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Biomedical subjects

S S Stevens

Publications and source records attributed to S S Stevens.

At least 19 recordsLinked to original sources
PubMed2000

Patients with depression are less likely to follow recommendations to reduce cardiac risk during recovery from a myocardial infarction.

BACKGROUND: Patients with depression are at greater risk of cardiac death in the first few months after a myocardial infarction (MI). This study was performed to determine whether depression affects adherence to recommendations intended to reduce the risk of cardiac events after an MI. METHODS: All consenting patients admitted to a university-affiliated teaching hospital during an 18-month period were interviewed 3 to 5 days following an acute MI using the Beck Depression Inventory to assess symptoms of depression and using the Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition, to determine the presence of major depression and/or dysthymia. Accessible survivors (n=204; 116 men and 88 women) were interviewed by telephone 4 months later using the Medical Outcomes Study Specific Adherence Scale to measure self-reported adherence to recommendations to modify cardiac risk. RESULTS: Patients who were found in the hospital to have symptoms of at least mild to moderate depression (Beck Depression Inventory score > or =10, n=35 [17.2%]) or to have major depression and/or dysthymia (n=31 [15.2%]) reported lower adherence to a low-fat diet, regular exercise, reducing stress, and increasing social support 4 months later. Those with major depression and/or dysthymia also reported taking medications as prescribed less often than those without major depression and/or dysthymia. Diabetic patients with major depression and/or dysthymia were less likely to follow a diet for patients with diabetes than diabetic patients without depression. CONCLUSIONS: Patients with depression following an acute MI are less likely to adhere to recommended behavior and lifestyle changes intended to reduce the risk of subsequent cardiac events. This finding could explain why depression in the hospital is related to long-term prognosis in patients recovering from an MI.

Aged↗
PubMed1999

Computer model of endochondral growth and ossification in long bones: biological and mechanobiological influences.

Endochondral growth and ossification, the processes by which cartilage increases in size and is replaced by bone, are affected by biological factors such as intrinsic genetic makeup and systemic chemical agents. In addition, these processes are affected by epigenetic mechanical factors: they may be accelerated in regions of intermittent high shear stress and decelerated in regions of intermittent high hydrostatic pressure. Previous models of bone development have not incorporated both biological and mechanobiological influences on endochondral growth and ossification. We have implemented a finite element analysis to model a developing bone rudiment from 8 weeks of gestational development to approximately 2 years after birth. As a function of time, we calculated a maturity index that reflects the progression of a region of cartilage through the endochondral ossification sequence of proliferation, hypertrophy, mineralization, and replacement by bone. We calculated a specific growth rate for each region of cartilage and estimated overall longitudinal growth of the rudiment. Regions of cartilage replaced by bone were remodeled. The results from the maturity index can be compared with distributions of proliferative, hypertrophic, and mineralized cartilage seen on histology at various stages in development. The results of the simulation predicted prenatal and postnatal developmental events, including formation of a secondary ossific nucleus, a layer of articular cartilage, and a growth plate. Our results demonstrate the necessity to include biological and mechanobiological influences when endochondral growth and ossification are considered.

Animals↗
PubMed1995

A biomechanical study of three wiring techniques for cerclage-plating.

Transverse fractures at the distal tip of a well-fixed femoral prosthesis are difficult to stabilize using plates and screws due to the presence of the underlying intramedullary stem. The attachment of plates using cerclage wires obviates the need for screws, but the stability provided by cerclage plating is a clinical concern. In this study we compared the mechanical performance of three wire-cerclage plating techniques: (a) simple cerclage (each wire wrapped around the bone and plate once); (b) double cerclage (each wire wrapped around the bone and plate twice); and (c) a new method that used small stainless steel inserts that fit into the plate holes and permit the direct coupling of the cerclage wires to the plate. To compare the performance of the three fixation constructs, synthetic femora were osteotomized, stabilized with a wire cerclage plating technique, and subjected to monotonic and cyclic loading using a Materials Testing System (Minneapolis, MN) servo-hydraulic testing system. The performance of each construct was evaluated using seven different mechanical parameters (four monotonic, three cyclic). Double cerclage performed significantly better than did simple cerclage for three of the seven mechanical parameters. The insert technique performed significantly better than did the simple and double cerclage techniques for all seven of the measured mechanical parameters. For both monotonic and cyclic loading, the use of inserts resulted in an improvement in fixation strength and stability in comparison with conventional simple and double cerclage plating techniques. The insert technique shows promise in the treatment of this difficult type of fracture at the distal tip of a well-fixed femoral prosthesis.

Biomechanical Phenomena↗
PubMedDate not supplied

Effect of early body image dissatisfaction on subsequent psychological and physical adjustment after disfiguring injury.

OBJECTIVE: The impact of body image dissatisfaction on quality of life after severe burn injury was investigated after controlling for other determinants of outcome (i.e., injury, distress, and preburn quality of life). METHODS: The postburn quality of life (2-months postdischarge) of groups with and without body image dissatisfaction was studied after controlling for preburn quality of life (measured 2-3 days postadmission). The patient population (N = 86) was 77.9% men, had an average total body surface area burned of 17.02%, and average full-thickness burn of 6.09%. Forty percent had facial injuries, 68.6% required surgery, most were injured by flame (39.5%), and 76.8% were employed. RESULTS: Multivariate analysis of covariance (covarying preburn level of Mental quality of life, facial injury, and size of burn) contrasting body image dissatisfaction groups found significantly lower psychosocial adjustment at 2-month follow-up in those with greater body image dissatisfaction (multivariate F = 3.61; p<.01). A second MANCOVA (covarying the preburn level of Physical quality of life and both facial injury and size of burn) found significantly lower physical functioning at 2-month follow-up in those with greater body image dissatisfaction (multivariate F = 2.78; p < .03). Adding two more covariates (depression and posttrauma distress) eliminated the effect of body image dissatisfaction on postburn Physical but not Mental adjustment. CONCLUSIONS: Body image dissatisfaction affects quality of life after severe burn injury. Distress moderates this impact on aspects of physical but not psychosocial health.

Adaptation, Psychological↗
PubMedDate not supplied

Mechanobiology in the development, maintenance, and degeneration of articular cartilage.

During skeletal development, the establishment of a layer of cartilage at the ends of long bones is intimately linked to the process of endochondral ossification. Previous in vivo studies and computer models suggest that mechanobiological factors can play a key role in modulating cartilage growth and ossification. Specifically, intermittent hydrostatic pressure is thought to maintain cartilage, and shear stresses encourage cartilage destruction and ossification. In the present investigation we examined the combined effects of hydrostatic pressure and shear stress--in the form of an osteogenic index--on the development of a layer of articular cartilage, using an idealized finite element computer model. The results of our analyses provide further support for the view that mechanobiological factors play a key role in regulating the distribution of cartilage thickness and in maintaining a stable cartilage layer at maturity. The model predicts that joints that experience higher contact pressures will have thicker cartilage layers. These predictions are consistent with observations of cartilage thickness in both humans and animals. Variations in articular mechanical load are predicted to modulate cartilage thickness. These results are consistent with the view that the mechanobiological factors responsible for the development of diarthrodial joints eventually lead to cartilage degeneration and osteoarthritis (OA) with aging.

Aging↗