Possible involvement of 5-lipoxygenase metabolite in itch-associated response of mosquito allergy in mice

This study investigated endogenous mediators involved in mosquito allergy-associated itching in mice. An intradermal injection of an extract of mosquito salivary gland elicited marked scratching in sensitized mice. The 5-lipoxygenase inhibitor zileuton (100 mg/kg), the 5-lipoxygenase activating peptide inhibitor MK-886 (10 mg/kg), and the glucocorticoid betamethasone 17-valerate (3 mg/kg) inhibited the scratching. The scratching was not affected by the cyclooxygenase inhibitors indomethacin and ketoprofen, the TP prostanoid receptor antagonist SQ-29548, the leukotriene B(4) antagonist ONO-4057, the cysteinyl leukotriene antagonist pranlucast, the leukotriene D(4) antagonist MK-571, the platelet-activating factor antagonist CV-3988, the nitric oxide synthase inhibitor N(G)-nitro-L-arginine methyl ester, the H(2) histamine-receptor antagonist cimetidine, the H(1) histamine-receptor antagonist terfenadine plus cimetidine, and cypoheptadine that blocks the 5-HT(1/2) serotonin receptors. Zileuton (100 mg/kg) inhibited the increased activity of the cutaneous nerve branch induced by an intradermal injection of the extract, suggesting the peripheral action. Zileuton and MK-886 (10 and 100 microM) did not affect high K(+)-induced increase in intracellular Ca(2+) concentration in cultured dorsal root ganglion neurons. The results suggest that 5-lipoxygenase metabolite(s) other than leukotriene B(4) and cysteinyl leukotrienes are involved in mosquito allergy-associated itching.

Real-time PCR assays based on distinct genomic regions for cytomegalovirus reactivation following hematopoietic stem cell transplantation

Real-time PCR has many advantages compared with antigenemia and qualitative PCR assays for detecting cytomegalovirus (CMV) infection in patients following SCT. However, the procedure used in each report was not standardized. This study compares the CMV load detected by real-time PCR assays amplifying distinct genomic regions. Real-time PCR assays based on US17, UL65, immediate early protein (IE) and glycoprotein B(gB) were selected and comparisons were made between each genomic region, and with antigenemia and nested PCR (IE region) in 18 SCT patients. The CMV load detected by real-time PCR using all combinations of primers targeting distinct genomic regions and by antigenemia assays correlated well. However, US17 and UL65-PCR could detect CMV earlier than gB-PCR, antigenemia and nested PCR assays. In longitudinal analysis, gB-PCR demonstrated a trend for showing a lower viral load in some patients than US17-, UL65- and IE-PCR. Moreover, the results suggest that a cutoff level of 500 copies/ml might be used to decide when to initiate treatment. We propose that monitoring should be carried out using real-time PCR assays targeting the US17 region and that a CMV load of 500 copies/ml could be used as a cutoff value for initiating treatment in patients following SCT, receiving immunoglobulin prophylaxis.

Two-terpyridine.Cu(II) complexes-containing antisense systems for rapid and highly site-specific RNA cleavage

In an approach toward artificial ribonucleases, novel RNA cleaving systems were constructed that contained two terpyridine.Cu(II) residues. The first antisense system used tandem Cu(II) complex--2'-O-methyloligonucleotide 5'- and 3'-conjugates to cleave an RNA substrate. The second system, which will be described in a future paper, contained two contiguous Cu(II) complex residues at an internal site of a 2'-O-methyloligonucleotide. We found that the first system rapidly cleaved RNA with high site-specificity. Based on these results, we expect the second system to also show efficient RNA cleavage.

Prevalence of Helicobacter pylori in NSAID users with gastric ulcer

OBJECTIVE

Regarding the interaction of Helicobacter pylori and non-steroidal anti-inflammatory drugs (NSAIDs), we cannot accept unanimous conclusions in inducing gastric ulcer. We therefore evaluated the role of Helicobacter pylori and NSAIDs in inducing gastric ulcer.

METHODS

Dyspeptic patients receiving NSAIDs underwent endoscopic examination. Gastric ulcer formation and H. pylori status were investigated. Biopsy specimens from the antrum and lower body of the stomach were prepared for the rapid urease test and pathological evaluation. Anti-H. pylori antibody was measured by enzyme-linked immunosorbent assay.

RESULTS

Two hundred and twenty-six patients receiving NSAIDs (220 chronic and six on-demand users) underwent gastrofibrescopic examination. There were 110 patients with gastric ulcer and 111 non-ulcer patients with gastritis. The remaining five patients had neither. NSAID users with gastric ulcer showed a low prevalence of H. pylori compared with those without them [55/110 (50.0%) vs 79/111 (71.2%), P < 0.01]. The same tendency was seen when patients receiving low-dose aspirin and those with rheumatoid arthritis were analysed separately [13/29 (44.8%) vs 50/62 (80.6%), P < 0.01, and 11/33 (33.3%) vs 16/26 (61.5%), P < 0.06 with Yates' correction, respectively].

CONCLUSION

Helicobacter pylori infection appeared to be a risk factor for developing gastritis, but we found no evidence that it increases gastric ulcer formation in NSAID users with dyspepsia.

Inhibitory effect of azelastine on allergic itch-associated response in mice sensitized with mosquito salivary glands extract

We examined whether azelastine would inhibit itch-associated responses of mice to mosquito allergy. Repeated injections of mosquito salivary gland extract increased scratching and sensory nerve activity. Azelastine inhibited the increased scratching and nerve activity, while terfenadine was without effects. Dexamethasone did not affect the increased scratching. Azelastine suppressed high K(+)-induced increase in intracellular free Ca(2+) in primary cultures of mouse sensory neurons. Direct inhibition by azelastine of sensory neurons may be at least involved in the anti-pruritic effect of azelastine. Histamine, substance P, and leukotriene B(4) may not play a key role in the itching of mosquito allergy.

Successful bone marrow transplantation from an unrelated donor in a patient with adult T cell leukemia

We report a 51-year-old male with adult T cell leukemia (ATL) who received a BMT from an HLA-identical unrelated donor. The ATL proved refractory to chemotherapy, and he underwent BMT conditioned with CY/TBI. Complications of encephalitis of unknown origin were successfully treated with steroid therapy and the patient has been in CR for 16 months after BMT. Human T cell leukemia virus type 1 proviral DNA loads were reduced to undetectable levels in PBMC sampled 12 months after BMT. This encouraging result suggests that BMT from an unrelated donor should be considered for ATL even if the disease is refractory to chemotherapy.

Roles of mast cells and histamine in mosquito bite-induced allergic itch-associated responses in mice

We investigated itch-associated responses (scratching) to mosquito bites and the role of histamine and mast cells in mosquito-induced itching in mice. Although the first bites of mosquito Aedes albopictus did not increase scratching, repeated bites increased scratching. The response was not diminished even after an interval of 2 months. Similarly, repeated intradermal (i.d.) injections of salivary gland extract (SGE) from Aedes albopictus increased scratching after SGE injection itself and mosquito bites. The scratching peaked within 10 min and almost subsided by 60 min. The opioid antagonist naloxone (1 mg/kg, s.c.) inhibited scratching following SGE injection. Although the non-sedative H1-histamine-receptor antagonist terfenadine (30 mg/kg, p.o.) significantly suppressed scratching induced by histamine (100 nmol/site, i.d.) in either naive or mosquito-sensitized mice, it did not affect mosquito-induced scratching in mosquito-sensitized mice. Repeated injections of SGE increased scratching in mast cell-deficient (WBB6F1-W/Wv) mice as well as in normal (WBB6F1-+/+) littermates. Repeated exposure to mosquito bites roughly doubled serum concentrations of total IgE and IgG1, but not IgG2a. Repeated injections of SGE markedly increased plasma extravasation induced by mosquito bites and such an increase was almost completely suppressed by terfenadine (30 mg/kg, p.o.). The results show the presence of histamine-mediated and histamine-independent mechanisms in cutaneous itching and suggest that histamine probably released from mast cells does not play an important role in itching in immediate allergic reaction. Our murine model of mosquito itching may be useful for studying the mechanisms of immediate allergic itching.

Rapid RNA cleavage using an antisense system with two terpyridine.Cu(II) complexes

An effective approach to promote sequence-specific RNA cleavage by an antisense 2'-O-methyloligonucleotide with a terpyridine.Cu(II) complex attached at the 5'-end was developed. We have synthesized a Cu(II) complex 3'-conjugate, which when used in a tandem fashion, greatly enhanced the RNA cleavage efficiency.

A role for MHR1, a gene required for mitochondrial genetic recombination, in the repair of damage spontaneously introduced in yeast mtDNA

A nuclear recessive mutant in Saccharomyces cerevisiae, mhr1-1, is defective in mitochondrial genetic recombination at 30 degrees C and shows extensive vegetative petite induction by UV irradiation at 30 degrees C or when cultivated at a higher temperature (37 degrees C). It has been postulated that mitochondrial DNA (mtDNA) is oxidatively damaged by by-products of oxidative respiration. Since genetic recombination plays a critical role in DNA repair in various organisms, we tested the possibility that MHR1 plays a role in the repair of oxidatively damaged mtDNA using an enzyme assay. mtDNA isolated from cells grown under standard (aerobic) conditions contained a much higher level of DNA lesions compared with mtDNA isolated from anaerobically grown cells. Soon after a temperature shift from 30 to 37 degrees C the number of mtDNA lesions increased 2-fold in mhr1-1 mutant cells but not in MHR1 cells. Malonic acid, which decreased the oxidative stress in mitochondria, partially suppressed both petite induction and the temperature-induced increase in the amount of mtDNA damage in mhr1-1 cells at 37 degrees C. Thus, functional mitochondria require active MHR1, which keeps the extent of spontaneous oxidative damage in mtDNA within a tolerable level. These observations are consistent with MHR1 having a possible role in mtDNA repair.

Allogeneic bone marrow transplantation-related transmission of human T lymphotropic virus type I (HTLV-I)

We report here the first case report of bone marrow transplantation (BMT)-related transmission of human T lymphotropic virus type-I (HTLV-I). Antibodies against HTLV-I-associated antigens (anti-HTLV-I) were detected in the serum from the BMT recipient 12 days post BMT. IgG against gag core proteins (anti-p19 and anti-p24) appeared earlier than IgM against gag and env proteins (anti-p19, anti-p24 and anti-gp46) during seroconversion. The data presented here differs from blood transfusion-related seroconversion. This phenomenon may be due to the engraftment of anti-HTLV-I producing cells from the donor.

No genetic association between alpha-2 macroglobulin I1000V polymorphism and Japanese sporadic Alzheimer's disease

Alpha-2 macroglobulin (A2M) is a serum pan-protease inhibitor that is related with the pathogenesis of Alzheimer's disease (AD) through its ability to mediate amyloid beta degradation. Recently, it has been reported that the I1000V polymorphism in A2M gene might increase the risk of AD. In the present study, we investigated this mutation in 95 healthy controls and in 111 sporadic AD cases by polymerase chain reaction-restriction fragment length polymorphism method in order to study this hypothesis in the Japanese AD population. Allelic frequencies with the I1000V polymorphism in the gene were 7.4 and 6.8% in the control and AD groups, respectively. Our results failed to demonstrate an association between this polymorphism and Japanese sporadic AD, and the A2M I1000V mutation does not seem to be a risk factor per se for sporadic AD.

Induction of ribozyme activity by anti-ribozyme oligonucleotides

A new type of hammerhead ribozyme, with cleavage activity enhanced by oligonucleotides, was constructed. Stem II of the ribozyme was substituted with a non complementary loop (loop II). The modified ribozyme exhibited negligible cleavage of a target RNA; however, it was converted to an active molecule in the presence of oligonucleotides which were complementary to loop II. The oligonucleotide compensated for the disabled stem II by binding with the ribozyme. The induction of the cleavage activity was sequence-specific and the oligonucleotides containing a purine base as the 3'-dangling end were able to induce the cleavage activity of the ribozyme most efficiently. A photo-crosslinking experiment proved that a pseudo-half-knot structure was formed in the active molecule. The cleavage of two kinds of substrate RNAs with different sequences was controlled by the corresponding ribozymes activated by specific oligonucleotides.

Nucleic acid synthesis for investigations of gene functions

The chemical syntheses of genes encoding human c-Ha-ras and T4 endonuclease V are described. These genes have been used for studies of mutagenesis by damaged bases and recognition of nucleic acids by proteins. The modes of interaction of photo-damaged DNA and cognate antibodies have also been investigated by biochemical and physicochemical approaches.

Chemical synthesis and properties of (6-4) photoproduct and its analogs

We report the preparation of a deoxyribooligonucleotide containing a new thymine (6-4) photoproduct analog. The (6-4) photoproduct is one of the major forms of DNA lesions, and leads to mutation in DNA. An antibody (64M5) that binds the (6-4) photoproduct has been described. To investigate the interaction of the photoproduct with the 64M5 antibody, we prepared a (6-4) photoproduct analog in which the two thymines were connected with a formacetal linkage. With UV-irradiation, the thymine dimer with the formacetal linkage reacted to the (6-4) photoproduct faster than the phosphodiesterified dimer, and the yields of the analog was higher than those of the natural thymine dimer. The 64M5 antibody exhibited sufficient binding to a tetranucleotide containing the (6-4) photoproduct analog with a formacetal linkage, although the association constant was slightly lower than that for the natural lesion. This (6-4) photoproduct analog may be useful for investigation of other proteins that recognize the (6-4) photoproduct.

Further studies of KMnO4 oxidation of synthetic DNAs containing oxidatively damaged bases

Recently we found that KMnO4 oxidation of DNA oligomers containing a 7,8-dihydro-8-oxoguanine (8-oxo-G) residue induces damage to the neighboring base residues; other modified bases, 7,8-dihydro-8-oxoadenine (8-oxo-A) and 5-hydroxyuracil (5-oh-U), show similar behavior in DNA. The present study indicated that the ability to induce damage, which could also occur by the oxidation of a 5-oh-C residue, was low as in the case of 5-oh-U. On the other hand, in order to examine the pathways and the intermediates for the oxidative degradation of 8-oxo-A, we have carried out the KMnO4 oxidation using an 8-oxo-2'-deoxyadenosine derivative as a model and have determined the structures of the three major products.

Crystal structures of the 64M-2 and 64M-3 antibody Fabs complexed with DNA (6-4) photoproducts

Crystal structures of the 64M-2 antibody Fab fragment complexed with DNA photoproducts of dT(6-4)T and dTT(6-4)TT, and of the 64M-3 Fab fragment complexed with dT(6-4)T were determined. The 5'-thymine base of the bound dT(6-4)T ligand is in a half-chair conformation, and its base plane is nearly perpendicular to the planar 3'-pyrimidone base. The 64M-2 and 64M-3 Fabs have a common structure suitable for accommodating the dT(6-4)T ligand. In each of the antigen binding sites of the 64M-2 and 64M-3 Fabs, basic residues of His 35H and Arg 95H are located at the bottom of the binding pocket, and are hydrogen-bonded to the base moieties of dT(6-4)T. Two water molecules are involved in the interactions that intervene between the base moieties and the binding site. Aromatic residues of Trp 33H and Tyr 100iH form a side-wall of the pocket and are in van der Waals interactions with the base moieties. The Trp 33H side-chain is placed in parallel to the 3'-pyrimidone base, and the Tyr 100iH side-chain is nearly perpendicular to the 5'-thymine base. His 27dL, Tyr 32L, Leu 93L, and Ser 58H forming another side-wall are located in the vicinity of the sugar-phosphate backbone. In the 64M-2 Fab complex with dTT(6-4)TT, 5'- and 3'-side phosphate groups are also involved in interaction with Fab residues.

Toward artificial ribonucleases: design and synthesis of 2'-O-methyloligonucleotides with a terpyridine-copper(II) complex

In order to construct an antisense 2'-O-methyloligonucleotide with an internal terpyridine-Cu(II) complex, a novel synthon was synthesized. This synthon was a 2'-deoxy-uridine-3'-phosphoramidite derivative with a terpyridine group at the 5'-O and a dimethoxytritylated hydroxypropyl group at the C-5. The antisense agent cleaved the RNA site-specifically and in a moderate yield.

[Leukocytopenia and thrombocytopenia preceded by human parvovirus B19 infection: report of three adult cases]

In Saiki City, Oita, Japan, erythema infectiosum in children has been prevalent from June, 1999 to the time of writing (January, 2000). We present three adult cases of parvovirus B19-associated leukocytopenia and thrombocytopenia that developed during this epidemic. Between June and November, 1999, a 32-year-old woman, a 38-year-old woman, and a 63-year-old man were referred to our hospital for treatment of leukocytopenia and thrombocytopenia. All complained of common cold-like symptoms. Their WBC counts (percentage of neutrophils) were 1,000/microliter (70%), 1,900/microliter (40%) and 1,680/microliter (40%), their hemoglobin levels 9.4 g/dl, 9.8 g/dl and 14.9 g/dl, and their platelet counts 10.8 x 10(4)/microliter, 6.9 x 10(4)/microliter and 4.5 x 10(4)/microliter, respectively. The diagnosis of parvovirus B19 infection was documented by the presence of B19-specific IgM antibodies or serum positivity for viral DNA. In two cases, the leukocytopenia and thrombocytopenia resolved gradually. In the other case, leukocytopenia, thrombocytopenia and B19 infection persisted for more than two months. These cases suggest that parvovirus B19 may be a common cause of leukocytopenia and thrombocytopenia even in adult patients without hematological disorders (erythropoietic stress), and that testing for parvovirus infection is justified in such patients, even if anemia is slight, especially when erythema infectiosum is prevalent.

Construction of new ribozymes requiring short regulator oligonucleotides as a cofactor

A hairpin loop and an oligonucleotide bound to the loop form one-half of the pseudoknot structure. We have designed an allosteric hammerhead ribozyme, which is activated by the introduction of this motif by using a short complementary oligonucleotide as a cofactor. Stem II of the hammerhead ribozyme was substituted with a non-self-complementary loop sequence (loop II) to abolish the cleavage activity. The new ribozyme had almost no cleavage activity of the target RNA. However, it exhibited the cleavage activity in the presence of a cofactor oligoribonucleotide, which is complementary to loop II of the ribozyme. The activity is assumed to be derived from the formation of a pseudo-stem structure between the cofactor oligonucleotide and loop II. The structure including the loop may be similar to the pseudo-half-knot structure. The activation efficiencies of the cofactor oligonucleotides were decreased as the lengths of the oligonucleotides increased, and the ribozyme with a longer loop II was more active than that with a short loop II. Oligoribonucleotides with 3'-dangling purine bases served as efficient cofactors of the ribozyme, and a 2'-O-methyloligonucleotide enhanced the cleavage activity of the ribozyme most efficiently, by as much as about 750-fold as compared with that in the absence of the oligonucleotide. Cofactor oligonucleotides with a cytidine base at the 3'-end also activated a ribozyme with the G10.1.G11.1 mutation, which eliminates the cleavage activity in the wild-type. The binding sites of the oligonucleotide were identified by photo-crosslinking experiments and were found to be the predicted sites in the loop. This is the first report of a design aimed at positively controlling the activity of ribozymes by employing a structural motif. This method can be applied to control the activities of other functional RNAs with hairpin loops.

Crystal structure of the 64M-2 antibody Fab fragment in complex with a DNA dT(6-4)T photoproduct formed by ultraviolet radiation

DNA photoproducts with (6-4) pyrimidine-pyrimidone adducts formed by ultraviolet radiation are implicated in mutagenesis and cancer, particularly skin cancer. The crystal structure of the Fab fragment of the murine 64M-2 antibody specific to DNA T(6-4)T photoproducts is determined as a complex with dT(6-4)T, a (6-4) pyrimidine-pyrimidone photodimer of dTpT, at 2.4 A resolution to a crystallographic R-factor of 0.199 and an R(free) value of 0.279. The 64M-2 Fab molecule is in an extended arrangement with an elbow angle of 174 degrees, and its five complementarity-determining regions, except L2, are involved in the ligand binding. The bound dT(6-4)T ligand adopting a ring structure with (6-4) linked 5' thymine-3' pyrimidone bases is fully accommodated in an antigen-binding pocket of about 15 Ax10 A. The 5'-thymine and 3'-pyrimidone bases are in half-chair and planar conformations, respectively, and are nearly perpendicular to each other. The 5'-thymine base is hydrogen-bonded to Arg95H and Ser96H, and is in van der Waals contact with Tyr100iH. The 3'-pyrimidone base is hydrogen-bonded to His35H, and is in contact with Trp33H. Three water molecules are located at the interface between the bases and the Fab residues. Hydrogen bonds involving these water molecules also contribute to Fab recognition of the dT(6-4)T bases. The sugar-phosphate backbone connecting the bases is surrounded by residues His27dL, Tyr32L, Ser92L, Trp33H, and Ser58H, but is not hydrogen-bonded to these residues.

Functional domain-assembly in hairpin ribozymes

Functional structures of hairpin ribozymes have been investigated by constructing various chemically modified molecules. Domain-exchange and linker insertion experiments were performed to find active conformations of the RNA enzyme showing cleavage activity. Our experiments and other evidence suggest that the active structure has a bent conformation, and that domain-interactions are essential for the cleavage activity.

DNA binding mode of the Fab fragment of a monoclonal antibody specific for cyclobutane pyrimidine dimer

Monoclonal antibodies specific for the cyclobutane pyrimidine dimer (CPD) are widely used for detection and quantification of DNA photolesions. However, the mechanisms of antigen binding by anti-CPD antibodies are little understood. Here we report NMR analyses of antigen recognition by TDM-2, which is a mouse monoclonal antibody specific for the cis - syn -cyclobutane thymine dimer (T[ c, s ]T). (31)P NMR and surface plasmon resonance data indicated that the epitope recognized by TDM-2 comprises hexadeoxynucleotides centered on the CPD. Chemical shift perturbations observed for TDM-2 Fab upon binding to d(T[ c, s ]T) and d(TAT[ c, s ]TAT) were examined in order to identify the binding sites for these antigen analogs. It was revealed that d(T[ c, s ]T) binds to the central part of the antibody-combining site, while the CPD-flanking nucleotides bind to the positively charged area of the V(H)domain via electrostatic interactions. By applying a novel NMR method utilizing a pair of spin-labeled DNA analogs, the orientation of DNA with respect to the antigen-binding site was determined: CPD-containing oligonucleotides bind to TDM-2 in a crooked form, draping the 3'-side of the nucleotides onto the H1 and H3 segments, with the 5'-side on the H2 and L3 segments. These data provide valuable information for antibody engineering of TDM-2.

Investigation of the recognition of an important uridine in an internal loop of a hairpin ribozyme prepared using post-synthetically modified oligonucleotides

We introduced 4-thio- ((4S)U), 2-thio- ((2S)U), 4- O -methyluridine ((4Me)U) and cytidine substitutions for U+2, which is an important base for cleavage in a substrate RNA. Oligonucleotides containing 4-thio- and 4- O -methyluridine were prepared by a new convenient post-synthetic modification method using a 4- O - p -nitrophenyl-uridine derivative. A hairpin ribozyme cleaved the substrate RNA with either C+2, (4S)U+2 or (4Me)U+2 at approximately 14-, 6- and 4-fold lower rates, respectively, than that of the natural substrate. In contrast, the substrate with a (2S)U+2 was cleaved with the same activity as the natural substrate. These results suggest that the O4 of U+2 is involved in hydrogen bonding at loop A, but the O2 of U+2 is not recognized by the active residues. Circular dichroism data of the ribozymes containing (4S)U+2 and (2S)U+2, as well as the susceptibility of the thiocarbonyl group to hydrogen peroxide, suggest that a conformational change of U+2 occurs during the domain docking in the cleavage reaction. We propose here the conformational change of U+2 from the ground state to the active molecule during the reaction.

Tryptophan H33 plays an important role in pyrimidine (6-4) pyrimidone photoproduct binding by a high-affinity antibody

The importance of Trp H33 in antibody recognition of DNA containing a central pyrimidine (6-4) pyrimidone photoproduct was investigated. This residue was replaced by Tyr, Phe and Ala and the binding abilities of these mutants were determined by surface plasmon resonance and fluorescence spectroscopy. Conservative substitution of Trp H33 by Tyr or Phe resulted in moderate losses of binding affinity; however, replacement by Ala had a significantly larger impact. The fluorescence properties of DNA containing a (6-4) photoproduct were strongly affected by the identity of the H33 residue. DNA binding by both the wild-type and the W-H33-Y mutant was accompanied by a small degree of fluorescence quenching; by contrast, binding by the W-H33-F and W-H33-A mutants produced large fluorescence increases. Taken together, these variations in binding and fluorescence properties with the identity of the H33 residue are consistent with a role in photoproduct recognition by Trp H33 in the high-affinity antibody 64M5.

Reactive oxygen species production of neutrophils in patients with acute promyelocytic leukemia during treatment with all-trans retinoic acid

We measured N-formyl-methionyl-leucyl-phenylalanine-induced reactive oxygen species production by neutrophils from three patients with acute promyelocytic leukemia during treatment with all-trans retinoic acid using a luminol-enhanced chemiluminescence assay. The maximum level of reactive oxygen species production during all-trans retinoic acid treatment was 58.8 +/- 2.3 x 10(4) (mean +/- SEM) counted photons per seconds (cps), which was significantly higher (p<0.0001) than that of neutrophils from health volunteers (13.3 +/- 2.3 x 10(4) cps).

[Nucleic acid syntheses and molecular recognition]

Syntheses of nucleic acids are of importance not only in the natural product chemistry but also in the molecular recognition study in biology. This review describes syntheses of RNA and DNA, which were found to be related each other. Deoxyinosine probes were developed for cloning genes with degenerated codons. Synthetic genes for c-Ha-ras and T4 endonuclease V provided new approaches in recognition of nucleic acids by proteins. Antibodies specific for photo-damaged pyrimidines in DNA have been studied by cloning and mutating their genes.

Genetic association between alpha-2 macroglobulin and Japanese sporadic Alzheimer's disease

Alpha-2 macroglobulin (encoded by the gene A2M) is a serum pan-protease inhibitor that may be related with the pathogenesis of Alzheimer's disease (AD) because of its ability to mediate amyloid beta degradation. Recently, several groups have reported that the five-nucleotides deletion in A2M gene at the 5' splice site of exon 18 might increase risk for AD. In the present study, therefore, this mutation was studied in 69 healthy controls and 55 sporadic AD cases by polymerase chain reaction- restriction fragment length polymorphism method. The allelic frequencies with the deletion (A2M-2) are 9.4 and 6.4% in the control and AD groups, respectively. There is no significant difference in the A2M-2 frequencies between the controls and sporadic AD cases. This is the first report to study the frequencies of A2M-2 in Japanese AD cases, suggesting its no genetic association with sporadic AD.

Conformational multiplicity of the antibody combining site of a monoclonal antibody specific for a (6-4) photoproduct

The antigen binding site of monoclonal antibody 64M5, which possesses a high degree of affinity for DNA containing pyrimidine (6-4) pyrimidone photoproducts, were investigated by use of stable-isotope-assisted NMR spectroscopy. A variety of 64M5 Fab fragments specifically labeled with 13C and 15N at backbone amide groups were prepared. Extensive assignments of amide resonances originating from the variable region of 64M5 were made by using 2D-HN(CO) measurements along with recombination of the heavy and light chains of 64M5. On the basis of chemical shift changes of the amide resonances caused upon addition of d(T[6-4]T) and d(GTAT[6-4]TATG), the binding sites of 64M5 Fab for the (6-4) photodimer and for the oligodeoxynucleotides flanking it were identified. It was revealed that the L1 and L3 segments, which are responsible for the binding to (6-4) photodimer, exhibit conformational multiplicities in the absence of antigens, and take different conformations between the d(T[6-4]T) and d(GTAT[6-4]TATG)-bound forms. On the basis of spectral comparison with another Fab fragment with a similarity in the amino acid sequence of the VL domain of 64M5, we suggest that the conformational multiplicities observed in the present study is caused by a substitution of an amino acid residue at the position of a key residue in L3 canonical structure, which leads to a preferable effect on the antigen binding, and by a specific combination of L1 and L3 canonical structures.

Human MMH (OGG1) type 1a protein is a major enzyme for repair of 8-hydroxyguanine lesions in human cells

8-Hydroxyguanine (8-OH-G) is the site of a frequent mutagenic lesion of DNA, produced by oxidative damage. MutM of E. coli and OGG1 of Saccharomyces cervisiae are known to possess 8-OH-G glycosylase activity and apurinic (AP) site lyase activity to repair 8-OH-G lesions. Recently, cDNA clones of human OGG1 homologues (hMMH) of four isoforms (type 1a, type 1b, type 1c, and type 2) were isolated. However, it is unknown whether expression of endogenous hMMH proteins actually occurs in mammalian cells. Here using hMMH type 1a-specific antibody and cells overexpressing tag-fused hMMH type 1a, we show the expression of hMMH type 1a protein in many types of human cells and show that endogenous hMMH type 1a protein has 8-OH-G glycosylase/AP lyase activity. Furthermore, we show that upon depletion of hMMH type 1a protein in a whole cell extract by its antibody, most of the AP lyase activity is lost, indicating that hMMH type 1a protein is a major enzyme for repair of 8-OH-G lesions in human cells.

Effects of a high-affinity antibody fragment on DNA polymerase reactions near a (6-4) photoproduct site

Pyrimidine (6-4) pyrimidone photodimers are major photoproducts that have mutagenic and carcinogenic consequences. One major reason for these biological effects of (6-4) photoproducts may be base mispairing/DNA replication errors due to hydrogen bonding to bases opposite these damaged sites. We synthesized a modified 41-mer DNA containing a (6-4) photoproduct using a preformed building block, then employed it as a template for primer extension reactions catalyzed by Klenow fragment and DNA polymerases alpha, beta and delta (pol alpha, pol beta and pol delta). None of these DNA polymerases were able to bypass the (6-4) photoproduct and elongation terminated at or near the 3'-pyrimidone of the photoproduct, depending on the dNTP concentration. When a single-chain Fv (scFv) with high affinity for the (6-4) photoproduct was included in the polymerization reaction, DNA synthesis was inhibited at base positions four, six, eight or eight nucleotides prior to the 3'-pyrimidone by Klenow fragment, pol alpha, pol beta or pol delta, respectively. These results suggest that the scFv can bind to the template DNA containing a (6-4) photoproduct and inhibit extension reactions by polymerases.

Probing the interaction between a high-affinity single-chain Fv and a pyrimidine (6-4) pyrimidone photodimer by site-directed mutagenesis

We have used site-directed mutagenesis to uncover the origin of the binding affinity differences exhibited by a series of monoclonal antibodies that recognize pyrimidine (6-4) pyrimidone photoproducts in the context of single- or double-stranded DNA. In this study, we have focused on two antibodies-64M3 and 64M5-that share the same binding specificity but differ in their affinities. We used single-chain Fv (scFv) derivatives for these studies since they can be easily expressed in Escherichia coli. To facilitate this, we also developed a simple, on-column refolding procedure for scFvs that is rapid and does not require high dilution. We took several precautions to ensure that the scFvs faithfully reflected the behavior of the parent monoclonal antibodies. Results obtained from chimeric scFvs constructed from 64M3 and 64M5 suggested that the higher affinity of the 64M5 antibody was mainly due to its VL region. Loop-grafting studies in which VH CDR loops of 64M3 were individually transplanted into 64M5 were consistent with this hypothesis. Since the VL sequences of 64M3 and 64M5 differ at only three positions (L30, L50, and L90), alanine-scanning mutagenesis was used to assess the importance of these three residues in DNA binding by 64M5. These studies highlighted the importance of all three VL CDR loops; furthermore, they suggested that photoproduct binding involved conformational changes within the VL region.

A rapid method for determination of the relative copy number of HTLV-I proviral genome in HTLV-I carriers and adult T-cell leukemia patients by polymerase chain reaction

Ten adult T-cell leukemia (ATL) patients and 11 asymptomatic human T-cell leukemia virus type I (HTLV-I) carriers were examined by polymerase chain reaction (PCR) assay with a reduced sensitivity to evaluate its utility in detecting the relative copy number of the HTLV-I genome in clinical samples. Differences in the intensities of the PCR products were observed between the acute type ATL patients and ATL patients in remission or carriers. Intense bands were found in all acute type ATL patients (6/6, 100%), while specific bands were seen in only 2 carriers (2/11, 18.2%). The bands found in one of the two patients in remission were weak. One patient, who had acute type ATL, had achieved a remission but later relapsed. Using this technique, we examined the differences in the intensities of the bands of the PCR products in a patient with acute type ATL who had achieved remission but later relapsed. Thus, this technique may be of clinical importance in diagnosing acute ATL and assessing the effect of therapy.

[Lymphoma associated hemophagocytic syndrome with plasmacytosis in the bone marrow and hypergammaglobulinemia]

A 72-year-old woman was admitted to our hospital because of fever, anemia and thrombocytopenia in March 1997. Laboratory findings showed elevated serum LDH levels and polyclonal gammopathy. Bone marrow aspiration samples revealed hemophagocytosis and plasmacytosis. Although serum interleukin-6 was elevated, serum interferon-lambda and tumor necrosis factor-alpha were below detectable limits. Magnetic resonance images disclosed a tumor in the patient's pelvic cavity. The tumor was resected and diagnosed as non-Hodgkin's lymphoma. The patient was treated with combination chemotherapy and has remained in complete remission. Also, histiocyte and plasma cell counts in the bone marrow fell significantly and the serum interleukin-6 level returned to the normal range. We reasoned that lymphoma cells may have induced plasmacytosis in the bone marrow and polyclonal gammopathy accompanied by hemophagocytic syndrome.

Eosinophilia associated with adult T-cell leukemia: role of interleukin 5 and granulocyte-macrophage colony-stimulating factor

To clarify the mechanism of eosinophilia in adult T-cell leukemia (ATL), we studied three ATL patients having marked eosinophilia. Eosinophil-predominant colony-stimulating activity was detected in the serum of one patient and in the conditioned media (CM) from cultured ATL cells from two patients. Soluble interleukin 5 (IL-5), but no interleukin 3 (IL-3) and granulocyte-macrophage colony-stimulating factor (GM-CSF), was detected in sera from all patients. On the other hand, GM-CSF was produced in vitro by ATL cells from all cases, whereas detectable IL-3 and IL-5 was produced by cells from only one, suggesting that in the other two cases, the serum IL-5 was produced by the normal reacting lymphocytes. The fact that no patient showed marked neutrophilia supports the possibility that IL-5 may have a leading role in the development of eosinophilia, with GM-CSF produced by ATL cells playing a complementary role.

The role of surface lysines in pyrimidine (6-4) pyrimidone photoproduct binding by a high-affinity antibody

The roles of four VH surface lysine side-chains in antibody recognition of DNA containing a central pyrimidine (6-4) pyrimidone photoproduct was investigated. Three of the four lysines (at positions H62, H64 and H66) are strongly conserved; however, the presence of lysine at position H68 was highly unusual. Each lysine was replaced individually by alanine; in addition, a quadruple mutant was also created. Studies of the binding kinetics revealed that these lysine residues mainly influenced the association phase. Our results suggest that these side chains help to guide the DNA polyanion to the antigen binding pocket by electrostatic effects.

Modification and application of self-trimming hairpin ribozymes to targeting a transcribed RNA in vitro

The three-domain hairpin ribozyme was improved by increasing the number of linker bases connecting domain I' with domain II from six to seven, and a new ribozyme was designed to release a trans-acting ribozyme that is able to bind with target RNAs by three hybridizing arms. The trans-cleavage activities of the trimmed ribozyme were used to cleave a long target RNA, with 85 bases transcribed from a synthetic gene encoding induced nitric oxide synthase (iNOS). Although the ribozyme with three-hybridizing arms did not efficiently cleave the long target RNA, the overall activity, from self-trimming to the trans-cleavage reaction of the target RNA, was higher than that of the ribozyme with two hybridizing arms.

Neighboring base damage induced by permanganate oxidation of 8-oxoguanine in DNA

We found that single-stranded DNA oligomers containing a 7, 8-dihydro-8-oxoguanine (8-oxo-G) residue have high reactivity toward KMnO4; the oxidation of 8-oxo-G induces damage to the neighboring nucleotide residues. This paper describes the novel reaction in detail, including experiments that demonstrate the mechanism involved in the induction of DNA damage. The results using DNAs of various base compositions indicated that damaged G, T and C (but not A) sites caused strand scissions after hot piperidine treatment and that the damage around the 8-oxo-G occurred at G sites in both single and double strands with high frequency. The latter substrates were less sensitive to damage. Further, kinetic studies of the KMnO4reaction of single-stranded oligomers suggested that thereactivity of the DNA bases at the site 5'-adjacent to the 8-oxo-G was in the order G >A >T, C. This preference correlates with the electron donating abilities of the bases. In addition, we found that the DNA damage at the G site, which was connected with the 8-oxo-G by a long abasic chain, was inhibited in the above order by the addition of dG, dA or dC. On the other hand, the damage reactions proceeded even after the addition of scavengers for active oxygen species. This study suggests the involvement of a redox process in the unique DNA damage initiated by the oxidation of the 8-oxo-G.

31P NMR study of the interactions between oligodeoxynucleotides containing (6-4) photoproduct and Fab fragments of monoclonal antibodies specific for (6-4) photoproduct

A 31P nuclear magnetic resonance (NMR) study of the interactions between oligonucleotides containing the (6-4) photoproduct and the Fab fragments of monoclonal antibodies (64M3 and 64M5) recognizing the (6-4) photoproduct is reported. The 31P chemical shift data indicate that backbone conformation of (64) adduct is affected by the presence of flanking oligodeoxynucleotides, and (6-4) adducts with different backbone conformations are accommodated in the antigen binding sites of these antibodies. It was also revealed that epitopes for these antibodies consist of not only the (6-4) adduct but the flanking di- or tri-deoxynucleotides on both the 5' and 3' sides as well.

Antibodies specific for (6-4) DNA photoproducts: cloning, antibody modeling and construction of a single-chain Fv derivative

We have investigated a series of four monoclonal antibodies that specifically recognize pyrimidine (6-4) pyrimidone photoproducts. One of these antibodies (64M4), bound all four possible pyrimidine-pyrimidone photoadducts with equal affinities whereas the others (64M2, 64M3 and 64M5) were selective for TC and TT sequences. In addition, 64M5 had the highest binding affinity for photodamaged DNA of the four [T. Mori et al., Photochem. Photobiol. 54 (1991) 225-232]. To help understand the differences between these antibodies, we have cloned and sequenced the variable region genes from all four. Comparing these sequences revealed that all four were highly similar to one another, although there were some differences in potential antigen-contact regions. To assess the influences of these sequence differences at the structural level, computer models were constructed for all four antibodies. Most of the sequence differences occurred in potential antigen contact regions, suggesting specific positions that might account for the observed differences in binding affinities and selectivities. A single-chain Fv derivative of 64M5 was therefore constructed and characterized to provide an experimental system in which structure-function relationships can be tested. This derivative could be isolated from Escherichia coli using two chromatographic steps and possessed the same binding specificity as the parent monoclonal antibody.

Functional sites of human PCNA which interact with p21 (Cip1/Waf1), DNA polymerase delta and replication factor C

BACKGROUND

PCNA, an eukaryotic DNA sliding clamp interacts with replication factors and the cell cycle protein, p21(Cip1/Waf1) and functions as a molecular switch for DNA elongation. To understand how DNA replication is regulated through PCNA, elucidation of the precise mechanisms of these protein interactions is necessary.

RESULTS

Loop-region mutants in which human PCNA sequences were substituted with the corresponding Saccharomyces cerevisiae PCNA regions were prepared. Analysis of their functions, along with previously prepared alanine scanning mutants, demonstrated that some loops interact with DNA polymerase delta (pol delta) and replication factor C (RFC). The p21 binding sites of PCNA, mapped by affinity measurement of the mutant forms, found to be located within a distinct structure of the PCNA monomer, overlap with RFC- and pol delta-interaction sites. Competition between p21 and pol delta or RFC for binding to PCNA results in efficient inhibition of its stimulation of pol delta DNA synthesis and RFC ATPase but not of PCNA loading on DNA by RFC.

CONCLUSIONS

Semi-saturated amounts of p21 selectively block formation of the active pol delta complex but not the RFC-PCNA complex at 3'-ends of DNA primers. This differential effect may explain the specific inhibition of DNA replication by p21.