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In order to develop a biopreservation strategy in cold-smoked salmon, the inhibitory capacity of 3 bacteriocin-producing Carnobacterium strains isolated from fish have been tested towards Listeria monocytogenes strains. C. divergens V41 maintains the level of Listeria below 50 CFU/g in sterile cold-smoked salmon during the 28 days of vacuum storage at 4 and 8°C, thanks to the divercin V41 action. For its use in the product, the culture of the strain was optimized in a growth medium without animal protein. On commercial cold-smoked salmon slices, the strain inhibits slightly the endogenous microflora and doesn't modify the sensorial quality, but it produces tyramine, a biogenic amine. A non-producing tyramine mutant was obtained by chemical mutagenesis. This mutant was characterized and showed no enzymatic activity due to a stable mutation in the structural gene of tyrosine decarboxylase (1863 bp). The mutant C. divergens V41A8 has the characteristics of a good biopreservation agent., Traditionnellement utilisé pour la conservation, le procédé de salage-fumage du saumon, désormais surtout appliqué à des fins organoleptiques, met en oeuvre des traitements de plus en plus allégés. Cette tendance, associée à une conservation réfrigérée sous vide assez longue et au fait que le produit est consommé cru, engendre un risque sanitaire lié à la présence et la croissance possible de Listeria monocytogenes dans le produit. Ce projet de thèse consiste à développer une stratégie de biopréservation du saumon fumé vis à vis du risque L. monocytogenes, tout en garantissant la qualité organoleptique des produits. Dans un premier temps, les capacités d'inhibition de trois souches productrices de bactériocine, Carnobacterium piscicola SF668 et V1 et Carnobacterium divergens V41 sont étudiées vis-à-vis d'une large gamme de souches de Listeria monocytogenes isolées du saumon fumé et des ateliers de production. Ensuite, le potentiel d'altération de ces trois souches est testé sur saumon fumé stérile. A l'issue de ces études, C. divergens V41, la souche la moins altérante montrant le profil d'inhibition le plus intéressant est sélectionnée pour être ensemencée sur des lots de saumon fumé du commerce. La souche ne modifie pas ou peu les caractéristiques organoleptiques du produit et inhibe légèrement les flores endogènes responsables de l'altération organoleptique présentes naturellement sur les produits. De plus, l'activité anti-listeria est démontrée par la seule production de divercine V41 grâce à l'obtention d'une souche de C. divergens V41 non productrice de bactériocine. Parallèlement, la culture de C. divergens V41 est optimisée en fermenteur dans un milieu de culture dépourvu de protéines d'origine animale en vue de son utilisation potentielle dans les poissons fumés. Le second objectif est d'approfondir les connaissances sur les activités de décarboxylation d'acides aminés par les souches de Carnobacterium, pouvant conduire à la production d'amines biogènes indésirables. La tyramine, issue de la décarboxylation de la tyrosine, est la seule amine produite par les Carnobacterium dans le saumon fumé. Un mutant tyramine négatif de la souche sélectionnée dans la première partie des travaux, et appelé C. divergens V41A8, a été obtenu par mutagenèse chimique afin qu'il soit utilisable dans le saumon fumé d'un point de vue réglementaire. Le gène de structure de la tyrosine décarboxylase (TDC) a ensuite été mis en évidence et séquencé chez la souche sauvage et chez le mutant (1863 pb). L'observation d'une transition G?A au niveau d'un nucléotide a conduit à l'apparition d'un codon stop chez le mutant, expliquant ainsi la stabilité de ce dernier. De plus, la souche C. divergens V41A8 présente des caractéristiques d'inhibition et d'altération similaires à celles de la souche sauvage. L'ensemble de ces caractéristiques, associé au fait que C. divergens V41A8 soit incapable de produire de la tyramine, font que cette souche est également un bon candidat comme agent de biopréservation des poissons fumés. Parallèlement, le séquençage du gène de structure de la TDC permet d'enrichir les données génétiques concernant la tyrosine décarboxylase des bactéries, notamment pour développer des outils moléculaires de détection ou de quantification des microorganismes producteurs de tyramine dans les aliments.

Effects of Eutypa lata, the fungal agent of eutypiosis, on polyamine (putrescine (Put), spermidine (Spd), spermine (Spm), diaminopropane (Dap)) and tyramine (Tyr) contents in grapevine leaves were studied to determine the relationship between these components and disease development. The external symptoms of eutypiosis are small and necrotic leaves, which could be observed on only one arm or on two arms of the vine stock. This study was carried out on healthy leaves (S, borne by healthy vine stock), apparently healthy leaves (Aps, borne by one arm without symptoms, whereas the other arm was diseased), and moderately (M. mal.) and strongly (F. mal.) diseased leaves. We analysed free polyamines (free PAs, chlorhydric acid soluble fraction), conjugated polyamines (PAs-fpm, PAs covalently linked to molecules with low molecular mass like hydroxycinnamic acids), and bound polyamines (PAs-mm, covalently linked to macromolecules) in Vitis vinifera L. 'Cabernet sauvignon', a variety sensitive to eutypiosis. In diseased leaves, we noted a decrease of free PAs, PAs-fpm, free Tyr, and Tyr-fpm levels. By contrast, the Dap-fpm level was increased by the disease. Eutypiosis also induced an increase of Spm-mm and Dap-mm levels, whereas the Put-mm and Spd-mm levels were decreased. Free Put, free Spd, PAs-fpm, free Tyr, and Tyr-fpm levels were higher in apparently healthy leaves than in healthy leaves. The PAs-mm levels were slightly affected by eutypiosis in apparently healthy leaves. The specific role of each type of polyamines and tyramine is discussed with regard to the host-parasite relationship.Key words: polyamines, leaf, Eutypa lata, Vitis vinifera.

In the catalyzed reporter deposition technique, horseradish peroxidase catalyzes the activation of conjugated phenolic compounds resulting in the covalent binding of the radicalized intermediates to electron rich moieties in the protein molecules present at the site of reaction. Comparing the biotinyl-, digoxigeninyl-, and fluoresceinyl-derivatives of tyramine and four immunohistochemical formats, we showed that the most sensitive detection system was that using biotinyl-tyramide and an immunohistochemical technique using a biotinylated secondary antibody followed by a streptavidin peroxidase. Amplification without background staining was obtained in most biotin rich tissues with digoxigeninyl-tyramide. With fluoresceinyl-tyramide, clear signal amplification was observed in the fluorescent microscope. Finally, when compared with standard methods, increased sensitivity was obtained with the fluorescent derivative for detection of hybridized sequences in interphase chromosomes.

Early chronic sympathectomy does not normalize blood pressure (BP) in genetically hypertensive rats of the Lyon strain (LH). The purpose of this study was to examine the role of the renin angiotensin system (RAS) and vasopressin in the residual hypertension exhibited by LH sympathectomized rats. Chronic sympathectomy was achieved by treating male LH and control normotensive LN rats with guanethidine sulfate between 1 and 13 weeks of age (60 mg/kg daily from day 7 after birth to day 25, 30 mg/kg daily from day 26 to day 70 and 30 mg/kg every other day from day 71 to day 90). At 14 weeks of age, catheters were inserted into the lower abdominal aorta and inferior vena cava via the left femoral artery and vein. After 2 days of recovery, BP was continuously recorded in the conscious freely moving animals during 3 consecutive 1-hour periods: before and after administration of either an angiotensin converting enzyme inhibitor (perindopril 2 mg/kg i.v.) or a selective vascular vasopressin antagonist [beta-mercapto- beta,beta-cyclopentamethylenepropionyl1, O-Me-Tyr2, Arg8-vasopressin, AVPX 10 micrograms/kg i.v.) and finally after conjoint administration of both drugs. At the end of each period, the efficacy of blockade was verified by the disappearance of pressor responses to respective agonists (angiotensin I 150 ng/kg i.v., Arg8-vasopressin 10 ng/kg i.v.). Chronic treatment with guanethidine resulted in the disappearance of pressor responses to tyramine (250 micrograms/kg i.v.) indicating complete functional denervation of the vessels. Under basal conditions, the 1-hour average value of mean BP (MBP) was higher in LH than in LN sympathectomized rats (134 +/- 3 vs 104 +/- 2 mmHg, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

The ability of endogenous myocardial catecholamines to participate in the development of myocardial cellular alterations during a short period of severe hypoxia (30 min) was studied in isolated, Langendorff-perfused rat heart preparation, arrested by a high potassium concentration (16 mM) and perfused in the absence of exogenous substrate (Table I). Tyramine, which accelerated catecholamine depletion, also increased myocardial cell damage as assessed by a higher lactate dehydrogenase (LDH) release and a more marked reduction in cellular levels of high energy phosphates and glycogen (Table II). On the other hand, under conditions of beta-blockade (atenolol), hypoxia-induced tissular damage was reduced (Table II). These changes could be related to modifications in the cellular content of cyclic AMP (cAMP) since cAMP was consistently higher during the first 30 min of hypoxic perfusion than in control normoxic hearts (Table III) whereas cyclic GMP content remained unchanged. Moreover, interventions increasing cellular content of cAMP (theophylline, dibutyryl-cAMP) also increased hypoxic damage (Table IV), whereas N-methyl imidazole which reduced cellular content of cAMP lessened hypoxia-induced cellular alterations (Table IV). It is concluded that cellular lesions developing during the first 30 min of hypoxia in isolated arrested rat heart preparation perfused without exogenous substrate could be related to intracellular accumulation of cAMP occurring under the effect of endogenous catecholamine release.

Summary The chicken digestive tract is mainly colonized by bacteria belonging to the Lactobacillus genus. One of these strains (LEM-207) isolated from the crop of a cock and closely resembling L. acidophilus, was able to develop on a carbohydrate-free medium. Production of carbon dioxide and synthesis of tyramine, putrescine and cadaverine were observed in the cultures. Once implanted in the crops of germ-free chickens, strain LEM-207 led to the formation of amines. In germ-free (axenic) animals, only endogenous tyramine was detected, whereas in monoassociated chickens, we found a production of tyramine, cadaverine and putrescine. The concentrations of cadaverine and putrescine decreased with increasing acidification of the contents, whereas the level of tyramine increased (7-fold higher level than in germ-free chicken). Amine production was not detected in the c˦ca. The toxicological aspects of tyramine production in terms of the animal are discussed.

Metabolic and hormonal tests to assess plasma renin, aldosterone, and catecholamine activity were conducted in three patients with idiopathic orthostatic hypotension. Blood pressure readings were then taken in decubitus and orthostatism during treatment with 10 to 15 mg of tyramine and 30 mg of tranylcypromine. Marked functional improvement was observed, with an increase in mean blood pressure in decubitus and a less marked reduction in orthostatism avoiding the onset of severe discomfort. Therapeutic indications are limited, however, because of a possible hypertensive response.

MR imaging and CT myelography were compared in a retrospective study of 38 patients with suspected lesions of the cervical and thoracic spinal canal and cord. Twenty-eight abnormal cases were found, including spondylosis (9), tumors (8), intramedullary cavities (3), arachnoiditis (3), disk-space-centered infection or osteomyelitis (2), nonneoplastic cord swelling (2), and CSF-borne metastasis (1). MR was equal or superior to CT myelography in depicting cases of cord enlargement, cord compression, and cord atrophy, providing better tissue characterization, no shoulder artifact, and no limitation caused by CSF block. CT myelography was superior to MR in depicting cases of spondylosis and arachnoiditis. It showed superior spatial resolution, which was most pronounced when comparing axial images and hence particularly superior in detecting the lateral extent of disk herniation. Use of surface coils and thin imaging sections is essential for accurate and complete MR evaluation of the cervical and thoracic spine.

Paroxystic hypertension was observed in two patients receiving isoniazide treatment, after they had ingested gruyere cheese. It is highly probable that isoniazide was responsible, as hypertension did not reoccur under the same conditions after interrupting treatment. One patient developed a vasomotor reaction identical to that which sometimes occurs after the eating of foods rich in tyramine by patients taking monoamine oxydase inhibitors. It could be that in our patients this phenomenon was consecutive to the inhibition of plasma monoamine oxydase by the isoniazide. It was not due to an overdose of isoniazide. This unusual reaction suggest that patients taking isoniazide should be questioned whether they have had post-prandial vasomotor flushes, and if so, advised to avoid foods rich in tyramine.

Three cases of primary amyloidosis and 2 cases of familial amyloidosis complicated by asympathicotonic orthostatic hypotension are reported. Blood pressure measurements on a tilting table, plasma renin activity and plasma aldosterone or catecholamine concentrations enabled localisation of the lesion of the baroreceptor reflex in some cases. When the pre- and post-synaptic efferent sympathetic pathway was intact, treatment associating Tyramine and Tranylcypromine may provide these bedridden patients some autonomy of movement. When this pathway is affected by the disease the association of Indomethacin, Dihydroergotamine and 9-alpha-fluorohydrocortisone may be tried.