Comparison of outcomes after endovascular and open repair of abdominal aortic aneurysms in low-risk patients

Background

In randomized trials endovascular aortic aneurysm repair (EVAR) has been shown to have superior perioperative outcomes compared with open aneurysm repair (OAR). However, outcomes in patients at low risk of complications are unclear and many surgeons still prefer OAR in this cohort. The objective was to analyse perioperative and longer-term outcomes of OAR and EVAR in this low-risk group of patients.

Methods

All elective infrarenal EVARs and OARs in the Vascular Study Group of New England database were reviewed from 2003 to 2014. The Medicare scoring system was used to identity patients at low risk of perioperative complications and death. Perioperative and longer-term outcomes were analysed in this cohort. A Kaplan–Meier plot was constructed for evaluation of longer-term survival. Further propensity matching and multivariable analysis were performed to analyse additional differences between the two groups.

Results

Some 1070 patients who underwent EVAR and 476 who had OAR were identified. Mean(s.d.) age was 67·3(5·7) and 65·1(6·3) years respectively (P < 0·001). EVAR was associated with a lower overall perioperative complication rate (4·2 versus 26·5 per cent; P < 0·001). There was no difference in 30-day mortality (0·4 versus 0·6 per cent; P = 0·446). Overall survival at 3 years was similar after EVAR and OAR (92·5 versus 92·1 per cent respectively; P = 0·592). In multivariable analyses there was no difference in freedom from reintervention (odds ratio 1·69, 95 per cent c.i. 0·73 to 3·90; P = 0·220) or survival (hazard ratio 0·85, 0·61 to 1·20; P = 0·353).

Conclusion

In patients predicted to be at low risk of perioperative death following aneurysm repair, EVAR resulted in fewer perioperative complications than OAR. However, perioperative mortality, reinterventions and survival rates in the longer term appeared similar between endovascular and open repair.

Revascularization for chronic limb-threatening ischaemia

Trials hampered by poor definitions

Rapid identification of Enterobacter hormaechei and Enterobacter cloacae genetic cluster III

AIM

Enterobacter cloacae complex bacteria are of both clinical and environmental importance. Phenotypic methods are unable to distinguish between some of the species in this complex, which often renders their identification incomplete. The goal of this study was to develop molecular assays to identify Enterobacter hormaechei and Ent. cloacae genetic cluster III which are relatively frequently encountered in clinical material.

METHODS AND RESULTS

The molecular assays developed in this study are qPCR technology based and served to identify both Ent. hormaechei and Ent. cloacae genetic cluster III. qPCR results were compared to hsp60 sequence analysis. Most clinical isolates were assigned to Ent. hormaechei subsp. steigerwaltii and Ent. cloacae genetic cluster III. The latter was proportionately more frequently isolated from bloodstream infections than from other material (P < 0·05).

CONCLUSION

The qPCR assays detecting Ent. hormaechei and Ent. cloacae genetic cluster III demonstrated high sensitivity and specificity.

SIGNIFICANCE AND IMPACT OF THE STUDY

The presented qPCR assays allow accurate and rapid identification of clinical isolates of the Ent. cloacae complex. The improved identifications obtained can specifically assist analysis of Ent. hormaechei and Ent. cloacae genetic cluster III in nosocomial outbreaks and can promote rapid environmental monitoring. An association was observed between Ent. cloacae cluster III and systemic infection that deserves further attention.

Current state of affairs in the treatment of infrainguinal critical limb ischemia

Atherosclerosis is widespread in Western society and is the leading cause of morbidity and mortality in the United States (US). Epidemiological studies indicate that peripheral artery disease (PAD) has a prevalence of 3-10% in the general population. This rate increases to 15-20% in persons over 70 years of age, and PAD is particularly common in individuals who smoke or have diabetes. Further highlighting the lack of current treatment uniformity, the Society for Vascular Surgery has recently designated the goal of clarifying optimal treatment for CLI as one of its top societal priorities.

The evaluation of a novel technique to treat saphenous vein incompetence: preclinical animal study to examine safety and efficacy of a new vein occlusion device

Objectives

We tested a novel technique to treat great saphenous vein (GSV) incompetence in an animal model.

Methods

V-block (VVT Medical Ltd, Kfar Saba, Israel), an occlusion device composed of a nitinol frame and anchoring hooks, was percutaneously deployed at the saphenofemoral junction in 12 sheep. Four of the 12 sheep were treated with adjunctive liquid sclerotherapy. Animals underwent duplex ultrasound, venography and histopathological evaluation immediately postimplantation at 30, 60 and 90 days.

Results

V-block was successfully deployed in all animals without adverse events. There was no device migration at follow-up. Histopathological analysis demonstrated V-block to be lodged within the GSV and surrounded by fibrous tissue in all samples. Obliteration of the GSV lumen, widespread intimal loss and multifocal medial smooth muscle loss was noted.

Conclusions

In this animal study V-block was deployed without complications, remained in stable position and led to GSV occlusion. This device has promise for future use in humans.

The perspective of the vascular surgery trainee on new ACGME regulations, fatigue, resident training, and patient safety

OBJECTIVE

To assess the opinions of vascular surgery trainees on the new Accreditation Council for Graduate Medical Education (ACGME) guidelines.

METHODS

A questionnaire was developed and electronically distributed to trainee members of the Society for Vascular Surgery.

RESULTS

Of 238 eligible vascular trainees, 38 (16%) participated. Respondents were predominantly 30 to 35 years of age (47%), male (69%), in 2-year fellowship (73%), and at large academic centers (61%). Trainees report occasionally working while fatigued (63%). Fellows were more likely to report for duty while fatigued (P = .012) than integrated vascular residents. Respondents thought further work-hour restrictions would not improve patient care or training (P < .05) and may not lead to more sleep or improved quality of life. Respondents reported that duty hours should vary by specialty (81%) and allow flexibility in the last years of training (P < .05).

CONCLUSIONS

Vascular surgery trainees are concerned about further duty-hour restrictions on patient care, education, and training and fatigue mitigation has to be balanced against the need to adequately train vascular surgeons.

Cryopreserved saphenous vein allografts in infrainguinal arterial reconstruction

Cryopreserved saphenous vein allografts (cryografts) have been used as conduit in infrainguinal revascularization when autogenous vein is inadequate or unavailable. Numerous reports on the subject exist, however most are hampered by small sample size or retrospective design. Despite poor patency rates, limb salvage in patients undergoing cryograft bypass is acceptable. In this article we review the literature of cryograft use in infrainguinal revascularization and define its role in the armamentarium of the modern vascular surgeon.

Chronic antigen-specific immune-system activation may potentially be involved in the loosening of cemented acetabular components

Previous studies have attempted to determine whether aseptic loosening and osteolysis are caused by a T cell-mediated type IV hypersensitivity reaction or a nonspecific foreign body reaction involving phagocytic macrophages. The purpose of this study was to examine the role of the B7-CD28 costimulatory pathway (which is indicative of an activated immune response) in loosening and osteolysis of total joint replacements (TJRs). We harvested periprosthetic tissues from 24 loose, cemented, all polyethylene, acetabular components in patients undergoing revision total hip replacement surgery for aseptic loosening. Prostheses were classified radiographically as to whether ballooning, scalloping osteolysis was present or not. Monoclonal antibodies were used to identify macrophages, antigen presenting cells (APCs) expressing B7-1 or B7-2, total T lymphocytes, and T cells expressing CD28 or CTLA-4. The large numbers of positive cells, including macrophages, T cells, and APCs in both groups are substantially higher than previously reported. Macrophages constituted the predominant cell type, the majority of which were APCs. B7-1 was expressed by 18.3% of all cells, and B7-2 was expressed by 61.0% of cells. Despite the fact that there were no statistically significant differences in expression of proteins in the B7-CD28 pathway between the osteolytic and nonosteolytic groups, the magnitude of positive staining suggests that the process of aseptic loosening (not osteolysis) may involve proteins of the B7-CD28 pathway, particularly B7-2. One possible antigenic stimulus is protein-coated particulate wear debris from prosthetic materials.

DIMA enlargement mammography in microcalcifications: a prospective study with ROC analysis

The purpose of this study was to investigate whether the four-fold magnification mammography (direct magnification, DIMA) technique would perform better than conventional 1.5-fold magnification mammography in the differentiation of breast microcalcifications into benign and malignant. Fifty patients with non-palpable microcalcifications detected by mammography were examined immediately prior to surgical biopsy using both a conventional (1.5-fold) and the DIMA (fourfold) magnification mammography techniques. The microcalcifications were classified by five experienced radiologists using morphological criteria. A receiver operating characteristics curve (ROC) analysis of the sensitivity and specificity of both techniques in assessing malignancy was then carried out. The DIMA mammography technique was slightly but non-significantly superior to the conventional method in detecting malignancy (p > 0.05). Coarse granular and pleomorphic calcifications were detected more frequently with the DIMA technique. Coarse calcifications were significantly more frequently associated with histologically benign findings, whereas fine granular calcifications were significantly more likely to be malignant lesions. Assessment of malignancy associated with microcalcifications using morphological criteria is not significantly improved by mammography techniques with higher magnification.

Recovery of Cardiac Function after Standard Hypothermic Storage Versus Preservation with Peg-Hemoglobin

Preservation of the heart for transplantation after infusion of cardioplegia and extirpation of a cardiac allograft results in an ischemic insult to the myocardium. This ischemic insult may lead to a loss of function in the transplanted heart. Hypothermic perfusion preservation with an oxygen hemoglobin carrying solution may avert ischemic injury and lead to improved recovery of cardiac function. The purpose of this study was to compare cardiac function after 8 hours of continuous hypothermic perfusion with a unique polyethylene-glycol-hemoglobin (PEG-Hb) solution to hearts preserved by 4 hours of hypothermic ischemic storage. Freshly extirpated hearts served as functional controls. The hearts of 26 anesthetized and intubated New Zealand white rabbits were harvested after cold cardioplegic arrest. Group I (n = 12) hearts were perfused with a PEG-Hb solution at 20 degrees C and 30 mm Hg for 8 hours. PO2 was maintained > or = 500 mm Hg. Group II (n = 7) hearts were preserved by cold ischemic storage for 4 hours at 4 degrees C. Group III (n = 7) were tested immediately after harvest. Left ventricular (LV) function was measured in the nonworking state at 15 minutes, 1 hour, and 2 hours after transfer to a standard crystalloid Langendorff circuit. Measurement of LV developed pressure, peak + dP/dt and -dP/dt revealed a superior trend between Group I and Group II hearts in comparison with freshly extirpated hearts. Heart rate was similar among all groups throughout testing (p = ns). Coronary blood flow was not significantly different between groups. Continuous perfusion preservation of rabbit hearts for 8 hours with PEG-Hb solution at 30 mm Hg and 20 degrees C yielded LV function that was similar to 4 hours of ischemic hypothermic storage. Furthermore, return of cardiac function after 8 hours of perfusion preservation using this PEG-Hb solution may be superior to that obtained in freshly extirpated hearts. These data suggest that some recovery of myocardial function may occur during perfusion preservation with this PEG-Hb solution after the ischemic insult of cardioplegic arrest. Continuous perfusion preservation using this PEG-Hb solution deserves further investigation in large animal transplant models.

Immunoglobulin heavy chain variable region gene replacement As a mechanism for receptor revision in rheumatoid arthritis synovial tissue B lymphocytes

Mature B cells can alter their antibody repertoires by several mechanisms, including immunoglobulin heavy chain variable region (V(H)) replacement. This process changes the antigen combining site by replacing a portion of the original V(H)/diversity/heavy chain joining region (V(H)DJ(H)) rearrangement with a corresponding portion of a new V(H) segment. This exchange can involve cryptic heptamer-like sequences embedded in the coding regions of V(H) genes. While studying the B lymphocytes that expand in the synovial tissues of patients with rheumatoid arthritis (RA), clones with V(H)DJ(H) variants that were apparently generated by V(H) replacement were identified with surprising frequency (approximately 8%). Examples of multiple independent V(H) replacement events occurring in distinct progeny clones were also identified. These secondary V(H) rearrangements were documented at both the cDNA and genomic DNA levels and involved several heptamer-like sequences at four distinct locations within V(H) (three sites in framework region 3 and one in complementarity determining region 2). The identification of blunt-ended double-stranded DNA breaks at the embedded heptamers and the demonstration of recombinase activating gene (RAG) expression suggested that these rearrangements could occur in the synovial tissues, presumably in pseudo-germinal centers, and that they could be mediated by RAG in a recognition signal sequence-specific manner. The presence of V(H) mutations in the clones that had undergone replacement indicated that these B cells were immunocompetent and could receive and respond to diversification signals. A relationship between these secondary V(H) gene rearrangements and the autoimmunity characteristic of RA should be considered.

Matched-pair analysis of conventional versus endoluminal AAA treatment outcomes during the initial phase of an aortic endografting program

PURPOSE

To investigate whether endovascular stent-grafts implanted during the early phase of an aortic endografting program have advantages over conventional surgical procedures for treatment of infrarenal aortic aneurysm (AAA).

METHODS

In the first months of an endografting program, 37 patients (36 men; mean age 67.9 +/- 7.1 years, range 55 to 86) underwent AAA repair with endovascular implantation of a Vanguard (n = 17) or Talent (n = 20) bifurcated stent-graft. Data collected during the perioperative period and in follow-up were compared retrospectively to a matched group of 37 elective surgical patients.

RESULTS

All endograft implantations were completed. Two type I and 6 type II endoleaks (21.6%) were seen postoperatively. Five type II sealed without intervention; 1 type I endoleak was corrected with an additional stent, but 1 type I and 1 type II endoleaks persisted despite attempts with coil embolization. Two (5.4%) endograft patients died during the perioperative period; however, this was not significantly different (p = 0.15) from the control group. In the mean follow-up of 12 +/- 6 months for both groups, 1 (2.7%) late conversion was necessary at 2 years for aneurysm expansion in an endograft patient with an unsealed type I endoleak.

CONCLUSIONS

In our learning curve experience with aortic endografting, postoperative morbidity and mortality were higher in endograft patients compared to conventionally treated controls. Only in the endograft group was reoperation required during follow-up. Careful monitoring with periodic imaging studies is mandatory after endoluminal AAA treatment.

[Radiographic image magnification as quality control of microcalcification imaging within the scope of histopathological control of breast biopsy tissue]

PURPOSE

Evaluation of specimen radiography as a quality control for the detection of microcalcifications by the pathologist during histopathological examination of breast biopsies.

MATERIALS AND METHODS

29 breast biopsy specimen with microcalcifications were radiographed using the magnification (x4) mammography System DIMA Plus MI I before and after the histopathological examination. Tissue with detected microcalcifications after the histopathological examination was reexamined histologically.

RESULTS

In 55% (16/29) of all specimen we could identify missed microcalcifications. In 5 specimens the microcalcifications were missed completely. The radiologically detected areas of residual microcalcifications were reexamined histologically and in one case invasive parts of a carcinoma were detected, which primarily had been diagnosed as an in-situ carcinoma. In 6 cases the radiographs of the intraoperative specimen radiography were sent to the pathologist together with the biopsy. In these cases the rate of complete detection of the microcalcifications increased from 39% to 66%.

CONCLUSION

Specimen radiography should be performed not only intraoperatively but also as part of the histopathological examination.

[Digital subtraction angiography with carbon dioxide--basic principles, technique and clinical application]

Carbon dioxide digital subtraction angiography Carbon dioxide (CO2) digital subtraction angiography offers the possibility for diagnostic and interventional angiographic procedures in high risk patients for ionidated contrast material. As a gaseous contrast agent its physicochemical properties have special requirements concerning the radiologists knowledge, the X-ray equipment, the injector and the catheters. This article reviews the current literature concerning the history, physics and physiology, indications and contraindications, clinical use, adverse effects and possible complications of carbon dioxide digital subtraction angiography.

[Detection of microcalcifications in breast specimens by 4-fold DIMA direct magnification radiography compared to 1.5-fold conventional magnification radiography]

AIMS OF STUDY

The purpose of this study was to investigate the efficacy of 4-fold magnification breast specimen radiography (direct magnification, DIMA) compared to conventional 1.5-fold magnification radiography in evaluating the presence or absence of carcinoma at the surgical margins by detection of microcalcification.

METHODS

Fifty breast specimens with non-palpable microcalcifications were examined during surgical biopsy using both DIMA (4-fold) and conventional (1.5-fold) magnification specimen radiography. The number of detected microcalcifications of the whole specimen, of an area of 5 mm distance to the margins and of the area of the suspicious cluster of microcalcifications was counted and the results compared with the histological examination as a gold standard.

RESULTS

In 50 specimen 2821 (1305 within 3 mm distance to the margins) microcalcifications were detected with the DIMA mammography technique compared to 1608 (446) microcalcifications with the conventional technique. This increased detection rate by DIMA-magnification radiography was accompanied by a decreased specificity in comparison to the conventional magnification radiography (33.3% DIMA versus 83.3% conventional) regarding the evaluation of presence or absence of carcinoma at the surgical margins. Differentiating the microcalcifications into calcifications belonging to the suspicious cluster and those that are located outside the cluster led to an increase in specificity (83.3% DIMA versus 100% conventional).

CONCLUSIONS

The efficacy of breast specimen radiography in evaluating the presence or absence of carcinoma at the surgical margins by detection of microcalcification is not improved by 4-fold magnification radiography (direct magnification, DIMA) compared to conventional 1.5-fold magnification radiography due to an increase in false-positive results. Analysis of the attachment of the microcalcifications to the cluster can improve the specificity.

A specific inhibitor of apoptosis decreases tissue injury after intestinal ischemia-reperfusion in mice

PURPOSE

Apoptosis is a stereotypical pathway of cell death that is orchestrated by a family of cysteine endoproteases called caspases. This study examined the effect of apoptosis inhibition with a specific caspase inhibitor on murine intestinal viability after ischemia-reperfusion (IR).

METHODS

C57Bl6 X SV129 mice underwent segmental small bowel ischemia by vascular isolation of 10 cm of terminal ileum. In separate experiments, the ischemic time was varied from 30 to 130 minutes with a reperfusion interval of 6 hours. The degree of small bowel injury was quantified from 1 to 5 (increasing severity) by standardized, blinded histologic grading. The degree of apoptosis was assessed with a specific assay (terminal deoxyamcleotydil transferase-mediated deoxyuridine triphosphate nick end labeling [TUNEL]) and quantified by calculating the apoptotic index (apoptotic cells/10 high-power fields). To evaluate for activation of interleukin-1beta converting enzyme we measured tissue mature interleukin-1beta levels using a specific enzyme-linked immunosorbent assay. To evaluate the effect of apoptosis inhibition on intestinal viability after IR, mice received 3.0 mg of the caspase inhibitor ZVAD (N-benzyloxycarbonyl Val-Ala-Asp-Ome-fluoromethylketone) subcutaneously before and after IR in five divided doses (n = 11), the same dose of ZFA (N-benzyloxycarbonyl Phe-Ala fluoromethylketone), a structurally similar molecule with no anticaspase activity (n = 9), or sham operation (n = 6).

RESULTS

A linear relationship existed between ischemic interval and histologic grade (r = 0.69, P <.006). Increasing the ischemic interval from 0 to 50 minutes was associated with a fivefold increase in apoptotic index (P =.05). Ischemic bowel was measured to have an average of 57.3 +/- 7.8 pg/mL whereas normal bowel had an average of 1.8 +/- 0.5 pg/mL of mature interleukin-1beta present. Mice tolerated multiple injections of ZVAD and ZFA without signs of toxicity. Animals treated with ZVAD (apoptosis inhibitor) had little injury after 50 minutes of ischemia and 6 hours of reperfusion (injury grade 1.8) compared with sham controls (injury grade 1.2, P =.7) and had significantly less injury than mice treated with ZFA (placebo) (injury grade 3.0, P <.006).

CONCLUSIONS

Increasing ischemic interval in a segmental small bowel murine IR model is associated with increased histologic injury and augmented apoptosis as evidenced by increased TUNEL staining and interleukin-1beta converting enzyme activation. Inhibition of apoptosis with a specific caspase inhibitor significantly diminishes the degree of small bowel injury.

A caspase inhibitor decreases oxidized low-density lipoprotein-induced apoptosis in bovine endothelial cells

BACKGROUND

Apoptosis is a pathway of cell death orchestrated by a family of proteases called caspases. Oxidized low density lipoprotein (oxLDL) is a putative cause of atherogenesis. We examined the effect of oxLDL on endothelial cell (EC) apoptosis and the ability of a caspase antagonist to inhibit oxLDL-induced EC injury.

METHODS

Bovine ECs were plated at a concentration of 5.0 x 10(5) cells/ml and exposed to LDL oxidized by ultraviolet radiation at a concentration of 100 microgram oxLDL/ml for 20 h. Some ECs were pretreated with an irreversible caspase inhibitor (ZVAD). Samples were analyzed histologically. Apoptosis was measured using the Annexin V assay (flow cytometry) which detects phosphatidylserine on plasma membranes and confirmed by TUNEL assay (flow cytometry). Statistical assessments were performed using ANOVA.

RESULTS

ECs treated with LDL were morphologically similar to untreated cells. Cells treated with oxLDL demonstrated cytoplasmic shrinkage, plasma membrane blebbing, chromatin condensation, and loss of adhesion. These effects were diminished after pretreatment with the caspase inhibitor ZVAD. The Annexin V assay showed: (a) cells exposed to LDL had a 12 +/- 1% apoptosis rate, (b) exposure to oxLDL induced apoptosis in 30 +/- 0.3% of the cells, and (c) pretreatment with the caspase inhibitor ZVAD decreased the oxLDL-induced apoptosis to 16 +/- 1% (P < 0.05). This decrease in apoptosis was also reflected by an increase in the percentage of alive cells from 34 +/- 7% after oxLDL exposure to 55 +/- 6% after apoptosis inhibition with ZVAD. TUNEL assay demonstrated a 2.5-fold reduction in mean fluorescence intensity between cells treated with oxLDL alone and those treated with ZVAD, suggesting a significant decrease in apoptosis in the latter group.

CONCLUSIONS

We conclude that treatment of bovine ECs with oxLDL induces apoptosis which can be significantly reduced by a specific caspase inhibitor.

Access-related venous stenoses and occlusions: treatment with percutaneous transluminal angioplasty and Dacron-covered stents

PURPOSE

To determine the effectiveness of using Dacron-covered stents to treat access-related venous stenoses and occlusions.

METHODS

Twenty-two Dacron-covered stents were placed in 20 patients: in the basilic or axillary vein (n = 2), cephalic vein (n = 3), subclavian vein (n = 5), and at the venous anastomosis of the polytetrafluoroethylene (PTFE) implant graft (n = 10).

RESULTS

Initial technical success was 100%. The cumulative primary and secondary patency rates were 57% and 83% at 6 months, 29% and 64% at 12 months, and 29% and 53% at 18 months. A statistically significant difference in the stent patency was revealed by comparing the patients with stents in the subclavian vein and patients with upper arm stents. The secondary patency rates of the upper arm stents were 73% after 6, 12, and 18 months.

CONCLUSIONS

Percutaneous placement of Dacron-covered stents is a safe and effective procedure for salvage of a dialysis fistula. First results are promising, with a tendency to prolongation of the time interval between reinterventions.

[The demonstration of microcalcification in breast core biopsies: DIMA specimen radiography (7x) compared to the histopathological findings]

PURPOSE

Comparing the sensitivity in detecting microcalcifications in stereotactically guided core biopsy specimen of the breast of direct magnification (DIMA) specimen radiography (x7) with the histological examination.

MATERIALS AND METHODS

In 52 patients 509 stereotactically obtained core biopsy (14-gauge) specimens of the breast were radiographed by direct magnification (DIMA) specimen radiography (x7) and examined histologically.

RESULTS

In 188 specimen microcalcifications were detected by magnification radiography compared to 98 by histological examination. Only 3% of the specimen microcalcifications were seen exclusively in the histological examination. In core biopsies with malignancy the relative proportion of biopsies with radiologically detected microcalcifications was increased (59% versus 32%).

CONCLUSION

Concerning the detection of microcalcifications in core biopsy specimen of the breast, the direct magnification (DIMA) radiography (x7) was superior compared to the histological examination. Due to the high relative proportion of biopsies with radiologically detected microcalcification and malignancy, we recommend a comprehensive histological examination of these specimen. Confirmation of microcalcifications in core biopsies should be achieved by magnification radiography to prove that the suspicious area in the breast was truly sampled. Specimen radiography simultaneously with the biopsy procedure can reduce the number of punctures in the process of documenting the presence of calcifications early in the biopsy procedure.

Dynamics of Xanthophyll-Cycle Activity in Different Antenna Subcomplexes in the Photosynthetic Membranes of Higher Plants (The Relationship between Zeaxanthin Conversion and Nonphotochemical Fluorescence Quenching)

The generation of nonphotochemical quenching of chlorophyll fluorescence (qN) in the antenna of photosystem II (PSII) is accompanied by the de-epoxidation of violaxanthin to antheraxanthin and zeaxanthin. The function of zeaxanthin in two mechanisms of qN, energy-dependent quenching (qE) and photoinhibitory quenching (qI), was investigated by measuring the de-epoxidation state in the antenna subcomplexes of PSII during the generation and relaxation of qN under varying conditions. Three different antenna subcomplexes were separated by isoelectric focusing: Lhcb1/2/3, Lhcb5/6, and the Lhcb4/PSII core. Under all conditions, the highest de-epoxidation state was detected in Lhcb1/2/3 and Lhcb5/6. The kinetics of de-epoxidation in these complexes were found to be similar to the formation of qE. The Lhcb4/PSII core showed the most pronounced differences in the de-epoxidation state when illumination with low and high light intensities was compared, correlating roughly with the differences in qI. Furthermore, the epoxidation kinetics in the Lhcb4/PSII core showed the most pronounced differences of all subcomplexes when comparing the epoxidation after either moderate or very strong photoinhibitory preillumination. Our data support the suggestion that zeaxanthin formation/epoxidation in Lhcb1-3 and Lhcb5/6 may be related to qE, and in Lhcb4 (and/or PSII core) to qI.

Is preoperative cardiac evaluation for abdominal aortic aneurysm repair necessary?

PURPOSE

It is reported that 25% to 50% of patients with abdominal aortic aneurysms (AAA) have severe coronary artery disease (CAD) and should undergo an aggressive cardiac workup before AAA repair. In contrast, it has been our policy that patients referred for AAA repairs undergo no cardiac testing before surgery.

METHODS

This report reviews the last 113 consecutive patients who underwent elective AAA repair by the senior author using this policy. Seventy-four patients (group A) had only an electrocardiogram before surgery. The remaining 39 patients (group B) were referred having already had additional testing that included a thallium stress test (n = 20), echocardiogram (n = 18), multiple gated acquisition (MUGA) scan (n = 3), cardiac catheterization (n = 8), or some combination of these.

RESULTS

There was no statistical difference between group A and group B with regard to age, sex, tobacco use or history of coronary artery disease, diabetes mellitus, stroke (CVA), hypertension, peripheral vascular disease, or chronic obstructive pulmonary disease. Group B more commonly had a history of myocardial infarction (41% vs 19%, p < 0.03) and congestive heart failure (23% vs 7%, p < 0.03). During surgery there was no significant differences in blood loss, transfusion requirements, or operative times. There were no myocardial infarctions in group A and two (5.1%) in group B, which was not significantly different. Other complications, such as CVA, renal failure, pulmonary failure, pneumonia, wound infection, and hemorrhage, were not significantly different between the two groups. Postoperative hospital stay was not significantly different. There were three deaths in the entire series (2.7%), and only one in group B was cardiac-related in a patient with known end-stage cardiac disease and a symptomatic 8 cm AAA.

CONCLUSIONS

These data indicate that most patients with AAA can safely undergo repair with no cardiac workup and that cardiac workup before AAA repair contributes little information that impacts on treatment or final clinical outcome. We conclude that cardiac testing in preparation for AAA repair is not usually necessary and that intraoperative hemodynamic management may be the most important variable in determining outcome.

Hypothenar hammer syndrome successfully managed with intravenous prostaglandin E1 and heparin and with correction of the thrombogenic risk profile. A case report

A fifty-one-year-old man presented with a history, symptoms, and clinical findings typical of a hypothenar hammer syndrome in his dominant hand. A thrombotic obstruction in the distal section of the ulnar artery with multiple downstream occlusions of proper digital arteries were documented angiographically. Coexistence of additional cardiovascular risk factors (smoking-induced polycythemia, obesity, hypercholesterolemia, and hypertension) was identified. Conservative management with intravenous heparin and prostaglandin E1 together with measures directed at controlling the additional risk factors (repeated venesection, immediate smoking cessation, and low-lipid diet) resulted in a striking clinical and angiographic improvement of the digital perfusion, without resort to interventional measures or thrombolysis.

Cytokine secretion by genetically modified nonimmunogenic murine fibrosarcoma. Tumor inhibition by IL-2 but not tumor necrosis factor

Recent investigations have demonstrated that the in vivo growth of weakly immunogenic murine tumors can be inhibited by genetic manipulations that enable them to secrete a variety of cytokines. Inasmuch as most human tumors fail to elicit a detectable host immune response we questioned whether the growth of a nonimmunogenic murine tumor could be inhibited by the secretion of cytokines. We have thus inserted the cDNA encoding for human IL-2 or TNF into the nonimmunogenic murine fibrosarcoma MCA 102. Tumor cells secreting IL-2 failed to grow in vivo despite normal in vitro growth. This growth inhibition required an intact immune system as tumors grew progressively in mice sublethally irradiated before tumor injection. Tumor inhibition was abrogated by the in vivo depletion, by specific mAb before tumor injection, of either CD8+ T cells or NK cells, but not CD4+ T cells. IL-2 secretion by tumor afforded a significant survival benefit to the animal, and IL-2-secreting tumor limited the growth of admixed nonsecreting parental tumor. Histologic evidence and FACS analyses revealed a dense lymphocytic infiltration of IL-2-secreting tumors composed of both CD4+ and CD8+ T cells. In contrast, secretion of TNF failed to inhibit the growth of MCA 102, and similar lymphocyte subset depletions, or administration of specific anti-TNF mAb had no effect on the growth of TNF secreting MCA 102. In summary, these investigations demonstrated that the host response to this nonimmunogenic tumor can be markedly enhanced by the genetic manipulation of the tumor cells to secrete IL-2, but not TNF. This strategy has potential application for the development of immunotherapies for nonimmunogenic tumors.

Cytokine secretion by genetically modified nonimmunogenic murine fibrosarcoma. Tumor inhibition by IL-2 but not tumor necrosis factor

Recent investigations have demonstrated that the in vivo growth of weakly immunogenic murine tumors can be inhibited by genetic manipulations that enable them to secrete a variety of cytokines. Inasmuch as most human tumors fail to elicit a detectable host immune response we questioned whether the growth of a nonimmunogenic murine tumor could be inhibited by the secretion of cytokines. We have thus inserted the cDNA encoding for human IL-2 or TNF into the nonimmunogenic murine fibrosarcoma MCA 102. Tumor cells secreting IL-2 failed to grow in vivo despite normal in vitro growth. This growth inhibition required an intact immune system as tumors grew progressively in mice sublethally irradiated before tumor injection. Tumor inhibition was abrogated by the in vivo depletion, by specific mAb before tumor injection, of either CD8+ T cells or NK cells, but not CD4+ T cells. IL-2 secretion by tumor afforded a significant survival benefit to the animal, and IL-2-secreting tumor limited the growth of admixed nonsecreting parental tumor. Histologic evidence and FACS analyses revealed a dense lymphocytic infiltration of IL-2-secreting tumors composed of both CD4+ and CD8+ T cells. In contrast, secretion of TNF failed to inhibit the growth of MCA 102, and similar lymphocyte subset depletions, or administration of specific anti-TNF mAb had no effect on the growth of TNF secreting MCA 102. In summary, these investigations demonstrated that the host response to this nonimmunogenic tumor can be markedly enhanced by the genetic manipulation of the tumor cells to secrete IL-2, but not TNF. This strategy has potential application for the development of immunotherapies for nonimmunogenic tumors.

In vivo activity of tumor necrosis factor (TNF) mutants. Secretory but not membrane-bound TNF mediates the regression of retrovirally transduced murine tumor

We have previously demonstrated that murine tumor cells transduced with a retrovirus containing the cDNA encoding wild-type human TNF regress in vivo when injected into immunocompetent mice; this regression is T cell mediated. To determine whether membrane-associated or secreted TNF was responsible for tumor regression, we transduced a cloned murine fibrosarcoma 205 F4 with retroviruses encoding modified human TNF genes. The cloned tumor lines of one retroviral transduction expressed only membrane bound 26-kDa TNF. This TNF could not be cleaved or secreted, but was present on the cell surface. A second retrovirus caused the expression of only secretory 17-kDa TNF, as the transmembrane domain of the cDNA was deleted. The TNF produced by tumor cells transduced with either retroviral vector was functional in vitro as direct lysis of the TNF-sensitive target L929 by transduced tumor cells was demonstrated. The TNF present on 26-kDa expressing tumors was membrane bound as supernatants from cultured 17-kDa TNF expressing tumor cells but not 26-kDa TNF expressing tumors mediated the lysis of L929 cells. Both tumors were injected s.c. into syngeneic mice and tumor growth was measured serially. In repeated experiments, 26-kDa TNF expressing tumors grew progressively in all mice. In contrast, 17-kDa TNF expressing tumors grew for 10 days and then regressed with all animals free of tumor at 28 days. Tumor regression was abrogated by in vivo injection of an anti-TNF antibody. Similar results were obtained in a second tumor model, 203 E4. Thus regression of TNF transduced tumors in vivo requires secretion of TNF, as membrane-bound TNF is insufficient to elicit the host response.

In vivo activity of tumor necrosis factor (TNF) mutants. Secretory but not membrane-bound TNF mediates the regression of retrovirally transduced murine tumor

We have previously demonstrated that murine tumor cells transduced with a retrovirus containing the cDNA encoding wild-type human TNF regress in vivo when injected into immunocompetent mice; this regression is T cell mediated. To determine whether membrane-associated or secreted TNF was responsible for tumor regression, we transduced a cloned murine fibrosarcoma 205 F4 with retroviruses encoding modified human TNF genes. The cloned tumor lines of one retroviral transduction expressed only membrane bound 26-kDa TNF. This TNF could not be cleaved or secreted, but was present on the cell surface. A second retrovirus caused the expression of only secretory 17-kDa TNF, as the transmembrane domain of the cDNA was deleted. The TNF produced by tumor cells transduced with either retroviral vector was functional in vitro as direct lysis of the TNF-sensitive target L929 by transduced tumor cells was demonstrated. The TNF present on 26-kDa expressing tumors was membrane bound as supernatants from cultured 17-kDa TNF expressing tumor cells but not 26-kDa TNF expressing tumors mediated the lysis of L929 cells. Both tumors were injected s.c. into syngeneic mice and tumor growth was measured serially. In repeated experiments, 26-kDa TNF expressing tumors grew progressively in all mice. In contrast, 17-kDa TNF expressing tumors grew for 10 days and then regressed with all animals free of tumor at 28 days. Tumor regression was abrogated by in vivo injection of an anti-TNF antibody. Similar results were obtained in a second tumor model, 203 E4. Thus regression of TNF transduced tumors in vivo requires secretion of TNF, as membrane-bound TNF is insufficient to elicit the host response.

Membrane expression of platelet calpain

Platelet calpain has many platelet substrates, including external membrane proteins. We thus investigated whether platelet calpain II was associated with platelet membranes in unstimulated and thrombin-activated platelets. A monospecific, goat polyclonal antibody was reared to purified platelet calpain II. Sixteen whole platelet lysates were found to contain 4.5 +/- 0.7 micrograms calpain antigen II per 10(8) platelets (mean +/- SEM) as determined by a competitive enzyme-linked immunosorbent assay. Using the dipeptide fluorogenic substrate, Suc-Leu-Tyr-MCA, 17 human platelet lysates contained 3.6 +/- 0.4 micrograms calpain activity per 10(8) platelets. Platelet calpain II was associated with the Triton X-100 insoluble platelet cytoskeletons from both unstimulated and thrombin-activated platelets. When compared with the total cell content of platelet calpain II, calpain antigen (10% to 13%) and calpain activity (24% to 28%) was associated with platelet cytoskeletons in unstimulated and thrombin-activated platelets, respectively. On immunoblot, the heavy chain (80 Kd) of calpain II was detected in platelet cytoskeletons. Subcellular fractionation studies on both unstimulated and thrombin-activated platelets, revealed that half of the total platelet calpain II antigen was associated with cytosol, and the other half was associated with the membrane fraction. Platelet calpain II was not seen on the surface of unstimulated, paraformaldehyde fixed platelets by immunofluorescence. However, on thrombin-activated platelets, rim immunofluorescence was seen, indicating that activated platelets externalize their calpain. This observation was confirmed by the finding that about 2,000 molecules per platelet of an 125I-anti-calpain II Fab' specifically bound to thrombin-activated but not unstimulated platelets. Both dibucaine (1 mmol/L) and platelet activating factor (1.86 mumol/L) in the absence of external Ca++, but not collagen (5 micrograms/mL) or ionophore A23187 (2.5 mumol/L) in the absence of external Ca++, were also able to externalize platelet calpain II antigen, as indicated by a similar level of specific 125I-anti-calpain II Fab'-platelet binding. These combined studies indicate that platelet calpain II is a major protein, comprising 2% of total platelet protein, a substantial portion of which is membrane-associated. When platelets are activated by thrombin and platelet activating factor, calpain II antigen also becomes present on the external platelet surface.

Immunoblotting of plasma in a pregnant patient with hereditary angioedema

Hereditary angioedema (HAE), an autosomal disorder caused by a deficiency of C1 inhibitor, is characterized by attacks of localized swelling, laryngeal edema, or abdominal pain. Plasma samples from one pregnant patient were studied serially by functional and quantitative immunochemical assays as well as immunoblot assays for high molecular weight kininogen (HMWK) and/or prekallikrein/kallikrein (PK/K). An immunoblot of this patient's HMWK from plasma obtained before she became pregnant and when she was well revealed that it was mostly an intact protein of 120 kd, similar to immunoblot results of normal plasma HMWK. In plasma samples taken throughout her pregnancy, before, during, and after clinical attacks of angioedema, all of her plasma HMWK was shown to be cleaved into the 45 kd light chain form. After delivery of the infant the 120 kd form of intact plasma HMWK returned to her plasma. In comparison, immunoblot studies on 21 normal and abnormal pregnancies revealed that plasma HMWK was an intact protein at 120 kd. That this patient's plasma during her pregnancy was contact activated was determined by additional immunoblot studies for PK/K. Immunoblot assay for plasma PK/K revealed kallikrein-alpha 2-macroglobulin complexes and a 50 kd PK/K form seen only in activated plasma samples. The findings of kallikrein-alpha 2-macroglobulin complexes and a 50 kd PK/K form disappeared after delivery. These combined studies on this patient show that the structures of HMWK and prekallikrein as indicated by immunoblot assays were altered during pregnancy. Immunoblot assays for detection of changes in the structure of HMWK and prekallikrein may be objective laboratory studies for documenting clinical attacks of hereditary angioedema, their onset, and their resolution.

Synthesis and expression of C1 inhibitor by human umbilical vein endothelial cells

The biologic activity of C1 esterase, activated forms of factor XII and kallikrein at sites of vascular inflammation may be regulated by C1 inhibitor (C1 INH) elaborated by endothelial cells. Therefore, we investigated whether human umbilical vein endothelial cells (HUVEC) in culture produce C1 INH. Passaged HUVEC contain 1.6 +/- 0.8 micrograms of C1 INH/10(8) cells (mean +/- S.D.; n = 7) which was immunochemically similar to plasma C1 INH measured by a competitive enzyme-linked immunosorbent assay. Methylamine-treated lysates of HUVEC contained a functional inhibitor of purified kallikrein (2.7 +/- 0.8 micrograms activity/10(8) cells, mean +/- S.D.; n = 4). The HUVEC-derived kallikrein inhibitory activity was mostly C1 INH because it was reversed by chemically treating the lysate with chloroform and was neutralized by anti-C1 INH antibody. A lysate of HUVEC derived from an umbilical cord from a patient with Type I hereditary angioedema contained less than 30% of the normal levels of C1 INH antigen and activity. Immunohistochemical staining of HUVEC demonstrated a diffuse pattern of staining for C1 INH. HUVEC C1 INH was also expressed on the endothelial cell surface as detected by binding of anti-C1 INH antibody to intact monolayers and was elaborated progressively into the overlying media over the first 24 h in culture. HUVEC incubated with [35S] methionine secreted a metabolically labeled protein having a molecular mass of 92 kDa immunoisolated using polyclonal or monoclonal antibodies to human C1 INH. A mRNA transcript encoding for C1 INH was detected by slot blot hybridization. Incubation of HUVEC with gamma-interferon stimulated the expression of the 2.1 kilobase mRNA for C1 INH and increased the level of C1 INH produced by these cells. Production and expression of C1 INH by endothelial cells may help modulate the complement system and the contact system of plasma proteolysis on the vascular surface in vivo.

Structural changes of plasma high molecular weight kininogen after in vitro activation and in sepsis

High molecular weight kininogen (HMWK) is a multifunctional protein that is a parent molecule for bradykinin, a cofactor for coagulation, and an inhibitor of cysteine proteases. On immunoblot, nonreduced plasma HMWK is usually two bands at 140 kd and 120 kd; reduced plasma HMWK is a single band at 120 kd. In both concentration-dependent and time-dependent experiments kaolin-activated normal plasma HMWK becomes cleaved in an ordered sequence. When nonreduced, HMWK on immunoblot in kaolin-activated plasma changes in size from a 140 kd band through a 120 kd intermediate to result in a stable 100 kd protein. When reduced, HMWK on immunoblot in kaolin-activated plasma changes from a single 120 kd band through a 56 kd intermediate to result in a stable 46 kd protein. A similar sequence of cleavage of plasma HMWK occurs when the soluble activator dextran sulfate is used to stimulate the system. Cleavage of plasma HMWK after kaolin activation occurs similarly in factor XI-deficient plasma as in normal plasma but is decreased in prekallikrein-deficient plasma. Prolonged kaolin activation of prekallikrein-deficient plasma results in HMWK cleavage to bands below 120 kd. No band of plasma HMWK below 120 kd appears in prolonged kaolin-activated factor XII-deficient plasma. In some patients with sepsis, detectable cleavage of plasma HMWK to bands below 120 kd may not be seen, even though the patient has other evidence for contact system activation. In conclusion, these studies indicate that certain cleaved patterns of plasma HMWK on immunoblot indicate prior activation of the contact system. However, the absence of these cleaved forms of plasma HMWK in a single plasma does not exclude the occurrence of contact activation.

Determination of the bifunctional properties of high molecular weight kininogen by studies with monoclonal antibodies directed to each of its chains

In normal human plasma two forms of kininogen exist, low molecular weight kininogen (LMWK) and high molecular weight kininogen (HMWK). When these proteins are cleaved they are found to have a common heavy chain and bradykinin, but each has a unique light chain. Monoclonal antibodies to the heavy and light chains of HMWK have been developed, and the effects of each on the function of this protein are defined. Initial studies showed that an antibody, C11C1, completely neutralized the coagulant activity of plasma HMWK whereas another antibody, 2B5, did not. On a competitive enzyme-linked immunosorbent assay (CELISA) the C11C1 antibody was consumed by kininogen antigen in normal plasma but not by kininogen antigen in HMWK-deficient plasma. On immunoblot, the C11C1 antibody recognized one kininogen protein in normal plasma and did not recognize any kininogen antigen in HMWK-deficient plasma. These combined studies indicated that the C11C1 antibody was directed to an epitope on the unique 46-kDa light chain of HMWK. In contrast, the 2B5 antibody on a CELISA was consumed by kininogen antigen in both normal plasma and HMWK-deficient plasma but not by total kininogen-deficient plasma. On immunoblot, the 2B5 antibody recognized both kininogens in normal plasma but only LMWK in HMWK-deficient plasma. These combined studies indicated that the 2B5 antibody was directed to the common 64-kDa heavy chain of the plasma kininogens. Utilizing direct binding studies or competition kinetic experiments, the 2B5 and C11C1 antibodies bound with high affinity (1.71 and 0.77 nM, respectively) to their antigenic determinants on the HMWK molecule. The 2B5 antibody did neutralize the ability of HMWK to inhibit platelet calpain. These studies with monoclonal antibodies directed to each of the HMWK chains indicate that HMWK is a bifunctional molecule that can serve as a cofactor for serine zymogen activation and an inhibitor of cysteine proteases.

High molecular weight kininogen is an inhibitor of platelet calpain

Recent studies from our laboratory indicate that a high concentration of platelet-derived calcium-activated cysteine protease (calpain) can cleave high molecular weight kininogen (HMWK). On immunodiffusion and immunoblot, antiserum directed to the heavy chain of HMWK showed immunochemical identity with alpha-cysteine protease inhibitor--a major plasma inhibitor of tissue calpains. Studies were then initiated to determine whether purified or plasma HMWK was also an inhibitor of platelet calpain. Purified alpha-cysteine protease inhibitor, alpha-2-macroglobulin, as well as purified heavy chain of HMWK or HMWK itself inhibited purified platelet calpain. Kinetic analysis revealed that HMWK inhibited platelet calpain noncompetitively (Ki approximately equal to 5 nM). Incubation of platelet calpain with HMWK, alpha-2-macroglobulin, purified heavy chain of HMWK, or purified alpha-cysteine protease inhibitor under similar conditions resulted in an IC50 of 36, 500, 700, and 1,700 nM, respectively. The contribution of these proteins in plasma towards the inhibition of platelet calpain was investigated next. Normal plasma contained a protein that conferred a five to sixfold greater IC50 of purified platelet calpain than plasma deficient in either HMWK or total kininogen. Reconstitution of total kininogen deficient plasma with purified HMWK to normal levels (0.67 microM) completely corrected the subnormal inhibitory activity. However, reconstitution of HMWK deficient plasma to normal levels of low molecular weight kininogen (2.4 microM) did not fully correct the subnormal calpain inhibitory capacity of this plasma. These studies indicate that HMWK is a potent inhibitor as well as a substrate of platelet calpain and that the plasma and cellular kininogens may function as regulators of cytosolic, calcium-activated cysteine proteases.