Rolipram, a Phosphodiesterase 4 Inhibitor, Stimulates Inducible cAMP Early Repressor Expression in Osteoblasts

Phosphodiesterase (PDE) 4 inhibitors have been shown to induce the cAMP-mediated signaling pathway by inhibiting cAMP hydrolysis. This study investigated the effect of a PDE4 inhibitor on the expression of the inducible cAMP early repressor (ICER), which is an endogenous inhibitor of CRE- mediated transcription, in osteoblastic cells. RT-PCR analysis revealed that rolipram, a PDE4 inhibitor, stimulates the ICER mRNA in a dose dependent manner. The induction of ICER mRNA expression by rolipram was suppressed by the inhibitors of protein kinase A (PKA) and p38 MAPK, suggesting the involvement of PKA and p38 MAPK activation in ICER expression by rolipram. It was previously shown that rolipram induced the expression of TNF-related activation-induced cytokine (TRANCE, also known as RANKL, ODF, or OPGL) in osteoblasts. This paper provides evidences that a transcriptional repressor like ICER might modulate TRANCE mRNA expression by rolipram in osteoblasts.

Experience with an Image-Guided Surgery Device-CANS Navigator-

The authors describe their experience with the CANS navigator, which has been in use since January 1997. The device uses magnetic field modulation technology for intraoperative localization: using a built-in scanner, a preoperative image with fiducial markers is input to a computer, and intraoperative localization uses a suctiontube integrated probe. During the previous ten months, we have used the device to perform surgery in 60 cases of brain lesion, mostly tumors. In five early cases, precise intraoperative localization was not successful, probably due to error in image input or registration, but after 2 months, there were only two failures, and for surgery, the device was very helpful: it was useful in the dessign of scalp incisionand bone flap, and for assessing the extent of resection in tumors, especially in cases in which surrounding brain tissue was poorly demarcated. It was also helpful in skull base surgery, in which precise localization of the work area is critical. The CANS navigator uses a magnetic field for localization, but except for the skull clamp, there was no problem in using metallic surgical instruments: there was no interference with laser, CUSA, or monitoring devices, and no complication attributable to its use. We suggest that for neurosurgery, the CANS navigator is a useful device: it is helpful for performing minimally invasive surgery.

Jugular Foramen Schwannomas

The cases of ten patients with schwannomas of the jugular foramen who underwent surgery in our department between 1983 and 1996 are described. Seven were women and three were men(mean age 40 years) and the duration of their symptoms, the most predominant of which were hearing loss and tinnitus, ranged from 1 months to 20 years(median 8.5 months). Computerized tomography was performed in all cases, magnetic resonance imaging in eight, and angiography in three. Depending on their radiological and surgical features, the tumors were classified as follows : Type A, a tumor primarily at the cerebellopontine angle, with minimal enlargement of the jugular foramen(n=5) ; Type B, a tumor primarily at the jugular foramen, with or without intracranial extension(n=4) ; Type C, a primarily extracranial tumor with extension into the jugular foramen(n=0) ; Type D, a dumbbell-shaped tumor with both intra- and extracranial components(n=1). A retromastoid suboccipital craniectomy(RM-SOC) was performed for type A tumors, and the RM-SOC or staged infratemporal fossa approach/RM-SOC was used for type B and D. Total removal was achieved in six cases, and no patient died. Postoperative complications were detected in six cases, with low cranial nerve dysfunction most common(n=5). The follow-up period ranged from 14 to 173(mean 48) months. In one patient, a subtotally-resected tumor recurred ; this was again resected and LINAC radiosurgery was successful. In the remaining nine patients, tumors did not recur. It is suggested that jugular foramen schwannomas could be totally resected by RMSOC/ITFA ; to reduce postoperative complications, cases showing adhesion to critical structures could be managed with sub- or near-total resection.