RESUMEN
Babesiosis is a parasitic infection of the Babesia protozoa, which has been increasing in incidence in endemic areas of the United States. Symptoms of babesiosis can occur on a wide spectrum, from a mild flu-like illness to a fulminant disease course. Known complications of severe cases include intravascular hemolytic anemia and may involve the coagulation system, heart, spleen, kidneys, and in some cases, the lungs. This case report describes an 81-year-old, asplenic female in northern Wisconsin who presented to a hospital with shortness of breath and a non-productive cough. Definitive diagnosis of babesiosis, which was made through both a nucleic acid panel and blood smear, was initially delayed given the rare pulmonary manifestation of babesiosis. When the lungs are involved in the disease course, non-cardiogenic pulmonary edema leading to acute respiratory distress syndrome is among the most commonly seen complications. The pathophysiology of pulmonary involvement has not been made entirely clear but is most likely multifactorial, including the sequelae of changes to both the patient's red blood cells and pulmonary vasculature. This report highlights that atypical tick-borne illnesses like babesiosis should be considered as a cause of acute respiratory failure, particularly in the setting of sepsis and fever. The threshold for parasitic testing should be low in patients in endemic regions with risk factors, including increased age and history of asplenia, as babesiosis frequently has no localizing symptoms to suggest a protozoan infection. As babesiosis incidence continues to rise, prompt diagnosis and proper treatment can prevent severe complications and death in patients.
RESUMEN
Tendon elongation involves both stretching and sliding between adjacent fascicles and fibers. Hence, age-related changes in tendon matrix properties may alter sliding behavior and thereby affect injury thresholds. The objective of this study was to investigate the effects of age on interfibrillar shear behavior in partial cut tendon fascicles. Cine microscopic imaging was used to track deformation patterns of intact and partial cut fascicles from mature (9 months, n = 10) and aged (32 months, n = 10) rat tail tendons. Finite element (FE) models coupled with experimental data provided insight into age-related changes in tissue constitutive properties that could give rise to age-dependent behavior. Intact fascicles from aged tendons exhibited a 28% lower linear region modulus and reduced toe region when compared to fascicles from mature tendons. Partial cut tendon fascicles consistently exhibited a shearing plane that extended longitudinally from the tip of the cut. Both mature and aged fascicles exhibited distinct failure that was observable in differential displacement across the shearing plane. However, aged fascicles exhibited 11-20% higher grip-to-grip strain at failure and tended to exhibit more variable and greater differential displacement at failure, when compared to mature fascicles. FE models suggest that this age-related change in shear behavior arises from a reduction in interfibrillar shear modulus with age. These data suggest that aging alters interfibrillar failure mechanisms and hence may contribute to the increased propensity for injury that is commonly seen in older tendons.
