Generation of Dopamine Transporter (DAT)-mCherry Knock-in Rats by CRISPR-Cas9 Genome Editing

Midbrain dopaminergic neurons respond to rewards and have a crucial role in positive motivation and pleasure. Electrical stimulation of dopaminergic neurons and/or their axonal fibers and arborization has been often used to motivate animals to perform cognitive tasks. Still, the electrical stimulation is incompatible with electrophysiological recordings. In this light, optical stimulation following artificial expression of channelrhodopsin-2 (ChR2) in the cell membrane has been also used, but the expression level of ChR2 varies among researchers. Thus, we attempted to stably express ChR2 fused with a red fluorescence protein, mCherry, in dopaminergic neurons. Since dopamine transporter (DAT) gene is known as a marker for dopaminergic neurons, we inserted ChR2-mCherry into the downstream of the DAT gene locus of the rat genome by clustered regularly interspaced short palindromic repeats (CRISPR)-associated protein 9 (CRISPR-Cas9) genome editing and created DAT-ChR2-mCherry knock-in rats. Immunohistochemistry showed that ChR2-mCherry was expressed in dopaminergic neurons in homozygote knock-in rats, whereas whole-cell recordings revealed that ChR2-mCherry-positive neurons did not fire action potentials upon blue light stimulation, indicating that ChR2 was not functional for optogenetics. Nevertheless, fluorescent labeling of dopaminergic neurons mediated by mCherry could help characterize them physiologically and histologically.

The effect of risperidone on D-amino acid oxidase activity as a hypothesis for a novel mechanism of action in the treatment of schizophrenia

D-Amino acid oxidase (DAO) has been established to be involved in the oxidation of D-serine, an allosteric activator of the N-methyl-D-aspartate-type glutamate receptor in the brain, and to be associated with the onset of schizophrenia. The effect of risperidone, a benzisoxazole derivative, atypical antischizophrenic drug, on the activity of human DAO was tested using an in-vitro oxygraph system and rat C6, stable C6 transformant cells overexpressing mouse DAO (designated as C6/DAO) and pig kidney epithelial cells (LLC-PK(1)). Risperidone has a hyperbolic mixed-type inhibition, designated as 'partial uncompetitive inhibition effect', with K(i) value of 41 microM on human DAO. Risperidone exhibited a protective effect from D-amino acid induced cell death in both C6/DAO and LLC-PK(1) cells with 10% increase in viability. These data indicate the involvement of DAO activity in D-serine metabolism and also suggest a new mechanism of action to risperidone as antischizophrenic drug.

A delayed response to acute stimulation with human chorionic gonadotropin in scorbutic rats

Since our previous study revealed low basal testosterone (T) levels and a failure in response to an acute stimulation with human chorionic gonadotropin (HCG) despite of a good response to chronic stimulation in scorbutic mutant rats, time course of the response to HCG was studied and plasma LH level was measured in young adult rats deficient in ascorbic acid for 3 weeks. A single subcutaneous injection of HCG (200 IU) elevated T levels only slightly in plasma and not in testicular tissues of scorbutic rats 1 h after the injection when the levels in ascorbutic rats reached a maximum, while it yielded the same response pattern as in ascorbutic rats after 3 h. A pretreatment with HCG to scorbutic rats for 1 or 4 days resulted in the same response of plasma T as in ascorbutic rats. Plasma LH levels in unstimulated scorbutic rats were about 40% of those in ascorbutic rats. These findings indicate that a prolonged deficiency of ascorbic acid decreases plasma LH, and may reduce the sensitivity of testes to LH.

Changes in serum and red blood cell membrane lipids in patients treated with interferon ribavirin for chronic hepatitis C

One of the side effects by interferon ribavirin (I/R) treatment is haemolytic anemia, causing some patients to discontinue I/R treatment. The exact mechanism of I/R-induced anemia is unknown. The aim of this study is to evaluate the effects of I/R treatment on the serum lipid and red blood cell (RBC) membrane lipid profiles of patients with chronic hepatitis C (CHC) and the association between changes of RBC membrane lipids and haemolytic anemia by I/R treatment. Fourteen patients with CHC were treated with I/R and their serum lipid profiles were studied. In addition, in seven of the 14 patients, the RBC membrane lipid profiles were analysed. In the RBC membrane lipid composition, the total cholesterol, total phospholipids and cholesterol/phospholipids (C/PL) ratio were significantly increased. Phosphatidylcholine (PC) and the phosphatidylcholine/ sphingomyelin (PC/SM) ratio were significantly decreased and other phospholipid fractions were significantly increased. Changes in the serum lipids and RBC membrane lipid profiles of patients with CHC treated with I/R were shown. Especially, a decrease in the RBC deformability and membrane fluidity by changes in these RBC membrane lipids was supposed and it is suggested that those changes may result in haemolytic anemia by I/R treatment.

Long-term local hyperthermia in the treatment of advanced breast cancer (case report)

BACKGROUND

It is difficult to control non-resectable locally advanced primary and recurrent breast cancer by conventional modalities. Recently, hyperthermia (HT) has been recognized as an effective adjuvant to radiotherapy (RT) and chemotherapy (CT) in treatment of various malignancies, including breast cancer.

PATIENT AND METHODS

The patient was a 58-year-old female Japanese, with breast cancer, T4N2M0, stage IIIb (papillo-tubular carcinoma). Previous treatment included RT and neoadjuvant CT Local HT was performed with a total number of 87 sessions given over 12 months. The mean time of each session was 40 minutes. Elevation of temperature to a tumoricidal level of 43 degrees C was confirmed. The patient received cyclophosphamide (50 mg p.o./day) and tamoxifen (20 mg p.o./day) during the whole period of HT. Due to the decreased amount of WBC, further CT was not possible, except for one course of CMF performed 3 months after the start of HT.

RESULTS

The patient had a decrease in the intensity of pain even after the first 3 sessions. In one month, movement in the right shoulder became possible in an anterio-posterior direction. By 5 months, the healing of ulceration became evident. At present, the patient is in continuous CR for 15 months after HT. The movement in the shoulder joint is markedly improved in all directions. In addition, HT did not cause any notable complications.

CONCLUSION

Long-term HT may be useful in the management of locally advanced breast cancer and these results should encourage further clinical study.

Linearization and integration of DNA into cells preferentially occurs at intrinsically curved regions from human LINE-1 repetitive element

A bent DNA library was constructed from human genomic DNA, from which a new clone belonging to the human LINE-1 sequence family was isolated and characterized. This clone, with a length of 378 base pairs and termed HBC-1 (human bent clone-1), contained an intrinsically occurring curved DNA structure. By permutation analysis, the center of curvature of this fragment was mapped onto the nucleotide position 886 from the 5' terminus of the complete LINE-1 sequence. Reporter plasmids, which contain HBC-1, were effectively integrated into human chromosome, indicating that the bent DNA structure provides a preferential donor site for the integration of human LINE-1 sequences. The present finding may provide an explanation as to why some inactivated LINE-1 sequences on human chromosomes carry the deletion at their 5' termini.

[Hepatitis C in hemodialysis patients]

Characteristics of chronic hepatitis C in 99 hemodialysis patients were studied. Eleven out of 18 anti-HCV-positive patients(61.1%) and 13 out of 81 anti-HCV-negative patients (16.0%) were HCV-RNA-positive. Twenty four HCV-RNA-positive patients were divided into 2 groups according to anti-HCV-positivity. Seven out of 11 patients in anti-HCV-positive group and 1 out of 13 in anti-HCV-negative group were infected with more than 100 K copies/ml of HCV. A number of HCV-RNA copy was significantly larger in anti-HCV-positive group. Fourteen biopsies and necropsies in hemodialysis were achieved and the histological diagnosis did not correspond to clinical feature of chronic hepatitis C.

A common feature shared by bent DNA structures locating in the eukaryotic promoter region

Eukaryotic promoters often contain a bent DNA structure, suggesting that this structure plays some role in transcription. To reveal the role, we need more information on the promoters that contain or flank a bent DNA structure. In this study, we collected such promoters by the following approach: we first isolated human genomic DNA fragments that contained at least one bent DNA structure, then shotgun cloned them into a promoter trap vector, screened DNA fragments that functioned as a promoter, and finally found the promoters of interest by determining the bent DNA locus and the region expressing promoter activity. From 1,187 recombinant plasmids, we isolated 51 that showed promoter activity. Structural and functional analyses of randomly selected 10 clones with inserts of 548-913 bp demonstrated 11 sequences that could drive transcription. Unexpectedly, all of these clones met our purpose: i.e., each segment that showed a promoter activity (67-179 bp) was very close to the bent DNA structure (spanning about 150 bp in all clones), and in some cases overlapped it. More interestingly, these bent DNA structures all had a superhelical writhe. We propose a hypothesis that in the bent-DNA-containing eukaryotic promoters. bent DNA organizes local chromatin infrastructure appropriately for transcription initiation.

Structural basis of hematopoietic prostaglandin D synthase activity elucidated by site-directed mutagenesis

Hematopoietic prostaglandin (PG) D synthase (PGDS) is the first identified vertebrate ortholog in the Sigma class of the glutathione S-transferase (GST) family and catalyzes both isomerization of PGH(2) to PGD(2) and conjugation of glutathione to 1-chloro-2, 4-dinitrobenzene. We introduced site-directed mutations of Tyr(8), Arg(14), Trp(104), Lys(112), Tyr(152), Cys(156), Lys(198), and Leu(199), which are presumed to participate in catalysis or PGH(2) substrate binding based on the crystallographic structure. Mutants were analyzed in terms of structure, GST and PGDS activities, and activation of the glutathione thiol group. Of all the mutants, only Y8F, W104I, K112E, and L199F showed minor but substantial differences in their far-UV circular dichroism spectra from the wild-type enzyme. Y8F, R14K/E, and W104I were completely inactive. C156L/Y selectively lost only PGDS activity. K112E reduced GST activity slightly and PGDS activity markedly, whereas K198E caused a selective decrease in PGDS activity and K(m) for glutathione and PGH(2) in the PGDS reaction. No significant changes were observed in the catalytic activities of Y152F and L199F, although their K(m) for glutathione was increased. Using 5,5'-dithiobis(2-nitrobenzoic acid) as an SH-selective agent, we found that only Y8F and R14E/K did not accelerate the reactivity of the glutathione thiol group under the low reactivity condition of pH 5.0. These results indicate that Lys(112), Cys(156), and Lys(198) are involved in the binding of PGH(2); Trp(104) is critical for structural integrity of the catalytic center for GST and PGDS activities; and Tyr(8) and Arg(14) are essential for activation of the thiol group of glutathione.

Ocular and extraocular inflammation induced by immunization of tyrosinase related protein 1 and 2 in Lewis rats

Vogt-Koyanagi-Harada (VKH) disease is an ocular inflammatory disease and is considered to be a cell-mediated, autoimmune disease against melanocytes. To learn more about the mechanisms involved in VKH disease, the identification of the antigens specific to the disease and the development of an animal model are critically important. We have expressed and purified the melanocyte specific proteins, tyrosinase-related protein 1 (TRP1) and 2 (TRP2). Lewis rats developed an ocular and extraocular inflammatory disease 12 days after immunization with TRP1 or TRP2 that was characterized clinically by the infiltration of inflammatory cells and accumulation of massive fibrin in the anterior and posterior chambers of the eye. Histologically, inflammatory cells were found in the anterior and posterior chambers, iris, ciliary body, the choroid, subretinal space and vitreous body. In severe cases, a serous detachment of the retina was observed. In mild cases, focal inflammatory lesions surrounded by normal chorioretinal architecture were observed and the inflammation persisted for more than 42 days after the injection. Some eyes showed accumulation of epithelioid cells in the choroid or the retinal pigment epithelium which were similar to the Dalen-Fuchs nodules found in patients with VKH disease. The alterations of the photoreceptor outer segment and the outer nuclear layer were less severe than in experimental autoimmune uveitis induced by retinal antigens. Extraocular manifestations such as skin lesions and meningitis were also observed. The clinical course and histological findings in these rats resembled the changes in patients with VKH disease.

Crystal structure of rhodopsin: A G protein-coupled receptor

Heterotrimeric guanine nucleotide-binding protein (G protein)-coupled receptors (GPCRs) respond to a variety of different external stimuli and activate G proteins. GPCRs share many structural features, including a bundle of seven transmembrane alpha helices connected by six loops of varying lengths. We determined the structure of rhodopsin from diffraction data extending to 2.8 angstroms resolution. The highly organized structure in the extracellular region, including a conserved disulfide bridge, forms a basis for the arrangement of the seven-helix transmembrane motif. The ground-state chromophore, 11-cis-retinal, holds the transmembrane region of the protein in the inactive conformation. Interactions of the chromophore with a cluster of key residues determine the wavelength of the maximum absorption. Changes in these interactions among rhodopsins facilitate color discrimination. Identification of a set of residues that mediate interactions between the transmembrane helices and the cytoplasmic surface, where G-protein activation occurs, also suggests a possible structural change upon photoactivation.

Influence of highly curved DNA segments on in vivo topology of plasmids

Recombinant plasmids carrying a highly curved DNA structure are sometimes unstable in Escherichia coli. In order to know the underlying mechanism, several plasmids carrying one or two highly bent DNA segment(s) from the human adenovirus type 2 (Ad2) enhancer and/or origin region of phage lambda replication were systematically constructed and propagated in E. coli. The highly bent DNA segments disturbed the action of DNA topoisomerases: i.e. they were shown to be able to produce an anomalously wide spectrum of linking number topoisomers that tails toward lower supercoiling with a little of the DNA actually positively supercoiled. Furthermore, bent DNA caused multimeric plasmid formation. The linking number topoisomers and multimers seemed to be intermediate topological states of the bent DNA-containing plasmids that would lead to the deletion occurring in them. The nucleotide sequence of a deletion product of a bent DNA-containing plasmid showed that the putative source of the severe topological constraint was entirely eliminated from the plasmid.

Crystal structure of the RNA-dependent RNA polymerase of hepatitis C virus

BACKGROUND

Hepatitis C virus (HCV) is the major etiological agent of hepatocellular carcinoma, and HCV RNA-dependent RNA polymerase (RdRp) is one of the main potential targets for anti-HCV agents. HCV RdRp performs run-off copying replication in an RNA-selective manner for the template-primer duplex and the substrate, but the structural basis of this reaction mechanism has still to be elucidated.

RESULTS

The three-dimensional structure of HCV RdRp was determined by X-ray crystallography at 2.5 A resolution. The compact HCV RdRp structure resembles a right hand, but has more complicated fingers and thumb domains than those of the other known polymerases, with a novel alpha-helix-rich subdomain (alpha fingers) as an addition to the fingers domain. The other fingers subdomain (beta fingers) is folded in the same manner as the fingers domain of human immunodeficiency virus (HIV) reverse transcriptase (RT), another RNA-dependent polymerase. The ribose-recognition site of HCV RdRp is constructed of hydrophilic residues, unlike those of DNA polymerases. The C-terminal region of HCV RdRp occupies the putative RNA-duplex-binding cleft.

CONCLUSIONS

The structural basis of the RNA selectivity of HCV RdRp was elucidated from its crystal structure. The putative substrate-binding site with a shallow hydrophilic cavity should have ribonucleoside triphosphate (rNTP) as the preferred substrate. We propose that the unique alpha fingers might represent a common structural discriminator of the template-primer duplex that distinguishes between RNA and DNA during the replication of positive single-stranded RNA by viral RdRps. The C-terminal region might exert a regulatory function on the initiation and activity of HCV RdRp.

Effect of simvastatin on the lipid profile of hemodialysis patients

BACKGROUND

Simvastatin, a 3-hydroxy 3-methylglutaryl co-enzyme A (HMG-CoA) reductase inhibitor, is used widely for treatment of hypercholesterolemia. Simvastatin may be a suitable treatment for dyslipidemia in hemodialysis (HD) patients. However, investigation of the side-effects and safety of long-term administration of simvastatin to HD patients has been limited. In this study, we investigated the effects and safety of simvastatin and its effects on lipoprotein metabolism in hypercholesterolemic patients on HD.

METHODS

Simvastatin was administered at a dosage of 5 mg/day for 24 weeks to 38 HD patients with high serum total cholesterol (TC) levels (200 mg/dl) or low high-density lipoprotein cholesterol (HDL-C) levels (35 mg/dl). Every four weeks, serum lipids, apolipoprotein, lipoprotein (a) [Lp(a)] and malondialdehyde (MDA) levels were measured. In addition, lipid levels were determined in each lipoprotein fraction separated by ultracentrifugation.

RESULTS

After 24 weeks of simvastatin administration, TC significantly decreased by 25.7%, and low-density lipoprotein cholesterol (LDL-C) was significantly decreased by 33.6%. Triglyceride (TG) and HDL-C showed no significant changes. Apolipoprotein (apo) B significantly decreased by 24.5% and apo E by 30.0%. No significant changes were observed in the other apolipoproteins. MDA was also significantly decreased, whereas Lp(a) was not significantly altered. In the lipoprotein fractions, very LDL cholesterol (VLDL-C), intermediate-density lipoprotein cholesterol (IDL-C), LDL1 cholesterol (LDL1-C), and LDL2 cholesterol (LDL2-C) showed significant decreases. No particular side-effects were observed during the 12 months of simvastatin administration.

CONCLUSIONS

These results suggest that simvastatin appears to be safe and effective in HD patients with hypercholesterolemia.

[Detection of TT virus (TTV) in Japanese hemodialysis (HD) patients]

The clinical and epidemiological studies on TT virus (TTV) were achieved in 44 Japanese HD patients. TTV-DNA was detected in 29.5% of HD patients, and the percentage was higher than that reported in normal populations. HBsAg, anti-HBc, anti-HCV and HGV-RNA were positive in 6.8%, 36.4%, 22.7% and 2.3%, respectively. One of three HD patients with TTV had liver disorders. In comparison between TTV positive and negative groups, there were significant differences of anti-HBc and total cholesterol value.

cDNA cloning, expression, and mutagenesis study of liver-type prostaglandin F synthase

Prostaglandin (PG) F synthase catalyzes the reduction of PGD2 to 9alpha,11beta-PGF2 and that of PGH2 to PGF2alpha on the same molecule. PGF synthase has at least two isoforms, the lung-type enzyme (Km value of 120 microM for PGD2 (Watanabe, K., Yoshida, R., Shimizu, T., and Hayaishi, O. (1985) J. Biol. Chem. 260, 7035-7041) and the liver-type one (Km value of 10 microM for PGD2 (Chen, L. -Y., Watanabe, K., and Hayaishi, O. (1992) Arch. Biochem. Biophys. 296, 17-26)). The liver-type enzyme was presently found to consist of a 969-base pair open reading frame coding for a 323-amino acid polypeptide with a Mr of 36,742. Sequence analysis indicated that the bovine liver PGF synthase had 87, 79, 77, and 76% identity with the bovine lung PGF synthase and human liver dihydrodiol dehydrogenase (DD) isozymes DD1, DD2, and DD4, respectively. Moreover, the amino acid sequence of the liver-type PGF synthase was identical with that of bovine liver DD3. The liver-type PGF synthase was expressed in COS-7 cells, and its recombinant enzyme had almost the same properties as the native enzyme. Furthermore, to investigate the nature of catalysis and/or substrate binding of PGF synthase, we constructed and characterized various mutant enzymes as follows: R27E, R91Q, H170C, R223L, K225S, S301R, and N306Y. Although the reductase activities toward PGH2 and phenanthrenequinone (PQ) of almost all mutants were not inactivated, the Km values of R27E, R91Q, H170C, R223L, and N306Y for PGD2 were increased from 15 to 110, 145, 75, 180, and 100 microM, respectively, indicating that Arg27, Arg91, His170, Arg223, and Asn306 are essential to give a low Km value for PGD2 of the liver-type PGF synthase and that these amino acid residues serve in the binding of PGD2. Moreover, the R223L mutant among these seven mutants especially has a profound effect on kcat for PGD2 reduction. The Km values of R223L, K225S, and S301R for PQ were about 2-10-fold lower than the wild-type value, indicating that the amino acid residues at 223, 225 and 301 serve in the binding of PQ to the enzyme. On the other hand, the Km value of H170C for PGH2 was 8-fold lower than that of the wild type, indicating that the amino acid residue at 170 is related to the binding of PGH2 to the enzyme and that Cys170 confer high affinity for PGH2. Additionally, the 5-fold increase in kcat/Km value of the N306Y mutant for PGH2 compared with the wild-type value suggests that the amino acid at 306 plays an important role in catalytic efficiency for PGH2.

Comparative study of 5' UTR and NS3R primers for the detection of GB virus C/hepatitis G virus RNA in Japanese

AIMS/BACKGROUND

Many epidemiological studies of new hepatitis viruses, including GB virus C (GBV-C) and hepatitis G virus (HGV), have used polymerase chain reaction (PCR) primers designed for the third nonstructural region (NS3R). However, a homology study of GBV-C and HGV genomes revealed that the 5' untranslated region (5'UTR) was more conserved than NS3R.

METHODS

We attempted to detect GBV-C/HGV using PCR primers corresponding to the 5' UTR, and compared its incidence to that derived from NS3R primers. Furthermore, PCR products amplified using the 5' UTR primers were sequenced and subjected to phylogenetic analysis.

RESULTS

In patients with chronic hepatitis C, the prevalence of GBV-C/HGV by PCR with the NS3R and 5' UTR primers was 5.1% (4/78) and 17.9% (14/78), respectively, and in patients on hemodialysis, it was 0% (0/81) and 5.9% (5/85), respectively. We could not detect GBV-C/HGV in patients with non-A-C liver disease. The incidence of GBV-C/HGV by 5' UTR primers was higher than by NS3R primers. After DNA sequencing at 5' UTR, phylogenetic analysis showed two types of GBV-C/HGV, Jap and HGV types.

CONCLUSION

5' UTR primers proved highly sensitive for detection of GBV-C/HGV and were superior to the NS3R primers.

Crystal structure of annexin V with its ligand K-201 as a calcium channel activity inhibitor

The crystal structure of recombinant human annexin V complexed with K-201, an inhibitor of the calcium ion channel activity of annexin V, was solved at 3.0 A by molecular replacement including the apo and high-calcium forms. K-201 was bound at the hinge region cavity formed by the N-terminal strand and domains II, III and IV, at the side opposite the calcium and membrane-binding surface, in an L-shaped conformation. Based on the complex and other annexin structures, K-201 is proposed to restrain the hinge movement of annexin V in an allosteric manner, resulting in the inhibition of calcium movement across the annexin V molecule.

Cloning and crystal structure of hematopoietic prostaglandin D synthase

Hematopoietic prostaglandin (PG) D synthase is the key enzyme for production of the D and J series of prostanoids in the immune system and mast cells. We isolated a cDNA for the rat enzyme, crystallized the recombinant enzyme, and determined the three-dimensional structure of the enzyme complexed with glutathione at 2.3 A resolution. The enzyme is the first member of the sigma class glutathione S-transferase (GST) from vertebrates and possesses a prominent cleft as the active site, which is never seen among other members of the GST family. The unique 3-D architecture of the cleft leads to the putative substrate binding mode and its catalytic mechanism, responsible for the specific isomerization from PGH2 to PGD2.

Restoration of Leydig cells after repeated administration of ethane dimethanesulfonate in adult rats

Adult male rats were repeatedly treated with ethane dimethanesulfonate (EDS), an agent known to destroy Leydig cells selectively. Following a second injection, changes in serum testosterone levels and histological and morphometric changes of Leydig cells showed the time course to be similar to those after the first treatment. The number and volume of Leydig cells markedly decreased at day 2, began to increase from day 7, and recovered to the values of the control rats at day 30, concomitant with the changes of serum testosterone levels. Cells in the interstitial tissue labeled with bromodeoxyuridine markedly increased in number at day 2, gradually decreased thereafter, and returned to the values of the controls at day 14. During this period, cells undergoing mitosis were seen, their type unable to be determined, but were presumed to be regenerating Leydig cells. Even 30 days following four treatments with intervals of 30 days each, serum testosterone levels were the same as those in the controls. Also the numerical and volume densities of Leydig cells and the volume of an average Leydig cell were the same as those of the controls. Mitosis was observed in mature Leydig cells at this period, if any. It appears that new Leydig cells began to proliferate by division earlier than 14 days after EDS, allowing that there were several stages of proliferation, and that the source of reappearing Leydig cells may not be a limited number of precursor cells, implying the presence of stem cells for Leydig cells.

[Late phase reaction in atopic dermatitis--immunological parameters and immunohistological analysis]

We studied the correlation between late phase reaction (LPR) and laboratory data in atopic dermatitis (AD) and evaluated the pathological findings in LPR. We studied the correlation between LPR and the severity of AD, total IgE, specific IgE, total IgG4, specific IgG4 and eosinophils. There were correlations between immediate reaction (IR) and some laboratory data, but not between LPR and laboratory data. Pathological findings at 15 min 24 hrs and 48 hrs after dermal injection showed edema at 15 min, followed by epidermal eczematous changes in almost all cases at 24 hrs, edema and degeneration of dermal endothelial cells and surrounding connective tissue, and leukocytoclasia in half of the cases and deposition of C3 and IgG in parts. We found CD4+ cells in all layers of dermis, a greater ratio of EG2+ cells in deeper layers of dermis as time passed, and decrease of CD23+ cells after 24 hrs throughout the dermis. These changes were found in cases of IR-LPR+, too. It appears that the mechanism of LPR is complex and that IR is not indispensable, for LPR and that infiltration of CD4+ and EG2+ cells throughout all layers of dermis are important, and these condition were related to subsequent reactions.

Physiochemical characterization of ATP binding to human 5-lipoxygenase

Human 5-lipoxygenase requires ATP as a stimulatory factor. At the two preferred concentrations of the free Ca2+, 0.02 microM with a resting cell and 20 microM with a stimulated cell, Scatchard analysis revealed that 5-lipoxygenase has one affinity ATP binding site with a Kd of 4.6 microM at the low Ca2+ concentration but has two affinity ATP binding sites with a higher Kd of 4.4 microM and a lower Kd of 14.5 microM at the high Ca2+ concentration. In contrast, in a Tween 20 reaction system, 5-lipoxygenase had similar activation coefficients for ATP at both Ca2+ concentrations; these were 12.7 microM at the low Ca2+ concentration and 12.0 microM at the high Ca2+ concentration. These results showed that 5-lipoxygenase has an ATP binding site and suggest that self-association of 5-lipoxygenase in 20 microM Ca2+ may affect ATP binding affinity as measured by Scatchard analysis.

A novel series of orally active antiplatelet agents

A novel series of orally active fibrinogen receptor antagonists has been discovered through structural modification of our lead intravenous (iv) antiplatelet agent, 5-(4-amidinophenyl)pentanoyl-Asp-Phe 1 (SC-52012). The Asp-Phe amide bond was removed through truncation to a 3-substituted beta-amino acid aspartate mimetic which resulted in a tripeptide mimetic inhibitor of lower molecular weight (from 482 to the 330-390 g mol-1). The zwitterionic nature of the inhibitor was masked through the preparation of an ethyl ester prodrug. A lead compound from this series, 5-(4-amidinophenyl)pentanoyl-3-(3-pyridyl)propanoic acid 19a, was found to be a potent inhibitor of canine platelet aggregation in vitro (collagen, platelet rich plasma, PRP, IC50 = 270 nM). In further canine studies, oral administration of different ester pro-drugs of 19a at 10 mg kg-1 resulted in the following oral systemic activities: pivaloyloxymethyl ester derivative 19p (5.1 +/- 1.5% OSA), cyclohexyl ester derivative 19c (9.2 +/- 1.9% OSA), and ethyl ester derivative 19e (9.9 +/- 2.3% OSA).

Human 5-lipoxygenase associates with phosphatidylcholine liposomes and modulates LTA4 synthetase activity

A Ca2+ and a phosphatidylcholine (PC) as stimulatory factors to human 5-lipoxygenase (5-LO) were assessed to examine aspects of the regulatory mechanism of 5-LO. In the presence of Ca2+ (1 microM or less), PC liposomes distinctly stimulated the dual activities of 5-LO for the production of 5-HPETE from arachidonate and for its subsequent conversion to LTA4. At the same concentration of Ca2+, 5-LO was found to bind to PC liposomes. As with 5-LO activities, the binding was dependent on the range of Ca2+ concentration. The conversion ratios of 5-HPETE to LTA4 were dependent on PC liposome concentration and reached a maximum of 50% conversion. Among the four cell membrane lipids examined, PC liposomes demonstrated the highest conversion ratio of 5-HPETE to LTA4 by 5-LO. Most of the arachidonate added to the reaction mixture localized in PC liposomes. These results confirm that the intracellular increase of Ca2+ concentration causes 5-LO to associate with the cell membrane and perform an interfacial reaction. They also suggest that this binding of 5-LO to the cell membrane enhances the subsequent conversion from 5-HPETE to LTA4.

X-ray structure of a pokeweed antiviral protein, coded by a new genomic clone, at 0.23 nm resolution. A model structure provides a suitable electrostatic field for substrate binding

We have determined the crystal structure of alpha-pokeweed antiviral protein, a member of ribosome-inactivating proteins, at 0.23 nm resolution, by the molecular-replacement method. The crystals belong to the space group P2(1)2(1)2 with unit-cell dimensions a = 4.71, b = 11.63 and c = 4.96 nm, and contain one protein molecule/asymmetric unit based on a crystal volume/unit protein molecular mass of 2.1 x 10(-3) nm3/Da. The crystallographic residual value was reduced to 17.2% (0.6-0.23 nm resolution) with root-mean-square deviations in bond lengths of 1.9 pm and bond angles of 2.2 degrees. The C alpha-C alpha distance map shows that alpha-pokeweed antiviral protein is composed of three modules, the N-terminal (Ala1-Leu76), the central (Tyr77-Lys185) and the C-terminal (Tyr186-Thr266) modules. The substrate-binding site is formed as a cleft between the central and C-terminal modules and all the active residues exist on the central module. The electrostatic potential around the substrate-binding site shows that the central and C-terminal module sides of this cleft have a negatively and a positively charged region, respectively. This charge distribution in the protein seems to provide a suitable interaction with the substrate rRNA.

Improved crystals of the toxic protein MAP by protein engineering towards the host specificity

Mirabilis anti-viral protein (MAP) is a ribosome-inactivating protein from Mirabilis jalapa L. Since MAP is effective over a broad spectrum of species, the protein is difficult to express in heterologous hosts such as Escherichia coli. Recently, we obtained a MAP mutant, Y72F which exhibits a lower (1/100) activity against E. coli ribosomes while retaining almost full activity against mammalian cells [Habuka, Miyano, Kataoka, Tsuge & Noma (1992). J. Biol. Chem. 267, 7758-7760]. For the crystallographic studies, the Y72F MAP expression vector with an OmpA leading sequence was constructed and expressed in E. coli. The Y72F MAP mutant was then isolated and purified from the cell culture medium. Crystals were grown using the crystallization conditions for the native MAP crystals [Miyano et al. (1992). J. Mol. Biol. 226, 281-283]: 50% ammonium sulfate containing 50 mM ammonium citrate and 2 mM adenine sulfate, pH 5.4. The crystals belong to space group P3(1)21 (or P3(2)21) with a = b = 104.1 and c = 134.3 A. The crystals are isomorphous with the wild-type crystals but diffract to higher resolution. Imaging-plate photographs of the Y72F mutant showed sharp intense spots without the streaking observed in the native crystals.

Interfacial kinetic reaction of human 5-lipoxygenase

The kinetics of human 5-lipoxygenase were investigated in the presence of Tween 20 using a continuous spectrophotometric assay. Using the mixture at a constant molar ratio of arachidonate/Tween 20 at pH 8.0, the steady-state velocity on a varied arachidonate concentration did not follow simple Michaelis-Menten-type kinetics and double-reciprocal plot analysis gave hyperbolic curves. However, by introducing the concept of a local pH change, it was possible to analyze the kinetics as simple Michaelis-Menten type. The concept of a local pH change implies that when utilizing an acidic and amphiphilic substance as a substrate, such as arachidonate, the medium around the substrate is acidified with an increased concentration of substrate. This concept was explained rationally by two experiments. Consequently, the data were transformed according to a local pH change and analyzed according to a dual phospholipid model as has been proposed for phospholipase A2 [Hendrickson, H. S. and Dennis, E. A. (1984) Kinetic analysis of the dual phospholipid model for phosphalipase A2, J. Biol. Chem. 259, 5734-5739]. It is concluded that 5-lipoxygenase performs an interfacial reaction in the arachidonate/Tween 20 mixed micelles in the same manner as phospholipase A2. The values of Km were almost constant (about 0.07 molar fraction), even when arachidonate molar ratios were changed in the surface of the mixed micelles. The values for Ks (the association constant of the enzyme to the micelle interface) ranged over 0.21-0.48 microM. The Vmax was 25.76 mumol.min-1.mg-1. This concept of a local pH change could be used extensively with enzymes which utilize both amphiphilic and acidic substances as substrates.

Crystallization and preliminary X-ray crystallographic studies of recombinant human leukotriene A4 hydrolase complexed with bestatin

Recombinant human leukotriene A4 hydrolase complexed with bestatin, an inhibitor of metalloprotease, has been crystallized by the hanging drop vapor diffusion method using 0.1 M phosphate buffer (pH 6.5) and 50 to 54% saturated ammonium sulfate. The orthorhombic crystals belong to the space group I222 or I2(1)2(1)2(1) with unit cell dimensions of a = 273.6 A, b = 261.3 A and c = 52.9 A. They diffract beyond 2.5 A resolution and a native data set up to 3 A resolution has been collected on an imaging plate Weissenberg camera using synchrotron radiation.

[Study on the aging influence on the recognizability for colored targets--black and color]

Recently spaces for the aged have become more wide spread as the population of them has increased. Most of the spaces, however, are originally provided for the young and, accordingly, can not be considered preferable environments for the aged. From this point of view, the authors aimed at the visual environments for the aged and carried out experimental research on the influences that aging gives to recognizability for colored targets, for the purpose of providing a preferable visual environment for the aged. The results show that the recognizability for colored targets declines drastically from about fifty years old, as just as the recognizability for uncolored targets. Moreover, the results show that, although the recognizability of the young is considerably influenced by differences of the illuminance and color of the target surfaces, aging made the recognizability less influencable by these differences.

[A study on the visibility of different floor levels--experiments from a stumbling point of view]

Experiments were conducted to examine the visibility of different floor levels from a stumbling point of view. The test subjects were the elderly and the young, and we compared the difference between the two. We investigated eye movement while they were scanning the different floor levels. The results were as follows: 1) The height of different floor levels and illuminance had an influence on the visibility of different floor levels. Especially, the elderly were easily influenced by them. 2) The eye movements in scanning the different floor levels did not relate to the visibility of them, but were related to the personality of the test subjects. Eye movement patterns of the elderly differed from that of the young. The elderly were scanning mainly the lower part. The eye fixation time of the elderly was longer than that of the young. From the results, it was clarified that there were the difference between the elderly and the young. We could show it by the degree of influence. For example, the influence by the change of environmental condition.

Potent in vitro and in vivo inhibitors of platelet aggregation based upon the Arg-Gly-Asp-Phe sequence of fibrinogen. A proposal on the nature of the binding interaction between the Arg-guanidine of RGDX mimetics and the platelet GP IIb-IIIa receptor

Peptide mimetics of the RGDF sequence in which Arg-Gly has been replaced with 5-(4-amidinophenyl)pentanoyl mimetic has led to a 1000-fold increase in inhibitory potency over the natural RGDF ligand. The guanidine residue of the arginine may be involved in a reinforced ionic interaction with a carboxylate of the receptor which could explain the dramatic increase in potency upon replacement with benzamidine. This hypothesis is supported by the observation of low inhibitory potency of the corresponding benzylamine (18) and no activity with the corresponding imidazoline derivative (19); plus, ab initio calculations on the respective complexes suggest that the benzamidine-carboxylate is more favorable than the guanidine-carboxylate interaction. The ED50 for the inhibition of ex vivo collagen induced platelet aggregation in the dog for SC-52012 (1) was 0.32 microgram/kg/min by iv infusion with a pharmacodynamic half-life for recovery of approximately 40 min.