Abstract: Heart rate variability (HRV) analysis involves examining the normal rhythmic fluctuations in heart rate using statistical indices (e.g. standard deviation, root mean square of the successive differences) or more complex spectral analytic techniques. Recently, Balocchi et al (2006) found that the ratio of the standard deviation of the r-r interval (SD) over the root mean squared of the successive differences (rMSSD), a simple statistical index, could be used as a surrogate for the low-to-high frequency ratio (LH/HF) typically calculated from the spectral estimates. We sought to extend this work by examining a patient population. Results indicate that the SD/rMSSD ratio is a good surrogate for the LF/HF ratio across multiple contexts in both patients and normal healthy controls.

Abstract: While 5-fluorouracil continues to be the chemotherapeutic gold-standard for the treatment of colon cancer, the side effects of 5-FU are numerous due to its ability to attack both healthy and cancerous cells. However, research continues to provide positive findings in regards to antioxidants and their success in deterring certain disease processes, especially cancer. Epigallocatechin-3-gallate (EGCG), the most abundant catechin found in green tea, is a valuable scavenger of reactive oxygen species in vitro as well as in vivo. Thymoquinone (TQ), the major active component of Nigella sativa (black seed), is also known for its powerful scavenger abilities as an inhibitor of oxidative stress and has been utilized in the Middle East for centuries because of its capability to heal many different diseases. Therefore, the objective of this study was to investigate the role of sustained drug delivery of TQ, EGCG, and 5-FU on the metabolic activity as well as structural changes in the SW-626 human colon cancer cell line in culture. Results of this study indicate a sustained drug delivery of EGCG and TQ demonstrated significant (p < 0 .01) cellular destruction and interference of cellular metabolic functions of SW-626 human colon cancer cells, which was comparable to SW-626 cells exposed to sustained drug delivery of 5-FU. Furthermore, MDA, glutathione, and nitric oxide all revealed significant alterations (p<0.05) as early as 24 hours. Morphologically, cellular changes occurred after exposure to TQ and EGCG at 24 hours which were also comparable to cells exposed to 5-FU. The delivery of the natural agents may offer a safe alternative treatment in for colon cancer.

Abstract: Preventing cartilage injury is important in minimizing the long term debilitating effects of osteoarthritis. Accurate subfracture injury prediction must take into account the possible effects that freeze thaw cycles may have on the mechanical properties of cartilage tissue. This paper addresses this concern with matched pair testing of various low temperature storage techniques against fresh control groups. Ten matched pairs of bovine knees were used for testing, five pairs for a -20 degrees C slow freeze cycle and five pairs for a -80 degres C flash freeze cycle. Controlled mechanical indention tests were performed on the bovine articular cartilage-on-bone specimens to compare stiffness, peak stress, and loading energy of the cartilage. Findings showed that a slow freeze cycle or flash freeze cycle caused cartilage stiffness to decrease by 37% and 31% respectively, which was statistically significant in both cases (p< or =0.01). Compressive stress at this strain was also lowered by 31% with a slow freezing process (p=0.03). A similar trend was observed with compressive stress in the flash freeze specimens, although the 37% decrease was not found to be statistically significant (p=0.08). These results may be indicative of a weakened extracellular matrix structure caused by the freeze-thaw process. It is still unclear whether these changes in mechanical properties will result in a change in injury susceptibility for articular cartilage.

Abstract: Antioxidants are substances that may protect cells from the damage caused by unstable molecules known as free radicals. Although many subsequent studies have been done on antioxidants and cancer, studies that specifically assess the relation with ovarian cancer are very limited. The goal of this study was to establish alternative treatment methodologies in the treatment of the aggressive behavioral activity of ovarian carcinogenesis through investigation of the effects of antioxidants. The specific aims of this study were to analyze the effect of low and high doses of EGCG, Selenium, and Thymoquinone on ES-2 ovarian cell line at 24, 48, and 72 hours as determined by morphology, cell count, and biochemical markers. During phase I, experimental groups were administered physiological doses of specific antioxidants. Upon administration of epigallecatechin-3-gallate, selenium, and thymoquinone, selenium exhibited the largest effect on biochemical assays in the study. Analysis of collected data showed that antioxidants suppress metabolic activity, alter behavioral responses, and cause molecular damage. However, it has not been shown that the antioxidants utilized result in total eradication of ES-2 ovarian cancer cell line.

Abstract: The objective of the present investigation is to determine localized brains strains in lateral impact using finite element modeling and evaluate the role of the falx. A two-dimensional finite element model was developed and validated with experimental data from literature. Motions and strains from the stress analysis matched well with experimental results. A parametric study was conducted by introducing flexible falx in the finite element model. For the model with the rigid falx, high strains were concentrated in the corpus callosum, whereas for the model with the flexible falx, high strains extended into the cerebral vertex. These preliminary findings indicate that the flexibility of falx has an effect on regional brain strains in lateral impact.

Abstract: This paper describes the research, development, and implementation of an electrooculogram-controlled wheelchair. This system was designed specifically to fit the demands of users with limited use of their arms and legs. By monitoring ocular bio-electrical signals, this system allows the user to steer the wheelchair using only eye movements. The first generation prototype described here used a "sip and puff" unit for overall control of the system, allowing the user to change modes of operation using only his/her breath. Finally, an ultra-sonic rangefinder was added to provide an extra measure of safety, alerting the user to sudden changes in grade. This is part of an ongoing project to allow greater independence for those with special needs.

Abstract: Over 2 million eye injuries occur each year in the United States as a result of trauma. In order to show the injury potential of objects such as BB guns, paintball guns, automotive airbag systems, and other consumer products, researchers have frequently tested enucleated eyes which have been placed in simulated orbits and held in place with a 10% gelatin solution. The purpose of this study is to perform biomechanical impact tests using both in-situ human eyes and human eyes mounted in simulated orbits, to compare the responses of both. A total of 12 dynamic eye impact tests were performed to develop force-deflection characteristics of the human eye in-situ, determine the effects that the extraocular muscles have on the response of the eye to dynamic impacts, and to characterize the force-deflection response of eyes supported with a gelatin solution within a simulated orbit. It was found that force-deflection corridors are similar with the extraocular muscles left intact or transected. Impact tests performed on eyes mounted in simulated orbits made of polycarbonate and filled with a 10% gelatin solution showed force-deflection responses that matched those of the in-situ eye impact tests. It is concluded that the use of simulated orbits to perform eye impact tests offers the appropriate boundary conditions to represent the in-situ human eye under dynamic eye impact events.

Abstract: The bone morphogenetic proteins (BMPs) carry a crucial role in bone formation and bone healing. Previous studies have identified the osteoinductive capabilities of demineralized bone matrix (DBM) and the individual factor osteogenic protein-1 (OP-1), also known as BMP-7. The purpose of this study is to identify the short-term healing effects of targeted drug delivery of demineralized bone matrix and osteogenic protein-1 following bony trauma in terms of mechanical strength and histological changes. Animals in Group 1 acted as the control and Group 2 received a unicortical drill defect and placement of a calcined tricalcium phosphate lysine (TCPL) capsule containing antibiotic (sham). Group 3 and 4 animals had a created drill defect and received a TCPL carrier containing antibiotic along with DBM or OP-1, respectively. After 2 weeks post-implantation, animals in each group were sacrificed before the retrieval of the bone. The femurs were analyzed biomechanically for return of strength and histologically for bone growth. The average rupture strength for the femurs of the control group was shown to be significantly higher than all other groups (p<0.001 compared to sham, DBM, and OP-1). There was no significant difference between the two treatment groups (p=0.984) and there was no significant difference between the sham and DBM or OP-1 treated groups (p=0.908 and p=0.991, respectively). Analysis of the gross specimens showed minimal signs of bone regeneration at the defect site for both DBM and OP-l treated femurs when compared to the shams. Histological sections did show increased cortical thickness and new bone formation in the DBM and OP-1 groups, with the OP-1 group appearing slightly thicker. Despite the histological changes seen, the results indicate that there is no significant improvement in mechanical strength during the early stages of healing regardless of treatment.

Abstract: Electromyogram (EMG)-based and eye gaze tracking (EGT)-based hands-free cursor control input systems have been developed in the past as independent forms of cursor control Each form of control possesses its own advantages and disadvantages in terms of usability This paper presents a novel form of hands-free cursor control that integrates these two inputs in order to provide the user with the ability to manipulate the cursor more efficiently than the individual input systems operating in isolation An experiment was conducted to compare the performance of this new EMG/EGT input system to EGT and mouse input systems in point-and-click trials The results showed that while the EMG/EGT system was slower than the EGT system and the mouse, it produced a significantly smaller error rate than EGT input alone and therefore, EMG/EGT input could be considered to be a more usable form of hands-free cursor control when compared to EGT input

Abstract: Antioxidants are entities that play a vital role in protecting cells from free radical damage, which is implicated in cancer development. A detailed literature review on nutritional supplementation and cancer has demonstrated that antioxidants may be beneficial in preventing prostate cancer development. A reduced incidence of prostate cancer has been associated with high consumptions of antioxidants. The goal of this study was to utilize the ceramic drug delivery system to evaluate the behavior and response of LNCaP prostate cells upon treatment with epigallocatechin-3-gallate (EGCG), thymoquinone (TQ), and tannic acid (TA). After treatment with the various antioxidants, the groups were evaluated after 24, 48, and 72 hours of incubation. After all phases of incubation, groups treated with EGCG +TCP demonstrated the greatest reduction in cell count as well as the most cell membrane damage according to malondialdehyde (MDA) levels. In comparison to the control group, all groups demonstrated reductions in cell growth and decreased PSA levels that were significant according to one way analysis of variance (P < 0.001). Findings from this study revealed that sustained delivery with antioxidants may be a means of treating prostate cancer both safely as well as effectively. Future studies are needed to test the mechanisms behind these reactions.

Abstract: Computational models are used to investigate placental abruption in motor vehicle crashes, which is the leading cause of traumatic fetal injury mortality in the United States. Material parameters for computational modeling of pregnant occupant kinematics come from early research on placenta tissue at quasi-static loading rates. The purpose of this research is to develop a methodology for using cryogenic grips to test placenta specimens in uniaxial tension at a rate normally seen in a motor vehicle crash. For dynamic testing of placental tissue, implementing and adapting a cryogenic grip mechanism provides the ability to grip the tissue throughout the thickness and eliminates potential slipping of the tissue in the grip during the dynamic test. The validation for using the cryogenic grips is presented with video images of a typical test event showing the tissue failing in the active area. Additionally, local and global strain measures are compared to confirm the tissue strain is similar throughout the specimen. The cryogenic grips provide a low-cost and effective method of gripping and pulling a thick soft tissue in uniaxial tension. As a result, these methods can be used to acquire the material properties of placenta tissue loaded at a dynamic rate to apply in a computational pregnant model.

Abstract: Degenerative disc disease is a leading source of pain as well as increased health care costs in the United States, and research efforts into understanding the pathophysiology of this disease are necessary for the development of new management strategies. Addition of growth factors to stimulate chondrocyte development are on the horizon as new treatment modalities for degenerative disc disease, but increasing growth factor concentrations in the body may have adverse affects on vital organs. The objective of this study was to investigate the use of sustained delivery of insulin-like growth factor-1 (IGF-1) for treatment of degenerative discs using the adult male rat as a model. The results showed increased chondrocyte proliferation and decreased apoptosis at the traumatized disc after 28 days. Analysis of the vital organs revealed slight increases in kidney wet weights, and closer histomorphometric evaluation of the tissue revealed changes in the proximal tubules. Further investigation to evaluate the potential physiological or pathophysioloigcal effects of the growth factors at the organ levels is warranted before use as therapeutic agent to treat degenerative disc disease.

Abstract: Tumor growth and abnormal cell survival were shown to be associated with a number of cellular metabolic abnormalities revealed by impaired oral glucose tolerance, depressed lipoprotein lipase activity leading to hypertriglyceridemia, and changes in amino acid profile as evidenced by increased plasma free tryptophan levels in patients with breast, lung, colon, stomach, and other cancers from various origins. The above findings seem to relate to or indicate a shift to non-oxidative metabolic pathways in cancer. In contrast to normal cells, cancer cells may lose the ability to utilize aerobic respiration due to either defective mitochondria or hypoxia within the tumor microenvironments. Glucose was shown to be the major energy source in cancer cells where it utilizes aerobic /anaerobic glycolysis with the resultant lactic acid formation. The role of energetic modulations and use of glycolytic inhibitors on cancer / normal cell survival is not clearly established in the literature. Therefore, the purpose of this study was to evaluate six glycolytic inhibitors namely, sodium ascorbate, oxalic acid, oxaloacetic acid, sodium citrate, fructose diphosphate (FDP) and sodium bicarbonate at microM concentrations on growing A549 (lung cancer) and MRC-5 (normal; human lung fibroblast) cell lines with the objective of determining their influence on cell survival. Exposed and non-exposed cells were tested with phase contrast micro scanning, survival / death and metabolic activity trends through MTT-assays, as well as death end-point determinations by testing re-growth on complete media. Results showed that oxalic acid and oxaloacetic acid both influenced the pH of the medium and resulted in differential massive cell debris within the exposure period. Sodium ascorbate, sodium citrate, sodium bicarbonate and FDP did not cause pH changes; however, they caused detectable cell disfigurement and loss of metabolic activity and survival/ death end points with the resultant death of the A549 cell line. MRC-5 cells were differentially unaffected by exposure to sodium ascorbate, sodium citrate, sodium bicarbonate, and oxaloacxetic acid, underwent complete recovery and remained both attached and healthy for 6 weeks upon subculture when transferred to a new complete medium. Oxalic acid did not show differential modulation with the consequent loss of survival and death of the MRC-5 cell line. These studies show the potential for exploiting cellular metabolic differences in cancer control.

Abstract: The objective of this study was to perform a dynamic biomechanical analysis of football neck collars in order to determine their effect on head and neck loading. A total of 48 tests were performed comparing the Cowboy Collar, Bullock Collar, and the Kerr Collar. A control and each collar was tested at two speeds (5 m/s and 7 m/s), three impact locations (front, top, and side of the helmet), and two shoulder pad positions (normal and raised). This paper specifically analyzes the load limiting capabilities of these collars during an impact to the side of the helmet. A 50 percentile male Hybrid III dummy was equipped with a helmet, shoulder pads, and the various neck collars mentioned. The dummy was instrumented with tri-axial accelerometers at the CG of the head. Angular rate sensors were used in the head and chest. In addition, both the upper and lower neck were instrumented with load cells. The helmet was struck with a pneumatic linear impactor to provoke rotation of the head and neck. With the side impact location, the Kerr Collar substantially reduced lower neck moment. These reductions in loads correlate with the degree to which each collar restricted the motion of the head and neck.

Abstract: Diffusion tensor imaging (DTI) has been successfully used to image the human brain and spinal cord, although there is still controversy as to which tensor-derived diffusion indices produce the greatest contrast and provide the best anatomical representation of gray and white matter within the spinal cord. The aim of this study was to determine the best diffusion indices for use in the spinal cord using the detectability index, ROC analysis, and opinion data in the form of a survey. DTI of the entire spinal cord (C1-L1) was performed on five neurologically intact human subjects at 1.5-T. Eigenvalues, mean diffusivity (MD), fractional anisotropy (FA), volume ratio (VR), relative anisotropy (RA) and measured anisotropy (deviation of eigenvalues with respect to mean diffusivity) were calculated from the diffusion tensor. ROIs for white matter (WM) and gray matter (GM) were extracted using FA colormaps. The detectability index indicated FA and VR provided significant contrast between GM and WM. Since the FA was used for classification, results appeared to be biased toward FA and indices highly correlated with FA. ROC analysis illustrated similar results, but area under the ROC curve did not show statistical significance between indices. The survey indicated that the deviation of the primary eigenvalue with respect to mean diffusivity (MA1) was significantly better than all other indices at representing underlying spinal cord morphology. This is consistent with previous results showing lack of detail in ventral gray matter regions using the FA. Results indicate FA and MA1 provide the highest contrast and most accurate representation of underlying morphology, respectively.

Abstract: Demineralized bone matrix (DBM) has been shown to possess osteoinductive capability and one of the specific bone morphogenetic proteins (BMPs) found within DBM that has been attributed with this osteoinductive ability is BMP-7, also known as osteogenic protein-1 (OP-1). The specific aims of this study were (1) to compare the treatment of segmental bone defects with OP-l and DBM in a rat femur model and (2) to determine the effects of the two treatments given at high and low doses via sustained release drug delivery. Animals in Group 1 acted as the control and Group 2 had a created segmental defect with plating and placement of a calcined tricalcium phosphate lysine (TCPL) capsule containing antibiotic (sham). Group 3 and 4 animals had a created segmental defect and received a TCPL carrier containing antibiotic along with DBM or OP-1, respectively. After 4 weeks post-implantation, animals were sacrificed before the retrieval of the bone. The femora were analyzed radiographically and histologically for bone growth. Analysis of the gross specimens showed considerable bone regeneration at low and high doses for both DBM and OP-1 when compared to the shams. At low levels bone regeneration between DBM and OP-1 was very similar. However, at high doses, OP-1 was shown to cause bone overgrowth with a greater curvature and an increased thickness of the distal and proximal ends of the femur. The stained slides showed the defects treated with DBM and OP-1 to be bridged with lamellar and woven bone that was continuous with the original bone. Histologically, the experimental femora demonstrated natural remodeling processes with new osteons and angiogenesis.

Abstract: In present study, an anatomically accurate, validated in the entirenonlinear domain, three-dimensional finite elementmodel was used to investigate the biomechanical effects of facetectomy on the stability of the human lumbosacral spine. Bilateral total facetectomy was simulated at L4-L5 and L5-S1 levels. Flexion, extension, and axial torsion were applied using pure moment protocols. Total facetectomy increased spinal instability significantly under extension and axial rotation and not under flexion.

Abstract: In response to genotoxic agents, normal tissue cells are instructed by p53 either to perform DNA repair or to undergo apoptosis. Studies showed that chemo and/or radiotherapy damage both normal and cancerous cells indiscriminately. To this end, severe side effects inflicted by p53 activation in normal tissues, would possibly be abrogated by p53 inhibition. Pifithrin-alpha (PFT-alpha) is a reversible inhibitor of p53-mediated apoptosis, p53-dependent gene transcription, as well as down stream responsive gene function. The objective of this study was (1) to evaluate PFT-alpha for differential cellular protection in response to arsenic trioxide and cadmium chloride exposure of normal and neoplastic cells, and (2) to evaluate the transcriptional activation of p53 and p53-responsive genes in rat liver cells and HepG2 carcinoma cell line. Cell survival was detected by fluorescein diacetate (FDA) and fluorospectroscopy. Mean LC50 and (SD) for HepG2 cells following exposure to arsenic were 13.7 (+/-1.0) microg/ml with PFT- alpha and 13.4 (+/- 0.5) microg/ml without PFT-alpha (p>0.05). For rat liver cells it was 670 (+/- 8.15) microg/ml with and 573.15 (+/-1.0) microg/ml without PFT-alphha (p 0.5). The results revealed significant differences from controls only upon exposure of rat liver cells to arsenic trioxide in presence of PFT-alpha. PFT-alpha inhibited the transactivation of p53 in rat liver cells and resulted in repression of Bcl2, PCNA, MDM2, Cyclin G and P21 genes by arsenic trioxide. HepG2 cells exposed to arsenic trioxide and PFT-alpha showed expression of only the P53 and PCNA genes. We conclude that PFT-alpha exhibits cytoprotective effect, modifies the detrimental influences of known genotoxic agents in normal cells and has the potential for use as an adjuvant to cancer therapy.

Abstract: The relationship between diffuse brain injury (DBI) occurrence and impact biomechanics is well documented. Previous studies attempted to develop injury thresholds based on various biomechanical parameters and have demonstrated inconsistent results. The spectral nature of DBI requires robust metrics capable of predicting injury occurrence and severity. In the present study impact biomechanics reported previously were correlated to rat unconsciousness time. Significant correlation was identified in three parameters including square angular velocity, change in rotational velocity, and Head Impact Power. Results suggest rotational loading of the rat head has similar correlates to the human condition. In addition, certain biomechanical parameters demonstrate capacity for predicting DBI severity.

Abstract: The path of the carotid artery and its branches through the neck is characterized through an analysis of non-contrast computed tomography (CT) scans. The distance from the vessel wall of the carotid arteries to the skin and vertebral bodies are recorded from the level of the 2nd cervical vertebrae (C2) to the 6th cervical vertebrae (C6). A total of seven individuals were included in the study. The common carotid artery exhibited the closest average distance to the skin (23.5 +/- 6.9 mm) whereas the internal carotid artery exhibited the closest average distance to the vertebral body (7.36 +/- 3.8 mm, measured to the transverse process). This study provides morphological validation data towards the development of a regional-level finite element model of the neck and may also be used for the design of biomechanical experiments for the study of carotid artery injury.

Abstract: The purpose of this study was to establish a semi-automated method for determining the extent of damage to the spleen from computed tomography (CT) scans. This method uses a software program to evaluate the differences in splenic tissue based on Hounsfield units. In this study, five patients that suffered blunt abdominal injury with splenic injury from a motor vehicle crash were evaluated. First, a trained radiologist identified the damaged areas of the spleens of each patient. From this assessment a semi-automated method of assessment was created using a wide range of Hounsfield units to create a mask of the entire spleen. The contrast range of the injured tissue, consisting of laceration, hematoma, contusion, or other injury was also identified. A percent injured tissue was created by dividing the injured tissue mask volume by the total spleen mask volume. The results demonstrated as the AIS grade increased, the percent injury volume increased. In conclusion, it is possible to calculate injury volumes from abdominal CT scans with minimal user inputs. Language: en

Abstract: Bone grafts are used to treat various disorders, including delayed union and nonunion of fractures, congenital pseudoarthrosis, and osseous defects from trauma, infection, and tumors. Bone graft substitutes provide surgeons a wide range of materials, structures, and potential delivery systems to use in bone grafting procedures. In addition, the materials may be used as scaffolds to deliver patient derived bone cells. The goal of this study was to seed MG63 osteoblast cells onto three different material constructs--TCP, ZnCaP and ProOsteon--and to compare the growth characteristics of the cells in reaction to the materials. Cellular response to the material was evident as early as 24 hours following the addition of cells onto the constructs. Cells were found adjacent to and along the TCP and ZnCaP carrier, while in the ProOsteon group, the cells appeared non-adhered and more round than spindle shaped. Type I collagen synthesis was highly evident in the TCP and ZnCaP groups at the end of 16 days, whereas little cellular activity was noted around the ProOsteon construct. The overall results suggest a favorable environment for bone cell growth on TCP and ZnCaP materials. The materials may serve as delivery systems for cells in tissue engineering fields in the future.

Abstract: A comparison between two stochastic optimization techniques, adaptive simulated annealing (ASA) and the multi-island genetic algorithm (MIGA) is conducted to investigate which is the more attractive option for tuning a finite element model to match experimental data. The study probes the repeatability, robustness and sensitivity of each algorithm. While both algorithms produced FE results within one standard deviation of the experimental mean, the ASA approach proved more effective than the MIGA. The ASA algorithm demonstrated better repeatability after 1000 trials, with an average parameter value change of 9%. The ASA algorithm also probed a wider range of the solution space and produced results with significantly lower sum-of-squares error than the MIGA (t-test, one tailed, p < 0.001).

Abstract: This paper discusses methods that will be used to experimentally determine the limitations of transdermal ethanol alcohol sensors when used on human subjects. Transdermal ethanol sensors are used to measure the concentration of ethanol emitted by the surface of the skin. The maximum concentration of ethanol in the skin is proportional to the concentration of ethanol in the blood stream but is offset temporally because of the diffusion delay intrinsic to body tissue. Methods to evaluate different model ethanol sensors are discussed as well as the development and function of a portable, transdermal ethanol sensing device suitable for measuring ethanol concentration on the palm of a test subject's hand. In addition, the designs of several experiments are described to test the functional limitations of transdermal ethanol sensors in practical use settings. These experiments include tests to correlate a subject's peak blood and skin ethanol concentrations and experimental determination of different false positive sources.

Abstract: We have developed an electronic safety support system to assist in the care of elderly people. The system uses a low power mobile phone (PHS) and a server computer. The PHS is carried by the subjects, and their location is identified within 100 m from the PHS antenna ID. The caregiver sets the patient's movement area with specialized computer software. When the patient leaves the area, the system automatically informs the caregiver via voice mode and sends the patient's location map by e-mail. The caregiver can monitor the current location and prior movement by the map displayed on server computer.

Abstract: Placental abruption accounts for 50% to 70% of fetal losses in motor vehicle crashes. Since automobile crashes are the leading cause of traumatic fetal injury mortality in the United States, research of this injury mechanism is important. Before research can adequately evaluate current and future restraint designs, a detailed model of the pregnant uterine tissues is necessary. The purpose of this study is to develop a methodology for testing the pregnant uterus in biaxial tension at a rate normally seen in a motor vehicle crash. Since the majority of previous biaxial work has established methods for quasi-static testing, this paper combines previous research and new methods to develop a custom designed system to strain the tissue at a dynamic rate. Load cells and optical markers are used for calculating stress strain curves of the perpendicular loading axes. Results for this methodology show images of a tissue specimen loaded and a finite verification of the optical strain measurement. The biaxial test system dynamically pulls the tissue to failure with synchronous motion of four tissue grips that are rigidly coupled to the tissue specimen. The test device models in situ loading conditions of the pregnant uterus and overcomes previous limitations of biaxial testing. A non-contact method of measuring strains combined with data reduction to resolve the stresses in two directions provides the information necessary to develop a three dimensional constitutive model of the material. Moreover, future research can apply this method to other soft tissues with similar in situ loading conditions. Language: en

Abstract: The object of this study was to develop a quasi-linear viscoelastic model for the iliofemoral and ischiofemoral hip ligaments. In order to accomplish this, a total of 56 axial tension tests were performed on 8 bone-ligament-bone specimens prepared from 4 fresh frozen male cadavers. Each specimen went through a battery of 7 tests including a series of step-and-hold tests and load-and-unload ramp tests. The bone-ligament-bone specimens were situated so that the load from a servo-hydraulic Material Testing System would be applied on the long axis of each ligament. The reduced relaxation data was fit to a two exponential damping function while the instantaneous elastic response was fit to a power-law function. These two constituents were then combined to create a single constitutive equation for each ligament. The quasi-linear viscoelastic model presented in this study can be used to improve the biofidelity of computational models of the human hip.

Abstract: Wear debris generated from total joint arthroplasty may elicit a granulomatous and inflammatory response and has also been implicated in the development of osteolysis. Technical difficulty in retrieval and isolation of wear material from tissues has hindered the study of their physicochemical properties. The purpose of this study was to retrieve and analyze metallic wear debris from periprosthetic tissue obtained during revision arthroplasty. Tissue from six osteoarthritic patients was obtained during revision arthroplasty. The tissue was minced and then heated in a sodium dodecyl sulfate solution. Undigested tissue was incubated sequentially with papain and pepsin solutions. Metallic wear debris retrieved from the digestion procedure was analyzed by scanning electron microscopy. Wear fragments were seen as irregularly shaped flakes, splinters and polyhedral structures ranging from 1 to 100 microns in size. These structures appeared to be free from non-metallic surface-adherent material. Energy dispersion spectroscopy verified the presence of cobalt, chrome and molybdenum which comprised the implant alloy. Fatigue lines were observed on the surface suggesting brittle wear. Our technique for isolating metallic fragments facilitates the retrieval and preparation of wear debris for analysis of physicochemical properties and how wear debris interacts with cellular elements in surrounding tissue.

Abstract: This paper examines the visual stimuli, recording methods, and cell identification techniques used to gather visual information from the household fly, Musca domestica. Visual information from the pre-processing layers of the household fly are explored in order to advance a biomimetic sensor that requires analog pre-processing prior to computational algorithms that mimic the higher level visual processing that occurs in the deeper optic lobes of the fly. The fly is stimulated with a series of primitives created by a green laser stimulus. The primitives are a line, bar, and a spot. The recorded neuron is then identified through cell staining techniques and microscope visualization. With the availability of numerous anatomical drawings on the structure of the fly's optic lobes, it will be easy to identify the stained neuron. With this information models will be constructed to determine the processing performed by the lamina monopolar neurons and their relationship to one another.