Critical care ultrasound in geriatric trauma resuscitation leads to decreased fluid administration and ventilator days

BACKGROUND

Geriatric trauma populations respond differently than younger trauma populations. Critical care ultrasound (CCUS) can guide resuscitation, and it has been shown to decrease intravenous fluid (IVF), lower time until operation, and lower mortality in trauma. Critical care ultrasound-guided resuscitation has not yet been studied in geriatric trauma. We hypothesized that incorporation of CCUS would decrease amount of IVF administered, decrease time to initiation of vasopressors, and decrease end organ dysfunction.

METHODS

A PRE-CCUS geriatric trauma group between January 2015 and October 2016 was resuscitated per standard practice. A POST-CCUS group between January 2017 and December 2018 was resuscitated based on CCUS performed by trained intensivist upon admission to the intensive care unit and 6 hours after initial ultrasound. The PRE-CCUS and POST-CCUS groups underwent propensity score matching, yielding 60 enrollees in each arm. Retrospective review was conducted for demographics, clinical outcomes, and primary endpoints, including amount of IVF in the first 48 hours, duration to initiation of vasopressor use, and end organ dysfunction. Wilcoxon two-sample, χ2 tests, and κ statistics were performed to check associations between groups.

RESULTS

There was no statistical difference between PRE-CCUS and POST-CCUS demographics and Injury Severity Scores. Intravenous fluid within 48 hours decreased from median [interquartile range] of 4941 mL [4019 mL] in the PRE-CCUS to 2633 mL [3671 mL] in the POST-CCUS (p = 0.0003). There was no significant difference between the two groups in time to initiation of vasopressors, vasopressor duration, lactate clearance, intensive care unit length of stay, or hospital length of stay. There was a significant decrease in ventilator days, with 26.7% PRE-CCUS with ventilation longer than 2 days, and only 6.7% POST-CCUS requiring ventilation longer than 2 days (p = 0.0033).

CONCLUSION

Critical care ultrasound can be a useful addition to geriatric resuscitation. The POST-CCUS received less IV fluid and had decreased ventilator days. While mortality, lactate clearance, complications, and hospital stay were not statistically different, there was a perception that CCUS was a useful adjunct for assessing volume status and cardiac function.

LEVEL OF EVIDENCE

Therapeutic, level II.

Endovascular Graft Repair for Blunt Traumatic Disruption of the Thoracic Aorta: Experience at a Nonuniversity Hospital

Blunt thoracic aortic injury (BAI) represents the second leading cause of death from blunt trauma. Admission rates for BAI are extremely low because instant fatality occurs in nearly 75 per cent of patients. Management strategies have transitioned from the more invasive immediate thoracotomy to delayed endograft repair with strict hemodynamic management. In this study, we assess outcomes and complications of open versus endograft repair for BAI at a nonuniversity hospital. Retrospective chart review was conducted on 49 patients admitted to a Level I trauma center who incurred BAI from 2004 to 2011. Collected data points included demographics, mortality, complication rates, and intensive care unit and hospital length of stay (LOS). Twenty-one patients underwent open thoracotomy (OPEN), whereas 28 patients were managed with thoracic endovascular aortic repair (TEVAR). The overall 30-day mortality rate was significantly lower comparing TEVAR to OPEN (7.1 vs 50%, P = 0.028); seven deaths occurred in the OPEN group versus two with TEVAR. Overall complications, including mortality, acute respiratory distress syndrome, renal failure, pneumonia, pulmonary embolism, and cardiac arrest, were fewer after TEVAR (32.1 vs 81.0%, P < 0.001) despite similar injury severity. Survivor hospital LOS (26.0 ± 15.3 vs 27.7 ± 18.7 days, P = 0.79), intensive care unit LOS (13.5 ± 10.9 vs 12.7 ± 8.8 days, P = 0.94), and ventilator days (11.4 ± 13.4 vs 16.4 ± 14.5 days, P = 0.25) were similar. Early nonoperative management with TEVAR for BAIs is a feasible and effective management strategy. Improved patient outcomes over traditional open thoracotomy in the presence of similar injury severity can be seen after TEVAR in the nonuniversity hospital setting.

Efficacy of Oscillation and Lung Expansion in Reducing Postoperative Pulmonary Complication

BACKGROUND

Postoperative pulmonary complications (PPCs) cause high morbidity and mortality. Targeted treatment for patients at risk for PPCs can improve outcomes. This multicenter prospective trial examined the impact of oscillation and lung expansion (OLE) therapy, using continuous high-frequency oscillation and continuous positive expiratory pressure on PPCs in high-risk patients.

METHODS

In stage I, CPT and ICD codes were queried for patients (n = 210) undergoing thoracic, upper abdominal, or aortic open procedures at 3 institutions from December 2014 to April 2016. Patients were selected randomly. Age, comorbidities, American Society of Anesthesiologists physical status classification scores, and PPC rates were determined. In stage II, 209 subjects were enrolled prospectively from October 2016 to July 2017 using the same criteria. Stage II subjects received OLE treatment and standard respiratory care. The PPCs rate (prolonged ventilation, high-level respiratory support, pneumonia, ICU readmission) were compared. We also compared ICU length of stay (LOS), hospital LOS, and mortality using t-tests and analysis of covariance. Data are mean ± SD.

RESULTS

There were 419 subjects. Stage II patients were older (61.1 ± 13.7 years vs 57.4 ± 15.5 years; p < 0.05) and had higher American Society of Anesthesiologists scores. Treatment with OLE decreased PPCs from 22.9% (stage I) to 15.8% (stage II) (p < 0.01 adjusted for age, American Society of Anesthesiologists score, and operation time). Similarly, OLE treatment reduced ventilator time (23.7 ± 107.5 hours to 8.5 ± 27.5 hours; p < 0.05) and hospital LOS (8.4 ± 7.9 days to 6.8 ± 5.0 days; p < 0.05). No differences in ICU LOS, pneumonia, or mortality were observed.

CONCLUSIONS

Aggressive treatment with OLE reduces PPCs and resource use in high-risk surgical patients.

Impact of Multiprofessional Rounds on Critical Care Outcomes in the Surgical Trauma Intensive Care Unit

Multiprofessional rounds (MPR) represent a mechanism for the coordination of care in critically ill patients. Herein, we examined the impact of MPR on ventilator days (Vent-day), ICU length of stay (LOS), hospital LOS (HLOS), and mortality. A team developed guidelines for MPR, which began in February 2016. Patients admitted between November 2015 and March 2017 with Acute Physiology and Chronic Health Evaluation (APACHE) IV and injury severity scores were included. Outcome data consisted of Vent-day, Vent-day observed/expected ratio (O/E), ICU LOS, ICU LOS O/E, HLOS, HLOS-O/E, and mortality. Linear regression models are constructed to assess statistical significance. A total of 3372 patients were included. Among surgical patients (n = 343 pre-MPR, n = 1675 post-MPR), MPR was associated with decreases in Vent-day O/E (0.74 pre, 0.59 post, P = 0.03), ICU LOS O/E (0.67 pre, 0.61 post, P = 0.01), and HLOS-O/E (1.47 pre, 1.22 post, P = 0.0005). No mortality difference was observed. For trauma patients (n = 221 pre, n = 1133 post), MPR resulted in a reduction in Vent-days (2.2 days pre, 1.6 days post, P = 0.05). However, no differences were observed for Vent-day O/E, ICU LOS O/E, HLOS-O/E, and mortality. Implementation of MPR was associated with improved outcomes for surgical trauma ICU patients. Sustainability of MPR remains a challenge and requires education and engagement.

Impact of Multiprofessional Rounds on Critical Care Outcomes in the Surgical Trauma Intensive Care Unit

Multiprofessional rounds (MPR) represent a mechanism for the coordination of care in critically ill patients. Herein, we examined the impact of MPR on ventilator days (Vent-day), ICU length of stay (LOS), hospital LOS (HLOS), and mortality. A team developed guidelines for MPR, which began in February 2016. Patients admitted between November 2015 and March 2017 with Acute Physiology and Chronic Health Evaluation (APACHE) IV and injury severity scores were included. Outcome data consisted of Vent-day, Vent-day observed/expected ratio (O/E), ICU LOS, ICU LOS O/E, HLOS, HLOS-O/E, and mortality. Linear regression models are constructed to assess statistical significance. A total of 3372 patients were included. Among surgical patients (n = 343 pre-MPR, n = 1675 post-MPR), MPR was associated with decreases in Vent-day O/E (0.74 pre, 0.59 post, P = 0.03), ICU LOS O/E (0.67 pre, 0.61 post, P = 0.01), and HLOS-O/E (1.47 pre, 1.22 post, P = 0.0005). No mortality difference was observed. For trauma patients (n = 221 pre, n = 1133 post), MPR resulted in a reduction in Vent-days (2.2 days pre, 1.6 days post, P = 0.05). However, no differences were observed for Vent-day O/E, ICU LOS O/E, HLOS-O/E, and mortality. Implementation of MPR was associated with improved outcomes for surgical trauma ICU patients. Sustainability of MPR remains a challenge and requires education and engagement.

Does history of substance use disorder predict acute traumatic brain injury rehabilitation outcomes?

BACKGROUND/OBJECTIVE

The study explored whether premorbid substance use disorder (SUD) predicts acute traumatic brain injury (TBI) outcomes.

METHODS

143 participants with moderate (34.2%) and severe (65.8%) TBI were enrolled at two Level 1 trauma center inpatient brain injury rehabilitation units. Acute outcomes were measured with the Disability Rating Scale (DRS), the FIMTM; self and informant ratings of the Patient Competency Rating Scale (PCRS); self and family rating of the Frontal Systems Behavioral Scale (FrSBe), and the Neurobehavioral Rating Scale-Revised (NRS-R).

RESULTS

Hierarchical linear modeling revealed that SUD history significantly predicted trajectories of PCRS clinician ratings, PCRS self-family and PCRS self-clinician discrepancy scores, and more negative FrSBE family ratings. These findings indicate comparatively greater post-injury executive functions (EF) impairments, particularly self-awareness (SA) of injury-related deficits, for those with SUD history. No significant SUD*time interaction effect was found for FIM or NRS-R scores.

CONCLUSIONS

SUD history and TBI are associated with impaired SA and EF but their co-occurrence is not a consistent predictor of acute post-injury functional outcomes. Pre-morbid patient characteristics and rater expectations and biases may moderate associations between SA and recovery after TBI.

Phase-aware echocardiogram stabilization using keyframes

This paper presents an echocardiogram stabilization method designed to compensate for unwanted auxilliary motion. Echocardiograms contain both deformable cardiac motion and approximately rigid motion due to a number of factors. The goal of this work is to stabilize the video, while preserving the informative deformable cardiac motion. Our approach incorporates synchronized side information, extracted from electrocardiography (ECG), which provides a proxy for cardiac phase. To avoid the computational expense of pairwise alignment, we propose an efficient strategy for keyframe selection, formulated as a submodular optimization problem. We evaluate our approach quantitatively on synthetic data and demonstrate its benefit as a preprocessing step for two common echocardiogram applications: denoising and left ventricle segmentation. In both cases, preprocessing with our method improved the performance compared to no preprocessing or other alignment approaches.

Delays in transfer of elderly less-injured trauma patients can have deadly consequences

Transfer of severely injured patients to regional trauma centers is often expedited; however, transfer of less-injured, older patients may not evoke the same urgency. We examined referring hospitals' length of stay (LOS) and compared the subsequent outcomes in less-injured transfer patients (TP) with patients presenting directly (DP) to the trauma center. We reviewed the medical records of less-injured (Injury Severity Score [ISS] 9 or less), older (age older than 60 years) patients transferred to a regional Level 1 trauma center to determine the referring facility LOS, demographics, and injury information. Outcomes of the TP were then compared with similarly injured DP using local trauma registry data. In 2011, there were 1657 transfers; the referring facility LOS averaged greater than 3 hours. In the less-injured patients (ISS 9 or less), the average referring facility LOS was 3 hours 20 minutes compared with 2 hours 24 minutes in more severely injured patients (ISS 25 or greater, P < 0.05). The mortality was significantly lower in the DP patients (5.8% TP vs 2.6% DP, P = 0.035). Delays in transfer of less-injured, older trauma patients can result in poor outcomes including increased mortality. Geographic challenges do not allow for every patient to be transported directly to a trauma center. As a result, we propose further outreach efforts to identify potential causes for delay and to promote compliance with regional referral guidelines.

Delays in Transfer of Elderly Less-injured Trauma Patients Can Have Deadly Consequences

Transfer of severely injured patients to regional trauma centers is often expedited; however, transfer of less-injured, older patients may not evoke the same urgency. We examined referring hospitals’ length of stay (LOS) and compared the subsequent outcomes in less-injured transfer patients (TP) with patients presenting directly (DP) to the trauma center. We reviewed the medical records of less-injured (Injury Severity Score [ISS] 9 or less), older (age older than 60 years) patients transferred to a regional Level 1 trauma center to determine the referring facility LOS, demographics, and injury information. Outcomes of the TP were then compared with similarly injured DP using local trauma registry data. In 2011, there were 1657 transfers; the referring facility LOS averaged greater than 3 hours. In the less-injured patients (ISS 9 or less), the average referring facility LOS was 3 hours 20 minutes compared with 2 hours 24 minutes in more severely injured patients (ISS 25 or greater, P < 0.05). The mortality was significantly lower in the DP patients (5.8% TP vs 2.6% DP, P = 0.035). Delays in transfer of less-injured, older trauma patients can result in poor outcomes including increased mortality. Geographic challenges do not allow for every patient to be transported directly to a trauma center. As a result, we propose further outreach efforts to identify potential causes for delay and to promote compliance with regional referral guidelines.

Endovascular graft repair for blunt traumatic disruption of the thoracic aorta: experience at a nonuniversity hospital

Blunt thoracic aortic injury (BAI) represents the second leading cause of death from blunt trauma. Admission rates for BAI are extremely low because instant fatality occurs in nearly 75 per cent of patients. Management strategies have transitioned from the more invasive immediate thoracotomy to delayed endograft repair with strict hemodynamic management. In this study, we assess outcomes and complications of open versus endograft repair for BAI at a nonuniversity hospital. Retrospective chart review was conducted on 49 patients admitted to a Level I trauma center who incurred BAI from 2004 to 2011. Collected data points included demographics, mortality, complication rates, and intensive care unit and hospital length of stay (LOS). Twenty-one patients underwent open thoracotomy (OPEN), whereas 28 patients were managed with thoracic endovascular aortic repair (TEVAR). The overall 30-day mortality rate was significantly lower comparing TEVAR to OPEN (7.1 vs 50%, P = 0.028); seven deaths occurred in the OPEN group versus two with TEVAR. Overall complications, including mortality, acute respiratory distress syndrome, renal failure, pneumonia, pulmonary embolism, and cardiac arrest, were fewer after TEVAR (32.1 vs 81.0%, P < 0.001) despite similar injury severity. Survivor hospital LOS (26.0 ± 15.3 vs 27.7 ± 18.7 days, P = 0.79), intensive care unit LOS (13.5 ± 10.9 vs 12.7 ± 8.8 days, P = 0.94), and ventilator days (11.4 ± 13.4 vs 16.4 ± 14.5 days, P = 0.25) were similar. Early nonoperative management with TEVAR for BAIs is a feasible and effective management strategy. Improved patient outcomes over traditional open thoracotomy in the presence of similar injury severity can be seen after TEVAR in the nonuniversity hospital setting.

Phytoextraction of heavy metals by willows growing in biosolids under field conditions

Biosolids produced by sewage treatment facilities can exceed guideline thresholds for contaminant elements. Phytoextraction is one technique with the potential to reduce these elements allowing reuse of the biosolids as a soil amendment. In this field trial, cuttings of seven species/cultivars of Salix(willows) were planted directly into soil and into biosolids to identify their suitability for decontaminating biosolids. Trees were irrigated and harvested each year for three consecutive years. Harvested biomass was weighed and analyzed for the contaminant elements: As, Cd, Cu, Cr, Hg, Pb, Ni, and Zn. All Salix cultivars, except S. chilensis, growing in soils produced 10 to 20 t ha(-1) of biomass, whereas most Salix cultivars growing in biosolids produced significantly less biomass (<6 t ha(-1)). Salix matsudana (30 t ha(-1)) and S. × reichardtii A. Kerner (18 t ha(-1)) had similar aboveground biomass production in both soil and biosolids. These were also the most successful cultivars in extracting metals from biosolids, driven by superior biomass increases and not high tissue concentrations. The willows were effectual in extracting the most soluble/exchangeable metals (Cd, 0.18; Ni, 0.40; and Zn, 11.66 kg ha(-1)), whereas Cr and Cu were extracted to a lesser degree (0.02 and 0.11 kg ha(-1)). Low bioavailable elements, As, Hg, and Pb, were not detectable in any of the aboveground biomass of the willows.

Effects of serum-free storage on morphology, phenotype, and viability of ex vivo cultured human conjunctival epithelium

The use of amniotic membrane (AM) represents one of the major developments in ocular surface reconstruction. However, in a study on patients with primary pterygium, transplantation of AM with ex vivo expanded human conjunctival epithelial cells (HCjE) promoted earlier epithelialization than AM alone. We previously showed that cultured human limbal epithelial cells maintain their morphology, phenotype, and viability for one week when stored at 23°C. The current study investigates the feasibility of storing HCjE in HEPES-MEM and Optisol-GS at 23°C for 4 and 7 days, respectively. The five experimental groups were analyzed by light microscopy, immunohistochemistry, transmission electron microscopy, and a viability assay. The ultrastructural integrity of cultured HCjE was well preserved following 4 days of storage, however, 7 days of storage resulted in some loss of cell-cell contacts and epithelial detachment from the amniotic membrane. The number of microvilli in cultured HCjE not subjected to storage was 2.03±0.38 microvilli/μm. In comparison, after 4 and 7 days of HEPES-MEM storage this number was 1.69±0.54 microvilli/μm; P=0.98 and 0.89±1.0 microvilli/μm; P=0.28, respectively. After Optisol-GS storage for 4 and 7 days, the mean number of microvilli was 1.07±1.0 microvilli/μm; P=0.47 and 0.07±0.07 microvilli/μm; P=0.03, respectively. The number of cell layers in cultured HCjE not subjected to storage was 4.4±0.3 cell layers, as opposed to 4.0±0.9 cell layers; P=0.89 after 4 days of HEPES-MEM storage and 2.8±0.6 cell layers; P=0.01 after 7 days of storage in HEPES-MEM. The number of cell layers after 4 and 7 days of storage in Optisol-GS was 3.7±0.2 cell layers; P=0.46 and 3.4±0.4 cell layers; P=0.18, respectively. The expression of markers for undifferentiated cells (ΔNp63α, ABCG2 and p63), proliferating cells (Ki67 and PCNA), goblet cells (Ck7 and MUC5AC), stratified squamous epithelial cells (Ck4), and apoptotic cells (caspase-3) in cultured HCjE appeared to be unchanged after 4 and 7 days of HEPES-MEM and Optisol-GS storage. The percentage of viable cells in cultured HCjE not subjected to storage (91.4%±3.2%) was sustained after 4 and 7 days of storage in HEPES-MEM (94.1%±4.5%; P=0.99 and 85.1%±13.7%; P=0.87, respectively) as well as after 4 and 7 days of storage in Optisol-GS (87.7%±15.2%; P=0.97 and 79.8%±15.7%; P=0.48, respectively). We conclude that cultured HCjE may be stored for at least 4 days in serum-free conditions at 23°C while maintaining the phenotype and viability. HEPES-MEM appears to be comparable to Optisol-GS for serum-free storage with preservation of the ultrastructure for at least 4 days.

Tracking colliding cells in vivo microscopy

Leukocyte motion represents an important component in the innate immune response to infection. Intravital microscopy is a powerful tool as it enables in vivo imaging of leukocyte motion. Under inflammatory conditions, leukocytes may exhibit various motion behaviors, such as flowing, rolling, and adhering. With many leukocytes moving at a wide range of speeds, collisions occur. These collisions result in abrupt changes in the motion and appearance of leukocytes. Manual analysis is tedious, error prone,time consuming, and could introduce technician-related bias. Automatic tracking is also challenging due to the noise inherent in in vivo images and abrupt changes in motion and appearance due to collision. This paper presents a method to automatically track multiple cells undergoing collisions by modeling the appearance and motion for each collision state and testing collision hypotheses of possible transitions between states. The tracking results are demonstrated using in vivo intravital microscopy image sequences.We demonstrate that 1)71% of colliding cells are correctly tracked; (2) the improvement of the proposed method is enhanced when the duration of collision increases; and (3) given good detection results, the proposed method can correctly track 88% of colliding cells. The method minimizes the tracking failures under collisions and, therefore, allows more robust analysis in the study of leukocyte behaviors responding to inflammatory conditions.

Removal of erythropoietin from anaemia trauma practice guideline does not increase red blood cell transfusions and decreases hospital utilization costs

INTRODUCTION

We previously demonstrated that utilization of erythropoietin (r-EPO) did not significantly reduce blood utilization in trauma patients. We undertook this study to analyze blood utilization 1 year after r-EPO removal from our trauma service anaemia practice management guideline.

METHODS

Electronic records of patients admitted to the trauma service were retrospectively reviewed for units of packed red blood cells (pRBCs) transfused and for units of r-EPO administered 12 months before the initiation of an anaemia practice guideline (PRE), 12 months during the use of an anaemia guideline (GUIDE), and 12 months following removal of r-EPO from the guideline (POST). Hospital acquisition cost was also reviewed for the respective time periods. Nominal data were analyzed using chi-squared or Fisher's exact tests, and interval data were compared using ANOVA followed by Tukey's test where appropriate. Results were considered significant for P<0.05.

RESULTS

Over the 3-year study period, 4881 patients were admitted to the trauma service and included in this study. The hospital length of stay, intensive care unit length of stay, and units of pRBC transfused were similar among all three groups. Group I (PRE) received a total of 228 doses of r-EPO at a cost of $102,600. Group II (GUIDE) received a total of 410 doses at a cost of $184,500. Group III (POST) received 28 doses of r-EPO at a cost of $12,600.

CONCLUSION

Removal of erythropoietin from our trauma service anaemia practice management guideline did not result in increased blood utilization. However, it yielded a hospital acquisition cost savings of $171,900.

Clinical outcomes of mesenteric artery stenting versus surgical revascularization in chronic mesenteric ischemia

AIM

Endovascular stenting of atherosclerotic lesions has become a common practice and widely accepted treatment strategy in the treatment of arterial occlusive disease. This study examines the clinical outcome of mesenteric stenting and open mesenteric revascularization for chronic mesenteric ischemia (CMI).

METHODS

Hospital records and clinical data of all patients undergoing surgical or endovascular interventions for CMI were reviewed during a recent 10-year period. Clinical outcomes were analyzed between the two groups.

RESULTS

Endovascular treatment was performed in 48 patients (58 vessels), and open repair was performed in 96 patients (157 vessels) during the study period. The mean age in the endovascular group was greater than the open group (74+/-9 vs 62+/-7 years, P<0.05). There was no difference in comorbidities, symptom duration, or treatment indications between the two groups. Among patients treated with surgical revascularization, operative strategies included bypass grafting (N.=72, 75%); transaortic endarterectomy (N.=19, 20%), or patch angioplasty (N.=5, 5%). In the open group, one-vessel and two-vessel revascularization was performed in 36% and 64% of patients, respectively. In the endovascular cohorts, one-vessel and two-vessel balloon angioplasty and/or stenting were performed in 79% and 21% of patients, respectively. The hospital length of stay was shorter in the endovascular group (3 vs 12 days, P<0.03). There was no difference in 30-day mortality, in-hospital complication, or three-year cumulative survival rate. Cumulative freedom from recurrent symptoms at three years were significantly greater in the open group (66%) compared to the endovascular group (27%, P<0.02).

CONCLUSIONS

Endovascular treatment offers a benefit of shorter hospitalization compared to the open revascularization, while both groups had similar morbidity and mortality rates. Patients treated with surgical reconstruction were more likely to experience long-term symptomatic relief compared to endovascular cohorts, possibly due to higher incidence of two-vessel surgical revascularization. Long term durability of endovascular intervention may be improved with two-vessel revascularization.

Effects of phytoextraction on heavy metal concentrations and pH of pore-water of biosolids determined using an in situ sampling technique

Heavy metal concentrations and pH of pore-water in contaminated substrates are important factors in controlling metal uptake by plants. We investigated the effects of phytoextraction on these properties in the solution phase of biosolids and diluted biosolids in a 12-month phytoextraction column experiment. Phytoextraction using Salix and Populus spp. temporarily decreased pore-water pH of the substrates over the experimental period followed by a return to initial pH conditions. Salixxreichardtii and Populus balsamifera effectively extracted Ni, Zn and Cd and actively mobilized these metals from the solid to the solution phase. S.xreichardtii had the stronger effect on mobilization of metals due to its larger root system. Phytoextraction did not affect Cu in the solution phase of the biosolids. Heavy metals were leached down to lower depths of the columns during the phytoextraction process.

Mechanical stretch has contrasting effects on mediator release from bronchial epithelial cells, with a rho-kinase-dependent component to the mechanotransduction pathway

INTRODUCTION

In vivo, the airway epithelium stretches and relaxes with each respiratory cycle, but little is known about the effect this pattern of elongation and relaxation has on bronchial epithelial cells. We have used a model of cell deformation to measure the effect of stretch on inflammatory cytokine release by the BEAS 2B cell line, and to examine the method of mechanotransduction in these cells.

METHODS

BEAS 2B cells were cyclically stretched using the Flexercell system. IL-8 and RANTES protein and RNA levels were measured after different elongations, rates and duration of stretch. An inhibitor of Rho (Ras Homologous)-associated kinases was used, to assess the effect of blocking downstream of integrin signalling. Immunofluorescent staining of paxillin was used to study the effect of stretch on the distribution of focal contacts and the organisation of the actin cytoskeleton.

RESULTS

IL-8 release by BEAS 2B cells was increased by cytokine stimulation and stretch, whereas RANTES levels in the cell supernatant decreased after stretch in a dose-, time- and rate-dependent manner. Thirty percent elongation at 20 cycles/min for 24h increased IL-8 levels by over 100% (P < 0.01). Blocking rho kinase using Y-27632 inhibited the effect of stretch on IL-8 release by the BEAS 2B cells. Immunofluorescent staining demonstrated that stretch caused dramatic disassembly of focal adhesions and resulted in the redistribution of paxillin to the peri-nuclear region.

CONCLUSION

This study demonstrates a marked effect of stretch on bronchial epithelial cell function. We propose that stretch modulates epithelial cell function via the activation of rho kinases. The observation that stretch promotes focal adhesion disassembly suggests a mechanism whereby focal adhesion turnover (coordination of assembly and disassembly) is essential for mechanotransduction in bronchial epithelial cells.

Expression of CXCR6 and its ligand CXCL16 in the lung in health and disease

BACKGROUND

Chemokine receptors (CR) play an important role in T cell migration, but their contribution to lung trafficking is unclear.

OBJECTIVE

We hypothesized that if a particular CR was involved in T cell homing its expression would be enriched on lung T cells compared with peripheral blood T cells (PBT).

METHODS

We have measured the CR expression on BAL T cells from patients with sarcoid, other interstitial lung diseases (ILD), asthma and healthy volunteers.

RESULTS

Of 14 CR studied in sarcoid, CXCR6 expression was the most markedly increased in the lung compared with the blood, a finding that was also seen in ILD patients. A striking although lesser increase was also seen in asthmatics and healthy controls. Analysis of expression of the CXCR6 ligand, CXCL16, by immunohistochemistry suggested that alveolar macrophages (AM) were the major source of CXCL16 in the lung. AM expressed mRNA for CXCL16 and released nanogram quantities after adhesion to plastic as shown by RT-PCR, Western blotting and ELISA. Bronchoalveolar lavage (BAL) fluid from all subjects contained large amounts of CXCL16. The full-length CXCL16 was the predominant isoform in AM lysates, supernatants and BAL.

CONCLUSION

This data suggests that CXCR6 and CXCL16 may play a role in T cell recruitment to the lung.

The Role of Transesophageal Echocardiography in Optimizing Resuscitation in Acutely Injured Patients

BACKGROUND

The goal of resuscitation is to correct the mismatch between oxygen delivery and that of cellular demands. The pulmonary artery catheter (PAC) is frequently used to gauge the adequacy of resuscitation and guide therapy based on ventricular filling pressures. Transesophageal echocardiography (TEE) has emerged as a potential tool in assessing adequacy of acute hemodynamic resuscitation. The purpose of this study was to evaluate the role of TEE in assessing preload during ongoing volume resuscitation in trauma patients.

METHODS

A retrospective review was conducted of acutely injured patients undergoing TEE during resuscitation from hemorrhagic shock from January 2002 to 2004 at a Level I trauma center. The indication for TEE was persistent hemodynamic instability in the absence of ongoing surgical hemorrhage. Variables included hemodynamic and PAC parameters, pre-TEE resuscitation volume, and vasopressor requirements. The impact of TEE findings on therapeutic decisions was evaluated.

RESULTS

Twenty-five patients underwent TEE, 18 (72%) had an indwelling PAC with a mean pulmonary artery occlusion pressure of 19.3 mm Hg (range, 12-29 mm Hg) and mean cardiac index of 2.9 L/min/m2 (range, 1.6-4.6 L/min/m2). Twelve patients (48%) were receiving inotropes and/or vasopressors for hypotension at the time of TEE. Resuscitation volume within 6 hours before TEE included a mean of 6.5 L of crystalloid and 12.2 units of blood products (packed red blood cells, fresh frozen plasma, and platelets). TEE revealed left ventricular hypovolemia in 13 patients (52%) and altered therapy in 16 patients (64%), including additional volume (n = 13), addition of an inotrope (n = 4), and addition of a vasodilator (n = 1) in one patient with ventricular overdistention. Comparison of the abnormal and normal TEE groups revealed that only cardiac index was significantly different (2.6 L/min/m2 in the abnormal group vs. 3.9 L/min/m2 in the normal group; p = 0.005). Significant mitral valve regurgitation leading to valve replacement was identified in one patient. No clinically relevant pericardial effusion was identified.

CONCLUSION

TEE altered resuscitation management in almost two thirds of patients. Many patients with "acceptable" pulmonary artery occlusion pressure parameters may in fact have inadequate left ventricular filling. In addition, TEE offers the advantage of direct assessment of cardiac valve competency, myocardial wall contractility, and pericardial fluid.

Perflubron emulsion improves hepatic microvascular integrity and mitochondrial redox state after hemorrhagic shock

Hemorrhagic shock is associated with decreased systemic oxygen delivery, but also with impaired microvascular perfusion, which can result in diminished local oxygen availability even in the presence of adequate cardiac output after resuscitation. Beside surgical interventions to control blood loss, transfusion of stored packed red blood cells represents the current standard of care in the management of severe hemorrhagic shock. Because stored red blood cells are less deformable and show a higher O2 affinity that affects the O2 off-load to tissues, perfluorocarbon-based artificial oxygen carriers might improve local O2 delivery under these conditions. To test this, rats were subjected to hemorrhagic shock (1 h, mean arterial pressure [MAP] 30-35 mmHg) and were resuscitated with fresh whole blood, pentastarch, stored red blood cells, perflubron emulsion (2.7 and 5.4 g/kg body weight) together with pentastarch, or stored red blood cells together with 2.7 g/kg perflubron emulsion. Hepatic microcirculation, tissue oxygenation, and mitochondrial redox state were investigated by intravital microscopy. In addition, hepatocellular function and liver enzyme release were determined. After hemorrhagic shock and resuscitation with perflubron emulsion, volumetric sinusoidal blood flow was significantly increased compared with resuscitation with stored red blood cells. Furthermore, resuscitation with perflubron emulsion resulted in higher hepatic tissue PO2 and normalized mitochondrial redox potential, which was accompanied by lessened hepatocellular injury as well as improved liver function. These results indicate that, in this model of hemorrhagic shock, asanguineous fluid resuscitation with addition of perflubron emulsion is superior to stored blood or pentastarch alone with respect to increased local O2 availability on the cellular level. This effect is primarily due to improved restoration of hepatic microcirculatory integrity.

High-resolution visualization of oxygen distribution in the liver in vivo

Microcirculatory failure after stress events results in mismatch in oxygen supply and demand. Determination of tissue oxygen distribution in vivo may help elucidate mechanisms of injury, but present methods have limited resolution. Male Sprague-Dawley rats were anesthetized, prepared for intravital microscopy, and received intravenously the oxygen-sensitive fluorescent dye Tris(1,10-phenanthroline)ruthenium(II) chloride hydrate [Ru(phen)3(2+)]. An impaired hepatic oxygen distribution was induced by either phenylephrine or hemorrhage. Intensity of Ru(phen)3(2+) fluorescence was compared with NADH autofluorescence indicating changes in the mitochondrial redox potential. Ethanol was injected to affect the NADH-to-NAD+ ratio without altering the P(O2). Infusion of Ru(phen)3(2+) resulted in a heterogeneous fluorescence under baseline conditions reflecting the physiological acinar P(O2) distribution. A decrease in oxygen supply due to phenylephrine or hemorrhage was paralleled by an increase in Ru(phen)3(2+) and NADH fluorescence reflecting an impaired mitochondrial redox state. Ethanol did not alter Ru(phen)3(2+) fluorescence but increased NADH fluorescence indicating independence of P(O2) and redox state imaging. Intravenous administration of Ru(phen)3(2+) for intravital videomicroscopy represents a new method to visualize the hepatic tissue P(O2). Combined with NADH autofluorescence, it provides additional information regarding the tissue redox state.

Functional Link Between ETBReceptors and eNOS Maintain Tissue Oxygenation in the Normal Liver

OBJECTIVE

Endothelins and their receptors play a crucial role in regulating liver microcirculation in pathophysiological conditions. The authors investigated the functional significance of the coupling of ET(B) receptors and eNOS in maintaining regional perfusion and tissue oxygenation in the normal liver.

METHODS

The effect of endothelin-1 or the ET(B) agonist IRL1620 on oxygen consumption was determined in isolated perfused liver and isolated hepatocytes. Oxygen delivery to the liver tissue was determined in vivo. Following eNOS or iNOS blockade, either ET-1 or IRL1620 was infused via the portal vein. Hepatic tissue oxygenation, redox state, and microcirculation were investigated by intravital microscopy. Injury was estimated by serum LDH.

RESULTS

Although IRL1620 and endothelin-1 increased oxygen consumption in isolated hepatocytes, in intact liver, endothelin decreased oxygen consumption while IRL1620 produced no change. In vivo, ET(B) stimulation modestly altered hepatic tissue P(O(2)), redox potential, and microcirculation. eNOS inhibition and ET(B) activation dramatically reduced microcirculatory blood flow, oxygen supply, and increased LDH release. Inhibition of iNOS resulted in small but not significant changes in these parameters. Concomitant ET(A)/ET(B) receptor activation increased microcirculatory failure and decreased tissue oxygen even without NOS inhibition. In contrast, hepatocellular injury was significantly increased following eNOS inhibition.

CONCLUSIONS

Coupling between ET(B) receptor stimulation and eNOS activation decreases sinusoidal constriction and plays a functionally important role in maintaining microcirculation and tissue oxygenation in the normal liver.

Kaempferol-induced growth inhibition and apoptosis in A549 lung cancer cells is mediated by activation of MEK-MAPK

A vast variety of naturally occurring substances have been shown to protect against experimental carcinogenesis and an increasing amount of evidence suggests that kaempferol may have cancer chemopreventative properties. However, the precise underlying protective mechanisms are poorly understood. To elucidate these mechanisms, we challenged human lung cancer cell line A549 with kaempferol and investigated its effects upon cellular growth and signal transduction pathways. Treatment of A549 cells with kaempferol resulted in a dose- and time-dependent reduction in cell viability and DNA synthesis with the rate of apoptosis equivalent to 0.9+/-0.5, 5.2+/-1.5, 16.8+/-2.0, 25.4+/-2.6, and 37.8+/-4.5% on treatment with 0, 17.5, 35.0, 52.5, and 70.0 microM kaempferol, respectively. Concomitantly, kaempferol treatments led to a 1.2-, 2.7-, 3.3-, and 3.4-fold increase in Bax. Similar elevations were also observed in Bad which increased 1.2-, 3.3-, 3.7-, and 4.7-fold, respectively, as compared to control. Bcl-2 and Bcl-xL expression were inhibited in a dose-dependent fashion. While the Akt-1 and phosphorylated Akt-1 were inhibited, the mitogen-activated protein kinase (MAPK) was activated upon kaempferol treatment. Kaempferol induced apoptosis was associated with the cleavage of caspase-7 and poly ADP-ribose polymerase (PARP). Inhibition of MEK1/2 but not PI-3 kinase blocked kaempferol-induced cleavage of caspase-7, PARP cleavage, and apoptosis. The results suggest that inactivation of Akt-1 and alteration of Bcl-2 family of proteins are not sufficient for kaempferol to induce apoptosis and activation of MEK-MAPK is a requirement for kaempferol-induced cell death machinery in A549 cells.

The hazard of scattered radiation in a trauma intensive care unit

OBJECTIVE

Patients admitted to the trauma intensive care unit (TICU) often require bedside imaging procedures such as radiographs, fluoroscopic placement of enteral feeding tubes, and insertion of vena cava filters. The potential for scattered radiation exposure is a concern to healthcare workers. Our study's purpose was to measure the level of scattered ionizing radiation present in a TICU.

DESIGN AND SETTING

This prospective study was conducted over 3 months in an open-design, ten-bed TICU of a Level I trauma center.

INTERVENTIONS AND MEASUREMENTS

Fifteen dosimeters were placed in selected areas of the TICU to measure the amount of scattered radiation present. Standard radiation protection precautions were used throughout the study period. At the end of each month, data from the dosimeters were sent to the manufacturer for analysis.

MAIN RESULTS

One thousand seventy-four radiologic studies were performed at the bedside during the study period (803 portable chest radiographs, 103 abdominal radiographs, 303 extremity radiographs, 223 spine radiographs, and 15 fluoroscopic procedures). Dosimetry analysis showed <5 mrem (1/1000 roentgen equivalent in man) scattered radiation per month (<60 mrem/year) in each of the monitored areas. All monitored areas measured <2 mrem per week of scattered radiation when adjusted for occupancy.

CONCLUSIONS

The level of scattered radiation in our TICU is less than the recommended allowable exposure of <100 mrem/year, indicating that radiation exposure is not a significant occupational hazard in our TICU, even in the setting of frequent use of bedside imaging studies.

Failure of steroid regulation of the MMTV promoter in a small cell lung cancer cell line is caused by a DNA sequence flanking the glucocorticoid response element

We have previously described a panel of human small cell lung carcinoma (SCLC) cell lines that have profound glucocorticoid resistance, resulting from various molecular defects in glucocorticoid signalling. However, in one SCLC cell line, CORL103, the cause of the resistance is unknown. These cells are refractory to dexamethasone stimulation of MMTV even when exogenous wild-type glucocorticoid receptor (GR) is co-transfected. This is in contrast to cell lines DMS79 and CORL24 where resistance is overcome by transfection of the wild-type receptor. Sequencing of the GR from CORL103 cells revealed two point mutations, but neither of these induced dominant negative activity. Steroid hormone resistance extended to mineralocorticoid and progesterone receptor (MR, PR) activation of MMTV-luc, whereas oestrogen and thyroid hormone receptor transactivation were normal. A simpler reporter, TAT3-luc, containing three copies of the tyrosine aminotransferase glucocorticoid response element (GRE), was responsive when transfected into CORL103 cells with GR, MR and PR expression vectors and activated with their respective ligands. Similarly, pHH-luc and pAH-luc (truncated MMTV variants containing the GRE region, both derived from a different strain of MMTV), were effectively transactivated with dexamethasone. This suggests that the minor changes in the flanking sequence of the MMTV promoter are critically important in determining steroid responsiveness in CORL103 cells. We propose that minor differences in MMTV may determine recruitment of co-factors, which destabilise GR binding to the MMTV GREs. These findings represent a new, selective, model of glucocorticoid resistance that may explain specific cell and target gene differences in glucocorticoid sensitivity.

Staged repair of extensive aortic aneurysms: morbidity and mortality in the elephant trunk technique

BACKGROUND

Extensive aortic aneurysms (ascending aorta, aortic arch, and descending or thoracoabdominal aorta) require innovative surgical techniques. Some surgeons advocate a single procedure with long periods of profound hypothermia, whereas others use a staged approach. We adopted a two-staged procedure (elephant trunk technique) in 1991 for elective repair of extensive aortic aneurysms.

METHODS AND RESULTS

Between February 1991 and May 2000, we performed a total of 1146 aortic aneurysm operations. Of these, 182 (15.9%) operations were first- or second-stage elephant trunk procedures, performed in a total of 117 patients. Stage 1 was completed in all 117 patients. Stage 2 was completed in 65 (55.6%) of 117 patients. Thirty-day mortality rate for the first stage was 5.1% (6 of 117). Mortality rate during the interval between operations was 3.6% (4 of 111), of which 75% (3 of 4) were the result of aneurysm rupture. Thirty-day mortality rate for the second stage was 6.2% (4 of 65). A total of 43 patients did not return for second-stage repair. Among these patients, within an average period of 3.4 years (range, 1.5 months to 4.9 years), 13 of 43 (30.2%) died, 4 of 13 (30.8%) as the result of rupture. Two of 117 (1.7%) first-stage patients had postoperative stroke. No spinal cord dysfunction occurred in second-stage patients.

CONCLUSIONS

Extensive aortic aneurysms can be repaired with acceptable morbidity and mortality rates through the use of the elephant trunk technique. Death was most commonly the result of rupture, both in interval patients awaiting scheduled second-stage repair and in patients who did not return. After the first stage, prompt treatment of the remaining segment is crucial to the success of staged repair.

Neurologic outcome after thoracic and thoracoabdominal aortic aneurysm repair

BACKGROUND

Neurologic deficit (paraparesis and paraplegia) after repair of the thoracic and thoracoabdominal aorta remains a devastating complication. The purpose of this study was to determine the effect of cerebrospinal fluid drainage and distal aortic perfusion upon neurologic outcome during repair of thoracic and thoracoabdominal aortic aneurysm (TAAA) repair.

METHODS

Between February 1991 and March 2000, we performed 654 repairs of the thoracic and thoracoabdominal aorta. The median age was 67 years and 420 (64%) patients were male. Forty-five cases (6.9%) were performed emergently. Distribution of TAAA was the following: extent I, 164 (25%); extent II, 165 (25%); extent III, 61 (9%); extent IV, 95 (15%); extent V, 23 (3.5%); and descending thoracic, 147 (22%). The adjuncts cerebrospinal fluid drainage and distal aortic perfusion were used in 428 cases (65%).

RESULTS

Thirty-day mortality was 14% (94 of 654). The in-hospital mortality was 16% (106 of 654). Early neurologic deficits occurred in 33 patients (5.0%). Overall, 14 of 428 (3.3%) neurologic deficits were observed in the adjunct group, and 19 of 226 (8.4%) in the nonadjunct group (p = 0.004). When the adjuncts were used during extent II repair, the incidence was 10 of 129 (7.8%) compared with 11 of 36 (30.6%) in the nonadjunct group (p < 0.001). Multivariate analysis demonstrated that risk factors for neurologic deficit were cerebrovascular disease and extent of TAAA (II and III) (p < 0.05).

CONCLUSIONS

The combined adjuncts of distal aortic perfusion and cerebrospinal fluid drainage demonstrated improved neurologic outcome with repair of thoracic and TAAAs. In extent II aneurysms, adjuncts continue to make a considerable difference in the outcome and to provide significant protection against spinal cord morbidity. Future research should focus on spinal cord protection in patients with high-risk extent II aneurysms.

Descending thoracic aortic aneurysm: surgical approach and treatment using the adjuncts cerebrospinal fluid drainage and distal aortic perfusion

BACKGROUND

Neurologic deficit (paraplegia or paraparesis) remains a significant morbidity in the repair of descending thoracic aortic aneurysm.

METHODS

Between February 1991 and February 2000, we operated on 182 patients for descending thoracic aortic aneurysm. For the purpose of this study-to identify the impact of the combined adjuncts distal aortic perfusion and cerebrospinal fluid (CSF) drainage on neurologic outcome-we selected the 148 of 182 nonemergent patients who had received conventional treatment (simple cross-clamping with or without adjuncts). The mean patient age was 61 years, and 49 of the 148 (33%) patients were women. Nine of the 148 patients (6%) had acute type B dissections. We compared the results of 105 of the 148 patients (71%) who received the combined adjuncts of CSF drainage and distal aortic perfusion with the remaining 43 (29%) patients who underwent repair using the simple cross-clamp with or without the addition of a single adjunct.

RESULTS

Overall 30-day mortality was 13 of 148 patients (8.8%). Overall early neurologic deficit was 4 of 148 (2.7%): 1 of 105 (0.9%) patients who had received distal aortic perfusion and CSF drainage, versus 3 of 43 (7%) in all other patients (p < 0.04).

CONCLUSIONS

In our practice the use of the combined adjuncts of CSF drainage and distal aortic perfusion has all but eliminated the incidence of immediate postoperative neurologic deficit in nonemergent patients with aneurysms of the descending thoracic aorta.

Pheochromocytomas in von Hippel-Lindau syndrome and multiple endocrine neoplasia type 2 display distinct biochemical and clinical phenotypes

This study examined the mechanisms linking different biochemical and clinical phenotypes of pheochromocytoma in multiple endocrine neoplasia type 2 (MEN 2) and von Hippel-Lindau (VHL) syndrome to underlying differences in the expression of tyrosine hydroxylase (TH), the rate-limiting enzyme in catecholamine synthesis, and of phenylethanolamine N-methyltransferase (PNMT), the enzyme that converts norepinephrine to epinephrine. Signs and symptoms of pheochromocytoma, plasma catecholamines and metanephrines, and tumor cell neurochemistry and expression of TH and PNMT were examined in 19 MEN 2 patients and 30 VHL patients with adrenal pheochromocytomas. MEN 2 patients were more symptomatic and had a higher incidence of hypertension (mainly paroxysmal) and higher plasma concentrations of metanephrines, but paradoxically lower total plasma concentrations of catecholamines, than VHL patients. MEN 2 patients all had elevated plasma concentrations of the epinephrine metabolite, metanephrine, whereas VHL patients showed specific increases in the norepinephrine metabolite, normetanephrine. The above differences in clinical presentation were largely explained by lower total tissue contents of catecholamines and expression of TH and negligible stores of epinephrine and expression of PNMT in pheochromocytomas from VHL than from MEN 2 patients. Thus, mutation-dependent differences in the expression of genes controlling catecholamine synthesis represent molecular mechanisms linking the underlying mutation to differences in clinical presentation of pheochromocytoma in patients with MEN 2 and the VHL syndrome.

Vascular endothelial growth factor restores corporeal smooth muscle function in vitro

PURPOSE

The therapeutic use of vasculogenic growth factors has been successfully demonstrated in models of organ ischemia. We determined whether vascular endothelial growth factor (VEGF) would reverse corporeal smooth muscle dysfunction in the hypercholesterolemic rabbit model of erectile dysfunction.

MATERIALS AND METHODS

A total of 36 New Zealand White rabbits were fed a normal (12) or 1% cholesterol (24) diet and treated after 6 weeks with 0.9 mg. VEGF or vehicle. At 6 weeks 24 rabbits received a single intracavernous dose and 12 received a single intravenous bolus of either drug. Ten days after injection corporeal smooth muscle function was analyzed after relaxation to acetylcholine and sodium nitroprusside using isometric tension studies. Corporeal sections were assessed for smooth muscle content with f-actin staining and VEGF expression by immunohistochemical study and enzyme-linked immunosorbent assay.

RESULTS

Endothelium dependent (acetylcholine) and nitric oxide mediated (sodium nitroprusside) smooth muscle relaxation were impaired in cholesterol fed animals (p = 0.021 and 0.003, respectively). Intracavernous VEGF treatment restored sodium nitroprusside mediated relaxation to normal (p = 0.015) and intravenous VEGF restored acetylcholine and sodium nitroprusside mediated relaxation (p = 0.014 and 0.018, respectively). Decreased smooth muscle content was noted in cholesterol fed animals versus normal diet controls (p = 0.008), which was not affected by VEGF treatment (p = 0.450). Corporeal endothelial cell content was increased after intracavernous but not intravenous VEGF treatment (p = 0.001 and 0.385, respectively). VEGF expression was augmented after treatment with recombinant VEGF (p <0.001).

CONCLUSIONS

VEGF administration variably mitigated the impairment of corporeal smooth muscle relaxation in the hypercholesterolemic rabbit model of erectile dysfunction.

Local treatment with recombinant tissue factor pathway inhibitor reduces the development of intimal hyperplasia in experimental vein grafts

BACKGROUND

Tissue factor (TF)-initiated thrombin generation has been implicated in the development of intimal hyperplasia after arterial injury. An increase in intimal TF expression has been shown to precede the development of intimal hyperplasia in vein grafts. This study examines the effects of local treatment with recombinant human tissue factor pathway inhibitor (rTFPI) in experimental vein grafts.

METHODS

Thirty-six male New Zealand white rabbits underwent bypass grafting of the carotid artery by use of the reversed ipsilateral jugular vein and were divided into four groups. Twenty animals had ex vivo incubation with rTFPI treatment (50 microg x mL(-1); n = 10) or placebo vehicle (control; n = 10). Sixteen animals received both ex vivo incubation and in vivo gel treatment with rTFPI (50 microg. mL(-1); n = 8) or without rTFPI (gel-control; n = 8). After operation, vein grafts were harvested at 3 days for immunohistochemical and Western analyses and at 28 days for histomorphologic study.

RESULTS

Western analysis demonstrated a 6.2-fold reduction in the expression of TF protein with rTFPI treatment in comparison to without rTFPI treatment. CD-18 leukocyte staining was diminished, whereas Tie-2 endothelial staining was increased in all rTFPI-treated vein grafts, compared with control and gel-control vein grafts. Intimal thickness was reduced by 21% with ex vivo rTFPI treatment compared with placebo (69 +/- 4 versus 87 +/- 5 microm; P <.05) and by 30% with the addition of rTFPI in vivo compared with gel-control (60 +/- 4 versus 86 +/- 5 microm; P <.01).

CONCLUSION

Local administration of rTFPI exerts early beneficial effects and limits the development of intimal hyperplasia in vein grafts. Therefore blocking TF-mediated pathway may offer new therapeutic options to reduce vein graft failure.

The genes of two G-proteins involved in protein transport in Pichia pastoris

Members of the Rab protein family play essential roles in vesicle fusion during protein secretion and represent highly conserved GTP binding proteins. The Saccharomyces cerevisiae Sec4p and Ypt1p, promoting vesicle fusion at the plasma membrane and in ER-Golgi transport, respectively, are among the best characterised yeast members. We have here cloned the Pichia pastoris SEC4 homologue using a S. cerevisiae SEC4 probe. In addition we isolated a crosshybridising clone encoding another Rab-/Ypt-like protein. The deduced full-length PpSec4p comprises 204 amino acid residues with an over all identity of 64% to the Sec4p from S. cerevisiae and 72% to the Candida albicans Sec4p. The YPT-like gene encodes a 216 amino acid residue protein showing highest similarity to the S. cerevisiae Ypt10p and Ypt53p. Both PpSec4p and the Ypt-like protein carry a -Cys-Cys C-terminus, indicating that these proteins are targets for geranyl-geranylation by a type II prenyltransferase.

Delayed onset of neurologic deficit: significance and management

As contemporary adjuncts have substantially reduced the overall incidence of paraplegia and paraparesis after the surgical repair of thoracoabdominal aortic aneurysm, delayed-onset neurologic deficit has emerged as a significant clinical entity. It is generally agreed that neurologic deficits are attributable to the duration of spinal cord ischemia sustained during aortic cross-clamping. Factors known to increase the risk of spinal cord injury include the aneurysm extent, aortic cross-clamp time, aneurysm rupture, and associated acute aortic dissection. Clinically and experimentally, studies have shown different adjuncts to improve spinal cord protection, providing further insights into the pathophysiology of spinal cord ischemia. However, the pathophysiology of delayed-onset spinal cord deficit after thoracoabdominal aortic aneurysm repair remains largely controversial. This review discusses the significance and management of delayed-onset neurologic deficit.

Characterization of dopamine-mediated relaxation in experimental vein bypass grafts

BACKGROUND

Dopamine is an endogenous inotropic agent commonly used during coronary artery surgery and in the medical therapy of a revascularized patient. In this study the responses of intimal hyperplastic vein grafts to dopamine are examined.

METHODS

The in vitro isometric tension responses to dopamine of common carotid jugular vein bypass grafts in New Zealand White rabbits were determined. The responses were compared to those obtained in the jugular vein and in the common carotid artery. Both endothelialized and denuded vessels were precontracted with prostaglandin F(2alpha) and the responses to dopamine were assessed. The contributions of nitric oxide and prostanoids to the response were also determined.

RESULTS

Each vessel showed a biphasic dose response to dopamine with relaxation at low concentrations followed by contraction at high concentrations. Dopamine relaxation in the jugular vein was endothelial independent while in the carotid artery it was endothelial dependent and decreased. The sensitivity of both vessels was significantly greater than the vein graft (6.62 +/- 0.12; P < 0. 05); however, after endothelial denudation, the sensitivity of dopamine-mediated relaxation of the vein graft (8.91 +/- 0.09) was significantly enhanced. Preincubation with L-NMMA (to block NO synthesis) inhibited vein graft relaxation to dopamine and preincubation with indomethacin (to block cyclooxygenase activity) inhibited carotid artery relaxation to dopamine. Addition of phenoxybenzamine, a broad alpha-adrenergic antagonist, enhanced dopamine relaxation in the jugular vein and depressed the relaxation in the carotid artery. There was no effect on the dopamine response in the vein graft. Jugular vein and carotid artery responded to dopamine with cholera toxin-sensitive (Galpha(s)) responses. In contrast, dopamine relaxation in the vein graft was enhanced by inhibition of Galpha(s).

CONCLUSION

Dopamine relaxation in vein grafts is mediated in part by NO but not by either prostanoids or alpha-adrenergic receptor activation. It is diminished compared to native vessels due to an endothelium-dependent, Galpha(s)-mediated pathway.

Reversal of twice-delayed neurologic deficits with cerebrospinal fluid drainage after thoracoabdominal aneurysm repair: a case report and plea for a national database collection

Delayed neurologic deficits are an uncommon yet devastating complication of thoracoabdominal aortic aneurysm repair. The mechanisms involved in the development of delayed spinal cord ischemia remain ill defined. We report a case of complete reversal of delayed neurologic deficits with postoperative cerebrospinal fluid (CSF) drainage. After a thoracoabdominal aneurysm extent I repair, the patient experienced delayed paraplegia at 6 hours and again at 34 hours after the operation, with elevated CSF pressure (>10 mm Hg) on both occasions. Prompt CSF decompression completely reversed the neurologic deficits within hours after onset. The findings in this case further support the role of CSF drainage in spinal cord protection for patients who undergo thoracoabdominal aneurysm repair and make a plea for a national database collection.

Combination therapy of cholesterol reduction and L-arginine supplementation controls accelerated vein graft atheroma

Hyperlipidemia contributes to the development of intimal hyperplasia and accelerated atheroma in vein bypass grafts. Dietary cholesterol reduction and oral supplementation with L-arginine have been shown to reduce accelerated atheroma in experimental vein grafts. This study extends these observations by examining the effect of the combination therapy of cholesterol reduction and L-arginine supplementation on the development of intimal hyperplasia in vein grafts in hypercholesterolemic animals. Thirty New Zealand White rabbits had a carotid vein bypass graft performed and were sacrificed at 28 days postoperatively either for morphology (light and electron microscopy) and videomorphometry, or for in vitro contractile studies. Twenty animals received a 1% cholesterol diet for 4 weeks prior to surgery. This diet was continued until harvest in ten animals. Ten cholesterol-fed animals received L-arginine supplementation (2 g/kg/day, p.o.) for 7 days preoperatively and thereafter until harvest and in addition were returned to a normal diet on the day of surgery. The last ten animals were controls (normal diet). Combined cholesterol reduction and L-arginine supplementation prevented accelerated atheroma in vein grafts, halted the change in enhanced smooth muscle cell contractility, and improved endothelial cell function. Early postoperative therapy targeting atheroma development in the high-risk patient could offer significant morphological and functional benefits.

External support modulates G protein expression and receptor coupling in experimental vein grafts

BACKGROUND

Intimal hyperplasia remains the leading cause of vein graft failure. Various external stenting devices have been shown to reduce the development of intimal hyperplasia in vein grafts. Mitogenic and mechanotransduction signals are known to be mediated by G protein-coupled receptors. Therefore in this study we examined the alterations in G protein expression and receptor coupling in vein grafts stented with external tube support.

METHODS

Thirty New Zealand White male rabbits had a right carotid interposition bypass graft with use of the ipsilateral jugular vein. Fifteen animals received external support and 15 were controls. In a subset the animals either had removal of the external support or a sham-control neck exploration at 14 days after the initial implantation (n = 5 per group).

RESULTS

External support reduced G alpha i3 proteins by 30% in vein grafts without changes in G alpha s by Western blot. Vein grafts with external support were significantly less sensitive to pertussis toxin inactivation than controls were in response to both norepinephrine and serotonin. A 24% decrease in intimal thickness was maintained after withdrawal of the initial external support.

CONCLUSIONS

The placement of an external support is associated with alternations in G protein expression and receptor coupling function in vein grafts. The results of this study suggest that the development of vein graft intimal hyperplasia may involve G protein-mediated events.

Early morphology of accelerated vein graft atheroma in experimental vein grafts

Vein grafts fail because of the development of intimal hyperplasia and atheroma. Recent experimental evidence suggests that the presence of hypercholesterolemia induces a three-fold increase in intimal hyperplasia with early atheroma development within 4 weeks of implantation. We have previously demonstrated endothelial cell preservation and a short-lived (3-day) polymorphonuclear leukocyte infiltrate in vein grafts. The aim of this study is to define the early morphology and ultrastructure of vein grafts implanted into a hyperlipidemic environment to provide a pathological foundation on which to examine the cellular and molecular events that determine this accelerated response. Twenty-one male New Zealand White rabbits underwent a right carotid interposition bypass graft using the ipsilateral external jugular vein; all animals received a 1% cholesterol diet for 4 weeks prior to surgery and continuing postoperatively until harvest. Animals (n = 3 per time point) were sacrificed at 60 min, 1 day, 3 days, 5 days, 7 days, 14 days, and 28 days postoperatively for scanning and transmission electron microscopy of the vein grafts. No concurrent controls were employed. The results of this study suggest that in the presence of hypercholesterolemia, the pathophysiological processes involved in the vein graft are similar to those reported for noncholesterol-fed animals. There is a sustained subendothelial response with the prolonged presence of macrophages and cellular debris and the accumulation of foam cells.

Reduction of lipid peroxidation with intraoperative superoxide dismutase treatment decreases intimal hyperplasia in experimental vein grafts

BACKGROUND

Vein graft failure is commonly attributed to the development of intimal hyperplastic lesions. Oxidative stress has been implicated in the initiation and progression of atherosclerosis. In this study we examined the effects of local intraoperative treatment with polyethylene glycolated superoxide dismutase (PEG-SOD) on lipid peroxidation and on the development of intimal hyperplasia in experimental vein grafts.

MATERIALS AND METHODS

Forty-one New Zealand White male rabbits had a right carotid interposition bypass graft using the ipsilateral reversed jugular vein. Sixteen animals received local PEG-SOD (4,100 units) treatment; 9 animals received the polyethylene glycol (PEG) vehicle without SOD; 16 animals were used as controls. Postoperatively, malondialdehyde (MDA, a product of lipid peroxidation) concentration and SOD activity were assessed in 3-day vein grafts by colorimetric spectrophotometry. To determine wall dimensions and vasomotor function, morphometric and isometric tension studies were performed on 28-day vein grafts.

RESULTS

MDA concentration was increased 5. 7-fold (P < 0.05) in 3-day control vein grafts compared to ungrafted jugular veins. Intraoperative PEG-SOD treatment raised SOD activity 5.0-fold (P < 0.05) and reduced MDA concentration 8-fold (P < 0.05) in 3-day vein grafts compared to controls. At 28 days, intimal thickness was reduced by 35% with PEG-SOD treatment (54 +/- 4 vs 83 +/- 5; P < 0.001) compared to control vein grafts, without a change in medial thickness (77 +/- 4 vs 88 +/- 5; P = ns). The vasomotor functions of 28-day PEG-SOD-treated vein grafts to norepinephrine, serotonin, bradykinin, nitroprusside, and acetylcholine were not significantly changed when compared to controls. Treatment with PEG alone did not significantly alter lipid peroxidation, wall dimensions, or vasomotor function of vein grafts.

CONCLUSION

This study demonstrates that intraoperative local treatment of vein grafts with PEG-SOD increases SOD activity and decreases lipid peroxidation for at least 3 days, resulting in reduced intimal hyperplasia at 28 days. These findings further implicate oxidative stress in the hyperplastic response of vein grafts and suggest a potential therapeutic role for PEG-SOD in the prevention of vein graft failure.

Controlling transplant vasculopathy in cryopreserved vein grafts with polyethylene glycol and glutathione during transport

BACKGROUND

the biological characteristics of cryopreserved allografts are poorly understood, although many factors are known to influence their outcome. This study examines the development of transplant vasculopathy in both fresh and cryopreserved vein allografts and specifically assesses the efficacy of a transport solution containing 10% polyethylene glycol and 10 microM glutathione (PEG/GSH).

METHODS

jugular veins were harvested from control donor rabbits and transplanted as interposition carotid bypass grafts in 30 New Zealand White (NZW) rabbits. Ten received the fresh jugular veins (fresh). Ten animals received jugular veins which had been harvested, transported in a physiological solution, cryopreserved and stored in a standard fashion (cryopreserved). Ten animals received jugular veins which had been harvested, transported in the same solution with the addition of PEG/GSH, cryopreserved and stored in a standard fashion (PEG/GSH). Cryopreserved jugular veins were stored for 6 weeks before transplantation. All animals were sacrificed 28 days postoperatively. Vein grafts were perfusion-fixed and wall dimensions were determined by planimetry.

RESULTS

all transplanted grafts were patent at harvest. The control cryopreserved vein grafts showed a 54% increase in mean intimal thickness (63+/-10 micron vs. 41+/-3 micron p<0.05) but no change in mean medial thickness (125+/-9 micron vs. 119+/-13 micron; p = N.S. ) compared to the fresh allograft. Transport of the grafts in PEG/GSH solution resulted in the abolition of the increase in intimal thickness (41+/-4 micron; p <0.01) associated with cryopreservation without a change in medial thickness (140+/-15 micron; p = N.S.) compared to the cryopreserved allograft.

CONCLUSION

cryopreserved vein grafts develop significant intimal hyperplasia compared to freshly transplanted grafts. The use of PEG/GSH in the transport solution significantly reduces this transplant graft intimal hyperplasia to that which develops in fresh grafts and may lead to improvements in the clinical use of cryopreserved veins.

Functional characterization of alpha1-adrenergic receptors in experimental vein grafts

BACKGROUND

Studies on the pharmacology of the smooth muscle cells in vein bypass grafts suggest that the function of G-proteins and adrenergic receptors is altered. This study examines the alpha-adrenergic responsiveness of smooth muscle cells in vein bypass grafts as compared with those in the common carotid arteries and external jugular veins.

METHODS

New Zealand White rabbits received jugular vein interposition bypass grafts of the common carotid. Vessel segments of the vein bypass grafts harvested after 28 days, common carotid arteries, and external jugular veins were sectioned into 5-mm rings (four per vessel) for studies of isometric tension in response to phenylephrine (10(-10) to 10(-4) M) alone and in the presence of prazosin, an alpha1-adrenergic antagonist; WB4101 and 5-methylurapidil (5-MU), alpha1A antagonists; chloroethylclonidine (CEC); an alpha1B antagonist; or the Gi/o G-protein inhibitor pertussis toxin (PTx).

RESULTS

All vessels had prazosin-sensitive responses. The jugular veins appear to have functional alpha1A receptors (WB4101 and 5-MU sensitive, CEC insensitive) which are associated with pertussis toxin-sensitive G-proteins. Carotid arteries appear to have atypical alpha1 receptors (WB4101 and 5-MU insensitive, CEC insensitive) associated with pertussis toxin-insensitive G-proteins. Vein grafts appear to have functional alpha1B receptors (WB4101 and 5-MU insensitive, CEC sensitive) which are associated with pertussis toxin-insensitive G-proteins.

CONCLUSIONS

These results show that placement of a vein into the arterial circulation induces a change in alpha1-adrenergic receptor subtypes (alpha1A to alpha1B) and in the G-protein coupling of the receptors (PTx sensitive to PTx insensitive), reflecting a signficant phenotypic change in smooth muscle cell signal transduction.

Alterations in wall tension and shear stress modulate tyrosine kinase signaling and wall remodeling in experimental vein grafts

PURPOSE

Hemodynamic alterations have been implicated as major stimuli for the development of intimal hyperplasia in vein grafts that are implanted in the arterial circulation. Tyrosine kinase is known to mediate cell signaling. However, its role with in vivo mechanotransduction is not yet well defined. We used a novel bioprosthetic collagen tube to provide an external support to vein grafts and examined the subsequent changes in hemodynamics, tyrosine kinase signaling, wall remodeling, and vasomotor function.

METHODS

Carotid interposition bypass grafting was performed with the reversed jugular vein in New Zealand white rabbits. In the experimental group (n = 15), after the completion of the proximal anastomosis, the vein was passed through a 4-mm collagen tube and the distal anastomosis was performed. The tube support was fashioned to completely cover the vein grafts. The control animals (n = 14) had no tube support. After surgery, the blood pressure and flow rate were measured and the wall tension and shear stress were calculated in the vein grafts on day 3 or day 28 (n = 5 per group). Tyrosine phosphorylation was assessed with the Western blot test in vein grafts at day 3 (n = 4 per group). The intimal and medial dimensions of the vein grafts were assessed with videomorphometry on day 28 (n = 5 per group). The cumulative dose response curves of the vein grafts to contractile and relaxant agonists were determined in isometric tension studies on day 28 (n = 5 per group).

RESULTS

The use of tube support reduced wall tension 1.7-fold (P <.01) and increased shear stress 4.8-fold (P <.001) without altering the flow rate or blood pressure. The tyrosine kinase activity was reduced 15-fold (P <.001) in the tube-supported vein grafts. The intimal thickness was reduced by 45% in the tube-supported vein grafts as compared with the control grafts (46 +/- 2 mm vs 84 +/- 5 mm, respectively; P <.0001), and the media thickness was reduced by 20% (63 +/- 8 mm vs 79 +/- 4 mm, respectively; P <.05). Isometric tension studies showed preservation of contractile function and modulation of endothelial-dependent dysfunctional relaxation in tube-supported vein grafts.

CONCLUSION

These results show that reduced wall tension and increased shear stress with an external tube support can effectively modulate the signaling, functional, and hyperplastic responses in vein grafts. We conclude that this simple strategy deserves further study and clinical consideration.