Studies on chemical modification of monensin IX. Synthesis of 26-substituted monensins and their Na+ ion transport activity

The C-26 modified monensin derivatives, 26-O-benzoylmonensin (3), 26-O-benzylmonensin (4) and 26-phenylaminomonensin (5) were prepared from monensin (1). Na+ ion transport activity through biological membrane and antibacterial activity of 3-5 were evaluated and compared with the activities reported for a 26-phenylurethane derivative (2). Among these compounds, 5 showed the largest Na+ ion transport and antibacterial activities. In these compounds, the formation of head-to-tail hydrogen bonds was suggested to be an important factor for Na+ ion transport and antibacterial activities.

Photoaffinity labeling and site-directed mutagenesis of rat squalene epoxidase

Squalene epoxidase (SE) (EC 1.14.99.7) is a flavin-requiring, non-cytochrome P-450 oxidase that catalyzes the conversion of squalene to (3S)-2,3-oxidosqualene. Photolabeling and site-directed mutagenesis were performed on recombinant rat SE (rrSE) to elucidate the location and roles of active-site residues important for catalysis. Two new benzophenone-containing analogs of NB-598, a nanomolar inhibitor of vertebrate SE, were synthesized in tritium-labeled form. These photoaffinity analogs (PDA-I and PDA-II) became covalently attached to SE when irradiated at 360 nm. Lys-C digestion and HPLC purification of [3H]PDA-I-labeled rrSE resulted in isolation of a single major peptide. MALDI-TOF mass spectrometry of this peptide indicated a covalent adduct between PDA-I and a tripeptide, Asp-Ile-Lys, beginning at Asp-426 of rat SE. Based on the labeling results, three mutant constructs were made. First, the D426A and K428A constructs showed a 5- to 8-fold reduction in SE activity compared with wild-type enzyme, while little change was observed in the I427A mutant. Second, a set of five mutant constructs was prepared for the conserved region based on the structure of the flavoprotein p-hydroxybenzoate hydroxylase (PHBH). Compared with wild-type, D284A and D407A showed less than 25% SE activity. This reduction also appeared to correlate with reduced affinity of the mutant proteins for FAD. Finally, each of the seven Cys residues of rrSE were individually mutated to Ala. Three Cys substitutions had no effect on SE activity, and substitutions at Cys-500 and Cys-533 showed a 50% lower SE activity. Mutations at Cys-490 and Cys-557 produced proteins with negligible SE activity, implicating these residues as being either structurally or catalytically essential. Chemical modification of wildtype and Cys mutants with a thiol-modifying reagent support the existence of a disulfide bond between Cys-490 and Cys-557.

[Estimation of adverse drug reactions by the evaluation scores of subjective symptoms (complaints) and background of patients. V. Drug-induced gastrointestinal system disorders]

OBJECTIVES

The purpose of this study was to develop, implement, and assess an estimation procedure for preventing adverse drug reaction by subjective symptoms (complaints) of patients. This time, we focused and studied on drug-induced gastrointestinal system disorders.

METHODS

We have built a database for CARPIS (Case Reports of Adverse Drug Reaction and Poisoning Information System) since 1987. We studied 224 cases of drug-induced Gastrointestinal System Disorders (stomach or colon disorders: 148, esophagus disorders: 31, pancreas disorders: 45) cumulated in the CARPIS database. The evaluation scores were created based on the subjective symptoms and backgrounds of the patients. We estimated 224 cases using these evaluation scores.

RESULTS

We could estimate 137 cases (92.6%) in 148 cases to be stomach or colon disorders by the use of these evaluation scores. The validity of this evaluation scores was estimated to be as follows: Sensitivity = 92.6%, Specificity = 95.0% and Predictive Value of Positive Test (PVP) = 96.5%. The positive likelihood ratio (LR) was 18.5 and negative likelihood ratio was 0.08. On the other hand, in the case of esophagus disorders, PVP was 84.8% and LR was 18.1. In the case of pancreas disorders, PVP was 90.7% and LR was 21.7.

CONCLUSIONS

In this study, PVP and LR values were good. We thought that these evaluation scores could pick up the drug-induced gastrointestinal system disorders efficiently. We reported previously the evaluation scores about drug-induced liver disorders, extra-pyramidal symptoms, leukopenia and eruption before. In order to apply these evaluation scores onto the clinical practice, we prepared an evaluation form for subjective symptoms and backgrounds of the patients with adverse drug reactions. As a result, the adverse reactions symptoms of each one defined more.

[Application study of drug information to proper use of drugs--estimation of adverse drug reactions by the evaluation scores of subjective symptoms (complaints) and background of patients]

We have built a database for CARPIS (Case Reports of Adverse Drug Reaction and Poisoning Information System) since 1987, and the case reports of adverse drug reactions accumulated in the CARPIS database to be total about 20,000. The purpose of our study is to develop, implement, and assess an estimation procedure for preventing the adverse drug reactions by subjective symptoms (complaints) of patients using this CARPIS. The case reports of the adverse reactions are not a systematical study and are elapse reports by the case, which encountered on the way of the cure. Therefore, it might be possible to use as the data if not gaining enough evaluation. Especially, the abstracts in the annual meeting of the society are fragmentary and does not often have objective evidence. Therefore, we contrived an original evaluation method and carefully selected the case reports for our study. Also, the adverse reactions are very colorful and it is difficult to handle them at once. Therefore, we study every organ and want to aim to make a finally all-round format. We reported on the Liver disorders, the Extra-pyramidal symptoms, the Drug eruption, the Leukopenia and so on. We discovered that there was an adverse reaction which shows very peculiar subjective symptoms (ex. Extra-pyramidal symptoms) and unpeculiar subjective symptoms (ex. Leukopenia). We want to show our point of view and the future of our study below.

[Estimation of adverse drug reactions by the evaluation scores of subjective symptoms (complaints) and background of patients. IV. Drug eruptions]

OBJECTIVES

The purpose of this study is to develop, implement, and assess an estimation procedure for preventing adverse drug reaction by subjective symptoms (complaints) of patients. This time, we focused and studied on drug eruptions.

METHODS

We have built a database for CARPIS (Case Reports of Adverse Drug Reaction and Poisoning Information System) since 1987, and the case reports of adverse drug reactions accumulated in the CARPIS database to be total about 20,000. We studied 1473 cases of drug eruptions cumulated in CARPIS database. The evaluation scores were created based on the subjective symptoms and backgrounds of the patients. We estimated 1473 cases using this evaluation scores.

RESULTS

We could estimate 1455 cases (98.8%) in 1473 cases to be drug eruptions using this evaluation scores. The validity of this evaluation scores were sensitivity = 98.8%, specificity = 91.0% and predictive value of positive test = 99.4%. The positive likelihood ratio was 11.0 and negative likelihood ratio was 0.01.

CONCLUSIONS

This study confirmed the validity of our evaluation scores. We reported the evaluation scores about drug-induced liver diseases, drug-induced extra-pyramidal symptoms and drug-induced leukopenia before. In order to apply these evaluation scores to the clinical practice, we prepared an evaluation form for subjective symptoms and backgrounds of the patients with adverse drug reactions.

[Estimation of adverse drug reactions by the evaluation scores of subjective symptoms (complaints) and background of patients. III. Drug-induced leucopenia]

OBJECTIVES

The purpose of this study was to develop, implement, and assess an estimation procedure for preventing adverse drug reaction by subjective symptoms (complaints) of patients. This time, we carried out this study focusing on drug-induced leucopenia.

METHODS

We have built a database for CARPIS (Case Reports of Adverse Drug Reaction and Poisoning Information System) since 1987, and the total number of case reports of adverse drug reaction accumulated in the CARPIS database amounts to about 16,000. Using the date obtained from 139 cases of drug-induced leucopenia accumulated in the CARPIS database, we investigated a relationship between leucopenia and patients. The evaluation scores were created based on the subjective symptoms and backgrounds of the patients.

RESULTS

We could estimate 91 cases (65.5%) in 139 cases to be drug-induced leucopenia by the use of these evaluation scores. The validity of this evaluation scores was estimated to be as follows; sensitivity = 65.5%, specificity = 80.0% and predictive value of positive test (PVP) = 82.0%. The positive likelihood (LR) ratio was 3.3 and negative likelihood ratio 0.43.

CONCLUSIONS

In this study, PVP and LR values were not good, because among the symptoms of leucopenia a very few specific symptoms could be detected. But we reported previous by the evaluation scores about drug-induced liver disorders. Therefore, in order to apply these evaluation scores to the clinical practice, we prepared an evaluation form for subjective symptoms and backgrounds of the patients with adverse drug reactions. In the future, we plan to examine other adverse reactions which adds the data to this form.

Green tea polyphenols: novel and potent inhibitors of squalene epoxidase

The green tea gallocatechins, (-)-epigallocatechin-3-O-gallate (EGCG) (IC(50) = 0.69 microM), (-)-gallocatechin-3-O-gallate (GCG) (IC(50) = 0.67 microM), (-)-epicatechin-3-O-gallate (ECG) (IC(50) = 1.3 microM), and theasinensin A (IC(50) = 0.13 microM), were found to be potent and selective inhibitors of rat squalene epoxidase (SE), a rate-limiting enzyme of cholesterol biogenesis. On the other hand, flavan-3-ols without galloyl group at C-3 did not show significant enzyme inhibition. It was demonstrated for the first time that the cholesterol lowering effect of green tea may be attributed to their potent SE inhibition activities. Inhibition kinetics revealed that EGCG inhibited SE in noncompetitive (K(I) = 0.74 microM), and non-time-dependent manner. The potent enzyme inhibition would be caused by specific binding to the enzyme, and by scavenging reactive oxygen species required for the monooxygenase reaction.

[Estimation of adverse drug reactions by the evaluation scores of subjective symptoms (complaints) and background of patients. II. Drug-induced extrapyramidal symptoms]

OBJECTIVES

The purpose of this study was to develop, implement, and assess an estimation procedure for preventing adverse drug reaction by subjective symptoms (complaints) of patients. This time, we focused and studied on drug-induced extrapyramidal symptoms.

METHODS

We have built a database for CARPIS (Case Reports of Adverse Drug Reaction and Poisoning Information Systems) since 1987, and the case reports of adverse drug reaction accumulated in the CARPIS database to be total about 16,000. We studied for 180 cases of drug-induced extrapyramidal symptoms cumulated in CARPIS database. The evaluation scores were created based on the subjective symptoms and backgrounds of the patients. We estimated 180 cases using these evaluation scores.

RESULTS

We could estimate 178 cases (98.9%) in 180 cases to be drug-induced extrapyramidal symptoms using these evaluation scores. The validity of these evaluation scores were sensitivity = 98.9%, specificity = 98.0% and predictive value of positive test = 98.9%. The positive likelihood ratio was 49.5 and the negative likelihood ratio was 0.01.

CONCLUSIONS

This study confirmed the validity of our evaluation scores. We reported the evaluation scores about drug-induced liver diseases before. Therefore, to apply these evaluation scores onto the clinical practice, we prepared an evaluation form for subjective symptoms and backgrounds of the patients with adverse drug reactions.

Serotonin derivative, N-(p-Coumaroyl)serotonin, isolated from safflower (Carthamus tinctorius L.) oil cake augments the proliferation of normal human and mouse fibroblasts in synergy with basic fibroblast growth factor (bFGF) or epidermal growth factor (EGF)

N-(p-Coumaroyl)serotonin (CS) with antioxidative activity is present in safflower oil. We have reported that CS inhibits proinflammatory cytokine generation from human monocytes in vitro. As reactive oxygen species (ROS) affect cell proliferation, in this study the effect of CS on the proliferation of various cell types was examined. CS augments the proliferation of normal human and mouse fibroblast cells. The cells continue to proliferate in the presence of CS and form a transformed cell-like focus without transformation. CS, however, does not augment the proliferation of other cell types, either normal or tumor cells. CS augments the proliferation of fibroblasts in synergy with basic fibroblast growth factor (bFGF) or epidermal growth factor (EGF), but not with acidic FGF(aFGF) or platelet-derived growth factor (PDGF). This study using synthesized derivatives of CS reveals that the growth-promoting activity is not due to antioxidative activity. These findings indicate that CS is a natural compound with unique growth-promoting activity for fibroblasts.

[Estimation of adverse drug reactions by the evaluation scores of subjective symptoms (complaints) and background of patients. I. Drug-induced liver disorders]

The purpose of this study was to develop, implement, and assess an estimation procedure for preventing drug-induced liver disorders. We have built a database for CARPIS (case reports of adverse drug reaction and poisoning information services) since 1987, and the case reports of adverse drug reaction accumulated in the CARPIS database to be total about 11,000. We studied the estimation procedure by evaluating the subjective symptoms, backgrounds and laboratory data of patients in 199 cases cumulated in the CARPIS database. The evaluation scores were created on the basis of the subjective symptoms and backgrounds of the patients. Then, we re-estimated 199 cases with the evaluation scores, among which were 165 cases (82.9%) in 199 cases drug-induced liver disorders. For the rest of 34 cases (17.1%) drug-induced liver disorders could not be estimated from our evaluation scores. These 34 cases were either those which the subjective symptoms were not described in their reports, because the patients were hospitalized for other diseases and drug-induced liver disorders were discovered by a clinical examination, or cases of infants for whom it was difficult to confirm the subjective symptoms. The validity of this evaluation scores were sensitivity = 82.9%, specificity = 91.0% and predictive value of positive test = 94.8%. To apply this evaluation scores onto the clinical practice, we prepared an evaluation form for the subjective symptoms and backgrounds of the patients with drug suspecting-induced liver disorders.

Serotonin derivative, N-(p-coumaroyl) serotonin, inhibits the production of TNF-alpha, IL-1alpha, IL-1beta, and IL-6 by endotoxin-stimulated human blood monocytes

We have reported that N-(p-coumaroyl) serotonin (CS) and its derivatives with antioxidative activity are present in safflower seeds. As reactive oxygen species (ROS) are implicated in the signaling of lipopolysaccharide (LPS), we examined whether CS has a suppressive effect on inflammatory cytokine generation from human monocytes in vitro. CS at 50-200 microM reduced tumor necrosis factor (TNF), interleukin-1 (IL-1), and IL-6 activities in the culture supernatants from LPS-stimulated human blood monocytes without cytotoxicity. ELISA assay revealed that the production of TNF-alpha, IL-1alpha, IL-1beta, and IL-6 was inhibited by CS. Northern blot analysis showed that LPS-induced expression of these cytokine mRNA in monocytes was suppressed by CS. NF-kappaB activation was also inhibited by CS. These findings indicate that CS has a suppressive effect on proinflammatory cytokine production from monocytes, and this effect is based in part on the suppression of cytokine mRNA expression through inhibition of NF-kappaB activation.

Inhibitory effects of fatty acid monoesters of 2-O-beta-D-glucosylglycerol on Epstein-Barr virus activation

In a screening for cancer chemopreventing agents several glycosylglycerols were found to be active. In order to optimize the anti-tumor activity of this class of compounds, a series of 1-O-acyl-2-O-beta-D-glucopyranosyl-sn-glycerols differing in the acyl chain length, which varied from C4 to C18, were examined for their in vitro anti-tumor promoting effects on Epstein-Barr virus early antigen (EBV-BA) activation induced by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA). Among the compounds tested, the monohexanoyl derivative was the most active and, noteworthy, the most potent compound of the glycosylglycerol series hitherto known.

Contribution of cytosolic ionic and energetic milieu change to ischemia- and reperfusion-induced injury in guinea pig heart: fluorometry and nuclear magnetic resonance studies

The contribution of cytosolic ion and energy milieu changes to ischemia/reperfusion injury was investigated in isolated guinea-pig hearts and mitochondria, with fluorometry and 31P nuclear magnetic resonance (NMR). The fura-2 Ca2+ signal during ischemia in the guinea-pig Langendorff heart changed triphasically (phases I, II, and III) and rapidly returned to the control level after the reperfusion. These triphasic changes during ischemia were affected by various agents that affect the cytosolic ion milieu: the combination of asebotoxin-III and dihydroouabain (which increase intracellular Na+) caused an increase in Ca2+ levels in the final stage (phase III) with a manifestation of contracture after the reperfusion of the heart. Inhibitors of the H+-Na+ exchange such as 5-(N-ethyl-N-isopropyl)-amiloride (EIPA) produced a significant restorative effect on the contractility of the reperfused heart with increased proton and decreased Na+ and Ca2+ in the cytosol. The mitochondrial matrix Ca2+ ([Ca2+]m) preloaded with abnormally high Ca2+ levels was markedly increased by perfusion with either a physiologic concentration of Ca2+ or an acidified perfusate. These [Ca2+]m increases were reduced by the H+-Na+ and H+-K+ exchange inhibitor (EIPA; omeprazole), respectively. These findings will help to explain the Ca paradox at the mitochondria level (i.e., mitochondria for Ca2+ pumping play an essential role in the cellular homeostasis of Ca2+ for the maintenance of cell functions of the heart, acting like a Ca2+ scavenger in the cytosol). Factors that induce Ca2+ overload on mitochondria via sarcolemmal Ca2+ influx and any exchange mechanisms with Na+, K+, Ca2+, and H+ will lead to a loss of contractility, associated with the extremely reduced level of free energy change predicted from the reduced ATP x PCr/Pi ratio by 31P NMR.

Antioxidative compounds isolated from safflower (Carthamus tinctorius L.) oil cake

Seven antioxidative serotonin derivatives were isolated from safflower (Carthamus tinctorius L.) oil cake. Their structures were established as N-[2-(5-hydroxy-1H-indol-3-yl)ethyl]ferulamide (1), N-[2-(5-hydroxy-1H-indol-3-yl)ethyl]-p-coumaramide (2), N,N'-[2,2'-(5,5'-dihydroxy-4,4'-bi-1H-indol-3,3'-yl)diethyl]- di-p-coumaramide (3), N-[2-[3'-[2-(p-coumaramido)ethyl]-5,5'-dihydroxy- 4,4'-bi-1H-indol-3-yl]ethyl]ferulamide (4), and N,N'-[2,2'-(5,5'-dihydroxy-4,4'-bi-1H-indol-3,3'-yl)diethyl]- diferulamide (5), N-[2-[5-(beta-D-glucosyloxy)-1H-indol-3-yl)ethyl]- p-coumaramide (6), and N-[2-[5-(beta-D-glucosyloxy)-1H-indol-3-yl)ethyl]ferulamide (7). Antioxidative activities of the compounds were measured by the ferric thiocyanate method and the alpha,alpha-diphenyl-beta-picrylhydrazyl (DPPH) method, and compounds 1-5 were found to have relatively strong antioxidative activity.

A simplified squalene epoxidase assay based on an HPLC separation and time-dependent UV/visible determination of squalene

A novel and highly simplified enzyme assay for squalene epoxidase (EC 1.14.99.7) has been developed. The assay relies on the UV/visible determination of squalene at 195 nm, as it elutes from an octadecylsilane HPLC column. An acetonitrile/water (95.5/0.5, v/v) mixture was found to provide an ideal mobile phase, into which aqueous enzyme reaction mixture aliquots could be injected. Squalene, the natural substrate for squalene epoxidase, may be quantitatively determined within the concentration range 0-30 microM, with a calibration curve exhibiting an r2 (where r2 is the square of the Pearson correlation coefficient r) of 0.995. The HPLC retention time for squalene was significantly longer (> 15 min) than that for any other component required to prepare an enzyme assay reaction mixture, so facilitating its identification and quantification. In this way HPLC was used to follow enzymic squalene consumption within aliquots taken over a 30-min period. Previously reported squalene epoxidase assays rely on the radiolabeling and subsequent monitoring of squalene as it is metabolized by the enzyme. A highly simplified enzyme assay for squalene epoxidase is therefore reported.

[Transformation of natural products into more potent compounds: chemical modification of monensin]

Monensin (1) is a representative compound of polyether ionophore antibiotics, which selectively transport Na+ ions. In order to obtain potent Na+ ionophores, the modification of the carboxyl group of monensin was carried out to yield monensylamino acids (2) and monensylamino acid-1,29-lactones (3). The Na+ permeability of ion through the erythrocyte membrane of 2 and 3 was evaluated by the 23Na-NMR method. Compound 2 showed less Na+ ion transport activity than monensin, probably due to the lower lipophilicity caused by the conformational change of the chain moiety of the molecules. Although 3 showed higher lipophilisity than 1, 3 had no Na+ ion permeability, probably due to loss of the carboxyl group. As more lipophilic compounds possessing a carboxyl group was supposed to have more ion transport activity, 7-O-acylmonensins (8) and 7-O-alkylmonensins (11) were synthesized. Among these compounds, the value of Na+ ion permeability of 7-O-benzylmonensin (11c) was 1.4 time that of 1. Further investigation was carried out by preparing various 7-O-(substituted benzyl)monensins (13), and 7-O-(p-ethylbenzyl)monensin (13b) exhibited the largest Na+ ion permeability, about twice the value of 1. In order to convert monensin (1) to Ca2+ ionophore, 7-carboxylmethylmonensin (18) via protected 7-oxomonensin (15), and 25-carboxylmonensin (26) were prepared. In the course of the synthesis, 15 was clarified as a useful intermediate to give 7-amino and 7-alkyl derivatives. Ca2+ ion transport activities of 18 and 26 were determined by a CHCl3 liquid membrane system. 25-carboxylmonensin (26) showed 70% of the activity of Ca2+ ionophore, lasalocid A, and compound 26 could be the lead compound for the preparation of a new Ca2+ ionophore.

Localization of the squalene epoxidase gene (SQLE) to human chromosome region 8q24.1

Squalene epoxidase (EC 1.14.99.7) catalyzes the first oxygenation step in sterol biosynthesis and is suggested to be one of the rate-limiting enzymes in this pathway. We previously isolated the mammalian squalene epoxidase cDNAs and demonstrated the transcriptional regulation of human squalene epoxidase by sterols and inhibitors. The present study was undertaken to determine the chromosomal mapping of the human squalene epoxidase gene (SQLE). PCR evidence localizes human SQLE to chromosome 8 by using the NIGMS (National Institute of General Medical Sciences) Human/Rodent Somatic Cell Hybrid Mapping Panel 2 as template. To refine the localization of human SQLE further, PCR on the Stanford G3 Radiation Hybrid Panel was performed. The result shows that human SQLE is most tightly linked to D8S508, which is reported to be located at 8q24.13-qter (lod score 7.87). Moreover, fluorescence in situ hybridization also maps human SQLE to 8q24.1.

Unusual effects of some vegetable oils on the survival time of stroke-prone spontaneously hypertensive rats

Preliminary experiments have shown that a diet containing 10% rapeseed oil (low-erucic acid) markedly shortens the survival time of stroke-prone spontaneously hypertensive (SHRSP) rats under 1% NaCl loading as compared with diets containing perilla oil or soybean oil. High-oleate safflower oil and high-oleate sunflower oil were found to have survival time-shortening activities comparable to that of rapeseed oil; olive oil had slightly less activity. A mixture was made of soybean oil, perilla oil, and triolein partially purified from high-oleate sunflower oil to adjust the fatty acid composition to that of rapeseed oil. The survival time of this triolein/mixed oil group was between those of the rapeseed oil and soybean oil groups. When 1% NaCl was replaced with tap water, the survival time was prolonged by approximately 80%. Under these conditions, the rapeseed oil and evening primrose oil shortened the survival time by approximately 40% as compared with n-3 fatty acid-rich perilla and fish oil; lard, soybean oil, and safflower oil with relatively high n-6/n-3 ratios shortened the survival time by roughly 10%. The observed unusual survival time-shortening activities of some vegetable oils (rapeseed, high-oleate safflower, high-oleate sunflower, olive, and evening primrose oil) may not be due to their unique fatty acid compositions, but these results suggest that these vegetable oils contain factor(s) which are detrimental to SHRSP rats.

Studies on chemical modification of monensin. VI. Preparation of C-7 modified monensins via protected 7-oxomonensin and evaluation of their ion transport activity

7-Carboxymethylmonensin (3), 7-aminomonensin (4), and 7-oxomonensin (5) were synthesized via protected 7-oxomonensin (2), which is expected to be a useful intermediate for the preparation of various monensin derivatives. intermediate for the preparation of various monensin derivatives. Compounds 3-5 exhibited smaller ion transport activity than monensin (1).

Studies on cardiac ingredients of plants. XIII: Chemical modification of gitoxin to cardiotonic compounds without vascular effect

Nitrated gitoxins (4) and bufotoxin homologues with various lengths of alkyl chain at C-3 of the steroid nucleus (10) were prepared from gitoxin (1). The pharmacological activities of the resulting compounds (4 and 10) were evaluated by measurement of inhibitory effect on NA+, K(+)-adenosine triphosphatase (ATPase) prepared from dog kidney, positive inotropic effect (PIE) on isolated guinea-pig papillary muscle preparations, and the effect on smooth muscle using the mesenteric artery from spontaneously hypertensive rats. Most of the compounds showed a smaller contractile effect on the arterial muscle. Among these compounds, gitoxin 3"-nitrate (4g) exhibited the most desirable biological activities, such as PIE comparable to that of 1, 1.25 times wider concentration-dependent range than 1, and lack of contractile activity on vascular muscle.

Antitumor-promoting activities of various synthetic 1-O-acyl-3-O-(6'-O-acyl-beta-D-galactopyranosyl)-sn-glycerols related to natural product from freshwater cyanobacterium Anabaena flos-aquae f. flos-aquae

1-O-Acyl-3-O-(6'-O-acyl-beta-D-galactopyranosyl)-sn-glycerol, which was isolated from a nitrogen-fixing fresh water cyanobacterium, Anabaena flos-aquae f. flos-aquae, was synthesized by utilizing lipase-catalyzed acylation. The antitumor-promoting activities of these galactolipids were evaluated using a short-term in vitro assay of Epstein-Barr virus activation in Raji cells induced by 12-O-tetradecanoyl- phorbol 13-acetate (TPA). The glyceroglycolipids which have a palmitoleoyl residue at the 1-O-position exhibited more potent activities than the others in this assay.

Inhibition of 12-O-tetradecanoylphorbol-13-acetate promoted mouse skin papilloma by digalactosyl diacylglycerols from the fresh water cyanobacterium Phormidium tenue

To search for possible antitumor-promoters, two digalactosyl diacylglycerols (DGDGs), which were obtained from the freshwater cyanobacterium Phormidium tenue and possessed a single pair of acyl residues, were evaluated for their inhibitory effects on the two-stage carcinogenesis test in mouse skin. Papillomas in mouse skin were initiated with 390 nmol of 7,12-O-dimethylbenz[a]anthracene and 1 week later, were promoted twice a week with 1.7 nmol of 12-O-tetradecanoylphorbol-13-acetate (TPA). Two DGDGs effectively inhibited tumor formation in the sensitive mouse stock even when these compounds were given 1 h before TPA treatment.

Transcriptional regulation of squalene epoxidase by sterols and inhibitors in HeLa cells

Regulation of squalene epoxidase (SE) gene expression was studied in comparison with those of 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase and low density lipoprotein (LDL) receptor. An increased expression of SE mRNA and protein content in mouse L929 cells grown in 10% lipoprotein-deficient fetal bovine serum (LPDS) for 48 h was found by performing immunoblot and Northern blot analyses when compared with the culture in the presence of fetal bovine serum (FBS). The same results in mRNA levels were seen using human cell lines HepG2, HeLa, and Chang liver cells. The increase of SE mRNA in HeLa cells grown in LPDS was preventable in a dose-dependent manner by feeding cells with 25-hydroxycholesterol or cholesterol. When an SE inhibitor, NB-598, was fed to HeLa cells grown in LPDS, it caused further increases in mRNA levels of SE, HMG-CoA reductase, and LDL receptor. In contrast, NB-598 had no effect on the message levels of these genes when fed to HeLa cells grown in FBS. These results suggest that sterol produced endogenously can also regulate SE expression at the level of transcription.

Anti-tumour-promoting glyceroglycolipids from the green alga, Chlorella vulgaris

Two new monogalactosyl diacylglycerols were isolated from the freshwater green alga, Chlorella vulgaris, as anti-tumour promoters, together with three monogalactosyl diacylglycerols and two digalactosyl diacylglycerols. The new monogalactosyl diacylglycerol containing (7Z,10Z)-hexadecadienoic acid showed a more potent inhibitory effect toward tumour promotion than the other glycerolipids isolated.

Different effects of isoproterenol and dihydroouabain on cardiac Ca2+ transients

Cytosolic fura-2 Ca2+ transient signals (TCa) and the left ventricular pressure or contraction of myocardium under the positive inotropic effects of the beta-adrenoceptor agonist, isoproterenol, and the cardiac glycoside, dihydroouabain, were measured simultaneously and the results were compared. TCa was observed preceding the onset of force development and showed a steeper rise and slower decay than did the contraction curve of papillary muscle. Isoproterenol increased the steepness and the amplitude of TCa, reflecting the speed and peak force of contraction, and clearly biphasic TCa were observed with biphasic contractions developed at low frequency. Ryanodine reduced not only the early component of the contraction but also TCa, without affecting the diastolic Ca2+ level. These effects of isoproterenol were attributed to the enhanced uptake of Ca2+ by the sarcoplasmic reticulum. In contrast, dihydroouabain elevated the Ca2+ level at diastole without any change in the amplitude of TCa, suggesting that dihydroouabain inhibits the membrane Na pump thereby increasing the intracellular Ca2+ via Na(+)-Ca2+ exchange. Furthermore, a comparison of the time course of the isometric twitch curve with that of TCa in rested state contraction indicated that there are distinct differences between the mechanisms of the positive inotropic effects of isoproterenol and of dihydroouabain.

Purification and characterization of recombinant squalene epoxidase

Recombinant rat squalene epoxidase (rSE) was expressed in E. coli and purified to an apparent homogeneity. This expression system was constructed using squalene epoxidase (SE) cDNA in which nucleotides coding 99 amino acids in the N-terminal were deleted and nucleotides coding hexa-histidine in the C-terminal were added. Purification was carried out using Ni-chelate affinity agarose and Cibacron Blue Sepharose column chromatography. Purification was achieved 100-fold over the crude E. coli extract with a yield of about 50%. The purified enzyme demonstrated a single band on SDS-polyacrylamide gel electrophoresis. The enzyme showed no distinct absorption spectrum in the visible regions. The properties of rSE were compared with those of rat liver microsomal SE. The requirement of the co-factors, the S105 fraction or Triton X-100, and NADPH-cytochrome c reductase, the pH dependency for enzyme activity, and the sensitivity to NB-598 seen with both enzymes suggest that rSE has properties very similar to rat microsomal SE. 2,3-Oxi-dosqualene (OSQ) and 2,3;22,23-dioxidosqualene (DOSQ) were formed by rSE in a completely reconstituted system. It is suggested that recombinant squalene epoxidase catalyzes the conversion of squalene to 2,3-oxidosqualene and of 2,3-oxidosqualene to 2,3;22,23-dioxidosqualene.

Novel antioxidants from roasted perilla seed

Novel antioxidants, 5-(3,4-dihydroxyphenylmethyl)oxazolidine-2,4-dione (1) and 3-(3,4-dihydroxyphenyl)lactamide (2), have been isolated from roasted perilla seed. Compound 1 was the first example of non-synthetic oxazolidinedione.

Tissue-specific suppression of aortic fatty-acid-binding protein in streptozotocin-induced diabetic rats

Fatty-acid-binding protein (FABP) expressed in rat aorta has been shown to be homologous to heart FABP (H-FABP) but its precise primary structure, cellular localization and function are not known. To establish the nucleotide identity between heart and aorta FABP, we performed an RNase protection assay with antisense RNA of rat H-FABP. The results demonstrate that the primary nucleotide sequence of aortic FABP is identical to that of rat H-FABP. In situ hybridization analysis revealed that aortic H-FABP mRNA is present in both smooth muscle cells and endothelial cells. In order to explore the function of aortic H-FABP, we examined whether a quantitative change in aortic H-FABP occurred in diabetes mellitus, since this pathological state has been shown to cause abnormalities in fatty acid metabolism. Northern blot analysis revealed that the level of aortic H-FABP mRNA was markedly decreased in rats made diabetic by streptozotocin treatment. The suppression of the mRNA level paralleled that of the protein level, as assessed by Western blot analysis. In distinct contrast, no major changes in the H-FABP mRNA level were observed in any other tissues examined, including heart, kidney and skeletal muscle, suggesting that this decrease is highly tissue-specific. The suppression of the aortic H-FABP in streptozotocin-diabetic rats was abolished by insulin supplementation. Taken together, these results suggest that the expression of the H-FABP gene in aorta may be specifically and dramatically suppressed in streptozotocin-diabetic rats, and that this suppression appears to be regulated by insulin.

Nucleotide sequence of a cDNA for mouse squalene epoxidase

A full-length cDNA encoding mouse squalene epoxidase was isolated by screening a mouse liver cDNA library with the rat squalene epoxidase gene as a probe. The cDNA had an open reading frame for a 572 amino acid polypeptide with a calculated molecular mass of 63.8 kDa. The predicted amino acid sequence of the mouse enzyme contained an FAD-binding motif, and was 93% identical to that of the rat enzyme. The former is one amino acid shorter than the latter. Blotting analyses showed that the mRNA is 2.8 kb in size and that a single copy of the gene is present in the mouse genome.

Molecular cloning and expression of rat squalene epoxidase

Squalene epoxidase (SE) (EC 1.14.99.7) catalyzes the first oxygenation step in sterol biosynthesis and is suggested to be one of the rate-limiting enzymes in this pathway. Rat SE cDNA was isolated by selecting yeast transformants expressing rat cDNA in the presence of transformants expressing rat cDNA in the presence of terbinafine, an inhibitor specific for fungal SE. The expression of rat SE in the isolated terbinafine-resistant clone was confirmed by its survival in the presence of either terbinafine or an inhibitor specific for mammalian SE, NB-598, but not in the presence of both terbinafine and NB-598. Rat SE polypeptide deduced from the nucleotide sequence contains 573 amino acids, and its molecular weight is 63,950 Da. The amino acid sequence reveals one potential transmembrane domain, a hydrophobic segment (Leu27 to Tyr43) in the NH2-terminal region. This region also contains a beta 1-alpha A-beta 2 motif, which is the consensus sequence for an FAD binding domain, suggesting that SE is a flavoenzyme. This deduced rat SE sequence is 30.2% identical to the ERG 1 gene, which encodes SE from an allylamine-resistant Saccharomyces cerevisiae mutant. Expression of a full-length rat SE protein in Escherichia coli confirms this polypeptide as a functional SE. This is the first report of the molecular cloning of mammalian SE.

Studies on chemical modification of monensin. V. Synthesis, sodium ion permeability, antibacterial activity, and crystal structure of 7-O-(4-substituted benzyl)monensins

7-O-(4-Substituted benzyl)monensins (3a-g) were synthesized from monensin (1), and their lipophilicity, antibacterial activity, and Na+ ion permeability were examined. 7-O-(4-Ethylbenzyl)monensin (3e) showed the largest Na+ ion permeability, but 3c,f,g showed smaller Na+ ion permeability than 7-O-benzylmonensin (2) in spite of higher lipophilicity. An X-ray study of the sodium salt of 3e revealed that the benzyl group was located over the position between the D and E rings, and that the ethyl substituent on the benzyl group was close to the C(28) methyl group on the E ring.

Direct measurement of increased myocardial cellular 23Na NMR signals in perfused guinea-pig heart induced by dihydroouabain and grayanotoxin-I

The effects of the cardiac glycoside dihydroouabain (DHO), and the ericaceous toxin grayanotoxin-I (GTX-I) on myocardial cellular sodium (Nai) concentrations were investigated using sodium-23 nuclear magnetic resonance (23Na NMR) spectroscopy at 30 degrees C in isolated perfused guinea-pig hearts. The Nai NMR signals from perfused Langendorff heart preparations were obtained by the modified inversion recovery (IR) method based on the previous observation that the spin-lattice relaxation time (T1) of the Nai (25 or 34 msec at 8.46 Tesla (T)) is much faster than that of extracellular sodium (64 msec at 9.4 T). Nai was estimated from the calibration curve of the frequency area of the 23Na NMR FT spectra plotted against the standard Na concentration. The Nai concentration of the heart increased concomitantly with the positive inotropic effects (PIE) of DHO, GTX-I and monensin (MON). The cumulative sequential addition of DHO (5 x 10(-6) M), GTX-I (7 x 10(-8) M) and MON (5 x 10(-6) M), each of which alone induced no appreciable PIE, produced a 22% elevation in Nai concentration relative to that of the control (100%) accompanying a PIE of 44%. The mechanism of this Nai elevation induced by combinational addition of DHO, GTX-I and MON may be mediated as follows: GTX-I increases the net Na-influx via Na+ channels; DHO inhibits the pumping out of Na+ from the cell; and MON transports external Na+ into the cell, acting as a sodium ionophore. Consequently, these drugs act synergistically to increase the Nai, thereby increasing the intracellular Ca2+ concentration via Na(+)-Ca2+. exchange.

Mechanism of an early lysis by fatty acids from axenic Phormidium tenue (musty odor-producing cyanobacterium) and its growth prolongation by bacteria

We have previously demonstrated that bacteria-containing Phormidium tenue, a cyanobacterium which produces musty odor 2-methylisoborneol, grew beyond 8 weeks, whereas axenic alga perished suddenly between the 3rd week and the 4th week while being cultured in the laboratory. This mechanism was investigated. It is assumed that when algal cells grow beyond a certain level, the supply of CO2 becomes inadequate and results in the rapid lysis of axenic alga. At that time, inhibitory substances liberated from algal cells kill the surviving alga. Since the process occurs continuously, this alga is finally annihilated. On the other hand, since inhibitory substances are metabolized or degraded by bacteria coexistent with alga, bacteria-containing P. tenue maintains growth for a long time. The growth-inhibitory substance was found to be unsaturated free fatty acids.

Molecular cloning of a cDNA encoding a novel fatty acid-binding protein from rat skin

A novel skin-type fatty acid-binding protein, termed cutaneous(C)-FABP, has been purified from rat skin and a cDNA clone for this protein has been identified. The purified protein had the ability to bind long chain fatty acids like other rat FABPs. The deduced amino acid sequence of the cDNA clone comprises residues yielding a molecular mass for the polypeptide of 15.1 kDa and exhibits around 50% identity to myelin P2 protein, adipocyte FABP and heart FABP. Our results propose that C-FABP is a new member of the FABP family.

Decomposition of the Modulated Waves in a Rotating Couette System

The time-dependent velocity field in a rotating Couette system has been decomposed. Successive instantaneous velocity profiles were obtained by an ultrasonic Doppler velocity profile method, and the spatiotemporal velocity field had been analyzed by two-dimensional Fourier transform. The Fourier spectrum is depicted by intrinsic peaks, and the velocity field cpan be reconstructed with these peak components only, indicating a successful decomposition of the velocity field. This method shows that the so-called broadband component, which is purely spatiotemporal and attributed to chaos, corresponds to a global motion of the wave propagating from roll to roll.

Positron emission tomography of auditory sensation in deaf patients and patients with cochlear implants

The present study investigated the function of the auditory cortices in severely hearing-impaired or deaf patients and cochlear implant patients before and after auditory stimulation. Positron emission computed tomography (PET), which can detect brain activity by providing quantitative measurements of the metabolic rates of oxygen and glucose, was used. In patients with residual hearing, the activity of the auditory cortex measured by PET was almost normal. Among the totally deaf patients, the longer the duration of deafness, the lower the brain activity in the auditory cortex measured by PET. Patients who had been deaf for a long period showed remarkably reduced metabolic rates in the auditory cortices. However, following implantation of the cochlear device, the metabolic activity returned to near-normal levels. These findings suggest that activation of the speech comprehension mechanism of the higher brain system can be initiated by sound signals from the implant devices.

Auto-growth inhibitory substance from the fresh-water cyanobacterium Phormidium tenue

An extract of the cyanobacterium P. tenue showed a significant inhibitory effect on its own growth. Bioassay-directed fractionation has led to the identification of the auto-growth inhibitory substance as a mixture of fatty acids. Unsaturated fatty acids such as linoleic and linolenic acids appear to be predominantly responsible for the auto-growth inhibitory effect.

Isolation and identification of anti-tumor-promoting principles from the fresh-water cyanobacterium Phormidium tenue

Bioassay-directed fractionation of the extract of the cyanobacterium P. tenue led to the isolation of the three classes of glycolipids, viz., monogalactosyl diacylglycerol (MGDG), digalactosyl diacylglycerol (DGDG), and sulfoquinovosyl diacylglycerol (SQDG) as anti-tumor-promoters. In comparing the anti-tumor-promoting effect of the three classes of glycolipids with various acyl residues, MGDG and DGDG inhibited tumor promotion more intensely than SQDG. With respect to MGDG and DGDG, the inhibitory activity of each glycolipid possessing a single pair of acyl residues was also investigated after HPLC separation. Among the 17 tested MGDGs (1a--h) and DGDGs (2a--i), three of the DGDGs (2a, b, e) showed more potent inhibitory activity toward tumor promotion than the others.

Cardiac glycoside-induced elevation of intracellular Na+ ion concentration in human erythrocytes studied by 23Na NMR spectroscopy: relationship between inotropy speed and elevation rate of intracellular Na+ ion concentration

Elevation of intracellular sodium ion concentration in human erythrocyte induced by the cardiac glycoside, proscillaridin, and its four derivatives was measured using 23Na NMR spectrometry. In this examination, there was a significant correlation between the time to half maximum inotropic effect and the time to maximum of Na+ concentrations in human erythrocyte, determined by 23Na NMR.

Structural analysis of oxidation products of urofuran acid by hypochlorous acid

The oxidation of urofuran acid derivatives (1-2) by hypochlorous acid (HOCl) was investigated with the goal to possibly simplify the detection of their metabolites in biological materials. The oxidation products of 3-carboxy-4-methyl-5-propyl-2-furanpropionic acid (1) were obtained as an isomeric mixture and confirmed to exist as cis (3a) and trans (3b) isomers, based on their 13C nuclear magnetic resonance (NMR) spectra. Similarly, the products of 5-H substituted acid 2 obtained by oxidation with HOCl were identified as 4a and 4b by 13C and 1H NMR which indicated the presence of cis and trans hemiacetal hydrogens at C-5 in a ratio of 2.11:1. The oxidation was found to proceed in a manner different from that of the F-acid, because of the presence of the electron withdrawing COOCH3 group at C-3 which favored the nucleophilic attack on the carbonyl group to afford cis- and trans-2,5-dihydroxy-2,5-dihydrofurans (3a-b, 4a-b).