Dual-color fluorescence cross-correlation spectroscopy on a planar optofluidic chip

Fluorescence cross-correlation spectroscopy (FCCS) is a highly sensitive fluorescence technique with distinct advantages in many bioanalytical applications involving interaction and binding of multiple components. Due to the use of multiple beams, bulk optical FCCS setups require delicate and complex alignment procedures. We demonstrate the first implementation of dual-color FCCS on a planar, integrated optofluidic chip based on liquid-core waveguides that can guide liquid and light simultaneously. In this configuration, the excitation beams are delivered in predefined locations and automatically aligned within the excitation waveguides. We implement two canonical applications of FCCS in the optofluidic lab-on-chip environment: particle colocalization and binding/dissociation dynamics. Colocalization is demonstrated in the detection and discrimination of single-color and double-color fluorescently labeled nanobeads. FCCS in combination with fluorescence resonance energy transfer (FRET) is used to detect the denaturation process of double-stranded DNA at nanomolar concentration.

Results from a low-energy analysis of the CDMS II germanium data

We report results from a reanalysis of data from the Cryogenic Dark Matter Search (CDMS II) experiment at the Soudan Underground Laboratory. Data taken between October 2006 and September 2008 using eight germanium detectors are reanalyzed with a lowered, 2 keV recoil-energy threshold, to give increased sensitivity to interactions from weakly interacting massive particles (WIMPs) with masses below ∼10  GeV/c(2). This analysis provides stronger constraints than previous CDMS II results for WIMP masses below 9  GeV/c(2) and excludes parameter space associated with possible low-mass WIMP signals from the DAMA/LIBRA and CoGeNT experiments.

Mutant p53 protein is targeted by arsenic for degradation and plays a role in arsenic-mediated growth suppression

p53 is frequently mutated in tumor cells, and mutant p53 is often highly expressed due to its increased half-life. Thus, targeting mutant p53 for degradation might be explored as a therapeutic strategy to manage tumors that are addicted to mutant p53 for survival. Arsenic trioxide, a drug for patients with acute promyelocytic leukemia, is found to target and degrade a class of proteins with high levels of cysteine residues and vicinal thiol groups, such as promyelocytic leukemia protein (PML) and PML-retinoic acid receptor α fusion protein. Interestingly, wild type p53 is accumulated in cells treated with arsenic compounds, presumably due to arsenic-induced oxidative stresses. In this study, we found that wild type p53 is induced by arsenic trioxide in tumor cells, consistent with published studies. In contrast, we found that arsenic compounds degrade both endogenous and ectopically expressed mutant p53 in time- and dose-dependent manners. We also found that arsenic trioxide decreases the stability of mutant p53 protein through a proteasomal pathway, and blockage of mutant p53 nuclear export can alleviate the arsenic-induced mutant p53 degradation. Furthermore, we found that knockdown of endogenous mutant p53 sensitizes, whereas ectopic expression of mutant p53 desensitizes, tumor cells to arsenic treatment. Taken together, we found that mutant p53 is a target of arsenic compounds, which provides an insight into exploring arsenic compound-based therapy for tumors harboring a mutant p53.

Conditional β1-integrin-deficient mice display impaired pancreatic β cell function

β1-Integrin, a critical regulator of β cell survival and function, has been shown to protect against cell death and promote insulin expression and secretion in rat and human islet cells in vitro. The aim of the present study was to examine whether the knockout of β1-integrin in collagen I-producing cells would have physiological and functional implications in pancreatic endocrine cells in vivo. Using adult mice with a conditional knockout of β1-integrin in collagen I-producing cells, the effects of β1-integrin deficiency on glucose metabolism and pancreatic endocrine cells were examined. Male β1-integrin-deficient mice display impaired glucose tolerance, with a significant reduction in pancreatic insulin content (p < 0.01). Morphometric analysis revealed a significant reduction in β cell mass (p < 0.001) in β1-integrin-deficient mice, along with a significant decrease in β cell proliferation, Pdx-1 and Nkx6.1 expression when compared with controls. Interestingly, these physiological and morphometric alterations in female β1-integrin-deficient mice were less significant. Furthermore, β1-integrin-deficient mice displayed decreased FAK (p < 0.05) and ERK1/2 (p < 0.001) phosphorylation, reduced cyclin D1 levels (p < 0.001) and increased caspase 3 cleavage (p < 0.01), while no changes in Akt phosphorylation were observed, indicating that the β1-integrin signals through the FAK-MAPK-ERK pathway in vivo. Our results demonstrate that β1-integrin is involved in the regulation of glucose metabolism and contributes to the maintenance of β cell survival and function in vivo.

Prostate cancer outcomes and polymorphism in LHRH and LH receptors and SHBG

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Background: The hypothalamic-pituitary-gonadal axis is integral to androgen synthesis and the management of prostate cancer (PC). Genetic variation in the receptors of this pathway may impact the efficiency of signal transduction and overall clinical course. We examined polymorphisms in four receptors central to this pathway: luteinizing hormone-releasing hormone receptor (LHRHR), luteinizing hormone receptor (LHR), androgen receptor (AR) and steroid hormone binding globulin (SHBG). We examined the association between these genotypes and survival.

Methods: Patients diagnosed with PC between 1999 and 2004 in Los Angeles County were identified using the Los Angeles County Cancer Registry as part of the California Collaborative Prostate Cancer study, a multiethnic, population based case-control study. Included in this analysis were 1232 men with PC: 631 with advanced stage PC at diagnosis and 430 with high-grade PC. The ethnic breakdown was 376 African-American, 355 Hispanic and 501 Caucasian. DNA was extracted from blood and genotypes for LHR, LHRHR, AR and SHBG were assayed using TaqMan or GeneScan methods. Vital status and cause of death was obtained by linking to the Cancer Registry records. Hazard ratios were estimated by fitting Cox proportional hazards models.

Results: As of September 2010, 396 (32%) had died and 122 (10%) had died of PC. In the multivariate model, there was a significant association between disease specific survival and genetic variation in LHRHR, LHR and SHBG. Hazard ratios (HR) for carriers (vs. non-carriers) of the LHR312 minor allele were 1.63 (95% CI: 1.08-2.45) among all cases and 2.04 (1.23-3.39) for high- grade cases. The LHRHR16 minor allele was rare among African Americans; the HR among Caucasians was 1.90 (1.15-3.13) and did not vary by disease grade. The SHGB356 minor allele was associated with survival only among high-grade cases with a HR of 2.38 (1.18-4.81). In addition, when comparing cases to controls, the LHR312 minor allele was inversely associated with PC incidence.

Conclusions: Genetic variation in the LHRHR, LHR and SHGB genes are associated with PC survival and warrant further analysis to define their role as prognostic and predictive markers.

No significant financial relationships to disclose.

Hollow waveguides with low intrinsic photoluminescence fabricated with Ta(2)O(5) and SiO(2) films

A type of integrated hollow core waveguide with low intrinsic photoluminescence fabricated with Ta(2)O(5) and SiO(2) films is demonstrated. Hollow core waveguides made with a combination of plasma-enhanced chemical vapor deposition SiO(2) and sputtered Ta(2)O(5) provide a nearly optimal structure for optofluidic biofluorescence measurements with low optical loss, high fabrication yield, and low background photoluminescence. Compared to earlier structures made using Si(3)N(4), the photoluminescence background of Ta(2)O(5) based hollow core waveguides is decreased by a factor of 10 and the signal-to-noise ratio for fluorescent nanobead detection is improved by a factor of 12.

Speckle contrast in near field scattering limited by time coherence

The relationship between the speckle contrast of scattered light in near field and longitudinal distance that is perpendicular to scattering surface is investigated. The experiment indicates that when using the laser illumination source with proper time coherence length, the curve of speckle contrast vs. longitudinal distance appears minimum turning point. The position and value of minimum point are decided by the coherence of light and scattering matter. It is easy to obtain the correlation area of scattered light by measuring the minimum point position and the illuminated area. Comparing to traditional scattering technique, this method can simultaneously measure the roughness parameters of surface height variance and surface height correlation area.

High dose human insulin and insulin glargine promote T24 bladder cancer cell proliferation via PI3K-independent activation of Akt

BACKGROUND

This study was to investigate the effects of human insulin and insulin glargine on proliferation of T24 human bladder cancer cells and the implication of the PI3K/Akt and MEK/ERK1/2 pathways.

METHODS

After exposure to insulin or glargine at the indicated concentrations for certain time courses, in the absence or presence of inhibitor for MEK (PD98059) or PI3K (LY294002), T24 cell proliferation was evaluated by CCK-8 assay. Phosphorylation of Akt and ERK1/2 was analyzed by Western blot.

RESULTS

Insulin and glargine similarly induced phosphorylation of Akt and slight increases in T24 cell proliferation at 10-100IU/L. LY294002 remarkably reduced T24 cell proliferation in all groups. However, in the presence of LY294002, cell growth was still promoted by insulin and glargine relative to LY294002-treated group. Accordingly, LY294002 profoundly reduced protein levels of pAkt, while insulin and glargine increased pAkt in T24 cells pretreated with LY294002 as compared with cells treated with LY294002 alone. PD98059 reduced pERK while enhanced T24 cell proliferation. Insulin and glargine increased pERK at 15, 30, 60 min, not at 24h.

CONCLUSIONS

High dose human insulin and insulin glargine similarly promoted T24 bladder cancer cell proliferation via PI3K-independent activation of Akt.

Acquisition and baseline performance of working memory tasks by adolescent rhesus monkeys

Adolescence is a transitional stage of development characterized by protracted refinements in the neural circuits required for adult level proficiency of working memory. Because impaired working memory is a hallmark feature of several psychiatric disorders that have their onset during adolescence, model systems that can be used to assess the maturation of working memory function, and of disease-related risk factors that disrupt its development, are of particular importance. However, few studies have investigated the maturation of working memory in nonhuman primates. Thus in the present study, we adapted two working memory tests that are among the most widely used in human and adult nonhuman primates, for adolescent rhesus monkeys. Using a touch-screen apparatus, monkeys were trained on a spatial delayed-response task to assess spatial working memory and a delayed match-to-sample task to assess object working memory. The results indicate that adolescent rhesus monkeys readily and efficiently acquire the ability to perform touch-screen based, complex tests of working memory. These data establish that distinct components of adult prefrontal cortex-dependent cognitive functions can be effectively modeled and evaluated in adolescent monkeys. As such, this approach should be useful for assessing the influence of environmental risk factors on the protracted maturation of working memory in adolescent macaques.

Sonochemotherapy inhibits the adhesion, migration and invasion of human ovarian cancer cells with highly metastatic potential

PURPOSE

Preclinical trials have shown that sonochemotherapy is effective for human ovarian cancers. Therefore, the effects of sonochemotherapy on cell adhesion and motility were investigated in this study, considering their roles in cancer metastasis.

MATERIALS AND METHODS

Cell lines, HO-8910 and its highly metastatic potential subline HO-8910PM, were subjected to cisplatin, paclitaxel and sonochemotherapy (anticancer drugs followed by insonation). Cytotoxicity was determined, and then cell adhesion, migration and invasion assays were performed.

RESULTS

Neither cisplatin (0.5 μg/ml) nor paclitaxel (6.0 μg/ml) alone led to cell death. The addition of ultrasound did not potentiate an anticancer drug, suggesting that there was a threshold dose for a cytotoxic agent employed in sonochemotherapy. The survival rate was decreased when combining cisplatin and paclitaxel followed by insonation. 6.0 μg/ml of paclitaxel completely suppressed cell adhesion and motility, thus the concentration was decreased to 1.2 μg/ml. Migration and invasion assays were only successfully performed in HO-8910PM cells. Cisplatin and paclitaxel inhibited adhesion, migration and invasion, resulting in lower rates, which were additionally decreased by insonation. No cell traveled through the membrane when cisplatin, paclitaxel and ultrasound were combined. Quantitative evaluations indicated that ultrasound enhanced anticancer agents via synergistic and/or additive effects.

CONCLUSION

Ultrasound synergized a combined regime and sonochemotherapy was a measure to suppress cancer spread.