Runs of homozygosity in European populations

Estimating individual genome-wide autozygosity is important both in the identification of recessive disease variants via homozygosity mapping and in the investigation of the effects of genome-wide homozygosity on traits of biomedical importance. Approaches have tended to involve either single-point estimates or rather complex multipoint methods of inferring individual autozygosity, all on the basis of limited marker data. Now, with the availability of high-density genome scans, a multipoint, observational method of estimating individual autozygosity is possible. Using data from a 300,000 SNP panel in 2618 individuals from two isolated and two more-cosmopolitan populations of European origin, we explore the potential of estimating individual autozygosity from data on runs of homozygosity (ROHs). Termed F(roh), this is defined as the proportion of the autosomal genome in runs of homozygosity above a specified length. Mean F(roh) distinguishes clearly between subpopulations classified in terms of grandparental endogamy and population size. With the use of good pedigree data for one of the populations (Orkney), F(roh) was found to correlate strongly with the inbreeding coefficient estimated from pedigrees (r = 0.86). Using pedigrees to identify individuals with no shared maternal and paternal ancestors in five, and probably at least ten, generations, we show that ROHs measuring up to 4 Mb are common in demonstrably outbred individuals. Given the stochastic variation in ROH number, length, and location and the fact that ROHs are important whether ancient or recent in origin, approaches such as this will provide a more useful description of genomic autozygosity than has hitherto been possible.

[llocalization of grouping effect in overlapping tasks]

In certain kinds of overlapping tasks subjects have to respond to two stimuli (S1 and S2), presented in close succession with variable onset asynchrony (SOA), carrying out two different responses (R1 and R2). When responding to S1 is given priority over S2 processing, reaction time (RT) to the first stimulus is unaffected by SOA. However, sometimes subjects adopt, either spontaneously or because of instruction, a different processing strategy called grouping. In this case R1 is postponed until R2 has been determined too. The present study addresses the localization of the postponed processing stage by means of the lateralized readiness potential (LRP). One group of subjects was instructed to group responses and a second group was to give priority to S1 processing. The adherence to instructions was verified by subjects' reaction times. In case of grouping the interval between LRP onset and overt reaction increased proportionally to the postponement caused by SOA. In contrast, the interval between stimulus and LRP onset was unaffected by SOA. These findings speak against assumptions that grouping causes response activation postponement; rather, the corresponding reaction is already selected and activated prior to postponement.

Identification of lymphocyte subsets in pregnancy gingivitis

The percentage of gingival tissue and peripheral T, T Subsets and B lymphocytes were assessed in ten pregnant women during the first, second and third trimesters. Clinically the gingival index (GI) was found to be higher during pregnancy than in the control group. The percentage of the T3, T4 and B cells appeared to decrease in peripheral blood and gingival tissues during pregnancy as compared to control group.