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Biomedical subjects

M Kitada

Publications and source records attributed to M Kitada.

At least 145 records · Page 8Linked to original sources
PubMed1990

Metabolic activation of aflatoxin B1 and 2-amino-3-methylimidazo[4,5-f]-quinoline by human adult and fetal livers.

The mutagenic activation of promutagens by human adult and fetal livers was investigated using the umu test system. Among the promutagens studied, aflatoxin B1 (AFB1) and 2-amino-3-methyl-imidazo[4,5-f] quinoline (IQ) were efficiently activated to mutagens by both adult and fetal livers. 7,8-Benzoflavone inhibited the activation of IQ by fetal livers, but the inhibition observed in fetal livers was much less than that observed in adult livers. Antibodies to P450HM1 (P450111A4) and P450HFLa markedly inhibited the activation of AFB1 by adult and fetal livers, respectively. The formation of genotoxic product(s) from IQ in human adult livers was almost completely inhibited by anti-P448H (P4501A2) antibodies but not by anti-P450HM1 antibodies, whereas that in fetal livers was inhibited by both anti-P450HFLa and anti-P450IA2 antibodies. P450HFLa catalyzed the mutagenic activation of both AFB1 and IQ in a reconstituted system. On the contrary, P450HM1 catalyzed the mutagenic activation of AFB1 but not IQ. A preparation of cytochrome P450 partially purified from human fetal livers and cross-reactive with anti-P450IA2 antibodies was found to be active for mutagenic activation of IQ in a reconstituted system. These results indicate that P450HFLa and P450HM1 are mainly involved in the genotoxic product formation from AFB1 in fetal and adult livers, respectively, and that the metabolic activation of IQ in fetal livers is catalyzed by two forms of cytochrome P450, P450HFLa, and cytochrome P450 immunochemically related to P450IA2 but that in adult livers it is mainly catalyzed by cytochrome P450 related to P450IA2.

Adult↗
PubMed1990

DNA sequences required for the alkalophily of Bacillus sp. strain C-125 are located close together on its chromosomal DNA.

Two alkali-sensitive mutants of alkalophilic Bacillus sp. strain C-125 were obtained. Mutant 38154 showed defective regulation of internal pH. Plasmids pALK1 and pALK2, containing DNA fragments different from those of the parent strain, were able to recover alkalophily in mutants 18224 and 38154, respectively. DNA analysis suggested that the two fragments overlapped on the chromosomal DNA of strain C-125.

Bacillus↗
PubMed1990

A survey of sudden death among school children in Osaka Prefecture.

For 2 years, from January 1985 to December 1986, we carried out a thorough investigation of sudden death or apparent sudden death in a population between 5 and 19 years of age in Osaka Prefecture. Sudden death (unexpected death caused by intrinsic factors within 24 h after the onset of symptoms) occurred in 62 boys and 30 girls, with an annual sudden death rate of 3.0 per 100,000 for boys and 1.5 per 100,000 for girls. Of these 92 deaths, 64 occurred among school children (elementary or high school students), and it was these that were subjected to further analyses. Of the school children deaths, 29.7% seemed to be apparent sudden cardiac death (based on circumstances immediately before death, although there was no definite evidence for sudden cardiac death), and 29.7% were sudden death clearly attributable to underlying heart diseases (hence, sudden cardiac death in the usual meaning of this term accounted for about 60% of the 64 sudden deaths). In addition, 17.2% of the 64 cases were sudden death from bronchial asthma. Analysis of seasonal variation in the incidence of sudden death showed that apparent sudden cardiac death frequently occurred in summer, while sudden death clearly attributable to underlying cardiac diseases often took place in winter, sudden death from bronchial asthma occurred chiefly in summer and fall. Of the total number of sudden deaths, death occurred during exercise in 29.7%, and during sleep in 18.8% of individuals. The percentage of sudden deaths occurring during school hours was as low as 23.4% (15/64). Analysis of the physical condition of the 64 sudden death cases immediately before death disclosed the presence of respiratory infection in 10.9%, fatigue in 21.9%, lack of sleep in 4.7% and other conditions in 4.7%. Thus, the percentage of sudden deaths which occurred under ordinary physical conditions was 57.8% (37/64), of which 14 deaths (21.9% of the total) were associated with exercise.

Adolescent↗
PubMed1990

Asymptomatic adrenal tumor; 386 cases in Japan including our 7 cases.

To clarify the indication of surgery in incidentally discovered asymptomatic adrenal masses, we analyzed 386 Japanese cases, 379 cases reported in Japan during the past 25 years (from 1964 to 1988) and 7 cases from our own experience. From a total of 460 patients, we carefully selected 379 patients satisfying our criterion of the absence of symptoms and signs suggestive of active hormone over-secretion as described in each case report. From the Japanese series, there was a high incidence of pheochromocytoma patients (20 of 37 patients) who had no symptoms and signs but had high plasma or urine catecholamines. Scintigraphy with 131I-meta-iodo-benzyl-guanidine was useful in the diagnosis of pheochromocytoma. For the other asymptomatic adrenal tumors, except for myelolipoma and adrenal cyst, differential diagnosis between malignant and benign adrenal lesions by imaging procedures such as whole body computed tomography (CT), ultrasonography (US), adrenocortical scintigraphy, and angiography was not always possible. In addition, among the 109 patients with cortical tumors whose hormonal data were reported, no clear-cut differentiation of malignant tumor from benign by means of these data could be obtained. Since 1980 whole body CT scanner and high resolution US scanner have become widely available, and there have been 283 cases of asymptomatic adrenal tumors who satisfied our criterion. Cortical carcinomas smaller than 3 cm and 6 cm in diameter account for 3.8% and 6.6%, respectively, of the total of 101 cases of cortical carcinoma, cortical adenoma, ganglioneuroma, and hemangioma during this period. The size of the smallest cortical carcinoma with metastasis was 2 cm in diameter in this series. Pre-operatively, an adrenocortical carcinoma 2.8 cm in diameter in our patient could not be diagnosed as such by imaging techniques and measurement of plasma hormones. These findings suggest that an adrenal mass larger than 3 cm should be removed and a patient with a smaller cortical tumor should be carefully followed up.

17-Hydroxycorticosteroids↗
PubMed1990

[Influence of gastric juice on human amylase activity].

Although it is well established that amylase activity is inactivated by acid, little is known about the influence of native gastric juice on amylase activity. We investigated the effect of gastric juice, acid, and pepsin on both pancreatic (P-) and salivary (S-) isoamylase activities in vitro. S- and P-isoamylase activities were completely inactivated by HCl (10 mEq/l), but 20% of each isoamylase activity remained when bovine serum albumin (BSA) (3%) was added. However pepsin (0.2 tyrosine mg/ml/min) inactivated both isoamylase activities even though BSA was added. When saliva or pancreatic juice was mixed with gastric juice, both isoamylase activities were detected until the mixing ratio was 3:7 (gastric juice:saliva or pancreatic juice, v/v). It is suggested that some of both isoamylase activities could survive after exposure to gastric juice in the stomach and duodenum, depending on the concentrations of acid and protein in gastric juice, and mixing ratio to gastric juice.

Amylases↗
PubMed1990

Isolation of cDNAs coding for three different forms of liver microsomal cytochrome P-450 from polychlorinated biphenyl-treated beagle dogs.

Three different cDNA clones, namely DM1-1, Dah1, and Dah2, encoding hepatic cytochrome P-450, were isolated from a cDNA library in lambda gt11 constructed from liver RNA of polychlorinated biphenyl-treated beagle dogs. DM1-1 was 1857 base pairs (bp) long and encoded a polypeptide of 457 residues. Dah1 was 2394 bp long and contained an entire coding region for 524 amino acid residues. In addition, Dah2 was 1623 bp long and had an open reading frame consisting of 503 amino acid residues, although it lacked the translational initiation codon. Judging from the similarity of the nucleotide and amino acid sequences, forms of cytochrome P-450 encoded by DM1-1, Dah1, and Dah2 were judged to belong to the P450IIC, P450IA1, and P450IA2 subfamilies, respectively. Northern blot analysis of RNA from various tissues, using the specific 3' noncoding regions of Dah1 and Dah2 as probes, indicated that mRNAs for P-450(Dah1) and P-450(Dah2) were not detectable in tissues from untreated dogs, except for P-450(Dah2) in livers. Polychlorinated biphenyl induced both mRNAs in liver, kidney, and lung, especially in the kidney.

Amino Acid Sequence↗
PubMed1990

Induction and immunohistochemical localization of cytochrome P-450 PCN by non-steroidal compound, in rat liver microsomes.

Induction of cytochrome P-450 PCN (P-450 PCN) by non-steroidal compound, M79193 (cyclohexane spiro-2,6-chloro-1'-(3-dimethyl-aminopropyl) spiro(chroman-4,4'-imidazolidine)-2',5'-dione], was investigated in both sexes of rats. The immunohistochemical localization of P-450 PCN was also studied in liver lobules of untreated and M79193-treated male rats. Immunoblot analysis of rat liver microsomes with anti-P-450 PCN indicated that the amount of P-450 PCN increased 5- to 7-fold by the treatment with M79193, but no increase was observed in P-450 PB-1 (P450IIB1) or P-450 MC-1 (P-450IA1). P-450 PCN was uniformly distributed in liver lobule of untreated rats, and was significantly increased by the treatment with M79193 in both the periportal and pericentral regions of the lobules.

Animals↗
PubMed1989

[Growth hormone response to arginine administration in diabetics--with special reference to the multiple regression analysis in association with diabetic retinopathy].

In 107 patients with non-insulin dependent diabetes(NIDDM), plasma growth hormone(GH) responses during standard arginine test (0.5 g/kg of body weight) were studied and analyzed in comparison with those in 17 normal subjects. The indices of the responsiveness of GH, peak value of GH, sum of GH values(sigma GH), area of GH curve(integral of GH), sum of GH values above fasting level(sigma delta GH) and area of GH curve above fasting level(integral of delta GH) during the test (2 hr) were calculated. Data were also analyzed with multiple regression analysis using stepwise method for variable selection. Basal level of GH was significantly higher in diabetic patients than in normal subjects (2.1 +/- 1.7 vs. 1.6 +/- 0.5 ng/ml, mean +/- SD, p less than 0.05), and sigma GH and integral of GH were also higher in diabetic patients. There was a significantly positive correlation between fasting plasma glucose(FPG) and basal level of GH (r = 0.24, n = 107, p less than 0.05), and the indices of GH responses except delta GH and GH peak value (r = 0.24 to 0.31, p less than 0.05 to 0.01). Some indices of GH responses (sigma delta GH, sigma GH, integral of delta GH and integral of GH) were significantly higher in the poor control group (patients with FPG above 180 mg/dl, n = 29) of diabetic patients than in the good control group (patients with FPG below 140 mg/dl, n = 59), or in the group with no abnormal findings of retinopathy (n = 46). During the follow-up of retinopathy for 2.5 years on the average, progression of retinopathy was found in 21 out of 107 patients. Significantly higher GH, and GH in the patients with increasing severity of retinopathy were revealed retrospectively compared to the patients without it. However, there were no significant differences in these parameters between both groups matched by FPG or severity of retinopathy. Multiple regression analysis to the basal GH level and GH responses during arginine infusion as criterion variables of various predictor variables (total 44 factors: biochemical laboratory data, indices of glucose and insulin response to oral glucose load, indices of glucose response to arginine, age, age of the onset, obese index, duration of retinopathy, neuropathy, and therapy) were performed in 86 patients using forward and backward method for variable selection. Basal plasma level of GH showed close positive association with therapy and proteinuria and negative association with age and obesity. Five of 6 indices of GH responsiveness showed significant relationship with retinopathy.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1989

Purification of cytochrome P-450 from polychlorinated biphenyl-treated crab-eating monkeys: high homology to a form of human cytochrome P-450.

Cytochrome P-450, designated as P-450-MK2, was purified to an electrophoretic homogeneity from polychlorinated biphenyl (PCB)-treated female crab-eating monkeys. P-450-MK2 catalyzed nifedipine and nilvadipine oxidations, at a rate comparable to human P-450-HM1. The N-terminal amino acid sequence of P-450-MK2 was highly homologous to those of P-450-HM1 and NF 25. The antibodies to P-450-HM1 recognized P-450-MK2 and effectively inhibited the activity of testosterone 6 beta-hydroxylase in monkey liver microsomes. These results suggest that a form of cytochrome P-450 corresponding to human P-450-HM1 or P-450NF which belongs to the P450 III gene family is also present in liver microsomes of crab-eating monkeys.

Amino Acid Sequence↗
PubMed1989

Effects of serum testosterone level with buserelin on the activities of drug and testosterone hydroxylase and on the content of a male-specific form of cytochrome P-450 in male rats.

The effects of administration of buserelin, a synthetic agonist of lutenizing hormone-releasing hormone (LH-RH), on the content of P-450-male, a male specific form of cytochrome P-450, and the activities of drug and testosterone hydroxylases were examined in liver microsomes of male rats. Administration of buserelin resulted in a decrease in the serum level of testosterone in a dose-dependent manner. Similar decreases were seen in the activities of aminopyrine N-demethylase, 7-propoxycoumarin O-depropylase and testosterone 2 alpha- and 16 alpha-hydroxylases, but not in the activity of aniline p-hydroxylase. Thus, correlations were observed between the serum level of testosterone and the activities of drug and testosterone hydroxylases except for aniline p-hydroxylase. These results indicate that the drug and testosterone hydroxylases are affected sensitively and sequentially by the changes in the testosterone levels in the body.

Aminopyrine N-Demethylase↗
PubMed1989

Comparative study of cytochrome P-450 in liver microsomes. A form of monkey cytochrome P-450, P-450-MK1, immunochemically cross-reactive with antibodies to rat P-450-male.

Cytochrome P-450, designated as P-450-MK1, which is cross-reactive with antibodies to rat P-450-male, was purified to an electrophoretical homogeneity from liver microsomes of the untreated male crab-eating monkey. The molecular weight of P-450-MK1 was estimated to be 50,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The oxidized form of P-450-MK1 showed a peak at 418 nm, indicating that this cytochrome is in a low spin state. The carbon monoxide-bound reduced form showed a peak at 451 nm. The first 22 amino acid residues of the NH2-terminal sequence of P-450-MK1 was fairly homologous to those of P-450-male (75% identity, not including unidentified amino acid residues). Unlike the P-450-male, P-450-MK1 did not exhibit catalytic activities for testosterone 2 alpha- and 16 alpha-hydroxylations and catalyzed testosterone 6 beta-hydroxylation. It is, therefore, suggested that although the spectral and immunochemical properties and the N-terminal amino acid sequence of P-450-MK1 were similar to those of P-450-male, the physiological functions of P-450-MK1 may be somewhat different from those of P-450-male. Comparison of the physico-chemical properties of P-450-MK1 with those of P-450-D1 and P-450-HM2, which are cross-reactive with anti-P-450-male antibodies, purified from liver microsomes of dogs and humans, respectively, are also discussed.

Amino Acid Sequence↗
PubMed1989

A novel form of cytochrome P-450 in beagle dogs. P-450-D3 is a low spin form of cytochrome P-450 but with catalytic and structural properties similar to P-450d.

A form of cytochrome P-450, P-450-D3, cross reactive with antibodies to rat P-450d was purified from liver microsomes of polychlorinated biphenyl (PCB)-treated female Beagle dogs to an electrophoretic homogeneity. Judging from the result of sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE), the molecular weight of P-450-D3 was estimated to be 54,000. The oxidized form of P-450-D3 showed a peak at 416 nm indicating that the cytochrome is mostly in a low spin state. The carbon monoxide bound reduced form of P-450-D3 showed a peak at 448 nm. In a reconstituted system, P-450-D3 catalyzed drug oxidations including benzphetamine and aminopyrine N-demethylations, 7-ethoxycoumarin and p-propoxyaniline O-dealkylations, and aniline and benzo(a)pyrene hydroxylations. The rate of aniline hydroxylation catalyzed by P-450-D3 was similar to that catalyzed by P-450c which is a low spin form of cytochrome P-450 purified from liver microsomes of PCB-treated rats, whereas the catalytic activities of P-450-D3 for 7-ethoxycoumarin O-deethylation and benzo(a)pyrene hydroxylation were considerably lower than those of P-450c. The amino terminal portion of P-450-D3 was found to be highly similar to those of P-450d, human P3-450 and P3-450 when four amino acid deletions were tentatively inserted between fifth and sixth amino acids from the N-terminal, but not that of P-450c which is a low spin form of cytochrome P-448 purified from rat liver microsomes. These results indicate that Beagle dogs possess a low spin form of cytochrome P-450 with spectral properties similar to P-450c but with catalytic and structural properties similar to P-450d.

Amino Acid Sequence↗
PubMed1989

Isolation of a new human fetal liver cytochrome P450 cDNA clone: evidence for expression of a limited number of forms of cytochrome P450 in human fetal livers.

From a human fetal liver cDNA library, a new cDNA clone (lambda HFL10) was isolated using an antiserum to P450 HFLa, which has been isolated from livers of human fetuses. Cytochrome P450 cDNAs, namely lambda hPA6, lamda hP2-1, and lambda hPD4 which were highly homologous to cDNA clones, pHY13, Hp1-1, and phP450j, respectively, were also isolated from the cDNA library of human adult livers. Using these cDNA clones as probes together with Lambda HFL10, Northern blot analysis was conducted to determine whether all of these cytochromes were expressed in human fetal livers. The results clearly showed that only P450 HFL10 mRNA was detected in human fetal livers. This result supports the allegation that there is a much more limited number of forms of cytochrome P450 in human fetal livers than in adult livers.

Amino Acid Sequence↗
PubMed1989

Distributional variation of P-450 immunoreactive hepatocytes in human liver disorders.

Implications of P-450 in human hepatic disorders were immunohistochemically examined. We first confirmed that an antibody against P-450-HM1, an isozyme of cytochrome P-450 which was purified from human livers at autopsy, detects only P-450 on immunoblots. In a study of 79 consecutive autopsied livers using the avidin-biotin-peroxidase complex method, the antibody reacted strongly with fetal hepatocytes, the reaction being more intense in the left lobe than in the right lobe. In normal livers, immunoreactivity was confined to centrilobular hepatocytes, decreasing in the periportal zone. Enhanced expression was occasionally found in scattered hepatocytes and in hepatocytes surrounding sublobular veins; this enhancement was related to longterm steroid therapy. No specific induction was observed in patients with toxic hepatitis. In patients with fibrosis, cirrhosis, or regenerative nodules, however, P-450-positive hepatocytes were observed in the periportal and middle zones as well as in the central zone. In contrast, hepatocellular carcinomas were devoid of P-450 immunoreactivity. These results suggest that P-450-HM1, which is abundant in the fetal liver, is reexpressed in regenerating hepatocytes but not in cancers.

Antibody Specificity↗
PubMed1989

Interspecies homology of cytochrome P-450: toxicological significance of cytochrome P-450 cross-reactive with anti-rat P-448-H antibodies in liver microsomes from dogs, monkeys and humans.

The mutagenic activation of various promutagens by liver microsomes from dogs, monkeys and humans was investigated. Dog liver microsomes efficiently catalyzed the mutagenic activation of Trp-P-2 and Glu-P-1 followed by IQ and AAF. Monkey liver microsomes were most active in the activation of IQ followed by Glu-P-1, AAF and Trp-P-2. Although there were remarkable individual differences, human liver microsomes were found to be most active in the mutagenic activation of IQ followed by Trp-P-2, Glu-P-1 and AAF. Antibodies against rat P-448-H inhibited the mutagenic activation of Glu-P-1, Trp-P-2 and IQ in rat and dog liver microsomes, and Glu-P-1 and Trp-P-2 in monkey liver microsomes. The activation of Glu-P-1 and IQ in human liver microsomes was also strongly inhibited by anti-P-448-H antibodies. The amounts of cytochrome P-450 cross-reactive with anti-P-448-H antibodies in human liver microsomes highly correlated with the capacity to activate Glu-P-1, Trp-P-2 and IQ but not AAF.

2-Acetylaminofluorene↗
PubMed1989

Mutagenic activation of aflatoxin B1 by P-450 HFLa in human fetal livers.

The genotoxic and mutagenic activation of promutagens by human fetal livers was measured by the induction of umu gene expression in Salmonella typhimurium TA1535/pSk1002. Liver homogenates of human fetuses were the most active for the mutagenic activation of aflatoxin B1 (AFB1), followed by 2-amino-3-methylimidazo(4,5-f)quinoline (IQ), and to a lesser extent by 2-amino-6-methyldipyrido(1,2-a:3',2'-d)imidazole (Glu-P-1). The amounts of P-450 HFLa immunochemically determined in human fetal livers correlated highly with the induction of umu gene expression by AFB1 (r = 0.98, n = 5). P-450 HFLa catalyzed the mutagenic activation of AFB1 in a reconstituted system: cytochrome b5 markedly stimulated the activation. Anti-P-450 HFLa antibodies inhibited the mutagenic activation of AFB1 in a dose-dependent manner. These results strongly support the idea that P-450 HFLa is responsible for the mutagenic activation of AFB1 in human fetal livers.

Aflatoxin B1↗
PubMed1989

Decrease in a constitutive form of cytochrome P-450 by macrolide antibiotics.

The effects of administration of macrolide antibiotics on cytochrome P-450 in liver microsomes of male rats were investigated. The macrolides tested were those with a 14-membered ring such as oleandomycin, troleandomycin, erythromycin and erythromycin estolate, and those with a 16-membered ring such as rokitamycin, leucomycin and josamycin. Cytochrome P-450-metabolite complex was detected with oleandomycin, troleandomycin, erythromycin and erythromycin estolate, whereas no such effect was observed with rokitamycin, leucomycin and josamycin. The content of uncomplexed cytochrome P-450 in liver microsomes remained unchanged with rokitamycin, leucomycin and josamycin, decreased with troleandomycin and oleandomycin, and increased with erythromycin and erythromycin estolate, indicating that oleandomycin, troleandomycin, erythromycin and erythromycin estolate also affect the amounts of other forms of cytochrome P-450. The administration of oleandomycin, troleandomycin, erythromycin and erythromycin estolate resulted in a dramatic decrease in the activities of testosterone 2 alpha- and 16 alpha-hydroxylases in liver microsomes. Supporting these results, a marked decrease (more than 75%) in the content of P-450-male, a major constitutive form of cytochrome P-450 in male rats, was noted with oleandomycin, troleandomycin, erythromycin and erythromycin estolate, while the decrease was rather small with rokitamycin and leucomycin. We conclude that the administration of the 14-membered ring macrolides may affect drug and steroid metabolism not only by formation of P-450-metabolite complex but also by decrease in the content of P-450-male.

Animals↗