Effects of prolonged endotoxemia on liver, skeletal muscle and kidney mitochondrial function

INTRODUCTION: Sepsis may impair mitochondrial utilization of oxygen. Since hepatic dysfunction is a hallmark of sepsis, we hypothesized that the liver is more susceptible to mitochondrial dysfunction than the peripheral tissues, such as the skeletal muscle. We studied the effect of prolonged endotoxin infusion on liver, muscle and kidney mitochondrial respiration and on hepatosplanchnic oxygen transport and microcirculation in pigs. METHODS: 20 anesthetized pigs were randomized to receive endotoxin or saline infusion for 24 hours. Muscle, liver and kidney mitochondrial respiration was assessed. Cardiac output (thermodilution), carotid, superior mesenteric and kidney arterial, portal venous (ultrasound Doppler) and microcirculatory blood flow (laser Doppler) were measured, and systemic and regional oxygen transport and lactate exchange were calculated. RESULTS: Endotoxin infusion induced hyperdynamic shock and impaired the glutamate- and succinate-dependent mitochondrial respiratory control ratio (RCR) in the liver (glutamate: endotoxemia: median [range] 2.8 [2.3-3.8] vs. controls: 5.3 [3.8-7.0]; p<0.001; succinate: endotoxemia: 2.9 [1.9-4.3] vs. controls: 3.9 [2.6-6.3] p=0.003). While the ADP:O ratio was reduced with both substrates, maximal ATP production was impaired only in the succinate-dependent respiration. Hepatic oxygen consumption and extraction, and liver surface laser Doppler blood flow remained unchanged. Glutamate-dependent respiration in the muscle and kidney was unaffected. CONCLUSIONS: Endotoxemia reduces the efficiency of hepatic but neither skeletal muscle nor kidney mitochondrial respiration, independent of regional and microcirculatory blood flow changes.

Canine microglial cells: stereotypy in immunophenotype and specificity in function?

Microglial cells represent the endogenous immune system of the central nervous system (CNS). Upon pathological insults they reveal their immunological potential aimed at regaining homeostasis. These reactions have long been believed to follow a uniform and unspecific pattern which is irrespective to the underlying disease entity. Evidence is growing that this view seriously underrates microglial competence as the defenders of the CNS. In the present study, microglial cells of 47 dogs were examined ex vivo by means of flow cytometry. Ex vivo examination included immunophenotypic characterization using eight different surface markers and functional studies such as phagocytosis assay and the reactive oxygen species (ROS) generation test. The dogs were classified according to their histopathological diagnoses in disease categories (controls, canine distemper virus (CDV) induced demyelination, other diseases of the CNS) and results of microglial reaction profiles were compared. Immunophenotypic characterization generally revealed relative high conformity in the microglial disease response among the different groups, however the functional response was shown to be more specific. Dogs with intracranial inflammation and dogs with demyelination showed an enhanced phagocytosis, whereas a significant up-regulation of ROS generation was found in dogs with demyelination due to CDV infection. This strongly suggests a specific response of microglia to infection with CDV in the settings of our study and underlines the pivotal role of microglial ROS generation in the pathogenesis of demyelinating diseases, such as canine distemper.

Coronary collateral function long after drug-eluting stent implantation

OBJECTIVES: This study was designed to compare coronary collateral function in patients after bare-metal stent (BMS) or drug-eluting stent (DES) implantation. BACKGROUND: Drug-eluting stents have an inhibitory effect on the production of cytokines, chemotactic proteins, and growth factors, and may therefore negatively affect coronary collateral growth. METHODS: A total of 120 patients with long-term stable coronary artery disease (CAD) after stent implantation were included. Both the BMS group and the DES group comprised 60 patients matched for in-stent stenosis severity of the vessel undergoing collateral flow index (CFI) measurement at follow-up and for the duration of follow-up. The primary end point of the investigation was invasively determined coronary collateral function 6 months after stent implantation. Collateral function was assessed by simultaneous aortic, coronary wedge, and central venous pressure measurements (yielding CFI) and by intracoronary electrocardiogram during balloon occlusion. RESULTS: There were no differences between the groups regarding age, gender, body mass index, frequency of cardiovascular risk factors, use of cardiovascular drugs, severity of CAD, or site of coronary artery stenoses. Despite equal in-stent stenosis severity (46 +/- 34% and 45 +/- 36%) and equal follow-up duration (6.2 +/- 10 months and 6.5 +/- 5.4 months), CFI was diminished in the DES versus BMS group (0.154 +/- 0.097 vs. 0.224 +/- 0.142; p = 0.0049), and the rate of collaterals insufficient to prevent ischemia during occlusion (intracoronary electrocardiographic ST-segment elevation > or =0.1 mV) was higher with 50 of 60 patients in the DES group and 33 of 60 patients in the BMS group (p = 0.001). CONCLUSIONS: Collateral function long after coronary stenting is impaired with DES (sirolimus and paclitaxel) when compared with BMS. Considering the protective nature of collateral vessels, this could lead to more serious cardiac events in the presence of an abrupt coronary occlusion.

Lateralized and frequency-dependent effects of prefrontal rTMS on regional cerebral blood flow

Repetitive transcranial magnetic stimulation (rTMS) is a means to study the function and connectivity of brain areas. The present study addressed the question of hemispheric asymmetry of frontal regions and aimed to further understand the acute effects of high- and low-frequency rTMS on regional cerebral blood flow (rCBF). Sixteen healthy right-handed men were imaged using H(2)(15)O positron emission tomography (PET) immediately after stimulation. High (10 Hz)- and low (1 Hz)-frequency suprathreshold short-duration rTMS was applied over either the left or right dorsolateral prefrontal cortex (DLPFC). Slow and fast rTMS applied over the left DLPFC significantly increased CBF in the stimulated area. Compared to baseline, slow rTMS induced a significant increase in CBF contralateral to the stimulation site, in the right caudate body and in the anterior cingulum. Furthermore, slow rTMS decreased CBF in the orbitofrontal cortex (OFC, ipsilateral to stimulation side). Fast rTMS applied over the right DLPFC was associated with increased activity at the stimulation site, in the bilateral orbitofrontal cortex and in the left medial thalamus compared to 1-Hz rTMS. These results show that rCBF changes induced by prefrontal rTMS differ upon hemisphere stimulated and vary with stimulation frequency. These differential neurophysiological effects of short-train rTMS with respect to side and frequency suggest hemisphere-dependent functional circuits of frontal cortico-subcortical areas.

Data Quality Assessment of Ungated Flow Cytometry Data in High

Background: The recent development of semi-automated techniques for staining and analyzing flow cytometry samples has presented new challenges. Quality control and quality assessment are critical when developing new high throughput technologies and their associated information services. Our experience suggests that significant bottlenecks remain in the development of high throughput flow cytometry methods for data analysis and display. Especially, data quality control and quality assessment are crucial steps in processing and analyzing high throughput flow cytometry data. Methods: We propose a variety of graphical exploratory data analytic tools for exploring ungated flow cytometry data. We have implemented a number of specialized functions and methods in the Bioconductor package rflowcyt. We demonstrate the use of these approaches by investigating two independent sets of high throughput flow cytometry data. Results: We found that graphical representations can reveal substantial non-biological differences in samples. Empirical Cumulative Distribution Function and summary scatterplots were especially useful in the rapid identification of problems not identified by manual review. Conclusions: Graphical exploratory data analytic tools are quick and useful means of assessing data quality. We propose that the described visualizations should be used as quality assessment tools and where possible, be used for quality control.

Pattern of regional cerebral blood-flow changes induced by acute heroin administration--a perfusion MRI study

Although both the subjective and physiological effects of abused psychotropic substances have been characterized, less is known about their effects on brain function. We examined the actions of intravenous diacetylmorphine (heroin), the most widely abused opioid, on regional cerebral blood flow (rCBF), as assessed by perfusion-weighted MR imaging (PWI) in a double-blind and placebo-controlled setting.

Plasma and urinary catecholamines as related to renal function in man

To assess the relationship between renal plasma flow (ERPF) or glomerular filtration rate (GFR) and the levels of norepinephrine (NE) or epinephrine (E) in plasma or urine in the presence of progressive degrees of non-oliguric renal functional impairment, these variables were assessed simultaneously in 18 normal subjects, 72 with parenchymal kidney disease and 14 with essential hypertension. ERPF and GFR were lower (P less than 0.01 to 0.001) in the groups with renal disease (mean +/- SD, 340 +/- 230 and 68 +/- 43 ml/min/1.73 m2, respectively) or essential hypertension (434 +/- 101 and 97 +/- 25 ml/min/1.73 m2) than normal subjects (597 +/- 133 and 118 +/- 14 ml/min/1.73 m2). Plasma and urinary NE and E did not differ significantly among groups and were unrelated with ERPF or GFR (range 4 to 160 ml/min/1.73 m2), except for reduced (P less than 0.001) urinary NE and E excretion in the presence of a GFR less than 20 ml/min. Subgroups with renal disease and a normal (N = 39) or high blood pressure (N = 33) also were comparable in their plasma and urinary NE and E, while ERPF and GFR tended to be lower in hypertensive patients. It is concluded that a chronic reduction in excretory kidney function may have no relevant impact on circulating levels of NE and E per se, although their urinary excretion falls distinctly at the stage of advanced renal failure. These aspects deserve consideration when pathogenetic or diagnostic studies of catecholamines are performed in normotensive or hypertensive patients with impaired kidney function.

Effect of atazanavir versus other protease inhibitor-containing antiretroviral therapy on endothelial function in HIV-infected persons: randomised controlled trial

OBJECTIVE: Impaired endothelial function was demonstrated in HIV-infected persons on protease inhibitor (PI)-containing antiretroviral therapy, probably due to altered lipid metabolism. Atazanavir is a PI causing less atherogenic lipoprotein changes. This study determined whether endothelial function improves after switching from other PI to atazanavir. DESIGN: Randomised, observer-blind, treatment-controlled trial. SETTING: Three university-based outpatient clinics. PATIENTS: 39 HIV-infected persons with suppressed viral replication on PI-containing regimens and fasting low-density lipoprotein (LDL)-cholesterol greater than 3 mmol/l. INTERVENTION: Patients were randomly assigned to continue the current PI or change to unboosted atazanavir. MAIN OUTCOME MEASURES: Endpoints at week 24 were endothelial function assessed by flow-mediated dilation (FMD) of the brachial artery, lipid profiles and serum inflammation and oxidative stress parameters. RESULTS: Baseline characteristics and mean FMD values of the two treatment groups were comparable (3.9% (SD 1.8) on atazanavir versus 4.0% (SD 1.5) in controls). After 24 weeks' treatment, FMD decreased to 3.3% (SD 1.4) and 3.4% (SD 1.7), respectively (all p = ns). Total cholesterol improved in both groups (p<0.0001 and p = 0.01, respectively) but changes were more pronounced on atazanavir (p = 0.05, changes between groups). High-density lipoprotein and triglyceride levels improved on atazanavir (p = 0.03 and p = 0.003, respectively) but not in controls. Serum inflammatory and oxidative stress parameters did not change; oxidised LDL improved significantly in the atazanavir group. CONCLUSIONS: The switch from another PI to atazanavir in treatment-experienced patients did not result in improvement of endothelial function despite significantly improved serum lipids. Atherogenic lipid profiles and direct effects of antiretroviral drugs on the endothelium may affect vascular function. Trial registration number: NCT00447070.

Impaired endothelial progenitor cell function predicts age-dependent carotid intimal thickening

OBJECTIVES: We investigated whether qualitative or quantitative alterations of the endothelial progenitor cell (EPC) pool predict age-related structural vessel wall changes. BACKGROUND: We have previously shown that age-related endothelial dysfunction is accompanied by qualitative rather than quantitative changes of EPCs. Animal studies suggest that impaired EPC functions lead to accelerated arterial intimal thickening. METHODS: Intima-media thickness (IMT) was measured in the common carotid artery in our previously published groups of younger (25 +/- 1 years, n = 20) and older (61 +/- 2 years, n = 20) healthy non-smoking volunteers without arterial hypertension, hypercholesterolemia, and diabetes mellitus. Endothelial progenitor cells (EPCs, KDR(+)/CD34(+) and KDR(+)/CD133(+)) were counted in peripheral blood using flow cytometry. In ex vivo expanded EPCs, the function was determined as chemotaxis to VEGF, proliferation, and survival. RESULTS: We observed thicker IMT in older as compared to younger subjects (0.68 +/- 0.03 mm Vs. 0.48 +/- 0.02 mm, P < 0.001). Importantly, there were significant inverse univariate correlations between IMT, EPC chemotaxis, and survival (r = -0.466 P < 0.05; r = -0.463, P < 0.01). No correlation was observed with numbers of circulating EPCs. Multivariate regression analysis revealed that age, mean arterial pressure and migration of EPCs were independent predictors of IMT (R (2 )= 0.58). CONCLUSION: Impaired EPC function may lead to accelerated vascular remodeling due to chronic impairment of endothelial maintenance.

Non-invasive gene-expression-based detection of well-developed collateral function in individuals with and without coronary artery disease

BACKGROUND: In patients with coronary artery disease (CAD), a well grown collateral circulation has been shown to be important. The aim of this prospective study using peripheral blood monocytes was to identify marker genes for an extensively grown coronary collateral circulation. METHODS: Collateral flow index (CFI) was obtained invasively by angioplasty pressure sensor guidewire in 160 individuals (110 patients with CAD, and 50 individuals without CAD). RNA was extracted from monocytes followed by microarray-based gene-expression analysis. 76 selected genes were analysed by real-time polymerase chain reaction (PCR). A receiver operating characteristics analysis based on differential gene expression was then performed to separate individuals with poor (CFI<0.21) and well-developed collaterals (CFI>or=0.21) Thereafter, the influence of the chemokine MCP-1 on the expression of six selected genes was tested by PCR. RESULTS: The expression of 203 genes significantly correlated with CFI (p = 0.000002-0.00267) in patients with CAD and 56 genes in individuals without CAD (p = 00079-0.0430). Biological pathway analysis revealed 76 of those genes belonging to four different pathways: angiogenesis, integrin-, platelet-derived growth factor-, and transforming growth factor beta-signalling. Three genes in each subgroup differentiated with high specificity among individuals with low and high CFI (>or=0.21). Two out of these genes showed pronounced differential expression between the two groups after cell stimulation with MCP-1. CONCLUSIONS: Genetic factors play a role in the formation and the preformation of the coronary collateral circulation. Gene expression analysis in peripheral blood monocytes can be used for non-invasive differentiation between individuals with poorly and with well grown collaterals. MCP-1 can influence the arteriogenic potential of monocytes.

Fluctuation analysis of lung function as a predictor of long-term response to beta2-agonists

The response to beta(2)-agonists differs between asthmatics and has been linked to subsequent adverse events, even death. Possible determinants include beta(2)-adrenoceptor genotype at position 16, lung function and airway hyperresponsiveness. Fluctuation analysis provides a simple parameter alpha measuring the complex correlation properties of day-to-day peak expiratory flow. The present study investigated whether alpha predicts clinical response to beta(2)-agonist treatment, taking into account other conventional predictors. Analysis was performed on previously published twice-daily peak expiratory flow measurements in 66 asthmatic adults over three 6-month randomised order treatment periods: placebo, salbutamol and salmeterol. Multiple linear regression was used to determine the association between alpha during the placebo period and response to treatment (change in the number of days with symptoms), taking into account other predictors namely beta(2)-adrenoceptor genotype, lung function and its variability, and airway hyperresponsiveness. The current authors found that alpha measured during the placebo period considerably improved the prediction of response to salmeterol treatment, taking into account genotype, lung function or its variability, or airway hyperresponsiveness. The present study provides further evidence that response to beta(2)-agonists is related to the time correlation properties of lung function in asthma. The current authors conclude that fluctuation analysis of lung function offers a novel predictor to identify patients who may respond well or poorly to treatment.

Relative impact of respiratory muscle activity on tidal flow and end expiratory volume in healthy neonates

INTRODUCTION: It has been suggested that infants dynamically regulate their tidal flow and end-expiratory volume level. The interaction between muscle activity, flow and lung volume in spontaneously sleeping neonates is poorly studied, since it requires the assessment of transcutaneous electromyography of respiratory muscles (rEMG) in matched comparison to lung function measurements. METHODS: After determining feasibility and repeatability of rEMG in 20 spontaneously sleeping healthy neonates, we measured the relative impact of intercostal and diaphragmatic EMG activity in direct comparison to the resulting tidal flow and FRC. RESULTS: We found good feasibility, repeatability and correlation of timing indices between rEMG activity and flow. The rEMG amplitude was significantly dependent on the resistive load of the face mask. Diaphragm and intercostal muscle activity commenced prior to the onset of flow and remained active during the expiratory cycle. The relative contribution of intercostal and diaphragmatic activity to flow was variable and changed dynamically. CONCLUSION: Using matched rEMG, air flow and lung volume measurements, we have found good feasibility and repeatability of intercostal and diaphragm rEMG measurements and provide the first quantitative measures of the temporal relationship between muscle activity and flow in spontaneously sleeping healthy neonates. Lung mechanical function is dynamically regulated and adapts on a breath to breath basis. So, non-invasive rEMG measurements alone or in combination with lung function might provide a more comprehensive picture of pulmonary mechanics in future studies. The data describing the timing of EMG and flow may be important for future studies of EMG triggered mechanical ventilation.

IMPROVING FLOW DISTRIBUTION IN SMALL-SCALE WATER-SUPPLY SYSTEMS THROUGH THE USE OF FLOW-REDUCING DISCS AND METHODS FOR ANALYZING THE EFFECTIVENESS OF SOLAR POWERED PUMPING FOR A DRINKING WATER SUPPLY IN RURAL PANAMA

As continued global funding and coordination are allocated toward the improvement of access to safe sources of drinking water, alternative solutions may be necessary to expand implementation to remote communities. This report evaluates two technologies used in a small water distribution system in a mountainous region of Panama; solar powered pumping and flow-reducing discs. The two parts of the system function independently, but were both chosen for their ability to mitigate unique issues in the community. The design program NeatWork and flow-reducing discs were evaluated because they are tools taught to Peace Corps Volunteers in Panama. Even when ample water is available, mountainous terrains affect the pressure available throughout a water distribution system. Since the static head in the system only varies with the height of water in the tank, frictional losses from pipes and fittings must be exploited to balance out the inequalities caused by the uneven terrain. Reducing the maximum allowable flow to connections through the installation of flow-reducing discs can help to retain enough residual pressure in the main distribution lines to provide reliable service to all connections. NeatWork was calibrated to measured flow rates by changing the orifice coefficient (θ), resulting in a value of 0.68, which is 10-15% higher than typical values for manufactured flow-reducing discs. NeatWork was used to model various system configurations to determine if a single-sized flow-reducing disc could provide equitable flow rates throughout an entire system. There is a strong correlation between the optimum single-sized flow- reducing disc and the average elevation change throughout a water distribution system; the larger the elevation change across the system, the smaller the recommended uniform orifice size. Renewable energy can jump the infrastructure gap and provide basic services at a fraction of the cost and time required to install transmission lines. Methods for the assessment of solar powered pumping systems as a means for rural water supply are presented and assessed. It was determined that manufacturer provided product specifications can be used to appropriately design a solar pumping system, but care must be taken to ensure that sufficient water can be provided to the system despite variations in solar intensity.

C-Port Flex-A-assisted automated anastomosis for high-flow extracranial-intracranial bypass surgery in patients with symptomatic carotid artery occlusion: a feasibility study. Clinical article

OBJECT: Preliminary experience with the C-Port Flex-A Anastomosis System (Cardica, Inc.) to enable rapid automated anastomosis has been reported in coronary artery bypass surgery. The goal of the current study was to define the feasibility and safety of this method for high-flow extracranial-intracranial (EC-IC) bypass surgery in a clinical series. METHODS: In a prospective study design, patients with symptomatic carotid artery (CA) occlusion were selected for C-Port-assisted high-flow EC-IC bypass surgery if they met the following criteria: 1) transient or moderate permanent symptoms of focal ischemia; 2) CA occlusion; 3) hemodynamic instability; and 4) had provided informed consent. Bypasses were done using a radial artery graft that was proximally anastomosed to the superficial temporal artery trunk, the cervical external, or common CA. All distal cerebral anastomoses were performed on M2 branches using the C-Port Flex-A system. RESULTS: Within 6 months, 10 patients were enrolled in the study. The distal automated anastomosis could be accomplished in all patients; the median temporary occlusion time was 16.6+/-3.4 minutes. Intraoperative digital subtraction angiography (DSA) confirmed good bypass function in 9 patients, and in 1 the anastomosis was classified as fair. There was 1 major perioperative complication that consisted of the creation of a pseudoaneurysm due to a hardware problem. In all but 1 case the bypass was shown to be patent on DSA after 7 days; furthermore, in 1 patient a late occlusion developed due to vasospasm after a sylvian hemorrhage. One-week follow-up DSA revealed transient asymptomatic extracranial spasm of the donor artery and the radial artery graft in 1 case. Two patients developed a limited zone of infarction on CT scanning during the follow-up course. CONCLUSIONS: In patients with symptomatic CA occlusion, C-Port Flex-A-assisted high-flow EC-IC bypass surgery is a technically feasible procedure. The system needs further modification to achieve a faster and safer anastomosis to enable a conclusive comparison with standard and laser-assisted methods for high-flow bypass surgery.

Assessment of splanchnic blood flow using magnetic resonance imaging

BACKGROUND AND AIMS: The splanchnic circulation has an important function in the body under both physiological and pathophysiological conditions. Despite its importance, no reliable noninvasive procedures for estimating splanchnic circulation have been established. The aim of this study was to evaluate MRI as a tool for assessing intra-abdominal blood flows of the aorta, portal vein (VPO) and the major intestinal and hepatic vessels. METHODS: In nine healthy volunteers, the proximal aorta (AOP) and distal abdominal aorta (AOD), superior mesenteric artery (SAM), celiac trunk (CTR), hepatic arteries (common and proper hepatic arteries, AHC and AHP, respectively), and VPO were localized on contrast-enhanced magnetic resonance angiography images. Volumetric flow was measured using a two-dimensional cine echocardiogram-gated phase contrast technique. Measurements were taken before and 30 min after continuous intravenous infusion of somatostatin (250 microg/h) and were independently evaluated by two investigators. RESULTS: Blood flow measured by MRI in the VPO, SAM, AOP, AHP, and CTR significantly decreased after drug infusion. Flows in the AOD and AHC showed a tendency to decrease (P>0.05). Interrater agreement on flows in MRI was very good for large vessels (VPO, AOP, and AOD), with a concordance correlation coefficient of 0.94, as well as for smaller vessels such as the CTR, AHC, AHP, and SAM (concordance correlation coefficient =0.78). CONCLUSION: Somatostatin-induced blood flow changes in the splanchnic region were reliably detected by MRI. MRI may be useful for the noninvasive assessment of blood flow changes in the splanchnic region.