Viral expression of a SERCA2a-activating PLB mutant improves calcium cycling and synchronicity in dilated cardiomyopathic hiPSC-CMs.

There is increasing momentum toward the development of gene therapy for heart failure (HF) that is defined by impaired calcium (Ca2+) transport and reduced contractility. We have used FRET (fluorescence resonance energy transfer) between fluorescently-tagged SERCA2a (the cardiac Ca2+ pump) and PLB (phospholamban, ventricular peptide inhibitor of SERCA) to test directly the effectiveness of loss-of-inhibition/gain-of-binding (LOI/GOB) PLB mutants (PLBM) that were engineered to compete with the binding of inhibitory wild-type PLB (PLBWT). Our therapeutic strategy is to relieve PLBWT inhibition of SERCA2a by using the reserve adrenergic capacity mediated by PLB to enhance cardiac contractility. Using a FRET assay, we determined that the combination of a LOI PLB mutation (L31A) and a GOB PLB mutation (I40A) results in a novel engineered LOI/GOB PLBM (L31A/I40A) that effectively competes with PLBWT binding to cardiac SERCA2a in HEK293-6E cells. We demonstrated that co-expression of PLBM enhances SERCA Ca-ATPase activity by increasing enzyme Ca2+ affinity (1/KCa) in PLBWT-inhibited HEK293 cell homogenates. For an initial assessment of PLBM physiological effectiveness, we used human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CMs) from a healthy individual. In this system, we observed that adeno-associated virus 2 (rAAV2)-driven expression of PLBM enhances the amplitude of SR Ca2+ release and the rate of SR Ca2+ re-uptake. To assess therapeutic potential, we used a hiPSC-CM model of dilated cardiomyopathy (DCM) containing PLB mutation R14del, where we observed that rAAV2-driven expression of PLBM rescues arrhythmic Ca2+ transients and alleviates decreased Ca2+ transport. Thus, we propose that PLBM transgene expression is a promising gene therapy strategy that directly targets the underlying pathophysiology of abnormal Ca2+ transport and thus contractility in underlying systolic heart failure.

Rapid expansion of post traumatic syringomyelia following parathyroidectomy: A case report and review of the literature.

Background: Post-traumatic syringomyelia (PTS) is an uncommon complication of spinal cord injury (SCI) characterized by development of a fluid filled cavity in the spinal cord parenchyma. Presentation involves pain, weakness, and abnormal reflexes. There are few known triggers for disease progression. We present a case of symptomatic PTS that appears to have been triggered by parathyroidectomy. Case Description: A 42-year-old female with a distant history of SCI developed clinical and imaging findings consistent with acute expansion of PTS immediately following parathyroidectomy. Her symptoms included acute numbness, tingling, and pain in both arms. Magnetic resonance imaging (MRI) revealed a syrinx in the cervical and thoracic spinal cord. However, this was initially misdiagnosed as transverse myelitis and was treated as such without resolution of symptoms. Over the following 6 months, the patient experienced progressive weakness. Repeat MRI demonstrated expansion of the syrinx with new involvement of the brain stem. The patient was diagnosed with PTS and referred for outpatient neurosurgery evaluation at a tertiary facility. Treatment was delayed due to problems with housing and scheduling at the outside facility, allowing for continued worsening of her symptoms. The syrinx was surgically drained and a syringo-subarachnoid shunt was placed. Follow-up MRI confirmed correct placement of the shunt as well as resolved syrinx and decreased thecal sac compression. The procedure effectively halted symptom progression but did not resolve all symptoms completely. The patient has regained her ability to perform much of her activities of daily living but remains in a nursing home facility. Conclusion: There are currently no cases of PTS expansion following non-central nervous system surgery reported in the literature. The reason for PTS expansion following parathyroidectomy in this case is unknown but may highlight the need for extra caution when intubating or positioning a patient with a history of SCI.

Primary epidural sporadic Burkitt lymphoma in a 3-year-old: Case report and literature review.

Background: Burkitt lymphoma (BL) is a common tumor of childhood that usually arises in the abdomen or pelvis in its sporadic form. In a minority of cases, BL can present with CNS involvement, usually as a secondary site. Rarely, BL can arise primarily in the epidural space and present with back pain, or less commonly, acute myelopathy. This presentation is a surgical emergency and requires vigilant management. Case Description: We describe a case of pediatric BL arising primarily within the epidural space and presenting with progressive difficulty walking in a 3-year-old boy. Progression to complete inability to walk, absent lower extremity deep tendon reflexes, and new urinary incontinence prompted MRI of the spine, which showed a lesion extending from T5 to T10 and wrapping around the anterior and posterior portions of the spine with evidence of spinal cord compression. The patient underwent decompressive laminectomies from T5 to T10 and partial debulking of the posterior portions of the tumor. Microscopic examination showed a prominent "starry sky" pattern with abundant mitotic figures. Immunohistochemistry confirmed the diagnosis of BL. The patient is 10 months post-op and continues to undergo chemotherapy with partial neurologic improvement. He was free of recurrence 10 months post-operative. Conclusion: This appears to be the youngest described patient presenting with acute myelopathy in primary paraspinal BL. Management should include surgical decompression of the spinal cord followed by one of the various described chemotherapeutic regimens. Preoperative staging and neurologic function correlate with prognosis.