Inclusion of shear rate effects in the kinetics of a discretized population balance model: Application to struvite precipitation

The effect of mixing in the modelling of processes based on mass transfer phenomena is commonly ignored in wastewater treatment industry. In this contribution, the effect of the average shear rate in the nucleation and growth rates of struvite is analyzed by combining experimental data with simulation results obtained with a previously presented mass-based discretized population balance model. According to the obtained results, the effect of the average shear rate is identifiable for the selected data and mechanisms. Therefore, it should be considered when a detailed modelling of the process is needed. Consequently, in this contribution, the average shear rate has been decoupled from the kinetic constants. In addition, kinetic rates where it is explicitly included as a power law function have been proposed. The exponents in these power law functions for the primary homogeneous nucleation and growth are 1.3 and 0.3, respectively. Considering shear rate effects allowed to see in the simulation outputs experimentally observed effects: a faster pH decay and smaller particle distribution for increasing mixing intensities.

Design and simulation of an imaging neutral particle analyzer for the ASDEX Upgrade tokamak

An Imaging Neutral Particle Analyzer (INPA) diagnostic has been designed for the ASDEX Upgrade (AUG) tokamak. The AUG INPA diagnostic will measure fast neutrals escaping the plasma after charge exchange reactions. The neutrals will be ionized by a 20 nm carbon foil and deflected toward a scintillator by the local magnetic field. The use of a neutral beam injector (NBI) as an active source of neutrals will provide radially resolved measurements, while the use of a scintillator as an active component will allow us to cover the whole plasma along the NBI line with unprecedented phase-space resolution (<12 keV and 8 cm) and a fast temporal response (up to 1 kHz with the high resolution acquisition system and above 100 kHz with the low resolution one), making it suitable to study localized fast-ion redistributions in phase space.

Double-Blind, Randomized Comparison of Systemic Continuous Infusion of 0.25 Versus 0.50 mg/kg/24 h of Alteplase over 3 to 7 Days for Treatment of Deep Venous Thrombosis in Heparinized Patients: Results of the European Thrombolysis with rt-PA in Venous Thrombosis (ETTT) Trial

Thirty-two patients with acute, proximal-vein thrombosis were treated with heparin and alteplase (0.25 versus 0.5 mg/kg/24 h during 3-7 days) in a randomized, double-blind, multicenter, European (ETTT) trial. The treatment resulted in a decrease of the venographic Marder’s score from 18 (6-25) to 13 (2-24) units (median, range) in Group I (0.25 mg/kg/24 h, n = 15, median decrease 3.0, p = 0.32) and from 17.5 (3-33) to 15.5 (0-27) in Group II (0.5 mg/kg/24 h, n = 16, median decrease 4.0, p = 0.23). Comparison of the sequential venograms could be performed in 14 cases of Group I and in 15 cases in Group II. A minority of patients showed substantial partial recanalization of the initially obstructed veins on the control venogram (one in each treatment group) and most of the control venograms showed

Thus, the results of the ETTT trial show that the used low dosages of alteplase administered intravenously over 3-7 days in heparinized patients cannot be recommended as a treatment for patients with deep venous thrombosis of lower limbs and/or pelvis. Further studies are needed to define a more suitable dosage regimen of alteplase in this indication.

Abstract 2667: In vitro properties and pre-clinical activity of PF-06801591, a high-affinity engineered anti-human PD-1

Monoclonal-antibody-based therapies targeting the immune checkpoint receptors have become the new standard of care in many cancers. Antibodies that specifically target programmed death receptor-1 (PD-1) or its cognate ligand, programmed death receptor ligand-1 (PD-L1), alone or in combination, have yielded clinical benefits and durable responses in patient subsets with various cancers (including metastatic melanoma, NSCLC, RCC, urothelial cancer, cHL and others). Here we report on the biophysical characteristics and non-clinical antagonistic activities of PF-06801591. PF-06801591 is a humanized anti-PD-1 antibody of human IgG4 isotype, that binds selectively and with similar potency to human and cynomolgus monkey PD-1 receptor (EC50 ~50 pM) and blocks its interaction with its cognate ligands PD-L1 and PD-L2 (IC50 &lt; 1 nM) with no detectable Fc effector function. The interaction of PF-06801591 to PD-1 rescues T cell suppression and exhaustion that translates into NFAT activation, IL-2 and IFN-gamma secretion and T cell proliferation both in vitro cultures and in vivo using an acute xeno GvHD model with human PBMC transfer. Binding of PF-068001591 to human and cynomolgus PD-1 is characterized by the formation of a very stable complex (T1/2 = 2 h) as measured by SPR at 37 C, resulting in high affinity (KD ~20 pM) as measured in solution by KinExA at 23 C. In addition, we explored therapeutic potential of anti-PD-1 in combination with other immunotherapy agents using surrogate antibodies in non-clinical tumor models. The data presented here support future development of PF-06801591 as a single agent or in combination with other immunotherapies.

Citation Format: Sawsan Youssef, Yasmina Abdiche, HoangKim Nguyen, Joyce Chou, Sherman Michael Chin, Cris Kamperschroer, Patricia A. Schneider, Eugenia Kraynov, Heike I. Krupka, Arvind Rajpal, John Lin. In vitro properties and pre-clinical activity of PF-06801591, a high-affinity engineered anti-human PD-1 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2667. doi:10.1158/1538-7445.AM2017-2667

Histone deacetylase inhibitors interrupt HSP90•RASGRP1 and HSP90•CRAF interactions to upregulate BIM and circumvent drug resistance in lymphoma cells

Histone deacetylase (HDAC) inhibitors, which are approved for the treatment of cutaneous T cell lymphoma and multiple myeloma, are undergoing evaluation in other lymphoid neoplasms. How they kill susceptible cells is incompletely understood. Here we show that trichostatin A, romidepsin, and panobinostat induce apoptosis across a panel of malignant B cell lines, including lines that are intrinsically resistant to bortezomib, etoposide, cytarabine, and BH3 mimetics. Further analysis traces the pro-apoptotic effects of HDAC inhibitors to increased acetylation of the chaperone heat shock protein 90 (HSP90), causing release and degradation of the HSP90 client proteins RASGRP1 and CRAF, which in turn leads to downregulation of mitogen activated protein kinase pathway signaling and upregulation of the pro-apoptotic BCL2 family member BIM in vitro and in vivo. Importantly, these pro-apoptotic effects are mimicked by RASGRP1 siRNA or HSP90 inhibition and reversed by overexpression of constitutively active MEK1 or siRNA-mediated downregulation of BIM. Collectively, these observations not only identify a new HSP90 client protein, RASGRP1, but also delineate a complete signaling pathway from HSP90 acetylation through RASGRP1 and CRAF degradation to BIM upregulation that contributes to selective cytotoxicity of HDAC inhibitors in lymphoid malignancies.

A new compact solid-state neutral particle analyser at ASDEX Upgrade: Setup and physics modeling

At ASDEX Upgrade (AUG), a new compact solid-state detector has been installed to measure the energy spectrum of fast neutrals based on the principle described by Shinohara et al. [Rev. Sci. Instrum. 75, 3640 (2004)]. The diagnostic relies on the usual charge exchange of supra-thermal fast-ions with neutrals in the plasma. Therefore, the measured energy spectra directly correspond to those of confined fast-ions with a pitch angle defined by the line of sight of the detector. Experiments in AUG showed the good signal to noise characteristics of the detector. It is energy calibrated and can measure energies of 40-200 keV with count rates of up to 140 kcps. The detector has an active view on one of the heating beams. The heating beam increases the neutral density locally; thereby, information about the central fast-ion velocity distribution is obtained. The measured fluxes are modeled with a newly developed module for the 3D Monte Carlo code F90FIDASIM [Geiger et al., Plasma Phys. Controlled Fusion 53, 65010 (2011)]. The modeling allows to distinguish between the active (beam) and passive contributions to the signal. Thereby, the birth profile of the measured fast neutrals can be reconstructed. This model reproduces the measured energy spectra with good accuracy when the passive contribution is taken into account.

MLN4924 induces Noxa upregulation in acute myelogenous leukemia and synergizes with Bcl-2 inhibitors

MLN4924 (pevonedistat), an inhibitor of the Nedd8 activating enzyme (NAE), has exhibited promising clinical activity in acute myelogenous leukemia (AML). Here we demonstrate that MLN4924 induces apoptosis in AML cell lines and clinical samples via a mechanism distinct from those observed in other malignancies. Inactivation of E3 cullin ring ligases (CRLs) through NAE inhibition causes accumulation of the CRL substrate c-Myc, which transactivates the PMAIP1 gene encoding Noxa, leading to increased Noxa protein, Bax and Bak activation, and subsequent apoptotic changes. Importantly, c-Myc knockdown diminishes Noxa induction; and Noxa siRNA diminishes MLN4924-induced killing. Because Noxa also neutralizes Mcl-1, an anti-apoptotic Bcl-2 paralog often upregulated in resistant AML, further experiments have examined the effect of combining MLN4924 with BH3 mimetics that target other anti-apoptotic proteins. In combination with ABT-199 or ABT-263 (navitoclax), MLN4924 exerts a synergistic cytotoxic effect. Collectively, these results provide new insight into MLN4924-induced engagement of the apoptotic machinery that could help guide further exploration of MLN4924 for AML.

Model-driven experimental evaluation of struvite nucleation, growth and aggregation kinetics

Nutrient stewardship is emerging as an issue of global importance, which will drive the development of nutrient recovery in the near to medium future. This will impact wastewater treatment practices, environmental protection, sustainable agriculture and global food security. A modelling framework for precipitation-based nutrient recovery systems has been developed, incorporating non-ideal solution thermodynamics, a dynamic mass balance and a dynamic population balance to track the development of the precipitating particles. The mechanisms of crystal nucleation and growth and, importantly, aggregation are considered. A novel approach to the population balance embeds the nucleation rate into the model, enabling direct regression of its kinetic parameters. The case study chosen for the modelling framework is that of struvite precipitation, given its wide interest and commercial promise as one possible nutrient recovery pathway. Power law kinetic parameters for nucleation, crystal growth and particle aggregation rates were regressed from an ensemble data set generated from 14 laboratory seeded batch experiments using synthetic solutions. These experiments were highly repeatable, giving confidence to the regressed parameter values. The model successfully describes the dynamic responses of solution pH, the evolving particle size distribution subject to nucleation, growth and aggregation effects and the aqueous magnesium concentration in the liquid phase. The proposed modelling framework could well be extended to other, more complex systems, leading to an improved understanding and commensurately greater confidence in the design, operation and optimisation of large-scale nutrient recovery processes from complex effluents.

Measuring T-cell responses against LCV and CMV in cynomolgus macaques using ELISPOT: potential application to non-clinical testing of immunomodulatory therapeutics

A number of immunomodulatory therapeutics increase the risk of disease associated with latent herpesviruses such as cytomegalovirus (CMV) and Epstein-Barr virus (EBV), a member of the lymphocryptovirus (LCV) family that infects humans. The diseases associated with loss of immunity to these viruses can have major impacts on patients as well as on the commercial viability of the immunomodulatory therapeutics. In an effort to develop non-clinical methods for measuring effects on anti-viral immunity, we have developed an interferon (IFN)-γ enzyme-linked immunosorbent spot (ELISPOT) assay to quantify the number of CMV or LCV-reactive T-cells in peripheral blood of cynomolgus macaques. After optimization of various parameters, the IFN-γ ELISPOT assay was characterized for specificity, intra-assay, monkey-to-monkey, and longitudinal variability and sensitivity to immunosuppression. The results show that nearly all animals have detectable responses against both CMV and LCV and responses were derived from T-cells specific to the virus of interest. Analyses of variability show assay reproducibility (≤23% CV), and that variability over time in anti-viral responses in individual animals (larger for LCV than for CMV) was ∼2-fold in most animals over a 3-month time period, which is predicted to allow for detection of drug-induced changes when using group sizes typical of non-clinical studies. In addition, the IFN-γ ELISPOT assay was capable of detecting decreases in the numbers of CMV and LCV reactive T-cells induced by immunosuppressive drugs in vitro. This assay may allow for non-clinical assessment of the effects of immunomodulatory therapeutics on anti-viral T-cell immunity in monkeys, and may help determine if therapeutics increase the risk of reactivating latent viral infections.

Assessments of critical flux in a pilot-scale membrane bioreactor

In this study, the influence of various parameters such as determination methods and step height and length of incremental flux on critical flux values were investigated. Experiments were carried out on a pilot-scale membrane bioreactor (MBR) treated municipal wastewater. Three of the five critical flux determination methods, such as flux linearity, 90% permeability and flux cycling conducted in this study, indicated a decline in critical flux values as the step height of incremental flux increased. However, the hysteresis method and the two-third (2/3) flux limitation method showed an increase and independence of critical flux to the step height of incremental flux, respectively. On the other hand, the step length of incremental flux had no obvious effect on critical flux values evaluated by all critical flux determination methods. Like critical flux, sustainable flux has negative relationship with the increase of step height but no influence of step length was found in this study.

How do I select cerebral protection devices today?

The establishment of cerebral protection has matured conceptually and clinically in recent years. We have accepted that some type of cerebral protection is desirable. We have some choices in whether to use filters, proximal occlusion, or proximal occlusion with reversed flow. There are anatomical and clinical factors that drive the choice of cerebral protection devices. Certain practical applications of cerebral protection technologies can be made based upon clinical experience. Making carotid artery stenting (CAS) safer is the key to a broader application of CAS as a treatment method and optimal selection of atherosclerosis new cerebral protection devices helps to achieve that goal.

2D electron cyclotron emission imaging at ASDEX Upgrade (invited)

The newly installed electron cyclotron emission imaging diagnostic on ASDEX Upgrade provides measurements of the 2D electron temperature dynamics with high spatial and temporal resolution. An overview of the technical and experimental properties of the system is presented. These properties are illustrated by the measurements of the edge localized mode and the reversed shear Alfvén eigenmode, showing both the advantage of having a two-dimensional (2D) measurement, as well as some of the limitations of electron cyclotron emission measurements. Furthermore, the application of singular value decomposition as a powerful tool for analyzing and filtering 2D data is presented.

TheIn VitroExpression and Secretion of Vascular Endothelial Growth Factor from Free and Alginate-Polyornithine Encapsulated Choroid Plexus Epithelium

The choroid plexus (CP) is a transplantable cell source secreting tropic and trophic factors for the treatment of brain and peripheral trauma characterized by cellular loss or dysfunction. Here we characterize the expression and secretion of vascular endothelial growth factor (VEGF) from neonatal porcine CP. Light and electron microscopy revealed that enzymatic digestion of the CP produced a preparation consisting primarily of epithelial cells without notable contaminating cells. Microarray analysis, quantitative polymerase chain reaction, and enzyme-linked immunosorbent assay were used to quantify the nuclear, cytoplasmic, and secretory compartmentalization of VEGF. In vitro, the kinetics of VEGF release were orderly, with stepwise increases in secretion over time. The secretory profile of VEGF from CP grown in configurations ranging from a simple monolayer to free-floating 3-dimensional clusters to clusters encapsulated within alginate-polyornithine microcapsules was similar. VEGF output was not affected notably when the cells were maintained in 90% stress medium or in other maintenance media devoid of serum proteins. Secreted VEGF was bioactive, as confirmed by demonstrating its continued ability to proliferate co-cultured human umbilical vascular endothelial cells. The robust ability of these cells to continue to secrete VEGF (and presumably other bioactive proteins) across a variety of dimensional configurations and medium types has implications for their use in clinical indications requiring novel and imaginative use of engineered ectopic transplant sites.

Intraperitoneal stability of alginate-polyornithine microcapsules in rats: an FTIR and SEM analysis

Alginate-polycation microcapsule systems have been used over decades as delivery vehicles for cell and protein therapy. These systems have been unpredictable across a range of indications with questions resulting around the inherent stability of the alginate polysaccharide and failure mode of the delivery system. The current study focuses on such a system using 5 different alginates, 2 of which are commercially purified, which are crosslinked by polyornithine. Capsules formed by frequency-generated droplet formation were studied in the peritoneal cavity of Long-Evans rats over the course of 3 months by morphometry, Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy of the surface. Individual capsule components were also investigated on FTIR and a relative stability index was generated by titration for comparison to explanted samples over time. Using these techniques, a distinct degradation pattern was noted and is compared between the 5 alginate sources.

Factors influencing ulcer healing in patients with combined arterial and venous insufficiency

PURPOSE

The purpose of this study was to determine the effectiveness of treatment of patients with combined arterial and venous insufficiency (CAVI), evaluate variables associated with successful ulcer healing, and better define criteria for interventional therapy.

STUDY DESIGN

We retrospectively reviewed the records of patients treated at four institutions from 1995 to 2000 with lower extremity ulcers and CAVI. Arterial disease was defined as an ankle/brachial index less than 0.9, absent pedal pulse, and at least one in-line arterial stenosis > 50% by arteriography. Venous insufficiency was defined as characteristic clinical findings and duplex findings of either reflux or thrombus in the deep or superficial system. Clinical, demographic, and hemodynamic parameters were statistically analyzed with multiple regression analysis and correlated with ulcer healing and limb salvage.

RESULTS

Fifty-nine patients with CAVI were treated for nonhealing ulcers that had been present from 1 to 39 months (mean, 6.4 months). All patients had edema. The mean ankle/brachial index was 0.55 (range, 0-0.86). Treatment included elastic compression and leg elevation in all patients and greater saphenous vein stripping in patients with superficial venous reflux. Fifty-two patients underwent arterial bypass grafting, three underwent an endarterectomy, one underwent superficial femoral artery percutaneous transluminal angioplasty, and three underwent primary below-knee amputation. For purposes of analysis, patients were divided into four groups according to the pattern of arterial and venous disease and the success of arterial reconstruction. Group 1 consisted of 22 patients with a patent arterial graft, superficial venous incompetence, and normal deep veins. Group 2 consisted of seven patients with a patent graft, superficial reflux, and deep venous reflux. Group 3 included 22 patients with a patent graft and deep venous thrombosis (DVT), and group 4 included eight patients with an occluded arterial graft. Follow-up ranged from 2 to 47 months (mean, 21.6 months). Forty-nine patients remained alive, and 10 died of unrelated causes. During follow-up, 48 of the 56 treated arteries remained patent and eight occluded. Thirty-four ulcers (58%) healed, 18 ulcers (31%) did not heal, and 7 patients (12%) required below-knee amputation for nonhealed ulcers and uncontrolled infection. No patient with graft occlusion was healed, and 12 ulcers persisted despite successful arterial reconstruction. Twenty-one (78%) of 27 patients undergoing greater saphenous vein stripping were healed, but none of these patients had DVT. The mean interval from bypass graft to healing was 7.9 months. Thirty-two (68%) of 46 patients without prior DVT were healed, whereas only two (15%) of 13 patients with prior DVT were healed, and this variable, in addition to graft patency, was the only factor statistically significant in predicting healing (P <.05).

CONCLUSIONS

Ulcers may develop anywhere on the calf or foot in patients with CAVI, and healing requires correction of arterial insufficiency. Patients with prior DVT are unlikely to heal, even with a patent bypass graft. Ulcer healing is a lengthy process and requires aggressive treatment of edema and infection, and successful arterial reconstruction. Patients with a prior DVT are unlikely to benefit from aggressive arterial or venous reconstruction.

Intraoperative superficial femoral artery balloon angioplasty and popliteal to distal bypass graft: an option for combined open and endovascular treatment of diabetic gangrene

PURPOSE

The purpose of this study was to evaluate the results of combining intraoperative balloon angioplasty (IBA) of the superficial femoral artery (SFA) with distal bypass graft originating from the popliteal artery as a method of lower extremity revascularization in diabetic patients with gangrene.

METHODS

Among 380 infrainguinal bypass grafts performed over a 6-year period, there were 110 reversed saphenous vein bypass grafts to the tibial or pedal arteries to treat diabetic patients with gangrene. Diffuse infrainguinal disease was treated with femoral-distal bypass graft (long; n = 46). Popliteal-distal bypass graft was performed when the inflow femoral artery was not significantly diseased (short; n = 52). Focal SFA stenosis and severe infrageniculate disease were treated with combined IBA of the SFA and distal bypass graft originating from the popliteal artery (combined; n = 12). Follow-up was performed with duplex scan surveillance of both the bypass graft and IBA sites. Treatment groups were compared with life-table analysis.

RESULTS

There were no perioperative graft failures or amputations. The perioperative mortality rate was 1% (1 of 110). The 2-year primary patency rates were similar in the three groups: 72% in the long bypass graft group, 82% in the short bypass graft group, and 76% in the combined group (P =.8, log-rank test). SFA IBA sites developed recurrent stenosis in two patients, at 7 and 48 months; both were detected with surveillance and treated with percutaneous transluminal balloon angioplasty. The overall 5-year rate of primary patency was 63%, secondary patency was 78%, limb salvage was 81%, and survival was 35%. There were no significant differences among the three treatment groups with respect to these outcomes.

CONCLUSION

Results with the combined procedure were similar to those achieved with either femoral-distal bypass graft or popliteal-distal bypass graft without SFA IBA. These data suggest that IBA of the inflow SFA may be combined with popliteal to distal bypass graft and that this technique is a reasonable alternative to longer, femoral-origin bypass graft in selected diabetic patients with gangrene.

Management of ischemic heel ulceration and gangrene: An evaluation of factors associated with successful healing

OBJECTIVE

The objective of this study was to determine the effectiveness of treatment of nonhealing heel ulcers and gangrene and to define those variables that are associated with success.

METHODS

A multi-institutional review was undertaken at four university or university-affiliated hospitals of all patients with wounds of the heel and arterial insufficiency, which was defined as absent pedal pulses and a decreased ankle/brachial index (ABI). Risk factors, hemodynamic parameters, and arteriographic findings were statistically analyzed to determine their effect on wound healing. Life-table analysis was used to assess graft patency and wound healing.

RESULTS

Ninety-one patients (57 men, 34 women) were treated for heel wounds that did not heal for 1 to 12 months (62% of nonhealing wounds, 3 months or longer). The mean preoperative ABI was 0.51, and 31% of wounds were infected. Of the patients, 55% had impaired renal function (Cr > 1.5), with 24% undergoing dialysis, 70% had diabetes, and 64% smoked cigarettes. Treatment was topical wound care for all patients and operative wound débridement in 50%. Infrainguinal bypass was performed for 81 patients, 4 had inflow procedures, 3 had superficial femoral artery percutaneous transluminal angioplasty, and 3 had primary below-knee amputation. Postoperatively, 85% of patients had in-line flow to the foot with at least a single patent vessel, 66% had a pedal pulse, and the mean ABI improved by 0.40, to 0.91. Follow-up ranged from 1 to 60 months (mean, 21 months), and 77 patients (85%) are currently alive. In 66 patients (73%), the wounds healed-all within 6 months (mean, 3 months). For 14 (16%) the wounds had not healed, and 11 patients (11%) underwent below-knee amputation. By life-table analysis, limb salvage was 86% at 3 years. During follow-up, 75 infrainguinal bypasses (91%) remained patent (3 secondarily) and 6 occluded, with primary assisted patency of 87% at 3 years. All wounds in patients with occluded grafts failed to heal. Variables found to be statistically significant in predicting healing included normal renal function (95% healed vs 55% nonhealed, P <.002), a palpable pedal pulse (85% healed vs 42%, P <.0015), a patent posterior tibial artery past the ankle (86% healed vs 57%, P <.02), and the number of patent tibial arteries after bypass to the ankle (P <.0001). Neither the ABI nor the presence of infection (defined as positive tissue cultures or the presence of osteomyelitis), diabetes, or other cardiovascular risk factors influenced the outcome.

CONCLUSIONS

Complete wound healing of ischemic heel ulcers or gangrene may require up to 6 months, and short-term graft patency is of minimal benefit. Successful arterial reconstruction, especially a patent posterior tibial artery after bypass, is effective in treating most heel ulcers or gangrene. Patients with impaired renal function are at increased risk for failure of treatment, but their wounds may successfully heal and they should not be denied revascularization procedures.

Lower extremity revascularization without contrast arteriography: a prospective study of operation based upon duplex mapping

This study prospectively assessed the results of lower extremity surgical revascularization, which was performed on the basis of duplex arterial mapping in selected patients without preoperative contrast arteriography. Criteria were developed for patient selection. Among 158 patients requiring surgery for lower extremity ischemia over a 24-month period, 24 (15%) were selected for operation without current preoperative arteriography. Aorto-iliac and infrainguinal duplex arterial mapping were performed in an laboratory that was accredited by the Intersocietal Commission for Accreditation of Vascular Laboratories. Indications for surgery were minor gangrene (11), rest pain (7), or claudication (6). Operations included femoropopliteal bypass (14), femoral endarterectomy (9) and femoral-femoral bypass (1). Mean length of stay was 4.5 +/- 2.0 days. Ankle-brachial index improved from 0.49 +/- 0.12 to 0.80 +/- 0.15 (P < 0.05). Primary patency was 91.7 +/- 9.4% and assisted primary patency was 100% at 18 months. There was no graft occlusion or limb loss. Mean follow-up was 16.7 +/- 7.0 months. These preliminary data support the safety and durability of duplex-guided lower extremity surgical revascularization without arteriography in selected cases. Success in a broader application of this approach requires the continuing development of patient selection criteria.

cDNA cloning and characterization of a human sperm antigen (SPAG6) with homology to the product of the Chlamydomonas PF16 locus

Serum from an infertile male with high-titer anti-sperm antibodies was used to identify a novel human sperm antigen by screening of a testis expression library. The clone, initially designated Repro-SA-1 (HUGO-approved symbol SPAG6), was found to encode a sequence highly enriched in testis. The deduced amino acid sequence of the full-length cDNA revealed striking homology to the product of the Chlamydomonas reinhardtii PF16 locus, which encodes a protein localized to the central pair of the flagellar axoneme. The human gene encodes 1.8- and 2.8-kb mRNAs highly expressed in testis but not in prostate, ovary, spleen, thymus, small intestine, colon, peripheral blood leukocytes, heart, brain, placenta, liver, muscle, kidney, and pancreas. The gene was mapped to chromosome 10p11.2-p12. Antibodies raised against SPAG6 sequences localized the protein to the tails of permeabilized human sperm. Both the Chlamydomonas protein and SPAG6 contain eight contiguous armadillo repeats, which place them in a family of proteins known to mediate protein-protein interactions. The cloning of the human homologue of the Chlamydomonas PF16 locus provides a new avenue to explore the role of the axoneme central pair in human sperm function.

Prevention of deep-vein thrombosis after total knee replacement. Randomised comparison between a low-molecular-weight heparin (nadroparin) and mechanical prophylaxis with a foot-pump system

The optimal regime of antithrombotic prophylaxis for patients undergoing total knee arthroplasty (TKA) has not been established. Many surgeons employ intermittent pneumatic compression while others use low-molecular-weight heparins (LMWH) which were primarily developed for total hip arthroplasty. We compared the efficacy and safety of these two techniques in a randomised study with blinded assessment of the endpoint by phlebography. We randomised 130 patients, scheduled for elective TKA, to receive one daily subcutaneous injection of nadroparin calcium (dosage adapted to body-weight) or continuous intermittent pneumatic compression of the foot by means of the arteriovenous impulse system. A total of 108 patients (60 in the LMWH group and 48 in the mechanical prophylaxis group) had phlebography eight to 12 days after surgery. Of the 47 with deep-vein thrombosis, 16 had received LMWH (26.7%, 95% CI 16.1 to 39.7) and 31, mechanical prophylaxis (64.6%, 95% CI 49.5 to 77.8). The difference between the two groups was highly significant (p < 0.001). Only one patient in the LMWH group had severe bleeding. We conclude that one daily subcutaneous injection of calcium nadroparin in a fixed, weight-adjusted dosage scheme is superior to intermittent pneumatic compression of the foot for thromboprophylaxis after TKA. The LMWH scheme was also safe.

Do aneurysms and pseudoaneurysms of the splenic artery require different surgical strategy?

BACKGROUND/AIMS

Although aneurysms and pseudoaneurysms of the splenic artery may result in life-threatening hemorrhage, their etiology, mode of presentation, and surgical strategy seem to differ. In an attempt to clarify their management, we reviewed our experience with aneurysms and pseudoaneurysms of the splenic artery.

METHODOLOGY

Between 1977 and 1997, 10 patients were operated on for true aneurysm and 6 for pseudoaneurysm of the splenic artery.

RESULTS

True aneurysms required resection because of rupture (n=7), size (n=2), and anticipated pregnancy (n=1). They remained asymptomatic unless rupture had occurred. Treatment consisted in aneurysmectomy with preservation of the pancreas and spleen when asymptomatic and required splenectomy or splenopancreatectomy when ruptured. Pseudoaneurysms were always associated with chronic pancreatitis and symptoms had lasted from several hours to 4 weeks prior to hospitalization. Caudal splenopancreatectomy was required in all but one case.

CONCLUSIONS

To contrast true aneurysms, pseudoaneurysms most often present with massive or intermittent bleeding. While the spleen and pancreas should be preserved when treating asymptomatic true aneurysms, management of ruptured aneurysms and pseudoaneurysms of the splenic artery usually consists of splenectomy or splenopancreatectomy.

Epidermoid cyst of the skull with nonpulsatile tinnitus

We report an intradiploic epidermoid cyst of the skull responsible for transverse sinus compression and presenting with nonpulsatile tinnitus. Plain films and CT both demonstrated the tumour. Cerebral angiography showed best the degree of narrowing of the right transverse sinus, accompanied with turbulent flow probably leading to tinnitus. MRI demonstrated accurately both the tumour and the dural sinus compression. The tumour was totally removed, cranioplasty was performed, and the patient was discharged free of symptoms.

Is routine preoperative aortoiliac arteriography necessary in the treatment of lower extremity ischemia?

PURPOSE

To determine whether preoperative aortoiliac arteriography can be replaced with noninvasive evaluation in the management of some patients with chronic lower extremity ischemia.

METHODS

Preoperative evaluation was performed on 184 ischemic limbs (119 patients) over 19 months by means of aortoiliac arteriography with runoff and noninvasive studies, which included common femoral artery duplex scanning, waveform and acceleration time (normal <140 msec), and aortoiliac duplex scanning. An algorithm was proposed for combining indirect (common femoral artery evaluation) and direct (aortoiliac evaluation) noninvasive studies to decrease the need for aortoiliac arteriography when possible.

RESULTS

Aortoiliac occlusive disease (> or =50% stenosis to occlusion) was present at arteriography in 48 limbs (30%), and there was no inflow disease in 114 (70%). Aortoiliac lesions were identified by means of noninvasive studies. The accuracies of femoral waveform, acceleration time, and aortoiliac duplex studies were 85%, 89% and 87%. The negative predictive values were 92%, 94% and 100%. The acceleration time results were not affected by runoff status but were significantly different for various categories of stenosis (p < 0.05). The algorithm was applied to the data obtained. When acceleration time and waveform were normal, 84 of 86 patients (98%) had no stenosis at arteriography. When aortoiliac duplex findings were normal, the arteriographic findings were normal in all examinations.

CONCLUSION

A combination of indirect and direct noninvasive studies can be used reliably to rule out clinically significant inflow occlusive disease and allows selective use of aortoiliac arteriography in patients with lower extremity ischemia.

Does stent placement improve the results of ineffective or complicated iliac artery angioplasty?

OBJECTIVE

This study was undertaken to determine the results and complications of stents placed for initially unsuccessful or complicated iliac percutaneous transluminal angioplasty (PTA), the effect of location (external iliac or common iliac) on outcome, and the influence of superficial femoral artery patency on benefit.

DESIGN

From 1992 through 1997, 350 patients underwent iliac artery PTA at the authors' institutions. Of this group, 88 patients (88 arteries) had one or more stents placed after PTA (140 stents in total) for residual stenosis or pressure gradient (63 patients), iliac dissection (12 patients), long-segment occlusion (10 patients), or recurrent stenosis (3 patients). Thirty patients required the placement of more than one stent. The indications for PTA in these 88 patients were claudication (48 patients) and limb-threatening ischemia (40 patients). Forty-seven patients had stents placed in the common iliac, 29 patients had stents placed in the external iliac, and 12 patients had stents placed in both. Seventy-one arteries (81%) were stenotic, and 17 (19%) were occluded before PTA. Sixty-six arteries were treated by interventional radiologists, 15 by a vascular surgeon, and 7 jointly.

MAIN OUTCOME MEASURE

Criteria for success included (1) increase of at least one clinical category of chronic limb ischemia from baseline or satisfactory wound healing, (2) maintenance of an ankle/brachial index increase of more than 0.10 above the preprocedure index, and (3) residual angiographic stenosis less than 25% and, for patients with pressure gradient measurements, a residual gradient less than 10 mm Hg.

RESULTS

Stent placement was accomplished in all 88 patients with 16 (18%) major complications. Mean follow-up was 17 months (range, 3 to 48 months). By life-table analysis, success was 75% at 1 year, 62% at 2 years, and 57% at 3 years. No cardiovascular risk factor or independent variable was statistically significant in predicting success. There was no difference in success rates for common iliac or external iliac lesions. Superficial femoral artery patency did not correlate with outcome.

CONCLUSIONS

Although stents can eliminate residual lesions and arterial dissection, these patients are likely to require adjuvant or subsequent procedures to attain clinical success. By controlling the PTA complication and treating the emergent problem, stents may allow for subsequent elective intervention.

Late pseudoaneurysm formation after repair of the descending aorta

We report a case of a 71-year-old hypertensive female patient presenting with haemoptysis and retrosternal pain from a leaking pseudo-aneurysm associated with a Dacron onlay patch used to repair a coarctation of the aorta 27 years earlier. This case illustrates a late and potentially fatal complication of this type of operation and describes a recent technique to reach the exact diagnosis and location of the aneurysm.

Stent-graft repair of mycotic superficial femoral artery aneurysm using a Palmaz stent and autologous saphenous vein

Developing endoluminal technology has permitted the management of selected aneurysms using stent-grafts, but the applicability and durability of these new devices has not yet been proven. Standard treatment of mycotic aneurysms generally requires arterial ligation, excision and debridement, and autologous or extraanatomic synthetic bypass. A saphenous vein-covered stent was used to exclude an expanding, mycotic, superficial femoral artery aneurysm in a critically ill patient. Although stent-graft exclusion was intended as a bridge to standard therapy, the mass resolved, the superficial femoral artery remains patent, and the patient is symptom-free at 1 year without further intervention. Additional experience is required to determine whether stent-grafts have a role in the management of mycotic aneurysms.

Long-term results of the Simon nitinol inferior vena cava filter

The aim of this study was to evaluate the clinical efficacy, mechanical stability, and safety of the Simon nitinol inferior vena cava filter (SNF). The SNF was inserted in 114 consecutive patients at two institutions for prophylaxis of pulmonary embolism (PE). Clinical follow-up data were obtained retrospectively on all patients, and 38 patients underwent a dedicated radiologic follow-up protocol consisting of abdominal radiography, Doppler sonography, and CT. There was no immediate complication following filter insertion. Fifty patients died, on average, 5.6 (1-23) months after filter insertion, and 64 patients were alive, on average, 27 (3-62) months after filter insertion. Recurrent pulmonary embolism was documented in 5 patients (4.4 %) but originated distal to the filter in 1 patient. Deep venous thrombosis (DVT) was documented in 5.3 %, thrombosis at the access site in 3.5 %, and thrombosis of the inferior vena cava in 3.5 %. The rate of thromboembolic complications was similar in patients who did receive long-term anticoagulation and in those who did not. Radiologic follow-up showed no filter migration after, on average, 32 (5-62) months. A CT examination showed that struts of the SNF had penetrated the vena cava in 95 %, and were in contact with adjacent organs in 76 %; however, there were no clinical symptoms attributable to the filter. Filters were in an eccentric position in 63 % and partial filter disruption was found in 16 %; however, this did not affect filter function. The rate of recurrent pulmonary embolism after insertion of the SNF is 2.4 % per patient per year. Regardless of long-term anticoagulation, the rate of caval thrombosis is acceptably low. Except for occasional access-site thrombosis, no other filter-related morbidity was observed.

Reoperation for recurrent chronic visceral ischemia

PURPOSE

Recurrent visceral ischemia after a failed visceral revascularization occurs in up to one third of patients, yet no comprehensive report has described the management of this problem. The purpose of this study was to examine the presentation, surgical management, and outcome of patients with recurrent visceral ischemia.

METHODS

Between 1959 and 1997, 109 patients underwent primary visceral revascularization at the University of California, San Francisco. Nineteen patients (17.4%) had recurrent visceral ischemia (12 chronic visceral ischemia, seven acute visceral ischemia). Fourteen additional patients with recurrent chronic visceral ischemia were referred after failed primary revascularization (two patients underwent multiple operations before referral). Thirty visceral reoperations were performed for recurrent visceral ischemia in 24 patients (10 patients with recurrence at University of California, San Francisco, 14 referred patients). Symptom-free and overall survival rates were determined by life table analysis.

RESULTS

Of seven patients (6.4%) who had recurrent acute visceral ischemia, six (85.7%) died of bowel infarction. Twelve patients (11%) had recurrent chronic visceral ischemia. Patients with recurrent chronic visceral ischemia received their diagnoses earlier and lost less weight than at their initial presentation (p = 0.004 and 0.001, respectively). Recurrent ischemia was associated with younger age, greater weight loss, and modification of surgical technique at the time of initial operation (p = 0.5, 0.009, and 0.02, respectively). For 20 (90.9%) of the 22 first reoperations, antegrade aortovisceral bypass (n = 10) or transaortic visceral endarterectomy (n = 10) was used. Multiple techniques (four antegrade bypass, two retrograde bypass, one endarterectomy, one anastomotic revision) were used in the eight second or third reoperations. Postoperative mortality and complication rates were 6.7% and 33.3%, respectively. Symptoms recurred in six of 22 patients (27.3%) after the first reoperation, three of whom were cured or improved after additional reoperations. The life table symptom-free survival rate after reoperation was 77.3% and 62.8% at 1 and 5 years, respectively. The life table overall survival rate after reoperation was 74.6% at 5 years.

CONCLUSIONS

Recurrent visceral ischemia is not uncommon after primary visceral revascularization. These results show that reoperation for recurrent chronic visceral ischemia can be accomplished safely and effectively with established revascularization techniques. Furthermore, after repeat visceral revascularization patients achieve durable relief of symptoms and have life expectancy rates comparable with those of patients who undergo primary visceral revascularization.

Implication of a cis-acting element in the cytoplasmic accumulation of unspliced Borna disease virus RNAs

Borna disease virus (BDV), the prototype of a new family within the order Mononegavirales, is unusual in its nuclear localization for replication and transcription and use of RNA splicing for gene expression. The BDV antigenome contains three transcription units and six major open reading frames. Multicistronic RNAs containing two introns are elaborated from the third transcription unit. Differential splicing of the two introns and cytoplasmic accumulation of the unspliced and partially spliced RNA are critical for the balanced expression of the putative matrix protein, glycoprotein, and polymerase. To investigate the mechanisms for cytoplasmic expression of unspliced and partially spliced BDV transcripts, the levels of these transcripts were measured in the cytoplasm of infected COS-7 cells and noninfected COS-7 cells transfected with plasmids containing 2.8-kb cDNA inserts representing either wild-type or mutant BDV RNA from the third transcription unit. Analysis of truncation mutations allowed the identification of a cis-acting element present within the 3' end of the BDV 2.8-kb transcript that facilitated the cytoplasmic accumulation of unspliced BDV transcripts through nucleocytoplasmic transport. The nucleocytoplasmic transport activity was not dependent on the presence of BDV proteins. Gel-shift assays revealed that the cis-acting element binds specifically to host cytoplasmic and nuclear proteins.

Should balloon angioplasty and stents have any role in operative intervention for lower extremity ischemia?

Balloon angioplasty has been combined with open vascular surgery to treat lower extremity ischemia due to multilevel occlusive disease. The purposes of this study were: (1) to compare staged and simultaneous approaches to determine the optimal method for combining endovascular and open techniques and; (2) to assess the role of stents in intraoperative balloon angioplasty. Among 274 patients undergoing lower extremity revascularization over 30 months, 38 (13.9%) required a combination of endovascular and open techniques; 17 were staged (endovascular followed at an interval by distal open surgery) and 21 were simultaneous (intraoperative balloon angioplasty with or without stent placement at the time of open surgery). Groups were similar with respect to demographics, lesions treated with endovascular intervention, incidence and location of stent placement, and results of surgery. Additional operating time required for intraoperative endovascular intervention was 41.0 +/- 30.7 min., fluoroscopic time was 3.9 +/- 2.4 min. and contrast administered was 58.8 +/- 28.1 ml. There was no perioperative mortality. Length of stay was longer in the staged than in the simultaneous group (p < 0.01). Cumulative combined primary patency at 1 year by life-table methods was 82 +/- 10% in the staged group and 83 +/- 9% in the simultaneous group (p = 0.79). Mean follow-up was 13 +/- 6 months. There is a role for balloon angioplasty and stent placement in operative revascularization of ischemic limbs in selected patients: patency was similar to that produced with the staged approach while the length of stay was shorter. Intraoperative balloon angioplasty is safe and effective and stents permit a measure of control in assuring an optimal intraoperative postangioplasty result.

Evidence for translation of the Borna disease virus G protein by leaky ribosomal scanning and ribosomal reinitiation

The Borna disease virus antigenome includes five major open reading frames (ORFs) which encode, from 5' to 3', the putative nucleoprotein (N), the phosphoprotein (P), the putative matrix protein (M), the major glycoprotein (G), and the RNA-dependent RNA polymerase (pol). Whereas the N and P ORFs are translated from monocistronic transcripts, the M, G, and pol ORFs are translated from polycistronic transcripts. Expression of the M, G, and pol ORFs is dependent upon differential splicing of two introns (intron 1, 94 nucleotides [nt]; intron 2, 1,294 nt). In vitro transcription-translation assays of wild-type and mutant sequences indicated that the G ORF is translated from an unspliced 2.8-kb RNA by leaky ribosomal scanning. Splicing of intron 1 enhances the translation of the G ORF by converting the M ORF into a 13-amino-acid minicistron, a structure that facilitates ribosomal reinitiation.

Ablation of hepatocellular carcinoma by percutaneous ethanol injection: imaging findings

Since PEI is a treatment based on imaging techniques, the radiologist should be familiar with the various findings that may be observed after PEI on US, CT, and MR images immediately after treatment and during later follow-up. Although US is well suited for performing PEI, contrast-enhanced CT currently is the most commonly used imaging method to evaluate the effect of PEI. Residual, nodular areas of contrast enhancement correlate well with residual tumor and warrant additional treatment. Although the findings on MR images obtained after PEI are more complex, MR imaging may be used as an alternative to CT.

Results of a multicenter study of the retrievable Tulip Vena Cava Filter: early clinical experience

PURPOSE

To evaluate clinically a new, retrievable vena caval filter in a multicenter study.

METHODS

The Tulip filter is a stainless steel half-basket that is suitable for antegrade or retrograde insertion via an 8.5 Fr introducer sheath. The filter can be retrieved via the jugular approach using an 11 Fr coaxial retrieval system. Forty-eight filters were implanted via the femoral approach and 38 via the jugular approach in 83 patients. Follow-up examinations (plain films, colorcoded duplex sonography) were performed up to 3 years after filter insertion (mean 136 days) in 75 patients. Twenty-seven patients were screened by colorcoded duplex sonography for insertion site thrombosis.

RESULTS

An appropriate filter position was achieved in all cases. Insertion problems occurred in 3 cases; these were not due to the filter design but to an imperfect prototype insertion mechanism that has now been modified (n = 2) or a manipulation error (n = 1). In 2 of these cases the filters were replaced percutaneously; 1 patient required venotomy for filter removal. No further complications due to filter insertion occurred. Two filters were used as temporary devices and were successfully removed after 6 and 11 days, respectively. There was 1 fatal recurrent pulmonary embolism (PE) and 2 non-fatal PE, 5 complete and 3 partial caval occlusions, and 3 caudal migrations of the filter. Insertion site venous thrombosis was not seen in the 27 patients monitored for this complication.

CONCLUSION

Precise placement of the Tulip filter is feasible by either access route and the device appears mechanically stable. Further observations are needed to confirm that safe filter removal is practical up to 10 days after its insertion.

Biochemical and functional analysis of the Borna disease virus G protein

The Borna disease virus (BDV) antigenome is comprised of five major open reading frames (ORFs). Products have been reported only for ORFs I, II, and III, encoding N (p40), P (p24/p23), and M (gp18), respectively. ORF IV predicts a 57-kDa protein with several potential glycosylation sites. Analysis of radiolabeled extracts from BDV-infected C6 cells and BHK-21 cells transfected with a Semliki Forest virus vector that contains ORF IV demonstrated the presence of a 94-kDa protein (G protein) which was sensitive to tunicamycin, endoglycosidase F/N-glycosidase, and endoglycosidase H but not to O-glycosidase. Sera from BDV-infected rats detected the G protein and had neutralization activity that was reduced following immunoadsorption with the G protein. Preincubation of cells with the G protein interfered with BDV infectivity. This effect was enhanced by treatment of the G protein with the exoglycosidase alpha-mannosidase and reduced after subsequent treatment with N-acetyl-beta-D-glucosaminidase. In concert these findings indicate that ORF IV encodes a 94-kDa N-linked glycoprotein with extensive high mannose- and/or hybrid-type oligosaccharide modifications. The presence of neutralization epitopes on the G protein and its capacity to interfere with infectivity suggest that the G protein is important for viral entry.

Management of arterial occlusive disease following radiation therapy

Clinically significant arterial occlusive disease developed in 26 patients at between 5 months and 44 years (mean(s.d.) 10.7(12.0) years) following radiation therapy. Therapeutic radiation was associated with lesions of the carotid artery (nine patients), subclavian-axillary arteries (seven) and the abdominal aorta and its branches (10). Clinical presentations included transient ischemic attack, stroke, vertebrobasilar insufficiency, carotid bruit, upper- or lower-extremity ischemia and renovascular hypertension. Surgery for cerebrovascular insufficiency included carotid endarterectomy with vein patch, interposition grafting or subclavian-to-carotid bypass. Carotid or subclavian-to-axillary bypass was performed for upper-extremity ischemia. A combination of endarterectomy and Dacron or saphenous vein grafts was used for infrarenal reconstruction. Tunnels were placed orthotopically. Musculocutaneous flaps assisted in healing selected wounds. Ureteral catheters were useful adjuncts in abdominal vascular reconstructions. There were no operative deaths, strokes or amputations. One patient had recurrent transient ischemic attacks following subclavian-to-carotid bypass. The mean(s.d.) postoperative follow-up was 48.1(39.6) months. Patients presenting with end-organ ischemia following radiation therapy can be managed successfully with aggressive surgical revascularization using a broad spectrum of reconstructive techniques.

The atypical strategies used for gene expression of Borna disease virus, a nonsegmented, negative-strand RNA virus

Borna disease virus (BDV) is a neurotropic agent that causes disturbances in movement and behavior in vertebrate host species ranging from birds to primates. Although the virus has not been isolated from human subjects, there is indirect evidence to suggest that humans with neuropsychiatric disorders may be infected with BDV. Recently, virus particles have been isolated and the viral genomic RNA has been cloned. This analysis revealed that BDV is a nonsegmented, negative-strand RNA virus. Unusual features such as RNA splicing, overlap of transcription units and transcription signals, as well as sequence dissimilarity for four of five major open reading frames to genes of other nonsegmented, negative-strand RNA viruses suggest that BDV is likely to represent a new taxon within the order Mononegavirales.

The remarkable coding strategy of borna disease virus: a new member of the nonsegmented negative strand RNA viruses

BDV uses a remarkably broad range of mechanisms to direct expression of its 8.9-kb genome. Although much remains to be elucidated, it is clear that BDV genome expression is modulated by the use of multiple strategies, including differential gene transcription, post-transcriptional modification, and translational efficiency. Further insights into the details of this multilevel system will be essential to understanding BDV biology, pathogenesis, and neurotropism.

Identification of signal sequences that control transcription of borna disease virus, a nonsegmented, negative-strand RNA virus

Borna disease virus (BDV) is a nonsegmented, negative-strand RNA virus that causes neurologic disorders in a wide range of animal species. Although the virus is unclassified, sequence analysis of the 8.9-kb viral genome has shown that it is related to rhabdoviruses and paramyxoviruses. We have mapped subgenomic RNAs of BDV strain He80-1 to the viral genome by determining the precise sequences at their 5' and 3' termini. This analysis showed that the genome contains three transcription initiation sites and four termination sites. A 14- to 16-nucleotide semiconserved sequence was present at the gene start sites and partially copied into the subgenomic RNAs. The termination sites contained a U-rich motif reminiscent of termination signals in rhabdoviruses and paramyxoviruses. In contrast to the genomes of other nonsegmented, negative-strand RNA viruses, the BDV genome lacked the typical configuration of termination signal, intergenic region, and initiation signal at the gene boundaries. Instead, transcription units and transcription signals frequently overlapped. These differences have implications for our understanding of the control of viral transcription and may relate to the low-level replication and persistence of BDV.

Subclavian artery catheterization: a new approach for endovascular procedures

PURPOSE

Percutaneous access to the arterial system for endovascular procedures is usually achieved through the femoral arteries. When femoral access is precluded, the axillary or brachial arteries serve as alternatives. Complications associated with the use of the latter arteries have led us to develop subclavian arterial catheterization.

METHODS AND RESULTS

From 1978 to 1993, 569 patients underwent angiography via the subclavian artery (> 99% left subclavian artery); 134 were studies of the aortic arch and brachiocephalic vessels; 435 studies involved the descending and abdominal aorta and its branches and runoff. Coronary arteriography was also feasible. Since 1986, 44 patients have undergone endovascular procedures: 33 percutaneous transluminal angioplasties of the visceral, iliac, femoral, and popliteal arteries and 11 thrombolytic procedures of aortofemoral graft limbs (n = 3) and femoral distal bypasses (n = 8) were performed. Complications (1.2%) included partial pneumothorax (n = 2), hemorrhage requiring operative control (n = 2), causalgia (n = 1) and embolization (n = 2).

CONCLUSIONS

Whenever percutaneous femoral catheterization cannot be achieved or an alternate access point is indicated, we select the subclavian approach as an alternative to axillary, brachial or translumbar access. It is safe, expeditious, and versatile for virtually all types of systemic and cardiac catheterization; it is also applicable to thrombolysis and balloon angioplasty.

Applicability of decision analysis to everyday clinical practice: a controlled feasibility trial

OBJECTIVE

To determine whether decision analysis is applicable to routine management of suspected pulmonary embolism in an emergency care setting.

DESIGN

Controlled feasibility trial.

SETTING

Emergency center of a university hospital.

PATIENTS

Outpatients (n = 84) admitted with clinical and scintigraphic evidence of pulmonary embolism.

INTERVENTIONS

Patients were treated either with the usual clinical work-up for pulmonary embolism (control group) or using a decision analysis model with three options: no action: angiography followed by treatment if positive; treatment without angiography.

RESULTS

All six senior residents in the decision analysis group agreed to fully participate for the 16 months of the study. Summarizing the decision analysis model in a graph was critical to obtain acceptance from all the physicians. Decision analysis (n = 43) and control (n = 41) patients underwent similar numbers of angiographies. However, angiographies for patients who had intermediate clinical probabilities of pulmonary embolism, between 25 and 75%, were more frequent in the decision analysis group (9/13 = 69%) than in the control group (7/20 = 35%). Agreement between clinical probability and lung-scan result was stronger in the decision analysis group.

CONCLUSIONS

Decision analysis was successfully used to manage all patients suspected of having pulmonary embolism admitted to an emergency center during the 16-month trial. There was no insuperable obstacle to acceptance of clinical decision analysis by the physicians. Decision analysis may have resulted in a better discrimination between low and intermediate clinical probabilities of pulmonary embolism.

RNA splicing in Borna disease virus, a nonsegmented, negative-strand RNA virus

Borna disease virus (BDV) is a nonsegmented, negative-strand RNA virus related to rhabdoviruses and paramyxoviruses. Unlike animal viruses of these two families, BDV transcribes RNAs in the nuclei of infected cells and produces high levels of transcripts containing multiple open reading frames. Previous Northern blot analysis of RNA from BDV-infected rat brain tissue has shown that two viral transcripts, a 6.1-kb RNA and a 1.5-kb RNA, lack regions that are internal to two otherwise identical transcripts, the 7.1-kb RNA and the 2.8-kb RNA, respectively (T. Briese, A. Schneemann, A. Lewis, Y. Park, S. Kim, H. Ludwig, and W. I. Lipkin, Proc. Natl. Acad. Sci. USA 91:4362-4366, 1994). To determine the precise location of this deletion, we performed reverse transcription PCR analysis using total RNA from BDV-infected rat brain tissue. This investigation resulted in the identification of two introns in the 7.1- and 2.8-kb RNAs, which can be alternatively spliced to yield additional RNA species, including the 6.1- and 1.5-kb RNAs. Transient transfection of COS-7 cells with a cDNA clone of the 2.8-kb RNA resulted in the production of both the 2.8-kb RNA and the 1.5-kb RNA, confirming the theory that the 2.8-kb RNA is a sufficient substrate for splicing in mammalian cells. Splicing has not previously been observed in nonsegmented, negative-strand RNA viruses and presumably serves as a mechanism by which expression of BDV proteins is regulated in infected cells.