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Longitudinal infection data on Mycobacterium avium subspecies paratuberculosis (MAP) was collected on three dairy farms in Northeastern United States during approximately 10 years. Precise data on animal characteristics and animal location within farm were collected on these farms. Cows were followed over time with regard to MAP status during biannual fecal and serum sampling and quarterly serum sampling. Approximately 13 000 serum samples, 6500 fecal samples and 2000 tissue samples were collected during these years. Prevalence of positive samples was 1.4% for serological samples, 2.2% in fecal samples and 16.7% in tissue samples. Infection dynamics of MAP was studied and resulted in a number of potential changes in our understanding of MAP infection dynamics. First, a high prevalence of MAP infection was observed in these herds due to lifetime follow up of cows, including slaughter. Second, two distinctly different infection patterns were observed, so called non-progressors and progressors. Non-progressors were characterized by intermittent and low shedding of MAP bacteria and a virtual absence of a humoral immune response. Progressors were characterized by continuous and progressive shedding and a clearly detectable and progressive humoral immune response. Strain typing of MAP isolates on the three farms identified on two of three farms a dominant strain type, indicating that some strains are more successful in terms of transmission and infection progression. Continuous high quality longitudinal data collection turned out to be an essential tool in our understanding of pathobiology and epidemiology of MAP infections in dairy herds.

Chem. 63, 2633 (1985).The kinetics of autoxidation of linoleic acid in dimyristoylphosphatidylcholine (DMPC) bilayers were studied at 30°C and pH 7 under 760 Torr 02. Reactions were initiated using either the lipid-soluble di-tert-butylhyponitrite (DBHN) or watersoluble azobis(2-amidinopropane) . HCI (ABAP). Rates of chain initiation, R i , were measured with a lipid-soluble antioxidant, a-tocopherol, or a water-soluble one, 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxyate (Trolox). The slightly higher oxidizability pbtained (kp/2k$ = 2.76 x lo-' M-i s-4 compared to methyl linoleate in chlombenzene (kp/2k$ = 2.18 x ]0-2 M-i -2 s 3 is attributed to a moderate polar solvent effect on ionized linoleate near the bilayer surface. A low initiator efficiency, e = 0.0895 for DBHN in DMPC, is attributed to the cage effect in the bilayer of high microviscosity. Similar autoxidation experiments on methyl linoleate in DMPC bilayers gave a lower oxidizability (kp/2k) = 1.79 x lo-' M-i s-i), indicating that the ester is sequestered deeper in the hydrophobic region of DMPC than is ionized linoleate. Some absolute rate constants are determined using the rotating sector technique for linoleic acid in 0.50 M SDS micelles, and egg lecithin and dilinoleoylphosphatidylcholine (DLPC) bilayers. A hundredfold decrease in the termination rate constant, 2k,, for DLPC bilayer compared to homogeneous solution is attributed to chain termination in a bilayer region of high polarity. A concomitant reduction (up to tenfold) in the propagation rate constant, k,, is attributed to diffusion of polar peroxyl radicals away from the oxidizable region of the bilayer.LAWRENCE ROSS COATES BARCLAY, STEVEN JEFFREY LOCKE, JOSEPH MARK MACNEIL et JOANN VANKESSEL. Can. J. Chem. 63, 2633 (1985).Opt5rant h 30°C, i un pH de 7 et sous une pression de 760 Torr d'02, on a ttudiC la cinktique de I'auto-oxydation de I'acide IinolCique dans des couches doubles de dimyristoylphosphatidylcholine (DMPC). On a initie les reactions i I'aide soit de I'hyponitrite du di-tert-butyle (HNDB) qui est soluble dans les lipides soit le chlorhydrate de I'azo bis(amidin0-2 propane) (ABAP) qui est soluble dans I'eau. On a mesure les vitesses d'initiation de chaines, Ri, en presence d'un antioxydant soluble dans I'eau, I'a-tocophCrol, ainsi que d'un antioxydant soluble days I'eau, I'hydroxy-q tt5pamethyl-2,5,7,8 chromanecarboxylate-2 (Trolox). L'oxyd,abifite est 1Cgkrement supt5rieure (k,/2k? = 2,76 x lo-' M-7 s-3 h celle du linoleate de mCthyle (kp/2k,3 = 2,18 x lo-' M-i s-3; on attribue ce resultat h une influence modCree du solvant polaire sur le linoltate ionis6 prks de la surface i couche double. On attribue la faible efficacitk comme initiateur, e = 0,0895, du HNDB dans le DMPC i un effet de cage dans la double couche qui aurait une microviscositC ClevCe. Des experiences semblables d'a~to~oxydation sur le linolkate de mCthyle dans des doubles couches de DMPC donnent lieu i des oxydabilites plus faibles (kp/2k,5 = 1,79 x M-f s-$; ce rksultat indiquerait que I'ester est plus sequ...

Mittels 31P‐ NMR‐Spektroskopie bei Verwendung von Pr3+ als Verschiebungsreagens wird gezeigt, daß die Phospholipide Dipalmitoylphosphatidylcholin (I), Dilinoleoylphosphatidylcholin (II) und Eilecithine (III) in den organischen Lösungsmitteln Benzol, Chlorbenzol und o‐Dichlorbenzol aggregieren, und zwar mit einer Aggregationszahl von 80‐100, wenn das molare Verhältnis von H2O/Phospholipid 20/1 beträgt.

. 64, 2103 (1986). Dicumylhyponitrite (DCHN) was used as a thermal initiator of autoxidation of unsaturated phosphatidylcholines in o-dichlorobenzene and in mixed bilayers of dilinoleoylphosphatidylcholine (DLPC) with dimyristoylphosphatidylcholine (DMPC). Quantitative studies were made of the products, a,a-dimethylbenzyl alcohol (DMBA), acetophenone (AP), and dicumylperoxide (DCP) from DCHN. The ratio DMBAIA2DCHN (37 rt 6%) indicates the effectiveness of cumyloxy in hydrogen abstraction from the phospholipid in solution. The overall efficiency (e) of DCHN determined by the inhibitor method with a-tocopherol (a-T) was 84 * 596, close to the overall ratio (DMBA + AP)/A2DCHN (90 rt 6' 361, and indicates either significant initiation through the methylperoxy radical in o-dichlorobenzene solution or that a-tocopherol traps cumyloxy radical before @-scission occurs. The thermal decomposition rate constant of DCHN is greatly reduced in a medium of high viscosity; in DLPC to one-quarter, in Nujol to one-sixth that in isooctane and this is interpreted in terms of a one-bond scission of DCHN. In DLPC + DMPC mixed bilayers the effectiveness of the cumyloxy radical to initiate reaction varied from 30 to 19% depending on the amount of DLPC and in this medium there is little or no initiation by methylperoxy according to product analysis and a-T inhibition studies. In mixed bilayers, the rate of oxidation was directly related to the [DLPC] indicating that the classical rate law applies. The oxidizability of DLPC in mixed bilayers (0.046 M I J 2 s ' " ) is comparable to that of neat DLPC.LAWRENCE ROSS COATES BARCLAY, DAVID KONG et JOANN VANKESSEL. Can. J. Chem. 64. 2103 (1986).On a utilisC l'hyponitrite de dicumyle (HNDC) comme initiateur thermique pour l'autooxydation de phosphatidylcholines non-saturts dans le o-dichlorobenzene et dans des doubles couches mixtes de dilinolCylphosphatidylcholine (DLPC) et de dimyristoylphosphatidylcholine (DMPC). On a rCalisC des etudes quantitatives des produits : l'alcool a , a-dimCthylbenzylique [Traduit par la revue]