Aluminum compounds enhance lipid peroxidation in liposomes: insight into cellular damage caused by oxidative stress

Aluminum (Al) has been proposed as one of the critical environmental factors responsible for several neurodegenerative diseases such as Alzheimer's disease. However, the suggested mechanism involving the contribution of reactive oxygen species still remains controversial. We have first attempted to identify Al compounds either in its ionic or complexed forms that cause oxidative stress in biological systems. For this purpose, we examined the effect of inorganic Fe(2+)- and organic radical initiator (2,2'-azobis (2-amidinopopane) hydrochloride; AAPH)-induced lipid peroxidation by using aluminum (Al(3+)) nitrate and tris(maltolato)aluminum(III) complex (ALM) with respect to molecular oxygen (O(2)) consumption and membrane fluidity change in liposomes as biological membrane models. The following important results were obtained: (1) ALM enhanced the lipid peroxidation induced by Fe(2+) and AAPH in phosphatidylcholine liposomes; this corresponded well with the promotion of O(2) uptake in the same liposomes, (2) Al(3+) increased both lipid peroxidation and O(2) consumption in phosphatidylserine liposomes in the presence of Fe(2+), and (3) both Al(3+) and ALM affected the membrane fluidity on the inner side. It has been concluded that ALM induces higher lipid peroxidation in liposomes than Al(3+); this finding will be useful to gain an insight into the role of Al in cellular damage in relation to oxidative stress.     

N-glycolylneuraminic acid deficiency in mice: implications for human biology and evolution

Humans and chimpanzees share >99% identity in most proteins. One rare difference is a human-specific inactivating deletion in the CMAH gene, which determines biosynthesis of the sialic acid N-glycolylneuraminic acid (Neu5Gc). Since Neu5Gc is prominent on most chimpanzee cell surfaces, this mutation could have affected multiple systems. However, Neu5Gc is found in human cancers and fetuses and in trace amounts in normal human tissues, suggesting an alternate biosynthetic pathway. We inactivated the mouse Cmah gene and studied the in vivo consequences. There was no evidence for an alternate pathway in normal, fetal, or malignant tissue. Rather, null fetuses accumulated Neu5Gc from heterozygous mothers and dietary Neu5Gc was incorporated into oncogene-induced tumors. As with humans, there were accumulation of the precursor N-acetylneuraminic acid and increases in sialic acid O acetylation. Null mice showed other abnormalities reminiscent of the human condition. Adult mice showed a diminished acoustic startle response and required higher acoustic stimuli to increase responses above the baseline level. In this regard, histological abnormalities of the inner ear occurred in older mice, which had impaired hearing. Adult animals also showed delayed skin wound healing. Loss of Neu5Gc in hominid ancestors approximately 2 to 3 million years ago likely had immediate and long-term consequences for human biology.     

Antidiabetic copper(II)-picolinate: impact of the first transition metal in the metallopicolinate complexes

In order to examine the effect of metallopicolinate complexes with first transition metals and develop complexes that are more active than an insulinomimetic leading compound such as oxovanadium(IV)-picolinate complex, VO(pa)2, 10 metallopicolinate complexes were prepared, and their in vitro insulinomimetic and in vivo antidiabetic activities were evaluated. The in vitro activity was estimated by determining the inhibitory effects of these complexes on free fatty acid release from isolated rat adipocytes treated with epinephrine. Among the complexes, Cu(pa)2, and Mn(pa)3 exhibited higher activity than their respective metal ions and better activity than VO(pa)2. Since Cu(pa)2 was non-toxic in the cultured rat hepatic M cells, this complex was given streptozotocin (STZ)-induced type 1-like diabetic mice by single intraperitoneal injection, and found that this complex exhibited a higher hypoglycemic effect than the VO(pa)2 complex. Based on these results, we propose that Cu(pa)2 may be a potent alternative antidiabetic agent.     

Chimeras of Channelrhodopsin-1 and -2 from Chlamydomonas reinhardtii Exhibit Distinctive Light-induced Structural Changes from Channelrhodopsin-2

Channelrhodopsin-2 (ChR2) from the green alga Chlamydomonas reinhardtii functions as a light-gated cation channel that has been developed as an optogenetic tool to stimulate specific nerve cells in animals and control their behavior by illumination. The molecular mechanism of ChR2 has been extensively studied by a variety of spectroscopic methods, including light-induced difference Fourier transform infrared (FTIR) spectroscopy, which is sensitive to structural changes in the protein upon light activation. An atomic structure of channelrhodopsin was recently determined by x-ray crystallography using a chimera of channelrhodopsin-1 (ChR1) and ChR2. Electrophysiological studies have shown that ChR1/ChR2 chimeras are less desensitized upon continuous illumination than native ChR2, implying that there are some structural differences between ChR2 and chimeras. In this study, we applied light-induced difference FTIR spectroscopy to ChR2 and ChR1/ChR2 chimeras to determine the molecular basis underlying these functional differences. Upon continuous illumination, ChR1/ChR2 chimeras exhibited structural changes distinct from those in ChR2. In particular, the protonation state of a glutamate residue, Glu-129 (Glu-90 in ChR2 numbering), in the ChR chimeras is not changed as dramatically as in ChR2. Moreover, using mutants stabilizing particular photointermediates as well as time-resolved measurements, we identified some differences between the major photointermediates of ChR2 and ChR1/ChR2 chimeras. Taken together, our data indicate that the gating and desensitizing processes in ChR1/ChR2 chimeras are different from those in ChR2 and that these differences should be considered in the rational design of new optogenetic tools based on channelrhodopsins.     

Environmental Surveillance of Poliovirus in Sewage Water around the Introduction Period for Inactivated Polio Vaccine in Japan

Environmental virus surveillance was conducted at two independent sewage plants from urban and rural areas in the northern prefecture of the Kyushu district, Japan, to trace polioviruses (PVs) within communities. Consequently, 83 PVs were isolated over a 34-month period from April 2010 to January 2013. The frequency of PV isolation at the urban plant was 1.5 times higher than that at the rural plant. Molecular sequence analysis of the viral VP1 gene identified all three serotypes among the PV isolates, with the most prevalent serotype being type 2 (46%). Nearly all poliovirus isolates exhibited more than one nucleotide mutation from the Sabin vaccine strains. During this study, inactivated poliovirus vaccine (IPV) was introduced for routine immunization on 1 September 2012, replacing the live oral poliovirus vaccine (OPV). Interestingly, the frequency of PV isolation from sewage waters declined before OPV cessation at both sites. Our study highlights the importance of environmental surveillance for the detection of the excretion of PVs from an OPV-immunized population in a highly sensitive manner, during the OPV-to-IPV transition period.     

Elucidation of Echovirus 30's Origin and Transmission during the 2012 Aseptic Meningitis Outbreak in Guangdong,China, through Continuing Environmental Surveillance

An aseptic meningitis outbreak occurred in Luoding City of Guangdong, China, in 2012, and echovirus type 30 (ECHO30) was identified as the major causative pathogen. Environmental surveillance indicated that ECHO30 was detected in the sewage of a neighboring city, Guangzhou, from 2010 to 2012 and also in Luoding City sewage samples (6/43, 14%) collected after the outbreak. In order to track the potential origin of the outbreak viral strains, we sequenced the VP1 genes of 29 viral strains from clinical patients and environmental samples. Sequence alignments and phylogenetic analyses based on VP1 gene sequences revealed that virus strains isolated from the sewage of Guangzhou and Luoding cities matched well the clinical strains from the outbreak, with high nucleotide sequence similarity (98.5% to 100%) and similar cluster distribution. Five ECHO30 clinical strains were clustered with the Guangdong environmental strains but diverged from strains from other regions, suggesting that this subcluster of viruses most likely originated from the circulating virus in Guangdong rather than having been more recently imported from other regions. These findings underscore the importance of long-term, continuous environmental surveillance and genetic analysis to monitor circulating enteroviruses.     

Comparison of the biological effects of F at different intracellular levels

We herein examined the biological effects of cells treated with ¹⁸F labeled drugs for positron emission tomography (PET). The relationship between the intracellular distribution of ¹⁸F and levels of damaged DNA has yet to be clarified in detail. We used culture cells (Chinese Hamster Ovary cells) treated with two types of ¹⁸F labeled drugs, fluorodeoxyglucose (FDG) and fluorine ion (HF). FDG efficiently accumulated in cells, whereas HF did not. To examine the induction of DNA double strand breaks (DSB), we measured the number of foci for 53BP1 that formed at the site of DNA DSB. The results revealed that although radioactivity levels were the same, the induction of 53BP1 foci was stronger in cells treated with ¹⁸F-FDG than in those treated with ¹⁸F-HF. The clonogenic survival of cells was significantly lower with ¹⁸F-FDG than with ¹⁸F-HF. We concluded that the efficient accumulation of ¹⁸F in cells led to stronger biological effects due to more severe cellular lethality via the induction of DNA DSB.