68 Ga-Citrate PET/CT Imaging in the Diagnosis of Skull Base Osteomyelitis and Its Usefulness in the Assessment of Treatment Response.

PURPOSE: 68 Ga-citrate PET/CT imaging in the diagnosis of skull base osteomyelitis (SBO) and its usefulness in the assessment of treatment response. METHODS: Eighteen patients underwent 68 Ga-citrate PET/CT scans for suspected SBO for diagnosis/assessment of treatment response. RESULTS: Of 18 patients, 16 patients had a positive study for SBO, and 2 patients had a negative study. Scan findings were correlated with clinical, biochemical, microbiological, and radiological parameters. CONCLUSION: 68 Ga-citrate PET/CT is a promising tool in the diagnosis and management of skull base osteomyelitis.

Effects of cardiovascular arousal on emotional experience.

Studies of arousal and emotion show that generalized physiological arousal can enhance emotional experience for a range of different emotions. Other research shows that different emotions may be associated with specific patterns of physiological reactivity. Together these findings suggest that while nonspecific autonomic activation can be sufficient in the generation of emotion, specific patterns of reactivity may appear once the emotion is established. This study aimed to test this hypothesis by examining the effects of generalized arousal on emotional experience, as well as the physiological responses associated with positive and negative emotions. One hundred and nine participants either sat or stood during the viewing of positive and negative film clips while emotion ratings and cardiorespiratory measures were taken. Those who stood during the videos reported greater levels of emotion than those who sat, indicating that generalized arousal due to standing heightened emotional experience. In addition, participants exhibited greater high-frequency heart rate variability and lower respiration rate during the negative video than the positive video, indicating that physiological reactivity differed between the positive and negative emotions. These results suggest that while patterns of physiological reactivity may be specific to individual emotions, nonspecific arousal is sufficient to enhance diverse emotions.

A Comparative Case Study between Gallium-67 Citrate Scintigraphy and Gallium-68 Citrate Positron Emission Tomography-Computed Tomography in Bone Infection.

Bone infections are a common problem, and early diagnosis and intervention can lead to better clinical outcomes and prognoses. Here, we compare the well-known tracers Gallium-67 (Ga-67) citrate versus Ga-68 citrate in the diagnosis of infections.

Effects of self-affirmation on emotion and cardiovascular responses.

Self-affirmation is the act of focusing on important aspects of the self, such as personal values and characteristics. We used a within-participants design (N = 125) to examine cardiovascular reactivity and self-reported affective responses to the practice of self-affirmation. In the self-affirmation condition, we asked participants to write about their top-ranked personal value for 5 min and used a writing exercise unrelated to personal values in the control condition. The International Affective Picture System was used to induce positive and negative emotion. Results showed that participants had greater high frequency heart rate variability and respiratory sinus arrhythmia (RSA) when practicing self-affirmation. During negative emotion induction, self-affirmation also led to lower maximum heart rate, higher RSA, and lower ratings of negative affect. Our findings suggest that the act of focusing on an important aspect of self has beneficial effects on psychological and physiological well-being.

Low- and room-temperature X-ray structures of protein kinase A ternary complexes shed new light on its activity.

Post-translational protein phosphorylation by protein kinase A (PKA) is a ubiquitous signalling mechanism which regulates many cellular processes. A low-temperature X-ray structure of the ternary complex of the PKA catalytic subunit (PKAc) with ATP and a 20-residue peptidic inhibitor (IP20) at the physiological Mg(2+) concentration of ∼0.5 mM (LT PKA-MgATP-IP20) revealed a single metal ion in the active site. The lack of a second metal in LT PKA-MgATP-IP20 renders the ß- and γ-phosphoryl groups of ATP very flexible, with high thermal B factors. Thus, the second metal is crucial for tight positioning of the terminal phosphoryl group for transfer to a substrate, as demonstrated by comparison of the former structure with that of the LT PKA-Mg(2)ATP-IP20 complex obtained at high Mg(2+) concentration. In addition to its kinase activity, PKAc is also able to slowly catalyze the hydrolysis of ATP using a water molecule as a substrate. It was found that ATP can be readily and completely hydrolyzed to ADP and a free phosphate ion in the crystals of the ternary complex PKA-Mg(2)ATP-IP20 by X-ray irradiation at room temperature. The cleavage of ATP may be aided by X-ray-generated free hydroxyl radicals, a very reactive chemical species, which move rapidly through the crystal at room temperature. The phosphate anion is clearly visible in the electron-density maps; it remains in the active site but slides about 2 Šfrom its position in ATP towards Ala21 of IP20, which mimics the phosphorylation site. The phosphate thus pushes the peptidic inhibitor away from the product ADP, while resulting in dramatic conformational changes of the terminal residues 24 and 25 of IP20. X-ray structures of PKAc in complex with the nonhydrolysable ATP analogue AMP-PNP at both room and low temperature demonstrated no temperature effects on the conformation and position of IP20.