Reverse micelles are discrete nanoscale particles composed of a water core surrounded by surfactant. The amount of water within the core of reverse micelles can be easily manipulated to directly affect the size of the reverse micelle particle. The water loading capacity of reverse micelles varies with temperature, and water can be shed if reverse micelles are exposed to low temperatures. The use of water shedding from the reverse micelle provides precise and comprehensive control over the amount of water available to solvate host molecules. Proteins encapsulated within reverse micelles can be studied to determine the effects of confinement and excluded volume. The data presented here provide an important bridge between commonly employed dilute in vitro studies and studies of the effects of a crowded environment, as found in vivo. Ubiquitin was encapsulated within bis(2-ethylhexyl) sodium sulfosuccinate AOT reverse micelles under various degrees of confinement and was compared with an analogously reconstituted sample of ubiquitin in the commonly used molecular crowding agent bovine serum albumin. The effects of encapsulation were monitored using chemical shift perturbation analysis of the amide (1)H and (15)N resonances. The results also reconcile alternative interpretations of protein cold denaturation within reverse micelles.

Membrane protein structural biology is a rapidly developing field with fundamental importance for elucidating key biological and biophysical processes including signal transduction, intercellular communication, and cellular transport. In addition to the intrinsic interest in this area of research, structural studies of membrane proteins have direct significance on the development of therapeutics that impact human health in diverse and important ways. In this article we demonstrate the potential of investigating the structure of membrane proteins using the reverse micelle forming surfactant dioctyl sulfosuccinate (AOT) in application to the prototypical model ion channel gramicidin A. Reverse micelles are surfactant based nanoparticles which have been employed to investigate fundamental physical properties of biomolecules. The results of this solution NMR based study indicate that the AOT reverse micelle system is capable of refolding and stabilizing relatively high concentrations of the native conformation of gramicidin A. Importantly, pulsed-field-gradient NMR diffusion and NOESY experiments reveal stable gramicidin A homodimer interactions that bridge reverse micelle particles. The spectroscopic benefit of reverse micelle-membrane protein solubilization is also explored, and significant enhancement over commonly used micelle based mimetic systems is demonstrated. These results establish the effectiveness of reverse micelle based studies of membrane proteins, and illustrate that membrane proteins solubilized by reverse micelles are compatible with high resolution solution NMR techniques.

Background Carbon dioxide is a potent cerebral vasodilator that may influence outcomes after ischemic stroke. The objective of this study was to investigate the effect of intraprocedural mean end-tidal CO2 (ETCO2) levels on core infarct expansion and neurologic outcome following thrombectomy for anterior circulation ischemic stroke. Methods A retrospective review was conducted of consecutive patients from March 2020 to June 2021 who underwent mechanical thrombectomy for acute anterior circulation ischemic stroke under general anesthesia and achieved successful recanalization (Thrombolysis in Cerebral Infarction [TICI] ≥ 2b). Only patients with CT perfusion, procedural ETCO2, and postoperative MRI data were included. Segmentation software was used for multi-parametric image analysis. Normocarbia defined as mean ETCO2 of 35 mmHg was used to dichotomize subjects. Univariate and multivariate statistics were applied. Results Fifty-eight patients met criteria for analysis. Of these, 44 had TICI 3 recanalization, 9 had TICI 2c, and 5 had TICI 2b. Within this combined recanalization group, patients with mean ETCO2 > 35 had significantly higher rates of functional independence at 90 days. Although patients tended to salvage more penumbra and experience smaller final infarcts when ETCO2 exceeded 35 mmHg, this did not reach statistical significance. Conclusions Stroke patients who underwent successful thrombectomy with general anesthesia achieved higher rates of functional independence when procedural ETCO2 exceeded 35 mmHg. Further studies to confirm this effect and investigate optimal ETCO2 parameters should be considered.

BACKGROUND A teenage boy who had been stabbed in the neck presented with an extracranial traumatic functional carotid artery occlusion that could not be crossed in an antegrade fashion. Endovascular repair depends on obtaining catheter access proximal and distal to an injury within the true lumen. OBSERVATIONS The occlusion was treated with flossing technique via the posterior communicating artery. After successful recanalization from a retrograde approach, the carotid artery occlusion was treated with a covered stent. LESSONS The flossing technique is well established in peripheral vascular disease and may be beneficial in certain cases in the neck vasculature when antegrade access is difficult to obtain. Recanalization of an occluded carotid artery from retrograde approach may be successful in cases of trauma from knife wounds.

Third molar surgery, also known as wisdom tooth extraction, is one of the most common procedures performed by the oral and maxillofacial surgeon with a generally low complication rate.1-3 Adverse events most often include infection, alveolar osteitis, bleeding, or swelling.3 Less common complications include paresthesia, mandibular fracture and displacement of teeth or instruments. Traumatic pseudoaneurysm (TPA) formation is an extremely rare complication which has been reported in the literature as a potential sequela following tooth extraction.3-11 In the maxillofacial region, TPA is most often associated with penetrating trauma, condylar fractures, and orthognathic surgery and involves the branches of the internal maxillary artery.3,4 TPA occurs when there is disruption in the vascular endothelium followed by blood extravasation into the adventitia or adjacent soft tissue. The resulting collection of blood may continue to expand, leading superimposed infection, severe hemorrhage, or thromboembolism. These lesions lack an intact muscularis layer and are surrounded by a weak connective tissue pseudocapsule. Management can involve both surgical and endovascular treatments. Minimally invasive catheter-based embolization is the favored technique as it avoids the morbidity of an open surgical procedure.12 In this case report, we review the current diagnostic imaging modalities and endovascular treatment paradigm for traumatic pseudoaneurysm of the facial artery following third molar tooth extraction. Several months following a catheter-based embolization procedure, the patient underwent surgical excision of the organized thrombus which presented as a well-lateralized level II neck mass.