Enhancement of a nano cavity lifetime by induced slow light and nonlinear dispersions.

We start from a 2D photonic crystal nanocavity with moderate Q-factor and dynamically increase it by two order of magnitude by the joint action of coherent population oscillations and nonlinear refractive index.

Nanocavity linewidth narrowing and group delay enhancement by slow light propagation and nonlinear effects.

Slow light induced by coherent population oscillations and cavity dispersive nonlinear response are combined achieving 2 orders of magnitude enhancement of the group delay and an equivalent decreasing of the spectral linewidth of a L3 two-dimensional photonic crystal nanocavity.

Small volume excitation and enhancement of dye fluorescence on a 2D photonic crystal surface.

We demonstrate an easy-to-implement scheme for fluorescence enhancement and observation volume reduction using photonic crystals (PhCs) as substrates for microscopy. By normal incidence coupling to slow 2D-PhC guided modes, a 65 fold enhancement in the excitation is achieved in the near field region (100 nm deep and 1 microm wide) of the resonant mode. Such large enhancement together with the high spatial resolution makes this device an excellent substrate for fluorescence microscopies.

Thermo-optical dynamics in an optically pumped Photonic Crystal nano-cavity.

Linear and non-linear thermo-optical dynamical regimes were investigated in a photonic crystal cavity. First, we have measured the thermal relaxation time in an InP-based nano-cavity with quantum dots in the presence of optical pumping. The experimental method presented here allows one to obtain the dynamics of temperature in a nanocavity based on reflectivity measurements of a cw probe beam coupled through an adiabatically tapered fiber. Characteristic times of 1.0+/-0.2 micros and 0.9+/-0.2 micros for the heating and the cooling processes were obtained. Finally, thermal dynamics were also investigated in a thermo-optical bistable regime. Switch-on/off times of 2 micros and 4 micros respectively were measured, which could be explained in terms of a simple non-linear dynamical representation.

Transition to superdiffusive behavior in intracellular actin-based transport mediated by molecular motors.

Intracellular transport of large cargoes, such as organelles, vesicles, or large proteins, is a complex dynamical process that involves the interplay of adenosine triphosphate-consuming molecular motors, cytoskeleton filaments, and the viscoelastic cytoplasm. In this work we investigate the motion of pigment organelles (melanosomes) driven by myosin-V motors in Xenopus laevis melanocytes using a high-spatio-temporal resolution tracking technique. By analyzing the obtained trajectories, we show that the melanosomes mean-square displacement undergoes a transition from a subdiffusive to a superdiffusive behavior. A stochastic theoretical model, which explicitly considers the collective action of the molecular motors, is introduced to generalize the interpretation of our data. Starting from a generalized Langevin equation, we derive an analytical expression for the mean square displacement, which also takes into account the experimental noise. By fitting theoretical expressions to experimental data we were able to discriminate the exponents that characterize the passive and active contributions to the dynamics and to estimate the "global" motor forces correctly. Then, our model gives a quantitative description of active transport in living cells with a reduced number of parameters.

Combined effects of bevacizumab with erlotinib and irradiation: a preclinical study on a head and neck cancer orthotopic model.

Clinical benefit has been demonstrated in patients with head and neck tumours receiving an anti-epidermal growth factor receptor (EGFR) agent in combination with radiotherapy (RT). Recent preclinical and clinical studies suggest beneficial effects from combining anti-angiogenic drugs with RT. To investigate the effect of combining these approaches, we evaluated in vivo the anti-tumour efficacy of the anti-angiogenic compound bevacizumab, a highly specific monoclonal antibody directed against the vascular endothelial growth factor (VEGF), erlotinib, an EGFR tyrosine kinase inhibitor, and irradiation given alone and in combination. Investigations were performed using a VEGF-secreting human head and neck tumour cell line, CAL33, with a high EGFR content, injected as orthotopic xenografts into the mouth floor of nude mice. Three days after tumour cell injection, bevacizumab (5 mg kg(-1), 5 days a week, i.p.), erlotinib (100 mg kg(-1), 5 days a week, orally) and irradiation (6 Gy, 3 days a week) were administered alone and in combination for 10 days. As compared with the control, concomitant administration of drugs produced a marked and significant supra-additive decrease in tumour mass; the addition of irradiation almost completely abolished tumour growth. The drug association markedly reduced the number of metastatic nodes and the triple combination significantly reduced the total number of pathologically positive lymph nodes as compared with controls. The RT-induced proliferation, reflected by Ki67 labelling, was reduced to control level with the triple combination. Radiotherapy induced a strong and very significant increase in tumour angiogenesis, which was no longer observed when combined with erlotinib and bevacizumab. The efficacy of the combination of bevacizumab+erlotinib and RT may be of clinical importance in the management of head and neck cancer patients.

Increased serum adenosine deaminase activity in schizophrenic receiving antipsychotic treatment.

Adenosine is an important modulator of the nervous system that has been implicated in the pathophysiology of schizophrenia. We studied peripheral adenosine metabolism by determining the activity of serum adenosine deaminase, which converts adenosine into inosine, and 5'-nucleotidase, which converts AMP into adenosine, in 26 DSM-IV male schizophrenic patients under antipsychotic monotherapy and 26 healthy volunteers balanced for age and race. Schizophrenic patients treated either with typical antipsychotics or clozapine showed increased serum adenosine deaminase activity compared to controls (controls=18.96+/-4.61 U/l; typical=25.09+/-10.98 U/l; clozapine=30.32+/-10.83 U/l; p<0.05, ANOVA) and 5'-nucleotidase activity was also increased in patients on clozapine. After adjusting for confounding factors, adenosine deaminase, but not 5'-nucleotidase, alterations remained significant particularly in the clozapine group. This result suggests that either altered adenosine metabolism is present in schizophrenic patients or is influenced by treatment with antipsychotics, particularly clozapine.

Allopurinol augmentation for poorly responsive schizophrenia.

Adenosine has been proposed to contribute to the pathophysiology of schizoprenia and as a target for therapeutic intervention. In the lack of direct adenosine agonists, allopurinol may indirectly elevate adenosine levels by inhibiting degradation of purines. We report two cases of poorly responsive schizophrenic patients who improved considerably with add-on allopurinol 300 mg/day. Their clear clinical improvement warrant further investigation of allopurinol, as well as other purinergic strategies, for the treatment of schizophrenia.