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Background: The usual location of thoracic blunt traumatic aortic injury (BTAI) is just distal to the left subclavian artery; however, injuries can also be found in other locations in the descending thoracic aorta (DTA)., Methods: This is a single-institution, retrospective study, using 74 consecutive BTAI in the DTA. The patients were separated into two groups based on the location of the injury. The proximal group included injuries within 5 cm of the left subclavian artery, whereas the distal group included injuries in the rest of the DTA. A total of 27 factors were compared., Results: Between 2010 and July 2017, we identified 14 of 74 patients (19%) with BTAI in the distal zone. Females were 9 of the 14 (64%) in the distal zone group, whereas females were 16 of 60 (27%) in the proximal zone group (P < .012). Thoracic spine fractures occurred in 7 of the 14 patients (50%) with injuries at the distal zone, whereas they occurred in 12 of the 60 patients (20%) in the proximal zone group (P < .038). Eleven of the 14 distal zone injuries (79%) were grade 1 or 2 compared with 15 of 60 injuries (25%) at the proximal zone (P = .016). Only 2 of the 14 injuries (14%) in the distal zone required an endovascular repair as opposed to 39 of 60 (65%) in the proximal zone (P < .001). The mean hospital duration of stay in patients with BTAI at the distal zone was 8.5 days compared with 20.3 days for patients in the proximal zone group (P < .004). Mortality occurred in 5 of 14 patients (36%) in the distal zone group compared with 5 of 60 patients (8%) in the proximal zone group (P = .017). The odds of mortality from an injury in the distal zone were almost 6-fold greater than the odds of mortality from an injury in the proximal zone (odds ratio, 5.9; 95% confidence interval, 1.2-31.8). No mortalities were related to the BTAI itself. The association of location with mortality remained significant even after adjusting for other significant factors like Injury Severity Score and patient age. Patients who died from injuries in the distal zone had a shorter duration of stay (5 days vs 20 days; P = .0002)., Conclusions: BTAI in the distal zone of DTA are associated with unique characteristics. They are (1) more frequently associated with thoracic spine fractures, (2) more common in women, (3) tend to be lower grade, (4) less likely to require intervention, and (5) seem to have a higher mortality owing to other associated traumatic injuries., (Copyright © 2018 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.)

Protein N-glycosylation has been identified in all three domains of life presumably conserved for its early role in glycoprotein folding. However, the N-glycans added to proteins in the secretory pathway of multicellular organisms are remodeling in the Golgi, increasing structural diversity exponentially and adding new layers of functionality in immunity, metabolism and other systems. The branching and elongation of N-glycan chains found on cell surface receptors generates a gradation of affinities for carbohydrate-binding proteins, the galectin, selectin and siglec families. These interactions adapt cellular responsiveness to environmental conditions, but their complexity presents a daunting challenge to drug design. To gain further insight, I review how N-glycans biosynthesis and biophysical properties provide a selective advantage in the form of tunable and ultrasensitive stimulus-response relationships. In addition, the N-glycosylation motif favors step-wise mutational experimentation with sites. Glycoproteins display accelerated evolution during vertebrate radiation, and the encoding asymmetry of NXS/T(X≠P) has left behind phylogenetic evidence suggesting that the genetic code may have been selected to optimize diversity in part through emerging posttranslational modifications., (Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.)

Metabolomics is the identification and quantitation of small bio-molecules (metabolites) in biological samples under various environmental and genetic conditions. Mass spectrometry provides the unique opportunity for targeted identification and quantification of known metabolites by selective reaction monitoring (SRM). However, reproducibility of this approach depends on careful consideration of sample preparation, chemical classes, and stability of metabolites to be evaluated. Herein, we introduce and validate a targeted metabolite profiling workflow for cultured cells and tissues by liquid chromatography-triple quadrupole tandem mass spectrometry. The method requires a one-step extraction of water-soluble metabolites and targeted analysis of central metabolites that include glycolysis, amino acids, nucleotides, citric acid cycle, and the hexosamine biosynthetic pathway. The sensitivity, reproducibility and molecular stability of each targeted metabolite were assessed under experimental conditions. Quantitation of metabolites by peak area ratio was linear with a dilution over a 4 fold dynamic range with minimal deviation R(2)=0.98. Inter- and intra-day precision with cells and tissues had an average coefficient of variation <15% for cultured cell lines, and somewhat higher for mouse liver tissues. The method applied in triplicate measurements readily distinguished immortalized cells from malignant cells, as well as mouse littermates based on their hepatic metabolic profiles., (Copyright © 2014. Published by Elsevier B.V.)

Objective: The ideal hemostatic agent for treatment of suture-line bleeding at vascular anastomoses has not yet been established. This study evaluated whether the use of a fibrin sealant containing 500 IU/mL thrombin and synthetic aprotinin (FS; marketed in the United States under the name TISSEEL) is beneficial for treatment of challenging suture-line bleeding at vascular anastomoses of expanded polytetrafluoroethylene (ePTFE) grafts, including those further complicated by concomitant antiplatelet therapies., Methods: Over a 1-year period ending in 2010, ePTFE graft prostheses, including arterio-arterial bypasses and arteriovenous shunts, were placed in 140 patients who experienced suture-line bleeding that required treatment after completion of anastomotic suturing. Across 24 US study sites, 70 patients were randomized and treated with FS and 70 with manual compression (control). The primary end point was the proportion of patients who achieved hemostasis at the study suture line at 4 minutes after start of application of FS or positioning of surgical gauze pads onto the study suture line., Results: There was a statistically significant difference in the comparison of hemostasis rates at the study suture line at 4 minutes between FS (62.9%) and control (31.4%) patients (P < .0001), which was the primary end point. Similarly, hemostasis rates in the subgroup of patients on antiplatelet therapies were 64.7% (FS group) and 28.2% (control group). When analyzed by bleeding severity, the hemostatic advantage of FS over control at 4 minutes was similar (27.8% absolute improvement for moderate bleeding vs 32.8% for severe bleeding). Logistic regression analysis (accounting for gender, age, intervention type, bleeding severity, blood pressure, heparin coating of ePTFE graft, and antiplatelet therapies) found a statistically significant treatment effect in the odds ratio (OR) of meeting the primary end point between treatment groups (OR, 6.73; P < .0001), as well as statistically significant effects for intervention type (OR, 0.25; P = .0055) and bleeding severity (OR, 2.59; P = .0209). The safety profile of FS was excellent as indicated by the lack of any related serious adverse events., Conclusions: The findings from this phase 3 study confirmed that FS is safe and its efficacy is superior to manual compression for hemostasis in patients with peripheral vascular ePTFE grafts. The data also suggest that FS promotes hemostasis independently of the patient's own coagulation system, as shown in a representative population of patients with vascular disease under single- or dual-antiplatelet therapies., (Copyright © 2012 Society for Vascular Surgery. Published by Mosby, Inc. All rights reserved.)

Background: Explosive blasts are common in the modern military environment. These blasts incorporate a concussive component (primary blast injury) and a penetrating component (secondary blast injury). Penetrating injuries are the leading cause of death and injury in these attacks. This review characterizes the vascular injuries associated with penetrating blast injuries to the neck and provides recommendations on the early management of these casualties for the surgeon unfamiliar with these injuries., Methods: The Landstuhl Regional Medical Center Trauma Registry was queried for admissions from January 1, 2006, to June 30, 2010, coded for a penetrating injury to the neck caused by a blast mechanism. Medical records were abstracted from the patient's initial presentation and care through the deployed military medical system. We recorded the vascular injuries, diagnostic studies, operative events, and early postinjury course for all identified patients., Results: Query of the Landstuhl Regional Medical Center Trauma Registry initially identified 252 patients, of which 53 were excluded because their injuries arose from other mechanisms or were only superficial. Among the remaining 199 patients, 38 (19.1%) sustained 44 vascular injuries requiring treatment. Compelling physical examination findings ("hard signs") were present in 15 (7.5%), who underwent immediate neck exploration. Another 12 patients also underwent neck exploration without any prior imaging studies. Computed tomography (CT) or CT angiography (CTA) examinations were done in 172 patients without hard-sign physical examination findings. Of these, the result of the imaging study was negative in 106 patients, and no further investigation or treatment for cervical vascular trauma was initiated. Of 66 patients who underwent CT/CTA before operative neck exploration, CT/CTA identified a vascular injury in 26 that was later confirmed on neck exploration. The combination of physical examination and CT/CTA resulted in a sensitivity of 96.3% and a specificity of 97.2% in diagnosing cervical vascular injury., Conclusions: Penetrating cervical wounds from war-related blast trauma are associated with potentially life-threatening vascular injuries. The presenting physical examination, availability of CT/CTA, local surgical expertise, and tactical combat situation all contribute to surgical decision making in these patients. In patients without hard signs of vascular trauma and a normal CT/CTA of the neck, there is no evidence to support mandatory surgical neck explorations or further immediate diagnostic studies to exclude cervical vascular injury., (Published by Mosby, Inc.)

Glycosylation is a common posttranslational modification of proteins and lipids of the secretory pathway that generates binding sites for galactose-specific lectins or galectins. Branching of Asn-linked (N-)glycans by the N-acetylglucosaminyltransferases (Mgat genes) increases affinity for galectins. Both tissue-specific expression of the enzymes and the metabolic supply of sugar-nucleotides to the ER and Golgi regulate glycan distribution while protein sequences specify NXS/T site multiplicity, providing metabolic and genetic contributions to galectin-glycoprotein interactions. Galectins cross-link glycoproteins forming dynamic microdomains or lattices that regulate various mediators of cell adhesion, migration, proliferation, survival and differentiation. There are a similar number of galactose-specific galectins in C. elegans and humans, but expression of higher-affinity branched N-glycans are a more recent feature of vertebrate evolution. Galectins might be considered a reading code for repetition of the minimal units of binding [Gal(NAc)β1-3/4GlcNAc] and NXS/T site multiplicity in proteins. The rapidly evolving and structurally complex Golgi modifications to surface receptors are interpreted through affinity for the lattice, which regulates receptor levels as a function of the cellular environment, and thereby the probability of various cell fates. Many important questions remain concerning the regulation of the galectins, the glycan ligands and lattice interaction with other membrane domains and endocytic pathways., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Purpose: Our preliminary experience with physical examination alone in the evaluation of penetrating zone 2 neck injuries for vascular trauma was previously reported in 28 patients over a 2-year period (1991-1993). The purpose of the current study was to examine the results of this approach in a much larger group of patients over an 8-year period., Methods: The medical records for all patients admitted to our level I trauma center (all of them entered into our prospective protocol) between December 1991 and April 1999 with penetrating zone 2 neck trauma were reviewed for their initial presentation and any documented vascular injury., Results: A total of 145 patients made up the study group; in 30 of these patients, the penetrating trajectory also traversed zone 1 or 3. Thirty-one patients (21%) had hard signs of vascular injury (active bleeding, expanding hematoma, bruit/thrill, pulse deficit, central neurologic deficit) and were taken immediately to the operating room; 28 (90%) of these 30 patients had either major arterial or venous injuries requiring operative repair (the false-positive rate for physical examination thus being 10%). Of the 114 patients with no hard signs, 23 underwent arteriography because of proximity of the injury to the vertebral arteries or because the trajectory included another zone. Of these 23 arteriograms, three showed abnormalities, but only one required operative repair. This case had no complications relating to the initial delay. The remaining 91 patients with no hard signs were observed without imaging or surgery for a minimum of 23 hours, and none had any evidence of vascular injury during hospitalization or during the initial 2-week follow-up period (1/114; false-negative rate for physical examination, 0.9%)., Conclusions: This series confirms the earlier report indicating that patients with zone 2 penetrating neck wounds can be safely and accurately evaluated by physical examination alone to confirm or exclude vascular injury. The missed-injury rate is 0.7% (1/145) with this approach, which is comparable to arteriography in accuracy but less costly and noninvasive. Long-term follow-up is needed to confirm this management option.

Malignant transformation is accompanied by altered cell surface glycosylation. N-Linked oligosaccharides carrying beta1-6GlcNAc branches are associated with tumor invasion and metastasis. Therefore, compounds that can enter cells and block biosynthesis of beta1-6GlcNAc-branched glycans without overt cytotoxicity are potential anticancer agents. We have developed a homogeneous cell-based assay for detection of such compounds. The method enables identification of agents that block beta1-6GlcNAc-branched glycan expression after incubation for 16-20 h with MDAY-D2 tumor cells, thereby protecting the cells from the subsequent addition of leukoagglutinin, a cytotoxic plant lectin. We observed that MDAY-D2 cell number is directly proportional to the level of endogenous alkaline phosphatase activity measured spectrophotometrically in cultures after the addition of substrate. The alkaline phosphatase assay was capable of detecting as few as 1,500 cells. The assay was readily adapted for high-throughput screening as reagent costs are low and no cell harvesting and washing steps are required. Under high-throughput operating conditions, the coefficient of variation for controls was found to be 4.2%. The results suggest that measurement of alkaline phosphatase in this cell assay format may be adapted for wider applications in high-throughput screenings for compounds that relieve cells from other growth inhibitors.

Multiple mRNA isoforms are generated from Siat1, the gene encoding ST6Gal I (beta-galactoside alpha2,6-sialyltransferase, SiaT-1, ST6N, alpha2,6ST). These isoforms, transcriptionally initiated from a number of physically distinct promoter regions, differ only in the 5'-most untranslated region and share an identical ST6Gal I coding region. W16 cells, a spontaneous mutant from MDAY-D2, the highly metastatic murine lymphoid tumor cell line, is considerably less metastatic and exhibits significantly slower tumor growth characteristics [R. Takano, E. Muchmore, and J. W. Dennis (1994) Glycobiology 4, 665-674]. Takano et al. further reported that ST6Gal I mRNA in W16 is elevated 40-fold compared to the parental cells. Here, by means of 5'-RACE analysis, we demonstrate a heretofore undocumented ST6Gal I mRNA form expressed in W16 cells. This ST6Gal I mRNA contains a novel 5'-most untranslated region with 96% sequence similarity to the retroviral-like transposable element, intracisternal particle A (IAP). This observation suggests the notion that elevated ST6Gal I expression in W16 cells is the result of DNA rearrangement in the Siat1 locus. Atypical transcriptional activation of Siat1 is the result of this IAP transposition., (Copyright 1999 Academic Press.)

Purpose: Expanded polytetraflouroethylene (ePTFE) grafts are the most popular prosthetic grafts for hemodialysis patients in whom autogenous fistulas cannot be constructed. Long-term studies to study the durability and complication rate of the different wall configurations of ePTFE grafts have not been carried out. The primary, secondary, and cumulative patency and other complications between standard thickness (STD) and thin wall (THN) 6 mm stretch ePTFE grafts (WL Gore & Assoc, Flagstaff, AZ) was prospectively evaluated., Methods: From September 1993 to August 1995, 108 patients receiving new grafts were randomized into 2 groups: those receiving STD grafts (n = 56) or those receiving THN (n = 52) grafts. Data prospectively collected included day of first access, primary patency, interventions required, and long-term results. Infections, pseudoaneurysms, and mortality were also documented. Student's unpaired t-test was used to compare the 2 groups, and log-rank life tables were constructed and compared., Results: Mean follow-up examination time was 38.1 +/- 0.8 months for STD grafts and 35.1 +/- 1.0 months for THN grafts (P<.03). Longer patency was noted in the STD group of grafts (18.2 months for STD vs. 12.1 months for THN). Biographical data and complications, including pseudoaneurysm (6% vs. 5%), infection (2% vs. 3%), and mortality (22% vs. 19%), between STD and THN groups were not different statistically. Mean primary (18.2 months vs. 12.1 months), secondary (20.9 months vs. 13.7 months), and cumulative patency times (22.2 months vs. 15.2 months) for the STD group were significantly more than those for the THN group (P<.000 by log rank of life tables). Other complications were not different between groups., Conclusion: Standard thickness ePTFE is the graft of choice when placing ePTFE arteriovenous grafts for hemodialysis.

Purpose: Pulmonary embolus (PE) remains a major factor in morbidity and death in severely injured patients, especially those in specific high-risk groups. PEs have been documented to occur despite routine deep venous thrombosis prophylaxis. The purpose of this study was to evaluate the safety and efficacy of prophylactic Greenfield filter (PGF) placement in patients who have multiple trauma with known high-risk injuries for PE., Methods: From January 1992 to June 1994, PGF were prospectively placed in 108 patients who had an injury severity score greater than 9 and met one of the following criteria: (1) severe head injury with prolonged ventilator dependence, (2) severe head injury with multiple lower extremity fractures, (3) spinal cord injury with or without paralysis, (4) major abdominal or pelvic penetrating venous injury, (5) pelvic fracture with lower extremity fractures. These patients were compared with 216 patients, historically matched for age, sex, mechanism of injury, injury severity score, and days in the intensive care unit. Data analysis was done with chi-squared and Student's t testing., Result: There were no statistical differences between the PGF and control group with regard to age (35.9 +/- 1.5 vs 38.3 +/- 1.4), sex (male 76% vs 75.5%), days in the intensive care unit (21.2 +/- 1.4 vs 18.1 +/- 1.5), ISS (28.0 +/- 1.0 vs 25.4 +/- 0.8) and mechanism of injury (blunt 85% vs 81%). None of the patients in the PGF group had a PE. In the control group, however, 13 patients had a PE, nine of which were fatal. These differences were statistically significant for both PE (p < 0.009) and PE-related death (p < 0.03). The overall mortality rate was reduced in the PGF group (18 of 108, 16%) versus the control group (47 of 216, 22%); however, this did not achieve statistical significance., Conclusion: PGF insertion in selected patients at high risk who had trauma effectively prevented both fatal and nonfatal PE. The lower incidence of fatal PE in the PGF group may have contributed to a reduction in the overall mortality rate. Patients who have trauma with high risk for PE should be considered for PGF placement.

CHOP2 cells, a subline of the Chinese hamster ovary (CHO) cell glycosylation mutant Lec2 which expresses polyoma virus large T antigen, was used as the host cell line to select cDNAs conferring resistance to the toxic effects of ricin. Glycoconjugates in CHOP2 cells are deficient in sialic acid and therefore the cells are hypersensitive to ricin, a galactose-binding lectin. CHOP2 cells acquiring cDNA that either corrected the Lec2 mutation or created a Lec2/Lec1 phenotype were expected to show a selective growth advantage in ricin-containing medium. After a single cycle of transfection with a lymphoid cDNA library in pCDM8 followed by ricin selection, the the predominant cDNA recovered from the cells was antisense N-acetyl-glucosaminyltransferase I (GlcNAc-TI) which conferred a Lec2/Lec1 phenotype. cDNA encoding GlcNAc-TI in a sense orientation was also enriched by transfecting a cDNA library into CHOP-1 cells, a mutant deficient in this enzyme, and selecting in medium containing ConA lectin. The results show that cell selection with toxic agents can be used to expression-clone both antisense and sense cDNA sequences from bi-directional cDNA libraries in the pCDM8.

UDP-GlcNAc:Gal beta 1-3GalNAc-R beta 1,6-N-acetylglucosaminyltransferase (GlcNAc to GalNAc) (i.e., core 2 GlcNAc-T) is a developmentally regulated enzyme of the O-linked oligosaccharide biosynthesis pathway. We have developed a coupled-enzyme assay for core 2 GlcNAc-T that is approximately 100 times more sensitive than the standard assay using UDP-[3H]GlcNAc as a sugar donor. Core 2 GlcNAc-T reactions were performed using unlabeled UDP-GlcNAc donor and Gal beta 1-3GalNAc alpha-paranitrophenyl (pNp) as acceptor. The product, Gal beta 1-3(GlcNAc beta 1-6)GalNAc alpha-pNp was then further reacted with purified bovine beta 1-4Gal-T and UDP-[3H]Gal to produce Gal beta 1-3([3H]Gal beta 1-4GlcNAc beta 1-6) GalNAc alpha-pNp, which was separated on an Ultrahydrogel HPLC column. Approximately 10% of the available GlcNAc-terminating acceptor was substituted in the Gal-T reaction, allowing 1 pmol of product to be readily detected. The increased sensitivity of the coupled assay should facilitate studies of core 2 GlcNAc-T activity where material is limiting or specific activity is low.

The evaluation and management of potential arterial injuries in penetrating neck trauma are controversial. Routine surgical exploration or arteriography can be very expensive and time-consuming and can overburden available resources if used in all patients. We reviewed the records of 4035 patients seen in our trauma center during a 20-month period and identified a total of 110 patients (2.7%) with penetrating wounds to zone II of the neck; 50 were from gunshot wounds, 43 from stab wounds, 7 from shotgun injuries, and 10 from lacerations. In 42 (39%) patients there was no arteriogram or surgery based on location of the wounds or lack of any physical findings. None of these patients later had any evidence of an arterial injury. Forty-five patients (40%) had arteriograms based on proximity or a "soft" sign of vascular injury, which included evidence of significant bleeding or a stable hematoma. A total of 15 injuries to major arteries were identified: 3 common carotid, 5 internal carotid, and 7 vertebral. One patient died during initial resuscitation, and four patients went directly to surgery with no preoperative arteriogram for active bleeding and expanding hematoma (n = 1), an expanding hematoma (n = 2), and a large, stable hematoma (n = 1). Only one patient (of the 110) had a significant major arterial injury requiring surgery that was not predicted by physical findings. Nine arterial injuries were treated nonoperatively: six vertebral, two common carotid intimal flaps, and one small distal internal carotid pseudoaneurysm (diagnosed late). Three additional minor external carotid artery injuries were observed with no adverse sequelae.(ABSTRACT TRUNCATED AT 250 WORDS)

Marked changes occur in cardiac function during aortic reconstruction. Numerous factors (primarily compliance changes) limit the currently used pressure-based pulmonary artery catheters' ability to reflect these changes accurately. A new pulmonary artery catheter was used in 26 patients undergoing aortic reconstruction (7 patients with abdominal aortic aneurysms and 19 with occlusive disease) that directly measures right ventricular (RV) volumes and ejection fractions. The extent of coronary artery disease (CAD) was evaluated before surgery, and the patients were divided into three classes. The greatest changes in cardiac function were noted immediately after aortic cross-clamping. Cardiac output significantly decreased in patients with mild or moderate CAD (p less than 0.01 and p less than 0.001) but not in patients with no CAD (p less than 0.5). This correlated well with RV end-diastolic volume (RV-EDV) and stroke volume (RV-SV) measurements in the groups with mild (p less than 0.05) and moderate CAD (p less than 0.01) but not in the group with no CAD (p greater than 0.5). Wedge pressure showed poor correlation, with no significant change noted in any group (p greater than 0.5). Measurements taken later in the procedure documented a significant trend toward baseline in mild and moderate groups. At the opening of the second limb of the graft, the compensated values (CO, RV-EDV, and RV-SV) did not change significantly in the groups with mild and no CAD (p greater than 0.2) but approached significance in the group with moderate CAD (p less than 0.08).(ABSTRACT TRUNCATED AT 250 WORDS)

Current management of penetrating injuries in the proximity of major extremity arteries with no evidence of vascular trauma remains controversial. A total of 318 such injuries in 254 patients were evaluated prospectively to clarify the appropriate timing and role of arteriography, as well as the natural history of these injuries. The arteries at risk were: axillary, 47; brachial, 57; superficial femoral, 176; and popliteal, 38. No deaths occurred, and no morbidity resulted from arteriographic delay of 6 to 24 hours after injury. Of the 48 arteriographic abnormalities detected, 16 involved noncritical branch vessels. There were 32 injuries to major arteries (10.0%), including localized narrowing (n = 13), intimal flap (n = 12), false aneurysm (n = 6), and arteriovenous fistula (n = 1). Shotgun wounds led to a greater arterial injury rate (3/17; 17.6%) than did gunshot wounds (24/247; 9.7%) or stab wounds (5/54; 9.3%). At the surgeon's discretion, three injuries underwent immediate exploration (one negative), whereas the remaining 29 vessel injuries were followed up nonoperatively by repeat arteriography (n = 22) or clinical examination (n = 7), for a mean interval of 2.8 months. Fifteen abnormalities resolved, 10 improved or remained unchanged, and 4 worsened. The four lesions (13.7%) that worsened (two shotgun and two axillary artery injuries) were identified within 3 months of injury and repaired surgically with no morbidity. In conclusion, only 6 operations were required out of 3218 potential injuries (1.8%), suggesting that routine arteriography is not a cost-effective means of evaluating these injuries.(ABSTRACT TRUNCATED AT 250 WORDS)

Secondary vascular procedures to below-knee vessels for lower extremity ischemia present a challenge to the vascular surgeon. Autogenous vein is often unavailable and failure of the previous bypass often limits the choice of distal vessels suitable for revascularization. This dilemma raises the question of amputation vs secondary vascular surgery. To address this question we reviewed the results of our previous aggressive approach to revascularization in a select group of 25 patients (26 limbs) who had secondary procedures with polytetrafluoroethylene grafts to tibial vessels or the infragenicular popliteal artery with single-vessel runoff. Nine of these 26 bypasses (35%) have remained patent for a mean of 17.2 months and no amputations have been done in this group. The other 17 bypasses (65%) have occluded from 1 day to 36 months postoperatively (mean 4.3 months); 15 of these limbs have required major amputation (58%). Ten were performed within the first 3 months postoperatively. Thirteen of the 25 patients died in the follow-up period (mean 27.5 months); five of these patients had viable limbs. Of 12 surviving patients (mean follow-up 19.9 months), six had viable limbs and six have required amputation. These results indicate that patients having secondary vascular surgical procedures with polytetrafluoroethylene grafts to tibial vessels have a high amputation rate and poor overall survival. Within this select group of patients, those who could walk with the aid of a prosthesis should be considered as candidates for primary amputation. This would facilitate rehabilitation and avoid the anguish of recurrent graft failure and multiple procedures.

The determinants of tumor cell susceptibility to NK cell-mediated cytolysis were analyzed in a two stage model. The binding of tumor cells to NK effectors was measured by target-effector conjugation and cold target competition in 51Cr-release assays, whereas triggering was measured by assaying phospholipid methylation in NK cells stimulated by intact targets. Representative targets could be grouped into three phenotypes based on the data. Those such as YAC 1.2 could bind and trigger NK cells whereas the mutagenized variant, YAC 6.28.8, could bind but was unable to trigger NK cells and therefore resisted lysis. The third phenotype was represented by HL-60 which could neither bind nor trigger NK cells and was therefore completely NK resistant. The oligosaccharide nature of the triggering molecules was demonstrated by showing that purified, high mannose containing, asparagine-linked oligosaccharides from tumor cell targets were potent stimulators of NK transmethylation at submicromolar levels. Tunicamycin pretreatment of target cells inhibited their triggering capacity but not their NK binding function. These results suggest a double restriction in NK specificity involving two independent but sequential stages in recognition represented in binding and triggering by asn-linked oligosaccharides on the tumor cell surface.

Previous studies from our laboratory have shown that bioresorbable vascular prostheses woven from lactide-glycolide copolymers and implanted into arteries of several animal models become replaced by cellular tissues; the rate of replacement parallels the kinetics of prosthetic resorption. This study evaluates the efficacy of bicomponent resorbable prostheses as a method of augmenting resistance to dilatation during the resorption period of the more rapidly resorbed component. Bicomponent prostheses (n = 37) were woven from compound yarns containing 74% polyglactin 910 (PG910) and 26% polydioxanone (PDS) and were interposed into adult white New Zealand rabbit infrarenal aortas. Resultant prosthesis-tissue complexes were harvested after 2 weeks to 12 months. Specimens were photographed and sectioned for light, scanning, and transmission electron microscopy. Randomly selected fresh explants at 1 and 3 months and control aortic segments from the same rabbits were simultaneously perfused with culture media (37 degrees C, 100/80 mm Hg, 60 ml/min) and perfusates assayed by means of tritiated radioimmunoassay techniques for the stable prostacyclin metabolite 6-keto-PGF1 alpha before and after the addition of sodium arachidonate (10 micrograms/ml) to the media. Results showed 100% patency, no aneurysms, and stenosis in 1 of 37 prostheses (3%). PG910 was totally resorbed by 2 months and PDS by 6 months. By 1 month inner capsule thickness was 303 +/- 30 microns. In contrast to previous reports this was significantly thicker than that within 100% PDS (230 +/- 40 microns) and significantly less thick than in 100% PG910 (530 +/- 62 microns). Inner capsules in all three groups stabilized at similar thicknesses (417 to 502 microns).(ABSTRACT TRUNCATED AT 250 WORDS)

This study evaluated morphologic and functional characteristics of tissue reactions to compound prostheses of 69% absorbable polyglactin 910 (PG910) and 31% nonabsorbable polypropylene in the rabbit. Forty-two woven PG910/polypropylene prostheses (24 X 4 mm internal diameter) implanted into rabbit infrarenal aortas were harvested after 2 weeks to 12 months. Each explant was photographed and sectioned for light microscopy and transmission and scanning electron microscopy. Randomly selected explants underwent either compliance and bursting strength measurements or assays of production of prostacyclin and thromboxane metabolites by luminal surfaces of both regenerated conduits and normal control aortas in response to administered sodium arachidonate. Results showed 100% patency with no aneurysms and 2% stenoses (1 of 42 prostheses). Confluent endothelial-like cellular luminal surfaces covering oriented smooth muscle-like myofibroblasts comprised the inner capsules whose thicknesses stabilized at 1 to 2 months. Only residual polypropylene remained in the prostheses after 2 months. Compliance studies reflected a 0.65 mm (14%) change over a pressure range of 0 to 160 mm Hg. All regenerated prosthesis-tissue complexes had bursting strengths greater than the proximal perianastomotic native aortas, which burst between 600 and 2000 mm Hg. At 1 month the rate of production of 6-keto-PGF1 alpha per square millimeter of surface area of experimental segments was normal. Production of 6-keto-PGF1 alpha by experimental segments at 3 months had increased fourfold whereas thromboxane B2 (TxB2) production remained unchanged. The 6-keto-PGF1 alpha/TxB2 ratio increased from 1 to 4 months. This study demonstrates clinically efficacious morphologic, mechanical, and biochemical characteristics of PG910/polypropylene-elicited vascular prosthesis-tissue complexes.

This current study analyzed macrophage/biomaterial interactions as modulators of endothelial cell proliferation. Rabbit peritoneal macrophages were harvested and seeded (1 x 10(6) cells/ml) into culture flasks with Dulbecco's modified Eagle medium and 10% platelet-poor, plasma-derived equine serum. Macrophages were identified by morphologic characteristics, nonspecific esterase, and Fc (immunoglobulin G) receptors on the cell membranes. Culture conditions were (1) no prosthetic material, (2) Dacron, or (3) Polyglactin 910 (PG910) (Ethicon, Inc., Somerville, N.J.). Both prosthetic materials were finely shredded into the media. After 5 weeks in culture, PG910 inclusions were seen within macrophage cytoplasm. No intracytoplasmic Dacron was observed. Conditioned media from all three groups were collected weekly from week 5 to week 10, centrifuged, filtered, and added in serial dilutions to cultured quiescent murine capillary lung endothelial cells. Quiescence was achieved by serum deprivation and verified by [3H]thymidine incorporation. Sixteen hours after addition of conditioned media, [3H]thymidine was measured in and expressed as percent increase above quiescent levels. Mitogenic activity in the PG910 group progressively increased from weeks 6 to 10. At week 10, the PG910 group (1:10 dilution) yielded a 620% increase in DNA synthesis. The Dacron group never varied from the control group (no prosthetic). The mean increases in [3H]thymidine incorporations over weeks 7 to 10 were PG910, 540% +/- 65%; Dacron, 323% +/- 65%, and control, 343% +/- 26% (PG910 vs Dacron, p less than or equal to 0.004). These studies suggest macrophage activation by bioresorbable prostheses, yielding growth factor release with subsequent enhanced endothelial cell proliferation.

ECGF, a polypeptide of bovine hypothalamic derivation, is the most potent endothelial cell mitogen known, with mitogenic and chemotactic effects well demonstrated in vitro on human endothelial cells. These effects are synergized by heparin. In vivo re-endothelialization of blood-contacting biomaterials may be enhanced by bonding ECGF and heparin to prosthetic surfaces. Long woven Dacron (24 mm) and woven PDS vascular prostheses were treated first with human plasma fibronectin (10 micrograms/cm2). Porcine sodium heparin (20 micrograms/cm2) was added by means of fibronectin's heparin affinity. Pure 125I-ECGF (95% alpha, 5% beta; 1 ng/cm2) was next fixed by the heparin affinity of ECGF and followed by a second heparin layer (20 micrograms/cm2) to synergize with and stabilize ECGF. 125I-ECGF adherences were determined by scintillation counts. Attachment efficiency averaged 25%. Prostheses were interposed into rabbit aortas and harvested in triplicate from 0 to 30 days to establish in vivo washout curves. After explantation, residual 125I-ECGF was eluted from prostheses, and intact ECGF was identified by SDS gel electrophoresis. Similarly prepared but nonradioiodinated Dacron and PDS prostheses were explanted after 7 days and their ECGF eluted off for in vitro activity documentation. This ECGF retained its mitogenic properties, causing a 1000% to 1200% increase in 3H-thymidine incorporation into newly synthesized DNA in test murine LE-II cells. Fibronectin-heparin-ECGF fixation to blood-contacting biomaterials may enhance spontaneous re-endothelialization and/or hasten the confluence of transplanted endothelial cells.