Like the majority of host cell mRNAs, the mRNAs of influenza virus are capped and polyadenylated. The NS1 protein of influenza has been implicated as a translational activator for both influenza and reporter gene mRNAs. Data is presented showing that influenza A virus infection resulted in an increased ratio of cap-dependent to cap-independent translation. This ratio increase was largely due to an increase in cap-dependent translation. These experiments employed a bicistronic reporter construct measuring cap-dependent and cap-independent translation in a single sample. Expression of NS1 alone resulted in a small, but reproducible increase in the ratio of cap-dependent to cap-independent translation. Additionally, with use of an NS1 deleted mutant influenza A virus (delNS1) it is shown that infection without NS1 expression produced less of a translation ratio increase compared to wild-type virus infection. Furthermore, expression of NS1 rescued a more wild-type ratio increase in delNS1 infected Vero cells. These results implicate NS1 as playing a role in increasing the ratio of cap-dependent to cap-independent translation in influenza A virus infected cells. Additionally, eIF4E-binding protein-1 (4E-BP1), a member of the protein family that inhibits cap-dependent translation through their inhibition of the cap-binding protein, eukaryotic initiation factor 4E (eIF4E), is shown to be inactivated throughout the majority of the influenza A virus infection process.

無 / In this article, a two-step process is considered to investigate the effects of measurement errors on EWMA and cause-selecting EWMA control charts. At the end of current process, a pair of imprecise measurements of in-coming quality and out-going quality is randomly taken with individual units. The linear relationship between in-coming quality and out-going quality is assumed and four possible states of the process are defined with respective distributions of in-coming and out-going qualities derived. The EWMA control chart with measurement error is then constructed to monitor small-scale shift in mean for the previous process while the cause-selecting control chart, or EWMA control chart based on residuals, including measurement error, is proposed to diagnose the state of current process. Based on sensitivity analysis, the presence of imprecise measurement diminishes the power of both the EWMA and the proposed control charts and affects the detectability of process disturbances. Further, applications of proposed control charts are demonstrated through a numerical example to show some possible misuses of control charts. If the process mean shifts in a small scale when a single assignable cause occurs on each step, the proposed cause-selecting control chart is more sensitive than other control charts. The Hotelling T^2 control chart is also compared to illustrate the diagnostic advantage outweighed by proposed cause-selecting control chart.

<p>Abstract: Considering the Schrödinger equation $\Delta_x u = i\partial{u}/\partial{t}$, we have a solution $u$ on the form $$u(x, t)= (2\pi)^{-n} \int_{\RR} {e^{i x\cdot \xi}e^{it|\xi|^2}\widehat{f}(\xi)}\, d \xi, x \in \RR, t \in \mathbf{R}$$ where $f$ belongs to the Sobolev space. It was shown by Sjögren and Sjölin, that assuming $\gamma : \mathbf{R}_+ \rightarrow \mathbf{R}_+ $ being a strictly increasing function, with $\gamma(0) = 0$ and $u$ and $f$ as above, there exists an $f \in H^{n/2} (\RR)$ such that $u$ is continuous in $\{ (x, t); t>0 \}$ and $$\limsup_{(y,t)\rightarrow (x,0),|y-x|<\gamma (t), t>0} |u(y,t)|= + \infty$$ for all $x \in \RR$. This theorem was proved by choosing $$\widehat{f}(\xi )=\widehat{f_a}(\xi )= | \xi | ^{-n} (\log | \xi |)^{-3/4} \sum_{j=1}^{\infty} \chi _j(\xi)e^{- i( x_{n_j} \cdot \xi + t_j | \xi | ^a)}, \, a=2,$$ where $\chi_j$ is the characteristic function of shells $S_j$ with the inner radius rapidly increasing with respect to $j$. The purpose of this essay is to explain the proof given by Sjögren and Sjölin, by first showing that the theorem is true for $\gamma (t)=t$, and to investigate the result when we use $$S^a f_a (x, t)= (2 \pi)^{-n}\int_{\RR} {e^{i x\cdot \xi}e^{it |\xi|^a}\widehat{f_a}(\xi)}\, d \xi$$ instead of $u$.</p>

Non-insulin diabetes mellitus (NIDDM) is a major health problem affecting U.S. Mexicans. A population of Southwestern Arizona, near the U.S.-Mexico border, was studied to assess the biocultural environment in which disease develops, and to determine risk factors affecting the population. This geographic area is home to a high percentage of farmworkers of Mexican origin or ancestry. A global overview of macro- and micro-level issues was used to provide the context in which the population lives, and where the disease emerges and is maintained. The discussion of historical, economic, demographic, and social issues provide the background for the understanding of the natural and the social environments. Anthropological methods and techniques were used to assess and analyze numerous factors to determine the most useful for the identification of NIDDM risk. Methods used for data gathering included anthropometric measurements, survey instruments, ethnographic interviews, life history, and participant observation. Fifty-seven households participated in the study. A total of 212 subjects were measured; a sub-sample of 79 adults was also interviewed. The study identified 17 diabetics (12 females, 5 males). Prevalence of NIDDM for the sampled population was calculated at 8.2 percent. The rate was higher among females than among males. Diabetics were older than 45 years of age, were in poor health, had more than one source of income, and depended on social safety net assistance; high parity was characteristic of diabetic females. Diabetics' blood glucose (B.G.) levels were higher than those of non-diabetics, regardless of the variables tested. Known risk factors for NIDDM were not found to be significantly strong in the determination of diabetic status nor of B.G. levels. However, the ethnographic and quantitative data suggested that physiological variables may be affected by work and occupational related risks, diluting the prediction strength of known NIDDM risk factors. The yearly cycles of farm work and the physiological demands of the tasks involved are probably the most salient risk factors in farmworkers' lives. Recommendations are provided for the incorporation of anthropological theory, methods and techniques to the study of disease processes, and for the design of public health strategies.

No description available.

Numerous experiments have demonstrated that the activity of neurons can alter the strength of excitatory synapses. This synaptic plasticity is bidirectional and synapses can be strengthened (potentiation) or weakened (depression). Synaptic plasticity offers a mechanism that links the ongoing activity of the brain with persistent physical changes to its structure. For this reason it is widely believed that synaptic plasticity mediates learning and memory. The hypothesis that synapses store memories by modifying their strengths raises an important issue. There should be a balance between the necessity that synapses change frequently, allowing new memories to be stored with high fidelity, and the necessity that synapses retain previously stored information. This is the plasticity stability dilemma. In this thesis the plasticity stability dilemma is studied in the context of the two dominant paradigms of activity dependent synaptic plasticity: Spike timing dependent plasticity (STDP) and long term potentiation and depression (LTP/D). Models of biological synapses are analysed and processes that might ameliorate the plasticity stability dilemma are identified. Two popular existing models of STDP are compared. Through this comparison it is demonstrated that the synaptic weight dynamics of STDP has a large impact upon the retention time of correlation between the weights of a single neuron and a memory. In networks it is shown that lateral inhibition stabilises the synaptic weights and receptive fields. To analyse LTP a novel model of LTP/D is proposed. The model centres on the distinction between early LTP/D, when synaptic modifications are persistent on a short timescale, and late LTP/D when synaptic modifications are persistent on a long timescale. In the context of the hippocampus it is proposed that early LTP/D allows the rapid and continuous storage of short lasting memory traces over a long lasting trace established with late LTP/D. It is shown that this might confer a longer memory retention time than in a system with only one phase of LTP/D. Experimental predictions about the dynamics of amnesia based upon this model are proposed. Synaptic tagging is a phenomenon whereby early LTP can be converted into late LTP, by subsequent induction of late LTP in a separate but nearby input. Synaptic tagging is incorporated into the LTP/D framework. Using this model it is demonstrated that synaptic tagging could lead to the conversion of a short lasting memory trace into a longer lasting trace. It is proposed that this allows the rescue of memory traces that were initially destined for complete decay. When combined with early and late LTP/D iii synaptic tagging might allow the management of hippocampal memory traces, such that not all memories must be stored on the longest, most stable late phase timescale. This lessens the plasticity stability dilemma in the hippocampus, where it has been hypothesised that memory traces must be frequently and vividly formed, but that not all traces demand eventual consolidation at the systems level.

<p>The Ras family of small GTPases, comprised of the KRAS, NRAS, and HRAS genes, are mutated to encode constitutively-active, GTP-bound, oncogenic proteins in upwards of one quarter or more of all human cancers, which is well established to promote tumorigenesis. Despite the prominent role these genes play in human cancer, the encoded proteins have proven difficult to pharmacologically inhibit. Therefore, it is important to understand how Ras proteins are activated. </p><p>RAS proteins cycle between a GDP-bound inactive state and a GTP-bound active state through guanine nucleotide exchange factors (GEFs) and GTPase activating proteins (GAPs). GEFs facilitate the GDP-to-GTP exchange of RAS and promote RAS activation. Similar to GEFs, reactive oxygen/nitrogen species can also promote RAS activation through reactions with the thiol residue of cysteine 118 (C118). This residue may therefore play a role in RAS activation in cancer. To test this possibility, I investigated the effect of mutating C118 to serine (C118S) in Kras on (1) carcinogen-induced lung tumorigenesis, and (2) xenograft tumor growth of HRAS12V-transformed cells.</p><p>To explore the impact of the C118S mutation in Kras on carcinogen-induced lung tumorigenesis, I introduced a C118S mutation into the endogenous murine Kras allele and exposed the resultant mice to the carcinogen urethane, which induces Kras mutation-positive lung tumors. Kras+/C118S and KrasC118S/C118S mice developed fewer and smaller lung tumors than Kras+/+ mice. Although the KrasC118S allele did not appear to affect tumorigenesis when the remaining Kras allele was conditionally oncogenic (KrasG12D), there was a moderate imbalance of oncogenic mutations favoring the native Kras allele in tumors from Kras+/C118S mice treated with urethane. Therefore, mutating C118 of Kras impedes urethane-induced lung tumorigenesis.</p><p>To explore the the impact of the C118S mutation in Kras on xenograft tumor growth of HRAS12V-transformed cells, I tested and found that redox-dependent reactions with cysteine 118 (C118) and activation of wild type KRAS are critical for oncogenic HRAS-driven tumorigenesis. Such redox-dependent activation of KRAS affected both PI3K-AKT and RAF-MEK-ERK pathways. These findings were confirmed in the endogenous mouse Kras gene. Speicfically, oncogenic HRAS-transformed KrasC118S/C118S MEFs grew in soft agar and as xenograft tumors more slowly than similarly transformed Kras+/+ MEFs, suggesting that redox-dependent reactions with C118 of Kras promotes transformation and tumorigenesis. </p><p>Taken together, I have demonstrated a critical role of redox-dependent reactions with Kras C118 in tumorigenesis.</p> / Dissertation

QC 351 A7 no. 65 / The significance of signal-dependent noise is discussed. Particular emphasis is placed on the type of multiplicative noise present in the density variations in a photographic emulsion. A theoretical treatment of the effect of multiplicative noise on signal detection and signal discrimination problems is presented. Optimum test statistics are derived for processing a sampled message to detect the presence of a known signal. Multiplicative noise described by Poisson and Gaussian statistics is considered. The expressions are extended to include the two-signal discrimination problem. Two-dimensional signal fields in the presence of multiplicative noise are simulated in a computer and processed for optimum signal detection according to the two derived methods. These results are compared to the results of processing based on the assumption of stationary noise statistics. This comparison reveals that modest improvements (20% to 30% reduction in false alarm rate) are obtained when the signal-dependent nature of the noise statistics is considered. The effects of signal-to-noise ratio, signal structure, and changing background level are also investigated. An example of optimum signal discrimination using circles and squares as signals in multiplicative noise is reported. An improvement in the percentage of correctly identified signals is again observed when the proper test statistic is used. Two examples of signal filtering in the presence of signal-dependent noise are included. The first concerns the processing of a real star field to determine the location of weak stars. The second is an illustration of the signal information contained in the noise spectrum of a message recorded on a common photographic film.

HIV-1 has evolved a number of strategies in response to current anti-retroviral drugs and the selection pressure of humoral and cellular immunity. In particular, R5 viral strains that are essential for AIDS pathogenesis are very resistant to neutralization by antibodies. Therefore, the aim of this thesis was to develop synthetic nucleic acid ligands, aptamers, against gp120 of an R5 strain of HIV-1, with a view of using aptamers as novel neutralization molecules and analytical tools to study HIV-1 entry into target cells. The central hypothesis of this thesis was that aptamers by virtue of their small size and slow dissociation rates, compared to antibodies, would easily access and bind occluded gp120 neutralization sites. Using the SELEX protocol and SPR technology, I isolated 2'-Fluoro-pyrimidine-RNA aptamers against HIV-l_Ba-L monomeric gp120. Most of these aptamers not only bound gp120 with high affinities but also neutralized R5 primary isolates in human PBMC by 1,000 to 100,000-fold, truly unprecedented when compared with natural ligands such as antibodies. Some aptamers, like B4, defined a conserved site of gp120 that could not mutate to escape neutralization following stringent selection, in vitro, for breakthrough virus. This was consistent with subsequent findings that B4 aptatope (binding site) overlaps a poorly immunogenic but highly conserved CD4-induced epitope as determined by competition with 17b and 48d mAbs that map to this neutralization epitope on the gp120. This study was thus the first of its kind to describe neutralization of HIV-1 primary isolates by a ligand against the CD4-induced epitope. Most intriguing, although B4 potently neutralized HIV-1_Ba-L infection in PBMC, which is a mixed T cell and macrophage population, it modestly neutralized infection of the same virus in a purified culture of macrophages. These findings are intriguing in that they suggest that aptamers could be used to dissect unique sites on the virus that interact with target cell surface in ways that have not been revealed heretofore, and would help understand better HIV-1 entry pathways, especially in macrophages. Thus neutralizing aptamers such as these could be exploited to provide leads in developing alternative anti-HIV-1 drugs and a deeper understanding of the molecular interactions between the virus and its host cell.

Correct regulation of transcription is essential for maintaining a healthy cellular state. During transcription RNA polymerase II (Pol II) proceeds in a regulated manner through several transitions to ensure appropriate control of synthesis and enable correct processing of the pre-RNA. Shortly after initiation Pol II is caused to pause by the binding of factors, DSIF and NELF. To enable transition of Pol II into the elongation phase CDK9/cyclin T phosphorylates the C-terminal domain (CTD) of Pol II, DSIF and NELF. This phosphorylation releases the paused state and provides an alternative set of post-transcriptional modifications on the CTD to generate a binding platform for elongation, histone modifying and termination factors. CDK9/cyclin T is itself regulated within multicomponent complexes. A small activated complex, containing Brd4, recruits CDK9/cyclin T to active sites of transcription, thereby promoting the elongation of transcription. The role of CDK9/cyclin T in the regulation of transcription has resulted in its validation as a drug target against several disease states including cancer, HIV and cardiac hypertrophy. In this thesis, I present the crystallographic structures of a series of 2-amino-4-heteroaryl-pyrimidine compounds and the roscovitine derivative, (S)-CR8, bound to CDK9/cyclin T and CDK2/cyclin A. In combination with thermal denaturation data and kinetic analysis, these structures have suggested chemical modifications that might be made to increase the CDK9 specificity of these compounds. I have also validated the use of a mutated form of cyclin T for use in the development of CDK9/cyclin T inhibitors. In addition, I present both structural and kinetic analysis of the Brd4-CDK9/cyclin T interaction. I show that C-terminal fragments of Brd4 enhance the in vitro kinase activity of CDK9/cyclin T against the Pol II CTD. Furthermore, I demonstrate that this enhancement may be inhibited by Plk1-mediated phosphorylation of Brd4. Finally, I show that Brd4 binds to a site that spans CDK9 and cyclin T and I propose detailed molecular models of the Brd4-cyclin T interaction.