Salivary changes and dental caries as potential oral markers of autoimmune salivary gland dysfunction in primary Sjögren's syndrome

BACKGROUND: the classification criteria for primary Sjögren's syndrome (pSS) include a number of oral components. In this study we evaluated if salivary flow and composition as well as dental caries are oral markers of disease severity in pSS. METHODS: in 20 patients fulfilling the American-European Consensus criteria for pSS and 20 age-matched healthy controls whole and parotid saliva flow rates and composition, measures of oral dryness, scores of decayed, missing and filled tooth surfaces (DMFS), periodontal indices, oral hygiene, and dietary habits were examined. RESULTS: in pSS, salivary flow rates, pH, and buffer capacities were lower, and DMFS, salivary sodium and chloride concentrations higher than in the healthy controls. DMFS also correlated inversely to salivary flow rates and positively to oral dryness. Apart from slightly increased gingival index, and more frequent dental visits in pSS, the periodontal condition, oral hygiene or sugar intake did not differ between these two groups. In pSS, findings were correlated to labial salivary gland focus score (FS) and presence of serum-autoantibodies to SSA/SSB (AB). The patients having both presence of AB and the highest FS (>2) also had the highest salivary sodium and chloride concentrations, the lowest salivary phosphate concentrations, lowest salivary flow rates, and highest DMFS compared to those with normal salivary concentrations of sodium and chloride at a given flow rate. CONCLUSION: the salivary changes observed in some pSS patients reflect impaired ductal salt reabsorption, but unaffected acinar transport mechanisms, despite low salivary secretion. Our results suggest that changes in salivary flow and composition as well as dental caries may serve as potential markers of the extent of autoimmune-mediated salivary gland dysfunction in pSS. The study also indicates that the ductal epithelium is functionally affected in some pSS patients, which calls for future pathophysiological studies on the mechanisms underlying this impaired salt reabsorption

Etude de la variabilité individuelle chez le maïs à l'issue de la phase d'implantation - conséquences sur la croissance et la production de grain

International audienc

Etude de la variabilite individuelle chez le maïs a l'issue de la phase d'implantation : consequences sur la croissance et la production de grain

La croissance et le développement d’environ 400 individus, déterminés préalablement au hasard au sein d’un même peuplement de maïs au champ, ont été analysés de la levée à la récolte. La faible densité de semis limite la compétition. La levée est étalée sur 9 jours, les plantes précoces ou tardives étant de façon préférentielle localisées à proximité de plantes du même type. Les manques à la levée se retrouvent plus souvent environnés de plantes précoces. Les plantes tardives ont généralement un comportement normal quand elles sont situées en zone tardive, alors qu’elles sont pénalisées quand elles sont situées en zone précoce. Parmi les plantes levées le même jour, on observe des différences de croissance, que l’on peut rapporter à leur poids à l’origine : elles reflètent, sans doute, une variabilité existant au sein du lot de semence. Les origines de la structure observée au sein du peuplement postérieurement à la levée et l’évolution ultérieure de cette structure jusqu’au rendement individuel en grain sont discutées.Growth and development of about 400 plants randomly fixed within an experimental plot have been analyzed from emergence to grain harvest The low sowing density limits competition. Germination was spread out over 9 days. The precocious or late plants are more often located near plants of the same type. Areas lacking in germination were more frequently found surrounded by precocious plants. The late plants generally grow normally when located in a late zone, but are penalized when located in a precocious zone. Among plants which emerged on the same day we observed differences in growth, which were dependent on their weight at the beginning and which probably express the variability within the seed lot. We discuss the origins of the structure of the crop after emergence, and the subsequent evolution of this structure, until the individual grain yield

Influence du poids de la semence et de la profondeur de semis sur la croissance et le développement de la plantule de maïs

On a étudié, en conditions semi-contrôlées sous serre, la croissance et le développement de plantules de maïs selon le poids de la semence, la profondeur de semis et la variété (4). Pendant la phase hétérotrophe, la croissance de l'hydride DEA est, à peu de choses près, directement proportionnelle à la quantité de réserves de la graine utilisées depuis la germination, dans un rapport peu variable suivant les conditions (cœfficient de variation de 3,1%). Les plantules issues de grosses semences présentent une croissance nettement plus rapide, mais une efficience légèrement moindre pour l'utilisation des réserves de la graine. Les stades foliaires ou racinaires sont déterminés par l'âge de la plantule depuis sa germination, indépendamment de la taille de la semence d'origine, et, après l'apparition de la 2e feuille, indépendamment de la profondeur de semis. Les plantules issues de semis profonds utilisent un peu plus rapidement les réserves de la semence et montrent un taux de croissance supérieur. La fraction des réserves mobilisées jusqu'au passage à l'autotrophie est peu variable, autour de 65% : les plantules issues de grosses semences débutent donc leur période photosynthétique avec une plus grande quantité de réserves encore disponibles dans la semence et avec un poids supérieur d'organes chlorophylliens.Effects of seed weight and sowing depth on growth and development of maize seedlings. Growth and development of maize seedlings according to seed weight, depth of sowing and variety (4) were studied in a greenhouse. Up to 240° per d, the growth of the DEA variety is directly proportional to the amount of seed reserves which have been used since germination: the ratio shows little variation according to seed weight and sowing depth (the variation cœfficient is 3.1 %, figs 1 and 2). The slight advantage of seedlings originating from light seeds in relation to the relative amount of reserves which have been utilized during a given period of time (table I) is quite insufficient to counterbalance the much larger absolute amount used from heavy seeds. As a consequence, the seedlings originating from heavy seeds displayed rapid growth (fig 3). We found a genetical variation in the rhythm of seed reserves utilisation as follows: Monarque was more rapid, followed by DEA, F7 x F2 then Mohican (table V). These differences have consequences on the rate of growth during the heterotrophic stage, which is higher with Monarque. Unlike the growth, the development (appearance of new organs as leaves or ramifications on the radicle or lateral roots) is independent of the weight of the originating seed. It expresses the physiological age of the seedling, according to the time passed, as the sum of temperature (table II). The ratio of reserves used when a seedling starts an autotrophic life is about 65%, showing little variation. At that time, seedlings have passed the 3rd leaf stage, the advent of ramifications on lateral roots, and we observe a temporary decrease in root weight as described by Bourdu and Gregory (1983) (table III). On the deep sowing treatments, the seedlings use seed reserves more rapidly and as a consequence of this, grow faster (table IV). In these situations the emergence is comparatively delayed with shallow sowings, but this difference of stage disappears after the advent of the 1st leaf. When the ermergence takes place, the seedlings originating from light seeds sowed deeply dispose of only 45% of maternal reserves (ie 75 mg) in contrast with those from heavy seeds and shallow sowing which still dispose of 71% (ie 235 mg). In the first situation, the safety margins, in the event of adverse conditions (cold weather, excess of water, coarse seed-bed, surface crust) are restricted. On the other hand, the weight of chlorophyllian organs, when efficient photosynthesis takes place, is much higher in seedlings originating from heavy seeds rather than from light seeds: the initial state of the exponential growth is much better, and, as a consequence, this fact could induce better progress at all stages

Un stress hydrique au stade plantule a l'origine d'une necrose

National audienc

Effets de la taille des semences, de leur position sur l'épi parental et de la taille de l'épi parental sur la surface foliaire d'une culture de maïs au champ

International audienc