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.

A Proficient Approach to the Production of Therapeutic Glucagon-Like Peptide-1 (GLP-1) in Transgenic Plants

Glucagon-like peptide-1 (GLP-1) is a small peptide hormone with potent insulinotropic activity and represents a promising new therapeutic tool for the treatment of diabetes. Like many other therapeutic peptides, GLP-1 is commonly produced using chemical synthesis methods, but is limited by product quantity and cost. The advent of recombinant DNA technology offers the possibility of producing GLP-1 inexpensively and in vast quantities. In this study, transgenic plants were used as a recombinant expression platform for the production of GLP-1 as a large multimeric protein. A synthetic gene encoding ten sequential tandem repeats of GLP-1 sequence (GLP-1x10) was produced and introduced into tobacco plants. Transcriptional expression of the GLP1x10 gene in transgenic plants was confirmed by RT-PCR. Western blot analysis showed that the GLP-1x10 protein efficiently accumulated in transgenic plants, with an accumulation level as high as 0.15% of total soluble protein in leaves. Importantly, insulin secretion assays using a mouse pancreatic β cell line (MIN6), showed that plant-derived GLP-1 in its synthetic decamer form, retained its ability to stimulate cellular insulin secretion, although with reduced efficacy. These results demonstrate that transgenic plants are an efficient system for the production of a multimerized recombinant GLP-1. Moreover, transgenic plants synthesizing high levels of GLP-1x10 may prove to be an attractive delivery system for direct oral administration of a novel stable GLP-1 analog in the treatment of patients with Type 2 diabetes.

Effects of Storage Temperature on the Shelf Life of One-step and Two-step Self-etch Adhesives

Storage temperature affects the alteration rate of one-step adhesives for all-in-one adhesive systems and self-etching primer for two-step adhesive systems. Their shelf life is strongly dependent on the storage temperature and time period. Storage under 20°C extends their shelf life.

Anti-biofilm effect of dental adhesive with cationic monomer

The incorporation of polymerizable cationic monomers has been attempted to generate dental resinous materials with antibacterial activity. This study tested the hypothesis that a dental adhesive containing a cationic monomer, methacryloxylethyl cetyl dimethyl ammonium chloride (DMAE-CB), would influence biofilm formation and gtf gene expression of Streptococcus mutans. The effect of the photo-polymerized DMAE-CB-incorporated adhesive on in vitro biofilm accumulation was investigated with spectrophotometry and scanning electron microscopy. The relative level of gtf gene expression by Streptococcus mutans in the biofilm was quantified by real-time reverse-transcription polymerase chain-reaction. The DMAE-CB-incorporated adhesive significantly decreased bio-film accumulation on its surface (P < 0.05), and suppressed the expression of gtfB and gtfC of Streptococcus mutans in the biofilm (P < 0.05). The results suggest that the cured DMAE-CB-incorporated adhesive may hamper biofilm accumulation via selective down-regulation of the expression of gtf genes in Streptococcus mutans.

Concomitant pemetrexed/carboplatin chemotherapy with 3-D conformal radiotherapy followed by pemetrexed/carboplatin consolidation chemotherapy in locally advanced non-small cell lung cancer in a Chinese population

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Background: Pemetrexed in combination with carboplatin has been shown to have promising activity, as well as superior toxicity profile in advanced non-small cell lung cancer(NSCLC). Radiotherapy(RT) has been shown to improve survival of patients with locally advanced NSCLC when combined with other platin doublets. This phase II study of concomitant pemetrexed/carboplatin chemotherapy(CT) with 3-D conformal RT followed by pemetrexed/carboplatin consolidation CT in locally advanced NSCLC was designed to evaluate the efficacy and safety of this novel regimen. This report presents preliminary information of 10 patients who have completed treatment. Methods: 10 chemoradiation (CRT)-naive and stage IIIA or IIIB (not effusion) with KPS≥80 patients were included in this study between February 2008 and October 2008. Patients received pemetrexed 500 mg/m2, carboplatin AUC 5 CT repeated q3 weeks for 2 cycles concomitant with RT and 3 cycles of consolidation pemetrexed (500 mg/m2) and carboplatin (AUC=5) q3 weeks. Median total dose of RT, without elective nodal irradiation, was 62 Gy (range: 60-66 Gy) with 2 Gy daily fractions. Results: 1 (10%) and 8 patients (80%) had a complete or partial response respectively, while 1 patient(10%) had progression of the disease(brain metastases). The overall response rate (90%,95% confidence interval (CI): 68%-97%) exceeded the goal per study design. After concomitant CRT, the main toxicity was neutropenia, with a median ANC nadir of 1.6, three patients had Grade 3 neutropenia, One patient had Grade 4 neutropenia. Grade 3 thrombocytopenia was seen in one patient, grade 3 esophagitis in one patient and grade 3 radiation pneumonitis in one patient. Consolidation CT was not administered to 3 patients- one due to the development of brain metastases during the first month after chemoradiation, one due to patient refusal and one due to grade 3 radiation pneumonitis. Conclusions: This preliminary data suggests that concomitant treatment was well tolerated, with promising activity and a significant improvement of QoL in a Chinese population with locally advanced NSCLC.

No significant financial relationships to disclose.

FDG-PET/CT imaging for staging and definition of tumor volumes in radiation treatment planning in non-small cell lung cancer

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Background: 18F-fluorodeoxyglucose (FDG)-positron emission tomography (PET) /computed tomography (CT) has a potential improvement for staging and radiation treatment (RT) planning of various tumor sites. But from a clinical standpoint, the open questions are essentially the following: to what extent does PET/CT change the target volume? Can PET/CT reduce inter-observer variability in target volume delineation? We analyzed the use of FDG-PET/ CT images for staging and evaluated the impact of FDG- PET/CT on the radiotherapy volume delineation compared with CT in patients with non-small cell lung cancer (NSCLC) candidates for radiotherapy. Intraobserver variation in delineating tumor volumes was also observed. Methods: Twenty-three patients with stage I-III NSCLC were enrolled in this pilot study and were treated with fractionated RT based therapy with or without chemotherapy. FDG-PET/CT scans were acquired within 2 weeks prior to RT. PET and CT data sets were sent to the treatment planning system Pinnacle through compact disc. The CT and PET images were subsequently fused by means of a dedicated radiation treatment planning system. Gross Tumor Volume (GTV) was contoured by four radiation oncologists respectively on CT (CT-GTV) and PET/CT images (PET/CT-GTV). The resulting volumes were analyzed and compared. Results: For the first phase, two radiation oncologists outlined together the contours achieving a final consensus. Based on PET/CT, changes in TNM categories occurred in 8/23 cases (35%). Radiation targeting with fused FDG-PET and CT images resulted in alterations in radiation therapy planning in 12/20 patients (60%) by comparison with CT targeting. The most prominent changes in GTV have been observed in cases with atelectasis. For the second phase was four intraobserver variation in delineating tumor volumes. The mean ratio of largest to smallest CT-based GTV was 2.31 (range 1.01–5.96). The addition of the PET data reduced the mean ratio to 1.46 (range 1.12–2.27). Conclusions: PET/CT fusion images could have a potential impact on both tumor staging and treatment planning. Implementing matched PET/CT reduced observer variation in delineating tumor volumes significantly with respect to CT only.

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Desmosine as a biomarker of elastin degradation in COPD: current status and future directions

Desmosine (DES) and isodesmosine (IDES) are two unusual, tetrafunctional, pyridinium ring-containing amino acids involved in elastin cross-linking. Being amino acids unique to mature, cross-linked elastin, they are useful for discriminating peptides derived from elastin breakdown from precursor elastin peptides. According to these features, DES and IDES have been extensively discussed as potentially attractive indicators of elevated lung elastic fibre turnover and markers of the effectiveness of agents with the potential to reduce elastin breakdown. In the present manuscript, immunology-based and separation methods for the evaluation of DES and IDES are discussed, along with studies reporting increased levels of urine excretion in chronic obstructive pulmonary disease (COPD) patients with and without alpha(1)-antitrypsin deficiency. The results of the application of DES and IDES as surrogate end-points in early clinical trials in COPD are also reported. Finally, recent advances in detection techniques, including liquid chromatography tandem mass spectrometry and high-performance capillary electrophoresis with laser-induced fluorescence, are discussed. These techniques allow detection of DES and IDES at very low concentration in body fluids other than urine, such as plasma or sputum, and will help the understanding of whether DES and IDES are potentially useful in monitoring therapeutic intervention in COPD.

Singapore's burden of disease and injury 2004

INTRODUCTION

The Singapore Burden of Disease (SBoD) Study 2004 provides a comprehensive and detailed assessment of the size and distribution of health problems in Singapore. It is the first local study to use disability-adjusted life years (DALYs) to quantify the total disease burden.

METHODS

The SBoD study applied the methods developed for the original Global Burden of Disease study to data specific to Singapore to compute the DALYs. DALY is a summary measure of population health that combines time lost due to premature mortality (years of life lost [YLL]) with time spent in ill-health (broadly-termed disability) arising from incident cases of disease or injury (years of life lost due to disability [YLD]). DALYs, stratified by gender and age group, were calculated for more than 130 specific health conditions for the Singapore resident population for the year 2004.

RESULTS

In 2004, diabetes mellitus, ischaemic heart disease and stroke were the top three leading causes of premature death and ill-health in Singapore, and together accounted for more than one-quarter (28 percent) of the total disease burden (in DALYs). Morbidity burden (YLD) was responsible for 52 percent of the total DALYs, with diabetes mellitus, anxiety and depression, and Alzheimer's disease and other dementias being the main sources of the total YLDs. Ischaemic heart disease, stroke and lung cancer were the major contributors to the premature mortality burden (YLL).

CONCLUSION

This study provides an objective and systematic assessment of the fatal and nonfatal health conditions in Singapore to support priority setting in public health policies and research.

Multiwavelength fiber ring laser based on a semiconductor and fiber gain medium

We report a novel multi-wavelength laser source based on hybrid gain medium, with a semiconductor optical amplifier and erbium doped fiber amplifier, and a double-ring structure. More than 60 lines with more than 50 dB signal-to-noise ratio (SNR) have been achieved in our setup. The wavelength interval between the wavelengths is approximately 0.32 nm. The 3 dB spectral width of each lasing line is approximately 0.019 nm. The laser can be tuned from approximately 1526 nm to approximately 1562 nm by adjusting the loss in the cavity.

Increased fear- and stress-related anxiety-like behavior in mice lacking tuberoinfundibular peptide of 39 residues

Tuberoinfundibular peptide of 39 residues (TIP39) is synthesized by two groups of neurons, one in the subparafascicular area at the caudal end of the thalamus and the other in the medial paralemniscal nucleus within the lateral brainstem. The subparafascicular TIP39 neurons project to a number of brain regions involved in emotional responses, and these regions contain a matching distribution of a receptor for TIP39, the parathyroid hormone 2 receptor (PTH2-R). We have now evaluated the involvement of TIP39 in anxiety-related behaviors using mice with targeted null mutation of the TIP39 gene (Tifp39). Tifp39(-/-) mice (TIP39-KO) did not significantly differ from wild-type (WT) littermates in the open field, light/dark exploration and elevated plus-maze assays under standard test conditions. However, the TIP39-KO engaged in more active defensive burying in the shock-probe test. In addition, when tested under high illumination or after restraint, TIP39-KO displayed significantly greater anxiety-like behavior in the elevated plus-maze than WT. In a Pavlovian fear-conditioning paradigm, TIP39-KO froze more than WT during training and during tone and context recall but showed normal fear extinction. Disruption of TIP39 projections to the medial prefrontal cortex, lateral septum, bed nucleus of the stria terminalis, hypothalamus and amygdala likely account for the fear- and anxiety-related phenotype of TIP39-KO. Current data support the hypothesis that TIP39 modulates anxiety-related behaviors following environmental provocation.

Studies of SARS virus vaccines

1. Intranasal vaccination using inactivated SARS coronavirus (SARS-CoV) vaccine with adjuvant can induce strong systemic (serum immunoglobulin [Ig] G) and respiratory tract local (tracheal-lung wash fluid IgA) antibody responses with neutralising activity. 2. RBD-Fc (protein-based vaccine) is able to induce effective neutralising antibodies able to provide protection from SARS-CoV infection in animal models. 3. A single dose of RBD-rAAV vaccination can induce adequate neutralising antibody against SARS-CoV infection. 4. Additional doses of vaccine increased the production of neutralising antibody 5-fold compared with a single dose. 5. RBD-rAAV vaccination provoked a prolonged antibody response with continually increasing levels of neutralising activity. 6. Intranasal vaccination with RBD-rAAV induced local IgA and systemic IgG neutralising antibodies and specific T-cell responses, able to protect against SARS-CoV infection in animal models. 7. When compared with the RBD-rAAV prime/boost vaccination, RBD-rAAV prime/RBD-peptide boost induced similar levels of Th1 and neutralising antibody responses that protected vaccinated mice from subsequent SARS-CoV challenges,but stronger Th2 and CTL responses. 8. Overall, our findings suggest that the inactivated vaccine, RBD-Fc and RBD-rAAV, can be further developed into effective and safe vaccines against SARS and that intranasal vaccination may be the preferred route of administration.

Chronic intermittent hypoxia sensitizes acute hypothalamic-pituitary-adrenal stress reactivity and Fos induction in the rat locus coeruleus in response to subsequent immobilization stress

Obstructive sleep apnea (OSA) is associated with several pathophysiological conditions, including hypertension, obesity, insulin resistance, hypothalamic-pituitary-adrenal (HPA) dysregulation, and other endocrine and metabolic disturbances comprising the "metabolic syndrome." Repeated episodes of hypoxia in OSA may represent a chronic intermittent stress, leading to HPA dysregulation. Alterations in HPA reactivity could then contribute to or exacerbate other pathophysiological processes. We showed previously that another metabolic stressor, chronic intermittent cold stress, enhanced noradrenergic facilitation of acute HPA stress reactivity. In this study, we investigated whether chronic intermittent hypoxia (CIH), a rat model for the arterial hypoxemia that accompanies OSA, similarly sensitizes the HPA response to novel acute stress. Rats were exposed to CIH (alternating cycles of normoxia [3 min at 21% O(2)] and hypoxia [3 min at 10% O(2)], repeated continuously for 8 h/day during the light portion of the cycle for 7 days). On the day after the final CIH exposure, there were no differences in baseline plasma adrenocorticotropic hormone (ACTH), but the peak ACTH response to 30 min acute immobilization stress was greater in CIH-stressed rats than in controls. Induction of Fos expression by acute immobilization stress was comparable following CIH in several HPA-modulatory brain regions, including the paraventricular nucleus, bed nucleus of the stria terminalis, and amygdala. Fos induction was attenuated in lateral hypothalamus, an HPA-inhibitory region. By contrast, acute Fos induction was enhanced in noradrenergic neurons in the locus coeruleus following CIH exposure. Thus, similar to chronic cold stress, CIH sensitized acute HPA and noradrenergic stress reactivity. Plasticity in the acute stress response is important for long-term adaptation, but may also contribute to pathophysiological conditions associated with states of chronic or repeated stress, such as OSA. Determining the neural mechanisms underlying these adaptations may help us better understand the etiology of such disorders, and inform the development of more effective treatments.