The kick-in system: a novel rapid knock-in strategy.

Knock-in mouse models have contributed tremendously to our understanding of human disorders. However, generation of knock-in animals requires a significant investment of time and effort. We addressed this problem by developing a novel knock-in system that circumvents several traditional challenges by establishing stem cells with acceptor elements enveloping a particular genomic target. Once established, these acceptor embryonic stem (ES) cells are efficient at directionally incorporating mutated target DNA using modified Cre/lox technology. This is advantageous, because knock-ins are not restricted to one a priori selected variation. Rather, it is possible to generate several mutant animal lines harboring desired alterations in the targeted area. Acceptor ES cell generation is the rate-limiting step, lasting approximately 2 months. Subsequent manipulations toward animal production require an additional 8 weeks, but this delimits the full period from conception of the genetic alteration to its animal incorporation. We call this system a "kick-in" to emphasize its unique characteristics of speed and convenience. To demonstrate the functionality of the kick-in methodology, we generated two mouse lines with separate mutant versions of the voltage-dependent potassium channel Kv7.2 (Kcnq2): p.Tyr284Cys (Y284C) and p.Ala306Thr (A306T); both variations have been associated with benign familial neonatal epilepsy. Adult mice homozygous for Y284C, heretofore unexamined in animals, presented with spontaneous seizures, whereas A306T homozygotes died early. Heterozygous mice of both lines showed increased sensitivity to pentylenetetrazole, possibly due to a reduction in M-current in CA1 hippocampal pyramidal neurons. Our observations for the A306T animals match those obtained with traditional knock-in technology, demonstrating that the kick-in system can readily generate mice bearing various mutations, making it a suitable feeder technology toward streamlined phenotyping.

Selective serotonin reuptake inhibitors in pregnant women and neonatal withdrawal syndrome: a database analysis.

BACKGROUND: Selective serotonin reuptake inhibitors (SSRIs) have been associated with withdrawal symptoms. We investigated whether use of these drugs in pregnant women might cause neonatal withdrawal syndrome. METHODS: An association between paroxetine and neonatal convulsions was identified in December, 2001, by the data mining method routinely used to screen the WHO database of adverse drug reactions. An information component (IC) measure was used to screen for unexpected adverse reactions relative to the information in the database. We then assessed cases of neonatal convulsions and neonatal withdrawal syndrome associated with drugs included in the anatomical therapeutic chemical groups N06AB and N06AX. FINDINGS: By November, 2003, a total of 93 suspected cases of SSRI-induced neonatal withdrawal syndrome had been reported, and were regarded as enough information to confirm a possible causal relation. 64 of the cases were associated with paroxetine, 14 with fluoxetine, nine with sertraline, and seven with citalopram. The IC-2 SD for the group became greater than 0 in the first quarter of 1991, and the IC increased to 2.68 (IC-2 SD 0.32) by the second quarter of 2003. For each individual compound, the IC-2 SD was greater than 0. INTERPRETATION: SSRIs, especially paroxetine, should be cautiously managed in the treatment of pregnant women with a psychiatric disorder.

Neonate characteristics after maternal use of antidepressants in late pregnancy.

BACKGROUND: Exposure to antidepressants during the third trimester of pregnancy has been associated with an increased risk for adverse birth outcomes, including preterm birth, respiratory distress, and hypoglycemia. OBJECTIVE: To investigate neonatal outcomes in 997 infants (987 mothers) after maternal use of antidepressants based on prospectively recorded information in antenatal care documents. RESULTS: An increased risk for preterm birth (odds ratio [OR], 1.96) and low birth weight (OR, 1.98) was verified, but the gestational week-specific birth weight was increased notably after exposure to tricyclic antidepressants. An increased risk for a low Apgar score (OR, 2.33), respiratory distress (OR, 2.21), neonatal convulsions (OR,1.90), and hypoglycemia (OR, 1.62) was found, the latter especially after exposure to tricyclic drugs, but no significant effect on the frequency of neonatal jaundice was seen (OR, 1.13). Most effects seemed not to be selective serotonin reuptake inhibitor drug specific, and outcomes after exposure to paroxetine hydrochloride were not worse than after exposure to other selective serotonin reuptake inhibitors. CONCLUSIONS: Neonatal effects after maternal use of antidepressant drugs during late pregnancy were seen. Selective serotonin reuptake inhibitors may be the drugs of choice during pregnancy.