Co-mutagenicity of glyco- and tauro-deoxycholic acids in the Ames test

Mutagenicity and co-mutagenicity of glyco- and tauro-deoxycholic acids (GDCA and TDCA), which are abundant in human bile, were examined by the Ames test. The two chemicals were not mutagenic for themselves to Salmonella typhimurium TA98 and TA100, with and without S9 mix. They enhanced, however, the mutagenic activities of the pro-mutagens, 2-aminoanthracene (2AA) and benzo[a]pyrene (BaP), for both TA98 and TA100 with S9 mix. They were more co-mutagenic for the pro-mutagens on TA98 than on TA100. On TA98, the mutagenic activities of 2AA with GDCA (5 mumol/plate) and with TDCA (5 mumol/plate) were 9.7-fold and 11.8-fold as high as that of the corresponding control (2AA only), respectively. BaP with GDCA (2.5 mumol/plate) and with TDCA (2.5 mumol/plate) showed 2.8-fold and 3.0-fold increases over the corresponding control level (BaP only), respectively. It is hence concluded that GDCA and TDCA may enhance the activity of some mutagens existing in bile.

Elucidation of the mechanism enhancing the avidity of lectin with oligosaccharides on the solid phase surface

The mechanism underlying molecular recognition of lectins was elucidated by a novel solid phase binding assay system based on surface plasmon resonance. When the apparent affinities of interactions between chitooligosaccharides and wheat germ agglutinin were compared between lectin-immobilized and oligosaccharide-immobilized assay systems, the affinity constants (Ka) calculated for the former system were in good agreement with the previously reported values measured in solution. On the other hand, in the latter system, the calculated Ka could be more than 10,000 times higher than the values in solution at lower lectin concentrations. To elucidate the reason for this, we systematically investigated the effects of the oligosaccharide immobilized density and the lectin valence on the apparent affinity in the oligosaccharide-immobilized assay system. Both the apparent association (k[ass]) and dissociation rate constants (k[diss]) showed a tendency to decrease as the oligosaccharide density increased. This effect was most remarkable for the interaction possessing an extremely fast intrinsic k(ass). Oligomerization of lectin enhanced the avidity due to a significant reduction in k(diss). These phenomena could be explained by considering the nonhomogeneous conditions under which binding occurred. The reaction in a nonhomogeneous state is limited by the mass transport effect, and the effect of rebinding becomes so large that it cannot be disregarded. These findings are the first to demonstrate the importance of the mass transport effect in modulating the affinity of lectin for oligosaccharides on a solid phase surface.

[Microsatellite analysis of Duchenne muscular dystrophy]

Duchenne muscular dystrophy is X-linked recessive neuromuscular disorders caused by mutations in the dystrophin gene. Prenatal diagnosis and carrier detection are usually performed using diallelic RFLP-markers which are not always informative. Now 30 of microsatellite marker have reported, these microsatellite polymorphism can easily be amplified using PCR technique. If mutations are known to localize in this region of the dystrophin gene or if routine RFLP-analysis is uninformative, the analysis of microsatellite markers is the preferable technique in prenatal diagnosis and carrier detection.

Loss of self-tolerance to ICA69 in nonobese diabetic mice

Islet cell antigen p69 (ICA69) is a target autoantigen in IDDM. Studies of T-cells from newly diabetic children suggested possible antigenic mimicry between human ICA69 (in particular the Tep69 T-cell epitope, aa 36-47) and the ABBOS region in bovine serum albumin (BSA; aa 152-169), one of several cow's milk proteins that evoke abnormal immunity in diabetes-prone hosts. We recently found the sequence of Tep69 regions to be identical in the four alternatively spliced human and rodent ICA69 isoforms. Immunization of nonobese diabetic (NOD) mice with BSA or ICA69 generates fully cross-reactive T-cell responses to both Tep69 and ABBOS as the immunodominant, naturally generated, and presented T-cell mimicry epitopes. Such responses are absent or weak in healthy strains of mice. NOD mouse recipients of adoptive spleen cell grafts from diabetic donors spontaneously generate easily detectable pools of T-cells specific for ICA69/BSA, as well as the unrelated GAD65. NOD mice injected neonatally with ABBOS or Tep69 show cross-tolerance, but ABBOS-induced tolerance is transient. Neonatal injection of Tep69 reduces disease incidence (23 vs. 68% IDDM, P < 0.02), while neonatal injection of ABBOS has little effect. In contrast, systemic immunization of young NOD females with ABBOS (but not Tep69) reduces the diabetes incidence and delays disease expression, with protected mice generating ABBOS-specific T-cell repertoires unable to recognize the Tep69 mimicry antigen. Our observations demonstrate a loss of self-tolerance to ICA69 in NOD mice, and they establish antigenic mimicry between the two T-cell epitopes in ICA69 and BSA. Further studies are necessary to understand the molecular basis of this mimicry and how either T-cell peptide can modify the disease course.

Identification of a high-affinity binding protein for N-acetylchitooligosaccharide elicitor in the plasma membrane of suspension-cultured rice cells by affinity labeling

A high-affinity binding protein for the N-acetylchito-oligosaccharide elicitor of phytoalexin biosynthesis was identified by photoaffinity labeling and affinity cross-linking in the plasma membrane of suspension-cultured rice cells. Both a [125I]-labeled photolabile 2-(4-azidophenyl)ethylamino conjugate ([125I]-GN8-AzPEA) and a [125I]-labeled 2-(4-aminophenyl)ethylamino conjugate ([125]-GN8-APEA) of N-acetylchito-octaose were synthesized. The two conjugates were separately incubated with the plasma membrane prepared by aqueous two-phase partitioning, and covalently cross-linked to the elicitor binding site by irradiation with UV light or treatment with the cross-linking agent glutaraldehyde, respectively. Autoradiography of the SDS-PAGE gel of the solubilized membrane proteins revealed the labeling of a single 75 kDa band in both cases. The incorporation of the radiolabeled ligands into the 75 kDa protein showed a saturable mode of binding, with half-maximal incorporation at 45 and 52 nM for photoaffinity labeling and affinity cross-linking, respectively. The labeling of the 75 kDa protein was inhibited by N-acetylchito-oligosaccharides in a size-dependent manner, and N-acetylchito-octaose (GlcNAc)8 showed a half-maximal inhibition at concentrations of the order of 10 nM. However, neither chito-octaose (GlcN)8, cellopentaose nor alpha-1,4 linked N-acetylgalactosamine octamer (GalNAc)8 at concentrations as high as 25 microM inhibited the labeling of the 75 kDa protein. These results are in good agreement with the sensitivity and the specificity of the 'high-affinity binding site' previously identified by binding assays, as well as with the activities of these oligosaccharides in the induction of phytoalexin biosynthesis and other cellular responses. These results suggest that the 75 kDa protein identified by the affinity labeling represents a functional receptor for this elicitor.

Treatment of experimental allergic encephalomyelitis by selective removal of CD4+ T cells

Experimental allergic encephalomyelitis (EAE) is a major animal model of human multiple sclerosis (MS). The pathogenesis of both MS and EAE directly involves CD4+ helper T cells. To remove CD4+ T cells selectively from the circulation, we designed a new column in which anti-CD4 monoclonal antibody was immobilized on the activated substance. Most of the CD4+ T cells, including pathogenic T cells, were selectively adsorbed from whole blood with a direct perfusion through the column in vitro, resulting in depletion of the antigen-specific T cell responses. A preliminary trial of ex vivo treatment with the column in EAE rats lowered the percentages of CD4+ populations but failed to alter the course of the disease, suggesting repeated treatment would be necessary to suppress the development of the disease. We conclude that this new column is potentially useful, and repeated treatment would be beneficial in MS and other CD4+ T cell dependent autoimmune diseases.

Isolation, cDNA cloning, biological properties, and carbohydrate binding specificity of sieboldin-b, a type II ribosome-inactivating protein from the bark of Japanese elderberry (Sambucus sieboldiana)

A type II ribosome-inactivating protein (RIP) was isolated from the bark tissue of Japanese elderberry (Sambucus sieboldiana) and named sieboldin-b. Sieboldin-b is a heterodimeric protein consisting of 27- and 33-kDa subunits and showed strong ribosome-inactivating activity in vitro but did not show in vivo toxicity. The amino acid sequence of sieboldin-b deduced from the structure of the cDNA showed that both subunits of sieboldin-b are encoded on a single precursor polypeptide. Sieboldin-b has a structure homologous with the Neu5Ac(alpha 2-6)Gal/GalNAc-specific bark lectin from S. sieboldiana (SSA) and also typical type II RIPs such as ricin and abrin. Detailed analyses of carbohydrate binding properties of sieboldin-b revealed that sieboldin-b binds to Gal/GalNAc, similar to ricin/abrin, in spite of its highly homologous structure with SSA. The biological properties of these toxins/lectins are compared, and the possible explanation for such diversity is discussed.

Immunological aspects of nutritional diabetes prevention in NOD mice: a pilot study for the cow's milk-based IDDM prevention trial

Human epidemiological studies delineated early exposure to intact dietary protein (e.g., most infant formulas) as an environmental risk factor for the development of IDDM. The Trial to Reduce IDDM in the Genetically at Risk (TRIGR), an international IDDM prevention trial, has been designed to determine if avoidance of intact dairy protein in high-risk infants < or =6 months of age can reduce the subsequent diabetes incidence. We here studied the casein hydrolysate-based trial diet (Nutramigen) in NOD mice. When given either continuously or for 10 weeks after weaning, the test diet was highly effective in preventing autoimmune diabetes (32-week incidence: 4.6 vs. 58.8%) and in preserving pancreatic insulin levels, with little effect on islet inflammation. Spleen cells from protected NOD mice failed to adoptively transfer diabetes into irradiated syngeneic recipients. When co-transferred with splenocytes from diabetic donors, cells from diet-protected mice inhibited adoptive diabetes transfer (incidence 50 vs. 94%, P < 0.001). T-cell reactivity to the islet cell autoantigens ICA69 (islet cell antigen 69) and GAD65 developed only in diabetic recipients of spleen cell grafts, indicating that diabetes protection extends to more than one autoantigen. In protected mice, ICA69 T-cell reactivity was not detectable spontaneously nor after priming with this autoantigen; however, priming with the cross-reactive non-self-antigen bovine serum albumin recruited T-cells responsive to ICA69. Thus, diabetes prevention with the clinical trial diet is effective in NOD mice, where it affects some T-cell repertoires and allows development of regulatory cells that interfere with destructive autoimmunity.

Purification and characterization of a (1-->3)-beta-D-glucan endohydrolase from rice (Oryza sativa) bran

A (1-->3)-beta-glucanase with an apparent M(r) of 29,000 and an isoelectric point of 4.0 has been purified 2000-fold from extracts of rice bran, using fractional precipitation with ammonium sulfate, anion exchange chromatography, size-exclusion chromatography, chromatofocussing, and hydrophobic interaction chromatography. The enzyme can be classified with the EC 3.2.1.39 group, because it releases laminarabiose and higher laminara-oligosaccharides from linear (1-->3)-beta-D-glucans with an action pattern that is typical of (1-->3)-beta-D-glucan endohydrolases. However, the introduction of substituents or branching in the (1-->3)-beta-D-glucan substrates causes a marked decrease in the rate of hydrolysis. Thus, substituted or branched (1-->3)-beta-D-glucans of the kind commonly found in fungal cell walls are less susceptible to hydrolysis than essentially linear (1-->3)-beta-D-glucans. Kinetic analyses indicate an apparent Km of 42 microM, a kcat constant of 67 s-1, and a pH optimum of 5.0 during hydrolysis of the (1-->3)-beta-D-glucan, laminaran, from Laminaria digitata. The first 60 NH2-terminal amino acid residues of the purified rice (1-->3)-beta-glucanase contain blocks of amino acids that are conserved in other cereal (1-->3)-beta-glucanases. Although the precise tissue location and function of the enzyme in rice bran are not known, it is likely that it is concentrated in the aleurone layer and that it plays a preemptive role in the protection of ungerminated grain against pathogen attack.

Mitochondrial encephalomyopathy with elderly onset of stroke-like episodes

A 52-year-old woman with a history of a hearing disturbance since age 20 experienced visual hallucinations and convulsions, followed by right hemiparesis and aphasia. On the basis of a muscle biopsy and mitochondrial DNA analysis, she was diagnosed as mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS). This case is unique in that the stroke-like episodes occurred 30 years after disease onset.

Mutagenicity of 24-hour duplicate of Japanese diet

In order to elucidate the genotoxicological characteristics of the Japanese diet, the mutagenicity of 24-h duplicate of the diet samples were investigated. The mutagenicity of blue rayon extract was examined in the Ames Salmonella/microsome assay. Thirty-two (91.4%) of 35 samples revealed mutagenicity toward Salmonella typhimurium TA98 in the presence of S9 mix. The mutagenic activities showed significant correlations with the consumption rates of broiled fish (r = 0.517, p = 0.0021) and broiled meat (r = 0.494, p = 0.0036). In other test conditions, 6 (17.1%), 5 (14.3%) and 8 (22.9%) samples were mutagenic to Salmonella typhimurium TA98 without S9 mix, TA100 with S9 mix and TA100 without S9 mix, respectively. Findings in the present study suggest that high consumption of broiled fish and broiled meat are important as the source of mutagens/carcinogens in the Japanese diet. In the present study, however, biological inference of these findings could not be made in relation to the occurrence of cancers, especially of the gastric cancer, which is the most prevalent form of cancer in Japan.

Establishment and characterization of cell lines, MeMS and MeFS, derived from spontaneous rat mesotheliomas

New cell lines, designated MeMS and MeFS, were established from the epithelial type of mesotheliomas occurring spontaneously in aged male and female Fischer 344 rats, respectively. Morphologically, MeMS and MeFS expressed the epithelial phenotype. Coexpression of keratin and vimentin in both cell lines was confirmed by the immunocytochemistry, one-dimensional gel electrophoresis and immunoblotting for intermediate filament proteins. Hyaluronic acid synthesis of both MeMS and MeFS was demonstrated by the analysis using high-performance liquid chromatography. MeMS and MeFS seem to be useful models for studying the biological nature of rat mesotheliomas.

Purification and properties of a basic endo-1,3-beta-glucanase from rice (Oryza sativa L.)

A 1,3-beta-glucanase purified from rice grain is a 33 kDa monomer with a pI of > or = 10.4. The enzyme was determined to be an endo-1,3-beta-glucanase (EC 3.2.1.39) by end product analysis using Laminaria digitata laminarin as substrate. Its amino-terminal amino acid sequence revealed strong homology to an endo-1,3-beta-glucanase from barley.

Two novel genes rapidly and transiently activated in suspension-cultured rice cells by treatment with N-acetylchitoheptaose, a biotic elicitor for phytoalexin production

By using subtracted probes, two cDNA clones of rice, EL2 and EL3, were isolated as genes responsive within 6 min to N-acetylchitoheptaose, a potent biotic elicitor for phytoalexin biosynthesis. Analyses of the sequence of the cDNAs showed that both of EL2 and EL3 encoded basic proteins with no significant similarities to those of known genes.

A novel tetrasaccharide, with a structure similar to the terminal sequence of an arabinogalactan-protein, accumulates in rice anthers in a stage-specific manner

Analysis of free sugars in developing rice anthers by high-performance anion-exchange chromatography (HPAEC) showed that a very high concentration of a novel oligosaccharide accumulated specifically during microsporogenesis. Structural analysis of the purified oligosaccharide by methylation analysis, mass spectrometry/mass spectrometry (MS/MS), and nuclear magnetic resonance (NMR) spectroscopy revealed its structure to be beta-L- Ara(f)-(1-->3)-alpha-L-Ara(f)-(1-->3)-beta-D-Gal(p)-(1-->6)-D-Gal, which is closely related to a tetrasaccharide unit found in the glycan chain of a plant cell surface proteoglycan, the arabinogalactan-protein (AGP). Chilling treatment (12 degrees C, 4 days), which injures rice anthers during microsporogenesis, decreased the concentration of the tetrasaccharide, but the sucrose level increased. This effect was especially evident in a chilling-sensitive mutant line, YM56-1. These results suggest that this unique tetrasaccharide may play an important role in both the development of the rice anther and its response to chilling.

[Effects of propofol on contractility and electrophysiological properties of canine single cardiomyocytes]

We assessed the effects of propofol on contraction, action potentials and Ca2+ currents (Ica) in single ventricular cells in dog. Low concentrations of propofol 10(-5)M had no effects on contractile responses, but high doses above 10(-4)M of propofol decreased contractions. Propofol 10(-3)M reduced the duration of action potentials (time to 90% repolarization). Ica was decreased by propofol 10(-4)M without accompanying use-dependent manner. The present study indicates that clinical concentrations of propofol do not exert direct negative inotropic effects, but at supratherapeutic concentrations it inhibits cardiac contractility.

Involvement of Jasmonic Acid in Elicitor-Induced Phytoalexin Production in Suspension-Cultured Rice Cells

It has been suggested that jasmonic acid (JA) could be an integral part of a general signal transduction system regulating inducible defense genes in plants. It was reported that treatment with an elicitor (N-acetylchitoheptaose) induced production of phytoalexin in suspension-cultured rice (Oryza sativa L.) cells. In this study, the role of JA in the induction of phytoalexin production by N-acetylchitoheptaose was investigated. Exogenously applied ([plus or minus])-JA (10-4 M) clearly induced the production of momilactone A, a major phytoalexin, in suspension-cultured rice cells. On the other hand, in rice cells treated with N-acetylchitoheptaose, endogenous JA was rapidly and transiently accumulated prior to accumulation of momilactone A. Treatment with ibuprofen, an inhibitor of JA biosynthesis, reduced production of momilactone A in the cells treated with N-acetylchitoheptaose, but the addition of ([plus or minus])-JA increased production of momilactone A to levels higher than those in the elicited rice cells. These results strongly suggest that JA functions as a signal transducer in the induction of biosynthesis of momilactone A by N-acetylchitoheptaose in suspension-cultured rice cells.

Sialylated oligosaccharide-specific plant lectin from Japanese elderberry (Sambucus sieboldiana) bark tissue has a homologous structure to type II ribosome-inactivating proteins, ricin and abrin. cDNA cloning and molecular modeling study

Bark lectins from the elderberry species belonging to the genus Sambucus have a unique carbohydrate binding specificity for sialylated glycoconjugates containing NeuAc(alpha 2-6)Gal/GalNAc sequence. To elucidate the structure of the elderberry lectin, a cDNA library was constructed from the mRNA isolated from the bark tissue of Japanese elderberry (Sambucus sieboldiana) with lambda gt11 phage and screened with anti-S. sieboldiana agglutinin (SSA) antibody. The nucleotide sequence of a cDNA clone encoding full-length SSA (LecSSA1) showed the presence of an open reading frame with 1902 base pairs, which corresponded to 570 amino acid residues. This open reading frame encoded a signal peptide and a linker region (19 amino acid residues) between the two subunits of SSA, the hydrophobic (A-chain) and hydrophilic (B-chain) subunits. This indicates that SSA is synthesized as a preproprotein and post-translationally cleaved into two mature subunits. Homology searching as well as molecular modeling studies unexpectedly revealed that each subunit of SSA has a highly homologous structure to the galactose-specific lectin subunit and ribosome-inactivating subunit of plant toxic proteins such as ricin and abrin, indicating a close evolutionary relationship between these carbohydrate-binding proteins.

Establishment and characterization of a cell line (NB-YK) derived from a transplantable rat nephroblastoma

A new cell line, designated NB-YK, was established from a transplantable rat nephroblastoma (NB-Y) which was derived from a spontaneous nephroblastoma in an aged Fischer 344 rat. NB-YK grew in a piling-up and noncohesive pattern on the plastic surface and formed colonies in a soft agar. The main cell type of NB-YK represented morphology of mesenchymal phenotype and most of the cells contained several secretory granules in their cytoplasm. Immunocytochemically the cells were positive for vimentin, cytokeratin, and laminin. Coexpression of vimentin and cytokeratin in the cells was confirmed by the one-dimensional gel electrophoresis and immunoblotting for intermediate filament proteins. NB-YK cells were tumorigenic and produced fibrosarcoma-like tumor when inoculated subcutaneously or intraperitoneally into syngeneic rats and nude mice. NB-YK seems to be a useful model for studying biological properties of nephroblastoma.

Differences in midazolam-induced breathing patterns in healthy volunteers

Sex differences, and the influence of drug dosage and additional upper airway obstruction were studied in midazolam-induced breathing patterns and sedation in 30 healthy volunteers (8 males and 22 females). After administration of 0.1 mg.kg-1 midazolam (8 male and 8 female subjects), the rib cage (RC) motion increased in 6 males and the abdominal wall (ABD) motion and SaO2 decreased in all males. In contrast, the RC and ABD motions and SaO2 decreased in all females. Snoring and loss of consciousness occurred in 7 males and in 2 females. There were significant differences in the RC motion, SaO2, the incidence of snoring and the sedative state between male and female subjects. A bolus dose of 0.5 mg of flumazenil completely antagonized the sedative effect of midazolam and restored the breathing pattern, whereas it did not completely restore SaO2. A higher dose (0.2 mg.kg-1) of midazolam was administered to an additional 8 females. It caused a loss of consciousness in all subjects and increased the RC motion in only one subject. Partial obstruction of the nasal cavity was effected with cotton balls in the remaining 6 females who were sedated with 0.1 mg.kg-1 midazolam. An increase in the RC motion occurred similar to that observed in males. These findings suggest a difference in midazolam-induced sedation and breathing patterns between male and female subjects with midazolam administration on a mg.kg-1 basis.

(+/-)-(Z)-2-(aminomethyl)-1-phenylcyclopropanecarboxamide derivatives as a new prototype of NMDA receptor antagonists

(+/-)-(Z)-2-(Aminomethyl)-1-phenylcyclopropane-N,N-diethylcarbo xamide (milnacipran, 1), a clinically useful antidepressant, and its derivatives were prepared by an improved method and were evaluated as NMDA receptor antagonists. Of these, milnacipran (1), its N-methyl and N,N-dimethyl derivatives, 7 and 8, respectively, and its homologue 12 at the aminomethyl moiety had binding affinity for the receptor in vitro (IC50: 1, 6.3 +/- 0.3 microM; 7, 13 +/- 2.1 microM; 8, 88 +/- 1.4 microM; 12, 10 +/- 1.2 microM). These also protected mice from NMDA-induced lethality. These compounds would be important as anovel prototype for designing potent NMDA-receptor antagonists because of their characteristic structure, which clearly differentiated them from known competitive and noncompetitive antagonists to the receptor.

Conformation of an arabinoxylan isolated from the rice endosperm cell wall by X-ray diffraction and a conformational analysis

The chain conformation of an arabinoxylan isolated from the rice endosperm cell wall, which was composed of the linear backbone of a 1,4-linked beta-xylose residue highly substituted at the C3 position with alpha-L-arabinofuranose, was studied by X-ray fiber diffraction and a conformational analysis. From the X-ray results the polysaccharide was suggested to take an extended left-handed, three-fold helical structure which is not a desirable conformation to make a complex firmly associated with cellulose or xyloglucan that was elucidated to be present in the cell wall. A conformational analysis, using the PFOS force field for the O-alpha-L-arabinofuranose-(1-->3)-beta-D-xylose residue and O-alpha-L-arabinofuranose-(1-->3)-[(1-->4)-beta-D-xylose residue]3, in which the arabinose residue was linked to the C3 position of the middle residue of the xylotriose residue, and using the PS79 computer program for the arabinoxylan indicated that the backbone xylan chain could not take a two-fold helix similar to that of cellulose because of significant steric interaction between the arabinose side chain and the backbone. Thus, the left-handed, three-fold helix was found to be reasonable.

Different muscle specific promoter characteristics in two sibs with Duchenne muscular dystrophy

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[Effects of bupivacaine on Na+ and Ca2+ currents in single canine ventricular cells]

The effects of bupivacaine on Na+ and Ca2+ currents in single canine isolated left ventricular cells were examined using whole-cell voltage clamp technique to reveal the mechanism of its negative inotropism. The cells were isolated by enzymatic dispersion and superfused in an oxygenated Tyrode's solution. Bupivacaine 10(-6) M decreased the amplitude of INa and delayed the peak time. These effects were dose and frequency dependent. At a concentration of 10(-3) M, bupivacaine abolished INa. Meanwhile, bupivacaine did not modify ICa at a concentration of 10(-6) M. At 10(-5) M bupivacaine, the amplitude of ICa was depressed by 22% and the depression was dose dependent. These results suggest that low concentration (10(-6) M) of bupivacaine depresses contraction, by reducing intracellular Ca2+ secondary to reduction in intracellular Na+ activity and the Na+-Ca2+ exchange mechanism. At higher concentrations, the reduction in contraction caused by bupivacaine may result partly from a reduced influx of Ca2+.

Repulsive contribution of surface sialic acid residues to cell adhesion to substratum

Roles of surface sialic acid residues in cell adhesion to substratum were investigated in model systems to clarify their contribution to intercellular interactions. Treatment of cells of a fibroblastic cell line, Swiss 3T3, an epithelial cell line, TES-1, and a T lymphoma cell line, BW5147, with a sialylated oligosaccharide binding lectin enhanced adhesion to plastic plates irrespective of the cell lineage. This enhancement was inhibited by the addition of sialyl lactose. Digestion of the cells with sialidase or endoglycoceramidase also augmented adhesion. On the other hand, adhesion was reduced by pre-coating plastic plates with gangliosides but not with desialylated gangliosides. These findings suggest that sialic acid residues exposed to cell surfaces negatively regulate cell adhesiveness.

Immunoadsorption therapy for myasthenia gravis

The results of a multicentre trial were analysed to evaluate the efficacy of immunoadsorption therapy for severe generalised myasthenia gravis. Twenty patients with myasthenia gravis who were concurrently receiving high dose prednisolone and azathioprine therapy were treated with an affinity-type adsorbent, using tryptophan-linked polyvinyl alcohol gel (IM-TR), according to a standardised treatment protocol. The 20 patients received five adsorption treatments within a period of 10 days. In 11, pronounced improvement of myasthenic weakness was seen and long-term remission was maintained. The treatment was especially effective in patients with thymic hyperplasia. Circulating acetylcholine receptor (AChR) antibodies were reduced by about 60% by treating one plasma volume. There was no difference in the rate of removal of the AChR antibodies between patients with thymic hyperplasia and patients with thymoma. No serious complications occurred during 100 procedures. It was concluded that the immunoadsorption therapy with IM-TR is useful in controlling symptoms in patients with severe myasthenia gravis who are otherwise unresponsive.

[Effect of sevoflurane on contraction and membrane potentials in canine right ventricular myocytes]

The effects of sevoflurane on contraction and membrane potentials were studied in isolated canine ventricular muscle strips. Sevoflurane depressed electrically-induced contraction in a dose-dependent manner. The inhibitory effect was more pronounced in high-K+ Tyrode solution than in normal Tyrode solution suggesting that sevoflurane inhibits transmembrane Ca2+ influx. In electrophysiological studies, sevoflurane depressed both overshoot and the plateau phase of action potentials. Resting membrane potential was not affected by sevoflurane. We conclude that the depression of myocardial contractility by sevoflurane may be due to block of transmembrane calcium influx.

[Inhibitory action of bupivacaine on cardiac contraction]

We studied the effects of bupivacaine on the contractility and membrane potentials in isolated dog papillary muscle. Bupivacaine (10(-6)-10(-4) M) produced dose-dependent depression of twitch tension elicited by electrical stimulation. These inhibitory effects were greater at high frequencies of stimulation (2, 3 Hz) than at low frequencies (less than 1 Hz). Bupivacaine did not alter the resting membrane potential, but produced a reduction in Vmax of the action potentials, in a dose-dependent and reversible manner (concentrations from 10(-6) to 10(-4) M). Bupivacaine 10(-4) M often blocked the fast action potentials in normal Tyrode's solution. In high K+ (26 mM) Tyrode's solution, bupivacaine inhibited both slow action potentials and associated contractions in the presence of isoproterenol. These results suggest that low concentrations of bupivacaine decreases the contraction mainly due to Na+ channel block, whereas at higher concentration, this anesthetic may block Ca2+ channels. In addition, isoproterenol may be clinically effective in the treatment of bupivacaine cardiotoxicity due to stimulation of Ca2+ mediated slow action potentials through beta-receptors.

Mutagenicity of activated carbon adsorbate of drinking water in the Ames assay

Mutagenicity of activated carbon adsorbate from drinking water collected in Niigata City was assayed by the Ames assay. Adsorbate was extracted from activated carbon with benzene, and then with ethanol. Although the benzene extract was not mutagenic, the ethanol one showed the mutagenic activity for Salmonella typhimurium strains TA98 and TA100 with and without S9 mix. The ethanol extract was much more mutagenic on TA100 than TA98 both with and without S9 mix. The mutagenic activity per liter of water was found to be the strongest in winter and the weakest in summer.

Effects of bupivacaine on contraction and membrane potential in isolated canine papillary muscles

The effects of bupivacaine on myocardial contraction and membrane potential were examined in isolated canine right ventricular papillary muscles. Bupivacaine (10(-6) to 10(-4) mol/l) produced a dose-dependent and reversible decrease in the electrically induced contractile response of canine right ventricular papillary muscles. The inhibitory effects of bupivacaine on contraction were more pronounced at high stimulation frequencies (2 and 3 Hz) than at low frequency (< 1 Hz). The resting membrane potential was not affected by bupivacaine. The maximal upstroke velocity of the action potential was reduced by 10(-6) mol/l bupivacaine (74 +/- 28% of control), and these effects were also dose dependent. At 10(-4) mol/l, bupivacaine blocked fast action potentials in normal Tyrode's solution. Furthermore, bupivacaine (10(-4) and 10(-3) mol/l) decreased both slow action potential duration and associated contractions in high-K+ (26 mmol/l) Tyrode's solution in the presence of isoproterenol. Our results suggest that low concentrations of bupivacaine depress contraction mainly due to an Na+ channel block, whereas at higher concentration, this local anesthetic may block Ca2+ channels.

Identification of a novel high-affinity binding site for N-acetylchitooligosaccharide elicitor in the membrane fraction from suspension-cultured rice cells

Binding experiments using a 125I-labeled tyramine conjugate of N-acetylchitooctaose, a highly potent elicitor for the induction of phytoalexin production in rice cells, and a microsomal membrane preparation from suspension-cultured rice cells showed the presence of a novel high-affinity binding site for this oligosaccharide. The binding of the ligand was saturable and the Scatchard plot analysis of the results indicated the presence of a single class of binding site with a Kd of 5.4 nM which is comparable with that reported for the binding of the hepta-beta-glucoside elicitor in soybean membrane. The ligand binding was inhibited by unlabeled N-acetylchitoheptaose but not by its deacetylated form. These characteristics of this binding site coincide well with the specificity and sensitivity for the elicitor in several assay systems, suggesting the possible involvement of this binding site in the recognition of the elicitor in vivo.

Identification of a novel high-affinity binding site for N-acetylchitooligosaccharide elicitor in the membrane fraction from suspension-cultured rice cells

Binding experiments using a 125I-labeled tyramine conjugate of N-acetylchitooctaose, a highly potent elicitor for the induction of phytoalexin production in rice cells, and a microsomal membrane preparation from suspension-cultured rice cells showed the presence of a novel high-affinity binding site for this oligosaccharide. The binding of the ligand was saturable and the Scatchard plot analysis of the results indicated the presence of a single class of binding site with a Kd of 5.4 nM which is comparable with that reported for the binding of the hepta-beta-glucoside elicitor in soybean membrane. The ligand binding was inhibited by unlabeled N-acetylchitoheptaose but not by its deacetylated form. These characteristics of this binding site coincide well with the specificity and sensitivity for the elicitor in several assay systems, suggesting the possible involvement of this binding site in the recognition of the elicitor in vivo.

Direct kinetics of bait region cleavage of alpha-2-macroglobulin by a rapid quenching method

The rate of bait region cleavage of human alpha-2-macroglobulin by chymotrypsin was determined by a rapid quenching method under conditions where the bimolecular encounter between the two reactants was not rate-limiting. alpha 2M was first mixed with a 30 molar excess of chymotrypsin in a sequential stopped-flow apparatus and after programmed time intervals the activity of chymotrypsin was quenched with 1 N HCl. The fraction of uncleaved subunits was quantitated by SDS-PAGE under reducing conditions. The result indicated that the bait region cleavage proceeded following a two-exponential decay curve with respective rate constants of k1 = 40 s-1 and k2 = 2 s-1.

Monomeric, monovalent derivative of Maackia amurensis leukoagglutinin. Preparation and application to the study of cell surface glycoconjugates by flow cytometry

A stable subunit of Maackia amurensis leukoagglutinin (MMAL) was prepared by the selective reduction of disulfide bridges between the subunits followed by alkylation with 4-vinylpyridine. MMAL failed to precipitate fetuin, whereas it retained its ability to bind to the same glycoprotein coated on a plastic plate, indicating the monovalency of this derivative. This binding to immobilized fetuin was inhibited by a haptenic sugar, Neu5Ac alpha 2-3lactose, with the same inhibitory potency as against the native M. amurensis leukoagglutinin. Microscopic observation as well as flow cytometric analyses showed that Chinese hamster ovary cells were clearly stained with fluorescein isothiocyanate-labeled MMAL without any detectable agglutination. This staining was inhibited by the addition of fetuin or by the sugar chains of fetuin. Differences in the types of sialylated glycoconjugates on the cell surface of several cell lines were detected by the combined use of fluorescein isothiocyanate-labeled MMAL and the monomeric derivative of elderberry bark lectin (specific for the Neu5Ac alpha 2-6Gal/GalNAc sequence) by flow cytometry. These results demonstrate the usefulness of these monovalent derivatives of sialylated oligosaccharide-specific lectins as probes for the analysis of cell surface glycoconjugates containing sialic acid by the technique of flow cytometry.

[Electrophysiological effects of ketamine on Ca(2+)-activated K+ channel in single rabbit portal vein cell]

The effects of ketamine on Ca(2+)-activated K+ channel currents were studied in dispersed single smooth muscle cells from rabbit portal vein using inside-out patch clamp technique. In a near physiological K+ and Ca2+ gradient, three populations of outward rectangular single currents were recorded in isolated cell membrane of rabbit portal vein at +60 mV membrane potential. These currents were judged as Ca(2+)-activated K+ channel currents since application of EGTA or Apamin in the internal solution inhibited these currents. Application of 10(-5)M or 10(-4)M ketamine inhibited the number of occurrences of channel opening and decreased open times, but did not reduce the amplitudes. When the 10(-3)M ketamine was applied, the Ca(2+)-activated K+ channel currents were abolished. We suggest that the depression of Ca(2+)-activated K+ channel currents may explain the continuous contraction observed in rabbit portal vein at a clinical concentration of ketamine from a point of electrophysiological K+ current study.

Actions of benzalkonium chloride as a potent depressant at the neuromuscular junction

Benzalkonium chloride (BA), a positively charged surface active agent, applied (> 10 nM) in the superfusing solution, produced a concentration-dependent reduction in the amplitude of both evoked endplate potentials (EPPs) and spontaneous miniature EPPs of the frog. Voltage-clamped endplate currents (EPCs) and spontaneous miniature endplate currents (MEPCs) were also diminished in amplitude, in the presence of BA (50-140 nM), whereas their time-course and reversal potential were not obviously affected. No significant change due to the addition of 50 nM BA was observed in apparent properties of the ACh channel estimated from ACh-induced current fluctuations. In the relationship between the amplitude of ACh potentials and the net charge for iontophoretic pulses at a single junction, the principal pattern of action of BA (30-60 nM) appeared to be a parallel shift to the right. At concentrations greater than about 1 microM, BA slightly increased the resting input conductance of the non-synaptic muscle fibre membrane. It was suggested that this increase was attributable to a slight increase in Cl ion conductance of the non-synaptic membrane. These results indicate that BA effectively blocked neuromuscular transmission, acting as an ACh receptor antagonist at smaller concentrations and as a more potent blocker that acts through multiple sites at greater concentrations.

Evaluation of myocardial damage in Duchenne's muscular dystrophy with thallium-201 myocardial SPECT

Myocardial damage and cardiopulmonary functions in patients with Duchenne's muscular dystrophy (DMD) were assessed using thallium-201 myocardial single-photon emission computed tomography (SPECT) and technetium-99m multigated radionuclide angiography. Twenty-five patients with DMD were divided into 4 groups according to percent of perfusion defect (%PD) calculated by the bull's-eye method and age. PD was detected in 24 (96.0%) of 25 patients with DMD, and it spread from the left ventricular lateral wall to the anterior wall and/or interventricular septum. PD was detected even in a 6-year-old DMD boy. Patients in Group I (%PD > or = 10 and age < 15 years old) were shown to have a higher risk of left-sided heart failure without respiratory failure. Patients in Group II (%PD > or = 10 and age > or = 15) showed decreased pulmonary function and worsened arterial blood gas values as compared with Group IV (%PD < 10 and age > or = 15). There was no significant difference in cardiac function among the 4 groups. It is postulated that myocardial damage in Group II patients is dependent primarily on a deficiency of dystrophin and on chronic respiratory failure, and that some of them are at risk of cardiopulmonary failure. It is concluded that myocardial SPECT is useful for the early diagnosis of myocardial damage and evaluation of cardiopulmonary function in DMD patients.

Preparation of a stable subunit of Japanese elderberry (Sambucus sieboldiana) bark lectin and its application for the study of cell surface carbohydrates by flow cytometry

A stable subunit of Sambucus sieboldiana bark lectin (MSSA) was prepared by selective reduction of disulfide bridges between the subunits and alkylation with 4-vinylpyridine. Amino acid analysis of MSSA revealed that 1.4 cysteine residues per subunit were selectively modified. MSSA failed to agglutinate rabbit erythrocytes and precipitate fetuin. However, MSSA retained the ability to bind to fetuin, as detected by ELISA. Neu5Ac alpha 2-6lactose inhibited the binding to fetuin of both SSA and MSSA. Flow cytometric analysis showed that human histocytic lymphoma U937 cells were clearly stained with FITC-labeled MSSA (FITC-MSSA) without any detectable agglutination and that this staining was almost completely inhibited by the addition of Neu5Ac alpha 2-6lactose (2 mM). Treatment of U937 cells with native FITC-SSA at the sub-agglutinating concentration (0.3 microgram/ml) showed much poorer fluorescence intensity than that of MSSA, suggesting that MSSA is an invaluable tool for the detection of cell surface glycoconjugates containing NeuAc alpha 2-6Gal/GalNAc sequences by flow cytometry.

The interaction of elderberry (Sambucus sieboldiana) bark lectin and sialyloligosaccharides as detected by 1H-NMR

The interaction of Japanese elderberry bark lectin (Sambucus sieboldiana agglutinin, SSA) with carbohydrate was investigated by 1H-NMR. When a low affinity ligand, methyl beta-D-galactoside (beta MeGal), was mixed with SSA, each proton signal of beta MeGal was broadened. The signal of H-4 was markedly broad, while those of H-1, OCH3, and H-2 of beta MeGal were rather sharp. The specific broadening of Gal H-4 was more evident when SSA was mixed with methyl-beta-D-lactoside (beta MeLac). Position-dependent signal broadening suggests that beta MeGal binds to SSA such that H-4 is closely involved in the contact region, but H-1, OCH3, and H-2 are far from this region. In the case of a high affinity ligand, Neu5Ac(alpha 2-6)Gal(beta 1-4)Glc(= N6L), ligand signals of the SSA-N6L mixture did not change at all. But when a small amount of N6L was added to the SSA-beta MeGal mixture, the broad signals of bound beta MeGal became dramatically sharp. This indicates that the added N6L molecules liberated the bound beta MeGal from SSA. On the other hand, the sialyllactose with the alpha(2-3)-linkage(= N3L) could not substitute for bound beta MeGal because of its lower affinity. This demonstrates that the competitive binding experiment between two ligands is a useful technique to detect the interaction of lectins with high affinity ligands which could not be observed directly by NMR signal broadening and/or chemical shift change.

Effects of ketamine on voltage-dependent Ca2+ currents in single smooth muscle cells from rabbit portal vein

The effects of ketamine on membrane potentials and long-lasting type (L-type) voltage-dependent Ca2+ currents were investigated in dispersed single smooth muscle cells from rabbit portal veins. The amplitude and duration of the action potentials evoked by intracellular stimulation were inhibited by ketamine and were completely blocked by 10(-3) mol/l ketamine. Ketamine, however, did not alter the resting membrane potential. Whole cell voltage clamp experiments revealed that ketamine at concentrations higher than 10(-4) mol/l reduced the peak L-type voltage-dependent Ca2+ currents. These effects of ketamine were concentration-dependent and reversible at concentrations from 10(-4) to 10(-3) mol/l. Moreover, the activation threshold of L-type Ca2+ current (approximately -30 mV) was slightly shifted to the positive potential side by ketamine. This effect can explain that the action potential was abolished by 10(-3) mol/l ketamine. It is concluded that relaxation of the vascular smooth muscle by ketamine may have to be attributed to the inhibition of L-type voltage-dependent Ca2+ current.

Gene-deletion and carrier detections, and prenatal diagnosis of Duchenne muscular dystrophy by analysis of the dystrophin gene amplified by polymerase chain reaction

Polymerase chain reaction (PCR)-based diagnosis was carried out in 62 patients (57 probands) with Duchenne or Becker muscular dystrophy (DMD or BMD) and 226 members in 57 families. The PCR studies were also performed for carrier detection in 57 mothers and 58 sisters, and prenatal diagnosis of 4 fetuses at risk of DMD. The PCR with 7 sets of primers, which amplify 7 different exon-sequences of the dystrophin gene, detected gene deletion of at least one exon in 49% of the probands. The PCR with the other 4 primer sets, which amplify 3 intragenic loci, and subsequent endonuclease digestion detected in 84% of the mothers a heterozygous pattern in at least one such locus/segment. Using the same primer sets, carrier detection was successful in 5 sisters of familial DMD cases, while recombination between the ERT87 and the 3' end intragenic loci was observed in 11% of family members studied. Prenatal diagnosis was made in all the 4 fetuses; two males were affected, one male fetus non-affected, and the remaining one female fetus a carrier. Thus, the PCR study and the primers used in the present study are useful and convincing for rapid diagnosis of DMD and/or BMD.

6-Deoxy-D-talan and 6-deoxy-L-talan. Novel serotype-specific polysaccharide antigens from Actinobacillus actinomycetemcomitans

Serotype-specific polysaccharide antigens from Actinobacillus actinomycetemcomitans ATCC 29523 (serotype a) and NCTC 9710 (serotype c) were extracted from whole cells by autoclaving and purified by ion-exchange chromatography and gel filtration. Analysis of component sugars by gas-liquid chromatography-mass spectrometry, high performance liquid chromatography, and NMR together with optical rotation data showed that the serotype a antigen was composed solely of 6-deoxy-D-talose, whereas the serotype c antigen consisted of 6-deoxy-L-talose. Structural analysis indicated that both of these antigens were composed of closely related repeating units, -3)-6-deoxy-alpha-D-Talp-(1-2)-6-deoxy-alpha-D-Talp-(1-(sero type a) and -3)-6-deoxy-alpha-L-Talp-(1-2)-6-deoxy-alpha-L-Talp-(1-(sero type c). 1H and 13C NMR analysis showed that both of these serotype antigens contained one acetyl group/2 sugar residues. These acetyl groups localized at the O-2 position of 3-linked 6-deoxy-D-talose (serotype a) or O-4 position of 3-linked 6-deoxy-L-talose residues (serotype c), respectively. These results coupled with our previous findings on the serotype b antigen (Amano, K., Nishihara, T., Shibuya, N., Noguchi, T., and Koga, T. (1989) Infect. Immun. 57, 2942-2946) showed that the serotype antigens from A. actinomycetemcomitans are a group of novel polysaccharides with structural features closely related biosynthetically.

[Mutagenicity of rice-straw and -husk ashes by Ames test]

In the rice-producing district of Japan, environmental pollution by smoke from burnt rice straws has become a matter of concern. The mutagenicity of fly- and bottom-ashes of rice-straw and -husk was assayed by the Ames test, TA100 +/- S9 and TA98 +/- S9, and the relationship of combustion temperature to mutagenicity was investigated. Fly ash showed weak mutagenicity at 300 degrees C, with no remarkable change in mutagenic activity between 300 degrees C and 500 degrees C. Above 500 degrees C the mutagenic activity increased with a rise of temperature. The increasing rate of mutagenicity was much higher in the test system with S9 mix than that without S9. Moreover, the mutagenicity with TA100 was stronger than with TA98. With respect to bottom ash, weak mutagenic activity was observed at 300 degrees C, but at 400 degrees C decreased and at 500 degrees C or above could not be observed. Fly ash derived from burning 1 g of rice straw at 600 degrees C showed about 14 times and 2.5 times higher mutagenicity than main stream smoke condensates from the burning of 1 g of cigarette in TA100 + S9 and TA98 + S9 test systems respectively.