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Biomedical subjects

Edwin A Deitch

Publications and source records attributed to Edwin A Deitch.

At least 73 records · Page 4Linked to original sources
PubMed2003

The role of oxidant-mediated pathways in the cytotoxicity of endothelial cells exposed to mesenteric lymph from rats subjected to trauma-hemorrhagic shock.

Because gut-derived factors carried in mesenteric lymph are implicated in multiple organ dysfunction syndrome and have been shown to injure endothelial cells, we investigated several cellular pathways by which this process could occur. To accomplish this, mesenteric lymph (5%, v/v) collected at 1 to 3 h postshock from male rats undergoing trauma (5-cm laparotomy) and hemorrhagic shock (90 min of mean arterial pressure [MAP] of 30 mmHg; T/HS) was tested for endothelial cell cytotoxicity on human umbilical vein endothelial cells (HUVECs). Over 30 pharmacologic agents that had been reported to inhibit endothelial cell death were tested for their ability to prevent T/HS lymph-induced HUVEC cell death. These included agents documented to protect against oxidant-mediated, calcium-mediated, and arachidonic acid pathway-mediated endothelial cell injury and death. These pharmacologic inhibitors were preincubated with HUVECs for 1 h or were added to the HUVECs simultaneously with lymph, and were then incubated for 18 h. Controls were lymph alone, inhibitor alone, or medium alone. Mitochondrial tetrazolium (MTT) and LDH release assays were used to determine cell viability. The inhibitors that significantly protected HUVECs from the cytotoxicity of T/HS lymph (P < 0.001) included the antioxidant combination of vitamins C and E and the antioxidant-lipooxygenase inhibitor nordihydroguaretic acid (NDGA). These agents were equally effective when added simultaneously with lymph or preincubated with the HUVECs, suggesting an extracellular or membrane-bound process. In summary, the inhibitors that provided protection from toxic lymph appear to work at the membrane and are involved in limiting membrane peroxidation. Based on this study, it appears that an oxidant pathway is involved in T/HS lymph-induced endothelial cell injury and death.

Animals↗
PubMed2003

Mesenteric lymph from rats with thermal injury prolongs the action potential and increases Ca2+ transient in rat ventricular myocytes.

Although gut-derived mesenteric lymph from animals with thermal injury appears to lead to myocardial contractile dysfunction, the cellular mechanisms remain unclear. We examined the direct effects of intestinal lymph on excitation-contraction coupling in rat ventricular myocytes. Lymph from rats receiving burn injury (burn lymph), but not from sham-burned rats, rapidly enhanced myocyte contraction and the amplitude of Ca2+ transient; the average percentage of shortening was increased from 5.5 +/- 0.3% to 10.5 +/- 0.9%. 90% and the Ca2+ transients increased by 80% +/- 20%. Burn lymph had no effect on the amplitude of L-type Ca2+ current (ICa) or the inward rectifier K+ current, but the transient outward K+ currents (Ito) were reduced significantly by burn lymph. Inhibition of Ito was not altered by an alpha1-adrenergic receptor (AR) antagonist, prazosin, indicating that the block was not mediated via alpha1-AR signaling pathway. Action potential (AP) duration, measured at 50% and 90% repolarization, was prolonged by burn lymph. Stimulation of myocytes with AP voltage-clamp waveforms derived from prolonged AP induced by burn lymph revealed a 1.7-fold increase in Ca2+ influx via ICa compared with the Ca2+ influx induced by control AP. Blocking of Ito by 4-aminopyridine prolonged AP duration and increased Ca2+ transients, mimicking the effects of burn lymph. Burn lymph did not affect Na+/Ca2+ exchange currents or caffeine-induced SR Ca2+ release. Thus, acute exposure of normal cardiac myocytes to burn lymph increases Ca2+ transients by a prolongation of AP as a result of a reduction of Ito with no intrinsic change in ICa or exchanger. The electrophysiological changes are similar to those that occur during compensated cardiac hypertrophy, suggesting a common mechanistic link between burn lymph- and hypertrophy-induced cardiac dysfunction.

4-Aminopyridine↗
PubMed2003

Bone marrow failure following severe injury in humans.

BACKGROUND: Hematopoietic failure has been observed in experimental animals following shock and injury. In humans, bone marrow dysfunction has been observed in the red cell component and characterized by a persistent anemia, low reticulocyte counts, and the need for repeated transfusions despite adequate iron stores. While a quantitative defect in white blood cell count has not been noted, an alteration in white blood cell function manifesting as an increased susceptibility to infection is well established. Since the etiology of this anemia remains unknown and the bone marrow has been rarely studied following injury, we measured various parameters of hematopoiesis directly using bone marrow from trauma patients and tested the hypothesis that trauma results in profound bone marrow dysfunction, which could explain both the persistent anemia and the alteration in white blood cell function. METHODS: Bone marrow aspirates and peripheral blood were obtained between day 1 and 7 following injury from 45 multiple trauma patients. Normal volunteers served as controls. Peripheral blood was assayed for hemoglobin concentration, reticulocyte count, erythropoietin levels, white blood cell count, and differential. Peripheral blood and bone marrow were cultured for hematopoietic progenitors (CFU-GM, BFU-E, and CFU-E colonies). RESULTS: Bone marrow CFU-GM, BFU-E, and CFU-E colony formation was significantly reduced while peripheral blood CFU-GM, BFU-E, and CFU-E was increased in the trauma patients compared with normal volunteers. Bone marrow stroma failed to grow to confluence by day 14 in >90% of trauma patients. In contrast, bone marrow stroma from volunteers always reached confluence between days 10 and 14 in culture. The mean hemoglobin concentration and reticulocyte counts of the trauma patients were 8.6 +/- 1.0 g/dL and 2.75 +/- 0.7% respectively, while their plasma erythropoietin levels were 2 to 10 times greater than control values. CONCLUSIONS: Release of immature white blood cells into the circulation may also contribute to a failure to clear infection and an increased propensity to organ failure. Concomitantly, profound changes occur within the bone marrow, which include the increased release of erythroid and myeloid progenitors into the circulation, a decrease in progenitor cell growth within the bone marrow, and an impaired growth of the bone marrow stroma. Erythropoietin levels are preserved following trauma, implying that the persistent anemia of injury is related to the failure of the bone marrow to respond to erythropoietin.

Adult↗
PubMed2003

Gut injury and gut-induced lung injury after trauma hemorrhagic shock is gender and estrus cycle specific in the rat.

BACKGROUND: The purpose of this study was to test the hypothesis that trauma-hemorrhagic shock (T/HS)-induced gut and lung injury is modulated by gender and the stage of the estrus cycle at the time of injury. METHODS: We compared the incidence and magnitude of gut and lung injury in male and female rats subjected to a laparotomy (trauma) followed by 90 minutes of shock (mean arterial pressure, 30 mm Hg) (T/HS) or sham shock. RESULTS: Lung injury and pulmonary neutrophil sequestration as well as gut injury were increased after T/HS in the diestrus female and the male rats, but not in the estrus or proestrus female rats. Although T/HS caused gut and lung injury in the male and the female diestrus rats, the magnitude of injury was less in the female diestrus than in the male rats (p < 0.05). A strong correlation was found between intestinal villous injury and lung injury as well as between gut injury and pulmonary leukosequestration in the female rats subjected to T/HS (p < 0.0001). Plasma nitric oxide levels were approximately two- to threefold higher in the male and the diestrus female rats subjected to T/HS than in other groups (p < 0.05), and a high degree of correlation (r2 = 0.68, p < 0.0001) was found between villous injury and plasma nitric oxide levels. Ileal constitutive nitric oxide synthase (NOS) and inducible NOS (iNOS) activity was measured. Ileal constitutive NOS activity was similar between the groups, but iNOS activity was three- to fourfold higher in the T/HS male rats than in the sham shock or the T/HS proestrus groups (p < 0.01). CONCLUSION: Gender and estrus cycle stage influence susceptibility to T/HS-induced gut and lung injury. This difference in susceptibility to organ injury was associated with increased plasma nitric oxide levels and increased ileal iNOS activity.

Animals↗
PubMed2003

Factors in intestinal lymph after shock increase neutrophil adhesion molecule expression and pulmonary leukosequestration.

BACKGROUND: Because the ischemic gut may produce factors that initiate systemic inflammation, we tested the hypothesis that factors released from the gut into the mesenteric lymphatics increase neutrophil (PMN) adhesion molecule expression after trauma and shock. METHODS: At 1 and 4 hours after hemorrhagic shock (30 mm Hg x 90 minutes) plus trauma (laparotomy) (T/HS) or sham-shock (T/SS), with or without mesenteric lymph duct ligation, PMN CD11b and CD18 expression was assessed in male rats. In additional rats, mesenteric lymph samples were tested for their ability to increase PMN CD11b expression in vitro. Lastly, at 4 hours after T/SS or T/HS with or without lymph duct ligation, pulmonary PMN sequestration was measured. RESULTS: Compared with T/SS rats, T/HS was associated with up-regulation of PMN CD11b and CD18 expression, which was largely prevented by ligation of the mesenteric lymph duct (p < 0.01). Lymph duct ligation also prevented T/HS-induced pulmonary leukocyte sequestration (p < 0.01). In addition, mesenteric lymph from rats subjected to T/HS but not T/SS increased CD11b expression (p < 0.01). CONCLUSION: Factors produced or released by the postischemic intestine and carried in the mesenteric lymph appear responsible for PMN activation and pulmonary PMN sequestration after an episode of T/HS.

Analysis of Variance↗
PubMed2003

Appearance of an erythrocyte population with decreased deformability and hemoglobin content following sepsis.

With the use of the cecal ligation and puncture model in mice, this study tested whether sepsis-induced decreased erythrocyte deformability is restricted to a subpopulation of cells. Erythrocyte subpopulations were isolated by centrifugal elutriation. Lineweaver-Burk conversion of deformability-response curves to shear stress was used to determine the shear stress at half-maximal cell elongation (K(EI)) and maximal cell elongation (EI(max)). Sepsis decreased erythrocyte deformability in whole blood. K(EI) values were elevated (2.7 vs. 2.1 Pa) and EI(max) values decreased (0.56 vs. 0.50) in sepsis compared with sham mice. K(EI) values for cells eluted at 7 ml/min (smallest and oldest cells) were similar; however, K(EI) values for cells eluted at 8 ml/min were greater in septic than sham animals (2.50 vs. 2.10). Younger and larger subpopulations of erythrocytes (eluted at 9, 10, and 11 ml/min) also showed a tendency of decreased deformability in sepsis. Mean corpuscular hemoglobin content was decreased in cells eluted at 7 and 8 ml/min in sepsis (4.5 and 10.2 pg) compared to sham (7.4 and 11.4 pg) mice. This study indicates that an erythrocyte subpopulation that represents 20% of circulating cells shows the most pronounced decrease in cell deformability during sepsis. Increased rigidity together with decreased corpuscular hemoglobin content in these cells may contribute to microcirculatory dysfunction and immune modulation during sepsis.

Animals↗
PubMed2002

Store-operated calcium entry in human neutrophils reflects multiple contributions from independently regulated pathways.

Human polymorphonuclear neutrophil (PMN) responses to G protein-coupled chemoattractants are highly dependent upon store-operated Ca(2+) entry (SOCE). Recent research suggests that SOCE currents can be mediated by a variety of related channel proteins of the transient receptor potential superfamily. SOCE has been regarded as a specific response to depletion of cell calcium stores. We hypothesized that net SOCE might reflect the contributions of more than one calcium entry pathway. SOCE was studied in normal human PMN using Ca(2+) and Sr(2+) ions. We found that PMN SOCE depends on at least two divalent cation influx pathways. One of these was nonspecific and Sr(2+) permeable; the other was Ca(2+) specific. The two pathways show different degrees of dependence on store depletion by thapsigargin and ionomycin, and differential sensitivity to inhibition by 2-aminoethyoxydiphenyl borane and gadolinium. The inflammatory G protein-coupled chemoattractants fMLP, platelet-activating factor, and IL-8 elicit unique patterns of Sr(2+) and Ca(2+) influx channel activation, and SOCE responses to these agonists displayed differing degrees of linkage to prior Ca(2+) store depletion. The mechanisms of PMN SOCE responses to G protein-coupled chemoattractants are physiologically diverse. They appear to reflect Ca(2+) transport through a variety of channels that are independently regulated to varying degrees by store depletion and by G protein-coupled receptor activation.

Calcium↗
PubMed2002

Influence of storage on red blood cell rheological properties.

BACKGROUND: It is known that the age of transfused blood is a risk factor for the development of multiple organ failure in surgical patients. However, the character of hemorrheological changes in stored blood as well as the time when they appear remains disputable. We assumed that blood storage was accompanied by a progressive decrease of RBC deformability and rheological disorders. The degree of rheological disturbances should be directly proportional to the number of RBC with altered geometry. MATERIALS AND METHODS: Nine packages of RBC kept in adenine saline solution were examined from the 5th to the 42nd day of storage. RBC deformability index (DI) was determined by micropore filtration technique. RBC shape was estimated by means of scanning electron microscopy. Blood clotting time was measured by Sonoclot coagulation analyzer. RESULTS: Significant alterations of RBC shape started at the second week of storage and progressed during the rest of the storage period. RBC shape changes were accompanied by progressive decrease in DI and increase in hemolysis and acidosis. The correlation index between the percentage of abnormally shaped RBC and DI was -0.81 (P = 0.0258). Blood clotting progressively decreased after 2 weeks of storage, probably due to the exhaustion of some procoagulant plasma factors. CONCLUSIONS: Serious hemorrheological disorders, including the decrease in RBC deformability secondary to shape abnormalities, acidosis, and the decrease of blood clotting, start already at the second week of storage and progress up to the end of the storage period. Transfusion of packed RBC older than 7 days may contribute to hemorrheological disorders in critically ill patients.

Adenine↗
PubMed2002

Hyperosmotic stress induces nuclear factor-kappaB activation and interleukin-8 production in human intestinal epithelial cells.

Inflammatory bowel disease of the colon is associated with a high osmolarity of colonic contents. We hypothesized that this hyperosmolarity may contribute to colonic inflammation by stimulating the proinflammatory activity of intestinal epithelial cells (IECs). The human IEC lines HT-29 and Caco-2 were used to study the effect of hyperosmolarity on the IEC inflammatory response. Exposure of IECs to hyperosmolarity triggered expression of the proinflammatory chemokine interleukin (IL)-8 both at the secreted protein and mRNA levels. In addition, hyperosmotic stimulation induced the release of another chemokine, GRO-alpha. These effects were because of activation of the transcription factor, nuclear factor (NF)-kappaB, because hyperosmolarity stimulated both NF-kappaB DNA binding and NF-kappaB-dependent transcriptional activity. Hyperosmolarity activated both p38 and p42/44 mitogen-activated protein kinases, which effect contributed to hyperosmolarity-stimulated IL-8 production, because p38 and p42/44 inhibition prevented the hyperosmolarity-induced increase in IL-8 production. In addition, the proinflammatory effects of hyperosmolarity were, in a large part, mediated by activation of Na(+)/H(+) exchangers, because selective blockade of Na(+)/H(+) exchangers prevented the hyperosmolarity-induced IEC inflammatory response. In summary, hyperosmolarity stimulates IEC IL-8 production, which effect may contribute to the maintenance of inflammation in inflammatory bowel disease.

Chemokine CXCL1↗
PubMed2002

Dopamine suppresses IL-12 p40 production by lipopolysaccharide-stimulated macrophages via a beta-adrenoceptor-mediated mechanism.

In this study, we examined the effect of dopamine on the production of IL-12 p40 by lipopolysaccharide (LPS)-stimulated J774.1 macrophages and mouse peritoneal macrophages. Treatment of J774.1 cells with dopamine (0.01-100 microM) decreased the release of IL-12 p40, in a concentration-dependent manner. The attenuating effect of dopamine on IL-12 p40 production appeared to be pretranslational, because dopamine decreased mRNA accumulation of IL-12 p40. The inhibitory effect of dopamine on IL-12 p40 production by J774.1 macrophages was not mediated by dopamine receptors, because dopamine receptor antagonists were unable to reverse the dopamine-induced suppression of IL-12 p40 production. Since the beta-adrenoceptor antagonist propranolol completely prevented the inhibitory effect of dopamine on IL-12 p40 production, the suppressive effect of dopamine on IL-12 p40 production by J774.1 cells is mediated by beta-adrenoceptors. In contrast to J774.1 cells, propranolol only partially reversed the inhibitory effect of dopamine on IL-12 production by peritoneal macrophages. Furthermore, dopamine stimulated the production of the anti-inflammatory cytokine IL-10 in both J774.1 cells and peritoneal macrophages. While the stimulatory effect of dopamine on IL-10 production by J774.1 cells was beta-adrenoceptor-mediated, dopamine increased IL-10 production by peritoneal macrophages via both beta-adrenoceptor-dependent and independent mechanisms. These results indicate that dopamine has multiple anti-inflammatory effects mediated by both beta-adrenoceptor dependent and independent mechanisms.

Animals↗
PubMed2002

Adenosine: a potential mediator of immunosuppression in multiple organ failure.

Multiple organ failure following a variety of insults, including, trauma, shock and pancreatitis, is the cause of 50-80% of all deaths in surgical intensive care units. In most patients, infections secondary to a general immunosuppressive state serve to trigger the development of multiple organ failure. This immunosuppressive state may be a consequence of excessive release of adenosine into the extracellular space, as adenosine has multiple immunosuppressive effects. Activation of adenosine receptors on immune cells inhibits the production of proinflammatory cytokines such as tumor necrosis factor alpha and interleukin (IL)-12, and increases the production of the anti-inflammatory cytokine IL-10. In addition, adenosine receptor activation appears to suppress cellular immunity by decreasing T helper cell (Th)1 and increasing Th2 responses. A deeper understanding of the role of adenosine in multiple organ failure may facilitate the development of adenosine-based therapeutic strategies.

Adenosine↗
PubMed2002

Inosine exerts a broad range of antiinflammatory effects in a murine model of acute lung injury.

OBJECTIVE: To investigate the effects of inosine on the acute lung inflammation induced by lipopolysaccharide (LPS) in vivo and on the activation and cytotoxicity elicited by proinflammatory cytokines on human lung epithelial (A549) cells in vitro. SUMMARY BACKGROUND DATA: Inosine is an endogenous purine recently shown to exert immunomodulatory and antiinflammatory effects. METHODS: Mice challenged with intratracheal LPS (50 microg) were treated after 1, 6, and 12 hours with inosine (200 mg/kg intraperitoneal) or vehicle. After 24 hours, bronchoalveolar lavage fluid was obtained to measure proinflammatory (tumor necrosis factor-alpha [TNF-alpha], interleukin [IL]-1beta, IL-6), and antiinflammatory (IL-10, IL-4) cytokines, chemokines (MIP-1alpha and MIP-2), myeloperoxidase activity and total cell counts, nitric oxide production, and proteins. Lung histology and immunohistochemical detection of 3-nitrotyrosine, a marker of nitrosative stress, were performed in inflated-fixed lungs. In vitro, cell viability and production of the chemokine IL-8 were evaluated in A549 cells stimulated with a mixture of cytokines in the presence or absence of inosine. RESULTS: Inosine downregulated the LPS-induced expression of TNF-alpha, IL-1beta, IL-6 and MIP-2 and tended to reduce MIP-1alpha, whereas it enhanced the production of IL-4. Total leukocyte counts, myeloperoxidase, nitric oxide production, and proteins were all significantly decreased by inosine. The purine also improved lung morphology and suppressed 3-nitrotyrosine staining in the lungs after LPS. Inosine attenuated the cytotoxicity and the expression of IL-8 induced by proinflammatory cytokines in A549 cells. CONCLUSIONS: Inosine largely suppressed LPS-induced lung inflammation in vivo and reduced the toxicity of cytokines in lung cells in vitro. These data support the proposal that inosine might represent a useful adjunct in the therapy of acute respiratory distress syndrome.

Animals↗
PubMed2002

Elemental and intravenous total parenteral nutrition diet-induced gut barrier failure is intestinal site specific and can be prevented by feeding nonfermentable fiber.

OBJECTIVE: Parenteral nutrition and elemental diets both cause bacterial translocation, immune dysfunction, and increased infection in laboratory animals, whereas elemental diets, with or without fiber, ameliorate some, but not all gut barrier failure. The purpose of this study is to investigate, in an Ussing chamber system, whether elemental vs. parenteral diets induce gut barrier failure in specific anatomical sites in the intestine and whether fiber can ameliorate this phenomenon. DESIGN: Controlled study in laboratory animals. SETTING: University laboratory. SUBJECTS: Male Sprague-Dawley rats. INTERVENTIONS: Nutritional support was provided to rats for 7 days by oral total parenteral nutrition (TPN; elemental diet) 307 kcal/kg/day, intravenous TPN (parenteral diet) 307 kcal/kg/day via jugular venous catheters, or rodent chow (controls). MEASUREMENTS AND MAIN RESULTS: Permeability to bacteria in intestinal segments of ileum, jejunum, and colon was evaluated in an Ussing chamber. Results were correlated with bacterial translocation to the mesenteric lymph nodes. Intravenous TPN caused greater bacterial translocation in all small intestinal segments and the cecum when compared with chow (p <.05). Oral TPN caused gut barrier failure only in the ileal segment, but not in the remainder of the small intestine (p <.001). Addition of cellulose provided a greater protection of the ileum to permeability than did pectin (p <.01). CONCLUSIONS: TPN causes global intestinal barrier failure, but elemental diet prevents barrier failure in parts of the small intestine other than the ileum. The addition of cellulose fiber to elemental diet can ameliorate further barrier failure in the ileum.

Analysis of Variance↗
PubMed2002

Isolated traumatic brain injury: age is an independent predictor of mortality and early outcome.

BACKGROUND: Geriatric trauma patients have a worse outcome than the young with comparable injuries. The contribution of traumatic brain injury (TBI) to this increased mortality is unknown and has been confounded by the presence of other injuries. The purpose of this study was to investigate the role of age in the mortality and early outcome from isolated TBI. METHODS: This was a retrospective analysis of all adult patients with isolated TBI (Abbreviated Injury Scale score > or = 3) admitted during a 5-year period to two Level I trauma centers. Mortality, Glasgow Outcome Scale score at discharge, therapy, and complications were compared for elderly (age > or = 65 years) and younger patients. RESULTS: Of 694 patients, 22% were defined as elderly. The mortality for the elderly group was twice that of their younger counterparts (30% vs. 14%, p < 0.001), even for those with mild to moderate TBI (Glasgow Coma Scale score of 9-15). Thirteen percent of elderly survivors had a poor functional outcome (Glasgow Outcome Scale score of 2 or 3) at hospital discharge versus 5% in the young group (p < 0.01). Independent factors associated with a high mortality were age and Glasgow Coma Scale score. CONCLUSION: The mortality from TBI is higher in the geriatric population at all levels of head injury. In addition, functional outcome at hospital discharge is worse. Although some of this increased mortality may be explained by complications or type of head injury, age itself is an independent predictor for mortality in TBI.

Adult↗
PubMed2002

Shock mesenteric lymph-induced rat polymorphonuclear neutrophil activation and endothelial cell injury is mediated by aqueous factors.

BACKGROUND: After trauma and hemorrhagic shock (T/HS), mesenteric lymph (ML) activates polymorphonuclear neutrophils (PMNs), injures endothelial cells (ECs), and predisposes to lung injury. The involved mediators, however, are unknown. We studied the ability of aqueous (AQ) and lipid (LIP) extracts of rat T/HS ML to activate PMNs and injure ECs. METHODS: ML was collected from male rats undergoing trauma (laparotomy) plus hemorrhagic shock (30 mm Hg, 90 minutes) or sham shock. AQ and LIP ML fractions were separated using the Bligh-Dyer technique. Human umbilical vein endothelial cells were incubated 18 hours in 5% LIP or AQ lymph fractions and viability was assessed using the MTT assay. Rat PMNs incubated 5 minutes with 3% LIP or AQ fractions were assessed for respiratory burst (RB) and cytosolic calcium ([Ca(2+)](i)) using dihydrorhodamine 123 and fura-2AM. Human PMN responses to AQ and LIP T/HS lymph were studied similarly. RESULTS: EC incubated in AQ showed 19 +/- 4% viability as compared with 65 +/- 11% in LIP (p < 0.001). Whole lymph affected ECs comparably to AQ T/HS lymph. Rat PMN basal [Ca(2+)](i) increased after exposure to AQ but not LIP T/HS lymph extracts. AQ T/HS lymph primed [Ca(2+)](i) responses to macrophage inflammatory protein-2 and platelet-activating factor; neither LIP T/HS nor any trauma and sham shock lymph fraction caused PMN priming. Rat PMN RB was elevated after AQ T/HS lymph incubation when compared with buffer (610 +/- 122 U/s vs. 225 +/- 38 U/s, p = 0.01). Rat PMN incubation in LIP T/HS lymph caused minimal activation (289 +/- 28 U/s, p = NS). Conversely, human PMN showed [Ca(2+)](i) and RB priming by rat T/HS LIP and not AQ extracts. CONCLUSION: T/HS mesenteric lymph contains multiple biologically active mediators. Both AQ and LIP extracts of T/HS lymph are toxic to human umbilical vein endothelial cells, with AQ more active than LIP. Only AQ T/HS lymph activates rat PMNs, although LIP rat lymph extract activates human PMNs. These findings demonstrate the complex nature of gut lymph-derived biologic factors as well as species-specific differences on PMN and EC physiology. Therapies directed at any one specific molecule or mediator are therefore unlikely to be successful.

Animals↗
PubMed2002

Influence of gut microflora on mesenteric lymph cytokine production in rats with hemorrhagic shock.

OBJECTIVE: The aim of the present study was to test the hypothesis that the resident gut microflora play a role in modulating gut cytokine production under normal circumstances and in response to tissue injury with or without hemorrhagic shock. METHODS: The postnodal lymph was collected from the main mesenteric lymphatic channel 1 hour before, during (1.5 hours), and hourly for 6 hours after 90 minutes of sham or actual hemorrhagic shock (30 mm Hg) in the following three groups of rats, all of which had laparotomies and vascular instrumentation: rats with a normal gut flora (NF), rats whose gut flora had been decontaminated with oral antibiotics (AD), and rats with Escherichia coli C25 intestinal overgrowth (MA). Interleukin (IL)-6 and TNF levels in the mesenteric lymph were measured using cytokine-dependent cellular assays. Endotoxin levels and endotoxin-neutralizing capacity in the lymph were also measured. RESULTS: Mesenteric lymph IL-6 levels in the laparotomized MA-sham animals were significantly elevated compared with NF-sham animals at 2 to 4 hours (p < 0.05) and at 5 and 6 hours after sham shock (p < 0.01). Similarly, IL-6 levels in laparotomized AD-shock animals were increased when compared with NF-shock animals 3 hours after shock (p < 0.001). Lymph tumor necrosis factor bioactivity, although present in all surgically manipulated groups, was scarcely detectable in untouched animals. Endotoxin-neutralizing capacity was significantly impaired in shocked animals compared with untouched animals. CONCLUSION: Changes in the gut microflora modulate the gut cytokine production after tissue injury with or without hemorrhagic shock, with intestinal bacterial overgrowth leading to the greatest increase in mesenteric lymph IL-6 levels.

Animals↗
PubMed2002

Nitric oxide directly impairs intestinal barrier function.

Excess production of nitric oxide (NO) has been implicated in endotoxin-induced loss of gut barrier function in vivo. Thus, we tested the direct effect of NO on the barrier function of intestinal mucosal membranes suspended ex vivo in Ussing chambers and on IEC-6 enterocyte monolayers. In these experiments, ex vivo-mounted ileal membranes or IEC-6 cell enterocyte monolayers were exposed to the NO donor, S-nitroso-N-acetyl-penicillamine (SNAP) over a dose range (10 microm to 2 mM) or medium. SNAP at concentrations of 1 or 2 mM, but not 10 or 100 microM, increased the rates of bacterial translocation (BT) across both the ileal membranes and the IEC-6 monolayers by >1 log (P < 0.05), as well as the permeability of the IEC-6 monolayers to phenol red (P < 0.05). The ileal membranes exposed to 1 or 2 mM SNAP for 3 h manifested histologic evidence of mucosal injury and decreases in electrical resistance and potential difference values (P < 0.05), while the IEC-6 cells exposed to SNAP for 18 h had increased levels of cell death (P < 0.05). Since NO produced locally by stimulated enterocytes could contribute to barrier dysfunction, NO production, iNOS mRNA levels, and monolayer permeability were measured in enterocytes (IEC-6 and Caco-2) exposed to medium, endotoxin (lipopolysaccharide [25 microg/mL]) or a cytokine mixture (IL-1beta 10 ng/mL, TNF-alpha 10 ng/mL, and INF-gamma 250 U/mL) for 6 or 24 h. Endotoxin increased NO production, iNOS mRNA expression, and monolayer permeability in the IEC-6, but not the Caco-2 cells, while exposure to the cytokine mixture increased both NO production, iNOS mRNA expression, and monolayer permeability in both the IEC-6 and Caco-2 cell lines. Based on the results of these studies it appears that NO can directly increase ileal mucosal membrane and enterocyte monolayer permeability and BT and that increased NO production and iNOS mRNA expression is associated with endotoxin- and/or cytokine-induced loss of enterocyte monolayer barrier function.

Animals↗