Influence of pneumoperitoneum and head-down maneuver on the cerebral microvasculature in rabbits.

BACKGROUND: With recent advances in robot-assisted techniques, an increasing number of surgeries are being performed with pneumoperitoneum and head-down maneuver (HDM) that may affect the cerebral microcirculation. For the first time, this study investigated the direct influence of pneumoperitoneum and HDM on the cerebral microvasculature in rabbits. METHODS: Adult male rabbits were randomly allocated to the following groups (n = 7 each): control, pneumoperitoneum alone (P), and pneumoperitoneum with HDM (P + HDM) for 120 min. A closed cranial window was installed above the parietal bone to visualize the pial microvasculature. Pial arteriolar diameter and hemodynamic and blood gas parameters were measured during the 140-min observation period. Brain edema was assessed by evaluation of the brain water content at the end of the experiment. RESULTS: Rabbits in the P and P + HDM groups exhibited a similar degree of immediate pial arteriolar dilation following the initiation of both P and P + HDM (P: 1.11 ± 0.03, p = 0.0044 and P + HDM: 1.07 ± 0.02, p = 0.0004, relative changes from the baseline value by defining the baseline as one). In the P + HDM group, pial arteriole diameter returned to the baseline level following the discontinuation of pneumoperitoneum and HDM (1.05 ± 0.03, p = 0.0906, vs. baseline). In contrast, the pial arterioles remained dilated as compared to the baseline level in the P group after discontinuation of pneumoperitoneum. There were no changes in pial arteriole diameter in the animals in the control group. Heart rate, blood gas parameters, and brain water content were not significantly different between the groups. CONCLUSION: The pial arterioles dilated immediately after pneumoperitoneum with or without HDM. The pial arterioles remained dilated 20 min after discontinuation of pneumoperitoneum alone but constricted upon discontinuation of pneumoperitoneum plus HDM. Pneumoperitoneum and HDM for 2 h did not cause brain edema.

G:U-Independent RNA Minihelix Aminoacylation by Nanoarchaeum equitans Alanyl-tRNA Synthetase: An Insight into the Evolution of Aminoacyl-tRNA Synthetases.

Nanoarchaeum equitans is a species of hyperthermophilic archaea with the smallest genome size. Its alanyl-tRNA synthetase genes are split into AlaRS-α and AlaRS-ß, encoding the respective subunits. In the current report, we surveyed N. equitans AlaRS-dependent alanylation of RNA minihelices, composed only of the acceptor stem and the T-arm of tRNAAla. Combination of AlaRS-α and AlaRS-ß showed a strong alanylation activity specific to a single G3:U70 base pair, known to mark a specific tRNA for charging with alanine. However, AlaRS-α alone had a weak but appreciable alanylation activity that was independent of the G3:U70 base pair. The shorter 16-mer RNA tetraloop substrate mimicking only the first four base pairs of the acceptor stem of tRNAAla, but with C3:G70 base pair, was also successfully aminoacylated by AlaRS-α. The end of the acceptor stem, including CCA-3' terminus and the discriminator A73, was able to function as a minimal structure for the recognition by the enzyme. Our findings imply that aminoacylation by N. equitans AlaRS-α may represent a vestige of a primitive aminoacylation system, before the appearance of the G3:U70 pair as an identity element for alanine.

Correction to: G:U­Independent RNA Minihelix Aminoacylation by Nanoarchaeum equitans Alanyl­tRNA Synthetase: An Insight into the Evolution of Aminoacyl­tRNA Synthetases.

In the original version of this article, "A73" in Fig 6b was inadvertently labeled as "G73". The corrected Fig. 6 is given here.

Effects of spinal anesthesia and sedation with dexmedetomidine or propofol on cerebral regional oxygen saturation and systemic oxygenation a period after spinal injection.

PURPOSE: To evaluate changes in cerebral regional oxygen saturation (rSO2) after spinal anesthesia and compare the changes in rSO2 and systemic oxygenation between dexmedetomidine sedation and propofol sedation. METHODS: Thirty-six patients scheduled to undergo transurethral surgery under spinal anesthesia were randomly assigned to the dexmedetomidine (n = 18) and propofol groups (n = 18). We used near-infrared spectroscopy sensors to measure rSO2, and obtained data from each side were averaged. After oxygen insufflation, baseline measurements of mean arterial blood pressure (MAP), heart rate, rSO2, pulse oximetry saturation (SpO2), bispectral index, and body temperature were made. After spinal anesthesia, we measured these parameters every 5 min. Twenty minutes after spinal injection, dexmedetomidine or propofol administration was started. We measured each parameter at 10, 25, and 40 min after the administration of dexmedetomidine or propofol. RESULTS: The baseline rSO2 in the dexmedetomidine group was 71.3 ± 7.3%, and that in the propofol group was 71.8 ± 5.6%. After spinal anesthesia, rSO2 in both groups decreased significantly (dexmedetomidine group: 65.4 ± 6.9%; propofol group: 64.3 ± 7.4%). After administering sedatives, rSO2 was equivalent after spinal anesthesia. rSO2 was comparable between the two groups. MAP and SpO2 were significantly higher in the dexmedetomidine group than in the propofol group. CONCLUSION: Spinal anesthesia decreased rSO2; however, the decline was not severe. Dexmedetomidine and propofol did not compromise cerebral oxygenation under spinal anesthesia. Nevertheless, MAP and SpO2 were more stable in dexmedetomidine sedation than in propofol sedation. Dexmedetomidine may be suitable for spinal anesthesia.

Changes of cerebral regional oxygen saturation during pneumoperitoneum and Trendelenburg position under propofol anesthesia: a prospective observational study.

BACKGROUND: We evaluated the change of cerebral regional tissue oxygen saturation (rSO2) along with the pneumoperitoneum and the Trendelenburg position. We also assessed the relationship between the change of rSO2 and the changes of mean arterial blood pressure (MAP), heart rate (HR), arterial carbon dioxide tension (PaCO2), arterial oxygen tension (PaO2), or arterial oxygen saturation (SaO2). METHODS: Forty-one adult patients who underwent a robotic assisted endoscopic prostatic surgery under propofol and remifentanil anesthesia were involved in this study. During the surgery, a pneumoperitoneum was established using carbon dioxide. Measurements of rSO2, MAP, HR, PaCO2, PaO2, and SaO2 were performed before the pneumoperitoneum (baseline), every 5 min after the onset of pneumoperitoneum, before the Trendelenburg position. After the onset of the Trendelenburg position, rSO2, MAP, HR were recorded at 5, 10, 20, 30, 45, and 60 min, and PaCO2, PaO2, and SaO2 were measured at 10, 30, and 60 min. RESULTS: Before the pneumoperitoneum, left and right rSO2 were 67.9 ± 6.3% and 68.5 ± 7.0%. Ten minutes after the onset of pneumoperitoneum, significant increase in the rSO2 was observed (left: 69.6 ± 5.9%, right: 70.6 ± 7.4%). During the Trendelenburg position, the rSO2 increased initially and peaked at 5 min (left: 72.2 ± 6.5%, right: 73.1 ± 7.6%), then decreased. Multiple regression analysis showed that change of rSO2 correlated with MAP and PaCO2. CONCLUSIONS: Pneumoperitoneum and the Trendelenburg position in robotic-assisted endoscopic prostatic surgery did not worsen cerebral oxygenation. Arterial blood pressure is the critical factor in cerebral oxygenation. TRIAL REGISTRATION: Japan Primary Registries Network (JPRN); UMIN-CTR ID; UMIN000026227 (retrospectively registered).

Effects of hyperventilation on cerebral oxygen saturation estimated using near-infrared spectroscopy: A randomised comparison between propofol and sevoflurane anaesthesia.

BACKGROUND: Near-infrared spectroscopy estimates cerebral regional tissue oxygen saturation (rSO2), which may decrease under hyperventilation. Propofol and sevoflurane act differently on cerebral blood vessels. Consequently, cerebral blood flow during hyperventilation with propofol and sevoflurane anaesthesia may differ. OBJECTIVES: The first aim of this study was to compare the changes in rSO2 between propofol and sevoflurane anaesthesia during hyperventilation. The second aim was to assess changes in rSO2 with ventilation changes. DESIGN: A randomised, open-label study. SETTING: University of Yamanashi Hospital, Yamanashi, Japan from January 2014 to September 2014. PARTICIPANTS: Fifty American Society of Anesthesiologists physical status 1 or 2 adult patients who were scheduled for elective abdominal surgery were assigned randomly to receive either propofol or sevoflurane anaesthesia. Exclusion criterion was a known history of cerebral disease such as cerebral infarction, cerebral haemorrhage, transient ischaemic attack and subarachnoid haemorrhage. INTERVENTIONS: After induction of anaesthesia but before the start of surgery, rSO2, arterial carbon dioxide partial pressure (PaCO2) and arterial oxygen saturation were measured. Measurements were repeated at 5-min intervals during 15 min of hyperventilation with a PaCO2 around 30 mmHg (4 kPa), and again after ventilation was normalised. MAIN OUTCOME MEASURES: The primary outcome was the difference of changes in rSO2 between propofol anaesthesia and sevoflurane anaesthesia during and after hyperventilation. The second outcome was change in rSO2 after the initiation of hyperventilation and after the normalisation of ventilation. RESULTS: Changes of rSO2 during hyperventilation were -10 ±â€Š7% (left) and -11 ±â€Š8% (right) in the propofol group, and -10 ±â€Š8% (left) and -9 ±â€Š7% (right) in the sevoflurane group. After normalisation of PaCO2, rSO2 returned to baseline values. Arterial oxygen saturation remained stable throughout the measurement period. The rSO2 values were similar in the propofol and the sevoflurane groups at each time point. CONCLUSION: The effects of hyperventilation on estimated rSO2 were similar with propofol and sevoflurane anaesthesia. Changes in rSO2 correlated well with ventilation changes. TRIAL REGISTRATION: Japan Primary Registries Network (JPRN); UMIN-CTR ID; UMIN000010640.

Role of the protein kinase A signaling pathway and identification of mediators in the cardioprotective effects of enteral lactoferrin for ischemia-reperfusion injury in an isolated rat heart model.

OBJECTIVE: Lactoferrin is an iron-binding glycoprotein. Enteral lactoferrin attenuates myocardial ischemia-reperfusion (IR) injury, but the underlying mechanism remains unknown. The aim of this study was to investigate protein kinase A (PKA) signaling pathway activation and levels of serum glucagonlike peptide-1 (GLP-1), secreted by intestinal endocrine L cells, and adiponectin, secreted by adipose tissue, after enteral lactoferrin administration. METHODS: Hearts (N = 32) were excised from Wistar rats and perfused using a Langendorff system. To assess the role of the PKA pathway in the cardioprotective effects of lactoferrin, an inhibitor of PKA (H89) was applied before no-flow ischemia. Rats were randomly divided into four groups: control, lactoferrin (LF), control+H89, and LF+H89. The control and control+H89 groups were administered normal saline by gavage, and the LF and L +H89 groups were administered bovine lactoferrin (1000 mg/kg) by gavage 15 min before intraperitoneal pentobarbital injection. Muscle sampling was performed at the end of reperfusion. When rats were sacrificed, blood was sampled to measure hormone levels. The primary outcome was maximum left ventricular pressure derivative (LV dP/dt max) 15 min after reperfusion. RESULTS: LV dP/dt max at 10 and 15 min after reperfusion was significantly higher in the LF group than in the control group (P < 0.05), and the effect was diminished by H89. The PKA pathway was significantly activated in the LF group. Enteral lactoferrin increased serum GLP-1 but not serum adiponectin levels. CONCLUSIONS: Enteral lactoferrin induces cardioprotective effects against myocardial IR injury via the PKA signaling pathway and increases serum GLP-1 levels.

Amiodarone Provides Long-Lasting Local Anesthesia and Analgesia in Open-State Mouse Nociceptors.

Local anesthetics with long-lasting effects and selectivity for nociceptors have been sought over the past decades. In this study, we investigated whether amiodarone, a multiple channel blocker, provides long-lasting local anesthesia and whether adding a TRPV1 channel activator selectively prolongs sensory anesthetic effects without prolonging motor blockade. Additionally, we examined whether amiodarone provides long-lasting analgesic effects against inflammatory pain without TRPV1 channel activator co-administration. In the sciatic nerve block model, 32 adult C57BL/6J mice received either bupivacaine, amiodarone with or without capsaicin (a TRPV1 agonist), or vehicle via peri-sciatic nerve injection. Sensory and motor blockade were assessed either by pinprick and toe spread tests, respectively. In another set of 16 mice, inflammatory pain was induced in the hind paw by zymosan injection, followed by administration of either amiodarone or vehicle. Mechanical and thermal sensitivity and paw thickness were assessed using the von Frey and Hargreaves tests, respectively. The possible cardiovascular and neurological side effects of local amiodarone injection were assessed in another set of 12 mice. In the sciatic nerve block model, amiodarone produced robust anesthesia, and the co-administration of TRPV1 agonist capsaicin prolonged the duration of sensory blockade, but not that of motor blockade [complete sensory block duration: 195.0 ± 9.8 min vs. 28.8 ± 1.3 min, F (2, 21) = 317.6, p < 0.01, complete motor block duration: 27.5 ± 1.6 min vs. 21.3 ± 2.3 min, F (2, 22) = 11.1, p = 0.0695]. In the zymosan-induced inflammatory pain model, low-dose amiodarone was effective in reversing the mechanical and thermal hypersensitivity not requiring capsaicin co-administration [50% withdrawal threshold at 8 h (g): 0.85 ± 0.09 vs. 0.25 ± 0.08, p < 0.01, withdrawal latency at 4 h (s) 8.5 ± 0.5 vs. 5.7 ± 1.4, p < 0.05]. Low-dose amiodarone did not affect zymosan-induced paw inflammation. Local amiodarone did not cause cardiovascular or central nervous system side effects. Amiodarone may have the potential to be a long-acting and nociceptor-selective local anesthetic and analgesic method acting over open-state large-pore channels.

PI3K/Akt pathway mediates the positive inotropic effects of insulin in Langendorff-perfused rat hearts.

Insulin exerts positive inotropic effects on cardiac muscle; however, the relationship between cardiac contractility and phosphoinositol-3-kinase/Akt (PI3K/Akt) activation remains unclear. We hypothesized that the positive inotropic effects of insulin are dose-dependent and mediated via the PI3K/Akt pathway in isolated normal rat hearts. The Institutional Animal Investigation Committee approved the use of hearts excised from rats under pentobarbital anesthesia. The hearts were perfused at a constant pressure using the Langendorff technique. After stabilization (baseline), the hearts were randomly divided into the following four insulin (Ins) groups: 1) Ins0 (0 IU/L), 2) Ins0.5 (0.5 IU/L), 3) Ins5 (5 IU/L), and 4) Ins50 (50 IU/L) (n = 8 in each group). To clarify the role of the PI3K/Akt pathway in insulin-dependent inotropic effects, we also treated the insulin groups with the PI3K inhibitor wortmannin (InsW): 5) InsW0 (0 IU/L), 6) InsW0.5 (0.5 IU/L), 7) InsW5 (5 IU/L), and 8) InsW50 (50 IU/L). Hearts were perfused with Krebs-Henseleit buffer solution with or without wortmannin for 10 min, followed by 20 min perfusion with the solution containing each concentration of insulin. The data were recorded as the maximum left ventricular derivative of pressure development (LV dP/dt max). Myocardial p-Akt levels were measured at 3 min, 5 min, and at the end of the perfusion. In the Ins groups, LV dP/dt max in Ins5 and Ins50 increased by 14% and 48%, respectively, 3 min after insulin perfusion compared with the baseline. Tachyphylaxis was observed after 10 min in the Ins5 and Ins50 treatment groups. Wortmannin partially inhibited the positive inotropic effect of insulin; although insulin enhanced p-Akt levels at all time points compared with the control group, this increase was suppressed in the presence of wortmannin. The positive inotropic effect of insulin is dose-dependent and consistent with Akt activation. This effect mediated by high doses of insulin on cardiac tissue was temporary and caused tachyphylaxis, potentially triggered by Akt overactivation, which leads beta 1 deactivation.

Cardioprotective effects of enteral vs. parenteral lactoferrin administration on myocardial ischemia-reperfusion injury in a rat model of stunned myocardium.

BACKGROUND: Lactoferrin, an iron-binding glycoprotein, is known to have protective effects against intestinal and cerebral ischemia-reperfusion (IR) injuries; however, its cardioprotective effects against the stunned myocardium are unknown. This study aimed to test the hypothesis that lactoferrin has cardioprotective effects against stunned myocardium. METHODS: Using isolated rat hearts (Langendorff system), we determined the effects of lactoferrin administered enterally and by direct cardiac perfusion. Rat hearts were perfused using the Langendorff system, and two experiments were performed. In experiment 1, the hearts were divided into the enteral lactoferrin (E-LF) 7.5 m, 15 m, 30 m, and 60 m groups, where lactoferrin (1000 mg/kg) was administered enterally 7.5, 15, 30, and 60 min, respectively, before perfusion; and a control group, where saline was administered 30 min before perfusion. In experiment 2, hearts were allocated to the perfusate lactoferrin (P-LF) 15 and 100 groups, where 15 mg/L and 100 mg/L lactoferrin were respectively added to the perfusate, and a control group. Each group was perfused for 20 min prior to 15 min of no-flow ischemia with pacing, followed by 20 min of reperfusion. The primary outcome was the maximum left ventricular derivative of pressure development (LV dP/dt max) 15 min after reperfusion. Myocardial phospho-protein kinase B (p-Akt) was assayed using western blotting. RESULTS: The LV dP/dt max 15 min after reperfusion in the E-LF 15 and 30 m groups was significantly higher than that in the control group. However, the effects disappeared in the E-LF 60 m group. In the second experiment, there were no significant differences in LV dP/dt max. Myocardial p-Akt was not significantly activated in any lactoferrin group. CONCLUSION: Cardioprotection was observed 15-30 min after enteral lactoferrin but not by direct cardiac perfusion with lactoferrin. Myocardial p-Akt was not associated with the cardioprotective effect. The cardioprotective effect may be induced by enteral lactoferrin-induced substances.

Ulinastatin attenuates protamine-induced cardiotoxicity in rats by inhibiting tumor necrosis factor alpha.

Protamine causes cardiac depression, which may be mediated by tumor necrosis factor alpha (TNF-α). Ulinastatin, a human urinary protease inhibitor, inhibits TNF-α. Here, we aimed to investigate whether ulinastatin prevented protamine-induced myocardial depression by inhibiting TNF-α. Rat hearts were perfused using a Langendorff system, and three protocols were followed. Protocol 1: The hearts were divided into saline, ulinastatin-low, and ulinastatin-high groups. Protamine was administered to each group, and myocardial contractility was the primary outcome. Protocol 2: The hearts were allotted to saline or ulinastatin group. Protamine was administered to each group. TNF-α expression in the coronary effluent and myocardial tissue was measured. Protocol 3: The hearts were allotted to saline and ulinastatin groups. Recombinant rat-TNF-α was administered to each group. Protamine alone reduced the maximum left ventricular pressure derivative (LV dP/dt max) by 45 ± 4%. In contrast, the reduction in LV dP/dt max was 4 ± 3% in the ulinastatin-high group. Compared with that in the saline group, the increase in TNF-α in the coronary effluent was attenuated in the ulinastatin group. Recombinant TNF-α alone reduced LV dP/dt max (- 21 ± 14%). In contrast, when TNF-α was added in the presence of ulinastatin, the decrease in LV dP/dt max was prevented significantly (- 3 ± 8%). We showed, for the first time, that ulinastatin protected against protamine-induced myocardial damage, both by inhibiting TNF-α synthesis and by directly preventing the cardiodepressant action of TNF-α.

Dendritic folate rosettes as ion channels in lipid bilayers.

The self-assembly of folate dendrimers into pi-stacked supramolecular rosettes is shown to produce ion channels in planar and spherical lipid bilayer membranes. The found ion channels are small, quite homogeneous, long-lived, ohmic, cation selective (Eisenman I), and blockable by the permeant cation.

Thermotropic liquid-crystalline peptide derivatives: oligo(glutamic acid)s forming hydrogen-bonded columns.

We report on new thermotropic liquid-crystalline oligo(amino acid) derivatives forming columnar structures. These are based on branched oligo(glutamic acid)s and 2-(3,4-dialkyloxyphenyl)ethyl moieties. An oligo(glutamic acid) derivative, alpha,gamma-bis(L-glutamoyl) L-glutamic acid tetra[2-(3,4-dioctadecyloxyphenyl)ethyl]ester, shows a hexagonal columnar phase, whilst a glutamic acid derivative, alpha,gamma-bis[2-(3,4-dioctadecyloxyphenyl)ethyl] L-glutamate, does not show a mesophase. Hydrogen bonds formed by the oligo(glutamic acid) moieties should contribute to the induction of the columnar liquid-crystalline properties. In addition, we have examined the effects of the molecular chirality of the oligo(glutamic acid) parts and the functionalisation at the focal position of the taper shaped molecules on the liquid-crystalline properties of the compounds.