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Acute kidney injury (AKI) is frequently seen in patients with hemorrhagic shock due to hypotension, tissue hypoxia, and inflammation despite adequate resuscitation. There is a lack of information concerning the alteration of renal microcirculation and perfusion during shock and resuscitation. The aim of this study was to investigate the possible role of renal microcirculatory alterations on development of renal dysfunction in a pig model of non-traumatic hemorrhagic shock (HS) induced AKI.Fully instrumented female pigs were divided into the two groups as Control (n = 6) and HS (n = 11). HS was achieved by withdrawing blood until mean arterial pressure (MAP) reached around 50 mmHg. After an hour cessation period, fluid resuscitation with balanced crystalloid was started for the duration of 1 h. The systemic and renal hemodynamics, renal microcirculatory perfusion (contrast-enhanced ultrasound (CEUS)) and the sublingual microcirculation were measured.CEUS peak enhancement was significantly increased in HS during shock, early-, and late resuscitation indicating perfusion defects in the renal cortex (p < 0.05 vs. baseline, BL) despite a stable renal blood flow (RBF) and urine output. Following normalization of systemic hemodynamics, we observed persistent hypoxia (high lactate) and high red blood cell (RBC) velocity just after initiation of resuscitation resulting in further endothelial and renal damage as shown by increased plasma sialic acid (p < 0.05 vs. BL) and NGAL levels. We also showed that total vessel density (TVD) and functional capillary density (FCD) were depleted during resuscitation (p < 0.05).In this study, we showed that the correction of systemic hemodynamic variables may not be accompanied with the improvement of renal cortical perfusion, intra-renal blood volume and renal damage following fluid resuscitation. We suggest that the measurement of renal injury biomarkers, systemic and renal microcirculation can be used for guiding to the optimization of fluid therapies., (© 2023. The Author(s).)

Although high-frequency ultrasound imaging is gaining attention in various applications, hardly any ultrasound contrast agents (UCAs) dedicated to such frequencies (>15 MHz) are available for contrast-enhanced ultrasound (CEUS) imaging. Moreover, the composition of the limited commercially available UCAs for high-frequency CEUS (hfCEUS) is largely unknown, while shell properties have been shown to be an important factor for their performance. The aim of our study was to produce UCAs in-house for hfCEUS. Twelve different UCA formulations A-L were made by either sonication or mechanical agitation. The gas core consisted of C 4 F 10 and the main coating lipid was either 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC; A-F formulation) or 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC; G-L formulation). Mechanical agitation resulted in UCAs with smaller microbubbles (number weighted mean diameter ~1 [Formula: see text]) than sonication (number weighted mean diameter ~2 [Formula: see text]). UCA formulations with similar size distributions but different main lipid components showed that the DPPC-based UCA formulations had higher nonlinear responses at both the fundamental and subharmonic frequencies in vitro for hfCEUS using the Vevo2100 high-frequency preclinical scanner (FUJIFILM VisualSonics, Inc.). In addition, UCA formulations F (DSPC-based) and L (DPPC-based) that were made by mechanical agitation performed similar in vitro to the commercially available Target-Ready MicroMarker (FUJIFILM VisualSonics, Inc.). UCA formulation F also performed similar to Target-Ready MicroMarker in vivo in pigs with similar mean contrast intensity within the kidney ( n = 7 ), but formulation L did not. This is likely due to the lower stability of formulation L in vivo. Our study shows that DSPC-based microbubbles produced by mechanical agitation resulted in small microbubbles with high nonlinear responses suitable for hfCEUS imaging.

Oxygen delivery and metabolism represent key factors for organ function in health and disease. We describe the optical key characteristics of a technique to comprehensively measure oxygen tension (PO(2)) in myocardium, using oxygen-dependent quenching of phosphorescence and delayed fluorescence of porphyrins, by means of Monte Carlo simulations and ex vivo experiments. Oxyphor G2 (microvascular PO(2)) was excited at 442 nm and 632 nm and protoporphyrin IX (mitochondrial PO(2)) at 510 nm. This resulted in catchment depths of 161 (86) µm, 350 (307) µm and 262 (255) µm respectively, as estimated by Monte Carlo simulations and ex vivo experiments (brackets). The feasibility to detect changes in oxygenation within separate anatomical compartments is demonstrated in rat heart in vivo. Schematic of ex vivo measurements., (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim.)

Objective: The objective of this paper was to determine the effect of neuromuscular blockade (NMB) on working space in a porcine laparoscopy model., Background: Conflicting results on the effect of NMB on laparoscopic working space are found in literature. Almost all studies are limited by absence of objective assessment of working space or use surrogate outcomes., Methods: In a standardized porcine laparoscopy model, laparoscopic working-space dimensions with and without NMB were investigated in 16 animals using computed tomography at intra-abdominal pressures of 0, 5, 10, and 15 mmHg during multiple runs of abdominal insufflation., Results: No statistically significant effect of NMB on abdominal dimensions and laparoscopic working-space volume was found during CO2 pneumoperitoneum. In contrast, the effect of pre-stretching of the abdominal wall by a previous abdominal insufflation was found to be significant., Conclusions: This experimental study confirms the results from several clinical studies that NMB does not influence laparoscopic working space. Studies dealing with working space during laparoscopy should take note of pre-stretching bias.

Background: The leading cause of mortality due to pulmonary arterial hypertension (PAH) is failure of the cardiac right ventricle. It has long been hypothesized that during the development of chronic cardiac failure the heart becomes energy deprived, possibly due to shortage of oxygen at the level of cardiomyocyte mitochondria. However, direct evaluation of oxygen tension levels within the in vivo right ventricle during PAH is currently lacking. Here we directly evaluated this hypothesis by using a recently reported technique of oxygen-dependent quenching of delayed fluorescence of mitochondrial protoprophyrin IX, to determine the distribution of mitochondrial oxygen tension (mitoPO2) within the right ventricle (RV) subjected to progressive PAH., Methods: PAH was induced through a single injection of monocrotaline (MCT). Control (saline-injected), compensated RV hypertrophy (30 mg/kg MCT; MCT30), and RV failure (60 mg/kg MCT; MCT60) rats were compared 4 wk after treatment. The distribution of mitoPO2 within the RV was determined in mechanically-ventilated, anaesthetized animals, applying different inspired oxygen (FiO2) levels and two increment dosages of dobutamine., Results: MCT60 resulted in RV failure (increased mortality, weight loss, increased lung weight), MCT30 resulted in compensated RV hypertrophy. At 30% or 40% FiO2, necessary to obtain physiological arterial PO2 in the diseased animals, RV failure rats had significantly less mitochondria (15% of total mitochondria) in the 0-20 mmHg mitoPO2 range than hypertrophied RV rats (48%) or control rats (54%). Only when oxygen supply was reduced to 21% FiO2, resulting in low arterial PO2 for the MCT60 animals, or when oxygen demand increased with high dose dobutamine, the number of failing RV mitochondria with low oxygen became similar to control RV. In addition, metabolic enzyme analysis revealed similar mitochondrial mass, increased glycolytic hexokinase activity following MCT, with increased lactate dehydrogenase activity only in compensated hypertrophied RV., Conclusions: Our novel observation of increased mitochondrial oxygenation suggests down-regulation of in vivo mitochondrial oxygen consumption, in the absence of hypoxia, with transition towards right ventricular failure induced by pulmonary arterial hypertension.

Aims: Hemoglobin-based oxygen carriers (HBOC) provide a potential alternative to red blood cell (RBC) transfusion. Their clinical application has been limited by adverse effects, in large part thought to be mediated by the intravascular scavenging of the vasodilator nitric oxide (NO) by cell-free plasma oxy-hemoglobin. Free hemoglobin may also cause endothelial dysfunction and platelet activation in hemolytic diseases and after transfusion of aged stored RBCs. The new soluble guanylate cyclase (sGC) stimulator Bay 41-8543 and sGC activator Bay 60-2770 directly modulate sGC, independent of NO bioavailability, providing a potential therapeutic mechanism to bypass hemoglobin-mediated NO inactivation., Results: Infusions of human hemoglobin solutions and the HBOC Oxyglobin into rats produced a severe hypertensive response, even at low plasma heme concentrations approaching 10 μM. These reactions were only observed for ferrous oxy-hemoglobin and not analogs that do not rapidly scavenge NO. Infusions of L-NG-Nitroarginine methyl ester (L-NAME), a competitive NO synthase inhibitor, after hemoglobin infusion did not produce additive vasoconstriction, suggesting that vasoconstriction is related to scavenging of vascular NO. Open-chest hemodynamic studies confirmed that hypertension occurred secondary to direct effects on increasing vascular resistance, with limited negative cardiac inotropic effects. Intravascular hemoglobin reduced the vasodilatory potency of sodium nitroprusside (SNP) and sildenafil, but had no effect on vasodilatation by direct NO-independent activation of sGC by BAY 41-8543 and BAY 60-2770., Innovation and Conclusion: These data suggest that both sGC stimulators and sGC activators could be used to restore cyclic guanosine monophosphate-dependent vasodilation in conditions where cell-free plasma hemoglobin is sufficient to inhibit endogenous NO signaling.

Acute respiratory distress syndrome (ARDS) is a devastating clinical syndrome. Angiotensin-converting enzyme (ACE) and its effector peptide angiotensin (Ang) II have been implicated in the pathogenesis of ARDS. A counter-regulatory enzyme of ACE, ie ACE2 that degrades Ang II to Ang-(1-7), offers a promising novel treatment modality for this syndrome. As the involvement of ACE and ACE2 in ARDS is still unclear, this study investigated the role of these two enzymes in an animal model of ARDS. ARDS was induced in rats by intratracheal administration of LPS followed by mechanical ventilation. During ventilation, animals were treated with saline (placebo), losartan (Ang II receptor antagonist), or with a protease-resistant, cyclic form of Ang-(1-7) [cAng-(1-7)]. In bronchoalveolar lavage fluid (BALF) of ventilated LPS-exposed animals, ACE activity was enhanced, whereas ACE2 activity was reduced. This was matched by enhanced BALF levels of Ang II and reduced levels of Ang-(1-7). Therapeutic intervention with cAng-(1-7) attenuated the inflammatory mediator response, markedly decreased lung injury scores, and improved lung function, as evidenced by increased oxygenation. These data indicate that ARDS develops, in part, due to reduced pulmonary levels of Ang-(1-7) and that repletion of this peptide halts the development of ARDS., (Copyright © 2011 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.)

Angiotensin-converting enzyme (ACE) mediates the ventilator-induced inflammatory response in healthy lungs via angiotensin II (Ang II). A rat model was used to examine the role of ACE and Ang II in the inflammatory response during mechanical ventilation of preinjured (ie, lipopolysaccharide [LPS]-exposed) lungs. When indicated, rats were pretreated with the ACE inhibitor captopril and/or intratracheal administration of LPS. The animals were ventilated for 4 hours with moderate pressure amplitudes. Nonventilated animals served as controls. ACE activity and levels of Ang II and inflammatory mediators (interleukin-6, Cytokine-induced Neutrophil Chemoattractant (CINC)-3, interleukin-1beta, and interleukin-10) were determined in bronchoalveolar lavage fluid (BALF). The localization of ACE and Ang II type 1 receptor in lung tissue was determined by immunohistochemistry. The role of the Ang II pathway was assessed by using its receptor antagonist Losartan. Mechanical ventilation of LPS-exposed animals increased ACE activity and levels of inflammatory mediators in BALF compared with ventilated nonexposed and LPS-exposed nonventilated animals. Blocking ACE by captopril attenuated the lung inflammatory response. Furthermore, increased ACE activity in BALF was accompanied by increased levels of Ang II and enhanced expression of its receptor on alveolar cells. Blocking the Ang II receptor attenuated the inflammatory mediator response to a larger extent than by blocking ACE. In conclusion, during mechanical ventilation ACE, via Ang II, mediates the inflammatory response of both healthy and preinjured lungs.

Introduction: Results from clinical studies have provided evidence for the importance of leukocyte-endothelial interactions in the pathogenesis of pulmonary diseases such as acute lung injury (ALI) and acute respiratory distress syndrome (ARDS), as well as in systemic events like sepsis and multiple organ failure (MOF). The present study was designed to investigate whether alveolar stretch due to mechanical ventilation (MV) may evoke endothelial activation and inflammation in healthy mice, not only in the lung but also in organs distal to the lung., Methods: Healthy male C3H/HeN mice were anesthetized, tracheotomized and mechanically ventilated for either 1, 2 or 4 hours. To study the effects of alveolar stretch in vivo, we applied a MV strategy that causes overstretch of pulmonary tissue i.e. 20 cmH2O peak inspiratory pressure (PIP) and 0 cmH2O positive end expiratory pressure (PEEP). Non-ventilated, sham-operated animals served as a reference group (non-ventilated controls, NVC)., Results: Alveolar stretch imposed by MV did not only induce de novo synthesis of adhesion molecules in the lung but also in organs distal to the lung, like liver and kidney. No activation was observed in the brain. In addition, we demonstrated elevated cytokine and chemokine expression in pulmonary, hepatic and renal tissue after MV which was accompanied by enhanced recruitment of granulocytes to these organs., Conclusions: Our data implicate that MV causes endothelial activation and inflammation in mice without pre-existing pulmonary injury, both in the lung and distal organs.

Myocardial blood flow and oxygen consumption are heterogeneously distributed. Perfusion and myocardial oxygen consumption are closely correlated in the normal heart. It is unknown how this metabolism-perfusion relation is influenced by sympathetic denervation. We investigated this question in seven chloralose-anaesthetized dogs, 3-4 weeks after regional sympathetic denervation of the left circumflex coronary artery area of supply of the left ventricle. Measurements were made of local myocardial blood flow (MBF, in ml min(-1) (g dry wt)(-1)), measured with microspheres, and myocardial oxygen consumption ( , in mumol min(-1) (g dry wt)(-1)) in the same location, calculated from the (13)C spectrum of tissue extracts after intracoronary infusion of 3-(13)C-lactate. Since both innervated and denervated regions are subject to the same arterial pressure, lower blood flow indicates higher resistance. Mean MBF was 5.56 ml min(-1) (g dry wt)(-1) (heterogeneity of 3.47 ml min(-1) (g dry wt)(-1)) innervated, 7.48 ml min(-1) (g dry wt)(-1) (heterogeneity of 3.62 ml min(-1) (g dry wt)(-1)) denervated (n.s.). Significant linear relations were found between MBF and M Vo2 of individual samples within the innervated and denervated regions. The slopes of these relations were not significantly different, but the adjusted mean was significantly higher in the denervated regions (+1.92 ml min(-1) (g dry wt)(-1), an increase of 38% of the mean MBF at the pooled mean M Vo2, P = 0.028, ANCOVA). The ratio MBF/M Vo2(in ml micromol(-1)) was significantly higher, being 0.296 +/- 0.167 ml micromol(-1) in the denervated region compared with the innervated region, 0.216 +/- 0.126 ml micromol(-1), P = 0.0182, Mann-Whitney U test. These results indicate that sympathetic tone under chloralose anaesthesia imposes a moderate vasoconstrictive effect in the myocardium that is not detected by comparison of the mean blood flow or resistance.

The FHH (fawn-hooded hypertensive) rat is a model of hypertension-associated chronic kidney damage. Five interacting quantitative trait loci (QTLs), named Rf-1-Rf-5, determine the high renal susceptibility. The aim of the present study was to investigate a possible interaction between Rf-1 and Rf-3. Differences in renal susceptibility between ACI (August x Copenhagen Irish) controls, Rf-1A and Rf-3 single congenics, and Rf-1A+3 double congenic rats were assessed using four different treatments: two-kidney control (2K), 2K plus N(omega)-nitro-L-arginine methyl ester (L-NAME)-induced hypertension (2K+L-NAME), unilateral nephrectomy (UNX), and UNX plus L-NAME-induced hypertension (UNX+L-NAME). Proteinuria (UPV) and systolic blood pressure (SBP) were assessed after 6, 12, and 18 weeks, while the incidence of glomerulosclerosis (%FGS) was determined at the end of the experiment. In a separate experiment, renal autoregulation was assessed in 13-15-week old 2K rats of all four strains. Compared to ACI rats, small increases in renal susceptibility were found in Rf-1A and Rf-3 single congenics following 2K+L-NAME, UNX, and UNX+L-NAME treatments. However, in the Rf-1A+3 double congenics, a major increase in renal susceptibility was found with all four treatments. Both Rf-1A and Rf-1A+3 congenic rats had an impaired renal autoregulation. In contrast, the Rf-3 had a normal autoregulation, similar to that of the ACI rat. These findings indicate that Rf-1 and Rf-3 alone slightly increase the susceptibility to the development of renal damage. However, a synergistic interaction between these two QTLs markedly enhances renal susceptibility. In contrast to the Rf-1 region, the Rf-3 region does not carry genes influencing renal autoregulation.

Background: Previous studies showed that combining the Rf-1 and Rf-3 or Rf-4 QTLs of FHH induced synergistic interactions markedly enhancing renal susceptibility. The present study aimed to determine the presence of such interaction between the Rf-1 and Rf-5 QTLs., Methods: Renal damage susceptibility was assessed in Rf-1B, Rf-1B+5, Rf-1B+4 congenics and ACI control rats in four situations: two-kidney control (2K), unilateral nephrectomy (UNX), L-NAME-induced hypertension (2K+L-NAME) and UNX+L-NAME. Albuminuria (UAV) and systolic blood pressure (SBP) were measured during 18 weeks of follow-up. In separate experiments, renal autoregulation was assessed in 2K rats., Results: In all four situations, Rf-1B+4 rats developed more severe UAV than ACI, Rf-1B and Rf-1B+5. There were no significant differences in UAV between Rf-1B and Rf-1B+5 rats. In the 2K and UNX situation no differences in SBP were noted between all four strains. With 2K+L-NAME and UNX+L-NAME treatment, SBP in double congenics was higher than that of ACI and Rf-1B rats. Renal autoregulation was similarly impaired in all three congenic strains., Conclusion: We conclude that the Rf-5 region, alone or in the presence of Rf-1B, does not affect the development of renal damage. We cannot substantiate that the Rf-5 region contains genes influencing renal damage susceptibility., (Copyright 2006 S. Karger AG, Basel.)

Background: Five quantitative trait loci (QTLs), Rf-1 to Rf-5, were found in Fawn-Hooded hypertensive (FHH) rats influencing susceptibility to renal damage. Previously, we found that single transfer of the Rf-1 QTL from FHH rats onto the renal-resistant August x Copenhagen Irish (ACI) strain caused a small increase in renal susceptibility. To investigate the separate role of the Rf-4 QTL and its interaction with Rf-1, we generated a single congenic strain carrying Rf-4 and a double congenic carrying both Rf-1 and Rf-4., Methods: Differences in renal susceptibility between ACI, Rf-1A, and Rf-4 single congenics and Rf-1A+4 double congenics were assessed using four different treatments: control (two-kidney), two-kidney with l-arginine analogue N-nitro-l-arginine methyl ester (L-NAME)-induced hypertension, unilateral nephrectomy, and unilateral nephrectomy + L-NAME. In separate experiments, renal blood flow (RBF) autoregulation was compared between two-kidney ACI and congenic rats., Results: Compared to ACI, Rf-1A rats developed more renal damage, while Rf-4 rats did not. The most severe renal damage was found in the Rf-1A+4 double congenic rats. Analysis of variance (ANOVA) demonstrated a significant interaction between the Rf-1A and Rf-4 QTLs. The magnitude of the interaction varied with the type and duration of the treatment. The RBF autoregulation was impaired in Rf-1A single and Rf-1A+4 double congenics, while in Rf-4 single congenics it was similar to that of ACI controls., Conclusion: These findings indicate that the Rf-1 QTL directly influences renal susceptibility and autoregulation. In contrast, the Rf-4 QTL shows no direct effects, but significantly increases susceptibility to renal damage via an interaction with Rf-1.

Background: Linkage analyses of crosses of rats susceptible to renal damage, fawn-hooded hypertensive (FHH), and those resistant to kidney damage, August x Copenhagen Irish (ACI), indicated that five quantitative trait loci (QTLs), Rf-1 to Rf-5, influence proteinuria (UPV), albuminuria (UAV) and focal glomerulosclerosis (FGS). Here we present data obtained in congenic rats to directly assess the role of the Rf-1 and Rf-5 QTLs., Methods: Renal damage (UPV, UAV, and FGS) was assessed in ACI, ACI.FHH-(D1Rat324-D1Rat156)(Rf-1B), and ACI.FHH-(D17Rat117-D17Arb5)(D17Rat180-D17Rat51) (Rf-5) congenic rats in the two-kidney (2K) control situation, and following L-NAME-induced hypertension, unilateral nephrectomy (UNX), and UNX combined with L-NAME. In addition we investigated renal blood flow (RBF) autoregulation in 2K congenic and parental ACI and FHH rats., Results: Compared to ACI, Rf-1B congenic rats showed a significant increase in susceptibility to renal damage after all three treatments. The increase was most pronounced after UNX with L-NAME. In contrast, the degree of renal damage in Rf-5 congenic rats was not different from the ACI. Like FHH, Rf-1B rats had impaired renal autoregulation. In contrast, RBF autoregulation of Rf-5 rats does not differ from ACI., Conclusion: The Rf-5 QTL does not show any direct effect. The Rf-1 QTL carries one or more genes impairing renal autoregulation and influencing renal damage susceptibility. Whether these are the same genes remains to be established., (Copyright 2005 S. Karger AG, Basel.)

DNA was isolated from 19 strains and substrains of Streptococcus sanguis and analysed for guanine plus cytosine (GC) contents and base sequence homologies. Three groups could be discerned: group 1 strains had 40-8 to 42-8 mol % GC; group 2, 42-7 to 44-0 mol % GC; group 3, 43-8 to 46-4 mol % GC. DNA homologies between groups 1 and 3 were 40 to 60% at 67 degrees C and 40% at 72 degrees C. The homologies of group 2 towards groups 1 and 3 were much lower. Strains in groups 1 and 3 hydrolysed arginine and aesculin and fermented inulin; group 2 strains did not. Groups 1 and 3 could be considered subspecies of S. sanguis. Group 2 should not be considered S. sanguis.

Streptococcus mutans, an organism implicated in dental caries and not previously found outside of man and certain laboratory animals, was isolated from the mouths of wild rats which ate sugar cane. The strains isolated fermented mannitol and sorbitol, and failed to grow in 6.5% NaCl or at 45 C. They formed in vitro plaques on nichrome wires when grown in sucrose broth. They also stored intracellular polysaccharide which could be catabolized by washed, resting cells. Deoxyribonucleic acid-deoxyribonucleic acid reassociations revealed two genetic types. One type shared extensive deoxyribonucleic acid base sequences with S. mutans strains HS6 and OMZ61, two members of a genetic type found in man and laboratory hamsters. The other type seemed unrelated to any S. mutans genetic type previously encountered. It is concluded that the ecological triad of tooth-sucrose-S. mutans is not a phenomenon unique to man and experimental animals.