Daniel Schnobrich

The DnaK Chaperone System Facilitates 30S Ribosomal Subunit Assembly

Functional Escherichia coli 30S ribosomal subunits can be reconstituted in vitro. However, slow kinetics and sharp temperature dependence suggest additional assembly factors are present in vivo. Extract activation of in vitro assembly results in association of DnaK/hsp70 chaperone components with pre-30S particles. Purified DnaK, its cochaperones DnaJ and GrpE, and ATP can facilitate reconstitution of functional 30S subunits under otherwise nonpermissive conditions. A link has been observed between DnaK, 30S subunit components, and ribosome biogenesis in vivo as well as in vitro. These studies reveal a novel role for the DnaK/hsp70 chaperone system, in addition to its well-documented role in protein folding, and suggest that 30S subunit assembly can be facilitated.

Ultrasound in the diagnosis and management of pleural effusions

We review the literature on the use of point-of-care ultrasound to evaluate and manage pleural effusions. Point-of-care ultrasound is more sensitive than physical exam and chest radiography to detect pleural effusions, and avoids many negative aspects of computerized tomography. Additionally, point-of-care ultrasound can assess pleural fluid volume and character, revealing possible underlying pathologies and guiding management. Thoracentesis performed with ultrasound guidance has lower risk of pneumothorax and bleeding complications. Future research should focus on the clinical effectiveness of point-of-care ultrasound in the routine management of pleural effusions and how new technologies may expand its clinical utility.

Feasibility and acceptability of a structured curriculum in teaching procedural and basic diagnostic ultrasound skills to internal medicine residents.

BACKGROUND Point-of-care ultrasound has emerged as a powerful diagnostic tool and is also being increasingly used by clinicians to guide procedures. Many current and future internists desire training, yet no formal, multiple-application, program-wide teaching interventions have been described. INTERVENTION We describe a structured 30-hour ultrasound training course in diagnostic and procedural ultrasound implemented during intern orientation. Internal medicine interns learned basic ultrasound physics and machine skills; focused cardiac, great vessel, pulmonary, and abdominal ultrasound diagnostic examinations; and procedural applications. RESULTS In postcourse testing, learners demonstrated the ability to acquire images, had significantly increased knowledge scores (P < .001), and demonstrated good performance on practical scenarios designed to test abilities in image acquisition, interpretation, and incorporation into medical decision making. In the postcourse survey, learners strongly agreed (4.6 of 5.0) that ultrasound skills would be valuable during residency and in their careers. CONCLUSIONS A structured ultrasound course can increase knowledge and can result in learners who have skills in image acquisition, interpretation, and integration in management. Future work will focus on refining and improving these skills to allow these learners to be entrusted with the use of ultrasound independently for patient care decisions.

Ultrasound guidance for lumbar puncture

Purpose of review:To review the literature and describe techniques to use ultrasound to guide performance of lumbar puncture (LP). Recent findings:Ultrasound evaluation of the lumbar spine has been shown in randomized trials to improve LP success rates while reducing the number of attempts and the number of traumatic taps. Summary:Ultrasound mapping of the lumbar spine reveals anatomical information that is not obtainable by physical examination, including depth of the ligamentum flavum, width of the interspinous spaces, and spinal bone abnormalities, including scoliosis. Using static ultrasound, the lumbar spine anatomy is visualized in transverse and longitudinal planes and the needle insertion site is marked. Using real-time ultrasound guidance, the needle tip is tracked in a paramedian plane as it traverses toward the ligamentum flavum. Future research should focus on efficient methods to train providers, cost-effectiveness of ultrasound-guided LP, and the role of new needle-tracking technologies to facilitate the procedure.

Recommendations on the Use of Ultrasound Guidance for Adult Thoracentesis: A Position Statement of the Society of Hospital Medicine

Executive Summary: 1) We recommend that ultrasound should be used to guide thoracentesis to reduce the risk of complications, the most common being pneumothorax. 2) We recommend that ultrasound guidance should be used to increase the success rate of thoracentesis. 3) We recommend that ultrasound-guided thoracentesis should be performed or closely supervised by experienced operators. 4) We suggest that ultrasound guidance be used to reduce the risk of complications from thoracentesis in mechanically ventilated patients. 5) We recommend that ultrasound should be used to identify the chest wall, pleura, diaphragm, lung, and subdiaphragmatic organs throughout the respiratory cycle before selecting a needle insertion site. 6) We recommend that ultrasound should be used to detect the presence or absence of an effusion and approximate the volume of pleural fluid to guide clinical decision-making. 7) We recommend that ultrasound should be used to detect complex sonographic features, such as septations, to guide clinical decision-making regarding the timing and method of pleural drainage. 8) We suggest that ultrasound be used to measure the depth from the skin surface to the parietal pleura to help select an appropriate length needle and determine the maximum needle insertion depth. 9) We suggest that ultrasound be used to evaluate normal lung sliding pre- and postprocedure to rule out pneumothorax. 10) We suggest avoiding delay or interval change in patient position from the time of marking the needle insertion site to performing the thoracentesis. 11) We recommend against performing routine postprocedure chest radiographs in patients who have undergone thoracentesis successfully with ultrasound guidance and are asymptomatic with normal lung sliding postprocedure. 12) We recommend that novices who use ultrasound guidance for thoracentesis should receive focused training in lung and pleural ultrasonography and hands-on practice in procedural technique. 13) We suggest that novices undergo simulation-based training prior to performing ultrasound-guided thoracentesis on patients. 14) Learning curves for novices to become competent in lung ultrasound and ultrasound-guided thoracentesis are not completely understood, and we recommend that training should be tailored to the skill acquisition of the learner and the resources of the institution.

Scrotum, Testes, and Paratesticular Structures

Ultrasound is the optimal modality for imaging the scrotum, testicles, and paratesticular structures, and is an essential procedure when the traditional physical exam is inconclusive or incomplete [1]. Ultrasound is required in the evaluation of epididymitis, orchitis, torsion, hydrocele, varicocele, trauma, and other scrotal anomalies (Figs. 32.1, 32.2, 32.3, and 32.4).

Ultrasound guidance for lumbar punctureAuthors Respond

I read the article by Soni et al.1 line by line. Because of my association with a hospital at the epicenter of the AIDS epidemic, I have performed many thousands of lumbar punctures (LPs) for all of the usual reasons. Many patients were tapped repeatedly. I am right-handed and so the LP is performed with the patient in the left lateral decubitus position. This is essential to measure the opening pressure. I mark the back in the usual fashion using the line between the superior iliac crests to identify the L4-L5 interspace. I prefer the L2-L3 interspace for the procedure. Once identified, I begin the procedure. I use the same words with each patient and prep and drape the patient in the same fashion each time. I use local anesthesia. Once I again have the L2 spinous process identified, I keep my left thumb firmly pressed there for guidance and support and to distract the patient. The needle is advanced perpendicular to the skin and once it has passed the bone is at times angled cephalad. What I have described is a ritual. It is the ritual that makes the successful LP and this can be taught.