PubMed Health⌕ Search

Biomedical subjects

K Fukuhara

Publications and source records attributed to K Fukuhara.

At least 19 recordsLinked to original sources
PubMed1992

Noradrenergic activation in the paraventricular nucleus during acute and chronic immobilization stress in rats: an in vivo microdialysis study.

In vivo microdialysis was used to study the effects of single (2 h) or repeated (2 h for 7 consecutive days) immobilization (IMMO) stress on extracellular fluid concentrations of norepinephrine (NE) and the deaminated metabolites of NE and dopamine, dihydroxyphenylglycol (DHPG) and dihydroxyphenylacetic acid (DOPAC) in the paraventricular nucleus of conscious rats. During IMMO, NE, DHPG, and DOPAC levels increased markedly, with similar peak values and time courses in the repeatedly stressed and previously unstressed groups. NE levels during a 2-h baseline period were lower in the repeatedly stressed group than in the unstressed group (99 +/- 9 pg/ml vs. 167 +/- 13 pg/ml, P less than 0.05), whereas DHPG (1,697 +/- 263 pg/ml vs. 1,424 +/- 194 pg/ml) and DOPAC (5,989 +/- 863 pg/ml vs. 4,428 +/- 1150 pg/ml) levels tended to be higher, so that the NE/DHPG ratio at baseline was significantly lower in the repeatedly stressed group (P less than 0.05). The results indicate that IMMO stress enhances NE release, reuptake, metabolism, and synthesis in the PVN. Repeated exposure to IMMO may decrease the microdialysate NE/DHPG ratio by inhibiting exocytotic release or enhancing neuronal reuptake of NE. In either case, the results suggest that repeated exposure to stress alters the release and disposition of NE in the PVN of conscious animals.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1992

Induction of colon adenocarcinomas in CD rats and lung adenomas in ICR mice by 6-nitrochrysene: comparison of carcinogenicity and aryl hydrocarbon hydroxylase induction in the target organs of each species.

Species and organ specificity of 6-nitrochrysene (6-NC)-induced carcinogenicity and the potential correlation with aryl hydrocarbon hydroxylase (AHH) induction in the target organs were investigated in both sexes of ICR mice and CD rats. Animals received total 6-NC doses of 1.4 mumol/mouse and 14.8 mumol/rat. The first i.p. injection was performed within 24 h of birth, then the animals were subjected to 3 and 5 weekly injections in the mouse and rat cases, and the survivors were sacrificed at weeks 24 and 32, respectively. Adenocarcinomas and dysplasias and/or adenomas of the colon in rats and lung adenomas in mice were observed in animals treated with 6-NC. However, no such lesions were observed in animals treated with the vehicle dimethyl sulfoxide alone. AHH activities in the lung, colon, and liver of each animal after treatment with 6-NC or dimethyl sulfoxide were also investigated. Six-week-old animals received a single 6-NC injection i.p. at the dose of 0.8 mumol/mouse or 8.0 mumol/rat. Animals were sacrificed on day 1 or 7 following injections, when AHH levels were measured. The results indicated enzyme levels in all these organs to be elevated by 6-NC treatment, the induction rate in the mouse lung being the highest. These results showed that 6-NC is carcinogenic for the colon of rats, as well as the lung of mice, and that it also induces AHH activity in both target and nontarget organs.

Adenocarcinoma↗
PubMed1992

Reduction properties of nitrated naphthalenes: relationship between electrochemical reduction potential and the enzymatic reduction by microsomes or cytosol from rat liver.

The nitroreductase activities of rat liver microsomes and cytosol towards various nitrated naphthalenes (1-, 2-mononitro-, 1,3-, 1,5-, 1,7-, 1,8-dinitro-1,3,5- and 1,3,8-trinitronaphthalenes) were characterized as follows. (1) The rates of reduction of nitrated naphthalenes in either microsomal or cytosolic incubation were found to increase in the order of trinitro- > dinitro- > mono-nitronaphthalene, although, in the case of microsomal nitroreduction, trinitronaphthalenes were reduced more rapidly than in cytosol. (2) The effective cofactors, electron donors, in the nitroreduction of nitrated naphthalenes in cytosol were NADH and hypoxanthine, but not NADPH. (3) The nitrated naphthalenes with a nitro group at a beta-position appear to be more easily reduced among the various isomers. The cytosolic nitroreductase activities towards the nitrated naphthalenes were closely related to the single-electron reduction potentials measured by cyclic voltammetry and hence, there was a good relationship between the logarithm of nitroreductase activities and the electrochemical reduction potentials. In microsomes, nitroreductase activities were rather less well related to electrochemical reduction potentials.

Animals↗
PubMed1992

Mutagenicity of nitro-azabenzo[a]pyrene and its related compounds.

The mutagenicity of nitrated benzo[a]pyrene (BP) and the related compounds, 1- and 3-nitrobenzo[a]pyrene (NBP), 1- and 3-nitro-6-cyanobenzo[a]pyrene (N-6-CBP), 1- and 3-nitro-6-azabenzo[a]-pyrene (N-6-ABP), 1- and 3-nitro-6-azabenzo[a]-pyrene-N-oxide (N-6-ABPO) and 1,6- and 3,6-dinitrobenzo[a]-pyrene (DNBP), was investigated. The mutagenic activities of 3-N-6-CBP and 3-N-6-ABP were 117 and 76 times, respectively, that of 3-NBP. In addition, 3,6-DNBP was more mutagenic than 1,6-DNBP. It is suggested that the mutagenic activation differs with the position of NO2 substitution in the chemical structure. A nitro derivative with NO2 substitution at the 3 position of the aromatic ring of BP was more mutagenic than that with the substitution at the 1 or 6 position. The reducibility of DNBPs was then determined by detecting 1- or 3-amino-6-nitrobenzo[a]pyrene (A-6-NBP), a metabolite of DNBP; 3,6- and 1,6-DNBP were reduced to 3- and 1-A-6-NBP at frequencies of 958 +/- 26 and 79 +/- 8, respectively, pmole per mg of protein, when the compound was incubated anaerobically with rat liver S9 mix at 37 degrees C for 15 min. NO2 substituted at the 3 position of the aromatic ring of BP was readily reduced by a microsome enzyme to form an amino derivative. The result suggests that these compounds have a structure-activity relationship between mutagenicity and NO2 substitution of BP.

Animals↗
PubMed1992

Immunohistological analysis of P53 expression in human skin tumors.

The p53 expression in various skin tumors was immunohistologically evaluated using two mouse monoclonal anti-p53 antibodies, PAb421 and PAb1801. The p53 expression was not detected in the normal epidermal cells. Nuclear staining suggested that the p53 expression was observed in 10 of 26 squamous cell carcinomas (SCCs) from 24 patients, in one undifferentiated carcinoma, one proliferating trichilemmal cyst, one malignant proliferating trichilemmal tumor and in one metastatic carcinoma of breast cancer. None off four cases of Bowen's disease (SCC in situ) showed nuclear staining. In the SCCs, five of 20 primary lesions, three of four recurrent lesions and both of two metastatic lesions had positive nuclei. There was one case of SCC in which a primary lesion was negative but a recurrent lesion was positive. Thus, p53 expression was more frequently observed in SCCs at more clinically advanced stages. This may suggest that p53 has some relevance to progression of SCC. Nuclear staining was not detected in any of the following cases: two cases of seborrheic keratosis, one eccrine poroma, one keratoacanthoma, 11 basal cell epitheliomas, two mammary Paget's disease, three genital Paget's disease, one sebaceous carcinoma, four malignant melanomas, six lymphomas, two leukemia cutis and two angiosarcomas.

Antibodies, Monoclonal↗
PubMed1992

Regulation of tyrosine hydroxylase and dopamine beta-hydroxylase mRNA levels in rat adrenals by a single and repeated immobilization stress.

Adrenal catecholamines are known to mediate many of the physiological consequences of the "fight or flight" response to stress. However, the mechanisms by which the long-term responses to repeated stress are mediated are less well understood and possibly involve alterations in gene expression. In this study the effects of a single and repeated immobilization stress on mRNA levels of the adrenal catecholamine biosynthetic enzymes, tyrosine hydroxylase and dopamine beta-hydroxylase, were examined. A repeated 2-hr daily immobilization for 7 consecutive days markedly elevated both tyrosine hydroxylase and dopamine beta-hydroxylase mRNA levels (about six- and fourfold, respectively). In contrast, tyrosine hydroxylase but not dopamine beta-hydroxylase mRNA levels were elevated immediately following a single immobilization. The elevation in tyrosine hydroxylase mRNA with a single immobilization was as high as with seven daily repeated immobilizations. This elevation was not sustained and returned toward control values 24 hr later. Both tyrosine hydroxylase and dopamine beta-hydroxylase mRNA levels were elevated immediately following two daily immobilizations to levels similar to those observed after seven immobilizations and were maintained 24 hr later. The results indicate that both tyrosine hydroxylase and dopamine beta-hydroxylase mRNA levels are elevated by stress; however, the mechanism and/or timing of their regulation are not identical.

Adrenal Glands↗
PubMed1992

Hypercortisolemia inhibits yohimbine-induced release of norepinephrine in the posterolateral hypothalamus of conscious rats.

Chronic hypercortisolemia attenuates yohimbine (YOH)-induced increments in plasma levels of the sympathetic neurotransmitter norepinephrine (NE). The present study used in vivo microdialysis to study the effects of hypercortisolemia on YOH-induced release of NE in the brain. Cortisol (25 mg/kg.day) or saline was infused sc into rats for 7 days via an osmotic minipump. Microdialysate and plasma concentrations of NE and its metabolites dihydroxyphenylglycol and methoxyhydroxyphenylglycol were measured before and after YOH (1 mg/kg, iv) administration in conscious animals, with microdialysate and plasma collections beginning 20-24 h after probe implantation. Chronic cortisol treatment resulted in attenuated NE, dihydroxyphenylglycol, and methoxyhydroxyphenylglycol responses in both microdialysate and plasma. The results indicate that YOH increases central neural as well as peripheral release, reuptake, turnover, and metabolism of NE and that hypercortisolemia suppresses these responses.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1992

The metabolism of 1,6-dinitropyrene in rat hepatocytes.

This paper reports investigations using hepatocytes to study the metabolism and DNA binding of the environmental contaminant, 1,6-dinitropyrene. Since 1,6-dinitropyrene is not believed to be mutagenic per se, metabolites were synthesized and the metabolism of 1,6-dinitropyrene was subsequently studied in rat hepatocytes. The mode of activation of dinitropyrenes is reduction of one of the nitro groups. Nitroreduction has been shown previously to be oxygen sensitive and therefore the effect of oxygen on the metabolic pattern and DNA binding was investigated by comparing results from aerobic and anaerobic conditions. The binding of [14C]1,6-dinitropyrene equivalents to rat hepatocyte DNA was increased by 15% in the presence of oxygen. Although there was little difference in the rate of 1,6-dinitropyrene metabolism, with or without O2, there was a difference in the metabolic pattern. Under anaerobic conditions there was an increase in the level of the terminal reduction product 1-amino-6-nitropyrene.

Animals↗
PubMed1992

Plasma dopa responses during stress: dependence on sympathoneural activity and tyrosine hydroxylation.

Dihydroxyphenylalanine (dopa), the precursor of all the endogenous catecholamines, circulates in plasma at a concentration higher than that of the sympathetic neurotransmitter, norepinephrine (NE). Sources of dopa in plasma and the meaning of plasma dopa levels in terms of sympathoneural function have been unclear. Plasma concentrations of dopa, the catecholamines NE, epinephrine and dopamine, the deaminated catechol metabolites dihydroxyphenylglycol and dihydroxyphenylacetic acid, and the O-methylated metabolites methoxyhydroxyphenylglycol and homovanillic acid were measured during immobilization stress in conscious rats. Animals were pretreated with chlorisondamine to block ganglionic neurotransmission or with alpha-methyl-para-tyrosine to inhibit tyrosine hydroxylation. Immobilization produced rapid, sustained increases in plasma levels of dopa, catecholamines and catecholamine metabolites. Chlorisondamine decreased base-line plasma dopa and NE levels and abolished the increases in plasma dopa and NE levels during immobilization. alpha-Methyl-para-tyrosine administration produced sustained decreases in plasma dopa levels and markedly attenuated immobilization-induced increases in plasma dopa levels. Bilateral adrenalectomy augmented base-line plasma levels of dopa and NE and augmented dopa and NE responses during immobilization. The results indicate that during immobilization stress, increased postganglionic sympathoneural outflow stimulates the synthesis of dopa in sympathetic neurones and enhances release of dopa into the circulation. The data generally support the view that changes in plasma dopa levels during stress reflect in vivo changes in the rate of catecholamine biosynthesis in sympathetic nerve terminals.

Adrenalectomy↗
PubMed1991

Isolation of steroidal glycoalkaloids from Solanum incanum by two countercurrent chromatographic methods.

Using a bioassay for inhibition of plant growth and a combination of two countercurrent chromatographies: rotation locular countercurrent chromatography and droplet countercurrent chromatography, two biologically active glycosidal alkaloids, solasonine and solamargine were isolated from fresh ripe fruit of Solanum incanum. The combination of these chromatographic techniques has established an efficient isolation of polar phytochemicals of steroidal glycoalkaloids.

Carbohydrate Sequence↗
PubMed1991

Detection of 3,6-dinitrobenzo[a]pyrene in airborne particulates.

3,6-Dinitrobenzo[a]pyrene, a new mutagen, was detected in airborne particulates collected in Santiago (Chile). The quantity of the compound in the airborne particulates was very small, accounting for 0.01 micrograms/g of total particulates (0.002 ng/m3 of air) at the lowest concentration. It was found that 3,6-dinitrobenzo[a]pyrene is readily decomposed by UV irradiation at 312 nm. The decomposed product was identified as 3-nitrobenzo[a]pyrene-6-quinone by means of mass spectrometry and proton nuclear magnetic resonance analysis. The mutagenicity of 3,6-dinitrobenzo[a]pyrene was 137,000 revertants/nmole for Salmonella typhimurium strain TA98, less than that for strain TA98/1,8-DNP6, an acetyltransferase-deficient mutant, and more than that for strain YG1024, an acetyltransferase-rich mutant.

Air Pollutants↗
PubMed1990

Rapid confirmation and revision of the primary structure of bovine serum albumin by ESIMS and Frit-FAB LC/MS.

Incorrectness of the amino acid sequence of bovine serum albumin (BSA) was suggested from the observed molecular weight of BSA obtained by electrospray ionization mass spectrometry (ESIMS). Lack of a tyrosine residue in the position of 156th was found rapidly, by the combination of frit-fast atom bombardment mass spectrometry/liquid chromatography (Frit-FAB LC/MS), automated Edman degradation and tandem mass spectrometry (MS). Then it turned out that BSA is composed of 583 amino acid residues, and that its average molecular weight is not 66267.1, and it is corrected to 66430.3. Moreover the amino acid sequence of the positions of 94th and 95th was corrected to -QE- by using automated Edman degradation method.

Amino Acid Sequence↗
PubMed1990

Three-dimensional structure of an alpha-amylase inhibitor HAIM as determined by nuclear magnetic resonance methods.

The three-dimensional structure of an alpha-amylase inhibitor, HAIM, composed of 78 amino acids, was analyzed by two-dimensional NMR techniques. Sequence-specific assignments were made for the amino acid residues from Ile-6 to Cys-72. Distance geometry analysis of the interresidue NOEs revealed that the HAIM molecule consists of two beta-sheets, as is the case in a homologous alpha-amylase inhibitor, Tendamistat, though one of its beta-strands is much shorter than that of Tendamistat. The combination of molecular modeling from Tendamistat and distance geometry analysis was confirmed to be useful for our purpose.

Amino Acid Sequence↗
PubMed1990

Synthesis, chemical properties and mutagenicity of 1,6- and 3,6-dinitrobenzo[a]pyrenes.

Nitration of benzo[a]pyrene (BaP) with HNO3 (d = 1.38) produced a mixture of dinitroBaPs (1,6- and 3,6-isomers) and mononitroBaPs (1-, 3- and 6-isomers). Pure 1,6-dinitroBaP and 3,6-dinitroBaP were obtained by the reduction of the dinitroBaPs mixture with NaSH to yield the separable products 1-amino-6-nitroBaP and 3-amino-6-nitroBaP, followed by conversion to dinitroBaPs via the the diazonium salts. The half-wave potentials (E1/2) corresponding to the one-electron reduction of dinitroBaPs were measured and the relationship of these values to the mutagenicity is discussed.

Benzopyrenes↗
PubMed1989

Plasma amino acid abnormalities in liver disease: comparative analysis of idiopathic portal hypertension, extrahepatic portal occlusion and liver cirrhosis.

To clarify the clinical significance of specific plasma amino acid abnormalities occurring in liver disorders with portal-systemic shunting, plasma amino acids and insulin levels were measured in idiopathic portal hypertension (IPH), extrahepatic portal occulusion (EHPO), and liver cirrhosis (LC). Three branched chain amino acids (BCAA: valine + leucine + isoleucine) were decreased in all three diseases in comparison with controls. Since plasma insulin measured during oral glucose tolerance tests did not specifically rise in LC, reduction of BCAA is not merely ascribed to hyperinsulinemia. Either portal-systemic shunting or some extent of liver damage may contribute to a fall in BCAA. Two aromatic amino acids (AAA: phenylalanine + tyrosine), which were within the normal range in EHPO and IPH, showed a marked increase in LC. Thus, changes of AAA probably mainly reflect the severity of the liver disease. The molar ratio of BCAA/AAA (MR) significantly correlated with ICG k, ICG R15, PT and the sum of blood ammonia in an oral ammonia tolerance test which may reflect the degree of hepatic disorder. MR diminished in the following decreasing order: controls, EHPO, IPH and LC.

Amino Acids↗
PubMed1988

Release of inflammatory mediators by noxious stimuli; effect of neurotropin on the release.

Anesthetized rats were perfused with saline in the subcutaneous space of the hind paw and the release of inflammatory mediators induced by noxious stimuli was studied. Not only immunoreactive bradykinin (BK) but also histamine, serotonin (5-HT) and immunoreactive prostaglandin E2 (PGE2) were found to be released into the perfusate when the paw was pinched. Neurotropin, used clinically as an analgesic and anti-allergic drug in Japan, inhibited the release of BK in dose-dependent manner without altering the release of histamine, 5-HT and PGE2. The maximal inhibition of BK release was observed 60 min after p.o. administration of neurotropin. Indomethacin failed to inhibit the release of BK.

Animals↗
PubMed1988

A determination of the positions of disulphide bonds in Paim I, alpha-amylase inhibitor from Streptomyces corchorushii, using fast atom bombardment mass spectrometry.

Paim I, a protein alpha-amylase inhibitor, is a single-chain polypeptide which consists of 73 amino acids, including 4 half-cystine residues. The positions of disulphide bonds in Paim I have been determined with the combination of enzymatic digestion and fast atom bombardment (FAB) mass spectrometry. Denatured Paim I was digested to peptides with Staphylococcus aureus V8 protease. These peptides were subjected to FAB mass spectrometry, with or without isolation by high-performance liquid chromatography. The positions of disulphide bonds in Paim I were determined from the relative molecular masses of the peptides containing a disulphide bond and by the enzyme specificity of S. aureus V8 protease. It is deduced that Paim I has two disulphide bridges at Cys(8)--Cys(24) and Cys(42)--Cys(70).

Amino Acid Sequence↗