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Biomedical subjects

D L Gardner

Publications and source records attributed to D L Gardner.

At least 91 records · Page 5Linked to original sources
PubMed1981

Mandatory continuing education or periodic reexamination?

A descriptive study of physical therapists located primarily in the southeastern United States was undertaken to determine their opinions concerning mandatory continuing education or reexamination for license renewal. A majority of the 1,187 respondents favored continuing education rather than reexamination. Of those favoring continuing education, a majority prefer a yearly minimum requirement of at least 10 hours, a three-year review cycle, a sharing of costs by therapists and employers, provision of courses by the national association, approval of courses by the district or state association, and awarding of credit for demonstrated improved performance at the course. Of those favoring periodic reexamination, a majority preferred a five-year cycle, self-assessment methods available prior to reexamination, a sharing of costs by therapists and government, and an oral examination that the national association would compose but academic institutions administer. Both groups favor probationary status for noncompliance. Based on the findings, some implications for adoption and implementation of either system for the physical therapy profession are discussed.

Accreditation↗
PubMed1981

Low temperature scanning electron microscopy of dog and guinea-pig hyaline articular cartilage.

Fifty seven blocks of cartilage excised from the femoral condyles of 20 beagle dogs, and whole lower ends of 5 guinea-pig femora, were examined at -195 degrees (78 K), by scanning electron microscopy. The unfixed tissue, taken into slushy nitrogen at -210 degrees (63 K), was not exposed to atmospheric air after quenching and remained fully hydrated throughout long periods of observation. Images susceptible to analysis were obtained from washed and from unwashed cartilage surfaces. Preliminary coating with gold or with aluminium, known to be possible without exposing cold cartilage surfaces to changes in temperature likely to cause water loss by sublimation, was valuable in minimising charging and in facilitating the recording of electron images at higher magnifications. Although examination was possible without coating, the resultant images were of low resolution. Microscopy revealed a pattern of secondary surface irregularities of tertiary elevations closely resembling those seen by the conventional scanning electron microscopy of fixed, dehydrated hyaline cartilage. However, the pattern of tertiary surface structures was predominantly that of elevations, not of hollows. Quaternary surface ridges were common on the surfaces of excised dog cartilage blocks and were not seen on the surfaces of guinea-pig cartilage which remained on the femoral condyles.

Animals↗
PubMed1980

Production of split patterns on the articular cartilage surfaces of rats.

A device has been designed to permit reproducible loads to be applied perpendicularly to the acutely curved cartilage surfaces of the diarthrodial joints of small animals. With this apparatus, a sharp, round pin has been used to cause splits in the hyaline articular cartilage of the lower end of the femurs of 37 Wistar rats. In the patellar groove, the splits form a longitudinal pattern. On the condylar surface, the pattern is fantail, radial or non-uniform. It is suggested that cartilage thickness, joint congruence and load per unit area, are variables related to the directional pattern of the splits. These variables, in turn, reflect the gross, microscopic and molecular anatomy of the cartilage. The effects pin-pricks are comples: they disrupt surface collagen bundles and other cartilage components. Experiments made to test the effects of drying, isotonic saline, hyaluronic acid and sodium hydroxide support the view that the state of hydration and fluid flow are important determinants of the shape of cartilage splits. However, sodium hydroxide-induced cartilage disruption, involving glycosaminoglycan loss, did not influence split configuration. Some preliminary evidence suggests that the process of crack propagation, by which splits form, may be related to the position and shape of chondrocyte lacunae. It is concluded that pin-prick testing offers a means by which the structural properties of the cartilage of small diarthrodial joints may be conveniently tested in vitro.

Animals↗
PubMed1980

Influence of aqueous fixation on articular surface morphology. A reflected light interference microscope study.

Fresh, unfixed temporomandibular fibrous articular surfaces from baboons were examined by reflected light interference microscopy. The appearances, recorded photographically, were compared with those of joints subjected to aqueous fixation in buffered glutaraldehyde and formalin. Fixation caused readily detectable, measureable changes in articular surface morphology. Reflected light interference microscopy is a valuable technique for the demonstration of the effects of fixation on articular surface morphology.

Aldehydes↗
PubMed1980

Fine structure of artificial splits in femoral condylar cartilage of the rat: a scanning electron microscopic study.

Artificial splits made in rat femoral condylar articular cartilage have been studied by SEM. Three types of split have been described; non-layered, unidirectional layered and multidirectional layered. The frequency of each type of split varies in the different regions of the condyle. Deformation and crack propagation are features of layered splits and the latter are often accompanied by exposure of fibres. The fibre pattern over the articulating surface of the rat femoral condyle, revealed by trypsin or NaOH treatment, has been determined and a correlation found between this pattern and the orientation of splits previously observed by ILM. The influence of fibre arrangement on split production is discussed and consideration given to other factors, such as mechanical stress, chondrocyte distribution or PG concentration gradients, which may determine both characteristic patterns. Further evidence is presented of the value of the pin prick method as a technique for exploring the nature of normal and abnormal articular cartilage.

Animals↗
PubMed1979

Changes with age in the glycosaminoglycans of human articular cartilage.

Human articular cartilage was obtained post mortem from the lateral femoral condyles of 30 subjects aged from under 1 to 70 years. Cryostat sections taken 0--100 micrometers and 900--100 micrometers deep to the cartilage surface were exhaustively extracted to recover the glycosaminoglycans (GAG). After fractionation by cellulose acetate electrophoresis and enzyme depolymerisation individual GAG were determined by alcian blue -0.05 M MgCl2 and disaccharide microassay procedures. Changes with age were observed in GAG concentration and in the proportion of individual GAG. Large alterations occurred during the period of skeletal growth (0--16y). At birth GAG formed about 50% of the dry weight of cartilage, a value that decreased to about 15% in adult cartilage. Chondroitin sulphates (ChS) formed the principal GAG of articular cartilage and accounted for almost all of the GAG of the infant material. The ChS decreased with age and were partially replaced by keratan sulphate (KS), so the KS eventually comprised 12% of the GAG. Hyaluronic acid (HA) was identified and was found to increase linearly with age to form 6% by weight of the cartilage GAG by 60y.

Adolescent↗
PubMed1979

In vitro measurement of articular cartilage deformations in the intact human hip joint under load.

Using a new roentgenographic technique for measuring cartilage deformation in intact joint specimens, twenty-eight normal human hip joints from subjects twenty-five to eighty-five years old were loaded with a force of five times body weight in a testing machine. The initial unloaded thickness of the articular cartilage of the femoral head and the changes in thickness of this cartilage under load were measured roentgenographically at seven to twelve sites on each femoral head. These measurements showed that the deformations of femiral-head articular cartilage under load in the intact joint are non-uniform and increase greatly with age. In twelve specimens measurements were also made of the increase in cartilage deformation with time when the load of five times body weight was maintained on the joint. A single osteoarthrotic joint was also studied. The experimental findings imply changes in the fundamental mechanical properties of the cartilage with age, which probably result from age-related alterations in cartilage microstructure and chemical composition.

Adult↗
PubMed1978

The surface structure of ageing human articular cartilage: a study by reflected light interference microscopy (RLIM).

The surface contours of the weight-bearing area of the left lateral femoral condyle have been examined in vitro in 26 cadavers by reflected light interference microscopy over the age range 0--47 years. The presence of 4 orders of surface irregularity was confirmed. In addition, measurement of the depth, diameter and frequency of the tertiary order of surface hollows showed that while none of these variables was sex-associated, age-related changes in the variables were present. Multiple regression analysis showed that these changes could be considered in terms of periods of maturation (0--21 years) and ageing (22--50 years) of the cartilage. Focal changes in the surface were observed with advancing age. These changes appeared to be regressive and possibly represent an early stage in cartilage fibrillation.

Adolescent↗
PubMed1977

The micro-assay of the disaccharide isomers of chondroitin sulphate.

Connective tissue extracts containing the 4- and 6-sulphated isomers of chondroitin sulphate can be measured at the microgram level (approximately 10 microgram) using colorimetric assays. The chondroitin sulphates are depolymerised to disaccharides using chondroitin ABC lyase (EC 4.2.2.4). The 4- and 6-sulphated disaccharides after treatment with acid periodate are determined using a thiobarbituric acid procedure. An alkaline borate p-dimethylaminobenzaldehyde reaction is used to measure 6-sulphated disaccharide, the 4-sulphated disaccharide not forming a chromogen. Unsulphated disaccharide causes interference in both assays and if present is separated prior to assay using paper electrophoresis fractionation.

Chondroitin↗
PubMed1977

Thickness and distribution of human femoral head articular cartilage. Changes with age.

The distribution of hyaline cartilage in the sagittal plane of the normal human femoral head was examined. 28 specimens from persons aged 10 to 68 years subject to post-mortem examination in a teaching hospital were anatomically orientated and x-rayed in a lateromedial projection. An optical technique was used to measure the cartilage thickness from the x-ray films thus produced. Measurements were made with a sensitivity of +/- 0-01 mm using a metrological projector. 11 defined sites on each femoral head were surveyed to give the distribution of cartilage thickness. The greatest thickness was identified anterior to the zenith. Between the ages of 20 and 45 years the thickness of this zone increased with age. The thickness of femoral head cartilage was not evidently related to femoral head diameter, femur length, or body weight.

Adolescent↗