Biomedical subjects

Hasan B Alam

Publications and source records attributed to Hasan B Alam.

At least 37 records · Page 2Linked to original sources

PubMed2005

Energy substrate-supplemented resuscitation affects brain monocarboxylate transporter levels and gliosis in a rat model of hemorrhagic shock.

BACKGROUND: Monocarboxylate (MC)-supplemented resuscitation has been shown to attenuate cellular injury after hemorrhagic shock. However, little is known about its effect on the central nervous system. The brain can use MCs such as lactate, pyruvate, and beta-hydroxybutyrate as energy substrates. The transit of MCs into the central nervous system is facilitated by the monocarboxylate transporters (MCTs), and their blockage can exacerbate neuronal damage. We examined the expression of MCT1 and markers specific for activation of astroglia and microglia in the brains of rats subjected to hemorrhagic shock and resuscitation. The hypothesis was that resuscitation with MC-based fluids would be accompanied by MCT1 up-regulation and glial response. METHODS: Rats (n = 30) were subjected to volume-controlled hemorrhage. Test groups included: sham, no resuscitation, resuscitation with normal saline, resuscitation with racemic lactated Ringer's solution, resuscitation with pyruvate Ringer's solution, and resuscitation with beta-hydroxybutyrate-containing ketone Ringer's solution. Plasma levels of MC were measured serially. The brains were investigated using GFAP, CD11b, CD43, MCT1, and GLUT1 immunohistochemistry. RESULTS: Rats resuscitated with MC-containing fluids had increased levels of MCT1 in brain endothelial cells and neuropil compared with sham rats. Enhanced staining was localized to the choroid plexus, astrocytic end feet, and white matter structures. None of the resuscitation treatment induced astrocytic hyperplasia, and pyruvate Ringer's solution and ketone Ringer's solution resuscitation led to hypertrophy of astrocytes. CONCLUSION: In hemorrhagic shock, resuscitation with MC-based fluids increased brain MCT1 level and led to activation of astrocytes. Enhanced MC trafficking could be an essential route for energy supply to neurons under adverse circulatory conditions.

Animals↗

PubMed2005

Hemorrhage control in the battlefield: role of new hemostatic agents.

Uncontrolled hemorrhage is the leading cause of preventable combat-related deaths. The vast majority of these deaths occur in the field before the injured can be transported to a treatment facility. Early control of hemorrhage remains the most effective strategy for treating combat casualties. A number of hemostatic agents have recently been deployed to the warfront that can be used to arrest bleeding before surgical control of the source. The purpose of this article is to summarize the background information regarding these hemostatic agents, indications and rationale for their use, and characteristics of these products that may impact effectiveness.

Acetylglucosamine↗

PubMed2005

Administration of recombinant interleukin-11 improves the hemodynamic functions and decreases third space fluid loss in a porcine model of hemorrhagic shock and resuscitation.

We have previously demonstrated that the administration of recombinant human interleukin-11 (rhIL-11) during resuscitation improves the blood pressure in a rodent model of hemorrhagic shock. The purpose of this study was to determine whether the effects of rhIL-11 could be reproduced in a large animal model and to elucidate the impact of rhIL-11 administration on the intravascular volume status and the degree of third space fluid loss after resuscitation. A 40% blood volume hemorrhage was induced in swine (n = 45, weight of 25-35 kg) followed by a 1-h shock period and resuscitation with 0.9% sodium chloride (three times the shed blood volume). The animals were randomized to receive sham hemorrhage (group I, sham); sham hemorrhage and 50 microg/kg rhIL-11 (group II, sham + IL-11); no drug (group III, saline); or 50 microg/kg rhIL-11 (group IV, IL-11). Blood and urine samples were obtained and analyzed at baseline, at the end of hemorrhaging, and thereafter once every hour. The pleural and peritoneal effusions were precisely quantified by using clinically accepted criteria. The mean arterial pressure (MAP) was higher postresuscitation (PR) in groups I, II, and IV (71.4 +/- 7.5 mmHg, 71.0 +/- 8.9 mmHg, and 72.9 +/- 12.3 mmHg, respectively) than in group III (59.9 +/- 10.9 mmHg), and the cardiac output of PR was higher in group IV (3.46 +/- 0.56 L/min) than in group III (2.99 +/- 0.62 L/min; P < 0.01). The difference in MAP between groups I and II became statistically significant at 40 min after rhIL-11 injection and such a difference persisted for 90 min. After resuscitation, the urine output was higher, and the urine specific gravity and third space fluid loss were lower in group IV (1434 +/- 325 mL and 1.0035, 82 +/- 21 mL) than in group III (958 +/- 390 mL and 1.0053, 125 +/- 32 mL; P < 0.05). In a porcine model of hemorrhagic shock, the administration of rhIL-11 at the start of resuscitation significantly improved the cardiac output and blood pressure. This strategy also significantly reduced the extent of third space fluid losses while also having a favorable impact on the intravascular volume status as evidenced by the improved urine output.

Animals↗

PubMed2004

Effect of different resuscitation strategies on neutrophil activation in a swine model of hemorrhagic shock.

UNLABELLED: Activated neutrophils play a pivotal role in resuscitation injury. The strategies used for resuscitation (types of fluids and methods of administration) can affect the degree of neutrophil activation. The aim of this study was to test the commonly available resuscitation fluids in a large animal model of hemorrhagic shock to determine the strategy associated with the least degree of neutrophil activation. METHODS: Female swine (n=63, weight 45-60 kg) were anesthetized using isoflurane and catheters were placed for hemodynamic monitoring. After 120 min, they were subjected to a volume controlled hemorrhage (28 ml/kg) over 15 min, kept in shock for 60 min, and then resuscitated. The resuscitation groups were as follows: (1) anesthesia only (n=5); (2) hemorrhage, sham resuscitation (n=5); (3) LR-fast rate 3x blood loss (n=6); (4) LR slow rate-3x blood loss (n=6); (5) LR low volume-1x blood loss (n=6); (6) Dextran 40-1x blood loss (n=6); (7) 6% hetastarch-1x blood loss (n=6); (8) 5% albumin-1x blood loss (n=6); (9) 25% albumin-1/5x blood loss (n=6); (10) whole blood resuscitation-1x blood loss (n=6); (11) 7.5% hypertonic saline (HTS)-0.3x blood loss (n=5). Resuscitation fluids were infused over 1 h in all groups except group 4 (LR slow rate, which was over 3 h). Animals were observed for 180 min following the resuscitation period. Neutrophil oxidative burst activity was determined in whole blood using flow cytometery. RESULTS: Animals resuscitated with dextran and hetastarch showed significantly (P<0.05) higher neutrophil burst activity. Resuscitation with LR also caused neutrophil activation (P<0.05), and the highest degree of activation was seen when a large volume of LR was given at a fast rate (group 8). However, all LR infusion protocols were associated with significant neutrophil activation compared with anesthesia (group 1) or sham resuscitation (group 2). No significant activation was seen in the animals resuscitated with albumin or fresh whole blood. CONCLUSION: Artificial colloids and LR (independent of rate or volume of infusion) caused significant neutrophil activation, which was not seen with albumin and whole blood resuscitation. These findings suggest that the type of resuscitation fluid and method of infusion can influence neutrophil function.

Albumins↗

PubMed2004

Application of a zeolite hemostatic agent achieves 100% survival in a lethal model of complex groin injury in Swine.

BACKGROUND: Techniques for better hemorrhage control after injury could change outcome. We have previously shown that a zeolite mineral hemostatic agent (ZH) can control aggressive bleeding through adsorption of water, which is an exothermic process. Increasing the residual moisture content (RM) of ZH can theoretically decrease heat generation, but its effect on the hemostatic properties is unknown. We tested ZH with increasing RM against controls and other hemostatic agents in a swine model of battlefield injury. METHODS: A complex groin injury was created in 72 swine (37 +/- 0.8 kg). This included semitransection of the proximal thigh and complete division of the femoral artery and vein. After 3 minutes, the animals were randomized to 1 of 10 groups: group 1, no dressing (ND); group 2, standard dressing (SD); group 3, SD + 3.5 oz ZH with 1% RM (1% ZH); group 4, SD + 3.5 oz ZH with 4% RM (4% ZH); group 5, SD + 2 oz ZH with 1% RM (1% ZH 2oz); group 6, SD + 3.5 oz ZH with 8% RM (8% ZH); group 7, SD + chitosan-based hemostat, HemCon (HC); group 8, SD + 3.5 oz nonzeolite mineral hemostat, Quick Relief (NZH); group 9, SD + bovine clotting factors-based hemostat, Fast Act (FA); and group 10, SD + 30 g of starch-based hemostat, TraumaDex (TDex). Resuscitation (500 mL of Hespan over 30 minutes) was started 15 minutes after injury and hemodynamic monitoring was performed for 180 minutes. Primary endpoints were survival for 180 minutes and blood loss. In addition, maximum wound temperatures were recorded, and histologic damage to artery, vein, nerve, and muscle was documented. RESULTS: Use of 1% ZH decreased blood loss and reduced mortality to 0% (p < 0.05). Increasing the RM adversely affected efficacy without any significant decrease in wound temperatures. Minimal histologic tissue damage was seen with ZH independent of the percentage of RM. CONCLUSION: The use of zeolite hemostatic agent (1% residual moisture, 3.5 oz) can control hemorrhage and dramatically reduce mortality from a lethal groin wound.

Adsorption↗

PubMed2004

D-lactate increases pulmonary apoptosis by restricting phosphorylation of bad and eNOS in a rat model of hemorrhagic shock.

UNLABELLED: Resuscitation with racemic lactated Ringer's solution (containing equal amounts of D and L isomers of lactate) has been shown to induce pulmonary apoptosis. Substitution of DL-isomer lactate with ketone bodies (beta-hydroxybutyrate, BHB), sodium pyruvate, or L-isomer of lactate decrease this injury without changing the energy status of the tissues or the expression of apoptotic genes. These modified solutions however alter the function of apoptotic proteins through an unknown mechanism. We postulated that DL-LR induces apoptosis by restricting the phosphorylation of key apoptotic proteins. METHODS: Male Sprague Dawley rats (n = 30, 5/group) were subjected to a three stage, volume-controlled hemorrhage and randomized to the following groups. 1) No hemorrhage (Sham); 2) Hemorrhage and no resuscitation (NR); 3) Resuscitation with 3x shed blood volume of racemic LR (DL-LR); 4) Resuscitation with 3x shed blood volume of LR containing only the L-isomer of lactate (L-LR); 5) Resuscitation with 3s shed blood volume of pyruvate Ringer's (PR); 6) Resuscitation with 3s shed blood volume of ketone Ringer's (KR). The modified Ringer's solutions were identical to racemic LR except for equimolar substitution of DL-lactate for L-lactate, pyruvate and BHB respectively. Lung tissue was obtained 2 hours later and subjected to Western Blotting. The levels of Akt, Bad, and eNOS (total and phosphorylated) proteins were measured. Finally, the expression of gene coding for protein 14-3-3 was measured using RT-PCR. RESULTS: Resuscitation with DL-LR caused a significant (p < 0.05) increase in the total Bad and a decrease in phosphorylated Bad protein expression in the lung. It also caused an increase in the phosphorylated Akt levels and a decrease in gene coding for protein 14-3-3. These changes were consistent with signaling imbalances that favor apoptosis. Modified LR solutions, on the other hand, did not cause these alterations. Phosphorylation pattern of eNOS supported the involvement of PI3K/Akt pathway in this process. CONCLUSION: Racemic lactate plays a role in the induction of pulmonary apoptosis by restricting phosphorylation of Bad and eNOS proteins.

14-3-3 Proteins↗

PubMed2004

The rate of induction of hypothermic arrest determines the outcome in a Swine model of lethal hemorrhage.

BACKGROUND: Lethal injuries can be surgically repaired under asanguineous hypothermic condition (suspended animation) with excellent outcome. However, the optimal rate for the induction of hypothermic metabolic arrest following uncontrolled lethal hemorrhage (ULH) is unknown. METHODS: ULH was induced in 32 female swine (80-120 lbs) by creating an iliac artery and vein injury, followed 30 minutes later by laceration of the descending thoracic aorta. Through a left thoracotomy approach, total body hypothermic hyperkalemic metabolic arrest was induced by infusing organ preservation fluids into the aorta. Experimental groups were: normothermic controls (no cooling, NC), or hypothermia induced at a rate of 0.5 degrees C/min (slow, SC), 1 degrees C/min (medium, MC), or 2 degrees C/min (fast, FC). Vascular injuries were repaired during the 60 minutes of profound (10 degrees C) hypothermic arrest. Hyperkalemia was reversed by hypokalemic fluid exchange, and blood was infused for resuscitation during the re-warming (0.5 degrees C/ minute) period. The survivors were monitored for 6 weeks. RESULTS: The 6 week survival rates were 0% (NC), 37.5% (SC), 62.5% (MC), and 87.5% (FC) respectively (p < 0.05 MC&FC versus NC). All of the surviving hypothermic arrest animals were neurologically intact and displayed no long term organ dysfunction. CONCLUSION: Hypothermic metabolic arrest can be used to maintain viability of key organs during repair of lethal injuries. Survival is influenced by the rate of cooling with the best outcome following rapid induction of hypothermia.

Animals↗

PubMed2003

cDNA profiling in leukocytes exposed to hypertonic resuscitation fluids.

BACKGROUND: Resuscitative fluids induce distinctive changes in leukocyte functions: incubation with colloid Dextran increases production of reactive oxygen species and adhesion, whereas exposure to hypertonic saline (HTS) inhibits "oxidative burst" and phagocytosis. In hypertonic saline Dextran (HTD), the hypertonic component determines the leukocyte functional behavior and subsequently activation response. We investigated whether leukocyte gene expression is analogously affected. METHODS: Whole blood from eight volunteers was diluted and incubated for 30 min at 37(o)C in 6.0% Dextran-70, 7.5% HTS, and 7.5% HTD. Total leukocyte RNA was extracted and used to synthesize biotinylated cDNA probes. Each probe was individually hybridized to a cDNA array to simultaneously measure the expression of 23 genes involved in inflammation, cell migration, and apoptosis. RESULTS: Leukocytes incubated with Dextran-70 demonstrated greater than a 6-fold (p < 0.05) increase in the expression of interleukin-8, growth-regulated oncogenes alpha and beta, L-selectin, superoxide dismutase, tumor necrosis factor-alpha (TNF-alpha), and mitogen-activated protein kinase 3. The expression profile induced by HTS was not significantly different from that of unstimulated blood, except for prominent induction of only three genes. HTD attenuated the expression of Dextran-70 upregulated genes, although the level of their expression was higher than in HTS-treated leukocytes. CONCLUSIONS: Hypertonic resuscitation fluids diminish the expression of immune activation-associated genes. Hypertonic component of HTD determines the leukocyte gene expression profile.

Adult↗

PubMed2003

Ketone and pyruvate Ringer's solutions decrease pulmonary apoptosis in a rat model of severe hemorrhagic shock and resuscitation.

BACKGROUND: Resuscitation fluids containing beta-hydroxybutyrate (BHB) have been shown to decrease cellular injury after hemorrhagic shock and resuscitation through an unknown mechanism. We tested whether this effect was related to BHB-induced metabolic modulations. METHODS: Male Sprague Dawley rats (n=30) were subjected to volume-controlled hemorrhage (27 mL/kg during 10 minutes followed by 75 minutes of shock during which another 8 mL/kg of blood was withdrawn). Experimental groups included the following: (1) sham, (2) no resuscitation (NR), (3) racemic lactated Ringer's (DL-LR) solution, (4) LR containing L-isomer only (L-LR), (5) ketone Ringer's solution with lactate substituted by BHB (KR), and (6) pyruvate Ringer's solution with lactate substituted by pyruvate (PR). The resuscitation fluids were infused during 45 minutes simultaneously with additional hemorrhage of 8 mL/kg. Hemodynamic and physiologic parameters and the plasma levels of BHB were serially measured. The animals were killed 2 hours after resuscitation, and tissues were frozen instantaneously for cellular adenylate extraction and adenosine triphosphate (ATP) and adenosine diphosphate analysis. Pulmonary apoptosis was studied using Western blotting, immunohistochemistry, and reverse transcriptase-polymerase chain reaction. Expression of enzymes involved in ketogenesis and ketolysis was analyzed by reverse transcriptase-polymerase chain reaction. RESULTS: NR and resuscitation with DL-LR increased the expression of apoptotic markers, whereas resuscitation with KR and PR significantly decreased the expression of apoptotic markers in rat lungs. Resuscitation with KR was followed by a profound increase in plasma BHB levels; however, the expression levels of ketolytic enzymes were essentially unaffected. KR infusion did not induce significant improvements in tissue ATP levels. CONCLUSIONS: Resuscitation with KR and PR protects against pulmonary apoptosis without improving tissue ATP content. Therefore, metabolic modulation is unlikely to be the major mechanism by which BHB exerts its protective effects during reperfusion.

3-Hydroxybutyric Acid↗

PubMed2003

Human polymorphonuclear cell death after exposure to resuscitation fluids in vitro: apoptosis versus necrosis.

BACKGROUND: Resuscitation fluids can have variable effects on key functions of circulating polymorphonuclear neutrophils (PMNs) such as oxidative burst, chemotaxis, and bacterial killing. We hypothesized that choice of resuscitation fluids will also affect the rate of PMN apoptosis. To test this, we studied cellular death (apoptosis and necrosis) in human PMNs after brief exposure to different hypertonic and isotonic fluids. METHODS: Blood from 12 volunteers was incubated for 1 hour at 37 degrees C in normal saline, 6.0% dextran-70, 7.5% hypertonic saline, and 7.5% hypertonic saline with 6% dextran-70. Isolated PMNs were double labeled with fluorescein-Annexin V and propidium iodide, and apoptosis and necrosis were measured using flow cytometry. Caspase activation was also detected with flow cytometry using pan-caspase inhibitor (carbobenzoxy-valyl-alanyl-aspartyl-fluoromethylketone) in non-isolated whole blood samples to determine apoptosis. Finally, cDNA macroarrays were used to evaluate the expression of 23 genes involved in the regulation of cell cycling and apoptosis. RESULTS: Exposure to hypertonic fluids (hypertonic saline and 7.5% hypertonic saline with 6% dextran-70) significantly (p < 0.05) increased necrosis in isolated PMNs. In whole blood samples, PMNs exposed to dextran demonstrated significant apoptosis as evidenced by increased caspase activation. Dextran was the only fluid that affected leukocyte gene expression, inducing significant up-regulation of Rb gene transcription. CONCLUSION: Hypertonic fluids and dextran decrease human polymorphonuclear cell survival through necrotic and apoptotic pathways, respectively.

Apoptosis↗

PubMed2003

Searching for the optimal resuscitation method: recommendations for the initial fluid resuscitation of combat casualties.

Resuscitation can exacerbate cellular injury caused by hemorrhagic shock, and the type of fluid used for resuscitation may play an important role in this injury. Unlike some factors in the treatment of combat casualty, the method of resuscitation is under our control. The prevention of cellular injury through wiser resuscitation strategies would be more advantageous than attempting complex immunomodulation after the damage has already occurred. This article summarizes data from a number of studies to illustrate the differential effects of commonly used resuscitation fluids on cellular injury. Our findings show that resuscitation with hypotonic/isotonic crystalloids, including lactated Ringer's (LR) solution, and artificial colloid solutions, elicit severe immune activation and an up-regulation of cellular injury markers. This effect is not seen with plasma, natural colloids (albumin), and fresh whole blood. Hypertonic fluids cause suppression of neutrophil activation and a milder increase in the expression of cell injury markers compared with isotonic fluids. The effect of various resuscitation fluids on core cellular functions such as gene regulation is also summarized in this article. Finally, because of the uniqueness of combat care, a set of new recommendations for initial fluid resuscitation of combat casualties is proposed.

Animals↗

PubMed2003

Comparative analysis of hemostatic agents in a swine model of lethal groin injury.

BACKGROUND: Techniques for better hemorrhage control after injury could change outcome. A large-animal model of lethal, uncontrolled hemorrhage was developed to test whether the use of various hemostatic agents would decrease bleeding and improve early survival. METHODS: A complex groin injury was created in 30 Yorkshire swine (42-55 kg) to produce uncontrolled hemorrhage. This injury included semitransection of the proximal thigh and complete division of the femoral artery and vein. After 5 minutes, the animals were randomized to (n = 6 animals per group) no dressing (ND), standard dressing (SD), SD and Rapid Deployment Hemostat (RDH) bandage, SD and QuikClot hemostatic agent (QC), or SD and TraumaDEX (TDEX). Limited volume 0.9% saline (1,000 mL over 30 minutes) resuscitation was started 30 minutes after injury. We measured blood loss, early mortality (180 minutes), and physiologic markers of hemorrhagic shock (e.g., cardiac output, blood pressure, hemoglobin, metabolic acidosis). RESULTS: Application of wound dressing decreased mortality in all groups compared with the ND group (83% mortality). However, this difference was significant (p < 0.05) only for the QuikClot hemostatic agent (0% mortality). Before the application of dressing (first 5 minutes), there were no differences in blood loss between the groups. After application of dressings, the QC group had the lowest blood loss (4.4 +/- 1.4 mL/kg). CONCLUSION: Of the hemostatic agents tested, QuikClot improved survival and decreased bleeding in a swine model of lethal vascular and soft tissue injury.

Animals↗

PubMed2003

A portable handpump is effective in the evacuation of hemothorax in a swine model of penetrating chest injury.

BACKGROUND: Standard pleural evacuation devices are not practical for use on the battlefield. A small, portable, easy-to-use handpump (HP) that does not require continuous suction for treating hemopneumothorax would offer a major logistical advantage. In addition, using endotracheal tubes instead of regular pleural tubes would help minimize supplies carried on the battlefield. A swine model of penetrating chest injury was designed to test this concept. Our hypothesis was that an HP would be as effective as the standard of care for the evacuation of a large hemopneumothorax. METHODS: A 2-cm lung laceration was created in 18 Yorkshire swine (35-51 kg) under inhaled anesthesia and 1.4 L of blood was infused into the pleural space (200 mL every 15 minutes). Fluid resuscitation (2,000 mL of 0.9% saline) was started 15 minutes after injury, and animals were randomized into one of three groups: group 1, 36-Fr Argyle pleural tube and Pleur-Evac chest drainage unit with 20-cm H2O suction (control); group 2, 36-Fr pleural tube attached to the HP; and group 3, a No. 8 endotracheal tube in the pleural space attached to the HP. After 120 minutes, a thoracotomy was performed to determine the amount of residual blood in the pleural space. RESULTS: Effectiveness of the three methods as a percentage of total blood (evacuated and retained) removed was measured over 2 hours. The handpump (group 2) performed better than the standard of care (group 1) at numerous time points and evacuated significantly (p < 0.05) more blood at the end of the experiment. CONCLUSION: Using the handpump with a pleural tube was more effective than the standard of care in treating traumatic hemothorax. The use of an endotracheal instead of a conventional pleural tube had no adverse impact on efficacy of the pump in evacuating blood from the chest cavity.

Animals↗

PubMed2003

Alterations of cullin-5 mRNA levels in the rat central nervous system following hemorrhagic shock.

Hemorrhagic shock is a clinical syndrome that manifests as hypoperfusion, hypoxia, and ischemia initiating various cellular stress responses involved in the synthesis and release of an assortment of pro-inflammatory molecules, cytokines, chemokines, and reactive oxidant species (ROS). The ROS have been shown to oxidize and damage proteins making them targets for ubiquitination and proteasomal degradation. Cullin-5 (cul-5), an E3 ligase that binds ubiquitin to proteins targeted for degradation via the proteasome, was investigated for its gene expression during hemorrhagic shock. Male Long-Evans rats were subjected to volume controlled (27 ml kg-1) hemorrhage over 10 min and kept in shock for 60 min. Quantitative realtime polymerase chain reaction showed cul-5 mRNA levels were significantly increased in the brainstem and cerebellum, and decreased in the hypothalamus of rats as a result of hemorrhagic shock (n = 6) compared to sham-treated rats (n = 6). Cul-5 mRNA levels in the cerebral cortex, small intestine, kidney, liver, lung, or pituitary gland did not significantly change after hemorrhagic shock. This is the first report of cul-5 mRNA regulation by hemorrhagic shock. Evidence indicates this protein may have a regulatory role in ubiquitin-proteasomal protein degradation in response to hemorrhagic shock.

Animals↗

PubMed2002

cDNA array analysis of gene expression following hemorrhagic shock and resuscitation in rats.

UNLABELLED: The aim of this study was to characterize gene expression following hemorrhagic shock and resuscitation with emphasis on the differences between various resuscitation strategies. METHODS: Male Sprague Dawley rats (n = 25; 5/group) were subjected to a three stage hemorrhage and resuscitated as follows: (1) sham hemorrhage; (2) sham resuscitation; (3) lactated Ringer's solution (LR), 3:1 volume; (4) 7.5% hypertonic saline (HTS) 9.7 ml/kg; (5) plasma, 1:1 volume. Liver, spleen, lung and muscle were collected 3 h post resuscitation and cDNA array analysis was performed on the total RNA. RESULTS: Expression of 1,176 genes was analyzed. Following resuscitation, 82 of the genes studied (7%) displayed an altered expression of at least 2-fold compared to the sham hemorrhage group. Depending on organ system under study and resuscitation conditions, expression of these 82 genes was down- or up-regulated, bringing the total number of expression alterations to 167. Largest number of organ-specific changes in gene expression was noted in liver (63/167), followed by lung (57), muscle (25), and spleen (22). Most of the resuscitation strategy specific changes were caused by plasma resuscitation (68/167), followed by LR (51), and HTS (48). In every organ studied, gene expression profile was dependent upon the fluid used for resuscitation. CONCLUSION: Cellular response to hemorrhagic shock, even at the level of gene expression, is dependent on the resuscitation strategy. We have discovered altered expression of genes not previously implicated in the physiology of hemorrhagic shock and resuscitation. Gene array technology provides a rapid and efficient means of dissecting the complex genetic regulation of cellular response to shock.

Animals↗

PubMed2002

Learning and memory is preserved after induced asanguineous hyperkalemic hypothermic arrest in a swine model of traumatic exsanguination.

BACKGROUND: Induced asanguineous hypothermic metabolic arrest (suspended animation) could provide valuable time to repair major vascular injuries if safely induced in patients with trauma. We report a novel method of doing this in a swine model of uncontrolled lethal hemorrhage (ULH) that resulted in preservation of learning ability and memory. METHODS: Yorkshire swine (100 to 125 lb) underwent ULH before rapid intra-aortic infusion of a hypothermic (4 degrees C), hyperkalemic (70 mEq/L) organ preservation solution by a left thoracotomy. Cooling continued until core temperature reached 10 degrees C, and this was maintained for 60 minutes using low-flow cardiopulmonary bypass. Vascular injuries were repaired during this state of suspended animation, which was then reversed, and the animals were observed for 6 weeks. Cognitive functions were tested by training animals to retrieve food from color-coded boxes. Postoperatively, the ability to remember this task and a 75-point objective neurologic scale were used to test neurologic function. In experiment I, ULH was caused by lacerating thoracic aorta (n = 9). Five preoperatively untrained animals were trained to perform the task and compared with control animals (n = 15), and 4 preoperatively trained animals were tested for memory retention postoperatively. In experiment II, ULH was induced by creating an iliac artery and vein injury (n = 15). Animals were kept in shock for 15, 30, and 60 minutes before the induction of hypothermia. RESULTS: In experiment I, surviving animals (7/9) were neurologically intact, and their capacity to learn new skills was no different than for control animals. All pretrained animals demonstrated complete memory retention. In experiment II, survival with 15, 30, and 60 minutes of shock were 80%, 60%, and 80%, respectively. All animals (except 1) in the 60-minute group were neurologically intact and displayed normal learning capacity. CONCLUSIONS: Induction of hypothermic metabolic arrest (by thoracotomy) for repair of complex traumatic injuries is feasible with preservation of normal neurologic function, even after extended periods of shock from an intra-abdominal source of uncontrolled hemorrhage.

Animals↗

PubMed2002

Hypertonic saline: intraosseous infusion causes myonecrosis in a dehydrated swine model of uncontrolled hemorrhagic shock.

BACKGROUND: The Institute of Medicine has recommended intraosseous (IO) infusion of 7.5% hypertonic saline (HTS) for combat casualties in shock. We tested the safety and efficacy of this recommendation in a long-term survival model of uncontrolled hemorrhagic shock using dehydrated swine. METHODS: Fourteen dehydrated Yorkshire swine had placement of a 12G needle in the right anterior tibia under isoflurane anesthesia. Uncontrolled hemorrhage was induced via left iliac artery and vein injury. Animals were kept in shock for 2 hours and then resuscitated over 2 hours with 5 mL/kg of 7.5% HTS given either as 10 small boluses (group I, n = 4) or two large boluses (group II, n = 6) to compare the physiologic response and blood loss. Control animals (group III, n = 4) received an equal volume of 0.9% saline IO and additional intravenous saline to equalize the salt load in all groups. RESULTS: The three groups had similar physiologic responses, with no increase in blood loss following HTS resuscitation. However, between the second and fifth postresuscitation days, the 7.5% HTS resuscitated animals developed soft tissue necrosis or bone marrow necrosis of the right hind leg (group I, 100%; group II, 66.6%; group III, 0%). CONCLUSION: HTS resuscitation effectively restored hemodynamic stability in dehydrated swine without increased bleeding from an uncontrolled vascular injury. However, IO infusion of HTS in this model was associated with a very high rate of local complications. Further investigations should be undertaken before IO use of 7.5% HTS in humans.

Animals↗

PubMed2002

Cytokine expression profiling in human leukocytes after exposure to hypertonic and isotonic fluids.

BACKGROUND: Resuscitation from hemorrhagic shock causes profound immunologic changes. The tonicity of fluids used for resuscitation clearly influences the immune response. Our study was designed to determine whether isotonic and hypertonic fluids exert their differential effects on immune response by altering the cytokine gene profile of human leukocytes. The cDNA array method was used to profile transcriptional responses after exposure to hypertonic and isotonic fluids. METHODS: Blood from seven healthy volunteers was incubated for 30 minutes with isotonic (10% dextran-40 and lactated Ringer's [LR] solution) and hypertonic (7.5% hypertonic saline and hypertonic dextran [HTD]) fluids. The volumes of isotonic fluids used were equal to the volume of blood, whereas the volumes of hypertonic fluids were adjusted to keep the salt load identical to the LR group. The cDNA array technique was used to measure the gene expression of 23 common cytokines. RESULTS: Increased gene transcription of proinflammatory cytokines (interleukin [IL]-1alpha, IL-6, IL-10, and tumor necrosis factor-alpha) as well as others (IL-5, IL-7, and IL-16) was found after incubation with resuscitation fluids. Variances were noted depending on the type of fluid: HTD and LR solution did not induce expression of IL-5, and HTD also did not induce IL-1beta expression. Genes encoding IL-1alpha, IL-6, IL-9, and tumor necrosis factor-alpha had low level baseline expression in leukocytes isolated from unstimulated blood, and their expression increased markedly after exposure to resuscitation fluids. The inducible transcripts included IL-1beta, IL-7, IL-10, and IL-16. However, there was no difference in cytokine expression profile between isotonic and hypertonic fluids. CONCLUSION: Exposure of human leukocytes to resuscitation fluids causes an increase in cytokine gene expressions compared with undiluted blood. This expression profile is largely independent of the type of fluid used.

Adult↗