The Role of Arginine-Vasopressin in Stroke and the Potential Use of Arginine-Vasopressin Type 1 Receptor Antagonists in Stroke Therapy: A Narrative Review.

Stroke is a life-threatening condition in which accurate diagnoses and timely treatment are critical for successful neurological recovery. The current acute treatment strategies, particularly non-invasive interventions, are limited, thus urging the need for novel therapeutical targets. Arginine vasopressin (AVP) receptor antagonists are emerging as potential targets to treat edema formation and subsequent elevation in intracranial pressure, both significant causes of mortality in acute stroke. Here, we summarize the current knowledge on the mechanisms leading to AVP hyperexcretion in acute stroke and the subsequent secondary neuropathological responses. Furthermore, we discuss the work supporting the predictive value of measuring copeptin, a surrogate marker of AVP in stroke patients, followed by a review of the experimental evidence suggesting AVP receptor antagonists in stroke therapy. As we highlight throughout the narrative, critical gaps in the literature exist and indicate the need for further research to understand better AVP mechanisms in stroke. Likewise, there are advantages and limitations in using copeptin as a prognostic tool, and the translation of findings from experimental animal models to clinical settings has its challenges. Still, monitoring AVP levels and using AVP receptor antagonists as an add-on therapeutic intervention are potential promises in clinical applications to alleviate stroke neurological consequences.

Recent Advances in Assessment and Treatment in Kienböck's Disease.

Kienböck's disease is a rare disease described as progressive avascular osteonecrosis of the lunate. The typical manifestations include a unilateral reduction in wrist motion with accompanying pain and swelling. Besides recent advances in treatment options, the etiology and pathophysiology of the disease remain poorly understood. Common risk factors include anatomical features including ulnar variance, differences in blood supply, increased intraosseous pressure along with direct trauma, and environmental influence. The staging of Kienböck's disease depends mainly on radiographic characteristics assessed according to the modified Lichtman scale. The selection of treatment options is often challenging, as radiographic features may not correspond directly to initial clinical symptoms and differ among age groups. At the earliest stages of Kienböck disease, the nonoperative, unloading management is generally preferred. Patients with negative ulnar variance are usually treated with radial shortening osteotomy. For patients with positive or neutral ulnar variance, a capitate shortening osteotomy is a recommended option. One of the most recent surgical techniques used in Stage III Kienböck cases is vascularized bone grafting. One of the most promising procedures is a vascularized, pedicled, scaphoid graft combined with partial radioscaphoid arthrodesis. This technique provides excellent pain management and prevents carpal collapse. In stage IV, salvage procedures including total wrist fusion or total wrist arthroplasty are often required.

Neuroprotective Effects of Guanosine in Ischemic Stroke-Small Steps towards Effective Therapy.

Guanosine (Guo) is a nucleotide metabolite that acts as a potent neuromodulator with neurotrophic and regenerative properties in neurological disorders. Under brain ischemia or trauma, Guo is released to the extracellular milieu and its concentration substantially raises. In vitro studies on brain tissue slices or cell lines subjected to ischemic conditions demonstrated that Guo counteracts destructive events that occur during ischemic conditions, e.g., glutaminergic excitotoxicity, reactive oxygen and nitrogen species production. Moreover, Guo mitigates neuroinflammation and regulates post-translational processing. Guo asserts its neuroprotective effects via interplay with adenosine receptors, potassium channels, and excitatory amino acid transporters. Subsequently, guanosine activates several prosurvival molecular pathways including PI3K/Akt (PI3K) and MEK/ERK. Due to systemic degradation, the half-life of exogenous Guo is relatively low, thus creating difficulty regarding adequate exogenous Guo distribution. Nevertheless, in vivo studies performed on ischemic stroke rodent models provide promising results presenting a sustained decrease in infarct volume, improved neurological outcome, decrease in proinflammatory events, and stimulation of neuroregeneration through the release of neurotrophic factors. In this comprehensive review, we discuss molecular signaling related to Guo protection against brain ischemia. We present recent advances, limitations, and prospects in exogenous guanosine therapy in the context of ischemic stroke.