Biomedical subjects

I H Chaudry

Publications and source records attributed to I H Chaudry.

At least 19 recordsLinked to original sources

PubMed1998

Increased mucosal B-lymphocyte apoptosis during polymicrobial sepsis is a Fas ligand but not an endotoxin-mediated process.

Sepsis is reported to induce an increase in the rate of apoptosis (Ao), in immature lymphoid cells residing in hematopoietic tissues such as the thymus and bone marrow. Alternatively, secondary lymphoid tissue, such as the spleen exhibit little innate (unstimulated) Ao. However, it is unknown whether or not polymicrobial sepsis has any effects on the frequency of Ao in mucosal lymphoid tissue and what, if any, are the functional consequences of such a change. To assess this, Peyer's patch cells were harvested from C3H/HeN (endotoxin-sensitive) mice killed 12 or 24 hours after the onset of polymicrobial sepsis (cecal ligation and puncture [CLP]). The results indicate that the percentage of cells that were Ao+ as determined by flow cytometry were markedly increased at 24 hours, but not at 12 hours post-CLP. This correlates well with evidence of increased DNA fragmentation as well as histological changes observed both at a light and transmission electron microscopic level of the Peyer's patch Ao. Phenotypically, these changes were restricted to the B220+ (B-cell) population that also exhibited a marked increase of Fas/Apo-1 antigen expression. The functional consequence of this increased apoptosis appears to be associated with the endogenous stimulation (activation) of IgA production by mucosal B lymphocytes and increased nuclear c-Rel expression. Furthermore, we found that Peyer's patch lymphocytes isolated from C3H/HeJ-Faslgld (endotoxin-tolerant/Fas ligand- [FasL] deficient) as opposed to C3H/HeJ (endotoxin-tolerant) inbred mice did not exhibit increased Ao after CLP. These findings indicate that increased B-cell Ao appears to be a FasL-Fas antigen-mediated process, but is not due to endotoxin sensitivity. In conclusion, we speculate that the increased Fas-associated apoptosis detected in mucosal B cells (as opposed to splenic or bone marrow B cells) may be due to increased luminal antigens other than endotoxin, released due to gut barrier integrity breakdown during sepsis.

Animals↗

PubMed1998

Is gut the "motor" for producing hepatocellular dysfunction after trauma and hemorrhagic shock?

BACKGROUND: Although studies suggest that the gut may be the "motor" responsible for producing sepsis and multiple organ failure after injury, it is not known whether enterectomy prior to the onset of hemorrhage alters proinflammatory cytokines TNF and IL-6 and, if so, whether hepatocellular dysfunction and damage are prevented or attenuated under such conditions. MATERIALS AND METHODS: Under methoxyflurane anesthesia, an enterectomy in the rat was performed by excision of the duodenum, jejunum, and ileum. The rats were then bled to and maintained at a mean arterial pressure of 40 mm Hg until 40% of the maximal shed volume was returned in the form of Ringer's lactate. The animals were then resuscitated with four times the volume of shed blood with Ringer's lactate over 1 h. At 1.5 h after the completion of resuscitation, hepatocellular function [i.e., the maximal velocity (Vmax) and transport efficiency (Km) of indocyanine green (ICG) clearance] was assessed by an in vivo ICG clearance technique. Blood samples were taken for the measurement of TNF, IL-6, and liver enzymes (i.e., SGPT and SGOT). Cardiac output and microvascular blood flow were determined by ICG dilution and laser Doppler flowmetry, respectively. RESULTS: The increase in circulating levels of TNF but not IL-6 was prevented by enterectomy prior to hemorrhage. The reduced Vmax and K(m) and elevated SGPT and SGOT following hemorrhage and resuscitation, however, were not significantly affected by prior enterectomy. Moreover, enterectomy before hemorrhage further reduced hepatic perfusion. CONCLUSION: Since enterectomy prior to the onset of hemorrhage does not prevent or attenuate the reduced ICG clearance and elevated liver enzymes despite downregulation of TNF production, it appears that the small intestine does not play a significant role in producing hepatocellular dysfunction and injury following trauma and hemorrhagic shock.

Alanine Transaminase↗

PubMed1998

Gut and liver: the organs responsible for increased nitric oxide production after trauma-hemorrhage and resuscitation.

OBJECTIVE: To determine which organs produce the increased levels of nitric oxide (NO) seen after hemorrhage and resuscitation. ANIMALS AND INTERVENTIONS: Adult male rats underwent laparotomy (ie, trauma induced) and were bled to and maintained at a mean arterial pressure of 40 mm Hg until 40% of the maximum bleedout volume was returned in the form of Ringer lactate. The rats were then resuscitated with Ringer lactate, 4 times the maximum bleedout volume for 1 hour. Sham-operated animals underwent only the surgical procedure. MAIN OUTCOME MEASURES: Plasma levels of nitrate/nitrite (NO3-/NO2-, stable products of NO) were measured by colorimetric assay at the maximum bleedout volume; at the end of hemorrhage; at the end of resuscitation; and 1.5, 4, 8, and 24 hours after resuscitation. In additional rats, the heart, liver, small intestine, kidneys, and spleen were harvested 4 hours after resuscitation for the measurement of NO3-/NO2- levels. Moreover, tissue perfusion was determined in the above-mentioned organs by radioactive microspheres 4 hours after resuscitation in other groups of animals. RESULTS: Plasma levels of NO3-/NO2- were similar to those of sham-operated animals during hemorrhage and at the end of resuscitation. One and a half hours after the end of resuscitation, however, NO production increased significantly. The peak levels of plasma NO3-/NO2- occurred at 4 hours, and the levels remained elevated even 24 hours after resuscitation. Tissue NO3-/NO2- levels were significantly increased in the liver, small intestine, and spleen 4 hours after resuscitation. In contrast, the levels of NO3-/NO2- were similar to those of sham-operated animals in the heart and kidneys at all times. Blood flow in the heart was maintained after hemorrhage, whereas hepatic, intestinal, splenic, and renal perfusion decreased significantly. CONCLUSIONS: The gut and liver seem to be the sites responsible for the increased NO production seen after trauma and hemorrhage. The overproduction of NO is most likely caused by up-regulation of inducible NO synthase. Thus, attempts to reduce NO production using specific inhibitors for inducible NO synthase might be helpful for improving hepatic and intestinal functions after trauma and hemorrhagic shock.

Animals↗

PubMed1998

Does hepatocellular injury in sepsis involve apoptosis?

Apoptosis (AO) is a process by which cells typically undergo a form of nonnecrotic cellular suicide. AO normally allows the host to selectively delete cells from a given tissue site without producing bystander injury associated with necrosis. However, inappropriate induction of AO has been associated with a variety of acute as well as chronic pathological states and may contribute to the therapeutic nonresponsiveness frequently encountered in the septic animal/patient's organ function. In this respect, while AO has been demonstrated in a variety of immune cell tissues of septic animals it is unclear if it is present in the septic liver. Therefore, it was the aim of our study to determine if AO is evident in hepatocytes of polymicrobial septic animals. To assess this, C3H/HeN male mice were subjected to polymicrobial sepsis (cecal ligation and puncture) or sham- CLP (Sham). Hepatocytes were then harvested at 4 h (early hyperdynamic phase) or 24 h (late hypodynamic state) later, and indices of AO were assessed [cell cycle analysis of Annexin V/propidium iodide (PI) staining for flow cytometric analysis, DNA extracted, and cell death ELISA]. Plasma glutamic pyruvic transaminase (GPT) was also colorimetrically assessed as well as total viable cell yield as an index of hepatocellular necrosis. The results indicate that indices of hepatocellular AO, as determined by cell cycle analysis and cell death ELISA, were markedly increased in polymicrobial septic mice at 24 h. However, while an increase in DNA fragmentation/degradation could be consistently detected, the pattern was typically faint. Similarly, although there was an increase in Annexin V staining it was not dissociated from that of PI (necrotic index). Alternatively, necrosis (as evidenced by increased GPT levels at both 4 and 24 h) preceded the induction of all the indices of AO. Taken together, these data suggest a role for both necrosis and apoptosis in the evolution of hepatocellular injury encountered in the polymicrobial septic animal/patient which may represent a unique pattern of cell death under such conditions.

Animals↗

PubMed1998

Sepsis induces increased apoptosis in lamina propria mononuclear cells which is associated with altered cytokine gene expression.

Studies indicate that lymphoid tissue (e.g., thymus, bone marrow, and Peyer's patches) shows evidence of increase apoptosis (Ao, a form of nonnecrotic cell death) during sepsis. However, it is not known if mucosal lymphoid tissue, such as lamina propria (LP), also shows evidence of increased Ao and if so, is this associated with functional changes, i.e., cytokine gene expression in the LP. To examine this, male C3H/HeN mice were subjected to cecal ligation and puncture (CLP) and lamina propria mononuclear cells (LPMC) were harvested at 4 h (early sepsis) or 24 h (late sepsis). Alterations in the cell phenotype as well as Ao (Tunel assay) were determined by three-color flow cytometry. Cytokine gene expression was assessed by multiprobe RNase protection assay. Sham LPMC preparations were found to be 34.4 +/- 2.4% B220(+) (B-cells), while 12.4 +/- 2.1% were CD8(+) (cytotoxic T-cells), 22.0 +/- 0.8% were CD4(+) (helper T-cells), and 6.4 +/- 0.7% were F4/80(+) (macrophages). The frequency of B220(+) (9%* upward arrow) and CD8 (6%* upward arrow) populations increased markedly at 4 h after CLP; however, this increase was not seen at 24 h. The percentage of Ao+ in CD8(+), B220(+), and F4/80(+) cells increased markedly at both 4 and 24 h. CD4(+) cells showed a marked increase in Ao only at 24 h after CLP. When LPMC mRNA expression was examined, a significant increase in IL-2, -10, and -15 gene expression was observed only at 24 h but not 4 h after CLP. Thus, the early phenotypic changes associated with increased Ao may be a reflection of localized immune cell activation in early sepsis contributing to the increased cytokine gene expression seen in late sepsis. This localized activation may contribute to gastrointestinal inflammation and/or immune dysfunction in sepsis.

Animals↗

PubMed1998

[Contribution of soft tissue trauma and/or bone fracture to immune suppression after hemorrhagic shock in the animal experiment].

Bone fracture, soft-tissue trauma and hemorrhagic shock are frequent complications in trauma patients, and these patients are known to be immunocompromised. Nonetheless, it is difficult to differentiate the effect of soft-tissue trauma plus hemorrhage from that of bone fracture and hemorrhage on host immune function in the clinical setting. To determine this experimentally, closed bone fracture (right lower leg) and/or soft-tissue trauma (2.5 cm midline laparotomy) were induced prior to hemorrhagic shock (mean arterial BP of 35 +/- 5 mm Hg for 90 min) in male C3H/HeN mice. All animals were killed at 72 h after initiation of the experiment and the spleens were collected aseptically. More significant depression of splenocyte IL-2 and IL-3 release occurred with the combined insult than after bony injury or tissue trauma alone with hemorrhage. The present study suggests that different traumatic insults, i.e. bone fracture as well as soft-tissue trauma in conjunction with hemorrhagic shock, produce comparable depression of host immune function. Moreover, combination of closed bone fracture and soft-tissue trauma prior to hemorrhagic shock leads to even more compromised immunity. This indicates that different mechanisms of immune depression may be involved following soft-tissue trauma or bony injury coupled with hemorrhage. The markedly depressed immune function following bony injury, soft-tissue trauma and hemorrhagic shock may contribute to the increased susceptibility of severely injured patients to sepsis and the ensuing multiple organ failure in the clinical situation.

Animals↗

PubMed1998

Chronic resuscitation after trauma-hemorrhage and acute fluid replacement improves hepatocellular function and cardiac output.

OBJECTIVE: To determine whether prolonged (chronic) resuscitation has any beneficial effects on cardiac output and hepatocellular function after trauma-hemorrhage and acute fluid replacement. BACKGROUND DATA: Acute fluid resuscitation after trauma-hemorrhage restores but does not maintain the depressed hepatocellular function and cardiac output. METHODS: Male Sprague-Dawley rats underwent a 5-cm laparotomy (i.e., trauma was induced) and were bled to and maintained at a mean arterial pressure of 40 mmHg until 40% of maximal bleed-out volume was returned in the form of Ringer's lactate (RL). The animals were acutely resuscitated with RL using 4 times the volume of maximum bleed-out over 60 minutes, followed by chronic resuscitation of 0, 5, or 10 mL/kg/hr RL for 20 hours. Hepatocellular function was determined by an in vivo indocyanine green clearance technique. Hepatic microvascular blood flow was assessed by laser Doppler flowmetry. Plasma levels of interleukin-6 (IL-6) were determined by bioassay. RESULTS: Chronic resuscitation with 5 mL/kg/hr RL, but not with 0 or 10 mL/kg/hr RL, restored cardiac output, hepatocellular function, and hepatic microvascular blood flow at 20 hours after hemorrhage. The regimen above also reduced plasma IL-6 levels. CONCLUSION: Because chronic resuscitation with 5 mL/kg/hr RL after trauma-hemorrhage and acute fluid replacement restored hepatocellular function and hepatic microvascular blood flow and decreased plasma levels of IL-6, we propose that chronic fluid resuscitation in addition to acute fluid replacement should be routinely used in experimental studies of trauma-hemorrhage.

Animals↗

PubMed1998

Testosterone: the crucial hormone responsible for depressing myocardial function in males after trauma-hemorrhage.

OBJECTIVE: To determine whether testosterone depletion in males before trauma-hemorrhage has any salutary effects on cardiac performance after hemorrhage and resuscitation. SUMMARY BACKGROUND DATA: Studies indicate that castration of male mice before trauma-hemorrhage prevents the immunodepression seen after hemorrhage and resuscitation. However, the effect of precastration on cardiac performance under such conditions remains unknown. METHODS: Male rats were castrated or sham-castrated 14 days before the experiment. After laparotomy (i.e., induction of trauma), the rats were bled to and maintained at a mean arterial pressure of 40 mm Hg until 40% of the maximal shed volume was returned in the form of Ringer's lactate solution. The animals were then resuscitated with four times the shed blood volume with Ringer's lactate solution over 60 minutes. Heart performance was measured using a left ventricular catheter connected to an in vivo heart performance analyzer. Indices of left ventricular performance (i.e., maximal rate of the pressure increase [+dP/dt(max)] and decrease [-dP/dt(max)) were measured up to 4 hours after trauma, hemorrhagic shock, and resuscitation. RESULTS: In sham-castrated animals, trauma-hemorrhage and resuscitation decreased the in vivo heart performance as evidenced by the reduced values of +dP/dt(max) and -dP/dt(max). Precastrated animals, however, showed significantly higher values of +dP/dt(max) and -dP/dt(max) than sham-castrated animals after trauma-hemorrhage and resuscitation. CONCLUSIONS: Testosterone antagonism in males might be an effective approach for maintaining myocardial function after adverse circulatory conditions. Although testosterone depletion in male trauma victims is neither practical nor advocated, testosterone receptor blockade after trauma may represent a novel and useful adjunct for maintaining normal myocardial performance under those conditions.

Animals↗

PubMed1998

Pentoxifylline increases gut ketogenesis following trauma and hemorrhagic shock.

OBJECTIVES: Although pentoxifylline produces various beneficial effects following adverse circulatory conditions, it is not known whether this agent has any effects on gut lipid metabolism after trauma-hemorrhage and resuscitation. The aim of this study, therefore, was to determine whether or not administration of pentoxifylline after trauma-hemorrhagic shock has any salutary effects on gut ketogenesis. DESIGN: A prospective, controlled animal study. SETTING: A university research laboratory. SUBJECTS: Fifty-six male Sprague-Dawley rats. INTERVENTIONS: Rats underwent a midline laparotomy (i.e., trauma-induced) and were bled to and maintained at a mean arterial pressure of 40 mm Hg until 40% of the shed blood volume was returned in the form of lactated Ringer's solution. The animals were then resuscitated with four times the volume of maximal bleedout with lactated Ringer's solution over 60 mins. Pentoxifylline (50 mg/kg body weight) or an equivalent volume of normal saline was infused intravenously over 100 mins during and after resuscitation. For in vivo lipid loading, one milliliter of olive oil was given intraduodenally on the completion of resuscitation. Blood samples from portal vein and carotid artery, as well as enterocytes from proximal small intestine, were obtained at 1.5 hrs after fat feeding. MEASUREMENTS AND MAIN RESULTS: Mitochondrial fatty acid beta-oxidation enzyme (i.e., palmitoyl-coenzyme A dehydrogenase) activity, as well as portal and arterial plasma beta-hydroxybutyrate values, were determined. Palmitoyl-coenzyme A dehydrogenase activity in villus tip cells and plasma beta-hydroxybutyrate values in portal vein and carotid artery were significantly reduced after trauma-hemorrhage and resuscitation. Pentoxifylline administration, however, significantly increased mitochondrial fatty acid beta-oxidation enzyme activity and portal plasma beta-hydroxybutyrate concentration without significantly affecting arterial concentrations under such conditions. CONCLUSION: Pentoxifylline promotes gut ketogenesis following trauma-hemorrhage and resuscitation.

3-Hydroxybutyric Acid↗

PubMed1998

Metoclopramide: a novel and safe immunomodulating agent for restoring the depressed macrophage immune function after hemorrhage.

BACKGROUND AND OBJECTIVE: Recent studies have shown that administration of the anterior pituitary hormone, prolactin, after hemorrhage restored the depressed immune responses that are observed under those conditions. Because metoclopramide (MCP) is known to increase prolactin secretion and ultimately plasma prolactin levels, we attempted to determine whether administration of metoclopramide after hemorrhage produces any beneficial effects on the depressed splenocyte and peritoneal macrophage immune function after severe hemorrhage. DESIGN, MATERIALS AND METHODS: Mice were bled to and maintained at a mean arterial pressure of 35 mm Hg for 60 minutes, then adequately resuscitated and segregated into two groups. One group received saline vehicle; animals in the other group were treated with metoclopramide (100 microg/100 g body weight, subcutaneously) before resuscitation. Two hours after saline or MCP injection, the animals were killed and macrophage as well as splenocyte cultures established. Plasma corticosterone levels were also measured. RESULTS: The proliferative capacity of the splenocytes as well as their ability to release interleukin (IL)-2 and IL-3 in response to mitogen was markedly improved in animals that had hemorrhaged and that were treated with MCP compared with saline-injected mice. Moreover, the depressed splenic and peritoneal macrophage IL-1 and IL-6 release after hemorrhage was restored with MCP treatment. Furthermore, treatment with MCP prevented the increase in blood corticosterone levels seen after severe hemorrhage. CONCLUSION: These results support the concept that the immunosuppression after hemorrhage may be mediated by hormones from the hypothalamic-pituitary-adrenal axis. Furthermore, MCP may be a useful adjuvant in the treatment of the trauma-hemorrhagic shock-induced immunosuppression.

Animals↗

PubMed1998

Testosterone and/or low estradiol: normally required but harmful immunologically for males after trauma-hemorrhage.

BACKGROUND: Previous studies indicate that after severe hemorrhage, immune functions are markedly depressed in males, whereas females do not show any depression. Although androgen depletion by castration of mice before soft-tissue trauma and hemorrhagic shock prevents the depression of cell-mediated immunity, it remains unknown whether testosterone per se is responsible for producing immune depression. METHODS: Female C3H/HeN mice were pretreated with 5alpha-dihydrotestosterone (DHT) or vehicle for 20 days. The mice then underwent soft-tissue trauma (laparotomy) and hemorrhagic shock (blood pressure 35+/-5 mm Hg for 90 minutes) followed by adequate fluid resuscitation (shed blood and lactated Ringer's solution) or sham operation. Two groups of nontreated male C3H/HeN mice were included as controls: one group was subjected to hemorrhagic shock followed by resuscitation, and the second group underwent only sham operation. At 24 hours after trauma-hemorrhage and resuscitation, animals were killed, macrophages harvested from the peritoneum and spleen, and their ability to release interleukin (IL)-1 and IL-6 was evaluated. Plasma DHT, estradiol, and corticosterone levels were measured by radioimmunoassay. RESULTS: Treatment of female mice with DHT produces a significant increase in DHT levels that was comparable with those seen in nontreated male mice. Alternatively, estradiol levels in female mice were significantly depressed by DHT treatment to levels comparable with those observed in control males. In the vehicle-treated female mice, no depression of the macrophage function was evident after trauma hemorrhage. In contrast, testosterone-treated female mice that had experienced hemorrhage showed significant depression in splenic and peritoneal macrophage IL-1 and IL-6 production, comparable with the values seen in macrophages from male mice that had experienced hemorrhage. CONCLUSIONS: These findings indicate that pretreatment of female mice with DHT depresses macrophage function after trauma-hemorrhage, which mimics the changes seen in normal male mice subjected to trauma-hemorrhage. We propose, therefore, that high testosterone and/or low estradiol levels are responsible for producing the immune depression in male mice after trauma-hemorrhage. Testosterone receptor blocking agents, e.g., flutamide, and/or estradiol administration should thus be useful adjuncts for preventing immune depression in male trauma patients.

Animals↗

PubMed1998

Prolonged immunodepression after trauma and hemorrhagic shock.

BACKGROUND: Although hemorrhage or trauma (laparotomy) alone in mice produces a marked immunosuppression for 3 to 4 days and trauma plus hemorrhage produces immune depression for 5 days after resuscitation, it remains unknown when the immune functions return to normal after trauma-hemorrhage and whether lymphocyte and macrophage functions are similarly affected by trauma-hemorrhage. METHODS: Male C3H/HeN mice underwent either sham operation, trauma (laparotomy), hemorrhagic shock (mean arterial blood pressure of 35 +/- 5 mm Hg for 60 minutes, followed by fluid resuscitation), or trauma plus hemorrhage. Plasma, splenocytes, splenic macrophages, and peritoneal macrophages were harvested at 7 or 10 days after the operation. Plasma and macrophage tumor necrosis factor, interleukin (IL)-6, and splenocyte IL-2 and IL-3 release were determined by bioassay, and splenocyte proliferation was measured by [3H]thymidine incorporation. RESULTS: Splenocyte proliferation, splenocyte lymphokine release, and splenic and peritoneal macrophage cytokine release were still markedly decreased in the trauma-hemorrhage group compared with other groups at 7 days but returned to normal by day 10. Tumor necrosis factor and IL-6 levels, however, were not detectable in plasma of any groups at 7 or 10 days after operation. CONCLUSION: The results indicate that a more severe and prolonged immunodepression occurs after combined trauma and hemorrhage than after trauma or hemorrhage alone.

Animals↗

PubMed1998

Resuscitation after uncontrolled venous hemorrhage: Does increased resuscitation volume improve regional perfusion?

BACKGROUND: Recent studies have questioned the use of aggressive fluid resuscitation after uncontrolled arterial hemorrhage until the bleeding is controlled. However, it remains unknown whether resuscitation after hemorrhage from a venous origin (usually nonaccessible to surgical intervention) has any beneficial or deleterious effects on regional perfusion. The aim of this study, therefore, was to determine whether increased volume of fluid resuscitation after uncontrolled venous hemorrhage improves hemodynamic profile and regional perfusion in various tissues. MATERIALS AND METHODS: After methoxyflurane anesthesia and midline laparotomy, both lumbar veins in the rat were severed, which resulted in lowering the mean arterial blood pressure to approximately 40 mm Hg. This pressure was maintained for 45 minutes by allowing further bleeding from the lumbar veins. The abdominal incision was then closed in layers and the animals received either 0, 10, or 30 mL of lactated Ringer's solution intravenously over a period of 60 minutes. Cardiac output and regional blood flow were determined by radioactive microspheres immediately or at 1.5 hours after the completion of resuscitation. RESULTS: Fluid resuscitation with 10 or 30 mL lactated Ringer's solution increased mean arterial blood pressure and cardiac output immediately after resuscitation compared with the nonresuscitated animals. At both time points, regional perfusion in the heart, kidney and intestines remained significantly decreased compared with the sham values, irrespective of the volume of fluid resuscitation. Moreover, no further improvements in hemodynamics or regional perfusion occurred when volume resuscitation was increased from 10 mL to 30 mL. Total hepatic blood flow, however, increased with 10 mL lactated Ringer's solution compared with the other hemorrhage groups and the increase was evident even at 1.5 hours after resuscitation. CONCLUSIONS: Fluid resuscitation after uncontrolled venous bleeding transiently increased cardiac output and mean arterial blood pressure compared with nonresuscitated animals. Moderate fluid administration, i.e., 10 mL, however, did increase total hepatic blood flow. In contrast, increasing the resuscitation volume to 30 mL did not improve hemodynamic parameters or regional perfusion. Thus moderate instead of no resuscitation or larger volume of resuscitation is recommended in an uncontrolled model of venous hemorrhage.

Aged↗

PubMed1998

Cardiac contractility and structure are not significantly compromised even during the late, hypodynamic stage of sepsis.

Although cardiac function is depressed during endotoxic shock, it remains controversial whether the ventricular contractility and structure are altered during sepsis. To resolve this issue, rats were subjected to polymicrobial sepsis by cecal ligation and puncture (CLP). At 2, 5, and 10 h after CLP (i.e., the early, hyperdynamic stage of sepsis) or 20 h after CLP (the late, hypodynamic stage of sepsis, based on the depressed tissue perfusion), in vivo left ventricular contractility parameters such as maximal rate of the left ventricular pressure increase (+dP/dtmax) and decrease (-dP/dtmax), maximal rate of "pressure-normalized" change in ventricular pressure (dP/dtmax/P), and ventricular peak systemic pressure were determined using a Digi-Med Heart Performance Analyzer. In additional groups of animals, ultrastructure of the cardiac muscle in the left ventricle was examined at 5, 10, or 20 h after CLP, using a transmission electron microscope. The results indicate that +dP/dtmax and dP/dtmax/P increased significantly at 2-10 h after CLP. The values of -dP/dtmax and ventricular peak systemic pressure increased significantly at 2 and 5 h after the onset of sepsis, respectively. These in vivo ventricular contractility parameters, however, were not significantly different from shams at 20 h after CLP. Ultrastructural examination showed that enlarged T-tubules were prominent during the hyperdynamic stage of sepsis, which was correlated with the increased cardiac contractility. Although focal and moderate hypertrophy as well as expanded intermyocyte junctions could be observed occasionally, myocardial cells did not appear to be compromised at 20 h after CLP. Thus, the transition from the hyperdynamic to hypodynamic circulation during sepsis does not appear to be due to any depression in myocardial function because cardiac contractility and structure are not compromised even during the late, hypodynamic stage of sepsis. However, further investigation is required to determine whether cardiac function is depressed at the terminal stage of polymicrobial sepsis.

Animals↗

PubMed1998

Trauma-hemorrhage activates signal transduction pathways in mouse splenic T cells.

Severe impairment in the functions of immune-competent cells has been observed following trauma and hemorrhage. Inappropriate release of cytokines during trauma and hemorrhagic shock disrupt T lymphocyte functions and enable cells to activate genes whose products are detrimental for maintaining a much-needed humoral and cell-mediated immunity. The intracellular events for gene activation are mediated by cytoplasmic transcription factors present as nascent (signal transducer and activator of transcription 1 (STAT 1)) or as a complex (nuclear factor kappaB (NF-kappaB)). Receptor-initiated phosphorylation activates these transcription factors prior to their nuclear translocation and binding to cognate DNA sequences. Because T cell functions are critical to efficient functioning of the immune system, we investigated whether expression of transcription factors, STAT1 and NF-kappaB, is perturbed in splenic T cells following trauma and hemorrhage. To study this, enriched T cells harvested from spleens (pooled from three or four mice per group) of sham, trauma (consisting of midline laparotomy), sham+trauma, hemorrhage (blood pressure maintained at approximately 30 mmHg for 90 min followed by adequate fluid resuscitation), and trauma+hemorrhage groups at 16-18 h after surgical procedure were probed for signal expressions in the presence and absence of interferon-gamma using electrophoretic mobility shift and Western immunoblot assay procedures. Hemorrhage with or without trauma induced activation of Janus kinase 1, STAT1, and NF-kappaB in T cells. Stimulation of T cells with interferon-gamma led to activation of all these signals in all groups including experimental controls. STAT1 activation was accompanied by Janus kinase 1 phosphorylation, whereas NF-kappaB activation was mediated by phosphorylation and rapid degradation of IkappaBalpha. These studies demonstrate that hemorrhagic shock, with or without laparotomy, is sufficient to induce activation of transcription factors in splenic T cells. Thus, attempts to prevent the activation of transcription factors following hemorrhage by pharmacologic means might be helpful for maintaining cell-mediated immunity under these conditions.

Animals↗

PubMed1998

Testosterone: the culprit for producing splenocyte immune depression after trauma hemorrhage.

Studies indicate that, whereas immune functions in males are depressed, they are enhanced in females after trauma hemorrhage. Moreover, castration of male mice (i.e., androgen depletion) before trauma hemorrhage prevented the depression of cell-mediated immunity. Nonetheless, it remains unknown whether or not testosterone per se is responsible for producing the immune depression. To study this, female C3H/HeN mice (n = 7 animals/group) were pretreated with 5-dihydrotestosterone (DHT) or vehicle for 19 days, then subjected to laparotomy (e.g., trauma) and hemorrhagic shock (blood pressure 35 +/- 5 mmHg for 90 min) followed by fluid resuscitation or sham operation. Nontreated males underwent either trauma hemorrhage or sham operation. Twenty-four hours thereafter, splenocyte immune functions as well as plasma DHT, estradiol, and corticosterone levels were measured. DHT-pretreated females had significantly (P < 0.05) increased DHT levels, comparable to those seen in males. Conversely, estradiol levels in such females were similar to control males. Splenocyte proliferation as well as interleukin-2 and interleukin-3 release were not depressed in vehicle-treated females, whereas it was in DHT-treated females after trauma hemorrhage, comparable to hemorrhaged males. Thus high testosterone and/or low estradiol levels appear to be responsible for producing splenocyte immune depression in males after trauma hemorrhage. Agents that block testosterone receptors or increase estradiol levels may therefore be helpful in improving depressed immune functions in male trauma patients.

Animals↗

PubMed1997

Administration of ATP-MgCl2 following hemorrhage and resuscitation increases hepatic phosphoenolpyruvate carboxykinase and decreases pyruvate kinase activities.

Since administration of ATP-MgCl2 following trauma and hemorrhagic shock improves tissue perfusion as well as cell and organ function, the aim of this study was to determine whether this agent has any salutary effects on the hepatic rate-controlling enzymes specific for gluconeogenesis, such as phosphoenolpyruvate carboxykinase (PEPCK), and for glycolysis, such as pyruvate kinase (PK), under such conditions. To study this, rats underwent a 5-cm midline laparotomy (i.e., trauma-induced) and were bled to and maintained at a mean arterial pressure of 40 mm Hg until 40% of maximum bleed out volume was returned in the form of Ringer's lactate (RL). The animals were then resuscitated with 3 times the volume of shed blood with RL over 45 min, followed by 2 times RL with ATP-MgCl2 (50 micromol/kg body wt.) or an equivalent volume of normal saline over 95 min. Hepatic PEPCK, PK and glucokinase activities were determined 4 h after the completion of resuscitation. The mRNA levels of PEPCK and PK in the isolated hepatocytes were determined by Northern blot analysis. The results indicate that glucokinase activity was not significantly altered after hemorrhage, irrespective of ATP-MgCl2 treatment. Although the mRNA levels of PEPCK were similar in all groups, PEPCK activity decreased significantly after hemorrhage. ATP-MgCl2 treatment, however, restored PEPCK activity. Hemorrhage resulted in an increase in PK activity and its mRNA. ATP-MgCl2 treatment significantly decreased PK activity and the mRNA. Thus, up-regulation of the gluconeogenic enzyme, PEPCK, and down-regulation of the glycolytic enzyme, PK, by ATP-MgCl2 may be responsible, in part, for the beneficial effects of this agent following trauma-hemorrhage and resuscitation.

Adenosine Triphosphate↗

PubMed1997

Severe hypoxemia in the absence of blood loss depresses hepatocellular function and up-regulates IL-6 and PGE2.

Although hepatocellular function is depressed early after trauma and hemorrhage (which are associated with low flow conditions and tissue hypoxemia), it remains unknown whether hypoxemia without blood loss, produces hepatocellular dysfunction and, if so, whether IL-6 and PGE2 are associated with this dysfunction. To study this, rats were placed in a plastic box which was flushed with a gas mixture containing 6.3% O2:93.7% N2 or room air for 60 min, followed by their return to room air. At 0 and 4 h after hypoxemia, hepatocellular function (i.e., maximum velocity of indocyanine green clearance (Vmax) and the efficiency of the transport (Km)) was measured using an in vivo hemoreflectometer. Cardiac output was assessed by dye dilution technique. Tissue microvascular blood flow was determined by laser Doppler flowmetry. Plasma IL-6 and PGE2 were measured by bioassay and radioimmunoassay, respectively. The results indicate that hypoxemia produced a depression in hepatocellular function (i.e., decreased Vmax by 44-50% and Km by 55-68%) despite stable cardiac output and hepatic microcirculation at 0 and 4 h after hypoxemia. Moreover, hypoxemia resulted in a significant increase in plasma IL-6 (by 372%-389%) as well as PGE2 (by 38% at 0 h post-hypoxemia). Thus, hypoxemia observed after trauma and hemorrhagic shock appears to be responsible for producing hepatocellular dysfunction possibly through the up-regulation of IL-6 and PGE2. In view of this, long-lasting hypoxemia in trauma victims should be avoided, perhaps by early intubation and ventilation so that the potential additional proinflammatory cytokine and PGE2 release can be prevented.

Animals↗