Cilia and flagella are highly conserved motile and sensory organelles in eukaryotes, and defects in ciliary assembly and motility cause many ciliopathies. The two-headed I1 inner arm dynein is a critical regulator of ciliary and flagellar beating. To understand I1 architecture and function better, we analyzed the 3D structure and composition of the I1 dynein in Chlamydomonas axonemes by cryoelectron tomography and subtomogram averaging. Our data revealed several connections from the I1 dynein to neighboring structures that are likely to be important for assembly and/or regulation, including a tether linking one I1 motor domain to the doublet microtubule and doublet-specific differences potentially contributing to the asymmetrical distribution of dynein activity required for ciliary beating. We also imaged three I1 mutants and analyzed their polypeptide composition using 2D gel-based proteomics. Structural and biochemical comparisons revealed the likely location of the regulatory IC138 phosphoprotein and its associated subcomplex. Overall, our studies demonstrate that I1 dynein is connected to multiple structures within the axoneme, and therefore ideally positioned to integrate signals that regulate ciliary motility.dynein f | flagella C ilia and flagella are highly conserved organelles with roles in cellular movement and signal transduction. In humans, defects in cilia can lead to a number of diseases, such as polycystic kidney disease and primary ciliary dyskinesia (1, 2). The axoneme core of most motile cilia and flagella consists of nine doublet microtubules (DMTs) surrounding two single microtubules (MTs) known as the central pair complex (CPC) (Fig. 1). DMTs are highly periodic with a 96-nm-long unit that repeats along the MT length. They are decorated with two rows of dynein motors, the inner dynein arms (IDAs) and the outer dynein arms (ODAs), which drive MT sliding and axoneme bending (3). Generating the diverse ciliary and flagellar waveforms requires the precise coordination of the activity of thousands of dynein motors within a single organelle (4).The primary signaling pathway known to regulate dynein function in axonemes involves signals traveling from the CPC through radial spokes (RSs) to the IDAs and ODAs (reviewed in 5, 6). Many CPC and RS mutants are paralyzed (7). However, MT sliding can be restored to WT levels in isolated CPC/RS mutant axonemes using protein kinase inhibitors (8, 9). These observations, together with biochemical evidence of phosphorylation of dynein subunits, have implicated the dyneins as a major signaling target of the CPC/RS signaling pathway (10, 11). However, the regulatory mechanisms and physical interactions that participate in signal transduction to the dynein targets are not well understood.Isolated axonemes require only ATP for reactivation, suggesting that direct interactions between the dyneins and their regulators are physically built into the axoneme (4). Therefore, studies that visualize axonemal structures and their connections at high resolution can provide ...

This study demonstrates a lower intubation rate in patients administered ketamine than prior literature in association with a lower weight-based dosing regimen. Ketamine use was correlated with a higher frequency of intubation and a greater need for additional chemical restraint when compared with other restraint modalities, though exogenous factors such as provider preference may have impacted this result. There was no difference in ED length of stay or admission rate between the ketamine and haloperidol plus benzodiazepine groups. Further prospective study is needed to determine whether there is a subset of patients for whom ketamine would be beneficial compared to other therapies.

Introduction: It is difficult to obtain an accurate blood pressure (BP) measurement, especially in the prehospital environment. It is not known fully how various BP measurement techniques differ from one another. Study Objective: The study hypothesized that there are differences in the accuracy of various non-invasive blood pressure (NIBP) measurement strategies as compared to the gold standard of intra-arterial (IA) measurement. Methods: The study enrolled adult intensive care unit (ICU) patients with radial IA catheters placed to measure radial intra-arterial blood pressure (RIBP) as a part of their standard care at a large, urban, tertiary-care Level I trauma center. Systolic blood pressure (SBP) was taken by three different NIBP techniques (oscillometric, auscultated, and palpated) and compared to RIBP measurements. Data were analyzed using the paired t-test with dependent samples to detect differences between RIBP measurements and each NIBP method. The primary outcome was the difference in RIBP and NIBP measurement. There was also a predetermined subgroup analysis based on gender, body mass index (BMI), primary diagnosis requiring IA line placement, and current vasoactive medication use. Results: Forty-four patients were enrolled to detect a predetermined clinically significant difference of 5mmHg in SBP. The patient population was 63.6% male and 36.4% female with an average age of 58.4 years old. The most common primary diagnoses were septic shock (47.7%), stroke (13.6%), and increased intracranial pressure (ICP; 13.6%). Most patients were receiving some form of sedation (63.4%), while 50.0% were receiving vasopressor medication and 31.8% were receiving anti-hypertensive medication. When compared to RIBP values, only the palpated SBP values had a clinically significant difference (9.88mmHg less than RIBP; P < .001). When compared to RIBP, the oscillometric and auscultated SBP readings showed statistically but not clinically significant lower values. The palpated method also showed a clinically significant lower SBP reading than the oscillometric method (5.48mmHg; P < .001) and the auscultated method (5.06mmHg; P < .001). There was no significant difference between the oscillometric and auscultated methods (0.42mmHg; P = .73). Conclusion: Overall, NIBPs significantly under-estimated RIBP measurements. Palpated BP measurements were consistently lower than RIBP, which was statistically and clinically significant. These results raise concern about the accuracy of palpated BP and its pervasive use in prehospital care. The data also suggested that auscultated and oscillometric BP may provide similar measurements.

ObjectivesIf a patient wishes to refuse treatment in the prehospital setting, prehospital providers and consulting emergency physicians must establish that the patient possesses the capacity to do so. The objective of this study is to assess agreement among prehospital providers and emergency physicians in performing patient capacity assessments.MethodsThis study involved 139 prehospital providers and 28 emergency medicine physicians. Study participants listened to 30 medical control calls pertaining to patient capacity and were asked to interpret whether the patients in the scenarios had the capacity to refuse treatment. Participants also reported their comfort level using modified Likert scales. Inter‐rater reliability was calculated utilizing Fleiss' and Model B kappa statistics. Fisher's exact tests were used to calculate p‐values comparing the proportion in each cohort that responded “no capacity.” Primary outcomes included inter‐rater reliability in the physician and prehospital provider cohorts.ResultsThe inter‐rater agreement between the physicians was low (Fleiss' kappa = 0.31, standard error [SE] =0.06; model‐based kappa = 0.18, SE = 0.04). Agreement was similarly low for the 135 prehospital providers (Fleiss' kappa = 0.30, SE = 0.06; model‐based kappa = 0.28, SE = 0.04). The difference between the proportion of physicians and prehospital providers who responded “no capacity” was statistically significant in five of 30 scenarios. Median prehospital provider and physician confidence, on a 1 to 4 scale, was 2.00 (Q1–Q3 = 1.00–3.00 for prehospital providers and Q1–Q3 =1.0–2.0 for physicians).ConclusionsThere was poor inter‐rater reliability in capacity determination between and among the prehospital provider and physician cohorts. This suggests that there is need for additional study and standardization of this task.