Thromboembolic infarction caused by an unknown patent foramen ovale 30 years after VA shunt insertion: a case report and review of the literature.

BACKGROUND: Ventriculoatrial shunt (VA) insertion is one of the possible surgical procedures to treat hydrocephalus. However, it is also associated with several complications such as obstruction and shunt infection as well as life-threatening complications like intraatrial thrombus or thrombosis on the distal catheter. In this case report, we share a rare case of a patient with a VA shunt, who was admitted to our hospital with a stroke. CASE DESCRIPTION: A 56-year-old female patient with suspected acute stroke was admitted to the stroke unit. CT and MRI scans showed multiple cerebral infarctions in both hemispheres. The transesophageal echocardiography (TEE) showed at the tip of the VA shunt catheter, which was implanted about 30 years ago due to aqueduct stenosis, also a thrombotic formation as the reason of stroke. Interestingly, the tip of the catheter was not in the right atrium as expected, but in the left atrium. Further evaluation showed a patent foramen ovale (PFO), through which the catheter migrated from the right to the left side. At first, conservative treatment with anticoagulation was started with the aim to dissolve the thrombotic formation; however, a control TEE showed an unchanged mass at the catheter tip. Therefore, a ventriculoperitoneal shunt was implanted and the proximal shunt catheter was removed with an additional closure of the PFO by our heart surgeons. Postoperatively, the patient was discharged 10 days later in good condition to a rehabilitation center. CONCLUSIONS: Thromboembolic events due to a PFO are rare but possible life-threatening complication after VA shunt insertion. Therefore, preoperative cardiac diagnostic might be clinically relevant prior to a VA shunt implantation to avoid such complications.

Alternative splicing of the maize Ac transposase transcript in transgenic sugar beet (Beta vulgaris L.).

The maize Activator/Dissociation (Ac/Ds) transposable element system was introduced into sugar beet. The autonomous Ac and non-autonomous Ds element excise from the T-DNA vector and integrate at novel positions in the sugar beet genome. Ac and Ds excisions generate footprints in the donor T-DNA that support the hairpin model for transposon excision. Two complete integration events into genomic sugar beet DNA were obtained by IPCR. Integration of Ac leads to an eight bp duplication, while integration of Ds in a homologue of a sugar beet flowering locus gene did not induce a duplication. The molecular structure of the target site indicates Ds integration into a double strand break. Analyses of transposase transcription using RT-PCR revealed low amounts of alternatively spliced mRNAs. The fourth intron of the transposase was found to be partially misspliced. Four different splice products were identified. In addition, the second and third exon were found to harbour two and three novel introns, respectively. These utilize each the same splice donor but several alternative splice acceptor sites. Using the SplicePredictor online tool, one of the two introns within exon two is predicted to be efficiently spliced in maize. Most interestingly, splicing of this intron together with the four major introns of Ac would generate a transposase that lacks the DNA binding domain and two of its three nuclear localization signals, but still harbours the dimerization domain.