Biomedical subjects

Hasan B Alam

Publications and source records attributed to Hasan B Alam.

At least 19 recordsLinked to original sources

PubMed2007

New developments in fluid resuscitation.

Hemorrhagic shock is the leading cause of death in civilian and military trauma. Effective hemorrhage control and optimal resuscitation are the main goals in the management of severely injured patients. This article addresses the changing trends in fluid resuscitation in regards to who, when, and how. Much of these changing trends are caused by the recognition that the current method of resuscitation with crystalloid fluids may not be optimal and may even have detrimental consequences. This article summarizes a number of studies that have evaluated the cellular toxicities of commonly used resuscitation fluids, to highlight the need for the development of new fluids.

Animals↗

PubMed2006

Falls from height: spine, spine, spine!

BACKGROUND: Falls from a height are a major cause of morbidity and hospital cost. Spinal injury is frequently associated with falls from height, but reliable predictive factors have not been identified. Diagnostic evaluation of the spine is complex and debated. Our objective was to characterize spinal injury after falls from height and identify predictive factors of spinal injuries. STUDY DESIGN: Medical records of patients with falls from height>10 feet admitted in a Level I trauma center during a period of 66 months were reviewed. Univariate and multivariate analyses were performed to identify independent risk factors of spinal injuries. RESULTS: Of 414 patients, 127 (31%) suffered 277 spinal injuries. Multiple spinal injuries at different levels were found in 62 (49%) patients; in 19 (15%) spinal injuries were at noncontinuous levels. The only independent predictor of spinal injury was alcohol intoxication (odds ratio=3.305; 95% CI, 1.75-6.242; p<0.001) but the number of intoxicated patients was low and the predictive ability weak. Level of falls from height did not correlate with likelihood of spinal injury. Twenty-four of 107 (22%) patients with spinal injuries and a reliable clinical examination had no symptoms related to the spine; all but 2 had distracting injuries. CONCLUSIONS: Spinal injury is frequent among survivors of falls from height>10 feet. Because of the absence of reliable predictors of spinal injury, the possibility of multiple noncontinuous fractures, and the presence of distracting injuries clouding the clinical presentation, aggressive evaluation of the entire spine is warranted.

Accidental Falls↗

PubMed2006

Host-guest composites for induced hemostasis and therapeutic healing in traumatic injuries.

INTRODUCTION: The United States military currently outfits our soldiers with a zeolite-based hemostatic agent (HA) that is applied directly onto a traumatic wound to induce hemostasis and prevent loss of life from exsanguination. The goals of this work were to identify and implement strategies to attenuate a tissue burning side effect associated with the HA, resulting from a large release of heat upon hydration, without adversely affecting the wound healing properties. Five ion exchanged derivatives of the parent HA were prepared and characterized with regard to their material and thermal properties, in vitro hemostatic efficacy, and antibacterial activity. METHODS: The five host-guest high-surface-area HAs were prepared by ion exchanging the zeolite linde type 5A with aqueous salt solutions under controlled conditions. The modified HAs were characterized by TGA, DSC, Thermal Imaging, SEM, XRD, XPS, BET, and a Thromboelastograph (TEG) was employed to assay the in vitro hemostatic efficacy. Antibacterial activity was assayed by measuring the zone of no growth of Pseudomonas aeruginosa biofilms growing in contact with the ion exchanged HAs. RESULTS: The heat released during application of the HA can be minimized from 680 J/g to 420 J/g by ion exchanging the calcium ions in zeolite linde type 5A with cations of a reduced hydration enthalpy. Zeolite-based HAs that demonstrate in vitro clot induction time of R < or = 1.8 min, and with surfaces areas > or = 634 m2/g, correlate with 75% in vivo swine survivability of a universally lethal groin injury. Silver exchanged HA maintained a zone of no growth of P. aeruginosa with a surface area twice the geometrical surface area of an HA pressed pellet for 24 hours in an LB Agar assay. CONCLUSIONS: Two strategies for reducing the large amount of heat released by a zeolite-based HA during application have been described and quantified: (1) ion exchange and (2) prehydration. Five ion-exchanged derivatives of the original HA have been prepared and assayed for hemostatic efficacy both in vitro, by TEG, and in vivo, by clinical swine trials. Contact activation coagulation rates, alpha, were found to increase with the amount of heat released by the HA. In Vitro clot induction time, R, and HA surface area have been identified as predictors of in vivo hemostatic performance. A proposed rationale for selecting hemostatic materials based on these parameters will likely reduce the quantity of experiments involving animals, and the associated labor and capital costs, necessary to test a new HA. A method for incorporating antibacterial activity against gram negative P. aeruginosa into the Ag-exchanged formulation of zeolite LTA-5A has been described and substantiated.

Animals↗

PubMed2006

Cardiac histones are substrates of histone deacetylase activity in hemorrhagic shock and resuscitation.

BACKGROUND: DNA transcription is regulated, in part, by acetylation of nuclear histones that are controlled by 2 groups of enzymes: histone deacetylases (HDAC) and histone acetyl transferases (HAT). Whether an imbalance in HDAC/HAT system plays a role in hemorrhage/resuscitation is unknown. The goals of this study were to determine whether hemorrhage results in deacetylation of cardiac histones and whether this can be corrected through the application of different resuscitation strategies or specific HDAC inhibitors. METHODS: In the first experiment, rats (n = 6 per group) were subjected to volume-controlled hemorrhage and resuscitated with racemic lactated Ringer's solution, L-lactated Ringer's solution, 7.5% hypertonic saline solution, ketone Ringer's solution, and pyruvate Ringer's solution. Control groups included no hemorrhage (sham) and hemorrhage with no resuscitation. In the second experiment (n = 5 per group), 3 HDAC inhibitors (valproic acid, trichostatin A, and suberoylanilide hydroxamic acid) were added to saline solution resuscitation. Heart tissue was collected at the end of resuscitation. Isolated subcellular protein fractions were used in Western blotting to analyze the patterns of total protein acetylation and histone acetylation specifically. HDAC and HAT activity was measured in tissue extracts. RESULTS: Hemorrhage led to partial histone deacetylation. Resuscitation resulted in protein hyperacetylation in nuclear fractions only. A detailed analysis of histones (on 10 acetylation sites) revealed that ketone Ringer's solution hyperacetylated histones H2B, H3, and H4. The addition of suberoylanilide hydroxamic acid hyperacetylated histones more effectively than other resuscitation strategies, presumably by direct inhibition of HDAC activity. CONCLUSION: Hemorrhage/resuscitation is associated with HDAC/HAT activity misbalance, and the acetylation status of cardiac histones is influenced by the choice of resuscitation strategy. Shock-induced changes can be reversed through the infusion of pharmacologic HDAC inhibitor, even when it is administered after the insult for a limited period of time.

Acetylation↗

PubMed2006

Profound hypothermia is superior to ultraprofound hypothermia in improving survival in a swine model of lethal injuries.

BACKGROUND: Rapid induction of profound hypothermia can improve survival from uncontrolled lethal hemorrhage. However, the optimal depth of hypothermia in this setting remains unknown. This experiment was designed to compare the impact of deep (15 degrees C), profound (10 degrees C), and ultraprofound (5 degrees C) hypothermia on survival and organ functions. METHODS: Uncontrolled lethal hemorrhage was induced in 32 swine (80-120 lb) by creating an iliac artery and vein injury, followed 30 minutes later by laceration of the descending thoracic aorta. Hypothermia was induced rapidly (2 degrees C/min) by infusing cold organ preservation solution into the aorta through a thoracotomy. The experimental groups were (n = 8 per group): a normothermic control, and 3 hypothermic groups in which the core temperature was reduced to 15 degrees C, 10 degrees C, and 5 degrees C. Vascular injuries were repaired during 60 minutes of hypothermia. Animals were then rewarmed (0.5 degrees C/min) and resuscitated on cardiopulmonary bypass, and monitored for 6 weeks for neurologic deficits, cognitive function, and organ dysfunction. RESULTS: All normothermic animals died, whereas 6-week survival rates for the 15 degrees C, 10 degrees C, and 5 degrees C groups were 62.5%, 87.5%, and 25%, respectively (P < .05: normothermic vs 15 degrees C and 10 degrees C; 10 degrees C vs 5 degrees C). The surviving animals from the 15 degrees C and 10 degrees C groups were neurologically intact, displayed normal learning capacity, and had no long-term organ dysfunction. The survivors from the 5 degrees C group displayed slower recovery and impaired cognitive functions. CONCLUSIONS: In a model of lethal injuries, rapid induction of profound hypothermia can prevent death. The depth of hypothermia influences survival, with a better outcome associated with a core temperature of 10 degrees C compared with 5 degrees C.

Animals↗

PubMed2006

Valproic acid prevents hemorrhage-associated lethality and affects the acetylation pattern of cardiac histones.

Pharmacological inhibitors of histone deacetylases (HDAC) demonstrate cytoprotective effects both in vitro and in vivo. In this study, we investigated whether valproic acid (VPA), a known mood stabilizer and anticonvulsant with HDAC-inhibiting activity, improves survival following otherwise lethal hemorrhage in rats. We found that preinsult injection of VPA (300 mg/kg, twice) prolonged the survival of severely hypotensive animals up to 5 times. VPA treatment increased the acetylation of nonhistone and histone proteins in the rat heart. The pattern of modifications of individual histones revealed hyperacetylation of histones H2A, H3, and H4, indicating the presence of active genes. Expression of HSP70 and superoxide dismutase, implicated in the modulation of vitality, was increased by VPA. Our results reveal that VPA offers considerable protection in the hemorrhagic shock model and suggest a role for HDAC inhibition in mediating VPA actions.

Acetylation↗

PubMed2006

Making sense of the preclinical literature on advanced hemostatic products.

A number of new hemostatic products have been developed recently for use in trauma settings of severe uncontrolled bleeding. Currently, the literature on these products is controversial, with efficacy demonstrated under some circumstances but not others. In this review, we analyze the current literature pertaining to four of the most promising products (dry fibrin sealant dressing, Rapid Deployment Hemostat, HemCon chitosan dressing, and QuikClot) that have been suggested for use in combat casualty care applications. In particular, this analysis takes into account the characteristics of the animal models used for efficacy testing of these products, the desired characteristics of hemostatic dressings, and specific safety considerations. Animal models ranged from those featuring low-pressure/low-flow bleeding to those featuring high-pressure/high-flow bleeding. When data are viewed in the context of the specific characteristics of the differing animal models used, seemingly disparate experimental results related to efficacy and safety become quite complementary and lead to recommendations for the use of different products in different injury scenarios. Mission and training requirements will dictate the use of these products by military and civilian prehospital care providers.

Animals↗

PubMed2006

Does the rate of rewarming from profound hypothermic arrest influence the outcome in a swine model of lethal hemorrhage?

BACKGROUND: Rapid induction of profound hypothermic arrest (suspended animation) can provide valuable time for the repair of complex injuries and improve survival. The optimal rate for re-warming from a state of profound hypothermia is unknown. This experiment was designed to test the impact of different warming rates on outcome in a swine model of lethal hemorrhage from complex vascular injuries. METHODS: Uncontrolled lethal hemorrhage was induced in 40 swine (80-120 lbs) by creating an iliac artery and vein injury, followed 30 minutes later (simulating transport time) by laceration of the descending thoracic aorta. Through a thoracotomy approach, a catheter was placed in the aorta and hyperkalemic organ preservation solution was infused on cardiopulmonary bypass to rapidly (2 degrees C/min) induce profound (10 degrees C) hypothermia. Vascular injuries were repaired during 60 minutes of hypothermic arrest. The 4 groups (n = 10/group) included normothermic controls (NC) where core temperature was maintained between 36 to 37 degrees C, and re-warming from profound hypothermia at rates of: 0.25 degrees C/min (slow), 0.5 degrees C/min (medium), or 1 degrees C/min (fast). Hyperkalemia was reversed during the hypothermic arrest period, and blood was infused for resuscitation during re-warming. After discontinuation of cardiopulmonary bypass, the animals were recovered and monitored for 6 weeks for neurologic deficits, cognitive function (learning new skills), and organ dysfunction. Detailed examination of brains was performed at 6 weeks. RESULTS: All the normothermic animals died, whereas survival rates for slow, medium and fast re-warming from hypothermic arrest were 50, 90, and 30%, respectively (p < 0.05 slow and medium warming versus normothermic control, p < 0.05 medium versus fast re-warming). All the surviving animals were neurologically intact, displayed normal learning capacity, and had no long-term organ dysfunction. CONCLUSIONS: Rapid induction of hypothermic arrest maintains viability of brain during repair of lethal vascular injuries. Long-term survival is influenced by the rate of reversal of hypothermia.

Animals↗

PubMed2006

Hepatic and pulmonary apoptosis after hemorrhagic shock in swine can be reduced through modifications of conventional Ringer's solution.

BACKGROUND: Cytotoxic properties of racemic (D-,L-isomers) lactated Ringer's solution detected in vitro and in small animal experiments, have not been confirmed in large animal models. Our hypothesis was that in a clinically relevant large animal model of hemorrhage, resuscitation with racemic lactated Ringer's solution would induce cellular apoptosis, which can be attenuated by elimination of d-lactate. METHODS: Yorkshire swine (n = 49, weight 40-58 kg) were subjected to uncontrolled (iliac arterial and venous injuries) and controlled hemorrhage, totaling 40% of estimated blood volume. They were randomized (n = 7/group) to control groups, which consisted of (1) no hemorrhage (NH), (2) no resuscitation (NR), or resuscitation groups, which consisted of (3) 0.9% saline (NS), (4) racemic lactated Ringer's (DL-LR), (5) L-isomer lactated Ringer's (L-LR), (6) Ketone Ringer's (KR), (7) 6% hetastarch in 0.9% saline (Hespan). KR was identical to LR except for equimolar substitution of lactate with beta-hydroxybutyrate. Resuscitation was performed in three phases, simulating (1) prehospital, (2) operative, (3) postoperative/recovery periods. Arterial blood gasses, circulating cytokines (TNF-alpha, IL-1, -6, -10), and markers of organ injury were serially measured. Metabolic activity of brain, and liver, was measured with microdialysis. Four hours postinjury, organs were harvested for Western blotting, ELISA, TUNEL assay, and immunohistochemistry. RESULTS: All resuscitation strategies restored blood pressure, but clearance of lactic acidosis was impeded following DL-LR resuscitation. Metabolic activity decreased during shock and improved with resuscitation, without any significant inter-group differences. Levels of cytokines in circulation were similar, but tissue levels of TNF in liver and lung increased six- and threefolds (p < 0.05) in NR group. In liver, all resuscitation strategies significantly decreased TNF levels compared with the NR group, but in the lung resuscitation with lactated Ringer (DL and L isomers) failed to decrease tissue TNF levels. DL-LR resuscitation also increased apoptosis (p < 0.05) in liver and lung, which was not seen after resuscitation with other solutions. CONCLUSIONS: In this large animal model of hemorrhagic shock, resuscitation with conventional (racemic) LR solution increased apoptotic cell death in liver and lung. This effect can be prevented by simple elimination of D-lactate from the Ringer's solution.

Animals↗

PubMed2006

Routine repeat head CT for minimal head injury is unnecessary.

BACKGROUND: Patients with MHI and a positive head computed tomography (CT) scan frequently have a routine repeat head CT (RRHCT) to identify possible evolution of the head injury requiring intervention. RRHCT is ordered based on the premise that significant injury progression may take place in the absence of clinical deterioration. METHODS: In a Level I urban trauma center with a policy of RRHCT, we reviewed the records of 692 consecutive trauma patients with Glasgow Coma Scale scores of 13-15 and a head CT (October 2004 through October 2005). The need for medical or surgical neurologic intervention after RRHCT was recorded. Patients with a worse and unchanged RRHCT were compared, and independent predictors of a worse RRHCT were identified by stepwise logistic regression. RESULTS: There were 179 patients with MHI and RRHCT ordered. Of them, 37 (21%) showed signs of injury evolution on RRHCT and 7 (4%) required intervention. All 7 had clinical deterioration preceding RRHCT. In no patient without clinical deterioration did RRHCT prompt a change in management. A Glasgow Coma Scale score less than 15 (13 or 14), age higher than 65 years, multiple traumatic lesions found on first head CT, and interval shorter than 90 minutes from arrival to first head CT predicted independently a worse RRHCT. CONCLUSIONS: RRHCT is unnecessary in patients with MHI. Clinical examination identifies accurately the few who will show significant evolution and require intervention.

Adult↗

PubMed2006

Identification of expression patterns associated with hemorrhage and resuscitation: integrated approach to data analysis.

BACKGROUND: Although transcriptional profiling is a well-established technique, its application to systematic studying of various biological phenomena is still limited because of problems with high-volume data analysis and interpretation. This research project's objective was to create a comprehensive summary of changes in gene expression after hemorrhagic shock (HS), reliant and impartial of multiple variables, such as resuscitation treatments, organ analyzed, and time after impact. METHODS: Rat model of severe (40% total blood loss) HS was employed. Hemorrhagic shock was treated with 6 different resuscitation strategies: (1) racemic lactated Ringer's (DL-LR); (2) L-lactated Ringer's (L-LR); (3) ketone Ringer's (KR); (4) pyruvate Ringer's (PR); (5) 6% hetastarch (Hex); (6) 7.5% hypertonic saline (HTS). Nonresuscitated and nonhemorrhaged rats served as controls. Ketone and pyruvate Ringer solutions were identical to the lactated Ringer's solution except for equimolar substitution of lactate with beta-hydroxybutyrate and sodium pyruvate, respectively. Total RNA from liver, lung, and spleen was isolated immediately (0 hour) and 24 hour postresuscitation. Each organ, time point and treatment was profiled using individual cDNA array (1,200 genes), to produce 183 separate data files. Methods of analysis included one-way and unbalanced factorial ANOVA, Sokal-Michener average linkage clustering and contextual mapping. RESULTS: : Unresuscitated HS produced the highest number (56) of upregulated expressions in spleen and lungs. HEX and HTS affected mostly pulmonary genes (22 and 9). Fourteen genes changed in response to combination of all three factors: treatment, organ, and time. Eighteen genes were identified as treatment-specific. Fifteen genes adjusted expression 24 hour post-treatment. The largest number of genes with altered expression (168) responded differently in all three organs. In this study 15 gene clusters were pinpointed. Contextual mapping identified novel and confirmed known pathways contributing to hemorrhage/resuscitation. CONCLUSIONS: We have reliably identified genes and pathways that are affected by HS and are responsive to resuscitation. Gene expression in various organs is affected differentially by HS, which can be further modulated by the choice of resuscitation strategy.

Analysis of Variance↗

PubMed2006

Testing of modified zeolite hemostatic dressings in a large animal model of lethal groin injury.

BACKGROUND: We have previously identified a granular zeolite hemostat (ZH) as an effective agent for control of severe bleeding, and it is currently being used by the US troops in the battlefield. ZH causes an exothermic reaction on application, which theoretically can be decreased by altering its chemical composition or changing its physical properties. However, the effect of these alterations on the hemostatic efficacy is unknown. We tested modified zeolites and a chitosan based dressing against controls in a swine model of battlefield injury. METHODS: A complex groin injury was created in 60 swine (40-55 kg). This included semi-transection of the proximal thigh (level of inguinal ligament), and complete division of the femoral artery and vein. After 3 minutes, the animals were assigned to (1) no dressing (ND), (2) standard dressing (SD), (3-5) SD + chemically modified ZHs, where calcium was substituted with sodium (Na), barium (Ba), or silver (Ag), respectively, (6) SD + physically modified ZH, where "beads" were packaged in a fabric bag, (7) SD + chitosan based dressing (CD). Resuscitation was started 15 minutes after application of dressing (500 mL of 6% hetastarch over 30 minutes). Survival for 180 minutes was the primary endpoint for this study. In addition, blood loss, wound temperatures, and histologic tissue damage were recorded. RESULTS: Mortality in the group that was treated with the application of bagged ZH was 10% versus 100% in the no dressing group and 50% in the SD group (p < 0.05 vs. ND and SD groups). The Na ZH group had a mortality rate of 43%, whereas application of Ba and Ag substituted zeolites, and CD were associated with a mortality rate of 25%. Ionic substitution of zeolite decreased the in vivo temperature peak by 5 to 10 degrees C. No histologic evidence of tissue necrosis was noted in this experiment. CONCLUSIONS: The use of zeolite hemostat can control hemorrhage and dramatically reduce mortality from a lethal groin wound. Modifications of zeolite hemostat can decrease the exothermic reaction and attenuate tissue damage.

Animals↗

PubMed2006

Development and testing of portable pump for the induction of profound hypothermia in a Swine model of lethal vascular injuries.

UNLABELLED: Rapid induction of a profound hypothermic state (suspended animation) can maintain viability of key organs during repair of lethal injuries. Conventional cardiopulmonary bypass equipment (roller pump) used to induce and reverse hypothermia is expensive, bulky, requires standard electricity, and is not transportable. Development of a small, portable, battery operated, disposable, pump can logistically facilitate induction and maintenance of hypothermia. In this experiment, a portable prototype pump was tested and its performance was compared with the regular roller pump in a swine model of lethal vascular injuries. METHODS: Uncontrolled hemorrhage was induced in 16 swine (80-120 lbs) by creating an iliac artery and vein injury (nonlethal). After 30 minutes of pulseless shock, the descending thoracic aorta was lacerated (lethal injury). Through a left thoracotomy approach, a catheter was placed in the aorta and cold organ preservation solution was infused to rapidly (2 degrees C/min) induce hypothermia (10 degrees C) for 60 minutes. The performance of the prototype pump was initially tested in a nonsurvival experiment (four animals). Then, 12 animals were cooled either with (n = 6/group) (1) conventional roller pump or (2) small prototype pump. The injuries were repaired during hypothermic arrest and the animals were re-warmed (0.5 degrees C/min). Whole blood was infused during resuscitation on cardiopulmonary bypass. Surviving animals were closely monitored for 3 weeks for postoperative complications, neurologic deficits, and organ dysfunction. RESULTS: The flow rates and the time needed to induce and reverse profound hypothermia were no different between the prototype and the conventional roller pumps. Three-week survival rates were 83% in both groups. Only a transient increase in liver enzymes, and markers of cellular injury (creatine kinase, lactate dehydrogenase) was noted (no meaningful difference between groups), with no long-term organ dysfunction. CONCLUSIONS: In this large animal model of lethal vascular injuries, a portable, battery operated, disposable, rotary pump performed as well as the conventional roller pump. The logistical advantages of this system make it an attractive choice for inducing hypothermia in emergency departments and austere settings, and for maintaining hypothermia during transport.

Animals↗

PubMed2005

Hepatic apoptosis after hemorrhagic shock in rats can be reduced through modifications of conventional Ringer's solution.

BACKGROUND: Resuscitation with racemic lactated Ringer's solution induces cellular apoptosis. This study was conducted to determine if the elimination of D-lactate isomer would attenuate apoptosis in the liver, and to investigate the possible mechanisms. STUDY DESIGN: Sprague Dawley rats (n=30, 5 per group) were subjected to modified volume-controlled hemorrhage and randomized to the following groups: no hemorrhage (sham); no resuscitation (NR); resuscitation with racemic lactated Ringer's (DL-LR); L-isomer LR (L-LR); ketone (beta-hydroxybuturate) Ringer's (KR); or pyruvate Ringer's (PR). Animals were sacrificed 2 hours later and expressions of proapoptotic proteins (BAD), antiapoptotic (bcl-2) proteins, and poly-ADP ribose polymerase (PARP) cleavage in liver were analyzed by Western blotting. Contribution of the phosphatidylinositol 3-kinase/serine/threonine kinase (PI3k/Akt) pathway was assessed by measuring total and phosphorylated PI3K, Akt, BAD, and endothelial nitric oxide synthase (eNOS) proteins. The terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) assay was used to detect the apoptotic cells. Liver ATP levels were measured using a luciferase reaction assay. RESULTS: Hemorrhage significantly decreased the hepatic ATP level and resuscitation improved it, but it returned to normal only in the L-isomer lactated Ringer's and ketone Ringer's groups. Expression of proapoptotic proteins was significantly lower in the pyruvate Ringer's and ketone Ringer's groups; L-isomer lactated Ringer's and pyruvate Ringer's resuscitation significantly increased bcl-2 expression. Poly-ADP ribose polymerase fragmentation and total number of apoptotic cells were significantly increased in the racemic lactated Ringer's group. There was no significant induction of Akt activity or changes in phosphorylated BAD, Akt, or eNOS levels. CONCLUSIONS: Resuscitation with racemic lactated Ringer's induces hepatic apoptosis, which is decreased if the D-isomer of lactate is eliminated. Apoptosis is reduced even more when lactate is substituted with beta-hydroxybutyrate or pyruvate. The beneficial effects are not through improvements in the energy status or activation of the PI3K/Akt pathway.

Adenosine Diphosphate↗

PubMed2005

Profound hypothermia protects neurons and astrocytes, and preserves cognitive functions in a Swine model of lethal hemorrhage.

BACKGROUND: Lethal injuries can be repaired under asanguineous hypothermic arrest (suspended animation) with excellent survival. This experiment was designed to test the impact of this strategy on neuronal and astroglial damage in a swine model of lethal hemorrhage. Furthermore, our goal was to correlate the histological changes in the brain with neurological outcome, and the levels of circulating brain specific markers. MATERIALS AND METHODS: Uncontrolled hemorrhage was induced in 32 female swine (80-120 lbs) by creating an iliac artery and vein injury, followed 30 min later by laceration of the thoracic aorta. Through a thoracotomy approach, organ preservation fluid was infused into the aorta using a roller pump. Experimental groups included normothermic controls (no cooling, NC), and groups where hypothermia was induced at three different rates: 0.5 degrees C/min (slow, SC), 1 degrees C/min (medium, MC), or 2 degrees C/min (fast, FC). Profound hypothermia (core temperature of 10 degrees C) was maintained for 60 min for repair of vascular injuries, after which the animals were re-warmed (0.5 degrees C/min) and resuscitated on cardiopulmonary bypass (CPB). Circulating levels of neuron specific enolase (NSE) and S-100beta were serially measured as markers of damage to neurons and astrocytes, respectively. Light microscopy and quantitative immunohistochemical techniques were used to evaluate hippocampal CA1 area and caudate putamen for neuronal injury and astrogliosis (astrocyte hyperplasia/hypertrophy). Surviving animals were observed for 6 weeks and neurological status was documented on an objective scale, and cognitive functions were evaluated using a technique based upon the concept of operant conditioning. RESULTS: Normothermic arrest resulted in clinical brain death in all of the animals. None of the surviving hypothermic animals displayed any neurological deficits or cognitive impairment. On histological examination, normothermic animals were found to have ischemic changes in the neurons and astrocytes (hypertrophy). In contrast, all of the hypothermic animals had histologically normal brains. The circulating levels of brain specific proteins did not correlate with the degree of brain damage. The changes in NSE levels were not statistically significant, whereas S-100beta increased in the circulation after CPB, largely independent of the temperature modulation. CONCLUSIONS: Profound hypothermia can preserve viability of neurons and astrocytes during prolonged periods of cerebral hypoxia. This approach is associated with excellent cognitive and neurological outcome following severe shock. Circulating markers of central nervous system injury did not correlate with the actual degree of brain damage in this model.

Animals↗

PubMed2005

Induction of profound hypothermia modulates the immune/inflammatory response in a swine model of lethal hemorrhage.

UNLABELLED: Profound hypothermic arrest ("suspended animation") is a new strategy to improve outcome following uncontrolled lethal hemorrhage (ULH). However, the impact of this approach on the immune/inflammatory response is unknown. This experiment was conducted to test the influence of profound hypothermia on markers of immune/inflammatory system. METHODS: ULH was induced in 32 female swine (80-120 lb) by creating an iliac artery and vein injury, followed 30 min 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 using a cardiopulmonary bypass machine (CPB). Experimental groups were (1) normothermic controls (no cooling, NC), or hypothermia induced at the following rates: (2) 0.5 degrees C/min (slow, SC), (3) 1 degrees C/min (medium, MC) and (4) 2 degrees C/min (fast, FC). Vascular injuries were repaired during 60 min of profound (10 degrees C) hypothermic arrest. Hyperkalemia was reversed by hypokalemic fluid exchange, and blood was infused for resuscitation during re-warming (0.5 degrees C/min). The surviving animals were monitored for 6 weeks. Levels of IL-1, TNFalpha, IL-6, IL-10, TGF-1 beta and heat shock protein (HSP-70) were measured by ELISA in serum samples collected serially during the experiment and post-operatively. RESULTS: Some of the immune markers were influenced by the use of CPB, independent of hypothermia (decrease in TGF-1 beta and increase in IL-1 beta). Hypothermia caused a significant decrease in IL-6, and an increase in HSP-70 expression compared to normothermic controls, independent of the cooling rate. An increase in IL-10 levels was noted which was influenced by the rate of cooling (p<0.05, MC versus NC). CONCLUSIONS: Profound hypothermia modulates the post-shock immune/inflammatory system by attenuating the pro-inflammatory IL-6, increasing anti-inflammatory IL-10 and augmenting the protective heat shock responses.

Animals↗

PubMed2005

Combat casualty care research: from bench to the battlefield.

Hemorrhagic shock is the leading cause of death in civilian and combat trauma. Effective hemorrhage control and better resuscitation strategies have the potential of saving lives. The Trauma Readiness and Research Institute for Surgery (TRRI-Surg) was established to address the core mission of the Uniformed Services University, "Learning to Care for Those in Harm's Way," by conducting research to improve the outcome of combat casualties. This article highlights the salient achievements of this research effort in the areas of hemorrhage control, resuscitation, design and testing of devices, and some novel concepts such as the use of profound hypothermia. The impact of these basic science research findings on changes in military medical care and outcome of injured soldiers is also described.

Humans↗

PubMed2005

Differential expression of extracellular matrix remodeling genes in rat model of hemorrhagic shock and resuscitation.

BACKGROUND: Matrix metalloproteinases (MMPs) and their specific physiological inhibitors, tissue inhibitors of metalloproteinases (TIMPs), are thought to play an essential role in tissue repair, cell death and morphogenesis. We have previously discovered unexpected up-regulation of genes coding for multiple MMP/TIMP family members in a rat model of hemorrhagic shock and resuscitation. However, the effect of different resuscitation protocols at the level of protein expression and function remains unknown. MATERIALS AND METHODS: Male Sprague-Dawley rats (n = 50; 10/group) were subjected to a three-stage volume controlled hemorrhage and resuscitated as follows: 1) lactated Ringer's solution (LR), 3:1 volume of lost blood; 2) 7.5% hypertonic saline (HTS), 9.7 ml/kg; 3) plasma, 1:1 volume. Sham hemorrhage and sham resuscitation groups were used as controls. Expression of lung and spleen MMPs (-2, -7, -9, -10, -14, and -16), and TIMPs (-1, -2, and -3) was analyzed at transcriptional, functional and protein expression level using RT-PCR, ELISA, Western blotting, and gelatin zymography techniques. RESULTS: Spleen was affected more than lung by the resuscitation strategy and the largest number of changes was caused by HTS resuscitation. RT-PCR confirmed an increased levels of MMP-2, MMP-9, MMP-7, MMP-14, MMP-16, and TIMP-1, TIMP-2 in the spleen of HTS group compared to sham groups, whereas in lungs transcriptional levels of only TIMP-3 and TIMP-1 were significantly changed. CONCLUSION: Expression of MMP and TIMP in lung and spleen following hemorrhage is modulated by the resuscitation strategy.

Animals↗