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Bacteriophytochromes sense light in the near-infrared window, the spectral region where absorption by mammalian tissues is minimal, and their chromophore, biliverdin IXa, is naturally present in animal cells. These properties make bacteriophytochromes particularly attractive for optogenetic applications. However, the lack of understanding of how light-induced conformational changes control output activities has hindered engineering of bacteriophytochrome-based optogenetic tools. Many bacteriophytochromes function as homodimeric enzymes, in which light-induced conformational changes are transferred via a-helical linkers to the rigid output domains. We hypothesized that heterologous output domains requiring homodimerization can be fused to the photosensory modules of bacteriophytochromes to generate light-activated fusions. Here, we tested this hypothesis by engineering adenylate cyclases regulated by light in the near-infrared spectral window using the photosensory module of the Rhodobacter sphaeroides bacteriophytochrome BphGI and the adenylate cyclase domain from Nostoc sp. CyaBL We engineered several light-activated fusion proteins that differed from each other by approximately one or two a-helical turns, suggesting that positioning of the output domains in the same phase of the helix is important for light-dependent activity. Extensive mutagenesis of one of these fusions resulted in an adenylate cyclase with a sixfold photodynamic range. Additional mutagenesis produced an enzyme with a more stable photoactivated state. When expressed in cholinergic neurons in Caenorhabditis elegans, the engineered adenylate cyclase affected worm behavior in a light-dependent manner. The insights derived from this study can be applied to the engineering of other homodimeric bacteriophytochromes, which will further expand the optogenetic toolset. [ABSTRACT FROM AUTHOR]

The article focuses on a study published in the "Journal of Neuroscience" regarding the association of the temporal pattern of microstimulation with behavioral responses. The sensitivity of the oculomotor system to specific microstimulation pulse patterns was examined by applying microstimulation to the frontal eye field (FEF) of the Macaque monkey. The temporal order of interpulse intervals on the effectiveness of microstimulation has been also showed.

Ischemic colitis is the most common form of gastrointestinal ischemia 1. The diagnosis of ischemic colitis is made by clinical data and computed tomography (CT) imaging of the abdomen and pelvis 1. While colonoscopy is considered the gold standard for diagnosis, this is not performed in the emergency department (ED) 2. Few studies have been performed to describe the sonographic findings of ischemic colitis using point of care ultrasound (POCUS). We report a case that highlights the sonographic findings of ischemic colitis in a patient who had two separate visits to the ED, showcasing the utility of POCUS in making this diagnosis. POCUS can be used as a diagnostic tool for early detection of ischemic colitis leading to prompt treatment with antibiotics, CT imaging, and surgical consultation., Competing Interests: AC is a consultant for Phillips Healthcare. All other authors report no relevant disclosures., (Copyright (c) 2024 Kandria Ledesma, MD, Joseph Kim, MD, Allison Cohen, MD, Nicholas Bielawa, PA-C, Mathew Nelson, DO.)

Uterine fibroids occur in up to 30% of women of reproductive age and can cause complications during pregnancy that can harm mother and fetus, such as prematurity and increased risk of miscarriage. This article describes a pregnant woman whose abdominal pain was diagnosed as degenerating uterine fibroids.

Objectives: To assess the self-reported frequency of use of ultrasound guidance for central venous catheterization by emergency medicine (EM) residents, describe residents' perceptions regarding the use of ultrasound guidance, and identify barriers to the use of ultrasound guidance., Methods: A longitudinal cross-sectional study was conducted at 5 academic institutions. A questionnaire on the use of ultrasound guidance for central venous catheterization was initially administered to EM residents in 2007. The same questionnaire was distributed again in the 5 EM residency programs in 2013., Results: In 2007 and 2013, 147 and 131 residents completed questionnaires, respectively. A significant increase in the use of ultrasound guidance for central venous catheterization was reported in 2013 compared to 2007 (P< .001). In 2007, 53% (95% confidence interval, 44%-61%) of residents reported that they were initially trained in central venous catheterization using ultrasound guidance compared to 96% (95% confidence interval, 92%-99%) in 2013 (P < .0001). In 2007, more residents thought that faculty were insufficiently adopting ultrasound (42% versus 9%), and there was a lack of ultrasound teaching during residency training (14% versus 5%) compared to 2013., Conclusions: The use of self-reported ultrasound guidance for central venous catheterization significantly increased from 2007 to 2013 at academic institutions. Most residents were aware of the benefits of using ultrasound guidance. Although faculty adoption of ultrasound for central venous catheterization remains a barrier, it has decreased., (© 2015 by the American Institute of Ultrasound in Medicine.)

Objectives: Resuscitation often requires rapid vascular access via central venous catheters. Chest radiography is the reference standard to confirm central venous catheter placement and exclude complications. However, radiographs are often untimely. The purpose of this study was to determine whether dynamic sonographic visualization of a saline flush in the right side of the heart after central venous catheter placement could serve as a more rapid confirmatory study for above-the-diaphragm catheter placement., Methods: A consecutive prospective enrollment study was conducted in the emergency departments of 2 major tertiary care centers. Adult patients of the study investigators who required an above-the-diaphragm central venous catheter were enrolled during the study period. Patients had a catheter placed with sonographic guidance. After placement of the catheter, thoracic sonography was performed. The times for visualization of the saline flush in the right ventricle and sonographic exclusion of ipsilateral pneumothorax were recorded. Chest radiography was performed per standard practice., Results: Eighty-one patients were enrolled; 13 were excluded. The mean catheter confirmation time by sonography was 8.80 minutes (95% confidence interval, 7.46-10.14 minutes). The mean catheter confirmation time by chest radiograph availability for viewing was 45.78 minutes (95% confidence interval, 37.03-54.54 minutes). Mean sonographic confirmation occurred 36.98 minutes sooner than radiography (P< .001). No discrepancy existed between sonographic and radiographic confirmation., Conclusions: Confirmation of central venous catheter placement by dynamic sonographic visualization of a saline flush with exclusion of pneumothorax is an accurate, safe, and more efficient method than confirmation by chest radiography. It allows the central line to be used immediately, expediting patient care., (© 2015 by the American Institute of Ultrasound in Medicine.)

Purpose: The purpose of this study was to determine the effect of thermal stress and hydration status on immune function during exercise., Methods: Ten trained men completed four cycle ergometer rides at 55% VO2peak under the following conditions: EN (euhydrated neutral; 22 degrees C, 30% RH), DN (dehydrated neutral), EH (euhydrated hot; 38 degrees C, 45% RH), and DH (dehydrated hot). During EN and EH, a carbohydrate/electrolyte beverage was consumed at a rate matching sweat loss, and during DN and DH, no fluid was ingested. Blood samples were drawn pre- and postexercise, and at 2 and 24 h of recovery. Cell counts were determined by automated counting and flow cytometry. Neutrophil activity was assessed as superoxide production, lymphocyte function was determined via PHA-stimulated mitogenesis, and natural killer (NK) cell activity was measured with a 51Cr-release assay. Cortisol was assayed via RIA., Results: Lymphocytes proliferation was depressed 2 h after exercise in all conditions (P < 0.05); however, when expressed on a per cell basis, function was greater in the DH and EH conditions. NK activity (max x 10(3) cells) was greater post compared with preexercise in all conditions (EH = 25.5 +/- 16.8, DH = 26.2 +/- 10.5, EN = 19.3 +/- 11.0, and DN = 16.5 +/- 8.7) but was not different between conditions. Leukocyte, neutrophil, lymphocyte, and NK cell counts were also elevated postexercise with the former two remaining elevated 2 h postexercise in the EH and DH conditions. Cortisol was greater postexercise in EH (22.1 +/- 1.3) and DH (27.7 +/- 1.3) compared with EN (17.8 +/- 2.1) and DN (18.9 +/- 1.6 microg x dL(-1)., Conclusion: Euhydration did not affect cell number or function when compared with a dehydrated state; however, the hot environment caused more severe disturbances in these measures compared with a neutral environment.