Estimation of muscle spindle information rate by pattern matching and the effect of gamma system activity on parallel spindles.

The information transmission properties of ensembles of MSs and the effect of the gamma system on these properties were studied. Three converging lines of research were taken: (1) the development of information theoretic estimation tools, and the formulation of an "operational" interpretation for the information rate; (2) animal experiments in which the mutual information rate was estimated and the effect of the gamma system was quantified; (3) simulation of a muscle spindle model with gamma activation in order to corroborate the results of the animal experiments. The main hypothesis was that the gamma system will enhance information theoretic measures that quantify the quality of the sensory neural channel comprised from an ensemble of primary muscle spindle afferents. A random stimulus was applied to a muscle in the hind limb of a cat, while spike trains from several primary MS afferents were recorded simultaneously. The stimulus was administered twice, with an operative and a disconnected gamma system. The mutual information rate between the stimulus and spike trains, as well as other information theoretic measures, was estimated. The information rate of ensembles of MSs increased with increasing ensemble size. However, with an operative gamma system the "ensemble effect" was much higher. In addition, the ensemble effect was influenced by the stimulus spectrum. A muscle spindle population model with gamma activation was simulated with stimuli that were identical to that of the animal experiments. The simulation results supported the experimental results and corroborated the main hypothesis. The results indicate that the gamma system has an important role in enhancing information transmission from ensembles of MSs to the spinal cord.

Oligohydramnios, intrauterine growth retardation and fetal death due to umbilical cord torsion.

Intrauterine fetal death was observed in a woman at 35 gestational weeks shortly after she was admitted to hospital due to suspected placental insufficiency expressed by oligohydramnios and fetal growth retardation. The pathologic examination showed umbilical cord torsion and an organized thrombus at the site of the torsion. This findings could imply that both the fetal death and the placental insufficiency were the results of the cord torsion.

The structure of the variable regions of mouse monoclonal antibodies to hepatitis B virus core antigen.

From a panel of monoclonal antibodies (MoAbs) directed against E. coli-derived native and denatured hepatitis B virus (HBV) core antigen we have selected a set of specific MoAbs which recognize different linear antigenic determinants: MoAb C1-5--cl epitope; MoAb 14K8--less immunogenic N-terminal region; and MoAbs 13C9, 10F10 and 14E11, 14G3--the immunodominant region between amino acids 134 and 140. We have applied the polymerase chain reaction technique to clone Ig VH and VL region genes, and appropriate full-length cDNA clones were obtained and characterized by nucleotide sequence analysis. Among the six heavy chain variable region sequences examined, three VH families were represented. Two of them belong to the 7183 (MoAb C1-5) and 3609 (14B8) families respectively and four, having only two amino acid changes in the CDR2 region, to the J558 family. These four probably are derived from a single expanded B-cell clone. The light chain sequences indicate that their VL are encoded by V kappa 21, V kappa 19 and V kappa 3 germline genes. Unlike VH genes, light chain genes are closely related to known representatives of mouse kappa light chain families and are employed also by MoAbs raised against other antigens.