Comparative analysis of the HBsAg level in human blood preparations

A total of 218 batches of blood preparations produced from different raw materials have been studied by means of enzyme immunoassay kits (Abbott Laboratories, USA). The assays have revealed that the preparations under study are nonstandard with respect to the content and isolation rate of HBsAg, the marker of hepatitis B virus. These data necessitate search for the ways of improving the quality of blood preparations.     

Contractile properties of reinnervated skeletal muscle and their relation to the degree of nerve damage

Experiments with 22 rats have shown that the anterior tibial muscle in the stage of incomplete reinnervation is marked by decreased force and retardation of the semi-relaxation of an isometric contraction. In completely reinnervated muscles, the changes in the contractility are determined by the degree of nerve damage. The group of animals with the sciatic nerve injury demonstrated the contractility characteristic of a slower muscle, in contrast to the group with the fibular nerve damage.     

Path analysis of natural selection on plant chemistry: the xylem resin of ponderosa pine

We analyzed the pattern of correlations among fitness components, herbivory, and resin characteristics in a natural all-aged stand of ponderosa pine, to infer the strength and mechanism of natural selection on plant chemistry. Male and female cone production were monitored yearly for 15 years, and levels of herbivory for 9 years in 165 trees. Resin flow rate and monoterpene composition were determined for these same trees. Multiple regression of fitness components on resin characteristics showed significant associations consistent with directional selection for increased resin flow rates and increased proportions of α- and β-pinene, myrcene and terpinolene. However, negative correlations among monoterpene fractions of the resin constrained the overall selection. Selective herbivory by aphids approached statistical significance and monoterpenes showed some (non-significant) effect as deterrents against deer browse. Resin characteristics were not correlated with attack by cone insects or porcupines. However, the association between resin characteristics and fitness is significantly different from that predicted by the path coefficients involving herbivores. Therefore the hypothesis that these herbivores mediate selection on the resin is not supported by the observed pattern of correlations among resin characteristics, herbivory, growth and fecundity. In this population, most of the association between resin characteristics and fitness appears to be mediated by some other factor independent of attack by herbivore species present. Received: 18 March 1996/Accepted: 18 July 1996