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Biomedical subjects

Y Arakawa

Publications and source records attributed to Y Arakawa.

At least 19 recordsLinked to original sources
PubMed1992

Mechanisms of antibacterial action of tachyplesins and polyphemusins, a group of antimicrobial peptides isolated from horseshoe crab hemocytes.

Tachyplesins I and II and polyphemusins I and II, cationic peptides isolated from the hemocytes of horseshoe crabs, show bactericidal activities with similar efficiencies for both gram-negative and gram-positive bacteria. Tachyplesin I inhibited bacterial growth irreversibly within 40 min. A subinhibitory concentration of tachyplesin I sensitized gram-negative bacteria to the bactericidal actions of novobiocin and nalidixic acid, although polymyxin B-resistant strains which have altered lipopolysaccharides were susceptible to tachyplesin I. This implies that tachyplesin permeabilizes the outer membrane and that the likely target of its action is outer membrane constituents other than lipopolysaccharides. On the other hand, a defensin-susceptible phoP strain of Salmonella typhimurium was also susceptible to tachyplesin I. Tachyplesin I rapidly depolarized the inverted inner-membrane vesicles of Escherichia coli. These results suggest that depolarization of the cytoplasmic membrane, preceded by the permeabilization of the outer membrane for gram-negative bacteria, is associated with tachyplesin-mediated bactericidal activity. The similarity between the actions of tachyplesin and those of defensin was discussed.

Animals↗
PubMed1992

Involvement of rcsB in Klebsiella K2 capsule synthesis in Escherichia coli K-12.

Escherichia coli K-12 harboring a part of the structural genes for the Klebsiella K2 capsular polysaccharide (cpsK*) expresses a large amount of K2 capsular polysaccharide as a thick capsule in the presence of plasmids carrying rmpA and rcsB. We have previously shown that expression of the Klebsiella K2 capsule in E. coli HB101 harboring cpsK* depends on the presence of rmpA, a regulatory gene from a large plasmid of Klebsiella pneumoniae Chedid (O1:K2). E. coli K-12 JM109, however, produces only a small amount of K2 capsular polysaccharide, even in the presence of plasmids carrying rmpA as well as the cpsK* structural genes. Introduction of the rcsB gene, a positive regulator of colanic acid capsule synthesis in E. coli K-12 which was cloned from HB101 on a plasmid, into JM109 cells carrying cpsK* and rmpA, results in the expression of a thick K2 capsule. By Northern (RNA) hybridization analysis, rcsB has been found to enhance transcription of a long strand of mRNA (longer than 14 kb) from cpsK*. These E. coli transformants which produce a thick K2 capsule also express colanic acid production at high levels. Therefore, rcsB can act as a positive regulator of Klebsiella K2 capsule production and two capsular polysaccharides can be expressed in E. coli simultaneously. With a somewhat different strain background, we have found that both of the colanic acid regulators, rcsA and rcsB, contribute to the basal level of Klebsiella K2 capsule expression but that the presence of multicopy rcsB in either an rcsB or an rcsA mutant of E. coli is sufficient to increase the expression of K2 capsular polysaccharide. These results suggest further parallels between the regulation of colanic acid synthesis in E. coli and the regulation of Klebsiella K2 capsule synthesis.

Bacterial Capsules↗
PubMed1992

[The significance of the determination of AFP-isoform in the early diagnosis of hepatocellular carcinoma].

To evaluate the significance of the determination of the AFP-isoform in the early diagnosis of hepatocellular carcinoma (HCC), the AFP-isoform was determined in 48 patients with HCC and in 53 patients with liver cirrhosis, using the lectin electrophoresis of AFP by antibody-affinity blotting technique. 1. The HCC-type AFP-isoform was detected in 44 of the 48 patients with HCC, 2. In about 30% of the patients with HCC, the HCC-type AFP-isoform appeared 3-10 months before the graphic diagnosis of HCC, 3. In about 60% of the patients with liver cirrhosis found to have the HCC-type AFP-isoform, HCC developed within one year. Thus, the serial determination of the AFP-isoform in patients with liver cirrhosis was considered very useful for the early diagnosis of HCC.

Carcinoma, Hepatocellular↗
PubMed1992

[A case of sarcoidosis presenting with Heerfordt's syndrome, associated with hepatosplenomegaly, pleural effusion, and ascites].

A 30-year-old female developed symptoms consistent with Heerfordt's syndrome (complete type) and was effectively treated with steroid. However, she developed hepatosplenomegaly, bloody pleural effusion, and ascites one year after discontinuation of steroid therapy. The symptoms were considered to be due to sarcoidosis since serum ACE level, and ACE level and OKT4/8 ratio in pleural and peritoneal effusions were significantly elevated, and readministration of steroid normalized these changes. Bloody pleural and peritoneal effusions are very rare complications of sarcoidosis.

Adult↗
PubMed1991

Construction of a novel suicide vector: selection for Escherichia coli HB101 recombinants carrying the DNA insert.

We constructed a new type of cloning vector, pERISH2, that transforms Escherichia coli HB101 only when a foreign DNA fragment is ligated into the cloning site of the plasmid vector. Plasmid pERISH2 carries the rcsB gene which is derived from the chromosome of E. coli HB101 and is involved in the regulation of colanic acid production. When E. coli HB101 is transformed by this vector carrying the intact rcsB gene, the gene product RcsB blocks bacterial growth. However, if the rcsB gene is inactivated by the insertion of a foreign DNA fragment, this recombinant plasmid no longer inhibits the growth of E. coli HB101. Although E. coli HB101 is not stably transformed by pERISH2, E. coli K-12 strains such as JM109 and C600 can harbor this vector. Therefore, pERISH2 can be amplified in JM109 and be prepared from this strain in a large quantity using conventional methods. A chromosomal gene library of Klebsiella pneumoniae is constructed easily and efficiently by the utilization of this new cloning vector.

Blotting, Southern↗
PubMed1991

Transport of exogenous fluorescent phosphatidylserine analogue to the Golgi apparatus in cultured fibroblasts.

We have examined intracellular transport and metabolism of the fluorescent analogue of phosphatidylserine, 1-palmitoyl-2-(N-[12[(7-nitrobenz-2-oxa-1,3-diazole-4-yl)amino] dodecanoyl])-phosphatidylserine ([palmitoyl-C12-NBD]-PS) in cultured fibroblasts. When monolayer cultures were incubated with liposomes containing (palmitoyl-C12-NBD)-PS at 37 degrees C, fluorescent PS was transported to the Golgi apparatus. NBD-containing analogues of phosphatidylcholine, phosphatidylethanolamine (PE), or phosphatidic acid did not accumulate in the Golgi apparatus under the same experimental conditions. We suggest that the transport is not due to endocytosis, but is the result of incorporation and trans-bilayer movement of the (palmitoyl-C12-NBD)-PS at the plasma membrane followed by translocation of the lipid from plasma membrane to the Golgi apparatus via nonvesicular mechanisms. Uptake of fluorescent PS was inhibited by depletion of cellular ATP and was blocked by structural analogues of the lipid or by pretreatment of cells with glutaraldehyde or N-ethylmaleimide. After incorporation into the cell, fluorescent PS was metabolized to fluorescent PE. The intracellular distribution of fluorescence changed during the conversion. In addition to the Golgi apparatus, mitochondria also became labeled.

Animals↗
PubMed1991

A case of cutaneous metastases of gastric carcinoma showing peculiar clinical features.

A 52-year-old male patient presented with multiple cutaneous nodules on the face, trunk, and upper extremities. Examination of a skin biopsy specimen disclosed numerous signet ring cells throughout the dermis. Histopathologic examination of the stomach, along with gastroscopy, revealed that the cutaneous metastases were of gastric origin. The metastatic skin lesion on the shoulder and the back of the patient grew relatively rapidly, showing an erysipelas-like lesion followed by prominently large tumor masses. The clinical appearance seen in our case is thought to be rare. Radiotherapy and chemotherapy appeared to be effective in reducing some tumors and the swelling on the anterior of the neck, and in prolonging life.

Adenocarcinoma↗
PubMed1991

Cloning and expression of the rfe-rff gene cluster of Escherichia coli.

We have cloned a 13 kb Escherichia coli DNA fragment which complemented the rfe mutation to recover the biosynthesis of E. coli O9 polysaccharide. Using Tn5 insertion inactivation, the rfe gene was localized at the 1.5 kb HindIII-EcoRI region flanking the rho gene. We constructed an rfe-deficient E. coli K-12 mutant by site-directed inactivation using a DNA fragment of the cloned 1.5 kb rfe gene. This also confirmed the presence of the rfe gene in the 1.5 kb region. By simultaneous introduction of both the rfe plasmid and the plasmid of our previously cloned E. coli O9 rfb into this rfe mutant, we succeeded in achieving in vivo reconstitution of O9 polysaccharide biosynthesis. From sequence analysis of the rfe gene, a putative promoter followed by an open reading frame (ORF) was identified downstream of the rho gene. This ORF coincided with the position of the rfe gene determined by Tn5 analysis and site-directed mutagenesis. Furthermore, we identified the rff genes in the 10.5 kb DNA flanking the rfe gene. We recognized at least two functional domains on this cloned rff region. Region I complemented a newly found K-12 rff mutant, A238, to synthesize the enterobacterial common antigen (ECA). Deletion of region II resulted in the synthesis of ECAs with shorter sugar chains. When the 10.5 kb rff genes of the plasmid were inactivated by either deletion or Tn5 insertion, the plasmid lost its ability to give rise to transformants of the rfe mutants.

Amino Acid Sequence↗
PubMed1991

Neurite-promoting activities of phosphatidylinositol and other lipids on fetal rat septal neurons in culture.

Neurite-promoting activities of lipids were assessed using serum-free cultures of fetal rat septal neurons. The most potent one was phosphatidylinositol (PI), followed by PI 4-phosphate, phosphatidylserine, sphingomyelin, and phosphatidylcholine. The EC50 value for PI was 1.5 micrograms/ml (1.8 microM), and activity was maximal at 4 micrograms/ml (56% of total cells had neurites after 24 h). Cerebroside, sulfatide, and di- and triacylglycerols showed relatively low activities. Synthetic dipalmitoyl phosphatidylcholine was also active, with a maximal activity (47%) at 100 micrograms/ml, a finding implying that the unsaturated fatty acid moiety is not released and further used as substrate for the arachidonic acid cascade. Lysophospholipids, phosphatidylglycerol, and cardiolipin were rather cytotoxic and lacked activity, an observation suggesting that membrane perturbation is not responsible for the neurite-promoting activity. Treatment with a protein kinase C inhibitor, H-7, or an Na+,K(+)-ATPase inhibitor, ouabain, inhibited the PI-induced neurite outgrowth, but the cyclic AMP- and cyclic GMP-dependent protein kinase inhibitor HA1004 did not inhibit this activity, a result indicating that multiple elements (protein kinase C and Na+,K(+)-ATPase) are involved in the induction of neurites. Because phospholipids can be provided either as lipid vesicles or as lipoproteins produced by macrophages at regeneration sites, they may play an important role in the regeneration of certain populations of neurons.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1991

Increased resistance to multiple drugs by introduction of the Enterobacter cloacae romA gene into OmpF porin-deficient mutants of Escherichia coli K-12.

Introduction of the romA gene cloned from Enterobacter cloacae into Escherichia coli K-12 resulted in almost complete inhibition of OmpF expression and a concomitant increase in resistance to quinolones, beta-lactams, chloramphenicol, and tetracyclines. In addition, the romA gene reduced the susceptibility to these multiple drugs even in the OmpF porin-deficient mutants of E. coli K-12. Results indicate the presence of romA-sensitive penetration pathway(s) for these multiple drugs other than the OmpF porin in E. coli.

Anti-Bacterial Agents↗
PubMed1991

Possible mechanisms underlying the slow lactose fermentation phenotype in Shigella spp.

A Southern hybridization analysis revealed that the region homologous to Escherichia coli lacZ was present on the chromosomal DNAs of beta-galactosidase-positive Shigella strains, such as Shigella dysenteriae serovar 1 and Shigella sonnei strains, whereas this region was absent from chromosomal DNAs of beta-galactosidase-negative strains of Shigella flexneri and Shigella boydii. We found that the lacY-A region was deficient in S. dysenteriae serovar 1 and believe that this is the reason for the slow fermentation of lactose by this strain. S. sonnei strains possessed the region which hybridized with E. coli lacY-A despite their slow hydrolysis of lactose. The whole lactose-fermenting region was cloned from S. sonnei and compared with the cloned lac operon of E. coli K-12. Both clones directed the synthesis of beta-galactosidase in an E. coli K-12 strain lacking indigenous beta-galactosidase activity (strain JM109-1), and we observed no difference in the expression of beta-galactosidase activity in S. sonnei and E. coli. However, E. coli JM109-1 harboring the lactose-fermenting genes of S. sonnei exhibited the slow lactose fermentation phenotype like the parental strain. S. sonnei strains had no detectable lactose permease activities. E. coli JM109-1 harboring the lactose-fermenting genes of S. sonnei had a detectable permease activity, possibly because of the multicopy nature of the cloned genes, but this permease activity was much lower than that of strain JM109-1 harboring the lac operon of E. coli K-12. From these results we concluded that slow lactose fermentation by S. sonnei is due to weak lactose permease activity.

Blotting, Southern↗
PubMed1991

Biosynthesis of Klebsiella K2 capsular polysaccharide in Escherichia coli HB101 requires the functions of rmpA and the chromosomal cps gene cluster of the virulent strain Klebsiella pneumoniae Chedid (O1:K2).

The genes determining the biosynthesis of type 2 (K2) capsular polysaccharide [3----beta Glc1,4----beta Man(1,3----beta GlcUA) 1,4----alpha Glc1----] of Klebsiella pneumoniae Chedid (O1:K2), which is highly virulent for mice, were cloned and introduced into Escherichia coli HB101 and into four noncapsulated mutants derived from K. pneumoniae reference strains of K1, K7, K9, and K28. The recombinant plasmid pCPS7B06 carried 23 kb of a chromosomal DNA fragment of strain Chedid and encoded a part of the Klebsiella cps gene cluster. However, pCPS7B06 encoded enough genetic information for the production of Klebsiella K2 capsular polysaccharide on the cell surfaces of four noncapsulated mutants of K. pneumoniae. On the other hand, both pCPS7B06 and pROJ3 carrying the rmpA gene locus derived from a resident large plasmid of Chedid were required for the biosynthesis of Klebsiella K2 capsular polysaccharide on the cell surface of E. coli HB101. The insertion inactivation analysis using Tn5 revealed that the cps gene cluster occupied more than 15 kb of the chromosome of Chedid. We conclude that rmpA, which has been known to enhance the biosynthesis of colanic acid in E. coli, is also involved in the biosynthesis of Klebsiella capsular polysaccharide in E. coli HB101.

Animals↗
PubMed1991

Effect of ciliary neurotrophic factor (CNTF) on motoneuron survival.

We have demonstrated that the extensive degeneration of motoneurons in the rat facial nucleus after transection of the facial nerve in newborn rats can be prevented by local ciliary neurotrophic factor (CNTF) administration. CNTF differs distinctly from known neurotrophic molecules such as NGF, BDNF and NT-3 in both its molecular characteristics (CNTF is a cytosolic rather than a secretory molecule) and its broad spectrum of biological activities. CNTF is expressed selectively by Schwann cells and astrocytes of the peripheral and central nervous system, respectively, but not by target tissues of the great variety of CNTF-responsive neurons. CNTF mRNA is not detectable by Northern blot or PCR analysis during embryonic development and immediately after birth. However, during the second post-natal week, a more than 30-fold increase in CNTF mRNA and protein occurs in the sciatic nerve. Since the period of low CNTF levels in peripheral nerves coincides with that of high vulnerability of motoneurons (i.e. axonal lesion results in degeneration of motoneuron cell bodies), insufficient availability of CNTF may be the reason for the rate of lesion-induced cell death of early post-natal motoneurons. Highly enriched embryonic chick motoneurons in culture are supported at survival rates higher than 60% by CNTF, even in single cell cultures, indicating that CNTF acts directly on motoneurons. In contrast to CNTF, the members of the neurotrophin gene family (NGF, BDNF and NT-3) do not support the survival of motoneurons in culture. However, aFGF and bFGF show distinct survival activities which are additive to those of CNTF, resulting in the survival of virtually all motoneurons cultured in the presence of CNTF and bFGF.

Animals↗
PubMed1991

Inhibitory effect of 2-(E-2-alkenoylamino)ethyl alkyl sulfides on gastric ulceration in rats. II. Structure and activity relationships of 2-(E-n or Z-n-Decenoylamino)ethyl alkyl sulfides.

The analogues of 2-(E-n or Z-n-decenoylamino)ethyl carbamoylmethyl sulfide, including the modifications of sulfide portion, double bond in decenoyl chain and alkyl sulfide moiety, were synthesized and their inhibitory effects on stress-induced ulceration in rats were compared. Replacing the sulfura atom by methylene group or oxygen atom reduced the effect of potency. Saturation of the double bond in the decenoyl chain tended to reduce the anti-ulcerogenic activity in rats. There was no relationship between the position of double bond in decenoyl chain and the pharmacological activity. On the other hand, compounds with E-configuration showed stronger anti-ulcer activity than the corresponding Z-type of compounds. Among 9 kinds of S substituted alkyl groups for carbamoylmethyl, 2-(E-2-decenoylamino)ethyl 2-cyclohexylethyl sulfide showed the most potent anti-ulcerogenic activity in rats and also showed the lowest acute toxicity in mice.

Animals↗