Decreased daytime light intensity at nonwindow hospital beds: Comparisons with light intensity at window hospital beds and light exposure in nonhospitalized elderly individuals

Light is crucial for the synchronization of internal biological rhythms with environmental rhythms. Hospitalization causes a range of unfavorable medical conditions, including delirium, sleep disturbances, depressed mood, and increased fall, especially in elderly people. The hospital room environment contributes significantly to patients’ circadian physiology and behavior; however, few studies have evaluated light intensity in hospital settings. In this study, bedside light intensity during the daytime (6:00–21:00) was measured at 1-min intervals using a light meter on 4869 bed-days at the Inabe General Hospital in Mie, Japan (latitude 35°N), for approximately 1 month in each season. Daytime light exposure in home settings was measured in nonhospitalized elderly individuals (n = 1113) for two consecutive days at 1-min intervals using a wrist light meter. Median daytime light intensities at window and nonwindow hospital beds were 327.9 lux [interquartile range (IQR), 261.5–378.4] and 118.4 lux (IQR, 100.6–142.9), respectively, and daytime light intensity measured in nonhospitalized elderly individuals was 337.3 lux (IQR, 165.5–722.7). Compared with data in nonhospitalized elderly individuals, nonwindow beds were exposed to significantly lower daytime light intensity (p < 0.001), whereas window beds were exposed to similar daytime light intensity to that of home settings (p = 1.00). These results were consistent regardless of seasons (spring, summer, fall, and winter) or room directions (north vs. south facing). The lowest median daytime light intensity was observed at nonwindow beds in north-facing rooms during the winter (84.8 lux; IQR, 76.0–95.8). Further studies evaluating the incidence of in-hospital outcomes between patients hospitalized in window and nonwindow beds are needed.     

Epimorphin is involved in differentiation of rat hepatic stem-like cells through cell-cell contact

Epimorphin, a mesenchymal cell surface-associated molecule, is detected on hepatic stellate cells (HSCs) in the liver. Here, we show the involvement of epimorphin in differentiation of rat hepatic stem-like cells (HSLCs) through contact with HSCs. HSLCs, isolated from adult rats, cultured in stellate cell-conditioned medium had no phenotypic and morphological changes, whereas HSLCs co-cultured with HSCs expressed albumin, transferrin, and tyrosine aminotransferase. An anti-epimorphin antibody inhibited hepatocytic differentiation of HSLCs in co-culture. Furthermore, epimorphin induced mRNA expression of albumin, transferrin, tyrosine aminotransferase, and gamma-glutamyl transpeptidase with decrease of c-kit and musashi-1. Morphologically, HSLCs piled up when co-cultured with HSCs, which was dramatically inhibited by an anti-epimorphin antibody. HSLCs contact with epimorphin started piling up, changed their shape from flat to cuboidal, and subsequently developed bile-canaliculi-like structures. In conclusion, epimorphin is a factor that induces differentiation of hepatic stem-like cells through epithelial-mesenchymal cell contact.     

Occurrence of free D-amino acids and aspartate racemases in hyperthermophilic archaea.

The occurrence of free D-amino acids and aspartate racemases in several hyperthermophilic archaea was investigated. Aspartic acid in all the hyperthermophilic archaea was highly racemized. The ratio of D-aspartic acid to total aspartic acid was in the range of 43.0 to 49.1%. The crude extracts of the hyperthermophiles exhibited aspartate racemase activity at 70 degrees C, and aspartate racemase homologous genes in them were identified by PCR. D-Enantiomers of other amino acids (alanine, leucine, phenylalanine, and lysine) in Thermococcus strains were also detected. Some of them might be by-products of aspartate racemase. It is proven that D-amino acids are produced in some hyperthermophilic archaea, although their function is unknown.     

SEA-scFv as a bifunctional antibody: construction of a bacterial expression system and its functional analysis

A SEA-antibody single chain Fv (SEA-scFv) fusion protein was produced by bacterial expression system in this study. SEA-scFv has both staphylococcal enterotoxin A (SEA) effects and antibody activity directed at the epithelial mucin core protein MUC1, a cancer associated antigen. It was expressed mostly in the cytoplasm as an insoluble form. The gene product was solubilized by guanidine hydrochloride, refolded by conventional dilution method, and purified using metal-chelating chromatography. The resulting SEA-scFv fusion protein preparation was found to react with MUC1 and MHC class II antigens and had the ability to enhance cytotoxicity of lymphokine activated killer cells with a T cell phenotype against a human bile duct carcinoma cell line, TFK-1, expressing MUC1. This genetically engineered SEA-scFv fusion protein promises to be an important reagent for cancer immunotherapy.     

Structure, backbone dynamics and interactions with RNA of the C-terminal RNA-binding domain of a mouse neural RNA-binding protein, Musashi1

Musashi1 is an RNA-binding protein abundantly expressed in the developing mouse central nervous system. Its restricted expression in neural precursor cells suggests that it is involved in the regulation of asymmetric cell division. Musashi1 contains two ribonucleoprotein (RNP)-type RNA-binding domains (RBDs), RBD1 and RBD2. Our previous studies showed that RBD1 alone binds to RNA, while the binding of RBD2 is not detected under the same conditions. Joining of RBD2 to RBD1, however, increases the affinity to greater than that of RBD1 alone, indicating that RBD2 contributes to RNA-binding. We have determined the three-dimensional solution structure of the C-terminal RBD (RBD2) of Musashi1 by NMR. It folds into a compact alpha beta structure comprising a four-stranded antiparallel beta-sheet packed against two alpha-helices, which is characteristic of RNP-type RBDs. Special structural features of RBD2 include a beta-bulge in beta2 and a shallow twist of the beta-sheet. The smaller 1H-15N nuclear Overhauser enhancement values for the residues of loop 3 between beta2 and beta3 suggest that this loop is flexible in the time-scale of nano- to picosecond order. The smaller 15N T2 values for the residues around the border between alpha2 and the following loop (loop 5) suggest this region undergoes conformational exchange in the milli- to microsecond time-scale. Chemical shift perturbation analysis indicated that RBD2 binds to an RNA oligomer obtained by in vitro selection under the conditions for NMR measurements, and thus the nature of the weak RNA-binding of RBD2 was successfully characterized by NMR, which is otherwise difficult to assess. Mainly the residues of the surface composed of the four-stranded beta-sheet, loops and C-terminal region are involved in the interaction. The appearance of side-chain NH proton resonances of arginine residues of loop 3 and imino proton resonances of RNA bases upon complex formation suggests the formation of intermolecular hydrogen bonds. The structural arrangement of the rings of the conserved aromatic residues of beta2 and beta3 is suitable for stacking interaction with RNA bases, known to be one of the major protein-RNA interactions, but a survey of the perturbation data suggested that the stacking interaction is not ideally achieved in the complex, which may be related to the weaker RNA-binding of RBD2.     

Oxidative Stress Impairs the Heat Stress Response and Delays Unfolded Protein Recovery

Background

Environmental changes, air pollution and ozone depletion are increasing oxidative stress, and global warming threatens health by heat stress. We now face a high risk of simultaneous exposure to heat and oxidative stress. However, there have been few studies investigating their combined adverse effects on cell viability.

Principal Findings

Pretreatment of hydrogen peroxide (H₂O₂) specifically and highly sensitized cells to heat stress, and enhanced loss of mitochondrial membrane potential. H₂O₂ exposure impaired the HSP40/HSP70 induction as heat shock response (HSR) and the unfolded protein recovery, and enhanced eIF2α phosphorylation and/or XBP1 splicing, land marks of ER stress. These H₂O₂-mediated effects mimicked enhanced heat sensitivity in HSF1 knockdown or knockout cells. Importantly, thermal preconditioning blocked H₂O₂–mediated inhibitory effects on refolding activity and rescued HSF1 +/+ MEFs, but neither blocked the effects nor rescued HSF1 -/- MEFs. These data strongly suggest that inhibition of HSR and refolding activity is crucial for H₂O₂–mediated enhanced heat sensitivity.

Conclusions

H₂O₂ blocks HSR and refolding activity under heat stress, thereby leading to insufficient quality control and enhancing ER stress. These uncontrolled stress responses may enhance cell death. Our data thus highlight oxidative stress as a crucial factor affecting heat tolerance.