Effect of Feed Restriction on Performance and Postprandial Nutrient Metabolism in Pigs Co-Infected with Mycoplasma hyopneumoniae and Swine Influenza Virus

As nutritional status and inflammation are strongly connected, feeding and nutritional strategies could be effective to improve the ability of pigs to cope with disease. The aims of this study were to investigate the impact of a feed restriction on the ability of pigs to resist and be tolerant to a coinfection with Mycoplasma hyopneumoniae (Mhp) and the European H1N1 swine influenza virus, and the consequences for nutrient metabolism, with a focus on amino acids. Two groups of specific pathogen-free pigs were inoculated with Mhp and H1N1 21 days apart. One group was fed ad libitum, the other group was subjected to a two-week 40% feed restriction starting one week before H1N1 infection. The two respective mock control groups were included. Three days post-H1N1 infection, 200 g of feed was given to pigs previously fasted overnight and serial blood samples were taken over 4 hours to measure plasma nutrient concentrations. Throughout the study, clinical signs were observed and pathogens were detected in nasal swabs and lung tissues. Feed-restricted pigs presented shorter hyperthermia and a positive mean weight gain over the 3 days post-H1N1 infection whereas animals fed ad libitum lost weight. Both infection and feed restriction reduced postprandial glucose concentrations, indicating changes in glucose metabolism. Post-prandial plasma concentrations of the essential amino acids histidine, arginine and threonine were lower in co-infected pigs suggesting a greater use of those amino acids for metabolic purposes associated with the immune response. Altogether, these results indicate that modifying feeding practices could help to prepare animals to overcome an influenza infection. Connections with metabolism changes are discussed.     

Phencyclidine-induced depressions of cerebellar purkinje neurons

Local administration of phencyclidine (PCP) by pressure ejection elicited a dose-dependent slowing of the spontaneous discharge of cerebellar Purkinje neurons. Ketamine also depressed firing and was much less potent than PCP. Effects of both PCP and ketamine were antagonized by local or parenteral administration of antipsychotic drugs. The similarities between the electrophysiological and behavioral actions of phencyclidine suggest that alterations in neuronal discharge may underlie its psychotomimetic properties.     

Attachment of blastocysts to lens capsule: A model system for trophoblast-epithelial cell interaction on a natural basement membrane

Summary The bovine lens capsule has previously been shown to provide an optimal surface for the examination of epithelial cell interaction with a basement membrane. This native substrate has been used to investigate some initial aspects of attachment of mouse blastocysts and trophoblastic cellular outgrowth. Mouse blastocysts were presented to the cell-free humoral side of the anterior lens capsule, incubated for 72 h, and examined by scanning and transmission electron microscopy. Blastocysts hatch and attach from their zonae pellucidae by 30 h. Trophoblastic cells proliferate rapidly in a coronal direction, display extensive surface microvilli, and advance by the extension of numerous filipodia, many of which terminate with bulbous projections. These projections were shown by transmission electron microscopy to contain numerous vacuoles and polysomes. To simulate further the initial blastocyst-uterine interaction, a suspension of lens epithelial cells was introduced to the capsule and permitted to form a monolayer prior to the addition of the blastocysts. At 72 h the monolayer of lens cells remained intact. We observed that: a) lens cells appear to recede from the advancing trophoblastic cells, and b) trophoblastic cells extend beneath the monolayer of lens cells and thereby dislodge the cells from the lens capsule substrate. No infiltration of the capsule by the advancing trophoblastic cells was observed. The lens capsule appears to offer a promising system for the study of trophoblast-epithelial cell interaction on a natural basement membrane.     

Biochemical and phenotypical correction of an envelope mutant of Salmonella typhimurium

Salmonella typhimurium DA 361 bears an env D1 mutation with the following abnormal phenotypical and biochemical characteristics: a) it autolyses at stationary phase in nutrient broth; b) it grows in chains of short rods; c) it is a poor maltose fermenter and d) it has a diphosphatidylglycerol (DPG) content twice as high than its isogenic non-lytic pair DA 362 (env D+) and LT2, of which both are derivatives. Growth of DA 361 in the presence of 400 mM ethanol leads on a 50% decrease of DPG level, thereby equalling its PG/DPG ratio with those of the control strain. Consequently, a correction on the other phenotypical and biochemical anomalies are induced since the DA 361 strain decreases its autolytic activity, ferments normally maltose and appear as rods undifferentiated from DA 362.     

Characteristics of the maintenance of the upright posture in subjects touching an external object while standing on a moving or immobile platform

Postural sway was compared for humans touching an external object while standing on an immobile or slowly moving posturographic platform. When the platform moves, the central nervous system may interpret the movement of the point of the contact with the external object as the movement of the body relative to the support or as the movement of the support itself. Thus, the information concerning the body position that is provided by the touch becomes ambiguous. It was demonstrated that contact with an external object during standing on an unstable support leads to a decrease in support sway. When a subject stands on a moving platform, this decrease is smaller than in the case of an immobile platform. Contact with an external object causes a decrease in postural responses to shank muscle vibrations on an immobile platform. On a moving platform, this decrease is nonsignificant. The change in postural sway depending on the unambiguity of afferent information is discussed in terms of the interaction between afferent signals of different modalities on the basis of the body scheme in subjects maintaining balance.Translated from Fiziologiya Cheloveka, Vol. 31, No. 1, 2005, pp. 59–65.Original Russian Text Copyright © 2005 by Kazennikov, Shlykov, Levik.     

Human skin chymotrypsin-like proteinase chymase. Subcellular localization to mast cell granules and interaction with heparin and other glycosaminoglycans

The subcellular localization of human skin chymase to mast cell granules was established by immunoelectron microscopy, and binding of chymase to the area of the dermo-epidermal junction, a basement membrane, was demonstrated immunocytochemically in cryosections incubated with purified proteinase prior to immunolabeling. Because heparin and heparan sulfate proteoglycans are major constituents of mast cell granules and basement membranes, respectively, the ability of chymase to bind to glycosaminoglycans (GAG) was investigated. Among a variety of GAGs, only binding of chymase to heparin and heparan sulfate appears physiologically significant. Binding was ionic strength-dependent, involved amino groups on the proteinase, and correlated with increasing GAG sulfate content, indicating a predominantly electrostatic association. Interaction with heparin was observed in solutions containing up to 0.5 M NaCl, and interaction with heparan sulfate was observed in solutions containing up to 0.3 M NaCl. Binding of heparin did not detectably affect catalysis of peptide substrates, but may reduce accessibility of proteinase to protein substrates. Measurements among a series of serine class proteinases indicated that heparin binding was a more common property of mast cell proteinases than proteinases stored in other secretory granules. Binding of chymase to heparin is likely to have a storage as well as a structural role within the mast cell granule, whereas binding of chymase to heparan sulfate may have physiological significance after degranulation.     

An apparatus to measure in vivo biomechanical behavior of dorsi- and plantarflexors of mouse ankle.

We developed an apparatus to quantify the biomechanical behavior of the dorsi- and plantarflexor muscles of the ankle of an anesthetized mouse. When the dorsi- or plantarflexor muscle group is activated by electrical stimulation of either the peroneal or tibial nerve, the apparatus measures the moment developed about the ankle during isometric, isovelocity shortening, or isovelocity lengthening contractions. Displacements may be performed over the full 105 degrees range of ankle motion with an angular resolution of 0.09 degrees. Bidirectional isovelocity ramps in ankle angle up to 1,100 degrees/s are possible and are equivalent to maximum velocities of 2.3 fiber lengths/s (Lf/s) for the fibers in tibialis anterior muscle and 11.9 Lf/s for those in gastrocnemius muscle. During single contractions of the dorsi- and plantarflexor muscle groups at 37 degrees C and with both knee and ankle joint at 90 degrees neutral position, the isometric tetanic force developed was 1.4 and 3.3 N, power output at 2.2 Lf/s was 3.1 and 5.9 mW, and power absorption at 0.5 Lf/s was 4.9 and 9.0 mW, respectively. These values are in reasonable agreement with data from the same muscle groups tested in situ. We conclude that the apparatus provides valid measurements of force and power of the dorsi- and plantarflexor muscle groups.