Sex Disparities in Left Ventricular Assist Device Implantation: Delayed Presentation and Worse Right Heart Failure

We explored whether women undergo continuous-flow left ventricular assist device (CF-LVAD) implantation in later stages of heart failure (HF) than men, evidenced by worse preoperative right HF (RHF). We also compared two propensity models with and without preoperative RHF to assess its effect on outcomes. INTERMACS was queried from July 2008 to December 2017. Propensity model 1 matched men and women on age ≥50 years, HF etiology, body surface area, INTERMACS class, comorbidities, device strategy, temporary mechanical circulatory support, and device type. Model 2 included these variables plus LV end-diastolic diameter, right atrial pressure/pulmonary capillary wedge pressure, pulmonary artery pulsatility index, and right ventricular ejection fraction. The primary outcome was all-cause mortality. Secondary outcomes comprise RHF, rehospitalization, renal dysfunction, stroke, and device malfunction. In model 1, characteristics were comparable between 3,195 women and 3,195 men, except women more often had preoperative RHF and postoperative right VAD support and had worse 1 year and overall survival. In model 2, after propensity matching for additional risk factors for preoperative RHF, 1,119 women and 1,119 men had comparable post-LVAD implant RVAD use and survival. These findings suggest that women present more often with biventricular failure and after implantation have higher RHF and mortality rates.

Impact of time off anticoagulation in patients with continuous-flow left ventricular assist devices

Patients with left ventricular assist devices (LVADs) receive anticoagulation to decrease the risk of thrombosis. Various circumstances require discontinuing anticoagulation in LVAD patients, but the risks entailed are not well defined. In a retrospective review of LVAD implantation procedures, we examined the effect of time off anticoagulation on thrombosis and mortality rates after implantation. An international normalized ratio ≤ 1.5 was used to screen for patients taken off anticoagulation. Patients were divided into three groups by the cumulative number of days off anticoagulation: no discontinuation, short-term discontinuation (< 30 days), and long-term discontinuation (≥ 30 days). Rates of ischemic stroke, pump thrombosis, and mortality were compared among groups. Of 245 patients who underwent LVAD implantation during the study, 70 (28.6%) were off anticoagulation during follow-up: 37 (15.1%) had short-term discontinuation (median, 11 days), and 33 (13.5%) had long-term discontinuation (median, 124 days). Patients with long-term discontinuation had a higher rate of ischemic stroke (adjusted hazard ratio 8.5, p = 0.001) and death (adjusted hazard ratio 3.9, p = 0.001). The three groups did not differ in pump thrombosis rate. We conclude that after LVAD implantation, discontinuing anticoagulation for ≥ 30 days is independently associated with an increased risk of ischemic stroke and death.

Incidence, Risk Score Performance, and In-Hospital Outcomes of Postoperative Atrial Fibrillation After Cardiac Surgery

BACKGROUND

Postoperative atrial fibrillation (POAF) frequently complicates cardiac surgery. Predicting POAF can guide interventions to prevent its onset. This study assessed the incidence, risk factors, and related adverse outcomes of POAF after cardiac surgery.

METHODS

A cohort of 1,606 patients undergoing cardiac surgery at a tertiary referral center was analyzed. Postoperative AF was defined based on the Society of Thoracic Surgeons' criteria: AF/atrial flutter after operating room exit that either lasted longer than 1 hour or required medical or procedural intervention. Risk factors for POAF were evaluated, and the performance of established risk scores (POAF, HATCH, COM-AF, CHA2DS2-VASc, and Society of Thoracic Surgeons risk scores) in predicting POAF was assessed using discrimination (area under the receiver operator characteristics curve) analysis. The association of POAF with secondary outcomes, including length of hospital stay, ventilator time, and discharge to rehabilitation facilities, was evaluated using adjusted linear and logistic regression models.

RESULTS

The incidence of POAF was 32.2% (n = 517). Patients who developed POAF were older, had traditional cardiovascular risk factors and higher Society of Thoracic Surgeons risk scores, and often underwent valve surgery. The POAF risk score demonstrated the highest area under the receiver operator characteristics curve (0.65), but risk scores generally underperformed. Postoperative AF was associated with extended hospital stays, longer ventilator use, and higher likelihood of discharge to rehabilitation facilities (odds ratio, 2.30; 95% CI, 1.73-3.08).

CONCLUSION

This study observed a high incidence of POAF following cardiac surgery and its association with increased morbidity and resource utilization. Accurate POAF prediction remains elusive, emphasizing the need for better risk-prediction methods and tailored interventions to diminish the effect of POAF on patient outcomes.

Clinical Predictors and Outcomes After Left Ventricular Assist Device Implantation and Tracheostomy

BACKGROUND

Postoperative respiratory failure is a major complication that affects up to 10% of patients who undergo cardiac surgery and has a high in-hospital mortality rate. Few studies have investigated whether patients who require tracheostomy for postoperative respiratory failure after continuous-flow left ventricular assist device (CF-LVAD) implantation have worse survival outcomes than patients who do not.

OBJECTIVE

To identify risk factors for respiratory failure necessitating tracheostomy in CF-LVAD recipients and to compare survival outcomes between those who did and did not require tracheostomy.

METHODS

Consecutive patients who underwent primary CF-LVAD placement at a single institution between August 1, 2002, and December 31, 2019, were retrospectively reviewed. Propensity score matching accounted for baseline differences between the tracheostomy and nontracheostomy groups. Multivariate logistic regression was used to identify tracheostomy risk factors and 90-day survival; Kaplan-Meier analysis was used to assess midterm survival.

RESULTS

During the study period, 664 patients received a CF-LVAD; 106 (16.0%) underwent tracheostomy for respiratory failure. Propensity score matching produced 103 matched tracheostomy-nontracheostomy pairs. Patients who underwent tracheostomy were older (mean [SD] age, 57.9 [12.3] vs 54.6 [13.9] years; P = .02) and more likely to need preoperative mechanical circulatory support (61.3% vs 47.8%; P = .01) and preoperative intubation (27.4% vs 8.8%; P < .001); serum creatinine was higher in the tracheostomy group (mean [SD], 1.7 [1.0] vs 1.4 [0.6] mg/dL; P < .001), correlating with tracheostomy need (odds ratio, 1.76; 95% CI, 1.21-2.56; P = .003). Both before and after propensity matching, 30-day, 60-day, 90-day, and 1-year survival were worse in patients who underwent tracheostomy. Median follow-up was 0.8 years (range, 0.0-11.2 years). Three-year Kaplan-Meier survival was significantly worse for the tracheostomy group before (22.0% vs 61.0%; P < .001) and after (22.4% vs 48.3%; P < .001) matching.

CONCLUSION

Given the substantially increased probability of death in patients who develop respiratory failure and need tracheostomy, those at high risk for respiratory failure should be carefully considered for CF-LVAD implantation. Comprehensive management to decrease respiratory failure before and after surgery is critical.

Extracorporeal Membrane Oxygenation for COVID-19: Collaborative Experience From the Texas Medical Center in Houston With 2 Years Follow-Up

Patients with severe refractory hypoxemic respiratory failure may benefit from extracorporeal membrane oxygenation (ECMO) for salvage therapy. The Coronavirus disease 2019 (COVID-19) pandemic offered three high-volume independent ECMO programs at a large medical center the chance to collaborate to optimize ECMO care at the beginning of the pandemic in Spring 2020. Between March 15, 2020, and May 30, 2020, 3,615 inpatients with COVID-19 were treated at the Texas Medical Center. During this time, 35 COVID-19 patients were cannulated for ECMO, all but one in a veno-venous configuration. At hospital discharge, 23 (66%) of the 35 patients were alive. Twelve patients died of vasodilatory shock (n = 9), intracranial hemorrhage (n = 2), and cannulation-related bleeding and multiorgan dysfunction (n = 1). The average duration of ECMO was 13.6 days in survivors and 25.0 days in nonsurvivors ( p < 0.04). At 1 year follow-up, all 23 discharged patients were still alive, making the 1 year survival rate 66% (23/35). At 2 years follow-up, the overall rate of survival was 63% (22/35). Of those patients who survived 2 years, all were at home and alive and well at follow-up.

Preoperative hyponatremia and survival after left ventricular assist device implantation

BACKGROUND

Hyponatremia is associated with adverse outcomes in heart failure and after cardiac surgery. We hypothesized that hyponatremia is associated with poorer short-term and longer-term survival in patients after continuous-flow left ventricular assist device (CF-LVAD) placement.

METHODS

We reviewed a single-center database of patients who received a CF-LVAD during 2012-2017. Sodium (Na) values obtained within 14 days before CF-LVAD insertion were averaged; patients (n=332) were divided into hyponatremia (mean Na <135 mEq/L; n=160; 48.2%) and normonatremia groups (mean Na 135-145 mEq/L; n=172; 51.8%). Patients requiring preoperative dialysis or pump exchanged were excluded. We compared outcomes between preoperative hyponatremia and normonatremia groups.

RESULTS

The two groups' baseline characteristics were similar, although hyponatremia patients more often had preoperative mechanical circulatory support (44.4% vs 31.4%, p=0.002). Although hyponatremic and normonatremic patients did not differ in 30-day mortality (7.5% vs 6.5%, p=0.7), preoperative hyponatremia was associated with greater 5-year mortality (61% vs 44%, p=0.03). On binary logistic regression analysis, the strongest independent predictors of late mortality were hyponatremia (odds ratio [OR] 1.88, 95% CI [1.07-3.31], p=0.02), older age (OR 1.03, 95% CI [1.01-1.05], p=0.01), and elevated mean right atrial pressure/pulmonary capillary wedge pressure ratio (OR 4.69, 95% CI [1.76-12.47], p=0.002).

CONCLUSIONS

Hyponatremia was not associated with greater early mortality but was associated with poorer late survival. Optimal timing of LVAD implantation in relation to hyponatremia, and whether correcting hyponatremia perioperatively improves long-term survival, should be investigated.

Extracorporeal membrane oxygenation as a bridge to durable left ventricular assist device implantation in INTERMACS-1 patients

Left ventricular assist devices (LVADs) are increasingly used as destination therapy or as a bridge to future cardiac transplant in patients with end-stage heart failure. Extracorporeal membrane oxygenation (ECMO) can be used to bridge patients in cardiogenic shock or with decompensated heart failure to durable mechanical circulatory support. We assessed outcomes in patients in critical cardiogenic shock (Interagency Registry for Mechanically Assisted Circulatory Support [INTERMACS] profile 1) who underwent implantation of a continuous-flow (CF)-LVAD, with or without preoperative ECMO bridging. For this retrospective study, we selected INTERMACS profile 1 patients who underwent CF-LVAD implantation at our institution between Sep 1, 2004 and Nov 30, 2018. Of 768 patients identified, 133 (17.3%) were INTERMACS profile 1; 26 (19.5%) received preoperative ECMO support, and 107 (80.5%) did not. Postimplantation outcomes were compared between the ECMO and no-ECMO groups. No significant differences were found in 30-day mortality (15.4 vs. 15.9%, P = 0.95) or survival at 1 year (53.8 vs. 60.9%, P = 0.51). Three patients who received ECMO before CF-LVAD implantation subsequently underwent cardiac transplant. In the ECMO group, the lactate level 1 day after ECMO initiation was lower in survivors than nonsurvivors (2.7 ± 2.2 vs. 7.4 ± 4.2 mmol/L, P = 0.02; area under the curve = 0.85, P = 0.01) after CF-LVAD implantation. Bridging with ECMO to CF-LVAD implantation in carefully selected INTERMACS profile 1 patients (those who are at the highest risk for critical cardiogenic shock and for whom palliation may be the only other option) produced acceptable postoperative outcomes.Field of research: Artificial lung/ECMO.

Increasing Heart Transplant Volume by Expansion of Donor Heart Selection Criteria: A Single-Center Analysis

BACKGROUND

Our transplant center recently expanded the acceptance criteria for cardiac donors to increase heart transplant volume. Our purpose was to assess the success of this strategy while maintaining acceptable 1-year survival.

METHODS

We retrospectively reviewed patients who underwent heart transplantation at our institution from January 2011 through December 2017. This time period was divided into 2 periods: 2011 to 2014 (Period A) and 2015 to 2017 (Period B) because we implemented our new donor acceptance policy at the onset of 2015. We compared recipient and donor characteristics from the 2 time periods. The primary outcomes were 1-year graft and patient survival.

RESULTS

Transplant volume increased in Period B with the expanded donor acceptance policy: 128 heart transplants over 36 months compared to 52 transplants in 48 months in Period A. Mean (± SD) recipient age was significantly higher in Period B (54 ± 12 vs 50 ± 15 years; P = .04) whereas other recipient variables were similar. Donors in Period B were significantly older, more likely to be female, had larger body mass index, were located a greater distance from the transplant center, and had a higher sequence number. Female donor to male recipient occurred more often in Period B than in Period A (27% vs 10%; P = .01). Both 1-year patient survival and graft survival were unchanged between Period B (95% for both) and Period A (96% for both).

CONCLUSIONS

Using a more aggressive donor acceptance policy allowed for an increase in heart transplant volume while maintaining acceptable 1-year graft and patient survival.

Impact of donor lung pathogenic bacteria on patient outcomes in the immediate post-transplant period

BACKGROUND

Patient outcomes post-lung transplant remain inferior to other types of solid organ transplantation. We investigated whether the presence of potentially pathogenic bacteria (PPB) in donor lung bronchial cultures was associated with adverse outcomes postoperatively.

METHODS

All patients who underwent lung transplantation between August 2015 and April 2017 at the University of Kentucky Medical Center were retrospectively reviewed. Retransplants, patients with bronchiectasis (including cystic fibrosis), and individuals who received organs from donation after cardiac death (DCD) donors were excluded. The remaining subjects were separated into two groups: individuals whose donor bronchial cultures grew PPB, and those whose cultures either returned negative for PPB or were sterile. 30-day mortality rates as well as the incidence of grade 3 primary graft dysfunction (PGD) and acute kidney injury (AKI) at both 24 and 72 hours post-transplant were calculated. The duration of mechanical ventilation postoperatively was also recorded.

RESULTS

Thirty two subjects comprised the study population. 20 patients (63%) had growth of PPB on donor cultures, while 12 (37%) did not. Patients with PPB had a significantly greater number of days on the ventilator postoperatively compared to those with no PPB (mean = 11.3 and median = 5.0 vs mean = 5.8 and median = 3.0, respectively, P = 0.0232). Subsequent regression analysis revealed this association to not be influenced by recipient lung allocation score (LAS), donor age, donor smoking history, recipient mean pulmonary artery pressure (mPAP) value, and/or use of cardiopulmonary bypass at the time of transplantation. Neither 30-day survival nor incidence of Grade 3 PGD and AKI at 24 or 72 hours post-transplant differed between the two groups (P > 0.05).

CONCLUSION

The recovery of PPB in donor lung cultures was associated with a longer duration of mechanical ventilation postoperatively in lung transplant recipients.

Increased blood transfusion and its impact in patients having tracheostomy while on extracorporeal membrane oxygenation

Introduction:

Tracheostomy has been utilized in combination with venovenous extracorporeal membrane oxygenation (VV-ECMO) to enable early spontaneous breathing and minimize sedation requirements. Tracheostomy has been previously reported to be safe in patients supported on VV-ECMO; however, the impact of tracheostomy on blood loss in VV-ECMO patients is unknown.

Methods:

We analyzed VV-ECMO patients with and without tracheostomy over a 5-year period. In order to avoid other potential sources of blood loss not related to tracheostomy or ECMO-related blood loss, patients who underwent a recent surgery prior to ECMO or during ECMO (other than tracheostomy) were excluded.

Results:

Sixty-three patients meeting the inclusion criteria were identified (tracheostomy n=30, non-tracheostomy n=33). Tracheostomy patients were found to require more daily transfusions of red blood cells (RBC) (0.47 [0.20-1.0] vs. 0.23 [0.06-0.40] units/day, p=0.02) and total blood products (0.60 [0.32-1.0] vs. 0.31 [0.10-0.50] units/day, p=0.01).

Conclusions:

These results suggest that tracheostomy while on VV-ECMO predisposes patients to increased transfusion burden. Based on previous research, this increased transfusion burden could potentially be linked to increased complications and mortality.

Clearance of Hepatitis C Virus Prior to Lung Transplantation: A Case Report

Hepatitis C virus (HCV) continues to be considered a relative contraindication to lung transplantation due to concerns of progression of liver disease with the introduction of immunosuppression. Since the recent introduction of effective antiviral therapy for HCV, new approaches in the management of the HCV-positive recipient are being utilized in liver transplantation to clear HCV pre- and post-transplant. Herein, we report use of ledipasvir/sofosbuvir for HCV clearance prior to lung transplantation in a patient with usual interstitial pneumonia. Listing for transplant was delayed until completion of HCV treatment, and he subsequently required extracorporeal membrane oxygenation as a bridge to transplantation due to progressive hypoxia. With antiviral cure rates exceeding 90%, HCV should no longer be considered a relative contraindication to lung transplant, and timing of antiviral treatment should consider the progressive nature of the recipient's lung disease.

Emergency department repair of blunt right atrial rupture utilizing cardiopulmonary bypass

Blunt cardiac injury (BCI) with free wall rupture carries a high risk of pre-hospital death. Cardiopulmonary bypass (CPB) has been utilized as a bridge to repair of cardiac lesions in select patients. We present an interesting case of emergency department repair of right atrial rupture with cardiopulmonary bypass.

Too high for transplantation? Single-center analysis of the lung allocation score

BACKGROUND

Recent studies using United Network for Organ Sharing data suggest that lung transplantation in patients with high lung allocation scores (LAS) may lead to organ and resource wastage. Therefore, to determine whether a LAS cutoff value should be considered, we evaluated the relation of LAS to waitlist and posttransplant mortality in our center to determine if it could identify patients for whom listing for transplantation may be futile.

METHODS

From May 1, 2005 to July 1, 2010, 537 adults were listed and 426 underwent primary lung transplantation at our institution. Endpoints were mortality before and after lung transplantation. The relationships of LAS at listing to waitlist mortality and of pretransplant LAS to posttransplant mortality were both analyzed by multiphase hazard function methodology.

RESULTS

Higher LAS was strongly associated with waitlist mortality (p<0.0001), with the highest quartile (LAS ranging from 47 to 95) experiencing 75% mortality within a year of listing. Although early (p=0.05), but not late (p=0.4), posttransplant survival was associated with higher LAS at transplantation, once other clinical characteristics predictive of early mortality were accounted for, neither waitlist nor pretransplant LAS was independently related to posttransplant mortality (p=0.12).

CONCLUSIONS

Higher LAS strongly predicts higher mortality on the lung transplantation waitlist, underscoring the value of LAS in prioritizing patients with the highest scores for transplantation. Early posttransplant mortality is modestly higher with higher pretransplant LAS, but the data of our center do not suggest a value above which transplantation should be denied as futile. This suggests that donor organs and resources are not being wasted.

Spectroscopic limb monitoring in peripheral extracorporeal membrane oxygenation

Limb-related complications are major contributors to extracorporeal membrane oxygenation-associated complications. Early detection of limb ischemia and or compartment syndrome is paramount to minimizing the adverse effects. With the absence of pulsatile flow, bedside Doppler examination of distal arterial waveforms is an impractical and an unreliable method of monitoring limb perfusion. We describe a new application of near-infrared spectroscopy monitoring of tissue oxygenation for the early detection of limb complications in extracorporeal membrane oxygenation.

Changes in left ventricular morphology and function after mitral valve surgery

Degenerative mitral valve disease is the leading cause of mitral regurgitation in North America. Surgical intervention has hinged on the symptoms and ventricular changes that develop as compensatory ventricular remodeling occurs. In the present study, we sought to characterize the temporal response of left ventricular (LV) morphology and function to mitral valve surgery for degenerative disease and to identify the preoperative factors that influence reverse remodeling. From 1986 to 2007, 2,778 patients with isolated degenerative mitral valve disease underwent valve repair (n = 2,607 [94%]) or replacement (n = 171 [6%]) and had ≥1 postoperative transthoracic echocardiogram; 5,336 transthoracic echocardiograms were available for analysis. Multivariate longitudinal repeated-measures analysis was performed to identify the factors associated with reverse remodeling. The LV dimensions decreased in the first year after surgery (end-diastolic from 5.7 ± 0.80 to 4.9 ± 1.4 cm; end-systolic from 3.4 ± 0.71 to 3.1 ± 1.4 cm). The LV mass index decreased from 139 ± 44 to 112 ± 73 g/m(2). The reduction in LV hypertrophy was less pronounced in patients with greater preoperative left heart enlargement (p <0.0001) and a greater preoperative LV mass (p <0.0001). The postoperative LV ejection fraction initially decreased from 58 ± 7.0% to 53 ± 20%, increased slightly during the first postoperative year, and was negatively influenced by preoperative heart failure symptoms (p <0.0001) and a lower preoperative LV ejection fraction (p <0.0001). The risk-adjusted response of LV morphology and function to valve repair and replacement was similar (p >0.2). In conclusion, a positive response toward normalization of LV morphology and function after mitral valve surgery is greatest in the first year. The best response occurs when surgery is performed before left heart dilation, LV hypertrophy, or LV dysfunction develop.

Perforated gastric corpus in a strangulated paraesophageal hernia: a case report

Introduction

Patients with paraesophageal hernias often present secondary to chronic symptomatology. Infrequently, acute intestinal ischemia and perforation can occur as a consequence of paraesophageal hernias with potentially dire consequences.

Case presentation

An 86-year-old obtunded male presented to the emergency department with hypotension and severe back and abdominal pain. An emergency abdominal CT scan was ordered with a presumptive diagnosis of ruptured abdominal aortic aneurysm. CT topograms revealed extensive free intra-abdominal air and herniated abdominal viscera into the right hemithorax. Prior to completion of the CT study, the patient sustained a cardiopulmonary arrest. Surgery was consulted, but the patient was unable to be revived. Post-mortem examination revealed gross contamination within the abdomen and a giant, incarcerated, hiatal hernia with organoaxial volvulus and ischemic perforation.

Conclusion

Current recommendations call for prompt repair of giant hiatal hernias before they become symptomatic due to the increased risk of strangulation. Torsion of the stomach in large hiatal hernias frequently leads to a fatal complication such as this warranting elective repair as soon as possible.

Matrix metalloproteinase inhibition improves survival in an orthotopic model of human pancreatic cancer

Matrix metalloproteinases (MMPs) have been implicated in the growth and invasiveness of primary and metastatic tumors. Hypothesizing that MMP inhibition would slow cancer growth, the MMP inhibitor BB-94 (batimistat) was evaluated in an orthotopic animal model of human pancreatic carcinoma. Ten million human pancreatic cancer cells were surgically implanted into the pancreata of 30 athymic nu/nu mice. Intraperitoneal administration of 30 mg/kg BB-94 or vehicle control began 7 days after tumor implantation (13 mice with confirmed implantations in each group) and continued daily for 21 days, and then three times weekly until death or sacrifice at day 70. Representative tumors harvested from mice in each group were analyzed for presence and activity of MMP-2 and MMP-9. Animal weights were significantly higher in the BB-94-treated group at sacrifice (mean 58.4 +/- 7.9 g vs. 39.8 +/- 6.2 g; P < 0.05, Student's t test). The likelihood of survival to 70 days was significantly higher in the treated group (4 of 13 vs. 0 of 13, P < 0.05, Z-test for end points) than in the control group as was overall survival (P = 0.03, Wilcoxon test). Nine mice in the control group developed metastases to the liver, peritoneum, abdominal wall, or local lymph nodes, whereas only two mice in the BB-94 group had evidence of metastatic disease (P < 0.02, Fisher's exact test), in both instances confined to the abdominal wall. Tumors from treated mice manifested lower MMP activity than those from control animals. These reports support the use of MMP inhibitors alone or as an adjunct in the treatment of pancreatic cancer.

Matrix metalloproteinase inhibition suppresses MMP-2 activity and activation of PANC-1 cells in vitro

BACKGROUND

We have shown previously that the metalloproteinase inhibitor, BB-94, prolongs survival and attenuates MMP-2 activity in a murine model of pancreatic cancer. The purpose of this study was to determine the effect of BB-94 on the activity and activation of MMP-2 by PANC-1 cells in vitro.

MATERIALS AND METHODS

The poorly differentiated pancreatic cancer cell line PANC-1 was stimulated in vitro with the phorbol ester PMA (20 nM) and grown in the presence of increasing doses of BB-94 (0, 40, 200, and 400 ng/ml) for 24 h. Activation of MMP-2 was determined by gel zymography. In a separate experiment detailing the effects of BB-94 on MMP-2 activity, PANC cells were stimulated for 24 h with PMA and run out on four separate zymograms, each incubated in the previously noted concentrations of BB-94. Using densitometry, band intensity on all gels was determined and compared for each concentration of BB-94. The Matrigel assay was used to determine BB-94's effect on the invasive potential of PANC cells at the previously studied concentrations. The presence of MT-MMP (a putative component of MMP-2 activation) was confirmed using Western blot in each group.

RESULTS

BB-94 inhibited the conversion of latent to active MMP-2 in a dose-dependent fashion. BB-94 also inhibited the activity of MMP-2 when run out on gel zymograms incubated with increasing concentrations of BB-94. Decreased activity and activation of MMP-2 by BB-94 were manifested by a significant reduction in the invasive potential of PANC as determined by the Matrigel assay. MT-MMP was universally present in each study group.

CONCLUSIONS

The previously described salutary effects of MMP blockade in mice implanted with pancreatic cancer can be explained in vitro by a dose-dependent diminution of MMP-2 activity and activation in PANC cells exposed to BB-94.

Induction of tolerance to hemorrhagic or endotoxic shock involves activation of NF-kappaB

BACKGROUND

Tolerance to hemorrhagic or endotoxic shock can be induced by prior sublethal hemorrhage (SLH). The purpose of this study was to explore whether alterations in signal transduction pathways involving NF-kappaB occur in macrophages (Mphi) following induction of tolerance by SLH.

METHODS

Using a model of SLH previously shown in our lab to impart a survival benefit to subsequent hemorrhagic or endotoxic shock, rats (n = 30) were conditioned by SLH. Peritoneal Mphi were harvested 24 h after conditioning and stimulated with lipopolysaccharide (LPS) (10 microg/mL). Nuclear and cytosolic proteins were isolated 1 h later for determination of NF-kappaB activation by gel-shift assay and IkappaB-alpha by Western blot. TNF mRNA gene expression was measured 4 h after LPS stimulation by reverse transcription/polymerase chain reaction (RT/PCR). TNF protein levels were measured in cellular supernatants by enzyme-linked immunosorbent assay (ELISA) 18 h after LPS. RESULTS. LPS stimulation of sham Mphi increased NF-kappaB activation with corresponding loss of its inhibitor IkappaB-alpha. In contrast, IkappaB-alpha was not detectable following conditioning, and conditioned Mphi had NF-kappaB activation at baseline which increased minimally with LPS stimulation. LPS increased TNF gene expression and significantly increased protein production by both sham and conditioned Mphi, but this increase was greater in the sham-conditioned group.

CONCLUSIONS

The ability of Mphi from animals made tolerant by SLH to produce TNF in vitro is conserved. Nevertheless, these same Mphi exhibit alterations in TNF gene induction and expression as well as signal transduction, specifically, changes in IkappaB-alpha and NF-kappaB activation. This suggests a role for activation of NF-kappaB in the induction of tolerance.

Matrix metalloproteinase (MMP) inhibition selectively decreases type II MMP activity in a murine model of pancreatic cancer

BACKGROUND

Basement membrane degradation is a critical component of tumor invasion and metastasis that is facilitated by the family of enzymes known as matrix metalloproteinases (MMPs). MMP-2 and MMP-9 are two subtypes that have specifically been identified in tumors of gastrointestinal origin. We have previously shown that broad inhibition of these enzymes with the MMP inhibitor BB-94 improves survival in a murine model of pancreatic cancer. The purpose of this study was to determine MMP-2 and MMP-9 activity in orthotopic tumors from mice treated with and without BB-94.

METHODS

Ten million cells of a moderately differentiated pancreatic cancer cell line (HPAC) were implanted orthotopically into Balb/c nu/nu mice. The mice were treated with BB-94 or vehicle control for 70 days or until death. At necropsy, tumors were harvested, total protein was extracted, and MMPs were purified from 400 microgram of crude protein extract by gelatin-Sepharose affinity chromatography. Relative enzyme levels and activity of MMP-2 and MMP-9 were determined by Western blot and gelatin zymography.

RESULTS

Tumors from treated animals were significantly smaller than those from nontreated animals. MMP-2 was present in greater amounts in both treated and nontreated animals than MMP-9. Active MMP-2 was present in both groups but significantly decreased in animals treated with BB-94. Active MMP-9 was absent in both groups, whereas levels of latent MMP-9 appeared lower than those of MMP-2 in all samples.

CONCLUSIONS

Activated MMP-2 and not MMP-9 in HPAC cells grown in nude mice suggests that this MMP subtype is more critical in the phenotypic behavior of such tumors. Furthermore, attenuated levels of active MMP-2 in animals treated with the enzyme inhibitor BB-94 suggest that previously observed improvements in survival correlate with the level of MMP-2 activity.