Preoperative Alpha-Blocker Therapy in Patients with Missed Preoperative Diagnosis of Extra-Adrenal Retroperitoneal Paraganglioma Undergoing Resection: A Retrospective Study of 167 Cases at a Single Center

INTRODUCTION

Preoperative α-adrenergic blockade is thought to decrease perioperative risks and mortality in surgeries for adrenal pheochromocytoma. However, there are limited data on the efficacy of α-blockers in surgeries for retroperitoneal paragangliomas. The aim of this study was to evaluate the effects of the preoperative α-adrenergic blockade on outcomes in patients undergoing surgery for extra-adrenal retroperitoneal paraganglioma.

METHODS

We searched the clinical database for patients diagnosed with extra-adrenal retroperitoneal paraganglioma by postoperative histopathology in the General Hospital of People's Liberation Army in China from 2000 to 2017. We compared the preoperative status of patients, preoperative examination, preoperative preparation, intraoperative and postoperative cardiovascular events, intake and output, length of stay in the intensive care unit, length of hospital stays, and short-term outcomes between patients who received preoperative treatment with α-adrenergic blockade and those who did not.

RESULTS

Of the 167 patients enrolled in the study, 61 received preoperative α-adrenergic blockade therapy. Intraoperative heart rate elevation and highest heart rate were higher in patients undergoing tumor manipulation with preoperative α-adrenergic blockade than those who did not (p < 0.05). However, there were no significant differences between these 2 groups in terms of intraoperative blood pressure elevation and systolic blood pressure decrease following tumorectomy (p > 0.05). Moreover, there were no significant differences in postoperative complications and outcomes (p > 0.05).

CONCLUSION

Under the current medical practice, resection of extra-adrenal retroperitoneal paraganglioma can be successfully carried out with or without preoperative α-adrenergic blockade.

Functional and pharmacological role of the dopamine D4 receptor and its polymorphic variants

The functional and pharmacological significance of the dopamine D₄ receptor (D₄R) has remained the least well understood of all the dopamine receptor subtypes. Even more enigmatic has been the role of the very prevalent human DRD4 gene polymorphisms in the region that encodes the third intracellular loop of the receptor. The most common polymorphisms encode a D₄R with 4 or 7 repeats of a proline-rich sequence of 16 amino acids (D_4.4R and D_4.7R). DRD4 polymorphisms have been associated with individual differences linked to impulse control-related neuropsychiatric disorders, with the most consistent associations established between the gene encoding D_4.7R and attention-deficit hyperactivity disorder (ADHD) and substance use disorders. The function of D₄R and its polymorphic variants is being revealed by addressing the role of receptor heteromerization and the relatively avidity of norepinephrine for D₄R. We review the evidence conveying a significant and differential role of D_4.4R and D_4.7R in the dopaminergic and noradrenergic modulation of the frontal cortico-striatal pyramidal neuron, with implications for the moderation of constructs of impulsivity as personality traits. This differential role depends on their ability to confer different properties to adrenergic α_2A receptor (α_2AR)-D₄R heteromers and dopamine D₂ receptor (D₂R)-D₄R heteromers, preferentially localized in the perisomatic region of the frontal cortical pyramidal neuron and its striatal terminals, respectively. We also review the evidence to support the D₄R as a therapeutic target for ADHD and other impulse-control disorders, as well as for restless legs syndrome.

β-Adrenergic Contributions to Emotion and Physiology During an Acute Psychosocial Stressor

OBJECTIVE

β-Adrenergic receptor signaling, a critical mediator of sympathetic nervous system influences on physiology and behavior, has long been proposed as one contributor to subjective stress. However, prior findings are surprisingly mixed about whether β-blockade (e.g., propranolol) blunts subjective stress, with many studies reporting no effects. We reevaluated this question in the context of an acute psychosocial stressor with more comprehensive measures and a larger-than-typical sample. We also examined the effects of β-blockade on psychophysiological indicators of sympathetic and parasympathetic nervous system reactivity, given that β-blockade effects for these measures specifically under acute psychosocial stress are not yet well established.

METHODS

In a double-blind, randomized, placebo-controlled study, 90 healthy young adults received 40 mg of the β-blocker propranolol or placebo. Participants then completed the Trier Social Stress Test, which involved completing an impromptu speech and difficult arithmetic in front of evaluative judges. Self-reported emotions and appraisals as well as psychophysiology were assessed throughout.

RESULTS

Propranolol blunted Trier Social Stress Test preejection period reactivity (b = 9.68, p = .003), a marker of sympathetic nervous system activity, as well as salivary α-amylase reactivity (b = -0.50, p = .006). Critically, propranolol also blunted negative, high arousal emotions in response to the stressor (b = -0.22, p = .026), but cognitive appraisals remained intact (b values < -0.17, p values > .10).

CONCLUSIONS

These results provide updated experimental evidence that β-adrenergic blockade attenuates negative, high arousal emotions in response to a psychosocial stressor while also blunting sympathetic nervous system reactivity. Together, these findings shed light on the neurophysiological mechanisms by which stressors transform into the subjective experience we call "stress."Trial Registration: ClinicalTrials.gov Identifier: NCT02972554.

The Adrenergic System in Plastic and Reconstructive Surgery: Physiology and Clinical Considerations

ABSTRACT

The primary organ systems and tissues concerning plastic and reconstructive surgery include the integument, vasculature, subcutis, and peripheral nerves, because these may individually or collectively be injured requiring reconstruction, or indeed be used in reconstruction themselves through grafts, flaps, or anastomoses. Adrenergic receptors are present throughout these anatomic components on the vasculature, adipose, platelets, immune cells, keratinocytes, melanocytes, fibroblasts, peripheral nerves, and tendons. Herein, the influence of adrenergic signaling on the physiology of anatomic components related to plastic surgery is discussed, along with clinical considerations of this systems involvement in procedures, such as free flap reconstruction, skin grafting, fat grafting, and other areas relevant to plastic and reconstructive surgery. Current evidence as well as potential for further investigation is discussed.

Detouring adrenergic stimulation to induce adipose thermogenesis

Harnessing the thermogenic, energy-expending capacity of adipocytes has the potential to combat metabolic disorders. Although β₃-adrenergic receptor agonists are the best-known activators of thermogenesis, they carry considerable cardiovascular risks. A new study demonstrates the ability of G protein-coupled receptor 3 to intrinsically drive adipose thermogenesis independent of β₃-adrenergic receptor signalling.

Phenyl imidazolidin-2-ones antagonize a β-adrenergic-like octopamine receptor in diamondback moth (Plutella xylostella)

BACKGROUND

The diamondback moth (Plutella xylostella) is one of the most destructive lepidopteran pests on cruciferous vegetables. However, resistance has emerged to current chemical and biological insecticides used for P. xylostella control, indicating the necessity of screening new targets on P. xylostella, and finding new insecticides against P. xylostella. In particular, octopamine receptors are representative G protein-coupled receptors found only in invertebrates and are potential targets for identifying novel insecticides.

RESULTS

A β-adrenergic-like octopamine receptor gene (PxOA2B1) was cloned, and its pharmacological characteristics in P. xylostella were studied. The results demonstrated that octopamine could activate the PxOA2B1 receptor, with a half-maximal effective concentration (EC₅₀ ) of 49.5 nm. Amitraz, an insecticide and acaricide, and its metabolite (N-2,4-dimethylphenyl-N'-methylformamidine; DPMF) were also found to act as PxOAB1R agonists. We synthesized phenyl imidazolidin-2-one derivatives 3a-h using DPMF as the lead compound, and compounds 3a-h showed similar antagonist activities as phentolamine, mianserin and chlorpromazine. In particular, 3d, with an EC₅₀ of 25.2 nm, showed very similar antagonist activity to mianserin.

CONCLUSION

This research found that PxOAB1R might be a potential target for P. xylostella control. Phenyl imidazolidin-2-ones could be novel potential antagonists targeted at octopamine receptors and would be useful tools for the design and development of novel insecticides. © 2021 Society of Chemical Industry.

β-Adrenergic blockade in patients with dementia and hip fracture is associated with decreased postoperative mortality

Purpose

Dementia, present in 20% of hip fracture patients, is associated with an almost threefold increase in postoperative mortality risk. These patients have a substantially higher incidence of cardiovascular, respiratory, and cerebrovascular mortality after hip fracture surgery compared to patients without dementia. This study aimed to investigate the association between beta-blocker therapy and postoperative mortality in patients with dementia undergoing hip fracture surgery.

Methods

This nationwide study included all patients in Sweden with the diagnosis of dementia who underwent emergency surgery for a hip fracture between January 2008 and December 2017. Cases where the hip fracture was pathological or conservatively managed were not included. Poisson regression analysis with robust standard errors was performed while controlling for confounders to determine the relationship between beta-blocker therapy and all-cause, as well as cause-specific, postoperative mortality.

Results

A total of 26,549 patients met the study inclusion criteria, of whom 8258 (31%) had ongoing beta-blocker therapy at time of admission. After adjusting for clinically relevant variables, the incidence of postoperative mortality in patients receiving beta-blocker therapy was decreased by 50% at 30 days [adj. IRR (95% CI) 0.50 (0.45–0.54), p < 0.001] and 34% at 90 days [adj. IRR (95% CI) 0.66 (0.62–0.70), p < 0.001]. Cause-specific mortality analysis demonstrated a significant reduction in the incidence of postoperative cardiovascular, respiratory, and cerebrovascular death within 30 and 90 days postoperatively.

Conclusion

Beta-blocker therapy is associated with decreased postoperative mortality in hip fracture patients with dementia up to 90 days after surgery. This finding warrants further investigation.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00068-021-01723-y.

Characterization of Spatio-Temporal Cardiac Action Potential Variability at Baseline and Under β-Adrenergic Stimulation by Combined Unscented Kalman Filter and Double Greedy Dimension Reduction

OBJECTIVE

Elevated spatio-temporal variability of human ventricular repolarization has been related to increased risk for ventricular arrhythmias and sudden cardiac death, particularly under β-adrenergic stimulation ( β-AS). This work presents a methodology for theoretical characterization of temporal and spatial repolarization variability at baseline conditions and in response to β-AS. For any measured voltage trace, the proposed methodology estimates the parameters and state variables of an underlying human ventricular action potential (AP) model by combining Double Greedy Dimension Reduction (DGDR) with automatic selection of biomarkers and the Unscented Kalman Filter (UKF). Such theoretical characterization can facilitate subsequent characterization of underlying variability mechanisms.

MATERIAL AND METHODS

Given an AP trace, initial estimates for the ionic conductances in a stochastic version of the baseline human ventricular O'Hara et al. model were obtained by DGDR. Those estimates served to initialize and update model parameter estimates by the UKF method based on formulation of an associated nonlinear state-space representation and joint estimation of model parameters and state variables. Similarly, β-AS-induced phosphorylation levels of cellular substrates were estimated by the DGDR-UKF methodology. Performance was tested by building an experimentally-calibrated population of virtual cells, from which synthetic AP traces were generated for baseline and β-AS conditions.

RESULTS

The combined DGDR-UKF methodology led to 25% reduction in the error associated with estimation of ionic current conductances at baseline conditions and phosphorylation levels under β-AS with respect to individual DGDR and UKF methods. This improvement was not at the expense of higher computational load, which was diminished by 90% with respect to the individual UKF method. Both temporal and spatial AP variability of repolarization were accurately characterized by the DGDR-UKF methodology.

CONCLUSIONS

A combined DGDR-UKF methodology is proposed for parameter and state variable estimation of human ventricular cell models from available AP traces at baseline and under β-AS. This methodology improves the estimation performance and reduces the convergence time with respect to individual DGDR and UKF methods and renders a suitable approach for computational characterization of spatio-temporal repolarization variability to be used for ascertainment of variability mechanisms and its relation to arrhythmogenesis.

Effects of intraoperative adrenergic administration on postoperative hyperlactatemia in open colon surgery: an observational study

Background

Postoperative Hyperlactatemia (PO-HL) is a frequent condition associated with poor prognosis. In recent years, there has been growing evidence that adrenergic stimulation may contribute to increased lactate levels. The use of adrenergic agonists for the control of intraoperative hypotension is frequent, and its impact on the development of PO-HL is unknown.

Objective

To evaluate whether the use of intraoperative adrenergic agents is associated with the occurrence of PO-HL.

Methods

This was a prospective observational study. The inclusion criteria were undergoing elective open colon surgery, being ≥60 years old and signing informed consent. The exclusion criteria were cognitive impairment, unplanned surgery, and anticipated need for postoperative mechanical ventilation. Baseline and intraoperative variables were collected, and arterial lactate data were collected at baseline and every 6 hours postoperatively for 24 hours. Hyperlactatemia was defined as lactate >2.1 mEq.L^-1.

Results

We studied 28 patients, 61% of whom developed hyperlactatemia. The variables associated with PO-HL in the univariate analysis were anesthetic time, the total dose of intraoperative ephedrine, and lower intraoperative central venous oxygen saturation (ScvO₂). Multivariate analysis confirmed the association between the use of ephedrine (p = 0.004), intraoperative hypotension (p = 0.026), and use of phenylephrine (p = 0.001) with PO-HL.

Conclusions

The use of intraoperative ephedrine, phenylephrine and intraoperative hypotension were independently associated with the development of PO-HL. This finding should lead to new studies in this field, as well as a judicious interpretation of the finding of a postoperative increase in lactate levels.

NCLX pumps up the heat

Mitochondrial Ca2+ signaling is a well-appreciated regulator of cell metabolism and energy production. A major function of mitochondria in brown adipose tissue (BAT) is thermogenesis. Assali et al. offer new insights into how the mitochondrial Ca2+ extrusion mediator NCLX is crucial for BAT survival and thermogenesis.

A point mutation in the β-adrenergic-like octopamine receptor: possible association with amitraz resistance

BACKGROUND

Amitraz is a unique formamidine-class acaricide/insecticide that effectively controls ticks, mites, and insect pests. However, the recent emergence of amitraz-resistant cattle ticks is a serious problem that requires an urgent solution. A nonsynonymous single nucleotide polymorphism (A181T) leading to an amino acid substitution (I61F) in the β-adrenergic-like (β-AL) octopamine receptor (OAR) of amitraz-resistant southern cattle ticks (Rhipicephalus microplus) (RmβAOR) was proposed to be a cause of the amitraz resistance. However, it remains unclear whether this substitution exerts any functional effect on the action of amitraz. To make this clear, the functional role of this mutation was examined using an orthologous OAR (BmOAR2) from the silkworm (Bombyx mori).

RESULTS

Both amitraz and its metabolite N² -(2,4-dimethylphenyl)-N¹ -methyformamidine (DPMF) elevated intracellular cyclic AMP levels as orthosteric OAR agonists in HEK-293 cells stably expressing BmOAR2. The I45F mutant of BmOAR2 (equivalent to I61F in RmβAOR) was generated and tested for its sensitivity to amitraz and DPMF. The assay result showed that the I45F mutation reduces the potency of DPMF to a level similar to that of the endogenous agonist (R)-OA in wild-type BmOAR2.

CONCLUSION

The amino acid substitution found in the first transmembrane segment of RmβAOR most likely causes target-site insensitivity to DPMF, which might contribute to the resistance of R. microplus to amitraz. This needs to be further confirmed using RmβAOR. © 2020 Society of Chemical Industry.

SK Channel Block and Adrenergic Stimulation Counteract Acetylcholine-Induced Arrhythmogenic Effects in Human Atria

There is increasing evidence on the role of the autonomic nervous system in the pathogenesis of atrial fibrillation. Interventions targeting autonomic modulation of atrial electrical activity have been shown to reduce the incidence of atrial arrhythmias. Additionally, recent investigations have proved that pharmacological therapies inhibiting small-conductance calcium-activated potassium (SK) channels are able to lessen cholinergic effects in the atria.In this study we use computational modeling and simulation to test individual and combined effects of SK channel block and adrenergic stimulation in counteracting detrimental effects induced by the parasympathetic neurotransmitter acetylcholine (ACh) on human atrial electrophysiology. Cell and tissue models are built that incorporate descriptions of SK channels as well as of isoproterenol (Iso)- and ACh-mediated regulation of the atrial action potential (AP). Three different cellular AP models, representing a range of physiological AP shapes, are considered and both homogeneous and heterogeneous ACh distributions in atrial tissue are simulated.At the cellular level, SK channel block is demonstrated to partially revert shortening of AP duration (APD) mediated by ACh at various doses, whereas 1 µM Iso has a variable response depending on the AP shape. The combination of SK block and Iso is in all cases able to take APD back to baseline levels, recovering between 82% and 120% of the APD shortening induced by 0.1 µM ACh. At the tissue level, SK block and Iso alone or in combination do not exert remarkable effects on conduction velocity, but the combination of the two is able to notably prolong the ACh-mediated APD shortening, thus increasing the wavelength for reentry.In conclusion, the results from this study support the combination of SK channel block and adrenergic stimulation as a potential option to counteract parasympathetically-mediated proarrhythmic effects in the human atria.

Carvedilol improves glucose tolerance and insulin sensitivity in treatment of adrenergic overdrive in high fat diet-induced obesity in mice

Catecholamine excess reflecting an adrenergic overdrive of the sympathetic nervous system (SNS) has been proposed to link to hyperleptinemia in obesity and may contribute to the development of metabolic disorders. However, relationship between the catecholamine level and plasma leptin in obesity has not yet been investigated. Moreover, whether pharmacological blockade of the adrenergic overdrive in obesity by the third-generation beta-blocker agents such as carvedilol could help to prevent metabolic disorders is controversial and remains to be determined. Using the high fat diet (HFD)-induced obese mouse model, we found that basal plasma norepinephrine, the principal catecholamine as an index of SNS activity, was persistently elevated and highly correlated with plasma leptin concentration during obesity development. Targeting the adrenergic overdrive from this chronic norepinephrine excess in HFD-induced obesity with carvedilol, a third-generation beta-blocker with vasodilating action, blunted the HFD-induced hepatic glucose over-production by suppressing the induction of gluconeogenic enzymes, and enhanced the muscular insulin signaling pathway. Furthermore, carvedilol treatment in HFD-induced obese mice decreased the enlargement of white adipose tissue and improved the glucose tolerance and insulin sensitivity without affecting body weight and blood glucose levels. Our results suggested that catecholamine excess in obesity might directly link to the hyperleptinemic condition and the therapeutic targeting of chronic adrenergic overdrive in obesity with carvedilol might be helpful to attenuate obesity-related metabolic disorders.

C/EBPβ regulates the M2 transcriptome in β-adrenergic-stimulated macrophages

At the M2 terminal of the macrophage activation spectrum, expression of genes is regulated by transcription factors that include STAT6, CREB, and C/EBPβ. Signaling through β-adrenergic receptors drives M2 activation of macrophages, but little is known about the transcription factors involved. In the present study, we found that C/EBPβ regulates the signaling pathway between β-adrenergic stimulation and expression of Arg1 and several other specific genes in the greater M2 transcriptome. β-adrenergic signaling induced Cebpb gene expression relatively early with a peak at 1 h post-stimulation, followed by peak Arg1 gene expression at 8 h. C/EBPβ transcription factor activity was elevated at the enhancer region for Arg 1 at both 4 and 8 h after stimulation but not near the more proximal promoter region. Knockdown of Cebpb suppressed the β-adrenergic-induced peak in Cebpb gene expression as well as subsequent accumulation of C/EBPβ protein in the nucleus, which resulted in suppression of β-adrenergic-induced Arg1 gene expression. Analysis of genome-wide transcriptional profiles identified 20 additional M2 genes that followed the same pattern of regulation by β-adrenergic- and C/EBPβ-signaling. Promoter-based bioinformatic analysis confirmed enrichment of binding motifs for C/EBPβ transcription factor across these M2 genes. These findings pinpoint a mechanism that may be targeted to redirect the deleterious influence of β-adrenergic signaling on macrophage involvement in M2-related diseases such as cancer.

The L-type calcium channel current modulation mechanism: the plot thickens and fogs

Stressful situations provoke the fight-or-flight response, incurring rapid elevation of cardiac output via activation of protein kinase A (PKA). In this issue of the JCI, Yang et al. focus on the L-type calcium channel complex (LTCC), and their findings require reexamination of dogmatic principles. LTCC phosphorylation sites identified and studied to date are dispensable for PKA modulation of LTCC; however, a CaVβ2-CaV1.2 calcium channel interaction is now shown to be required. Yang et al. suggest a new hypothesis that LTCC modulation involves rearrangement of auxiliary proteins within the LTCC. However, we still do not know the targets of PKA that mediate LTCC modulation.

Oil Exposure Impairs In Situ Cardiac Function in Response to β-Adrenergic Stimulation in Cobia (Rachycentron canadum)

Aqueous crude oil spills expose fish to varying concentrations of dissolved polycyclic aromatic hydrocarbons (PAHs), which can have lethal and sublethal effects. The heart is particularly vulnerable in early life stages, as PAH toxicity causes developmental cardiac abnormalities and impaired cardiovascular function. However, cardiac responses of juvenile and adult fish to acute oil exposure remain poorly understood. We sought to assess cardiac function in a pelagic fish species, the cobia (Rachycentron canadum), following acute (24 h) exposure to two ecologically relevant levels of dissolved PAHs. Cardiac power output (CPO) was used to quantify cardiovascular performance using an in situ heart preparation. Cardiovascular performance was varied using multiple concentrations of the β-adrenoceptor agonist isoproterenol (ISO) and by varying afterload pressures. Oil exposure adversely affected CPO with control fish achieving maximum CPO's (4 mW g^-1 Mv) greater than that of oil-exposed fish (1 mW g^-1 Mv) at ISO concentrations of 1 × 10^-6 M. However, the highest concentration of ISO (1 × 10^-5 M) rescued cardiac function. This indicates an interactive effect between oil-exposure and β-adrenergic stimulation and suggests if animals achieve very large increases in β-adrenergic stimulation it could play a compensatory role that may mitigate some adverse effects of oil-exposure in vivo.