A Review of the Effectiveness of Foreign Language Enjoyment and Foreign Language Classroom Anxiety on Learners' Engagement and Attainment.

Cognitive factors are not the fundamental determinants of success in language learning. Foreign language attainment depends on both cognitive and affective factors, highlighting the deeper impacts of the former. Some scholars started to investigate affective issues, particularly negative emotions in language learning studies; nevertheless, reducing negative emotions such as anxiety should be accompanied by the development of positive emotions (e.g., well-being, autonomy, and enjoyment). Since then, a great number of researchers have examined the impact of anxiety and enjoyment in foreign language literature, particularly after the introduction of reliable and valid foreign language classroom anxiety (FLCA) and foreign language enjoyment (FLE) scales. So, the present study aims to review contemporary scholarly articles and books in this regard. Findings suggest that there has been a major interest in the evaluation of FLCA and FLE across a variety of dimensions including personality traits, interpersonal characteristics, and classroom conditions. The central issues are summarized into three categories of the relationship between FLCA and FLE, the robustness of respective scales, and the impact of individual and interpersonal factors. Hence, this research attempts to highlight probable gaps and areas for further examinations to help enrich the literature and improve the theoretical knowledge.

Nocardia Infection in Nephrotic Syndrome Patients: Three Case Studies and A Systematic Literature Review.

OBJECTIVE: The multicenter literature review and case studies of 3 patients were undertaken to provide an updated understanding of nocardiosis, an opportunistic bacterial infection affecting immunosuppressed nephrotic syndrome (NS) patients receiving long-term glucocorticoid and immunosuppressant treatment. The results provided clinical and microbiological data to assist physicians in managing nocardiosis patients. METHODS: Three cases between 2017 and 2018 from a single center were reported. Additionally, a systematic review of multicenter cases described in the NCBI PubMed, Web of Science, and Embase in English between January 1, 2001 and May 10, 2021 was conducted. RESULTS: This study described three cases of Nocardia infection in NS patients. The systematic literature review identified 24 cases with sufficient individual patient data. A total of 27 cases extracted from the literature review showed that most patients were > 50 years of age and 70.4% were male. Furthermore, the glucocorticoid or corticosteroid mean dose was 30.9 ± 13.7 mg per day. The average time between hormone therapy and Nocardia infection was 8.5 ± 9.7 months. Pulmonary (85.2%) and skin (44.4%) infections were the most common manifestations in NS patients, with disseminated infections in 77.8% of patients. Nodule/masses and consolidations were the major radiological manifestations. Most patients showed elevated inflammatory biomarkers levels, including white blood cell counts, neutrophils percentage, and C-reactive protein. Twenty-five patients received trimethoprim-sulfamethoxazole monotherapy (18.5%) or trimethoprim-sulfamethoxazole-based multidrug therapy (74.1%), and the remaining two patients (7.4%) received biapenem monotherapy. All patients, except the two who were lost to follow-up, survived without relapse after antibiotic therapy. CONCLUSIONS: Nephrotic syndrome patients are at high risk of Nocardia infection even if receiving low-dose glucocorticoid during the maintenance therapy. The most common manifestations of nocardiosis in NS patients include abnormal lungs revealing nodules and consolidations, skin and subcutaneous abscesses. The NS patients have a high rate of disseminated and cutaneous infections but a low mortality rate. Accurate and prompt microbiological diagnosis is critical for early treatment, besides the combination of appropriate antibiotic therapy and surgical drainage when needed for an improved prognosis.

Systematic study of the functions for the residues around the nucleotide pocket in simian virus 40 AAA+ hexameric helicase.

The high-resolution structural data for simian virus 40 large-T-antigen helicase revealed a set of nine residues bound to ATP/ADP directly or indirectly. The functional role of each of these residues in ATP hydrolysis and also the helicase function of this AAA+ (ATPases associated with various cellular activities) molecular motor are unclear. Here, we report our mutational analysis of each of these residues to examine their functionality in oligomerization, DNA binding, ATP hydrolysis, and double-stranded DNA (dsDNA) unwinding. All mutants were capable of oligomerization in the presence of ATP and could bind single-stranded DNA and dsDNA. ATP hydrolysis was substantially reduced for proteins with mutations of residues making direct contact with the gamma-phosphate of ATP or the apical water molecule. A potentially noncanonical "arginine finger" residue, K418, is critical for ATP hydrolysis and helicase function, suggesting a new type of arginine finger role by a lysine in the stabilization of the transition state during ATP hydrolysis. Interestingly, our mutational data suggest that the positive- and negative-charge interactions in the uniquely observed residue pairs, R498/D499 and R540/D502, in large-T-antigen helicase are critically involved in the transfer of energy of ATP binding/hydrolysis to DNA unwinding.

Identification of amino acids important for the biochemical activity of Methanothermobacter thermautotrophicus MCM.

Methanothermobacter thermautotrophicus minichromosomal maintenance protein (mtMCM) is a 75 kDa protein that self-assembles into a double hexamer structure. The double hexamer formed by the N-terminal region of mtMCM has a highly charged (overwhelmingly net positive) inner channel. Here we investigate the effects of point mutations of some of these charged residues on the biological activities of mtMCM. Although all of the mutants were similar to the wild type in protein folding and complex assembly, we found that mutations impaired helicase activity. The study of the DNA binding and ATPase activities of these mutants revealed that the impairment of the helicase activity was highly correlated with a decrease in DNA binding, providing evidence consistent with the role of these charged residues of the inner channel in interactions with DNA.

Crystal structure of the C-terminal domain of splicing factor Prp8 carrying retinitis pigmentosa mutants.

Prp8 is a critical pre-mRNA splicing factor. Prp8 is proposed to help form and stabilize the spliceosome catalytic core and to be an important regulator of spliceosome activation. Mutations in human Prp8 (hPrp8) cause a severe form of the genetic disorder retinitis pigmentosa, RP13. Understanding the molecular mechanism of Prp8's function in pre-mRNA splicing and RP13 has been hindered by its large size (over 2000 amino acids) and remarkably low-sequence similarity with other proteins. Here we present the crystal structure of the C-terminal domain (the last 273 residues) of Caenorhabditis elegans Prp8 (cPrp8). The core of the C-terminal domain is an alpha/beta structure that forms the MPN (Mpr1, Pad1 N-terminal) fold but without Zn(2+) coordination. We propose that the C-terminal domain is a protein interaction domain instead of a Zn(2+)-dependent metalloenzyme as proposed for some MPN proteins. Mapping of RP13 mutants on the Prp8 structure suggests that these residues constitute a binding surface between Prp8 and other partner(s), and the disruption of this interaction provides a plausible molecular mechanism for RP13.

Crystal structure of UAP56, a DExD/H-box protein involved in pre-mRNA splicing and mRNA export.

UAP56 is an essential eukaryotic pre-mRNA splicing factor and mRNA export factor. The mechanisms of its functions are not well understood. We determined the crystal structures of the N- and C-terminal domains of human UAP56 (comprising 90% of the full-length UAP56) at 1.9 A resolution. The two domains each have a RecA-like fold and are connected by a flexible linker. The overall fold of each domain is highly similar to the corresponding domains of eIF4A (a prototypic DExD/H-box protein), with differences at the loops and termini. This structural similarity suggests that UAP56 is likely to possess ATPase and helicase activity similar to eIF4A. The NTP binding pocket of UAP56 is occupied by a citrate ion, mimicking the phosphates of NTP and retaining the P loop in an open conformation. The crystal structure of the N-terminal domain of UAP56 also reveals a dimer interface that is potentially important for UAP56's function.

Diphtheria toxin-epidermal growth factor fusion protein DAB389EGF for the treatment of bladder cancer.

PURPOSE: The novel fusion protein, DAB(389)EGF, is composed of both the catalytic and the translocation domains of diphtheria toxin that are fused to the human EGF, providing a targeting and a toxicity component. We tested DAB(389)EGF for antitumor activity in both in vitro and in vivo urinary bladder cancer models. EXPERIMENTAL DESIGN: Human bladder cancer lines were treated with DAB(389)EGF and assessed for growth inhibition and clonogenic suppression. Using 6- to 8-week-old female athymic nude mice implanted orthotopically with HTB9 cells, DAB(389)EGF was administered intravesically twice weekly for 2 weeks. The response of the luciferase-expressing HTB9 cells was monitored via bioluminescence as the primary endpoint. RESULTS: Treatment response with DAB(389)EGF was specific and robust, with an IC(50) ranging from 0.5 to 15 ng/mL in eight tested bladder cancer cell lines, but greater than 50 ng/mL in the EGF receptor (EGFR)-negative H520 control cell line. Simulating short-duration intravesical therapy used clinically, a 2-hour treatment exposure of DAB(389)EGF (10 ng/mL) produced clonogenic suppression in three selected bladder cancer cell lines. In vivo, luciferase activity was suppressed in five of six mice treated with DAB(389)EGF [70 µL (1 ng/µL) per mouse], as compared with only one of six mice treated with a control diphtheria toxin (DT) fusion protein. Histologic assessment of tumor clearance correlated with the bioluminescent changes observed with DAB(389)EGF treatment. Immunocompetent mice treated with intravesical DAB(389)EGF did not show any nonspecific systemic toxicity. CONCLUSIONS: The intravesical delivery of targeted toxin fusion proteins is a novel treatment approach for non-muscle-invasive urinary bladder cancer. With appropriate targeting, the treatments are effective and well-tolerated in vivo.

Role of phosphatidylinositol-3-kinase pathway in head and neck squamous cell carcinoma.

Activation of the phosphatidylinositol-3-kinase (PI3K) pathway is one of the most frequently observed molecular alterations in many human malignancies, including head and neck squamous cell carcinoma (HNSCC). A growing body of evidence demonstrates the prime importance of the PI3K pathway at each stage of tumorigenesis, that is, tumor initiation, progression, recurrence, and metastasis. Expectedly, targeting the PI3K pathway yields some promising results in both preclinical studies and clinical trials for certain cancer patients. However, there are still many questions that need to be answered, given the complexity of this pathway and the existence of its multiple feedback loops and interactions with other signaling pathways. In this paper, we will summarize recent advances in the understanding of the PI3K pathway role in human malignancies, with an emphasis on HNSCC, and discuss the clinical applications and future direction of this field.

Quantitative, noninvasive imaging of radiation-induced DNA double-strand breaks in vivo.

DNA double-strand breaks (DSB) are a major form of DNA damage and a key mechanism through which radiotherapy and some chemotherapeutic agents kill cancer cells. Despite its importance, measuring DNA DSBs is still a tedious task that is normally carried out by gel electrophoresis or immunofluorescence staining. Here, we report a novel approach to image and quantify DSBs in live mammalian cells through bifragment luciferase reconstitution. N- and C-terminal fragments of firefly luciferase genes were fused with H2AX and MDC1 genes, respectively. Our strategy was based on the established fact that at the sites of DSBs, H2AX protein is phosphoryated and physically associates with the MDC1 protein, thus bringing together N- and C-luciferase fragments and reconstituting luciferase activity. Our strategy allowed serial, noninvasive quantification of DSBs in cells irradiated with X-rays and (56)Fe ions. Furthermore, it allowed for the evaluation of DSBs noninvasively in vivo in irradiated tumors over 2 weeks. Surprisingly, we detected a second wave of DSB induction in irradiated tumor cells days after radiation exposure in addition to the initial rapid induction of DSBs. We conclude that our new split-luciferase-based method for imaging γ-H2AX-MDC1 interaction is a powerful new tool to study DSB repair kinetics in vivo with considerable advantage for experiments requiring observations over an extended period of time.

Caspase 3-mediated stimulation of tumor cell repopulation during cancer radiotherapy.

In cancer treatment, apoptosis is a well-recognized cell death mechanism through which cytotoxic agents kill tumor cells. Here we report that dying tumor cells use the apoptotic process to generate potent growth-stimulating signals to stimulate the repopulation of tumors undergoing radiotherapy. Furthermore, activated caspase 3, a key executioner in apoptosis, is involved in the growth stimulation. One downstream effector that caspase 3 regulates is prostaglandin E(2) (PGE(2)), which can potently stimulate growth of surviving tumor cells. Deficiency of caspase 3 either in tumor cells or in tumor stroma caused substantial tumor sensitivity to radiotherapy in xenograft or mouse tumors. In human subjects with cancer, higher amounts of activated caspase 3 in tumor tissues are correlated with markedly increased rate of recurrence and death. We propose the existence of a cell death-induced tumor repopulation pathway in which caspase 3 has a major role.

Apoptotic caspases regulate induction of iPSCs from human fibroblasts.

The molecular mechanisms involved in the derivation of induced pluripotent stem cells (iPSCs) from differentiated cells are poorly understood. Here we report that caspases 3 and 8, two proteases associated with apoptotic cell death, play critical roles in induction of iPSCs from human fibroblasts. Activation of caspases 3 and 8 occurs soon after transduction of iPSC-inducing transcription factors. Oct-4, a key iPSC transcription factor, is responsible for the activation. Inhibition of caspase 3 or 8 in human fibroblast cells partially or completely (respectively) prevents the induction of iPSCs. Furthermore, retinoblastoma susceptibility (Rb) protein appears to be one of the factors that act downstream of the caspases. We propose that caspases are key facilitators of nuclear reprogramming in iPSC induction.

The Hsp90 inhibitor radicicol interacts with the ATP-binding pocket of bacterial sensor kinase PhoQ.

Sensor kinases in the bacterial two-component system share a unique ATP-binding Bergerat fold with the GHL (gyrase, Hsp90, and MutL) family of proteins. We demonstrated that selected GHL inhibitors bind to the catalytic domain of sensor kinase PhoQ (PhoQcat) using NMR chemical shift perturbation experiments. Using crystallographic approaches, we show that radicicol (an Hsp90 inhibitor) binds and interacts specifically with residues in the ATP-binding pocket of PhoQ. The interaction between radicicol and PhoQcat demonstrates significant similarities as well as differences compared to AMPPNP (a non-hydrolyzable ATP analog) bound to PhoQcat and radicicol bound to Hsp90. Our results suggest that GHL inhibitors may be useful lead compounds for developing sensor kinase inhibitors.

Distinct activities of the DExD/H-box splicing factor hUAP56 facilitate stepwise assembly of the spliceosome.

The essential splicing factor human UAP56 (hUAP56) is a DExD/H-box protein known to promote prespliceosome assembly. Here, using a series of hUAP56 mutants that are defective for ATP-binding, ATP hydrolysis, or dsRNA unwindase/helicase activity, we assess the relative contributions of these biochemical functions to pre-mRNA splicing. We show that prespliceosome assembly requires hUAP56's ATP-binding and ATPase activities, which, unexpectedly, are required for hUAP56 to interact with U2AF(65) and be recruited into splicing complexes. Surprisingly, we find that hUAP56 is also required for mature spliceosome assembly, which requires, in addition to the ATP-binding and ATPase activities, hUAP56's dsRNA unwindase/helicase activity. We demonstrate that hUAP56 directly contacts U4 and U6 snRNAs and can promote unwinding of the U4/U6 duplex, and that both these activities are dependent on U2AF(65). Our results indicate that hUAP56 first interacts with U2AF(65) in an ATP-dependent manner, and subsequently with U4/U6 snRNAs to facilitate stepwise assembly of the spliceosome.

Biochemical characterization of the ATPase and helicase activity of UAP56, an essential pre-mRNA splicing and mRNA export factor.

DEXD/H-box protein UAP56 is an essential pre-mRNA splicing factor required for the first ATP-dependent spliceosome assembly step. UAP56 is also essential for the export of the majority of mRNAs from the nucleus to the cytoplasm. We performed biochemical characterization of UAP56's ATPase and helicase activity, which is important for further understanding the role of these activities in UAP56's function. We showed that UAP56 is an RNA-stimulated ATPase that can only hydrolyze ATP. We demonstrated that UAP56 is an ATP-dependent RNA helicase that can unwind substrates with 5' or 3' overhangs or blunt ends in vitro. We showed that U2AF(65) and Aly, two proteins known to interact with UAP56, do not influence UAP56's ATPase or helicase activity. We also demonstrated that several mutants in the conserved helicase motifs I, II, and III abolish UAP56's ATPase and/or helicase activity, providing tools for future investigation of the role of UAP56's ATPase and helicase activity in spliceosome assembly and mRNA export.

The roles of the residues on the channel beta-hairpin and loop structures of simian virus 40 hexameric helicase.

Simian virus 40 large tumor antigen is required for DNA unwinding during viral replication. The helicase-active form of large tumor antigen is a ring-shaped hexamer/double hexamer, which has a positively charged hexameric channel for interacting with DNA. On the hexameric channel surface are six beta-hairpin structures and loops, emanating from each of the six subunits. At the tips of the beta-hairpin and the loop structures are two ring-shaped residues, H513 and F459, respectively. Additionally, two positively charged residues, K512 and K516, are near the tip of the beta-hairpin. The positions of these ring-shaped and positively charged residues suggest that they may play a role in binding DNA for helicase function. To understand the roles of these residues in helicase function, we obtained a set of mutants and examined various activities, including oligomerization, ATPase, DNA binding, and helicase activities. We found that substitution of these residues by Ala abolished helicase activity. Extensive mutagenesis showed that substitutions by ring-shaped residues (W and Y) at position F459 and by residues with hydrophobic or long aliphatic side chains (W, Y, F, L, M, and R) at position H513 supported helicase activity. Our study demonstrated that the four residues (F459, H513, K512, and K516) play a critical role in interacting with DNA for helicase function. The results suggest a possible mechanism to explain how these residues, as well as the beta-hairpin and the loop structures on which the residues reside, participate in binding and translocating DNA for origin melting and unwinding.

Double hexamer disruption and biochemical activities of Methanobacterium thermoautotrophicum MCM.

Methanobacterium thermoautotrophicum MCM (mtMCM) is a helicase required for DNA replication. Previous electron microscopy studies have shown mtMCM in several oligomeric forms. However, biochemical studies suggest that mtMCM is a dodecamer, likely a double hexamer (dHex). The crystal structure of the N-terminal fragment of mtMCM reveals a stable dHex architecture. To further confirm that the dHex is not an artifact of crystal packing of two hexamers, we investigated the relevance of the dHex by disrupting the hexamer-hexamer interactions seen in the crystal structure via site-directed mutagenesis and examining various biochemical activities of the mutants in vitro. Using a combination of biochemical and structural assays, we demonstrated that changing arginine to alanine at amino acid position 161 or the insertion of a six-aminoacid peptide at the hexamer-hexamer interface disrupted dHex formation and produced stable single hexamers (sHex). Furthermore, we showed that the sHex mutants retained wild-type level of ATPase and DNA binding activities but had decreased helicase activity when compared with the wild type dHex protein. These biochemical properties of mtMCM are reminiscent of those of SV40 large T antigen, suggesting that the dHex form of mtMCM may be the active helicase for DNA unwinding during the bidirectional DNA replication.