Differential assay reactivity of immunglobulin A anti-ß2 glycoprotein I antibodies: implications for the clinical interpretation of antiphospholipid antibody testing

OBJECTIVE

The routine measurement of IgA anticardiolipin (aCL) and IgA anti-β₂ glycoprotein I (anti-β₂ GPI) antibodies remain controversial despite several studies demonstrating an association with thromboembolic disease in patients with systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS). This controversy may be a contributing factor for the current under use of IgA antiphospholipid antibodies. We aimed to investigate the nature of discrepant IgA anti-β₂ GPI reactivity to help define the diagnostic value of IgA antiphospholipid antibodies.

MATERIAL AND METHODS

Four sera selected from SLE/APS patients and positive for antiphospholipid antibodies but having discrepant IgA anti-β₂ GPI reactivity on two commercial assays were studied. IgA antibodies were affinity purified to investigate anti-β₂ GPI reactivity. Column wash through and eluent fractions were tested on both IgA anti-β₂ GPI assays. Results were normalized to total protein. Assay conjugates and standards from the discrepant assays were interchanged.

RESULTS

The diseased samples were strongly positive in one assay [144-388 IgA antiphospholipid (APL) units] and negative or weakly positive in another assay (9.9-53 APL units). IgA eluents from IgA anti-β₂ GPI positive samples reacted 10 times stronger on the reactive assay. When normalized to protein content, the eluents showed no cross-reactivity for IgG or IgM anti-β₂ GPI antibodies, confirming IgA isotype specificity. Conjugate interchange confirmed that both assays bound IgA anti-β₂ GPI antibodies, but the anti-IgA conjugate from the reactive assay was 4 times stronger, suggesting that its ability to detect IgA anti-β₂ GPI antibodies was partially dependent on the anti-IgA conjugate and calibration.

CONCLUSION

These results confirm not only the presence of IgA anti-β₂ GPI antibodies in the selected patient samples but also highlight an IgA conjugate issue for the unreactive assay, causing an underestimation of IgA anti-β₂ GPI. This finding may assist in the ongoing standardization efforts of APS antibody testing. In addition, conclusions from published clinical studies may need to be revised as some assays may understate IgA significance.

In utero exposure to benzo(a)pyrene predisposes offspring to cardiovascular dysfunction in later-life

In utero exposure of the fetus to benzo(a)pyrene [B(a)P], a polycyclic aromatic hydrocarbon, is thought to dysregulate cardiovascular development. To investigate the effects of in utero B(a)P exposure on cardiovascular development, timed-pregnant Long Evans Hooded (LEH) rats were exposed to diluent or B(a)P (150, 300, 600 and 1200 μg/kg/BW) by oral gavage on embryonic (E) days E14 (the metamorphosing embryo stage) through E17 (the 1st fetal stage). There were no significant effects of in utero exposure to B(a)P on the number of pups born per litter or in pre-weaning growth curves. Pre-weaning profiles for B(a)P metabolite generation from cardiovascular tissue were shown to be dose-dependent and elimination of these metabolites was shown to be time-dependent in exposed offspring. Systolic blood pressure on postnatal day P53 in the middle and high exposure groups of offspring were significantly elevated as compared to controls. Microarray and quantitative real-time PCR results were directly relevant to a biological process pathway in animal models for "regulation of blood pressure". Microarray and quantitative real-time PCR analysis revealed upregulation of mRNA expression for angiotensin (AngII), angiotensinogen (AGT) and endothelial nitric oxide synthase (eNOS) in exposed offspring. Biological network analysis and gene set enrichment analysis subsequently identified potential signaling mechanisms and molecular pathways that might explain the elevated systolic blood pressures observed in B(a)P-exposed offspring. Our findings suggest that in utero exposure to B(a)P predispose offspring to functional deficits in cardiovascular development that may contribute to cardiovascular dysfunction in later life.

Identification of potent and selective amidobipyridyl inhibitors of protein kinase D

The synthesis and biological evaluation of potent and selective PKD inhibitors are described herein. The compounds described in the present study selectively inhibit PKD among other putative HDAC kinases. The PKD inhibitors of the present study blunt phosphorylation and subsequent nuclear export of HDAC4/5 in response to diverse agonists. These compounds further establish the central role of PKD as an HDAC4/5 kinase and enhance the current understanding of cardiac myocyte signal transduction. The in vivo efficacy of a representative example compound on heart morphology is reported herein.

A novel kinase inhibitor establishes a predominant role for protein kinase D as a cardiac class IIa histone deacetylase kinase

Class IIa histone deacetylases (HDACs) repress genes involved in pathological cardiac hypertrophy. The anti-hypertrophic action of class IIa HDACs is overcome by signals that promote their phosphorylation-dependent nuclear export. Several kinases have been shown to phosphorylate class IIa HDACs, including calcium/calmodulin-dependent protein kinase (CaMK), protein kinase D (PKD) and G protein-coupled receptor kinase (GRK). However, the identity of the kinase(s) responsible for phosphorylating class IIa HDACs during cardiac hypertrophy has remained controversial. We describe a novel and selective small molecule inhibitor of PKD, bipyridyl PKD inhibitor (BPKDi). BPKDi blocks signal-dependent phosphorylation and nuclear export of class IIa HDACs in cardiomyocytes and concomitantly suppresses hypertrophy of these cells. These studies define PKD as a principal cardiac class IIa HDAC kinase.

Suppression of HDAC nuclear export and cardiomyocyte hypertrophy by novel irreversible inhibitors of CRM1

Histone deacetylase 5 (HDAC5) represses expression of nuclear genes that promote cardiac hypertrophy. Agonism of a variety of G protein coupled receptors (GPCRs) triggers phosphorylation-dependent nuclear export of HDAC5 via the CRM1 nuclear export receptor, resulting in derepression of pro-hypertrophic genes. A cell-based high-throughput screen of a commercial compound collection was employed to identify compounds with the ability to preserve the nuclear fraction of GFP-HDAC5 in primary cardiomyocytes exposed to GPCR agonists. A hit compound potently inhibited agonist-induced GFP-HDAC5 nuclear export in cultured neonatal rat ventricular myocytes (NRVMs). A small set of related compounds was designed and synthesized to evaluate structure-activity relationship (SAR). The results demonstrated that inhibition of HDAC5 nuclear export was a result of compounds irreversibly reacting with a key cysteine residue in CRM1 that is required for its function. CRM1 inhibition by the compounds also resulted in potent suppression of cardiomyocyte hypertrophy. These studies define a novel class of anti-hypertrophic compounds that function through irreversible inhibition of CRM1-dependent nuclear export.

Canonical Transient Receptor Potential Channels Promote Cardiomyocyte Hypertrophy through Activation of Calcineurin Signaling

The calcium/calmodulin-dependent phosphatase calcineurin plays a central role in the control of cardiomyocyte hypertrophy in response to pathological stimuli. Although calcineurin is present at high levels in normal heart, its activity appears to be unaffected by calcium during the course of a cardiac cycle. The mechanism(s) whereby calcineurin is selectively activated by calcium under pathological conditions has remained unclear. Here, we demonstrate that diverse signals for cardiac hypertrophy stimulate expression of canonical transient receptor potential (TRPC) channels. TRPC consists of a family of seven membrane-spanning nonselective cation channels that have been implicated in the nonvoltage-gated influx of calcium in response to G protein-coupled receptor signaling, receptor tyrosine kinase signaling, and depletion of internal calcium stores. TRPC3 expression is up-regulated in multiple rodent models of pathological cardiac hypertrophy, whereas TRPC5 expression is induced in failing human heart. We demonstrate that TRPC promotes cardiomyocyte hypertrophy through activation of calcineurin and its downstream effector, the nuclear factor of activated T cells transcription factor. These results define a novel role for TRPC channels in the control of cardiac growth, and suggest that a TRPC-derived pool of calcium contributes to selective activation of calcineurin in diseased heart.

The CRM1 nuclear export receptor controls pathological cardiac gene expression

Diverse pathological insults trigger a cardiac remodeling process during which myocytes undergo hypertrophy, with consequent decline in cardiac function and eventual heart failure. Multiple transcriptional regulators of pathological cardiac hypertrophy are controlled at the level of subcellular distribution. For example, prohypertrophic transcription factors belonging to the nuclear factor of activated T cells (NFAT) and GATA families are subject to CRM1-dependent nuclear export but are rapidly relocalized to the nucleus in response to cues for hypertrophic growth. Here, we demonstrate that the antihypertrophic chromatin-modifying enzyme histone deacetylase 5 (HDAC5) is shuttled out of the cardiomyocyte nucleus via a CRM1-mediated pathway in response to diverse signals for hypertrophy. CRM1 antagonists block the agonist-mediated nuclear export of HDAC 5 and repress pathological gene expression and associated hypertrophy of cultured cardiomyocytes. Conversely, CRM1 activity is dispensable for nonpathological cardiac gene activation mediated by thyroid hormone and insulin-like growth factor 1, agonists that fail to trigger the nuclear export of HDAC5. These results suggest a selective role for CRM1 in derepression of pathological cardiac genes via its neutralizing effects on antihypertrophic factors such as HDAC5. Pharmacological approaches targeting CRM1-dependent nuclear export in heart muscle may have salutary effects on cardiac function by suppressing maladaptive changes in gene expression evoked by stress signals.

Inhaled benzo(a)pyrene impairs long-term potentiation in the F1 generation rat dentate gyrus

The purpose of this study is to provide a point of reference regarding the neurotoxic effects resulting from exposure to environmental contaminants. Benzo(a)pyrene is a member of the polycyclic aromatic hydrocarbon (PAH) family and it is a by-product of combustion processes. Thus, persons living near factories or hazardous waste sites face the danger of exposure through contact with contaminated air, water and soil. In an effort to understand the impact of environmental contaminants, we have investigated the effects of gestational B(a)P aerosol exposure on long-term potentiation (LTP), a cellular correlate of learning and memory in the F1 generation. Briefly, timed-pregnant rats were exposed to B(a)P via nose-only inhalation on gestation days 11-21 for 4 hr per day. Dams were maintained to term and pups were weaned on postnatal day 30. Subsequent electrophysiological studies during postnatal days 60-70 revealed a diminution in LTP across the perforant path-granular cells synapses in the hippocampus of F1 generation animals that were transplacentally exposed to B(a)P aerosol relative to unexposed controls. Additionally, NMDA receptor subunit 1 (NR1) protein was found to be downregulated in the hippocampus of B(a)P exposed F1 generation animals. Taken together, our results suggest that gestational exposure to B(a)P aerosol attenuates the capacity for LTP in the F1 generation.

Downregulation of hippocampal NMDA receptor expression by prenatal exposure to dioxin

Gestational exposure to the environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (dioxin) has been implicated as causative to disparities between ethnic groups with respect to learning disabilities. Dioxin is an extremely toxic environmental pollutant that bioaccumulates in maternal adipose tissue, and is transferred to the developing organism during gestation and lactation. Long-term cognitive deficits have been reported following prenatal exposure to dioxin. N-methyl-D-aspartate (NMDA) receptors in the central nervous system (CNS) have been well known to play an important role in the activity-dependent synaptic plasticity underlying learning and memory and in CNS development including brain cell differentiation. Here, the effects of prenatal exposure to dioxin on the developmental expression profiles of rat hippocampal NMDA receptor subtype 1 mRNA and protein was examined. F-344 rats were exposed to 0 and 700 ng of dioxin/kg on gestational day 15. Real-time PCR and Western blot analysis clearly revealed that dioxin significantly downregulated NMDAR1 mRNA and protein expression during the first postnatal month. The study provides support to the hypothesis that NMDA receptors are important targets for dioxin-induced neurotoxicity in F1 preweaning pups. The results also support the concept that prenatal exposure to dioxin may contribute to the pathogenesis of diseases in the adult.

Metabolism, bioavailability, and toxicokinetics of benzo(alpha)pyrene in F-344 rats following oral administration

The objective of this study was to evaluate the bioavailability of Benzo(a)pyrene [B(a)p], subsequent to oral exposure. Eight-week-old F-344 rats were dosed orally with 100 mg/kg body weight B(a)p and sacrificed at 0, 0.5, 1.0, 2.0, 4.0. 8.0, 24, 48 and 72 hours post exposure. Blood, liver, reproductive tissues, urine and fecal samples were collected at necropsy and were analyzed for parent B(a)p and metabolites by HPLC with fluorescence detection. Peak levels of B(a)p in plasma occurred 8 hours after exposure (67%) followed by a gradual decrease. Liver retained 10% of the administered B(a)p up to 24 hours following, which the levels dropped during the remaining time periods studied. Twenty-four hours after administration, 45% of the dose was excreted in feces and urine. Metabolite levels in plasma peaked at 24 hours (10%) and decreased to 1% at 72 hours. In the liver, metabolite levels were higher at 8 hours (10%) but were only 3% at 72 hours. Benzo(a)pyrene levels increased after 24 hours in the reproductive organs and constituted 10% of the administered dose at 72 hours. Blood showed high levels of 7,8-diol than 9,10 and 4,5-diols which were high in liver and reproductive organs. Compared to diols, the hydroxy metabolites were detected at high levels in urine and fecal samples. Among the aqueous phase metabolites, glucuronides were at higher levels compared to glutathiones and sulfates. The slow release of unmetabolized B(a)p from reproductive organs and the presence of reactive metabolites in these organs is a matter of concern as they could interfere with gonadal steroid synthesis and release and its regulatory role in gamete production, maturation and function of male animals in a continuous exposure paradigm.

Toxicokinetics of inhaled benzo[a]pyrene: plasma and lung bioavailability

Bioavailability and toxicokinetic studies are essential in order to establish dose-response relationships of widely distributed environmental toxicants such as benzo[a]pyrene (BaP), a polycyclic aromatic hydrocarbon. Fischer 344 rats were exposed for 4 h (via nose-only inhalation) to aerosol exposure concentrations of 0.1, 1.0, and 2.5 mg/m(3) of BaP absorbed onto carbon black particles using a state-of-the-art model aerosol generation system. Nominal and chamber concentrations of the particulate aerosol were determined gravimetrically with a seven-stage cascade impactor. The average aerosol for the 3 exposure concentrations used in this study exhibited a trimodal distribution with 93% cumulative mass less than 15.85 microm, 89% cumulative mass less than 10 microm, 55.3% cumulative mass less than 2.5 microm, and 38% less than 1 microm. Fifty-five percent of the aerosol had a cumulative mass less than PM(2.5) and the mass median aerodynamic diameter (MMAD) -/+ geometric standard deviation (GSD) for this mode was 1.7 -/+ 0.085 microm. Plasma and lung samples were collected at 30, 60, 120, and 240 min postexposure. The concentrations of BaP parent compound and metabolites were determined by high-performance liquid chromatography. The toxicokinetic parameters were computed from the time course of plasma BaP concentration. The bioavailability of BaP increased as a function of exposure concentration, and toxicokinetic analysis indicates first-order pharmacokinetics for BaP. However, some toxicokinetic parameters such as clearance and volume of distribution remained constant throughout the duration of the postexposure period. BaP and its metabolite concentrations in plasma peaked at 1 h postexposure. At 240 min postexposure, only trace levels of BaP remained in the plasma. The BaP metabolites in the lung showed an identical trend where no parent compound was detected. Among the metabolites detected, BaP 4,5-, 7,8-, and 9,10-dihydrodiols, 3-OH-BaP, and 9-OH-BaP were predominant.

Modulation in the developmental expression profile of Sp1 subsequent to transplacental exposure of fetal rats to desorbed benzo[a]pyrene following maternal inhalation

Any alteration of the critical sequence of genes that are required to coordinate the differentiation of cells, the promotion of migration, dendritic arborization, synapse formation, and myelination in the developing nervous system would be expected to have deleterious consequences. The focus of this article is a molecular evaluation of the neurotoxicological effects that result subsequent to the transplacental exposure of fetal rats to desorbed benzo(a)pyrene (BaP) following maternal inhalation. A state-of-the-art, newly designed, fabricated, and tested model aerosol generation system was utilized in these studies. Timed-pregnant Sprague Dawley rats were exposed for 4 h on gestation day 15 of a 21-day gestation period to an acute dose of BaP:carbon black aerosol (100 microg/m(3)). Controls received carbon black only. Nominal and chamber concentrations of the particulate aerosol were determined gravimetrically with a seven-stage cascade impactor. The aerosol exhibited a trimodal distribution with 95% cumulative mass less than 15.85 microm, 90% cumulative mass less than 10 microm, 67. 5% cumulative mass less than 2.5 microm and 66.2% cumulative mass less than 1.0 microm. Time-course bioavailability results indicated that greater than 95% of the parent compound is cleared from blood 240 min postexposure. An Sp1 transcription factor consensus sequence was examined by electrophoretic mobility shift analysis of nuclear extracts from various brain regions of resulting pups on postnatal days 3, 5, 7, 10, and 15. It revealed perturbations in the developmental expression profile of Sp1 abundance as a result of nose-only particulate aerosol exposure to the timed-pregnant dam. The data obtained on the temporal and spatial regulation of gene expression in the brain indicate that (1) Sp1 DNA-binding is developmentally regulated and expressed very highly in actively developing brain regions, and (2) a consequence of the transplacental deposition of desorbed BaP to the fetus is in utero neurotoxicity.

Aryl hydrocarbon hydroxylase activity in F-344 rats subchronically exposed to benzo(a)pyrene and fluoranthene through diet

In order to investigate the relationship between aryl hydrocarbon hydroxylase (AHH) activity and exposure to benzo[a]pyrene [B(a)p] and fluoranthene (FLA), AHH activities in liver tissues of male and female F-344 rats were determined. Based on a range-finding study, doses of 0, 5, 50, and 100 mg/kg B(a)p or 0, 150, 750, and 1500 mg/kg FLA were administered in the animal diet over a 90-day period. After dosing, animals were sacrificed, liver tissues were removed, and microsomes were isolated. AHH activities were determined by reverse-phase HPLC coupled with fluorescence detection using 3-hydroxy B(a)p, and trans-2,3-dihydroxy-1,10-epoxy-1,2,3,10b tetrahydrofluoranthene as the standards. A dose-dependent increase in enzyme activity was observed with increased B(a)p or FLA exposure in both males and females. Our results also demonstrate that B(a)p-exposed females possess a higher AHH activity than males, but there is no significant sex difference with regard to enzyme activity in the case of FLA at higher doses. Overall, our findings suggest that long-term exposure to the parent compound results in elevated levels of AHH activity, which may contribute to the formation of toxic reactive metabolites and subsequent symptoms in target organs.

The use of colorflow duplex scanning to detect significant renal artery stenosis

The purpose of this study was to review our institutional experience with colorflow duplex scanning in detecting significant renal artery stenosis and to validate the criteria used: renal artery peak systolic velocity (PSV) >/=200 cm/sec and renal-to-aortic peak systolic ratio (RAR) >/=3.5. The results of renal artery duplex and arteriography in 58 patients (107 kidneys) who underwent both exams were reviewed. Arteriography revealed 32 main renal arteries with >/=60% stenosis. The PSV criterion detected 29, for a sensitivity of 91%, specificity of 75%, positive predictive value (PPV) of 60%, negative predictive value (NPV) of 95%, and accuracy of 79%. Using RAR >/=3.5 provided a sensitivity of 72%, specificity of 92%, PPV of 79%, NPV of 88%, and accuracy of 86%. In a subset of 36 kidneys that had hilar scans, the criteria of acceleration time (AT) >/=100 cm/sec and index (AI) </=3.78 kHz/sec were evaluated. The AT and AI yielded sensitivity of 50% and 36%, specificity of 86% and 100%, PPV of 70% and 100%, NPV of 73% and 71%, and accuracy of 72% and 75%, respectively. Colorflow duplex scanning is clinically useful in screening for hemodynamically significant renal artery stenosis. The renal artery PSV criterion is highly sensitive, with a high NPV that obviates the need for arteriography in most cases of a negative duplex. The criteria of RAR, AT, and AI are of less value.

The standardized vascular clinic: an alternative to the traditional ambulatory setting

PURPOSE

To investigate the effectiveness of a standardized vascular clinic (SVC) in teaching diagnostic and management skills for common vascular problems, as compared with that of the traditional ambulatory setting.

METHODS

Third-year medical students participating in the required surgical clerkship participated in this study. Students were randomly assigned to attend either a 4-hour SVC experience (group 1, n = 64) or a 4-hour traditional ambulatory experience (group 2, n = 60). Students completed a satisfaction rating scale and a preencounter and postencounter self-efficacy rating scale at the end of the experience. Student t tests were used to compare the groups in the areas of knowledge acquisition, problem solving, clinical skills and satisfaction with the encounter. Analysis of covariance was used to compare the change between pre and post self-efficacy ratings.

RESULTS

Students in group 1 performed significantly higher than students in group 2 in the areas of problem solving, clinical skills, and student satisfaction. They also demonstrated a higher level of confidence in their vascular skills than students assigned to the traditional setting.

CONCLUSION

The SVC may be more effective in teaching problem-solving and clinical skills. It also may promote more student satisfaction with the experience and confidence in clinical skills than the traditional ambulatory setting.

Percutaneous transluminal angioplasty and stenting for iliac artery occlusive disease

Atherosclerotic iliac artery stenoses respond well to simple balloon angioplasty and have the best results of all of the peripheral vessels. Nonetheless, initial technical failures occur in as many as 20% of patients, most of which can be salvaged with intravascular stenting, as can many of the potential complications; however, even though the initial technical success rates for stenting approach 100%, stenotic recurrences within stents are not infrequent. Whether promising new concepts, such as brachytherapy, gene therapy, and endoluminal grafting, will have a durable impact on the results of iliac angioplasty is yet to be seen. Meanwhile, the excellent results of endoluminal treatment of patients with iliac artery occlusive disease, combined with the relatively low risk for complications compared with surgical revascularization, ensure an enduring role for this modality of treatment and a diminution in the fraction of patients requiring surgery to correct their iliac artery occlusive disease.

Changing perspectives in the diagnosis of peripheral vascular trauma

The diagnosis of peripheral vascular trauma has undergone significant evolution in the last two decades. A minority of patients with arterial trauma present with classic findings that make the diagnosis obvious. However, the diagnosis of occult arterial injuries is more challenging, and it is for this group that the diagnostic algorithm has changed most significantly. Because of the low yield of routine operative exploration and routine arteriography to evaluate potential injury to vessels in proximity to penetrating wounds, many authors now recommend the selective use of arteriography or other diagnostic modalities based on the results of clinical examination and noninvasive pressure determinations. This article reviews the evidence in support of such a selective approach to the diagnosis of arterial injuries.

Breast screening: the psychological sequelae of false-positive recall in women with and without a family history of breast cancer

The psychological effects of false-positive mammography were evaluated in 124 women who had taken part in the U.K. National Health Service Breast Screening Programme. In addition, the effects of recall on women with and without a family history were compared. These women were asked to complete the Hospital Anxiety and Depression Scale (HADS) before being invited to attend for screening, at recall and 5 weeks and 4 months after recall. At screening and at recall, the women were asked to complete the Health Questionnaire (HQ) which measures stress-related behaviour changes in the previous week. In the week before screening, compared with women who did not have a family history of breast cancer, women with a family history had lower scores on HADS depression and reported fewer stress-related behaviour changes. At recall, regardless of family history, the women were more likely to have borderline or clinically significant anxiety than at baseline or screening. Nevertheless, for most women, recall-induced anxiety was relatively transient (less than 5 weeks). Compared with women without a family history, women with a family history were more anxious 4 months after recall, although their anxiety scores tended to be lower (P < 0.06) than at baseline. A strength of the present study is that the initial baseline measure was uncontaminated by the screening process. Women who did not complete questionnaires at one or more of the subsequent time points scored higher on HADS depression at baseline, indicating that the results are likely to have underestimated the effects of recall. Screening appears to be less stressful for women with a family history than for those without a history. However, for both groups recall causes short term distress. Breast screening programmes should ensure that steps are taken to minimise the number of women who are recalled for unnecessary investigations.

Combined carotid endarterectomy and coronary artery bypass grafting in asymptomatic carotid artery stenosis

The role of combined carotid endarterectomy (CEA) and coronary artery bypass grafting (CABG) in patients with severe asymptomatic carotid artery disease and concurrent symptomatic coronary artery disease is controversial. The objective of this report is to investigate the safety of combined CEA/CABG. The medical records of 30 patients who underwent combined CEA/CABG for coexistent asymptomatic carotid and symptomatic coronary artery occlusive disease were reviewed. All patients were scheduled for either elective or urgent myocardial revascularization due to their symptomatic coronary artery disease. Color-flow duplex scanning identified internal carotid artery stenosis of 80 to 99 per cent in 28 patients (93%) and 50 to 79 per cent in 2 patients (7%). Seventeen patients (57%) were male. The mean age was 64 +/- 10 years (range, 42-84 years). Contralateral internal carotid artery occlusion was present in four patients. Severe left main coronary artery disease was present in 12 patients (40%) and 7 patients (23%) had an ejection fraction of less than 50 per cent. There were no perioperative deaths or strokes. One patient suffered a myocardial infarction on postoperative day 1. This study demonstrates the safety of combined CEA/CABG for coexistent coronary and asymptomatic carotid disease. Using this surgical approach for critical coexistent disease may minimize the incidence of perioperative cerebrovascular complications in patients undergoing CABG.

Vascular complications of thoracic outlet syndrome

Vascular complications of thoracic outlet syndrome are uncommon but may result in significant long-term disability. This report documents a retrospective review of 17 such patients. Ten patients presented with acute onset of upper extremity swelling and axillosubclavian vein thrombosis. One patient presented with chronic, intermittent arm swelling and subclavian vein stenosis. Three patients presented with acute symptoms of upper extremity emboli, and three presented with chronic arm claudication. Cervical ribs were discovered in four patients with arterial symptoms and in no patients with venous symptoms. All ten patients with acute venous thrombosis underwent successful thrombolysis, with venous stenosis uncovered in 8. Thrombolysis was also performed for two patients with arterial emboli. All 17 patients underwent surgical decompression of the thoracic outlet, 16 via a supraclavicular approach and one via a transaxillary approach. One subclavian arteriotomy with endarterectomy and one resection of a subclavian artery aneurysm were performed at the time of decompression. Repeat venography after decompression demonstrated persistent venous stenosis in one patient that was treated with balloon angioplasty and stenting. After a mean of 22 months' follow-up, 12 patients had no residual symptoms, and 5 had experienced significant improvement of symptoms. In conclusion, a combined approach of thrombolysis and surgical decompression of the thoracic outlet provides a salutary outcome in a majority of patients.

Local anesthesia for infrainguinal arterial reconstruction

PURPOSE

Perioperative cardiac complications occur in 4% to 6% of patients undergoing infrainguinal revascularization under general, spinal, or epidural anesthesia. The risk may be even greater in patients whose cardiac disease cannot be fully evaluated or treated before urgent limb salvage operations. Prompted by these considerations, we investigated the feasibility and results of using local anesthesia in these high-risk patients.

METHODS

From January 1, 1994, through August 30, 1996, 86 infrainguinal reconstructions were performed under local infiltration anesthesia (0.5% or 1.0% lidocaine). Supplementary intravenous sedation with propofol or other agents was given as needed for patients comfort. Most patients had arterial lines but Swan Ganz catheters were used infrequently. Postoperatively, continuous electrocardiographic monitoring was continued in the intermediate or intensive care units. Patients ranged in age from 37 to 86 years (mean 68 +/- 12); 47% were diabetic, 69% had severe coronary artery disease, and 14% had end-stage renal disease.

RESULTS

Operations included 7 femoral-femoral, 21 femoral-popliteal, 16 femoral-tibial and 13 popliteal-tibial bypass grafts, 9 pseudoaneurysms, and 20 distal graft revisions (+/- thrombectomy). Autogenous vein was used in eight of the femoral-popliteal and all of the femoral-tibial and popliteal-tibial bypass grafts. There were two postoperative deaths. One patient died of a stroke (1.2%) on postoperative day (POD) 2 and one died on POD 27 of unknown cause. Two other (2%) patients had nonfatal subendocardial myocardial infarctions. Conversion to general anesthesia was required in four (5%) operations, three because patients became agitated and one because a long segment of vein had to be harvested from the opposite leg. Otherwise, patients tolerated the procedures well and postanesthetic recovery problems were minimized.

CONCLUSIONS

Limb salvage operations can be done under local anesthesia with acceptable complication rates. In selected patients with high-risk coronary artery disease, local anesthesia has theoretic and practical advantages and should be considered an alternative to general or regional anesthesia.

Prevalence and distribution of calf vein thrombosis in patients with symptomatic deep venous thrombosis: a color-flow duplex study

PURPOSE

This retrospective study was performed to identify the patterns of calf vein thrombosis in patients in whom deep vein thrombosis (DVT) was suspected and to better define the role of color-flow duplex scanning (CDS) in the evaluation of this patient population.

METHODS

Over a recent 9-month period, we reviewed the vascular laboratory charts of 540 symptomatic patients (696 limbs) who underwent CDS for clinically suspected acute DVT. Patients who had a previous episode of DVT were excluded.

RESULTS

CDS satisfactorily visualized all three paired calf veins in 655 of the limbs (94%). Inadequate scans (n = 41) were attributed to edema in 29, excessive calf size in eight, and anatomic inaccessibility in four. Peroneal veins were the most difficult to visualize (n = 29), followed by posterior tibial (n = 10) and anterior tibial (n = 9) veins. CDS identified acute DVT in 159 of 655 limbs (24%) that had adequate scans. Calf vein thrombi were detected in 110 of the 655 limbs (17%) and in 69% of the 159 limbs with DVT. Clots were confined to the calf veins in 53 limbs with DVT (33%). Isolated calf vein thrombi were found in 45% of outpatient limbs and in 27% of inpatient limbs with DVT. The peroneal (81%) and posterior tibial veins (69%) were more frequently involved (p < 0.001) than the anterior tibial veins (21%). In limbs with calf DVT, the prevalence of thrombosis isolated to the peroneal and posterior tibial veins was similar (37% and 25%, respectively); no limb had an isolated anterior tibial DVT (p = 0.02).

CONCLUSION

CDS is a reliable method for evaluating calf veins for DVT. Calf vein thrombosis is common in patients who have acute DVT and often occurs as an isolated finding. The peroneal and posterior tibial veins are involved in the majority of cases; thrombi occur much less frequently in the anterior tibial veins. We conclude that CDS should be the noninvasive method of choice for the initial evaluation of patients in whom DVT is suspected, and we recommend that calf veins should always be studied but that routine scanning of the anterior tibial veins may not be necessary.

Determinants of success of color-flow duplex-guided compression repair of femoral pseudoaneurysms

BACKGROUND

Ultrasonography-guided compression repair is reported to be effective therapy for femoral pseudoaneurysms that develop after catheterization procedures. This study summarizes our experience with color-flow duplex-guided repair of these lesions.

METHODS

A retrospective chart review of all patients who underwent this procedure was undertaken, with statistical analysis to identify factors associated with success.

RESULTS

Compression repair of 69 pseudoaneurysms was attempted. Pseudoaneurysms developed after therapeutic catheterization in 48 patients and after diagnostic procedures in 21. Sites of arterial puncture were the common femoral artery in 59 patients and the superficial femoral or profunda femoris arteries in 10. Diameters of the pseudoaneurysms ranged from 3 to 60 mm (mean, 28 mm). Compression was attempted at a mean of 5 days (range, 1 to 21 days) after catheterization. Compression produced complete thrombosis of the pseudoaneurysm at the initial attempt in 43 (62%) of 69 patients. With repeated attempts the ultimate success was 47 (68%) of 69. Success was achieved in 44 (75%) of 59 common femoral pseudoaneurysms but in only 3 (30%) of 10 superficial femoral or profunda femoris lesions (p = 0.009). Anticoagulation, sheath size, pseudoaneurysm chamber size, and time between catheterization and compression were not significantly different between lesions that were successfully compressed and those that were not. No ischemic or embolic complications were observed.

CONCLUSIONS

Color-flow duplex-guided compression repair can be safely attempted as the initial therapy for all uncomplicated pseudoaneurysms arising from the common femoral artery after catheterization, with the expectation of success in most.

Cardiac evaluation of the diabetic patient prior to peripheral vascular surgery

The benefit of preoperative cardiac evaluation in the diabetic patient undergoing peripheral vascular surgery is uncertain. To investigate this issue we performed a retrospective review of 192 procedures performed in diabetic patients for chronic lower extremity arterial occlusive disease. The incidence of adverse postoperative cardiac events was determined, as well as its association with several preoperative factors including symptoms of coronary artery disease (CAD), extent and results of preoperative noninvasive cardiac evaluation, and operative site (aorta vs. lower extremity). The overall death and cardiac complication rates were 10.2% for lower extremity and 25.7% for aortic procedures (p = 0.02). For myocardial infarction and cardiac death alone, the rates were 5.1% and 5.7%, respectively (p > 0.10). Although a history of symptomatic CAD predicted the occurrence of any cardiac complication (28.3% vs. 8.2% [p < 0.01] for the aortic and lower extremity revascularization groups combined), no factor was found to be associated with the occurrence of myocardial infarction and cardiac death alone. In patients with a history of symptomatic CAD, there was no significant difference in the incidence of complications whether or not preoperative noninvasive cardiac testing was performed (28.1% vs. 28.6%, p > 0.10) or, if testing was performed, if the results were abnormal or normal (35.3% vs. 20.0%, p > 0.10). Similar results were obtained in patients with no history of symptomatic CAD. In summary, this retrospective review of our experience with noninvasive evaluation to detect CAD in diabetic patients undergoing peripheral vascular surgery failed to show any benefit in terms of reducing the incidence of postoperative cardiac events.

Prospective evaluation of new duplex criteria to identify 70% internal carotid artery stenosis

PURPOSE

Large multicenter trials (North American Symptomatic Carotid Endarterectomy Trial, European Carotid Surgery Trial) have documented the benefits of carotid endarterectomy for treating symptomatic patients with >or=70% stenosis of the internal carotid artery. Although color-flow duplex scanning has become the preferred method for noninvasive assessment of internal carotid artery disease, no criteria have been generally accepted to identify this subset of patients. We previously reported a retrospective series to establish such criteria. This study details our results when these criteria were applied prospectively.

METHODS

Carotid color-flow duplex scans were compared with arteriograms in 457 patients who underwent both studies. Criteria for >or=70% internal carotid artery stenosis were peak systolic velocity >130 cm/sec and end-diastolic velocity >100 cm/sec. Internal carotid arteries with peak systolic velocity <40 cm/sec in which only a trickle of flow could be detected were classified as preocclusive lesions (95% to 99% stenosis). Arteriographic stenosis was determined by comparing the diameter of the internal carotid artery at the site of maximal stenosis to the diameter of the normal distal internal carotid artery.

RESULTS

Internal carotid artery stenosis of >or=70% was detected with a sensitivity of 87%, specificity of 97% positive predictive value of 89%, negative predictive value of 96%, and overall accuracy of 95%. Eighty-seven percent of 70% to 99% stenoses were correctly identified. False-positive errors (n=10) were attributed to contralateral internal carotid artery occlusion or high-grade (>90%) stenosis (n=5) and to interpreter error (n=1); no explanation was apparent in the other four. Eleven of 12 false-negative examinations occurred in patients with 70% to 80% internal carotid artery stenosis.

CONCLUSIONS

In our laboratories, prospective application of the above velocity criteria identified internal carotid artery stenosis of >or=70% with a reasonably high degree of accuracy. Errors occurred when stenoses were borderline and in patients with severe contralateral disease. With suitably modified velocity criteria, color-flow duplex scanning remains the most reliable noninvasive method for identifying symptomatic patients who are candidates for carotid endarterectomy.

Incorporation of endovascular training into a vascular fellowship program

BACKGROUND

Despite expanding indications for endovascular therapy of peripheral vascular disease, vascular surgeons have largely remained bystanders in the use of this form of treatment for the disease, which is the focus of their profession. Lack of access to training in endovascular techniques is a major obstacle to increasing involvement by vascular surgeons. This paper reports our experience in the endovascular training of vascular surgical fellows without the involvement of radiologists.

METHODS

The results of vascular surgery fellows receiving instruction in endovascular diagnostic and therapeutic procedures from vascular surgery faculty were reviewed.

RESULTS

Endovascular training of vascular surgery fellows exceeded the case levels recommended by all involved societies. A diverse case mix of 355 endovascular diagnostic procedures were performed with a major complication rate of 0.3% and no procedure-related deaths. Two hundred six endovascular interventions were performed, with an initial technical success rate of 96.6%, a 30-day success rate of 93%, no major complications, and an overall intervention-related mortality rate of less than 1%.

CONCLUSIONS

Vascular surgery fellows can receive endovascular training by vascular surgery faculty without the involvement of radiologists and can do so with acceptable success and complication rates. This experience is sufficient to qualify them to perform and teach endovascular therapy in their future practices.

Detection of total occlusion, string sign, and preocclusive stenosis of the internal carotid artery by color-flow duplex scanning

BACKGROUND

Stroke prevention depends on the accurate differentiation of surgically treatable preocclusive lesions from total occlusions of the internal carotid artery. This prospective study was undertaken to review the accuracy of colorflow duplex scanning for identifying carotid string signs, focal preocclusive lesions (95% to 99% stenoses), and total occlusion of the internal carotid artery.

MATERIALS AND METHODS

Over an 18-month period, 4,362 patients underwent color-flow duplex scanning of the carotid arteries. Angiograms of 596 internal carotid arteries were available for comparison with the duplex scan findings. Total occlusion was diagnosed by the absence of flow in internal carotid arteries visualized on B-mode scanning. Preocclusive lesions were identified by a trickle of flow in the vessel lumen.

RESULTS

Of 65 color-flow duplex scans that predicted total occlusion, 64 (98%) were confirmed by angiography. The negative predictive value for total occlusion was 99%. Twenty-six (87%) of 30 string signs and focal 95% to 99% stenoses were correctly identified. Color-flow scanning prediction of preocclusive lesions was accurate in 84% of 31 cases. Low velocities in the internal carotid artery were usually associated with a string sign, and high velocities with a focal preocclusive lesion.

CONCLUSIONS

Color-flow duplex scanning accurately differentiates between stenotic and totally occluded internal carotid arteries. Identification of preocclusive lesions is not as accurate but the results are promising. Arteriographic confirmation of duplex scan findings is necessary only when scans are equivocal.

Hemodialysis graft salvage with endoluminal stents

The most common cause of failure of hemodialysis access sites is stenosis within the site. The stenoses have traditionally been corrected surgically, but endovascular techniques may be an alternative method to treat these flow-limiting lesions and maintain graft patency. Over a recent 17-month period, endoluminal stents to relieve stenoses resistant to balloon dilatation alone were placed in 14 access sites. All sites were located on the upper extremity (13 PTFE bridge grafts and 1 A-V fistula). A total of 20 stents were placed: seven at the venous anastomosis, 12 in the venous outflow tract (including 3 in the subclavian vein), and one within the graft. Nine patients had placement of a single stent, four patients had two stents placed, and one patient had three. An additional eight stenotic lesions within these 14 sites were successfully dilated without need of a stent. After stent placement, these 14 sites have remained functional for a mean of 6.2 months. Four were functioning without further intervention at a mean of 8.5 months. Nine sites occluded at a mean of 4.7 months. The remaining site remained functional until death of the patient 10 months after stent placement. Of the nine failed sites, four developed restenosis at the site of stent placement, four developed stenoses at other sites, and the other site was abandoned. Three stents were placed in subclavian vein stenoses, and none of these has failed. Further study is necessary to determine whether endovascular stenting of dialysis access site stenoses will prove to be a durable, cost-effective alternative to surgical revision.

Orthotopic ex vivo renal artery reconstruction

Ex vivo renal artery reconstruction is a technique used to repair renal vascular lesions not amenable to conventional in situ methods of revascularization, either because of anatomical considerations or the inability of the kidney to tolerate the extended period of warm ischemia necessary to complete the procedure. In general, this refers to lesions at or beyond the division of the main renal artery into the segmental branches. The kidney is mobilized to the level of the abdominal wall after dividing the origins of the renal artery and vein from the aorta and inferior vena cava, respectively. The ureter is left intact. The kidney is cooled by placing it in an external slush bath and by perfusion through the renal vessels of a cold electrolyte solution. A suitable conduit (usually saphenous vein or hypogastric artery) is then prepared for grafting. After completion of the distal anastomosis(es), the kidney is returned to the renal fossa, and the proximal anastomosis to the aorta is completed. The renal vein is then reattached, thus completing revascularization of the kidney. We report our experience with five orthotopic ex vivo renal artery reconstructions. Indications for the procedure, details of the technique, and expected results are discussed.

Alpha 1-proteinase inhibitor variant T345R. Influence of P14 residue on substrate and inhibitory pathways

To test whether the presence of charged residues at position P14 of the reactive center region of noninhibitory members of the serpin family of protein proteinase inhibitors is responsible for their lack of proteinase inhibitory properties, we expressed a variant of the alpha 1-proteinase inhibitor (alpha 1-PI) with arginine substituted for threonine at this position (T345R) and characterized its functional properties. Although the T345R variant reacted with proteinases principally as a substrate, it was still capable of forming stable complexes with the three serine proteinases examined, human neutrophil elastase (HNE), porcine pancreatic elastase (PPE), and trypsin. The fraction of T345R alpha 1-PI that formed a complex with proteinase was quantitated by autoradiography of SDS gels of the variant incubated with 125I-labeled proteinase. The stoichiometry of inhibition (S.I.) (number of mol of alpha 1-PI required to completely inhibit 1 mol of proteinase), which was 1 for both plasma alpha 1-PI and wild-type recombinant alpha 1-PI interacting with each of the proteinases, was very much greater than 1 for T345R variant alpha 1-PI. Values of 9.5, 45, and about 70 were estimated for variant alpha 1-PI inhibition of trypsin, HNE, and PPE, respectively. An inverse relationship between the apparent second-order rate constant and the S.I. for inhibition of PPE by T345R alpha 1-PI suggested that the mutation did not affect the rate-determining step of formation of a transient intermediate complex. Following cleavage of the reactive center loop, there was a large increase in protein stability and changes in the CD spectrum, both consistent with insertion of the reactive center loop into beta-sheet A. This behavior is similar to that of wild-type alpha 1-PI. We conclude that the presence of a charged residue at P14 does not prevent reactive center loop insertion or the functioning of alpha 1-PI as an inhibitor of serine proteinases but does significantly alter the relative rates of the substrate and inhibitory pathways in favor of the former, probably by reducing the rate of the latter reaction.

Advances in the treatment of phlegmasia cerulea dolens

Phlegmasia cerulea dolens (PCD) is an uncommon, severe form of lower extremity deep venous thrombosis characterized by extremity swelling, cyanosis, and pain. Progression of the thrombotic process may result in extremity gangrene, amputation, and death. The relative value of specific therapeutic regimens in the treatment of this disease remains uncertain. Twelve patients, 9 females and 3 males, with PCD were treated during a 10-year period. Eighteen lower extremities were involved. Pre-existing conditions included malignancy (eight), postoperative state (four), diabetes (three), previous deep venous thrombosis (three), and hypercoagulation (two). Venous gangrene was present in four patients. All patients were treated initially with bedrest, fluid resuscitation, extremity elevation, and systemic high-dose heparin therapy. Five patients had complete resolution with this regimen alone. One patient required cessation of heparin therapy due to heparin-induced thrombocytopenia and developed gangrenous toes. Two patients whose condition failed to respond to heparin therapy underwent catheter-based delivery of urokinase with marked clinical improvement. Four patients, two with venous gangrene, died, three of whom had disseminated malignant disease. A significant percentage of patients with PCD will respond to extremity elevation, fluid resuscitation, and aggressive systemic anticoagulation therapy. Thrombolytic therapy selectively administered is beneficial in patients whose disease fails to respond promptly. Venous thrombectomy should be reserved for patients with contraindications to thrombolysis.

Nitrogen dioxide reactivity with proteins: effects on activity and immunoreactivity with alpha-1-proteinase inhibitor and implications for NO2-mediated peptide degradation

Nitrogen dioxide (NO2), an air pollutant produced by burning fossil fuels and a component of cigarette smoke, is thought to contribute to the pathogenesis of pulmonary diseases, such as emphysema. In order to gain information on the mechanism by which NO2 damages the lung and proteins vital to its function, as well as its reaction with proteins in general, in vitro exposures of alpha-1-proteinase inhibitor (alpha 1PI), elastin, poly-L-lysine, and poly-L-arginine were performed. The ability of alpha 1PI to inhibit its natural physiological target, human neutrophil elastase (HNE), declined with exposure to 54% of the control value at molar ratios of NO2:alpha 1PI of 400:1 and greater. Exposure of alpha 1PI to NO2 resulted in a 50% loss of immunoreactivity with either monoclonal or polyclonal antibodies in an enzyme-linked immunosorbent assay at molar ratios of NO2:alpha 1PI of 100:1 and greater. The results of parallel O-phthalaldehyde and bicinchoninic acid protein assays as well as amino acid analysis on control and NO2-exposed alpha 1PI suggested a reactivity of NO2 with lysine residues. Elastin and poly-L-lysine were labeled by reductive methylation of amino groups with [3H]HCHO prior to treatment with NO2 in aqueous solutions at physiological pH. NO2 exposure of elastin resulted in the solubilization of 84% of the associated radioactivity of which 79% was identified as [3H]methyllysine by amino acid analysis. After NO2 exposure of poly-L-[3H]lysine, gel filtration chromatography revealed that the 50,000 M(r) poly-L-[3H]lysine had been degraded to small peptides of 1-3000 M(r). Similarly, after NO2 exposure of unlabeled poly-L-arginine, gel filtration chromatography, and total peptide analysis revealed that the 47,500 M(r) peptide was also partially degraded to peptides. These results suggest that NO2 reacts with the epsilon-amino groups of Lys residues (primary amines) and with the amide nitrogen (secondary amines) of surface-exposed Lys and Arg residues in the peptide backbone to result in peptide bond cleavage. These findings are the first indication of NO2-mediated peptide degradation and provide additional data on the potential of NO2 to damage proteins vital to the function of the lung in an in vitro exposure system.

A 1H NMR probe for mobility in the reactive center loops of serpins: spin-echo studies of native and modified forms of ovalbumin and alpha 1-proteinase inhibitor

It has recently been proposed that the expression of inhibitory activity in serine protease inhibitors (serpins) is a function of the mobility of the extended alpha-helical reactive center loop [Stein, P.E., Leslie, A.G.W., Finch, J.T., Turnell, W.G., McLaughlin, P.J., & Carrell, R.W. (1990) Nature 347, 99-102]. We have employed solution 1H NMR methods, including the Carr-Purcell-Meiboom-Gill (CPMG) and Hahn spin-echo pulse sequences, to try to identify such regions by virtue of their anticipated longer T2 relaxation times in two of the best characterized members of the serpin superfamily, ovalbumin and alpha 1-proteinase inhibitor. The CPMG spectra of native ovalbumin reveal the presence of long-lived resonances from the methyl protons of alanine residues and the CH3 protons of leucine or valine residues as well as the acetyl and ring methine protons of the carbohydrate moieties. Following reaction of ovalbumin with subtilisin Carlsberg to generate plakalbumin [where excision from within the reactive center loop homologue of a hexa- or heptapeptide, with sequence (E)-A-G-V-D-A-A, occurs], its CPMG spectrum retained almost all of the originally present long-lived resonances. Concurrent with the retention of these mobile resonances in plakalbumin is the appearance of two additional resonances consistent with the formation of new C and N termini. On the basis of the proposed mobility of the reactive center loop, it had been expected that removal of the alanine-rich hexapeptide would result in loss of some or all of the long-lived alanine methyl resonances.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of refractory period after exercise and eucapnic voluntary hyperventilation challenge

We compared specific airway conductance (SGaw) and the FEV1 after repetitive exercise or repetitive eucapnic voluntary hyperventilation (EVH) challenges. Replicate challenges were matched in terms of inspired air conditions and minute ventilations (VE) in order to determine the degree of refractoriness after each type of challenge in patients with exercise-induced asthma. Ten patients exercised or hyperventilated dry, room temperature air at matched VE on two study days. When the patients FEV1 had returned to 90% of baseline or better, or at 3.75 h if FEV, had not returned to 90% of baseline, patients repeated the identical exercise or the EVH challenge. Minimum FEV1 values expressed as a percent of predicted FEV1 after the first and second exercise challenges were 52 +/- 16 and 58 +/- 17, respectively, which were statistically different (p less than 0.001; paired t test). Minimum FEV1 values after the first and second EVH challenges were 52 +/- 13 and 59 +/- 9% of predicted, respectively, which were also statistically different (p less than 0.01; paired t test). Seven of 10 subjects demonstrated higher SGaw values after the second exercise challenge compared with the first challenge, whereas eight of 10 subjects showed higher SGaw values after the second EVH challenge compared with the first challenge. Paired t test analysis indicated that percent protection, measured by FEV1, was similar after either type of challenge. We conclude that replicate exercise or EVH challenges with similarly matched inspired air conditions and VE induce similar degrees of refractoriness.(ABSTRACT TRUNCATED AT 250 WORDS)