Experimental Studies on Protective Effects of FK506 Against Hepatic Ischemia-Reperfusion Injury.

Purposes; FK506 (strong immunosuppressive agent) was investigated experimentally whether to protect the hepatic IRI. Methods; Warm ischemic experiment using pigs and rats were performed and examined whether FK506 is effective. Results; The results obtained are as follows. 1. Warm ischemia allowed time of the pigs without FK506 was 150 minutes, but as for that of FK506 group, the extension of 30 minutes was got in 180 minutes. 2. Biliary excretion rate of BSP after reperfusion were better in the group of 180 minutes ischemia with FK506 than in without FK506 group. 3. Chemiluminescence intensity in the peripheral neutrophils and adhered and infiltrated leukocytes in the liver were suppressed markedly by FK506. 4. The vascular endothelium with the scanning electron microscope was relatively preserved in the FK506 group comparing to the placebo group on 30 minutes after reperfusion. 5. Stress gastric ulcer was controlled and myeloperoxidase activity in the gastric mucosa was suppressed by FK506. Conclusion; Based on the results of theses experiments, it was suggested that FK506 has a protective effect on IRI by suppressing: the impairment of sinusoidal endothelial cells; the activation of KCs; the disturbance of micro-circulation; oxidative stress; inflammation; and the accumulation of leukocytes. J. Med. Invest. 63: 262-269, August, 2016.

Analysis of solute-solvent interactions in the fragment molecular orbital method interfaced with effective fragment potentials: theory and application to a solvated griffithsin-carbohydrate complex.

Based on the proposed new expression of the polarization energy for the fragment molecular orbital (FMO) method interfaced with effective fragment potentials (EFPs), we develop an analysis of the solute(FMO)-solvent(EFP) interactions by defining individual fragment contributions for both solute and solvent. The obtained components are compared to all-electron calculations where water is treated as FMO fragments in the pair interaction energy decomposition analysis. The new energy expression is shown to be accurate, and the developed energy analysis is applied to the solvated griffithsin-carbohydrate complex. The details of the ligand recognition are revealed in the context with their interplay with the solvent effects. Tyr residue fragments are shown to reduce the desolvation penalty for Asp, which strongly binds the ligand.

A combined effective fragment potential-fragment molecular orbital method. II. Analytic gradient and application to the geometry optimization of solvated tetraglycine and chignolin.

The gradient for the fragment molecular orbital (FMO) method interfaced with effective fragment potentials (EFP), denoted by FMO∕EFP, was developed and applied to polypeptides solvated in water. The structures of neutral and zwitterionic tetraglycine immersed in water layers of 2.0, 2.5, 3.0, 3.5, 4.0, and 4.5 Å are investigated by performing FMO∕EFP geometry optimizations at the RHF∕cc-pVDZ level of theory for the solutes. The geometries optimized with FMO-RHF∕EFP are compared to those from the conventional RHF∕EFP and are found to be in very close agreement. Using the optimized geometries, the stability of the hydrated zwitterionic and neutral structures is discussed structurally and in terms of energetics at the second-order Møller-Plesset theory (MP2)∕cc-pVDZ level. To demonstrate the potential of the method for proteins, the geometry of hydrated chignolin (protein data bank ID: 1UAO) was optimized, and the importance of the inclusion of water was examined by comparing the solvated and gas phase structures of chignolin with the experimental NMR structure.

Role of the key mutation in the selective binding of avian and human influenza hemagglutinin to sialosides revealed by quantum-mechanical calculations.

The selective binding between avian and human influenza A viral hemagglutinins (HA) subtype H3 and Neu5Acα2-3 and α2-6Gal (avian α2-3, human α2-6) is qualitatively rationalized by the fragment molecular orbital (FMO) method. We suggest a general model of analyzing protein-ligand interactions based on the electrostatic, polarization, dispersion, and desolvation components obtained from quantum-mechanical calculations at the MP2/6-31G(d) level with the polarizable continuum model of solvation. The favorable avian H3 (A/duck/Ukraine/1963)-avian α2-3 binding arises from the hydrophilic interaction between Gal-4 OH and side-chain NH(2)CO on Gln226, which is supported by the intermolecular hydrogen-bond network to the 1-COO group on Neu5Ac moiety. A substitution of Gln226Leu in the avian H3 HA1 domain increases the binding affinity to human α2-6 due to the Leu226···human α2-6 dispersion with a small entropic penalty during the complex formation. The remarkable human H3 (A/Aichi/2/1968)-human α2-6 binding is not governed by the Ser228-OH···OH-9 Neu5Ac hydrogen bond. These fragment-based chemical aspects can help design monovalent inhibitors of the influenza viral HA-sialoside binding and the simulation studies on the viral HAs-human α2-6 binding.

Binding of influenza A virus hemagglutinin to the sialoside receptor is not controlled by the homotropic allosteric effect.

Several sialoside receptors can bind to three active sites on influenza A viral hemagglutinin (HA), determining the mechanism of the virus and host cell binding. Optimization of complex structures at the molecular mechanics level shows an insignificant conformational change of HA between the isolated state and the complex with three sialosides. The energetic analysis of the HA (X-31, Aichi/2/1968)-sialoside complexes performed with quantum-mechanical calculations of the complex containing about 24 000 atoms at the FMO2-MP2/PCM/6-31G(d) level suggests that the binding of one, two, or three receptors has the same binding energy per sialoside, thus the trivalent HA-sialoside binding is not regulated by the sialoside homotropic allosteric effect. These results rationalize the experimentally reported simple binding mode for the trivalent HA-monovalent sialoside interaction in solution at equilibrium.

Highly fucosylated N-glycan ligands for mannan-binding protein expressed specifically on CD26 (DPPVI) isolated from a human colorectal carcinoma cell line, SW1116.

The serum mannan-binding protein (MBP) is a host defense C-type lectin specific for mannose, N-acetylglucosamine, and fucose residues, and exhibits growth inhibitory activity toward human colorectal carcinoma cells. The MBP-ligand oligosaccharides (MLO) isolated from a human colorectal carcinoma cell line, SW1116, are large, multiantennary N-glycans with highly fucosylated polylactosamine-type structures having Le(b)-Le(a) or tandem repeats of the Le(a) structure at their nonreducing ends. In this study, we isolated the major MBP-ligand glycoproteins from SW1116 cell lysates with an MBP column and identified them as CD26/dipeptidyl peptidase IV (DPPIV) (110 kDa) and CD98 heavy chain (CD98hc)/4F2hc (82 kDa). Glycosidase digestion revealed that CD26 contained such complex-type N-glycans that appear to mediate the MBP binding. MALDI-MS of the N-glycans released from CD26 by PNGase F demonstrated conclusively that CD26 is the major MLO-carrying protein. More interestingly, a comparison of the N-glycans released from the MBP-binding and non-MBP-binding glycopeptides suggested that complex-type N-glycans carrying a minimum of 4 Le(a)/Le(b) epitopes arranged either as multimeric tandem repeats or terminal epitopes on multiantennary structures are critically important for the high affinity binding to MBP. Analysis of the N-glycan attachment sites demonstrated that the high affinity MLO was expressed preferentially at some N-glycosylation sites, but this site preference was not so stringent. Finally, hypothetical 3D models of tandem repeats of the Le(a) epitope and the MBP-Lewis oligosaccharide complex were presented.

Ab initio fragment molecular orbital studies of influenza virus hemagglutinin-sialosaccharide complexes toward chemical clarification about the virus host range determination.

If we predict the host range of new or mutant influenza virus in advance, we are able to measure against pandemic human influenza immediately after the new virus emerges somewhere. Influenza viral hemagglutinin(HA)-sialoside receptor interaction is a target event for in silico chemical prediction studies about the virus host range determination. We theoretically studied avian and human influenza A virus HA H3 subtype complexed with avian or human type receptor Neu5Acalpha(2-3 or 2-6)Gal analogues by ab initio fragment molecular orbital (FMO) method at the second order Møller-Plesset (MP2)/6-31G level, which can evaluate correctly not only electrostatic interactions but also lipophilic interactions based on van der Waals dispersion force. Avian H3 bound to avian alpha2-3 11.4 kcal/mol stronger than to human alpha2-6 in the model complexes with taking account of intermolecular lipophilic interaction. A substitution at the position 226 between Gln(avian) and Leu(human) on influenza H3 HA1 has altered its virus host range between avian and human. In the ab initio FMO studies, binding energy of avian Gln226Leu H3-human alpha2-6 was quite similar to that in the human H3-human alpha2-6 complex with amino acid sequence differences at nine positions in the models. This similarity indicates that avian Gln226Leu H3 virus can infect human with the same level as human H3 virus. Opposite mutation Leu226Gln in the human H3 gave the moderate binding energies to avian alpha2-3 with similarity to avian H3-alpha2-3 complex that supported our previous virus-sialoside binding assay. Ab initio FMO studies have revealed the relationship between influenza H3 virus host range and H3-alpha(2-3 or 2-6) receptors binding. Our theoretical approach may predict the infectious level of new viruses and point out some unknown dangerous mutation positions on HA in advance.

In vitro inhibition of human influenza A virus infection by fruit-juice concentrate of Japanese plum (Prunus mume SIEB. et ZUCC).

Using a plaque reduction assay, treatment of human influenza A viruses with the fruit-juice concentrate of Japanese plum (Prunus mume SIEB. et ZUCC) showed strong in vitro anti-influenza activity against human influenza A viruses before viral adsorption, but not after viral adsorption, with 50% inhibitory concentration (IC50) values against A/PR/8/34 (H1N1) virus, A/Aichi/2/68 (H3N2) virus and A/Memphis/1/71 (H3N2) virus of 6.35+/-0.17, 2.84+/-1.98 and 0.53+/-0.10 microg/ml, respectively. The plum-juice concentrate exhibited hemagglutination activity toward guinea pig erythrocytes. Its hemagglutination activity was inhibited by the monosaccharide N-acetylneuraminic acid and a sialoglycoprotein (fetuin), but not by the other tested monosaccharides (mannose, galactose, glucose and N-acetylglucosamine), suggesting the presence of a lectin-like molecule(s) in the Japanese plum-juice concentrate. Our findings suggest that the fruit-juice concentrate of Japanese plum may prevent and reduce infection with human influenza A virus, possibly via inhibition of viral hemagglutinin attachment to host cell surfaces by its lectin-like activity.

Ab initio base fragment molecular orbital studies of influenza viral hemagglutinin HA1 full-domains in complex with sialoside receptors.

Mutations in avian influenza A viral hemagglutinin HA1 domain may alter the binding specificity of HA for alpha-sialosaccharide receptors, shifting the virus's host range from birds to humans. The amino acid mutations can occur at the sialoside binding site, as well as the antigenic site, far from the binding site. Thus, a theoretical study involving the in silico prediction of HA-sialosaccharide binding may require quantum chemical analysis of HA1 full domain complexed with sialosides, balancing a computational cost with model size of HA1-sialoside complex. In addition, there is no insight to relationship between the model size of HA1-sialoside complex and its binding energy. In this study, H3 subtype HA1 full domains complexed with avian- and human-type Neu5Acalpha(2-3 and 2-6)Gal receptor analogs was investigated by ab initio based fragment molecular orbital (FMO) method at the level of second-order Møller-Plesset perturbation (MP2)/6-31G. Using this approach, we found avian H3 HA1 to bind to avian alpha2-3 receptor more strongly than to human alpha2-6 receptor in gas phase, by a value of 15.3-16.5 kcal/mol. This binding benefit was larger than that in the small model complex. Analysis of the interfragment interaction energies (IFIEs) between Neu5Ac-Gal receptor and amino acid residues on the full domain of H3 HA1 also confirmed the higher avian H3-avian alpha2-3 binding specificity. It was particularly important to evaluate the IFIEs of amino acid residues in a 13A radius around Neu5Ac-Gal to take account of long-range electrostatic interactions in the larger HA1-sialoside complex model. These results suggest suitable size of HA1-sialoside complex is significant to estimate HA1-sialoside binding energy and IFIE analysis with FMO method.

Synthetic glycan ligand excludes CD22 from antigen receptor-containing lipid rafts.

CD22/Siglec-2 is a B cell membrane-bound lectin that recognizes glycan ligands containing alpha2,6-linked sialic acid, and negatively regulates signaling through the B cell antigen receptor (BCR). Previous studies demonstrated that synthetic sialosides that bind to CD22 augment BCR signaling by inhibiting CD22-mediated BCR regulation. Here we demonstrate that, after antigen stimulation, CD22 forms a cap together with BCR, and translocates to lipid rafts. Both co-capping of CD22 with BCR and translocation of CD22 to lipid rafts were markedly blocked by a synthetic alpha2,6-linked sialic acid, Neu5Gcalpha2-6GalbetaSE. These results strongly suggest that synthetic glycan ligand excludes CD22 from BCR-containing lipid rafts. Because CD22-mediated signal regulation requires phosphorylation of CD22 by Lyn that localizes in lipid rafts and is activated by BCR, synthetic glycan ligand regulates localization of CD22 crucial for signal regulation.

Influenza viral hemagglutinin complicated shape is advantageous to its binding affinity for sialosaccharide receptor.

Do the complexity and the bulkiness of a protein affect the affinity between protein and ligand? We attempted to investigate this problem by using ab initio fragment molecular orbital (FMO) method to calculate the binding energy between human influenza viral hemagglutinin (HA) and human oligo-saccharide receptor. We compared the binding energies of 4 different sizes of human A virus HA H3 subtype complexed with human receptor Neu5Ac(alpha2-6)Gal as a model. The full shape receptor binding domain complexed with Neu5Ac(alpha2-6)Gal had the highest binding energy 170.3kcal/mol at the FMO-HF/STO-3G level, which was 52.3kcal/mol higher than that of the smallest domain-receptor complex. These data provide the consideration of the backyard bulkiness beyond the binding site of protein to the protein-ligand stability.

Haemagglutinin mutations responsible for the binding of H5N1 influenza A viruses to human-type receptors.

H5N1 influenza A viruses have spread to numerous countries in Asia, Europe and Africa, infecting not only large numbers of poultry, but also an increasing number of humans, often with lethal effects. Human and avian influenza A viruses differ in their recognition of host cell receptors: the former preferentially recognize receptors with saccharides terminating in sialic acid-alpha2,6-galactose (SAalpha2,6Gal), whereas the latter prefer those ending in SAalpha2,3Gal (refs 3-6). A conversion from SAalpha2,3Gal to SAalpha2,6Gal recognition is thought to be one of the changes that must occur before avian influenza viruses can replicate efficiently in humans and acquire the potential to cause a pandemic. By identifying mutations in the receptor-binding haemagglutinin (HA) molecule that would enable avian H5N1 viruses to recognize human-type host cell receptors, it may be possible to predict (and thus to increase preparedness for) the emergence of pandemic viruses. Here we show that some H5N1 viruses isolated from humans can bind to both human and avian receptors, in contrast to those isolated from chickens and ducks, which recognize the avian receptors exclusively. Mutations at positions 182 and 192 independently convert the HAs of H5N1 viruses known to recognize the avian receptor to ones that recognize the human receptor. Analysis of the crystal structure of the HA from an H5N1 virus used in our genetic experiments shows that the locations of these amino acids in the HA molecule are compatible with an effect on receptor binding. The amino acid changes that we identify might serve as molecular markers for assessing the pandemic potential of H5N1 field isolates.

Why does avian influenza A virus hemagglutinin bind to avian receptor stronger than to human receptor? Ab initio fragment molecular orbital studies.

Influenza A viruses attach to alpha-sialosides on the target cell surface by their hemagglutinins, which strictly recognize the difference in sialic acid-galactose linkage. Why does avian virus H3 subtype bind to avian receptor Neu5Ac(alpha2-3)Gal stronger than to human receptor Neu5Ac(alpha2-6)Gal? Why does avian H3 mutated Gln226 to Leu preferentially bind to human receptor? In this paper, we theoretically answer the questions by molecular mechanics and ab initio fragment molecular orbital (FMO) calculations. The binding energy between avian H3 and avian receptor is 8.2kcal/mol larger than that of the avian H3-human receptor complex estimated at the FMO-HF/STO-3G level, which is a reason that avian H3 binds to avian receptor stronger than to human receptor. Avian Leu226 H3 clashes to Gal unit on the avian receptor to quite decrease its binding affinity. In contrast, Gal unit on the human receptor forms intermolecular hydrophobic interaction with avian Leu226 H3 to afford moderate binding affinity.

[Long-term survival in a case of large bowel cancer--efficacy of CPT-11-based chemotherapy].

A 77-year-old woman underwent an ileocecal resection and a partial resection of the small intestine for cecal cancer. However, ileus caused by a recurrence in the small intestine was detected two years and four months postoperatively, so an ileal resection was performed. Furthermore, metastases to the lungs, lymph nodes, and peritoneum were detected, and CPT-11-based chemotherapy was administered. The patient was initially treated by combination therapy with a small dose of CPT-11 and CDDP. The combination drugs were changed to MMC, 5'-DFUR, etc. while the appearance of adverse reactions was monitored. Three years of continuous treatment served to prevent the proliferation of tumors. At present, TS-1 chemotherapy is ongoing. The results suggest that CPT-11-based chemotherapy can be continued by changing the combination of concomitant drugs while monitoring adverse reactions. It thus may be an effective regimen for advanced and recurrent large bowel cancer.

Synthesis of sulfated phenyl 2-acetamido-2-deoxy-D-galactopyranosides. 4-O-Sulfated phenyl 2-acetamido-2-deoxy-beta-D-galactopyranoside is a competitive acceptor that decreases sulfation of chondroitin sulfate by N-acetylgalactosamine 4-sulfate 6-O-sulfotransferase.

We have previously cloned N-acetylgalactosamine 4-sulfate 6-O-sulfotransferase (GalNAc4S-6ST), which transfers sulfate from 3'-phosphoadenosine 5'-phosphosulfate (PAPS) to the C-6 hydroxyl group of the GalNAc 4-sulfate residue of chondroitin sulfate A and forms chondroitin sulfate E containing GlcA-GalNAc(4,6-SO(4)) repeating units. To investigate the function of chondroitin sulfate E, the development of specific inhibitors of GalNAc4S-6ST is important. Because GalNAc4S-6ST requires a sulfate group attached to the C-4 hydroxyl group of the GalNAc residue as the acceptor, the sulfated GalNAc residue is expected to interact with GalNAc4S-6ST and affect its activity. In this study, we synthesized phenyl alpha- or -beta-2-acetamido-2-deoxy-beta-D-galactopyranosides containing a sulfate group at the C-3, C-4, or C-6 hydroxyl groups and examined their inhibitory activity against recombinant GalNAc4S-6ST. We found that phenyl beta-GalNAc(4SO(4)) inhibits GalNAc4S-6ST competitively and also serves as an acceptor. The sulfated product derived from phenyl beta-GalNAc(4SO(4)) was identical to phenyl beta-GalNAc(4,6-SO(4)). These observations indicate that derivatives of beta-D-GalNAc(4SO(4)) are possible specific inhibitors of GalNAc4S-6ST.

Mouse N-acetylgalactosamine 4-sulfotransferases-1 and -2. Molecular cloning, expression, chromosomal mapping and detection of their activity with GalNAcbeta1-4GlcNAcbeta1-octyl.

N-Acetylgalactosamine 4-sulfotransferase (GalNAc4ST) transfers sulfate to position 4 of nonreducing terminal GalNAc residues. We previously cloned human GalNAc4ST-1 cDNA. In this paper, we report the cloning, characterization and chromosomal mapping of mouse GalNAc4ST-1 and GalNAc4ST-2. Mouse GalNAc4ST-1 and GalNAc4ST-2 contain single open reading frames that predict type II transmembrane proteins composed of 417 and 413 amino acid residues, respectively. The amino acid sequence identity between the two isoforms is 49%. When the cDNA was transfected to COS-7 cells, sulfotransferase activities toward carbonic anhydrase VI and GalNAcbeta1-4GlcNAcbeta1-octyl were overexpressed, but the sulfotransferase activity toward chondroitin showed no increase over the control level. Northern blot analysis showed that the 2.4 kb messages of GalNAc4ST-1 and GalNAc4ST-2 were strongly expressed in the kidney, where both of the human isoforms were hardly expressed. Reverse transcription-PCR analysis showed that, unlike human GalNAc4ST-1, the expression of mouse GalNAc4ST-1 in the pituitary gland was only marginal, while that of GalNAc4ST-2 in the pituitary gland was as high as that in the kidney. These results suggest that the functions of the two GalNAc4ST isoforms may differ between human and mouse. By fluorescence in situ hybridization, the GalNAc4ST-1 and GalNAc4ST-2 genes were localized to mouse chromosome 7B3 distal-B5 proximal and chromosome 18A2 distal-B1 proximal, respectively.