Combined Short-Term Glucose Starvation and Chemotherapy in 3D Colorectal Cancer Cell Culture Decreases 14-3-3 Family Protein Expression and Phenotypic Response to Therapy

Short-term glucose starvation prior to chemotherapy has the potential to preferentially weaken cancer cells, making them more likely to succumb to treatment, while protecting normal cells. In this study, we used 3D cell cultures of colorectal cancer and assessed the effects of short-term glucose starvation and chemotherapy compared to treatment of either individually. We evaluated both phenotypic changes and protein expression levels. Our findings indicate that the combined treatment results in more significant phenotypic responses, including decreased cell viability and clonogenicity. These phenotypic responses can be explained by the decreased expression of LDHA and 14-3-3 family proteins, which were found only in the combined treatment groups. This study indicates that short-term glucose starvation has the potential to increase the efficacy of current cancer treatment regimes.

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Hybrid fluorescent nanoparticles from quantum dots coupled to cellulose nanocrystals

Carboxylated cellulose nanocrystals (CNCs) were decorated with CdSe/ZnS quantum dots (QDs) using a carbodiimide chemistry coupling approach. The one-step covalent modification was supported by nanoscale imaging, which showed QDs clustered on and around the CNCs after coupling. The QD–CNC hybrid nanoparticles remained colloidally stable in aqueous suspension and were fluorescent, exhibiting the broad excitation and narrow emission profile characteristic of the QDs. QD–CNCs in nanocomposite films imparted strong fluorescence within CNC-compatible matrices at relatively low loadings (0.15 nmol QDs/g of dry film), without altering the overall physical properties or self-assembly of the CNCs. The hybrid QD–CNCs may find applications in nanoparticle tracking, bio-imaging, optical/sensing devices, and anti-counterfeit technologies.     

Evidence of upward spread of suppression in DPOAE measurements

Measurements of DPOAE level in the presence of a suppressor were used to describe a pattern that is qualitatively similar to population studies in the auditory nerve and to behavioral studies of upward spread of masking. DPOAEs were measured in the presence of a suppressor (f3) fixed at either 2.1 or 4.2 kHz, and set to each of seven levels (L3) from 20 to 80 dB SPL. In the presence of a fixed f3 and L3 combination, f2 was varied from about 1 oct below to at least 1/2 oct above f3, while L2 was set to each of 6 values (20-70 dB SPL). L1 was set according to the equation L1 = 0.4L2 + 39 [Janssen et al., J. Acoust. Soc. Am. 103, 3418-3430 (1998)]. At each L2, L1 combination, DPOAE level was measured in a control condition in which no suppressor was presented. Data were converted into decrements (the amount of suppression, in dB) by subtracting the DPOAE level in the presence of each suppressor from the DPOAE level in the corresponding control condition. Plots of DPOAE decrements as a function of f2 showed maximum suppression when f2 approximately = f3. As L3 increased, the suppressive effect spread more towards higher f2 frequencies, with less spread towards lower frequencies relative to f3. DPOAE decrement versus L3 functions had steeper slopes when f2 > f3, compared to the slopes when f2 < f3. These data are consistent with other findings that have shown that response growth for a characteristic place (CP) or frequency (CF) depends on the relation between CP or CF and driver frequency, with steeper slopes when driver frequency is less than CF and shallower slopes when driver frequency is greater than CF. For a fixed amount of suppression (3 dB), L3 and L2 varied nearly linearly for conditions in which f3 approximately = f2, but grew more rapidly for conditions in which f3 < f2, reflecting the basal spread of excitation to the suppressor. The present data are similar in form to the results observed in population studies from the auditory nerve of lower animals and in behavioral masking studies in humans.     

Large force fluctuations in a flowing granular medium

We study fluctuations in the force at the boundary of a 2D granular flow. The forces are mainly impulsive at all flow rates. The probability distribution of impulses decays exponentially at large impulses, as do the forces in a static granular medium. At small impulses, the distribution evolves continuously with flow rate with no indication of the transition from collisional flow to intermittently jamming flows. However, the distribution of the time interval between collisions tends to a power law, P(tau) - tau(-3/2), showing a clear dynamical signature of the approach to jamming.     

Crystallization of poly(ethylene oxide) fractions: Crystallization isotherms

The crystallization kinetics of a range of fractions of poly(ethylene oxide) are presented and analyzed. It is concluded that deviations from the Avrami equation with exponent of 3 are mainly due to rejection of low molecular weight molecules for the low molecular weight fractions (M?_n < 6,000) and to a process of crystal perfecting for the high molecular weight fractions (M?_n > 6,000).     

A sharp bound for the degree of proper monomial mappings between balls

The authors prove that a proper monomial holomorphic mapping from the two-ball to the N-ball has degree at most 2N-3, and that this result is sharp. The authors first show that certain group-invariant polynomials (related to Lucas polynomials) achieve the bound. To establish the bound the authors introduce a graph-theoretic approach that requires determining the number of sinks in a directed graph associated with the quotient polynomial. The proof also relies on a result of the first author that expresses all proper polynomial holomorphic mappings between balls in terms of tensor products.     

Vortex collisions: crossing or recombination?

We investigate the collision of two vortex lines moving with viscous dynamics and driven towards each other by an applied current. Using London theory in the approach phase we observe a nontrivial vortex conformation producing antiparallel segments; their attractive interaction triggers a violent collision. The collision region is analyzed using the time-dependent Ginzburg-Landau equation. While we find that vortices will always recombine through the exchange of segments, a crossing channel appears naturally through a double collision process.     

Prediction of structure-dependent charge transfer rates for a Li atom outside a Si(0 0 1) surface

We investigate the broadening of the 2s energy level of a Li atom outside a Si(0 0 1) surface using a first principles approach. The covalent nature of the Si surface produces large variations in Li energy level widths as a function of lateral position across the surface. The widths above symmetric Si dimers are predicted to be much larger than above buckled Si dimers, suggesting that charge transfer will occur primarily above symmetric dimers. We discuss the ramifications of our results on the controversy surrounding the relative abundance of the buckled vs. symmetric dimers on the Si surface.     

An unconventional method for measuring the Tc L3‐edge of technetium compounds

Tc L₃‐edge XANES spectra have been collected on powder samples of SrTcO₃ (octahedral Tc⁴⁺) and NH₄TcO₄ (tetrahedral Tc⁷⁺) immobilized in an epoxy resin. Features in the Tc L₃‐edge XANES spectra are compared with the pre‐edge feature of the Tc K‐edge as well as other 4d transition metal L₃‐edges. Evidence of crystal field splitting is obvious in the Tc L₃‐edge, which is sensitive to the coordination number and oxidation state of the Tc cation. The Tc L₃ absorption edge energy difference between SrTcO₃ (Tc⁴⁺) and NH₄TcO₄ (Tc⁷⁺) shows that the energy shift at the Tc L₃‐edge is an effective tool for studying changes in the oxidation states of technetium compounds. The Tc L₃‐edge spectra are compared with those obtained from Mo and Ru oxide standards with various oxidation states and coordination environments. Most importantly, fitting the Tc L₃‐edge to component peaks can provide direct evidence of crystal field splitting that cannot be obtained from the Tc K‐edge.