Acute elevation of plasma non-esterified fatty acids increases pulse wave velocity and induces peripheral vasodilation in humans in vivo

Therapeutic Options for Migraines in the Microsurgical Patient: A Scoping Review

BACKGROUND

There exists an increasing array of treatments proposed to prevent, alleviate, and abort symptoms of a migraine; however, for patients who undergo reconstructive microsurgery, caution must be taken to preserve vascular integrity. This study is the first-to-date scoping review of vascular and bleeding risk of current migraine therapies, with the purpose of identifying potential therapeutic agents for postoperative migraine management appropriate for microsurgical patients.

METHODS

Currently available migraine therapeutics were compiled from the UpToDate software system and the American Academy of Family Physicians. A PubMed literature review was performed for each therapeutic's effect on bleeding or vascular involvement. Data were compiled into tables of abortive, symptom-controlling and prophylactic, and nonpharmacologic treatments. Expert microsurgeons reviewed the data to provide recommendations for optimized patient care.

RESULTS

Triptans and other ergot derivatives demonstrated strong evidence of vasoconstriction and were greatly advised against for immediate postmicrosurgical use. Novel pharmaceutical therapies such as lasmiditan and calcitonin gene-related peptide antagonists have no literature indicating potential for vasoconstriction or hematoma and remain an investigational option for abortive medical treatment. For symptom control, acetaminophen appears the safest option, with clinical judgment and further research needed for use of nonsteroidal antiinflammatory drugs. Alternative treatment techniques may include migraine prophylaxis with botulinum toxin injection or nutraceutical treatment by means of magnesium supplementation or coenzyme Q10 administration, minimizing the need for additional medication in the postoperative setting.

CONCLUSIONS

Patients undergoing reconstructive microsurgery have a unique medical profile limiting the therapeutic options available to treat migraines. This review provides preliminary evidence to be considered as a guide for prescribing therapeutics for migraine in the postoperative setting.

Sonographic Measurement of Mesenteric Fat Thickness Is a Better Predictor of Aortic Stiffness Compared With Conventional Obesity Indexes

Increased aortic stiffness is closely associated with central obesity whereas mesenteric fat is the key adipose tissue in central obesity. We investigated the associations of mesenteric fat thickness with aortic stiffness, with comparison to conventional obesity measures. We used ultrasound to measure mesenteric, pre-peritoneal and subcutaneous fat thickness, carotid intima-media thickness (CIMT) and carotid-femoral pulse wave velocity (c-f PWV), an index of central aortic stiffness. Anthropometric indexes, blood pressure, fasting plasma glucose and lipid profile were measured. One hundred forty-seven healthy volunteers (age [mean ± standard deviation]: 43.2 ± 13.3 y; 41.5% men) were assessed. On univariate analysis, mesenteric, preperitoneal and subcutaneous fat thickness, body mass index (BMI), waist circumference (WC), waist/hip ratio (WHR) and waist/height ratio (WHtR) were associated with c-f PWV with or without adjustment for age. The mesenteric fat thickness had the highest correlation coefficient (r = 0.48, p < 0.001) with c-f PWV among all the investigated obesity indexes. Using multiple linear regression analysis, only mesenteric fat thickness remained to be an independent determinant of c-f PWV after adjustments for other abdominal fat thickness, anthropometric and metabolic indexes and CIMT. In conclusion, mesenteric fat thickness is an independent risk factor for aortic stiffness and has a stronger association with aortic stiffness compared with conventional obesity indexes.

Phosphorylation of GSK-3β mediates intralipid-induced cardioprotection against ischemia/reperfusion injury

BACKGROUND

Intralipid (Sigma, St. Louis, MO), a brand name for the first safe fat emulsion for human use, has been shown to be cardioprotective. However, the mechanism of this protection is not known. The authors investigated the molecular mechanism(s) of Intralipid-induced cardioprotection against ischemia/reperfusion injury, particularly the role of glycogen synthase kinase-3β (GSK-3β) and mitochondrial permeability transition pore in this protective action.

METHODS

In vivo rat hearts or isolated Langendorff-perfused mouse hearts were subjected to ischemia followed by reperfusion with Intralipid (1% in ex vivo and one bolus of 20% in in vivo) or vehicle. The hemodynamic function, infarct size, threshold for the opening of mitochondrial permeability transition pore, and phosphorylation levels of protein kinase B (Akt)/extracellular signal regulating kinase (ERK)/GSK-3β were measured.

RESULTS

Administration of Intralipid at the onset of reperfusion resulted in approximately 70% reduction in infarct size in the in vivo rat model. Intralipid also significantly improved functional recovery of isolated Langendorff-perfused mouse hearts as the rate pressure product was increased from 2,999 ± 863 mmHg*beats/min in the control group to 13,676 ± 611 mmHg*beats/min (mean±SEM) and the infarct size was markedly smaller (18.3 ± 2.4% vs. 54.8 ± 2.9% in the control group, P < 0.01). The Intralipid-induced cardioprotection was fully abolished by LY294002, a specific inhibitor of PI3K, but only partially by PD98059, a specific ERK inhibitor. Intralipid also increased the phosphorylation levels of Akt/ERK1/glycogen synthase kinase-3β by eightfold, threefold, and ninefold, respectively. The opening of mitochondrial permeability transition pore was inhibited by Intralipid because calcium retention capacity was higher in the Intralipid group (274.3 ± 8.4 nM/mg vs. 168.6 ± 9.6 nM/mg in the control group).

CONCLUSIONS

Postischemic treatment with Intralipid inhibits the opening of mitochondiral permeability transition pore and protects the heart through glycogen synthase kinase-3β via PI3K/Akt/ERK pathways.

Acute elevation of triglycerides increases left ventricular contractility and alters ventricular-vascular interaction

Acute elevation of circulating lipids, such as the postprandial state, contributes to increased cardiovascular risk. However, the effect of acutely elevated triglycerides on arterial and left ventricular function is not completely understood. We aimed to assess whether an acute increase in triglycerides affects ventricular-vascular interaction. Fifteen healthy men (age, 49 ± 8 yr) underwent blinded, randomized infusion of saline and intravenous fat emulsion to acutely raise plasma triglycerides. All subjects underwent both randomization trials, in random order on two separate days. Ventricular-vascular interaction measures were recorded by tonometry (central blood pressure) and echocardiography (left ventricular volumes, strain, and strain rate) at baseline and after 1 h infusion. Net ventricular-vascular interaction was defined by the effective arterial elastance (E(A))-to-left ventricular end-systolic elastance (E(LV)) ratio (E(A)/E(LV)). When compared with saline, the infusion of intravenous fat emulsion increased triglycerides and free fatty acids (ΔP < 0.001 for both) and improved left ventricular contractility (ΔE(LV), end-systolic volume and strain rate; P < 0.05 for all). However, arterial function was unchanged (ΔE(A), brachial and central blood pressure; P > 0.05 for all). Overall, E(A)/E(LV) was decreased by an infusion of intravenous fat emulsion (P = 0.004) but not saline (P > 0.05, P = 0.001 for Δ between trials). We conclude that intravenous fat emulsion and acute elevation of blood lipids (including triglycerides and free fatty acids) alter ventricular-vascular interaction by increasing left ventricular contractility without affecting arterial load. These findings may have implications for cardiovascular responses to parenteral nutrition.

Non-esterified fatty acids increase arterial pressure via central sympathetic activation in humans

Previous studies have shown that acute increases in plasma NEFAs (non-esterified fatty acids) raise SVR (systemic vascular resistance) and BP (blood pressure). However, these studies have failed to distinguish between CNS (central nervous system) mechanisms that raise sympathetic activity and paracrine mechanisms that increase SVR directly, independent of CNS involvement. The aim of the present study was to directly determine whether the sympathetic nervous system contributes to the pressor response to NEFAs. On 2 days separated by at least 2 weeks, 17 lean healthy volunteers (ten male/seven female; age, 22±1 years; body mass index, 23±1 kg/m2; values are means±S.E.M.) received a 4-h intravenous infusion of 20% Intralipid® or placebo (in a single-blind randomized balanced order). MSNA (muscle sympathetic nerve activity), HR (heart rate), BP (oscillometric brachial measurement) and (cardiac output; acetylene rebreathing) were measured before and throughout infusion. The change in HR (+8.2±1.0 and +2.4±1.2 beats/min), systolic BP (+14.0±1.6 and +3.2±2.5 mmHg) and diastolic BP (+8.2±1.0 and −0.1±1.7 mmHg) were significantly greater after the 4-h infusion of Intralipid® compared with placebo (P<0.001). The change in BP with Intralipid® resulted from an increase in SVR (/mean arterial pressure; P<0.001) compared with baseline, without a change in . MSNA burst frequency increased during Intralipid® infusion compared with baseline (+4.9±1.3 bursts/min; P<0.05), and total MSNA (frequency×amplitude) was augmented 65% (P<0.001), with no change during placebo infusion. Lipid infusion increased insulin, aldosterone and F2-isoprostane, but not leptin, concentrations. On the basis of the concomitant increase in BP, MSNA and SVR, we conclude that central sympathetic activation contributes to the pressor response to NEFAs.

Intra-arterial AICA-riboside administration induces NO-dependent vasodilation in vivo in human skeletal muscle

In animal models, administration of the adenosine analog AICA-riboside has shown beneficial effects on ischemia-reperfusion injury and glucose homeostasis. The vascular and/or metabolic effects of AICA-riboside administration in humans remain to be established. AICA-riboside was infused intra-arterially in four different dosages up to 8 mg x min(-1) x dl(-1) in 24 healthy subjects. Forearm blood flow (FBF) and glucose uptake and plasma glucose, free fatty acid, and AICA-riboside concentrations were assessed. We also combined AICA-riboside infusion (2 mg x min(-1) x dl(-1)) with the intra-arterial administration of the adenosine receptor antagonist caffeine (90 microg x min(-1) x dl(-1); n = 6) and with the endothelial NO synthase inhibitor l-NMMA (0.4 mg x min(-1) x dl(-1); n = 6). Additional in vitro experiments were performed to explain our in vivo effects of AICA-riboside in humans. AICA-riboside increased FBF dose dependently from 2.0 +/- 0.2 to 13.2 +/- 1.9 ml x min(-1) x dl(-1) maximally (P < 0.05 for all dosages). The latter was not reduced by caffeine administration but was significantly attenuated by l-NMMA infusion. Despite high plasma AICA-riboside concentrations, forearm glucose uptake did not change. In vitro experiments showed rapid uptake of AICA-riboside by the equilibrative nucleoside transporter in erythrocytes and subsequent phosphorylation to AICA-ribotide. We conclude that AICA-riboside induces a potent vasodilator response in humans that is mediated by NO. Despite high local plasma concentrations, AICA-riboside does not increase skeletal muscle glucose uptake.

Associations between circulating free fatty acids, visceral adipose tissue accumulation, and insulin sensitivity in postmenopausal women

The aims of the study were to evaluate the contribution of visceral adipose tissue (AT) accumulation and insulin sensitivity to the determination of circulating free fatty acid (FFA) concentrations measured during a 2-hour euglycemic-hyperinsulinemic clamp and to verify whether elevated FFAs are associated with other components of the metabolic syndrome in postmenopausal women. This cross-sectional study included 115 postmenopausal women (46-68 years old). Visceral AT was estimated by computed tomography. Insulin sensitivity was assessed by a 2-hour euglycemic-hyperinsulinemic clamp. Free fatty acid concentration was measured in the fasting state and every 30 minutes during the clamp. Fasting plasma glucose and 2-hour plasma glucose were measured by an oral glucose tolerance test. Visceral AT was associated positively and insulin sensitivity negatively with FFA area under the curve (AUC) measured during the clamp. Women with high visceral AT accumulation and low insulin sensitivity had higher FFA AUC than women with high visceral AT accumulation and high insulin sensitivity or women with low visceral AT combined with either low or high insulin sensitivity. Free fatty acid AUC was positively associated with triglyceride (r = 0.25, P < .05), fasting plasma glucose (r = 0.26, P < .01), 2-hour plasma glucose (r = 0.27, P < .01), and diastolic blood pressure (r = 0.21, P < .05) independently of visceral AT and insulin sensitivity. In postmenopausal women, the presence of both high visceral AT and low insulin sensitivity is needed to observe an elevated FFA AUC. Moreover, FFA AUC is associated with some components of the metabolic syndrome, independently of visceral AT and insulin sensitivity.

Ischaemia and insulin, but not ischaemia and contraction, act synergistically in stimulating muscle glucose uptake in vivo in humans

Ischaemia, like muscle contraction, has been reported to induce skeletal muscle glucose uptake in in vitro models. This stimulating effect appears independent of insulin and is probably mediated by activation of AMPK (AMP-activated protein kinase). In the present study, we hypothesized that in vivo in humans ischaemia- and insulin-induced glucose uptake are additive, and that the combined impact of ischaemia and contraction on glucose uptake is of a similar magnitude when each is applied separately. We assessed the effects of ischaemia with and without euglycaemic–hyperinsulinaemia (clamp; protocol 1) and with and without muscle contraction (protocol 2) on muscle FGU (forearm glucose uptake) in healthy subjects. Furthermore, we assessed the impact of ischaemia on FBF (forearm blood flow; plethysmography). In protocol 1, ischaemia increased FGU from 0.6±0.1 at baseline to 5.5±1.9 μmol·min−1·dl−1, and insulin increased FGU to 1.6±0.3 μmol·min−1·dl−1 (P<0.05 for both). The combination of ischaemia+insulin increased FGU to 15.5±2.2 μmol·min−1·dl−1 (P<0.05 compared with each stimulus alone). Maximal FBF obtained after ischaemia was similar with and without hyperinsulinaemia. In protocol 2, isometric contraction increased FGU from 0.3±0.1 to 2.7±0.8 μmol·min−1·dl−1 (P<0.05), but FGU was not significantly different from ischaemia compared with ischaemia+contraction. However, combined ischaemia+contraction resulted in a greater increase in FBF. In summary, ischaemia and insulin independently stimulate skeletal muscle glucose uptake in vivo in humans, whereas ischaemia and contraction do not. The observed differential effects of these stimuli on glucose uptake appear to be unrelated to changes in muscle blood flow.