Regulation of Bone Marrow Stem Cells through Oscillatory Shear Stresses - A Heart Valve Tissue Engineering Perspective

Heart valve disease occurs in adults as well as in pediatric population due to age-related changes, rheumatic fever, infection or congenital condition. Current treatment options are limited to mechanical heart valve (MHV) or bio-prosthetic heart valve (BHV) replacements. Lifelong anti-coagulant medication in case of MHV and calcification, durability in case of BHV are major setbacks for both treatments. Lack of somatic growth of these implants require multiple surgical interventions in case of pediatric patients. Advent of stem cell research and regenerative therapy propose an alternative and potential tissue engineered heart valves (TEHV) treatment approach to treat this life threatening condition. TEHV has the potential to promote tissue growth by replacing and regenerating a functional native valve. Hemodynamics play a crucial role in heart valve tissue formation and sustained performance. The focus of this study was to understand the role of physiological shear stress and flexure effects on de novo HV tissue formation as well as resulting gene and protein expression. A bioreactor system was used to generate physiological shear stress and cyclic flexure. Human bone marrow mesenchymal stem cell derived tissue constructs were exposed to native valve-like physiological condition. Responses of these tissue constructs to the valve-relevant stress states along with gene and protein expression were investigated after 22 days of tissue culture. We conclude that the combination of steady flow and cyclic flexure helps support engineered tissue formation by the co-existence of both OSS and appreciable shear stress magnitudes, and potentially augment valvular gene and protein expression when both parameters are in the physiological range.

Regulation of bone marrow stem cells through oscillatory shear stresses - A heart valve tissue engineering perspective

Heart valve disease occurs in adults as well as in pediatric population due to age-related changes, rheumatic fever, infection or congenital condition. Current treatment options are limited to mechanical heart valve (MHV) or bio-prosthetic heart valve (BHV) replacements. Lifelong anti-coagulant medication in case of MHV and calcification, durability in case of BHV are major setbacks for both treatments. Lack of somatic growth of these implants require multiple surgical interventions in case of pediatric patients. Advent of stem cell research and regenerative therapy propose an alternative and potential tissue engineered heart valves (TEHV) treatment approach to treat this life threatening condition. TEHV has the potential to promote tissue growth by replacing and regenerating a functional native valve. Hemodynamics play a crucial role in heart valve tissue formation and sustained performance. The focus of this study was to understand the role of physiological shear stress and flexure effects on de novo HV tissue formation as well as resulting gene and protein expression. A bioreactor system was used to generate physiological shear stress and cyclic flexure. Human bone marrow mesenchymal stem cell derived tissue constructs were exposed to native valve-like physiological condition. Responses of these tissue constructs to the valve-relevant stress states along with gene and protein expression were investigated after 22 days of tissue culture. We conclude that the combination of steady flow and cyclic flexure helps support engineered tissue formation by the co-existence of both OSS and appreciable shear stress magnitudes, and potentially augment valvular gene and protein expression when both parameters are in the physiological range. ^

What individuals with rheumatic diseases know about the Americans with Disabilities Act: A survey

Individuals with rheumatic diseases often have disabilities which limit one or more major life activity. Common disabilities among individuals with rheumatic illnesses such as chronic pain, hand deformities, and fatigue may be hidden. With a hidden disability, an individual may be unaware that he or she could qualify as disabled under the Americans with Disabilities Act (ADA). The ADA provides for reasonable accommodation for qualified individuals with disability related limitations. Accommodations under the ADA are designed to remove barriers preventing full participation in society, including employment, for individuals with disability related limitations.^ The primary objective of this study was to determine the knowledge level of individuals with rheumatic conditions about the Americans with Disabilities Act (ADA). One hundred and seven individuals with various rheumatic illnesses participated in this survey. The forty question survey included questions about type of rheumatic condition, employment, pain level, and knowledge of the ADA. Results of this study show that individuals with rheumatic conditions are more familiar with general information about the ADA and less familiar with specific information. The longer an individual has been diagnosed with a rheumatic condition the more he or she knows about the ADA. Common sources of information about the ADA are media and networking with others, rather than health care professionals. The recommendation for occupational therapists is to include education about the ADA as an integral component of treatment for all individuals with rheumatic conditions. ^

Effects of nursing interventions for fever in acutely ill adults

Fever has both beneficial and detrimental effects. There is evidence that antipyretics and physical cooling methods, when used in combination, are more effective than antipyretics alone. This randomized controlled study examined 45 acutely ill adults with fever ${\ge}102.5\sp\circ\rm F$ where three nursing interventions were used. Group I received acetaminophen 650 mgs., Group II received acetaminophen 650 mgs. and tepid sponging, and Group III received acetaminophen 650 mgs. and hypothermia blanket. The purpose of this study was to evaluate which nursing intervention reduced temperature most effectively with respect to eight biobehavioral variables. Research hypotheses were tested statistically using the chi-square test and repeated measures analysis of variance. The study found statistically significant results for fever reduction overall, but no difference for the groups. Therefore, we suggest that acetaminophen alone be used in the treatment of fever in order to decrease cost, nursing time, and increase patient comfort. ^

Fever, methods of fever management, and caretakers' perceptions of pediatric after-hour telephone triage and advice services for children between the ages of twelve months and three years with fever

Despite the frequency with which fevers occur in children ages 1–3 years, lack of knowledge and understanding about the implications of fever and methods of fever management often results in anxiety among caretakers, sometimes prompting them to seek help at nearby emergency departments. Caretakers often look to health care professionals for advice and guidance over the telephone. The purpose of this study was to investigate caretakers' knowledge of the implications of fever, methods of fever management, perceptions of pediatric telephone triage and advice services regarding fever, and the effectiveness of after hour telephone triage directed toward improving the caretakers' ability to manage their child's fever at home. Pre-triage questionnaires were completed by 72 caretakers over the telephone before the triage encounter. Twenty-two of those same caretakers whose children were triaged using the fever guideline completed and returned the mailed post-triage questionnaire. Descriptive statistics were used to analyze responses for the larger pre-intervention group and describe comparisons for the pre and post-triage responses in the smaller sample subset (n = 22). ^

The endocrine basis for reproductive life-history trade-offs during the previtellogenic resting stage in the yellow fever mosquito, Aedes Aegypti

Juvenile hormone (JH) is the central hormonal regulator of life-history trade-offs in many insects. In Aedes aegypti, JH regulates reproductive development after emergence. Little is known about JH's physiological functions after reproductive development is complete or JH's role in mediating life-history trade-offs. By examining the effect of hormones, nutrition, and mating on ovarian physiology during the previtellogenic resting stage, critical roles were determined for these factors in mediating life-history trade-offs and reproductive output. The extent of follicular resorption during the previtellogenic resting stage is dependent on nutritional quality. Feeding females a low quality diet during the resting stage causes the rate of follicular resorption to increase and reproductive output to decrease. Conversely, feeding females a high quality diet causes resorption to remain low. The extent of resorption can be increased by separating the ovaries from a source of JH or decreased by exogenous application of methoprene. Active caspases were localized to resorbing follicles indicating that an apoptosis-like mechanism participates in follicular resorption. Accumulations of neutral lipids and the accumulation of mRNA's integral to endocytosis and oocyte development such as the vitellogenin receptor (AaVgR), lipophorin receptor (AaLpRov), heavy-chain clathrin (AaCHC), and ribosomal protein L32 (rpL32) were also examined under various nutritional and hormonal conditions. The abundance of mRNA's and neutral lipid content increased within the previtellogenic ovary as mosquitoes were offered increasing sucrose concentrations or were treated with methoprene. These same nutritional and hormonal manipulations altered the extent of resorption after a blood meal indicating that the fate of follicles and overall fecundity depends, in part, on nutritional and hormonal status during the previtellogenic resting stage. Mating female mosquitoes also altered follicle quality and resorption similarly to nutrition or hormonal application and demonstrates that male accessory gland substances such as JH III passed to the female during copulation have a strong effect on ovarian physiology during the previtellogenic resting stage and can influence reproductive output. Taken together these results demonstrate that the previtellogenic resting stage is not an inactive period but is instead a period marked by extensive life-history and fitness trade-offs in response to nutrition, hormones and mating stimuli.