The simultaneous occurrence of paraganglioma, Takotsubo syndrome, and Markis type I coronary artery ectasia in the same patient is a rare, high-risk clinical syndrome: a case report.

BACKGROUND: Population-wide, paraganglioma (PGL) is uncommon. The incidence of Takotsubo syndrome (TTS) ranges from 0.5% to 0.9% and also is an exceedingly rare manifestation of PGL. Coronary artery ectasia (CAE) is also uncommon, with an incidence ranging from 1.2% to 4.9%. Herein, we present a case of PGL, TTS, and Markis type I CAE that occured in the same patient. CASE PRESENTATION: A man in his early 40s was admitted to our hospital with a 16-hour history of abdominal colic. Computed tomography and laboratory examination led to the diagnosis of PGL, coronary angiography led to the diagnosis of Markis type I or Chinese type III CAE, and two echocardiographic examinations led to the diagnosis of TTS. When the patient was treated by phenoxybenzamine instead of surgery for the PGL, his blood pressure and glucose level gradually returned to normal. The CAE was treated by thrombolysis, antiplatelet medications, atorvastatin, and myocardial protection therapies. No symptoms of PGL, CAE, or TTS were seen during a 6-month follow-up, and the patient had an excellent quality of life. We confirmed that phenoxybenzamine was the cause of the TTS because paradoxical systolic motion of the apex, inferior wall, left ventricular anterior wall, and interventricular septum were similarly recovered when the PGL was treated by phenoxybenzamine. CONCLUSIONS: To raise awareness of this illness and prevent misdiagnosis, we have herein presented a case of TTS that was brought on by PGL with Markis type I CAE for clinicians' reference. In addition, in clinical practice, we should consider the possibility of a concomitant coronary artery disease even if the TTS is caused by a PGL-induced catecholamine surge.

Comparison of Preoperative Alpha-blockade for Resection of Paraganglioma and Pheochromocytoma.

OBJECTIVE: Phenoxybenzamine (nonselective, noncompetitive alpha-blocker) is the preferred drug for preoperative treatment of pheochromocytoma, but doxazosin (selective, competitive alpha-blocker) may be equally effective. We compared the efficacy of doxazosin vs phenoxybenzamine. METHODS: We conducted a prospective study of patients undergoing pheochromocytoma or paraganglioma resection by randomizing pretreatment with phenoxybenzamine or doxazosin at a single tertiary referral center. The high cost of phenoxybenzamine led to high crossover to doxazosin. Randomization was halted, and a consecutive historical cohort of phenoxybenzamine patients was included for a case-control study design. The efficacy of alpha-blockade was assessed with preinduction infusion of incremental doses of phenylephrine. The primary outcomes were mortality, cardiovascular complications, and intensive care unit admission. The secondary outcomes were hemodynamic instability index (proportion of operation outside of hemodynamic goals), adequacy of blockade by the phenylephrine titration test, and drug costs. RESULTS: Twenty-four patients were prospectively enrolled (doxazosin, n = 20; phenoxybenzamine, n = 4), and 15 historical patients treated with phenoxybenzamine were added (total phenoxybenzamine, n = 19). No major cardiovascular complications occurred in either group. The phenylephrine dose-response curves showed less blood pressure rise in the phenoxybenzamine than in the doxazosin group (linear regression coefficient = 0.008 vs 0.018, P = .01), suggesting better alpha-blockade in the phenoxybenzamine group. The median hemodynamic instability index was 14% vs 13% in the phenoxybenzamine and doxazosin groups, respectively (P = .56). The median highest daily cost of phenoxybenzamine was $442.20 compared to $5.06 for doxazosin. CONCLUSION: Phenoxybenzamine may blunt intraoperative hypertension better than doxazosin, but this difference did not translate to fewer cardiovascular complications and is offset by a considerably increased cost.

Ectopic Cushing's syndrome associated with a pheochromocytoma in a dog: a case report.

BACKGROUND: Ectopic Cushing's syndrome (ECS) associated with malignant tumors, such as small cell lung carcinoma, bronchial carcinoids, and pheochromocytoma, has been reported in human medicine. However, ECS related to pheochromocytoma has not been reported in dogs. CASE PRESENTATION: An 11-year-old castrated, male Scottish terrier was diagnosed with a left adrenal mass. Cushing's syndrome was suspected based on clinical signs, including pot belly, polyuria, polydipsia, bilateral alopecia, recurrent pyoderma, and calcinosis cutis. Cushing's syndrome was diagnosed on the basis of consistent clinical signs and repeated adrenocorticotropic hormone (ACTH) stimulation tests. In addition, tests for fractionated plasma metanephrine/normetanephrine suggested a pheochromocytoma. Unilateral adrenalectomy was performed after medical management with trilostane and phenoxybenzamine. Histopathology confirmed a diagnosis of pheochromocytoma without cortical lesions. After surgery, fractionated metanephrine/normetanephrine and the findings of low-dose dexamethasone suppression and ACTH stimulation tests were within the normal ranges without any medication. There were no clinical signs or evidence of recurrence and metastasis on thoracic and abdominal X-rays and ultrasonography up to 8 months after surgery. CONCLUSIONS: Pheochromocytoma should be considered a differential diagnosis for dogs with Cushing's syndrome with an adrenal tumor. A good prognosis can be expected with prompt diagnosis and surgical intervention.

Favorable outcome of pheochromocytoma in a dog with atypical Cushing's syndrome and diabetes mellitus following medical treatment: a case report.

BACKGROUND: Pheochromocytoma (PCC) has poor prognosis and adrenalectomy is hard to be performed, in case of caudal vena cava invasion. The long-term administration of phenoxybenzamine in PCC has not been reported in dogs. CASE PRESENTATION: A 14-year-old castrated male Poodle dog presented with an abdominal mass. On physical examination, hypertension, increased lens opacity, calcinosis cutis, generalized alopecia, and systolic murmur were observed. Serum chemistry and urinalysis profiles revealed hyperglycemia, hypercholesterolemia, elevated liver enzymes, and glucosuria. Abdominal ultrasonography showed a right adrenal mass with invasion of the caudal vena cava, which was cytologically diagnosed as suspected PCC. An adrenal mass (width × height × length, 28 × 26 × 48 mm3) was found on computed tomography and diagnosed as PCC with increased plasma metanephrines and normetanephrines. An adrenocorticotropin hormone stimulation test showed elevated adrenal hormones (androstenedione, estradiol, progesterone, and 17-OH progesterone) with normal cortisol, compatible with atypical Cushing's syndrome. The dog was managed with trilostane, phenoxybenzamine, and insulin therapy. Glycosylated hemoglobin and fructosamine levels gradually decreased, and hypertension resolved. In the 10-month follow-up period, the liver enzymes levels gradually decreased, and the clinical signs of the dog were well-controlled without deterioration. CONCLUSIONS: This case report describes long-term medical management without adrenalectomy of PCC complicated with atypical Cushing's syndrome and DM.

Preparation of a thiols ß-cyclodextrin/gold nanoparticles-coated open tubular column for capillary electrochromatography enantioseparations.

Inspired by the distinct chemical and physical properties of nanoparticles, here a novel open-tubular capillary electrochromatography column was prepared by electrostatic assembly of poly(diallydimethylammonium chloride) onto the inner surface of a fused-silica capillary, followed by self-adsorption of negatively charged SH-ß-cyclodextrin/gold nanoparticles. The formation of the SH-ß-cyclodextrin/gold nanoparticles coated capillary was confirmed and characterized by scanning electron microscopy and energy dispersive spectrometry. The results of scanning electron microscopy and energy dispersive spectrometry studies indicated that SH-ß-cyclodextrin/gold nanoparticles were successfully coated on the inner wall of the capillary column. The performance of the SH-ß-cyclodextrin/gold nanoparticles coated capillary was validated by the analysis of six pairs of chiral drugs, namely zopiclone, carvedilol, salbutamol, terbutaline sulfate, phenoxybenzamine hydrochloride, and ibuprofen. Satisfactory enantioseparation results were achieved, confirming the use of gold nanoparticles as the support could enhance the phase ratio of the open-tubular capillary column. Additionally, the stability and reproducibility of the SH-ß-cyclodextrin/gold nanoparticles coated capillary column were also investigated. Then, this proposed method was well validated with good linearity (≥0.999), recovery (90.0-93.5%) and repeatability, and was successfully used for enantioseparation of ibuprofen in spiked plasma samples, which indicated the new column's potential usage in biological analysis.

The pharmacologic characterization of allosteric molecules: Gq protein activation.

Context: Drugs such as positive allosteric modulators (PAMs) produce complex behaviors when acting on tissues in different physiological contexts in vivo. Objective: This study describes the use of functional assays of varying receptor sensitivity to unveil the various behaviors of PAMs and thus quantify allosteric effect through system independent scales. Materials and methods: Muscarinic receptor activation with acetylcholine (ACh) was used to the demonstrate activity of the PAM agonist 1-(4-methoxybenzyl)-4-oxo-1,4-dihydroquinoline-3-carboxylic acid, Benzyl quinolone carboxylic acid (BQCA) in terms of direct agonism, potentiation of ACh affinity, and ACh efficacy. Concentration-response curves were fit to the functional allosteric model to yield indices of agonism (τB), effects on affinity (α cooperativity), and efficacy (ß cooperativity). Results: It is shown that a highly sensitive functional assay revealed the direct efficacy of BQCA as an agonist and relatively insensitive cells (produced by chemical alkylation of muscarinic receptor with phenoxybenzamine) revealed a positive allosteric effect of BQCA on ACh efficacy. A wide range of functional assay sensitivities produced a complex pattern of behavior for BQCA all of which was accurately quantified through the system-independent parameters of the functional allosteric model. Conclusions: The study of complex allosteric molecules in a range of functional assays of varying sensitivity allows the measurement of the complete array of activities of these molecules on receptors and also better predicts which will be seen with these in vivo where a range of tissue sensitivities is encountered.

Discovery of novel phenoxybenzamide analogues as Raf/HDAC dual inhibitors.

Histone deacetylase (HDAC) inhibitors as an important epigenetic therapeutic strategy affect signaling networks and act synergistically with kinase inhibitors for the treatment of cancer. Herein we presented a series of novel phenoxybenzamide analogues with inhibition of Raf and HDAC. Among them, compound 10e showed potent antiproliferative activities against Hepg2 and MDA-MB-468 in cellular assays. This work may lay the foundation for developing novel dual Raf/HDAC inhibitors as potential anticancer therapeutics.

Selective Versus Non-selective α-Blockade Prior to Laparoscopic Adrenalectomy for Pheochromocytoma.

BACKGROUND: The optimal preoperative α-blockade strategy is debated for patients undergoing laparoscopic adrenalectomy for pheochromocytomas. We evaluated the impact of selective versus non-selective α-blockade on intraoperative hemodynamics and postoperative outcomes. METHODS: We identified patients having laparoscopic adrenalectomy for pheochromocytomas from 2001 to 2015. As a marker of overall intraoperative hemodynamics, we combined systolic blood pressure (SBP) > 200, SBP < 80, SBP < 80 and >200, pulse > 120, vasopressor infusion, and vasodilator infusion into a single variable. Similarly, the combination of vasopressor infusion in the post-anesthesia care unit (PACU) and the need for intensive care unit (ICU) admission provided an overview of postoperative support. RESULTS: We identified 52 patients undergoing unilateral laparoscopic adrenalectomy for pheochromocytoma. Selective α-blockade (i.e. doxazosin) was performed in 35 % (n = 18) of patients, and non-selective blockade with phenoxybenzamine was performed in 65 % (n = 34) of patients. Demographics and tumor characteristics were similar between groups. Patients blocked selectively were more likely to have an SBP < 80 (67 %) than those blocked with phenoxybenzamine (35 %) (p = 0.03), but we found no significant difference in overall intraoperative hemodynamics between patients blocked selectively and non-selectively (p = 0.09). However, postoperatively, patients blocked selectively were more likely to require additional support with vasopressor infusions in the PACU or ICU admission (p = 0.02). Hospital stay and complication rates were similar. CONCLUSION: Laparoscopic adrenalectomy for pheochromocytoma is safe regardless of the preoperative α-blockade strategy employed, but patients blocked selectively may have a higher incidence of transient hypotension during surgery and a greater need for postoperative support. These differences did not result in longer hospital stay or increased complications.

Dexmedetomidine Inhibits Phenylephrine-induced Contractions via Alpha-1 Adrenoceptor Blockade and Nitric Oxide Release in Isolated Rat Aortae.

The goal of this in vitro study was to examine the effect of the alpha-2 adrenoceptor agonist dexmedetomidine on phenylephrine (alpha-1 adrenoceptor agonist)-induced contraction in isolated rat aortae and to elucidate the associated cellular mechanisms, with a particular focus on alpha-1 adrenoceptor antagonism. Dexmedetomidine dose-response curves were generated in isolated endothelium-intact and endothelium-denuded rat aortae precontracted with phenylephrine or 5-hydroxytryptamine. Endothelium-denuded aortic rings were pretreated with either dexmedetomidine or the reversible alpha-1 adrenoceptor antagonist phentolamine, followed by post-treatment with the irreversible alpha-1 adrenoceptor blocker phenoxybenzamine. Control rings were treated with phenoxybenzamine alone. All rings were repeatedly washed with Krebs solution to remove all pretreatment drugs, including phenoxybenzamine, phentolamine and dexmedetomidine. Phenylephrine dose-response curves were then generated. The effect of rauwolscine on the dexmedetomidine-mediated change in phenylephrine-induced endothelial nitric oxide synthase (eNOS) phosphorylation in human umbilical vein endothelial cells was examined using western blotting. The magnitude of the dexmedetomidine-mediated inhibition of phenylephrine-induced contraction was higher in endothelium-intact aortae than in endothelium-denuded aortae or endothelium-intact aortae treated with Nω-nitro-L-arginine methyl ester. However, dexmedetomidine did not significantly alter 5-hydroxytryptamine-induced contraction. In further experiments, prazosin attenuated dexmedetomidine-induced contraction. Additionally, pretreatment with either dexmedetomidine plus phenoxybenzamine or phentolamine plus phenoxybenzamine produced greater phenylephrine-induced contraction than phenoxybenzamine alone, suggesting that dexmedetomidine protects aortae from the alpha-1 adrenoceptor blockade induced by phenoxybenzamine. Rauwolscine attenuated the dexmedetomidine-mediated enhancement of phenylephrine-induced eNOS phosphorylation. Taken together, these results suggest that dexmedetomidine attenuates phenylephrine-induced contractions via alpha-1 adrenoceptor blockade and endothelial nitric oxide release in the isolated rat aorta.

Molecular Mechanisms of Action of M5 Muscarinic Acetylcholine Receptor Allosteric Modulators.

Recently, the first subtype-selective allosteric modulators of the M5 muscarinic acetylcholine receptor (mAChR) have been described, but their molecular mechanisms of action remain unknown. Using radioligand-binding and functional assays of inositol phosphate (IP) accumulation and Ca(2+) mobilization in a recombinant cell line stably expressing the human M5 mAChR, we investigated the effects of the positive allosteric modulator (PAM), ML380, and negative allosteric modulator, ML375. In functional assays, ML380 caused robust enhancements in the potency of the full agonists, acetylcholine (ACh), carbachol, and oxotremorine-M, while significantly increasing the maximal response to the partial agonist, pilocarpine. ML380 also demonstrated direct allosteric agonist activity. In contrast, ML375 displayed negative cooperativity with each of the agonists in a manner that varied with the pathway investigated and progressively reduced the maximal pilocarpine response. Radioligand-binding affinity cooperativity estimates were consistent with values derived from functional assays in some instances but not others, suggesting additional allosteric effects on orthosteric ligand efficacy. For ML375 this was confirmed in IP assays performed after reduction of receptor reserve by the alkylating agent, phenoxybenzamine, as it reduced the maximal ACh response. In contrast, ML380 enhanced only ACh potency after receptor alkylation, with no effect on maximal response, consistent with studies of the M1 mAChR with the prototypical PAM, BQZ12. Interaction studies between ML380 and ML375 also indicated that they most likely used an overlapping allosteric site. Our findings indicate that novel small-molecule modulators of the M5 mAChR display mixed mechanisms of action compared with previously characterized modulators of other mAChRs.

Anti-tumor activity of phenoxybenzamine hydrochloride on malignant glioma cells.

Phenoxybenzamine hydrochloride (PHEN) is a selective antagonist of both α-adrenoceptor and calmodulin that exhibits anticancer properties. The aim of this study was to explore the anti-tumor function of PHEN in glioma. Cell proliferation assay was used to assess glioma cell growth. Migration and invasion capacity of glioma cells was monitored by wound-healing and transwell assay, respectively. Neurosphere formation test was adopted for the tumorigenesis of glioma cells, which was also confirmed by soft agar cloning formation test in vitro and a nude mouse model in vivo. Finally, we explored the potential pathway utilized by PHEN using Western blot and immunofluoresce staining. PHEN exhibited a significant inhibitory effect on the proliferation of both U251 and U87MG glioma cell lines in a positive dose-dependent manner. PHEN apparently attenuated the malignancy of glioma in terms of migration and invasion and also suppressed the tumorigenic capacity both in vitro and in vivo. Mechanism study showed that PHEN promoted tumor suppression by inhibiting the TrkB-Akt pathway. The results of the present study demonstrated that PHEN suppressed the proliferation, migration, invasion, and tumorigenesis of glioma cells, induced LINGO-1 expression, and inhibited the TrkB-Akt pathway, which may prove to be the mechanisms underlying the anti-tumor effect of PHEN on glioma cells.

Hemodynamic Stability During Pheochromocytoma Resection: Lessons Learned Over the Last Two Decades.

BACKGROUND: Ideal perioperative management of pheochromocytomas/paragangliomas (pheo) is a subject of debate and can be highly variable. The purpose of this study was to identify potential predictive factors of hemodynamic instability during pheo resection. METHODS: A retrospective review of pheo resections from 1992 to 2013 was undertaken. Intraoperative hemodynamics, patient demographics, tumor characteristics, and perioperative management were examined. Postoperative intensive-care admission, myocardial infarction, stroke, and 30-day mortality were reviewed. Linear regression was used to analyze factors influencing intraoperative hemodynamics. RESULTS: During the 20-year study period, 100 patients underwent pheo resection. Postoperative morbidity and mortality was significantly reduced (p = 0.003) in the last 10 years of practice, and there was a trend towards greater morbidity and mortality with intraoperative hemodynamic instability (p = 0.06). The preoperative dose of phenoxybenzamine and the number of laparoscopic procedures has increased in the last decade [59 mg (95 % CI 32-108) to 106 mg (95 % CI 91-124), p = 0.008, and 27 vs. 54 %, p = 0.05, respectively]. Increased preoperative phenoxybenzamine dose was a significant predictor of improved intraoperative hemodynamic stability (p = 0.01). Lack of intraoperative magnesium use resulted in greater hemodynamic instability as preoperative systolic blood pressure increased (p = 0.002). CONCLUSIONS: Postoperative outcomes following pheo resection have improved over the last two decades. Preoperative α-blockade plays a significant role in improving intraoperative hemodynamics and post-op outcomes. Increased doses of phenoxybenzamine and utilization of laparoscopic approaches have likely contributed to improved outcomes in the last decade. Intraoperative magnesium use may provide protection against hemodynamic instability and warrants further study.

Analgesic effect of GT-0198, a structurally novel glycine transporter 2 inhibitor, in a mouse model of neuropathic pain.

This study was conducted to identify the characteristic pharmacological features of GT-0198 that is phenoxymethylbenzamide derivatives. GT-0198 inhibited the function of glycine transporter 2 (GlyT2) in human GlyT2-expressing HEK293 cells and did not bind various major transporters or receptors of neurotransmitters in a competitive manner. Thus, GT-0198 is considered to be a comparatively selective GlyT2 inhibitor. Intravenous, oral, and intrathecal injections of GT-0198 decreased the pain-related response in a model of neuropathic pain with partial sciatic nerve ligation. This result suggests that GT-0198 has an analgesic effect. The analgesic effect of GT-0198 was abolished by the intrathecal injection of strychnine, a glycine receptor antagonist. Therefore, GT-0198 is considered to exhibit its analgesic effect via the activation of a glycine receptor by glycine following presynaptic GlyT2 inhibition in the spinal cord. In summary, GT-0198 is a structurally novel GlyT2 inhibitor bearing a phenoxymethylbenzamide moiety with in vivo efficacy in behavioral models of neuropathic pain.

Predictors of hemodynamic instability during surgery for pheochromocytoma.

BACKGROUND: Resection of pheochromocytoma is often associated with hemodynamic instability (HDI). We examined patient and tumor factors that may influence HDI. The effect of pretreatment with nonselective α blockade phenoxybenzamine (PXB) versus selective α blockade on HDI and outcomes was also evaluated. METHODS: The records of 91 patients who underwent adrenalectomy between 2002 and 2013 were retrospectively reviewed. HDI was determined by number of intraoperative episodes of systolic blood pressure (SBP) > 200 mmHg, those greater than or less than 30 % of baseline, heart rate > 110 bpm, and the need for postoperative vasopressors. Fishers exact, t test and regressions were performed. RESULTS: Among 91 patients, 78 % received PXB, 18 % selective α blockade and 4 % no adrenergic blockade. Patient demographics, tumor factors and surgical approach were similar among the blockade groups. On multivariate analysis, increasing tumor size was associated with a significant rise in the number of episodes of SBP > 30 % [rate ratio (RR) 1.40] and an increased postoperative vasopressor requirement [odds ratio (OR) 1.23]. Open adrenalectomy and use of selective blockade were associated with an increased number of episodes of SBP > 200 mmHg (RR 27.8 and RR 20.9, respectively). Open adrenalectomy was also associated with increased readmissions (OR 12.3), complications (OR 5.6), use of postoperative vasopressors (OR 4.4) and hospital stay (4.6 days longer). There were no differences in other HDI measurements or postoperative outcomes among the blockade groups. CONCLUSIONS: Tumor size, open adrenalectomy, and type of α blockade were associated with intraoperative HDI during pheochromocytoma resection. Selective blockade was associated with significantly more episodes of intraoperative hypertension but no perioperative adverse outcomes.

Prospective study to compare peri-operative hemodynamic alterations following preparation for pheochromocytoma surgery by phenoxybenzamine or prazosin.

BACKGROUND: Prospective studies comparing the efficacy of selective versus nonselective alpha blockers for preoperative preparation of pheochromocytoma (PCC) are lacking. In this prospective nonrandomized study, we compared the outcome of preoperative preparation with phenoxybenzamine (PBZ) and prazosin (PRZ) in terms of perioperative hemodynamic alterations. METHODS: The study was conducted at a tertiary referral center from July 2010 to December 2012. Thirty-two patients with PCC underwent operation after adequate preparation with PBZ (n = 15) or PRZ (n = 17). Five pediatric and adolescent patients were excluded because of different hemodynamics in this population. Perioperative monitoring was done for pulse rate (PR) and blood pressure(BP) alterations, occurrence of arrhythmias, and time taken to achieve hemodynamic stability. Groups were compared with the Mann-Whitney test, Student's t test, and the χ2 test as applicable. RESULTS: Patients in the two groups were similar in age,gender, 24 h urinary metanephrine and normetanephrine levels, and type of procedure. Patients prepared with PRZ had significantly more intraoperative episodes of transient hypertension (systolic BP ≥ 160 mmHg) and hypertensive urgency (BP >180/110 mmHg) (p 0.02, 0.03, respectively). More patients receiving PRZ suffered from transient severe hypertension (SBP ≥ 220 mmHg) (p 0.03). The PRZ group also had more median maximum SBP (233 mmHg vs PBZ 181.5 mmHg) (p = 0.01) and lesser median minimum SBP (71 mmHg vs PBZ 78 mmHg) (p 0.03). No significant differences were found between the study groups for changes in PR, postoperative BP alterations,occurrence of arrhythmias, and time taken to achieve hemodynamic stability. CONCLUSIONS: PBZ was found superior to PRZ in having fewer intraoperative hemodynamic fluctuations.

Phenoxybenzamine is neuroprotective in a rat model of severe traumatic brain injury.

Phenoxybenzamine (PBZ) is an FDA approved α-1 adrenergic receptor antagonist that is currently used to treat symptoms of pheochromocytoma. However, it has not been studied as a neuroprotective agent for traumatic brain injury (TBI). While screening neuroprotective candidates, we found that phenoxybenzamine reduced neuronal death in rat hippocampal slice cultures following exposure to oxygen glucose deprivation (OGD). Using this system, we found that phenoxybenzamine reduced neuronal death over a broad dose range (0.1 µM-1 mM) and provided efficacy when delivered up to 16 h post-OGD. We further tested phenoxybenzamine in the rat lateral fluid percussion model of TBI. When administered 8 h after TBI, phenoxybenzamine improved neurological severity scoring and foot fault assessments. At 25 days post injury, phenoxybenzamine treated TBI animals also showed a significant improvement in both learning and memory compared to saline treated controls. We further examined gene expression changes within the cortex following TBI. At 32 h post-TBI phenoxybenzamine treated animals had significantly lower expression of pro-inflammatory signaling proteins CCL2, IL1ß, and MyD88, suggesting that phenoxybenzamine may exert a neuroprotective effect by reducing neuroinflammation after TBI. These data suggest that phenonxybenzamine may have application in the treatment of TBI.

Surgery for phaeochromocytomas and paragangliomas: Current practice in the United Kingdom.

INTRODUCTION: There is wide variability in the perioperative management of phaeochromocytoma and paraganglioma (PPGL) in different centres. This study aimed to summarise the management of PPGLs as reported in the United Kingdom Registry for Endocrine and Thyroid Surgery (UKRETS) database and to determine current perioperative management of PPGLs by surveying UK clinicians. METHODS: Data recorded on UKRETS from 2005 to 2021 were subjected to descriptive analyses. British Association of Endocrine and Thyroid Surgeons members were invited to participate in an open survey relating to the perioperative management of patients with PPGLs. RESULTS: A total of 2,007 operations for PPGL from 49 participating centres were included. The median annual workload in each centre was four cases. Operations were performed predominantly laparoscopically (69%). The median length of stay (4 days) was the same in groups of surgeons stratified by volume. The survey had 29 respondents from 22 centres across the UK, and a formal protocol for perioperative management exists in 48% of the centres. Phenoxybenzamine (72%) was preferred for alpha-blockade. The practice of admitting patients for optimisation from 1 to 7 days before the day of surgery was common (62%). Central venous pressure and blood glucose monitoring were mentioned as routine intraoperative adjuncts by 72% of the responders. CONCLUSIONS: There is significant variation in the workload and perioperative management of PPGLs in the UK. This is potentially detrimental to patient outcomes and a consensus document might be beneficial to harmonise practice across the UK.

Kinetics of 5-HT2B receptor signaling: profound agonist-dependent effects on signaling onset and duration.

The kinetics of drug-receptor interactions can profoundly influence in vivo and in vitro pharmacology. In vitro, the potencies of slowly associating agonists may be underestimated in assays capturing transient signaling events. When divergent receptor-mediated signaling pathways are evaluated using combinations of equilibrium and transient assays, potency differences driven by kinetics may be erroneously interpreted as biased signaling. In vivo, drugs with slow dissociation rates may display prolonged physiologic effects inconsistent with their pharmacokinetic profiles. We evaluated a panel of 5-hydroxytryptamine2B (5-HT2B) receptor agonists in kinetic radioligand binding assays and in transient, calcium flux assays, and inositol phosphate accumulation assays; two functional readouts emanating from Gαq-mediated activation of phospholipase C. In binding studies, ergot derivatives demonstrated slow receptor association and dissociation rates, resulting in significantly reduced potency in calcium assays relative to inositol phosphate accumulation assays. Ergot potencies for activation of extracellular signal-regulated kinases 1 and 2 were also highly time-dependent. A number of ergots produced wash-resistant 5-HT2B signaling that persisted for many hours without appreciable loss of potency, which was not explained simply by slow receptor-dissociation kinetics. Mechanistic studies indicated that persistent signaling originated from internalized or sequestered receptors. This study provides a mechanistic basis for the long durations of action in vivo and wash-resistant effects in ex vivo tissue models often observed for ergots. The 5-HT2B agonist activity of a number of ergot-derived therapeutics has been implicated in development of cardiac valvulopathy in man. The novel, sustained nature of ergot signaling reported here may represent an additional mechanism contributing to the valvulopathic potential of these compounds.