTC4 production and a decrease in the clinical parameters of disease activity. Clinically attainable (30-60 micrograms/ml) in-vitro doses of pirazolac further depressed the chemotactic responsiveness of normal neutrophils treated with 10(-5)M f-MLP. Effects on endothelial gating of migrating neutrophil populations may explain this apparent contradiction between in-vivo and in-vitro actions of pirazolac on neutrophil chemotaxis.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1990

Non-ossicle homograft bone prostheses in the middle ear.

This thesis proposes the use of human cadaver non-ossicle temporal homograft bone as middle ear reconstructive material. Bone obtained from the otic capsule histologically resembles that of the ossicles more so than any other bone in the body. The otic capsule, due to its proximity to the middle ear, can be harvested with the middle ear structures when bone cores are obtained, making it easily accessible. These prostheses are cost effective because multiple prostheses can be sculptured from one temporal bone core. This paper further proposes the use and introduction of non-ossicle homografts in primary stapedectomy, as well as in selected cases to bypass the incus and the superstructure of the stapes. Audiological data is provided. Some of the grafts have been in the middle ear for up to 5 years. There have been no extrusions and no complications. The method of harvesting, preservation, and sterilization is presented, as well as a pictorial illustration of the finished product and its relation to the natural ossicles. One histological specimen is presented. On the basis of the audiologic results, as well as the fact that no ossicles have extruded and none have been resorbed, it is proposed that non-ossicle temporal bone homografts have a place in transplantation surgery.

Animals↗
PubMed1990

Wagner resurfacing hip arthroplasty. The results of one hundred consecutive arthroplasties after eight to ten years.

In a prospective study of 100 consecutive Wagner resurfacing hip arthroplasties in ninety-three patients, the outcomes for all hips were determined for an eight to ten-year follow-up period. By survivorship analysis, the rate of survival of the arthroplasty was calculated to be 70 per cent at five years, but only 40 per cent at eight years. The major cause of failure was aseptic loosening of the acetabular or femoral component, or both. Fracture of the neck of the femur occurred in three hips. Although the medium-term results (at fifty-six to eighty-three months) were better than those in most comparable studies of resurfacing arthroplasty, the poor long-term results (at ninety-one to 118 months) show that meaningful studies of new prosthetic designs must continue for at least eight years, and, if at all possible, must include 100 per cent follow-up. The survival curve for the resurfacing arthroplasties in this study can serve as the basis for comparison of the early, medium, and long-term results of future designs of resurfacing hip prostheses.

Adult↗
PubMed1989

Brain damage in fatal non-missile head injury in relation to age and type of injury.

Brain damage in a series of 635 fatal non-missile head injuries has been analysed with particular reference to the age of the patient and the type of injury. The differences in the type of brain damage in relation to age were less than we had anticipated, lending further support to the contention that the aged brain has a reduced potential for recovery. The analysis confirms the relationship between road traffic accidents, diffuse axonal injury, gliding contusions and 'basal ganglia' haematomas, and the importance of diffuse brain swelling resulting from a head injury in children.

Adolescent↗
PubMed1986

Activity swing.

Explore the source record for details and available documents.

Adult↗
PubMed1986

The surgical technique for implantation of the temporal bone stimulator (Audiant ABC).

Microsurgical techniques and modern hearing aids are very limited in providing hearing improvement to patients with a vast number of middle ear and external ear canal conditions. A new electromagnetic temporal bone stimulator (TBS), capable of direct stimulation of the cochlea, has been developed. Nothing is placed in the external ear canal. The internal portion of the device is placed in the mastoid portion of the temporal bone, thus completely bypassing the external canal, the ossicles, and the middle ear. This provides stimulation to the inner ear regardless of the condition of the external canal and the middle ear. Unilateral hearing losses may also be benefited by transfer of energy to the opposite ear. Selection of patients, the surgical technique, and the instrumental armamentarium are discussed. The pitfalls and expected results are described.

Audiometry↗
PubMed1986

An implantable hearing device: osseointegration of a titanium-magnet temporal bone stimulator.

The use of bone conduction hearing devices has recently entered the realm of implantable prostheses and solid-state electronics, resulting in improved fidelity and applicability for a wider range of patients. One particular device, a temporal bone stimulator (TBS), consists of an external sound processor and implanted portion to cause vibration under the skin. An implantable temporal bone stimulator screw constructed of titanium alloy with a permanent magnet can be vibrated by inductive transcutaneous coupling. The safety and osseointegration of the TBS bone screw were tested in adult goats that were free-field stimulated at 75 dB with the TBS processor for 4 to 21 weeks. Histologic comparisons of the soft tissue and bone adjacent to active and passive screws revealed no remarkable differences between them with bone growing in the interstices of the threaded portion. Evidence for mild reorganization of bone was shown with Goldner's stain, which differentiated bone that was young and unmineralized from bone that was older and mineralized. Reorganization was evident in both the active and passive sites and there was no remarkable difference between the two in a blind study. Additional evidence for the integrity of the implant was obtained by subjecting a calvarium containing both screws to a 5000 gauss magnetic field for 10 minutes of a nuclear magnetic resonance head scan. The calvarium was first dissected free from overlying skin and connective tissue. The magnet-containing screws were not loosened. We conclude that the implanted screw portion of the TBS implantable hearing device is well-integrated into the temporal bone. Mild stimulation of new bone growth indicates a healthy long-term viable implant for bone conduction amplification of sound.

Animals↗
PubMed1986

Temporalis muscle flap for the otologist.

Part or all of the mastoid cavity, ear canal, middle ear, and inner ear are frequently removed in tumor surgery by the otologist. This creates a cavity that is usually closed off at the level of the external meatus and filled with adipose tissue. When this cavity becomes infected in the postoperative period, the surgeon not only has to deal with the local infected cavity, but also with meningitis. This prohibits one from the standard surgical principles of incision and drainage to the outside. A case of an infected obliterated cavity is presented, as well as its treatment with a temporalis muscle flap. This resulted in closure of the dead space in the temporal bone, as well as a successful outcome for the patient.

Adult↗
PubMed1976

Craig-Scott orthosis: a biochemical and functional evaluation.

The Craig-Scott double upright knee ankle orthosis was subjected to a biomechanical evaluation which included analysis of the force interaction with the supported limb and a functional evaluation. The results were compared with data previously determined from biomechanical evaluations of other common orthoses. In the Craig-Scott design, the single application of the knee stabilizing force below the knee concentrates this force in a relatively small bony area, sometimes exceeding tolerance. This might be avoided by using a tibial closure with patellar tendon bearing features. The design was found to produce relatively low anatomic knee shear. In functional aspects such as donning, doffing, transfers and ambulation, the orthosis is essentially equivalent to other double upright designs. The rigidity of the orthosis with only a tibial band closure and a bail connecting the uprights was determined to be adequate. The limited number of bands and closures provides some advantages in reduced donning and doffing time; however, in the absence of posterior closures below the knee, the orthosis had a tendency to slide forward off the leg when transferring. This disadvantage was eliminated by adding a soft posterior closure below the knee, which produced a minimal increase in donning and doffing times.

Animals↗