The elastase infusion model of experimental aortic aneurysms: synchrony of induction of endogenous proteinases with matrix destruction and inflammatory cell response

PURPOSE

Perfusion of the isolated aorta of the rat with a saline solution containing pancreatic elastase induces an abdominal aortic aneurysm (AAA). An interesting feature of this model is the phenomenon of latency, suggesting that additional steps beyond the initial injury are required for AAA formation. This study was performed to determine whether the latency period for aortic dilation to aneurysmal proportions is correlated with the appearance of proteinases of endogenous origin and the interval for infiltration of inflammatory cells.

METHODS

Twenty Wistar rat aortas were perfused with the test solution, and 20 with normal saline solution. Laparotomy was performed on days 1, 2, 3, and 6 for measurement and harvest of the aorta. Histochemical studies were performed to analyze changes in matrix proteins, and substrate gel enzymography was used to determine the appearance of endogenous proteinases. Immunohistochemical studies were performed with monoclonal antibodies to T cells (CD-4, -5, and -8), monocytes/macrophages (ED-2), B cells (LC-A), immunoglobulin G, and immunoglobulin M.

RESULTS

The exogenously administered elastase was not detectable beyond day 2, but the aortic diameter did not progress to aneurysmal dimensions until the interval between days 3 and 6. During the period from day 3 to day 6, multiple endogenous matrix proteinases became detectable in the aortic tissue preparations. Immunohistochemical study revealed progressive infiltration of the aorta with various subsets of inflammatory cells.

CONCLUSION

The results suggest that the latency in AAA formation in this model corresponds with a complex sequence of biochemical and cellular events. The model provides an "early window" into these interesting early phases leading to aneurysm formation.

Demonstration of interstitial collagenase in abdominal aortic aneurysm disease

This study was performed to evaluate the presence of interstitial collagenase, now known as matrix metalloproteinase-1 (MMP-1), in specimens of abdominal aortic aneurysms (AAA). Eight AAA and four control infrarenal aortas were evaluated. After homogenization and extraction of soluble proteins, immunoblots of the extracts equalized for protein content were performed with a specific antibody to MMP-1. Under native conditions, immunoreactive material was distributed between M(r) 27 kDa to > 106 kDa. When the extracts were reduced and denatured, immunoreactive bands were detected in AAA at the expected M(r)'s of the secreted isoforms (57 and 52 kDa), whereas control aortic extracts had low levels of detectable immunoreactive material. Only extracts from AAA demonstrated significant immunoreactivity to the lower M(r) isoforms (22, 25, and 27 kDa), which correspond to reported cleavage products of MMP-1. Preliminary immunofluorescent studies of AAA localized MMP-1 to cells present in the adventitia of AAA. These findings will help to resolve disagreement in the recent literature regarding the presence of collagenolytic activity in AAA disease.

Factors that affect the survival rate of patients with ruptured abdominal aortic aneurysms

PURPOSE

There has been much discussion in the literature of factors that affect the mortality rate of patients who undergo repair of ruptured abdominal aortic aneurysms. Some studies have suggested restricting patient selection for repair on the basis of certain preoperative factors including age, increased creatinine level, low hemoglobin level, loss of consciousness, electrocardiographic changes, and preoperative cormorbid medical conditions. A retrospective review of 96 patients who underwent repair of a ruptured abdominal aortic aneurysm was performed to determine whether these factors would necessarily be applicable to all populations.

METHODS

A retrospective chart review of all patients who underwent repair of a ruptured abdominal aortic aneurysm was performed over a study period of 20 years. Data was analyzed by both univariate and multivariate analysis.

RESULTS

The mean age of the patients was 73 years. The intraoperative mortality rate was 23%. The in-hospital mortality rate was 60.4%, with a 30-day mortality rate of 56.3%. By univariate analysis of various factors associated with the mortality rate, hemoglobin level, creatinine level, lowest preoperative and average intraoperative systolic blood pressure, packed red blood cells transfused, estimated blood loss, intraoperative urine output, and temperature were statistically significant. A history of loss of consciousness was also statistically significant. No preoperative comorbid medical conditions were significant, nor was age. On a multivariate analysis, preoperative factors of loss of consciousness, a lowest preoperative systolic blood pressure less than 90 mm Hg, a hemoglobin level less than 10 g/dl, and a creatinine level greater than 1.5 mg/dl were predictive of death. The effects of the hemoglobin level, creatinine level, and loss of consciousness on the mortality rate were strongest in patients who had a lowest preoperative systolic blood pressure greater than 90 mm Hg. In patients who had the sets of preoperative factors that were associated with a 100% mortality rate, there were intraoprative factors that influenced their death.

CONCLUSIONS

These findings suggest that the factors (loss of consciousness, creatinine level, hemoglobin level) that are predictive of death may be a reflection of shock in this patient population. Further studies should be directed to optimizing preoperative resuscitation. Patients who have a ruptured abdominal aortic aneurysm should not be denied therapy on the basis of any specific set of preoperative factors.

Laparoscopically assisted abdominal aortic aneurysm repair: first 20 cases

PURPOSE

Laparoscopic surgery decreases postoperative pain, shortens hospital stay, and returns patients to full functional status more quickly than open surgery for a variety of surgical procedures. This study was undertaken to evaluate laparoscopic techniques for application to abdominal aortic aneurysm (AAA) repair.

METHODS

Twenty patients who had AAAs that required a tube graft underwent laparoscopically assisted AAA repair. The procedure consisted of transperitoneal laparoscopic dissection of the aneurysm neck and iliac vessels. A standard endoaneurysmorrhaphy was then performed through a minilaparotomy using the port sites for the aortic and iliac clamps. Data included operative times, duration of nasogastric suction, intensive care unit days, and postoperative hospital days. Pulmonary artery catheters and transesophageal echocardiography were used in seven patients. For these patients data included heart rate, pulmonary artery systolic and diastolic pressures, mean arterial pressure, central venous pressure, pulmonary capillary wedge pressure, cardiac index, and end diastolic area. Data were obtained before induction, during and after insufflation, during aortic cross-clamp, and at the end of the procedure.

RESULTS

Laparoscopically assisted AAA repair was completed in 18 of 20 patients. Laparoscopic and total operative times were 1.44 +/- 0.44 and 4.1 +/- 0.92 hours, respectively. Duration of nasogastric suction was 1.3 +/- 0.7 days. Intensive care unit stay was 2.2 +/- 0.9 days. The mean length of hospital stay was 5.8 days excluding three patients who underwent other procedures. There were two minor complications, one major complication (colectomy after colon ischemia), and no deaths. For the eight patients who had intraoperative transesophageal echocardiographic monitoring, no changes were noted in heart rate, pulmonary artery systolic pressure, pulmonary capillary wedge pressure, and cardiac index. Pulmonary artery diastolic pressure and central venous pressure were greatest during insufflation without changes in end-diastolic area. Volume status, as reflected by end-diastolic area and pulmonary capillary wedge pressure, did not change.

CONCLUSIONS

Laparoscopically assisted AAA repair is technically challenging but feasible. Potential advantages may be early removal of nasogastric suction, shorter intensive care unit and hospital stays, and prompt return to full functional status. The hemodynamic data obtained from the pulmonary artery catheter and transesophageal echocardiogram during pneumoperitoneum suggest that transesophageal echocardiography may be sufficient for evaluation of volume status along with the added benefit of detection of regional wall motion abnormalities and aortic insufficiency. Further refinement in technique and instrumentation will make total laparoscopic AAA repair a reality.

Elastin degradation products induce adventitial angiogenesis in the Anidjar/Dobrin rat aneurysm model

BACKGROUND

Infusion of the abdominal aorta with pancreatic elastase induces aneurysms in a rat model (Anidjar/Dobrin). Because elastolysis liberates elastin degradation products (EDPs), the present experiment was carried out to test the hypothesis that an EDP alone could induce features of aneurysm disease.

METHODS

The EDP val/gly/val/ala/pro/gly (VGVAPG), elastase, or saline solution was infused into infrarenal aorta (n = 4/group). After 1 week aortic diameters were measured, and the tissues were prepared for histologic examination. Adventitial capillaries (vessels per high-power field) were counted over a standardized preparation of aorta. Wall thickness was measured by means of computer-aided planimetry.

RESULTS

There was an increase of greater than 100-fold in mean vessels per high-power field in aortas receiving VGVAPG or elastase versus saline controls (4.10 +/- 0.68 SEM or 4.48 +/- 0.49 SEM versus 0.03 +/- 0.03 SEM, respectively, p < 0.05). The VGVAPG-perfused group had a 26% +/- 4% SEM increase in diameter from baseline that was statistically significant (p < 0.01), but the aortas did not reach aneurysmal dimensions.

CONCLUSIONS

Although no aneurysms occurred at 1 week after the infusion of EDP, the results demonstrate that the EDP VGVAPG can induce a characteristic feature of aneurysm disease. The model permits study of the earliest stages of experimental aneurysm formation and raises interesting questions regarding the role of the vasa vasorum in this pathologic process.

Strategies to improve adherence and acceptability of hormonal methods for contraception

BACKGROUND

Worldwide, hormonal contraceptives are among the most popular reversible contraceptives in current use. Despite their high theoretical effectiveness, typical use results in much lower effectiveness. In large part, this disparity reflects difficulties in adherence to the contraceptive regimen and low rates for long-term continuation.

OBJECTIVES

To determine the effectiveness of ancillary techniques to improve adherence to, and continuation rates of, hormonal methods of contraception.

SEARCH STRATEGY

We searched computerized databases for randomized controlled trials (RCTs) comparing client-provider interventions with standard family planning counseling. Sources included CENTRAL, MEDLINE, EMBASE, POPLINE, LILACS, and PsycINFO.

SELECTION CRITERIA

Randomized controlled trials (RCTs) of an intensive counseling technique or client-provider intervention versus routine family planning counseling. Interventions included group motivation; structured, peer, or multi-component counseling; and intensive reminders of appointments. Outcome measures were discontinuation, reasons for discontinuation, number of missed pills and on-time injections, and pregnancy.

DATA COLLECTION AND ANALYSIS

The primary author evaluated all titles and abstracts from the searches to determine eligibility. Two authors independently extracted data from the included studies. With RevMan 4.2, we calculated the odds ratio for all dichotomous outcomes and the weighted mean difference for continuous data. The studies were so different that we could not conduct a meta-analysis.

MAIN RESULTS

We found six RCTs; only one showed a statistically significant benefit of the experimental intervention. In that trial, women who received repeated, structured information about the injectable contraceptive depo-medroxyprogesterone acetate (DMPA) were less likely to have discontinued the method by 12 months (OR 0.27; 95% CI 0.16 to 0.44) than were women who had routine counseling. The intervention group was also less likely to discontinue due to menstrual disturbances. In another study, the intervention group was less likely to discontinue due to dissatisfaction with the contraceptive method, but overall continuation was not affected.

AUTHORS' CONCLUSIONS

Most studies to date have shown no benefit of strategies to improve adherence and continuation. These trials have important limitations, however. Two had small sample sizes, several had high losses to follow-up, and the intervention and its intensity varied across the studies. High-quality research is a priority, since adherence and continuation are fundamentally important to the successful use of hormonal contraceptives.

Perioperative predictors of colonic ischemia after ruptured abdominal aortic aneurysm

PURPOSE

Colonic ischemia and colonic resection occur frequently after ruptured abdominal aortic aneurysm (rAAA). The purpose of this study was to identify the perioperative risk factors that might help to determine earlier in the postoperative period which patients are at risk for colonic ischemia and colonic resection.

METHODS

The medical records of the 43 patients who underwent repair of rAAA from January 1989 to November 1997 were reviewed. The data were reviewed for the following factors: acidosis, pressor agents, lactate levels, guaiac status, cardiac index, coagulopathy, early postoperative bowel movement, the lowest intraoperative pH level, the temperature at the conclusion of the case, the location and duration of aortic cross clamping, the amount of fluid boluses administered after surgery, the amount of packed red blood cells administered during the case, and the average systolic blood pressure at admission and during surgery. Univariate analysis was performed with Fisher exact test, chi2 test, and Student t test. Multivariate analyses also were performed with the variables that were found to be significant on the univariate analysis.

RESULTS

Thirteen of the 43 patients (30. 2%) had colonic ischemia, and seven of the 13 underwent colonic resection (53.8%). The overall mortality rate was 51.2% (22/43) five of the deaths were intraoperative and excluded from the study. In a comparison of the patients who had colonic ischemia with those who did not, statistically significant differences were found in the following variables: average systolic blood pressure at admission 90 mm Hg or less, hypotension of more than 30 minutes' duration, temperature less than 35 degreesC, pH less than 7.3, fluid boluses administered after surgery 5 L or more, and packed red blood cells 6 units or more. Multivariate analysis indicated that the number of these variables present correlated significantly with the positive predicted probability of colonic ischemia occurring. No patient with two factors or fewer had an ischemic bowel, and the positive predictive probability of colonic ischemia for those patients with six factors was 80%.

CONCLUSION

The results of this study show that: (1) colonic ischemia after rAAA may be predicted with the presence of two or more specific perioperative factors, (2) the lack of a guaiac-positive bowel movement may be misleading for the early diagnosis of colonic ischemia, and (3) more than 50% of the patients with colonic ischemia will require a colonic resection. We recommend that any patient with rAAA with more than two perioperative factors undergo sigmoidoscopy every 12 hours after surgery for 48 hours to rule out colonic ischemia without waiting for early or guaiac-positive bowel movement.

Minimal incision abdominal aortic aneurysm repair

PURPOSE

The use of a limited incision for abdominal aortic aneurysm (AAA) repair was evaluated, and its outcome was analyzed in comparison to laparoscopic-assisted and standard open repair.

METHODS

Eleven patients who had an AAA that required a tube graft underwent minimal incision (MINI) repair. The procedure consisted of a standard endoaneurysmorrhaphy performed through an 8- to 10-cm minilaparotomy. Clinical characteristics, in-hospital outcomes, and total in-hospital charges for this procedure were then compared with those of comparative groups of patients who had undergone repair of AAA by means of a laparoscopic-assisted (LAP) approach or a standard open (OPEN) technique.

RESULTS

MINI repair was successfully completed in all 11 patients. Patients in the three groups were comparable for age, sex, risk factors, and aortic dimensions. The mean values for operative time, blood loss, length of hospital stay, and total hospital charges for the three comparison groups were: 129. 7 minutes (MINI) vs. 244.8 minutes (LAP)*, 209.9 minutes (OPEN)*; 522.7 mL (MINI) vs. 1214.7 mL (LAP), 1795.8 mL (OPEN)*; 5.18 days (MINI) vs. 18.7 days (LAP), 17.4 days (OPEN); $22,692 (MINI) vs. $59, 922 (LAP)*, $62,324 (OPEN)* (*P <.05). Local complications occurred in 18.2% of patients who underwent MINI repair, 23.5% of patients who underwent LAP repair, and 29.7% of patients who underwent OPEN repair (P = not significant). Patients undergoing minilaparotomy demonstrated decreased compromise of gastrointestinal function, with a decreased need for postoperative fluid resuscitation (6799.7 mL [MINI], 7781.8 mL [LAP] vs. 11061.1 mL [OPEN]*) and shortened nasogastric tube decompression (1.6 days [MINI], 1.5 days [LAP] vs. 4.1 days [OPEN]*; *P <.05).

CONCLUSION

MINI repair is a technically feasible technique that combines the benefits of minimally invasive surgery with those of conventional open repair with few, if any disadvantages. Facility of the procedure, combined with the potential cost benefits, encourages further study for consideration of this technique as a viable alternative for the management of AAAs.

Multiple idiopathic arterial aneurysms in children: a case report and review of the literature

A 6-year-old boy from China presented initially at 2 years of age with a pulsatile mass in his right antecubital fossa. He was not fully evaluated until the age of six years, when pan-angiography and computed axial tomography scan revealed multiple aneurysms of his right brachial artery, right radial artery aneurysms, an infrarenal aortic aneurysm, and a right internal carotid artery aneurysm in the region of the cavernous sinus. The patient underwent uneventful repairs of both the abdominal aortic aneurysm and the multiple aneurysms of the right arm. Pathologic evaluation was significant for medial fibrosis of the arterial wall with decreased and disordered elastin fibers. Review of the previously reported cases in children indicate the upper extremity arteries are involved in 92% of patients, the aortoiliac region in 92% of patients, and the renal/mesenteric vessels in 77% of cases. Lower extremity and cerebrovascular arteries are involved to a lesser extent. Children with peripheral aneurysms should have pan-angiography performed before treatment is begun. Surgical repair in these cases has been excellent.

Relationship of protamine dosing with postoperative complications of carotid endarterectomy

Protamine sulfate (PS) neutralization of heparin (HEP) given during carotid endarterectomy (CEA) has been previously associated with an increased postoperative stroke rate. Dosing regimens of PS have varied in previous studies. The accuracy of PS dosing and its effect on postoperative complications was analyzed. The medical records of all patients undergoing elective CEAs from January 1993 to June 1996 in our institution were reviewed. A hematoma was defined as either an event requiring return to the operating room or when repeatedly identified in the medical record. The accuracy of dosing PS was determined utilizing a formula calculating the logarithmic exponential decay of HEP, which determined the residual HEP at the time of PS dosing. An ideal PS dose was then calculated and compared to the dose given. Statistical analyses was performed using a Fisher's exact test as well as the Student's t-test. Four hundred-seven CEAs were performed in 365 patients. There were 10/407 (2.5%) postoperative strokes (STROKE) and 11/407 (2.7%) hematomas, 3 of which required reoperation. Results indicate that (1) the administration of PS significantly reduced the incidence of postoperative hematoma; (2) there appears to be an association between the administration of PS and STROKE; (3) the inaccuracy in dosing PS appears to be based on a decision to dose PS to the total HEP given rather than the residual HEP on board at the time of neutralization. The effect of PS overdosing is unclear, but it may play a role in STROKE.

Warfarin anticoagulation in the perioperative period: is it safe?

This study was undertaken to determine if warfarin anticoagulation could be safely continued during surgery and in the perioperative period. An animal model was followed by a prospective human study of all patients on heparin or warfarin at the time of surgery. Twenty-four rabbits underwent laparotomy, during which a controlled liver injury was created and repaired. Group 1 (Warf) was anticoagulated with warfarin to raise the mean international normalization ratio (INR) to 2.5-3.0. Group 2 (Hep) was anticoagulated with heparin to raise the activated partial thromboplastin time to 1.5-2.0 times control. The heparin was then stopped 6 hr prior to surgery and resumed 6 hr postoperatively without a bolus. Group 3 (control) was not anticoagulated and received saline infusion. For the human study, data were collected on 40 patients undergoing 50 operations from October 1996 to January 1998. The results of this study reveal that (1) bleeding was less in the group anticoagulated with warfarin throughout surgery in the animal model, (2) bleeding complications were less in the patients continued on warfarin through surgery than those on heparin (3) older patients may have an increased risk of bleeding, and (4) an INR of >3 at the time of surgery may increase the risk of bleeding.

Steroid hormones for contraception in men

BACKGROUND

Male hormonal contraception has been an elusive goal. Administration of sex steroids to men can shut off sperm production through effects on the pituitary and hypothalamus. However, this approach also decreases production of testosterone, so 'add-back' therapy is needed.

OBJECTIVES

To summarize all randomized controlled trials of male hormonal contraception.

SEARCH STRATEGY

We searched the computerized databases CENTRAL, MEDLINE, EMBASE, POPLINE, and LILACS (each from inception to March 2006) for randomized controlled trials of hormonal contraception in men. We wrote to authors of identified trials to seek unpublished or published trials that we might have missed.

SELECTION CRITERIA

We included all randomized controlled trials in any language that compared a steroid hormone with another contraceptive. We excluded non-steroidal male contraceptives, such as gossypol. We included both placebo and active-regimen control groups. All trials identified included only healthy men with normal semen analyses.

DATA COLLECTION AND ANALYSIS

Azoospermia (absence of spermatozoa on semen examination) was the primary outcome measure. Data were insufficient to examine pregnancy rates and side effects.

MAIN RESULTS

We found 30 trials that met our inclusion criteria. The proportion of men who achieved azoospermia varied widely in reports to date. A few important differences emerged from these trials: levonorgestrel implants combined with injectable testosterone enanthate (TE) were more effective than levonorgestrel 125 microg daily combined with testosterone patches; levonorgestrel 500 mug daily improved the effectiveness of TE 100 mg injected weekly; desogestrel 150 mug was less effective than desogestrel 300 mug (with testosterone pellets); testosterone undecanoate (TU) 500 mg was less likely to produce azoospermia than TU 1000 mg (with levonorgestrel implants); norethisterone enanthate 200 mg with TU 1000 mg led to more azoospermia when given every 8 weeks versus 12 weeks; four implants of 7-alpha-methyl-19-nortestosterone (MENT) were more effective than two MENT implants. Several trials showed promising efficacy in terms of percentages with azoospermia. Three examined desogestrel and testosterone preparations or etonogestrel (metabolite of desogestrel) and testosterone, and two examined levonorgestrel and testosterone.

AUTHORS' CONCLUSIONS

No male hormonal contraceptive is ready for clinical use. Most trials were small exploratory studies. As a result, their power to detect important differences was limited and their results imprecise. In addition, the definition of oligozoospermia has been imprecise or inconsistent. To avoid bias, future trials need more attention to the methodological requirements for randomized controlled trials. More trials with adequate power would also be helpful.

Effect of a Decision Aid on Agreement Between Patient Preferences and Repair Type for Abdominal Aortic Aneurysm: A Randomized Clinical Trial

Importance

Patients with abdominal aortic aneurysm (AAA) can choose open repair or endovascular repair (EVAR). While EVAR is less invasive, it requires lifelong surveillance and more frequent aneurysm-related reinterventions than open repair. A decision aid may help patients receive their preferred type of AAA repair.

Objective

To determine the effect of a decision aid on agreement between patient preference for AAA repair type and the repair type they receive.

Design, Setting, and Participants

In this cluster randomized trial, 235 patients were randomized at 22 VA vascular surgery clinics. All patients had AAAs greater than 5.0 cm in diameter and were candidates for both open repair and EVAR. Data were collected from August 2017 to December 2020, and data were analyzed from December 2020 to June 2021.

Interventions

Presurgical consultation using a decision aid vs usual care.

Main Outcomes and Measures

The primary outcome was the proportion of patients who had agreement between their preference and their repair type, measured using χ2 analyses, κ statistics, and adjusted odds ratios.

Results

Of 235 included patients, 234 (99.6%) were male, and the mean (SD) age was 73 (5.9) years. A total of 126 patients were enrolled in the decision aid group, and 109 were enrolled in the control group. Within 2 years after enrollment, 192 (81.7%) underwent repair. Patients were similar between the decision aid and control groups by age, sex, aneurysm size, iliac artery involvement, and Charlson Comorbidity Index score. Patients preferred EVAR over open repair in both groups (96 of 122 [79%] in the decision aid group; 81 of 106 [76%] in the control group; P = .60). Patients in the decision aid group were more likely to receive their preferred repair type than patients in the control group (95% agreement [93 of 98] vs 86% agreement [81 of 94]; P = .03), and κ statistics were higher in the decision aid group (κ = 0.78; 95% CI, 0.60-0.95) compared with the control group (κ = 0.53; 95% CI, 0.32-0.74). Adjusted models confirmed this association (odds ratio of agreement in the decision aid group relative to control group, 2.93; 95% CI, 1.10-7.70).

Conclusions and Relevance

Patients exposed to a decision aid were more likely to receive their preferred AAA repair type, suggesting that decision aids can help better align patient preferences and treatments in major cardiovascular procedures.

Trial Registration

ClinicalTrials.gov Identifier: NCT03115346.

Pro-inflammatory cytokines from Kupffer cells downregulate hepatocyte expression of adrenomedullin binding protein-1

Polymicrobial sepsis is characterized by an early, hyperdynamic phase followed by a late hypodynamic phase. Adrenomedullin (AM), a vasodilatory peptide, inhibits this transition from the early phase to the late phase. Adrenomedullin binding protein-1 (AMBP-1) enhances AM-mediated activities. The decrease of AMBP-1 levels in late sepsis reduces the vascular response to AM and produces the hypodynamic phase. Studies have indicated that the administration of LPS downregulates AMBP-1 production in the liver. Since hepatocytes are the primary source of AMBP-1 biosynthesis in the liver, we employed a co-culture strategy using hepatocyte and Kupffer cells to determine whether LPS directly or by increasing pro-inflammatory cytokines from Kupffer cells downregulates AMBP-1 production. Hepatocytes and Kupffer cells isolated from rats were co-cultured and treated with LPS for 24 h. LPS significantly attenuated AMBP-1 protein expression in a dose-dependent manner. Since AMBP-1 is basically a secretory protein, cell supernatants from co-culture cells treated with LPS were examined for AMBP-1 protein levels. LPS treatment caused a dose related decrease in AMBP-1 protein secretion. Similarly, LPS treatment produced a significant decrease in AMBP-1 protein expression in hepatocytes and Kupffer cells cultured using transwell inserts. LPS had no direct effect on AMBP-1 levels in cultured hepatocytes or Kupffer cells alone. To confirm that the observed effects in co-culture were due to the cytokines released from Kupffer cells, hepatocytes were treated with IL-1beta or TNF-alpha for 24 h and AMBP-1 expression was examined. The results indicated that both cytokines significantly inhibited AMBP-1 protein levels. Thus, pro-inflammatory cytokines released from Kupffer cells are responsible for downregulation of AMBP-1.

Reduced protease inhibitory capacity in patients with abdominal aortic aneurysms is reversed with surgical repair

BACKGROUND

Abdominal aortic aneurysm (AAA) disease is a complex degenerative process that is associated with elevated proteolytic activity. This increased proteolytic activity may be linked to an imbalance in the protease regulatory mechanisms. We hypothesize that reduced AAA plasma inhibitory capacity is related to increased elastolytic activity observed in patients with AAA, which promotes matrix degradation in the aortic wall and AAA expansion.

METHODS

Preoperative plasma from patients with AAA (n = 86; mean age, 75 +/- 8 years) and healthy controls (n = 30; mean age, 72 +/- 10 years) was assayed for inhibitory capacity. Postoperative plasma inhibitory capacity was evaluated with comparison of the activity of porcine pancreatic elastase on succinylated elastin substrate, in the presence and absence of AAA and control plasma.

RESULTS

AAA plasma showed a significantly reduced capacity to inhibit porcine pancreatic elastase (71.31% +/- 1.47%) compared with control plasma (85.52% +/- 1.70%; P <.001). Within the AAA group, the inhibitory capacity increased with AAA diameter (P <.05). In addition, surgical repair of AAA resulted in a significant increase in plasma inhibitory capacity (79.83% +/- 1.86%) as compared with preoperative levels (63.98% +/- 2.69%; P <.001). Of note, the postoperative plasma inhibitory capacity is not significantly different than that of control.

CONCLUSION

AAA plasma has a significantly reduced inhibitory capacity, which varies with aortic diameter and returns to control levels after surgical repair of the AAA. This suggests that protease regulation is a dynamic balance that changes with AAA progression and may play an important role in AAA progression.

Design of the PReferences for Open Versus Endovascular Repair of Abdominal Aortic Aneurysm (PROVE-AAA) Trial

For patients with abdominal aortic aneurysm (AAA), randomized trials have found endovascular AAA repair (EVAR) is associated with lower perioperative morbidity and mortality than open surgical repair (OSR). However, OSR has fewer long-term aneurysm-related complications, such as endoleak or late rupture. Patients treated with EVAR and OSR have similar survival rates within two years after surgery, and OSR does not require intensive surveillance. Few have examined if patient preferences are aligned with the type of treatment they receive for their AAA. Although many assume that patients may universally prefer the less-invasive nature of EVAR, our preliminary work suggests that patients who value the lower risk of late complications may prefer OSR. In this study, called The PReferences for Open Versus Endovascular Repair of Abdominal Aortic Aneurysm (PROVE-AAA) trial, we describe a cluster-randomized trial to test if a decision aid can better align patients' preferences and their treatment type for AAA. Patients enrolled in the study are candidates for either endovascular or open repair and are followed up at VA hospitals by vascular surgery teams who regularly perform both types of repair. In Aim 1, we will determine patients' preferences for endovascular or open repair and identify domains associated with each repair type. In Aim 2, we will assess alignment between patients' preferences and the repair type elected and then compare the impact of a decision aid on this alignment between the intervention and control groups. This study will help us to accomplish two goals. First, we will better understand the factors that affect patient preference when choosing between EVAR and OSR. Second, we will better understand if a decision aid can help patients be more likely to receive the treatment strategy they prefer for their AAA. Study enrollment began on June 1, 2017. Between June 1, 2017 and November 1, 2018, we have enrolled 178 of a total goal of 240 veterans from 20 VA medical centers and their vascular surgery teams across the country. We anticipate completing enrollment in PROVE-AAA in June 2019, and study analyses will be performed thereafter.

Simple model for ac ionic conduction in solids

We present a model for the ac conduction in ionically conducting solids that takes into account, in a simple way, the interaction between carriers. The Coulomb force forms an "ionic atmosphere" that exerts a restoring force on a central ion, whose motion corresponds to an overdamped oscillator. We consider the effect of the relaxation of the ionic atmosphere by introducing an additional equation for the displacement of the potential toward the particle position. The general behavior of the ac conductivity can be understood in terms of two types of motions: motion of the bound ion at high frequencies determined by microscopic friction, and a much slower motion coupled to the surrounding carriers relaxation at low frequencies.