Ultrasound Aspects and Recanalization Rates in Patients with Lower-Limb Deep Venous Thrombosis Treated with Rivaroxaban.

BACKGROUND: In this article, we report the ultrasound aspects and recanalization rates of patients with deep venous thrombosis (DVT) in the lower limbs treated with the rivaroxaban, focusing on the recanalization rate and the ultrasonographic aspects. METHODS: This was a prospective and consecutive cohort study of patients admitted with DVT who were submitted to treatment with rivaroxaban for 6 months at the Division of Vascular and Endovascular Surgery, Hospital do Servidor Público Estadual, São Paulo, Brazil, between March 2016 and July 2018. RESULTS: Fifty-one patients with DVT were admitted to the Vascular Surgery Department and received rivaroxaban for 6 months. The follow-up time was 360 days. Analyses were performed at 180 and 360 days. The rate of total venous recanalization at 360 days was 76.4% (39 patients). The incidence of partial venous recanalization was 23.5% (12 patients). At the first month, 11 patients (21.7%) continued with total occlusion of the vein, with 4 patients (6.5%) with no residual thrombi. However, at 6 months, only 2 patients (2.2%) continued with total occlusion of the vein, with 26 patients (47.8%) with no residual thrombi. At 12 months, there were 39 patients (76.4%) with no residual thrombi. Univariate and multivariate logistic regression identified the following factors related to total venous recanalization: the absence of popliteal vein reflux (odds ratio [OR], 0.386; P = 0.007), no residual thrombi (OR, 3.213; P = 0.008), femoropopliteal clot length at 1 month (OR, 3.021; P = 0.016), femoropopliteal clot length at 6 months (OR, 2.234; P = 0.008). The incidence of post-thrombotic syndrome (PTS) at 12 months was 8.3%. CONCLUSIONS: In this study, patients who received oral rivaroxaban displayed satisfactory total vein recanalization rate after 6 months and 12 months. The factors associated with better total recanalization rates were the absence of popliteal vein reflux, the absence of residual thrombi in the veins, femoropopliteal clot length at 1 month (OR, 3.021; P = 0.016), and femoropopliteal clot length at 6 months (OR, 2.234; P = 0.008). Moreover, the incidence of PTS at 12 months was 8.3%.

Single- versus multiple-stage catheter-directed thrombolysis for acute iliofemoral deep venous thrombosis does not have an impact on iliac vein stent length or patency rates.

BACKGROUND: Incomplete venous thrombolysis and residual nonstented iliac vein disease are known predictors of recurrent deep venous thrombosis (DVT). Controversy exists as to whether the number of thrombolysis sessions affects total stent treatment length or stent patency. The goal of this study was to evaluate the outcomes of patients who underwent single vs multiple catheter-directed lysis sessions with regard to stent extent and patency. METHODS: Consecutive patients who underwent thrombolysis and stenting for acute iliofemoral DVT between 2007 and 2018 were identified and divided into two groups on the basis of the number of treatments performed (one vs multiple sessions). Operative notes and venograms were reviewed to determine the number of lytic sessions performed and stent information, including size, location, total number, and length treated. End points included total stent length, 30-day and long-term patency, and post-thrombotic syndrome (Villalta score ≥5). The χ2 comparisons, logistic regression, and survival analysis were used to determine outcomes. RESULTS: There were 79 patients who underwent lysis and stenting (6 bilateral interventions; mean age, 45.9 ± 17 years; 48 female). Ten patients (12 limbs) underwent single-stage treatment with pharmacomechanical thrombolysis, and the remaining 69 (73 limbs) had two to four operating room sessions combining pharmacomechanical and catheter-directed thrombolysis. Patients who underwent a single-stage procedure were older and more likely to have a malignant disease. These patients received less tissue plasminogen activator compared with the multiple-stage group (17.2 ± 2.2 mg vs 27.6 ± 11.6 mg; P = .008). Average stent length was 8.8 ± 5.2 cm for the single-stage group vs 9.2 ± 4.6 cm for the multiple-stage group (P = .764). Patients who underwent a single-stage procedure had no difference in average length of stay from that of patients who underwent multiple sessions (8.5 days vs 5.9 days; P = .269). The overall 30-day rethrombosis rate was 7.3%. Two-year patency was 72.2% and 74.7% for the single and multiple stages, respectively (P = .909). The major predictors for loss of primary patency were previous DVT (hazard ratio [HR], 5.99; P = .020) and incomplete lysis (HR, 5.39; P = .014) but not number of procedures (HR, 0.957; P = .966). The overall post-thrombotic syndrome rate was 28.4% at 5 years and was also not associated with the number of treatment sessions. CONCLUSIONS: Single- vs multiple-stage thrombolysis for DVT is not associated with a difference in extent of stent coverage. Patency rates remain high for iliac stenting irrespective of the number of lytic sessions, provided lysis is complete and the diseased segments are appropriately stented.

Comparison of the recanalization rate and postthrombotic syndrome in patients with deep venous thrombosis treated with rivaroxaban or warfarin.

BACKGROUND: In this article, we report the outcomes of patients with deep venous thrombosis in the lower limbs treated with the oral anticoagulant rivaroxaban or warfarin, focusing on the recanalization rate (measured with duplex ultrasound) and the incidence of postthrombotic syndrome. METHODS: This was a prospective, consecutive, randomized, blind cohort study of patients admitted with deep venous thrombosis to the Division of Vascular and Endovascular Surgery, Hospital do Servidor Público Estadual, São Paulo, Brazil, between March 2016 and July 2018. The patients were randomized into 2 groups and treated with oral anticoagulation for 6 months: either rivaroxaban (group 1) or warfarin (group 2). The study was registered at clinicaltrials.gov under NCT 02704598. RESULTS: Eighty-eight patients with deep venous thrombosis were admitted to the Vascular Surgery Department and randomized into the 2 groups. The follow-up time was 360 days. Analyses were performed at 180 and 360 days. Four patients were excluded from the study during follow-up because of a diagnosis of ovarian cancer (1 patient), head and neck cancer (1 patient), lung cancer (1 patient), and stomach cancer (1 patient). Therefore, 84 patients were evaluated: 46 patients in group 1 and 38 in group 2. The incidence of postthrombotic syndrome was 17.9% (15 cases) in the total cohort, but was significantly higher in group 2 (11 cases, 28.9%) than in group 1 (4 cases, 8.7%; P < .001; odds ratio, 4.278). The rate of total venous recanalization at 360 days was 40.5% (34 patients) in the total cohort, but was significantly higher in group 1 (35 patients, 76.1%) than in group 2 (5 patients, 13.2%; P < .001). The incidence of partial venous recanalization was 46.4% and was significantly higher in group 2 (28 patients, 73.7%) than in group 1 (11 patients, 23.9%; P = .016). Five patients in the total cohort (6%) showed no venous recanalization, all of them in group 2 (P = .016). CONCLUSION: In this study, patients who received oral rivaroxaban displayed a lower incidence of postthrombotic syndrome and a better total vein recanalization rate after 6 and 12 months than patients who received warfarin.

Dual platelet antiaggregation therapy after myocardial revascularization surgery.

Coronary artery bypass graft (CABG) is a consolidated treatment in patients with coronary artery disease (CAD) for both symptom control and improvement of prognosis. The patency of venous grafts is still the most vulnerable point of the surgical treatment since it presents a high prevalence of occlusion both in the immediate postoperative period and in the long-term follow-up. Aspirin plays a well-established role in this setting, and for a long time, clopidogrel use has been restricted to patients allergic to aspirin. Recently, subgroup analyses of studies with different anti-platelet therapies have shown reduced mortality and cardiovascular events in patients on dual anti-platelet antiplatelet therapy (DAPT) undergoing CABG, although such studies have not been designed to evaluate this patient profile. However, there is still an insufficient number of randomized studies using DAPT in this context, resulting in a disagreement between the European and American cardiology societies guidelines regarding their indication and generating doubts in clinical practice.

Dual platelet antiaggregation therapy after myocardial revascularization surgery

SUMMARY Coronary artery bypass graft (CABG) is a consolidated treatment in patients with coronary artery disease (CAD) for both symptom control and improvement of prognosis. The patency of venous grafts is still the most vulnerable point of the surgical treatment since it presents a high prevalence of occlusion both in the immediate postoperative period and in the long-term follow-up. Aspirin plays a well-established role in this setting, and for a long time, clopidogrel use has been restricted to patients allergic to aspirin. Recently, subgroup analyses of studies with different anti-platelet therapies have shown reduced mortality and cardiovascular events in patients on dual anti-platelet antiplatelet therapy (DAPT) undergoing CABG, although such studies have not been designed to evaluate this patient profile. However, there is still an insufficient number of randomized studies using DAPT in this context, resulting in a disagreement between the European and American cardiology societies guidelines regarding their indication and generating doubts in clinical practice.

RESUMO A cirurgia de revascularização miocárdica (CRM) é tratamento fundamental em pacientes com doença arterial coronariana (DAC) tanto para controle de sintomas quanto para melhora do prognóstico. A patência dos enxertos venosos ainda hoje é o ponto mais vulnerável do tratamento cirúrgico, por apresentar alta prevalência de oclusão tanto no pós-operatório imediato como no seguimento em longo prazo. A aspirina tem papel bem estabelecido neste cenário e, por muito tempo, o uso do clopidogrel ficou restrito a pacientes alérgicos a aspirina. Recentemente, análises de subgrupos de estudos com diferentes terapias antiplaquetárias demonstraram redução de mortalidade e eventos cardiovasculares em pacientes em uso de dupla antiagregação plaquetária (Dapt) submetidos à CRM, ainda que tais estudos não tenham sido desenhados para avaliar este perfil de pacientes. Contudo, há ainda uma quantidade insuficiente de estudos randomizados com uso de Dapt nesse contexto, resultando em uma discordância entre as diretrizes europeia e americana de cardiologia quanto à sua indicação e gerando dúvidas na prática clínica.

Use of intravenous alprostadil in patients with severe critical ischemia of the lower limbs.

OBJECTIVES: To determine the indications for the use, potential benefits, and adverse reactions of alprostadil in a group of Colombian patients. METHODS: A retrospective cross-sectional study was conducted in patients diagnosed with critical limb ischemia who received alprostadil in five hospitals in Colombia between September 2011 and July 2017. We reviewed the clinical records of each patient to obtain the sociodemographic and pharmacological variables, clinical stages, complications, comorbidities, reported effectiveness and adverse reactions. RESULTS: Sixty-one patients treated with alprostadil were evaluated; 50.8% of patients were men, and the average age of 72.5 ± 10.7 years. A total of 86.9% of patients were hypertensive, and 65.6% were diabetic. A total of 77.0% presented ulceration, and this condition was considered as a diabetic foot in 57.4% of patients. A total of 81.9% of patients were classified as Fontaine stage 4; 60.7% received therapy as initially indicated, with an average of 19 days of alprostadil use. Regarding the therapy results, 58.0% of the patients with ulcers or trophic lesions showed improvement, 86.2% showed improvement of pain, and the limb was saved in 72.1% of patients. CONCLUSIONS: Critical limb ischemia was presented by patients with advanced age and high cardiovascular risk who were treated during severe and advanced stages where therapeutic options are limited. Treatment with alprostadil achieved satisfactory results with improvement in ulcers, pain, and limb salvage rates in this series of patients.

Occluded Tunneled Venous Catheter in Hemodialysis Patients: Risk Factors and Efficacy of Alteplase.

Thrombosis of tunneled central venous catheters (CVC) in hemodialysis (HD) patients is common and it can lead to the elimination of vascular sites. This study aimed to evaluate the incidence of thrombotic obstruction of tunneled CVC in HD patients and the efficacy of occlusion treatment with alteplase use, and identify factors associated with thrombotic occlusion. It was a prospective cohort study performed in two centers which evaluated the diagnosis and treatment of thrombotic occlusion of CVC in HD patients for 24 consecutive months. The catheter occlusion was defined as the difficulty infusing or withdrawing fluid from their paths. Alteplase dose was infused to fill the lumen of the occluded catheter and remained for 50 min. As there was no obstruction of the catheter, the procedure was repeated. Three hundred and thirty-nine CVC in 247 patients were evaluated and followed, totalling 67,244 CVC-days. One hundred fifty-seven patients had only one CVC, 88 patients had two CVC during the study, and two patients had three CVC. The median age was 58 (47-66) years, patients were predominantly men (54%), with diabetic nephropathy as the main cause of chronic kidney disease (44%), the internal jugular vein as the main site of implantation (82%), and duration of dialysis before CVC implantation of 119 (41.5 to 585.5) days. Eight hundred and fifteen occlusion episodes were diagnosed (12 episodes/1000 CVC-days), with primary success with alteplase in 596 episodes (77%) and secondary in 81 cases (10%). In 99 episodes (13%), success was not achieved after the second dose of alteplase. Two hundred and thirty CVC were removed during the study and the removal causes were arteriovenous fistula use in 88 patients (38.3%), infectious and mechanical complications in 89 (38.7%) and 21 (9.1%), respectively, and others (transplantation, transfer, or death) in 32 patients (13.9%). Adverse effects were also not observed. In the multivariate analysis, we identified the greatest number of days with CVC (OR = 1.02, CI = 1.01-1.04, P = 0.004), the presence of diabetes (OR = 1.560, CI = 1.351-1.894, P = 0.015), and exit site infection (ESI) (OR = 1.567 CI = 1347-1926, P = 0.023) as factors associated with obstruction. Thrombotic occlusion showed frequent mechanical complication in CVC of HD patients. We observed 12 episodes of obstruction per 1000 CVC-days, with a high success rate after alteplase use (87%). In the multivariate analysis, the time with CVC, the presence of diabetes, and ESI were identified as variables associated with thrombotic obstruction.

Effective use of alteplase for occluded tunneled venous catheter in hemodialysis patients.

Despite their propensity for significant infectious and mechanical complications, tunneled central venous catheters (CVCs) have become a common means of vascular access in the world for patients requiring chronic hemodialysis for end-stage renal disease. The objective of this study was to explore if cryopreserved solutions of the thrombolytic agent alteplase could be used as an effective, safe, and economically reasonable alternative in hemodialysis patients with occluded tunneled CVC. Patients requiring chronic hemodialysis and presenting with occluded tunneled CVC received a sufficient volume of the alteplase solution to fill the occluded catheter. To make alteplase economically feasible, it was diluted to 1-mg/mL aliquots and they were stored at -20°C until use. Eighty-one patients accounting for 179 attempted clearances were assessable for efficacy. One hundred forty-seven (82.1%) of the 179 catheter clearance attempts resulted in successful catheter clearance after one dose. Twenty-seven (15.1%) of all occluded CVCs were successful after two doses whereas five (2.8%) were not. No adverse events were reported. Cryopreserved 1-mg/mL aliquots of alteplase are safe and effective in the clearance of occluded CVC for hemodialysis patients.

Effect of mutalysin II on vascular recanalization after thrombosis induction in the ear of the hairless mice model.

Mutalysin II (mut-II) is an alpha-fibrinogenase isolated from Lachesis muta muta (bushmaster) snake venom. The enzyme lyses fibrin clots in vitro, and this activity does not depend on plasminogen activation. The aim of this study was to assess by intravital microscopy the effect of Mutalysin II on the recanalization of microvessels after thrombus induction in the ears of hairless mice. Photochemical thrombus formation was induced after i.v. injection of 5% fluorescein isothiocyanate labelled dextran (FITC-dextran) followed by mercury light exposure of individual microvessels of the ear of five anesthetized animals. Video playback analysis of intravital microscopy images of the ear microcirculation permitted us to measure blood flow velocity (microm/s) under control conditions (before thrombus formation) in the ear microvessels. Thirty minutes after thrombus formation (blood flow velocity stopped completely), each animal (n=5) was infused with Mutalysin II (2.0 mg/kg, i.v.). All animals treated with Mutalysin II showed evident thrombolysis after approximately 12 min, followed by recanalization. A separate group of mice (n=5) which received urokinase type-plasminogen activator (u-PA, 250 U/mouse, i.v.) showed blood flow restoration within the same interval (12 min). These in vivo data suggest that Mutalysin II has the potential to be an effective thrombolytic agent.

Effect of tamoxifen on arterial microvascular anastomosis.

Breast reconstruction after cancer treatment is based on the circulation of pedicle and microvascular flaps. This article aimed to verify the effect of tamoxifen (TMX) pretreatment in arterial anastomosis in rats. Twenty female Wistar rats were equally divided into two groups. TMX (0.3 mg/kg) was administered to the experimental group for 2 weeks orally. After this period, the right femoral artery was sectioned and a terminoterminal anastomosis performed. The same procedure was done in the control group, except that the animals received the vehicle without TMX. One week later, the femoral arteries were inspected for flow through the anastomosis, and the vessel near it was sent to light microscopic examination. It was observed mild vasculite in both groups. The intimal thickness and total vessel wall in the TMX-treated group was significantly higher. A real thrombotic effect upon the arterial vascular anastomosis was not observed, eventhough, TMX induced intimal hyperplasia.

Aterogênese em artéria ilíaca comum de suínos submetidos à homocisteinemia induzida pela ingestão de metionina / Atherogenesis in swine iliac artery with homocystinemia induced by methionine ingestion

OBJETIVO: Avaliar os efeitos da homocisteinemia induzida na artéria ilíaca de suínos. MATERIAL E MÉTODO: Realizou-se estudo experimental comparativo em dois grupos homogêneos de sete suínos da raça Macau, com peso entre 20 e 30 kg durante 30 dias. Os animais foram divididos em dois grupos, sendo um deles alimentado com metionina adicionada à dieta por um período de 4 semanas. Foram colhidas amostras de sangue para a dosagem de colesterol, triglicerídeos, HDL e homocisteína. Os animais foram submetidos à arteriografia para avaliação da perviedade das artérias ilíacas e, posteriormente, sacrificados. As artérias ilíacas foram enviadas para análise histológica. RESULTADOS: Os animais sobreviveram ao experimento, e não houve alterações significativas nos níveis de colesterol total, triglicerídeos e HDL nos dois grupos. O exame microscópico do grupo-controle não apresentou alterações patológicas e foi semelhante em todas as preparações examinadas. No grupo da dieta com metionina, as placas eram formadas por macrófagos espumosos, mas não foram observadas células musculares lisas, cristais de colesterol ou células inflamatórias. A túnica média apresentava-se com lâmina elástica interna íntegra. No grupo-controle, não houve alteração nos níveis de homocisteína durante o experimento. No grupo-metionina, houve aumento dos níveis séricos da homocisteína, com valor médio de 59,80 µmol/l após 30 dias de dieta rica em metionina. CONCLUSÃO: A homocisteinemia induzida pela metionina causa aterogênese nas artérias ilíacas de suínos.

Efficacy and safety of oral sirolimus to inhibit in-stent intimal hyperplasia.

Sirolimus systemic administration has shown marked inhibition of neointimal hyperplasia (NIH) after balloon angioplasty in porcine models. In this pilot study, we tested the hypothesis that oral sirolimus is safe and effective to inhibit in-stent NIH and therefore to prevent and treat in-stent restenosis (ISR). Twelve patients (18 lesions) with high risk for ISR, including 8 ISR lesions, were admitted. One day before the procedure, patients were given a 15 mg loading dose of oral sirolimus, followed by 5 mg daily for 28 days, with weekly whole blood level measurements. The daily dose was adjusted to keep the concentration at 10-15 ng/ml. Sirolimus was well tolerated by all patients but one, who died at the end of the third week of treatment. The 4- and 8-month follow-up revealed an angiographic late loss of 0.40 +/- 0.24 and 0.67 +/- 0.45 mm (P < 0.01), respectively. At the same time points, the intravascular ultrasound in in-stent relative volumetric obstruction was 14.4% +/- 9.1% and 23.2% +/- 10.1% (P < 0.01), respectively. At 24-month clinical follow-up, adverse events were one (8.3%) death, two (11.1%) target lesion, and four (22.2%) target vessel revascularizations. In conclusion, in this small group of high-risk ISR patients, oral sirolimus inhibited NIH and therefore may be an effective strategy for the prevention and treatment of ISR.

Papaverine prolongs patency of peripheral arterial catheters in neonates.

OBJECTIVE: To test the hypothesis that the continuous infusion of papaverine-containing solutions in peripheral arterial catheters would decrease the catheter failure rate and increase the functional duration of the catheter in neonates. STUDY DESIGN: In a prospective, randomized, placebo-controlled, masked trial, 82 catheters were placed in 70 neonates in the papaverine group and 98 catheters were placed in 71 neonates in the placebo group. RESULTS: The catheters in the papaverine group remained functional for a significantly longer duration than those in the placebo group. The median (25th%, 75th%) time before catheter failure was 16.6 (9.5, 24.3) days in the papaverine group and 12 days (6.1, 18.2) in the placebo group ( P = .023; Cox proportional hazards model). There was no significant difference in the incidence of intraventricular hemorrhage (IVH) between groups, and there was no evidence of hepatic toxicity. CONCLUSIONS: The continuous infusion of papaverine-containing fluids prolongs the patency of peripheral arterial catheters in neonates. In this small number of infants, we found no difference in the incidence of IVH or hepatic toxicity.

Recombinant tissue plasminogen activator in the treatment of central venous catheter occlusion in children.

Tissue plasminogen activator was used to treat 228 children with 320 central venous catheter (CVC) occlusion events. Patency was restored in 91% of CVCs after 1 to 3 treatments, with no adverse events. Tissue plasminogen activator is effective in restoring patency to occluded CVCs and is a viable alternative to CVC removal or urokinase treatment.

Sustained suppression of neointimal proliferation by sirolimus-eluting stents: one-year angiographic and intravascular ultrasound follow-up.

BACKGROUND: We have previously reported a virtual absence of neointimal hyperplasia 4 months after implantation of sirolimus-eluting stents. The aim of the present investigation was to determine whether these results are sustained over a period of 1 year. METHODS AND RESULTS: Forty-five patients with de novo coronary disease were successfully treated with the implantation of a single sirolimus-eluting Bx VELOCITY stent in São Paulo, Brazil (n=30, 15 fast release [group I, GI] and 15 slow release [GII]) and Rotterdam, The Netherlands (15 slow release, GIII). Angiographic and volumetric intravascular ultrasound (IVUS) follow-up was obtained at 4 and 12 months (GI and GII) and 6 months (GIII). In-stent minimal lumen diameter and percent diameter stenosis remained essentially unchanged in all groups (at 12 months, GI and GII; at 6 months, GIII). Follow-up in-lesion minimal lumen diameter was 2.28 mm (GIII), 2.32 mm (GI), and 2.48 mm (GII). No patient approached the >/=50% diameter stenosis at 1 year by angiography or IVUS assessment, and no edge restenosis was observed. Neointimal hyperplasia, as detected by IVUS, was virtually absent at 6 months (2+/-5% obstruction volume, GIII) and at 12 months (GI=2+/-5% and GII=2+/-3%). CONCLUSIONS: This study demonstrates a sustained suppression of neointimal proliferation by sirolimus-eluting Bx VELOCITY stents 1 year after implantation.

Kinins in the pathogenesis of human airway diseases.

1. Over the past decade, data have been obtained showing that the potent vasoactive peptides known as kinins are generated in airway secretions during a variety of inflammatory airway diseases, such as allergic rhinitis, viral rhinitis and asthma. Kinin generation involves release of tissue kallikrein from airway glands, as well as increased vascular permeability and activation of the plasma kallikrein system. The activity of generated kinins is regulated by a number of cell-associated, as well as plasma-derived, peptidases. 2. Kinins can induce relevant symptoms when applied to the surface of human airways. Moreover, the effects of kinins are more pronounced in the setting of chronic inflammation. In the upper airways, kinins can stimulate glandular secretion, increase vascular permeability and stimulate sensory nerves to produce symptoms of nasal obstruction, rhinorrhea, and nasal and throat irritation. In the lower airways of asthmatics, kinins are potent inducers of edema and cause bronchoconstriction by a mechanism that involves, at least in part, neural reflexes. 3. Definitive proof of a role for kinins in human airway diseases has been difficult to obtain because receptor antagonists that have been available to date have suffered from problems of potency or duration of action. Studies are continuing, however, to understand the mechanisms by which kinins exert their effects and to delineate their importance in airway diseases.

PAF antagonists do not modify IgE antibody production in mice.

The effect of selective PAF antagonists on the in vivo production of IgE antibodies was investigated. The anti-ovalbumin IgE antibody content was estimated by passive cutaneous anaphylactic reaction (PCA) in the plasma of Balb/c mice 10 days after immunization with ovalbumin and alum. The PAF antagonists, BN 52021 (5 mg/kg, ip), BN 50730 (20 mg/kg, po), WEB 2086 (2 mg/kg, ip) and WEB 2170 (5 mg/kg, ip) were administered 1 h before immunization and twice a day for 8 days thereafter. The effect of the antagonists on the PAF-induced vasopermeability was also assayed. In the immunized mice the level of antiovalbumin IgE antibody, estimated by PCA titer, was 1/640. The treatment with the PAF antagonists did not change this level. At the concentrations employed, the antagonists BN 50730, WEB 2086 and WEB 2170 significantly reduced the PAF-induced vascular permeability. These results suggest that PAF does not seem to have a relevant effect on the production of IgE antibodies in vivo in the system used in the present study.

Paf antagonists do not modify IgE antibody production in mice

The effect of selective PAF antagonists on the in vivo production of IgE antibodies was investigated. The anti-ovalbumin IgE antibody content was estimated by passive cutaneous anaphylactic reaction (PCA) in the plasma of Balb/c mice 10 days after immunization with ovalbumin and alum. The PAF antagonists, BN 52021 (5 mg/kg, ip), BN 50730(20 mg/kg, ip) BN 50730 (20 mg/kg, po), WEB 2086 (2 mg/kg, ip) and WEB 2170 (5 mg/kg, ip) were administered 1 h before immunization and twice a day for 8 days thereafter. The effect of the antagonists on the PAF-induced vasopermeability was also assayed. In the immunized mice the level of antiovalbumin IgE antibody, estimated by PCA titer, was 1/640. The treatment with the PAF antagonists did not change this level. At the concentrations employed, the antagonists BN 50730, WEB 2086 and WEB 2170 significantly reduced the PAF-induced vascular permeability. These results suggest that PAF does not seem to have a relevant effect on the production of IgE antibodies in vivo in the system used in the present study