Shock : molecular, cellular, and systemic pathobiological aspects and therapeutic approaches : the official journal the Shock Society, the European Shock Society, the Brazilian Shock Society, the International Federation of Shock Societies
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Macrophage-derived factors, including TNF-α, are known as important inducers of insulin resistance. However, the role of macrophages in insulin resistance in the liver is unclear. Hyperglycemia and insulin resistance commonly occur following acute injuries or critical illness, referred to as "critical illness diabetes." In the present studies, the roles of macrophages in hepatic insulin resistance following surgical trauma and hemorrhage were investigated. ⋯ In contrast, macrophage depletion significantly reversed the hepatic insulin resistance several hours later, following resuscitation. As a comparison, splenectomy resulted in improvement in hepatic insulin signaling following resuscitation, but to a lesser extent, suggesting that both liver and spleen resident macrophages have a role in the continuation of hepatic insulin resistance following resuscitation. These studies demonstrated that the initial development of insulin resistance in liver is macrophage-independent in a rodent model of critical illness diabetes, whereas both liver and spleen macrophages have a role in the later maintenance of the insulin-resistant state, following resuscitation.
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We hypothesized that fluid administration may increase regional splanchnic perfusion after abdominal surgery-even in the absence of a cardiac stroke volume (SV) increase and independent of accompanying endotoxemia. Sixteen anesthetized pigs underwent abdominal surgery with flow probe fitting around splanchnic vessels and carotid arteries. They were randomized to continuous placebo or endotoxin infusion, and when clinical signs of hypovolemia (mean arterial pressure, <60 mmHg; heart rate, >100 beats · min(-1); urine production, <0.5 mL · kg(-1) · h(-1); arterial lactate concentration, >2 mmol · L(-1)) and/or low pulmonary artery occlusion pressure (target 5-8 mmHg) were present, they received repeated boli of colloids (50 mL) as long as SV increased 10% or greater. ⋯ In control animals, celiac trunk (30% vs. 9%, P = 0.004) and hepatic artery (25% vs. 11%, P = 0.040) flow decreased more often than in endotoxin-infused pigs. Accordingly, blood flow redistribution is a common phenomenon in the postoperative period and is only marginally influenced by endotoxemia. Fluid management based on SV changes may not be useful for improving regional abdominal perfusion.
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Mortality in the intensive care unit frequently results from the synergistic effect of two temporally distinct infections. This study examined the pathophysiology of a new model of intra-abdominal sepsis followed by methicillin-resistant Staphylococcus aureus (MRSA) pneumonia. Mice underwent cecal ligation and puncture (CLP) or sham laparotomy followed 3 days later by an intratracheal injection of MRSA or saline. ⋯ Systemic cytokines were upregulated in both CLP/saline and sham/MRSA mice, and this was blunted by the combination of CLP/MRSA. In contrast, no synergistic effect on pneumonia severity, white blood cell count, or lymphocyte apoptosis was identified in CLP/MRSA mice compared with animals with either insult in isolation. These results indicate that a clinically relevant model of CLP followed by MRSA pneumonia causes higher mortality than could have been predicted from studying either infection in isolation, and this was associated with a blunted local (pulmonary and peritoneal) and systemic inflammatory response and decreased ability to clear infection.
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We evaluated the effects of hyperoxia on pulmonary inflammatory changes in sepsis induced by cecal ligation and puncture (CLP) in rats. Seven groups were studied: sham-operated rats breathing air for 20 or 48 h; CLP breathing air for 20 or 48 h; and CLP + 100% oxygen for 20 h, or 70% oxygen for 48 h, or 100% oxygen intermittently (6 h/d) for 48 h. Video microscopy was used to monitor lung macromolecular leak, microvascular flow velocity, and shear rates, and lung morphometry was used for leukocyte infiltration and solid tissue area. ⋯ Inhalation of 70% oxygen (48 h) attenuated expression of adhesion molecules (P < 0.001) but failed to attenuate markers of lung inflammation. In contrast, intermittent 100% oxygen exerted favorable effects on markers of inflammation, attenuated leukocyte expression of L selectin and CD11 (P < 0.01), decreased pulmonary sequestration of leukocytes (P < 0.001), and ameliorated changes in macromolecular leak (P < 0.01) and lung solid tissue area (P < 0.05). Our data support the beneficial effects of safe subtoxic regimens of normobaric hyperoxia on the systemic and pulmonary inflammatory response following CLP.
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The aim of this study was to determine whether mitochondrial nitric oxide (NO) synthase (NOS) is involved in septic shock myocardial depression. The cecal ligation and puncture (CLP) method was used to induce septic shock. There was a significant depression of hemodynamic parameters recorded in the septic shock stage. ⋯ Mitochondrial NOS expression increased significantly in the septic shock stage, and its overexpression was attenuated using 7-NI. There was no significant decrease in the mitochondrial permeability transition pore measurement in the CLP-septic shock group, whereas a significant decrease was observed in those treated with L-NAME or 7-NI. These results indicate that overexpression of mitochondrial NOS is involved in myocardial depression.