Improving acoustic wave propagation models in highly attenuating porous materials.

This article presents an improved and extended modeling approach for acoustic wave propagation in rigid porous materials, focusing on examples, such as plastic foams used for noise reduction in automotive applications. We demonstrate that the classical model (Johnson-Champoux-Allard) in the asymptotic high-frequency limit, widely employed in the literature, fails to accurately reconstruct the transmitted acoustic signal through high absorbent porous materials characterized by significant wave attenuation. The study focuses on the airborne ultrasonic frequency range (30-200 kHz). To address this limitation, we introduce new non-acoustic parameters Σ and V for viscous effects, and Σ' and V' for thermal effects, with surface and volumetric dimensions, respectively, allowing for the reconstruction of the transmitted signal and accurate modeling of the pronounced acoustic attenuation within the material. These parameters are incorporated into the expansion on skin depths of the dynamic tortuosity α(ω) and thermal tortuosity α' (ω) response functions, which describe the inertial-viscous and thermal interactions between the fluid and the solid, respectively. This novel modeling approach enables a more comprehensive study of high attenuating porous media, which are crucial for effective noise reduction. Additionally, it opens up new possibilities for characterization beyond the capabilities of current models.

Acoustics of monodisperse open-cell foam: An experimental and numerical parametric study.

This article presents an experimental and numerical parametric study of the acoustical properties of monodisperse open-cell solid foam. Solid foam samples are produced with very good control of both the pore size (from 0.2 to 1.0 mm) and the solid volume fraction (from 6% to 35%). Acoustical measurements are performed by the three-microphone impedance tube method. From these measurements, the visco-thermal parameters-namely, viscous permeability, tortuosity, viscous characteristic length, thermal permeability, and thermal characteristic length-are determined for an extensive number of foam samples. By combining Surface Evolver and finite-element method calculations, the visco-thermal parameters of body centered cubic (bcc) foam numerical samples are also calculated on the whole range of solid volume fraction (from 0.5% to 32%), compared to measured values and to theoretical model predictions [Langlois et al. (2019). Phys. Rev. E 100(1), 013115]. Numerical results are then used to find approximate formulas of visco-thermal parameters. A systematic comparison between measurements and predictions of the Johnson-Champoux-Allard-Lafarge (JCAL) model using measured visco-thermal parameters as input parameters, reveals a consistent agreement between them. From this first step, a calculation of the optimal microstructures maximizing the sound absorption coefficient is performed.

Multiscale prediction of acoustic properties for glass wools: Computational study and experimental validation.

This work is concerned with the multiscale prediction of the transport and sound absorption properties associated with industrial glass wool samples. In the first step, an experimental characterization is performed on various products using optical granulometry and porosity measurements. A morphological analysis, based on scanning electron imaging, is further conducted to identify the probability density functions associated with the fiber angular orientation. The key morphological characterization parameters of the microstructure, which serve as input parameters of the model, include the porosity, the weighted volume diameter accounting for both lengths and diameters of the analyzed fibers (and therefore the specific surface area of the random fibrous material), and the preferred out-of-plane fiber orientation generated by the manufacturing process. A computational framework is subsequently proposed and allows for the reconstruction of an equivalent fibrous network. A fully stochastic microstructural model, parameterized by the probability laws inferred from the database, is also proposed herein. Multiscale simulations are carried out to estimate transport properties and sound absorption. With no adjustable parameter, the results accounting for ten different samples obtained with various processing parameters are finally compared with the experimental data and used to assess the relevance of the reconstruction procedures and the multiscale computations.

[Poor self-esteem is correlated with suicide intent, independently from the severity of depression]. / La faible estime de soi est corrélée à l'intentionnalité suicidaire, indépendamment de la sévérité de la dépression.

INTRODUCTION: Suicide is a major Public Health concern, and low self-esteem might represent a major risk factor. Our main objective was to assess the correlation between self-esteem and suicide intent. More specifically, we aimed to examine the relationship between the different dimensions of self-esteem (total, general, familial, professional and social) and suicide intent. We also sought the role of depression in the relationship of self-esteem to suicide intent. METHOD: This retrospective cross-sectional study was conducted at a suicide prevention department at the CMME (Sainte-Anne Hospital, Paris, France). We included patients aged 15 and older and admitted for suicide attempt over a 3-year period from January 2008 to December 2010. Self-esteem was assessed with the Coopersmith's Self-Esteem Inventory (SEI) scale that takes into account several domains of self-esteem. Subjects scoring over 5 points on the lie scale were excluded. Our primary endpoint was the correlation between self-esteem and suicide intent. Our secondary endpoint was the same correlation adjusted for depression severity (using the Hamilton scale). Suicide intent was estimated using Beck's Suicide Intentionality Scale (SIS). We examined the Pearson's correlation coefficients between self-esteem and suicide intent. These analyses were adjusted for the severity of depressive symptoms assessed with the Hamilton Depression Rating Scale (17 items). RESULTS: Overall, 132 patients were included. Suicide intent was correlated with total self-esteem (r=-0.227, P=0.009), social self-esteem (r=-0.331, P<0.001) and familial self-esteem (r=-0.260, P=0.003). These results remained significant after adjusting for the level of depression for total score (r=-0.181, P=0.038), and the social (r=-0.282, P=0.001) and familial (r=-0.237, P=0.006) dimensions. CONCLUSION: Self-esteem (and especially social and familial dimensions) is likely to be associated with suicide intent, at least in part independently of the severity of depression, in a population of subjects hospitalized for suicide attempt. This correlation was strongest with social self-esteem. The main limitation of this monocentric study is the lack of representative sample. Nevertheless, this result paves the way for future strategies of suicide prevention, especially those dealing with poor self-esteem.

Quantitative System Pharmacology (QSP): An Integrative Framework for paradigm change in the treatment of the first-episode schizophrenia.

Despite the lack of progress in the curative treatment of mental illness, especially schizophrenia, the accumulation of neuroscience data over the past decade suggests the re-conceptualization of schizophrenia. With the advent of new biomarkers and cognitive tools, new neuroscience technologies such as functional dynamic connectivity and the identification of subtle clinical features; it is now possible to detect early stages at risk or prodromes of a first psychotic episode. Current concepts reconceptualizes schizophrenia as a neurodevelopmental disorder at early onset, with polygenic risk and only symptomatic treatment for positive symptoms at this time. The use of such technologies in the future suggests new diagnostic and therapeutic options. Next steps include new pharmacological perspectives and potential contributions of new technologies such as quantitative system pharmacology brain computational modeling approach.

[Retrospective evaluation of short tympanostomy tubes efficacy in case of recurrent acute otitis media on an infant population]. / Evaluation rétrospective de l'efficacité des aérateurs trans-tympaniques courts en cas d'otites moyennes aiguës récidivantes chez le nourrisson.

INTRODUCTION: The aim of this study is to appreciate the results of short-tympanostomy tubes (ST) in case of recurrent acute otitis media (AOM), and to appreciate the risk factors of recurrent AOM. METHODS: This retrospective chart study concerns infants who had STT placement surgery forrecurrent AOM, between 2007 and 2011. Demographic data, anamnesis, efficacy and postoperative follow-up were analyzed. RESULTS: Forty-nine children were included in the study (30 boys, 19 girls; 7 months to 2 years-old, median age 1.4 year). Two-thirds attended a day-care center, one third was an onlychild. One quarter had an anemia. Anti-Haemophilus and anti-pneumococcus vaccinations were up-to-date in 87.5%. After STT placement, 20 children (40.8%) did not present any new episode of AOM. This result did not vary with adenoidectomy. Among the ones that relapsed AOM after STT, 48.3% presented with only one episode. For two thirds of the patients, no general antibiotic treatment was necessary as long as the STT were in place. Half STT have been spontaneously expulsed between 6 and 12 months. Thirteen infants (37.1%) had new episodes of AOM after STT expulsion and 5 (38.5%) needed new tube placement. CONCLUSION: This study confirms that day care and siblings are risk factors of recurrent AOM, but does not confirm potential role of the anemia. STT placement decreased effectively AOM recurrences, their severity and the need for antibiotics prescriptions. No residual perforation was encountered in this study.

Evaluation of symptomatic drug effects in Alzheimer's disease: strategies for prediction of efficacy in humans.

In chronic diseases such as Alzheimer's disease (AD), the arsenal of biomarkers available to determine the effectiveness of symptomatic treatment is very limited. Interpretation of the results provided in literature is cumbersome and it becomes difficult to predict their standardization to a larger patient population. Indeed, cognitive assessment alone does not appear to have sufficient predictive value of drug efficacy in early clinical development of AD treatment. In recent years, research has contributed to the emergence of new tools to assess brain activity relying on innovative technologies of imaging and electrophysiology. However, the relevance of the use of these newer markers in treatment response assessment is waiting for validation. This review shows how the early clinical assessment of symptomatic drugs could benefit from the inclusion of suitable pharmacodynamic markers. This review also emphasizes the importance of re-evaluating a step-by-step strategy in drug development.

Permeability of polydisperse solid foams.

The effect of polydispersity on foam permeability is investigated by numerical simulations. Foam structures are first generated by Laguerre tessellations via the Neper software and relaxed to minimize the surface energy via the Surface Evolver software. The fluid flow and permeability are then calculated by means of pore-network simulations, by considering either fully open-cell foams or foams with randomly selected closed windows. Different configurations of window aperture are used, including identical window aperture size, identical window aperture ratio, or random window aperture ratio. The main results are obtained for the case of foams having identical and uniform window aperture ratios. For such foams and at constant mean pore size, foam permeability is found to strongly increase with the polydispersity degree. The numerical results are employed to discuss the validity of the mean pressure field assumption used to calculate the foam permeability, the effect of small pores, and the definition of an equivalent Kelvin foam size. We show that as long as the fluctuations of the window aperture ratio remain low, foam permeability can be estimated by using the mean pressure field hypothesis. The weak effect of small pores on permeability is related to their small contribution to the overall fluid volume fraction. Finally, various estimations of the equivalent Kelvin foam size based on pore-size distribution are proposed.

Navigation in head and neck oncological surgery: an emerging concept.

Navigation surgery, initially applied in rhinology, neurosurgery and orthopaedic cases, has been developed over the last twenty years. Surgery based on computed tomography data has become increasingly important in the head and neck region. The technique for hardware fusion between RMI and computed tomography is also becoming more useful. We use such device since 2006 in head and neck carcinologic situation. Navigation allows control of the resection in order to avoid and protect the precise anatomical structures (vessels and nerves). It also guides biopsy and radiofrequency. Therefore, quality of life is much more increased and morbidity is decreased for these patients who undergo major and mutilating head and neck surgery. Here we report the results of 33 navigation procedures performed for 31 patients in our institution.

Hepatorenal bypass allowing fenestrated endovascular repair of juxtarenal abdominal aortic aneurysm: a case report.

A 61-year-old man presented with a 66-mm juxtarenal aortic aneurysm. He was unfit for open repair. The anatomical proximity of his right renal artery (RRA) and his superior mesenteric artery (SMA) precluded fabrication of an endograft allowing perfusion of both vessels. He underwent a hepato-renal bypass to his RRA and subsequent fenestrated endovascular aneurysm repair (EVAR) using an endoprosthesis with fenestrations for the SMA and the left renal artery (LRA), and a scallop for the coeliac trunk. Follow-up imaging showed all visceral vessels to be perfused. The use of this limited hybrid approach allows endovascular treatment of aneurysms that are initially unsuitable for such an approach.

Endovascular repair of thoracoabdominal aortic aneurysms.

OBJECTIVES: To evaluate the early outcomes following thoracoabdominal aortic aneurysm (TAAA) repair utilising fenestrated and branched endografts. DESIGN AND MATERIALS AND METHODS: A prospective analysis of all patients undergoing endovascular repair of TAAA in a single academic centre. All patients were deemed unfit for open surgical repair. Customised endografts were designed using CT data reconstructed on 3D workstations. Post-operatively all patients were evaluated radiologically at hospital discharge, at 6, 12, 18 and 24 months, and annually thereafter. RESULTS: Thirty-three consecutive patients (30 males) were treated over 33 months (August 2006 to April 2009). Median age and aneurysm size were 70 years (range 50-83 years) and 64 mm (range 55-100 mm) respectively. 114/116 (98%) of the targeted visceral vessels were successfully catheterised and perfused. The in-hospital mortality rate was 9% (3/33). Transient spinal cord ischaemia was diagnosed in 4/33 (12%) patients, and permanent paraplegia in one (3%). The median follow-up period was 11 months (range 1-33 months). Endoleaks were identified in 5/33 (15%) patients: type II in four patients and a type III endoleak in one patient which required the only secondary intervention. During follow-up, two patients died: one from stroke and the other from myocardial infarction 9 and 29 months respectively after the procedure. CONCLUSION: This preliminary study, which includes our learning curve, confirms the feasibility and safety of the endovascular repair of TAAA in high-risk patients. Meticulous follow-up to assess sac behaviour and visceral perfusion is critical in order to ensure optimal results of these complex endovascular repairs requiring numerous mating components.

Electrical conductivity and tortuosity of solid foam: Effect of pore connections.

Numerical and analytical methods at both micro- and mesoscales are used to study how the electrical resistivity and the high-frequency tortuosity of solid foam are modified by the presence of membranes that partially or totally close the cell windows connecting neighbor pores. Finite-element-method simulations are performed on two pores connected by a single-holed membrane and on well-ordered Kelvin foam. For two pores connected by a single-holed membrane, we show that the equation for pore access resistance obtained by Sahu and Zwolak [Phys. Rev. E 98, 012404 (2018)2470-004510.1103/PhysRevE.98.012404] can predict, after a few modifications, the electrical resistivity at the membrane scale for a large range of membrane apertures. Considering these analytical results, we build a pore-network model by using two kinds of conductances at the pore scale: interpore conductance and intrapore conductance. Local interpore resistances govern foam electrical conductivity at small membrane aperture size, but when the membrane aperture has the same order of magnitude as the pore size, the intrapore resistances are no longer negligible. An important success of this pore-network model is that it can be used to study the effects of percolation on the foam electrical conductivity by using pore-network simulations on larger samples containing a few thousand pores and having different proportions of closed membrane randomly distributed over the sample. The tortuosity is found to be drastically larger than one in foam containing membranes with small apertures or a significant fraction of closed membranes.

Permeability of solid foam: Effect of pore connections.

In this paper, we study how the permeability of solid foam is modified by the presence of membranes that close partially or totally the cell windows connecting neighboring pores. The finite element method (FEM) simulations computing the Stokes problem are performed at both pore and macroscopic scales. For foam with fully interconnected pores, we obtain a robust power-law relationship between permeability and aperture size. This result is due to the local pressure drop mechanism through the aperture as described by Sampson for fluid flow through a circular orifice in a thin plate. Based on this local law, pore-network simulation of simple flow is used and is shown to reproduce FEM results. Then this low computational cost method is used to study in detail the effect of an open window fraction on the percolation properties of the foam pore space. The results clarify the effect of membranes on foam permeability. Finally, Kirkpatrick's model is adapted to provide analytical expressions that allow for our simulation results to be successfully reproduced.

Fluorescence in situ hybridization analysis of 110 hematopoietic disorders with chromosome 5 abnormalities: do de novo and therapy-related myelodysplastic syndrome-acute myeloid leukemia actually differ?

A retrospective cytogenetic study of acute myeloid leukemias (AML) and myelodysplastic syndromes (MDS) was conducted by the Groupe Francophone de Cytogénétique Hématologique (GFCH) to evaluate the structural abnormalities of chromosome 5 associated with other chromosomal abnormalities, in particular of chromosome 7, in these pathologies. In all, 110 cases of AML/MDS were recruited based on the presence of chromosome 5 abnormalities under conventional cytogenetics and supplemented by a systematic fluorescence in situ hybridization study of chromosomes 5 and 7. The abnormalities of the long arm of chromosome 5 (5q) were deletions of various sizes and sometimes cryptic. The 5q abnormalities were associated with translocations in 54% of cases and were simple deletions in 46%. In 68% of cases, 5q deletions were associated with chromosome 7 abnormalities, and 90% of these presented a complex karyotype. Of the 110 patients, 28 had a hematopoietic disorder secondary to chemotherapy, radiotherapy, or both. Among 82 patients with de novo AML/MDS, 63 were older than 60 years. Chromosomal abnormalities often associated hypodiploidy and chromosome 5 and 7 abnormalities in complex karyotypes, features resembling those of secondary hemopathies. Systematic investigation of the exposure to mutagens and oncogenes is thus essential to specify the factors potentially involved in MDS/AML with 5q abnormalities.

[Conceptualisation and validation of the "Emotional State Questionnaire (ESQ)": evaluation of an emotional profile]. / Conceptualisation et validation factorielle d'un questionnaire mesurant le profil émotionnel: Emotional State Questionnaire (ESQ).

OBJECTIVES: The objective of this study is to evaluate the validity of a new self questionnaire: the "ESQ" (Emotional State Questionnaire). BACKGROUND: This novel instrument possesses a number of original attributes: first of all, it is designed to assess a general emotional profile, in opposition to other similar scales which can only be applied to the emotional reactions provoked by specific stimuli. Secondly, this scale is composed of several emotional dimensions. The ESQ has been constructed according to four components: recognition, expression, internal emotional experience and social context. The first three dimensions were selected because of their wide use through behavioral experiments. Indeed, contrary to most scales used in this field, which only assess the emotional experience, we wanted to propose an instrument also able to assess the subject's impression of his own capacities to encode and decode emotions. We hypothesized that these three dimensions could not be dissociated from a fourth dimension, the social context, which therefore also figures in this scale. The emotions explored were the five fundamental emotions indicated by Izard (fear, happiness, sadness, disgust and surprise) to which we added a neutral feeling that we considered as a basic emotion. STUDY DESIGN: To establish this instrument, a first conceptual phase was conducted by a group of experts. These experts all worked in the psychological field. They proposed the scale on the base of their clinical experience and after study of the literature. The scale was then validated in a population of 218 healthy volunteers, aged between 15 and 88 years. Subjects were not included if they presented depression (score above 16 in the Beck Depression Scale) or pathological anxiety (score above 5 in the Spieberger State Anxiety Inventory). The psychometric characteristics tested were: the item analysis, the item-dimension correlation, the factor analysis and the internal consistency reliability. RESULTS: The population studied was equally distributed according to gender (sex ratio: 0.97), the mean age was of 36.2 2 +/- 16.1 years. Acceptability was good with less than 5% of data missing. The analysis of items revealed no floor or ceiling effect and a low correlation between items. Item-dimension correlation ranged from 0.23 to 0.62, with most scores above 0.4. The items were always better correlated to their dimension than to other dimensions, except for one item. The 4 dimensions (recognition, expression, internal emotional experience and social context of emotions) explained 42% of the total variance. Finally, the scale showed good internal consistency with Cronbach coefficients, equal or above 0.84 for the total score, the recognition and the expression dimensions. This coefficient reached 0.77 for the feeling dimension but only 0.58 for the social context dimension. CONCLUSION: All together, results showed satisfactory characteristics in regard of the complexity of the notion measured. However, an important drawback is the lack of an external instrument to assess convergent validity. This instrument can be of great interest in the emotional characterization of healthy volunteers. More-over, if validated in psychiatric populations, this scale could be most useful in psychopathological assessment and also in comparison with behavioral evaluations of emotion.

[Determinants of diphemanil methylsulfate (Prantal) utilization: a survey of practice in the French neonatal and intensive care units]. / Enquête française sur l'utilisation du diphémanil méthylsulfate (Prantal) dans les unités de néonatologie.

UNLABELLED: Diphemanil methylsulfate (Prantal) is a quaternary ammonium with parasympathicolytic properties. It is used in premature and term neonates with bradycardias related to vagal hyper reflectivity (HRV). OBJECTIVES: To assess the use of Prantal in the French neonatal and intensive care units: its indications, its modalities of use, its side effects and the number of patients treated during 1 year (2004) in France. METHODS: A questionnaire was electronically sent to all neonatology units and all neonatal intensive care units in France. RESULTS: Among 202 units, 121 (60%) answered the questionnaire. Prantal was reported to be used in 51 (42.1%) units. Among them, 38 (31.4%) actually treated 169 patients in 2004 with a mean number of patients treated by unit of 4. The diagnostic of HRV was supported by: a history of malaise (84.3%), bradycardia (94.1%), oculocardiac reflex (74.5%), cardiac Holter (76.4%), cardiorespirographic recording (19.6%), esophageal pHmetry (35.2%) and esophageal fibroscopy (21.5%). The mean starting dosing was 4.7 mg/kg/d, the mean maximal dosing was 9 mg/kg/d and the mean daily intakes were initially 2.3 and secondary 2.9. Prantal dosing was adjusted to weight in 54.9%, every month in 85.7%. Treatment was stopped at the mean post-natal age of 6 months, mostly in a progressive manner and without monitoring help. CONCLUSION: Prantal was seldom used in 2004 in France for different reasons: HRV is an uncertain entity, the efficacy of Prantal has not been validated and atropinic side effects can be encountered.

Assessing multiple goods and services derived from livestock farming on a nation-wide gradient.

Livestock farming is an essential activity in many rural areas, where it contributes to the maintenance of soil fertility and farmland biodiversity, as well as to a set of social public goods including food security, rural vitality and culture. However, livestock sustainability assessments tend to focus primarily on environmental and economic dimensions; therefore, these valuations might be limited because they do not consider the complete set of associated goods and services (GS). Hence, a need exists to recognise the multiple contributions provided by livestock to human well-being and society. The objective of this study was to analyse the provision of multiple GS derived from livestock across regions in France and empirically demonstrate sets of GS that repeatedly appeared together. We designated these multiple GS provided by livestock as contributions to productive, environmental, rural vitality and cultural benefits that human populations derive directly or indirectly from livestock agroecosystems. First, we combined expert knowledge with results of a literature review to define a bundle of GS provided by livestock. We then described indicators that quantified each good or service and screened national databases to determine the availability of supporting data. Finally, we assessed the GS and their relationships (synergies or trade-offs) on a nation-wide gradient in France at the department level (Nomenclature of Territorial Units for Statistics 3). Four main categories of GS were considered: provisioning (e.g. food quantity and quality), environmental quality (e.g. biodiversity, landscape heterogeneity, water quality), rural vitality (e.g. employment, rural dynamism) and culture (e.g. gastronomy and landscape heritage). Four major types of GS bundles were identified, which suggested strong contrasts among French rural areas in terms of the nature of the GS that occurred together and their levels of provision. GS bundles in France had a non-random spatial distribution. This study represents an initial step towards developing a methodology to consider GS bundles provided by livestock. Nonetheless, further research is needed to understand socio-economic, environmental, political and geographic determinants of the composition of GS bundles.

Structure of the lateral mass of the ethmoid by curved stacking of endoturbinal elements.

CONTEXT: According to evo-devo theory, the embryonic development of the nasal organ mimics its phylontogenic formation: the lateral masses of the human ethmoid bone develop by curved "onion" stacking of the endoturbinals (the horizontal bone septa of the mammalian olfactory chamber) under the impact of facial and skull-base remodeling, rather than by pneumatization of cavities communicating via ostia. OBJECTIVES: To assess the frequency of the onion structure on coronal CT. MATERIAL AND METHODS: Three independent examiners performed a retrospective descriptive study of coronal CT scans taken ahead of septorhinoplasty between June 2010 and December 2012 in adult patients without history of sinonasal surgery. RESULTS: Fifty patients were included. In the anterior right and left and posterior right ethmoid, an onion arrangement of the endoturbinals was systematically found on at least 1 view, and on 60% of views taking all ethmoid compartments together. Two endoturbinals were generally involved, but a rolling-up of 3 endoturbinals was also observed, significantly more frequently in the posterior compartments (P=0.004 on the right side, P=0.012 on the left). CONCLUSION: The onion structure of the lateral masses of the ethmoid can be observed on coronal CT scans. This structure confirms evo-devo theory. The ethmoid thus appears fundamentally different from the paranasal sinuses, suggesting that the pathogenesis of nasal polyposis and ethmoidectomy techniques need to be reconsidered.

Inhibition of pancreatic colipase by antibodies and Fab fragments. Selective effects of two fractions of antibodies on the functional sites of the cofactor.

Rabbit antiserum was raised against porcine pancreatic colipase and Fab fragments were prepared by papain digestion of purified antibodies followed by purification on protein A-Sepharose. Fab fragments showed inactivation toward porcine colipase activity similar to that of antiserum and purified antibodies. From inactivation studies carried out by incubating porcine colipase and lipase with Fab fragments in the absence of lipid or in the presence of triolein and sodium deoxycholate, it could be concluded that polyclonal antiporcine colipase antibodies contain fractions that bind specifically to epitopes at or near the functional regions of the porcine cofactor. Studies with an enzyme-linked immunosorbent assay showed that cross-reactivity of horse or chicken colipase with antiporcine colipase antiserum was lower than that of the human or porcine protein. Results of immunoactivation kinetic studies performed with the same proteins, fully confirmed these observations. Partial cross-reactivity between porcine and chicken colipases allowed us to fractionate antibodies by immunoaffinity chromatography on immobilized chicken colipase. Fraction I contains antibodies absorbed on porcine colipase not accessible when the cofactor is bound to lipid. Antibodies of fraction II, nonadsorbed on chicken colipase, inactivate porcine colipase preincubated with triolein/deoxycholate. Lipase had a protective effect against inactivation. Antibodies of fraction II bind likely to epitopes close to the specific region of colipase interacting with lipase. Our conclusions are in good agreement with analysis of the sequence of porcine, equine and human colipases by calculating local hydrophilicity indices.