Biomedical subjects

I H Chaudry

Publications and source records attributed to I H Chaudry.

At least 37 records · Page 2Linked to original sources

PubMed2001

Cyclooxygenase-2-mediated regulation of Kupffer cell interleukin-6 production following trauma-hemorrhage and subsequent sepsis.

Studies indicate that trauma-hemorrhage results in activation of Kupffer cells to release inflammatory mediators and it leads to immunosuppression and increased susceptibility to subsequent sepsis. The cyclooxygenase (COX) product prostaglandin (PG) E2 appears to be central to this process, however, non-selective inhibition of COX activity with non-steroidal anti-inflammatory agents that block both the constitutive (COX-1) and inducible (COX-2) isoforms of cyclooxygenase has not yielded promising results in trauma patients. Nonetheless, it remains unknown whether selective inhibition of COX-2 activity has any salutary effect following trauma-hemorrhage and subsequent induction of sepsis. To study this, male C3H/HeN mice were subjected to laparotomy (i.e., soft-tissue trauma) and hemorrhagic shock (35 +/- 5 mmHg for 90 min, then resuscitated) or to sham operation. Twenty-four hours later, the mice were subjected to sepsis by cecal ligation and puncture (CLP) or to sham CLP. The mice were treated with the COX-2 inhibitor NS-398 (10 mg/kg body weight, intraperitoneally) or vehicle immediately after trauma-hemorrhage or sham operation, 12 h thereafter, and following CLP or sham CLP. At 5 h after CLP, plasma PGE2, Interleukin-(IL) 6, and TNF-alpha levels were determined along with Kupffer cell IL-6 and TNF-alpha production in vitro. NS-398 treatment markedly suppressed the elevation in plasma PGE2 levels following CLP. The increase in plasma IL-6 levels after CLP were also significantly attenuated by NS-398 treatment. In vitro Kupffer cell IL-6 production after CLP was significantly reduced by in vivo NS-398 treatment. However, NS-398 had no effect on TNF-alpha levels, in vivo and in vitro. These findings indicate that activation of COX-2 following trauma-hemorrhage and subsequent sepsis up-regulates Kupffer cell IL-6 production. Thus, selective inhibition of COX-2 activity may reduce the deleterious consequences of sepsis under such conditions.

Animals↗

PubMed2001

MAPK p38 antagonism as a novel method of inhibiting lymphoid immune suppression in polymicrobial sepsis.

Although studies indicate that a shift from a Th1 to a Th2 response contributes to a marked suppression of cell-mediated immunity during sepsis, the mechanism by which this occurs remains unknown. Given that the mitogen-activated protein kinase (MAPK) p38 plays a critical role in the activation and function of immune cells, the aim of this study was to determine the contribution of MAPK p38 activation to the immune dysfunction seen in polymicrobial sepsis. To study this, polymicrobial sepsis was induced in C3H/HeN male mice by cecal ligation and puncture (CLP). Splenic lymphocytes and purified T cells were harvested 24 h post-CLP, pretreated with the specific MAPK p38 inhibitor SB-203580, and then stimulated with a monoclonal antibody against the T cell marker CD3. The results indicate that interleukin (IL)-2 release is markedly depressed while the release of the immunosuppressive mediator, IL-10, as well as mRNA levels of IL-10 and IL-4, are augmented after CLP. Inhibition of MAPK p38 suppressed in vitro IL-10 levels as well as IL-10 and IL-4 gene expression while restoring the release of IL-2. To determine whether these in vitro findings could be translated to an in vivo setting, mice were given 100 mg of SB-203580/kg body wt or saline vehicle (intraperitoneal) at 12 h post-CLP. Examination of ex vivo lymphocyte responsiveness indicated that, as with the in vitro finding, septic mouse Th1 responsiveness was restored. In light of our recent finding that delayed in vivo SB-203580 treatment also improved survival after CLP, we believe that these results not only illustrate the role of MAPK p38 in the induction of immunosuppressive agents in sepsis but demonstrate that SB-203580 administration after the initial proinflammatory state of sepsis significantly prevents the morbidity from sepsis.

Animals↗

PubMed2001

17 beta-Estradiol normalizes immune responses in ovariectomized females after trauma-hemorrhage.

Recent studies indicate that immune responses in proestrus females are maintained after trauma-hemorrhage but markedly depressed in ovariectomized females under such conditions. The current study tested the hypothesis that the decreased estrogen levels after ovariectomy are responsible for this immune depression. To study this hypothesis, ovariectomized female CBA/J mice were subjected to laparotomy (i.e., soft tissue trauma) and hemorrhagic shock (35 +/- 5 mmHg for 90 min, then resuscitated) or sham operation. The mice received either 17 beta-estradiol (E2; 100 microg/25 g body wt) or vehicle subcutaneously during resuscitation. Immune cells were isolated 24 h thereafter. Splenocyte proliferation and interferon-gamma, interleukin (IL)-2, and IL-3 release were significantly depressed after trauma-hemorrhage in vehicle-treated mice, whereas these functions were maintained in E2-treated mice. Peritoneal macrophage IL-1 beta and IL-6 release and splenic macrophage IL-6 and IL-12 release were also significantly depressed in vehicle-treated mice after trauma-hemorrhage, and release of these cytokines was restored by E2 treatment. In summary our findings indicate that the depressed splenic and peritoneal immune responses after trauma-hemorrhage can be normalized by a single dose of E2. Thus estrogen appears to be the causative factor in the maintenance of immunocompetence in females after trauma-hemorrhage, and its administration to ovariectomized or postmenopausal females should be helpful in preventing immune depression under such conditions.

Animals↗

PubMed2001

Resistance of macrophages to the suppressive effect of interleukin-10 following thermal injury.

The activation of a macrophage (Mphi)-dependent proinflammatory cascade following thermal injury plays an important role in the development of immunosuppression and increased susceptibility to subsequent sepsis in burn patients. In contrast, although interleukin (IL)-10, an anti-inflammatory cytokine that can downregulate M phi activity, has also been implicated in postburn immune dysfunction, its role in the regulation of M phi function postburn remains unclear. To study this, C57BL/6 female mice were subjected to a 25% total body surface area third-degree scald burn, and splenic Mphis were isolated 7 days later. Lipopolysaccharide (LPS)-stimulated IL-10, IL-6, tumor necrosis factor (TNF)-alpha, and nitric oxide (NO) production were significantly increased in the burn group compared with shams. Blockade of endogenous IL-10 activity enhanced IL-6 and TNF-alpha release, but not NO release, in both groups. The addition of exogenous IL-10 to the M phi cultures dose dependently suppressed production of these inflammatory mediators in both groups. The timing of IL-10 addition to the cultures in relation to LPS stimulation, however, was critical. The suppressive effect of exogenous IL-10 was attenuated in both groups when the cells were exposed to IL-10 at 4-6 h after LPS stimulation; however, Mphis from injured mice were significantly better able to maintain inflammatory mediator-productive capacity. The resistance of Mphis from injured mice to IL-10-mediated suppression correlated with decreased IL-10 receptor (IL-10R) expression and increased CD11b expression. These findings suggest that Mphis, following thermal injury, display resistance to suppression by IL-10 due in part to downregulation of IL-10R expression.

Animals↗

PubMed2001

Increased apoptosis in lamina propria B cells during polymicrobial sepsis is FasL but not endotoxin mediated.

Recent studies from our laboratory demonstrated that mucosal lymphoid tissue such as Peyer's patch cells and lamina propria (LP) B lymphocytes from mice shows evidence of increased apoptosis after sepsis that is associated with localized inflammation/activation. The mechanism for this is poorly understood. Endotoxin as well as Fas/Fas ligand (FasL) have been shown to augment lymphocyte apoptosis; however, their contribution to the increase of apoptosis in LP B-cells during sepsis is not known. To study this, sepsis was induced by cecal ligation and puncture (CLP) in endotoxin-tolerant C3H/HeJ or FasL-deficient C3H/HeJ-FasL(gld) (FasL(-)) mice and LP lymphocytes were isolated 24 h later. Phenotypic, apoptotic, and functional indexes were assessed. The number of LP B cells decreased markedly in C3H/HeJ mice but not in FasL-deficient animals at 24 h after CLP. This was associated with comparable alteration in apoptosis and Fas antigen expression in the B cells of these mice. Septic LP lymphocytes also showed increased IgA production, which was absent in the FasL-deficient CLP mice. Furthermore, Fas ligand deficiency appeared to improve survival of septic challenge. These data suggest that the increase in B cell apoptosis in septic animals is partially due to a Fas/FasL-mediated process but not endotoxin.

Animals↗

PubMed2001

Norepinephrine-induced hepatocellular dysfunction in early sepsis is mediated by activation of alpha2-adrenoceptors.

Gut-derived norepinephrine (NE) has been shown to play a critical role in producing hepatocellular dysfunction in early sepsis, but it is not known whether alpha2-adrenoceptor activation mediates this dysfunction. We infused normal male adult rats with NE, NE plus the specific alpha2-adrenergic antagonist rauwolscine (RW), or vehicle (normal saline) for 2 h. Hepatocellular function was determined by in vivo indocyanine green (ICG) clearance. An isolated perfused liver preparation was also used to assess hepatocellular function by in vitro ICG clearance; NE alone or with RW was added to the perfusate. Rats were subjected to sepsis by cecal ligation and puncture (CLP). At 1 h after CLP, RW was infused for 15 min. At 5 h after CLP, we measured hepatocellular function and serum tumor necrosis factor-alpha (TNF-alpha) levels. Intraportal NE infusion in normal rats produced hepatocellular dysfunction, which was prevented by RW and NE infusion. This is confirmed by findings with the isolated perfused liver preparation. RW administration in early sepsis maintained hepatocellular function and downregulated TNF-alpha production at 5 h after CLP. These results suggest that NE-induced hepatocellular dysfunction in early sepsis is mediated by alpha2-adrenoceptor activation, which appears to upregulate TNF-alpha production. Modulation of hepatic responsiveness to NE by alpha2-adrenergic antagonists should provide a novel approach for maintaining cell and organ functions during sepsis.

Animals↗

PubMed2001

The small intestine plays an important role in upregulating CGRP during sepsis.

Although studies have indicated that calcitonin gene-related peptide (CGRP), a potent vasodilatory peptide, is upregulated after endotoxic shock, it remains controversial whether this peptide increases during sepsis and, if so, whether the gut is a significant source of CGRP under such conditions. To study this, polymicrobial sepsis was induced by cecal ligation and puncture (CLP) followed by fluid resuscitation. Plasma levels of CGRP were measured at 2, 5, and 10 h after CLP (i.e., early, hyperdynamic sepsis) and at 20 h after CLP (late, hypodynamic sepsis). The results indicate that plasma CGRP did not increase at 2--5 h but increased by 177% at 10 h after CLP (P < 0.05). At 20 h after the onset of sepsis, however, the elevated plasma CGRP returned to the sham level. To determine the source of the increased plasma CGRP, the liver, spleen, small intestine, lungs, and heart were harvested, and tissue CGRP was assayed at 10 h after CLP in additional animals. Only the small intestine showed a significant increase in tissue levels of CGRP (by 129%, P < 0.05). Determination of portal vs. systemic levels of CGRP indicates that portal CGRP was 65.7 +/- 22.7% higher than the systemic level at 10 h after CLP, whereas portal CGRP in sham-operated rats was only 4.9 +/- 2.1% higher. Immunohistochemistry examination revealed that CGRP-positive stainings increased in the intestinal tissue but not in the liver at 10 h after the onset of sepsis. The distribution of CGRP stainings was associated with intestinal nerve fibers. These results, taken together, demonstrate that upregulation of CGRP occurs transiently during the progression of sepsis (at the late phase of the hyperdynamic sepsis), and the gut appears to be a major source of such an increase in circulating levels of this peptide.

Animals↗

PubMed2001

The small intestine is an important source of adrenomedullin release during polymicrobial sepsis.

Adrenomedullin (AM), a potent vasodilatory peptide, has recently been reported to be involved in the altered cardiovascular responses under various pathophysiological conditions. Although the increase in plasma AM levels is associated with upregulation of AM gene expression in various tissues, it remains unknown whether the gut is an important source of AM release under such conditions. To determine this, adult male rats were subjected to sepsis by cecal ligation and puncture (CLP) followed by fluid resuscitation. Systemic and portal blood samples were collected simultaneously at 10 and 20 h after CLP or sham operation. A portion of the jejunum was also harvested. Plasma and tissue levels of AM were then determined by RIA. The localization of AM in the intestinal tissue was examined using immunohistochemistry. In an additional group of normal rats, synthetic rat AM (8.5 microg/kg body wt) was infused for 15 min at a constant rate via the portal vein (which produces a similar level of AM as observed during sepsis). Cardiac output, stroke volume, total peripheral resistance, and microvascular blood flow in various organs were determined before and 30 min after AM administration. The results indicate that AM levels in portal blood were significantly higher than in systemic blood at 10 and 20 h after CLP. Intestinal AM was also markedly elevated. Immunohistochemical visualization shows that AM immunostainings were localized in the mucosa, submucosa, and intestinal nerve fibers, and they were increased at 10-20 h post-CLP. Because AM-immunopositive nerve fibers increase in the gut during sepsis, a nerve pathway may be involved in the regulation of vascular reactivity by this peptide. Moreover, intraportal administration of AM increased cardiac output, stroke volume, and microvascular blood flow in the liver, kidney, small intestine, and spleen. In contrast, total peripheral resistance was significantly reduced. Thus the gut plays an important role in increasing the levels of circulating AM during the progression of sepsis. Gut-derived AM appears to be a major factor in initiating the hyperdynamic response after the onset of sepsis.

Adrenomedullin↗

PubMed2001

Divergent immune responses in male and female mice after trauma-hemorrhage: dimorphic alterations in T lymphocyte steroidogenic enzyme activities.

Immune responses are suppressed in males, but not in proestrous females, after trauma-hemorrhage. Testosterone and 17beta-estradiol appear to be responsible for divergent immune effects. There is considerable evidence to suggest sex steroid hormone involvement in immune functions. As formation of active steroid depends on the activity of androgen- and estrogen-synthesizing enzymes, expression and activity of 5alpha-reductase, aromatase, and 3beta- and 17beta- hydroxysteroid dehydrogenases were determined in spleen and T lymphocytes of male and proestrous female mice after trauma-hemorrhage. All of the enzymes were present in spleen, specifically in T lymphocytes. 5alpha-Reductase expression and activity increased in male T lymphocytes, whereas aromatase activity, but not expression, increased in female T lymphocytes. Increased 5alpha-reductase activity in male T lymphocytes is immunosuppressive because of increased 5alpha-dihydrotestosterone synthesis, whereas in females increased aromatase activity triggering 17beta-estradiol synthesis is immunoprotective. This study also demonstrates the importance of 17beta-hydroxysteroid dehydrogenase oxidative and reductive functions. The immunoprotection of proestrous females is associated with enhanced reductase function of the enzyme. In males, decreased expression of oxidative isomer type IV, which impairs catabolism of 5alpha-dihydrotestosterone, probably augments immunosuppression. This study provides evidence for the involvement of intracrine sex steroid synthesis in gender dimorphic immune responses after trauma-hemorrhage.

17-Hydroxysteroid Dehydrogenases↗

PubMed2000

Sustained elevation of norepinephrine depresses hepatocellular function.

The sympathetic-adrenal system is rapidly activated in response to sepsis or hemorrhagic shock, resulting in an increase in circulating levels of catecholamines. Although it has been shown that the occurrence of hepatocellular dysfunction under such conditions is associated with an early and sustained increase in plasma norepinephrine (NE), it remains unknown whether the increased NE per se plays any role in producing hepatocellular dysfunction. To study this, exogenous NE was administered, by implantation of a peritoneal mini-osmotic pump (consistently releasing NE), to produce a plasma level of NE similar to that observed after sepsis or hemorrhage. At 24 h after the pump implantation, cardiac output was determined by dye dilution technique and hepatocellular function [i.e., the maximal velocity (V(max)) and the efficiency of the transport (K(m)) of in vivo indocyanine green clearance) was assessed without blood sampling. In addition, tissue perfusion in various organs was determined using laser Doppler flowmetry. Plasma levels of interleukin-6 were measured by bioassay and liver enzymes were assayed enzymatically. The results indicate that sustained (24 h) elevation of plasma levels of NE caused a decrease in cardiac output and microvascular blood flow in the liver, spleen, and small intestine. In addition, the increase in plasma NE produced significant depression in hepatocellular function as evidenced by reduced V(max) and K(m). This was associated with elevated plasma levels of liver enzymes, indicating hepatocyte injury. In addition, plasma levels of interleukin-6 increased significantly. These findings suggest that sustained elevated levels of NE, observed after sepsis or hemorrhagic shock, may play an important role in producing hepatocellular dysfunction and altered hepatocyte integrity.

Adrenergic alpha-Agonists↗

PubMed2000

Immune suppression in polymicrobial sepsis: differential regulation of Th1 and Th2 responses by p38 MAPK.

BACKGROUND: Studies have indicated that a shift from a Th1 to a Th2 response occurs that contributes to the late immunosuppression seen during sepsis. However, the mechanism by which this occurs is unknown. In this regard, mediators released in response to sepsis are thought to upregulate a family of stress-induced mitogen-activated protein kinases (MAPKs), such as JNK, ERK, and p38 MAPK, which may play a role in this process. MATERIALS AND METHODS: To determine the role of MAPK in immune suppression, we induced polymicrobial sepsis in C3H/HeN male mice using cecal ligation and puncture (CLP). Splenic lymphocytes were harvested 24 h post-CLP and stimulated with the T-cell mitogen concanavalin A, and the expression and activation of these MAPKs were assessed by Western analysis. To determine the extent to which these MAPKs may have an impact on splenic immune function, cells were pretreated with a 10 microM concentration of the p38 MAPK inhibitor SB203580 or the MEK inhibitor PD98059 or with DMSO vehicle. The cells were then stimulated with 2.5 microg/ml of the T-cell mitogen concanavalin A, and cytokine release was then determined (by ELISA). RESULTS: In the lymphocytes from CLP mice no JNK signal was detected, however, p38 expression and activation were markedly (P < 0.05, n = 6) increased. In contrast, the expression of activated ERK markedly decreased following septic challenge. The results indicate that p38 MAPK inhibition with SB203580 suppressed the sepsis-induced augmentation of interleukin-10 release while restoring the suppressed Th1 cytokine interleukin-2 release typically encountered following sepsis. Inhibition of ERK had no effect on cytokine release. Neither PD98059 nor SB203580 had an effect on interferon gamma release or on proliferative capacity. CONCLUSION: This would indicate that the induction of p38 MAPK activation in splenocytes contributes to the immunosuppression seen in late sepsis.

Animals↗

PubMed2000

Neither Fas ligand nor endotoxin is responsible for inducible peritoneal phagocyte apoptosis during sepsis/peritonitis.

Regulation of the phagocyte apoptotic response appears to play a significant role in the pathophysiology of sepsis. In this regard, prior studies have shown that the onset of phagocyte apoptosis, as well as those agents that regulate it at the nidus of infection, differ significantly from those seen in circulation. The aim of this study therefore was to determine if the increase in inducible phagocyte apoptosis and caspase activities seen in the peritoneum during sepsis is due to endotoxin or Fas ligand. To study this, male C3H/HeN (endotoxin-sensitive), C3H/HeJ (endotoxin-tolerant), and C3H/HeJ-FasL(gld) (endotoxin-tolerant/FasL-deficient) mice were subjected to cecal ligation and puncture or sham operation. Twenty-four hours later, phagocytes were collected and cultured with lipopolysaccharide (LPS), then harvested for apoptosis (propidium iodide cell cycle or cell death ELISA analysis), cytokine release (ELISA), and caspase activity (fluorogenic assay) determination. The data indicate that there was a marked increase in apoptosis in LPS-stimulated phagocytes which was associated with a significant increase in caspase 3, 8, and 9 activities but a decrease in caspase 1 activity from C3H/HeN and C3H/HeJ-FasL(gld) septic mice and an increase in caspase 3 and 8 activities in phagocytes from C3H/HeJ septic mice. Furthermore, cells from septic mice, including all three strains, lost their ability to produce IL-1beta and IL-6 in response to LPS stimulation. The inability to completely suppress these changes suggests that neither endotoxin (via signaling through TLR-4 pathway) nor Fas ligand regulates the peritoneal phagocyte apoptotic responses seen during the late phase of polymicrobial sepsis/peritonitis.

Animals↗

PubMed2000

The dissociation between upregulated endothelins and hemodynamic responses during polymicrobial sepsis.

Polymicrobial sepsis is characterized by an early, hyperdynamic phase followed by a late, hypodynamic phase. Although studies have suggested that endothelins (ETs) contribute to the development of shock after a bolus injection of endotoxin, little is known about the role of ETs in the transition from the hyperdynamic phase to the hypodynamic phase of sepsis. To study this, male adult rats were subjected to sepsis by cecal ligation and puncture (CLP) followed by fluid resuscitation. Plasma levels of ET-1 and ET-2 were measured by radioimmunoassay at 2, 5, 10 h (i.e. the early stage of sepsis), and 20 h (late stage) following CLP or sham operation. Tissue levels of ET-1 and ET-2 were determined in the heart, lungs, small intestine, and spleen at 5 h after CLP or sham operation. In addition, preproendothelin-1 (precursor of ET-1) gene expression was analyzed by reverse transcription-polymerase chain reaction (RT-PCR) at 5 h in the heart, lungs, small intestine, spleen, and liver. The results indicate that plasma levels of ET-1 and ET-2 were not different from values of sham groups at 2 and 20 h, but were significantly higher than the sham values at 5 and 10 h after CLP. While there were no significant increases in tissue levels of ET-1 and ET-2 at 5 h post-CLP, RT-PCR analysis indicates a significant upregulation of preproendothelin-1 gene expression in the heart, spleen, and liver (but not in the lungs or small intestine) at 5 h after the onset of sepsis. These results indicate that the heart, spleen, and liver appear to be important ET-producing organs during the early stage of sepsis. The lack of significant increases in tissue ET levels could be due to the possibility that the newly converted peptide is quickly transferred to the bloodstream. Since the hyperdynamic phase of sepsis occurs at 2-10 h and the hypodynamic phase occurs at 20 h after CLP, the increased plasma levels of ET at 5 and 10 h suggest that mediators other than ETs (such as adrenomedullin) are responsible for producing the biphasic hemodynamic responses during the progression of polymicrobial sepsis.

Animals↗

PubMed2000

Mechanism of the beneficial effects of pentoxifylline during sepsis: maintenance of adrenomedullin responsiveness and downregulation of proinflammatory cytokines.

BACKGROUND: Although it is known that pentoxifylline (PTX) produces various beneficial effects during sepsis, it remains unknown whether this agent has any salutary effects on the depressed vascular responsiveness to adrenomedullin (ADM), a novel potent vasodilatory peptide, under such conditions. MATERIALS AND METHODS: Adult male Sprague-Dawley rats were subjected to polymicrobial sepsis by cecal ligation and puncture (CLP). One hour after CLP, PTX (50 mg/kg body wt) or vehicle (normal saline) was infused intravenously over 90 min. Twenty hours after CLP (i.e., the late, hypodynamic stage of sepsis), the thoracic aorta and small intestine were isolated and preconstricted by norepinephrine. Rat ADM (10(-7) M) was applied, and the percentage of ADM-induced relaxation in the aortic rings and resistance vessels in the small intestine was determined. In addition, plasma ADM was determined by radioimmunoassay and tumor necrosis factor alpha (TNF-alpha), interleukin (IL)-1beta, and IL-6 levels were measured by enzyme-linked immunosorbent assay. RESULTS: The percentage of ADM-induced vascular relaxation in the aortic rings and resistance vessels of the isolated gut was significantly reduced 20 h after CLP. Administration of PTX early after the onset of sepsis, however, prevented the decrease in vascular ADM responsiveness at the macro- and microcirculatory levels. Plasma ADM levels increased after CLP, irrespective of PTX infusion, indicating that the effect of PTX was not mediated by altering ADM release. The upregulated TNF-alpha, IL-1beta, and IL-6 during late sepsis were, however, attenuated by PTX administration, suggesting that maintenance of ADM responsiveness by this agent appears to be due to downregulation of these cytokines. CONCLUSIONS: Since early administration of PTX maintains vascular ADM responsiveness even during the late stage of sepsis, this agent appears to be a useful adjunct in preventing the deterioration in hemodynamics and cardiovascular function during the progression of polymicrobial sepsis.

Adrenomedullin↗

PubMed2000

Restoration of body temperature to normothermia during resuscitation following trauma-hemorrhage improves the depressed cardiovascular and hepatocellular functions.

HYPOTHESIS: Rewarming the body to 37 degrees C during resuscitation following trauma-hemorrhage has salutary effects on cardiovascular and hepatocellular functions. DESIGN, INTERVENTIONS, AND MAIN OUTCOME MEASURES: Male rats underwent laparotomy (trauma induced) and were then bled to and maintained at a mean arterial pressure of 40 mm Hg until 40% of the maximum shed blood volume was returned in the form of Ringer lactate solution. Rats were exposed to ambient temperature and allowed to become hypothermic during hemorrhage. The animals were then resuscitated with 4 times the volume of shed blood with Ringer lactate solution for 60 minutes. In 1 group, the body temperature was rewarmed to 37 degrees C during resuscitation. In another group, the body temperature was maintained at hypothermia (32 degrees C) for 4 hours after resuscitation. In an additional group, the body temperature was kept at 37 degrees C during hemorrhage and resuscitation. At 4 hours after resuscitation, the rats were returned to a room with ambient temperature. Various in vivo heart performance variables (maximal rate of pressure increase and decrease), cardiac output, hepatocellular function, and plasma IL-6 level were determined at 24 hours after resuscitation. RESULTS: Either maintenance of normothermia during hemorrhage or prolonged hypothermia following resuscitation had deleterious effects on cardiovascular variables and hepatocellular function and up-regulated plasma IL-6 levels. In contrast, rewarming the body to 37 degrees C during resuscitation improved cardiac contractility, cardiac output, and hepatocellular function and reduced plasma IL-6 level. CONCLUSION: Since rewarming the body temperature to normothermia during resuscitation improved depressed cardiovascular and hepatocellular functions, this should be considered as a useful adjunct to fluid resuscitation after trauma-hemorrhage.

Animals↗

PubMed2000

Plasma alpha-glutathione S-transferase: a sensitive indicator of hepatocellular damage during polymicrobial sepsis.

HYPOTHESIS: Since studies have found the liver enzyme alpha-glutathione S-transferase (alphaGST) to be a marker of hepatic injury after hemorrhagic shock, alphaGST also may serve as a sensitive indicator of hepatocellular damage during the early stage of polymicrobial sepsis. DESIGN, INTERVENTIONS, AND MAIN OUTCOME MEASURES: Male adult rats were subjected to the cecal ligation and puncture (CLP) model of polymicrobial sepsis or sham operation, followed by fluid resuscitation with isotonic sodium chloride solution. Systemic blood samples were taken at 2, 5, 10, or 20 hours after CLP or sham operation. Plasma levels of alphaGST and lactate were determined using an enzyme immunoassay and enzymatic assay, respectively. Additional animals were examined for morphologic alterations in liver ultrastructure of septic animals using electron microscopy. RESULTS: A similar level of alphaGST (mean +/- SEM, 30.5 +/- 3.5 microg/L) was found in the sham group at all measured time points. Although plasma levels of alphaGST did not change at 2 hours after CLP, they were elevated by 249% at 5 hours after the onset of sepsis and continued to increase throughout the septic course. Plasma lactate levels were significantly increased only at 20 hours after CLP (P<.001). Previous studies have shown that liver transaminase levels did not increase at 5 hours, but at 10 and 20 hours after CLP. In addition, electron microscopy revealed structural changes in hepatocyte morphology at 5 and 20 hours after CLP that were indicative of hepatocellular injury. CONCLUSION: Since plasma alphaGST levels increased earlier than plasma lactate and liver transaminase levels, alphaGST may be a more sensitive indicator of early liver injury and should be used in monitoring hepatocellular damage during the progression of sepsis.

Animals↗

PubMed2000

Mechanisms of the salutary effects of dehydroepiandrosterone after trauma-hemorrhage: direct or indirect effects on cardiac and hepatocellular functions?

BACKGROUND: Dehydroepiandrosterone (DHEA) is the most abundant adrenal hormone in man and has been shown to improve immune functions after trauma-hemorrhage. However, it remains unknown whether this agent has any salutary effects on the depressed organ functions under such conditions. HYPOTHESIS: Administration of DHEA after trauma-hemorrhage attenuates depressed cardiac and hepatocellular functions, and beneficial effects are mediated via the estrogen receptors. DESIGN, INTERVENTIONS, AND MAIN OUTCOME MEASURES: Male rats underwent laparotomy and were then bled to and maintained at a mean arterial pressure of 40 mm Hg until 40% of the maximal bleed-out volume was returned in the form of Ringer lactate (RL) solution. The animals were then resuscitated with 4 times the maximum bleed-out volume with RL for 60 minutes. Subcutaneous administration of DHEA (30 mg/kg of body weight) or vehicle occurred after resuscitation. At 24 hours after resuscitation, cardiac output was measured by a dye-dilution technique. Hepatocellular function, ie, the maximum velocity of indocyanine green clearance (Vmax) and the efficiency of the active transport (Km), was determined using an in vivo hemoreflectometer. Plasma levels of DHEA, sex hormone binding globulin, 17beta-estradiol, and testosterone were also determined. Moreover, additional groups of animals received a high-affinity estrogen receptor antagonist (ICI 182,780) with or without DHEA treatment. RESULTS: Cardiac output decreased by 12.9% at 24 hours after trauma-hemorrhage; however, it was similar to shams in DHEA-treated animals. Moreover, hepatocellular function was significantly depressed after hemorrhage (Vmax, -74.4%; Km, -62.3%), whereas DHEA treatment restored those values to sham levels. Plasma levels of 17beta-estradiol and testosterone were not significantly altered in animals receiving DHEA. The hemorrhage group treated with DHEA and ICI 182,780 showed markedly depressed cardiac and hepatocellular functions. CONCLUSIONS: Since DHEA treatment after trauma-hemorrhage restored the depressed cardiac and hepatocellular functions, it appears that DHEA is a safe and inexpensive adjunct to fluid resuscitation for restoring the depressed cardiac and hepatocellular responses after severe hemorrhagic shock in male subjects. Furthermore, since ICI 182,780 administration with DHEA abolished the salutary effects of DHEA, it appears that these effects on cardiac and hepatocellular functions after trauma-hemorrhage are mediated via the estrogen receptors.

Adjuvants, Immunologic↗

PubMed2000

Do female sex steroids adversely or beneficially affect the depressed immune responses in males after trauma-hemorrhage?

HYPOTHESIS: Administration of female sex steroids in males after trauma-hemorrhage has salutary effects on the depressed immune responses. DESIGN: Randomized laboratory experiment. INTERVENTIONS: Male C3H/HeN mice were subjected to midline laparotomy and hemorrhagic shock (35+/-5 mm Hg for 90 minutes, then resuscitation) or sham operation and received subcutaneous 17beta-estradiol (40 microg/kg body weight) or corn oil vehicle at the beginning of resuscitation. MAIN OUTCOME MEASURES: At 24 hours after hemorrhage, the animals were killed and plasma 17beta-estradiol and IL-6, splenocyte interleukin (IL) 2, IL-3, and IL-10 production as well as splenic and peritoneal macrophage IL-1beta, IL-10, and IL-6 release were measured. RESULTS: Splenocyte IL-2 and IL-3 release were significantly depressed after hemorrhage in vehicle-treated mice (P<.05, analysis of variance). Treatment with 17beta-estradiol after hemorrhage led to the restoration of splenocyte IL-2 and IL-3 release. The depressed proinflammatory cytokine (IL-1 and IL-6) release seen in splenic and peritoneal macrophages was restored in the 17beta-estradiol-treated hemorrhage group. In contrast, the sustained release of the anti-inflammatory cytokine IL-10 by splenocytes and splenic and peritoneal macrophages in vehicle-treated mice after hemorrhage was decreased in 17beta-estradiol-treated mice. The increase in circulating IL-6 levels after hemorrhage was significantly attenuated in 17beta-estradiol-treated mice. Although administration of 17beta-estradiol increased plasma 17beta-estradiol levels by approximately 100% in sham as well as hemorrhage groups, improved immune responses were seen only in posthemorrhage 17beta-estradiol-treated mice. There was no adverse effect of 17beta-estradiol treatment in the sham or posthemorrhage groups. CONCLUSION: Since administration of a single dose of 17beta-estradiol in males after trauma-hemorrhage restores the immune functions and decreases circulating levels of IL-6, hormones with estrogenic properties should be considered as safe and novel therapeutic agents for restoring the immune responsiveness in male trauma victims.

Adjuvants, Immunologic↗