How Well Do We Know the Neutron-Matter Equation of State at the Densities Inside Neutron Stars? A Bayesian Approach with Correlated Uncertainties

We introduce a new framework for quantifying correlated uncertainties of the infinite-matter equation of state derived from chiral effective field theory (χEFT). Bayesian machine learning via Gaussian processes with physics-based hyperparameters allows us to efficiently quantify and propagate theoretical uncertainties of the equation of state, such as χEFT truncation errors, to derived quantities. We apply this framework to state-of-the-art many-body perturbation theory calculations with nucleon-nucleon and three-nucleon interactions up to fourth order in the χEFT expansion. This produces the first statistically robust uncertainty estimates for key quantities of neutron stars. We give results up to twice nuclear saturation density for the energy per particle, pressure, and speed of sound of neutron matter, as well as for the nuclear symmetry energy and its derivative. At nuclear saturation density, the predicted symmetry energy and its slope are consistent with experimental constraints.

Ab Initio Calculations of Low-Energy Nuclear Scattering Using Confining Potential Traps

A recently modified method to enable low-energy nuclear scattering results to be extracted from the discrete energy levels of the target-projectile clusters confined by harmonic potential traps is tested. We report encouraging results for neutron-α and neutron-^{24}O elastic scattering from analyzing the trapped levels computed using two different ab initio nuclear structure methods. The n-α results have also been checked against a direct ab initio reaction calculation. The n-^{24}O results demonstrate the approach's applicability for a large range of systems provided their spectra in traps can be computed by ab initio methods. A key ingredient is a rigorous understanding of the errors in the calculated energy levels caused by inevitable Hilbert-space truncations in the ab initio methods.

The effects of 100% wild blueberry (Vaccinium angustifolium) juice consumption on cardiometablic biomarkers: a randomized, placebo-controlled, crossover trial in adults with increased risk for type 2 diabetes

Background

Wild blueberries have a high content of polyphenols, but there is limited data evaluating their health benefits in adults at risk for type 2 diabetes. The objective of the study was to investigate whether consumption of 100% wild blueberry juice improves cardiometabolic biomarkers associated with type 2 diabetes risk.

Methods

A single-blind, randomized, placebo-controlled, crossover design trial was conducted in which adults (women, n = 19, ages 39–64 y) at risk for type 2 diabetes consumed 240 mL of wild blueberry juice or a placebo beverage as part of their free-living diet for 7 days. Blood was collected to determine various biomarkers such as fasting plasma glucose, fasting serum insulin, surrogate markers of insulin sensitivity, triglycerides, inflammation (interleukin-6, interleukin-10, high-sensitivity C-reactive protein, tumor necrosis factor-alpha, serum amyloid A), adhesion molecules (soluble intercellular adhesion molecule-1, soluble vascular adhesion molecule-1), oxidative stress (LDL-oxidation, total 8-isoprostanes), and nitric oxide. Endothelial function and blood pressure were also assessed.

Results

Wild blueberry juice consumption for 7 days produced no significant changes in glucose, insulin, insulin sensitivity, triglycerides, inflammatory markers, adhesion molecules, oxidative stress, endothelial function or blood pressure. However, wild blueberry juice consumption showed a trend for lowering systolic blood pressure: 120.8 ± 2.2 mmHg in the placebo group vs 116.0 ± 2.2 mmHg in the blueberry juice group (P = 0.088). Serum concentrations of nitrates and nitrites, an index of nitric oxide production, increased from 2.9 ± 0.4 μM after placebo drink to 4.1 ± 0.4 μM after drinking wild blueberry juice (P = 0.039).

Conclusions

Short-term consumption of wild blueberry juice may promote cardioprotective effects, by improving systolic blood pressure, possibly through nitric oxide production, in adults at risk for type 2 diabetes. This outcome warrants longer-term human studies of blueberries, including defined amounts of either the whole fruit or juice, to clarify whether polyphenol-rich foods can be efficacious for improving cardiometabolic biomarkers in adults at risk for type 2 diabetes.

Trial registration

NCT02139878, clinicaltrials.gov; date of registration: May 4, 2014.

Mitochondrial targeting of a catalase transgene product by plasmid liposomes increases radioresistance in vitro and in vivo

To determine whether increased mitochondrially localized catalase was radioprotective, a human catalase transgene was cloned into a small pSVZeo plasmid and localized to the mitochondria of 32D cl 3 cells by adding the mitochondrial localization sequence of MnSOD (mt-catalase). The cell lines 32D-Cat and 32D-mt-Cat had increased catalase biochemical activity as confirmed by Western blot analysis compared to the 32D cl 3 parent cells. The MnSOD-overexpressing 32D cl 3 cell line, 2C6, had decreased baseline catalase activity that was increased in 2C6-Cat and 2C6-mt-Cat subclonal cell lines. 32D-mt-Cat cells were more radioresistant than 32D-Cat cells, but both were radioresistant relative to 32D cl 3 cells. 2C6-mt-Cat cells but not 2C6-Cat cells were radioresistant compared to 2C6 cells. Intratracheal injection of the mt-catalase-plasmid liposome complex (mt-Cat-PL) but not the catalase-plasmid liposome complex (Cat-PL) increased the resistance of C57BL/6NHsd female mice to 20 Gy thoracic irradiation compared to MnSOD-plasmid liposomes. Thus mitochondrially targeted overexpression of the catalase transgene is radioprotective in vitro and in vivo.

Determination of metabolic monitor errors and precision under clinical conditions

BACKGROUND & AIMS

Metabolic monitoring devices used in the critical care setting are subject to a range of conditions that may compromise their accuracy. We sought to investigate the error and precision of the Deltatrac metabolic monitor under these conditions.

METHODS

A modified version of the funnel burner, described by Miodownik et al. (8), was ventilated by a mechanical ventilator. This was used to examine the performance of the Deltatrac metabolic monitor over a wide range of inspired oxygen concentrations, minute ventilation, and positive end expiratory pressure at different levels of oxygen consumption and carbon dioxide production.

RESULTS

The Deltatrac measured V(O(2)) with a mean error+/-precision of 9.4%+/-19.5% (range, 9.3%+/-1.9%-72.6%+/-13.6%). The mean V(CO(2)) error+/-precision was 1.2%+/-3.1% (range-2.0%+/-1.2%-5.4%+/-3.1%). Error was significantly affected by oxygen concentration and minute ventilation but was largely independent of positive and expiratory pressure.

CONCLUSIONS

The methodology of Miodownik et al. permits the expression of metabolic device errors over a wide range of simulated clinical conditions.

Potential mechanisms for the inhibition of tumor cell growth by manganese superoxide dismutase

Studies from many laboratories have shown that overexpression of manganese superoxide dismutase (MnSOD) inhibits the growth of numerous tumor cell types. The inhibition of tumor cell growth can be attributed to the increase in the steady-state levels of H2O2 as a result of the increased dismuting activity of MnSOD. Here we demonstrate that overexpression of MnSOD enhances the activity of the superoxide (O2*-)-sensitive enzyme aconitase, decreases the intracellular GSH/GSSG ratio, and dose-dependently inhibits pyruvate carboxylase activity. Thus, alterations in the steady-state concentrations of mitochondrial O2*- and H2O2 as a result of MnSOD overexpression can alter the metabolic capacity of the cell leading to inhibition of cell growth. Furthermore, we propose that MnSOD overexpression can modulate the activity of nitric oxide (*NO) by preventing its reaction with O2*-. This hypothesis suggests that the redox environment of the mitochondria can be altered to favor the activity of *NO rather than peroxynitrite (ONOO-) and may explain the enhanced toxicity of *NO-generating compounds toward MnSOD-overexpressing cell lines. These findings indicate that therapeutic strategies targeted at overexpressing MnSOD in tumor tissue may be more effective when used in combination with agents that deplete the oxidant-buffering and enhance the *NO-generating capacity of the tumor and host, respectively.

Manganese superoxide dismutase signals matrix metalloproteinase expression via H2O2-dependent ERK1/2 activation

Manganese-superoxide dismutase (Sod2) removes mitochondrially derived superoxide (O(2)) at near-diffusion limiting rates and is the only antioxidant enzyme whose expression is regulated by numerous stimuli. Here it is shown that Sod2 also serves as a source of the intracellular signaling molecule H(2)O(2). Sod2-dependent increases in the steady-state levels of H(2)O(2) led to ERK1/2 activation and subsequent downstream transcriptional increases in matrix metalloproteinase-1 (MMP-1) expression, which were reversed by expression of the H(2)O(2)-detoxifying enzyme, catalase. In addition, a single nucleotide polymorphism has recently been identified (1G/2G) at base pair--1607 that creates an Ets site adjacent to an AP-1 site at base pair --1602 and has been shown to dramatically enhance transcription of the MMP-1 promoter. Luciferase promoter constructs containing either the 1G or 2G variation were 25- or 1000-fold more active when transiently transfected into Sod2-overexpressing cell lines, respectively. The levels of MMP-2, -3, and -7 were also increased in the Sod2-overexpressing cell lines, suggesting that Sod2 may function as a "global" redox regulator of MMP expression. In addition, Sod2(-/+) mouse embryonic fibroblasts failed to respond to the cytokine-mediated induction of the murine functional analog of MMP-1, MMP-13. This study provides evidence that the modulation of Sod2 activity by a wide array of pathogenic and inflammatory stimuli may be utilized by the cell as a primary signaling mechanism leading to matrix metalloproteinase expression.

Localization and regulation of IL-1alpha in rat myometrium during late pregnancy and the postpartum period

Interleukin-1 (IL-1) has been implicated as a participant in preterm labor that is induced by bacterial infection. Previously, we showed that serotonin-induced production of IL-1alpha by myometrial smooth muscle cells in vitro is also essential for the synthesis of interstitial collagenase. It is therefore likely that IL-1alpha production in uterine tissues has implications for both the normal physiology of involution and for the pathophysiological mechanisms of preterm labor. The objective of this study was to characterize the serotonin-induced production of IL-1alpha by myometrial cultures in vitro and to assess the production of IL-1alpha and its relationship to collagenase production in vivo during pregnancy and the postpartum period. Immunohistochemistry demonstrated IL-1alpha protein in the nuclei and cytoplasm of serotonin-treated myometrial cells. IL-1alpha levels were decreased by treatment with progesterone or IL-1-receptor antagonist but were unaffected by lipopolysaccharide. Western analysis of myometrium from pregnant rats showed low levels of IL-1alpha during midpregnancy with increased concentrations at days 21 and 22 and postpartum. IL-1alpha mRNA levels also increased from days 15 to 22. Levels of mRNA for IL-1beta also increased, although to a lesser degree than IL-1alpha. Both mRNAs decreased postpartum. Conversely, mRNA for interstitial collagenase was barely detectable at term but increased postpartum. Together, these data show that serotonin stimulates IL-1alpha production in vitro and indicate that normal myometrium from pregnant rats is an identifiable source of IL-1 during late pregnancy. The findings are consistent with the possibility that myometrial IL-1alpha participates in normal labor as well as the postpartum production of interstitial collagenase.

Correlation of peripheral venous pressure and central venous pressure in surgical patients

OBJECTIVE

To determine the degree of agreement between central venous pressure (CVP) and peripheral venous pressure (PVP) in surgical patients.

DESIGN

Prospective study.

SETTING

University hospital.

PARTICIPANTS

Patients without cardiac dysfunction undergoing major elective noncardiac surgery (n = 150).

MEASUREMENTS AND MAIN RESULTS

Simultaneous CVP and PVP measurements were obtained at random points in mechanically ventilated patients during surgery (n = 100) and in spontaneously ventilating patients in the postanesthesia care unit (n = 50). In a subset of 10 intraoperative patients, measurements were made before and after a 2-L fluid challenge. During surgery, PVP correlated highly to CVP (r = 0.86), and the bias (mean difference between CVP and PVP) was -1.6 +/- 1.7 mmHg (mean +/- SD). In the postanesthesia care unit, PVP also correlated highly to CVP (r = 0.88), and the bias was -2.2 +/- 1.9 (mean +/- SD). When adjusted by the average bias of -2, PVP predicted the observed CVP to within +/-3 mmHg in both populations of patients with 95% probability. In patients receiving a fluid challenge, PVP and CVP increased similarly from 6 +/- 2 to 11 +/- 2 mmHg and 4 +/- 2 to 9 +/- 2 mmHg.

CONCLUSION

Under the conditions of this study, PVP showed a consistent and high degree of agreement with CVP in the perioperative period in patients without significant cardiac dysfunction. PVP -2 was useful in predicting CVP over common clinical ranges of CVP. PVP is a rapid noninvasive tool to estimate volume status in surgical patients.

A comparative study between a calcium channel blocker (Nicardipine) and a combined alpha-beta-blocker (Labetalol) for the control of emergence hypertension during craniotomy for tumor surgery

We compared the efficacy of the combination of enalaprilat/labetalol with that of enalaprilat/nicardipine to prevent emergence postcraniotomy hypertension. A prospective, randomized open labeled clinical trial was designed to compare the incidence of breakthrough hypertension (systolic blood pressure [SBP] > 140 mm Hg) and adverse effects (hypotension, tachycardia, and bradycardia) between the two drug combinations. Secondarily, the effects of the drugs on SBP, mean blood pressure, and diastolic blood pressure were evaluated over the course of the study. Forty-two patients received enalaprilat 1.25 mg IV at dural closure followed by either multidose nicardipine 2 mg IV or labetalol 5 mg IV to maintain the SBP below 140 mm Hg. SBP was similarly controlled in both groups. There was a marginally smaller incidence of failures and adverse effects with labetalol. Blood pressure profiles were similar for both groups.

Reactive oxygen species generated at mitochondrial complex III stabilize hypoxia-inducible factor-1alpha during hypoxia: a mechanism of O2 sensing

During hypoxia, hypoxia-inducible factor-1alpha (HIF-1alpha) is required for induction of a variety of genes including erythropoietin and vascular endothelial growth factor. Hypoxia increases mitochondrial reactive oxygen species (ROS) generation at Complex III, which causes accumulation of HIF-1alpha protein responsible for initiating expression of a luciferase reporter construct under the control of a hypoxic response element. This response is lost in cells depleted of mitochondrial DNA (rho(0) cells). Overexpression of catalase abolishes hypoxic response element-luciferase expression during hypoxia. Exogenous H(2)O(2) stabilizes HIF-1alpha protein during normoxia and activates luciferase expression in wild-type and rho(0) cells. Isolated mitochondria increase ROS generation during hypoxia, as does the bacterium Paracoccus denitrificans. These findings reveal that mitochondria-derived ROS are both required and sufficient to initiate HIF-1alpha stabilization during hypoxia.

System of automated gas-exchange analysis for the investigation of metabolic processes

Conventional gas-exchange instruments are confined to the measurement of O(2) consumption (VO(2)) and CO(2) production (VCO(2)) and are subject to a variety of errors. This handicaps the performance of these devices at inspired O(2) fraction (FI(O(2))) > 0.40 and limits their applicability to indirect calorimetry only. We describe a device based on the automation of the Douglas bag technique that is capable of making continuous gas-exchange measurements of multiple species over a broad range of experimental conditions. This system is validated by using a quantitative methanol-burning lung model modified to provide reproducible (13)CO(2) production. The average error for VO(2) and VCO(2) over the FI(O(2)) range of 0.21-0.8. is 2.4 and 0.8%, respectively. The instrument is capable of determining the differential atom% volume of known references of (13)CO(2) to within 3.4%. This device reduces the sources of error that thwart other instruments at FI(O(2)) > 0. 40 and demonstrates the capacity to explore other expressions of metabolic activity in exhaled gases related to the excretion of (13)CO(2).

Overexpression of catalase in cytosolic or mitochondrial compartment protects HepG2 cells against oxidative injury

HepG2 cells were transfected with vectors containing human catalase cDNA and catalase cDNA with a mitochondrial leader sequence to allow comparison of the effectiveness of catalase overexpressed in the cytosolic or mitochondrial compartments to protect against oxidant-induced injury. Overexpression of catalase in cytosol and in mitochondria was confirmed by Western blot, and activity measurement and stable cell lines were established. The intracellular level of H(2)O(2) induced by exogenously added H(2)O(2) or antimycin A was lower in C33 cell lines overexpressing catalase in the cytosol and mC5 cell lines overexpressing catalase in the mitochondria as compared with Hp cell lines transfected with empty vector. Cell death caused by H(2)O(2), antimycin A, and menadione was considerably suppressed in both the mC5 and C33 cell lines. C33 and mC5 cells were also more resistant to apoptosis induced by H(2)O(2) and to the loss of mitochondrial membrane potential induced by H(2)O(2) and antimycin A. In view of the comparable protection by catalase overexpressed in the cytosol versus the mitochondria, catalase produced in both cellular compartments might act as a sink to decompose H(2)O(2) and move diffusable H(2)O(2) down its concentration gradient. The present study suggests that catalase in cytosol and catalase in mitochondria are capable of protecting HepG2 cells against cytotoxicity or apoptosis induced by oxidative stress.

Progesterone mediates decreases in uterine smooth muscle cell interleukin-1alpha by a mechanism involving decreased stability of IL-1alpha mRNA

The regulation, by progesterone, of serotonin-induced interleukin-1alpha production was studied in primary cultures of rat uterine smooth muscle cells. Prior reports from this laboratory have demonstrated that these cells produce IL-1alpha and IL-1beta mRNAs in response to the hormonal action of serotonin. Results of the present study indicate that treatment of myometrial smooth muscle cells with medroxyprogesterone acetate (MPA) results in a marked decrease in IL-1alpha protein as measured by western blot analysis. These decreases occur even in the presence of maximally-inducing concentrations of serotonin. MPA-mediated changes in IL-1alpha protein are characterized by a rapid decline in IL-1alpha mRNA levels. This inhibition by medroxyprogesterone also occurs when cells are stimulated to produce IL-1alpha by PMA rather than serotonin. Thus, when cells are cultured in the presence of both inducer and inhibitor, the inhibitor, progesterone, clearly dominates in the control of IL-1alpha expression. This effect is concentration-dependent, can be mimicked by native progesterone or glucocorticoids, but is unaffected by estradiol. The ability of progestins to decrease IL-1alpha mRNA is blocked by both inhibitors of transcription and translation and by treatment with RU-486. Progesterone had no effect on chloramphenicol acetyl transferase (CAT) transcription from two different IL-1alpha promoter constructs, indicating that progesterone's action appears to be dependent on post-transcriptional rather than transcriptional regulation. Conversely, progesterone accelerated the normal rate of decay of IL-1alpha mRNA that occurs following the removal of serotonin from the cultures. These results suggest that progesterone decreases IL-1alpha levels by stimulating the production of an intracellular intermediate that decreases the stability of IL-1alpha mRNA.

Nitric oxide enhances the manganese superoxide dismutase-dependent suppression of proliferation in HT-1080 fibrosarcoma cells

The overexpression of manganese superoxide dismutase (MnSOD), an enzyme that catalyzes the removal of superoxide (O2*-) from the mitochondria, has been shown to be closely associated with tumor regression in vivo and loss of the malignant phenotype in vitro. To investigate the mechanism by which MnSOD overexpression mediates this reversal, we have established 29 independent, clonal MnSOD-overexpressing HT-1080 fibrosarcoma cells. MnSOD activity is inversely correlated with cell proliferation in our cell lines. Incubating cells in 3% oxygen can prevent the inhibition of cellular proliferation mediated by MnSOD, suggesting that oxygen is a prerequisite component of the MnSOD-dependent proliferative inhibition. Confocal laser microscopy was used in combination with the oxidant-sensitive fluorescent dyes dihydrorhodamine-123, dihydroethidium, and 2',7'-dichlorodihydrofluorescein diacetate to determine the oxidizing capacity of the MnSOD-overexpressing cells. When compared with parental or control cell lines, there was a significant decrease in the rate of oxidation of the fluorophores in the MnSOD-overexpressing cell lines. Thus, an increase in the oxidizing capacity of the cells does not appear to mediate the inhibition of proliferation associated with MnSOD overexpression. Superoxide dismutase has also been shown to enhance the cytotoxic activity of NO* toward tumor cells. In this study, we have shown that MnSOD overexpression enhances the cytostatic action of the NO* donors, sodium nitroprusside, 3-morpholinosydnonomine, and (Z)-1-[2-aminethyl)-N-(2-ammonioethyl)amino]diazen-1-+ ++ium-1,2-diolate in a dose-dependent manner. In addition, the NO* toxicity is blocked by oxyhemoglobin, a NO* scavenger. Our findings suggest that NO* may play a role in the reversal of tumorigenicity associated with MnSOD overexpression.

Perioperative outcomes of major hepatic resections under low central venous pressure anesthesia: blood loss, blood transfusion, and the risk of postoperative renal dysfunction

BACKGROUND

We have previously demonstrated that maintenance of a low central venous pressure (LCVP) combined with extrahepatic control of venous outflow reduced the overall blood loss during major hepatic resections. This study examined the overall outcomes and, in particular, renal morbidity associated with a large series of consecutive major liver resections performed with this approach. In addition, the rationale for the anesthetic management to maintain LCVP was carefully reviewed.

STUDY DESIGN

All major hepatectomies performed between December 1991 and April 1997 were reviewed. The prospective Hepatobiliary Surgical Service database was merged with the Memorial Hospital Laboratory and Blood Bank databases to yield the nature of the operation, blood loss, blood product transfusions, outcomes, and levels of preoperative, postoperative, and discharge serum creatinine and blood urea nitrogen.

RESULTS

A total of 496 LCVP-assisted major liver resections were performed, with no intraoperative deaths and an in-hospital mortality rate of 3.8%. The median blood loss was 645 mL. Sixty-seven percent of the patients did not require perioperative blood transfusion during surgery and the immediate 12 hours after surgery. The median number of blood transfusions was 2. Only 3% of the patients experienced a persistent and clinically significant increase in serum creatinine possibly attributable to the anesthetic technique. Renal failure directly attributable to the anesthetic technique did not occur.

CONCLUSIONS

Major resection with LCVP allowed easy control of the hepatic veins before and during parenchymal transection. The anesthetic technique, designed to maintain LCVP during the critical stages of hepatic resection, not only helped to minimize blood loss and mortality but also preserved renal function.

Serotonin-mediated production of interstitial collagenase by uterine smooth muscle cells requires interleukin-1alpha, but not interleukin-1beta

The activation of the gene for interstitial collagenase in myometrial smooth muscle cells is absolutely dependent upon the presence of serotonin. Our previous studies investigating the mechanisms of this induction demonstrated that the mRNAs of both interleukin-1 (IL-1) isoforms, IL-1alpha and IL-1beta, are induced by serotonin and that the induction of IL-1 is required for the subsequent induction of collagenase. These data provided compelling evidence that serotonin-induced IL-1 acts via an autocrine loop in activating the collagenase gene. The experiments described here were designed to examine the potential role of each IL-1 isoform in collagenase production by using neutralizing antisera specific to each isoform of the cytokine. The antisera were examined for their ability to inhibit the serotonin-dependent production of the mRNA for collagenase and of the cytokines themselves. Neutralizing antiserum against IL-1alpha, but not against IL-1beta, inhibited the induction of the mRNA for collagenase and of the mRNAs for both IL-1alpha and IL-1beta. Western analysis indicated that detectable levels of IL-1alpha protein, but not that of IL-1beta, are produced at the time of serotonin-dependent collagenase induction. In contrast, significant levels of IL-1beta protein are detected only when bacterial lipopolysaccharide is added to the cells. Taken together, the results of our study indicate that IL-1alpha, but not IL-1beta, plays an obligatory role in multiple serotonin-mediated gene regulations in the myometrial smooth muscle cell. In addition, the data suggest that IL-1beta production has the potential for modifying myometrial function in pathological settings, particularly that of uterine infection.

Predictive respiratory complication quotient predicts pulmonary complications in thoracic surgical patients

BACKGROUND

This study was designed to develop an accurate preoperative index of prediction of outcome and hospital charges after lung resection with standard available pulmonary tests in a tertiary cancer center.

METHODS

Sixty-one consecutive patients undergoing pulmonary resections were evaluated. All patients underwent spirometry, carbon monoxide diffusion capacity, split lung function testing, and room air blood gas analysis at rest and after a 2-minute step climb. The thoracic prospective data base and patient charts were reviewed for length of hospitalization, postoperative length of stay, and complications requiring therapy. Logistic regression analysis of the preoperative data, operation and postoperative outcome was used to develop a new postoperative predictive index: the predictive respiratory complication quotient (PRQ). We describe the design of the equation for the probability of serious pulmonary complications, hospital stay, and hospital charges based on PRQ.

RESULTS

Ten of 12 patients with a PRQ less than 2,200 suffered serious pulmonary complications of pneumonia, respiratory insufficiency, hypoxemia, and death. Forty-nine patients with a PRQ more than 2,200 did not experience any pulmonary complications. Postoperative length of stay and hospital charges correlated with the PRQ.

CONCLUSIONS

A construct such as the PRQ may provide a better prediction of outcome than its individual parts. We identified an important underlying relationship between intensive care unit stay, hospital stay and charges, and our index. A PRQ of less than 2,200 was associated with an increased risk of pulmonary complications and mortality.

Cardiopulmonary risk index does not predict complications after thoracic surgery

STUDY OBJECTIVE

The preoperative cardiopulmonary risk index (CPRI) is a multifactorial index intended to predict postoperative outcome after thoracic surgery. It combines cardiac and pulmonary information into one parameter that ranges from 1 to 10, with 10 being the worst. A CPRI > or = 4 has been advocated as an effective predictor of postoperative pulmonary and cardiac complications. This study prospectively evaluates the predictive value of CPRI in a large population of patients undergoing thoracic surgery.

DESIGN

We performed prospective calculation of CPRI in patients about to undergo thoracic surgery. Postthoracic surgery occurrence of pneumonia, atelectasis, arrhythmias, congestive heart failure, respiratory failure requiring therapy, or death occurring within 30 days of surgery was compared with preoperative CPRI and its components.

PATIENTS AND PARTICIPANTS

One hundred eighty consecutive patients, aged 15 to 87 years, were studied.

INTERVENTIONS

Operations performed included 114 lobectomies, 35 wedge resections, 19 pneumonectomies, 5 pleurectomies, 5 lymph node dissections, 1 thoracic wall resection, and 1 paravertebral tumor resection.

MEASUREMENTS AND RESULTS

Twenty-seven percent of patients experienced complications. CPRI and its components did not predict complications, deaths, or the number of in-hospital days. We found a CPRI > or = 4 to be a moderate predictor of outcome for patients undergoing pneumonectomy (n = 19). It correctly identified four of nine postpneumonectomy complications.

CONCLUSION

The preoperative CPRI and its components are inadequate predictors of medical complications after thoracic surgery in a general population. In the subgroup of patients undergoing pneumonectomy, the index may be of some value in forecasting outcome.

Use of preoperative autologous blood donation in liver resections for colorectal metastases

BACKGROUND

Transfusion of allogeneic blood is associated with risks of human immunodeficiency virus and hepatitis transmission, transfusion reactions, and other potential immunologic and infectious complications. To determine if predonation of autologous blood impacts upon transfusion practice and clinical outcome following liver resection, clinical records of 379 consecutive patients undergoing hepatic resection for metastases of colorectal cancer were identified from the prospective hepatobiliary database and reviewed.

METHODS

Of the 379 hepatic resections performed for colorectal metastases between January 1991 and January 1996, 240 (63%) were hepatic lobectomy or trisegmentectomy. Thirty-two percent of patients (123 of 379) agreed to preoperative blood donation (POBD), and their clinical characteristics including age, preoperative hemoglobin, and operative mortality were comparable with those of patients without POBD. Liver resections were carried out using standard vascular inflow and outflow control. Parenchymal transections were performed bluntly with maintenance of low central venous pressure (0 to 5 cm H2O). No vascular isolation or normovolemic hemodilution was used intraoperatively. All erythrocyte transfusions during the entire hospital stay were considered and compared between the two groups.

RESULTS

Forty-five percent of patients (172 of 379) received blood transfusions during or after liver resections, of which 61% (105 of 172) required only 1 or 2 units. Only 17% of the POBD group required allogeneic blood. This was significantly less than the group without POBD (43%, P <0.01). There was no significant difference in the operative mortality (2.3% versus 4.9%, P = 0.2) and the median survival (50 versus 40 months, P = 0.3).

CONCLUSIONS

Major hepatic resections using current surgical techniques can be performed safely with low blood loss and transfusion is required for only a minority of patients. POBD further reduces transfusion requirement.

Cloning of the cDNA and nucleotide sequence of a skeletal muscle protease from myopathic hamsters

A neutral protease with an estimated Mr of about 26 kD and responsible for cleavage ofmyosin LC2 was isolated from hamster skeletal muscle. Complementary DNAs were generated by RT-PCR using total hamster muscle RNA and degenerate oligonucleotide primers based on the sequences of two internal peptides. The nucleotide sequences of the resultant cDNAs were subsequently determined and the complete amino acid sequence of the protease deduced. Although the hamster protein shared 63-85% identity in nucleotide and amino acid sequences with rat and mouse mast cell proteases, it had a higher degree of specificity for myosin LC2 than mast cell proteases which also digested myosin LC1 and myosin heavy chains. As a result, the hamster protease was designated mekratin because of its unique enzymatic specificities to distinguish it from other mast cell proteases. A polyclonal antibody was raised specific to the hamster muscle and human cardiac muscle mekratins without apparent cross-reaction with rat mast cell proteases. We have earlier demonstrated the presence in excess of a neutral protease that specifically cleaves LC2 in human hearts obtained at end stage idiopathic dilated cardiomyopathy (IDC). Western analyses revealed that heart tissue from patients with IDC contained 5-10 fold more mekratin than control samples. Furthermore, the level of the protease in human IDC tissues was similar to that seen in myopathic hamster skeletal muscle. No bands were recognized by the antibody when IDC myofibrils were probed due to the removal of soluble proteins during sample preparation. Thus, these results strongly suggest that the anti-mekratin antibody will provide positive identification of IDC in many cases and diagnosis by exclusion may be replaced.

Preoperative pulmonary evaluation of the thoracic surgical patient

A test designed to separate those undergoing thoracic surgery without complications and those with complications must be both highly specific and sensitive. Clearly, the difference between patients at opposite ends of the population curves is easy to identify. Spirometry can be helpful for screening, although it is not a very discriminating test. If patients fall in the overlap region between the populations, however, it is impossible to discern the risks with any certainty using low-yield tests. A test with higher sensitivity, specificity, and predictive values is necessary to ascertain such marginal differences. With this kind of analysis at hand, preoperative testing can be divided into three predictive value groups. Calculating the predictive value of each preoperative test can provide a comparative measure of usefulness of discriminative power (Table 1). In this way, spirometry, blood gas analysis, and stair climbing tolerance are shown to be poor predictors of outcome. An intermediate predictive value can be achieved using diffusion capacity, exercise-induced decreases in O2 saturation, and exercise PVR. High predictive value can be accomplished with combination indexes (PPP, possibly PRQ), measurement of VO2 at 40 watts of exercise, or VO2max. Logic dictates a step-wise preoperative evaluation using prediction value analysis (Fig.4). A flow decision chart for the preoperative evaluation of patients for pulmonary resection begins with exercise oximetry, spirometry, and blood gas analysis as general screening tests to separate those patients at minimal or no risks for complications from those patients that require further evaluation. Functional indexes (PPP, PRQ) or exercise testing can aid further in the selection of those patients in whom a nonsurgical option should be considered. Flow decision chart for the preoperative evaluation of patients for pulmonary resection should continue to evolve as new information about outcome studies is gathered. Examination of outcome data will provide us with reduction of the size of the nonoperable population, so that we can deny only those patients who truly pose a prohibitive risk.

Manganese superoxide dismutase modulates interleukin-1alpha levels in HT-1080 fibrosarcoma cells

Reactive oxygen species of mitochondrial origin have been implicated in regulating the expression of several tumor necrosis factor (TNF)-induced genes. Manganese superoxide dismutase (Mn-SOD) is one of many genes, but only antioxidant enzyme, induced in response to tumor necrosis factor. Mn-SOD is a nuclear-encoded mitochondrial matrix protein and serves a protective function by detoxifying superoxide. To address the role of superoxide in regulating gene expression in response to TNF, we have constitutively overexpressed Mn-SOD in a human fibrosarcoma cell line and asked what effect this has on the expression of a number of TNF-responsive genes using reverse transcription-polymerase chain reaction. Of the TNF-induced transcripts analyzed, only interleukin-1alpha (IL-1alpha) was modulated in response to Mn-SOD overexpression. In all cases of Mn-SOD overexpression, IL-1alpha protein and mRNA levels were lowered constitutively and in response to TNF when compared to the parental and mock-transfected cell lines. The induction of IL-1alpha by TNF can also be decreased by growth in 3% oxygen as compared to growth in 21% O2; in addition, growth in low oxygen lowers the basal level of IL-1alpha protein. The effect of Mn-SOD overexpression on IL-1alpha expression can be overcome by treatment with the protein kinase C activator, phorbol 12-myristate 13-acetate. Mn-SOD overexpression and low oxygen alter IL-1alpha mRNA levels by decreasing the stability of the IL-1alpha mRNA. These findings indicate that both Mn-SOD and O2 may regulate the levels of a cellular oxidant involved in both basal and TNF-induced IL-1alpha expression, presumably superoxide.

Pertussis toxin treatment alters manganese superoxide dismutase activity in lung. Evidence for lung oxygen toxicity in air-breathing rats

Exposure of rats to hyperoxia or to treatment with endotoxin, increases lung manganese superoxide dismutase (MnSOD) gene expression. However, the paths by which these environmental signals are transduced into enhanced MnSOD gene expression are unknown. We now provide evidence that heterotrimeric G proteins are involved in the hyperoxia-induced increase in lung MnSOD gene expression but that pertussis toxin-sensitive G proteins are not involved in the endotoxin-induced elevation of lung MnSOD gene expression. We also show that treating rats with pertussis toxin decreased lung MnSOD activity approximately 50%. This decline in MnSOD activity occurred without a change in the lung activity of copper-zinc SOD, catalase, or glutathione peroxidase. In air-breathing rats, the pertussis toxin-induced decrease in MnSOD activity was associated with the development of lung edema, pleural effusion with a high concentration of protein, and biochemical evidence of lung oxygen toxicity. Compared to air-breathing rats, maintenance of pertussis toxin-treated rats under hypoxic or hyperoxic conditions respectively decreased or increased intrathoracic fluid. Endotoxin treatment elevated lung MnSOD activity and protected pertussis toxin-treated rats from an increase in intrathoracic fluid.

Differential induction and decay of manganese superoxide dismutase mRNAs

Human manganese superoxide dismutase (MnSOD) is encoded by two mRNAs of 4 and 1 kb, respectively. These mRNAs are transcribed from the same gene and have an identical coding sequence, but differ in the 3' untranslated sequence because of alternate polyadenylation. Tumor necrosis factor-alpha (TNF) induced both 4- and 1-kb mRNAs in all the human cell lines examined. However, the relative expression of these mRNAs varied significantly among different cell lines after an 8-h treatment with TNF. Therefore, the time course of induction by TNF and the decay of MnSOD mRNAs after TNF removal were analyzed. The rate of accumulation of the 4-kb mRNA was initially much greater than that of the 1-kb mRNA, suggesting that the 4-kb mRNA was produced faster than the 1-kb mRNA. The rapid accumulation of the 4-kb mRNA was offset after a few hours by an enhanced rate of decay. The half-life of the 4-kb mRNA was approximately 2-4 h in different cells while that of the 1-kb mRNA was approximately 10-12 h. This different half-life of mRNAs that encode the same protein suggests that their relative expression is also regulated by a post-transcriptional mechanism affecting their turnover. Additional evidence supporting the differential decay of the two MnSOD mRNAs was obtained by incubation in a rabbit reticulocyte cell-free system; the 4-kb mRNA decayed rapidly while the 1-kb mRNA appeared to be stable.

Postthoracotomy respiratory muscle mechanics during incentive spirometry using respiratory inductance plethysmography

We undertook this study to characterize the postthoracotomy compartmental displacement and respiratory mechanical changes occurring during and after the performance of the incentive spirometry maneuver. We also evaluated the effect of recumbency angle on compartmental recruitment. Sixteen patients were randomized to perform incentive spirometry either at 30 degrees or 60 degrees recumbency angle. They were studied using respiratory inductance plethysmography to measure tidal volume, respiratory frequency, inspiratory time, rib cage motion/tidal volume ratio, inspiratory duty cycle, and inspiratory flow. Patients were studied before surgery and on postoperative days 1 and 3. Statistical analysis was accomplished using multiple measures ANOVA with post-hoc Student's t-tests when appropriate. Preoperative incentive spirometry augmented VT by increasing both VT/TI and TI. Postoperatively, the incentive recruitment of VT was reduced, a result of a decrease in TI and TI/TTOT; VT/TI was unchanged. There was postoperative decrease of AB and AB/VT during incentive spirometry, greatest in the 60 degrees group. Our results characterize the nature of the respiratory recruitment afforded by incentive spirometry, before and after thoracotomy. We also found evidence of postthoracotomy diaphragmatic derecruitment during incentive spirometry exacerbated by a high recumbency angle.

Reduced expression of manganese superoxide dismutase in cells resistant to cytolysis by tumor necrosis factor

Tumor necrosis factor (TNF) induces synthesis of manganese superoxide dismutase (MnSOD). It was previously shown that overexpression of MnSOD protected some mammalian cells from TNF cytotoxicity. The purpose of this study was to establish whether MnSOD was increased in cells selected for resistance to cytolysis by TNF in combination with cycloheximide. Melanoma SK-MEL-109 and HeLa cell-resistant variants were selected by repeated treatments with TNF and cycloheximide. The SK-MEL-109 variants had relatively low levels of MnSOD that were inducible by TNF. Surprisingly, the HeLa variants had very low levels of MnSOD that were poorly inducible by either TNF or interleukin-1 alpha. Therefore, an elevated level of MnSOD was not required to protect these cells from TNF-mediated cytolysis. The HeLa variants were more sensitive than parental cells to superoxide radical (O2-) generating compounds, such as paraquat or xanthine/xanthine oxidase. Pretreatment of these variants with TNF did not provide protection against damage by superoxide radicals.

Noncardiac surgery in heart transplant recipients in the cyclosporine era

As survival and quality of life continue to improve for cardiac transplant recipients, there is an ever-increasing possibility that these patients will present for elective and/or emergency surgery outside of a transplantation center. Cyclosporine therapy has been a major factor in extending homograft survival, but recent studies have suggested that cyclosporine administration increases the duration of action of some anesthetics. The authors evaluated the influence on anesthetic management of cardiac transplantation and chronic cyclosporine therapy in a retrospective review of all postcardiac transplant patients who presented for noncardiac surgery at the study institution. The data suggest that a number of commonly used anesthetic techniques can be administered safely to these patients when no evidence of graft rejection is present. No clinically significant prolongation of anesthetic effect was encountered following the doses of anesthetics described.

Influence of temperature on in vitro metabolism of esmolol

Esmolol has been used to improve hemodynamic stability during sternotomy and aortic manipulation for coronary artery bypass graft surgery. In order to investigate the alterations of esmolol metabolism by hypothermic cardiopulmonary bypass (CPB), the effect of temperature on the metabolism of esmolol in vitro was determined. Samples of human whole blood were combined with esmolol solution (50 micrograms/mL in 0.9 mol/L NaCl) and incubated at 4 degrees C, 15 degrees C, 25 degrees C, and 37 degrees C. Aliquots were sampled at 1, 5, 10, 15, 30, 60, and 120 minutes; esmolol concentration was determined using high-pressure liquid chromatography. There was a temperature-dependent decrease in the degradation of esmolol. The half-life for esmolol in human blood was 19.6 +/- 3.8 minutes at 37 degrees C, 47 +/- 10.1 minutes at 25 degrees C, 152 +/- 46.6 minutes at 15 degrees C, and 226.7 +/- 60.1 minutes at 4 degrees C. This study clearly shows marked reduction of esmolol metabolism with hypothermia possibly leading to persistent beta-adrenergic blockade following the discontinuation of CPB. Persistent beta-blockade may provide additional protection to the ischemic myocardium during hypothermic arrest and/or result in difficulty in weaning from CPB.

Lumbar epidural fentanyl analgesia after thoracic surgery

Thoracic epidural fentanyl has been used successfully for postoperative analgesia in patients undergoing thoracic surgery. Prior investigators have suggested that increasing the administered dosage and volume of lumbar epidural fentanyl may increase the spread of analgesia. The feasibility of injecting a high volume (20 mL) of fentanyl into the lumbar epidural space for post-thoracic surgery analgesia was studied in 17 patients undergoing elective thoracotomy or sternotomy. All patients had a lumbar epidural catheter placed before induction of general anesthesia. No narcotic was administered during surgery. Thirty minutes before the conclusion of anesthesia, 200 micrograms of fentanyl in 16 mL of 0.9% saline was administered via the epidural route. In the intensive care unit (ICU), additional fentanyl in the same dosage and volume was injected when the patient complained of pain. Pain was scored on a linear analog scale pre-injection and 30 minutes post-injection. Arterial blood gases were obtained simultaneously. All patients experienced pain relief within 15 minutes of injection. No significant respiratory depression or hypercarbia was noted. Lumbar epidural fentanyl is a safe and practical alternative to thoracic epidural analgesia in the post-thoracic surgical patient.