Biomedical subjects
J B Finlay
Publications and source records attributed to J B Finlay.
Cartilage impact in vitro: effect of bone and cement.
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Instrumentation and procedure for the controlled impact of articular cartilage.
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Impact characteristics of articular cartilage.
A rigid l m high stainless steel drop tower employing linear bearings has been used to study the impact characteristics of human articular cartilage. Instrumentation included a specially designed optoelctronic position transducer, piezoelectric force transducer, and high speed storage oscilloscope. Forty-eight 9 mm diameter samples of living articular cartilage and subchondral bone from the tibial plateaus of 4 human donors have been impacted at strains from 10 to 50%, and strain rates of 500s-1 and 1000 s-1. The integral bone/cartilage samples were mounted in polymethyl methacrylate for testing. Bone and cement impact characteristics have been studied separately. Stress, strain, and energy absorption data have been assembled for all the samples. Chondrocyte viability subsequent to impact has been investigated with the use of tritum labeled proline and autoradiography. Viability has been studied in relation to both the mechanical data and structural damage.
Survival of articular cartilage after controlled impact.
Survival characteristics of forty-three specimens of living human bone and articular cartilage from the knees of eight renal-transplant donors were studied, using a drop-tower device. Autoradiography and light and scanning electron microscopy revealed no evidence of chondrocyte death or structural damage until stress levels of twenty-five newtons per square millimeter were reached, corresponding to strains on the order of 20 to 30 per cent and involving energy absorption of one millijoule per cubic millimeter. The data for strain rates of 500 and 1000 s-1 suggest that impact loads sufficient to fracture a femoral shaft of an automobile occupant are nearly sufficient to cause chondrocyte death and fissuring in the articular cartilage of either the knee or the hip if the load-bearing areas measure less than 500 square millimeters.
Scanning electron microscopy of normal human scar tissue and keloids.
The fibrous architecture of 5 normal human scars between 1 week and 1 year old and 4 keloid scars has been studied by scanning electron microscopy. In normal wounds, significant changes in fibril and fibre orientations and mode of aggregation take place as the scars mature, indicating that remodelling carries on for many months. There are also major differences between the edge and centre of the wound. These changes can be related to the stresses placed on the fibroblasts which have responded by laying down collagen aligned in such a way as to resist these forces. It is suggested that keloid fibroblasts may lack this ability to respond appropriately to orientational stress.
Transarterial electrocoagulation therapy of a pseudoaneurysm in the head of the pancreas.
Because chemical and transcatheter embolizations for control of bleeding were inappropriate, electrocoagulation through a guidewire was used for arterial occlusion. The power was alternating current. The effectiveness of the procedure was confirmed by arteriograms done immediately and 5 months later.
Proposals for the selection and testing of d.c. defibrillators.
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The fibrous components of bovine ligamentum nuchae observed in the scanning electron microscope.
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Letter: Method and apparatus for testing and calibrating d.c. defibrillators.
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Preparation of human skin for high-resolution scanning electron microscopy using phosphate buffered crude bacterial alpha-amylase.
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Visualization of collagen cross-banding in the scanning electron microscope.
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The role of tissue pressure measurement in diagnosing chronic anterior compartment syndrome.
Pressure studies were performed in 55 patients (24 with chronic anterior leg pain and 31 asymptomatic recreational athletes). Pressure measurements were recorded at rest, during, and after exercise, using the slit catheter system. Seventeen of the twenty-four patients with symptomatic anterior leg pain were diagnosed on the basis of tissue pressure studies as having chronic exertional compartment syndrome. The increased tissue pressures at rest and after exercise are most helpful in distinguishing those patients likely to benefit from a surgical fasciotomy.
Microstructural organization of human and bovine cruciate ligaments.
Human and bovine anterior cruciate ligaments studied with the SEM demonstrate fascicular bundle and connective tissue sheath components. In the human, collagen fibers of the connective tissue sheath, although approximately the same diameter as the fascicular fibers, have an orientation suggestive of a binding rather than a tensile function. While both elements have tensile properties, it is hypothesized that the contribution from the sheath component is minimal and, consequently, detailed studies of the tensile properties of ligaments will produce meaningful data when related to the appropriate cross-sectional areas. In direct contrast to the human counterpart, the SEM appearance of bovine cruciate ligaments is tendon-like, characterized by very dense subfasciculi surrounded by very thin connective tissue sheaths.
Controlled voltages for electroconvulsive therapy.
A description is given for the design of an isolated output, servo-controlled voltage, electroconvulsive therapy (ECT) machine for the safe, controlled application of 60-Hz alternating current (ac) signals between 0 and 230 V rms for controlled periods ranging from 0.1 to 2 sec. Added safety is provided by current limiting in the range of 360 to 770 mA rms for patient impedances ranging from 500 to 50 omega. The use of this equipment has permitted a detailed description of the impedances characteristic of unilateral ECT.
Impact characteristics of articular cartilage.
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