Biomedical subjects
Publications and source records attributed to Hideaki Saito.
Oxazolidinone-functionalized enecarbamates undergo diastereoselective E/Z photoisomerization upon direct and triplet sensitized irradiations with chiral/achiral sensitizers, showing that the enhanced product diastereoselectivity depends on the solvent and temperature.
[reaction: see text]. Oxazolidinone-functionalized enecarbamates show contrasting behavior upon oxidation by singlet oxygen and by ozone. The observed stereoselectivity difference indicates that the oxidation with ozone is subject to classic steric effects, whereas the very high selectivity in the photooxidation with singlet oxygen is derived from vibrational deactivation.
Morbidity of intra-abdominal abscess is increased when severely injured patients are fed parenterally. Lack of enteral nutrition appears to impair peritoneal cavity host defense. Because the transcription factor nuclear factor kappaB (NFkappaB) regulates various genes involved in inflammatory responses and its activation is important for host defense, we hypothesized that enteral nutrition would preserve appropriate NFkappaB activation in peritoneal resident cells (PRCs), the first defense line against peritoneal contamination. Mice (n = 105) were randomized to chow (n = 38), intravenous (IV)-total parenteral nutrition (TPN) (n = 34), or intragastric (IG)-TPN (n = 33) for 5 days' feeding. In experiment 1, PRCs were harvested for measurement of intranuclear NFkappaB activity with or without in vitro lipopolysaccharide (LPS) stimulation using laser scanning cytometry and enzyme-linked immunoabsorbant assay. PRC numbers tended to be higher in enterally fed mice than in IV-TPN mice. The main PRC subpopulation was macrophages in all groups. NFkappaB activation was increased in response to LPS in chow mice, whereas there was no increase in the IV-TPN group. IG-TPN mice demonstrated moderate NFkappaB activation. In experiment 2, mice underwent cecal ligation and puncture (CLP). Survival was observed up to 5 days. In another set of mice, tumor necrosis factor (TNF) alpha levels of peritoneal lavaged fluid were measured 4 h after CLP. Survival times after CLP improved in the chow and IG-TPN groups compared with the IV-TPN group. TNFalpha levels were significantly higher in the chow than in the IV-TPN group. In conclusion, parenteral nutrition decreases PRC number and blunts NFkappaB activation in PRCs. These changes may impair host defense in the peritoneal cavity.
The geometry (donor-acceptor distance) and association constant of the ground-state CT complex were considerably affected by applied pressure, thus enhancing the reaction rate and the adduct yield particularly upon CT excitation, but the diastereoselectivity did not show any substantial change at elevated pressures in both excitation modes.
The selective excitation of the charge-transfer (CT) complex and the direct excitation of the substrate gave distinctly different product ratios and diastereomeric excesses (de's), as well as their temperature dependencies, in [2 + 2] photocycloaddition of (E)-stilbene to bis((R)-1-methylpropyl) fumarate, clearly demonstrating that the excited CT complex and the conventional exciplex differ in structure and reactivity. This conclusion is supported by the contrasting fluorescence behavior exhibited by the relevant excited species, particularly at low temperatures.
Several specific nutritional substrates have been shown to augment and/or modulate host immune function. Some enteral formulas enriched with specific immune-modulating nutrients are presently available for clinical use in Japan. Such nutrients include n-3 fatty acids, arginine, glutamine and nucleotides. Recent meta-analyses of clinical trials showed risk of infection, length of hospital stay and medical costs to be reduced by immunonutrition. The benefits of enteral immunonutrition to be most pronounced in GI surgical patients. However, in critical illness, it is difficult to draw any conclusion on the effect of immunonutrition because of the heterogeneity of the critically ill patients and few clinical trials Further clinical trials to determine which groups of patients are indicated for immunonutrition, as well as what is the optimal combinations of specific nutrients, are needed. Studies are also required to determine the safety of immunonutrition.
The photodecarboxylation of chiral mesityl alkanoate to mesitylalkane has been studied experimentally/theoretically, and it has been found that the photodecarboxylation proceeds to give the product in > 99% enantiomeric excesses under a variety of conditions, indicating no involvement of any radical intermediates, but that the reaction proceeds through the concerted cheletropic extrusion of CO2 from the energetically less-favored s-cis conformation.
Dietary restriction impairs polymorphonuclear neutrophil (PMN) recruitment into the local inflammatory site, resulting in susceptibility to infection. Probiotics enhance host immunity via conditioning host intestinal microflora. Oral administration of Bifidobacterium longum culture condensate (BCC) in a diet-restricted murine peritonitis model may enhance PMN recruitment into the inflammatory site. Male ICR mice (n = 40) were assigned in equal numbers to control or BCC groups and subjected to 75% restricted food intake for 7 d. During dietary restriction, controls received only standard mouse chow, whereas the BCC group received standard mouse chow containing 1% BCC. Mice were killed before (0 h) or after (2 or 4 h) intraperitoneal glycogen injection. Peritoneal lavage fluid and exudative cells were recovered by peritoneal lavage. Peritoneal exudative cell number was counted. Tumor necrosis factor-alpha, interleukin-6, macrophage inflammatory protein-2, and interleukin-10 concentrations in peritoneal lavage fluid were determined by enzyme-linked immunosorbent assay. CD11b, CD18, CD31, and CD62L expressions on circulating PMNs were measured by flow cytometry. Oral BCC administration upregulated PMN recruitment into the peritoneal cavity and increased peritoneal fluid cytokine concentrations as well as CD18 and CD62L expressions on circulating PMNs during glycogen-induced peritonitis. Oral BCC administration in a diet-restricted murine peritonitis model augmented PMN recruitment into the inflammatory site by upregulating cytokine concentrations in the local inflammatory site and adhesion molecule expression on circulating PMNs. Oral BCC administration may be a favorable modality for improving dietary restriction-induced host immunosuppression.
Tyrosine phosphorylation plays a critical role in signal transduction pathways in immune cells. Laser scanning cytometer (LSC), a newly developed microscope-based cytofluorometer, may overcome shortcomings of Western blotting and flow cytometry in the detection of intracellular signaling transduction. The aims of this study were to visualize and quantitate intracellular phosphotyrosine in the peritoneal cells harvested from diet-restricted mice by LSC. In addition, using LSC, we identified the main cell type with activated tyrosine phosphorylation in response to an inflammatory stimulus and we investigated the intracellular distribution of tyrosine phosphorylation within the peritoneal macrophages. Mice were assigned to the ad libitum and diet-restricted, i.e., 75% restricted food intake, groups. After 7 days of pair feeding, the peritoneal cells were harvested. Tyrosine phosphorylation in the harvested cells with either N-formyl-methionyl-leucyle-phenylalanine (fMLP) or lipopolysaccharide (LPS) stimulation was examined using LSC. Tyrosine phosphorylation of peritoneal cells from the diet-restricted group was significantly higher than that from the ad libitum group, regardless of stimulation. Stimulation of peritoneal cells with either fMLP or LPS significantly increased tyrosine phosphorylation in the ad libitum group, but not in the diet-restricted group. The relocation feature of LSC revealed that the cells with distinct tyrosine phosphorylation were macrophages. Topographic analysis demonstrated that phosphotyrosine was localized mainly in the cytoplasm of these cells. In summary, LSC revealed that tyrosine phosphorylation is mainly in the cytoplasm of the peritoneal macrophages and is deranged by diet restriction. LSC is a powerful tool for the study of intracellular signaling transduction.
Appropriate polymorphonuclear neutrophil (PMN) recruitment is essential for host defense against infection. We investigated the significance of the preoperative PMN adhesion-migration process, as assessed by the flow chamber method, on postoperative infectious complications. Thirty-one consecutive patients with gastrointestinal malignancies, 21 colorectal and 10 gastric, who were undergoing elective surgery were enrolled. PMNs, isolated preoperatively from each patient's venous blood, were perfused onto a tumor necrosis factor alpha-stimulated human umbilical vein endothelial cell (HUVEC) monolayer through the flow chamber. We evaluated the adherent PMN number, the migrated PMN number, and the stuck PMN number by directly inspecting PMN interactions with a HUVEC monolayer under continuous shear flow simulating postcapillary venules. The expression of adhesion molecules on circulating PMNs was also measured. Patients were grouped into an infectious and a noninfectious group according to the occurrence of postoperative infectious complications defined by the Centers for Disease Control criteria. Eleven patients developed postoperative infectious complications. Although the number of preoperative in vitro adherent PMNs in patients with postoperative infection was significantly higher than in those without postoperative infection (P = 0.01), migrated PMN number was similar in both groups. Stuck PMN number tended to be higher in the infectious group than in the noninfectious group. The migrated PMN number showed a significant positive correlation with the adherent PMN number in the noninfectious group but not in the infectious group. Preoperative CD31 expression on circulating PMNs was significantly lower in the infectious group than in the noninfectious group. Preoperative in vitro derangement of the PMN adhesion-migration process is closely associated with postoperative infectious complications.
Antibiotic therapy is an essential treatment for gram-negative bacterial infections. Antibiotic-induced endotoxin release and subsequent production of inflammatory cytokines reportedly depend on the type of antibiotic action. This study examined the effects of various beta-lactam antibiotics on cell death of human polymorphonuclear neutrophils (PMNs) cocultured with Escherichia coli (E. coli) in vitro. E. coli morphology after antibiotic treatment was determined. PMNs and E. coli were cocultured with antibiotics for 0, 4, or 12 h. Levels of endotoxin and cytokines (TNF-alpha, IL-1beta, and IL-6) in the supernatants were measured. The filtrates of antibiotic-treated E. coli supernatants were cocultured with PMNs for 0, 4, or 12 h. In all experiments, ampicillin (ABPC), cefazolin sodium (CEZ), cefoperazone sodium (CPZ), latamoxef sodium (LMOX), imipenem (IPM), and polymyxin B sulfate (PLB) were used at 30 microg/mL. PMNs were isolated from healthy volunteers. PMN cell death was assessed by flow cytometry and light microscopy. ABPC, CEZ, CPZ, and LMOX, which induce bacterial filament formation with lysis, caused PMN necrosis when cocultured with E. coli. In contrast, IPM, which induces bacterial spheroplast formation with lysis, caused PMN apoptosis. Levels of endotoxin, TNF-alpha and IL-6 in the supernatants with IPM and PLB were significantly lower than in those with other beta-lactam antibiotics. The filtrates of IPM- and PLB-treated E. coli supernatants induced PMN apoptosis, whereas those treated with other beta-lactam antibiotics increased PMN necrosis. Beta-lactam antibiotics have different impacts on the types of PMN cell death after E. coli killing. Underlying mechanisms and the clinical relevance of IPM-induced PMN apoptosis in severe gram-negative infection warrant further investigation.
The first unequivocal circular dichroism spectra were obtained for organic radical cations, which were prepared from p-(1S,2S,5R)-neomenthyloxyanisole (1) and p-(1S,2S,4S)-isobornyloxyanisole (2) by single electron oxidation with triethyloxonium hexachloroantimonate in dichloromethane. The chiroptical properties of the radical cations 1*+ and 2*+ were discussed in comparison with those of neutral species 1 and 2.
BACKGROUND: Phosphorylation of extracellular signal-regulated kinase (ERK) enhances various inflammatory responses in immune cells. It is unknown whether dysfunction of immune cells during malnutrition is attributed to derangement of ERK activation. METHODS: Male Institute of Cancer Research (ICR) mice received chow (146 g/kg per day, ad libitum or 36.5 g/kg per day, diet-restricted) for 7 days. Mice (n = 55) were given 6.5 mg/kg of an ERK inhibitor (PD98059) or vehicle intraperitoneally (IP), at 2 hours before cecal ligation and puncture (CLP). Survival was observed up to 60 hours. Detection of phosphorylated ERK (pERK) in the peritoneal exudative cells (PECs) was done as follows. In a separate study, PECs were harvested by peritoneal lavage 2 hours after an IP injection of 1% glycogen. PECs were incubated with or without 100 nmol/L N-formyl-methionyl-leucyl-phenylalanine (fMLP) for 1 minute. PEC ERK activation was detected with Western blot analysis (n = 38), by densitometric quantification, and with a laser scanning cytometer (LSC; n = 13). Subpopulations of PECs were determined by Wright-Giemsa staining. Unstimulated pERK expression was normalized to 100% for Western blot analysis. RESULTS: Diet restriction reduced survival after CLP compared with the ad libitum mice. ERK inhibition showed no effect on survival in diet-restricted mice but reduced survival in ad libitum mice. There were no differences in subpopulations of PECs 2 hours after glycogen injection between the groups. Western blot analysis revealed that fMLP stimulation significantly increased the phosphorylation of ERK1/2 in PECs from the ad libitum group (ERK1, 199 +/- 41%; ERK2, 211 +/- 49%; p < .03) but not in those from diet-restricted mice (ERK1, 98 +/- 10%; ERK2, 91 +/- 9%). Mean fluorescence intensity (MFI) of pERK in PECs obtained by LSC was significantly elevated after fMLP in the ad libitum group (from 19.4 +/- 1.5 MFI to 22.4 +/- 1.2 MFI; p < .05) but did not change in the diet-restricted group (from 19.4 +/- 1.8 MFI to 19.1 +/- 1.5 MFI). CONCLUSIONS: ERK activation is essential for survival in this murine sepsis model. Impaired ERK activation of PECs may, at least in part, impair host defense during malnutrition.
BACKGROUND: Malnutrition impairs host immunity, resulting in high mortality and morbidity, secondary to infections. Nuclear factor kappaB (NFkappaB) plays a critical role in host defense, but how quickly refeeding normalizes the impaired NFkappaB activity in peritoneal resident cells (PRCs) is unknown. Our aim was to investigate the effects of 1-day ad libitum refeeding on severe diet restriction-induced NFkappaB activity in PRCs. METHODS: Mice received chow, 146 g/kg per day (ad libitum) or 36.5 g/kg per day (severe diet restriction), for 7 days. One-half the mice in the diet-restricted group were then fed ad libitum for 1 day (refeeding). PRCs were harvested by peritoneal lavage. After incubation with tumor necrosis factor-alpha (TNF-alpha), nuclear translocation of NFkappaB in PRCs was investigated using laser scanning cytometry. RESULTS: The main subpopulation of PRCs was macrophages in all groups. Mean fluorescence intensity over the nuclear area at 0 or 100 ng/mL of TNF-alpha was 16 +/- 2 or 31 +/- 8* in the ad libitum, 20 +/- 4 or 19 +/- 3 in the severe diet-restricted, and 20 +/- 4 or 30 +/- 5* in the refeeding group, respectively (*p < .05 versus 0 ng/mL of TNF-alpha in each group versus 100 ng/mL of TNF-alpha in diet-restricted group). Cytoplasmic accumulation of NFkappaB was significantly increased after TNF-alpha stimulation in the refed group but not in the ad libitum group. CONCLUSIONS: The blunted NFkappaB activity in PRCs, after exposure to inflammatory stimuli, was restored after 1 day of refeeding, with increased accumulation of NFkappaB in the cytoplasm. Even brief nutritional replenishment in malnutrition may improve host defense by restoring NFkappaB activity and thereby improving macrophage functions.
On photooxygenation of the optically active Z/E enecarbamates 1 (X = i-Pr) and 2 (X = Me) equipped with the oxazolidinone chiral auxiliary in methylene-blue (MB)-incorporated, alkali-metal (M = Li, Na, K, Cs, Rb), exchanged Y-type zeolites (MY-MB), oxidative cleavage of the alkenyl functionality releases the enantiomerically enriched methyldesoxybenzoin (MDB) product. The extent (%ee) and/or the sense (R or S) of the stereoselectivity in the formation of the MDB product depends on the choice of the alkyl substiuent (i-Pr or Me) at the C-4 position of the oxazolidinone chiral auxiliary, the Z/E configuration of the alkene functionality in the enecarbamates, and the type of alkali metal in the zeolite. Most significantly-the highlight of this study-is the reversed sense (R or S) in the stereoselection when the photooxygenation is run in CDCl3 solution versus inside the MY-MB zeolite. As a mechanistic rationale for this novel stereochemical behavior, we propose the combined action of spatial confinement and metal-ion coordination (assessed by density-functional calculations) of the substrate within the zeolite supercage, both of which greatly reduce the freedom of the substrate and entropically manipulate the stereochemical outcome.