Rydberg Series of Dark Excitons in Cu_{2}O.

We demonstrate the Rydberg series of dark excitons, known as paraexcitons, up to the principal quantum number n=6 for the yellow exciton series in Cu_{2}O, using second harmonic generation. Each of these states is optically inactive to all orders, but their observation becomes possible by application of a magnetic field which leads to mixing with the quadrupole-allowed bright excitons, called orthoexcitons, of the same n. The dark parastates are generally located below the bright orthostates, whose energies are increased by the electron-hole exchange interaction, except for n=2, where this order is reversed. This inversion occurs due to band mixing, namely, of the 2S_{y,o} orthoexciton of the yellow series with the 1S_{g,o} orthoexciton of the green exciton series.

Quantum chaos and breaking of all anti-unitary symmetries in Rydberg excitons.

Symmetries are the underlying principles of fundamental interactions in nature. Chaos in a quantum system may emerge from breaking these symmetries. Compared to vacuum, crystals are attractive for studying quantum chaos, as they not only break spatial isotropy, but also lead to novel quasiparticles with modified interactions. Here we study yellow Rydberg excitons in cuprous oxide which couple strongly to the vacuum light field and interact significantly with crystal phonons, leading to inversion symmetry breaking. In a magnetic field, time-reversal symmetry is also broken and the exciton states show a complex splitting pattern, resulting in quadratic level repulsion for small splittings. In contrast to atomic chaotic systems in a magnetic field, which show only a linear level repulsion, this is a signature of a system where all anti-unitary symmetries are broken simultaneously. This behaviour can otherwise be found only for the electro-weak interaction or engineered billiards.

Nutritional parameters for patients with head and neck cancer.

AIM: Determination of the optimal nutritional parameter to provide useful information for the individual patient and assessing the impact of nutritional status have on the prognosis of head and neck cancer. PATIENTS AND METHODS: Firstly a retrospective study analysed the outcome of 110 patients in relation to initial weight loss and weight loss at the end of radiotherapy. A second study investigated the changing bioimpedance (BIA) data of 27 survivors and 39 patients who died between their first and last measurement during nutritional therapy (at least four weeks). RESULTS: A critical initial weight loss is 10 kg or more at the point of diagnosis. At the end of radiotherapy the body mass reduction should be less than 15 kg. Raw data of BIA reflect the changing nutritional status at the end of life. We observed a stabilized phase angle in survivors (4.7° to 5.2°) whereas patients who died exhibited a significant lower phase angle (4.6° to 3.7°, p<0.05). CONCLUSION: The prognosis of head and neck cancer patients is highly related to their nutritional status. Specific nutritional anamnesis (initial weight loss, total weight loss, body mass index) and additional biophysical measurements such as BIA are recommended to monitor the individual status during the follow-up.

Ultranarrow optical absorption and two-phonon excitation spectroscopy of Cu2O paraexcitons in a high magnetic field.

We show that in a magnetic field B the otherwise forbidden lowest exciton in Cu2O (paraexciton of Gamma(2)(+) symmetry) gives rise to a narrow absorption line of 80 neV at a temperature of 1.2 K. The B2 dependence of the field-induced oscillator strength and the low energy shift DeltaE with increasing field strength are measured. From two-phonon excitation spectroscopy measurements we derive by a merely kinematical analysis a very reliable value for the paraexciton mass. A blueshift and a broadening of the absorption line are observed for increasing excitation intensity. These observations are discussed in connection with a Bose-Einstein condensation of paraexcitons in Cu2O.

Tumor markers and lymphatic metastasis in head and neck cancer patients.

OBJECTIVE: This study was conducted to evaluate the relationship between the lymph node status and tumor marker status in patients with histologically confirmed head and neck cancer. MATERIALS AND METHODS: 134 patients were included in this retrospective analysis. 33/134 were classified as NO and 101/134 as N+. The wall of the lymph node was ruptured by the metastasis in 70/134 patients (poor prognosis). We analyzed the sensitivity of squamous cell carcinoma antigen (SCC), carcinoembryotic antigen (CEA) and CYFRA 21-1 in the total population and in the subgroups. RESULTS: We observed elevated SCC levels in 21.6%, CEA levels in 23.9% and CYFRA 21-1 levels in 50.0% of all patients. If there was no lymphatic metastasis, the SCC sensitivity was 15.1%, the CEA sensitivity was 21.2% and the CYFRA 21-1 sensitivity was 36.4%. Lymph node-positive disease had increased SCC levels in 23.8% of the patients, increased CEA levels in 24.8% and increased CYFRA 21-1 levels in 54.5%. The subgroup of patients with ruptured lymph nodes had the following sensitivities: SCC 18.6% CEA 8.6%, and CYFRA 21-1 50.0%. CONCLUSION: No significant relationship between the lymph node metastasis and the elevation of tumor markers in patients with advanced head and neck cancer was found.

Serum selenium in head and neck cancer patients--a new marker of tumor activity?

OBJECTIVE: The purpose of this work was to investigate the relationship between the tumor volume and the endogenous selenium levels in untreated head and neck cancer patients. MATERIALS AND METHODS: One hundred consecutive patients were included in this study. We measured the endogenous levels of selenium in the serum and the whole blood of all patients by atomic absorption spectrometry. Additionally, the activity of glutathione peroxidase and the concentration of malonedialdehyde were observed. The resectability of the tumor was used as an independent marker of the tumor volume. RESULTS: Thirty-one out of 100 patients had resectable tumors, while 69 patients were characterized as unresectable. The following median results were obtained (resectable versus unresectable): Serum Se 0.90 micromol/l versus 0.78 micromol/l (p=0.024); whole blood Se 1.00 micromol/l versus 0.93 micromol/l (p=0.139); glutathione peroxidase 145 U/l versus 148 U/l (p=0.93); and malonedialdehyde 2.21 mmol/l versus 2.6 mmol/l (p=0.84). CONCLUSION: The concentration of serum selenium shows a significant relationship with tumor resectability in patients with advanced head and neck cancer.

Phase-resolved second-harmonic imaging with nonideal laser sources.

An interferometric imaging setup is described that allows us to map the spatial distribution of the phase of a second-harmonic (SH) wave by using multimode laser sources with achromatic beam imaging of the fundamental and SH waves. Working distances > 1 m and a robust setup allow experiments that were not possible before.

High-dose-rate brachytherapy in the treatment of recurrent and residual head and neck cancer.

OBJECTIVES/HYPOTHESIS: Interstitial and endocavitary brachytherapy are well-accepted kinds of radiotherapy that are commonly used in recurrent head and neck cancer. Most reports about brachytherapy in the successful treatment of head and neck tumors used low-dose-rate brachytherapy. There are only a few reports about high-dose-rate brachytherapy (HDRBT) in head and neck cancer patients. METHODS: After 10 years of experience with HDRBT with Ir 192, we have analyzed the results regarding response rates, survival time, and side effects. Between 1991 and 2000, 90 consecutive patients (68 men, 22 women) were treated with interstitial (68 patients) or intracavitary (22 patients) HDRBT in the head and neck area. Primary tumor locations were as follows: oropharynx (n = 26), tongue/floor of mouth (n = 22), nasopharynx (n = 10), nose/paranasal sinuses (n = 9), salivary glands (n = 5), hypopharynx (n = 5), CUP syndrome (n = 5), and others (n = 8). High-dose-rate brachytherapy was administered in 51 patients with recurrent disease and in 32 patients with residual tumor after primary radiochemotherapy. Seven patients were given exclusive HDRBT in a primary palliative situation. The single dose per fraction ranged from 1.5 to 7.5 Gy (median value, 5 Gy), and the total HDRBT dose ranged from 4.0 to 42.0 Gy (median value, 17.5 Gy). RESULTS: The overall remission rate was 81% with a 46% rate of complete remissions. We observed no change in or progression of tumor in 17 cases (19%). The rate of complete remissions (and median overall survival time) was different in the three therapy groups: in case of recurrent disease, 28% (6 mo); in case of residual tumor, 84% (25 mo); and in primary palliative brachytherapy, 0% (1 mo). Late toxicities III and IV (radiation treatment oncology group score) occurred in 6 of 90 (6.7%) patients. CONCLUSIONS: High-dose-rate brachytherapy proved to be an effective treatment modality in locoregional recurrent head and neck cancer. In cases with persistent or residual tumor after primary radiochemotherapy a local boost with brachytherapy can improve the chance of cure of tumor disease.

Amifostine in simultaneous radiochemotherapy of advanced head and neck cancer.

The authors discuss the results of 3 studies of their group reflecting the possible role of amifostine in simultaneous radiochemotherapy (RCT) of advanced head and neck cancer. In a controlled phase II trial (1995 through 1996), 39 patients were included in this pilot investigation. A control group (n = 14) received simultaneous RCT of the head and neck region with an irradiation dose of 60 Gy and 2 cycles of carboplatin (700 mg/m(2) cumulative dose). Twenty-five patients received the same basic therapy and an additional 500-mg dose of amifostine before each chemotherapy. Amifostine was administered less than 45 minutes before the end of radiotherapy. The authors observed a dramatic reduction of typical radiotherapy-associated toxicities (mucositis, xerostomia, loss of taste, dysphagia). The hematologic side effects (leukocytopenia, anemia, thrombocytopenia) also were decreased significantly. The overall survival rate and locoregional control of both groups were comparable after 12 months. In a controlled intensification trial (1997 through 1999), the authors included 76 consecutive patients (69 men, 7 women) with pharyngeal cancer (oropharynx, n = 33; hypopharynx, n = 43). The tumors were characterized as unresectable and locally advanced without distant metastasis. All patients received a conventional radiotherapy (2-Gy single dose, daily fractionation) up to doses of 60 Gy and an additional 10 Gy as a boost in the tumor-infiltrated region. A dose of carboplatin, 70 mg/m(2), was given to a group of 45 patients on days 1 through 5 and 29 through 33 of radiotherapy (RCT arm). The resulting cumulative dose was 700 mg/m(2). A group of 31 patients (RCTintens arm) received the same dose of carboplatin on days 1 through 5, 22 through 26, and 43 through 47 or 1 through 5, 15 through 19, 29 through 33, and 43 through 47 of radiotherapy (cumulative dose 1.05 to 1.40 mg/m(2)). All patients received 500 mg of amifostine before each carboplatin administration. If the tumor volume was less than 20 cm(3), we observed an increased 1-year overall survival rate (91% v 71%) and time to progression (17 months v 10 months). If the tumor volume was greater than 20 cm(3), we observed comparable treatment results in both groups (1-year survival rate, 60% v 61%; time to progression, 13 months v 12 months). In a long-term follow-up investigation (1999 through 2000), 531 patients (89 women, 442 men) were analyzed according to their toxicities during regular follow-up investigations at our outpatient facility. All patients were treated by surgery or radio(chemo)therapy because of an advanced head and neck cancer. A total of 218 of 531 patients received the antineoplastic therapy without cytoprotection. An additional 313 patients received their RCT combined with amifostine administration before administration of the radiosensitizer. A significant influence of cytoprotection was registered in the following toxicities: xerostomia, fibrosis, loss of taste, and dysphagia. No impact was seen on the development of interstitial lymph edema and esophageal stenosis. Amifostine could be integrated in simultaneous radiochemotherapy of advanced head and neck cancer patients. The authors favor the administration of amifostine before chemotherapeutics alone. Selective cytoprotection could decrease the main acute toxicities (mucositis, xerostomia, dysphagia) as well as late side effects (xerostomia, loss of taste, fibrosis) of this form of combined treatment. The enhanced therapeutic index may be changed into a prognostic benefit for selected patients with unresectable tumors, if the volume is smaller than 20 cm(3).