Tetanic Stimulation Leads to Increased Accumulation of Ca^(2+)/Calmodulin-Dependent Protein Kinase II via Dendritic Protein Synthesis in Hippocampal Neurons

mRNA for the ɑ-subunit of CaMKII is abundant in dendrites of neurons in the forebrain (Steward, 1997). Here we show that tetanic stimulation of the Schaffer collateral pathway causes an increase in the concentration of ɑ-CaMKII in the dendrites of postsynaptic neurons. The increase is blocked by anisomycin and is detected by both quantitative immunoblot and semiquantitative immunocytochemistry. The increase in dendritic ɑ-CaMKII can be measured 100-200 µm away from the neuronal cell bodies as early as 5 min after a tetanus. Transport mechanisms for macromolecules from neuronal cell bodies are not fast enough to account for this rapid increase in distal portions of the dendrites. Therefore, we conclude that dendritic protein synthesis must produce a portion of the newly accumulated CaMKII. The increase in concentration of dendritic CaMKII after tetanus, together with the previously demonstrated increase in autophosphorylated CaMKII (Ouyang et al., 1997), will produce a prolonged increase in steady-state kinase activity in the dendrites, potentially influencing mechanisms of synaptic plasticity that are controlled through phosphorylation by CaMKII

Identification of a Phosphorylation Site for Calcium/Calmodulindependent Protein Kinase II in the NR2B Subunit of the N-Methyl-D-aspartate Receptor

The N-methyl-D-aspartate (NMDA) subtype of excitatory glutamate receptors plays critical roles in embryonic and adult synaptic plasticity in the central nervous system. The receptor is a heteromultimer of core subunits, NR1, and one or more regulatory subunits, NR2A-D. Protein phosphorylation can regulate NMDA receptor function (Lieberman, D. N., and Mody, I. (1994) Nature 369, 235-239; Wang, Y. T., and Salter, M. W. (1994) Nature 369, 233-235; Wang, L.-Y., Orser, B. A., Brautigan, D. L., and MacDonald, J. F. (1994) Nature 369, 230-232). Here we identify a major phosphorylation site on subunit NR2B that is phosphorylated by Ca2+/calmodulin-dependent protein kinase II (CaM kinase II), an abundant protein kinase located at postsynaptic sites in glutamatergic synapses. For the initial identification of the site, we constructed a recombinant fusion protein containing 334 amino acids of the C terminus of the NR2B subunit and phosphorylated it with CaM kinase II in vitro. By peptide mapping, automated sequencing, and mass spectrometry, we identified the major site of phosphorylation on the fusion protein as Ser-383, corresponding to Ser-1303 of full-length NR2B. The Km for phosphorylation of this site in the fusion protein was ~50 nM, much lower than that of other known substrates for CaM kinase II, suggesting that the receptor is a high affinity substrate. We show that serine 1303 in the full-length NR2B and/or the cognate site in NR2A is a major site of phosphorylation of the receptor both in the postsynaptic density fraction and in living hippocampal neurons

Chelators in Iron and Copper Toxicity

Purpose of Review Chelation therapy is used for diseases causing an imbalance of iron levels (for example haemochromatosis and thalassaemia) or copper levels (for example Menkes’ and Wilson’s diseases). Currently, most pharmaceutical chelators are relatively simple but often have side effects. Some have been taken off the market. This review attempts to find theory and knowledge required to design or find better chelators. Recent Findings Recent research attempting to understand the biological mechanisms of protection against iron and copper toxicity is reviewed. Understanding of molecular mechanisms behind normal iron/copper regulation may lead to the design of more sophisticated chelators. The theory of metal ion toxicity explains why some chelators, such as EDTA, which chelate metal ions in a way which exposes the ion to the surrounding environment are shown to be unsuitable except as a means of killing cancer cells. The Lewis theory of acids and bases suggests which amino acids favour the attachment of the hard/intermediate ions Fe2+, Fe3+, Cu2+ and soft ion Cu+. Non-polar amino acids will chelate the ion in a position not in contact with the surrounding cellular environment. The conclusion is that only the soft ion binding cysteine and methionine appear as suitable chelators. Clearly, nature has developed proteins which are less restricted. Recent research on naturally produced chelators such as siderophores and phytochemicals show some promise as pharmaceuticals. Summary Although an understanding of natural mechanisms of Fe/Cu regulation continues to increase, the pharmaceutical chelators for metal overload diseases remain simple non-protein molecules. Natural and synthetic alternatives have been studied but require further research before being accepted

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Tetanic stimulation leads to increased accumulation of Ca2+ calmodulin-dependent protein kinase II via dendritic protein synthesis in hippocampal neurons

mRNA for the alpha-subunit of CaMKII is abundant in dendrites of neurons in the forebrain (Steward, 1997). Here we show that tetanic stimulation of the Schaffer collateral pathway causes an increase in the concentration of alpha-CaMKII in the dendrites of postsynaptic neurons. The increase is blocked by anisomycin and is detected by both quantitative immunoblot and semiquantitative immunocytochemistry. The increase in dendritic alpha-CaMKII can be measured 100-200 micrometer away from the neuronal cell bodies as early as 5 min after a tetanus. Transport mechanisms for macromolecules from neuronal cell bodies are not fast enough to account for this rapid increase in distal portions of the dendrites. Therefore, we conclude that dendritic protein synthesis must produce a portion of the newly accumulated CaMKII. The increase in concentration of dendritic CaMKII after tetanus, together with the previously demonstrated increase in autophosphorylated CaMKII (Ouyang et al., 1997), will produce a prolonged increase in steady-state kinase activity in the dendrites, potentially influencing mechanisms of synaptic plasticity that are controlled through phosphorylation by CaMKII

Disruptive Behaviors in an Emergency Department: the Perspective of Physicians and Nurses

Introduction: Disruptive behaviors cause many problems in the workplace, especially in the emergency department (ED).This study was conducted to assess the physician’s and nurse’s perspective toward disruptive behaviors in the emergency department. Methods: In this cross-sectional study a total of 45 physicians and 110 nurses working in the emergency department of five general hospitals in Bojnurd participated. Data were collected using a translated, changed, and validated questionnaire (25 item). The collected data were analyzed by SPSS ver.13 software. Results: Findings showed that physicians gave more importance to nurse-physician relationships in the ED when compared to nurses’ perspective (90% vs. 70%). In this study, 81% of physicians and 52% of nurses exhibited disruptive behaviors. According to the participants these behaviors could result in adverse outcomes, such as stress (97%), job dissatisfaction and can compromise patient safety (53%), quality of care (72%), and errors (70%). Conclusion: Disruptive behaviors could have a negative effects on relationships and collaboration among medical staffs, and on patients’ quality of care as well. It is essential to provide some practical strategies for prevention of these behaviors