Protective effect of fluvastatin, a new inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, on MPP(+)-induced hydroxyl radical in the rat striatum

We examined whether fluvastatin, an inhibitor of low-density lipoprotein (LDL) oxidation, can resist 1-methyl-4-phenylpyridine (MPP(+))-induced hydroxyl radical generation (.OH) in the extracellular fluid of rat striatum. Rats were anesthetized and sodium salicylate in Ringer's solution (0.5 nmol/microliter/min) was infused through a microdialysis probe to detect the generation of.OH as reflected by the nonenzymatic formation of 2,3-dihydroxybenzoic acid (DHBA) in the striatum. MPP(+) (5 mM; total dose 75 nmol) clearly produced an increase in.OH formation. However, fluvastatin (100 microM) reduced the.OH formation by the action of MPP(+). These results indicated that fluvastatin, a potent inhibitor of LDL oxidation, may resist the formation of.OH products of MPP(+).

Growth inhibition of human fibroblasts by epidermal growth factor in the presence of arachidonic acid

The effect of epidermal growth factor on growth of human fibroblasts was investigated in serum-free medium supplemented with various fatty acids. When linoleic acid, arachidonic acid, or eicosapentaenoic acid was added, each inhibited epidermal growth factor-induced cell growth and showed cytotoxicity at high concentrations (greater than 10 microM). This cytotoxic effect was not observed in the presence of indomethacin, suggesting that prostaglandin production is important in mediation of the growth inhibition. Prostaglandin E2 was increased more than ten thousand times by epidermal growth factor in combination with arachidonic acid.

Effects of long-term treatment with dicyclic, tricyclic, tetracyclic, and noncyclic antidepressant drugs on monoamine oxidase activity in mouse brain

1. The individual long-term effects of the antidepressant drugs zimeldine, viloxazine, imipramine, amitriptyline, nortriptyline, maprotiline, or nomifensine, on brain mitochondrial monoamine oxidase (MAO) activity, were studied in mice that were given daily intraperitoneal injections (30 mg/kg) of these reagents for 4 weeks. 2. Both the A-form (MAO-A) and B-form (MAO-B) of MAO were inhibited after long-term administration of all the drugs except nortriptyline (MAO-A was not affected) and maprotiline (neither MAO-A nor MAO-B were affected). 3. Kinetic analysis showed a significant decrease in Vmax values, and an increase in K(m) values for MAO-B during treatment. 4. All seven drugs are competitive inhibitors of MAO-A, noncompetitive inhibitors of MAO-B, and were more potent in vitro for MAO-B. 5. MAO-A was inhibited by the following drugs (in ascending order of potency) : nortriptyline, amitriptyline, imipramine, maprotiline, zimeldine, nomifensine, and viloxazine. 6. MAO-B was inhibited by the following drugs (in ascending order of potency): nortriptyline, imipramine, maprotiline, amitriptyline, zimeldine, nomifensine, and viloxazine.

Effect of methylprednisolone on plasma lipid peroxidation induced by lipopolysaccharide

The effects of methylprednisolone succinate (MP) on plasma lipid peroxidation, plasma SOD activity and superoxide production in polymorphonuclear leukocytes (PMNs) induced by lipopolysaccharide (LPS) were examined in rats in vivo and in vitro. In rats subjected to LPS treatment, plasma phosphatidylcholine hydroperoxide (PCOOH) levels significantly increased, and the plasma Cu,Zn-SOD activity decreased by about 75%. When rats were given 30 mg/kg of MP intravenously, MP suppressed the elevation of plasma PCOOH levels and partially inhibited the decrease in plasma Cu,Zn-SOD activity. MP also suppressed PMA-induced superoxide production in PMNs primed by LPS. In in vitro experiments, low concentrations of MP had no effect on NADPH-dependent lipid peroxidation, but 4 mM MP produced 50% inhibition. MP had little effect on PMA-induced superoxide production in PMNs primed by LPS. Moreover, MP had no radical-trapping effect on superoxide, hydroxyl radical and stable DPPH radical. These results suggest that the suppressive effect of plasma lipid peroxidation by MP is not due to radical-trapping effects or preventive anti-oxidation, but may involve the suppression of the lipid chain reaction in liver membrane resulting from PMA-induced superoxide anions generated by PMNs.

Irinotecan plus carboplatin for patients with carcinoma of unknown primary site

Carcinoma of unknown primary site (CUP) is rarely encountered in clinical practice and optimal chemotherapy has not yet been established. This phase II study was conducted to evaluate the efficacy and toxicity of combined irinotecan+carboplatin therapy in chemotherapy-naive patients with CUP. Irinotecan was administered at 60 mg m(-2) as a 90-min intravenous infusion on days 1, 8 and 15. Carboplatin was administered at an area-under-the curve of 5 mg ml(-1) min as a 60-min intravenous infusion on day 1. This cycle was repeated every 28 days for up to six cycles. Forty-five patients were enrolled in the study. An intent-to-treat analysis revealed an objective response rate to the treatment of 41.9% (95% confidence interval, 27.0-57.9%). The median time to progression was 4.8 months and the median survival was 12.2 months. The 1- and 2-year survival rates were 44 and 27%, respectively. The most frequent grade 3 or more severe adverse events were leukopaenia (21%), neutropaenia (33%), anaemia (25%) and thrombocytopaenia (20%). Thus, the combination of irinotecan plus carboplatin was found to be active in patients with CUP. Therefore, the regimen may be one of the potentially available chemotherapeutic options for community standard of care in patients with a good performance status.

Preserved autonomic function in patients with POEMS syndrome

AIM

We systematically performed autonomic testing on patients with polyneuropathy, organomegaly, endocrinopathy, M-protein and skin changes syndrome (POEMS) to determine whether autonomic function is preserved in such patients.

METHODS

We studied 17 POEMS patients, 17 diabetic neuropathy (DN) patients and 17 age-matched normal subjects. Blood pressure responses to the head-up tilt test and heart rate variability were used to evaluate cardiovascular autonomic function. Sweat responses and cutaneous vasoconstriction to several stimuli were recorded via the finger tips to estimate cutaneous sympathetic function. In addition, motor nerve conduction studies were performed.

RESULTS

Although the results of the autonomic testing were normal in POEMS patients, motor disability was severe, and motor nerve conduction studies provided evidence of extensive axonal loss. The DN patients showed significantly impaired autonomic responses despite mild motor dysfunction.

CONCLUSIONS

Autonomic function was normal in POEMS patients, indicating the preservation of autonomic fibers and selective involvement of large fibers.

Three-dimensional organization of lymphatics in the dog small intestine: a scanning electron microscopic study on corrosion casts

Casts of the lymphatics of the canine small intestine were made by direct injection of a low viscosity methacrylate resin into a large lymphatic in the submucosal layer, and observed under a scanning electron microscope. The lymphatics started with rod-like central lacteals in the villi of the jejunum and leaf-like ones in those of the ileum. The bases of the lacteals were connected by slender lymphatics forming a three-dimensional network, tentatively called the "superficial lamina propria lymphatic plexus". From this plexus, a few straight branches descended through the lamina propria to drain into a well developed "deep lamina propria lymphatic plexus", which was extended two-dimensionally closely above the lamina muscularis mucosae. From this plexus, a few short lymphatics extended and penetrated the muscularis mucosae and drained into the "superficial submucosal lymphatic plexus", a coarse mesh work of thick lymphatics. From this plexus, a few slender lymphatics descended to drain into a second lymphatic plexus, called the "deep submucosal lymphatic plexus", which extended two-dimensionally on the circular muscle layer. This deep submucosal plexus was a coarse network of thick knotty lymphatics. A large collecting lymphatic was occasionally seen running through the mesh. The tunica muscularis contained tubular lymphatics extending horizontally parallel to the muscle fiber, both circular and longitudinal.

Effect of warfarin on plasma and liver vitamin K levels and vitamin K epoxide reductase activity in relation to plasma clotting factor levels in rats

Changes in plasma and liver vitamin K1 and vitamin K1 epoxide levels, liver microsomal vitamin K epoxide reductase activity, and plasma clotting factor II and VII levels were determined in rats after a single injection of warfarin (2.5 mg/kg, s.c.). The plasma and liver vitamin K1 levels gradually decreased after warfarin injection, attaining the lowest values at 2-3 hrs and remaining low for 48 hrs. They then returned to the control levels at 72 hrs. The changes in vitamin K1 epoxide levels were opposite, with an increase being seen soon after the warfarin injection, the highest values at 3 hrs and a gradual decrease to the initial levels occurring subsequently. The combined levels of vitamin K1 plus vitamin K1 epoxide, however, remained almost constant in both plasma and liver after the warfarin injection. The liver vitamin K epoxide reductase activity decreased to its lowest level soon after the injection and then gradually increased after 12 hrs, but the activity at 72 hrs was only about 30% of the initial activity. The plasma clotting factor levels gradually decreased after the injection, bottomed at 24 hrs and then began to increase, recovering almost to the initial levels at 72 hrs. A positive correlation was found between plasma and liver levels for both vitamin K1 and vitamin K1 epoxide, and the slope of the vitamin K1 epoxide curve was steeper than that for vitamin K1 in the warfarin-treated rats. A similar positive correlation was found for both vitamin K1 and vitamin K1 epoxide after vitamin K1 injection in normal untreated rats, but the slope of the vitamin K1 epoxide curve was much shallower. These results suggest that warfarin inhibits vitamin K epoxide reductase and decreases blood clotting factor synthesis, thus increasing plasma and liver vitamin K1 epoxide levels. A vitamin K epoxide reductase activity one third of that in normal rats is sufficient to maintain normal reduction of vitamin K1 epoxide and synthesis of blood clotting factors.

Investigation of the renal injury caused by liver ischemia-reperfusion in rats

To explain the mechanism of renal injury caused by liver ischemia-reperfusion, we investigated biochemical and morphological changes in the liver and kidney in rats. After reperfusion following 60 min of liver ischemia, numerous changes were found. The level of serum transaminases and lipid peroxide formation in the liver tissue increased significantly. Electron microscopic studies revealed that most of the hepatocytes had swollen mitochondria and clumping of the nuclear chromatin. The sinusoidal endothelium was disrupted and the sinusoidal lumen was filled with numerous erythrocytes. Blood endotoxin concentration, plasma lipid peroxide levels, and serum beta-glucuronidase activities were significantly higher than in the control group. Biochemical and morphological renal injury was also observed. Tissue lipid peroxide levels increased in both the kidney and the liver. Microscopic examination revealed damage to the renal tubules, including interstitial edema, dilatation of the lumen, and granular casts derived from necrotic cells in the proximal convoluted tubule. The levels of urinary N-acetyl-beta-D-glucosaminidase (NAG) in the liver ischemia-reperfusion group were also higher than in the control group. These results suggest that the renal injury was caused by an increase in endotoxin, lipid peroxide, and lysosomal enzymes in the blood following the liver injury induced by the ischemia-reperfusion.

Nicorandil increases adenosine 5'-monophosphate-primed interstitial adenosine via activation of ecto-5'-nucleotidase in rat hearts

With the use of microdialysis techniques, we examined the effects of nicorandil, a hybrid of an ATP-sensitive K+ (K ATP) channel opener and a nitrate compound, on the production of interstitial adenosine in rat hearts in situ. The level of dialysate adenosine measured under a constant supply of adenosine 5'-monophosphate (AMP) reflected the activity of endogenous ecto-5'-nucleotidase. Nicorandil (0.3-3mM) increased the level of AMP (100 microM)-primed dialysate adenosine in a concentration-dependent manner, and this effect was completely abolished by the guanylate cyclase inhibitor, methylene blue (100 microM), but not by the K ATP channel blocker, glibenclamide (10 microM). Another K ATP channel opener, cromakalim (0.1-1mM), did not increase the production of AMP-primed dialysate adenosine. These results suggest that nicorandil increases the level of interstitial adenosine via cyclic guanosine monophosphate-mediated activation of ecto-5'-nucleotidase.

Inhibition of monkey brain semicarbazide-sensitive amine oxidase by various antidepressants

We examined whether the antidepressant drugs, such as the dicyclic drug zimeldine, the tricyclic drug imipramine, tetracyclic drug maprotiline, and the non-cyclic drug nomifensine, inhibit in vitro semicarbazide-sensitive amine oxidase (SSAO) activity in monkey brain. The deamination of 1 microM benzylamine was not inhibited at high concentrations of clorgyline or deprenyl, while it was highly sensitive for semicarbazide. When corresponding experiments were performed with 100 microM benzylamine, the opposite results were obtained. The most potent of inhibition of SSAO was observed by imipramine, followed by maprotiline, zimeldine and nomifensine. Inhibition of SSAO was not enhanced by varying the time of preincubation of the enzyme and various antidepressant drugs, indicating direct action on and reversible inhibition of SSAO. We found the tricyclic antidepressant drug to be the most selective inhibitors of SSAO activity in monkey brain, as compared with other type of antidepressant drugs.

Potassium chloride depolarization enhances MPP+-induced hydroxyl radical generation in the rat striatum

We determined that extracellular potassium ion concentration, [K+]o-induced depolarization, enhances 1-methyl-4-phenylpyridinium ion (MPP+)-induced hydroxyl radical (*OH) generation in the rat striatum. Rats were anesthetized, and sodium salicylate in Ringer's solution (0.5 nmol/microl/min) was infused through a microdialysis probe to detect the generation of *OH as reflected by the non-enzymatic formation of 2,3-dihydroxybenzoic acid (DHBA) in the striatum. Induction of high concentration KCl (70 mM) drastically increased formation of *OH trapped as DHBA by the action of MPP+. When dopamine (DA) was administered to the high KCl-treated animals, a marked elevation of DHBA was observed, compared with MPP+-only-treated animals, that showed a positive linear correlation between DA and *OH formation trapped as DHBA (R2 = 0.979) in the dialysate. When corresponding experiments were performed with iron (II), the same results were obtained: a positive linear correlation between the release of iron (II) and DHBA (R2 = 0.988) in the dialysate. These results suggest that [K+]o-induced depolarization enhances the formation of *OH products of efflux/oxidation due to MPP+.

Characteristics of mitochondrial and synaptosomal monoamine oxidase in monkey brain

Enzymic properties of monoamine oxidase (MAO) from monkey brain were studied. High MAO activity was observed in the mesencephalon and dienecephalon of the brain. Highest activity in every region of the brain was found with tyramine as a substrate. Monkey brain mitochondrial MAO showed a different substrate specificity and different Km and Vmax values than the enzyme from mice, rats, guinea pigs and rabbits. The pH activity curves were all bell-shaped, but the pH optima were remarkably different with the various substrates used. The activities of various substrates at pH 7.2 were compared with those at the pH optimum. At the pH optima, the activity was about 1.2-fold higher with tyramine and dopamine, 2-fold higher with beta-phenylethylamine (beta-PEA) and 3-fold higher with serotonin (5-HT) and benzylamine. These results were almost similar when synaptosomes from monkey brain were used. MAO activities with 5-HT and beta-PEA were strongly inhibited by much lower concentrations of clorgyline and deprenyl, respectively. Plateau-shaped inhibition curves by these inhibitors were obtained with tyramine as the substrate. These results indicate that both the A- and B-form of MAO appear to be uniformly distributed in monkey brain, and the A-form of MAO represents approximately 35% and 50% of the total MAO activity in mitochondria and synaptosomes, respectively.

Effects of microinjection of a GABA antagonist into the periaqueductal gray upon electrically-induced vocalization in decerebrate cats

The effects of the GABA antagonist bicuculline methiodide (BIC), microinjected into the ventrolateral periaqueductal gray (PAG) on the stimulus threshold of electrically-induced vocalization were examined in unanesthetized precollicular-postmamillary decerebrate cats. To induce vocalization, repetitive electrical stimulation (0.2 ms, 100 Hz, 5-10 s duration) was delivered to the caudal portion of the PAG (30 to 300 microA) or the pontine call site (PCS) (10 to 60 microA) in the ventrolateral pontine reticular formation. Injection of 0.1 microliter of 2 mM BIC into the caudal portion of the PAG decreased the stimulus thresholds of the PCS and the injection site for about 1 h. Injection of BIC into the reticular formation near the PAG, where the electrical stimulation induced vocalization, did not decrease the stimulus thresholds of the PCS or the injection site. These results indicate that GABAergic inhibition regulates the excitability of the cells within the ventrolateral PAG, which exerts an excitatory effect on the lower brain structures that produce vocalization.

Effects of tracheostomy on electrically induced vocalization in decerebrate cats

Electrical stimulation delivered to the rostral pons induced well coordinated activity of the intralaryngeal muscles and the ventilatory muscles for vocalization in unanesthetized, decerebrate cats. The stimulation reset the normal respiratory rhythm and induced vocalization with a newly developed rhythm. Continuous opening of the tracheostomy decreased the breathing cycle during induced vocalization. Opening of the prepared tracheostomy during vocalization caused a sudden decrease in the subglottic pressure, but the expiration phase was not abruptly terminated. These findings suggested that vagal feedback from pulmonary stretch receptors plays a more significant role in the maintenance of the breathing cycle during electrically induced vocalization than the laryngeal feedback from the laryngeal mucosa.

Morphological analysis of subgingival biofilm formation on synthetic carbonate apatite inserted into human periodontal pockets

BACKGROUND

Details of the development of human subgingival biofilm are unknown due to the difficulties in conducting experiments and especially in obtaining undisturbed materials.

METHODS

This study was performed using deposits on carbonate apatite that had been inserted into human periodontal pockets for up to three weeks. Scanning electron microscopy using the vertically sectioned method and transmission electron microscopy using the freeze-substitution method were adopted.

RESULTS

The development of subgingival biofilm occurred in five sequential phases: pellicle formation, microbial adherence, initial colonization, microbial organization, and establishment. Certain species in each of the initial, secondary and tertiary colonizers were considered to have a predilection for biofilm formation. Gram-positive, bacillary initial colonizers and gram-negative, filamentous secondary colonizers organized one stable structure that served as the framework for biofilm formation, and gram-negative, rod-shaped tertiary colonizers with cell-surface vesicles showed multigeneric coaggregation. The microbiota in the tertiary colonizers underwent repeated microflora alteration.

CONCLUSIONS

Subgingival biofilm is constituted by initial, secondary and tertiary colonizers. Microflora alteration which is suggested to be related to periodontal disease, frequently occurred in the tertiary colonizers.

Modulation of neuronal MAO activity, 5-HT uptake and imipramine binding by endogenous substances in dog cerebrospinal fluid

Addition of small amounts of dog cerebrospinal fluid (CSF) inhibited both type A and type B monoamine oxidase (MAO) in dog brain mitochondria. The inhibition was competitive with 5-HT as substrate, but non-competitive with beta-phenylethylamine as substrate. Tricyclic antidepressants also exhibited competitive inhibition with type A MAO, but were non-competitive with type B MAO. The endogenous materials in CSF activate [3H]-imipramine specific, dose-dependent binding in dog brain preparations. The maximum number of binding sites (Bmax) increased, but the dissociation constant (Kd) was altered significantly in the presence of CSF. Addition of CSF induced a marked activation of uncompetitive [14C]-5-HT uptake in dog brain preparations. Moreover, there were reversibilities of the inhibition of MAO activity or of the activation of imipramine binding and 5-HT uptake by CSF substance after dilution experiment. These results indicate the possible presence of an endogenous psychotic drug-like substance in CSF.

Simultaneous determination of methamphetamine and its metabolites in monkey urine by gas chromatography/mass spectrometry with selected ion monitoring

A sensitive and specific gas chromatography/mass spectrometry (GC/MS) method has been developed for the simultaneous analysis of methampthetamine and its metabolites (amphetamine, p-hydroxymethamphetamine, and p-hydroxyamphetamine) in monkey urine. The method has been applied to the analysis of urine samples from monkeys singly and repeatedly treated with methamphetamine. We have shown that the repeated administration of methamphetamine causes the reduction of urinary excretion of aromatic hydroxylated metabolites. We propose that the method described here can be used for biological monitoring.

Emphysematous change with scleroderma-associated interstitial lung disease: the potential contribution of vasculopathy?

Background

Pulmonary emphysema combined with systemic sclerosis (SSc)-associated interstitial lung disease (ILD) occurs more often in smokers but also in never-smokers. This study aimed to describe a new finding characterized by peculiar emphysematous change with SSc-associated ILD (SSc-ILD).

Methods

We conducted a retrospective review of 21 consecutive patients with SSc-ILD diagnosed by surgical lung biopsy and focused on the radio-pathological correlation of the emphysematous change.

Results

Pathological pulmonary emphysema (p-PE) with SSc-ILD was the predominant complication in 16 patients (76.2%) with/without a smoking history, of whom 62.5% were never-smokers. A low attenuation area (LAA) within interstitial abnormality on high-resolution computed tomography (HRCT) was present in 31.3%. Diffusing capacity of the lung for carbon monoxide (D_LCO) was lower, disease extent on HRCT higher, and intimal/medial thickening in muscular pulmonary arteries more common in the patients with p-PE with SSc-ILD. However, forced vital capacity (FVC) was well preserved regardless of whether p-PE was observed. Most SSc-ILD patients had pulmonary microvasculature changes in arterioles (90.5%), venules (85.7%), and interlobular veins (81.0%).

Conclusions

Pulmonary emphysematous changes (LAA within interstitial abnormalities on HRCT and destruction of fibrously thickened alveolar walls) are specific and novel radio-pathological features of SSc-ILD. Peripheral vasculopathy may help to destroy the fibrously thickened alveolar walls, resulting in emphysematous change in SSc-ILD.

Prazosin attenuates hydroxyl radical generation in the rat myocardium

The present study examined whether tyramine-induced hydroxyl radical (*OH) generation via noradrenaline release was attenuated by prazosin. A flexibly mounted microdialysis technique was used to detect the generation of *OH in in vivo rat hearts. The microdialysis probe was implanted in the left ventricular myocardium of anaesthetized rats and Ringer's solution was used. To measure the level of *OH, sodium salicylate in Ringer's solution (0.5 nmol/microl/min) was infused directly through a microdialysis probe to detect the generation of *OH as reflected by the nonenzymatic formation of 2,3-dihydroxybenzoic acid (DHBA). Tyramine (0.1, 0.5 and 1.0 mM) increased the level of 2,3-DHBA in a concentration-dependent manner. However, in the presence of prazosin (10 microM), the effect of tyramine was abolished. To confirm the generation of *OH by a Fenton type reaction, iron (II) was infused through a microdialysis probe. A positive linear correlation between iron (II) and the formation of 2,3-DHBA (R2 = 0.982) was observed. To examine the effect of prazosin on ischemic/reperfused rat myocardium, the heart was subjected to myocardial ischemia for 15 min by occlusion of the left anterior descending coronary artery. When the heart was reperfused, a marked elevation of the level of 2,3-DHBA was observed. However, in the presence of prazosin (10 microM), the elevation of 2,3-DHBA was not observed in ischemic/reperfused rat heart. Prazosin was shown to have a *OH scavenging effect. These results suggest that tyramine-induced noradrenaline causes *OH generation, an effect which is inhibited by prazosin as Na+ channel blocker, but not through its alpha1-adrenoceptor antagonistic action of prazosin.

Glibenclamide, an antagonist of ATP sensitive K+ channels, blocks free radical generation in the rat myocardium

The present study examined the effect of glibenclamide, an ATP-sensitive K+ (K(ATP)) channels antagonist, on the potassium chloride (KCl)-induced hydroxyl free radical (.OH) generation. Sodium salicylate in Ringer's solution (0.5 nmol/microl per min) was infused directly through a microdialysis probe to detect the generation of .OH as reflected by the formation of dihydroxybenzoic acid (DHBA) in the myocardium of anesthetized rat. The high concentration of KCl (70 mM) significantly increased the level of 2,3- and 2,5-DHBA by the action of depolarization by KCl. However, in the presence of glibenclamide (10 microM), KCl failed to increase the 2,3- and 2,5-DHBA formation. Moreover, when allopurinol (10 mg/kg), a xanthine oxidase inhibitor, was administered by i.v. injection, the elevation of DHBA was not observed. These results suggest that openings of cardiac K(ATP) channel by depolarization evokes .OH generation via xanthine oxidase reaction.