The need for a randomised trial of hormone replacement therapy in women with breast cancer.
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Breast Neoplasms↗
Biomedical subjects
J A Davidson
Publications and source records attributed to J A Davidson.
Warming lignocaine to reduce pain associated with injection.
OBJECTIVE: To investigate the effect of warming lignocaine on the pain associated with subcutaneous injection. DESIGN: Double blind, randomised, crossover study. SETTING: Hospital clinic. SUBJECTS: 40 healthy volunteers. INTERVENTIONS: Subcutaneous injection with 1 ml of 1% lignocaine at 20 degrees C and 1 ml of 1% lignocaine at 37 degrees C. MAIN OUTCOME MEASURES: Pain assessed by linear analogue pain scores and subjects' comparison of pain on injection. RESULTS: 25 subjects (89%; 95% confidence interval 72% to 98%) thought that lignocaine at 20 degrees C was more painful and 3 (11%; 2% to 28%) thought that lignocaine at 37 degrees C was more painful (p < 0.0001); 12 subjects did not express a difference. Median pain score for injection at 20 degrees C was 11.00 and at 37 degrees C was 3.25 (p < 0.001). Median difference was 8.25 (4.00 to 13.50). CONCLUSIONS: The simple procedure of warming to 37 degrees C reduced the pain associated with subcutaneous injection of lignocaine.
Adult↗
HLA antigens and cervical carcinoma.
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Carcinoma, Squamous Cell↗
A biomechanical study of two methods of internal fixation of unstable fractures of the femoral neck. A preliminary study.
A model of an unstable femoral neck fracture was used in this study to compare the axial and torsional displacement obtained when the neck was fixed by a compression hip screw (CHS) and side plate, or three Knowles pins. Six paired, embalmed femora were mounted on a special, custom-made jig that grasped the femoral head and shaft securely. A standardized osteotomy was made with an oscillating saw, bisecting the distance between the lower cartilaginous portion of the femoral head and the intertrochanteric line. A 5-mm thick slice of bone was excised from the posteromedial quadrant of the distal fragment. The right or left femur in each pair was then randomly assigned to internal fixation with either three Knowles pins or a keyed CHS plus a 130 degrees four-hole side plate. After potting of the specimens and application of rosette strain gauges, axial displacements were measured during the application of in-plane and out-of-plane compressive loads. The resistance to torsion was also determined. There were no statistical differences between the two devices for compressive or torsional loading using this model.
Biomechanical Phenomena↗
Combined chemical and mechanical effects on free radicals in UHMWPE joints during implantation.
An electron spin resonance (ESR) technique is employed to determine the free radical distribution in the articulating surfaces of retrieved acetabular cups and knee-joint plateaus (retrieved after more than 6 years of implantation). Similar measurements made on samples prepared from cyclically stressed and unstressed cups, and on samples following oxidations in nitric acid and intralipid solutions provided sufficient data to gain more knowledge about the combined chemical and mechanical effects on PE free radicals during implantation. In UHMWPE free radicals are primarily initiated by gamma-ray sterilization; however, during implantation, peroxy (scission type) free radicals are formed and reach a maximum concentration level (equilibrium state) due to oxidation by chemical (hemoglobin and/or synovial fluids) environment of the joints. Subsequently, due to frictional heating and stress in the loading zones, free radical reaction is accelerated and their number is reduced only in those areas. This is consistent with the observations of a temperature rise in acetabular cups during in vitro frictional wear stress tests and in vivo telemetry observations, as reported by others. Compared with the previously reported SEM micrographs the low-free-radical regions are correlated with high-wear areas and the high-free-radical regions with the low-wear areas.
Biocompatible Materials↗
Diabetes care in minority groups. Overcoming barriers to meet these patients' special needs.
Physicians play a critical role in reaching diabetic patients in minority groups. These patients need professional help to modify their diets and exercise patterns, to follow drug regimens and blood-testing programs, to comply with treatment over the long term, and to pay for treatment. Closing the gap between the treatment levels afforded different groups of Americans is an enormous challenge, but it is one that is critical to the health of our population.
Aftercare↗
Stiffness and strength tailoring of a hip prosthesis made of advanced composite materials.
This work is concerned with the design of hip prostheses using advanced fiber reinforced composite materials. The major focus of the study is to evaluate how the stiffness and strength of composite hip prostheses can be affected by variations in ply orientation and stacking sequence for a selected manufacturing method. This investigation involved both analytical and experimental work. An analytical model was developed which consists of a stress analysis and a failure analysis. A finite element program was developed during the course of the investigation for analyzing stresses, strains, and deformations of composite stems with a simplified configuration. Failure and mode of failure were predicted by appropriately selected failure criteria. Experiments were also performed on T300/976 graphite/epoxy composites to verify the analysis and the computer calculations. Both testing and analysis accounted for the various combinations of in-plane and out-of-plane (torsion) loading that can act on the prosthetic hip. Simplified composite stems with a 120 layer thickness were fabricated and tested. An excellent agreement was found between the measured strain data and the numerical calculations. Using the program, parametric studies were performed. It was found that an optimal design of hip stems can be achieved by using advanced fiber-reinforced composite materials, but great care must be taken when selecting the appropriate ply orientation and stacking sequence for a chosen fabrication method.
Biocompatible Materials↗
The Georgia diabetic retinopathy screening study.
The diabetic retinopathy screening study represents a major collaborative effort of many volunteer groups interested in decreasing the risk of severe visual loss to Georgia citizens. Results of the present study have stimulated intense interest in screening more high risk persons, such as minorities, without the exclusion of whites. While age-related macular degeneration is the predominant cause of blindness in the U.S., diabetic retinopathy is a major new cause of blindness. With the continuation and completion of this study, we believe that many more of Georgia's citizens will seek ophthalmologic examinations and benefit from previous research regarding the use of laser photocoagulation and vitreoretinal surgery in preventing or reducing the risk of blindness. Since diabetic retinopathy requiring treatment can be present in patients with normal vision, such patients should obtain an annual dilated eye examination by an ophthalmologist. The value of statewide screening for undetected diabetic retinopathy, the determination of how and where to screen in order to give the most benefit to the potentially affected individuals and citizens of Georgia are only a few of the questions that may be answered when this study is completed. Moreover, to our knowledge this study is the first statewide screening for diabetic retinopathy in the United States.
Adult↗
Diabetic retinopathy.
Retinal involvement from diabetes mellitus is the leading cause of new blindness in the United States. Many diabetic patients, though they have perfect vision and no ocular complaints or symptoms, harbor retinal pathology capable of leading to severe loss of vision. Therefore, all medical personnel caring for the diabetic patient must recognize the importance of dilated pupil retinal examinations by an ophthalmologist or vitreoretinal surgeon. Lack of timely diagnosis and treatment is a major factor leading to blindness from diabetic retinopathy. On a more positive note, prompt laser treatment of diabetic retinopathy can reduce severe visual loss by more than 50%.
Diabetic Retinopathy↗
Heat transfer analysis of frictional heat dissipation during articulation of femoral implants.
Previous studies have shown the tendency for frictional heating to occur during articulation of total hip systems in vitro under simulated hip loading conditions. The magnitude of this heating is sufficient to accelerate wear, creep, and oxidation degradation of the UHMWPE bearing surface. It was shown that ceramic articulating systems generate less frictional heating than polished cobalt alloy against UHMWPE. This frictional heating is expected to occur primarily for younger, heavier, and more active patients. Thus, long-term performance of the articulating hip system in these patients may not be that predicted from current, body-temperature wear, creep, and degradation studies. Although the tendency to generate frictional heat has been observed only during in vitro simulated hip loading, a heat transfer analysis of this phenomenon is presented to evaluate the ability of the hip joint to dissipate such heating in vivo. Additional experiments were performed using controlled resistance heaters inside a cobalt femoral head to verify the calculated levels of frictional heat and to assess the heat dissipation under simulated in vivo conditions. The effect of blood perfusion on the effective thermal conductivity of the joint capsule is also discussed. The present study describes and analyzes the various heat dissipation mechanisms present both in vitro and in vivo during articulation of metal and ceramic hip systems. From these tests and analyses, it is concluded that frictional heating in the reconstructed hip cannot be effectively removed, and that degredative elevated temperature processes can be expected to occur in vivo to both the UHMWPE and adjacent tissue under extended periods of excessive patient activity. This is particularly true for metal cobalt alloy femoral heads articulating on UHMWPE versus ceramic heads which generate significantly lower levels of heat.
Alloys↗
Suicidal behaviour, social networks and psychiatric diagnosis.
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Humans↗
A study of HLA-A, B, DR and Bf bearing haplotypes derived from 304 families resident in the north west of England.
We report here haplotype frequencies for class I (HLA-A, B), class II (HLA-DR) and class III (Bf) gene products of the major histocompatibility complex (MHC) of man. As in other studies (Bertrams & Baur, 1979; Grange et al., 1981), we have chosen to document all families typed for HLA antigens and Bf phenotypes irrespective of ascertainment. We obtained 1,094 haplotypes from 304 families resident in the North West of England, of which 34.1% had been fully typed for HLA-A,B,DR and Bf polymorphisms. We have been able to find both positive and negative linkage disequilibria for two and three locus haplotypes and have listed the most commonly occurring four locus haplotypes. Our data confirms the position of the complement group between HLA-B and HLA-DR, and we have looked for evidence of segregation distortion of MHC haplotypes.
England↗
Wear, creep, and frictional heating of femoral implant articulating surfaces and the effect on long-term performance--Part II, Friction, heating, and torque.
In Part I, (J.A. Davidson and G. Schwartz, "Wear, creep, and frictional heating of femoral implant articulating surfaces and the effect on long-term performance--Part I, A review," J. Biomed. Mater. Res., 21, 000-000 (1987) it was shown that lubrication of the artificial hip joint was complex and that long-term performance is governed by the combined wear, creep, and to a lesser extent, oxidation degradation of the articulating materials. Importantly, it was shown that a tendency for heating exists during articulation in the hip joint and that elevated temperatures can increase the wear, creep, and oxidation degradation rate of UHMWPE. The present study was performed to examine closely the propensity to generate heat during articulation in a hip joint simulator. The systems investigated were polished Co-Cr-Mo alloy articulating against UHMWPE, polished alumina ceramic against UHMWPE, and polished alumina against itself. Frictional torque was also evaluated for each system at various levels of applied loads. A walking load history was used in both the frictional heating and torque tests. The majority of tests were performed with 5 mL of water lubricant. However, the effect of various concentrations of hyaluronic acid was also evaluated. Results showed frictional heating to occur in all three systems, reaching an equilibrium after roughly 30 min articulation time. Ceramic systems showed reduced levels of heating compared to the cobalt alloy-UHMWPE system. The level of frictional torque for each system ranked similar to their respective tendencies to generate heat. Hyaluronic acid had little effect, while dry conditions and the presence of small quantities of bone cement powder in water lubricant significantly increased frictional torque.
Hip Prosthesis↗
Wear, creep, and frictional heat of femoral implant articulating surfaces and the effect on long-term performance--Part I, A review.
Creep and wear of articulating reconstructed joints is a complex process, resulting in adverse tissue response, decreased range of motion, and eventual revision. As improvements are made in the design and surgical techniques of reconstructed joints, the long-term performance of the articulating system and materials becomes more important, particularly for younger, heavier, and more active patients. One aspect previously ignored in the long-term performance of articulating systems is the tendency for these systems to generate heat during articulation, particularly for extended periods of relatively strenuous activity. The present study reviews the various aspects of joint lubrication, friction, wear, and overall system performance. Local heating can increase the creep, wear, and oxidation degradation of UHMWPE, thus, specific attention is given to the effect that heat generation can have on long-term performance of these systems. Because of the complexity of this issue, the treatment of these various performance aspects is divided into two parts. The present part, Part I, reviews the various aspects of articulation performance. Part II presents results of friction, heating, and torque testing of various metal and ceramic hip systems. Criteria for frictional heating is also presented, along with discussion related to the various heat transfer mechanisms involved with heat dissipation.
Biomechanical Phenomena↗
The effect of HIPing on the fatigue and tensile strength of a case, porous-coated Co-Cr-Mo alloy.
The process required to sinter porous Co-Cr-Mo alloys results in the formation of substrate porosity through carbide dissolution. Since hot isostatic pressing (HIPing) has been shown to eliminate casting porosity in the Co-Cr-Mo alloy, it is possible that it may be equally effective on pores that are generated from the sintering operation. The effect that HIPing a porous-coated Co-Cr-Mo material has on the fatigue and tensile properties was investigated. Fatigue testing was performed on sintered materials as well as sintered and HIPed materials, both with and without a porous coating. Further, the effect of varying coating thickness on the resulting fatigue strength of sintered and HIPed materials was studied. Light microscopy was performed in order to define the microstructural changes brought about by the various thermal cycles. Scanning electron microscopy was utilized to define the crack initiation process. The fatigue strength of uncoated "as sintered" materials was found to be reduced by 34% relative to the "as cast" condition. The same material that was HIPed revealed a fatigue strength slightly lower than the "as cast" condition. It was found that porous coatings created preferential sites for fatigue crack initiation. However, the presence of the coating did not further reduce the fatigue strength of "as sintered" materials because of the already low strength created by the sintering operation. Materials that were sintered exhibited a lowering in both tensile strength and elongation to failure relative to the "as cast" condition. The HIPing of sintered materials improved both fatigue and tensile properties relative to the "as sintered" condition.
Biocompatible Materials↗
Spontaneous intracavitary left ventricular echocardiographic contrast effect resembling microbubbles.
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Coronary Circulation↗
An assessment of hostility in a population of adolescents.
In the course of an epidemiological survey of adolescents, the Hostility and Direction of Hostility Questionnaire was administered to 6,709 persons aged 13 to 18 years, representing 89% of secondary school students in Hobart, Tasmania. Extrapunitiveness was found to decrease substantially between the ages of 15 and 17 years in both sexes. Intropunitiveness also decreased, although to a lesser extent. Girls were less extrapunitive and more intropunitive than boys over the whole age range. These findings are discussed in relation to their clinical relevance and to the understanding of psychiatric disorder in adolescents.
Acting Out↗