Acute TrkB inhibition rescues phenobarbital‐resistant seizures in a mouse model of neonatal ischemia

Neonatal seizures are commonly associated with hypoxic–ischemic encephalopathy. Phenobarbital (PB) resistance is common and poses a serious challenge in clinical management. Using a newly characterized neonatal mouse model of ischemic seizures, this study investigated a novel strategy for rescuing PB resistance. A small‐molecule TrkB antagonist, ANA12, used to selectively and transiently block post‐ischemic BDNF‐TrkB signaling in vivo, determined whether rescuing TrkB‐mediated post‐ischemic degradation of the K⁺–Cl^? co‐transporter (KCC2) rescued PB‐resistant seizures. The anti‐seizure efficacy of ANA12 + PB was quantified by (i) electrographic seizure burden using acute continuous video‐electroencephalograms and (ii) post‐treatment expression levels of KCC2 and NKCC1 using Western blot analysis in postnatal day (P)7 and P10 CD1 pups with unilateral carotid ligation. ANA12 significantly rescued PB‐resistant seizures at P7 and improved PB efficacy at P10. A single dose of ANA12 + PB prevented the post‐ischemic degradation of KCC2 for up to 24 h. As anticipated, ANA12 by itself had no anti‐seizure properties and was unable to prevent KCC2 degradation at 24 h without follow‐on PB. This indicates that unsubdued seizures can independently lead to KCC2 degradation via non‐TrkB‐dependent pathways. This study, for the first time as a proof‐of‐concept, reports the potential therapeutic value of KCC2 modulation for the management of PB‐resistant seizures in neonates. Future investigations are required to establish the mechanistic link between ANA12 and the prevention of KCC2 degradation.     

Repetitive Treatment with Diluted Bee Venom Attenuates the Induction of Below-Level Neuropathic Pain Behaviors in a Rat Spinal Cord Injury Model

The administration of diluted bee venom (DBV) into an acupuncture point has been utilized traditionally in Eastern medicine to treat chronic pain. We demonstrated previously that DBV has a potent anti-nociceptive efficacy in several rodent pain models. The present study was designed to examine the potential anti-nociceptive effect of repetitive DBV treatment in the development of below-level neuropathic pain in spinal cord injury (SCI) rats. DBV was applied into the Joksamli acupoint during the induction and maintenance phase following thoracic 13 (T13) spinal hemisection. We examined the effect of repetitive DBV stimulation on SCI-induced bilateral pain behaviors, glia expression and motor function recovery. Repetitive DBV stimulation during the induction period, but not the maintenance, suppressed pain behavior in the ipsilateral hind paw. Moreover, SCI-induced increase in spinal glia expression was also suppressed by repetitive DBV treatment in the ipsilateral dorsal spinal cord. Finally, DBV injection facilitated motor function recovery as indicated by the Basso–Beattie–Bresnahan rating score. These results indicate that the repetitive application of DBV during the induction phase not only decreased neuropathic pain behavior and glia expression, but also enhanced locomotor functional recovery after SCI. This study suggests that DBV acupuncture can be a potential clinical therapy for SCI management.     

Photoaging: pathogenesis, prevention, and treatment

Premature skin aging, or photoaging, results largely from repeated exposure to ultraviolet (UV) radiation from the sun. Photoaging is characterized clinically by wrinkles, mottled pigmentation, rough skin, and loss of skin tone; the major histologic alterations lie in dermal connective tissue. In recent years, a great deal of research has been done to explain the mechanism by which UV induces dermal damage. This research has enabled the identification of rational targets for photoaging prevention strategies. Moreover, studies that have elucidated photoaging pathophysiology have produced significant evidence that topical tretinoin (all-trans retinoic acid), the only agent approved so far for the treatment of photoaging, also works to prevent it. This article summarizes evidence mainly from studies of human volunteers that provide the basis for the current model of photoaging and the effects of tretinoin.     

Treatment of Dural Carotid-Cavernous Fistulas via the Medial Ophthalmic Vein

Aim: To present a novel approach to treatment of dural carotid-cavernous fistulas via the medial ophthalmic vein.

Design: Retrospective case series.

Material and Methods: In this retrospective case series, we present 2 patients (3 eyes) with Type C dural CCFs, who had failed cannulation via the conventional transfemoral route and the transorbital superior ophthalmic vein approach. They subsequently underwent CCF occlusion via an anterior orbital approach through the medial ophthalmic veins, at the Department of Ophthalmology, National University Hospital Singapore. CCF occlusion was confirmed intraoperatively using angiography. Both patients were evaluated postoperatively for best-corrected visual acuity and resolution of clinical signs and symptoms.

Results: Successful occlusion of CCFs via the medial ophthalmic veins were achieved in all three orbits, with excellent visual and cosmetic outcomes postoperatively.

Conclusion: Dural CCFs may potentially lead to severe visual dysfunction and should be diagnosed and treated promptly. When all venous routes have been exhausted, the transorbital approach via the medial ophthalmic vein remains an excellent and viable alternative to access the fistula. Close cooperation between the orbital, anesthetic and radiological teams is essential in ensuring success of the operation.