Mechanisms of Interference with Simian Virus 40 (SV40) DNA Replication by Trans-Dominant Mutants of SV40 Large T Antigen

Mutations at multiple sites within the simian virus 40 (SV40) early region yield large T antigens which interfere trans dominantly with the replicative activities of wild-type T antigen. A series of experiments were conducted to study possible mechanisms of interference with SV40 DNA replication caused by these mutant T antigens. First, the levels of wild-type T antigen expression in cells cotransfected with wild-type and mutant SV40 DNAs were examined; approximately equal levels of wild-type T antigen were seen, regardless of whether the cotransfected mutant was trans dominant or not. Second, double mutants that contained the mutation of inA2827, a strong trans-dominant mutation with a 12-bp linker inserted at the position encoding amino acid 520, and various mutations in other parts of the large-T-antigen coding region were constructed. The trans-dominant interference of inA2827 was not affected by second mutations within the p105Rb binding site or the amino or carboxy terminus of large T antigen. Mutation of the nuclear localization signal partially reduced the trans dominance of inA2827. The large T antigen of mutant inA2815 contains an insertion of 4 amino acids at position 168 of large T; this T antigen fails to bind SV40 DNA but is not trans dominant for DNA replication. The double mutant containing the mutations of both inA2815 and in A2827 was not trans dominant. The large T antigen of dlA2433 lacks amino acids 587 to 589, was unstable, and failed to bind p53. Combining the dlA2433 mutation with the inA2827 mutation also reversed the trans dominance completely, but the effect of the dlA2433 mutation on trans dominance can be explained by the instability of this double mutant protein. In addition, we examined several mutants with conservative point mutations in the DNA binding domain and found that most of them were not trans dominant. The implications of the results of these experiments on possible mechanisms of trans dominance are discussed

A Novel Translational Regulation Function for the Simian Virus 40 Large-T Antigen Gene.

Cells use the interferon-induced, double-stranded-RNA-dependent protein kinase PKR as a defense against virus infections. Upon activation, PKR phosphorylates and thereby inactivates the protein synthesis initiation factor eIF-2, resulting in the cessation of protein synthesis. Viruses have evolved various strategies to counteract this cellular defense. In this paper, we show that simian virus 40 (SV40) large-T antigen can antagonize the translational inhibitory effect resulting from the activation of PKR in virus-infected cells. Unlike the situation with other virus-host cell interactions, SV40 large-T antigen does not block the activation of PKR, suggesting that SV40 counteracts the cellular antiviral response mediated by PKR at a step downstream of PKR activation. Mutational analysis of large-T antigen indicates that a domain located between amino acids 400 and 600 of large-T antigen is responsible for this function. These results define a novel translational regulatory function for the SV40 large-T antigen

TransNet: Transparent Object Manipulation Through Category-Level Pose Estimation

Transparent objects present multiple distinct challenges to visual perception systems. First, their lack of distinguishing visual features makes transparent objects harder to detect and localize than opaque objects. Even humans find certain transparent surfaces with little specular reflection or refraction, like glass doors, difficult to perceive. A second challenge is that depth sensors typically used for opaque object perception cannot obtain accurate depth measurements on transparent surfaces due to their unique reflective properties. Stemming from these challenges, we observe that transparent object instances within the same category, such as cups, look more similar to each other than to ordinary opaque objects of that same category. Given this observation, the present paper explores the possibility of category-level transparent object pose estimation rather than instance-level pose estimation. We propose \textit{\textbf{TransNet}}, a two-stage pipeline that estimates category-level transparent object pose using localized depth completion and surface normal estimation. TransNet is evaluated in terms of pose estimation accuracy on a large-scale transparent object dataset and compared to a state-of-the-art category-level pose estimation approach. Results from this comparison demonstrate that TransNet achieves improved pose estimation accuracy on transparent objects. Moreover, we use TransNet to build an autonomous transparent object manipulation system for robotic pick-and-place and pouring tasks

Therapeutic Targeting of Replicative Immortality

One of the hallmarks of malignant cell populations is the ability to undergo continuous proliferation. This property allows clonal lineages to acquire sequential aberrations that can fuel increasingly autonomous growth, invasiveness, and therapeutic resistance. Innate cellular mechanisms have evolved to regulate replicative potential as a hedge against malignant progression. When activated in the absence of normal terminal differentiation cues, these mechanisms can result in a state of persistent cytostasis. This state, termed “senescence,” can be triggered by intrinsic cellular processes such as telomere dysfunction and oncogene expression, and by exogenous factors such as DNA damaging agents or oxidative environments. Despite differences in upstream signaling, senescence often involves convergent interdependent activation of tumor suppressors p53 and p16/pRB, but can be induced, albeit with reduced sensitivity, when these suppressors are compromised. Doses of conventional genotoxic drugs required to achieve cancer cell senescence are often much lower than doses required to achieve outright cell death. Additional therapies, such as those targeting cyclin dependent kinases or components of the PI3K signaling pathway, may induce senescence specifically in cancer cells by circumventing defects in tumor suppressor pathways or exploiting cancer cells’ heightened requirements for telomerase. Such treatments sufficient to induce cancer cell senescence could provide increased patient survival with fewer and less severe side effects than conventional cytotoxic regimens. This positive aspect is countered by important caveats regarding senescence reversibility, genomic instability, and paracrine effects that may increase heterogeneity and adaptive resistance of surviving cancer cells. Nevertheless, agents that effectively disrupt replicative immortality will likely be valuable components of new combinatorial approaches to cancer therapy

Multiscale Understanding of Electric Polarization in Poly(vinylidene fluoride)-Based Ferroelectric Polymers

Poly(vinylidene fluoride) (PVDF) and PVDF-based copolymers with trifluoroethylene (PVDF-TrFE) have attracted considerable academic and industrial interest due to their ferroelectric properties, which are only presented in very few polymers. However, the underlying fundamentals of molecular ordering and induced polarizations are complex and not fully understood. Herein, PVDF, PVDF-TrFE and their blends, prepared using melt extrusion and hot pressing, have been selected to obtain controlled case studies with well-defined chain ordering and microstructures. Impedance analysis and terahertz time-domain spectroscopy are exploited to investigate electric polarization in PVDF-based polymers at different length scales. The extruded ferroelectric films show in-plane chain orientation and higher domain wall density compared to hot pressed films with randomly-distributed polymer chains, which favors the polarization at low frequencies (Hz to MHz), as concluded from the higher dielectric constants and more prominent high electric field polarization switching features. However, the domain walls cannot respond at high frequencies, which leads to lower dielectric constants in the extruded films at THz frequencies

Exurban and suburban forests have superior healthcare benefits beyond downtown forests

Forests in urban areas provide great healthcare benefits to citizens, but it is less well known whether this benefit is related to different geographical spaces. We selected exurban forest, suburban forest, downtown forest, and urban control in Guangzhou, China to analyze the change characteristics of negative air ion concentration (NAIC), air oxygen content (AOC), and human comfort index (HCI). Based on Criteria Importance Through Intercriteria Correlation (CRITIC) method, the urban forest comprehensive healthcare index (UFCHI) was established. Finally, the evaluation criteria for UFCHI were identified by cluster analysis. The results demonstrated that (1) The NAIC in exurban forest (2,713 ± 1,573 ions/cm3) and suburban forest (2,147 ± 923 ions/cm3) was evidently better than downtown forest (1,130 ± 255 ions/cm3) and urban control (531 ± 162 ions/cm3). (2) The AOC was in the order of exurban forest (21.17 ± 0.38%) > suburban forest (21.13 ± 0.30%) > downtown forest (21.10 ± 0.16%) > urban control (20.98 ± 0.12%). (3) The HCI in urban control (5.56 ± 2.32) and downtown forest (5.15 ± 1.80) is higher than suburban forest (4.02 ± 1.53) and exurban forest (3.71 ± 1.48). (4) The UFCHI in exurban forest (1.000), suburban forest (0.790), and downtown forest (0.378) were beneficial to human health to some extent, while urban control (0.000) was at Level IV, having no healthcare benefit. Except in winter, the UFCHI in exurban forest and suburban forest were all at Level II and above; while downtown forest and urban control were all at Level III and below at all seasons. Overall, urban forests in the exurbs and suburbs have better healthcare benefits than those in the downtowns. Furthermore, it is recommended that urban residents visit exurban and suburban forests for forest therapy in spring, summer, and autumn

Comparative Pharmacokinetics and Preliminary Pharmacodynamics Evaluation of Piscidin 1 Against PRV and PEDV in Rats

Antimicrobial peptide (Piscidin-1) is an effective natural polypeptide, which has great influence and potential on porcine epidemic diarrhea virus (PEDV) and pseudorabies virus (PRV). As an alternative antibiotic substitute, Piscidin-1 was subjected for pharmacokinetics study with three administration routes (i.v, i.m, and p.o) after a single dose of 2 mg/kg in rats and preliminary pharmacodynamics including antiviral activity in cell against PEDV and PRV. Based on 50 percent tissue culture infective dose (TCID50), there were about 2 and 10% virus survived ratios for Piscidin-1 against PRV and PEDV, respectively. The plaque test showed 1 and 2 μg/ml Piscidin-1 could eliminate 95% PRV and 85% PEDV, respectively. The main pharmacokinetics parameters of Cmax, AUC0−∞, Ke, t1/2, Tmax, MRT, and Clb in plasma were not applicable value, 25.9 μg*h/ml, 0.041 h−1, 16.97 h, not available value, 22.77 h, 0.067 L/h*kg after i.v administration, 2.37 μg/ml, 18.95 μg*h/ml, 0.029 h−1, 23.50 h, 0.33 h, 30.12 h, 0.095 L/h*kg after i.m administration and 0.73 μg/ml, 9.63 μg*h/ml, 0.036 h−1, 19.46 h, 0.50 h, 26.76 h, 0.171 L/h*kg after p.o administration. The bioavailability values after i.m and p.o administrations were calculated as 73.17 and 37.18%, respectively. The i.m administration was selected for pharmacokinetics study in ileum content against PEDV. The main pharmacokinetic parameters of Cmax, AUC0−∞, Ke, t1/2, Tmax, MRT, and Clb in ileum content were 1.67 μg/ml, 78.40 μg*h/ml, 0.034 h−1, 20.16 h, 8.12 h, 36.45 h, 0.026 L/h*kg. The Cmax values in plasma (2.37 μg/ml) and ileum content (1.67 μg/ml) were higher than the effective inhibitory concentration determined in the plaque test, and this indicates that Piscidin-1 might have effective inhibition effect against PRV and PEDV after administration of 2 mg/kg i.m. The results of this study represent the first investigations toward the pharmacokinetic characteristics of piscidin-1 in plasma upon three different administration routes, among which i.m. resulted in the highest bioavailability (73.17%). Furthermore, the pharmacokinetics study of ileum content indicated Piscidin-1 might have good effect against PEDV and could be regarded as an alternative antibiotic in clinical veterinary in the future study

Therapeutic targeting of replicative immortality

One of the hallmarks of malignant cell populations is the ability to undergo continuous proliferation. This property allows clonal lineages to acquire sequential aberrations that can fuel increasingly autonomous growth, invasiveness, and therapeutic resistance. Innate cellular mechanisms have evolved to regulate replicative potential as a hedge against malignant progression. When activated in the absence of normal terminal differentiation cues, these mechanisms can result in a state of persistent cytostasis. This state, termed “senescence,” can be triggered by intrinsic cellular processes such as telomere dysfunction and oncogene expression, and by exogenous factors such as DNA damaging agents or oxidative environments. Despite differences in upstream signaling, senescence often involves convergent interdependent activation of tumor suppressors p53 and p16/pRB, but can be induced, albeit with reduced sensitivity, when these suppressors are compromised. Doses of conventional genotoxic drugs required to achieve cancer cell senescence are often much lower than doses required to achieve outright cell death. Additional therapies, such as those targeting cyclin dependent kinases or components of the PI3K signaling pathway, may induce senescence specifically in cancer cells by circumventing defects in tumor suppressor pathways or exploiting cancer cells’ heightened requirements for telomerase. Such treatments sufficient to induce cancer cell senescence could provide increased patient survival with fewer and less severe side effects than conventional cytotoxic regimens. This positive aspect is countered by important caveats regarding senescence reversibility, genomic instability, and paracrine effects that may increase heterogeneity and adaptive resistance of surviving cancer cells. Nevertheless, agents that effectively disrupt replicative immortality will likely be valuable components of new combinatorial approaches to cancer therapy

Bibliometric and visual analysis of spinal cord injury-associated macrophages from 2002 to 2023

BackgroundSpinal cord injury (SCI) triggers motor, sensory, and autonomic impairments that adversely damage patients' quality of life. Its pathophysiological processes include inflammation, oxidative stress, and apoptosis, although existing treatment options have little success. Macrophages have a vital function in controlling inflammation in SCI, with their M1-type and M2-type macrophages dominating early inflammatory effects and late brain tissue repair and regeneration, respectively. However, there is a dearth of rigorous bibliometric study in this sector to explore its dynamics and trends. This study intends to examine the current status and trends of macrophage usage in SCI using bibliometric methodologies, which may drive novel therapeutic options.MethodsIn this study, the Web of Science Core Collection (WOSCC) was utilized to collect publications and reviews on macrophages in SCI from 2002 to 2023. Bibliometrics and visualization analyses were performed by VOSviewer, CiteSpace, the R package “bibliometrix”, and online analytic platforms. These analyses covered a variety of aspects, including countries and institutions, authors and co-cited authors, journals and co-cited journals, subject categories, co-cited references, and keyword co-occurrences, in order to provide insights into the research trends and hotspots in this field.Results1,775 papers were included in the study, comprising 1,528 articles and 247 reviews. Our research analysis demonstrates that the number of relevant studies in this sector is expanding, specifically the number of publications in the United States and China has risen dramatically. However, there are fewer collaborations between institutions in different nations, and international cooperation needs to be reinforced. Among them, Popovich PG became the leader in the field, and significant journals include Experimental Neurology, Journal of Neurotrauma, and Journal of Neuroscience. Research hotspots involve macrophage polarization, microglia, astrocytes, signaling, cytokines, inflammation, and neuroprotection.ConclusionsThis analysis gives, for the first time, a comprehensive overview of bibliometric studies on macrophages in SCI over the past 20 years. This study not only gives an extensive picture of the knowledge structure but also indicates trends in the subject. The systematic summarization gives a complete and intuitive understanding of the link between spinal cord damage and macrophages and provides a great reference for future related studies

Separable Bilayer Microfiltration Device for Viable Label-free Enrichment of Circulating Tumour Cells

The analysis of circulating tumour cells (CTCs) in cancer patients could provide important information for therapeutic management. Enrichment of viable CTCs could permit performance of functional analyses on CTCs to broaden understanding of metastatic disease. However, this has not been widely accomplished. Addressing this challenge, we present a separable bilayer (SB) microfilter for viable size-based CTC capture. Unlike other single-layer CTC microfilters, the precise gap between the two layers and the architecture of pore alignment result in drastic reduction in mechanical stress on CTCs, capturing them viably. Using multiple cancer cell lines spiked in healthy donor blood, the SB microfilter demonstrated high capture efficiency (78–83%), high retention of cell viability (71–74%), high tumour cell enrichment against leukocytes (1.7–2 × 10^3), and widespread ability to establish cultures post-capture (100% of cell lines tested). In a metastatic mouse model, SB microfilters successfully enriched viable mouse CTCs from 0.4–0.6 mL whole mouse blood samples and established in vitro cultures for further genetic and functional analysis. Our preliminary studies reflect the efficacy of the SB microfilter device to efficiently and reliably enrich viable CTCs in animal model studies, constituting an exciting technology for new insights in cancer research