Fuel source shift or cost reduction: Context-dependent adaptation strategies in closely related Neodon fuscus and Lasiopodomys brandtii against hypoxia.

Oxygen is essential for most life forms. Insufficient oxygen supply can disrupt homeostasis and compromise survival, and hypoxia-induced cardiovascular failure is fatal in many animals, including humans. However, certain species have adapted and evolved to cope with hypoxic environments and are therefore good models for studying the regulatory mechanisms underlying responses to hypoxia. Here, we explored the physiological and molecular responses of the cardiovascular system in two closely related hypoxia-adapted species with different life histories, namely, Qinghai voles ( Neodon fuscus) and Brandt's voles ( Lasiopodomys brandtii), under hypoxic (10% O 2 for 48 h) and normoxic (20.9% O 2 for 48 h) exposure. Kunming mice ( Mus musculus) were used for comparison. Qinghai voles live in plateau areas under hypoxic conditions, whereas Brandt's voles only experience periodic hypoxia. Histological and hematological analyses indicated a strong tolerance to hypoxia in both species, but significant cardiac tissue damage and increased blood circulation resistance in mice exposed to hypoxia. Comparative transcriptome analysis revealed enhanced oxygen transport efficiency as a coping mechanism against hypoxia in both N. fuscus and L. brandtii, but with some differences. Specifically, N. fuscus showed up-regulated expression of genes related to accelerated cardiac contraction and angiogenesis, whereas L. brandtii showed significant up-regulation of erythropoiesis-related genes. Synchronized up-regulation of hemoglobin synthesis-related genes was observed in both species. In addition, differences in cardiometabolic strategies against hypoxia were observed in the rodents. Notably, M. musculus relied on adenosine triphosphate (ATP) generation via fatty acid oxidation, whereas N. fuscus shifted energy production to glucose oxidation under hypoxic conditions and L. brandtii employed a conservative strategy involving down-regulation of fatty acid and glucose oxidation and a bradycardia phenotype. In conclusion, the cardiovascular systems of N. fuscus and L. brandtii have evolved different adaptation strategies to enhance oxygen transport capacity and conserve energy under hypoxia. Our findings suggest that the coping mechanisms underlying hypoxia tolerance in these closely related species are context dependent.

Failure of Less-Invasive Stabilization System (LISS) plating for periprosthetic distal femur fractures: Three case reports.

RATIONALE: Less-Invasive Stabilization System (LISS) plate is an internal fixation commonly used for the periprosthetic distal femur fractures. Failure associated with LISS plate has been rarely reported, and the reasons for LISS plate failure are multitudinous. Various advantages have been reported, but failures continue. PATIENT CONCERNS: We present 3 cases illustrating the failure of Less-Invasive Stabilization System (LISS) plating for periprosthetic distal femur fractures. The shaft screws of the LISS plate broke in 2 cases, and the plate placement was incorrect in 1 case. Early weight bearing, obesity, osteoporosis, and lateral collateral ligament injury due to incorrect plate placement constituted the etiologies of LISS plate failure. DIAGNOSIS: Failure of Less-Invasive Stabilization System (LISS) plating for periprosthetic distal femur fractures after Total knee arthroplasty. INTERVENTIONS: Three patients underwent Less-Invasive Stabilization System plates removal with replacement of the total knee arthroplasty revision surgery with rotating hinged knee prosthesis. OUTCOMES: After completing the total knee arthroplasty revision surgery, all patients underwent regular follow-up examinations. Case 2 could walk unaided, without pain, final union was confirmed for both case 1 and case 3. CONCLUSION: Less-Invasive Stabilization System (LISS) plate provides satisfactory results in periprosthetic fractures after Total knee arthroplasty (TKA). The LISS plate has many advantages, but failures continue to occur. The causes for failure were early weight bearing, obesity, osteoporosis, and lateral collateral ligament (LCL) injury due to incorrect plate placement in our series. We recommend that protection or properly delay of weight-bearing, active anti-osteoporosis treatment, and intraoperative fluoroscopy are the effective methods to avoid failure.