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Purpose: This study evaluates the growth inhibiting potential of our previously described sulfonyl chromen-4-ones (CHW09) compound in X-ray irradiated oral cancer cells. Materials and methods: The growth inhibiting effect and mechanism of combined CHW09/X-ray treatment was examined by analyzing cell viability, cell cycle, apoptosis, reactive oxygen species (ROS), and DNA damage. Results: Individual treatments of CHW09 (10 μg/mL) and X-ray irradiation (12 Gy) slightly decreased cell viability of oral cancer Ca9-22 (87.25% and 86.54%) and CAL 27 (80.00% and 74.01%) cells and normal oral HGF-1 cells (92.76% and 87.56%) at 24 h-MTS assay, respectively. In a combined treatment (CHW09/X-ray), the cell viability in Ca9-22 and CAL 27 cells was significantly decreased to 73.48% and 59.07%, whereas HGF-1 cells maintained 84.97% viability in 24 h-MTS assay. For CAL 27 cells, both 72 h-MTS assay and clonogenic assay showed that CHW09/X-ray resulted in more growth inhibition than other treatments. Intracellular ROS levels of CHW09/X-ray were higher than for CHW09, X-ray and control. CHW09/X-ray and X-ray alone had higher G2/M arrest than the control and CHW09 alone. Moreover, flow cytometry and western blotting showed that CHW09/X-ray treatment caused higher apoptosis levels. Levels of H2A histone family member X (γH2AX)-based DNA damage and 8-oxo-2′-deoxyguanosine (8-oxodG)-oxidative DNA damage of CHW09/X-ray were higher than for CHW09, X-ray and control. Conclusion: CHW09/X-ray treatment had additive growth inhibiting effects against X-ray irradiated oral cancer cells, partly attributing to apoptosis and ROS generation. [ABSTRACT FROM AUTHOR]

AbstractClustering is a widely used unsupervised learning technique that groups data into homogeneous clusters. However, when dealing with real-world data that contain categorical values, existing algorithms can be computationally costly in high dimensions and can struggle with noisy data that has missing values. Furthermore, except for one algorithm, no others provide theoretical guarantees of clustering accuracy. In this article, we propose a general categorical data encoding method and a computationally efficient spectral-based algorithm to cluster high-dimensional noisy categorical data (nominal or ordinal). Under a statistical model for data on m attributes from n subjects in r clusters with missing probability ϵ, we show that our algorithm exactly recovers the true clusters with high probability when mn(1−ϵ)≥CMr2 log 3M, with M=max(n,m) and a fixed constant C. In addition, we show that mn(1−ϵ)2≥rδ/2 with 0<δ<1 is necessary for any algorithm to succeed with probability at least (1+δ)/2. In cases where m = n and r are fixed, the sufficient condition matches with the necessary condition up to a polylog(n) factor. In numerical studies our algorithm outperforms several existing algorithms in both clustering accuracy and computational efficiency. Supplementary materials for this article are available online. [ABSTRACT FROM AUTHOR]

PurposeRadiation combined with natural products may improve the radiosensitivity of cancer cells. This study investigated the potential of a combined modality treatment with Ultraviolet C (UVC; wavelength range 200–280 nm) and our previously identified anti-oral cancer agent (methanolic extracts ofCryptocarya concinnaroots; MECCrt) in oral cancer cells. Materials and methodsThe mechanism of the possible synergy of UVC and MECCrt was explored in terms of cell viability, cell cycle, apoptosis, reactive oxygen species (ROS), mitochondrial membrane potential (MitoMP), and DNA damage analyses. ResultsIn cell viability (%) at 24 h treatment, the low doses of UVC (14 J/m2) and MECCrt (10μg/ml) resulted in slight damage to human oral cancer Ca9-22 cells (83.2 and 80.4) but was less harmful to human oral normal HGF-1 cells (93.4 and 91.8, respectively). The combined treatment of UVC and MECCrt (UVC/MECCrt) had a lower viability (54.5%) than UVC or MECCrt alone in Ca9-22 cells but no showed significant change in HGF-1 cells. In Ca9-22 cells, the expression of flow cytometry-based apoptosis (sub-G1 phase, annexin V, and pancaspase assays) was significantly higher in UVC/MECCrt than in UVC or MECCrt alone (p< 0.0001). Using flow cytometry, intracellular ROS levels of UVC/MECCrt and MECCrt alone were higher than for UVC alone. MitoMP change and H2A histone family member X (γH2AX; H2AFX)-based DNA damage were synergistically inhibited and induced by MECCrt/UVC compared to its single treatment in Ca9-22 cells, respectively. ConclusionUVC plus MECCrt treatment had selective killing and synergistic anti-proliferative effects against oral cancer cells involving apoptosis, oxidative stress, and DNA damage. This combination therapy appears to have a great clinical potential against oral cancer cells. [ABSTRACT FROM PUBLISHER]

Accelerated Life Testing (ALT) is used to provide timely estimates of a product's lifetime distribution. Step-Stress ALT (SSALT) is one of the most widely adopted stress loadings and the optimum design of a SSALT plan has been extensively studied. However, few research efforts have been devoted to establishing the theoretical rationale for using SSALT in lieu of other types of stress loadings. This article proves the existence of statistically equivalent SSALT plans that can provide equally precise estimates to those derived from any continuous stress loading for the log-location-scale lifetime distributions with Type-I censoring. That is, for any optimization criterion based on the Fisher information matrix, SSALT is identical in comparison to other continuous stress loadings. The Weibull and lognormal distributions are introduced as special cases. For these two distributions, the relationship among statistical equivalencies is investigated and it is shown that two equivalent ALT plans must be equivalent in terms of the strongest version of equivalency for many objective functions. A numerical example for a ramp-stress ALT, using data from an existing study on miniature lamps, is used to illustrate equivalent SSALT plans. Results show that SSALT is not only equivalent to the existing ramp-stress test plans but also more cost-effective in terms of the total test cost. [ABSTRACT FROM AUTHOR]

Using data from a simple step-stress accelerated life test procedure, a non-parametric proportional hazards model is proposed for obtaining upper confidence bounds for the cumulative failure probability of a product under normal use conditions. The approach is non-parametric in the sense that most of the functions involved in the model do not assume any specific forms, except for certain verifiable conditions. Test statistics are introduced to verify assumptions about the model and to test the goodness of fit of the proposed model to the data. A numerical example, using data simulated from the lifetime distribution of an existing parametric study on metal-oxide semiconductor capacitors, is used to illustrate the proposed methods. Discussions on how to determine the optimal stress levels and sample size are also given. [ABSTRACT FROM PUBLISHER]

The early work on multivariate statistical process control was built upon Hotelling's T[SUP2] control chart which was developed to simultaneously monitor the means of correlated quality variables. This chart, however, has a drawback, namely, the problem of identifying the responsible variable(s) when an out-of-control signal occurs. One alternative is to use a separate &Xbar; control chart for each individual characteristic with equal risks, based on Bonferroni inequality. In this study, we show that, from an economic perspective, it may be desirable to have unequal type I risks for the individual charts, because of different inspection and restoration costs associated with each variable. We obtain their risk ratios, which are measures of relative importance of the variables monitored. Then, based on these risk ratios, we develop computer algorithms for finding the exact control limits for individual variables from a multinormal distribution, in the sense that the overall type I risk of the charts is equal to the desired value. Numerical studies show that the proposed methods give optimal or near-optimal results from an economic as well as statistical point of view. [ABSTRACT FROM AUTHOR]

Shewhart charts are widely accepted as standard tools for monitoring manufacturing processes of univariate, independent, and "nearly" normal measurements. They are not as well developed beyond these types of data. We generalize the idea of Shewhart charts to cover other types of data commonly encountered in practice. More specifically, we develop some valid control charts for dependent data and for independent data that are not necessarily "nearly" normal. We derive the proposed charts from the moving blocks bootstrap and the standard bootstrap methods. Their constructions are completely nonparametric, and no distributional assumptions are required. Some simulated as well as real data examples are included, and they are very supportive of the proposed methods. [ABSTRACT FROM AUTHOR]

A procedure is proposed for screening applications in quality control that eliminates overselection (namely, the condition where the proportion of accepted screened items is greater than the proportion of conforming items in the original population) and controls for individual unit misclassification error (IME), namely, the probability of an accepted/selected item being below specification. Screening involves selecting items whose performance is within specifications based on observing one or more correlated screening variables in lieu of observing the performance variable directly. Overselection and an uncontrollably high IME can occur when (1) there is a high correlation between the performance and screening variables and (2) the proportion of conforming items among accepted items (or its complement, average outgoing quality (AOQ)), is prespecified as in, for example, Owen et al. (1975). We instead propose a procedure that prespecifies a maximum tolerable IME (emaxa) for accepted items, which eliminates overselection and assures that the IME of each outgoing item as well as the AOQ are both equal to or less than emaxa. The quality of each individual item as well as AOQ is thereby explicitly controlled. Only the use of standard normal tables is required to implement our proposed procedure. [ABSTRACT FROM AUTHOR]

When inspection on the performance variable of interest is destructive or costly, it is attractive to use other variables which are correlated with the performance variable and which are inexpensive to inspect as the screening variables. The idea of using a single correlated variable in a complete screening procedure has drawn much attention recently. In this paper, we extend a previously defined economic model for a screening procedure using more than one correlated variable. The screening specifications are based on a linear combination of the correlated variables, and if an item fails to conform to the screening specifications, it is rejected and excluded from shipment. The screening specifications are determined so that the total cost, the sum of three components, is minimized. [ABSTRACT FROM AUTHOR]

The process distribution of a manufacturing process which reflects past experience with the quality levels of outgoing lots is an indispensible input of the Bayesian quality audit systems. A distance-method estimator for the process distribution is developed and shown to be superior to the commonly used method-of-moments estimator. En a continuous manufacturing process, the process distribution needs to be updated after each new lot is inspected. Several updating procedures including the posterior distribution, the exponential smoothing method, the moving window method and the all periods method are proposed and compared by a simulation study. [ABSTRACT FROM AUTHOR]