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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
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.

Explore the source record for details and available documents.

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↗
PubMed1986

Delayed rupture of the spleen presenting as a scrotal hematoma.

A case of a delayed rupture of the spleen presenting as a left scrotal mass (hematoma) is described. This interesting association was made with computerized axial tomographic scanning, ultrasound, and surgical exploration. When a scrotal mass is suspected to be a hematoma, abdominal pathology as a cause must be ruled out.

Adult↗
PubMed1986

The histology of tendon attachments to bone in man.

Based on a parallel study of a wide range of human tendons from embalmed dissecting room subjects and from a study of dried bones, an explanation is offered for the well known similarity in gross appearance between the markings left by certain tendons (e.g. those of the rotator cuff) and by articular surfaces on dried bones. Epiphyseal tendons leave markings on bones that look like those left by articular surfaces. These tendons have a prominent zone of fibrocartilage at their attachment site and the deepest part of this is calcified, just as the deepest part of articular hyaline cartilage is calcified. After maceration of the soft tissues, the calcified (fibro) cartilage is left attached to the bone at articular surfaces and at the sites of tendon attachment. In all cases, the tissues separate at the basophilic tidemark between the calcified and uncalcified regions. This tidemark is smooth where there is much overlying uncalcified (fibro) cartilage and it is the smoothness that gives the typical appearance of the dried bone. Blood vessels do not generally traverse the tendon fibrocartilage plugs. Hence the areas are devoid of vascular foramina. The functional significance of tendon fibrocartilage is discussed with particular reference to supraspinatus. It is suggested that the uncalcified fibrocartilage ensures that the tendon fibres do not bend, splay out or become compressed at a hard tissue interface, and are thereby offered some protection from wear and tear. It is also suggested that the fibrocartilage plug of supraspinatus prevents the tendon from rubbing on the head of the humerus.

Aged↗
PubMed1985

Vibratory properties and resonances of the isolated human ulna.

The frequency response, at various points along the length and circumference, of two isolated human ulnas has been recorded during white noise excitation under 'free-free' conditions. Both bones showed a similar pattern of multiple frequencies of resonance; two fundamental mode resonances occurring in directions mutually at right angles. Further resonances appeared at higher frequencies, both in the same planes as the fundamental modes and in a second plane at 45 degrees; changing the plane of excitation through 90 degrees produced only small changes in the pattern of resonances. Both bones showed marked coupling between neighbouring resonances, with pulling of the frequencies of resonance so that the frequency of the resonant peak may appear to vary by up to 10%.

Biomechanical Phenomena↗
PubMed1985

Health risks of snorkel swimming in untreated water.

There are certain health risks associated with recreational exposure to bacteriologically polluted water. In this study, 27% (21/77) of swimmers who took part in a snorkel swimming event, experienced gastrointestinal symptoms within 48 hours of entering the untreated water. The incidence of these symptoms was statistically significantly greater than the incidence of such symptoms reported by two control populations (p less than 0.001), but not significantly different to 25% of people who had experienced gastrointestinal symptoms in a previous snorkel event in the same water environment. As the water quality came within the confidence intervals of the EEC standards for bathing water the adequacy of these standards needs further appraisal.

Adolescent↗
PubMed1979

Production of heat-stable, methanol-soluble enterotoxin by Yersinia enterocolitica.

Seven isolates of Yersinia enterocolitica serotype 0:8, recovered during an outbreak of gastrointestinal illness, were examined for enterotoxin production. All seven strains were enterotoxigenic in the suckling mouse model, and three of five isolates tested produced keratoconjunctivitis in the guinea pig eye model (Sereny test). Enterotoxin was detected in broth supernatant fluid after 12 h of incubation at 25 degrees C. The toxin was not inactivated by exposure to 121 degrees C for 30 min or by storage at 4 or -40 degrees C for at least 5 months. The enterotoxin was also acid stable and methanol soluble. Methanol extraction did not affect its heat stability or enterotoxic activity in suckling mice. These physical characteristics plus limited ultrafiltration studies suggest that the enterotoxin is a low-molecular-weight substance. Y. enterocolitica enterotoxin resembles Escherichia coli heat-stable enterotoxin in heat and pH stability, methanol solubility, and enterotoxic activity in suckling mice. However, its role in the pathogenesis of human diarrhea has not been established.

Bacterial Toxins↗
PubMed1977

Scanning electron microscopy of freeze-dried aortic elastin.

As part of a larger project aimed at claryfying some of the uncertainties that exist concerning the structural basis for an explanation of the mechanical behaviour of elastin, an examination was made of purified porcine aortic elastin under the scanning electron microscopy. In order to avoid structural changes caused by impregnation with organic solvents, specimens were prepared directly from their water-saturated state by either air-drying of freeze-drying processes. Comparison of the results obtained by these techniques demonstrates that freeze-drying of elastin has the advantage of enhancing fine detail, minimizing distortion and reducing specimen shrinkage.

Animals↗