Syntheses and Biological Evaluation of Costunolide, Parthenolide, and Their Fluorinated Analogues.

Inspired by the biosynthesis of sesquiterpene lactones (SLs), herein we report the asymmetric total synthesis of the germacrane ring (24). The synthetic strategy features a selective aldol reaction between ß,γ-unsaturated chiral sulfonylamide 15a and aldehyde 13, as well as the intramolecular α-alkylation of sulfone 21 to construct a 10-membered carbocylic ring. The key intermediate 24 can be used to prepare the natural products costunolide and parthenolide (PTL), which are the key precursors for transformation into other SLs. Furthermore, the described synthetic sequences are amenable to the total synthesis of SL analogues, such as trifluoromethylated analogues 32 and 45. Analogues 32 and 45 maintained high activities against a series of cancer cell lines compared to their parent PTL and costunolide, respectively. In addition, 32 showed enhanced tolerance to acidic media compared with PTL. To our surprise, PTL and 32 showed comparable half-lives in rat plasma and in the presence of human liver microsomes.

Total syntheses of parthenolide and its analogues with macrocyclic stereocontrol.

The first total synthesis of parthenolide (1) is described. The key feature of this synthesis is the formation of a 10-membered carbocylic ring by a macrocyclic stereocontrolled Barbier reaction, followed by a photoinduced Z/E isomerization. The biological evaluation of a small library of parthenolide analogues (19, 33, and 34) disclosed a preliminary structure-activity relationship (SAR). The results revealed that the C1, C10 double bond configuration of parthenolide has little or no effect on the activity, and the C6 and C7 configurations of the lactone ring have a moderate impact on the activities against some cancer cell lines.

Effects of alpha lipoic acid and its R+ enantiomer supplemented to hyperbaric oxygen therapy on interleukin-6, TNF-α and EGF production in chronic leg wound healing.

CONTEXT: Lipoic acid (LA) and hyperbaric oxygenation therapy (HBOT) improve chronic wound healing. OBJECTIVE: We compared the effects of LA or its enantiomer R-(+)-lipoic acid (RLA) on wound healing. MATERIALS AND METHODS: Groups LA + HBOT (L), RLA + HBOT (R) and placebo + HBOT (P). Lesion areas measured before treatment and on 20th and 40th day. The biopsies and plasma were harvested before treatment and on 7th and 14th (measurements of VEGF, vascular endothelial growth factor; EGF, epidermal growth factor, TNF-α and IL-6). RESULTS: Ulcers improved more on RLA. In both L and R groups, EGF and VEFG increased in time. RLA decreased IL-6 on T7 and T14, which did not happen with LA. TNF-α levels decreased on T14 in both LA and RLA. DISCUSSION: The improved wound healing is associated with increased EGF and VEGF and reduced plasma TNF-α and IL-6. CONCLUSION: RLA may be more effective than LA in improving chronic wound healing in patients undergoing HBO therapy.

Risk factors for delayed extubation in thoracic and lumbar spine surgery: a retrospective analysis of 135 patients.

PURPOSE: Extubation may be delayed after spine surgery mainly for the concerns of airway safety. Risk factors for delayed extubation in cervical spine surgery have been described to include prolonged surgery time and amount of crystalloids or blood transfused. To date, risk factors for delayed extubation in thoracic or lumbar spine surgery have not been investigated. We retrospectively reviewed 135 consecutive patients from 2006 to 2009 who underwent thoracic or lumbar spine surgery by one particular surgeon to identify risk factors for delayed extubation. METHODS: Data including patient factors, surgical time, anesthetic technique, blood loss, crystalloid and colloid administration, transfusion requirements, time to transfusion, and time to extubation were collected and analyzed. Delayed extubation was defined as the patient was not extubated in the operating room at completion of the surgery. RESULTS: One hundred and eight patients were extubated in the OR. Delayed extubation occurred in 27 patients. Delayed extubation was significantly related to total operative time (6.6 ± 0.4 vs. 5.2 ± 0.1 h), volume of crystalloid replacement (6,018 ± 408 vs. 4,186 ± 130 cm3), volume of total colloids infused (787 ± 93 vs. 442 ± 36 cm3), intraoperative blood transfused (3.7 ± 0.5 vs. 0.7 ± 0.1 units); blood loss (2,137 ± 286 vs. 832 ± 50 cm3), and time to starting blood transfusion (106 ± 12 vs. 199 ± 9 min). CONCLUSIONS: Our study suggests that intraoperative factors including prolonged surgical time, significant blood loss, larger volume of crystalloid and colloid infusion, and blood transfusion may be risk factors for delayed extubation following thoracic or lumbar spine surgery. Early blood transfusion may also increase the risk of delayed extubation. Patient factors did not affect extubation time.

Impact of anesthesia on mortality during endovascular clot removal for acute ischemic stroke.

BACKGROUND: Endovascular clot retrieval is a technique available for removing intracranial arterial occlusions in acute ischemic stroke (AIS). This rescue therapy can be performed with moderate conscious sedation (CS) or general anesthesia (GA). The effect of GA on clinical outcome in AIS remains controversial. Therefore, we retrospectively investigated whether the use of CS or GA during endovascular intervention for AIS influenced outcomes. METHODS: Patients who underwent emergent endovascular intervention for intracranial arterial occlusion during the years 2006 to 2012 were included in this study. Statistical analysis using the Spearman ρ was performed to examine demographic data and clinical outcomes between patients in the GA and CS groups. Binary logistic regression was used to determine the predictors of mortality. RESULTS: A total of 109 patients fit the inclusion criteria. Among them, 35 patients had GA and 74 patients had CS. Patients needing intubation upon admission for airway protection were more likely to receive GA (P<0.001). The duration of the procedure and the time-to-revascularization from symptom onset were significantly longer in the GA group. Mortality was higher in the GA group compared with the CS group (40% vs. 22%, P=0.045). Multivariate analysis, controlled for confounding variables, identified GA and elevated postprocedure glucose level to be significant predictors of mortality. CONCLUSIONS: Larger prospectively randomized multicenter trials evaluating the effects of GA and CS on clinical and radiographic outcomes seems warranted.

The usefulness of intraoperative neurophysiological monitoring in cervical spine surgery: a retrospective analysis of 200 consecutive patients.

The usefulness of intraoperative neurophysiological monitoring (IONM), including somatosensory-evoked potential (SSEP) and transcranial electrical motor-evoked potentials (TcMEPs) in cervical spine surgery still needs to be evaluated. We retrospectively reviewed 200 cervical spine surgery patients from 2008 to 2009 to determine the role of IONM in cervical spine surgery. Total intravenous anesthesia was used for all patients. IONM alerts were defined as a 50% decrease in amplitude, a 10% increase in latency, or a unilateral change for SSEP and an increase in stimulation threshold of more than 100 V for TcMEP. Three patients had SSEP alerts that were related to arm malposition (2 patients) and hypotension (1 patient). Five patients had TcMEP alerts: 4 alerts were caused by hypotension and 1 by bone graft compression of the spinal cord. All alerts were resolved when causative reasons were corrected. There was no postoperative iatrogenic neurological injury. The sensitivities of SSEP and TcMEP alerts for detecting impending neurological injury were 37.5% and 62.5%, respectively. The sensitivity of both SSEP and TcMEP used in combination was 100%. No false-positive and false-negative alerts were identified in either SSEP or TcMEP (100% specificity). The total intravenous anesthesia technique optimizes the detection of SSEP and TcMEP and therefore improves the sensitivity and specificity of IONM. SSEP is sensitive in detecting alerts in possible malposition-induced ischemia or brachial plexus nerve injury. TcMEP specifically detects hypotension-induced spinal functional compromises. Combination use of TcMEP and SSEP enhances the early detection of impeding neurological damage during cervical spine surgery.

Effect of in-water oxygen prebreathing at different depths on decompression-induced bubble formation and platelet activation.

Effect of in-water oxygen prebreathing at different depths on decompression-induced bubble formation and platelet activation in scuba divers was evaluated. Six volunteers participated in four diving protocols, with 2 wk of recovery between dives. On dive 1, before diving, all divers breathed normally for 20 min at the surface of the sea (Air). On dive 2, before diving, all divers breathed 100% oxygen for 20 min at the surface of the sea [normobaric oxygenation (NBO)]. On dive 3, before diving, all divers breathed 100% O2 for 20 min at 6 m of seawater [msw; hyperbaric oxygenation (HBO) 1.6 atmospheres absolute (ATA)]. On dive 4, before diving, all divers breathed 100% O2 for 20 min at 12 msw (HBO 2.2 ATA). Then they dove to 30 msw (4 ATA) for 20 min breathing air from scuba. After each dive, blood samples were collected as soon as the divers surfaced. Bubbles were measured at 20 and 50 min after decompression and converted to bubble count estimate (BCE) and numeric bubble grade (NBG). BCE and NBG were significantly lower in NBO than in Air [0.142+/-0.034 vs. 0.191+/-0.066 (P<0.05) and 1.61+/-0.25 vs. 1.89+/-0.31 (P<0.05), respectively] at 20 min, but not at 50 min. HBO at 1.6 ATA and 2.2 ATA has a similar significant effect of reducing BCE and NBG. BCE was 0.067+/-0.026 and 0.040+/-0.018 at 20 min and 0.030+/-0.022 and 0.020+/-0.020 at 50 min. NBG was 1.11+/-0.17 and 0.92+/-0.16 at 20 min and 0.83+/-0.18 and 0.75+/-0.16 at 50 min. Prebreathing NBO and HBO significantly alleviated decompression-induced platelet activation. Activation of CD62p was 3.0+/-0.4, 13.5+/-1.3, 10.7+/-0.9, 4.5+/-0.7, and 7.6+/-0.8% for baseline, Air, NBO, HBO at 1.6 ATA, and HBO at 2.2 ATA, respectively. The data show that prebreathing oxygen, more effective with HBO than NBO, decreases air bubbles and platelet activation and, therefore, may be beneficial in reducing the development of decompression sickness.

TNF-alpha modulates iNOS expression in an experimental rat model of indomethacin-induced jejunoileitis.

Multiple mucosal immune factors, such as TNF-alpha and IL-1beta, are thought to be key mediators involved in inflammatory bowel disease. We evaluated the role of the pro-inflammatory cytokine TNF-alpha on nitric oxide synthase (NOS) expression in indomethacin-induced jejunoileitis in rats. Jejunoileitis was induced in rats with subcutaneous injections of indomethacin (7.5 mg/kg) 24 h apart for two consecutive days, and animals were randomized into four groups. Group 1 received only indomethacin. Group 2 was treated with a daily dose of phosphodiesterase (PDE) inhibitor (theophylline or pentoxifylline) by oral gavage for 2 days before and 4 days after indomethacin. Group 3 received a single dose of anti-TNF-alpha monoclonal antibody (TNF-Ab, IP) 30 min before indomethacin. Group 4 was treated with 1 h hyperbaric oxygenation (HBO(2)) for 5 days after indomethacin. Rats were sacrificed at 12 h or 4 days after final indomethacin injection. PDE inhibitor, TNF-Ab, or HBO(2) treatment significantly decreased indomethacin-induced ulceration, myeloperoxidase activity, and disease activity index. Although indomethacin significantly increased serum TNF-alpha and nitrate/nitrite (NOx) concentrations above control values at 12 h, inducible NOS (iNOS) expression was detected only at day 4. Serum IL-1beta levels did not change at 12 h but increased 4-fold after 4 days. Indomethacin had no effect on constitutive NOS. Treatment with PDE inhibitor, TNF-Ab, or HBO(2) significantly reduced serum/tissue TNF-alpha, IL-1beta, NOx, and iNOS expression. Our data show TNF-alpha plays an early pro-inflammatory role in indomethacin-induced jejunoileitis. Additionally, down-regulation of NOx by PDE inhibitors, TNF-Ab, or HBO(2) suggests that TNF-alpha modulates iNOS expression.

Hyperbaric oxygenation alleviates MCAO-induced brain injury and reduces hydroxyl radical formation and glutamate release.

The present study examined the effect of hyperbaric oxygen (HBO) on the formation of 2,3-dihydroxybenzoic acid (2,3-DHBA) and 2,5-dihydroxybenzoic acid (2,5-DHBA), the products of salicylate trapping of hydroxyl free radicals, and glutamate release in the striatum during acute ischemia and reperfusion. Non-HBO rats (n = 8) were subjected to 1-h ischemia. Study rats (n = 8) were treated with HBO at 2.8 ATA for 1 h during ischemia. Artificial CSF solution containing 5 mM sodium salicylate was perfused at 1 microl/min. Samples were continuously collected at 15 min intervals and the levels of 2,3-DHBA, 2,5-DHBA, and glutamate were analyzed. The lesion volume was determined by TTC stain. Occlusion of the middle cerebral artery induced a significant increase in the levels of 2,3-DHBA and 2,5-DHBA. A peak of approximately two and fourfold of baseline levels was reached at 45 min and was maintained at elevated levels during reperfusion. The level of glutamate increased approximately two times at 30 min during ischemia, continued to increase, and reached approximately three times baseline level during reperfusion. HBO significantly alleviated brain injury associated with decreased levels of 2,3-DHBA, 2,5-DHBA and glutamate. This study suggests that the decreased glutamate release and the reduced formation of hydroxyl free radicals might contribute to the neuroprotective effect of HBO.

Neuroprotective effects of erythropoietin on acute metabolic and pathological changes in experimentally induced neurotrauma.

OBJECT: Head trauma is a dynamic process characterized by a cascade of metabolic and molecular events. Erythropoietin (EPO) has been shown to have neuroprotective effects in animal models of traumatic brain injury (TBI). Acute in vivo mechanisms and pathological changes associated with EPO following TBI are unknown. In this study the authors compare acute metabolic and pathological changes following TBI with and without systemically administered EPO. METHODS: Right frontal lobe microdialysis cannulae and right parietal lobe percussion hubs were inserted into 16 Sprague-Dawley rats. After a 4- to 5-day recovery, TBI was induced via a DragonFly fluid-percussion device at 2.5-2.8 atm. Rats were randomized into 2 groups, which received 5000 U/kg EPO or normal saline intraperitoneally 30 minutes after TBI. Microdialysis samples for glucose, lactate, pyruvate, and glutamate were obtained every 25 minutes for 10 hours. Rats were killed, their brains processed for light microscopy, and sections stained with H & E. RESULTS: Erythropoietin administered 30 minutes after TBI directly affects acute brain metabolism. Brains treated with EPO maintain higher levels of glucose 4-10 hours after TBI (p<0.01), lower levels of lactate 6-10 hours after TBI (p<0.01), and lower levels of pyruvate 7.5-10 hours after TBI (p<0.01) compared with saline-treated controls. Erythropoietin maintains aerobic metabolism after TBI. Systemic EPO administration reduces acute TBI-induced lesion volume (p<0.05). CONCLUSIONS: Following TBI, neuron use initially increases, with subsequent depletion of extracellular glucose, resulting in increased levels of extracellular lactate and pyruvate. This energy requirement can result in cell death due to increased metabolic demands. These data suggest that the neuroprotective effect of EPO may be partially due to improved energy metabolism in the acute phase in this rat model of TBI.

The effect of isovolemic hemodilution with oxycyte, a perfluorocarbon emulsion, on cerebral blood flow in rats.

BACKGROUND: Cerebral blood flow (CBF) is auto-regulated to meet the brain's metabolic requirements. Oxycyte is a perfluorocarbon emulsion that acts as a highly effective oxygen carrier compared to blood. The aim of this study is to determine the effects of Oxycyte on regional CBF (rCBF), by evaluating the effects of stepwise isovolemic hemodilution with Oxycyte on CBF. METHODOLOGY: Male rats were intubated and ventilated with 100% O(2) under isoflurane anesthesia. The regional (striatum) CBF (rCBF) was measured with a laser doppler flowmeter (LDF). Stepwise isovolemic hemodilution was performed by withdrawing 4ml of blood and substituting the same volume of 5% albumin or 2 ml Oxycyte plus 2 ml albumin at 20-minute intervals until the hematocrit (Hct) values reached 5%. PRINCIPAL FINDINGS: In the albumin-treated group, rCBF progressively increased to approximately twice its baseline level (208+/-30%) when Hct levels were less than 10%. In the Oxycyte-treated group on the other hand, rCBF increased by significantly smaller increments, and this group's mean rCBF was only slightly higher than baseline (118+/-18%) when Hct levels were less than 10%. Similarly, in the albumin-treated group, rCBF started to increase when hemodilution with albumin caused the CaO(2) to decrease below 17.5 ml/dl. Thereafter, the increase in rCBF was accompanied by a nearly proportional decrease in the CaO(2) level. In the Oxycyte-treated group, the increase in rCBF was significantly smaller than in the albumin-treated group when the CaO(2) level dropped below 10 ml/dl (142+/-20% vs. 186+/-26%), and rCBF returned to almost baseline levels (106+/-15) when the CaO(2) level was below 7 ml/dl. CONCLUSIONS/SIGNIFICANCE: Hemodilution with Oxycyte was accompanied with higher CaO(2) and PO(2) than control group treated with albumin alone. This effect may be partially responsible for maintaining relatively constant CBF and not allowing the elevated blood flow that was observed with albumin.

Effects of hyperbaric oxygen on glucose, lactate, glycerol and anti-oxidant enzymes in the skeletal muscle of rats during ischaemia and reperfusion.

1. Hyperbaric (HBO(2)) and topical oxygen represent two accepted options to oxygenate tissues. The aim of the present study was to investigate the effect of HBO(2) on energy metabolism and anti-oxidant enzymes in a rat model of ischaemia-reperfusion (IR) skeletal muscle injury. 2. In the first study, 16 rats were randomized to a HBO(2)-treated group (Group 1; n = 8) and an untreated group (Group 2; n = 8). Under general anaesthesia, right hind limb ischaemia was produced by application of a rubber-band tourniquet for 3 h. After 2 h ischaemia, Group 1 rats received HBO(2) during the last hour of ischaemia. The HBO(2) consisted of 100% oxygen delivered at 282.8 kPa absolute pressure. Group 2 rats were not treated. Following the ischaemic period, the tourniquet was released for 1 h. A microdialysis probe was used to sample lactate, glucose and glycerol concentrations in the muscle extracellular tissue every 15 min throughout each experiment. 3. In the second study, 24 rats were randomized into four groups (n = 6 each). The first two groups were subjected to the IR injury protocol outlined above and either treated (Group 1) or untreated (Group 2) with HBO(2). Group 3 rats were anaesthetized, did not undergo IR injury, but underwent HBO(2) treatment. Group 4 rats were anaesthetized but did not undergo either IR injury or HBO(2) treatment. At end of each experiment, the biceps femoris muscle was removed and assayed for superoxide dismutase (SOD) and catalase (CAT) activity. Malondialdehyde (MDA) was measured to estimate the extent of membrane lipid peroxidation. 4. Three hours of skeletal muscle ischaemia resulted in a gradual decrease in the glucose concentration and a gradual increase in the lactate concentration within the extracellular fluid of the affected skeletal muscle tissue. Treatment with HBO(2) had no effect on the glucose concentration; however, HBO(2) significantly attenuated the ischaemia-induced increase in lactate and glycerol. In both groups, glucose concentration increased rapidly during reperfusion; glucose concentration returned to pre-ischaemic levels 15 min after reperfusion both with and without HBO(2). 5. Catalase activity and MDA increased significantly after 1 h of reperfusion. The HBO(2) attenuated the reperfusion-induced increase in CAT activity and MDA. 6. The results of the study suggest that HBO(2) may have some beneficial effect by decreasing lactate and glycerol levels and modulating anti-oxidant enzyme activity in postischaemic skeletal muscle in our rat model of tourniquet-induced IR skeletal muscle injury.

Beneficial effect of hyperbaric oxygen pretreatment on lipopolysaccharide-induced shock in rats.

1. We investigated the effect of hyperbaric oxygenation (HBO2) pretreatment on the production of exhaled nitric oxide (ENO) and the expression of lung inducible nitric oxide synthase (iNOS) by Escherichia coli lipopolysaccharide (LPS)-induced shock in an experimental rat model. 2. Rats were randomized into four groups, anaesthetized, mechanically ventilated with room air and infused with normal saline (2 mL/h) through the jugular vein for 5 h. Group 1 (NS) received only normal saline. Group 2 (HBO2-NS) was pretreated with HBO2 at 2.8 absolute atmospheres for 2 h and then received normal saline. Group 3 (LPS) received LPS, 20 mg/kg, i.v., bolus. Group 4 (HBO2-LPS) was pretreated with HBO2 for 2 h, followed by LPS. 3. Arterial blood gases, blood pressure, blood pH and ENO production were measured every 30 min. Plasma nitrite/nitrate (NOx) concentrations were assessed at the beginning (baseline) and at the end of the study. Lung myeloperoxidase (MPO) activity, iNOS expression and histological scores were measured for the evaluation of lung injury. 4. Administration of LPS was associated with decreased blood pressure and pH, increased ENO production, plasma NOx concentrations, lung iNOS expression and MPO activity. 5. Pretreatment with HBO2 significantly alleviated the LPS-induced hypotension, acidosis and decreased ENO production, plasma NOx concentrations, lung MPO activity and expression of iNOS. Hyperbaric O2 had no effect on control rats. 6. Our data show that HBO2 pretreatment has beneficial haemodynamic effects in rats with endotoxin shock. The beneficial effects of HBO2 may be partially mediated by decreased ENO production via reduced LPS-induced lung iNOS expression.

Hyperbaric oxygenation mitigates focal cerebral injury and reduces striatal dopamine release in a rat model of transient middle cerebral artery occlusion.

The usefulness of the administration of hyperbaric oxygen (HBO) in the treatment of acute focal cerebral ischemia remains debatable. A significant association exists between focal cerebral injury and an excessive release of extracellular dopamine (DA). In vivo microdialysis was used in the present study to examine the effect of HBO on DA release in the striatum during ischemia and reperfusion in rats. The histological changes occurring were also evaluated. Focal cerebral ischemia was induced by occlusion of the middle cerebral artery (MCA) using a surgically placed intraluminal filament. Control rats (n=8) were subjected to 1 h of ischemia, whilst the study rats (n=8) were in addition treated with HBO (2.8 atmospheres of absolute pressure 100% O(2)) during ischemia. Both groups were returned to breathing room air at normal pressure during reperfusion. Microdialysis samples were continuously collected at 15 min intervals at 2 microl.min(-1). The [mean (SE)] increase in release of striatal DA attained significance after 30 min of occlusion of MCA [170 (24)%], and continued to increase [268 (26)% at 45 min] reaching a peak level at 60 min [672 (59)%] before returning to the baseline level during the late reperfusion phase. There was no significant change in the level of DA in HBO treated rats during the period of ischemia. A significant reduction in edema and neuronal shrinkage were observed by histological examination in HBO treated rats when compared to the control rats. The results showed that HBO, when administered during ischemia, offered significant neuroprotection in our experimental model of transient focal cerebral ischemia in the rat. The mechanism seems to imply, at least in part, a reduced level of DA.

Hypotension during septic shock does not correlate with exhaled nitric oxide in anesthetized rat.

Sepsis is characterized by hypotension, acidosis, and increased nitric oxide (NO) production. The role of NO in the development of sepsis-related hypotension is still unclear. The relationship among exhaled nitric oxide (ENO), arterial blood pressure (BP), and pH after administration of lipopolysaccharide (LPS) and tumor necrosis factor alpha (TNFalpha) was investigated in anesthetized rats. Forty-three adult male Sprague-Dawley rats were randomized into five groups: group 1 (C, n = 8) received normal saline; group 2 (LPS-I, n = 8) received Escherichia coli (LPS) 10 mg/kg intravenously (i.v.); group 3 (LPS-h, n = 10) received 100 mg/kg LPS i.v.; group 4 (n = 9) was treated with 100 mg/kg i.v. aminoguanidine (AG) 1 h after receiving 100 mg/kg i.v. LPS; group 5 (TNFalpha, n = 8) received 1 microg recombinant rat TNFalpha i.v.. ENO, BP, and pH were measured every 30 min for 4 h whereas arterial blood gases and pH were measured every hour. LPS administration induced a dose-related increase in ENO and a dose-related decrease in BP and pH. AG blocked the increase in ENO after LPS but had minimal effect on BP and pH. TNFalpha administration increased ENO without changing BP and pH. In LPS-treated rats, no significant correlation was found between ENO and BP (r2 = 0.13, P= ns). However, there was a significant correlation between pH and BP (r2 = 0.7, P < 0.01). Our results suggest that, in this animal model, ENO may not be a key mediator in the development of systemic hypotension during sepsis, while acidosis may significantly contribute to it.