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Biomedical subjects

K A Mayo

Publications and source records attributed to K A Mayo.

27 records · Page 2Linked to original sources
PubMed1989

Displaced intra-articular fractures of the tarsal navicular.

Between 1980 and 1987, twenty-one patients who had a displaced fracture of the body of the tarsal navicular were treated with open reduction and internal fixation. A classification system was devised on the basis of the direction of the fracture line, the pattern of disruption of the surrounding joints, and the direction of displacement of the foot. In a Type-1 injury, the fracture line is in the coronal plane and there is no angulation of the fore part of the foot. In a Type-2 fracture, the primary fracture line is dorsal-lateral to plantar-medial, and the major fragment and the fore part of the foot are displaced medially. In a Type-3 injury, there is a comminuted fracture in the sagittal plane of the body of the tarsal navicular, and the fore part of the foot is laterally displaced. Satisfactory reduction, which was defined as restoration of more than 60 per cent of the joint surface in the anteroposterior and lateral planes, was achieved in all Type-1 injuries, 67 per cent of the Type-2 fractures, and 50 per cent of the Type-3 fractures. Radiographic evidence of healing was seen at an average of 8.5 weeks after injury. At an average follow-up of forty-four months (range, twelve to 106 months), a good result was noted in fourteen patients (67 per cent); a fair result, in four (19 per cent); and a poor result, in three (14 per cent). Both the type of fracture and the accuracy of the operative reduction directly correlated with the final clinical outcome.

Adolescent↗
PubMed1987

Radiographic evaluation of modern orthopedic fixation devices.

Orthopedic surgeons employ a wide variety of modern fixation devices in the treatment of fractures. In order to assess these instruments correctly, the radiologist should be aware of both their purpose and their normal appearance. A review of the common internal and external fixation devices used at a major trauma center and the complications of their use has been presented.

Bone and Bones↗
PubMed1987

Subtrochanteric fracture of the femur. Fixation using the Zickel nail.

We divided 131 patients who had a subtrochanteric fracture into four clinical groups: elderly patients who had a fracture secondary to minor trauma, patients who had a fracture due to high-energy trauma, those who had a pathological fracture, and patients who had a fracture that previously had been treated unsuccessfully with internal fixation. In each patient operative fixation was performed using the Zickel device, and overall satisfactory results were obtained in 90 per cent. Considering the challenging nature of subtrochanteric fractures, complications, which included a rate of non-union of approximately 5 per cent, were minimum. Technical details for each of the four groups are emphasized.

Adolescent↗
PubMed1987

Fractures of the acetabulum.

Open reduction and internal fixation should now be considered the treatment of choice for most displaced fractures. The efficacy of this therapeutic approach is a function of improved fracture assessment coupled with advances in surgical exposure and stabilization techniques. A predictably high rate of good functional outcomes can now be expected, even in complex fracture patterns. It should be remembered, however, that this surgery is among the most demanding in orthopedics. Extensive study of general principles and techniques is necessary, and individual case preparation must be exhaustive. Early experience is probably best restricted to elemental fracture patterns. In this manner, both patient and surgeon may rely on a positive outcome.

Acetabulum↗
PubMed1986

Developmental regulation of gene expression in Tetrahymena.

The onset of gene expression in Tetrahymena thermophila during macronuclear differentiation was investigated by assay of galactokinase in conjugating deoxygalactose-resistant heterokaryons. Our results distinguish three successive states of galactokinase gene expression for cells developing a new macronucleus: stage 0, refractory to induction; stage 1, inducible by refeeding; and stage 2, induced. The refractory period ends at 12 to 13 hr after the onset of conjugation; this corresponds to the time of pair separation, and occurs several hours after the new macronuclei have become morphologically distinguishable. Stage 1 cells behave indistinguishably from mature starved cells. Inhibitor studies suggest that galactokinase synthesis is induced coincidentally with the induction of bulk protein synthesis during conjugation: thus it behaves developmentally like a typical protein; and that galactokinase mRNA is probably transcribed within 1 hr prior to its translation. Thus, when conjugating cells are refed during the refractory period, some developmental condition prevents the swift induction of protein (and galactokinase) synthesis observed upon refeeding starved (nonmating) cells. The possible nature of this developmental phenomenon is discussed.

Animals↗
PubMed1981

Further evidence for lack of gene expression in the Tetrahymena micronucleus.

Certain galA mutations in the ciliated protozoan Tetrahymena thermophila confer an almost total loss of galactokinase activity in homozygotes. Heterokaryons have been constructed that are homogeneous for the galA1 mutation in the (45n) macronucleus, but which contain a galA+ (2n) micronucleus. Soluble cell extracts prepared from these heterokaryons have been assayed for galactokinase activity, using a radiometric assay for the conversion of galactose to galactose-1-phosphate (gal-1-P). No galactokinase activity attributable to the micronuclear genes is observed in such heterokaryons. These results, obtained with the galA1 marker, provide the first direct, quantitative evidence for the lack of micronuclear (germ line) gene expression in Tetrahymena during vegetative growth, and substantiate the predictions of previous phenotypic observations on heterokaryons and autoradiographic studies of micronuclear RNA synthesis. The generality of this conclusion will be established in the future when other enzymically assayable mutations become available for similar studies.

Animals↗
PubMed1977

A model compartmental syndrome in man with particular reference to the quantification of nerve function.

A human model system was used to investigate the effect of increased tissue pressure on different parameters of the function of the nerves and muscles in the anterior compartment of the leg. Abnormalities of sensation, strength, motor nerve-conduction velocity, and compound muscle-action-potential amplitude occurred in a parallel fashion when the intracompartmental pressure exceeded a threshold value. This threshold was significantly lowered by elevation of the extremity. Grossly abnormal functional parameters were consistently elicited when the peripheral pulse remained intact. The motor nerve-conduction velocity and compound muscle-action-potential amplitude appear to be reliable, non-invasive, and quantitative parameters of the physiological status of the neuromuscular tissue within the compartment.

Action Potentials↗
PubMed1976

Monitoring of intramuscular pressure.

Increased pressure within an osteofascial compartment may produce a compartmental syndrome, one of the principal causes of local circulatory compromise in traumatized extremities. In certain instances, monitoring of intracompartmental pressure may be a valuable adjunct in the clinical evaluation of patients at risk for this syndrome.

Animals↗