ABC Component Research Articles

Importance of twitching and surface-associated motility in the virulence of Acinetobacter baumannii

ABSTRACT Acinetobacter baumannii is a pathogen of increasing clinical importance worldwide, especially given its ability to readily acquire resistance determinants. Motile strains of this bacterium can move by either or both of two types of motility: (i) twitching, driven by type IV pili, and (ii) surface-associated motility, an appendage-independent form of movement. A. baumannii strain MAR002 possesses both twitching and surface-associated motility. In this study, we isolated spontaneous rifampin-resistant mutants of strain MAR002 in which point mutations in the rpoB gene were identified that resulted in an altered motility pattern. Transcriptomic analysis of mutants lacking twitching, surface-associated motility, or both led to the identification of deregulated genes within each motility phenotype, based on their level of expression and their biological function. Investigations of the corresponding knockout mutants revealed several genes involved in the motility of A. baumannii strain MAR002, including two involved in twitching (encoding a minor pilin subunit and an RND [resistance nodulation division] component), one in surface-associated motility (encoding an amino acid permease), and eight in both (encoding RND and ABC components, the energy transducer TonB, the porin OprD, the T6SS component TagF, an IclR transcriptional regulator, a PQQ-dependent sugar dehydrogenase, and a putative pectate lyase). Virulence assays showed the reduced pathogenicity of mutants with impairments in both types of motility or in surface-associated motility alone. By contrast, the virulence of twitching-affected mutants was not affected. These results shed light on the key role of surface-associated motility and the limited role of twitching in the pathogenicity of A. baumannii.

A distributed API for coordinating AbC programs

Collective adaptive systems exhibit a particular notion of interaction where environmental conditions largely influence interactions. Previously, we proposed a calculus, named AbC, to model and reason about CAS. The calculus proved to be effective by naturally modelling essential CAS features. However, the question on the tradeoff between its expressiveness and its efficiency, when implemented to program CAS applications, is to be answered. In this article, we propose an efficient and distributed coordination infrastructure for AbC. We prove its correctness, and we evaluate its performance. The main novelty of our approach is that AbC components are infrastructure agnostic. Thus the code of a component does not specify how messages are routed in the infrastructure but rather what properties a target component must satisfy. We also developed a Go API, named mathcal {G}{} textit{o}mathcal {A}{} textit{t}, and an Eclipse plugin to program in a high-level syntax which can be automatically used to generate matching Go code. We showcase our development through a non-trivial case study.

Visualization of Primary Particles in a Tablet Based on Raman Crystal Orientation Mapping

Objective: The morphology of the primary particles in the active pharmaceutical ingredient (API) is one of the most important determinants for formulation function. However, it has not been possible to visualize primary particles in a tablet using various imaging methods, including spectroscopic mappings, because these particles usually exist as aggregated clusters in tablets. We revealed that the Raman spectrum of crystalline particles is determined depending upon the angle between the crystallographic axis and the polarization direction of the excitation laser. In this paper, we report a method to visualize primary particles within the aggregated cluster based on the Raman spectral change on the boundary of primary particles. Method: Metformin hydrochloride was chosen as a model API for this study. The crystal structure of metformin hydrochloride was solved using X-ray crystal structure analysis. The Raman spectra of metformin hydrochloride crystal along the xyz axes were recorded and resolved into components along the abc axes. Using the abc components, Raman mapping of metformin hydrochloride in tablets was performed to visualize the crystal orientation at each data point. Results: Metformin hydrochloride crystals recrystallized from water/ethanol formed a primitive monoclinic cell. Datasets of five distinct peak areas from the metformin hydrochloride Raman spectrum were used for analyses. Raman crystal orientation mapping (RCOM) from the tablet cross-section provided an image of primary particles within the aggregation cluster of metformin hydrochloride in the tablet. Conclusion: Based on the RCOM, we developed a visualization method for primary API particles in tablets. Because the morphology of primary particles is the key factor of formulation function, this method would contribute to better formulation development and quality control.

The ABCs of Trait Anger, Psychological Distress, and Disease Severity in HIV.

Trait anger consists of affective, behavioral, and cognitive (ABC) dimensions and may increase vulnerability for interpersonal conflict, diminished social support, and greater psychological distress. The concurrent influence of anger and psychosocial dysfunction on Human Immunodeficiency Virus (HIV) disease severity is unknown. The purpose of this study was to examine plausible psychosocial avenues (e.g., coping, social support, psychological distress), whereby trait anger may indirectly influence HIV disease status. Three hundred seventy-seven HIV seropositive adults, aged 18-55 years (58% AIDS-defined), completed a battery of psychosocial surveys and provided a fasting blood sample for HIV-1 viral load and T lymphocyte count assay. A second-order factor model confirmed higher levels of the multidimensional anger trait, which was directly associated with elevated psychological distress and avoidant coping (p<.001) and indirectly associated with greater HIV disease severity (p<.01) (comparative fit index (CFI)=0.90, root-mean-square error of approximation (RMSEA)=0.06, standardized root-mean-square residual (SRMR)=0.06). The model supports a role for the ABC components of anger, which may negatively influence immune function through various psychosocial mechanisms; however, longitudinal study is needed to elucidate these effects.

Coping with anxiety and rebuilding identity: A psychosynthesis approach to culture shock

As the number of international students continues to increase worldwide, their experience of culture shock has been well-researched. Missing, however, from the culture shock literature is the perspective of psychosynthesis psychology and its methodology to deal with the affective, behavioral, and cognitive (ABC) aspects of shock and adaptation. This article illustrates two psychosynthesis techniques that student sojourners found helpful in their acculturation process. Firstly, the self-identification exercise eased anxiety, an affective aspect of culture shock. Secondly, the subpersonality model aided students in their ability to integrate a new social identity, the cornerstone of the cognitive aspect. With a new integrated identity, students changed their behavior (the second ABC component) and new creative energies were released. These qualitative findings are supported by the testimonies of nine international student sojourners in the Netherlands who received psychosynthesis counseling. In addition, a case study demonstrates subpersonality integration and its role in helping students to come into relationship with themselves as well as others. The self-identification exercise and subpersonality model are not only effective tools for aiding sojourners in their adaptation to a host country, but viable methodologies for anyone searching to synthesize a new personal and social identity.

Coexistent squamous cell carcinoma and adenoid basal carcinoma in the uterine cervix and infection with human papillomavirus (HPV 31)

ObjectiveAdenoid basal carcinoma (ABC) is an uncommon neoplasm of the uterine cervix. ABC can be accompanied by carcinoma in situ or invasive carcinoma. Most cases are discovered accidentally during radical hysterectomy. ABC is associated with a high risk of human papillomavirus infection (HPV), most often HPV 16 infection. Case reportWe present a rare case of an 86-year-old Taiwanese married woman who suffered from bloody vaginal discharge and occasional lower abdominal pain and received cervical biopsy. The pathological report revealed squamous cell carcinoma (SCC) of the uterine cervix. After radical hysterectomy, bilateral salpingo-oophorectomy, and bilateral pelvic and para-aortic lymph node dissection, the final pathological report revealed SCC coexisting with ABC, and both of the components were infected by HPV 31. After receiving radiotherapy, she maintained outpatient department follow-up. ConclusionA literature review revealed that this was a rare case of combined ABC–SCC associated with HPV 31 infection. In this case, the ABC component did not affect the tumor stage because it was confined to the cervix. However, we must avoid overestimating the clinical stage because the ABC component is thought to be a benign lesion.

Morphologies and phase diagrams of ABC star triblock copolymers confined in a spherical cavity

The morphologies and phase diagrams exhibited by symmetric ABC star triblock copolymer nanoparticles are investigated by using the real-space self-consistent field theory. A variety of three-dimensional morphologies, such as spherically concentric lamellae and ring-like structures, are identified in the triangular phase diagrams for the polymeric nanoparticles, depending on the volume fractions of the components and the interaction between the polymers and the confining spherical surface. We first study a number of examples where the confining radius and degree of interactions between the polymer and the spherical surface are fixed. A neutral surface that has no energetic preference on any ABC component induces ring-like structures in axisymmetry in an orbicular region of the phase diagram, which surrounds the central region where distorted cylinder phases are stable; a spherical surface that attracts one of the three polymer components induces distorted cylinders into the ring-like structures in a central region of the phase diagram; a spherical surface that repels one of the components stabilizes a lamella-like structure in spherical symmetry in a large region of the phase diagrams. We then focus on an example of polygonal tiling morphologies to study the effects due to variations of the spherical radius and the degree of interactions between the polymer and the spherical surface. The results show that the degree of interactions can obviously influence the formation of morphologies but the spherical radius only affects the polygonal tiling morphologies through slightly adjusting their natural arrangement in the neutral surface case.

Nonlinear Estimation of Synchronous Machine Parameters Using Operating Data

This paper presents a nonlinear parameter estimator for synchronous machines based on the unscented Kalman filter. The proposed methodology uses voltages and current signals recorded from the stator and the field winding to update the parameters of the classical model of the synchronous machine for stability studies. The methodology can be applied without interrupting the normal operation of the generator. Park's Transformation is included in the estimation process to relate the stator measurements (in abc components) to the nonlinear voltage equations in the qd0 reference frame. The proposed robust methodology has been validated using real and simulated data to estimate the model parameters of a 483-MVA round rotor machine.

The Extreme C Terminus of the ABC Protein DrrA Contains Unique Motifs Involved in Function and Assembly of the DrrAB Complex

Two novel regulatory motifs, LDEVFL and C-terminal regulatory Glu (E)-rich motif (CREEM), are identified in the extreme C terminus of the ABC protein DrrA, which is involved in direct interaction with the N-terminal cytoplasmic tail of the membrane protein DrrB and in homodimerization of DrrA. Disulfide cross-linking analysis showed that the CREEM and the region immediately upstream of CREEM participate directly in forming an interaction interface with the N terminus of DrrB. A series of mutations created in the LDEVFL and CREEM motifs drastically affected overall function of the DrrAB transporter. Mutations in the LDEVFL motif also significantly impaired interaction between the C terminus of DrrA and the N terminus of DrrB as well as the ability of DrrA and DrrB to co-purify, therefore suggesting that the LDEVFL motif regulates CREEM-mediated interaction between DrrA and DrrB and plays a key role in biogenesis of the DrrAB complex. Modeling analysis indicated that the LDEVFL motif is critical for conformational integrity of the C-terminal domain of DrrA and confirmed that the C terminus of DrrA forms an independent domain. This is the first report which describes the presence of an assembly domain in an ABC protein and uncovers a novel mechanism whereby the ABC component facilitates the assembly of the membrane component. Homology sequence comparisons showed the presence of the LDEVFL and CREEM motifs in close prokaryotic and eukaryotic homologs of DrrA, suggesting that these motifs may play a similar role in other homologous drug and lipid export systems.

The ABCs of HIV Prevention in Men

To elucidate associations between beliefs in abstinence, fidelity, and condom use (the "ABCs" of preventing HIV and other sexually transmitted infections) and associated self-reported risk behaviors among Kenyan men. We assessed associations of beliefs in the ABCs with sociodemographic characteristics and sexual risk behaviors in a respondent-driven sample of 500 men in Nairobi. Younger age, single marital status, and higher education were associated with beliefs in abstinence and condom use as "best" prevention methods; and older age and marriage were associated with belief in fidelity. Many of these and other associations persisted in multivariate models. Men citing abstinence or fidelity belief less often reported sex with a female sex worker (FSW) ever or recent concurrent partnerships less often. Belief in fidelity was negatively associated with reported use of condoms ever. Belief in condom use to prevent HIV was most common among those having recent concurrent partnerships. Beliefs in abstinence, fidelity ("being faithful"), or condom use were associated, in plausible directions, with life stages and other demographic factors and with corresponding risk and preventive behaviors. Context-specific and selective educational promotion of individual ABC components rather than comprehensive education from an early age in a wide repertoire of prevention strategies ignores the evolution of sexual behaviors and the relative utility of different approaches throughout the life course.

Uganda's HIV/AIDS Epidemic: Guest Editorial

Uganda's HIV/AIDS Epidemic: Guest Editorial

The Aes Protein Directly Controls the Activity of MalT, the Central Transcriptional Activator of the Escherichia coliMaltose Regulon

MalT, the transcriptional activator of the maltose regulon from Escherichia coli, is the prototype of a new family of transcription factors. Its activity is controlled by multiple regulatory signals. ATP and maltotriose (the inducer) are two effectors of the activator that positively control its multimerization, a critical step in promoter binding. In addition, MalK, the ABC component of the maltodextrin transport system, and the two enzymes MalY and Aes down-regulate MalT activity in vivo. By using a biochemical approach, we demonstrate here that (i) Aes controls MalT activity through direct protein-protein interaction, (ii) Aes competes with maltotriose for MalT binding, (iii) ATP and ADP differentially affect the competition between Aes and the inducer, and (iv) part, if not all, of the Aes binding site is located in DT1, the N-terminal domain of the activator, which also contains the ATP binding site. All of these characteristics point toward an identical mode of action for MalY and Aes. However, we have identified an amino acid substitution in MalT that suppresses MalT inhibition by Aes without interfering with its inhibition by MalY, suggesting that the binding sites of the two inhibitory proteins do not coincide. The differential effects of ATP and ADP on the competition between the inducer and Aes (or MalY) suggest that the ATPase activity displayed by MalT plays a role in the negative control of its activity.

Parent and Teacher Ratings of Challenging Behaviour in Young Children with Developmental Disabilities

Parent and teacher ratings on the Aberrant Behaviour Checklist were compared to determine its reliability for assessing challenging behaviour in young children with developmental disabilities. Twenty‐four boys and eight girls aged 20 to 72 months (mean age = 51 months) were assessed independently by a parent and teacher using the Aberrant Behaviour Checklist. There were no significant differences between parent and teacher ratings on any of the five subscales. Spearman's rank correlation coefficients between parent and teacher ratings for each of the five subscales ranged from 0.50 to 0.83 (mean = 0.62). All correlations were significant (p &lt; 0.01). Confirmatory factor analyses generated item loadings consistent with the original factor structure of the ABC and similar component loadings for parents and teachers. These results suggest the Aberrant Behaviour Checklist can provide a reliable assessment of challenging behaviour when used by parents and teachers of young children with developmental disabilities.

Chromospherically active stars. 12: ADS 11060 C: A double lined K dwarf binary in a quintuple system

ADS 11060 C is a double lined spectroscopic binary with a period of 25.7631 days and an eccentricity of 0.565. Spectral types of the two stars are estimated as K7 V and MO V with a magnitude difference of about 0.55 mag in V. The stars appear to be somewhat metal rich with respect to the Sun. Despite the relatively large masses of 0.53 and 0.51 solar mass, our photometric observations find no evidence for eclipses and we estimate an inclination of 77 deg plus or minus 11 deg. ADS 11060 C is, however, photometrically variable with a period of 9 plus or minus 1 day and an amplitude of 0.05 mag in V. Thus, it is a newly identified BY Draconis variable. The center-of-mass velocity of ADS 11060 C and an estimated parallax of 0.030 sec support its physical association with ADS 11060 AB, making this a quintuple system. The projected separation of the AB-C system is nearly 1200 AU. Although the log lithium abundances of the two components of ADS 11060 C are only upper limits, less than or equal to -0.14, lithium abundances of the AB-C components appear to be consistent with those of similar stars in the alpha Persei and Pleiades clusters, suggesting an age of about 70 Myr for ADS 11060 AB-C. The system is a possible member of the Pleiades moving group. Listed as an optical counterpart to a source in the ROSAT Wide Field Camera extreme-ultraviolet bright source catalog, both ADS 11060 AB and C may contribute to the observed flux.