Effect of phosphoproteins on intracellular calcification of bacteria

This study aimed to evaluate the effects of phosphoproteins on bacterial mineralization. Dental calculus formation is attributed to bacterial mineralization in the oral cavity; however, the influence of phosphoproteins (which are abundant in saliva) is not clear. The model bacterium Escherichia coli was suspended in a calcification solution containing casein as a model phosphoprotein. To evaluate mineralization independent of bacterial metabolism, bacteria killed by heat treatment at 70°C were compared with viable bacteria. After incubation at 37°C for 24 h, the mode of calcification was observed using electron microscopy and energy dispersive x-ray spectroscopy. Solutions without casein produced precipitation in solution, which was identical to that in experiments without bacteria. In contrast, calcification solutions with 200 ppm casein only produced calcium phosphate deposition intracellularly. Without heat treatment, intracellular calcification rarely occurred, even when casein was added. Thus, phosphoproteins promoted intracellular calcification of dead bacteria; this is similar to the calcification of insoluble matrices, such as collagen fibrils, promoted by acidic polymers. We concluded that intracellular calcification is caused by the collagen fibril-like behavior of dead bacteria. The promotion of intracellular calcification of dead bacteria by phosphoproteins suggested a basic principle of dental calculus formation.

Analyzing redox balance in a synthetic yeast platform to improve utilization of brown macroalgae as feedstock

Macroalgae have high potential to be an efficient, and sustainable feedstock for the production of biofuels and other more valuable chemicals. Attempts have been made to enable the co-fermentation of alginate and mannitol by Saccharomyces cerevisiae to unlock the full potential of this marine biomass. However, the efficient use of the sugars derived from macroalgae depends on the equilibrium of cofactors derived from the alginate and mannitol catabolic pathways. There are a number of strong metabolic limitations that have to be tackled before this bioconversion can be carried out efficiently by engineered yeast cells.

An analysis of the redox balance during ethanol fermentation from alginate and mannitol by Saccharomyces cerevisiae using metabolic engineering tools was carried out. To represent the strain designed for conversion of macroalgae carbohydrates to ethanol, a context-specific model was derived from the available yeast genome-scale metabolic reconstructions. Flux balance analysis and dynamic simulations were used to determine the flux distributions. The model indicates that ethanol production is determined by the activity of 4-deoxy-l-erythro-5-hexoseulose uronate (DEHU) reductase (DehR) and its preferences for NADH or NADPH which influences strongly the flow of cellular resources. Different scenarios were explored to determine the equilibrium between NAD(H) and NADP(H) that will lead to increased ethanol yields on mannitol and DEHU under anaerobic conditions. When rates of mannitol dehydrogenase and DehR_NADH tend to be close to a ratio in the range 1–1.6, high growth rates and ethanol yields were predicted. The analysis shows a number of metabolic limitations that are not easily identified through experimental procedures such as quantifying the impact of the cofactor preference by DEHU reductase in the system, the low flux into the alginate catabolic pathway, and a detailed analysis of the redox balance. These results show that production of ethanol and other chemicals can be optimized if a redox balance is achieved. A possible methodology to achieve this balance is presented. This paper shows how metabolic engineering tools are essential to comprehend and overcome this limitation.

•

We studied a strain designed for bioconversion of macroalgae sugars to ethanol.

•

A genome-scale model was used to simulate biomass and by-product formation.

•

The characterization of the current metabolic state of the strain was achieved.

•

Biofuel production depends on the redox balance derived from alginate and mannitol.

•

Flux split into DehR determines the redox balance, by-products and ethanol level.

The in vivo synthesis of plant sesquiterpenes by Escherichia coli

Three plant genes encoding (+)-delta-cadinene, 5-epi-aristolochene, and vetispiradiene cyclases were expressed in Escherichia coli to evaluate the potential of this bacterium to synthesize sesquiterpenes in vivo. Various growth temperatures, carbon sources, and host strains were examined to optimize terpene production. The highest levels of sesquiterpene production occurred when the enzymes were expressed in strain DH5alpha from the trc promoter (Ptrc) of the high-copy plasmidpTrc99A in M9 medium supplemented with 0.2% (v/v) glycerol at 30 degrees C for 5-epi-aristolochene and vetispiradiene and 37 degrees C for (+)-delta-cadinene. The highest concentrations of sesquiterpenes observed were 10.3 microg of (+)-delta-cadinene, 0.24 microg of 5-epi-aristolochene (measured as (+)-delta-cadinene equivalents), and 6.4 microg of vetispiradiene (measured as (+)-delta-cadinene equivalents) per liter of culture. These sesquiterpene production levels are >500-fold lower than carotenoid production, both of which are synthesized from endogenous trans-farnesyl diphosphate (FDP) in E. coli. Based on these results, we conclude that the limiting factor for sesquiterpene synthesis in E. coli is the poor expression of the cyclase enzyme and not supply of the FDP precursor.

Three-dimensional laser microvision

A three-dimensional (3-D) optical imaging system offering high resolution in all three dimensions, requiring minimum manipulation and capable of real-time operation, is presented. The system derives its capabilities from use of the superstructure grating laser source in the implementation of a laser step frequency radar for depth information acquisition. A synthetic aperture radar technique was also used to further enhance its lateral resolution as well as extend the depth of focus. High-speed operation was made possible by a dual computer system consisting of a host and a remote microcomputer supported by a dual-channel Small Computer System Interface parallel data transfer system. The system is capable of operating near real time. The 3-D display of a tunneling diode, a microwave integrated circuit, and a see-through image taken by the system operating near real time are included. The depth resolution is 40 mum; lateral resolution with a synthetic aperture approach is a fraction of a micrometer and that without it is approximately 10 mum.

N-methyl-1-deoxynojirimycin (MOR-14), an alpha-glucosidase inhibitor, markedly reduced infarct size in rabbit hearts

BACKGROUND

N-methyl-1-deoxynojirimycin (MOR-14), an alpha-glucosidase inhibitor, reduces the glycogenolytic rate by inhibiting the alpha-1,6-glucosidase of glycogen-debranching enzyme in the liver, in addition to possessing an antihyperglycemic action by blocking alpha-1,4-glucosidase in the intestine. Because the reduction of the glycogenolytic rate may be one of the mechanisms of myocardial protection in ischemic preconditioning, the compounds inhibiting myocardial alpha-1,6-glucosidase may be protective against ischemic damage. Thus, we investigated whether MOR-14 could inhibit alpha-1,6-glucosidase and reduce the infarct size in rabbit hearts without collateral circulation.

METHODS AND RESULTS

MOR-14 dose-dependently decreased the alpha-1,6-glucosidase activity in rabbit heart extract. A tracer study demonstrated the myocardial uptake of a considerable amount of MOR-14 sufficient to fully inhibit alpha-1,6-glucosidase. To assess the infarct size-reducing effect of MOR-14, 54 rabbits were subjected to 30-minute coronary occlusion followed by 48-hour reperfusion. Preischemic treatment with 25, 50, and 100 mg/kg of MOR-14 dose-dependently reduced the infarct size (to 26+/-4%, 19+/-3%, and 14+/-2% of the area at risk, respectively), compared with the saline control (45+/-5%) without altering the blood pressure or heart rate. Another 40 rabbits given 100 mg of MOR-14 or saline 10 minutes before ischemia were euthanized at 10 or 30 minutes of ischemia for biochemical analysis. MOR-14 decreased the alpha-1,6-glucosidase activity to approximately 20% in vivo, reduced the glycogen breakdown, and attenuated the lactate accumulation at both 10 and 30 minutes of ischemia.

CONCLUSIONS

Preischemic treatment with MOR-14 preserved glycogen, attenuated the accumulation of lactate, and reduced the myocardial infarct size by 69%. This cardioprotective effect was independent of changes of blood pressure and heart rate or regional blood flow. It may be associated with alpha-1,6-glucosidase inhibition, because MOR-14 markedly decreased the alpha-1,6-glucosidase activity in the heart.

Inhibition of depolarization-induced nitric oxide synthase activation by NS-7, a phenylpyrimidine derivative, in primary neuronal culture

Neuronal nitric oxide synthase (NOS) is considered to be involved in the pathogenesis of ischemic brain damage. In the present study, the effect of a novel neuroprotective phenylpyrimidine derivative, 4-(4-fluorophenyl)-2-methyl-6-(5-piperidinopentyloxy)pyrimidine hydrochloride (NS-7), on depolarization-stimulated NOS activity was examined in cultured neurons of mouse cerebral cortex. Various depolarizing stimuli such as veratridine, KCl, and N-methyl-D-aspartate increased the NOS activity determined by cyclic GMP formation. NS-7 concentration-dependently inhibited both the veratridine- and KCl-induced NOS activation with IC50 values of 9.3 and 9.6 microM, respectively. The reversal of KCl-evoked NOS activity by NS-7 was also observed under blockade of both ionotropic glutamate receptors and the Na+ channel with MK-801, 6-cyano-7-nitroquinoxaline-2,3-dione, and tetrodotoxin. In contrast, NS-7, even at 100 microM, did not affect N-methyl-D-aspartate-stimulated NOS activity, nor did it have any influence on NOS activity determined in the soluble fraction of rat hippocampus. Because NS-7 has already been shown to block both Na+ and Ca2+ channels, the present findings suggest that this compound inhibits depolarization-induced NOS activation by reducing Ca2+ influx through blockade of Na+ and Ca2+ channels in primary neuronal culture.

Comparison of the effects of NS-21 and terodiline on the QTc interval in dogs

1. NS-21 [(+/-)-4-diethylamino-1,1-dimethylbut-2-yn-1-yl 2-cyclohexyl-2-hydroxy-2-phenylacetate monohydrochloride monohydrate], its active metabolite, RCC-36, and terodiline, are mixed anticholinergic-Ca2+ antagonistic drugs. Among them, terodiline has been shown to cause torsade de pointes, a serious polymorphic ventricular tachycardia. It remains unknown, however, whether NS-21 or its active metabolite, RCC-36, produces torsade de pointes. 2. In anesthetized dogs, terodiline (10 mg/kg i.v.) significantly prolonged the QTc interval by 6-8%, an effect thought to be associated with torsade de pointes. In contrast, neither NS-21 nor RCC-36 (10 mg/kg i.v.) prolonged the QTc interval; therefore NS-21 is unlikely to cause ventricular tachyarrhythmias, such as those associated with terodiline. 3. The effects of NS-21, RCC-36 and terodiline on the action potential were investigated in guinea pig papillary muscle. However, none of these drugs prolonged the duration of the action potential, although only terodiline caused the muscle preparation to lose its excitability.

Effect of a novel cognition enhancer NS-105 on learned helplessness in rats: possible involvement of GABA(B) receptor up-regulation after repeated treatment

We have previously found that a cognition enhancer [(+)-5-oxo-D-prolinepiperidinamide monohydrate] (NS-105) reversed the inhibition of cyclic AMP formation induced by the GABA(B) receptor agonist baclofen. The GABA(B) receptor has been implicated in the pathophysiology of depressive illness. The present experiment was designed to evaluate the antidepressant activity of NS-105 in the forced swimming and learned helplessness tests in rats. NS-105 (1-100 mg/kg, p.o.) significantly decreased immobility time in the forced swimming test, an effect similar to that of desipramine. Repeated administration of NS-105 also reversed the failure to escape in the shuttle-box test of rats previously exposed to inescapable footshock. Biochemical data showed that repeated administration of NS-105 increased the number of GABA(B) receptors in rat cerebral cortex without affecting the binding properties of beta-adrenoceptors and 5-HT2 receptors. In contrast to other antidepressants, NS-105 did not inhibit monoamine uptake in vitro, nor did it change monoamine concentrations in brain tissues or extracellular fluids. These findings suggest that NS-105, which lacks an effect on monoaminergic systems, has potent antidepressant activity, which may involve up-regulation of GABA(B) receptors after repeated administration.

Anticholinergic and calcium antagonistic activities of NS-21 contribute to the inhibition of rat urinary bladder contractions

1. Pharmacological characteristics of NS-21 and its main metabolite, RCC-36, in the inhibition of rat urinary bladder contractions were investigated both in vitro and in vivo. 2. NS-21 and RCC-36 inhibited muscarinic receptor bindings to rat bladder membranes with [3H]3-quinuclidinyl bezilate (pKi 6.19 and 7.24, respectively), whereas they failed to inhibit the following receptor bindings: adrenergic (alpha 1, alpha 2 and beta), dopaminergic (D1 and D2), adenosine (A1 and A2), histaminergic (H1) and opioid (mu, delta and kappa) receptors. 3. NS-21 and RCC-36 suppressed carbachol-induced contractions of isolated rat detrusor strips in competitive (pA2 6.80 and 7.93, respectively) and noncompetitive (pD'2 5.93 and 5.77, respectively) manners. 4. NS-21 and RCC-36 inhibited CaCl2-induced contractions of rat detrusor strips in the presence of 100 mM K+ (pIC50 6.54 and 5.76, respectively), as well as the 100 mM K(+)-induced 45Ca influx into the isolated bladder strips at > or = 1 microM. 5. Electrical stimulation of the peripheral end of the pelvic nerve in anesthetized rats induced bladder contractions composed of two phases: an initial phasic contraction that was weakly suppressed by atropine, and a tonic contraction that was strongly suppressed by atropine. NS-21 suppressed both contractions to the same degree (ID50 2.65 and 2.19 mg/kg, i.v., respectively). RCC-36 suppressed the tonic contraction (ID50 1.20 mg/kg, i.v.) more markedly than the initial contraction (ID50 7.43 mg/kg, i.v.). 6. These results suggest that NS-21 and RCC-36 suppressed bladder contractions owing to their anticholinergic and calcium antagonistic activities.

Na+ and high-voltage-activated Ca2+ channel blocking actions of NS-7, a novel neuroprotective agent, in NG108-15 cells

The actions of a novel neuroprotective compound, 4-(4-fluorophenyl)-2-methyl-6-(5-piperidinopentyloxy)pyrimidine hydrochloride (NS-7), on voltage-gated Na+, Ca2+ and K+ channels were investigated in a mouse neuroblastoma and rat glioma hybrid cell line, NG108-15, using a whole-cell voltage clamp technique. NG108-15 cells have a tetrodotoxin-sensitive Na+ channel, three types of Ca2+ channel (L, N and T) and voltage-gated K+ channels, all of which were inhibited by NS-7 in a concentration-dependent manner. However, there was a considerable difference in its potency: the IC50 values for the tetrodotoxin-sensitive Na+ channel, L-type Ca2+ channel and N-type Ca2+ channel were similar (7.8, 4.5 and 7.3 microM, respectively), lower than the IC50 value for the T-type Ca2+ channel (17.1 microM), and much lower than the IC50 value for the voltage-gated K+ channel (160.5 microM). NS-7 altered neither the shape nor the reversal potential of the current-voltage curves for Na+, L-type or N-type Ca2+ channels, although the currents were reduced at every potential tested. These results indicate that NS-7 is a Na+ and high-voltage-activated (L- and N-type) Ca2+ channel blocker, and its channel-blocking properties may contribute to its neuroprotective action.

Permeability of a neuroprotective compound NS-7 into brain: comparison between normal and middle cerebral artery-occluded rats

The pharmacokinetics of 4-(4-fluorophenyl)-2-methyl-6-(5-piperidinopentyloxy) pyrimidine hydrochloride (NS-7), a novel neuroprotective compound, in brains of normal and ischemic rats were investigated. In normal rats, the concentrations of NS-7 in the cerebral cortex and striatum were more than 10-folds higher than those in plasma during 5 min and 12 h after intravenous injection. The time course changes in plasma concentration of NS-7 were fitted to the two-compartment open model, in which elimination half-life (t(1/2)beta) was 6.0 h and distribution volume (V1) was 4.4. The estimated striatal interstitial concentration of NS-7 measured by microdialysis was unexpectedly low and almost constant after intravenous injection. Subsequently, the level of NS-7 in brain was compared between sham-operated and middle cerebral artery (MCA)-occluded rats. In MCA-occluded rats, the concentrations of NS-7 in the ischemic cerebral cortex and striatum were 64-71% of those in sham-operated group at 1 h after injection, although the initial concentrations (at 2-5 min) were much lower (about 20%) in MCA-occluded rats. The t(max) was observed at 1 h after injection, which was later than that (5 min) determined in sham-operated rats. Moreover, its elimination half-life was longer in MCA-occluded rats than in sham-operated animals. From these results it is suggested that peripherally administered NS-7 readily penetrates into brain, in which it exists for the most part in parenchymal fraction. In addition, substantial amount of NS-7 may distribute to the ischemic brain regions when it was injected after MCA occlusion.

A novel cognition enhancer NS-105 modulates adenylate cyclase activity through metabotropic glutamate receptors in primary neuronal culture

The effect of (+)-5-oxo-D-prolinepiperidinamide monohydrate (NS-105), a novel cognition enhancer, on adenylate cyclase activity was investigated in cultured neurons of the mouse cerebral cortex. NS-105 (10(-7) and 10(-6) M) inhibited forskolin-stimulated cyclic AMP formation, an action that was dependent on pertussis toxin-sensitive G proteins. Conversely, in pertussis toxin-pretreated neurons, NS-105 (10(-7)-10(-5) M) significantly enhanced the forskolin-stimulated cyclic AMP formation, and this action was completely reversed by cholera toxin. A metabotropic glutamate receptor agonist (1S, 3R)-1-aminocyclopentane-1,3-dicarboxylic acid (1S, 3R-ACPD) produced similar bi-directional actions on the cyclic AMP formation. Both of these inhibitory and facilitatory actions of NS-105 and 1S, 3R-ACPD were blocked by L(+)-2-amino-3-phosphopropinoic acid (L-AP3). NS-105 (10(-6) M) and 1S, 3R-ACPD (10(-4) M) significantly enhanced isoproterenol- and adenosine-stimulated cyclic AMP formation. The enhancement of such Gs-coupled receptor agonists-stimulated cyclic AMP formation was also produced by quisqualate but not by L(+)-2-amino-4-phosphonobutanoate (L-AP4). The phosphoinositides hydrolysis was enhanced by 1S, 3R-ACPD (10(-4) M) but not by NS-105 (10(-6) M), however, 1S, 3R-ACPD-induced increase in phosphoinositides turnover was attenuated by NS-105. These findings suggest that NS-105 stimulates metabotropic glutamate receptor subclasses that are coupled both negatively and positively to adenylate cyclase, but it acts as an antagonist at the receptor subclasses that are linked to phosphoinositides hydrolysis.

Effect of NS-21, an anticholinergic drug with calcium antagonistic activity, on lower urinary tract function in a rat model of urinary frequency

BACKGROUND

NS-21 is under development for the treatment of urinary frequency and urinary incontinence. The purpose of this study was to investigate the effects of NS-21 and its active metabolite, RCC-36, on lower urinary tract function in an experimental rat model of urinary frequency.

METHODS

Cystometrograms were recorded in anesthetized rats with bilaterally transected hypogastric nerves. All drugs were administered intraduodenally.

RESULTS

In sham-operated rats, NS-21 (> or = 50 mg/kg) significantly increased the bladder capacity without significantly decreasing micturition pressure, while RCC-36 (100 mg/kg) significantly increased bladder capacity, and at a dose of > or = 30 mg/kg, also caused a decrease in micturition pressure. This increase in bladder capacity appeared at lower doses of both NS-21 and RCC-36 in the hypogastric nerve-transected rats. Propiverine (100 mg/kg) increased bladder capacity and at > or = 30 mg/kg, decreased micturition pressure in both sham-operated and nerve-transected rats. Oxybutynin (100 mg/kg) and atropine (30 mg/kg) decreased the micturition pressure in both sham-operated and nerve-transected rats without increasing the bladder capacity, while a similar anticholinergic calcium antagonist, terodiline (100 mg/kg) had no effect on bladder capacity in either sham-operated or nerve-transected rats. Flavoxate (500 mg/kg) significantly increased bladder capacity without significantly decreasing micturition pressure in both sham-operated and nerve-transected rats, while 50 mg/kg of verapamil significantly increased bladder capacity without significantly decreasing the micturition pressure in nerve-transected rats.

CONCLUSIONS

NS-21 and RCC-36 increased bladder capacity at lower doses in hypogastric nerve-transected rats than in sham-operated rats. Furthermore, NS-21 increased the bladder capacity without suppressing micturition pressure, suggesting that NS-21 may be a more effective therapeutic drug than propiverine, oxybutynin or flavoxate for the treatment of urinary frequency and urinary incontinence.

Inhibition of ischemia-induced fodrin breakdown by a novel phenylpyrimidine derivative NS-7: an implication for its neuroprotective action in rats with middle cerebral artery occlusion

The effect of a novel neuroprotective compound, NS-7 [4-(4-fluorophenyl)-2-methyl-6-(5-piperidinopentyloxy)pyrimidine hydrochloride], on ischemia-induced fodrin breakdown was examined both in vitro and in vivo. The fodrin breakdown was measured by western blot followed by a densitometric analysis. In slices of the rat cerebral cortex, a pronounced fodrin breakdown was observed under hypoxic and hypoglycemic conditions. The enhancement of fodrin breakdown was completely blocked by omission of extracellular Ca2+ and significantly inhibited by calpain inhibitors such as E-64 and calpain inhibitor-I, thereby suggesting that the fodrin breakdown induced by hypoxia/hypoglycemia is due to the activation of Ca2+-stimulated neutral protease calpain. NS-7 (1-30 microM) produced a concentration-dependent inhibition of hypoxia/hypoglycemia-induced fodrin breakdown. In rats with unilateral middle cerebral artery occlusion (MCAO), a pronounced fodrin breakdown was observed in the cerebral cortex and striatum, although the time course for the development of the fodrin breakdown was much slower in the cerebral cortex than in the striatum. NS-7 (0.5 mg/kg i.v.), when injected immediately after MCAO, suppressed not only the fodrin breakdown but also the infarction in the cerebral cortex. From these results it is suggested that inhibition of calpain activation is implicated in the neuroprotective action of NS-7.

Blockade of voltage-sensitive sodium channels by NS-7, a novel neuroprotective compound, in the rat brain

The effects of 4-(4-fluorophenyl)-2-methyl-6-(5-piperidinopentyloxy) pyrimidine hydrochloride (NS-7), a novel neuroprotective compound, on the voltage-sensitive sodium channels (VSSC) were examined in the rat brain and cardiac myocytes. NS-7 inhibited [3H]batrachotoxinin A 20 alpha-benzoate (BTX) binding (neurotoxin receptor site 2) in brain membranes with a Ki value of 1 microM, while the compound was less effective in the cardiac myocytes (Ki = 13 microM). Aconitine, on the other hand, inhibited [3H]BTX binding to brain membranes and cardiac myocytes with the same potency. In contrast. NS-7 had no affinity for [3H]saxitoxin binding in brain (neurotoxin receptor site 1). In superfused slices of the rat cerebral cortex, NS-7 inhibited the veratridine (5 microM)-evoked glutamate release in a concentration-dependent manner, the IC50 value of which was 7.7 microM, whereas the compound showed a weak and not significant suppression of KCl-evoked glutamate release. The tissue concentrations of NS-7 in the rat cerebral cortex and heart were 89 and 28 nmole/g tissue, respectively, 5 min after its intravenous injection (8 mg/kg). Furthermore, in the cerebral cortex, NS-7 distributed preferentially to the membrane-enriched synaptosomal fraction. Since neurotoxin receptor site 2 is located in the transmembrane region of the VSSC moiety, the channel function may be substantially inhibited by a peripheral administration of NS-7. These results suggest that the blockade of neurotoxin receptor site 2 of VSSC in the brain contributes to the neuroprotective action of NS-7.

Cardiac electrophysiological actions of NS-21 and its active metabolite, RCC-36, compared with terodiline

Terodiline, an anticholinergic drug with a Ca2+ blocking action, is thought to be associated with torsade de pointes, a serious ventricular tachycardia. NS-21 is a newly developed drug for the treatment of urinary frequency and urinary incontinence and it has pharmacological properties similar to those of terodiline. It remains unknown, however, whether NS-21 and its active metabolite, RCC-36, have any proarrhythmic activity. The electrophysiological properties of NS-21 and RCC-36 were examined in guinea pig ventricular myocytes and were compared with those of terodiline using the whole-cell patch-clamp technique. NS-21, RCC-36 and terodiline inhibited L-type Ca2+ currents in a concentration-dependent manner with IC50 values of 27.0, 27.0 and 33.5 microM, respectively. At a concentration of 10 microM, terodiline inhibited both the time-dependent current and the tail current of the delayed rectifier K+ current, with the latter being significantly inhibited at voltages more positive than +10 mV. In contrast, NS-21 and RCC-36 had almost no effect on either of these currents. Terodiline also inhibited the inward rectifier K+ current significantly at voltages more negative than -100 mV, whereas NS-21 and RCC-36 had little effect. If the proarrhythmic activity of terodiline resulted primarily from the combined inhibition of K+ and Ca2+ currents, one might expect that NS-21 and RCC-36, which inhibit L-type Ca2+ currents without affecting either the delayed rectifier K+ current or the inward rectifier K+ current, would not share the proarrhythmic activities of terodiline.

Inhibitory effects of NS-21, a novel drug for urinary incontinence, and its active metabolite, RCC-36, on L-type calcium currents in isolated guinea pig detrusor smooth muscle cells

The inhibitory effects of NS-21, a newly developed drug for the treatment of urinary frequency and urinary incontinence, and its active metabolite, RCC-36, on L-type Ca2+ currents (ICa) in guinea pig detrusor smooth muscle cells have been compared to those of terodiline by a whole-cell patch-clamp technique. Like terodiline (10 microM), both NS-21 (10 microM) and RCC-36 (10 microM) induced a sizeable decrease in ICa elicited from a holding potential of -60 mV without changing the current-voltage relationship. The three drugs shifted the inactivation curves for ICa in the hyperpolarizing direction by 13 to 20 mV but had no effect on the activation curves for ICa resulting in a decrease in the calcium window current. The inhibitory effects of NS-21 and RCC-36 were greater than those of terodiline. The three drugs inhibited ICa in a concentration- and holding-potential-dependent manner. The IC50 values at a holding potential of -60 mV were 7.9 microM for NS-21, 6.4 microM for RCC-36, and 5.9 microM for terodiline, and at -40 mV they were 1.3, 1.2, and 3.5 microM, respectively. The ratio calculated by dividing the IC50 value at -60 mV by the value at -40 mV was 6.1, 5.3 and 1.7, respectively, indicating that the inhibitory effects of NS-21 and RCC-36 on ICa were more sensitive to voltage than those of terodiline. These results suggest that NS-21 and RCC-36 could be more effective in the treatment of urinary bladder ailments, such as urinary frequency and urinary incontinence.

Involvement of metabotropic glutamate receptors in Gi- and Gs-dependent modulation of adenylate cyclase activity induced by a novel cognition enhancer NS-105 in rat brain

The effect of a novel cognition enhancer [(+)-5-oxo-D-prolinepiperidinamide monohydrate] (NS-105) on cAMP formation was investigated in both slices and membranes of the rat cerebral cortex. NS-105 (10(-8)-10(-6) M) inhibited forskolin-stimulated cAMP formation in membranes, however, the compound significantly enhanced the cAMP formation in pertussis toxin-pre-treated membranes, an action that was abolished by cholera toxin. In contrast, in digitonin-permeabilized membranes, NS-105 had no influence on Mn2+-stimulated cAMP formation. Both of the inhibitory and facilitatory actions of NS-105 on cAMP formation were mimicked by a metabotropic glutamate receptor (mGluR) agonist (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid (1S,3R-ACPD) and an adrenergic alpha2 agonist UK-14,304, and blocked by a mGluR antagonist 2-amino-3-phosphonopropanoate but not by an alpha2 antagonist yohimbine. In cortical slices, NS-105 (10(-8)-10(-7) M) inhibited forskolin-stimulated cAMP accumulation but enhanced isoproterenol-stimulated cAMP accumulation, as did by a GABA(B) agonist (-)baclofen. On the other hand, (-)baclofen, while it significantly inhibited cAMP accumulation in slices, did no longer inhibit cAMP accumulation, when treated with NS-105 (10(-8)-10(-5) M). Similarly, (-)baclofen-induced inhibition of the cAMP accumulation was reversed by 1S,3R-ACPD and UK-14,304. NS-105 (10(-6)) increased [35S]GTPgammaS binding in the intact but not digitonin-permeabilized cortical membranes, as produced by UK-14,304, although the compound (10(-9)-10(-3) M) had no influence on various neurotransmitter receptor bindings, including alpha2 receptors. These results suggest that NS-105 modulates adenylate cyclase activity by stimulating mGluRs which might coupled to both Gi/Go and Gs.

Effect of the anticholinergic drug with calcium antagonistic activity, (+/-)-4-diethylamino-1,1-dimethylbut-2-yn-1-yl 2-cyclohexyl-2-hydroxy-2-phenylacetate monohydrochloride monohydrate, on lower urinary tract function in rhesus monkeys

NS-21 ((+/-)-4-diethylamino-1,1-dimethylbut-2-yn-1-yl 2-cyclohexyl-2-hydroxy-2-phenylacetate monohydrochloride monohydrate, CAS 129927-33-4) and its active metabolite, RCC-36 ((+/-)-4-ethylamino-1,1-dimethylbut-2-yn-1-yl 2-cyclohexyl-2-hydroxy-2-phenylacetate monohydrochloride), have both anticholinergic and calcium antagonistic activities. NS-21 is under development for the treatment of bladder dysfunction. This study was designed to compare the effects of NS-21 and RCC-36 on the bladder function of monkeys with the effects of various reference drugs. Male rhesus monkeys were anesthetized with a mixture of enflurane and nitrous oxide, a transurethral catheter was inserted into the urinary bladder from the external urethral orifice, and cystometrograms were recorded. Drugs were administered intravenously. NS-21 at doses of 0.3 and 1 mg/kg caused an increase in bladder capacity without affecting the micturition pressure. RCC-36 also caused an increase in bladder capacity, but it was accompanied by a significant decrease in micturition pressure. Oxybutynin, atropine and verapamil all caused decreases in micturition pressure at doses which caused an increase in bladder capacity. Of the drugs examined, only NS-21 caused an increase in the bladder capacity of rhesus monkeys without affecting the micturition pressure. This drug is therefore a promising candidate for the clinical treatment of pollakiuria and urinary incontinence.

Effect of the anticholinergic drug with calcium antagonistic activity, (+/-)-4-diethylamino-1,1-dimethylbut-2-yn-1-yl 2-cyclohexyl-2-hydroxy-2-phenylacetate monohydrochloride monohydrate, on lower urinary tract function in decerebrated dogs

NS-21 ((+/-)-4-diethylamino-1,1-dimethylbut-2-yn-1-yl 2-cyclohexyl-2-hydroxy-2-phenylacetate monohydrochloride monohydrate, CAS 129927-33-4) is a novel compound designed for the treatment of bladder dysfunction. The effects of NS-21 and its active metabolite, RCC-36 ((+/-)-4-ethylamino-1,1-dimethylbut-2-yn-1-yl 2-cyclohexyl-2-hydroxy-2-phenylacetate monohydrochloride), on the urodynamics of decerebrated dogs are reported. Dogs were decerebrated at the precollicular-postmamillary level and the urodynamic effects of intravenously administered NS-21, RCC-36, and various reference drugs were compared by cystometry. NS-21 (0.3-1 mg/kg) and RCC-36 (0.1 mg/kg) caused an increase in bladder capacity without affecting the micturition pressure or residual volume, and thus caused a significant increase in functional bladder capacity. Oxybutynin caused a dose-dependent increase in bladder capacity at 0.1 mg/ kg and higher doses; however, the associated decrease in micturition pressure resulted in a significant increase in residual volume and a decrease in functional bladder capacity. These effects of oxybutynin were similar to those of atropine. Propiverine (0.1-10 mg/kg) and terodiline (0.1-10 mg/kg) caused no significant increase in bladder capacity. In conclusion, in decerebrated dogs, NS-21 and RCC-36 increased the bladder capacity without increasing the residual volume. NS-21 thus had more favorable therapeutic effects than any of the reference drugs tested and is therefore a promising candidate drug for the treatment of pollakiuria and urinary incontinence.

NS-49, an alpha 1A-adrenoceptor agonist, selectively increases intraurethral pressure in dogs

The effects of NS-49 ((R)-(-)-3'-(2-amino-1-hydroxyethyl)-4'-fluoromethane sulfonanilide hydrochloride), an alpha 1A-adrenoceptor-selective agonist, on intraurethral pressure and blood pressure were investigated in anesthetized dogs. In addition, the contractile effects of NS-49 on the isolated dog urethra and carotid artery were compared with those of non-selective alpha 1-adrenoceptor agonists. Intravenously (i.v.) administered NS-49 at 0.3 microgram/kg or more significantly increased intraurethral pressure in a dose-dependent manner. Much higher doses of NS-49 were needed to increase blood pressure. In contrast, ST-1059 (1-(2',5'-dimethoxyphenyl)-2-aminoethanol) (an active metabolite of midodrine) at 30 micrograms/kg or more significantly increased both intraurethral pressure and blood pressure. NS-49 was 11-fold more selective for intraurethral pressure than ST-1059, NS-49, ST-1059, phenylephrine and noradrenaline caused concentration-dependent contraction of the isolated dog urethra. NS-49 caused only a slight contraction of the dog carotid artery even at high concentrations, whereas the reference drugs caused contractions of the artery with high efficacy. The alpha 1A-adrenoceptor-selective antagonists 5-methyl-urapidil and WB-4101 also showed high affinity for alpha 1-adrenoceptors in the dog urethra in inhibiting [3H]prazosin binding. In conclusion, the alpha 1A-selective agonist NS-49 selectively increased intraurethral pressure in dogs, and produced selective contraction of the dog urethra. These results suggest that the alpha 1A-adrenoceptor subtype is responsible for the contraction of the urethra and the regulation of intraurethral pressure, and that NS-49 might be useful for the treatment of stress incontinence with little effect on the cardiovascular system.

CNS-mediated influence of TRH and its analog, NS-3, on the function of the rabbit lower urinary tract

The effects of thyrotropin-releasing hormone (TRH) and its new analog, NS-3 (montireline), on the lower urinary tract in rabbits were investigated. TRH and NS-3 elicited transient increases in intravesical pressure and micturition. They also caused long-lasting increases in intraurethral pressure and EMG activity of the external urethral sphincter, which were not affected by prazosin or transection of the hypogastric nerve, but were eliminated by transection of the pudendal nerve. In animals decerebrated at the supracollicular post-mammillary level, these drugs did not increase intravesical pressure or micturition, but they did elicit increases in intraurethral pressure and sphincter EMG activity. No binding sites for TRH were found in the lower urinary tract. These findings suggest that the sites of action of TRH and NS-3 which elicit intravesical pressure increase or micturition might be located in the area rostral to the pons, and that the sites of action which elicit increases in intraurethral pressure and sphincter EMG activity might be located caudal to the rostral pons.

[EEG studies on the analeptic effect of montirelin hydrate (NS-3), a TRH analog, in posterior hypothalamic area-lesioned rats]

Effects of a novel TRH analog, montirelin hydrate (NS-3), on the EEG were compared with those of TRH in intact and posterior hypothalamic area (PHA)-lesioned rats. In the intact rats, NS-3 at 0.01 mg/kg and TRH at 1 mg/kg produced no changes in the sleep-waking cycle. NS-3 at 0.1 mg/kg caused an increase in the time spent in the arousal stage and delayed the onset of the slow wave sleep (SS). On the other hand, TRH at 10 mg/kg increased the time spent in the SS stage and decreased the time in the A1 stage during 2 to 4 hr after injection without increasing the arousal stage, although it delayed the onset of SS. No abnormal EEG was observed after NS-3 or TRH administration in the intact rats. Electrolytic ablation of the PHA elicited continuous behavioral resting and caused increases in the slow-wave components in the cortical EEG and loss of generation of the hippocampal rhythmic slow activity. NS-3 at 0.01 mg/kg and TRH at 1 mg/kg caused the reappearance of the hippocampal rhythmic slow activity. In addition, NS-3 at 0.1 mg/kg and TRH at 10 mg/kg decreased the slow-wave components and increased the fast-wave components in the cortical EEG. In conclusion, NS-3 showed a distinct analeptic effect with a 100-fold higher potency than that of TRH in both the intact and PHA-lesioned rats.

Brain pertussis toxin-sensitive G proteins are involved in the flavoxate hydrochloride-induced suppression of the micturition reflex in rats

The effect of flavoxate hydrochloride (flavoxate), an anti-pollakiurea agent, on cyclic AMP (cAMP) formation was investigated in the rat brain and a possible involvement of brain G proteins in the action of flavoxate on the bladder function was subsequently examined. Flavoxate (10(-8)-10(-5) M) inhibited cAMP formation in a concentration-dependent manner, an action which was completely abolished by pretreating the membranes with pertussis toxin (PTX). The inhibitory effect of flavoxate was also completely antagonized by combined treatment with any two antagonists for adenosine A1 (8-cyclopentyl-1,3-dipropylxanthine), dopamine D2 (sulpiride) or adrenergic alpha 2 (yohimbine) receptors, although each antagonist alone did not significantly block the flavoxate-induced inhibition of cAMP formation. Radioligand binding studies indicated that flavoxate at micro- or submicromolar concentrations has affinity for Gi-coupled receptors such as A1, D2 and alpha 2 receptors. Therefore, flavoxate may inhibit cAMP formation by the stimulation of A1, D2 and alpha 2 receptors. To clarify the involvement of brain Gi proteins in the flavoxate-induced inhibition of the micturition reflex, the effect of pretreatment with PTX (i.c.v.) on the flavoxate-induced inhibition of isovolumetric rhythmic bladder contractions was examined in rats. Flavoxate (3 mg/kg, i.v.) completely abolished rhythmic bladder contractions in vehicle-pretreated rats, but not in PTX-pretreated rats. These findings suggest that signal transduction via Gi-coupled receptors is involved, at least in part, in the inhibition of the micturition reflex by flavoxate in rats. These results also provide the first evidence suggesting a negative role of brain PTX-sensitive G proteins in the micturition reflex.

[Montirelin hydrate (NS-3), a TRH analog, improved disturbance of consciousness in cats: electroencephalographical studies]

Central effects of montirelin hydrate (NS-3) were electroencephalographically investigated in cats with experimentally induced disturbance of consciousness. All experiments were conducted under the gallamine-immobilized and artificially ventilated acute experimental condition. NS-3 and TRH produced EEG activation in cats with lesions in the midbrain reticular formation in a dose-dependent manner. Similar effects were observed in cats with bilateral lesions of the posterior hypothalamic area. These effects of NS-3 were 30 to 100 times more potent than those of TRH. NS-3 at doses higher than 0.003 mg/kg restored the suppressed EEG dose-dependently in cats with cerebral ischemia produced by clamping the bilateral common carotid arteries and basilar artery. TRH showed no effect at a dose of 10 mg/kg. These results indicate that NS-3 might be an effective drug for treating the disturbance of consciousness.

Enhancement of brain noradrenaline and dopamine turnover by thyrotropin-releasing hormone and its analogue NS-3 in mice and rats

The effects of intravenous injections of thyrotropin-releasing hormone and its analog NS-3 (montirelin hydrate, CG3703) on the dynamics of brain monoamines were examined in mice and rats. In mice, both NS-3 (0.1-1 mg/kg) and thyrotropin-releasing hormone (10 and 30 mg/kg) increased the concentrations of 4-hydroxy-3-methoxyphenylglycol, 3,4-dihydroxyphenylacetic acid and homovanillic acid. The turnover rates, estimated either by depletion of catecholamines after treatment with alpha-methyl-p-tyrosine or by probenecid-induced accumulation of homovanillic acid, were enhanced by these peptides. In contrast, none of the compounds had any influence on the serotonin turnover. In rats, both NS-3 and thyrotropin-releasing hormone produced a regionally specific increase in the concentrations of the catecholamine metabolites. A microdialysis study demonstrated that NS-3 significantly increased the release of dopamine in the nucleus accumbens as well as the striatum of conscious rats, while thyrotropin-releasing hormone caused a weak but significant enhancement of dopamine release only in the nucleus accumbens. These findings indicate that NS-3 was far more potent than thyrotropin-releasing hormone in facilitating the turnover of catecholamines without affecting serotonin turnover in the mouse and rat brain.

Mechanisms of the suppression of the bladder activity by flavoxate

BACKGROUND

This study was designed to clarify the primary site of action of flavoxate, clinically used for the treatment of urinary frequency.

METHODS

In rats, the effect of flavoxate on contractile responses in isolated detrusor strips, bladder contraction induced by pelvic nerve stimulation, isovolumetric rhythmic bladder contractions, and pelvic nerve activity were examined. In decerebrated cats, flavoxate was microinjected into the nuclei in the pons, and its effect on reflex micturition was observed.

RESULTS

Flavoxate suppressed carbachol- and calcium ion (Ca2+)-induced contractions of isolated detrusor strips in a noncompetitive and a competitive manner, respectively. Intravenous flavoxate suppressed both initial phasic, and later tonic, bladder contractions induced by electrical stimulation of the distal end of the pelvic nerve. It abolished isovolumetric rhythmic bladder contractions and the associated efferent pelvic nerve activity, without affecting baseline vesical pressure and afferent pelvic nerve activity. When administered intracerebroventricularly or intrathecally, it abolished isovolumetric rhythmic bladder contractions. Flavoxate microinjected into the nucleus reticularis pontis oralis (PoO; pontine micturition inhibitory region) of decerebrated cats inhibited the reflex micturition, but had no effect when microinjected into the locus coeruleus alpha (pontine micturition center) or locus subcoeruleus (pontine urine storage center).

CONCLUSIONS

Flavoxate suppressed the micturition reflex primarily by facilitating the inhibitory action of the PoO on the descending pathways from the pontine micturition center to the sacral parasympathetic intermediolateral nuclei.

[Montirelin hydrate (NS-3), a TRH analog, improved the disturbance of consciousness caused by head concussion and pentobarbital in mice]

Effects of a novel TRH analog, montirelin hydrate (NS-3), on the coma caused by head concussion and narcosis induced by pentobarbital were compared with those of TRH in mice. Head concussion caused a behavioral comatose state with loss of the righting reflex and spontaneous motor activity. NS-3 shortened the latent periods to the recovery of the righting reflex (0.03-0.1 mg/kg, i.v.) and spontaneous motor activity (0.1 mg/kg, i.v.) following the head concussion. In the case of TRH, higher doses were needed to induce such effects. NS-3 (0.1-0.3 mg/kg, i.v.) reversed the pentobarbital-induced narcosis in a dose-dependent manner. A similar effect was elicited by 30- to 100-fold higher doses of TRH than NS-3. The analeptic effect of NS-3 in the pentobarbital-narcotized mice was antagonized by SCH23390, a dopamine D1 antagonist or by the combined treatment with prazosin and scopolamine, while neither prazosin nor scopolamine alone antagonized the analeptic effect of NS-3. Taken together with the finding that NS-3 did not bind to dopamine, adrenaline or muscarine receptors, it is suggested that NS-3 may restore the disturbance of consciousness by activating the brain dopamine, noradrenaline and acetylcholine neurons without stimulating these receptors directly.

Protein kinases are involved in prolonged acetylcholine release from rat hippocampus induced by thyrotropin-releasing hormone analogue NS-3

The effects of various protein kinase inhibitors on acetylcholine release from the rat hippocampus induced by the local application of NS-3 (montirelin hydrate, CG-3703), a thyrotropin-releasing hormone analogue, into the medial septum-diagonal band were examined using in vivo microdialysis. Perfusion of NS-3 (1 microM) into the medial septum-diagonal band for 20 min produced a pronounced and prolonged increase in the hippocampal acetylcholine efflux. Pretreatment of the medial septum-diagonal band with either K-252a, a nonselective protein kinase inhibitor, or selective protein kinase A inhibitor H-89 almost completely blocked the acetylcholine efflux evoked by NS-3, and selective protein kinase C inhibitor calphostin C inhibited the action of NS-3. On the other hand, NS-3 (0.1-10 microM) or TRH (1-100 microM) increased the cyclic AMP efflux from the medial septum-diagonal band in a concentration-dependent manner, as measured by microdialysis. These findings suggest that protein kinases A and C in the neurons of the medial septum-diagonal band are involved in the mechanism of the prolonged stimulation of acetylcholine release from the hippocampus induced by thyrotropin-releasing hormone and its analogue, NS-3.

NS-3, a TRH-analog, reverses memory disruption by stimulating cholinergic and noradrenergic systems

The effects of a TRH-analog, N[[(3R,6R)-6-methyl-5-oxo-3-thiomorpholinyl]carbonyl]-L-histidyl-L - prolinamide tetrahydrate (NS-3, CG3703, montirelin hydrate) were compared with those of physostigmine on learning and memory disruption in the passive avoidance response (PAR) induced by either electrolytic lesion of the nucleus basalis magnocellularis (NBM) or by treatment with the noradrenergic neurotoxin, N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP4) in rats. a) In NBM-lesioned rats, both NS-3 and physostigmine significantly reversed disruption of memory consolidation examined 15 min after the training session when these drugs were injected IP immediately after the training session. In addition, reversal by NS-3 (0.1 mg/kg) of the disruption of memory was observed even in the retention test conducted 24 h after the training session. b) NS-3 (0.5 mg/kg) significantly reversed the disruption of memory retrieval, when the drug was administered 15 min before the test session. c) DSP4 (50 mg/kg IP) caused memory disruption when the retention tests were conducted between 1 and 48 h after the acquisition session. NS-3 (0.1 mg/kg), but not physostigmine, significantly reversed the disruption of memory induced by DSP4 treatment. These findings suggest that the consistent antiamnestic action of NS-3 is due to the enhancement of both central cholinergic and noradrenergic systems, possibly via facilitation of the release of these transmitters.

[The effect of lactitol (NS-4) on the concentrations of ammonia and amino acids in blood and cerebrospinal fluid in Eck fistula (portacaval-shunted) dogs]

Lactitol and lactulose were compared in their effect on the concentrations of ammonia and amino acids in blood and cerebrospinal fluid (CSF) in Eck fistula dogs. Drugs were administered intragastrically for four weeks from three weeks after the portacaval-shunt operation. The concentration of ammonia in the blood and CSF had increased three- to five-fold three weeks after the operation and increased gradually thereafter. Eck fistula dogs showed a characteristic profile of plasma amino acids, with increased concentrations of tryptophan (Trp) and aromatic amino acids (AAA) and reduced concentrations of branched-chain amino acids. The profile of CSF amino acids revealed substantial increases in the concentrations of AAA as well as glutamine (Gln), Trp and glutamic acid. Lactitol at doses of 1 and 3 g/kg/day significantly decreased the ammonia concentration in both the blood and CSF after administration for two and four weeks. Lactitol at a dose of 3 g/kg/day significantly decreased the concentration of Trp in the plasma and the concentrations of valine, leucine, AAA and Gln in CSF. Lactulose showed effects similar to those of lactitol. These findings suggest that lactitol may be a promising agent for the clinical treatment of hyperammonemia and hepatic encephalopathy, since it decreased the concentration of ammonia in the blood and CSF and the elevated concentrations of AAA in CSF associated with the development of hepatic encephalopathy.

Mechanism for lowering blood ammonia levels by lactitol

Lactitol has been reported to decrease the blood ammonia concentration in various experimental hyperammonemia models such as portacaval shunted rats. The mechanism responsible for this lowering of blood ammonia levels was investigated in rats. When lactitol was given orally twice a day for 7 days at doses of 3 and 10 g/kg/day and at half that daily dose on day 8, it significantly decreased the ammonium concentration of the portal blood by 27.3-43.2%, cecal ammonia contents by 49.2-57.6% and the pH of the cecal contents from 6.52 to 5.92-5.54, 4 hr after the final administration. Lactitol also inhibited increases in the portal ammonia concentration induced by the intracecal administration of ammonium acetate (300 mg/kg) 4 hr after the final administration. When lactitol was given orally at bolus doses of 1 and 3 g/kg simultaneously with a charcoal meal, lactitol significantly facilitated small intestinal transit by 12-13%. At a bolus dose of 3 g/kg, given 1 hr before the administration of a charcoal meal into the proximal colon, lactitol significantly facilitated colonic transit by 29.5%. These effects of lactitol were similar to those of lactulose. These findings suggest that lactitol decreases blood ammonia concentration by inhibiting both the production and the absorption of ammonia through reducing intestinal pH and shortening the residence time of intestinal contents in the intestinal tract.

[Effect of lactitol (NS-4) on the increase in blood and brain ammonia concentration and on coma in newly developed rat models of hepatic coma]

Encephalopathy caused by hepatic cirrhosis is often associated with portasystemic shunt and hepatic parenchymal injury. Together, these are known as a combined-type symptom. Two experimental hepatic comatose models with combined-type symptom were developed in rats. Both of these models involve the administration of ammonium acetate (500 mg/kg) into the cecum in portacaval shunted (PCS) rats. In addition, hepatic injury was induced in one model by carbontetrachloride (CCl4) and in the other by dimethylnitrosamine (DMNA). These model rats showed a higher increase in the concentration of ammonia in the blood and a higher incidence of coma as determined by the loss of the righting reflex than did rats subjected to a shunt only (PCS operation + ammonia loading) or hepatic parenchymal injury only (CCl4 treatment + ammonia loading). The effect of lactitol, administered orally for 7.5 days, on the experimental hepatic coma was compared with that of lactulose. Lactitol significantly inhibited the increase in blood and brain ammonia concentration at doses of 3 and 6 g/kg/day and also reduced the incidence of coma. The effects of lactitol were similar to those of lactulose, a therapeutic agent for hepatic encephalopathy. Therefore, lactitol should be useful in the clinical treatment of hyperammonemia or hepatic encephalopathy.

Effect of glycosidase inhibitors on the biosynthesis of alpha 2-plasmin inhibitor and antithrombin III in Hep G2 cells

We studied the effect of the glucosidase I inhibitor, N-methyl-1-deoxynojirimycin (MdN) and the mannosidase inhibitor, 1-deoxymannojirimycin (dMM) on the biosynthesis and secretion of alpha 2-plasmin inhibitor (alpha 2-PI) and antithrombin III (ATIII) in cultures of human hepatoma (Hep-G2) cells. Incubation with 1 mM MdN decreased secreted alpha 2-PI activity and antigen levels by about 40%, whereas those of ATIII were not affected. Neither inhibitor affected the messenger RNA levels as determined by Northern blotting. Pulse-chase studies using [35S]-methionine showed that MdN decreased alpha 2-PI and ATIII secretion rates. By the 18 h chase, MdN had decreased secreted alpha 2-PI to 50-60%, with little effect on ATIII. Intracellular forms of alpha 2-PI or ATIII synthesized by cells treated with 1 mM MdN were sensitive to endoglycosidase H (Endo H), whereas almost all the secreted forms were resistant, suggesting the presence of complex-type oligosaccharides. In the presence of 1 mM dMM, cells synthesized Endo H-sensitive alpha 2-PI and ATIII with similar secretion rates. These results suggest that retention of glucose on N-linked oligosaccharides not only retards the exit of alpha 2-PI and ATIII, but also changes the catabolic rate of alpha 2-PI in the endoplasmic reticulum.

Response of plasma tissue factor pathway inhibitor to diet-induced hypercholesterolemia in crab-eating monkeys

Tissue factor pathway inhibitor (TFPI), a protease inhibitor associated with lipoproteins in plasma and endothelial cells, can inhibit the initial reactions of the tissue factor-mediated coagulation pathway. A positive relationship between TFPI and cholesterol has been demonstrated in human plasma. To investigate this relation in more detail, in the present study we measured TFPI in the plasma of monkeys on a high-cholesterol diet. After diet treatment, cholesterol levels and TFPI activity were increased 3- and 1.5-fold, respectively. Three forms of TFPI, low-density lipoprotein (LDL)/very-low-density lipoprotein (VLDL)-associated TFPI, high-density lipoprotein (HDL)-associated TFPI, and free TFPI, were measured after gel filtration of plasma. In hypercholesterolemic monkeys, levels of TFPI activity and antigen in the LDL/VLDL fraction were increased to about three times those of normal monkeys. Changes in HDL-associated TFPI and free TFPI were not significant compared with the change in LDL/VLDL-associated TFPI. After the monkeys received heparin infusions TFPI was increased about fivefold, but there was no significant difference in these increases between normal and hypercholesterolemic monkeys. The increase in TFPI after heparin infusion is discussed in terms of the relationship between lipoprotein-associated TFPI in plasma and endothelial cell-associated TFPI.

An animal model of coronary thrombosis and thrombolysis--comparisons of vascular damage and thrombus formation in the coronary and femoral arteries after balloon angioplasty

The purpose of this study was to compare vascular damage and thrombus formation in the coronary and femoral arteries after balloon angioplasty, and to develop a physiological animal model of intracoronary occlusive thrombus using the balloon angioplasty technique. Angioplasty of the left anterior descending coronary arteries of 14 dogs was performed with an oversized balloon catheter at a high inflation pressure (150 PSI). This was followed angiographically (PTCA protocol). Dogs that showed arterial occlusion were divided into 2 groups. The dogs in 1 group were killed with an overdose of sodium pentobarbital, and those in the other group were infused with a tissue-type plasminogen activator (t-PA; 300,000 unit/kg). Angioplasty of the femoral and profunda femoris arteries (n = 5) was performed in 5 other dogs (PTA protocol). All of the animals were eventually sacrificed and tissue preparations were made from all 3 types of arteries. In the PTCA protocol, acute arterial occlusion was seen angiographically within 2 h in 10 of the 14 dogs. A histological study of the acutely occluded arteries (n = 5) showed thrombotic occlusion and severe arterial damage with medial tearing. T-PA was infused to 5 of the dogs with acute occlusion, and all showed reperfusion. A histological study of these animals showed severe arterial damage, but no macroscopic thrombus. In 4 dogs without acute occlusion, none of the 10 arteries examined were acutely occluded. In the PTA protocol, none of the 10 arteries were acutely occluded. A histological study showed fewer thrombi and less severe arterial damage.(ABSTRACT TRUNCATED AT 250 WORDS)

Diet-induced atherosclerosis in cynomolgus monkey aorta and regression by the sixth-month observation

Pathomorphologic analysis was employed to evaluate diet-induced atherosclerosis in cynomolgus monkey aorta and regression by administration of a hypolipidemic agent for six months after the atherogenic ration. Twenty-seven male cynomolgus monkeys were divided into three groups. Group A was fed individually with a high-fat diet containing 0.3% cholesterol under identical conditions for six months. Group B was fed with normal monkey chow for six months after the same atherogenic ration. Group C was fed with normal monkey chow and administered a hypolipidemic agent 1% of 4-[2-(4-isopropylbenzamido)ethoxy] benzonic acid for six months after the same atherogenic ration. Each thoracic and abdominal aorta of animal models was separately analyzed. Lipid composition analysis and esterified cholesterol (CE) in aortic wall, ratio of free cholesterol to phospholipid, surface involvement, and atherosclerotic index after Sudan IV staining were studied for evaluation of progression and regression. The configurations of atherosclerotic involvement were histologically evaluated among each group. These observed lesions, features specific to cynomolgus lesions, mainly consisted of lipid-rich foam cells, lipid debris, and proliferated extracellular matrix. No different lesion composition was noted between the thoracic and abdominal aorta. This may suggest that some local factors play an important role for development of atherosclerosis after the initial event. Group C had remarkable reduction of foam cells and of CE accumulation in both the thoracic and abdominal aortic wall. Accelerated regression in group C as compared with group B was demonstrated both biochemically and pathohistologically. These results suggest that substantial regression of atherosclerosis in both the thoracic and abdominal aorta can be expected. This hypolipidemic agent exerts notable antiatherosclerotic activity, along with a lowering effect on plasma total cholesterol levels.

Detection of Clostridium botulinum in natural sweetening

Various sugar products were examined for contamination with C. botulinum spores. Type A, B and C spores were detected in three of 56 samples of sugar for apiculture, which may attest the significance of bee-feed as a source of contamination of honey. The heavy contamination of honey with C. botulinum spores sometimes encountered, however, can not be explained unless some other factors, e.g., that allowing germination and multiplication of the spores somewhere during honey production, are found. Type A spores were detected in some samples of raw sugar and molasses and also in two of 41 samples of brown sugar lump, but not in refined sugar or other various samples taken at a sugar factory or in sugar cane left on the field in Okinawa. The fact that some natural sweetenings are contaminated with C. botulinum spores, even in low concentrations, may be food-hygienically important.

New hypocholesterolemic abietamide derivatives. II. Synthesis and hypocholesterolemic activity of N-phenyl-delta 8-dihydroabietamides

A series of N-phenyl-delta 8-dihydroabietamide analogs were prepared and tested for hypocholesterolemic activity. The effects of substituents of the phenyl moiety on the activities were quantitatively analyzed by using various substituent parameters. The activities were enhanced by the electron-donating effect of ortho and para substitutents and the bulkiness of ortho substituents. A combination of 2,6-dimethylaniline with resin acids other than delta 8-dihydroabietic acid produced lower activities than N-(2,6-dimethylphenyl)-delta 8-dihydroabietamide, abietane-type carboxamides being somewhat stronger than pimarane-type carboxamides. The conversion of the carboxamide group to other groups resulted in more or less of a decrease in activity, giving evidence that the carboxamide group is important to hypocholesterolemic activity.

Synthesis and alpha-glucosidase-inhibiting activity of a new alpha-glucosidase inhibitor, 4-O-alpha-D-glucopyranosylmoranoline and its N-substituted derivatives

Various N-substituted derivatives of 4-O-alpha-D-glucopyranosylmoranoline have been synthesized, and their inhibitory activities against rabbit sucrase and maltase have been measured, as well as their effects on postprandial hyperglycemia in the sucrose-loaded rat, 4-O-alpha-D-Glucopyranosylmoranoline was also shown to have potent hypoglycemic activity in starch-loaded dogs.

Hypolipidemic effect of NS-1 and other related drugs in rhesus monkeys

NS-1, 4-[2-(4-isopropylbenzamido)ethoxy]benzoic acid, is a novel chemical compound which has been found to be a potent hypolipidemic agent in rhesus monkeys. Significant reductions in serum cholesterol and phospholipids were observed in normolipidemic monkeys following oral doses of 30-300 mg/kg/day. A dose of 300 mg/kg/day for 28 days lowered serum cholesterol and phospholipid levels by 49% and 41%, respectively. NS-1 was more potent than clofibrate, clinofibrate, simfibrate, bezafibrate, gemfibrozil, nicomol and probucol in hypolipidemic activity in the same model. Lipoprotein analysis showed that NS-1 reduced low density lipoprotein much more than high density lipoprotein. The results suggest that NS-1 may have hypolipidemic activity in hyperlipidemic patients.

Inhibition of intestinal alpha-glucosidase and postprandial hyperglycemia by N-substituted moranoline derivatives

The inhibitory activity of N-substituted derivatives of moranoline (1-deoxynojirimycin) against intestinal alpha-glucosidase and postprandial hyperglycemia was evaluated. None of the N-substituted derivatives studied displayed more potent inhibition of sucrase or maltase from rabbit intestines than the parent compound moranoline. However, unlike the in vitro results, many compounds exhibited more potent hypoglycemic activities than moranoline in sucrose-, or starch-loaded rat models. Alkenyl or aralkenyl derivatives displayed more potent hypoglycemic activities than alkyl or aralkyl derivatives. There was a weak correlation between in vitro and in vivo assay systems found by statistical analysis. It is necessary to evaluate compounds in vivo in order to select the most potent hypoglycemic compound.

Effect of THD-341, a new hypocholesterolemic agent, on experimental atherosclerosis in rabbits

The influence of THD-341, N-(2,6-dimethylphenyl)-delta8-dihydroabietamide, upon the formation and regression of atherosclerosis and on serum and liver lipid levels has been studied. When rabbits were fed a 1% cholesterol diet for 7 weeks, THD-341 added at a dietary level of 0.01% during the last 4 weeks almost completely prevented the formation of atherosclerotic lesions and the elevation of serum and liver cholesterol levels. When the drug was fed for 10 weeks, either in the normal or cholesterol diet, to rabbits with pre-established atherosclerosis induced by cholesterol feeding for 11 weeks, it did not affect the extent or severity of the lesions but inhibited the progression of lipid deposition in the aorta in a group fed the cholesterol diet during the final 10-weeks period. The reduction of serum and liver cholesterol levels was greater in the drug-treated groups than in the normal rabbit chow-fed group.