Ketone bodies: A double-edged sword for mammalian life span

Accumulating evidence suggests health benefits of ketone bodies, and especially for longevity. However, the precise role of endogenous ketogenesis in mammalian life span, and the safety and efficacy of the long-term exogenous supplementation of ketone bodies remain unclear. In the present study, we show that a deficiency in endogenous ketogenesis, induced by whole-body Hmgcs2 deletion, shortens life span in mice, and that this is prevented by daily ketone body supplementation using a diet containing 1,3-butanediol, a precursor of β-hydroxybutyrate. Furthermore, feeding the 1,3-butanediol-containing diet from early in life increases midlife mortality in normal mice, but in aged mice it extends life span and prevents the high mortality associated with atherosclerosis in ApoE-deficient mice. By contrast, an ad libitum low-carbohydrate ketogenic diet markedly increases mortality. In conclusion, endogenous ketogenesis affects mammalian survival, and ketone body supplementation may represent a double-edged sword with respect to survival, depending on the method of administration and health status.

Ketone body 3-hydroxybutyrate enhances adipocyte function

Ketone bodies, including 3HBA, are endogenous products of fatty acid oxidation, and Hmgcs2 is the first rate-limiting enzyme of ketogenesis. From database analysis and in vivo and in vitro experiments, we found that adipose tissue and adipocytes express Hmgcs2, and that adipocytes produce and secrete 3HBA. Treatment with 3HBA enhanced the gene expression levels of the antioxidative stress factors, PPARγ, and lipogenic factors in adipose tissue in vivo and in adipocytes in vitro, accompanied by reduced ROS levels. Knockdown of endogenous Hmgcs2 in adipocytes markedly decreased 3HBA levels in adipocytes and decreased the gene expression levels of the antioxidative stress factors, PPARγ, and lipogenic factors with increased ROS levels. Conversely, overexpression of Hmgcs2 in adipocytes increased 3HBA secretion from adipocytes and enhanced the gene expression levels of the antioxidative stress factors, PPARγ, and lipogenic factors. These results demonstrate that 3HBA plays significant roles in enhancing the physiological function of adipocytes.

Protein O-GlcNAcylation Is Essential for the Maintenance of Renal Energy Homeostasis and Function via Lipolysis during Fasting and Diabetes

BACKGROUND

Energy metabolism in proximal tubular epithelial cells (PTECs) is unique, because ATP production largely depends on lipolysis in both the fed and fasting states. Furthermore, disruption of renal lipolysis is involved in the pathogenesis of diabetic tubulopathy. Emerging evidence suggests that protein O-GlcNAcylation, an intracellular nutrient-sensing system, may regulate a number of metabolic pathways according to changes in nutritional status. Although O-GlcNAcylation in PTECs has been demonstrated experimentally, its precise role in lipolysis in PTECs is unclear.

METHODS

To investigate the mechanism of renal lipolysis in PTECs-specifically, the role played by protein O-GlcNAcylation-we generated mice with PTECs deficient in O-GlcNAc transferase (Ogt). We analyzed their renal phenotypes during ad libitum feeding, after prolonged fasting, and after mice were fed a high-fat diet for 16 weeks to induce obesity and diabetes.

RESULTS

Although PTEC-specific Ogt-deficient mice lacked a marked renal phenotype during ad libitum feeding, after fasting 48 hours, they developed Fanconi syndrome-like abnormalities, PTEC apoptosis, and lower rates of renal lipolysis and ATP production. Proteomic analysis suggested that farnesoid X receptor-dependent upregulation of carboxylesterase-1 is involved in O-GlcNAcylation's regulation of lipolysis in fasted PTECs. PTEC-specific Ogt-deficient mice with diabetes induced by a high-fat diet developed severe tubular cell damage and enhanced lipotoxicity.

CONCLUSIONS

Protein O-GlcNAcylation is essential for renal lipolysis during prolonged fasting and offers PTECs significant protection against lipotoxicity in diabetes.

Phase II study of irinotecan, leucovorin, 5-fluorouracil and tegafur/uracil for metastatic colorectal cancer

Irinotecan combined with continuous-infusion 5-fluorouracil (5FU) has been shown to be an effective and tolerable regimen in the treatment of metastatic colorectal cancer (MCRC). Tegafur/uracil (UFT) during 5FU infusion enhances plasma 5FU concentration, mimics continuous 5FU infusion and delivers the drug to target tumor cells. We conducted a phase II trial of four-agent combined therapy for MCRC, giving patients (pts) intravenous irinotecan (30 mg/m2 on day 1), leucovorin (LV, 200 mg/m2 on day 1 and 2), 5FU (300 mg/m2 on day 1 and 2), and UFT (400 mg/day for 14 days). The main endpoint was the objective tumor response rate. Sixteen pts with a good performance status were enrolled from February 2001 to May 2002. The response rate was 19% (3 partial responses), and 13 pts had stable disease. The median time to progression was 5.2 months, and the median survival time was 20.2 months. Considering the low toxicity and reasonable cost, this regimen deserves further investigation.

Tea catechins prevent the development of atherosclerosis in apoprotein E-deficient mice

Green tea contains various antioxidative flavan-3ols (tea catechins), such as (-)-epigallocatechin gallate (EGCg, the major catechin), which exert potent inhibitory effects on LDL oxidation in vitro and ex vivo in humans. In this study, the antiatherogenic effects of tea catechins were examined in atherosclerosis-susceptible C57BL/6J, apoprotein (apo)E-deficient mice. Male apoE-deficient mice (10 wk old) were fed an atherogenic diet for 14 wk; during that time, one group (tea) was supplied drinking water supplemented with green tea extract (0.8 g/L), and another group (control) was offered the vehicle only. The tea extract consisted of the following (g/100 g): EGCg, 58.4; (-)-epigallocatechin (EGC), 11.7; (-)-epicatechin (EC), 6.6; (-)-gallocatechingallate (GCg), 1.6; (-)-epicatechin gallate (ECg), 0.5; and caffeine, 0.4. The estimated actual intake of tea catechin was 1.7 mg/(d. mouse). Tea ingestion did not influence plasma cholesterol or triglyceride concentrations. Plasma lipid peroxides were reduced in the tea group at wk 8, suggesting that the in vivo oxidative state is improved by tea ingestion. Atheromatous areas in the aorta from the arch to the femoral bifurcation and aortic weights were both significantly attenuated by 23% in the tea group compared with the control group. Aortic cholesterol and triglyceride contents were 27 and 50% lower, respectively, in the tea group than in the control group. These results suggest that chronic ingestion of tea extract prevents the development of atherosclerosis without changing the plasma lipid level in apoE-deficient mice, probably through the potent antioxidative activity of the tea.

[Role of national insurance pharmacies in community complete home care networks--home TPN and home care supported by local national insurance pharmacies]

The reforms in the medical system and introduction of home care insurance have brought great changes to national health insurance pharmacies. In April 1998, Dr. Hirai became new director of the Chiba Togane Hospital. The development of a community complete medical system was included in a restructuring of the hospital, and various reforms were begun. A system covering all aspects of the medical/pharmaceutical field was started in August 1998. For its part, the Sanbu-gun Pharmacists Association began accepting prescriptions outside the hospital, and regular meetings for the exchange of knowledge were held with members of the physicians and pharmacists associations. After building a relationship of trust in this way, a community complete home treatment system was begun in July 1999 with Togane Hospital functioning as its backup support hospital. To date, home TPN terminal care has been provided in cases of terminal cancer, incurable neurological diseases, and for the very aged and patients with cerebrovascular impairments. Any general pharmacy in the region can participate in the program to fill prescriptions for TPN, provided that the pharmacist him or herself so wishes, establishes a clean bench at the pharmacy, and undergoes training at Togane Hospital on the preparation of i.v. medicines in order to function responsibly in this capacity. These pharmacies are called satellite pharmacies, and at present there are four of them located with a good balance within the region. These satellite pharmacies prepare liquid medications for TPN, including narcotics, and oral medicines following the prescriptions written by the physician from the hospital who is serving as the primary home treatment physician. The pharmacy also delivers the medicines to the home of the patient. The pharmacist checks the status of remaining TPN liquids and oral medicines and informs the primary home physician and support hospital by e-mail or fax, so that everyone shares the same information. The success or failure of home TPN from a general pharmacy depends on the formation of a digital network in order to share information using the Internet and a back-up system for unconditional support by the support hospital in times of patient emergency. In our region, these conditions have been fulfilled.

Differential interaction of tubulin isotypes with the antimitotic compound IKP-104

The tubulin molecule is a heterodimer composed of two polypeptide chains, designated alpha and beta; both alpha and beta exist in numerous isotypic forms, which differ in their assembly and drug binding properties. 2-(4-Fluorophenyl)-1-(2-chloro-3, 5-dimethoxyphenyl)-3-methyl-6-phenyl-4(1H)-pyridinone (IKP-104) is an antimitotic compound which inhibits polymerization and induces depolymerization of microtubules [Mizuhashi, F., et al. (1992) Jpn. J. Cancer Res. 83, 211]. Since the previous work was undertaken with isotypically unfractionated tubulin, we have investigated the interactions of IKP-104 with the isotypically purified tubulin dimers (alpha beta(II), alpha beta(III), and alpha beta(IV)). We find that IKP-104 binds to alpha beta(II) and alpha beta(III) at two classes of binding sites. However, affinities for each class of site are much weaker for alpha beta(III) than for alpha beta(II). Interestingly, the low-affinity site on alpha beta(IV) was not detectable. Its high-affinity site was weaker than those of either alpha beta(II) or alpha beta(III). In a pattern consistent with these results, IKP-104 inhibited assembly better with alpha beta(II) than with the other two dimers. Higher concentrations of IKP-104 induced formation of spiral aggregates from alpha beta(II) and alpha beta(III) but not from alpha beta(IV). Our results suggest that the interaction of IKP-104 with tubulin isotypes is very complex: alpha beta(II) and alpha beta(III) differ quantitatively in their interaction with IKP-104, and alpha beta(IV)'s interaction differs both quantitatively and qualitatively from those of the other two dimers.

Green tea polyphenols (flavan 3-ols) prevent oxidative modification of low density lipoproteins: an ex vivo study in humans

Oxidation of low density lipoprotein (LDL) plays crucial roles in atherogenesis. We previously reported that green tea polyphenols (flavan 3-ols), especially epigallocatechingallate (EGCg) and epicatechingallate, exerted potent inhibitory effects on LDL oxidation in vitro. To examine whether intake of green tea polyphenols renders LDL resistant to ex vivo oxidation in humans, 22 male volunteers aged between 22 and 32 years were recruited and assigned the same dietary regimen for 2 weeks. After a 1-week baseline period, they were equally divided into two groups: control and tea. The tea group ingested 300 mg of green tea polyphenol extract twice daily for 1 week. Plasma EGCg concentration at the end of the experiment was 56 nmol/L on average (56% in free form) in the tea group; no EGCg was detected before the experiment. Plasma concentrations of lipids, ascorbate, alpha-tocopherol, and lipid peroxides did not change before and after the experiment in either group, but beta-carotene was higher in the tea group (P< 0.01 by paired Student'st-test). LDL (0.1 mg/mL) was incubated with 5 microM Cu(2+) and the oxidation was measured by absorbance at 234 nm. The lag time was significantly prolonged by 13.7 min in the tea group (P < 0.05 by paired Student'st-test, before versus after), whereas such a change was not observed in the control group. These results suggest that daily consumption of seven to eight cups (approximately 100 mL each cup) of green tea may increase resistance of LDL to in vivo oxidation, leading to reduction in the risk of cardiovascular diseases.

Lewy body-type degeneration in cardiac plexus in Parkinson's and incidental Lewy body diseases

Heart tissues of patients with PD or incidental Lewy body (LB) disease (ILBD) were examined by light and electron microscopy. LBs and alpha-synuclein-positive neurites were identified in the hearts from 9 of 11 patients with PD and from 7 of 7 patients with ILBD. LBs were present in both tyrosine hydroxylase-positive and -negative nerve processes, which are nerves of extrinsic sympathetic and intrinsic origin, respectively. These findings provide histologic evidence that the postganglionic sympathetic and intrinsic neurons in the heart are involved in the PD disease process.

Effects of phosphatidylcholine/phosphatidylethanolamine composition in cholesteryl ester-micellar substrates on neutral cholesterol esterase activity

The effect of phospholipid composition in cholesteryl ester (CE)-micellar substrates on neutral cholesterol esterase (N-CEase) activity was examined. N-CEase preparation was incubated with micelles composed of cholesteryl-[1-14C]-oleate, sodium taurocholate, and phosphatidylcholine (PC)/phosphatidylethanolamine (PE) at varying ratios (%PE:0 = PC only, 17, 33, 50, 66, 83). The activity increased dependently with the increase in PE content; the activity with the micelles containing the highest ratio of PE was 2.5-fold compared with the micelles consisting of PC only. Vmax with the micelles of 83, 66, and 50% PE was 3.1-, 2.7-, and 1.9-fold, respectively, compared with the micelles of PC only. Each micellar preparation was chromatographed through a Superose 6 column by the FPLC system. In 66 and 83% PE-containing micelles, PC, PE, CE, and part of sodium taurocholate eluted completely together in a single peak, whereas in micelles with 33 and 50% PE they eluted loosely together. The micelles with PC only or 17% PE formed PC-micelles without including CE and PE. It is concluded that PE plays a critical role in the formation of CE micelles with PC, and in the interaction with N-CEase. The CE-micelles with 66-83% PE serve as substrates for sensitive and reproducible N-CEase assay.

Loss of 123I-MIBG uptake by the heart in Parkinson's disease: assessment of cardiac sympathetic denervation and diagnostic value

Myocardial imaging with 123I-metaiodobenzylguanidine (MIBG) was performed on 35 patients with Parkinson's disease and 24 control subjects to evaluate cardiac sympathetic function in patients with Parkinson's disease, verify this phenomenon and examine whether myocardial MIBG uptake and clearance are correlated with the clinical severity of Parkinson's disease.

METHODS

We studied 35 patients with Parkinson's disease and 24 control subjects with other central nervous system diseases. The latter group consisted of 12 subjects with other neurodegenerative disorders (4 with spinocerebellar degeneration, 2 with amyotrophic lateral sclerosis, 3 with progressive supranuclear palsy and 3 with corticobasal degeneration and 12 patients with cerebral infarction (CI), 6 with vascular parkinsonism and 6 without it. Early and delayed images of the anterior view were obtained 15 min and 4 h after injection of 123I-MIBG, respectively. MIBG uptake was quantified by calculating a heart-to-mediastinum count (H/M) ratio.

RESULTS

The H/M ratio was markedly reduced in the patients with Parkinson's disease (II to V on the Hoehn and Yahr scale) compared with the control subjects. None of the subjects with neurodegenerative diseases showed a marked decrease in myocardial MIBG uptake nor did any subject with CI.

CONCLUSION

Our findings indicate that, in Parkinson's disease, a reduction in myocardial MIBG uptake is a very common, specific phenomenon that can be used to detect cardiac autonomic dysfunction to diagnose Parkinson's disease, particularly in patients without typical signs and symptoms.

Increases in 4-hydroxynonenal and hexanal in bone marrow of rats subjected to total body X-ray irradiation: association with antioxidant vitamins

Radiation-induced lipid peroxidation and its association with antioxidant vitamins in the bone marrow (BM), of rats subjected to total body irradiation (TBI) of X-rays at a dose of 3 Gy was investigated. The concentration of vitamin C in the BM decreased at 4 h, and reached about 2% of the control level at 24 h after irradiation. The concentration of vitamin E in the BM also decreased to 43% at 24 h. Corresponding to the decrease in vitamin E concentration, the concentration of 4-hydroxynonenal (HNE) in the BM increased 2.5-fold at 24 h. Similarly, increases in the concentrations of hexanal and thiobarbituric acid-reactive substances (TBA-RS) were detected in the BM. In the plasma, these parameters of lipid peroxidation were unchanged up to 48 h, but were increased at 96 h after irradiation. Four days of vitamin E administration to rats (p.o. 460 mg/kg body weight) prior to the 3 Gy X-irradiation increased the vitamin E concentration in the BM to 1.3-fold the control level, but did not attenuate the increases in HNE and hexanal in the BM. The slight accumulation of vitamin E in the BM as a result of the vitamin E treatment may be partly related to this lack of vitamin E effect.

IKP104-induced decay of tubulin: role of the A-ring binding site of colchicine

Tubulin, the major subunit protein of microtubules, has a tendency to lose its ability to assemble or to interact with ligands in a time-dependent process known as decay. Decay involves the increase in exposure of sulfhydryl groups and hydrophobic areas. The antimitotic drug IKP104 [2-(4-fluorophenyl)-1-(2-chloro-3, 5-dimethoxyphenyl)-3-methyl-6-phenyl-4(1H)-pyridinone] accelerates the decay of tubulin [Ludueña et al. (1995) Biochemistry 34, 15751-15759]. In the presence of colchicine, however, IKP104 stabilizes tubulin against decay. We have shown that the stability and the acceleration of the decay of tubulin are mediated respectively by the high- and low-affinity binding site(s) of IKP104 [Chaudhuri et al. (1998) J. Protein Chem. 17, 303-309]. To better understand the mechanism by which colchicine protects tubulin from IKP104-induced decay, we examined the effect of colchicine and its analogues on this process. We found that IKP104 unfolds tubulin in a process involving a specific domain where colchicine interacts, although the binding sites of these two drugs are distinctly different. 2-Methoxy-5-(2',3',4'-trimethoxyphenyl) tropolone (MTPT), the bicyclic analogue of colchicine that lacks the B-ring, can also protect tubulin from IKP104-induced decay. An A-ring analogue of colchicine, 3,4,5-trimethoxybenzaldehyde (TMB), can also stop IKP104-induced unfolding of tubulin significantly. Interestingly, the C-ring analogue of colchicine, tropolone methyl ether (TME), does not prevent this process. Our results thus suggest that neither the B-ring nor the C-ring binding regions of colchicine are involved in the IKP104-induced decay and that the A-ring binding site of colchicine on tubulin plays a crucial role in IKP104-induced decay.

Distinct and overlapping binding sites for IKP104 and vinblastine on tubulin

IKP104 is one of a group of tubulin-binding drugs whose interaction with tubulin suggests that it may bind to the protein at or close to the region where vinblastine binds. By itself IKP104 is a potent enhancer of tubulin decay as evidenced by the fact that it induces the exposure of the sulfhydryl groups and hydrophobic areas on tubulin. In this respect, IKP104 differs from vinblastine and other drugs such as phomopsin A, dolastatin 10, rhizoxin, and maytansine which are competitive or noncompetitive inhibitors of vinblastine binding. In contrast, however, in the presence of colchicine, IKP104 behaves differently and strongly stabilizes tubulin, to an extent much greater than does colchicine alone. IKP104 appears to have two classes of binding site on tubulin, differing in affinity; the acceleration of decay appears to be mediated by the low-affinity site (Chaudhuri et al., 1998, J. Protein Chem., in press). We investigated the relationship of the binding of IKP104 and vinblastine. We found that the high-affinity site or sites of IKP104 overlap with or interact with the vinblastine-binding sites, but that the low-affinity site is distinctly different.

[Studies on antioxidant effects of Hypsizigus marmoreus. II. Effects of Hypsizigus marmoreus for antioxidant activities of tumor-bearing mice]

The in vivo effect of Hypsizigus marmoreus on the plasma antioxidant status of tumor-bearing mice was examined. Female DBA/2 mice treated with subcutaneous injection of 3-methylcholanthrene were fed on a basal diet (CE-2) or CE-2 containing 5% fruit bodies of the mushroom for 76 weeks. Antioxidant activities (AOA) of mice with tumor were significantly higher than those of mice without tumor. The high levels of AOA were attributable to the increase of high molecular weight AOA in the plasma. A similar increase in plasma AOA was also observed in sarcoma-180 solid tumor-bearing mice. The mushroom feeding exhibited a potent antitumor effect and caused a significant decrease in lipid peroxide levels (as thiobarbituric acid reactive substances; TBARS). These results suggest that the increase of AOA in the plasma of tumor-bearing mice is one of the mechanism of cancer preventive effects and also suggest that Hypsizigus marmoreus might play a role in decreasing TBARS by controlling AOA induction.

Podophyllotoxin and nocodazole counter the effect of IKP104 on tubulin decay

Tubulin, the subunit protein of microtubules, undergoes a time-dependent loss of functional properties known as decay. We have previously shown that the drug 2-(4-fluorophenyl)- -(2-chloro-3,5-dimethoxyphenyl)-3-methyl-6-phenyl-4(1H)-pyridinone (IKP104) accelerates decay, but that in the presence of colchicine, IKP104 becomes a stabilizer of tubulin. To see if this is due to conformational effects specific to colchicine or simply to occupancy at the colchicine site, we examined the effects of nocodazole and podophyllotoxin, two well-known competitive inhibitors of colchicine for binding to tubulin, on IKP104's acceleration of decay. We found that podophyllotoxin abolished IKP104's accelerating effect and, like colchicine, turned it into a stabilizer of tubulin. Nocodazole's effects were similar to those of podophyllotoxin and colchicine, in that it abolished IKP104-induced enhancement of decay; however, in the presence of nocodazole, IKP104 caused little or no stabilization of tubulin. Since colchicine, nocodazole, and podophyllotoxin have very different interactions with tubulin, but all inhibit the IKP104-induced enhancement of decay, our findings suggest that this inhibition arises from occupancy of the colchicine site rather than from a direct conformational effect of these two drugs.

[Intra-arterial preventive chemotherapy for residual liver after resection of hepatic metastasis from colorectal cancer]

We treated 18 cases with intra-hepatic arterial infusion chemotherapy after resection of hepatic metastasis from colorectal cancer (June 1991-September 1997). Eight cases were H1, 7 were H2, and 3 were H3. Hepatic lobectomy was done in 3 cases, lobectomy + partial resection in 2 cases, and partial resection in 13 cases. All cases received high-dose intermittent 5-FU infusion (WHF = 5-FU 1,000 mg/m2/5 hrs/w) on an outpatient basis. The total frequency of WHF was 4-54 times (average 29), and total 5-FU doses ranged from 6.0 to 81.0 g (average 40 g). The 1- and 5-year cumulative survival rates were 100% and 77.5% in all patients 100% and 87.5% in H1 group and 100% and 64.3% in H2 + H3 group, respectively. There was no significant difference of survival between the H1 and H1 + H3 groups. The 1- and 5-year recurrence rates in residual liver were 5.9% and 14.4%, respectively. One of 2 cases with residual liver recurrence was resected for metastasis again, and the patient is now in a disease-free state. WHF after resection of hepatic metastasis from colorectal cancer has a preventive effect for their survival, not only in H1 group but also in H2 + H3 group.

Tubulin stability and decay: mediation by two distinct classes of IKP104-binding sites

IKP104, a novel antimitotic drug, has two classes of binding sites on bovine brain tubulin with different affinities. IKP104, by itself, enhances the decay of tubulin, but in the presence of colchicine or podophyllotoxin, it stabilizes tubulin instead of opening up the hydrophobic areas [Luduena et al. (1995), Biochemistry 34, 15751-15759]. Here, we have dissected these two apparently contradictory effects of IKP104 by cleaving the C-terminal ends of both alpha and beta subunits of tubulin with subtilisin. We have found that the selective removal of the C-terminal ends from both the alpha and beta subunits of alphabeta tubulin lowers the sulfhydryl titer by approximately 1.5 mol/mol of dimer. Interestingly, IKP104 does not increase either the sulfhydryl titer or the exposure of hydrophobic areas of this subtilisin-treated tubulin (alpha(s)beta(s)). Moreover, IKP104 lowers the sulfhydryl titer of alpha(s)beta(s) tubulin approximately by 1 mol/mol and appears to inhibit completely the time-dependent decay of alpha(s)beta(s) tubulin. The cleavage at the C-terminal ends of both alpha and beta modulates the effect of IKP104 on the beta subunit, but not on the alpha subunit. Fluorometric binding data analysis suggests that IKP104 binds to the alpha(s)beta(s) tubulin only at the high-affinity site; the low-affinity site(s) disappear almost completely. The sulfhydryl titer data for alpha and beta and the fluorometric data therefore suggest that the interaction of IKP104 at the high-affinity site on tubulin is not regulated by the C-terminal domains of alpha and beta and the effect of the high-affinity site is restricted largely to the alpha subunit, while the low-affinity-site binding is modulated by the C-terminal domain of beta. It also appears that the stabilization and the acceleration of the decay of tubulin are mediated by distinct interactions of IKP104 with its high- and low-affinity sites on tubulin, respectively.

Modification of enzyme sulfhydryl groups suppresses UV-induced mutagenesis depending on the nucleotide excision repair system in Escherichia coli B/r WP2

S-Methyl methanethiosulfonate (MMTS), which was isolated from cauliflower (Brassica oleracea var. botrytis) homogenate as a potent bio-antimutagen, has been used as an enzyme-sulfhydryl (SH) temporary blocking agent in modification studies of enzyme activities. We examined whether 23 kinds of MMTS-related compounds have a suppressing effect on UV mutagenesis in Escherichia coli B/r WP2. Disulfide derivatives of diphenyl, 2.2'-dipyridine and 4.4'-dipyridine, and N-ethyl maleimide (NEM), which temporarily or tightly block sulfhydryl (SH)-groups, showed similar suppressing effect in E. coli B/r WP2, but not in WP2s hcr- (uvrA-) in the range of nanomolar/plate as MMTS previously did. Cystamine sulfate, methyl methylsulfinylmethyl sulfide and S-methyl-L-cysteinesulfoxide moderately suppressed, and diallyl disulfide and glutathione (oxidized form) weakly suppressed UV mutagenesis in E. coli B/r WP2 in the range of micromolar/plate. MMTS and phorone, a glutathione (GSH)-depleting agent, lowered the intracellular GSH level in E. coli B/r WP2, but phorone did not inhibit UV-induced mutation. These results indicate that the target for SH-modification is enzyme-SHs but not GSH, and that the direct or indirect modification of enzyme-activity by SH-blocking might be involved in the antimutagenesis through a pathway associated with the DNA-excision repair system.

Active oxygens generation by flavonoids

The hydrogen peroxide (H2O2)-generating effects of 14 flavonoids were investigated. Seven out of 14 flavonoids tested were found to generate H2O2 in an acetate buffer of pH 7.4. The H2O2-generating abilities of flavonoids decrease in the order of myricetin > baicalein > quercetin > (-)-epicatechin > (+)-catechin > fisetin = 7,8-dihydroxy flavone. This ability was observed in flavonoids with either a pyrogallol or catechol structure, and the pyrogallol-type flavonoids generated more H2O2 than the catechol-types. The amount of H2O2 generated by myricetin (pyrogallol-type flavonoid) was proportional to its concentration and to the reaction time until about 4 h. In addition, H2O2 generation by myricetin was dependent on the amount of dissolved oxygen in the buffer, and it was inhibited by the addition of superoxide dismutase. These results suggest that the flavonoids generate H2O2 by donating a hydrogen from their pyrogallol or catechol structure to oxygen, through a superoxide anion radical. It was also found that flavonoids which generated more H2O2 were more powerful antioxidants in the NADPH-dependent lipid peroxidation of rat microsomes.

Response differences among mouse strains in DNA damage and skin carcinogenicity of 7,12-dimethylbenz[a]anthracene are due to inducible aryl hydrocarbon hydroxylase activity

Strain differences of mice in the induction of DNA damage in peripheral blood cells and skin tumors were investigated using 7,12-dimethylbenz[a]anthracene (DMBA). DMBA-induced DNA damage and skin tumorigenesis were evaluated using the single cell gel electrophoresis (SCGE) assay and 2-stage carcinogenicity study, respectively. DNA damaged cells were markedly increased in the aryl hydrocarbon hydroxylase (AHH)-inducible mice, BALB/c and C57BL/6, as compared with the AHH-noninducible mice, DBA/2, in the SCGE assay. The AHH-inducible mice were more sensitive to DMBA than the AHH-noninducible mice in the 2-stage carcinogenicity study. These results strongly suggest that the genetic capacity to metabolize PAH is associated with the mutagenicity and carcinogenicity of DMBA.

Orthotopic transplantation of a partial hepatic autograft in dogs

The purpose of this study was to investigate the availability of an orthotopic transplantation of partial hepatic autograft in dogs as a means of surgical training. Male mongrel dogs weighting 10-15 kg were used. The left lobe of the liver was harvested while preserving the left branches of the portal vein, hepatic artery and bile duct, and the left hepatic vein. The remnant liver was removed while preserving the inferior vena cava using a veno-venous bypass. Orthotopic transplantation of the autograft was performed while anastomosing the left hepatic vein to the inferior vena cava, portal and arterial reconstruction, and external biliary drainage. Thirteen out of 29 dogs survived more than 48 h after transplantation. However, 6 out of 13 dogs were sacrificed after developing bile peritonitis due to a dislodgement of the biliary catheter, and only two dogs were able to survive for 7 days after transplantation. The arterial ketone body ratio recovered to 1.0 within 1 h after reperfusion, and the ratio of the dogs that survived for more than 48 h remained above 1.0 until sacrifice. Orthotopic transplantation of a partial hepatic autograft is a useful and simple procedure to train surgeons for partial liver transplantation.

Cholesterol-mediated changes of neutral cholesterol esterase activity in macrophages. Mechanism for mobilization of cholesteryl esters in lipid droplets by HDL

Cholesteryl esters (CE) in lipid droplets undergo a continual cycle of hydrolysis and reesterification by neutral cholesterol esterase (N-CEase) and acyl CoA:cholesterol acyltransferase (ACAT), respectively. The mechanism by which HDL mobilizes CE from lipid droplets in J774 A.1 cells was investigated, focusing on N-CEase activity. We asked whether HDL enhances the activity and, if so, what signals induce the change of the activity. An incubation of cells with HDL enhanced the decline of cholesteryl-[l-14C]-oleate in foam cells and increased N-CEase activity in the supernatant of cell homogenate in a concentration-dependent manner, whereas incubation with LDL decreased the activity. In addition, N-CEase activity was fivefold higher when cells were cultured in 10% lipoprotein-deficient serum (LPDS) medium (2 micrograms cholesterol/mL) than when cultured in 10% fetal calf serum medium (31 micrograms cholesterol/mL), suggesting that changes in N-CEase activity are mediated by cholesterol. An addition of cholesterol (0 to 30 micrograms/mL) in LPDS medium markedly inhibited N-CEase activity with a concomitant increase in cellular cholesterol concentration. This inhibitory effect of cholesterol was also observed in mouse peritoneal macrophages. In vitro addition of cholesterol did not affect N-CEase activity. Treatment of cells with HMG-CoA reductase inhibitors enhanced N-CEase activity, whereas ACAT inhibitor decreased the activity. Northern blot analysis of N-CEase mRNA showed that the expression was not altered by the presence of cholesterol in LPDS medium. These results suggest that cholesterol downregulates N-CEase activity, probably through cholesterol-dependent appearance of some factors.

Antiatherogenic effects of a novel lipoprotein lipase-enhancing agent in cholesterol-fed New Zealand white rabbits

Following our report that administration of 4-diethoxyphosphorylmethyl-N-(4-bromo-2-cyanophenyl) benzamide (NO-1886) to rats elevated postheparin lipoprotein lipase (LPL) activity through an increase in the enzyme mass, we now investigate antiatherogenic effects of NO-1886 in cholesterol-fed New Zealand White rabbits. For 20 weeks, four groups of male rabbits received regular rabbit chow (the normal control), 0.25% cholesterol-containing chow (the control), and cholesterol chow supplemented with 0.5% and 1.0% NO-1886, respectively. Postheparin LPL activity at week 10 was raised by 30% in 0.5% of the NO-1886 group and 40% in 1.0% of the NO-1886 group compared with those in the control. The area under the curve of plasma cholesterol level was not different in three cholesterol-fed groups whereas the area under the curve of HDL cholesterol was approximately twofold greater in the two NO-1886 groups than in the control, and the area under the curve of plasma triglyceride was reduced to the level of the normal control. LPL activity was correlated with HDL cholesterol (r = .764, n = 18) and triglyceride (r = -.627, n = 18). Relative atheromatous area, aortic cholesterol, and triglyceride contents were reduced to approximately 25%, 60%, and 55%, respectively, of the control values by NO-1886 ingestion. Multiple regression analysis of LPL, HDL cholesterol, and triglyceride indicated that HDL cholesterol was the most powerful protector against aortic cholesterol accumulation, and triglyceride was the one to protect against the atheromatous area. We concluded that NO-1886 prevented the development of atherosclerosis through increasing LPL activity with a consequent increase in HDL cholesterol and a decrease in triglyceride without a significant influence of plasma cholesterol level.

Suppressing effects of S-methyl methanethiosulfonate and diphenyl disulfide on mitomycin C-induced somatic mutation and recombination in Drosophila melanogaster and micronuclei in mice

S-Methyl methanethiosulfonate (MMTS) and diphenyl disulfide (DPDS) are temporary enzyme-sulfhydryl blocking agents. They are naturally occurring phytoalexin-like and synthetic substances known to be very potent bio-antimutagens in Escherichia coli B/r WP2. In the present paper, the suppressing effects of MMTS on mitomycin C (MMC)-induced mutant wing spots in the somatic mutation and recombination test (SMART) of Drosophila melanogaster, and of MMTS and DPDS on MMC-induced micronucleated peripheral reticulocytes are described. MMTS consistently reduced the numbers of MMC-induced small single, large single and twin spots per wing at a dose of 10-1000 micrograms/vial, in a dose-dependent manner. MMTS reduced the number of twin spots per wing on the spontaneous mutation at the dose of 1000 micrograms/vial. MMTS and DPDS dose-dependently reduced the frequencies of MMC-induced micronucleated peripheral reticulocytes at a dose of 10-40, and 3-100 micrograms/kg, respectively. Our results confirmed that enzyme-sulfhydryl blocking agents, such as MMTS and DPDS, are effective antimutagens in vivo too.

[Evaluation of intra-arterial infusion chemotherapy for liver metastasis from gastric cancer]

We evaluated the result of intra-arterial infusion chemotherapy on liver metastasis from gastric cancer. Of 92 cases of metastatic liver tumor, 17 cases received intra-arterial infusion chemotherapy after primary resection. For comparison, we assigned the 17 cases to two groups according to the infused agents. One group was treated with the combination therapy of 5-FU, epirubicin and MMC (FEM group: n = 7), and another with other antineoplastic agents (non-FEM group: n = 10). In the FEM group, the response rate, 1-year survival rate and 50% survival period were 33.3%, 51.4%, 430 days, respectively, while those of the non-FEM group were 10.0%, 10.0%. 147 days. Although there was no significant difference (p = 0.0951), improvements in survival rate and survival period were observed. This implies the possibility that intra-arterial infusion chemotherapy, especially the combination therapy of FEM, is an effective treatment for liver metastasis from gastric cancer.

[Complication due to arterial infusion chemotherapy for liver metastasis from colorectal cancer]

OBJECTIVES

Arterial infusion chemotherapy is considered to be an extremely effective treatment for liver metastasis from colorectal cancer in terms of its tumor reduction and preventing recurrence in residual liver after resection. However, there still remain some unclear points as to the influence on hepatic artery and bile duct when this treatment is used over the long term. We report some conclusions obtained by examining cases of hepatic arterial occlusion (stenosis) and biliary complication who received this treatment.

MATERIALS AND METHODS

Thirty-six cases who received this treatment over 3 months were the objects of this study, with the aim of direct effect against metastatic focus (21 cases) and prevention of recurrence in residual liver (15 cases). The ages were from 27 to 81; 22 cases were male and 14 were female. Indwelling routes of catheter were gastroduodenal artery (GDA) in 28 cases and femoral artery (FA) in 8 cases. Intermittent high-dose infusion (WHF: 5-FU 1,000 mg/m2/5 hrs qw) was adopted as the method.

RESULTS

Hepatic arterial occlusion or stenosis was observed in 12 cases (GDA: 10; FA: 2). There seemed to be no correlation with the total dosage of 5-FU or the number of administrations. Even when hepatic arterial occlusion or stenosis occurred, no change was observed in liver function, and there no death was caused by this. However, CT showed a low-density area followed by atrophy in the right lobe in one case with right hepatic arterial stenosis, despite normal portal blood flow. Of the 6 cases which developed obstructive jaundice, 4 were due to the increase of metastatic focus or lymph nodes, and 1 case without dilatation of bile duct died from suspected sclerosing cholangitis. In this case, ALP had been increasing since 1 month before the onset of jaundice. Another case which developed biloma accompanied by the increase of serum bilirubin improved by discontinuance of chemotherapy.

CONCLUSION

Since arterial infusion chemotherapy for liver metastasis from colorectal cancer causes hepatic arterial occlusion (stenosis) at a high rate, early detection of abnormalities by liver function test and imaging diagnosis which leads to early treatment is important.

[Studies on antioxidant effect of Hypsizigus marmoreus. I. Effects of Hypsizigus marmoreus for antioxidant activities of mice plasma]

The antioxidant effects of Hypsizigus marmoreus, one of the most popular Japanese edible mushrooms, were investigated by the use of the augmentation effect of antioxidant activity (AOA) in the mice plasma. An aqueous extract of the mushroom fruit-body was found to have a slight trap activity for peroxyl and alkoxyl radicals. On the other hand, the blood plasma of mice fed with a fodder containing 5-10% of the dried powder of the mushroom extract augmented significantly AOA for alkoxyl radicals. It was suggested from analysis of the plasma by the HPLC post column AOA method that the increase of AOA in the mice plasma was caused by the induction of high molecular weight fractions having AOA produced by feeding Hypsizigus marmoreus. The amount of lipoperoxide in the mice plasma as values of thiobarbituric acid reactive substances showed a tendency to be lowered by intake of Hypsizigus marmoreus. These results suggest that oral administration of the fruit-body of Hypsizigus marmoreus can induce an antioxidant effect in the mice plasma.

A comparative study of medetomidine-butorphanol-ketamine and medetomidine-ketamine anaesthesia in dogs

The anaesthetic and cardiopulmonary effects of medetomidine (20 micrograms/kg)-butorphanol (0.1 mg/kg)-ketamine (MBK) (2.5, 5.0, 7.5 mg/kg) and medetomidine (40 micrograms/kg)-ketamine (5.0 mg/kg) (MK) were compared in dogs. The induction time (time from the initial injection of the sedative to lateral recumbency) by medetomidine-butorphanol (6.0 +/- 2.3 min) was significantly shorter than that by medetomidine alone (10.4 +/- 2.9 min). The duration of anaesthesia induced by MK was shorter than that by MBK2.5. The analgesic effects of MBK were more potent than those of MK. Mean arterial blood pressure increased significantly after administration of the sedatives, and then decreased to base-line value after the ketamine injection and remained stable throughout the experimental period. Respiratory rate decreased gradually after the administration of each sedative and was depressed until 60 min after the ketamine injection. MBK anaesthesia is effective and widely available for therapeutic procedures depending upon the selection of the ketamine dose.

Extrapontine myelinolysis presenting with parkinsonism as a sequel of rapid correction of hyponatraemia

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Suppressive effects of S-methyl methanethiosulfonate on promotion stage of diethylnitrosamine-initiated and phenobarbital-promoted hepatocarcinogenesis model

Modifying effects of S-methyl methanethiosulfonate (MMTS) on diethylnitrosamine (DEN)-initiated and phenobarbital (PB)-promoted hepatocarcinogenesis were examined in rats. Five-week-old male F344 rats were divided into 8 groups. After a week, groups 1-5 were given DEN (100 mg/kg body weight, i.p.) once a week for 3 weeks, whereas groups 6-8 received vehicle treatment. Group 2 was given 100 ppm MMTS containing diet in the initiation phase. From 4 weeks after the start of experiment, groups 3 and 5 were fed MMTS, and groups 1-3 and 7 received drinking water containing 500 ppm PB. Group 6 was given MMTS diet alone throughout the experiment (24 weeks). The incidences of hepatocellular adenoma and total liver tumors were significantly smaller in group 3 than those of group 1. The average numbers of hepatocellular adenoma, carcinoma and total tumors in group 3 were significantly smaller than in group 1. Glutathione S-transferase placental form-positive foci were also significantly decreased by MMTS treatment in the promotion phase. MMTS treatment in the initiation or promotion phase reduced ornithine decarboxylase activity in the liver of rats given DEN. The antioxidant activity against lipid peroxidation of MMTS was confirmed in tests with rabbit erythrocyte membrane ghosts or rat hepatocytes. These results suggest that MMTS is a promising chemopreventive agent for liver neoplasia when concurrently administered with PB.

Mutation of the trkB gene encoding the high-affinity receptor for brain-derived neurotrophic factor in stroke-prone spontaneously hypertensive rats

Brain-derived neurotrophic factor and its receptor, trkB, are thought to play a crucial role for protection against neuronal death induced by brain ischemia, such as in stroke. In the present study we found a missense mutation in the trkB gene from all of the five substrains of stroke-prone spontaneously hypertensive rats (SHRSP) that were examined. This mutation was not found in six out of seven hypertensive but stroke-resistant ancestral strains (SHR) of SHRSP, nor in any of seven strains of normotensive, non-stroke-prone strains. Hippocampal neurons, which are particularly vulnerable to damage in stroke, were shown to be more susceptible to ischemic damage in SHRSP than in either SHR or normotensive, stroke-resistant controls. The association of a mutated trkB gene with the stroke-prone genotype found in this study suggests that the trkB gene merits further study as a promising candidate gene for stroke.

S-methyl methanethiosulfonate, bio-antimutagen in homogenates of Cruciferae and Liliaceae vegetables

The isolation of a new type of bio-antimutagen, S-methyl methanethiosulfonate (MMTS), from cauliflower (Brassica oleracea var. botrytis) and the distribution and formation of MMTS in Cruciferae and Liliaceae vegetables are described. For the separation and purification, cauliflower curds were homogenized, extracted with acetone, and then purified by organic solvent extraction and by various processes of chromatographic separation. The chemical structure of an active principle was identified as MMTS by GC-MS and 1H-NMR analyses. MMTS was widely found in vegetable homogenates of the Cruciferae and Liliaceae species, and is found from its precursor S-methyl-L-cysteinesulfoxide (SMCS), by wounding the vegetable tissues. Wounding may induce C-S lyase, which converts SMCS to MMTS. The amount of MMTS formed was affected by the pH value for C- lyase, but not by the SMCS content in a tissue homogenate.

The beneficial effect of dibutyryl cyclic adenosine monophosphate on warm ischemic injury of the rat liver induced by cardiac arrest

Dibutyryl cAMP (DBcAMP) has a high membrane permeability, and maintenance of the intracellular cAMP concentration may improve the viability of organs. In this study, the effect of DBcAMP pretreatment on warm ischemic injury of rat livers was evaluated. Warm ischemic liver injury was induced in adult Wistar rats weighing 250-280 g by leaving them at room temperature (22-25 degrees C) after cardiac arrest. The hepatic cAMP concentration, %ATP, and trypan blue-positive nuclear ratio were determined after different durations of warm ischemia. In addition, transaminase and endothelin-1 (ET-1) release into the perfusate were examined during 60 min of isolated liver perfusion with Krebs-Henseleit solution. The optimal dose and time of DBcAMP pretreatment were determined to be 15 mg/kg and 60 min prior to warm ischemia, respectively. Data on the trypan blue-positive nuclear ratio and the release of transaminases and ET-1 revealed that warm ischemia first damaged the endothelial cells and then the hepatocytes. DBcAMP pretreatment appeared to protect the liver from warm ischemic injury by increasing the intracellular cAMP concentration and stabilizing the cell membranes of endothelial cells and hepatocytes.

The differences in Ca(2+)-sensitivity of protein kinase C in platelets from Wistar Kyoto rat and stroke-prone spontaneously hypertensive rat

Thrombin-induced phosphorylation of 47 kDa protein (P47) in platelets, a substrate of protein kinase C (PKC), was defective in stroke-prone spontaneously hypertensive rats (SHRSP) (Hypertens. 14, 304-315, 1989). Platelet PKC from SHRSP and Wistar Kyoto rats (WKY) was partially purified and Ca(2+)-sensitivity of PKC activity was examined to understand the defect in the protein phosphorylation. When the platelets from SHRSP and WKY were homogenized in a buffer containing 10 mM EGTA and 2 mM EDTA, approx. 80% of PKC was in the cytosol fraction. PKC in this fraction was purified by DE52 and hydroxyapatite column chromatography. Both platelet PKC preparations contained only PKC-alpha, and there was no significant difference in the Ca(2+)-dependency of activity between them. When the platelets from SHRSP and WKY were homogenized in a buffer containing 10 microM CaCl2, 90% of PKC was found to be bound to the membrane. PKC was extracted from the membrane with a buffer containing 2.5 mM EGTA and 2.5 mM EDTA, and purified by DE52 column chromatography. PKC from WKY platelets eluted as a single peak whereas that from SHRSP platelets eluted as two peaks (peak 1 and peak 2). Ca(2+)-sensitivity of peak 1 PKC was much lower than that of WKY PKC. In contrast, the Ca(2+)-sensitivity of peak 2 PKC appeared to be slightly higher than that of WKY PKC. The specific activity of peak 2 PKC was 4% to 5% of that of peak 1 and WKY PKC. These results suggest that there are two different types of PKC, normal and low Ca(2+)-sensitive in SHRSP platelets. Defective P47 phosphorylation in SHRSP platelets might be attributable to the occurrence of this low Ca(2+)-sensitive PKC.

Low affinity nerve growth factor receptor gene co-segregates with decreased bodyweight and increased left ventricular weight in spontaneously hypertensive rats

1. The sympathetic nervous system influences the cardiovascular and hormonal systems and sympathetic innervation is dependent on nerve growth factor (NGF). The NGF gene is linked genetically to high blood pressure in the spontaneously hypertensive rat (SHR) and there exists a mutation in the SHR low affinity NGF receptor (LNGFR) gene. 2. To determine whether the LNGFR mutation was linked genetically with cardiovascular phenotypes we studied an F2 population derived from SHR and normotensive Donryu (DRY) rats. 3. Mean arterial pressure (MAP), left ventricular mass (LVM) and related phenotypes were measured in 127 20 week old male F2 rats and correlated with the inheritance of the SHR mutation (S) and/or the DRY allele (D) of the LNGFR. 4. Analysis of variance revealed that the S mutation was associated with a significantly lower bodyweight in F2 rats (P < 0.0001). 5. The S mutation was associated with a significant (P < 0.007) increase in LVM:bodyweight ratio, but not with differences in right ventricular or kidney weights corrected for bodyweight. We found no association between MAP and LNGFR alleles or genotypes. 6. These results suggest that the mutation in the signal peptide of LNGFR may serve as a useful marker for the analysis of genetic factor(s) involved in the differential determination of body size and heart weight.