Adjuvant immunotherapy for melanoma patients: progress and opportunities.

The majority of patients who are diagnosed with cutaneous melanoma are candidates for surgical resection and thus curable from their disease. However, the risk for a recurrence is high for many patients, including those with lymph node-negative melanoma, thus necessitating additional therapies beyond surgery. With the advent of anti-programmed cell death protein 1 (PD-1)-based immunotherapies, which are vastly more effective compared to previous standard-of-care treatments in the advanced setting, the landscape of adjuvant therapy has fundamentally changed in recent years. Anti-PD-1-based immune checkpoint inhibition therapy is now the standard of care for many patients with stage IIB or higher melanoma. Neoadjuvant approaches have demonstrated superior outcomes compared to adjuvant-alone therapy. However, a number of questions remain including treatment combinations such as combined anti-PD-1 + lymphocyte activation gene-3, optimal sequencing of therapies, and the use of predictive markers to further improve outcomes for patients with high-risk melanoma.

Pembrolizumab for advanced prostate adenocarcinoma: findings of the KEYNOTE-028 study.

Background: Patients with castration-resistant prostate cancer derive only modest clinical benefit from available therapies. Blockade of the inhibitory programmed death 1 (PD-1) receptor by monoclonal antibodies has been effective in several malignancies. Results from the prostate adenocarcinoma cohort of the nonrandomized phase Ib KEYNOTE-028 trial of pembrolizumab in advanced solid tumors are presented. Materials and methods: Key eligibility criteria included advanced prostate adenocarcinoma, unsuccessful standard therapy, measurable disease per Response Evaluation Criteria in Solid Tumors, version 1.1 (RECIST v1.1), and PD-1 ligand (PD-L1) expression in ≥1% of tumor or stromal cells. Patients received pembrolizumab 10 mg/kg every 2 weeks until disease progression or intolerable toxicity for up to 24 months. Primary end point was objective response rate (ORR) per RECIST v1.1 by investigator review. Results: Median patient age in this cohort (n = 23) was 65 years; 73.9% of patients received at least two prior therapies for metastatic disease. There were four confirmed partial responses, for an ORR of 17.4% [95% confidence interval (CI) 5.0%-38.8%]; 8 of 23 (34.8%) patients had stable disease. Median duration of response was 13.5 months. Median progression-free survival (PFS) and overall survival (OS) were 3.5 and 7.9 months, respectively; 6-month PFS and OS rates were 34.8% and 73.4%, respectively. One patient remained on treatment at data cutoff. After a median follow-up of 7.9 months, 14 (60.9%) patients experienced treatment-related adverse events (TRAEs), most commonly nausea (n = 3, 13.0%). Four (17.3%) experienced grade 3/4 TRAEs: grade 3 peripheral neuropathy, grade 3 asthenia, grade 3 fatigue, and grade 4 lipase increase. No pembrolizumab-related deaths or discontinuations occurred. Conclusion: Pembrolizumab resulted in durable objective response in a subset of patients with heavily pretreated, advanced PD-L1-positive prostate cancer, and its side effect profile was favorable. ClinicalTrials.gov Identifier: NCT02054806.

Study of η and η' Photoproduction at MAMI.

The reactions γp→ηp and γp→η^{'}p are measured from their thresholds up to the center-of-mass energy W=1.96 GeV with the tagged-photon facilities at the Mainz Microtron, MAMI. Differential cross sections are obtained with unprecedented statistical accuracy, providing fine energy binning and full production-angle coverage. A strong cusp is observed in the total cross section for η photoproduction at the energies in the vicinity of the η^{'} threshold, W=1896 MeV (E_{γ}=1447 MeV). Within the framework of a revised ηMAID isobar model, the cusp, in connection with a steep rise of the η^{'} total cross section from its threshold, can only be explained by a strong coupling of the poorly known N(1895)1/2^{-} state to both ηp and η^{'}p. Including the new high-accuracy results in the ηMAID fit to available η and η^{'} photoproduction data allows the determination of the N(1895)1/2^{-} properties.

Safety and antitumor activity of the anti-PD-1 antibody pembrolizumab in patients with recurrent carcinoma of the anal canal.

Background: Safety and efficacy of pembrolizumab, a humanized programmed death 1 monoclonal antibody, was assessed in KEYNOTE-028, a multicohort, phase Ib trial for patients with programmed death ligand 1 (PD-L1)-positive advanced solid tumors. We report results for the cohort of patients with advanced anal carcinoma. Patients and methods: Patients with PD-L1-positive tumors (≥1%) received intravenous pembrolizumab 10 mg/kg once every 2 weeks for up to 2 years or until confirmed progression or unacceptable toxicity. Response was assessed every 8 weeks for the first 6 months and every 12 weeks thereafter per Response Evaluation Criteria In Solid Tumors, version 1.1. Primary endpoints were safety and overall response rate per investigator review. Secondary endpoints included progression-free survival, overall survival, and response duration. Data cutoff date was 1 July 2015. Results: Of the 43 patients with advanced anal carcinoma evaluable for PD-L1 expression, 32 (74%) had PD-L1-positive tumors as assessed with the 22C3 prototype assay, of whom 25 were enrolled between April and September 2014. Sixteen patients (64%) experienced treatment-related adverse events; the most common ones were diarrhea and fatigue in four patients (16%) each and nausea in three patients (12%). There were no treatment-related deaths or discontinuations as of the data cutoff date. Among the 24 patients with squamous cell carcinoma histology, four had confirmed partial response, for an overall response rate of 17% [95% confidence interval (CI), 5%-37%) and 10 (42%) had confirmed stable disease, for a disease control rate of 58%. One additional patient with non-squamous histology had confirmed stable disease. Conclusion: In this population of patients with PD-L1-positive advanced squamous cell anal carcinoma, pembrolizumab demonstrated a manageable safety profile and encouraging antitumor activity. These data support further study of pembrolizumab for this patient population. ClinicalTrials.gov: NCT02054806.

Lacaziosis-like disease in Tursiops truncatus from Brazil: a histopathological and immunohistochemical approach

ABSTRACT: Cetacean lacaziosis-like disease or lobomycosis-like disease (LLD) is a chronic skin condition caused by a non-cultivable yeast of the order Onygenales, which also includes Lacazia loboi, as well as Paracoccidioides brasiliensis and P. lutzii, respectively responsible for lacaziosis and paracoccidioidomycosis in humans. Complete identification and phylogenetic classification of the LLD etiological agent still needs to be elucidated, but preliminary phylogenetic analyses have shown a closer relationship of the LLD agent to Paracoccidioides spp. than to L. loboi. Cases of LLD in South American cetaceans based on photographic identification have been reported; however, to date, only 3 histologically confirmed cases of LLD have been described. We evaluated multiple tissue samples from 4 Tursiops truncatus stranded in the states of Santa Catarina (n = 3) and Rio Grande do Sul (n = 1), southern Brazil. Macroscopically, all animals presented lesions consistent with LLD. Hematoxylin-eosin, periodic acid-Schiff, Grocott's methenamine silver, and Mayer's mucicarmin stains were used for histological evaluation. Microscopically, numerous refractile yeasts (4-9 µm in diameter) were observed in skin samples (4/4), and for the first time in dolphins, also in a skeletal muscle abscess (1/4). Immunohistochemistry using anti-P. brasiliensis glycoprotein gp43 as a primary antibody, which is known to cross-react with L. loboi and the LLD agent, was performed and results were positive in all 4 cases. We describe 3 new cases of LLD in cetaceans based on histopathology and immunohistochemistry. This is the first report of LLD in the muscle of cetaceans.

Measurement of the transverse target and beam-target asymmetries in η meson photoproduction at MAMI.

We present new data for the transverse target asymmetry T and the very first data for the beam-target asymmetry F in the γ[over →]p[over →]→ηp reaction up to a center-of-mass energy of W=1.9 GeV. The data were obtained with the Crystal-Ball/TAPS detector setup at the Glasgow tagged photon facility of the Mainz Microtron MAMI. All existing model predictions fail to reproduce the new data indicating a significant impact on our understanding of the underlying dynamics of η meson photoproduction. The peculiar nodal structure observed in existing T data close to threshold is not confirmed.

[Immediate results of combined treatment for soft tissue sarcomas including intraoperative radiation therapy].

Nowadays the most popular and justified, from oncological positions, method of treatment for soft tissue sarcomas is a combined approach with the use of conservative surgery followed by postoperative radiation therapy. In this regard, intraoperative radiation therapy (IORT) in a single dose of 10-20 Gy is a method that optimizes the role of radiation therapy in treatment of this pathology allowing precise localization of radiation zone within the "tumor bed", thereby minimizing damage of normal tissues and critical organs. The aim of the study was to investigate the effect of IORT on the frequency and structure of post-operative complications. Testing group (n = 49) was compared to the group without IORT (n = 57) and group with only surgery (n = 171). According to the study it was not obtained statistically significant differences in the incidence of postoperative complications in the groups (p = 0,57), not marked influence on the structure of post-operative complications.

[Results of combined treatment with intraoperative radial therapy of soft tissue sarcoma].

The intraoperative radiation therapy (IORT) in combined therapy of soft tissue sarcoma in a single dose 10-20 Gy is the method, which can optimize the role of radiation therapy in treatment of this nosology. This method allows exact localization of the irradiation zone in the frames of "tumor bed", thereby minimizing the damage of normal tissues and critical organs. The aim of the study was the influence of IORT on the rate and structure of postoperative complications and long-term results of treatment in the group under study (n = 49) in comparison with the group of combined treatment without IORT (n = 57) and the group of surgical treatment. No statistically reliable difference in the rate of postoperative complications in groups (p = 0.57) was obtained and there was no influence on the structure of postoperative complications. At the same time the statistically reliable increase of general survival rates (p = 0.025) and the survival without relapse in the main group (p < 0.025) were obtained. Thus, the application of IORT in combined treatment of soft tissue sarcomas showed the satisfactory profile of "surgical safety", provided the reliable increase of general survival rates and rates without relapse.

[Long-term results of combined treatment of soft tissue sarcoma with the use of intraoperative radiotherapy].

This retrospective study of long-term results of combined treatment of soft tissue sarcoma with the use of intraoperative radiotherapy (IORT) included 171 patients. Controls received adjuvant distant gamma-therapy (n = 57) or surgical treatment (n = 171). IORT significantly improved 5 year general (p = 0.025) and relapse-free (p < 0.025) survival rate and the same parameters in patients with a tumour larger than 5 cm (p = 0.0001). The intergroup difference regardless of tumour differentiation was insignificant (p =0.33), but survival rate tended to decrease in patients with moderately and weakly differentiated sarcomas (G2-3). It is concluded that combined treatment with IORT may be used as an alternative method for the treatment of moderately and weakly differentiated sarcomas.

Molecular sexing of unusually large numbers of Spheniscus magellanicus (Spheniscidae) washed ashore along the Brazilian coast in 2008.

There have been few studies on Magellanic penguins (Spheniscus magellanicus). In 2008, these penguins washed ashore along the Brazilian coast in unusually high numbers, some reaching as far as northeast Brazil. As Magellanic penguins show little sexual dimorphism, sex determination by morphological features is not accurate. Here, we tested a molecular procedure for sexing specimens of S. magellanicus washed ashore along the coasts of Sergipe, Rio de Janeiro and Rio Grande do Sul in 2008, comparing the sex ratio between these localities. Tissue samples were collected from 135 dead, beached specimens. We carried out total genomic DNA extraction and CHD-Z/CHD-W gene amplification by PCR using P2 and P8 primers. Amplicons were separated by 12% acrylamide gel electrophoresis. We found a greater proportion of females (70%). Sex could be determined because females have two intronic regions of CHD gene of different size in the sex chromosomes, visualized as two bands on the gel (380 and 400 bp approximately), while males have only one (400 bp). Therefore, this method proved to be effective and sensitive for sex determination of S. magellanicus individuals. Data on sex ratios are useful for understanding the dynamics and ecology of Magellanic penguin populations.

In cirrhotic patients reduced muscle strength is unrelated to muscle capacity for ATP turnover suggesting a central limitation.

BACKGROUND AND AIMS: We investigated whether in patients with liver cirrhosis reduced muscle strength is related to dysfunction of muscle mitochondria. METHODS: The mitochondrial respiratory capacity of the tibial anterior muscle was evaluated in seven patients and eight healthy control subjects by 31P nuclear magnetic resonance spectroscopy (31PMRS) to express ATP turnover in vivo and by respirometry of permeabilized fibres from the same muscle to express the in vitro capacity for oxygen consumption. RESULTS: Maximal voluntary contraction force for plantar extension was low in the patients (46% of the control value; P < 0.05), but neither the capacity for mitochondrial ATP synthesis, V(max-ATP) (0.38 ± 0.26 vs. 0.50 ± 0.07 mM s(-1) ; P = 0.13) nor the in vitro VO(2max) (0.52 ± 0.21 vs. 0.48 ± 0.21 µmol O2 (min g wet wt.)(-1) P = 0.25) were lowered correspondingly. Also, the activity of citrate synthesis and the respiratory chain complexes II and IV were similar in patients and controls. However during the contractions, the contribution to initial anaerobic ATP production from glycolysis relative to that from PCr was reduced in the patients (0.73 ± 0.22 vs. 0.99 ± 0.09; P < 0.01). CONCLUSIONS: These results demonstrate that the markedly lower capacity for force generation in patients with liver cirrhosis is unrelated to their capacity for muscle ATP turnover, but the attenuated initial acceleration of anaerobic glycolysis suggests that these patients could be affected by a central limitation to force generation.

["Diabetes in Germany"(DIG) study. A prospective 4-year-follow-up study on the quality of treatment for type 2 diabetes in daily practice]. / "Diabetes in Germany" (DIG)-Studie. Prospektive 4-Jahres-Studie zur Therapiequalität bei Typ-2-Diabetes in der Praxis

INTRODUCTION: The efficacy of a multifactorial intervention with antihypertensive drugs, statins and acetylsalicylic acid was shown in the STENO 2 trial of diabetic patients with microalbuminuria. But how good is clinical practice in Germany? The DIG (Diabetes in Germany) study was an prospective survey, analysing the quality of risk factor control and treatment patterns of type 2 diabetics over 4 years between 2002 and 2007. METHODS: A total of 4020 type 2 diabetics (aged 35 - 80 years) were recruited by 238 physicians across Germany. Their medical history, risk factor profile and clinical data were recorded. The quality of control of diabetes, hypertension or hyperlipidemia and the use of aspirin were assessed in 2914 patients at baseline and after 3,7 years. RESULTS: The mean HbA (1c) value was 6,98 % at baseline and 7,03 at the study end. 42,9 % at the beginning vs. 36,9 % at follow-up had HbA (1c) values above the target level of 6,5 %. Mean blood pressure was 139,3/80.0 compared with 137,3/79.9 mm Hg (p < 0,01), while 24,1 % and 27,0 %, respectively had values above the target level. Mean LDL-cholesterol levels were 3,23 mmol/l and 2,93 mmol/l, respectively, but only 23,2 % and 30,4 % of patients, respectively, reached target levels. There was a significant increase in the use of antihypertensive drugs, statins and acetylsalicylic acid over the four-year period. CONCLUSION: Type 2 diabetics in Germany received an acceptable level of treatment for hyperglycaemia, but still more than 60 % of the patients have HbA (1c) values higher than 6,5 %. There are serious deficits in the management of hypertension, hypercholesterolemia and the use of aspirin. Because intensive, multifactorial care of type 2 diabetics leads to reduced rates of death and cardiovascular disorders, these results indicate that the early and meticulous implementation of current treatment guidelines remains a major challenge.

The influence of L-ascorbic acid on the antibacterial-toxic activity of aflatoxins on adsorbent layer.

AIMS: To substantiate the role of formaldehyde (HCHO) and its reaction products in the mechanism of the antibacterial-toxic effect of aflatoxins B1 (AFB1), B2, G1 and G2. MATERIALS AND RESULTS: Toxins were separated by overpressured layer chromatography, which was followed by biological evaluation directly on the adsorbent layer (BioArena system with Pseudomonas savastanoi pv. phaseolicola indicator bacteria). HCHO formed in this system was eliminated with exogenously added capturer molecule dimedone and L-ascorbic acid (AA) and measured as the adduct of dimedone and HCHO. The amount of HCHO was higher in the toxin-containing spots, particularly in the most toxic AFB1 spot, compared to a toxinless background. 0.1 mg ml(-1)AA augmented, 0.2 mg ml(-1) dimedone or 0.5 and 1 mg ml(-1) AA reduced the antibacterial effect of all four aflatoxins. CONCLUSION: The antibacterial-toxic effect of aflatoxins may be mediated by HCHO (and/or its reaction products) generated from bound HCHO forms in the bacterial cells. Basis of antibacterial-toxic activity of the four aflatoxins appears the same. SIGNIFICANCE AND IMPACT OF THE STUDY: Involvement of HCHO as a key molecule in the effect of aflatoxins indicates a totally new mechanism of action of these dangerous molecules. The BioArena system is useful to dissect the mode of action of antimicrobial compounds from different biological matrices.

Opposite effect of Cu(II) and Se(IV) ions on the antibacterial-toxic action of mycotoxins.

The effect of Se(IV) and Cu(II) ions on the antibacterial activity of aflatoxins and ochratoxin A (mycotoxins) was studied in BioArena as a complex bioautographic system. In the presence of 0.23 and 0.46 mg/100 mL Se(IV) the inhibition zones of mycotoxins were decreased, however, lower concentration (0.046 mg/100 mL) increased the antibacterial effect of aflatoxin B1. Cu(II) (1.53 mg/100 mL) enhanced the toxicity of mycotoxins. The results supported the possible role of formaldehyde and its reaction products (e.g. 1O2, O3) in the antibacterial-toxic action of mycotoxins. Cu(II) can probably generate and mobilise the formaldehyde molecules and so it could increase the toxicity with its potential reaction products. It is possible that the enzymatic or spontaneous methylation of Se(IV) takes place through formaldehyde, which may cause partial formaldehyde depletion in the system. The enhanced antibacterial effect at low concentration Se(IV) is overlapping with the often experienced prooxidant effect in cases of natural antioxidants.

Comparison of the prevalence of the metabolic syndrome by WHO, AHA/NHLBI, and IDF definitions in a German population with type 2 diabetes: the Diabetes in Germany (DIG) Study.

UNLABELLED: This study investigated the prevalence of the metabolic syndrome (MetS) in a German population with type 2 diabetes (T2DM) using the three definitions for MetS according to WHO 1999, AHA/NHLBI 2005, and IDF 2005 criteria. Four-thousand and twenty participants as a cross section of daily practice of diabetes care in Germany (238 unselected sites) were included in the Diabetes in Germany (DIG) study. INCLUSION CRITERIA: T2DM and age between 35-80 years. EXCLUSION CRITERIA: major cardiovascular event < 3 months before entry, NYHA-IV, macroproteinuria, and cancer < 5 years before entry. The components of MetS were measured following a standard protocol for anthropometric and laboratory control. The average diabetes duration was 8.4 years and HbA (1C) 7.0%. The prevalence of MetS by WHO criteria was 26.1%, by AHA/NHLBI 79.3%, and by IDF 82.6%. The degree of agreement (kappa statistic) was kappa = 0.69 between AHA/NHLBI and IDF definitions, but only 0.12 for WHO VS. IDF, and 0.17 for WHO vs. AHA/NHLBI. The frequency of central obesity by WHO was 50.9%, by AHA/NHLBI 72.9%, and by IDF 92.0% and for hypertension 29.3%, 92.6%, and 92.6%, respectively. However, the frequencies of lipid components by the three definitions were in the same range (57.8%, 59.5%, 59.5%). In this representative German sample of patients with type 2 diabetes, the prevalence of MetS was very highly independent of using the IDF or AHA/NHLBI definition. Females were significantly more affected than males. The distinctly lower prevalence delineated from WHO criteria is due to low frequency of central obesity and hypertension as consequence of higher cutoff limits for these components used in the WHO definition.

Hepatic lactate uptake versus leg lactate output during exercise in humans.

The exponential rise in blood lactate with exercise intensity may be influenced by hepatic lactate uptake. We compared muscle-derived lactate to the hepatic elimination during 2 h prolonged cycling (62 +/- 4% of maximal O(2) uptake, (.)Vo(2max)) followed by incremental exercise in seven healthy men. Hepatic blood flow was assessed by indocyanine green dye elimination and leg blood flow by thermodilution. During prolonged exercise, the hepatic glucose output was lower than the leg glucose uptake (3.8 +/- 0.5 vs. 6.5 +/- 0.6 mmol/min; mean +/- SE) and at an arterial lactate of 2.0 +/- 0.2 mM, the leg lactate output of 3.0 +/- 1.8 mmol/min was about fourfold higher than the hepatic lactate uptake (0.7 +/- 0.3 mmol/min). During incremental exercise, the hepatic glucose output was about one-third of the leg glucose uptake (2.0 +/- 0.4 vs. 6.2 +/- 1.3 mmol/min) and the arterial lactate reached 6.0 +/- 1.1 mM because the leg lactate output of 8.9 +/- 2.7 mmol/min was markedly higher than the lactate taken up by the liver (1.1 +/- 0.6 mmol/min). Compared with prolonged exercise, the hepatic lactate uptake increased during incremental exercise, but the relative hepatic lactate uptake decreased to about one-tenth of the lactate released by the legs. This drop in relative hepatic lactate extraction may contribute to the increase in arterial lactate during intense exercise.

[Limb salvage for the diabetic foot - disease management program]. / Extremitätenerhalt für den diabetischen Fuss - Disease-Management-Programm.

OBJECTIVE: Lower-extremity amputation (LEA) is a common complication among patients with diabetes. This study tests the effects of a structured disease management program for the diabetic foot (DF) aiming to reduce the number of LEA. DESIGN, METHODS: In a prospective study design we investigate patients with DF in a system of outpatient treatment, acute in-patient care and rehabilitative treatment. Subjects were recruited since January 1(st), 2000, with the latest admission being December 31, 2004. All study participants undergo a five-year follow-up observation period. The University of Texas Wound Classification System (UT) of foot ulcers serves as basis of the documentation and analysis. We evaluated numbers of LEA, rates of ulcer healing and underlying forms of peripheral vascular disease. RESULTS: We report the results of the first patient group completing the two-year follow-up examination. In 2000, 102 subjects with new foot ulcers were consecutively included into the study. 68.6% were men, the mean age of the study population was 68.1 +/- 11.4 years and the mean diabetes duration was 19.4 +/- 10.3 years. After two years, 68 patients can still be examined. Altogether, 22 patients (21.6%) died, and 12 (11.8%) dropped out for various reasons. At the point of discharge from the clinics 35.3% of the ulcers had healed and another 44.1% were in UT grade 1. After two years, a complete healing could still be determined with 51 patients (50.0% of the cohort of the original 102 patients, or 75.0% of the subjects reaching the two-year follow-up). 10 subjects (9.8% or 14.5%) were in the UT grade 1. Eight diabetics underwent major amputation (MA) during the two-year examination period (amputation rate 7.8%). CONCLUSIONS: The primary objective of the study, a significant reduction of MA with DF patients, has been achieved. The ulcer healing rates are comparable to the reports of leading centers.

Identification of virulence-associated genes of Pseudomonas viridiflava activated during infection by use of a novel IVET promoter probing plasmid.

Analysis of virulence mechanisms of plant pathogens is often limited by the lack of genetic tools that can be used to identify genes that are preferentially expressed during their interactions with plants. In the present study, we used the newly constructed IVET (in vivo expression technique) plasmid pIviGK and the corresponding antibiotic resistance-based selection method to identify genes that encode pathogenicity factors of the soft rot-causing bacterium Pseudomonas viridiflava. These included pel, the gene encoding pectate lyase, which is responsible for the development of soft rot symptoms. We have also isolated and characterized the gene mviNpv encoding a putative novel membrane associated virulence factor of P. viridiflava. A mutation in mviNpv was shown to influence motility as well as virulence of P. viridiflava. The mviNpv gene is expressed to a moderate level in LB media and its expression increases under inducing conditions as was shown by measuring in planta expression dynamics of the fused gfp reporter gene.

[The red tympanic membrane]. / Das rote Trommelfell.

An otoscopic red tympanic membrane is for the examiner a challenge. A short directed history, as well as a few functional examinations associated to a systematic otoscopy allow in most cases to make the otological diagnosis. The differential diagnosis for a red tympanic membrane is very large, including malformations, traumas, infections, and even tumors and other degenerative pathologies. The first diagnosis to think about is an infectious disease. On the other side, there are rare pathologies which, even for experienced examiners are quite seldom.

Effect of atrial overdrive pacing on pulmonary vein focal discharge in patients with atrial fibrillation.

AIMS: Recently, it has been shown that atrial fibrillation may be caused by spontaneously discharging foci located predominantly in the pulmonary veins. However, the effect of atrial overdrive pacing on these pulmonary vein foci has not been studied. METHODS AND RESULTS: In 58 patients with drug refractory paroxysmal or persistent atrial fibrillation we performed radiofrequency catheter ablation of arrhythmogenic triggers inside the pulmonary veins and/or an ostial pulmonary vein isolation with conventional mapping and ablation technology. Continuous bigeminal pattern of discharge from one or more arrhythmogenic pulmonary veins was recorded in 14 patients. Atrial overdrive pacing resulted in suppression of pulmonary vein 'focus' activity in all patients. The longest mean atrial pacing cycle length resulting in overdrive suppression was 587+/-114 ms. Independent of pacing rate and duration, bigeminal pulmonary vein focus activity reemerged 2.5+/-3.7s after cessation of pacing. Overdrive suppression of the pulmonary vein focus was incomplete in 9 pacing attempts, and resulted in induction of atrial fibrillation from the same vein in 3 of 31 pacing manoeuvres. At 2 years follow-up 79% of these patients were free of atrial fibrillation, 55% without antiarrhythmic drugs, 24% on previously ineffective antiarrhythmic drug therapy. CONCLUSION: Stable pulmonary vein 'focus' activity in patients with atrial fibrillation can be suppressed by atrial overdrive pacing. However, 'proarrhythmic' effects of atrial overdrive pacing, such as induction of atrial fibrillation, were also seen.