Development and Characterization of Hemoglobin Microbubbles for Acoustic Blood Oxygen Level Dependent Imaging.

Oxygen levels in tissues and organs are crucial for their normal functioning, and approaches to monitor them non-invasively have wide biological and clinical applications. In this study, we developed a method of acoustically detecting oxygenation using contrast-enhanced ultrasound (CEUS) imaging. Our approach involved the use of specially designed hemoglobin-based microbubbles (HbMBs) that reversibly bind to oxygen and alter the state-dependent acoustic response. We confirmed that the bioactivity of hemoglobin remained intact after the microbubble shell was formed, and we did not observe any significant loss of heme. We conducted passive cavitation detection (PCD) experiments to confirm whether the acoustic properties of HbMBs vary based on the level of oxygen present. The experiments involved driving the HbMBs with a 1.1 MHz focused ultrasound transducer. Through the PCD data collected, we observed significant differences in the subharmonic and harmonic responses of the HbMBs when exposed to an oxygen-rich environment versus an oxygen-depleted one. We used a programmable ultrasound system to capture high-frame rate B mode videos of HbMBs in both oxy and deoxy conditions at the same time in a two-chambered flow phantom and observed that the mean pixel intensity of deoxygenated HbMB was greater than in the oxygenated state using B-mode imaging. Finally, we demonstrated that HbMBs can circulate in vivo and are detectable by a clinical ultrasound scanner. To summarize, our results indicate that CEUS imaging with HbMB has the potential to detect changes in tissue oxygenation and could be a valuable tool for clinical purposes in monitoring regional blood oxygen levels.

Delayed Emergence in Pediatric Patients with Neurologic Disease Presenting for Ambulatory Surgery.

OBJECTIVES: Management of pediatric patients with neurological diagnoses can be challenging for anesthesiologists. We sought to determine whether preexisting neurologic disease could serve as an intrinsic risk factor for prolonged emergence. METHODS: Following institutional review board approval, we conducted a database search from 2012 to 2015. Included were patients aged 0 to 18 years undergoing ambulatory procedures, and carrying neurological diagnoses that profoundly affected their development. Patients were excluded if they received a total intravenous anesthetic, were not managed with an endotracheal tube, or were extubated deep. A healthy case-control group also was obtained for comparison. The primary outcome was emergence from anesthesia: time from anesthetic cessation to extubation. Our secondary outcome was time from extubation to discharge. Descriptive statistics were calculated for demographic data, outcomes were analyzed for differences using the Student t test, and regression analysis was performed. RESULTS: Data from 69 patients and 169 controls met criteria. There were no differences between study and control groups for age, sex, procedural length, or intraoperative temperatures. The study group had higher American Society of Anesthesiologists scores (2.4 vs 1.4). The primary outcome of time to emergence was longer in the study group (15.2 vs 11.0 min), and time to discharge also was prolonged (101.0 vs 86.1 min). Regression analysis on most differing variables did not yield a correlation to primary/secondary outcomes, but neurologic disease did correlate to both. CONCLUSIONS: In this case-controlled retrospective study, there was a prolongation of anesthetic emergence and hospital discharge times for pediatric patients with severe neurologic disease, mostly independent of external factors.

Influence of body position on severity of obstructive sleep apnea: a systematic review.

Aim. The aim of this review is to determine the relationship between sleeping body posture and severity of obstructive sleep apnea. This relationship has been investigated in the past. However, the conclusions derived from some of these studies are conflicting with each other. This paper intends to summarize the reported relationships between sleep posture and various sleep indices in patients diagnosed with sleep apnea. Methods and Materials. A systematic review of the published English literature during a 25-year period from 1983 to 2008 was performed. Results. Published data concerning the sleep apnea severity and posture in adults are limited. Supine sleep posture is consistently associated with more severe obstructive sleep apnea indices in adults. However, relationship between sleep apnea severity indices and prone posture is inconsistent.

Cryopreservation of Lomandra sonderi (Asparagaceae) shoot tips using droplet-vitrification.

A cryopreservation protocol was developed for Lomandra sonderi (Asparagaceae), an endemic plant of southwest Western Australia used for mine site restoration. Thermal analysis of L. sonderi shoot tips using differential scanning calorimetry was used to detect the formation of ice in shoot tips and consequently allowed optimisation of the time of incubation in plant vitrification solution 2 (PVS2), which attempted to minimise phytotoxicity of, and excessive dehydration by, its cryoprotective components. Sugar pretreatments did not improve survival. Use of a loading solution containing 2 M glycerol and 0.4 M sucrose prior to incubation in PVS2 improved survival of control shoot tips. Preconditioning at 20+/-1 degree C day/night alternating temperature with a 16 h photoperiod or at a constant 5 degree C temperature with a 12 h photoperiod both significantly improved both control shoot tip survival and post-cryopreservation survival. Shoot tips that recovered from liquid nitrogen immersion were successfully re-established as actively growing in vitro plantlets.