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Biomedical subjects

R Kato

Publications and source records attributed to R Kato.

At least 811 records · Page 45Linked to original sources

Expression of basic fibroblast growth factor in thyroid disorders.

Morphologic and biologic studies were undertaken to clarify the biologic significance of basic fibroblast growth factor (bFGF) in human thyroid neoplasms. A total of 71 malignant tumors (50 papillary carcinomas, 14 follicular carcinomas, 7 anaplastic carcinomas), 11 follicular adenomas, 6 adenomatous goiters, and 6 Graves' disease tissues were examined employing immunohistochemical methods (avidin-biotin-peroxidase complex technique). An affinity-purified polyclonal rabbit antiserum to human bFGF was used as a primary antibody. The eluate of malignant thyroid tumor tissues from the heparin-Sepharose column was examined by Western blot analysis to elucidate the molecular weight form. With immunohistochemical staining, bFGF was frequently detected in the cytoplasm of malignant thyroid tumors compared to tissues of the benign diseases and normal controls. With anaplastic carcinoma, immunoreactivity of the tumor cells was particularly strong. In the correlative analyses between UICC TNM classification and bFGF staining in papillary carcinoma, there were significant differences when relating positive staining to the grade of nodal metastases. By Western blot analysis, the bFGF immunoreactivity was specifically detected in the two forms, with molecular weights of 18 and 33 kDa. The high-molecular-weight form was detected in only anaplastic carcinoma. The present investigations demonstrated a close correlation between the expression of bFGF and the degree of malignancy. bFGF might play an important role in promoting lymph node metastases. Moreover, the high-molecular-weight form of bFGF might have an intense influence on tumor growth.

Adenocarcinoma, Follicular↗

Effects of the enkephalin analogue FK33-824 on rectal temperature and respiratory rate in male mice.

Subcutaneous administration of the enkephalin analogue FK33-824 (FK) elicited a dose-related decrease in rectal temperature and respiratory rate in male ddY strain mice. Naloxone and 3 days' implantation of morphine pellet decreased the effects of FK, suggesting the involvement of opioid receptors and cross-tolerance with morphine to both effects of FK. A positive correlation was found between the FK-induced decrease in rectal temperature and that in respiratory rate among the 6 strains of inbred mice including BALB/c, C3H, A/J, CBA, C57BL/6 and DBA/2. The degree of hypothermia elicited by FK was different among strains, whereas marginal strain difference was seen in the respiratory depression induced by FK. The strain difference in the FK responses may be due to the difference in the opioid receptor subtypes in the brain.

Animals↗

Isolation and characterization of human liver cytochrome b5 cDNA.

Three cDNA clones encoding human cytochrome b5 have been isolated and sequenced from a lambda gt 11 cDNA library of a human liver. The largest clone (b5-C) contains 765 base pairs corresponding to a complete coding sequence of 134 amino acids and sequences for 5' non-coding (56 bases) and 3' non-coding regions (307 bases). In Northern blots, a band hybridizing to 32P-labelled b5-B cDNA clone was detected at around 12S in mRNA of human and rat livers. The deduced amino acid sequence was identical with the partial amino acid sequence (2-100th) previously reported, except that two amino acid replacements were observed between the 89th and 91st positions. The deduced amino acid sequence of human cytochrome b5 shares 88.0, 86.5, 86.5 and 74.4% similarity with those of rat, pig, horse and chicken, respectively. The sequences in the haem binding region were highly conserved among these species. In addition, high similarities in the hydrophobicity profiles were maintained throughout their entire regions, although some diversity was observed in the N-terminal sequences between human and chicken.

Amino Acid Sequence↗

Outcome analysis of sildenafil citrate for erectile dysfunction of Japanese patients.

The approved maximal dose of sildenafil is only 50 mg in Japan, but the impact of dose regulation on treatment outcomes has not been established. Moreover, the contributors to the efficacy in patients having an intact peripheral nervous system have not been fully elucidated. We assessed in Japanese patients the treatment outcomes of sildenafil for erectile dysfunction (ED) under regulation of the approved dose and identified factors contributing to its efficacy among those with various etiologies other than pelvic surgery. We retrospectively reviewed 196 ED patients treated with sildenafil. The overall efficacy was 70.9% (139/196), and patients with psychological problems and concomitant cardiovascular disease showed high response rates (82.4 and 87.0%, respectively). Of the 139 responders, 89.9% achieved efficacy with a dose of 25 or 50 mg. Logistic regression analysis revealed concomitant cardiovascular disease and a favorable nocturnal penile tumescence result to be independent contributors to the efficacy.

Adult↗

Relationship between the classification of vascular invasion severity and the prognosis of uterine endometrial cancer.

The objective of this research is whether the classification of vascular invasion severity can be used as a prognostic factor in cases of uterine endometrial cancer. Sixty-five patients with stage I to III uterine endometrial cancer were included in the study. All patients were seen between 1987 and 1997, and the types of their cancers were histologically confirmed. The degree of vascular invasion was classified according to three different systems: (1). positive or negative; (2). negative, mild, or severe; and (3). negative, mild, moderate, or severe. For each classification, the disease-free survival rate was calculated according to various pathologic factors using the Wilcoxon test; multivariate analyses were performed using the Cox proportional hazard model. Patients with severe vascular invasion showed a significantly lower disease-free survival rate than did patients with moderate or less severe invasion. In the multivariate analysis, severe vascular invasion was shown to be an independent prognostic factor indicating a high relative risk. We conclude that the severity of vascular invasion is an important histopathologic factor in determining the prognosis of uterine endometrial cancer. Vascular invasion classification systems employing three subjective or four objective categories may be more appropriate than a positive/negative classification system for judging the prognosis in cases of uterine endometrial cancer.

Adult↗

Lack of effect of 3,3'5'-triiodothyronine (reverse T3) on cardiac function in the rabbit.

In a recent study, we have shown that the antiarrhythmic drug, amiodarone caused significant elevations of serum rT3 levels and inhibition of the peripheral conversion of T4 to T3 (Kannan et al. Endocrinology 115:1710-1716, 1984). In this study we have examined whether or not rT3 has a direct effect on the monodeiodinase enzyme activity and electropharmacology of the rabbit myocardium. Six male New Zealand White rabbits were administered 50 ug rT3 (a dose about 100 times the daily rT3 production rate) i.p. for 5 days, while the control group received saline. Serum T4, T3 and rT3 concentrations, and myocardial as well as liver and kidney 5'monodeiodinase enzyme activities were measured. Surface ECG and electrophysiological parameters in the atrial, ventricular and sinoatrial node in control and rT3 groups were obtained. Surface ECG did not show any difference in heart rate, RR, PQ, QRS or QT intervals in the two groups. Reverse T3 administration did not produce any significant alterations in APA, MRP, Vmax, APD90 and ERP of atrial and ventricular muscle. Despite administration of a massive dose of rT3, serum levels of T3 and T4 were unchanged as compared to control group. Reverse T3 administration did not produce any alterations in the 5'monodeiodinase activities in the myocardium, liver and kidney. The studies suggest that rT3 does not appreciably affect myocardial function and that the effects of amiodarone on the heart occur via mechanisms other than its ability to cause an increase in serum rT3 levels.

Action Potentials↗

Effects of amiodarone and its metabolite, desethylamiodarone, on the electrophysiologic properties of isolated cardiac muscle.

The electrophysiologic (EP) effects of chronically administered amiodarone (AM) is known, but the nature of its acute effects are unclear. Whether the delayed onset of AM action is due to its metabolite, desethylamiodarone (DAM), is also uncertain. By standard microelectrode techniques in isolated canine ventricular muscle (VM) and Purkinje fibers (PF) and in rabbit sinoatrial (SA) node and atrium, we therefore studied the comparative effects of AM and DAM, 10(-6) M (0.68 micrograms/ml), 10(-5) M (6.8 micrograms/ml), and 5 X 10(-5) M (34 micrograms/ml), dissolved in ethanol and homologous serum. In VM, PF, and atria stimulated at 1 Hz, AM and DAM had no effect on Vmax, action potential amplitude (APA), or resting membrane potential. At 2-4 Hz, AM exerted a marked use-dependent effect in VM and PF. In atria, 5 X 10(-5) M, AM and DAM increased (p less than 0.01) action potential duration at 90% repolarization (APD90); the effective refractory period (ERP) increased by 10.5% (p less than 0.05 for AM) and 21.6% (p less than 0.01 for DAM). In VM, AM increased APD90 by 9.6% (p less than 0.01) at 10(-6) M, 13.7% (p less than 0.01) at 10(-5) M, and 16.9% (p less than 0.01) at 5 X 10(-5) M. The corresponding values for DAM were 5.6% (NS), and 7.3% (p less than 0.01), respectively. The ERP in VM was increased significantly by AM but not by DAM at all 3 drug concentrations without a change in APD90/ERP ratio. In PF, AM and DAM decreased APD50 and APD90; the effects were greater than those produced by the superfusion medium, but the degree of shortening in ERP induced by AM and DAM was not. AM and DAM (10(-5) and 5 X 10(-5) M) increased spontaneous cycle length of rabbit SA node. AM significantly decreased slope of phase 4 depolarization (10.4% at 10(-6) M, p less than 0.05; 14.5% at 10(-5) M, p less than 0.01; 24.0% at 5 X 10(-5) M, p less than 0.01). At 5 X 10(-5) M, AM significantly decreased APA, maximum diastolic potential and threshold potential with an insignificant effect on APD100.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗

Enhancement by cysteinyl thiols of acetyltransferase-mediated, but not of sulfotransferase-mediated, binding of a pyrolysate-derived N-hydroxyarylamine, 2-hydroxyamino-6-methyldipyrido[1,2-a:3',2'-d]imidazole, to DNA.

The effect of thiols on the activation of a pyrolysate-derived N-hydroxyarylamine, 2-hydroxyamino-6-methyldipyrido[1,2-a:3',2'-d]imidazole (N-hydroxy-Glu-P-1), was studied in vitro. In hepatic cytosol of rats, [3H]-N-hydroxy-Glu-P-1 bound covalently to calf thymus DNA in the presence of acetyl CoA or 3'-phosphoadenosine-5'-phosphosulfate (PAPS). The extent of the binding of N-hydroxy-Glu-P-1 in a PAPS-dependent system was decreased by the addition of 10 mM glutathione, N-acetyl-L-cysteine, 2-mercaptoethanol or dithiothreitol. However, acetyl CoA-dependent binding of N-hydroxy-Glu-P-1 was stimulated by the addition of 10 mM N-acetyl-L-cysteine (3 fold), L-cysteine (2 fold) or glutathione (1.2 fold), but not 10 mM 2-mercaptoethanol or L-methionine. After hydrolysis of the modified DNA, no difference was detected in the physicochemical properties of the nucleoside adduct formed in the acetyl CoA-supported system with and without thiols. These results indicate that thiols with a cysteine residue are able to affect the activation of carcinogenic heterocyclic arylamines selectively by the modulation of the acetyltransferase-mediated, but not the sulfotransferase-mediated, pathway.

Acetyl Coenzyme A↗

Drug metabolism under pathological and abnormal physiological states in animals and man.

The activity of microsomal drug-metabolizing enzymes is altered by several pathological or abnormal physiological states, such as changes in nutritional status, liver, heart or kidney diseases, hormonal disturbances, pregnancy, tumour-bearing state, adjuvant arthritis, changes in reticuloendothelial system and environmental factors (stress, irradiation, heavy metals). The activities of other metabolic pathways, such as glucuronidation, sulphate conjugation, acetylation and alcohol oxidation are generally affected to lesser extents. Rats are most commonly used in drug metabolism studies, and it is important to know that the activity of most of the microsomal drug-metabolizing enzymes is higher in males than in females through androgen action which is readily impaire drug-metabolizing enzymes in male rats are thus manifested by two mechanisms; one is by impairment of androgen action and the other is by depression of the basic enzymic activity. Therefore, those effects of pathological states, observed only in male rats but not in females, are generally not seen in other species of animals, including man. The effects of starvation, hyperthyroidism, adrenal insufficiency, diabetes and morphine administration are cases where changes in metabolism are due solely to impairment of androgen action. In other pathological cases, those drug-metabolizing enzymes showing sex differences are depressed more markedly in male rats than those showing no clear sex difference. The author therefore recommends the use of female rats in the evaluation of the effects of pathological states on hepatic microsomal drug-metabolizing enzymes. Generally, changes in activity of the hepatic enzymes reflect closely the changes in the rates of drug metabolism in vivo. However, the protein-binding of drugs, hepatic blood flow and renal function are also known to affect the rate of drug metabolism and excretion in vivo, and therefore changes of these factors in pathological states should also be taken into consideration.

Animals↗

Metabolic activation of trp-P-2, a mutagenic amine from tryptophan-pyrolysate, by liver microsomes from 3-methylcholanthrene-responsive and non-responsive mice.

1. The metabolic activation of a tryptophan pyrolysate, Trp-P-2 (3-amino-1-methyl-5H-pyrido[4,3-]indole), was studied using liver microsomes from mice of 3-methylcholanthrene-responsive, C57BL/6N (B6) strain and non-responsive, DBA/2N (D2) strain. 2. The formation of N-hydroxy-Trp-P-2 (3-hydroxylamino-1-methyl-5H-pyrido-[4,3-b]indole) by hepatic microsomes was markedly increased by the pretreatment with 3-methylcholanthrene in B6 mice, but not in D2 mice. 3. The same treatment increased the activity to convert Trp-P-2 to a mutagen(s) in the Salmonella/microsome test system in B6 mice, but not in D2 mice. 4. The formation of N-hydroxy-Trp-P-2 corresponded with the increase in the number of the revertants, and with the activities of aromatic hydrocarbon hydroxylase and biphenyl 2-hydroxylase. 5. Addition of alpha-naphthoflavone to microsomes from control and 3-methyl-cholanthrene-treated B6 mice effectively decreased the activities to convert Trp-P-2 to a mutagen(s) and to N-hydroxylate Trp-P-2. 6. These results indicate that N-hydroxy-Trp-P-2 is a proximate or ultimate mutagenic principle of Trp-P-2.

Animals↗

Polymorphism in stereoselective hydroxylations of mephenytoin and hexobarbital by Japanese liver samples in relation to cytochrome P-450 human-2 (IIC9).

1. Stereoselective 4'-hydroxylations of R-(--)-mephenytoin and S-(+)-mephenytoin were determined in liver microsomes of 19 Japanese subjects. 2. The content of P-450 human-2 assessed by Western-blots correlated with microsomal S-(+)-mephenytoin 4'-hydroxylation. Antibody raised against P-450 human-2 effectively inhibited microsomal S-(+)-mephenytoin 4'-hydroxylation, but was less efficient for inhibition of R-(--)-mephenytoin 4'-hydroxylation in extensive metabolizers, and 4'-hydroxylation of both mephenytoin enantiomers in poor metabolizers. 3. Similar results were observed on the stereoselective hydroxylations of R-(--)- and S-(+)-hexobarbital. Clear correlations were observed for the content of P-450 human-2 and microsomal R-(--)-hexobarbital 3'alpha-hydroxylation and S-(+)-hexobarbital 3'beta-hydroxylation. 4. Moreover, yeast microsomes expressing P-450 human-2 cDNA showed high stereoselectivities for hydroxylations of mephenytoin and hexobarbital similar to those observed in human liver. 5. Two other cytochromes P-450(IIC 9/10) expressed in yeast, whose cDNA were synthesized by site-directed mutagenesis from human-2 cDNA, showed no stereoselectivity for the hydroxylations of mephenytoin and hexobarbital, in spite of the modification of only two amino acid substitutions or deletions in the whole sequence. 6. Only a cytochrome derived from P-450 human cDNA corresponding to P-450 human-2 was expressed in human livers, the two cytochromes of the three related IIC9/10 forms were not expressed. 7. These findings indicate that P-450 human-2 is the major cytochrome P-450 responsible for the polymorphisms in stereoselective hydroxylations of mephenytoin and hexobarbital.

Cytochrome P-450 Enzyme System↗

Absence of mutatins in the analysis of coding sequences of the entire transforming growth factor beta type II receptor gene in sporadic humangastric cancer using genomic DNA and intron primers.

Mutations in the transforming growth factor beta type II receptor (TGFbetaRII) gene have been detected in several human cancers that represent the phenotype of genomic instability. To establish a basis for diagnosis of cancer patients, we previously determined the exon-intron organization of the TGFbetaRII gene. The results indicated that TGFbetaRII protein is encoded by 567 codons in 7 exons. In this study, we further determined the nucleotide sequences surrounding these 7 exons and designed 8 sets of intron-based primers to examine the entire coding region of the TGFbetaRII gene. By using these primers, we screened for mutations of the TGFbetaRII gene in DNAs of 32 sporadic gastric cancer patients in whom one case showed MI+ (3.1%) at two loci. We found no mutations, and these data support other recent evidence that TGFbetaRII mutations rarely occur except in colon and gastric tumors with MI.

Chromosome Mapping↗

Epidermoid cyst of an intrapancreatic accessory spleen--a case report.

We report an extremely rare case of a splenic epidermoid cyst of the pancreas in a 51-year-old Japanese male with no clinical symptoms. A cystic tumor of the pancreatic tail was detected incidentally by abdominal ultrasonography. The patient was referred to the Gunma University Hospital for further examination of the pancreatic tumor. Upon diagnosis of a benign cystic tumor, a distal pancreatectomy with splenectomy was performed. Microscopically, the multicystic tumor, which was surrounded by the splenic tissue, was located within the pancreatic tissue. The cysts were lined by non-keratinizing squamous epithelium. The diagnosis of an epidermoid cyst occurring in an intrapancreatic accessory spleen was confirmed. To our knowledge, this is the 4th case ever reported in the English literature.

Choristoma↗