Cannabis for the treatment of amyotrophic lateral sclerosis: What is the patients' view?

Cannabis may have therapeutic benefits to relieve symptoms of amyotrophic lateral sclerosis (ALS) thanks to its pleiotropic pharmacological activity. This study is the first to present a large questionnaire-based survey about the "real-life" situation regarding cannabis use in the medical context in ALS patients in France. There were 129 respondents and 28 reported the use of cannabis (21.7%) to relieve symptoms of ALS. Participants mostly reported the use of cannabidiol (CBD) oil and cannabis weed and declared benefits both on motor (rigidity, cramps, fasciculations) and non-motor (sleep quality, pain, emotional state, quality of life, depression) symptoms and only eight reported minor adverse reactions (drowsiness, euphoria and dry mouth). Even if cannabis is mostly used outside medical pathways and could expose patients to complications (street and uncontrolled drugs, drug-drug interactions, adverse effects…), most of the participants reported "rational" consumption (legal cannabinoids, with only few combustion and adverse reactions). Despite some limitations, this study highlights the need for further research on the potential benefits of cannabis use for the management of ALS motor and non-motor symptoms. Indeed, there is an urgent need and call for and from patients to know more about cannabis and secure its use in a medical context.

Use of the parathyroid hormone assay at H6 post thyroidectomy: an early predictor of hypocalcemia.

PURPOSE: Hypocalcemia linked to a diminished circulating intact parathormone (iPTH) is the most common complication after total thyroidectomy. The objective of this study was to evaluate iPTH as a predictor of post-thyroidectomy hypocalcemia. METHODS: Hundred-and-eight patients who underwent total thyroidectomy were included. Blood samples (iPTH, calcium and albumin) were performed at different times: preoperatively (H0), after removal of the gland (Hdrop), 6 h (H6) and one day (D1) after the surgery. Hypocalcemia was defined by total calcium corrected by serum albumin ≤ 2.10 mmol/l. The area under the ROC curve (AUC) was used to determine the best cut-off value and predictability of iPTH for hypocalcemia in terms of absolute value (ng/L), decrease in the slope (ng/L) and decline (%) between two times. RESULTS: The study included 101 patients. Among them, 39 had hypocalcemia (38.6%). At H6, an iPTH absolute value less than 14.35 ng/L (Se = 0.706; Sp = 0.917) and a decline from the preoperative time of more than 59.5% (Se = 0.850; Sp = 0.820) were predictive of hypocalcemia. Other absolute values, decrease in the sloop and decline between preoperative and postoperative values were less relevant. CONCLUSION: The iPTH 6 h after total thyroidectomy is predictive of hypocalcemia. It might be used to identify patients not at risk of hypocalcemia and earlier discharge could be considered.

Upper limb onset of hereditary transthyretin amyloidosis is common in non-endemic areas.

BACKGROUND AND PURPOSE: The aim is to describe an uncommon phenotype of hereditary ATTR neuropathy with upper limb onset. METHODS: The French TTR Familial Amyloid Polyneuropathy database was used for a retrospective evaluation of 32 consecutive patients with upper limb onset of the neuropathy (study group) and they were compared to 31 Portuguese early-onset patients and 99 late-onset patients without upper limb onset. RESULTS: Initial upper limb symptoms were mostly sensory. Lower limb symptoms began 2.3 ± 3 years after upper limb symptoms. Twenty-four (75%) patients were initially misdiagnosed, with 15 different diagnoses. More patients in the study group had a Neuropathy Impairment Score upper limb/lower limb ratio > 1 compared to the late-onset patient group. The study group had significantly more pronounced axonal loss in the median and ulnar motor nerves and the ulnar sensory and sural nerves. On radial nerve biopsies (n = 11), epineurial vessels were abnormal in six cases, including amyloid deposits in vessel walls (3/11), with vessel occlusion in two cases. CONCLUSION: Upper limb onset of hereditary ATTR neuropathy is not rare in non-endemic areas. It is important to propose early TTR sequencing of patients with idiopathic upper limb neuropathies, as specific management and treatment are required.

Familial amyloid polyneuropathy: When does it stop to be asymptomatic and need a treatment?

Transthyretin familial amyloid polyneuropathy (FAP) is a rare disease with autosomal transmission due to point mutation of the transthyretin (TTR) gene. It is the most disabling hereditary neuropathy affecting sensory, motor and autonomic nerves, and is irreversible and fatal within 7 to 12 years of onset in the absence of therapy. Diagnosis is usually delayed for 1-5 years because the onset is usually insidious, and a positive family history is lacking in 50% of late-onset cases. Penetrance is variable, and depends of the age of the carrier and age of onset in family members. Two treatments are available: liver transplantation, to suppress the main source of systemic production of mutant TTR; and TTR tetramer stabilizer drugs, to avoid the release of highly amyloidogenic monomers and oligomers. These therapies are able to stop or slow the progression of the disease in its early stages. Genetic counseling is crucial to detect carriers at risk of developing the disease. The European network for TTR-FAP recommends careful baseline assessment by questionnaire, clinical examination and neurophysiological tests, and periodic consultations to detect the onset of disease in time to start anti-amyloid therapy after biopsy findings of amyloid deposition. A therapeutic educational program is important for improving patients' awareness. Patients are considered symptomatic and ill when they themselves perceive symptoms or changes, including changes from baseline measurements on neurophysiological tests, followed by findings of amyloid deposition on biopsy. The most sensitive biopsies are from the labial salivary gland and skin.

Management of burn wounds of the head and neck region.

Management of burn wounds of the head and neck region. Management of the severely burned patient is ery often a challenge, not only due to major disturbances in anatomy and physiological processes, but also because the relatively low incidence of this pathology in both civilian and military practice results in care providers'lack of experience. The purpose of this educational document is to provide doctors confronted with these formidable trauma patients with basic management guidelines as well as some practical tips. In summary, and most importantly, these patients should be reated as any other multitrauma patient. First aid is essential and can be provided by non-medical staff. Initial medical nanagement should focus on the usual, familiar trauma algorithms of ABCDEF from the emergency management of evere burns (EMSB) manual' or the ABCDEs of the manual of advanced trauma life support (ATLS)2 or advanced burn life support (ABLS). Medical care should proceed through the following steps - Step one: establish a reliable intravenous nfusion; step two: protect the airway; step three: establish and maintain a haemodynamic state compatible with sufficient organ perfusion in order to reduce aggravation of the burn wounds and increase overall survival likelihood; step four: provide analgesia with adequate sedation and provide anaesthesia for escharotomy, fasciotomy or other surgical injuries; step five: maintain normothermia; step six: feed the patient by starting enteral nutrition as early as possible; step seven: prevent infection using antiseptic wound management, systemic antibiotics and tetanus prophylaxis. All of these intricate steps require continuous reassessment and adjustment, but the existence of other wounds (blast injuries, penetrating and blunt trauma) even further complicates the management of burn casualties.

Surgical management of an epithelioid hemangioendothelioma of the superior vena cava protruding into the right atrium.

Epithelioid hemangioendothelioma (EH) is a rare malignant tumor of vascular origin that often involves soft tissues and visceral organs, and less commonly, large veins. We report a case of EH of the superior vena cava protruding into the right atrium and its surgical management.

Evolutionary Pathways to Break Down the Resistance of Allelic Versions of the PVY Resistance Gene va.

Emergence of viral genotypes can make control strategies based on resistance genes ineffective. A few years after the deployment of tobacco genotypes carrying alleles of the Potato virus Y (PVY) recessive resistance gene va, virulent PVY isolates have been reported, suggesting the low durability of va. To have a broader view of the evolutionary processes involved in PVY adaptation to va, we studied mutational pathways leading to the emergence of PVY resistance-breaking populations. The viral genome-linked protein (VPg) has been described to be potentially involved in va adaptation. Analyses of the VPg sequence of PVY isolates sampled from susceptible and resistant tobacco allowed us to identify mutations in the central part of the VPg. Analysis of the virulence of wild-type isolates with known VPg sequences and of mutated versions of PVY infectious clones allowed us to (i) validate VPg as the PVY virulence factor corresponding to va, (ii) highlight the fact that virulence gain in PVY occurs rapidly and preferentially by substitution at position AA105 in the VPg, and (iii) show that the 101G substitution in the VPg of a PVYC isolate is responsible for cross-virulence toward two resistance sources. Moreover, it appears that the evolutionary pathway of PVY adaptation to va depends on both virus and host genetic backgrounds.

Current knowledge and practice of Candida auris screening in France: A nationwide survey from the French Society of Medical Mycology (SFMM).

Due to large outbreaks observed worldwide, Candida auris has emerged as a major threat to healthcare facilities. To prevent these phenomena, a systematic screening should be performed in patients transferred from regions where the pathogen is highly endemic. In this study, we recorded and analyzed French mycologists' current knowledge and practice regarding C. auris screening and diagnosis. Thirty-six centers answered an online questionnaire. Only 11 (30.6 %) participants were aware of any systematic screening for C. auris for patients admitted to their hospital. In the case of post-admission screening, axillae/groins (n = 21), nares (n = 7), rectum (n = 9), and mouth (n = 6) alone or various combinations were the body sites the most frequently sampled. Only six centers (8.3 %) reported using a commercially available plate allowing the differentiation of C. auris colonies from that of other Candida species, while five laboratories (13.8 %) had implemented a C. auris-specific qPCR. Considering the potential impact on infected patients and the risk of disorganization in the care of patients, it is crucial to remember to biologists and clinicians the utmost importance of systematic screening on admission.

Reversibility of acquired amyloid polyneuropathy after liver retransplantation.

Domino liver transplantation (DLT) has become an accepted procedure designed to address problems with organ limited supply. However, cases of acquired amyloid neuropathy are increasingly being recognized following this procedure. Until now, only one patient had undergone liver retransplantation and follow-up findings were not reported. We describe the case of a 72-year-old patient with partial recovery from acquired amyloid neuropathy following retransplantation with a deceased donor 7 years after DLT performed for end-stage liver disease. His clinical and paraclinical improvement is described, and the impact of this case on the indication for a domino procedure and the challenges linked to retransplantation are discussed.

Effect on disability and safety of Tafamidis in late onset of Met30 transthyretin familial amyloid polyneuropathy.

BACKGROUND AND PURPOSE: The aim of this study was to assess the effect of Tafamidis, which slows the progression of early stages of Met30 transthyretin (TTR) familial amyloidosis polyneuropathy (FAP) in more advanced cases. METHODS: The study was a prospective, non-randomized controlled trial carried out at the French national reference centre for FAP with follow-up at 1 year. Thirty-seven consecutive Met30-TTR-FAP patients were enrolled between December 2009 and July 2011, with NIS-LL (Neuropathy Impairment Score-lower limbs) > 10 and Karnofsky score > 60. Their mean (SD) age was 56.4 (19) years. Seventy-seven per cent of patients had a walking disability. Seven patients (19%) were withdrawn for adverse effects. The primary study outcome measurements, planned before data collection began, were NIS-LL and NIS-UL (upper limbs) scores and disability scores. RESULTS: Of the 37 patients entered into the study, 29 were evaluated at 6 months and 13 at 12 months. During the first 6 months of treatment, the mean progression of NIS-LL score was 4.8 and was similar to that during the period before treatment. Among the 45% of patients without NIS-LL progression, the NIS-UL score worsened in 55%. During the first year, 55% deteriorated with respect to disability and 38% with respect to NIS only; only two patients (7%) remained stable. Four (out of 20; 20%) patients who were previously stage 1 reached stage 2 (walking with aid) after this period. Two out of nine patients who were initially normotensive developed orthostatic hypotension. There were a total of 19 adverse events, including four febrile urinary tract infections and three severe diarrhoeas, with faecal incontinence in two. CONCLUSION: In most patients with advanced Met30 TTR-FAP, Tafamidis is not able to stop disease progression, in respect of both NIS-LL and disability. Other anti-amyloid medicines should be assessed in this context.

Large-scale vibrating coil magnetometer for the magnetic characterization of bulk superconductors.

This work presents the design and validation of a vibrating coil magnetometer for the characterization of the field dependence of the critical current density of centimeter-sized bulk superconductors as an alternative to the destructive methods typically used. The magnetometer is also shown to be capable of measuring the magnetic moment in an applied field of up to 5 T for diverse magnetic materials, such as soft and hard ferromagnets and high-temperature superconducting pellets. The vibrating coil magnetometer was first optimized using finite element simulations and calibrated using a commercial vibrating sample magnetometer. The vibrating coil magnetometer was benchmarked with hysteresis measurements of a Nd2Fe14B disk made with a commercial hysteresisgraph, showing good agreement between the different setups. The magnetic hysteresis of a YBa2Cu3O7-x superconducting pellet was measured at 77 K, showing a penetration field of 1 T and an irreversibility field of 4 T. The field dependent critical current density of the superconductor was then inferred from the magnetic hysteresis measurements and extrapolated at low fields. Finally, the resulting critical current density was used to successfully reproduce the measured magnetization curve of the pellet at 2 T with finite element simulations.

Short and long-term effect of IVIg in demyelinating neuropathy associated with MGUS, experience of a monocentric study.

BACKGROUND: The optimal treatment for demyelinating neuropathy associated with MGUS and anti-MAG neuropathy is not known. METHODS: We retrospectively studied the efficacy of IVIg in 14 patients with DN-MGUS (seven IgM and seven IgG/A) and seven with anti-MAG neuropathies, treated in our reference center between 2002 and 2007. Patients were clinically evaluated before the first infusion, after the first infusion, and after the last IVIg treatment. RESULTS: Anti-MAG neuropathy: after a single infusion, one patient improved and six were stable. At last follow-up (mean: 15.6months [range: 3.5-31], mean number of IVIg courses: 8 [2-33]), one patient maintained her improvement from baseline. DN-MGUS: after a single infusion, nine patients improved (64%), four were stable and one deteriorated further. The factor predictive of short-term response to IVIg was relapsing neuropathy responding better in the walking score analysis (Fisher exact test: P=0.005). At last follow-up (mean: 22.6months [range 2-72], mean number of IVIg courses: seven [1-24]), neurological status improved in four patients, five patients remained stable, including three who are still under regular IVIg, and four had deteriorated. Improvement from baseline persisted for a prolonged period in two patients after IVIg were stopped. Patients who were responders on Norris after the first IVIg course were significantly better responders at long-term follow-up than the others (P=0.001). We report no serious adverse effect. CONCLUSION: IVIg are not very efficient in the management of anti-MAG neuropathies. Nevertheless, they have a frequent short-term beneficial effect in DN-MGUS, which was maintained at long-term follow-up in one-third of our patients. When a DN-MGUS patient is regularly treated by IVIg courses, frequent periodic clinical evaluations must be performed to determine when to stop treatment and switch to another one.

[New elements in the diagnosis and the treatment of primary AL amyloid polyneuropathy and neuropathy due to POEMS syndrome]. / Nouveautés dans le diagnostic et le traitement des neuropathies périphériques liées à l'amylose AL et au syndrome POEMS.

INTRODUCTION: Primary AL amyloid polyneuropathy (AL-PN) and neuropathy due to POEMS syndrome (POEMS-N) are rare, associated with a monoclonal gammopathy (MG) IgGλ or IgAλ at a low rate and systemic manifestations. They are invalidating and life-threatening. STATE OF THE ART: AL-PN usually mimics small fiber length-dependent axonal polyneuropathies, but also multifocal or painful neuropathies, POEMS-N corresponds to a rapid ascending CIDP with MG. To confirm the diagnosis of AL-PN, initial investigations should identify amyloidosis on nerve or accessory salivary glands, to establish the type of amyloid after serum free light-chain (FLC) measurements. For the diagnosis of N-POEMS, diagnosis is based on the presence of four criteria proposed by Dispenzieri. These neuropathies are associated with biomarkers, useful for diagnosis and treatment monitoring: elevated serum level of FLC monoclonal in (AL-PN) or VEGF (N-POEMS). PERSPECTIVES: Early diagnosis of these neuropathies and early treatment using high-dose melphalan associated with an autologous hematopoietic stem cell graft or low monthly doses can improve the clinical manifestations and patient survival. CONCLUSIONS: Systematic search for monoclonal gammopathy by immunofixation and serum free light chains is very useful for the management of progressive peripheral neuropathies of unknown origin.

[Survey on the medical mycology processes to the members of the French Society for Medical Mycology]. / Enquête sur les conditions analytiques d'un examen de mycologie médicale auprès des membres de la Société française de mycologie médicale.

AIM OF THE STUDY: The objective of the survey was to describe the practices of clinical laboratories in terms of cultures in medical mycology. We have implemented this project within the members of the French Society for Medical Mycology (SFMM) to evaluate the analytical processes of the mycological examination in our laboratories. This preliminary study would help to suggest the future French guidelines. MATERIALS AND METHODS: A questionnaire regarding the processing of mycology analysis was sent to the 227 members of the SFMM in 2009. The data involved 21 types of samples, direct microscopic examination with or without colouring and the reagents, the number of culture media, the types of media (Sabouraud, Sabouraud antibiotic, Sabouraud cycloheximide and chromogenic medium), temperature and duration of the incubation (days) and the existence of a first result before the end of the incubation period. The analytical processes were compared to an accredited laboratory according to EN ISO 15189. RESULTS: A great heterogeneity was observed in the 36 forms from 27 (75%) laboratories belonging to university hospitals among the 38 existing in France. As for deep samples, two microscopic exams were performed, only one was usually done. A more sensitive technique was preferred to the wet-mount for some samples. Routine samples are often inoculated on a chromogenic media. For deep samples two medium are inoculated (chromogenic media, Sabouraud and antibiotics). If the temperature of incubation is unique, 30°C was chosen. A temperature of 37°C was preferred for samples where Candida spp. is selected. When there are two temperatures of incubation, 27°C and 37°C were preferred. CONCLUSION: Each biologist can compare his proceedings to the other laboratories and to a laboratory already accredited. The question is to find the best strategies for each medical mycology specimen. They will aid the process of accreditation according to EN ISO 15189, which now applies in all laboratories in Europe.

[Quality controls in medical mycology]. / Les contrôles de qualité en mycologie médicale.

The Quality Management System in medical mycology refers to the systematic monitoring with internal and external quality controls: it needs to be organized in the laboratory. ISO 15189 standard is not precise in how to demonstrate the correctness of tests, in terms of frequency and requirements for quality controls QC. That's why the COFRAC, the French Accreditation Committee has published guides to which we should refer. The laboratory has to apply internal Quality Control Programs. They consist of various tests to check the reagents including the culture media. Reference strains have to be provided and preparations of homemade reagents are needed, because few are commercialized. Maintaining the competence of the technical staff through identification of unknown strains is also required. In the fungal serology field, home made antibodies with pooled sera or antigen controls are needed. This monitoring has to follow the recommandations from the Cofrac technical guide LAB GTA 06. For quantitative analysis, the Levey-Jennings chart is a graph with quality control data plotted on to give a visual indication. Some external QC references, besides the national quality control AFSSAPS, are available. Data evaluation, corrective actions in case of out of range results and preventive actions have to be determined in the Quality System documents and presented in the annual management review.

The invasion route for an insect pest species: the tobacco aphid in the New World.

Biological invasions are rapid evolutionary events in which populations are usually subject to a founder event during introduction followed by rapid adaptation to the new environment. Molecular tools and Bayesian approaches have shown their utility in exploring different evolutionary scenarios regarding the invasion routes of introduced species. We examined the situation for the tobacco aphid, Myzus persicae nicotianae, a recently introduced aphid species in Chile. Using seven microsatellite loci and approximate Bayesian computation, we studied populations of the tobacco aphid sampled from several American and European countries, identifying the most likely source populations and tracking the route of introduction to Chile. Our population genetic data are consistent with available historical information, pointing to an introduction route of the tobacco aphid from Europe and/or from other putative populations (e.g. Asia) with subsequent introduction through North America to South America. Evidence of multiple introductions to North America from different genetic pools, with successive loss of genetic diversity from Europe towards North America and a strong bottleneck during the southward introduction to South America, was also found. Additionally, we examined the special case of a widespread multilocus genotype that was found in all American countries examined. This case provides further evidence for the existence of highly successful genotypes or 'superclones' in asexually reproducing organisms.

Assessment of tumor angiogenesis as a prognostic factor of survival in patients with oligodendroglioma.

According to World Health Organization (WHO) and Daumas-Duport grading systems, progression of oligodendrogliomas (ODGs) to a higher grade (WHO grade III, grade B) is associated with increased angiogenesis. Based on multivariate assessment of molecular, pathological, and radiological parameters, we further assessed the influence of tumor angiogenesis on tumor progression and patient survival. Patients with a diagnosis of ODG, consecutively treated in a single institution, were reviewed and reclassified according to WHO and Daumas-Duport grading systems. MRI scans were reviewed to assess contrast enhancement and necrosis. Tissue sections were used for pathology review and to evaluate immunostaining of vascular endothelial growth factor (VEGF), vascular endothelial growth factor receptor (VEGF-R), Ki-67, and CD34. Multivariate analysis was performed to assess the impact of tumor angiogenesis-related pathological and radiological factors on patient survival. One hundred thirty-four patients with pure ODG were included in this study. Multivariate analysis identified four independent poor prognostic factors: necrosis, absence of seizure, increased vascularization, and age >55 years. A subgroup of patients with tumor necrosis, increased vascularization, and absence of seizures had a significantly worse outcome than predicted, with a median overall survival of 14.2 months. VEGF expression was significantly higher in this subgroup and correlated with disease progression regardless of histologic grade. Based on the presence of radiological or pathological necrosis, contrast enhancement or endothelial hyperplasia, and absence of seizures, a high risk group of ODG can be identified with significantly worse overall survival. Also, VEGF over-expression in ODG constitutes an early marker for predicting tumor progression.

Microvascular leakage and contrast enhancement as prognostic factors for recurrence in unfavorable low-grade gliomas.

Perfusion estimates and microvascular leakage (MVL) were recently correlated with glioma angiogenesis and aggressiveness, but their role in predicting outcome of patients (pts) with unfavorable low-grade gliomas (ULGG) is unclear. Their prognostic value was then investigated, versus conventional factors such as age, neurological status, tumor size, and contrast enhancement (CE). Clinical and anatomical magnetic resonance imaging (MRI) criteria of a cohort of ULGG pts were prospectively evaluated. A dynamic T2*-weighted MR sequence was included to detect high-perfusion areas, using the maximal value of the relative cerebral blood volume (rCBV) estimate, and MVL. Conventional and microvascular characteristics were correlated with progression-free survival (PFS). Among the 46 pts included, the following features were present in 61%, 26%, 67%, and 26%, respectively: age >or=40 years, neurological deficits, tumor size >or=6 cm, and CE. High perfusion value was noted in 30% of cases and MVL in 52%. With median follow-up of 22 months (range 4-46 months), median PFS was 32 months [95% confidence interval (CI) 17-45 months]. On univariate analysis, CE, rCBV, and MVL were significantly correlated with PFS. On multivariate analysis, only CE and MVL were unfavorable factors, with hazard ratio of 3.0 and 7.3 and P value of 0.04 and 0.02, respectively. Different prognostic subgroups were identified, with 2-year PFS of 86%, 57%, and 19% for pts with no MVL, MVL without CE, and MVL with CE, respectively. MVL and CE seem to predict short-term outcome in ULGG pts.

Comparative study of a new quantitative real-time PCR targeting the xylulose-5-phosphate/fructose-6-phosphate phosphoketolase bifidobacterial gene (xfp) in faecal samples with two fluorescence in situ hybridization methods.

AIMS: To detect and enumerate bifidobacteria in faeces with a new quantitative multiplex real-time PCR (qPCR) method and to compare the results obtained with fluorescence in situ hybridization (FISH) methods. METHODS AND RESULTS: A multiplex qPCR assay was developed, which enabled the enumeration of Bifidobacterium spp. by targeting the bifidobacterial xylulose-5-phosphate/fructose-6-phosphate phosphoketolase gene (xfp) and total bacteria using universal Eub-primers targeting 16S rRNA gene from the domain bacteria. The qPCR assay showed high sensitivity and specificity and a low detection limit of about 2.5 x 10(3) bifidobacterial cells per gram of faeces. The qPCR results were compared with FISH combined with microscopy or flow cytometry (FCM). No statistical differences among bifidobacterial counts averages measured in adult faeces with the three methods were observed. Total bacterial count averages were higher with the FISH method coupled with microscopic analyses compared to FISH with FCM, whereas total cell numbers estimated by qPCR were intermediate between the two FISH methods. CONCLUSIONS: The new qPCR assay was shown to be sensitive, rapid and accurate for enumerating bifidobacteria in faeces. SIGNIFICANCE AND IMPACT OF THE STUDY: This method is a valuable alternative for other molecular methods for detecting faecal bifidobacteria, especially when their counts are below the detection limit of the FISH methods.

Study of the physicochemical and biological stability of pediocin PA-1 in the upper gastrointestinal tract conditions using a dynamic in vitro model.

AIMS: To evaluate the survival of Pediococcus acidilactici UL5 and its ability to produce pediocin PA-1 during transit in an artificial gastrointestinal tract (GIT). To investigate the physicochemical and biological stability of purified pediocin PA-1 under GIT conditions. METHODS AND RESULTS: Skim milk culture of Ped. acidilactici UL5 was fed to a dynamic gastrointestinal (GI) model known as TIM-1, comprising four compartments connected by computer-controlled peristaltic valves and simulating the human stomach, duodenum, jejunum and ileum. This strain tolerated a pH of 2·7 in the gastric compartment, while lower pH reduced its viability. Bile salts in the duodenal compartment brought a further 4-log reduction after 180 min of digestion, while high viable counts (up to 5 × 10(7) CFU ml(-1) fermented milk) of Ped. acidilactici were found in both the jejunal and ileal compartments. Pediococcus acidilactici recovered from all four compartments was able to produce pediocin at the same level as unstressed cells. The activity of the purified pediocin in the gastric compartment was slightly reduced after 90 min of gastric digestion, while no detectable activity was found in the duodenal, jejunal and ileal compartments during 5 h of digestion. HPLC analysis showed partial degradation of the pediocin peptide in the duodenal compartment and massive breakdown in the jejunal and ileal compartments. CONCLUSIONS: Pediococcus acidilactici UL5 showed high resistance to GIT conditions, and its ability to produce pediocin was not affected, suggesting its potential as a probiotic candidate. The physicochemical and biological stability of pediocin was significantly poor under GIT conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: Pediococcus acidilactici UL5 appears to be a potential probiotic candidate because its capacity to produce pediocin PA-1 is not affected by the GI conditions as well as the strain shows an acceptable survival rate. Meanwhile, purified pediocin PA-1 losses activity during GIT transit; microcapsules could be used to deliver it to the target site.