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Biomedical subjects

E J Evans

Publications and source records attributed to E J Evans.

At least 19 recordsLinked to original sources
PubMed2000

Signaling lymphocytic activation molecule (CDw150) is homophilic but self-associates with very low affinity.

Signaling lymphocytic activating molecule ((SLAM) CDw150) is a glycoprotein that belongs to the CD2 subset of the immunoglobulin superfamily and is expressed on the surface of activated T- and B-cells. It has been proposed that SLAM is homophilic and required for bidirectional signaling during T- and B-cell activation. Previous work has suggested that the affinity of SLAM self-association might be unusually high, undermining the concept that protein interactions mediating transient cell-cell contacts, such as those involving leukocytes, have to be weak in order that such contacts are readily reversible. Using surface plasmon resonance-based methods and analytical ultracentrifugation (AUC), we confirm that SLAM is homophilic. However, we also establish a new theoretical treatment of surface plasmon resonance-derived homophilic binding data, which indicates that SLAM-SLAM interactions (solution K(d) approximately 200 micrometer) are in fact considerably weaker than most other well characterized protein-protein interactions at the cell surface (solution K(d) approximately 0.4-20 micrometer), a conclusion that is supported by the AUC analysis. Whereas further analysis of the AUC data imply that SLAM could form "head to head" dimers spanning adjacent cells, the very low affinity raises important questions regarding the physiological role and/or properties of such interactions.

Animals↗
PubMed1999

Subjective fatigue and self-care in individuals with chronic illness.

Fatigue is a serious problem for individuals experiencing chronic illness that can cause difficulties managing self-care activities and achieving quality of life. The applicability of a standardized research instrument for clinical use was explored and shown to have the potential to advance caregivers' understanding of fatigue and its consequences.

Activities of Daily Living↗
PubMed1995

Radiologic study of the accuracy of a tibial intramedullary cutting guide for knee arthroplasty.

Twenty-one caucasian, adult cadaveric tibiae were prepared as for knee arthroplasty using an intramedullary cutting guide. The instrumentation was used to produce slots in the proximal tibia into which Kirschner wires were placed as radio-opaque markers for subsequent anteroposterior and lateral radiographs. The anatomic axis of the tibia and lines perpendicular to the wire markers were drawn on the radiographs and the angle between the two lines was measured to assess the accuracy of the cuts. Seventy-one percent of the tibial cuts were found to be within 2 degrees of the anatomic axis on the anteroposterior radiograph (mean, 2.1 degrees), while on the lateral radiograph, 81% of the cuts were within 2 degrees (mean, 1.8 degrees). There was a significant tendency to position the bone cuts in varus (P < .05), although this did not correlate with varus or valgus deformity of the bones. There was no consistent tendency to anterior or posterior tilt on the lateral radiograph (P > .05). The results compare favorably with those obtained from a specialist unit using an extramedullary alignment system. The authors conclude that the tibial intramedullary guide can lead to preparation of the proximal tibia for knee arthroplasty as accurately as the conventional extramedullary system.

Adult↗
PubMed1994

Cell damage in vitro following direct contact with fine particles of titanium, titanium alloy and cobalt-chrome-molybdenum alloy.

Fibroblastic cells in vitro were exposed to powders of titanium, titanium-aluminium-vanadium alloy and cobalt-chrome-molybdenum (Co-Cr-Mo) alloy, either in direct contact with the cells or separated from the cells by a microporous membrane. Fine particles of all the materials reduced cell growth when in direct contact with cells, but only the finest particles of Co-Cr-Mo alloy caused cell damage through the microporous membrane. This provides further evidence that there is a mechanism of cell damage in vitro which depends on a direct interaction between cells and particles and is largely independent of the chemical nature of the particle.

Alloys↗
PubMed1993

Avoiding nerve damage during elbow arthroscopy.

To define the anatomical relationships of the nerves to the common arthroscopy portals at the elbow an arthroscope was introduced into 20 cadaver elbows and the positions of the nerves were then determined by dissection. In all cases the posterior interosseous nerve lay close to the radiohumeral joint and to the anterolateral portal. Pronation of the forearm displaced the nerve away from the arthroscope. The median nerve passed consistently within 14 mm of the arthroscope when it was introduced through the anteromedial portal. The branches supplying the superficial forearm flexor muscles were at risk.

Arthroscopy↗
PubMed1993

Loss of the fibrocartilaginous lining of the intertubercular sulcus associated with rupture of the tendon of the long head of biceps brachii.

Fibrocartilage lines the intertubercular sulcus of the humerus and protects both the bone and the tendon of the long head of biceps brachii where the tendon passes through the sulcus. It provides a smooth, resilient, lubricated gliding surface on the bone. The fibrocartilage is highly metachromatic and organised into distinct superficial and deep zones. In the superficial zone, the cells are small and the fibres run parallel to the articular surface. In the deep zone, the cells are large and rounded and the coarse bundles of fibres are interwoven. In 6 of the 26 dissecting room cadavers examined the tendons were completely ruptured. In these, the fibrocartilage was replaced by loose connective tissue that resembled the synovium of the tendon sheath. The results suggest that bone fibrocartilage exhibits dynamic behaviour in response to changes in its environment, in the same manner as tendon fibrocartilage.

Aged↗
PubMed1992

The structure of the insertions of the tendons of biceps brachii, triceps and brachialis in elderly dissecting room cadavers.

The terminal portions of the tendon of brachialis, and the distal tendons of biceps brachii and triceps, were compared by routine histology. All tendons came from elderly dissecting room cadavers. There were pronounced quantitative differences between the 3 tendons in (1) the thickness of the attachment-zone fibrocartilage, (2) the thickness of cortical calcified tissue, and (3) the percentage of bone to marrow. There was significantly more uncalcified fibrocartilage at the attachment of biceps than at the other sites, reflecting greater range of movement of the tendon at this site. The thickness of cortical calcified tissue and the percentage of bone to marrow were significantly greater at the attachment of brachialis than either biceps or triceps. The large quantities of bone at the attachment of brachialis may be related more to the importance of the coronoid process in buttressing the elbow joint than to any special requirement for large amounts of calcified tissue at the tendon attachment. Near its attachment zone, the biceps tendon splits into superficial and deep laminae that are distinct from the macroscopic subdivision of this tendon. It is suggested that the lamination may facilitate the movements of pronation and supination. In support of this, the deep portion of the superficial lamina contained fibrocartilage where it rubbed against the attachment-zone of the deep lamina. In one body, the fibrocartilage of the biceps attachment-zone was subject to degenerative changes, including cell clumping and matrix fissuring.

Aged↗
PubMed1991

Toxicity of hydroxyapatite in vitro: the effect of particle size.

Finely ground powders of synthetic hydroxyapatite applied to fibroblasts in vitro reduced the total growth rate and mitotic rate of the cells and increased the number of pycnotic cells. The effect was dose related and only occurred with small particles. The small particles appear to either adhere to the cells or are phagocytosed by them and the toxic effect may be physical rather than chemical.

Animals↗
PubMed1991

Quantitative differences in the histology of the attachment zones of the meniscal horns in the knee joint of man.

The attachment zones of the meniscal horns of 7 dissecting room cadavers were examined by routine histology. All the knees were devoid of gross pathological change and no discoid menisci were included. Significant differences are reported in the thickness of the zones of uncalcified fibrocartilage and cortical calcified tissue (calcified fibrocartilage and underlying lamellar bone) and in the percentage of bone:bone marrow. There was a thicker zone of uncalcified fibrocartilage and a greater quantity of calcified tissue at the horns of the lateral than the medial meniscus. The differences in uncalcified fibrocartilage were largely attributable to the posterior horns, but the variations in calcified tissue mainly reflected differences between the anterior horns. It is suggested that the greater mobility of the lateral meniscus and the blending of its anterior horn with the anterior cruciate ligament are important factors accounting for the quantitative differences in the meniscal attachment zones.

Aged↗
PubMed1991

Variations in the amount of calcified tissue at the attachments of the quadriceps tendon and patellar ligament in man.

Differences are reported in the total calcified tissue/bone marrow ratios and in the total thickness of cortical calcified tissue (lamellar bone and calcified fibrocartilage) between the attachment sites of the quadriceps tendon and the patellar ligament in man. The greatest amount of calcified tissue is at the insertion of the tendon and this is correlated with the larger force that the tendon transmits. It is concluded that differences in maximum force alone can produce a greater density of calcified tissue at ligament or tendon attachments. The similar amounts of calcified tissue at each end of the patellar ligament reflect the identical force that each attachment transmits. At the insertion of the quadriceps tendon and the 'origin' of the patellar ligament, there was more calcified tissue beneath the superficial than the deep parts of the attachment. This suggest that more force is transmitted through some parts of an attachment zone than others.

Aged↗
PubMed1990

Fibrocartilage.

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Animals↗
PubMed1990

Fibrocartilage in the attachment zones of the quadriceps tendon and patellar ligament of man.

Differences are reported in the quantities and distribution of uncalcified fibrocartilage at the attachment sites of the quadriceps tendon and the patellar ligament. The largest quantity of fibrocartilage was characteristic of the quadriceps tendon. A prominent wedge of fibrocartilage was seen in the proximal part of the tibial attachment of the patellar ligament, though there was no fibrocartilage in the most superficial fibres. Little fibrocartilage was seen at the patellar attachment of the patellar ligament. According to other workers, there is a similar change in angle (about 35 degrees) between the quadriceps insertion (in relation to the patella) and the tibial attachment of the patellar ligament (in relation to the tibia). However, there is virtually no change in angle at the origin of the patellar ligament (relative to the patella). Thus, fibrocartilage is least conspicuous where there is little motility near an attachment site. It is suggested that the larger amount of fibrocartilage in the quadriceps tendon compared with the tibial attachment of the patellar ligament may be related to the greater absolute size (and particularly anterior-posterior thickness) of the tendon compared with the ligament.

Aged↗
PubMed1990

Histological studies on the triangular fibrocartilage complex of the wrist.

The triangular fibrocartilage complex of the wrist was serially sectioned for routine histology. Results from eight dissecting room cadavers show that the complex is attached to hyaline cartilage on the radius via its articular disc. In contrast, the dorsal and volar radio-ulnar ligaments attach to the radius via zones of calcified and uncalcified fibrocartilage. The articular disc is thus a wide labrum that provides an articular surface for the ulna and for the carpal bones, and the radio-ulnar ligaments strengthen the attachment of the disc to the radius. Medially, the complex divides into upper and lower laminae. Arching strands of collagen fibres emerge from the upper lamina and pass through a region of highly vascular connective tissue to be attached to the ulna between the articular cartilage on the head and that at the tip of the styloid process. Much of the ulnar attachment is via zones of calcified and uncalcified fibrocartilage which blend with the adjacent articular cartilages. Such an arrangement of tissues prevents undue wear and tear at the ulnar attachment zone during pronation and supination of the forearm. The lower lamina blends with the sheath of extensor carpi ulnaris and the ulnar collateral ligament and allows the whole complex to attach to the carpal and metacarpal bones. The meniscus homologue is a region of dense irregular connective tissue with no independent histological identity.

Aged↗
PubMed1987

The effect of grinding conditions on the toxicity of cobalt-chrome-molybdenum particles in vitro.

Powders of cobalt-chrome-molybdenum alloy were produced by grinding larger particles for 8 h in water, serum or joint fluid. They were administered, in low doses (0.05-0.5 mg/ml) for 1-6 d, to human dermal fibroblasts in vitro. Particles were ground in a biological fluid in order to simulate conditions in an artificial hip joint. Such particles adhered to, or were phagocytosed by, the cells far less than those ground in water. The toxicity of the alloy was linked with a failure of test cells to grow as quickly as the controls - particles ground in water were the most toxic.

Alloys↗
PubMed1987

Single-dose accumulation pharmacokinetics of tobramycin and netilmicin in normal volunteers.

The two-compartment tissue accumulation pharmacokinetics of tobramycin and netilmicin were compared in 11 normal volunteers by using a crossover design. After each 1.0-mg/kg (body weight) dose, serum was collected for 96 h, and complete 24-h urine collections were obtained for a total of 30 days. Two months of washout were required before crossover. Concentrations in serum and urine were measured by radioimmunoassay, and concentrations in serum and urinary excretion rates were simultaneously fitted to a two-compartment pharmacokinetic model. Netilmicin exhibited significantly lower total body clearance (48 versus 90 ml/min) and longer terminal elimination half-life (161 versus 96 h) than tobramycin. As a result of these pharmacokinetic differences, the predicted tissue accumulation of netilmicin at steady state was significantly higher than that of tobramycin (P less than 0.05). Relative rates of aminoglycoside nephrotoxicity probably depend on both the differential tissue uptake (accumulation) and the concentration of the aminoglycoside which produces intracellular toxicity. Because the steady-state tissue accumulation of netilmicin is nearly 2.5 times greater than that of tobramycin, its potency in the production of intracellular toxicity needs to be that much less for the two agents to produce the same incidence of clinical nephrotoxicity.

Adult↗
PubMed1986

The effect of cobalt-chromium-molybdenum powder on collagen formation by fibroblasts in vitro.

Surgical implants frequently become surrounded by fibrous tissue. In order to investigate the mechanisms which cause this fibrosis, fibroblastic cells in culture were exposed to powders of cobalt-chromium-molybdenum alloy simulating the wear debris of metal-on-metal joint replacements. Collagen production during periods of up to 20 d was assayed by measurement of soluble and insoluble hydroxyproline. No stimulation of collagen production was seen with any of the concentrations of metal powder tested. It is therefore suggested that fibrosis around joint replacements is not caused by direct stimulation of fibroblasts by metallic wear debris.

Animals↗
PubMed1986

The in vitro toxicity of cobalt-chrome-molybdenum alloy and its constituent metals.

Cobalt-chrome-molybdenum alloys are widely used in orthopaedic implants. Although they are relatively well tolerated, complications (including loosening and tissue necrosis) still occur and sometimes appear to be due to incomplete biocompatibility of the alloy. To investigate the local effect of the alloy on cells derived from the musculo-skeletal system, primary lines of fibroblastic cells from newborn rats were exposed to powders of cobalt-chrome-molybdenum alloy and its main constituents cobalt, chromium nickel and molybdenum. The toxicity of the metals was determined by counts of total cell number and of abnormal cells at intervals from 2 to 12 d. The alloy was much less toxic than cobalt or nickel and the pattern of toxicity was different for each metal. The results emphasize the difficulty of devising a single tissue culture test of toxicity which will measure the toxicity of any potential implant material.

Animals↗