Corrigendum: Iatrogenic air embolism: pathoanatomy, thromboinflammation, endotheliopathy, and therapies

[This corrects the article DOI: 10.3389/fimmu.2023.1230049.].

Iatrogenic air embolism: pathoanatomy, thromboinflammation, endotheliopathy, and therapies

Iatrogenic vascular air embolism is a relatively infrequent event but is associated with significant morbidity and mortality. These emboli can arise in many clinical settings such as neurosurgery, cardiac surgery, and liver transplantation, but more recently, endoscopy, hemodialysis, thoracentesis, tissue biopsy, angiography, and central and peripheral venous access and removal have overtaken surgery and trauma as significant causes of vascular air embolism. The true incidence may be greater since many of these air emboli are asymptomatic and frequently go undiagnosed or unreported. Due to the rarity of vascular air embolism and because of the many manifestations, diagnoses can be difficult and require immediate therapeutic intervention. An iatrogenic air embolism can result in both venous and arterial emboli whose anatomic locations dictate the clinical course. Most clinically significant iatrogenic air emboli are caused by arterial obstruction of small vessels because the pulmonary gas exchange filters the more frequent, smaller volume bubbles that gain access to the venous circulation. However, there is a subset of patients with venous air emboli caused by larger volumes of air who present with more protean manifestations. There have been significant gains in the understanding of the interactions of fluid dynamics, hemostasis, and inflammation caused by air emboli due to in vitro and in vivo studies on flow dynamics of bubbles in small vessels. Intensive research regarding the thromboinflammatory changes at the level of the endothelium has been described recently. The obstruction of vessels by air emboli causes immediate pathoanatomic and immunologic and thromboinflammatory responses at the level of the endothelium. In this review, we describe those immunologic and thromboinflammatory responses at the level of the endothelium as well as evaluate traditional and novel forms of therapy for this rare and often unrecognized clinical condition.

Parallel learning and cognitive flexibility impairments between Fmr1 knockout mice and individuals with fragile X syndrome

Introduction

Fragile X Syndrome (FXS) is a monogenic condition that leads to intellectual disability along with behavioral and learning difficulties. Among behavioral and learning difficulties, cognitive flexibility impairments are among the most commonly reported in FXS, which significantly impacts daily living. Despite the extensive use of the Fmr1 knockout (KO) mouse to understand molecular, synaptic and behavioral alterations related to FXS, there has been limited development of translational paradigms to understand cognitive flexibility that can be employed in both animal models and individuals with FXS to facilitate treatment development.

Methods

To begin addressing this limitation, a parallel set of studies were carried out that investigated probabilistic reversal learning along with other behavioral and cognitive tests in individuals with FXS and Fmr1 KO mice. Fifty-five adolescents and adults with FXS (67% male) and 34 age- and sex-matched typically developing controls (62% male) completed an initial probabilistic learning training task and a probabilistic reversal learning task.

Results

In males with FXS, both initial probabilistic learning and reversal learning deficits were found. However, in females with FXS, we only observed reversal learning deficits. Reversal learning deficits related to more severe psychiatric features in females with FXS, whereas increased sensitivity to negative feedback (lose:shift errors) unexpectedly appear to be adaptive in males with FXS. Male Fmr1 KO mice exhibited both an initial probabilistic learning and reversal learning deficit compared to that of wildtype (WT) mice. Female Fmr1 KO mice were selectively impaired on probabilistic reversal learning. In a prepotent response inhibition test, both male and female Fmr1 KO mice were impaired in learning to choose a non-preferred spatial location to receive a food reward compared to that of WT mice. Neither male nor female Fmr1 KO mice exhibited a change in anxiety compared to that of WT mice.

Discussion

Together, our findings demonstrate strikingly similar sex-dependent learning disturbances across individuals with FXS and Fmr1 KO mice. This suggests the promise of using analogous paradigms of cognitive flexibility across species that may speed treatment development to improve lives of individuals with FXS.

Safety and tolerability of transcranial magnetic and direct current stimulation in children: Prospective single center evidence from 3.5 million stimulations

BACKGROUND

Non-invasive brain stimulation is being increasingly used to interrogate neurophysiology and modulate brain function. Despite the high scientific and therapeutic potential of non-invasive brain stimulation, experience in the developing brain has been limited.

OBJECTIVE

To determine the safety and tolerability of non-invasive neurostimulation in children across diverse modalities of stimulation and pediatric populations.

METHODS

A non-invasive brain stimulation program was established in 2008 at our pediatric, academic institution. Multi-disciplinary neurophysiological studies included single- and paired-pulse Transcranial Magnetic Stimulation (TMS) methods. Motor mapping employed robotic TMS. Interventional trials included repetitive TMS (rTMS) and transcranial direct current stimulation (tDCS). Standardized safety and tolerability measures were completed prospectively by all participants.

RESULTS

Over 10 years, 384 children underwent brain stimulation (median 13 years, range 0.8-18.0). Populations included typical development (n = 118), perinatal stroke/cerebral palsy (n = 101), mild traumatic brain injury (n = 121) neuropsychiatric disorders (n = 37), and other (n = 7). No serious adverse events occurred. Drop-outs were rare (<1%). No seizures were reported despite >100 participants having brain injuries and/or epilepsy. Tolerability between single and paired-pulse TMS (542340 stimulations) and rTMS (3.0 million stimulations) was comparable and favourable. TMS-related headache was more common in perinatal stroke (40%) than healthy participants (13%) but was mild and self-limiting. Tolerability improved over time with side-effect frequency decreasing by >50%. Robotic TMS motor mapping was well-tolerated though neck pain was more common than with manual TMS (33% vs 3%). Across 612 tDCS sessions including 92 children, tolerability was favourable with mild itching/tingling reported in 37%.

CONCLUSIONS

Standard non-invasive brain stimulation paradigms are safe and well-tolerated in children and should be considered minimal risk. Advancement of applications in the developing brain are warranted. A new and improved pediatric NIBS safety and tolerability form is included.

Behavioral and physiological characterization of PKC-dependent phosphorylation in the Grin2a∆PKC mouse

Activity-dependent plasticity in NMDA receptor-containing synapses can be regulated by phosphorylation of serines and tyrosines in the C-terminal domain of the receptor subunits by various kinases. We have previously identified S1291/S1312 as important sites for PKC phosphorylation; while Y1292/Y1312 are the sites indirectly phosphorylated by PKC via Src kinase. In the oocyte expression system, mutation of those Serine sites to Alanine (that cannot be phosphorylated) in the GluN2A subunit, resulted in a decreased PKC stimulated current enhancement through the receptors compared to wild-type NMDA receptors. To investigate the behavioral and physiological significance of those PKC-mediated phosphorylation sites in vivo, the Grin2a∆PKC mouse expressing GluN2A with four mutated amino acids: S1291A, S1312A, Y1292F and Y1387F was generated using homologous recombination. The Grin2a∆PKC mice exhibit reduced anxiety in the open field test, light dark emergence test, and elevated plus maze. The mutant mice show reduced alternation in a Y maze spontaneous alternation task and a in a non-reinforced T maze alternation task. Interestingly, when the mutant mice were exposed to novel environments, there was no increase in context-induced Fos levels in hippocampal CA1 and CA3 compared to home-cage Fos levels, while the Fos increased in the WT mice in CA1, CA3 and DG. When the SC-CA1 synapses in slices from mutant mice were stimulated using a theta-burst protocol, there was no impairment in LTP. Overall, these results suggest that at least one of those PKC-mediated phosphorylation sites regulates NMDAR-mediated signaling that modulates anxiety.

Management of painful diabetic neuropathy

Type 2 diabetes mellitus is a prevalent disease in the US which affects more than 15 million people. As the disease progresses over time, neuropathic pain can become a common complication; it is present in more than 50% of individuals with diabetes mellitus aged >60 years. The pathogenesis of diabetic neuropathy is theorized to be multifactorial. Numerous medications, some with different mechanisms of action, have been examined regarding their effects on the symptoms associated with diabetic neuropathy such as pain, paraesthesia and numbness. However, the majority of the studies have included small patient populations. Tricyclic antidepressants, amitriptyline and desipramine in particular, have been relatively well studied and shown to be effective. However, anticholinergic adverse effects may limit their usefulness and may preclude use in the elderly. Studies have also shown gabapentin to be effective and well tolerated in the treatment of diabetic neuropathy. Capsaicin cream provides another treatment option with a favourable adverse effect profile. Many other medications have been evaluated in diabetic neuropathy; however, more placebo-controlled studies with adequate patient populations need to be performed to solidify their role in treatment.

Decision making of clinical teams: communication patterns and diagnostic error

This study examined the discussion of information among mixed-status clinical teams while constructing differential diagnoses. Twenty-four ad hoc teams, each consisting of a resident, an intern, and a third-year medical student, were given two hypothetical patient cases to discuss and diagnose. Prior to discussion, team members individually viewed different versions of a videotaped interview with a "patient" (trained actor). Each videotape contained some information that was present in all three versions (shared information) and some that was present in only that version (unique information). In addition, half of the time, the cases were constructed so that the unique information that appeared in only one tape was crucial for a correct diagnosis (a "hidden profile" condition). After viewing the videotapes, team members met to discuss the case and develop a differential diagnosis. Discussions were videotaped and analyzed. Overall, shared information was mentioned more often than unique information (p < 0.0001). Furthermore, teams offered incorrect diagnoses significantly more often for hidden-profile cases than for control cases (p < 0.01). The teams' overreliance on previously shared information (inability to appropriately utilize unique information) was detrimental when a correct diagnosis demanded the inclusion of such information. Clinical discussions that require the consideration of uniquely held information may be susceptible to error.

Diagnosing groups: the pooling, management, and impact of shared and unshared case information in team-based medical decision making

The impact of group discussion on the decision-making effectiveness of medical teams was examined. Three-person teams of physicians diagnosed 2 hypothetical medical cases. Some of the information about each case was given to all team members prior to discussion (shared information), whereas the rest was divided among them (unshared information). Compared with unshared information, shared information was more likely to be pooled during discussion and was pooled earlier. In addition, team leaders were consistently more likely than other members to ask questions and to repeat shared information and, over time, also became more likely than others to repeat unshared information. Finally, pooling unshared (but not shared) information improved the overall accuracy of the team diagnoses, whereas repeating both shared and unshared information affected bias (but not accuracy) in the diagnoses.

Diagnosing groups: the pooling, management, and impact of shared and unshared case information in team-based medical decision making

The impact of group discussion on the decision-making effectiveness of medical teams was examined. Three-person teams of physicians diagnosed 2 hypothetical medical cases. Some of the information about each case was given to all team members prior to discussion (shared information), whereas the rest was divided among them (unshared information). Compared with unshared information, shared information was more likely to be pooled during discussion and was pooled earlier. In addition, team leaders were consistently more likely than other members to ask questions and to repeat shared information and, over time, also became more likely than others to repeat unshared information. Finally, pooling unshared (but not shared) information improved the overall accuracy of the team diagnoses, whereas repeating both shared and unshared information affected bias (but not accuracy) in the diagnoses.

Diagnosing groups: charting the flow of information in medical decision-making teams

Several hypotheses derived from an information sampling model of group discussion were tested with 3-person teams of physicians given 2 hypothetical medical cases to diagnose. Some of the information about each case was given to all 3 team members before discussion (shared information), whereas the rest was divided among them (unshared information). As predicted, shared information was, overall, more likely to be discussed than unshared information, and it was brought into discussion earlier. In addition, it was found that team leaders repeated substantially more case information than did other members and that, over time, they repeated unshared information at a steadily increasing rate. The latter findings are interpreted as evidence of leaders' information management role in problem-solving discussions.

Diagnosing groups: charting the flow of information in medical decision-making teams

Several hypotheses derived from an information sampling model of group discussion were tested with 3-person teams of physicians given 2 hypothetical medical cases to diagnose. Some of the information about each case was given to all 3 team members before discussion (shared information), whereas the rest was divided among them (unshared information). As predicted, shared information was, overall, more likely to be discussed than unshared information, and it was brought into discussion earlier. In addition, it was found that team leaders repeated substantially more case information than did other members and that, over time, they repeated unshared information at a steadily increasing rate. The latter findings are interpreted as evidence of leaders' information management role in problem-solving discussions.

Collaborative medical decision making

Collaborative decision making occurs whenever two or more individuals contribute their diverse knowledge and expertise to the decision-making process. In medicine, this happens during morning rounds, case conferences, consultations, and elsewhere. This paper presents an analysis of collaborative medical decision making, focusing on two factors that can powerfully influence the kind of information that gets discussed, and hence the nature of the decisions that are made. These are 1) the pre-discussion distribution of problem-relevant information/knowledge, and 2) each participant's awareness of other individuals' knowledge and talents. The authors review previous psychological research on group decision making that concerns these factors, and call attention to several lines of inquiry that might fruitfully be pursued in clinical settings.

Expression of truncated forms of liver microsomal P450 cytochromes 2B4 and 2E1 in Escherichia coli: influence of NH2-terminal region on localization in cytosol and membranes

The currently accepted model for the membrane topology of microsomal cytochrome P450 is that of a largely cytoplasmic domain bound by only one or two transmembrane segments at the NH2 terminus. However, as we have reported previously, P450 2E1 lacking the hydrophobic NH2-terminal signal peptide, like the full-length protein, is located in the inner cell membrane when expressed in Escherichia coli and is active with typical substrates. In the present study, additional variants of alcohol-inducible P450 2E1 as well as truncated forms of phenobarbital-inducible P450 2B4 were similarly expressed to determine the influence of the NH2-terminal region on the membrane-binding properties. After deletion of S1 (the NH2-terminal hydrophobic segment), or both S1 and L1 (the following hydrophilic region, expected to be lumenal or cytosolic), one-third of the resulting P450 2B4 (delta 2-20) and 2B4 (delta 2-27) remained membrane bound. Furthermore, the idea that the first two hydrophobic segments are required for attachment by a hairpin loop is not supported by the finding that after deletion of the S1, L1, and S2 segments about half of the P450 2E1 (delta 3-48) remained membrane bound. Since Na2CO3 treatment of the membrane fraction had no significant effect, the findings are apparently not attributable to a loose attachment or occlusion of the truncated proteins. The replacement of neutral amino acids by positively charged residues in positions 3 and 8 of P450 2E1 (delta 3-29) changed the amount in the cytosol from 35% to 50%, and the deletion of residues 2-20 or 2-27 from P450 2B4, which resulted in positive charges occurring in the NH2-terminal region, changed the amount in the cytosol from 27% to 67%. We conclude that alterations in the NH2-terminal region can change the location of the cytochrome from largely membranous to largely cytosolic and that the first two hydrophobic segments are not uniquely involved in membrane attachment.

Purification and properties of a shortened form of cytochrome P-450 2E1: deletion of the NH2-terminal membrane-insertion signal peptide does not alter the catalytic activities

As reported previously, alcohol-inducible cytochrome P-450 2E1 lacking the hydrophobic NH2-terminal segment is located primarily in the inner cell membrane when expressed in Escherichia coli and is active with a typical substrate. To study the catalytic properties in detail, we have purified the truncated P-450 lacking residues 3-29 to electrophoretic homogeneity from the solubilized bacterial membrane fraction in the presence of 4-methylpyrazole as a stabilizing agent. The resulting heme protein with a specific content of 15.8 nmol of P-450 per mg of protein has a reduced CO difference spectrum identical to that of the full-length enzyme, with a Soret maximum at 452 nm. The rates of catalysis of four reactions in the reconstituted enzyme system, including the oxygenation of ethanol to give acetaldehyde, the oxidative dealkylation of N-nitrosodiethylamine to give ethylene and acetaldehyde, and the ring hydroxylation of aniline and p-nitrophenol, are the same with the shortened and full-length enzymes. The apparent Km of p-nitrophenol is also the same, as is that for NADPH-cytochrome P-450 reductase and for cytochrome b5, which stimulates p-nitrocatechol formation about 3-fold. Moreover, the requirement for phosphatidylcholine for full catalytic activity is unchanged despite the absence of the NH2-terminal segment. Although this highly hydrophobic segment is believed to play a role in the intact cell as a membrane-insertion signal sequence, we conclude that it has no function in the catalytic activity of the cytochrome as an oxygenase, including interactions with the other components of the enzyme system.

Alcohol-inducible cytochrome P-450IIE1 lacking the hydrophobic NH2-terminal segment retains catalytic activity and is membrane-bound when expressed in Escherichia coli

We have expressed in Escherichia coli a cDNA encoding rabbit liver cytochrome P-450IIE1, the ethanol-inducible P-450. The expressed P-450 is located primarily in the bacterial inner cell membrane and comprises 3% of the E. coli total membrane protein. The partially purified cytochrome exhibits a reduced CO difference spectrum with a maximum at 452 nm, characteristic of P-450IIE1, and solubilized membranes or partially purified P-450 preparations reconstituted with NADPH-cytochrome P-450 reductase and phosphatidylcholine catalyze the deethylation of N-nitrosodiethylamine with a turnover number equal to that of purified liver P-450IIE1 (approximately 4.5 nmol/min/nmol of P-450). A modified IIE1 cDNA that encodes a protein lacking amino acids 3-29, a proposed membrane anchor for cytochrome P-450, was also expressed in E. coli and, unexpectedly, the shortened protein was also found to be predominantly located in the bacterial inner membrane rather than the cytosol. Like the full-length protein, this truncated cytochrome has a reduced CO difference spectrum characteristic of P-450IIE1 and is fully active in the deethylation of N-nitrosodiethylamine. These results demonstrate that the NH2-terminal hydrophobic segment is not solely responsible for attachment to the membrane and evidently is not required for proper protein folding or catalytic activity.

Effects of unilateral and bilateral training in a reaching task on dendritic branching of neurons in the rat motor-sensory forelimb cortex

Effects of motor training on a neocortical nerve cell population involved in performance of the motor task were assessed by measuring Layer V pyramidal neuron apical dendritic branching in motor-sensory forelimb cortex of rats trained to reach into a tube for food. Rats were trained to reach with the forepaw they preferred to use (group PRAC), the nonpreferred forepaw (REV), both forepaws (ALT), or neither forepaw (CONT). Across groups, hemispheres opposite trained forepaws had larger apical dendritic fields, in terms of total dendritic length, number of oblique branches from the apical shaft, and length of terminal branches. Similar, although somewhat less consistent, effects were seen when results were analyzed for between- (CONT vs ALT) and within-subject comparisons (trained vs nontrained hemispheres of REV and PRAC). This finding is compatible with the hypothesis that altered dendritic patterns, with associated synapses, are involved in storage of information from the training experience. The within-subject effects mitigate suggestions that these differences arise from generally acting hormonal or metabolic consequences of the training experience, although the possibility that these effects result from neural activity per se and are unrelated to information storage cannot be excluded.

Adenosine 3',5'-monophosphate analogs promote a circular morphology of cultured Schwannoma cells

Dibutyryl adenosine 3',5'-monophosphate (dibutyrl cycle AMP) and 8-bromo cyclic AMP stimulated cells cultured from a rat Schwannoma to change their morphology from irregularly shaped to flattened circular and hollow circular forms within 30 minutes. The change in shape was specifically effected by analogs of cyclic AMP and cyclic AMP elevating agents, was reversible after removal of these additives, and was prevented by vinblastine and cytochalasin b, but was not affected by actinomycin D or cycloheximide.