Assessing the evidential value of DNA profiles matching without using the assumption of independent loci.

DNA profiling allows determination of the alleles at multiple loci on an individual's genome. The frequencies of these alleles are then estimated from a sample drawn from the population. If the occurrences of alleles at different loci are independent, the frequencies may be multiplied together to give an estimate of the probability of DNA from a randomly-chosen member of the population matching the DNA in question. However, there is doubt as to whether the assumption of independence can be justified. This paper discusses a method of calculating the probability of a match that does not require the assumption of independence. A suitable set of criteria is also derived that offer an objective approach to the determination of a match from two DNA samples.

Effect of restricted feeding on the relationship between hypophysial portal concentrations of growth hormone (GH)-releasing factor and somatostatin, and jugular concentrations of GH in ovariectomized ewes.

These studies characterized the secretion of GH-releasing factor (GRF) and somatostatin (SRIF) into the hypophysial portal circulation in ewes after long term restricted feeding. In addition, we examined the temporal relationship between the concentrations of these two hypothalamic peptides in portal blood and the concentration of GH in jugular blood. Six sheep were fed 1000 g hay/day (normal feeding) and 6 sheep were fed 400-600 g hay/day (restricted feeding). This resulted in a wt loss of 35% in restricted animals compared with 6% in control animals after 20 weeks. Fluctuations in portal levels of GRF indicated a pulsatile pattern of secretion with approximately 60% of pulses coincident with, or immediately preceding, a GH pulse. Similarly, 65% of GH pulses were associated with GRF pulses. Restricted feeding increased (P less than 0.01) mean ( +/- SEM) plasma GH levels (9.8 +/- 1.4 vs. 2.9 +/- 0.6 ng/ml) and mean GH pulse amplitude (7.9 +/- 1.8 vs. 2.8 +/- 0.3 ng/ml) but did not affect mean GH pulse frequency (6.0 +/- 1.1 vs. 5.7 +/- 1.1 pulses/8 h). The level of feeding had no effect on mean portal concentration of GRF (restricted: 5.5 +/- 0.8, normal: 6.6 +/- 1.4 pg/ml), GRF pulse amplitude (14.7 +/- 2.3 vs. 13.5 +/- 0.7 pg/ml), or GRF pulse frequency (5.3 +/- 1.1 vs. 6.7 +/- 0.9 pulses/8 h). Portal concentrations of SRIF in sheep on a restricted diet were half (P less than 0.01) those of sheep fed a normal diet (10.2 +/- 2.3 vs. 19.6 +/- 1.6 pg/ml). Pulses of SRIF were not significantly associated with changes in GH or GRF concentrations. These data indicate a functional role for hypothalamic GRF in initiating GH pulses. Furthermore, the increase in GH secretion in underfed sheep was most probably due to a decrease in the release of SRIF into hypophysial portal blood. Restricted feeding had no affect on GRF secretion, but because of the reduced exposure of the pituitary gland to SRIF, it is possible that responsiveness to GRF is enhanced.