Bacillus polygoni sp. nov., a moderately halophilic, non-motile obligate alkaliphile isolated from indigo balls

A moderately halophilic, obligate alkaliphile (growth range pH 8-12), designated strain YN-1(T), was isolated from indigo balls obtained from Ibaraki, Japan. The cells of the isolate stained Gram-positive, and were aerobic, non-motile, sporulating rods which grew optimally at pH 9. The strain grew in 3-14% NaCl with optimum growth in 5% NaCl. It hydrolysed casein and Tweens 20, 40 and 60, but not gelatin, starch, DNA or pullulan. Its major isoprenoid quinone was MK-7 and its cellular fatty acid profile mainly consisted of anteiso-C(15:0), anteiso-C(17:0) and anteiso-C(17:1). 16S rRNA phylogeny suggested that strain YN-1(T) was a member of group 7 (alkaliphiles) of the genus Bacillus, with the closest relative being Bacillus clarkii DSM 8720(T) (similarity 99.5%). However, DNA-DNA hybridization showed a low DNA-DNA relatedness (7%) of strain YN-1(T) with B. clarkii DSM 8720(T). Owing to the significant differences in phenotypic and chemotaxonomic characteristics, and phylogenetic and DNA-DNA relatedness data, the isolate merits classification as a new species, for which the name Bacillus polygoni is proposed. The type strain of this species is YN-1(T) (=JCM 14604(T)=NCIMB 14282(T)).

Aerosolized anticoagulants ameliorate acute lung injury in sheep after exposure to burn and smoke inhalation

OBJECTIVE

Acute lung injury is a detrimental complication for victims of burn accidents. Airway obstruction plays an important role in pulmonary dysfunction in these patients. In this study, we tested the hypothesis that aerosolized anticoagulants will reduce the degree of airway obstruction and improve pulmonary function in sheep with severe combined burn and smoke inhalation injury by preventing the formation of airway fibrin clots.

DESIGN

Prospective, randomized, controlled, experimental animal study.

SETTING

Investigational intensive care unit at a university hospital.

SUBJECTS

Adult female sheep.

INTERVENTIONS

After 7 days of surgical recovery, sheep were given a cutaneous burn (40% of total body surface, third degree) and insufflated with cotton smoke (48 breaths, <40 degrees C) under halothane anesthesia. After injury, sheep were placed on ventilators and resuscitated with lactated Ringer's solution. Sheep were randomly divided into five groups: sham, noninjured and nontreated (n = 6); control, injured and aerosolized with saline (n = 6); recombinant human antithrombin (rhAT) + heparin, injured and aerosolized with rhAT (290 units for each) and heparin (10,000 units for each) (n = 6); rhAT, injured and aerosolized with rhAT alone (290 units for each; n = 5); and heparin, injured and aerosolized with heparin alone (10,000 units for each; n = 5). rhAT and heparin were aerosolized every 4 hrs, starting at 2 hrs postinjury.

MEASUREMENTS AND MAIN RESULTS

Cardiopulmonary hemodynamics were monitored during a 48-hr experimental time period. Control sheep developed multiple signs of acute lung injury. This pathophysiology included decreased pulmonary gas exchange and lung compliance, increased pulmonary edema, and extensive airway obstruction. These variables were stable in sham animals. The aerosolization of rhAT or heparin alone did not significantly improve deteriorated pulmonary gas exchange. However, aerosolization of these anticoagulants in combination significantly attenuated all the observed pulmonary pathophysiology.

CONCLUSIONS

The results provide definitive evidence that aerosolized rhAT and heparin in combination may be a novel treatment strategy for pulmonary pathology in burn victims with smoke inhalation injury.

The antioxidative function of eicosapentaenoic acid in a marine bacterium,Shewanella marinintestinaIK-1

When the eicosapentaenoic acid (EPA)-deficient mutant strain IK-1Delta8 of the marine EPA-producing Shewanella marinintestina IK-1 was treated with various concentrations of hydrogen peroxide (H(2)O(2)), its colony-forming ability decreased more than that of the wild type. Protein carbonylation, induced by treating cells with 0.01 mM H(2)O(2) under bacteriostatic conditions, was enhanced only in cells lacking EPA. The amount of cells recovered from the cultures was decreased more significantly by the presence of H(2)O(2) for cells lacking EPA than for those producing EPA. Treatment of the cells with 0.1 mM H(2)O(2) resulted in much lower intracellular concentrations of H(2)O(2) being consistently detected in cells with EPA than in those without EPA. These results suggest that cellular EPA can directly protect cells against oxidative damage by shielding the entry of exogenously added H(2)O(2) in S. marinintestina IK-1.

Structural and functional analysis of the apoptosis-associated tyrosine kinase (AATYK) family

Apoptosis-associated tyrosine kinase (AATYK) is a protein kinase that is predominantly expressed in the nervous system and is involved in apoptosis and neurite growth of cerebellar granule cells. In this study, we cloned three new members of the mouse AATYK family, AATYK1B, AATYK2 and AATYK3. AATYK1B is a splicing variant of the previously reported AATYK1 (referred to as AATYK1A hereafter). In comparison with AATYK1A, these three AATYK members were characterized by having an extra N-terminal region that consists of a signal peptide-like sequence and a predicted transmembrane (TM) region, which is followed by a kinase domain and a long C-terminal domain. Both TM-containing AATYK isoforms (AATYK(+)TM: AATYK1B, 2, and 3) and TM-lacking isoform (AATYK(-)TM: AATYK1A) were recovered in membrane fractions, suggesting that AATYK(+)TM and AATYK(-)TM are transmembrane- and peripheral-membrane protein kinases, respectively. AATYK1A was recovered in the soluble fraction when the cells were treated with 2-bromo palmitate, suggesting that AATYK1A associates with membrane via palmitoylation. The kinase domain was highly conserved among all AATYK members and was shown to be catalytically active. Three AATYK family members were predominantly expressed in adult mouse brains with almost similar expression profiles: widespread distribution over the various brain regions, especially in the cerebellum and hippocampus, and up-regulated expression during development of the cerebellum. In cultured cerebellar granule cells, AATYK1 was abundantly localized in both soma and axons, AATYK2 distribution was restricted to soma, and AATYK3 was punctately present over the cells. AATYK1 was concentrated in the central domain of growth cones of dorsal root ganglion neurons. Our results indicate that AATYK family members are brain-dominant and membrane-associated kinases with slightly different distribution patterns in the developing and adult mouse brain, which may be involved in fine regulation of neuronal functions including neurite extension and apoptosis.

Home-based walking improves cardiopulmonary function and health-related QOL in community-dwelling adults

The objective of our study was to investigate the effects of a home-based walking program on physical fitness and QOL among community residents. Subjects (n = 200, mean age: 64.2 years, range: 42 - 75 years) who participated in the 32-week trial were randomly allocated to one of two groups: an exercise (E) group and a control (C) group. The E group was instructed to increase the number of steps a day that they walked and to perform aerobic walking at a target heart rate for 20 minutes or more daily, 2 or more days a week. The C group was told to continue their normal level of activity. Outcome measures were the 3-minute shuttle stamina walk test (SSWT), 30-second chair-stand test (CS-30), and SF-36. Increases in SSWT values were significantly greater in the E group than in the C group (men 24.1 m vs. 6.3 m; women 8.8 m vs. 2.4 m), as were increases in CS-30 values (men 5.9 vs. 2.6; women 4.5 vs. - 0.1). On the SF-36, the scores in the E group for vitality and mental health increased significantly. Home-based walking is considered to be an effective and feasible method to improve physical fitness and QOL among community residents.

Enhanced heterologous production of eicosapentaenoic acid in Escherichia coli cells that co-express eicosapentaenoic acid biosynthesis pfa genes and foreign DNA fragments including a high-performance catalase gene, vktA

Cellular eicosapentaenoic acid (EPA) makes up approximately 3% of total fatty acids in Escherichia coli DH5alpha, a strain that carries EPA biosynthesis genes (pEPADelta1). EPA was increased to 12% of total fatty acids when the host cell co-expressed the vector pGBM3::sa1(vktA), which carried the high-performance catalase gene, vktA. Where this vector was co-expressed, the transformant accumulated a large amount of VktA protein. However, the EPA production of cells carrying the vector, that included the insert lacking almost the entire vktA gene, was approximately 6%. This suggests that the retention of a large DNA insert in the vector and the accumulation of the resulting protein, but not the catalytic activity of VktA catalase, would potentially be able to increase the content of EPA.

FDTD Simulation of Nonlinear Ultrasonic Pulse Propagation in ESWL

The extracorporeal shock wave lithotripsy (ESWL) has come into wide use due to its non-invasive advantage. However, as for the shock wave propagation in human body in relation to practical lithotripsy, there are a few studies on numerical simulation based on models conforming to practical situations. In this paper we report a numerical method of finite difference time domain (FDTD) for analyzing ultrasonic pulse nonlinear propagation in human body tissues and demonstrated it through an experiment of Reichenberger's ESWL in water.

Effects of severe smoke inhalation injury and septic shock on global hemodynamics and microvascular blood flow in sheep

This prospective, randomized, controlled experimental study looks at the effects on global and regional microvascular blood flow (RMBF) in an ovine model of septic shock after severe smoke inhalation injury. Sixteen sheep were randomized into two groups, a control group (no injury, n = 8) and a smoke/sepsis (SS) group (n = 8), which received an insufflation of 4 sets of 12 breaths of cotton smoke (<40 degrees C) followed by instillation of live Pseudomonas aeruginosa into both lung lobes, according to an established protocol. All sheep were mechanically ventilated with 100% oxygen, and fluid resuscitated with lactated Ringer's solution for the entire duration of the 24-h experimental period to maintain hematocrit at baseline (BL) levels. Healthy control animals were not subjected to the injury and received only 4 x 12 breaths of room air and instillation of the vehicle (normal saline). Blood flow was analyzed using colored microspheres. Control animals remained hemodynamically stable and had no statistical changes from BL in visceral or cerebral blood flow during the entire experimental period. All SS animals developed a hypotensive, hyperdynamic circulation, characterized by a significant increase in heart rate and cardiac output with a simultaneous significant fall in mean arterial pressure, which, in combination, led to a fall in systemic vascular resistance index versus BL (P < 0.001, each). In visceral organs, the trachea showed a significant increase in RMBF (P < 0.001). In addition, skeletal muscle significantly increased versus BL and versus controls over time (P < 0.01). Whereas the pancreas displayed a significant drop in RMBF versus BL and controls (P < 0.05), no statistical differences occurred in the renal cortex, spleen, and ileum. All investigated cerebral structures, such as the cortex cerebri, basal ganglia, thalamus, hippocampus, pons, medulla oblongata, and cerebellum showed a significant increase in RMBF versus BL and versus control animals (P < 0.05, each). These data differ in areas of normal, increased, and decreased RMBF during septic shock after smoke inhalation injury and show differences to former studies of our group investigating RMBF in ovine models of either smoke inhalation or P. aeruginosa infusion. The results of this study reflect the complex pathophysiological variances of the combined injury and may provide a basis for future investigations for the treatment of this kind of injury.

Vitamin E attenuates acute lung injury in sheep with burn and smoke inhalation injury

INTRODUCTION

A decrease in alpha-tocopherol (vitamin E) plasma levels in burn patients is typically associated with increased mortality. We hypothesized that vitamin E supplementation (alpha-tocopherol) would attenuate acute lung injury induced by burn and smoke inhalation injury.

MATERIALS AND METHODS

Under deep anesthesia, sheep (33 +/- 5 kg) were subjected to a flame burn (40% total body surface area, third degree) and inhalation injury (48 breaths of cotton smoke, < 40 degrees C). Half of the injured group received alpha-tocopherol (1000 IU vitamin E) orally, 24 h prior to injury. The sham group was neither injured nor given vitamin E. All three groups (n = 5 per group) were resuscitated with Ringer's lactate solution (4 ml/kg/%burn/24 h), and placed on a ventilator (PEEP = 5 cmH2O; tidal volume = 15 ml/kg) for 48 h.

RESULTS

Plasma alpha-tocopherol per lipids doubled in the vitamin E treated sheep. Vitamin E treatment prior to injury largely prevented the increase in pulmonary permeability index and moderated the increase in lung lymph flow (52.6 +/- 6.2 ml/min, compared with 27.3 +/- 6.0 ml/min, respectively), increased the PaO2/FiO2 ratio, ameliorated both peak and pause airway pressure increases, and decreased plasma conjugated dienes and nitrotyrosine.

CONCLUSIONS

Pretreatment with vitamin E ameliorated the acute lung injury caused by burn and smoke inhalation exposure.

Recombinant production of docosahexaenoic acid in a polyketide biosynthesis mode in Escherichia coli

The docosahexaenoic acid (DHA) biosynthesis gene cluster (pDHA3) from the DHA-producing Moritella marina strain MP-1 includes the genes pfaA, pfaB, pfaC, and pfaD, which are similar to the genes of polyketide biosynthesis. When this cluster was co-expressed in Escherichia coli with M. marina MP-1 pfaE, which encodes phosphopantetheinyl transferase, DHA was biosynthesized. The maximum production of DHA (5% of total fatty acids) was observed at 15 degrees C. This is the first report of the recombinant production of DHA in a polyketide biosynthesis mode.

Recombinant human activated protein C improves pulmonary function in ovine acute lung injury resulting from smoke inhalation and sepsis

OBJECTIVE

To investigate the effects of recombinant human activated protein C (rhAPC) on pulmonary function in acute lung injury (ALI) resulting from smoke inhalation in association with a bacterial challenge.

DESIGN

Prospective, randomized, controlled, experimental animal study with repeated measurements.

SETTING

Investigational intensive care unit at a university hospital.

SUBJECTS

Eighteen sheep (37.2 +/- 1.0 kg) were operatively prepared and randomly allocated to either the sham, control, or rhAPC group (n = 6 each). After a tracheotomy had been performed, ALI was produced in the control and rhAPC group by insufflation of 4 sets of 12 breaths of cotton smoke. Then, a 30 mL suspension of live Pseudomonas aeruginosa bacteria (containing 2-5 x 10(11) colony forming units) was instilled into the lungs according to an established protocol. The sham group received only the vehicle, i.e., 4 sets of 12 breaths of room air and instillation of 30 mL normal saline. The sheep were studied in the awake state for 24 hrs and were ventilated with 100% oxygen. RhAPC (24 mug/kg/hr) was intravenously administered. The infusion was initiated 1 hr post-injury and lasted until the end of the experiment. The animals were resuscitated with Ringer's lactate solution to maintain constant pulmonary artery occlusion pressure.

MEASUREMENTS AND MAIN RESULTS

In comparison with nontreatment in controls, the infusion of rhAPC significantly attenuated the fall in Pao2/Fio2 ratio (control group values were 521 +/- 22 at baseline [BL], 72 +/- 5 at 12 hrs, and 74 +/- 7 at 24 hrs, vs. rhAPC group values of 541 +/- 12 at BL, 151 +/- 29 at 12 hours [p < .05 vs. control], and 118 +/- 20 at 24 hrs), and significantly reduced the increase in pulmonary microvascular shunt fraction (Qs/Qt; control group at BL, 0.14 +/- 0.02, and at 24 hrs, 0.65 +/- 0.08; rhAPC group at BL, 0.24 +/- 0.04, and at 24 hrs, 0.45 +/- 0.02 [p < .05 vs. control]) and the increase in peak airway pressure (mbar; control group at BL, 20 +/- 1, and at 24 hrs, 36 +/- 4; rhAPC group at BL, 21 +/- 1, and at 24 hrs, 28 +/- 2 [p < .05 vs. control]). In addition, rhAPC limited the increase in lung 3-nitrotyrosine (after 24 hrs [%]: sham, 7 +/- 2; control, 17 +/- 1; rhAPC, 12 +/- 1 [p < .05 vs. control]), a reliable indicator of tissue injury. However, rhAPC failed to prevent lung edema formation. RhAPC-treated sheep showed no difference in activated clotting time or platelet count but exhibited less fibrin degradation products (1/6 animals) than did controls (4/6 animals).

CONCLUSIONS

Recombinant human activated protein C attenuated ALI after smoke inhalation and bacterial challenge in sheep, without bleeding complications.

The inhibition of inducible nitric oxide synthase in ovine sepsis model

Excessive NO has been shown to play a major role in the pathogenesis of multiple organ dysfunctions in septic condition. Burn injury, especially if it is associated with smoke inhalation, is often complicated by subsequent development of pneumonia or sepsis that determine the outcome. In the present study, we developed an ovine sepsis model, created by exposing sheep to smoke inhalation followed by instillation of bacteria into the airway, that closely mimics human sepsis and pneumonia. We hypothesized that the inhibition of iNOS-derived excessive NO might be beneficial in treating the cardiopulmonary derangement in this model. Female sheep (n = 18) were surgically prepared for the study and given a tracheostomy. This was followed by insufflation of 48 breaths of cotton smoke (< 40 degrees C) into the airway of each animal and subsequent instillation of live Pseudomonas aeruginosa (5 x 10(11) colony forming units) into each sheep's lung. All sheep were mechanically ventilated using 100% O2. Continuous infusion of BBS-2 (100 microg/kg/h), an iNOS inhibitor, was started 1 h after insult. The administration of BBS-2 improved pulmonary gas exchange (PaO2/FiO2 and pulmonary shunt fraction) and partially reduced airway obstruction and an increase in ventilatory pressures. The lung water content was not affected by iNOS inhibition. The hypotension seen in nontreated animals was not ameliorated either. The increase in plasma concentration of nitrate and nitrite was inhibited by BBS-2. The results of present study show that iNOS may be partially involved in the pathogenesis of acute lung injury induced by smoke inhalation followed by bacterial instillation in the airway.

A phosphopantetheinyl transferase gene essential for biosynthesis of n-3 polyunsaturated fatty acids from Moritella marina strain MP-1

A phosphopantetheinyl transferase (PPTase) gene (pfaE), cloned from the docosahexaenoic acid (DHA)-producing bacterium Moritella marina strain MP-1, has an open reading frame of 861 bp encoding a 287-amino acid protein. When the pfaE gene was expressed with pfaA-D, which are four out of five essential genes for biosynthesis of eicosapentaenoic acid (EPA) derived from Shewanella pneumatophori SCRC-2738 in Escherichia coli, the recombinant produced 12% EPA of total fatty acids. This suggests that pfaE encodes a PPTase required for producing n-3 polyunsaturated fatty acids, which is probably involved in the synthesis of DHA in M. marina strain MP-1.

A metastatic haemangiopericytoma of the floor of the mouth

A case of metastatic haemangiopericytoma in the floor of the mouth is described. Haemangiopericytoma is a relatively rare slow-growing vascular tumour with variable malignant potential. This tumour has been identified in almost every region of the body, but its occurrence in the oral cavity has been rarely reported. The rate of regional and distant metastasis of the tumour is low. This case, presented 12 years after initial surgery suggested the need for careful long-term follow-ups of patients with haemangiopericytoma.

Combined burn and smoke inhalation injury impairs ovine hypoxic pulmonary vasoconstriction

OBJECTIVE

To examine the effects of combined burn and smoke inhalation injury on hypoxic pulmonary vasoconstriction, 3-nitrotyrosine formation, and respiratory function in adult sheep.

DESIGN

Prospective, placebo-controlled, randomized, single-blinded trial.

SETTING

University research laboratory.

SUBJECTS

Twelve chronically instrumented ewes.

INTERVENTIONS

Following a baseline measurement, sheep were randomly allocated to either healthy controls (sham) or the injury group, subjected to a 40%, third-degree body surface area burn and 48 breaths of cotton smoke according to an established protocol (n = 6 each). Hypoxic pulmonary vasoconstriction was assessed as changes in pulmonary arterial blood flow (corrected for changes in cardiac index) in response to left lung hypoxic challenges performed at baseline and at 24 and 48 hrs postinjury.

MEASUREMENTS AND MAIN RESULTS

Combined burn and smoke inhalation was associated with increased expression of inducible nitric oxide (NO) synthase, elevated NO2/NO3 (NOx) plasma levels (12 hrs, sham, 6.2 +/- 0.6; injury, 16 +/- 1.6 micromol.L; p < .01) and increased peroxynitrite formation, as indicated by augmented lung tissue 3-nitrotyrosine content (30 +/- 3 vs. 216 +/- 8 nM; p < .001). These biochemical changes occurred in parallel with pulmonary shunting, progressive decreases in Pao2/Fio2 ratio, and a loss of hypoxic pulmonary vasoconstriction (48 hrs, -90.5% vs. baseline; p < .001). Histopathology revealed pulmonary edema and airway obstruction as the morphologic correlates of the deterioration in gas exchange and the increases in airway pressures.

CONCLUSIONS

This study provides evidence for a severe impairment of hypoxic pulmonary vasoconstriction following combined burn and smoke inhalation injury. In addition to airway obstruction, the loss of hypoxic pulmonary vasoconstriction may help to explain why blood gases are within physiologic ranges for a certain time postinjury and then suddenly deteriorate.

Aerosolized alpha-tocopherol ameliorates acute lung injury following combined burn and smoke inhalation injury in sheep

Victims of fire accidents who sustain both thermal injury to the skin and smoke inhalation have gross evidence of oxidant injury. Therefore, we hypothesized that delivery of vitamin E, an oxygen superoxide scavenger, directly into the airway would attenuate acute lung injury postburn and smoke inhalation. Sheep (N = 17 female, 35 +/- 5 kg) were divided into 3 groups: (1) injured, then nebulized with vitamin E (B&S, Vitamin E, n = 6); (2) injured, nebulized with saline (B&S, Saline, n = 6); and (3) not injured, not treated (Sham, n = 5). While under deep anesthesia with isoflurane, the sheep were subjected to a flame burn (40% total body surface area, 3rd degree) and inhalation injury (48 breaths of cotton smoke, <40 degrees C). All groups were resuscitated with Ringer lactate solution (4 mL/kg/%burn/24 h) and placed on a ventilator [positive end-expiratory pressure (PEEP) = 5 cm H2O, tidal volume = 15 mL/kg] for 48 h. B&S injury halved the lung alpha-tocopherol concentrations (0.9 +/- 0.1 nmol/g) compared with sham-injured animals (1.5 +/- 0.3), whereas vitamin E treatment elevated the lung alpha-tocopherol concentrations (7.40 +/- 2.61) in the injured animals. B&S injury decreased pulmonary gas exchange (PaO2/FiO2 ratios) from 517 +/- 15 at baseline to 329 +/- 49 at 24 h and to 149 +/- 32 at 48 h compared with sham ratios of 477 +/- 14, 536 +/- 48, and 609 +/- 49, respectively. Vitamin E treatment resulted in a significant improvement of pulmonary gas exchange; ratios were 415 +/- 34 and 283 +/- 42 at 24 and 48 h, respectively. Vitamin E nebulization therapy improved the clinical responses to burn and smoke inhalation-induced acute lung injury.

Effect of inhaled nitric oxide on pulmonary vascular hyperpermeability in sheep following smoke inhalation

Smoke inhalation increases mortality and morbidity in burn patients. We have reported that smoke inhalation increases lung lymph flow, an index of pulmonary transvascular fluid flux and decreases reflection coefficient, an index of microvascular permeability to protein. Nitric oxide has been reported to decrease microvascular permeability to protein. We hypothesize that inhaled nitric oxide decreases pulmonary microvascular hyperpermeability following smoke inhalation. Sheep were prepared for study with a chronic lung lymph fistula, Swan-Ganz, left atrial, and femoral arterial catheters. Occluders were placed on pulmonary veins to measure reflection coefficient. All animals were insufflated with 4 x 12 breaths of cotton smoke. Sheep were randomly divided into two groups: NO (injured, treated with nitric oxide (40 ppm) inhalation, n=6) and control (injured, not treated, n=6). Nitric oxide inhalation was started 22 h after the insult. Control animals showed an increase in lung lymph flow, and lung water content. These changes were associated with marked increase in pulmonary microvascular resistance, pulmonary artery pressure, and decrease in reflection coefficient. Nitric oxide inhalation ameliorated the above-mentioned pathological changes. The results suggest that nitric oxide inhalation has potential for beneficial effect in the treatment of patients suffering from smoke inhalation.

GENTAMICIN IMPROVES HEMODYNAMICS IN OVINE SEPTIC SHOCK AFTER SMOKE INHALATION INJURY

Previously, our group developed an ovine model of hyperdynamic sepsis associated with acute lung injury. In this study, we sought to modify this sepsis model by the administration of gentamicin to more closely simulate the symptoms observed in human sepsis in the intensive care unit. In a prospective, controlled, randomized laboratory experiment, 18 female sheep were surgically prepared for chronic study. After a tracheotomy had been performed, the sheep were randomized into sham, control, and gentamicin groups (n = 6 each). Sham animals were surgically prepared for the study but were neither injured nor treated. Control and gentamicin animals received 48 breaths of cotton smoke (<40 degrees C) followed by the instillation (via a bronchoscope) of live Pseudomonas aeruginosa (2-5 x 10(11) colony-forming units) bacteria into the lung. All sheep were mechanically ventilated with 100% O2 for the duration of the 24-h experimental period. Gentamicin (2 mg/kg) was administered at 6, 12, and 18 h after injury. The animals were resuscitated with lactated Ringer's solution to maintain filling pressures and hematocrit on a constant level. Cardiopulmonary variables were stable in sham animals, but in the control group, cardiac index increased significantly after 24 h versus baseline (BL, 5.1 +/- 0.4 L.min(-1).m(-2) vs. 24 h, 7.3 +/- 0.7 L.min(-1).m(-2); P < 0.05); this was associated with a significant drop in mean arterial pressure (BL, 95 +/- 3 mmHg vs. 24 h, 65 +/- 4 mmHg, P < 0.05) and systemic vascular resistance index (BL, 1410 +/- 118 dynes s.cm.m vs. 24 h, 598 +/- 101 dynes s.cm.m, P < 0.05). Treatment with gentamicin stabilized cardiac index (BL, 5.0 +/- 0.4 L.min(-1).m(-2) vs. 24 h, 4.7 +/- 0.4 L.min(-1).m(-2)) and attenuated the decrease in mean arterial pressure (BL, 99 +/- 3 mmHg vs. 24 h, 84 +/- 4 mmHg) and systemic vascular resistance index (BL, 1573 +/- 173 dynes s.cm.m vs. 24 h, 1263 +/- 187 dynes s.cm.m). In addition, the fluid requirement in the gentamicin group was significantly lower than in the control group. Pulmonary function remained stable in sham animals, but the PaO2/FiO2 ratio and shunt fraction deteriorated similarly in the control and the gentamicin groups. Because gentamicin improved hemodynamic variables and reduced the fluid requirement in this ovine model, we believe that this modified sepsis model might provide a clinically relevant and useful new approach for future studies focusing on hemodynamic variables and outcome.