Positive end-expiratory pressure aggravates left ventricular diastolic relaxation further in patients with pre-existing relaxation abnormality.

BACKGROUND: Positive end-expiratory pressure (PEEP) has been known to adversely influence cardiac output. Even though left ventricular (LV) diastolic function significantly contributes to LV performance, the effects of PEEP on LV diastolic function remains controversial. We, therefore, aimed to examine the effects of PEEP on LV diastolic function by use of pulsed wave Doppler tissue imaging in patients with pre-existing LV relaxation abnormality. METHODS: Seventeen patients with peak early diastolic velocity of lateral mitral annulus (E') <8.5 cm s(-1) among patients who underwent coronary artery bypass graft surgery were evaluated. Echocardiographic and haemodynamic variables were measured with 0, 5, and 10 cmH2O of PEEP. E' and deceleration time (DT) of peak early transmitral filling velocity (E) were used as echocardiographic indicators of LV diastolic function. RESULTS: Mean arterial blood pressure decreased during 10 cmH2O PEEP, compared with that during 0 cmH2O PEEP. E' showed a gradual and significant decrease with an incremental increase in PEEP (6.9 ± 0.9, 5.8 ± 0.9, and 5.2 ± 1.2 cm s(-1) during 0, 5, and 10 cmH2O PEEP, respectively), and DT of E was prolonged during 10 cmH2O PEEP, compared with that during 0 cmH2O PEEP. CONCLUSIONS: Increasing PEEP led to a progressive decline in LV relaxation in patients with pre-existing LV relaxation abnormality.

Impact of intravenous lidocaine on myocardial injury after off-pump coronary artery surgery.

BACKGROUND: Lidocaine has been demonstrated to exert cardioprotective effects against myocardial ischaemia and reperfusion injury. We evaluated whether a continuous i.v. infusion of lidocaine reduced myocardial injury in patients undergoing off-pump coronary artery bypass graft surgery (OPCAB). METHODS: In this randomized, double-blinded trial, 99 patients received i.v. lidocaine 2% (i.e. a 1.5 mg kg(-1) bolus at induction of anaesthesia followed by a 2.0 mg kg(-1) h(-1) infusion intraoperatively) or an equal volume of saline. Serum creatine kinase-myocardial band (CK-MB) and troponin I (TnI) concentrations were measured before surgery, upon arrival in the intensive care unit, and at 6, 24, 48, and 72 h after surgery. Cardiac enzymes, other biological markers, and rate of postoperative adverse events were compared between the groups. RESULTS: The median (25-75% inter-quartile range) TnI [0.90 (0.43-1.81) vs 1.71 (0.88-3.02) ng ml(-1), P=0.027] and CK-MB [6.5 (3.9-12.3) vs 9.8 (6.0-18.6) ng ml(-1), P=0.005] concentrations 24 h after surgery were significantly lower in the lidocaine group than in the control group. Moreover, lidocaine infusion reduced the total area under the curve of TnI and CK-MB release after surgery by 42% and 27%, respectively, compared with control. CONCLUSIONS: Continuous i.v. infusion of lidocaine during surgery reduces myocardial injury in patients undergoing OPCAB.

Prophylactic control of post-operative nausea and vomiting using ondansetron and ramosetron after cardiac surgery.

BACKGROUND: The aim of this study was to evaluate the efficacy of ondansetron and ramosetron in the reduction of post-operative nausea and vomiting (PONV) associated with patient-controlled analgesia (PCA) after cardiac surgery. METHODS: A total of 320 patients scheduled for elective cardiac surgery were enrolled. Patients were randomly assigned to one of four treatment regimens (n=80 in each group): no prophylactic antiemetics (group P); intravenous (i.v.) ondansetron 4 mg at the end of surgery and 12 mg added to PCA (group O); i.v. ramosetron 0.3 mg at the end of surgery and no antiemetics added to PCA (group R1); and i.v. ramosetron 0.3 mg at the end of surgery and 0.6 mg added to PCA (group R2). RESULTS: The incidence of PONV during the 48-h post-operative period was lower in groups O (46%), R1 (54%), and R2 (35%) compared with group P (71%, P<0.001). The incidence and severity of nausea were lower in groups O, R1, and R2 than in group P during the 24-h post-operative period, whereas the incidence and severity of nausea during 24-48 h after surgery were lower in groups O and R2, but not in group R1, than in group P. Compared with group P (53%), the frequency of rescue antiemetic usage was significantly lower in groups O (34%) and R2 (29%), but not in group R1 (43%). CONCLUSION: The addition of either ondansetron or ramosetron to PCA can reduce the incidence of PONV during 48 h after cardiac surgery.

Drug tolerance in biomembranes: a spin label study of the effects of ethanol.

Ethanol in vitro increased the fluidity of spin-labeled membranes from normal mice. Membranes from mice that had been subjected to long-term ethanol treatment were relatively resistant to this fluidizing effect. The data suggest that the membranes themselves had adapted to the drug, a novel form of drug tolerance.

Association between central venous pressure and blood loss during hepatic resection in 984 living donors.

BACKGROUND: Although low central venous pressure (CVP) anesthesia has been used to minimize blood loss during hepatectomy, the efficacy of this technique remains controversial. We therefore assessed the association between blood loss and CVP during hepatic resection, and examined significant determinants associated with intraoperative hemorrhage during hepatectomy in living donors. METHODS: Between April 2004 and April 2008, 984 living donors who underwent a hepatic resection were assessed retrospectively. Univariate and multivariate analyses were performed to explore the relationships between intraoperative blood loss and several variables including CVP. RESULTS: The mean intraoperative blood loss was 691.3 +/- 365.5 ml. Only four donors required packed red blood cell transfusions (mean, 1.5 U). The mean duration of hepatic resection was 92.1 +/- 26.3 min. The mean, maximum, and minimum values of CVP measured during hepatectomy were 4.6 +/- 1.7, 5.3 +/- 1.8, and 4.0 +/- 1.8 mmHg, respectively, and were not significantly correlated with intraoperative blood loss. On multivariate analysis, predictors of hemorrhage were liver fatty change, gender, and body weight, but none of the mean CVP, surgeons, anesthesiologists, anesthesia duration, resected liver volume, hepatectomy type, systolic blood pressure, heart rate, or body temperature were significant. CONCLUSIONS: CVP during hepatic resection was not associated with intraoperative blood loss in living liver donors, suggesting that CVP may not be an important factor in predicting blood loss during hepatectomy in healthy subjects.

Inactivation of endothelial derived relaxing factor by oxidized lipoproteins.

Endothelial cell derived relaxing factor (EDRF) mediated relaxation of blood vessels is impaired in vessels exposed to lipoproteins in vitro and in arteries of hyperlipidemic humans and animals. To investigate the mechanism by which lipoproteins impair the effects of EDRF, which is likely nitric oxide (NO) or a related molecule, we have bioassayed EDRF/NO activity by measuring its ability to increase cGMP accumulation in rat fetal lung cultured fibroblasts (RFL-6 cells). Low density lipoprotein modified by oxidation (ox-LDL) induced a concentration-dependent inhibition of EDRF activity that had been released from bovine aortic endothelial cells (BAEC) stimulated with bradykinin or the calcium ionophore A23187. In addition, lipoproteins directly impaired authentic NO-induced stimulation of cGMP accumulation in the detector cells; stimulation by sodium nitroprusside was unaffected. Ox-LDL or oxidized HDL3 were highly potent in blocking NO-stimulated cGMP accumulation with EC50's of approximately 1 microgram/ml. Lipid extracted from ox-LDL blocked NO-stimulated cGMP accumulation to about the same extent as intact ox-LDL, while the protein component of ox-LDL did not inhibit the cGMP response. These results suggest that the lipid component of oxidized lipoproteins inactivate EDRF after its release from endothelial cells.

Activation of heat shock protein (hsp)70 and proto-oncogene expression by alpha1 adrenergic agonist in rat aorta with age.

Induction of heat shock proteins (hsp) most likely is a homeostatic mechanism in response to metabolic and environmental insults. We have investigated signal transduction mechanisms involved in alpha1, adrenergic receptor stimulation of hsp7O gene expression in isolated aortas with age. We found that alpha1 adrenergic agonists directly induced hsp70 mRNA in rat aorta in vitro; the alpha1, selective antagonist prazosin blocked this effect whereas chloroethylclonidine, an antagonist which has some selectivity for alpha1B receptors, was ineffective. This response was insensitive to pertussis toxin and was partially blocked by the protein kinase C inhibitor H7. Removal of extracellular calcium attenuated induction of hsp70 mRNA but not the induction of c-fos or c-myc. The induction of hsp70 mRNA by either norepinephrine or by phorbol dibutyrate was blunted in aortas from old (24-27 mo) rats whereas c-fos responses were not diminished in the older vessels. The hsp70 response to elevated temperature (42 degrees C) was not changed with age. Activation of hsp70 expression most likely involves a pertussis toxin insensitive G protein which activates protein kinase C, and requires extracellular calcium. With age, hsp70 gene expression induced by stimulation of alpha1 adrenergic receptors is markedly attenuated, which could modify responses to stress or vascular injury with aging.

Increased cholesterol content of erythrocyte and brain membranes in ethanol-tolerant mice.

Mice were treated with ethanol for eight or nine days, using a liquid diet regimen known to produce physical dependence. In previous experiments, synaptosomal plasma membranes and erythrocyte ghosts from such ethanol-treated animals were found to be resistant to the fluidizing effects of ethanol in vitro, as measured by electron paramagnetic resonance. In the present experiments, corresponding membranes were analysed for phospholipid and cholesterol. The ratio of cholesterol to phospholipid was found to be significantly increased in both types of membrane after chronic ethanol treatment. The changed ratio was produced by an increase in cholesterol. There was little or no change in phospholipid content of the membranes. Increased cholesterol may explain the previously observed alteration of physical properties of the membranes.

Age-related deficit in beta receptor stimulation of cAMP binding in blood vessels.

Both vascular relaxation and cAMP accumulation mediated by beta adrenergic agonists declines with increasing age. We have developed a method to measure the biologically relevant cAMP bound to the regulatory subunits of cAMP-dependent protein kinase in rat aorta. In homogenates of rat aorta, binding of [3H]cAMP was saturable with a Kd of 8.0 +/- 1.5 nM; the dissociation of [3H]cAMP from the binding sites was comprised of fast and slow components at 4 degrees C. Endogenous cAMP binding in aortas stimulated with isoproterenol (10(-5) M) or forskolin (10(-5) M) was quantitated by radioimmunoassay. Compared to basal values, isoproterenol increased cAMP binding by 37% (P less than 0.05) in aortas from young animals (5-6 weeks) but had essentially no effect on binding in older animals (9-11 months). In contrast, forskolin, which causes full relaxation in aortas from older rats, equally elevated bound cAMP values in aortas in the two age groups. In addition, the ratio of total cAMP binding sites to cAMP-dependent protein kinase catalytic activity was 45% higher in aortas from the older rats, suggesting that there were proportionately more regulatory subunits in those vessels. The deficit in isoproterenol-stimulated cAMP binding in vascular smooth muscle in older animals may in part explain the loss in relaxation mediated by beta adrenergic agonists.

Beta-adrenergic responsiveness in cultured vascular smooth muscle cells and fibroblasts: effect of age.

beta-Adrenergic agonists stimulate cyclic 3',5'-adenosine monophosphate (cAMP) accumulation and relaxation in vascular smooth muscle; both of these responses decline in rat aorta with increasing age. To ascertain whether the deficit in beta-receptor stimulated cAMP accumulation persists in isolated aortic smooth muscle cells, the effect of isoproterenol on cAMP accumulation was measured in cultured vascular smooth muscle cells (VSMC) and vascular fibroblasts taken from young (4-6 weeks) and older (8-12 months) Fischer 344 male rats. Immunofluorescent staining confirmed the identity of VSMC as distinct from fibroblasts. Isoproterenol stimulated cAMP accumulation in a time- and concentration-dependent manner in both cell types; maximal cAMP accumulation induced by beta-adrenergic stimulation in cultured cells was much higher than those seen in the intact aorta. While there was a blunting of cAMP response to isoproterenol in fibroblasts cultured from the older rats, the response in VSMC cultured from the older rats was actually increased compared to the VSMC cultured from the younger rats. In contrast, activation of cAMP accumulation in the cultured cells by forskolin was similar in cells from older and young animals. The results suggest that the blunting in isoproterenol-stimulated cAMP accumulation found in aortas from older animals is not seen in VSMC cultured from these animals; whether this change in the culture reflects removal of some extrinsic factor in the older rats or is a consequence of intrinsic changes in the cells in culture requires further investigation.

cAMP signaling mechanisms with aging in rats.

Blunted cAMP responses to beta-adrenergic agonists play a major role in diminished smooth muscle relaxation in blood vessels from older animals, although the mechanisms remain uncertain. A diminished cAMP response could potentially arise from changes in the expression of adenylyl cyclase-coupled G proteins, such as a diminished expression of Gs or an increased expression of Gi. We tested the hypothesis that a loss in Gs or increased expression of Gi could occur in tissues such as the aorta, heart and kidney with aging, which would provide a unifying explanation for blunted cAMP responses to many hormones with aging in a variety of cells. Using Western blotting with specific antibodies, we found no generalized changes in G protein expression with aging. Also, injection of pertussis toxin (which functionally inactivates Gi) into older animals did not restore vascular relaxation mediated by beta-adrenergic receptors. We previously found an elevated ratio of regulatory to catalytic subunits of protein kinase A in the aorta of older rats, which would tend to impair activation of the catalytic unit; this alteration was not generalized to other organs such as the heart and kidney. Old rats fed a low salt diet did not show the restored beta-adrenergic agonist-induced vasodilation previously found in elderly humans, suggesting that there are species differences in the development of this deficit. Altogether, these results suggest that altered G protein expression does not provide a general explanation for blunted activation of adenylyl cyclase with aging.

Progressive dystonia following resuscitation from cardiac arrest.

We report a case of a 55-year-old man in whom progressive extrapyramidal disease developed nearly 1 year after resuscitation from cardiopulmonary arrest. Parkinsonian features evolved within 3 months, and progressive generalized dystonia developed after 11 months. CT and MRI revealed bilateral basal ganglia infarction. Autopsy after 4 years of illness showed bilateral basal ganglia necrosis with preserved corticospinal tracts. These findings support earlier suggestions that postinfarction dystonia is mediated by a pyramidal system lacking normal striatal control.

A new class of adenosine receptors in brain. Characterization by 2-chloro[3H]adenosine binding.

Micromolar concentrations of adenosine and its analogs have profound depressant effects on neuronal firing and synaptic transmission in many brain areas. Using the adenosine agonist 2-chloro[3H]adenosine (Cl[3H]Ado), we have identified a distinct class of micromolar-affinity adenosine binding sites in rat forebrain membranes. Specific Cl[3H]Ado binding was reversible and saturable with an apparent KD of 9.1 microM and a Bmax of 61 pmoles/mg protein. The present studies were conducted using washed brain membrane fractions not treated with adenosine deaminase. Specific Cl[3H]Ado binding under these conditions was insensitive to (-)-N6-(R-phenylisopropyl)adenosine ((-)PIA) and treatment with 3 mM N-ethylmaleimide, unlike high-affinity A1 adenosine receptor binding. Treatment of membranes with adenosine deaminase revealed an additional population of binding sites sensitive to (-)PIA. Inhibition of Cl[3H]Ado binding by adenosine analogs exhibited an order of potency ClAdo greater than 5'-N-ethylcarboxamide adenosine (NECA) greater than (-)PIA which differs from that of both A1 and A2 adenosine receptors. The potent A1 and A2 receptor antagonist 8-phenyltheophylline had no significant effect on binding up to 10 microM. Specific binding, however, was inhibited by the adenosine antagonists 8(p-sulfophenyl)theophylline, isobutylmethylxanthine, theophylline, and caffeine. Micromolar Cl[3H]Ado binding was highly selective for adenosine agonists and antagonists. These results suggest that the micromolar-affinity Cl[3H]Ado binding sites may represent a novel central purinergic receptor, distinct from the A1 and A2 adenosine receptors involved in the regulation of adenylate cyclase.

Magnolol attenuates peroxidative damage and improves survival of rats with sepsis.

Reactive oxygen species and peroxidative damage are implicated in the pathophysiology of sepsis. Magnolol is a compound extracted from the Chinese medicinal herb Magnolia officinalis and has multiple pharmacological effects, notably antioxidant functions. To determine whether magnolol can modulate the course of sepsis, survival rate and biochemical parameters were analyzed in rats with sepsis with various treatment protocols. Magnolol at doses ranging from 10(-9) g/kg to 10(-5) g/kg was administered either before or after induction of sepsis by cecal ligation and puncture. Magnolol did not modulate the course of sepsis induced by two cecal punctures. When one cecal puncture was performed, a moderately evolving type of sepsis was induced, and the survival rate of affected rats was significantly improved by pretreatment with 10(-7) g/kg magnolol. The beneficial effect was partially retained if magnolol was administered 6 hours after onset of sepsis when a higher dose (10(-5) g/kg) was used. The intensity of lipid peroxidation in plasma, liver, and lung of septic rats was also attenuated in a treatment-dependent manner. Magnolol at this dose range exerted these beneficial effects probably through its antioxidant efficacy. These significant results may suggest magnolol as a candidate agent for the treatment of sepsis.

Cobalt ion enhancement of 2-chloro[3H]adenosine binding to a novel class of adenosine receptors in brain: antagonism by calcium.

We have recently reported the identification of a novel class of micromolar-affinity adenosine binding sites in rat brain membranes using the adenosine agonist 2-chloro[3H]adenosine (C1[3H]Ado). These binding sites are distinguishable from the A1 and A2 adenosine receptors by a number of pharmacological criteria, and we have designated this new class of binding sites as the A3 adenosine binding sites. In the present study, the effects of a wide range of divalent and trivalent cations on micromolar C1[3H]Ado binding to brain membranes were examined. Co2+, Ni2+ and La3+ markedly stimulated specific C1[3H]Ado binding by 45-150% above control when tested at concentrations of 1-10 mM. Ca2+ had no significant effect on binding except at high concentrations where it depressed binding slightly. Ca2+, however, completely prevented the stimulation of C1[3H]Ado binding by Co2+. These findings further distinguish the A3 class of adenosine binding sites from the previously characterized adenosine receptors and suggest that the A3 binding sites are associated with calcium systems in brain.

Novel adenosine receptors in rat hippocampus. Identification and characterization.

2-Chloro[3H]adenosine, a stable analog of adenosine, was used to investigate the presence of adenosine receptors in rat hippocampal membranes that may mediate the depressant effects of adenosine on synaptic transmission in this tissue. Equilibrium binding studies reveal the presence of a previously undescribed class of receptors with a KD of 4.7 microM and a Bmax of 130 pmol/mg of protein. Binding is sensitive to alkylxanthines and to a number of adenosine-related compounds. The pharmacological properties of this binding site are distinct from those of the A1 and A2 adenosine receptors associated with adenylate cyclase. The results suggest that this adenosine binding site is a novel central purinergic receptor through which adenosine may regulate hippocampal excitability.

Cholesterol blocks the disordering effects of ethanol in biomembranes.

To assess the relation between the physical order of a membrane and its sensitivity to ethanol, we enriched biomembranes with cholesterol, both in vivo and in vitro. Japanese quail of the SEA line (selectively bred for susceptibility to experimental atherosclerosis) were treated for 9 to 16 weeks with a diet that contained 2% cholesterol. This regimen increased the cholesterol content of serum and erythrocytes. The cholesterol content of brain synaptosomal plasma membranes (SPM) was unaffected by the high cholesterol diet. In other experiments, isolated mouse synaptosomal plasma membranes were incubated with cholesterol/phospholipid (C/P) vesicles; different amounts of cholesterol were transferred according to the sterol content of the donor vesicles. Membrane order was determined in both types of membranes by a sensitive electron paramagnetic resonance (EPR) technique. The order parameter with 5- and 12-doxylstearic acid increased along with the cholesterol content. As expected, ethanol disordered membranes (decreased the order parameter) in a concentration-related manner. The slope of the concentration response curve was less steep in high cholesterol than low cholesterol membranes, indicating that cholesterol enrichment partially blocks the membrane action of ethanol in both types of membranes.

Electron paramagnetic resonance studies of ethanol on membrane fluidity.

An optimum level of fluidity in the membrane appears to be important for some physiological functions. The present studies examined the effects of ethanol in erythrocyte and brain membrane preparations from Swiss Webster mice using electron paramagnetic resonance (EPR) techniques with a fatty acid spin label. The spectral parameter measured was the order parmeter, S, an index of membrane fluidity. Synaptosomal membranes were more fluid than myelin but less fluid than mitochondrial membranes. In low concentrations of 1 and 2 mg/ml of ethanol membrane fluidity was increased in mitochondrial, synaptosomal, and erythrocyte membranes. Dose-related increases in membrane fluidity were also observed at higher concentrations of 4, 8 and 16 mg/ml of ethanol for all of the membranes except myelin. These data indicate that non-lethal concentrations of ethanol may increase membrane fluidity in vivo.

Effects of aliphatic alcohols and aldehydes on fluidity of spin-labeled synaptosomal plasma membranes.

Synaptosomal plasma membranes from Swiss-Webster mice were spin-labeled with 5-doxylstearic acid. By electron paramagnetic resonance techniques an order parameter was measured. A decrease in the order parameter reflected an increase in membrane fluidity. In confirmation of our previous work, ethanol decreased membrane order. Pentanol also showed a concentration-related decrease in the order parameter in the range of 23 to 87 mM. At equimolar concentrations, pentanol was about 9 times more effective than ethanol. Acetaldehyde had no effect on membrane fluidity at concentrations that might be found in vivo during ethanol oxidation (23 or 227 microM) but a very high concentration, 2.3 mM, produced a small decrease in the order parameter comparable to the effect of an intoxicating concentration of ethanol. Valeraldehyde also had a slight fluidizing effect and appeared very roughly three times more potent than acetaldehyde. This study shows that the fluidizing effects of ethanol are not shared by its aldehyde metabolite at relevant concentrations. The fluidizing effects of aldehydes are slight but they increase with concentration and with chain length.

Treatment of irresectible hepatocellular carcinoma with intrahepatic arterial lipoidal mixed with adriamycin and mitomycin C.

Four patients with advanced hepatocellular carcinoma, but with stage I functional disease, were treated with intrahepatic arterial lipoidal mixed with small doses of Adriamycin (20 mg) and Mitomycin C (10 mg). Regression was seen in 3 out of the 4 patients. In 2 patients, there was substantial regression of tumour clinically, radiologically and biochemically. The treatment was tolerable without marrow depression or deterioration of liver function. Mild fever (37 degrees C) was seen in 2 and epigastric pain in 1. This form of treatment opens up scope for further improvement in the management of irresectable hepatocellular carcinoma.