An apparatus and a method for measuring the relationship of triceps surae torques to tibio-tarsal angles in man.

1. The apparatus and method described give the relationship of triceps surae torque to the absolute tibio-tarsal angle. Data of the anatomy of the foot and the axis of the ankle are taken into consideration. They make complementary measurements necessary, which in certain cases enable the angle recorded by the apparatus to be corrected so as to obtain the true angle. 2. The reliability of the apparatus and the technique of linkage of subject to apparatus are judged by examination of the torque-angle plots obtained by passive stretching of the triceps in 7 subjects for whom correction is monor. Good reliability was observed during the session and from one session to another. The plot is exponential. The merits of the method of correcting angles are illustrated in three subjects with the same protocol: when plots are not corrected, they are more dispersed during the session and no longer exponential. These results justify the considerable correction of the angle that we propose in the study of isometric contractions.     

Characterization of elicitin-like phospholipases isolated from Phytophthora capsici culture filtrate.

The phytopathogenic oomycete Phytophthora capsici secretes in culture a phospholipase activity. Two enzyme isoforms exhibiting a high phospholipase B activity were isolated by chromatography and electrophoresis. They differ in their apparent molar masses (22 and 32 kDa). Both proteins are glycosylated and share the same N-terminal amino acid sequence up to the 39th residue with a high homology with capsicein, the P. capsici elicitin. Although devoid of phospholipase activity, capsicein was shown by circular dichroism to specifically interact with negatively charged phospholipids, suggesting that the membrane lipids could be a potential target for elicitins.     

Interleukin 2 up-regulates its own production

It has been previously reported that a combination pair of anti-CD2 monoclonal antibodies (mAb) T11(2)+T11(3) induces a strong proliferation of T cells, which does not require the involvement of accessory cells and exogenous interleukin 2 (IL-2). More recently, we have shown that the requirement for optimal T cell proliferation depends on the combination pairs of anti-CD2 mAb used. Among them, anti-GT2+T11(1) mAb do not allow optimal proliferation of TA4 helper cloned T cells due, at least in part, to a low level of IL-2 production. This observation offered us the opportunity to study the effect of IL-2 on its own production. We show here that stimulation of cloned TA4 cells with anti-GT2+T11(1) mAb induces only a marginal level of IL-2 production. By contrast, significantly higher levels of IL-2 activity are detected in the culture supernatant of TA4 cells preincubated with recombinant IL-2 (rIL-2) before stimulation with anti-GT2+T11(1) mAb. This effect is dose-dependent over a wide range (5 to 50 IU/ml) of rIL-2 concentrations added during preincubation time. In addition, it is not due to carryover of rIL-2 bound during the preincubation time, or to lesser IL-2 consumption by these cells, or to increasing numbers of IL-2-producing cells induced by exogenous IL-2. Moreover, the observation was confirmed with IL-2 mRNA. Although neither rIL-2 nor anti-GT2+T11(1) mAb alone could induce a significant production of IL-2, rIL-2 appears to up-regulate its own production when the TA4 cells are activated by the anti-CD2 mAb-mediated second signal.     

Chemical synthesis,expression and mutagenesis of a gene encoding β-cryptogein,an elicitin produced by Phytophthora cryptogea

Elicitins are 10 kDa holoproteins secreted by Phytophthora fungi, that elicit an incompatible hypersensitive reaction, leading to resistance against fungal and bacterial plant pathogens. Comparison of primary sequences of -elicitins and -elicitins indicated several potential necrotic activity-determining residues. All of the highly necrotic -elicitins have a hydrophilic residue (usually lysine) at position 13, whereas in the less necrotic -elicitins this residue is replaced by a valine. Here, we report the synthesis and expression of a gene encoding a highly necrotic elicitin, -cryptogein, and we show that the substitution of Lys-13 of this recombinant protein by a valine leads to a drastic alteration to the necrotic activity of the recombinant protein.     

Unimpaired induction of drug-metabolizing enzymes in hepatocytes isolated from rats with micronodular cirrhosis

To test further the competence of the cirrhotic liver to metabolize xenobiotics, hepatocytes were isolated from control and CCl4-induced cirrhotic male or female rats. Histologically micronodular cirrhosis was present in all CCl4-treated rats, while control rats had normal livers. Portal perfusion pressure and intrahepatic collagen content were also significantly increased by CCl4 administration. In male rats, no significant differences in levels of circulating transaminases nor in alkaline phosphatase was observed between cirrhotic and control rats, while CCl4-treated females had slightly higher than normal serum transaminase levels at the time of the studies. Hepatocytic cytochrome P-450 and basal xenobiotic biotransformation were unaffected by micronodular cirrhosis in both genders; calculation of the aminopyrine and 7-ethoxycoumarin intrinsic clearances (Cli) revealed, however, a slightly decreased transformation potential in hepatocytes obtained from cirrhotic females, a phenomenon not observed in cirrhotic male rats. It is speculated that the observed reduction in Cli may have been independent of cirrhosis per se, owing to the perduring cytotoxic effect of CCl4 as evidenced by the higher than normal level of transaminases in female rats. Finally, male rats were subjected to in vivo administration of phenobarbital or 3-methylcholanthrene; both compounds led to significant induction of the mixed-function oxidase system, which was similar in magnitude and in selectivity in control and cirrhotic rats as illustrated by calculation of the Michaelis-Menten kinetic parameters for aniline p-hydroxylation, aminopyrine-N-demethylation, 7-ethoxycoumarin-O-deethylation, and p-nitrophenol UDP-glucuronyl transferase. We conclude that in well-established but compensated and hepatolysis-free micronodular cirrhosis, hepatocytes are fully able to transform xenobiotics and to respond normally and selectively to inducers of drug metabolism.     

KIN‐BASED RECOGNITION AND SOCIAL AGGREGATION IN A CILIATE

Aggregative groups entail costs that must be overcome for the evolution of complex social interactions. Understanding the mechanisms that allow aggregations to form and restrict costs of cheating can provide a resolution to the instability of social evolution. Aggregation in Tetrahymena thermophila is associated with costs of reduced growth and benefits of improved survival through “growth factor” exchange. We investigated what mechanisms contribute to stable cooperative aggregation in the face of potential exploitation by less‐cooperative lines using experimental microcosms. We found that kin recognition modulates aggregative behavior to exclude cheaters from social interactions. Long‐distance kin recognition across patches modulates social structure by allowing recruitment of kin in aggregative lines and repulsion in asocial lines. Although previous studies have shown a clear benefit to social aggregation at low population densities, we found that social aggregation has very different effects at higher densities. Lower growth rates are a cost of aggregation, but also present potential benefits when restricted to kin aggregations: slow growth and crowd tolerance allow aggregations to form and permit longer persistence on ephemeral resources. Thus in highly dynamic metapopulations, kin recognition plays an important role in the formation and stability of social groups that increase persistence through cooperative consumptive restraint.