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With the emerging use of wireless applications, the radio frequency community continues to need to design miniature, lightweight, and inexpensive antennas that can easily be integrated into small-scale communication systems. According to today's global wireless applications, Circularly Polarized Microstrip Antennas (CPMAs) offer more flexibility for handheld and portable wireless devices due to their insensitivity to the orientation of the device and multipath effects. These antennas are best suited for wireless communications such as WLAN, RFID and GNSS applications. The objective of this work is to design a miniature microstrip antenna with circular polarization, intended for wireless applications such as positioning systems by GNSS satellites. The design will be done in two stages. First, we will design a patch antenna operating at the 1.575 GHz frequency using the technique of asymmetric circular slots to obtain circular polarization. The second step consists in miniaturizing the dimensions of this antenna thanks to a network of square-shaped SRR resonators, inserted at the level of the ground plane of the structure. The result is an antenna of compact size and well suited to the intended application. Simulation results are discussed and compared in terms of reflection coefficient, bandwidths, radiation patterns and axial ratio.

In a context of increasing communication standards, the need for the miniaturization of antennas facilitating their integration is increasing more and more. This paper has been devoted to the use of lefthand materials (LHM) for reducing the size of circular microstrip antenna as well as improved bandwidth. The antenna is designed to serve WLAN applications at operating frequency of 5 GHz. The design process begins by a simple circular patch antenna feed by a coaxial cable and designed on aFR4 dielectric substrate with total ground plane in its backward side. The iniaturization technique consists of placing the complementary split ring resonator cells on the ground plane. A size reduction of 35% is reached without losing the performance of the initial antenna. The design, and the simulation of the poposed antenna were completed using the CST Microwave Studio simulator. The numerical result show that satisfactory results have been obtained in terms of miniaturization and adaptation as well as improvement in the bandwidth at resonant frequency compared to the conventional antenna.

The objective of this work is the design and simulation of an antenna based on metamaterials in order to miniaturize the initial dimensions of the planar antennas. Metamaterials are on the rise in recent years. The new properties make it possible to consider the production of new electronic components with new functionalities. Metamaterials are artificial materials designed for different telecommunications applications in order to improve the performance of antennas in terms of efficiency, compactness and miniaturization of structures. The use of these materials offers advantages such as reduction in weight and bulk, which is beneficial for their integration into 5G and WIMAX telecommunications and telephony systems [1]. As part of this work, a set of simulations allowed us an understanding of the different characteristics of metamaterials engraved on planar antennas that resound in the 2.6 GHz frequency. This work is based on the performance monitoring of rectangular patch antennas using these materials. The purpose of this work is to achieve studying parametric to develop a miniature patch antenna optimally Original likely to meet the needs of systems without current son, conc u by the software simulation 3D CST Studio Suite and Matlab computer.

We report herein a case of bacteremic ascitic fluid infection in a liver transplant patient caused by a strain of Yersinia pseudotuberculosis serogroup I that lost the yersiniabactin core. The patient's outcome was favorable after a combined therapy with a third-generation cephalosporin and gentamicin. [ABSTRACT FROM AUTHOR]

Background: Endoscopic ultrasound-guided gastroenterostomy (EUS-GE) using lumen-apposing metal stents (LAMSs) appears to be effective and safe in gastric outlet obstruction (GOO); however, the EUS-GE procedure is not standardized, with the use of assisted or direct methods still debated. The aim of this study was to compare the outcomes of EUS-GE techniques focusing on an assisted with orointestinal drain wireless endoscopic simplified technique (WEST) and the nonassisted direct technique over a guidewire (DTOG)., Method: This was a multicenter European retrospective study involving four tertiary centers. Consecutive patients who underwent EUS-GE for GOO between August 2017 and May 2022 were included. The primary aim was to compare the technical success and adverse event (AE) rates of the different EUS-GE techniques. Clinical success was also analyzed., Results: 71 patients (mean [SD] age 66.2 10 years; 42.3 % men; 80.3 % malignant etiology) were included. Technical success was higher in the WEST group (95.1 % vs. 73.3 %; estimate of relative risk from odds ratio (eRR) 3.2, 95 %CI 0.94-10.9; P  = 0.01). The rate of AEs was lower in the WEST group (14.6 % vs. 46.7 %; eRR 2.3, 95 %CI 1.2-4.5; P  = 0.007). Clinical success was comparable between the two groups at 1 month (97.5 % vs. 89.3 %). The median follow-up was 5 months (range 1-57)., Conclusion: The WEST resulted in a higher technical success rate with fewer AEs, with clinical success comparable with the DTOG. Therefore, the WEST (with an orointestinal drain) should be preferred when performing EUS-GE., Competing Interests: L. Monino is a consultant for Prion Medical and Braun Medical and has received speaker’s fees from Olympus Belgium and Olympus Europe. E. Pérez-Cuadrado-Robles and J.-M. Gonzalez are consultants for Boston Scientific. P. H. Deprez is a consultant for Boston Scientific and Olympus Europe. T. G. Moreels has received speaker’s fees from Olympus Belgium and Olympus Europe. M. Barthet is a consultant for Boston Scientific.C. Snauwaert, H. Alric, M. Gasmi, S. Ouazzani, H. Benosman, G. Rahmi, and C. Cellier declare that they have no conflict of interest., (Thieme. All rights reserved.)

Objectives: Little is known about how to perform the endoscopic ultrasound (EUS)-directed transgastric endoscopic retrograde cholangiopancreatography (ERCP; EDGE) in patients with gastric bypass using lumen-apposing metal stents (LAMS). The aim was to assess the risk factors of anastomosis-related difficult ERCP., Methods: Observational single-center study. All patients who underwent an EDGE procedure in 2020-2022 following a standardized protocol were included. Risk factors for difficult ERCP, defined as the need of >5 min LAMS dilation or failure to pass a duodenoscope in the second duodenum, were assessed., Results: Forty-five ERCPs were performed in 31 patients (57.4 ± 8.2 years old, 38.7% male). The EUS procedure was done using a wire-guided technique (n = 28, 90.3%) for biliary stones (n = 22, 71%) in most cases. The location of the anastomosis was gastro-gastric (n = 24, 77.4%) and mainly in the middle-excluded stomach (n = 21, 67.7%) with an oblique axis (n = 22, 71%). The ERCP technical success was 96.8%. There were 10 difficult ERCPs (32.3%) due to timing (n = 8), anastomotic dilation (n = 8), or failure to pass (n = 3). By multivariable analysis adjusted by two-stage procedures, the risk factors for a difficult ERCP were the jejuno-gastric route (85.7% vs. 16.7%; odds ratio [OR a ] 31.875; 95% confidence interval [CI] 1.649-616.155; P = 0.022), and the anastomosis to the proximal/distal excluded stomach (70% vs. 14.3%; OR a 22.667; 95% CI 1.676-306.570; P = 0.019). There was only one complication (3.2%) and one persistent gastro-gastric fistula (3.2%) in a median follow-up of 4 months (2-18 months), with no weight regain (P = 0.465)., Conclusions: The jejunogastric route and the anastomosis with the proximal/distal excluded stomach during the EDGE procedure increase the difficulty of ERCP., (© 2023 The Authors. Digestive Endoscopy published by John Wiley & Sons Australia, Ltd on behalf of Japan Gastroenterological Endoscopy Society.)

Introduction: Endoscopic ultrasound-guided gastroenterostomy (EUS-GE) is increasingly used in the setting of malignant gastric outlet obstruction (GOO). However, little is known about the role of primary EUS-GE. The aim of the present study is to compare the outcomes of EUS-GE by using the freehand technique as a first- and second-line approach after enteral stenting (ES)., Methods: This is an observational single-center study using a prospectively collected database. All consecutive patients who underwent an EUS-GE using the freehand technique due to malignant GOO were included. Patients with previous gastric surgery, a wire-guided EUS-GE technique, or those presenting without GOO were excluded. The primary outcome was the clinical success, defined as a solid oral intake at 1 week after the procedure (GOO Score, GOOSS ≥ 2). The secondary outcomes were technical success and adverse event (AE) rates. The impact on nutritional parameters was also assessed., Results: Forty-five patients underwent an EUS-GE for all indications. Finally, 28 patients (mean age: 63 ± 17.2 years, 57.1% male) with ( n = 13, 46.4%) and without ( n = 15, 53.6%) a previous ES were included. The technical success was achieved in 25 cases (89.3%), with no differences between the two groups (92.3% vs. 86.7%, p = 1). The median limb diameter and procedure time were 27 mm (range:15-48) and 37 min. Overall, clinical success was achieved in 22 cases (88%), with three failures due to AEs ( n = 2) or peritoneal carcinomatosis ( n = 1). The diet progression was quicker in patients with a previous ES (GOOSS at 48 h, 2 vs. 1, p = 0.023), but the GOOSS at 1 week ( p = 0.299), albumin gain ( p = 0.366), and BMI gain (0.257) were comparable in the two groups. The AE rate was 7.1%., Conclusions: EUS-GE achieves a high technical and clinical success in patients with GOO regardless of the presence of a previous ES. Patients with previous ES may have a quicker progression of their diet, but the GOOSS and nutritional status in the long term at 1 week or 1 month are comparable. Primary EUS-GE might require fewer procedures and less discontinuation of chemotherapy to achieve a comparable result.

Introduction: biodegradable stents of various designs are reportedly used in pancreato-biliary conditions with promising results. Their major advantage is the avoidance of repeat endoscopic procedure for stent removal, thereby reducing overall costs and endoscopic retrograde cholangiopancreatography (ERCP) associated adverse events. The aim of the study was to evaluate the feasibility and safety of a new biodegradable stent in patients with pancreato-biliary diseases., Methods: a prospective multicenter pilot study was performed. All consecutive patients ≥ 18 years old who underwent biliary or pancreatic stenting using the new biodegradable Archimedes stent were included in the study. There were three biodegradation profiles. Technical and clinical success and feasibility and safety were assessed during a pre-established follow-up schedule., Results: fifty-three patients (mean age: 48.54 ± 19.29, 66 % male) with biliary (n = 29, 54.7 %) or pancreatic (n = 24, 45.3 %) indications were included. The distribution of stents used according to degradation properties were as follows: fast (n = 11, 20.8 %), medium (n = 16, 30.2 %) and slow (n = 26, 49.1 %). The technical and clinical success were 100 % and 77.8 %, respectively. Thirty-five patients were followed for a median of 26 weeks (range: 4-56, 66 %). There were nine procedure-related adverse events (17 %), all mild, including one uneventful stent-related event (external migration)., Conclusion: the biodegradable Archimedes stent placement is feasible and safe in pancreato-biliary diseases.

Competing Interests: The authors declare that they have no conflict of interest.

Background: European guidelines recommends the use of cold snare polypectomy (CSP) for removal of diminutive colorectal polyps (DCP). However, for DCP < 4 mm cold biopsy forceps (CBF) may be optional. We aimed to compare the efficacy of CSP with CBF for removal of DCP in routine colonoscopy., Methods: We conducted a multicenter non-inferiority randomized controlled trial. After screening, 123 patients were prospectively included and 180 DCPs were removed by either CBF or CSP after randomization (1:1). The primary end-point was the histological complete resection rate defined by negative additional biopsies taken from the edge of the polypectomy ulcer site., Results: Among DCPs, 121 (67.2%) adenomas or sessile serrated lesions were considered for the analysis. Polyps were 4 [1-5] mm in size, mostly flat (55.4%) and located in the proximal colon (44.6%). The en bloc resection rate was higher in the CSP group than the CBF group (91.7% vs. 42.6%, p < 0.001). The histological complete resection rate was comparable in the two groups (93.33% vs 90.16%; p = 0.527), even for polyps < 4 mm (91.30% vs 91.30%; p = 1). All specimens were retrieved and there was no difference in terms of procedure times and adverse events. Finally, univariate analysis did not identify any potential factor associated with complete resection rate., Conclusion: In this study, CSP was comparable to CBF for the removal of DCP. Therefore, CBF may be considered as an alternative technique for resection of DCP, together with CSP, ClinicalTrials.gov registry (NCT04727918)., Competing Interests: Declaration of Competing interest Comparison of cold biopsy forceps vs cold snare for diminutive colorectal polyp removal: a multicenter non-inferiority randomized controlled trial Authors declare no conflict of interest for this article Guillaume Perrod : no disclosure Enrique Perez-Cuadrado-Robles: no disclosure Emmanuel Coron : no disclosure Mathieu Pioche: no disclosure Aymeric Becq: no disclosure Nicolas Etchepare: no disclosure David Danan: no disclosure Nicolas Musquer: no disclosure Xavier Dray: no disclosure Arthur Laquiere: no disclosure Bénédicte Jais: no disclosure Chloé Broudin: no disclosure Hedi Benosman: no disclosure Christophe Cellier: no disclosure Gabriel Rahmi: no disclosure, (Copyright © 2022 Elsevier Masson SAS. All rights reserved.)

Competing Interests: The authors declare that they have no conflict of interest.

Background: Salvage transjugular intrahepatic portosystemic shunts (TIPS) are associated with poor prognosis, especially in patients with Child-Pugh C cirrhosis. Since preemptive TIPS improved prophylaxis of variceal bleeding in those patients, recourse to salvage TIPS may now affect patients with a better prognosis., Aim: To assess the impact of the preemptive TIPS policy on outcomes after salvage TIPS placement., Methods: We conducted a retrospective monocentric study on cirrhotic patients undergoing salvage TIPS with polytetrafluoroethylene-covered stents from 2002 to 2017 (period 1 until February 2011; period 2 after the preemptive TIPS policy in March 2011). The primary endpoint was one-year transplant-free survival., Results: We included 106 patients (period 1/2 = 53/53 patients, male gender 82%, age 54 ± 9 years, alcoholic cirrhosis 70%, Child-Pugh score B/C 94%). One-year transplant-free survival was 46.0% during period 1 compared to 40.2% during period 2 (p = 0.65). Amongst 61 patients with history of variceal bleeding, 32 (52.5%) had an inadequate secondary prophylaxis, including 19 (59.4%) with a previous indication of preemptive TIPS. One-year transplant-free survival was 33.2% if inadequate secondary prophylaxis vs 65.2% if adequate (p = 0.008). Independent factors associated with survival were a lower Child-Pugh or MELD score, infection, failure to control bleeding, and hepatic encephalopathy after TIPS., Conclusion: Prognosis after salvage TIPS remained poor in our series. Optimizing secondary prophylaxis, including preemptive TIPS placement, should be the main concern to improve prognosis., (Copyright © 2020 Elsevier Masson SAS. All rights reserved.)

Competing Interests: The authors declare that they have no conflict of interest.

Competing Interests: The authors declare that they have no conflict of interest.

Background and Aims: The role of small bowel neoplasia (SBN) screening in asymptomatic patients with Lynch syndrome (LS) is uncertain. The aim of our study was to assess the effectiveness of screening by capsule endoscopy (CE) in these patients., Methods: This study was an observational, analytical, and retrospective single-center study within the PRED-IdF network. All consecutive asymptomatic patients older than 35 years-old with confirmed LS and no personal history of SBN who started the screening from 2010-2015 were included. The baseline screening and 24 months follow-up were performed by CE. The CE diagnostic yield (positive tumor or polyp) and accuracy, using the follow-up as gold standard, were evaluated., Results: A total of 150 patients underwent the SBN screening program and 135 (52.7 ± 11.2 years-old, 37.8% male) met the inclusion criteria. The baseline CE diagnostic yield was 4.4% (3 polyps, 3 tumors) and the proximal small bowel was the most common location ( n  = 4, 66.7%). In total, 87 patients underwent follow-up and the diagnostic yield was 4.6%.Four patients were considered positive at follow-up (2 adenomas, 2 adenocarcinomas). The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of CE were 60%, 100%, 100%, 96.9%, and 97%, respectively., Conclusions: CE is an accurate procedure for baseline screening of SBN in LS patients and may be efficient for follow-up procedures. However, the optimal starting age of screening and intervals of follow-up must be clarified., Competing Interests: Conflict of interest statement: The authors declare that there is no conflict of interest., (© The Author(s), 2020.)

Background and Study Aims: Post-laparoscopic sleeve gastrectomy (LSG) fistula is a major complication, responsible for high morbidity. Endoscopic treatment represents an alternative to surgical management, with variable approaches and success rates. In this study, we aimed to evaluate the efficacy of endoscopic treatment in a tertiary care center., Patients and Methods: Between March 2010 and March 2015, all patients referred to our center for endoscopic treatment of fistula related to laparoscopic sleeve gastrectomy were included. The primary endpoint was defined as a complete closure of the fistula without recurrence within the 2 months., Results: A total of 26 patients were retrospectively included (73% female). The mean time between fistula diagnosis and first endoscopy was 27.4 days (± 22). Twenty-three (88.4%) patients had a complete fistula closure after endoscopic treatment. The healing delay was 76.4 days (± 42.8), and an average of 3.5 (± 1.4) endoscopic procedures were required. Clinical efficacy was 100% when the endoscopic treatment was performed within the first 3 weeks, or 70% afterwards (p = 0.046). The fistula closure rate was similar between patients with endoscopic drainage (with or without other endoscopic techniques) and patient with closing techniques alone (85.7% vs. 89.5%, respectively)., Conclusion: Endoscopic treatment of fistula after LSG is efficient but requires early procedures within the first 3 weeks. Endoscopic strategies involving closing procedure or drainage procedure seem to be similar, but these data must be confirmed in large prospective clinical studies.

Aim: The aim of this study was to evaluate the accuracy of procalcitonin (PCT) in predicting bacterial infection and survival without transplantation upon admission in the ICU for acute liver failure (ALF)., Patients and Methods: From January 2009 until October 2015, all cases of ALF patients admitted in our ICU were retrospectively reviewed and included in the study if the PCT level upon admission was available. Patients with pre-existing liver pathology or ALF in a context of already advanced multiorgan failure were excluded. The main clinical and biological characteristics of patients were recorded, as well as the etiology of ALF, diagnosis of bacterial infection (bacteriologically documented or suspected), and outcome., Results: 35 patients were included: 46% men, mean age 42 years, initial prothrombin ratio 31%, PCT 9.8 mg/l (0.7-49), and PCT more than 2 mg/l in 54% of cases. Etiology was acetaminophen intoxication in 18/35 (51%) cases. Sepsis was diagnosed in 9/35 (26%) cases, most frequently pneumonia with 4/9 cases. Survival without liver transplantation (LT) was observed in 28 (80%) cases. The median PCT was not different in patients with or without bacterial infection [6.3 mg/l (0.6-16) vs. 1.2 mg/l (0.8-9.7), P=0.8]. The median PCT was not different in patients who survived without LT [7.1 mg/l (0.9-16.1) vs. 0.75 mg/l (7.7-11.5), P=0.06]. In patients with ALF unrelated to acetaminophen intoxication, the median PCT was higher in patients with bacterial infection [1.1 mg/l (0.9-4) vs. 0.5 mg/l (0.3-0.8), P=0.01], but was similar in patients who did not survive without LT [0.7 mg/l (0.4-1.1) vs. 0.8 mg/l (0.4-2.2), P=0.6]. In the overall cohort, the median C-reactive protein (CRP) and leukocyte count were higher in patients who developed bacterial infection [40 mg/l (19-60) vs. 16 mg/l (6-34), P=0.04; 11.9 G/l (8.3-19) vs. 7.9 G/l (6-12.6), P=0.05]. The median CRP and leukocyte count were not significantly different in survivors versus nonsurvivors without LT., Conclusion: PCT was an accurate predictor for the diagnosis of bacterial infection only in patients with ALF unrelated to acetaminophen intoxication. CRP was higher in patients who developed infection and could also be an interesting tool in ALF patients.

Background and study aims  Over-the-scope clip (OTSC) has been recently used in management of gastrointestinal perforations, but data on it are still limited. The aim of this study was to compare management of iatrogenic perforations before and after the OTSC was available in our endoscopy unit. Patients and methods  We conducted a monocentric retrospective study from June 2007 to June 2015. All iatrogenic gastrointestinal perforations detected during endoscopy were included. Two time periods were compared in terms of surgery and mortality rates: before use of OTSC (June 2007 to June 2011) and after OTSC became available (June 2011 to June 2015). Results  During the first period, 24 perforations were recorded. Fifteen (62.5 %) were managed with surgery. The mortality rate was 8 %. During the second period, 16 perforations occurred. In 11 patients (68.7 %), an OTSC was used to close the perforation, with complete sealing of the perforation in 100 % of cases. However, 2 patients with sigmoid perforation had to undergo surgery due to right ureteral obstruction by the clip in 1 case and to presence of a localized peritonitis in the other. The surgery rate during this period was 12.5 % (2 /16), with a statistically significant difference compared to the first period ( P  = 0.002). There was no mortality in the second period versus 8 % in the first one ( P  = 0.23). Conclusions  OTSC is effective for endoluminal closure of iatrogenic perforations and results in a significant decrease in surgery rate.

Background & Aims: All trials on severe alcoholic hepatitis (AH) have included patients with "pure" AH, i.e., without concomitant gastrointestinal bleeding (GIB). Severe AH is often suspected in cirrhotic patients with GIB. We aimed at (1) assessing the prevalence of AH in patients with GIB and Maddrey discriminant function (DF) ⩾32; (2) comparing the outcome in AH patients with or without GIB (AH-GIB+, AH-GIB-); and (3) assessing the performance of the Lille model for survival in AH-GIB+ patients., Methods: We retrospectively included all patients with alcoholic cirrhosis admitted between January 2005 and March 2011 with the following: (1) jaundice <3 months; (2) DF ⩾32 at admission; (3) bilirubin level >50 μmol/L; and (4) active drinking. Exclusion criteria were advanced hepatocellular carcinoma, other etiology of cirrhosis, severe comorbidities and DF <32 after stabilization. In our centre, we systematically plan a liver biopsy for these patients. Patients with severe AH received prednisolone., Results: We screened 161 patients (86 GIB+, 75 GIB-), and analyzed data for 58 and 47 patients in each group, respectively. The 2 groups did not differ in prevalence of AH (77.3% vs. 81%), demographic data, MELD/Child-Pugh score, or DF. The 2 groups were similar in 6-month probability of survival (73.9 ± 6.0% vs. 69.9 ± 7%, p=0.49). The probability of developing infection was lower for AH-GIB+ patients (24.1% vs. 44.7%, p=0.04). The AUC for the Lille model in predicting 6-month survival was 0.71 ± 0.06 for all patients and 0.74 ± 0.06 for AH-GIB+ patients (p>0.05)., Conclusions: Prevalence of AH is 80% for patients with cirrhosis and GIB, recent jaundice and DF ⩾32. Infection was lower for AH-GIB+ patients, which suggests a beneficial role of antibiotic prophylaxis treatment. Survival among subjects with GIB was the same as among subjects without GIB., (Copyright © 2015 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.)

We present a new examination of the EPR redox titration data for the tetraheme cytochrome c3 from Desulfovibrio vulgaris Miyazaki. Our analysis includes the contribution of the interaction potentials between the four redox sites and is based on the model previously developed for the study of cytochrome c3 from Desulfovibrio desulfuricans Norway. We observed, as for D. desulfuricans Norway cytochrome c3, that the conformation of the heme with the lowest redox potential, heme 4, is sensitive to the redox state of the heme with the highest potential, heme 1. However in D. vulgaris Miyazaki cytochrome c3 spectral simulations show that heme 4 is present in two conformational states which interconvert partially when heme 1 is reduced. The sets of redox parameters which satisfy the fitting procedure of the titration curves are in the following domain: -250 mV less than or equal to e41 less than or equal to -220 mV, -325 mV less than or equal to e2 less than or equal to -320 mV, -335 mV less than or equal to e3 less than or equal to -330 mV, -360 mV less than or equal to e4 less than or equal to -355 mV, -5 mV less than or equal to I12 less than or equal to 20 mV, -10 mV less than or equal to I13 less than or equal to 5 mV, -15 mV less than or equal to I23 less than or equal to -5 mV, -15 mV less than or equal to I24 less than or equal to -10 mV, -25 mV, less than or equal to I34 less than or equal to -15 mV. As in D. desulfuricans Norway cytochrome c3 the interactions are moderate. Simple electrostatic considerations suggest that these moderate values could be related to the large accessibility of the hemes to the solvent. Our work does not confirm the existence of a cooperative interaction between heme 2 and heme 3 which has been proposed on the basis of electrochemical measurements.

In cytochromes c3 which contain four hemes per molecule, the redox properties of each heme may depend upon the redox state of the others. This effect can be described in terms of interaction redox potentials between the hemes and must be taken into account in the characterization of the redox properties of the molecule. We present here a method of measurement of these interactions based on the EPR study of the redox equilibria of the protein. The microscopic and macroscopic midpoint potentials and the interaction potentials are deduced from the analysis of the redox titration curves of the intensity and the amplitude of the EPR spectrum. This analysis includes a precise simulation of the spectrum of the protein in the oxidized state in order to determine the relative contribution of each heme to the spectral amplitude. Using our method on cytochrome c3 from D. desulfuricans Norway, we found evidence for the existence of weak interaction potentials between the hemes. The three interaction potentials which have been measured are characterized by absolute values lower than 20 mV in contrast with the values larger than 40-50 mV which have been reported for cytochrome c3 from D. gigas. Simulations of the spectra of samples poised at different potentials indicate a structural modification of the heme with the most negative potential during the first step of reduction. The correspondence between the redox sites as characterized by the EPR potentiometric titration and the hemes in the tridimensional structure is discussed.