Characterization of age‐associated exhausted CD8+ T cells defined by increased expression of Tim‐3 and PD‐1

Aging is accompanied by altered T‐cell responses that result in susceptibility to various diseases. Previous findings on the increased expression of inhibitory receptors, such as programmed cell death protein 1 (PD‐1), in the T cells of aged mice emphasize the importance of investigations into the relationship between T‐cell exhaustion and aging‐associated immune dysfunction. In this study, we demonstrate that T‐cell immunoglobulin mucin domain‐3 (Tim‐3), another exhaustion marker, is up‐regulated on aged T cells, especially CD8⁺ T cells. Tim‐3‐expressing cells also produced PD‐1, but Tim‐3⁺PD‐1⁺ CD8⁺ T cells had a distinct phenotype that included the expression of CD44 and CD62L, from Tim‐3^?PD‐1⁺ cells. Tim‐3⁺PD‐1⁺ CD8⁺ T cells showed more evident properties associated with exhaustion than Tim‐3^?PD‐1⁺ CD8⁺ T cells: an exhaustion‐related marker expression profile, proliferative defects following homeostatic or TCR stimulation, and altered production of cytokines. Interestingly, these cells produced a high level of IL‐10 and induced normal CD8⁺ T cells to produce IL‐10, which might contribute to immune dysregulation in aged mice. The generation of Tim‐3‐expressing CD8⁺ T cells in aged mice seems to be mediated by encounters with antigens but not by specific infection, based on their high expression of CD49d and their unbiased TCR Vβ usage. In conclusion, we found that a CD8⁺ T‐cell population with age‐associated exhaustion was distinguishable by its expression of Tim‐3. These results provide clues for understanding the alterations that occur in T‐cell populations with age and for improving dysfunctions related to the aging of the immune system.     

Increased Immunoreactivities of Cleaved αII-Spectrin and Cleaved Caspase-3 in the Aged Dog Spinal Cord

The activation of caspase-3 is considered to be a reliable marker for apoptotic cell death, and a 120-kDa fragment of αII-spectrin is generated by caspase-3 mediated cleavage of this structural protein. In the present study, we compared cleaved αII-spectrin (120-kDa) and cleaved caspase-3-immunoreactive cells and their protein levels in the cervical (C₅–C₆) and lumbar (L₃–L₄) levels of the spinal cord in adult (1–2 year-old) and aged (10–12 year-old) dogs (German shepherds). Weak cleaved αII-spectrin and cleaved caspase-3 immunoreactivity was found in neurons of the adult group; however, their immunoreactivity was distinctively increased in the neuronal cytoplasm in the aged group compared to those in the adult group, although the distribution pattern of their neurons was similar between the adult and age group. In addition, cleaved αII-spectrin and cleaved caspase-3 levels in the aged spinal cord were markedly increased compared to those in the adult group. These findings suggest that the increases of cleaved αII-spectrin and cleaved caspase-3 immunoreactivity may be related to aging of the spinal cord in dogs.     

Characterization of photodamage to escherichia coli in optical traps

Optical tweezers (infrared laser-based optical traps) have emerged as a powerful tool in molecular and cell biology. However, their usefulness has been limited, particularly in vivo, by the potential for damage to specimens resulting from the trapping laser. Relatively little is known about the origin of this phenomenon. Here we employed a wavelength-tunable optical trap in which the microscope objective transmission was fully characterized throughout the near infrared, in conjunction with a sensitive, rotating bacterial cell assay. Single cells of Escherichia coli were tethered to a glass coverslip by means of a single flagellum: such cells rotate at rates proportional to their transmembrane proton potential (. J. Mol. Biol. 138:541-561). Monitoring the rotation rates of cells subjected to laser illumination permits a rapid and quantitative measure of their metabolic state. Employing this assay, we characterized photodamage throughout the near-infrared region favored for optical trapping (790-1064 nm). The action spectrum for photodamage exhibits minima at 830 and 970 nm, and maxima at 870 and 930 nm. Damage was reduced to background levels under anaerobic conditions, implicating oxygen in the photodamage pathway. The intensity dependence for photodamage was linear, supporting a single-photon process. These findings may help guide the selection of lasers and experimental protocols best suited for optical trapping work.     

Exome Sequencing Identifies Rare Deleterious Mutations in DNA Repair Genes FANCC and BLM as Potential Breast Cancer Susceptibility Alleles

Despite intensive efforts using linkage and candidate gene approaches, the genetic etiology for the majority of families with a multi-generational breast cancer predisposition is unknown. In this study, we used whole-exome sequencing of thirty-three individuals from 15 breast cancer families to identify potential predisposing genes. Our analysis identified families with heterozygous, deleterious mutations in the DNA repair genes FANCC and BLM, which are responsible for the autosomal recessive disorders Fanconi Anemia and Bloom syndrome. In total, screening of all exons in these genes in 438 breast cancer families identified three with truncating mutations in FANCC and two with truncating mutations in BLM. Additional screening of FANCC mutation hotspot exons identified one pathogenic mutation among an additional 957 breast cancer families. Importantly, none of the deleterious mutations were identified among 464 healthy controls and are not reported in the 1,000 Genomes data. Given the rarity of Fanconi Anemia and Bloom syndrome disorders among Caucasian populations, the finding of multiple deleterious mutations in these critical DNA repair genes among high-risk breast cancer families is intriguing and suggestive of a predisposing role. Our data demonstrate the utility of intra-family exome-sequencing approaches to uncover cancer predisposition genes, but highlight the major challenge of definitively validating candidates where the incidence of sporadic disease is high, germline mutations are not fully penetrant, and individual predisposition genes may only account for a tiny proportion of breast cancer families.     

Comparative susceptibility studies of clinically isolated Pseudomonas aeruginosa, Escherichia coli and Klebsiella spp to cefoperazone and cefotaxime

The in-vitro activity of cefotaxime and cefoperazone were compared using clinically isolated Escherichia coli, Klebsiella spp and Pseudomonas aeruginosa. Cefotaxime was found on a weight to weight basis, to be much more active than cefoperazone. All the three species studied show the presence of cefoperazone-resistant population which were sensitive to cefotaxime. The possible mechanisms of resistance to these antibiotics were discussed.     

Minireview: Applied Structural Bioinformatics in Proteomics

The limited sequence similarity of protein sequences with known structures has led to an indispensable need for computational technology to predict their structures. Structural bioinformatics (SB) has become integral in elucidating the sequence–structure–function relationship of a protein. This report focuses on the applications of SB within the context of protein engineering including its limitation and future challenges.     

Identified taste bud cell proliferation in the perihatching chick [published erratum appears in Chem Senses 1998 Aug;23(4):459]

Developing taste buds in the anterior mandibular floor of perihatching chicks were studied by high voltage electron microscopic autoradiography in order to identify proliferating gemmal cell types. Montaged profiles of 29 taste buds in five cases euthanized between embryonic day 21 and posthatching day 2 were analyzed after a single [3H]thymidine injection administered on embryonic day 16, 17 or 18. Results showed that dark cells comprised 55% of identified (n = 900 cells) and 62% of labeled (n = 568 cells) gemmal cells as compared with light, intermediate, basal or perigemmal bud cells. Dark cells had both a greater (P < 0.05) number of labeled cells and a greater amount of label (grains/nucleus) than the other four bud cell types, irrespective of injection day. The nuclear area (micron 2) of dark cells was not significantly larger (P > 0.05) than that of the other gemmal cell types and therefore cannot account for the greater amount for label in the dark cells. Interestingly, only dark cells showed a positive correlation (P < 0.003) between amount of label and nuclear area. Results suggest that, during the perihatching period of robust cell proliferation, dividing dark cells may give rise primarily, but not exclusively, to dark cell progeny.      

Life cycle cost analysis of distributed versus centralized plastic sorting and recycling

Miniaturizing plastic recycling through distributed systems has been viewed as a way to manage waste closer to the source while minimizing logistics requirements. The environmental performance of distributed manufacturing and waste management systems has been evaluated, but few studies have measured the financial performance. This study combines life cycle costing and hybrid simulation modeling to compare the net present value of small-scale distributed versus large-scale centralized systems of sorting and recycling plastic bottles and takeaway containers disposed in Singapore over 7 years. The results showed that distributed systems face a net financial loss at existing prices of SGD80–120/tonne recycled pellets. This is because of the high operation costs, particularly the labor costs due to the reliance on manual sorting. Despite being closer to the waste sources, distributed scenarios have higher fuel costs due to the poorer fuel efficiency of commercial vans compared to the larger trucks in the centralized scenarios. To improve the financial performance of distributed small-scale plastic recycling systems, it is generally recommended that small-scale sorting facilities reduce the reliance on manual labor; the smaller trucks should have higher fuel economies than conventional large waste hauling trucks; the number of small-scale facilities set up should match the amount of waste to be converted; and the price of the recycled pellets should be high enough to recover the high operating costs of recycling. The findings of this study provide motivation for future research in evaluating the financial performance of distributed recycling of other waste streams. This article met the requirements for a gold-gold data badge JIE data openness badge described at http://jie.click/badges