Impact of Molecular Electrostatics on Field-Coupled Nanocomputing and Quantum-Dot Cellular Automata Circuits

The molecular Field-Coupled Nanocomputing (FCN) is a promising implementation of the Quantum-dot Cellular Automata (QCA) paradigm for future low-power digital electronics. However, most of the literature assumes all the QCA devices as possible molecular FCN devices, ignoring the molecular physics. Indeed, the electrostatic molecular characteristics play a relevant role in the interaction and consequently influence the functioning of the circuits. In this work, by considering three reference molecular species, namely neutral, oxidized, and zwitterionic, we analyze the fundamental devices, aiming to clarify how molecule physics impacts architectural behavior. We thus examine through energy analysis the fundamental cell-to-cell interactions involved in the layouts. Additionally, we simulate a set of circuits using two available simulators: SCERPA and QCADesigner. In fact, ignoring the molecular characteristics and assuming the molecules copying the QCA behavior lead to controversial molecular circuit proposals. This work demonstrates the importance of considering the molecular type during the design process, thus declaring the simulators working scope and facilitating the assessment of molecular FCN as a possible candidate for future digital electronics.

Prevalence, Genetic Structure, and Antifungal Susceptibility of the Cryptococcus neoformans/C. gattii Species Complex Strains Collected from the Arboreal Niche in Poland

Fungi belonging to the Cryptococcus neoformans/C. gattii species complex (CNGSC) are etiological agents of serious and not infrequently fatal infections in both humans and animals. Trees are the main ecological niche and source of potential exposition concerning these pathogens. With regard to epidemiology of cryptococcosis, various surveys were performed worldwide, enabling the establishment of a map of distribution and genetic structure of the arboreal population of the CNGSC. However, there are regions, among them Central and Eastern Europe, in which the data are lacking. The present study shows the results of such an environmental study performed in Wrocław, Poland. The CNGSC strains were detected in 2.2% of the tested trees belonging to four genera. The obtained pathogen population consisted exclusively of C. neoformans, represented by both the major molecular type VNI and VNIV. Within the tested group of isolates, resistance to commonly used antimycotics was not found, except for 5-fluorocytosine, in which about 5% of the strains were classified as a non-wild type.

Equal-gain combining with interference mitigation for molecular type hopping assisted molecular shift keying systems

In multiple access molecular diffusive communications, many nano-machines exchange information and fuse data through a common Diffusive Molecular Communication (DMC) channel. Hence, there is Multiple-Access Interference (MAI), which should be sufficiently mitigated so as to achieve reliable communications. In this paper, we propose a novel low-complexity detection scheme, namely Equal-Gain Combining with Interference Mitigation (EGC-IM), for signal detection in the Molecular Type Hopping assisted Molecular Shift Keying (MTH-MoSK) DMC systems. By removing a number of entries from each row of the detection matrix formed during detection, the EGC-IM scheme shows its potential to significantly mitigate MAI and hence, outperform the conventional EGC scheme. Furthermore, the EGC-IM scheme has lower complexity than the conventional EGC scheme and therefore, it is beneficial for practical implementation.

Emergence of tigecycline-resistant Klebsiella pneumoniae ST11 clone in patients without exposure to tigecycline

Introduction: Tigecycline is a unique class of semi-synthetic glycylcyclines developed to treat infections caused by multidrug-resistant Klebsiella pneumoniae. In the past decades, eight tigecycline-resistant Acinetobacter baumannii isolates have been identified in Tehran and no Klebsiella pneumoniae has been reported. Methodology: To elucidate the mechanism of K. pneumoniae efflux pump-mediated resistance, the expression of efflux pump genes (oqxA, oqxB, acrA, acrB, tolC) and regulators (acrR, ramA, marA, soxS, rarA, rob) was investigated by real-time RT-PCR. Multilocus sequence typing (MLST) of tigecycline-resistant strains was also performed. Results: Compared to the tigecycline sensitive strain K32 (negative control), all resistant strains showed higher expression levels of efflux genes and regulatory factors. Three tigecycline-resistant strains (K53, K67, K79) showed higher levels of rarA expression (38.1-fold, 41-fold and 24-fold, respectively) and oqxB pump gene (48.2-fold, 60-fold and 58-fold, respectively). The increased expression of acrB was associated with the expression of ramA. However, to the best of our knowledge, studies on the mechanisms of resistance of K. pneumoniae strains to tigecycline are limited, especially in developing countries such as Iran. Conclusions: In the present study, we found that both AcrAB-TolC and OqxAB efflux pumps may play an important role in tigecycline resistance in K. pneumoniae isolates. Finally, the emergence of ST11 molecular type of resistant isolates should be monitored in hospitals to identify factors leading to tigecycline resistance.

Cryptococcus neoformans VNII as the Main Cause of Cryptococcosis in Domestic Cats from Rio de Janeiro, Brazil

Cryptococcosis is a systemic fungal disease acquired from contaminated environments with propagules of the basidiomycetous yeasts of the Cryptococcus neoformans and C. gattii species complexes. The C. neoformans species complex classically comprises four major molecular types (VNI, VNII, VNIII, and VNIV), and the C. gattii species complex comprises another four (VGI, VGII, VGIII, and VGIV) and the newly identified molecular type VGV. These major molecular types differ in their epidemiological and ecological features, clinical presentations, and therapeutic outcomes. Generally, the most common isolated types are VNI, VGI, and VGII. The epidemiological profile of cryptococcosis in domestic cats is poorly studied and cats can be the sentinels for human infections. Therefore, the present study aimed to determine the molecular characterization of Cryptococcus spp. isolated from domestic cats and their dwellings in the metropolitan area of Rio de Janeiro, Brazil. A total of 36 Cryptococcus spp. strains, both clinical and environmental, from 19 cats were subtyped using multilocus sequence typing (MLST). The ploidy was identified using flow cytometry and the mating type was determined through amplification with specific pheromone primers. All strains were mating type alpha and 6/36 were diploid (all VNII). Most isolates (63.88%) were identified as VNII, a rare molecular type, leading to the consideration that this genotype is more likely related to skin lesions, since there was a high percentage (68.75%) of cats with skin lesions, which is also considered rare. Further studies regarding the molecular epidemiology of cryptococcosis in felines are still needed to clarify the reason for the large proportion of the rare molecular type VNII causing infections in cats.

Multi-locus sequence typing reveals genotypic similarity in Nigerian Cryptococcus neoformans AFLP1/VNI of environmental and clinical origin

Introduction Pigeon droppings are among the major environmental sources of Cryptococcus neoformans AFLP1/VNI, from where the organism infects susceptible humans and animals resulting in cryptococcosis. Until now, C. neoformans AFLP1B/VNII was the only molecular type reported in Nigeria. Effective clinical treatment of this infection has occasionally been stymied by the emergence of antifungal non-susceptible, and resistant strains of C. neoformans AFLP1/VNI. Hypothesis/Gap Statement Pigeon droppings harbour C. neoformans and HIV/AIDS patients are among the susceptible population to develop cryptococcal infection. Epidemiological data on cryptococcal prevalence is limited in Nigeria. Aim To investigate the environmental prevalence of C. neoformans in South-eastern Nigeria and compare the isolates with other lineages by using molecular and microbiological tools. Methodology A total of 500 pigeon droppings and 300 blood samples of HIV/AIDS patients were collected, respectively, from five market squares and three tertiary healthcare centres within the Nsukka area of South-eastern Nigeria. The antifungal susceptibility of the C. neoformans isolates to amphotericin B, fluconazole, 5-fluorocytosine, itraconazole, voriconazole, posaconazole, and isavuconazole was investigated based on the CLSI M27-A3 protocol. Yeasts were identified by MALDI-TOF MS, thereafter Cryptococcus MLST was performed according to the International Society for Human and Animal Mycology (ISHAM) consensus scheme. Results C. neoformans was recovered from 6 (1.2 %) pigeon droppings and 6 (2 %) blood cultures of HIV/AIDS patients. Molecular analyses indicated that all cryptococcal isolates belong to serotype A and the AFLP1/VNI molecular type with sequence type (ST)32. Infection with C. neoformans was independent of sex and age of the patients investigated. All C. neoformans isolates were susceptible to the seven antifungal agents. Conclusion This is the first report on the prevalence of C. neoformans AFLP1/VNI (ST32) in environmental and clinical samples from Nigeria. The antifungal susceptibility indicates that antifungal resistance by C. neoformans is yet a rare occurrence in Nigeria.

Cryptococcus gattii VGI Subtypes: Geographical Distribution, Molecular Traits, and Virulence Difference

Background: As a life-threatening fungus, Cryptococcus gattii (C gattii) species complex is emerging worldwide. However, the geographical distribution, molecular traits, and virulence difference are poorly characterized in China.Results: From 2011 to 2017, we collected 32 strains of C gattii from 18 hospitals across China, of which 27 [84·4%] strains molecular traits were profiled by whole-genome sequencing (WGS) and multi-locus sequence typing (MLST) and compared with strains previously described in China from 2006 to 2020. Totally 119 clinical cases caused by C gattii strains (87 in previous reports and 32 in our study) distributed widely in 20 provincial-level administrative regions of China, of which 114 strains molecular types were obtained. The majority molecular type was VGI (81/114, 71·1%) and the other was VGII (33/114, 28·9%). Four major subtypes of VGI (VGIa, VGIb, VGIc, and VGId) were revealed from global C gattii VGI (n=308), respectively accounting for 52·9% (163/308), 36·0% (111/308), 3·9% (12/308), and 4·2% (13/308). The other nine strains could not be assigned to these four subtypes clearly. Our clinical data suggested that VGIb cases had a worse clinical outcome than VGIa, which was consistent with in vitro and in vivo experiments. In addition, a candidate virulence SNP on SOD2 in VGIa was initially identified by comparing high-quality de novo reference genome.Conclusions: The geographical distribution of C gattii species complex was first described in China. C gattii VGI could be clearly segregated into four major subtypes based on genomics profiles and VGIb was more virulent than VGIa in China. Our study suggests the molecular type of C gattii is necessary for personalized treatment in clinic.