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Biomedical subjects

K Kondo

Publications and source records attributed to K Kondo.

At least 505 records · Page 28Linked to original sources
PubMed1993

Gender-related differences in the inhibitory effect on liver regeneration in alcohol-treated rats: study of polyamine metabolism.

We studied gender-related differences in the effect of a single dose of ethanol (EtOH) on liver regeneration following partial hepatectomy in male and female rats by determining polyamines and their related enzymes. When rats were orally treated with EtOH at 3 g/kg 1 hr before partial hepatectomy, liver ornithine decarboxylase (ODC) activity at 4 hr post-hepatectomy was found to be lower in EtOH-treated female than male rats (51% vs. 42%, P < 0.01). Although no EtOH effect was observed on spermidine acetyltransferase (SAT) activity, female rats showed significantly higher values than male rats. Among intra-hepatic polyamines, putrescine was strongly affected by EtOH and significantly reduced in both male and female rats, but the effect was more marked in female than in male rats (88% vs. 51%, P < 0.01). With respect to spermidine and spermine, male rats were unaffected by EtOH, whereas EtOH-treated female rats had lower levels. The gender-related differences became more distinct in terms of total polyamine; the decrease in total polyamine due to EtOH was observed in female rats only. These results suggested that there was a gender-related difference in the effect of EtOH on liver regeneration after partial hepatectomy, with the variations in polyamines probably affecting the subsequent process of liver regeneration.

Acetyltransferases↗
PubMed1993

Association of human herpesvirus 6 infection of the central nervous system with recurrence of febrile convulsions.

To determine the relationship of human herpesvirus-6 (HHV-6) infection to febrile convulsions, cerebrospinal fluid (CSF) from patients with a history of febrile convulsion were tested by polymerase chain reaction (PCR) amplification for HHV-6 DNA. HHV-6 DNA was detected in 9 of 10 samples from patients with exanthem subitum who showed neurologic symptoms. Also, 8 of 10 CSF samples from 8 patients who had three or more febrile convulsions and 1 of 7 CSF samples from patients who had a single febrile convulsion contained HHV-6 DNA. These data suggest that HHV-6 may invade the brain during the acute phase of exanthem subitum and that recurrence of febrile convulsions may be associated with reactivation of HHV-6.

Adolescent↗
PubMed1993

Characteristics of the epitope of protein-reactive anti-peptide antibodies.

The specificity of hen egg-white lysozyme (HEL)-reactive rabbit antibodies induced by the peptide loop I.II (sequences 57-107 containing Cys64-Cys80 and Cys76-Cys94) of HEL was clarified by analyzing their cross-reactions with various avian lysozymes and their reaction with synthetic peptides (sequences 59-82) in which alanine was substituted for the amino acid at certain positions. The Arg-68 residue of HEL plays a dominant role in the binding, while Gly-71, Ser-72, Arg-73, and Pro-79 also contribute to the binding of two anti-Ploop I.II antibodies (rabbit number 125 and 126). These residues, although remote in sequence, are grouped together in the crystal structure of HEL and may form an area of contact with the antibody. Contributions by Trp-63, Ile-78, and Asn-77 to the binding of the two antibodies to HEL were excluded. These results support the idea that the anti-Ploop I.II antibodies recognize a conformational type of epitope which is similar to that of native HEL. The immunogenicity of the reduced and alkylated form of Ploop I.II was also tested, but it failed to induce an HEL-reactive antibody.

Alanine↗
PubMed1993

Release of the outer membrane vesicles from Vibrio cholerae and Vibrio parahaemolyticus.

We found numerous small vesicles released from the cell by thin sectioning of the plate culture of Vibrio cholerae and V. parahaemolyticus fixed with the freeze-substitution technique. From the broth media of exponentially growing bacteria we could collect the vesicles by the centrifugation but not enough without fixation. The vesicles are encompassed with a membrane structure similar to the outer membrane of these bacteria. The anti-O (Inaba) serum reacted with the surface of the vesicles and the inside of the vesicle are generally filled with an electron-dense mass.

Bacterial Proteins↗
PubMed1993

Induction by ethanol of alcohol dehydrogenase activity in Acetobacter pasteurianus.

The membrane-bound alcohol dehydrogenase (ADH) activity of Acetobacter pasteurianus NCI1380 was enhanced more than 10-fold by the addition of ethanol to the medium. In order to elucidate the mechanism of the ethanol induction, a gene cluster encoding the dehydrogenase and cytochrome c subunits of ADH was cloned from this strain, and its nucleotide sequence was determined. Comparison of the deduced amino acid sequences and the NH2-terminal sequences determined with purified proteins showed that the dehydrogenase and cytochrome c subunits contained typical signal peptides of 35 and 26 amino acids, respectively. Transcriptional analysis of the cloned genes by primer extension revealed that the gene cluster was transcribed from two different promoters upstream from the dehydrogenase gene. One (59 bp upstream of the ATG start codon) of the two promoters was used in the presence of ethanol, whereas the other (232 bp upstream of the ATG start codon) was used in the absence of ethanol. Immunoblot analyses showed that almost the same amounts of the cytochrome c and the 15-kDa subunits were produced in both the presence and absence of ethanol and that the amount of the dehydrogenase subunit localized in the membrane was decreased in the absence of ethanol. This incorrect localization of the dehydrogenase subunit might be one of the factors responsible for the low ADH activity in the absence of ethanol.

Acetobacter↗
PubMed1993

Galanin as a physiological neurotransmitter in hemodynamic control of arginine vasopressin release in rats.

Previous neuroanatomical studies have revealed a localization of galanin in several nuclei in the brain stem which are involved in the hemodynamic control of arginine vasopressin (AVP) release. The present study, therefore, investigates the contribution of endogenous galanin to the plasma volume-mediated control of AVP release in conscious rats. Injection of synthetic rat galanin (12.5-50 pmol/rat) into the cisterna magna (i.c.s.) suppressed plasma AVP increased by polyethylene glycol-induced hypovolemia (2.45 +/- 0.24 pg/ml at 50 pmol/rat vs. the vehicle group 5.72 +/- 0.69 pg/ml, p < 0.01). In contrast, when plasma AVP was suppressed by isotonic plasma volume expansion, immunoneutralization of endogenous galanin by antigalanin-antibody i.c.s. significantly reversed the suppression (1.02 +/- 0.07 pg/ml vs. vehicle group 0.63 +/- 0.05 pg/ml, p < 0.01) without altering the mean arterial blood pressure. These results suggest that endogenous galanin is physiologically involved in the plasma volume-mediated control of AVP release through an inhibitory action on this pathway.

Animals↗
PubMed1993

Pituitary adenylate cyclase-activating polypeptide stimulates arginine vasopressin release in conscious rats.

The effect of pituitary adenylate cyclase-activating polypeptide (PACAP) on arginine vasopressin (AVP) release was investigated in conscious rats. Intracerebroventricular (i.c.v.) administration of PACAP raised the plasma AVP concentration in a dose-dependent manner (50-500 pmol/rat), and the maximum effect was obtained at 5 min after the administration. This AVP-releasing effect was not due to a fall of blood pressure, increase of plasma Na or decrease of plasma volume, all of which are known to stimulate AVP release. PACAP had little effect on blood pressure at a low dose, but at higher doses increased it. Vasoactive intestinal peptide (VIP), which is homologous to PACAP, also raised the plasma AVP concentration by i.c.v. injection. An antagonist for VIP receptor, [Lys, Pro, Arg, Tyr]-VIP inhibited the VIP-induced increase of plasma AVP, but had little effect on PACAP-induced increase of plasma AVP. These results suggest that PACAP stimulates AVP release, via specific receptors which are distinct from VIP receptors.

Animals↗
PubMed1993

Possible involvement of inefficient cleavage of preprovasopressin by signal peptidase as a cause for familial central diabetes insipidus.

A transition of G to A at nucleotide position 279 in exon 1 of the vasopressin gene has been identified in patients with familial central diabetes insipidus. The mutation predicts an amino acid substitution of Thr (ACG) for Ala (GCG) at the COOH terminus of the signal peptide in preprovasopression (preproVP). Translation in vitro of wild-type and mutant mRNAs produced 19-kD preproVPs. When translated in the presence of canine pancreatic rough microsomes, wild-type preproVP was converted to a 21-kD protein, whereas the mutant mRNA produced proteins of 21 kD and 23 kD. NH2-terminal amino acid sequence analysis revealed that the 21-kD proteins from the wild-type and the mutants were proVPs generated by the proteolytic cleavage of the 19-residue signal peptide and the addition of carbohydrate. Accordingly, mutant preproVP was cleaved at the correct site after Thr-19, but the efficiency of cleavage by signal peptidase was < 25% that observed for the wild-type preproVP, resulting in the formation of a predominant glycosylated but uncleaved 23-kD product. These data suggest that inefficient processing of preproVP produced by the mutant allele is possibly involved in the pathogenesis of diabetes insipidus in the affected individuals.

Amino Acid Sequence↗
PubMed1993

Preparation and cytotoxicity of cyclic hexapeptides, RA derivatives.

Several aromatic ring substituent modified RA derivatives were prepared from RA-VII (1), RA-V (8) and RA-II (11), and evaluated for cytotoxicity against P388 leukemia and KB cells. In terms of IC50 values, the C zeta methoxyl group of Tyr-3 greatly influenced the activities, while the substituents at the C zeta position of Tyr-6 were less important. One of the derivatives, Tyr-6-C zeta-deoxyRA-V (9, P388, IC50, 0.0025 micrograms/ml) was nearly as active as RA-VII (1, 0.0013 micrograms/ml), and also expressed promising anti-P388 in vivo activity (test/control = 171%, at 25 mg/kg).

Animals↗
PubMed1993

Antifungal peroxyketal acids from an Okinawan marine sponge of Plakortis sp.

Antifungal peroxyketal acids and their methyl esters, the peroxyplakoric acids A1 methyl ester (1), A2 methyl ester (2), A3 methyl ester (3), B1 methyl ester (4), and B3 methyl ester (5), were separated from an Okinawan marine sponge of Plakortis sp. The absolute stereostructures 1-5 have been elucidated on the basis of chemical and physicochemical evidence.

Animals↗
PubMed1993

Studies on RA derivatives. V. Synthesis and antitumor activity of Ala2-modified RA-VII derivatives.

A number of RA-VII derivatives having various amino acids including proline (6), pipecolic acid (11), norvaline (12), ornithine (14), aspartic acid (15) and methionine (20) in place of Ala2 have been synthesized from RA-X methyl ester (3) and evaluated for cytotoxicity to P388 leukemia and KB cells in vitro. Comparison of the cytotoxicity of these compounds suggests that the polarity and the length of the 2nd amino acid residue affect the activity. An NMR study revealed that, in solution, 6 and 11 are locked in one conformational state, corresponding to conformer A of RA-VII.

Animals↗
PubMed1993

Nematocidal activity of turmeric: synergistic action of curcuminoids.

A new curcuminoid, cyclocurcumin (IV), was isolated from the nematocidally active fraction of turmeric, the rhizome of Curcuma longa, together with three known curcuminoids, curcumin (I), demethoxycurcumin (II) and bisdemethoxycurcumin (III). The structure of IV was elucidated on the basis of spectral data and confirmed by the partial synthesis from curcumin (I). Although the above curcuminoids were ineffective when they were applied independently, the nematocidal activity increased remarkably when they were mixed, suggesting a synergistic action between them.

Animals↗
PubMed1993

Stimulation of nerve growth factor synthesis and secretion by fellutamide A in vitro.

Fellutamide A, a tripeptide derivative from Penicillium fellutanum was found to be a potent enhancer of nerve growth factor (NGF) synthesis and secretion in vitro. This compound enhanced production of NGF in L-M cells, rat brain cells, and rat glial cells. The mode of action of this compound was suggested to be different from that of a known NGF inducer, epinephrine, as inducing activities of fellutamide A and epinephrine were additive when they were admixed at the concentration which gave saturation in its respective activity. Furthermore, fellutamide A but not epinephrine induced production of NGF in the rat brain cells. NGF-inducing activity of several tripeptides and other compounds related to fellutamide A was examined.

Amino Acid Sequence↗