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PubMed2006

Structural variation of the monoamine oxidase A gene promoter repeat polymorphism in nonhuman primates.

By conferring allele-specific transcriptional activity on the monoamine oxidase A (MAOA) gene in humans, length variation of a repetitive sequence [(variable number of tandem repeat (VNTR)] in the MAOA promoter influences a constellation of personality traits related to aggressive and antisocial behavior and increases the risk of neurodevelopmental and psychiatric disorders. Here, we have analyzed the presence and variability of this MAOA promoter repeat in several species of nonhuman primates. Sequence analysis of MAOA's transcriptional control region revealed the presence of the VNTR in chimpanzee (Pan troglodytes), bonobo (Pan paniscus), gorilla (Gorilla gorilla), orangutan (Pongo pygmaeus), rhesus macaque (Macaca mulatta) and Gelada baboon (Theropithecus gelada). The majority of P. troglodytes and P. paniscus showed a single repeat with a sequence identical to the VNTR sequence in humans. In contrast, analyses of the remaining species revealed shorter sequences similar to the first 18 bp of human VNTR. Compared with other nonhuman primates, the VNTR sequence of M. mulatta showed the highest length variability with allele frequencies of 35, 25 and 40% for the five, six and seven repeat variants, respectively. The extent of variability of the MAOA promoter repeat in both rhesus monkeys and humans supports the notion that there may be a relationship between functional MAOA expression and aggression-related traits in humans and rhesus macaque populations.

Animals↗

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Backfiltration: does it occur in membrane plasma separation?

Backfiltration in hemodialysis refers to local filtration of dialysate into the blood compartment. This investigation was performed to examine whether there is a similar backfiltration phenomenon in membrane plasma separation. It was shown experimentally in hollow fiber devices that there is a flow of plasma through the filtrate side parallel to the blood flow inside the fiber. This bypass flow includes a backfiltration of the plasma from filtrate to the blood compartment near the end of the module. The following experimental results show the existence of bypass flow and backfiltration. In the case of no net filtration, these findings were made: 1) the existence of an offset of mean transmembrane pressure and 2) the blood side pressure drop in ACD-blood was less in impermeable fibers than in permeable ones. Filtrate pressure is higher than module outlet pressure at a wide range of filtration rates. In summary, backfiltration is not restricted to zero net filtration but occurs under the conditions of clinical use. Therefore, backfiltration is a crucial issue for device safety, because any contamination or wash-out from the membrane can reach the blood side.

Equipment Safety↗