Rat pineal arylalkylamine-N-acetyltransferase: cyclic AMP inducibility of its gene depends on prior entrained photoperiod.

The nocturnal biosynthesis of melatonin in the rat pineal depends on strongly enhanced expression of the enzyme N-acetyltransferase [arylalkylamine N-acetyltransferase (AA-NAT); EC 2.3.1.87]. AA-NAT transcription is stimulated during darkness by adrenergic inputs to the pineal from the suprachiasmatic nucleus (SCN). Nocturnal activation of the AA-NAT promotor following stimulation of pinealocyte adrenoceptors involves cAMP-dependent stimulation of protein kinase A (PKA). The nocturnal rise in AA-NAT depends on the lighting conditions. As compared with light/dark (LD) 12:12, the delay between dark onset and the nocturnal rise in AA-NAT is shortened under long photoperiods and prolonged under short photoperiods. Here, we report that the rapidity of nocturnal AA-NAT induction depends on cAMP inducibility of the gene. Accordingly, cAMP produces a strong AA-NAT response in pineals obtained from rats housed under long photoperiods and a weak AA-NAT response under short photoperiods. Changes in AA-NAT inducibility are fully developed not earlier than after seven cycles. This observation suggests that long-term changes in the photoperiod are necessary to achieve full adjustment of cAMP inducibility of the gene. A direct relationship was found between cAMP-dependent AA-NAT inducibility and the pineal protein kinase A (PKA) activity. As compared to LD 12:12, PKA activity was increased under LD 20:4 and attenuated under LD 4:20. On the basis of the present findings, we suggest that the photoperiod determines the effectiveness of nocturnal AA-NAT induction by long-term modulation of the intrapineal pathway that transmits the cAMP signal to the AA-NAT gene.

Systematic intraoperative application of confocal endomicroscopy for early detection and resection of squamous cell carcinoma of the head and neck: a preliminary report.

OBJECTIVE: To use intraoperative confocal endomicroscopy for early detection and resection of squamous cell carcinoma (SCC) of the head and neck. A preliminary report. DESIGN: Prospective case series. SETTING: Tertiary referral hospital. PATIENTS: Fifteen consecutive patients with SCC of the oral cavity, hypopharynx, and larynx were included from the Department of Otolaryngology-Head and Neck Surgery, HSK Dr Horst Schmidt Kliniken GmbH, Wiesbaden, Germany INTERVENTIONS: Confocal endomicroscopy was performed during diagnostic and therapeutic procedures with a prototype of a rigid laser endoscope in combination with the already available technology of autofluorescence. MAIN OUTCOME MEASURES: Real-time visualization of cellular and subcellular details during endoscopy. Diagnostic scores were applied to differentiate dysplastic and malignant mucosal changes of SCC of the head and neck from normal squamous cell mucosa using this method. Results were correlated with the well-established gold standard, histologic analysis. RESULTS: Dysplastic and malignant changes of head and neck squamous cell mucosa were endoscopically determined by this unique in vivo application of confocal laser endomicroscopy using a rigid probe. CONCLUSIONS: We present preliminary and descriptive data using this novel technology in vivo. Considering the impact of a virtual real-time histologic analysis, this technology points to a very promising development. It may carry potential for quicker intraoperative diagnosis, less need for multiple frozen sections, and more precise resection margins.

Increased basic fibroblast growth factor release and proliferation in xenotransplanted squamous cell carcinoma after combined irradiation/anti-vascular endothelial growth factor treatment.

Novel strategies of cancer therapy combine irradiation and anti-angiogenic active compounds. However, little is known concerning the undesired cellular and molecular effects caused by this novel treatment concept. We used a mouse squamous cell carcinoma (SCC) xenotransplantation model to evaluate the potential undesired effects which compromise the success of this therapeutic combination. SCCs were subcutanously implanted in nude mice. Animals were treated with a fractionated irradiation scheme (5x4 Gy) alone or in combination with daily injections of anti-vascular endothelial growth factor (VEGF) antibodies. Controls remained untreated. Before and after treatment, resonance imaging (MRI), ultrasound and near-infrared spectrometry were used to evaluate tumor vessel integrity. Finally, tumors were explanted and VEGF, basic fibroblast growth factor (bFGF), vessel density, proliferation and apoptotic activity were analyzed by immunohistochemistry. Irradiation caused VEGF release and we found evidence for VEGF-mediated vessel protection. In the tumors derived from the combined treatment, blood volume was decreased, and apoptotic indices were increased. Remarkably, bFGF levels and proliferative indices were also increased. Combined irradiation/anti-VEGF treatment resulted in the desired VEGF depletion and increased tumor cell apoptosis. Nonetheless, bFGF and proliferation also increased, possibly suggesting a compensatory response. The application of additional targeted drugs may help develop more effective SCC treatments.