High speed all-optical PRBS generation based on quantum-dot semiconductor optical amplifiers

A scheme to generate return-to-zero on-off keying (RZ-OOK) high speed all-optical pseudo random bit sequence (PRBS) based on quantum-dot semiconductor optical amplifiers (QD SOA) has been studied. By analyzing the performance of the core functional unit of this system, which is composed of QD SOA-based logic XOR and AND gates, as well as considering the saturation effect of the QD device and noise level of the system, we demonstrated the system's capability of producing stable high speed optical PRBS signals. Results show that the performance of the system depends on a number of parameters, including relaxation lifetime from QD excited state to ground state, injected current density, bit repetition rate, signal pulse width and single pulse energy. For devices with relaxation time approximately 1.0 ps, injected current density >1.8 kA/cm(2), single pulse energy <1.0 pJ with pulse width around 1.0 ps, the system is capable of PRBS generation at speeds of approximately 250 Gb/s.

The physiological role of pre- and postsynaptic GABA(B) receptors in membrane excitability and synaptic transmission of neurons in the rat's dorsal cortex of the inferior colliculus

In the inferior colliculus (IC), GABAergic inhibition mediated by GABA(A) receptors has been shown to play a significant role in regulating physiological responses, but little is known about the physiological role of GABA(B) receptors in IC neurons. In the present study, we used whole-cell patch clamp recording in vitro to investigate the effects of activation of GABA(B) receptors on membrane excitability and synaptic transmission of neurons in the rat's dorsal cortex of the inferior colliculus (ICD). Repetitive stimulation of GABAergic inputs to ICD neurons at high frequencies could elicit a slow and long-lasting postsynaptic response, which was reversibly abolished by the GABA(B) receptor antagonist, CGP 35348. The results suggest that postsynaptic GABA(B) receptors can directly mediate inhibitory synaptic transmission in ICD. The role of postsynaptic GABA(B) receptors in regulation of membrane excitability was further investigated by application of the GABA(B) receptor agonist, baclofen. Baclofen hyperpolarized the cell, reduced the membrane input resistance and firing rate, increased the threshold for generating action potentials (APs), and decreased the amplitude of the AP and its associated after-hyperpolarization. The Ca2+-mediated rebound depolarization following hyperpolarization and the depolarization hump at the beginning of membrane depolarization were also suppressed by baclofen. In voltage clamp experiments, baclofen induced inward rectifying K+ current and reduced low- and high-threshold Ca2+ currents, which may account for the suppression of membrane excitability by postsynaptic GABA(B) receptors. Application of baclofen also reduced excitatory synaptic responses mediated by alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors, and inhibitory synaptic responses mediated by GABA(A) receptors. Baclofen increased the ratios of 2nd/1st excitatory and inhibitory postsynaptic currents to paired-pulse stimulation of the synaptic inputs. These results suggest that fast glutamatergic and GABAergic synaptic transmission in ICD can be modulated by presynaptic GABA(B) receptors.

Apolipoprotein E deficiency abrogates insulin resistance in a mouse model of type 2 diabetes mellitus

AIMS/HYPOTHESIS

Although it is known that lipid metabolism plays a role in insulin resistance in type 2 diabetes and in obesity, the mechanism is still largely unknown. Apolipoprotein E (ApoE) regulates plasma lipid levels and also plays a role in the uptake of lipids into various tissues. To investigate whether the suppression of whole-particle lipoprotein uptake into tissues affects insulin responsiveness and the diabetic condition, we examined the effect of an ApoE (also known as Apoe) gene deletion in MKR mice, a mouse model of type 2 diabetes.

METHODS

ApoE ( -/- ), MKR, ApoE ( -/- )/MKR and control mice were placed on a high-fat, high-cholesterol diet for 16 weeks. Glucose tolerance, serum insulin, blood glucose, insulin tolerance, tissue triacylglycerol content and atherosclerotic lesions were assessed.

RESULTS

ApoE ( -/- )/MKR and ApoE ( -/- ) mice showed significantly improved blood glucose, glucose tolerance and insulin sensitivity. Reduced triacylglycerol content in liver and reduced fat accumulation in liver and adipose tissue were found in ApoE ( -/- )/MKR and ApoE ( -/- ) mice compared with control and MKR mice. ApoE ( -/- ) and ApoE ( -/- )/MKR mice demonstrated similarly large atherosclerotic lesions, whereas MKR and control mice had small atherosclerotic lesions.

CONCLUSIONS/INTERPRETATION

We demonstrated that ApoE deficiency abrogates insulin resistance in a mouse model of type 2 diabetes, suggesting that lipid accumulation in tissue is a major cause of insulin resistance in this mouse model.

The efficacy of chemotherapy in the advanced NSCLC patients who failed with the treatment of EGFR-TKI

e19078

Background: EGFR-TKI such as gefitinib and erlotinib were used as standard 2nd/3rd line therapy in previously treated NSCLC. However, those who benefit from EGFR-TKI will inevitably progress from the disease. We reported the efficacy of chemotherapy(CT) in the advanced NSCLC pts failed with the previously 2nd/3rd line treatment of EGFR-TKIs. Methods: Eligibility criteria included advanced NSCLC pts who got disease control(included CR, PR or SD) initially from TKI therapy and then progressed, PS = 0–2, and normal fatal organ function. Pts received systemic CT (docetaxal, pemetrexed, gemicitabine, novelbine or combined with platinum agent) until disease progression or unacceptable toxicity. Results: 32 pts were enrolled from Oct 15 2007 to Nov 30 2008. Demographics: M 56.3%/F 43.7%; median age 56 y [range 34–72]; stage IV 100%; PS 0/1/2: 3 (9.4%)/22(68.8%)/7(21.8%); adenocarcinoma/non-adenocarcinoma 29(90.6%)/3(9.4%); EGFR-TKI treatment duration >6 m 20(62.5%) /< 6 m 12(37.5%); monotherapy 16 (50%)/ doublets 16 (50%). All pts were evaluable for efficacy; partial response in 5 cases (15.6%), stable disease in 21 cases(37.5%), progressive disease in 15 (46.9%) ( Table ). The response of CT was not related with gender, age, regimens, but these with TKI treatment > 6 m achieved a significantly better response than those < 6 m(p=0.01) and these with PS 0–1 got a marginally significantly better response than PS 2(p=0.095). The toxicity was acceptable. Median progression free survival was 3.4 months and it was not correlated with the gender, age and regimens, but PFS were significant longer in the pts received > 6 m of TKI (median 4.8 vs 1.9, p=0.009) and with PS 0–1 (median 4.7 vs 1.9, p=0.002). Conclusions: Pts benefited from TKI therapy and developed progressive disease could also benefit from CT. The response duration of EGFR-TKI and performance status could be predictive for the better efficacy of CT.

[Table: see text]

No significant financial relationships to disclose.

Adjuvant chemotherapy in completely resected stage III-N2 non-small cell lung cancer

7563

Background: We evaluate effect of postoperative adjuvant chemotherapy on overall survival after complete resection of stage III-N2 non-small-cell lung cancer. Methods: From Jan.1999 to Dec. 2003, a total of 150 stage III-N2 non-small cell lung cancer patients randomly received four cycles of chemotherapy (NVB25mg/m2, D1,D5 or paclitaxel 175mg/m2, D1 / carboplatin AUC=5, D1) or observation after operation. Results: The median survival for the 150 patients was 879 days, with a 1-year survival rate of 81%, 3-year survival rate of 43%, and 5-year survival rate of 28%.There was significant difference in median survival between chemotherapy and control group (897 days vs 821 days p=0.04), and also there was significant difference in 5-year survival rate (30% vs 24% p<0.05). The most common site of recurrence was brain. 26% (39/150) of patients recurred in the brain as their first site, 22% (18/79) for chemotherapy group, 29% (21/71) for control group. The median survival time for brain metastasis patients between chemotherapy and control group is no difference (812 days vs 512 days, p=0.122), but there was significant difference in 2-year survival rate (66.71% vs 37.6% p<0.05). Conclusions: Postoperative adjuvant chemotherapy dose significantly improves median survival among completely resected stage III-N2 non-small-cell lung cancer patients, and significantly improves 5-year survival rate. It dose not decrease incidence of brain metastasis but postpone the time of brain metastasis in chemotherapy group.

No significant financial relationships to disclose.

Effects of immediate compared with delayed gefitinib after front-line chemotherapy in Chinese with advanced non-small cell lung cancer

8069

Background: To compare therapeutic effects of immediate vs. delayed gefitinib used for advanced non-small cell lung cancer (NSCLC) patients who obtained disease control (DC) after front-line chemotherapy in Chinese population. Methods: The study included 121 Chinese with advanced NSCLC treated with standard chemotherapy and obtained DC followed by either immediate gefitinib (66 cases) or delayed gefitinib, i.e. when tumors progressed (55 cases). The disease control rate (DCR), median progression-free survival time (PFS), median overall survival time (OS) of the two groups were analyzed. The impact of EGFR mutation status on the treatments was also evaluated. Results: The median PFS of patients treated in the immediate treatment setting was significantly longer than that of patients without gefitinib treatment (15.23 months versus 8.13 months,P<0.001). However, the overall median PFS was similar in patients treated with either immediate or delayed settings (15.23 months and 16.23 months respectively, P=0.450). There was no significant difference in OS between the two groups. Although patients whose tumors had EGFR mutation showed a longer median PFS compared to those without the mutation in both treatment groups, similar overall PFS was observed between the groups for patients with EGFR mutation (18.75 months and 18.30 months for maintenance and second-line groups, respectively). Conclusions: Immediate gefitinib use may improve PFS for Chinese patients with advanced NSCLC after front-line chemotherapy. However, similar PFS may be achieved by delayed use of gefitinib.

No significant financial relationships to disclose.

Placement of covered stents for the treatment of direct carotid cavernous fistulas

BACKGROUND AND PURPOSE

Endovascular detachable balloon occlusion and coil occlusion are 2 well-established options for the treatment of direct carotid cavernous fistulas (DCCFs). In recent years, covered stents have been applied in the treatment of neurovascular pathologies such as aneurysms, pseudoaneurysms, arterial dissections, and DCCFs. The purpose of this study was to investigate the clinical efficacy of covered stents for the treatment of DCCFs.

MATERIALS AND METHODS

Ten consecutive patients underwent covered-stent placement after failure of detachable balloon occlusion for the treatment of their DCCFs. Clinical and angiographic follow-up ranged from 5 to 48 months (mean, 18.2 months) after stent placement.

RESULTS

Stent placement was technically successful in all except 1 patient. In this patient, stent placement failed after multiple attempts because of rigidity of the Jostent GraftMaster Coronary Stent Graft and the tortuous anatomy of the internal carotid artery (ICA). Complete exclusion of the fistula was achieved in 6 patients immediately after stent deployment. Endoleak was observed in 3 patients. Re-dilation of the stent avoided the endoleak in 2 patients; in 1 of these 2 patients, formerly improved symptoms recurred the next morning and the ipsilateral ICA was occluded with detachable balloons. Spasm of the ICA was observed in most of the patients after stent placement; however, angioplasty was not required. Symptoms improved in all patients after treatment, without thromboembolic events. Follow-up cerebral angiography showed complete exclusion of all DCCFs and stent patency without intrastent stenosis in the 8 patients who had successful deployment of the stent.

CONCLUSIONS

Although a larger sample and expanded follow-up are needed, our series shows that covered stents can be used in the treatment of DCCFs with symptomatic relief.

Inhibition of allergic responses by CD40 gene silencing

BACKGROUND

Gene silencing using small interfering RNA (siRNA) is a potent method of specifically knocking down molecular targets. Small interfering RNA is therapeutically promising, however, treatment of allergic diseases with siRNA has not been explored in vivo. The aim of this study was to evaluate therapeutic effects of CD40 siRNA on inhibition of allergic responses.

METHODS

Mice sensitized with ovalbumin (OVA) and alum were treated with CD40 siRNA, scrambled siRNA, or phosphate buffer saline (PBS) alone, and then challenged intranasally with OVA.

RESULTS

A significant reduction in nasal allergic symptoms was observed in the CD40 siRNA treated OVA-allergic mice compared to the controls of scrambled siRNA and PBS alone, which is correlated with the decrease of local eosinophil accumulation. CD40 siRNA treatment knocked down CD40 expression on dendritic cells (DCs) in vivo and impaired their antigen presenting function. Treatment with CD40 siRNA resulted in inhibition of OVA-specific T cell response and decrease of interleukin-4 (IL-4), IL-5, and interferon-gamma production from T cells stimulated with OVA. Administration of CD40 siRNA also suppressed CD40 expression on B cells, resulting in down-regulation of OVA-specific immunoglobulin E (IgE), IgG1, and IgG2a levels. Additionally, increased regulatory T cells were observed in the CD40 siRNA treated mice.

CONCLUSIONS

The present study demonstrates a novel therapeutic use for siRNA in allergy. CD40 siRNA attenuated allergy through inhibition of DC and B cell functions and generation of regulatory T (Treg) cells.

Search for maximal flavor violating scalars in same-charge lepton pairs in pp collisions at sqrt[s]=1.96 TeV

Models of maximal flavor violation (MxFV) in elementary particle physics may contain at least one new scalar SU(2) doublet field Phi(FV)=(eta(0),eta(+)) that couples the first and third generation quarks (q_(1), q_(3)) via a Lagrangian term L(FV)=xi(13)Phi(FV)q(1)q(3). These models have a distinctive signature of same-charge top-quark pairs and evade flavor-changing limits from meson mixing measurements. Data corresponding to 2 fb(-1) collected by the Collider Dectector at Fermilab II detector in pp[over ] collisions at sqrt[s]=1.96 TeV are analyzed for evidence of the MxFV signature. For a neutral scalar eta(0) with m_(eta;(0))=200 GeV/c(2) and coupling xi(13)=1, approximately 11 signal events are expected over a background of 2.1+/-1.8 events. Three events are observed in the data, consistent with background expectations, and limits are set on the coupling xi(13) for m(eta(0)=180-300 GeV/c(2).

Antiarrhythmic drug therapy for atrial fibrillation: focus on atrial selectivity and safety

Atrial fibrillation (AF) is a highly prevalent arrhythmia and responsible for significant morbidity, mortality and health care cost. The prevalence of AF is expected to increase markedly with the aging population. The use of conventional antiarrhythmic agents has been limited by potentially fatal ventricular proarrhythmia. Rhythm control could become the preferred treatment strategy for AF if antiarrhythmic agents that are similarly or more effective, but safer, than currently approved AF agents become available. A subanalysis of the Atrial Fibrillation Follow-Up Investigation of Rhythm Management (AFFIRM) trial data showed that normal sinus rhythm confers a survival benefit in AF, suggesting that rhythm control, if achieved without the adverse effects related to current antiarrhythmic medications, may offer a significant survival advantage over rate control. Considerable work has been performed to explore novel, potentially safer antiarrhythmic drug targets for AF therapy, and some of these drug targets are currently being tested in experimental and clinical proof of concept studies. This article summarizes relevant aspects of the cellular electrophysiology of AF and reviews the actions of pharmacological agents being considered for the prevention and treatment of AF, focusing on atrial selective antiarrhythmic agents. A variety of drugs that inhibit the atrium-specific ultra rapid delayed rectifier potassium current (IKur) are being evaluated pre-clinically, but human experience with these agents is limited. The acetylcholine-activated current (IKACh) is another novel candidate target for atrial-specific drug therapy. The constitutively active form of this current is increased in human AF and pharmacological inhibition might be of therapeutic value. Certain drugs have IKACh blocking properties, but similar to IKur-blockers, none have been shown to have pure selectivity for this current. Newer agents being studied also include gap junction modulators and angiotensin-converting enzyme inhibitors. There is great hope that at least some of these agents will ultimately be available for effective and safer clinical treatment and prevention of AF.

[Use of automated bactec MGIT 960 system in the diagnosis of resistance to reserve drugs agents in Samara]

The paper gives the results of a demonstration project to introduce a test for drug sensitivity to second-line antituberculous agents for patients with multidrug-resistant (MDR) tuberculosis at a routine large Russian laboratory. Two hundred and thirty MDR isolates were examined; of them 8.7% had extreme drug resistance. The cost of this test was estimated to be US $ 33.4. The introduction of this test is possible and essential for the precise and timely choice of antituberculous therapy for patients with MDR tuberculosis.