A Fe(3+)/DNA complex induces an anti-human immunodeficiency virus factor(s) in CD4+ lymphocyte cell lines

Numerous cytokines and chemokines are involved in inflammatory and immune response. Whereas some of them inhibit virus replication in vitro directly or increase the patients' T4-lymphocyte level, others effects are not so clear. Using human immunodeficiency virus (HIV) and cell cultures we have studied the antiviral effect of complexes of salmon DNA with metals and of a new factor(s) (antiviral factor, AVF) induced in cells by the complexes. The Fe3+/DNA complex possessed the highest antiviral activity. It was found that MT-2, MT-4, CEM and Jurkat cells treated with the complexes secreted AVF which inhibited the replication of nine HIV-1 isolates, was noncytotoxic and stimulated cell proliferation. AVF did not inactivate HIV. The molecular mass analysis of AVF showed that its antiviral activity is associated with its fraction of M(r) of 3 K. Reverse transcription-polymerase chain reaction (RT-PCR) analysis of mRNA from MT-4 cells treated with the complexes showed an increase in the the expression of genes for interleukin-1 alpha (IL-1 alpha), tumour necrosis factor alpha (TNF-alpha) and TNF-beta while expression of genes for IL-1-beta, IL-2, IL-4, IL-6, IL-8. IL-10, IL-12; 35p, 40p, IL-13, GMCSF, GSF and RANTES was not detected at all. However, the anti-HIV activity of the cell culture supernatant in vitro cannot be explained by mere presence of the inflammatory substances mentioned above, because they do not possess such activity and their M(r) is higher than that of AVF. Our findings raise the possibility that AVF(s) may be involved in the mechanism of cell resistance against HIV.

Diversity of calcium signaling by metabotropic glutamate receptors

During prolonged application of glutamate (20 min), patterns of increase in intracellular Ca2+ concentration ([Ca2+]i) were studied in HEK-293 cells expressing metabotropic glutamate receptor, mGluR1alpha or mGluR5a. Stimulation of mGluR1alpha induced an increase in [Ca2+]i that consisted of an initial transient peak with a subsequent steady plateau or an oscillatory increase in [Ca2+]i. The transient phase was largely attributed to Ca2+ mobilization from the intracellular Ca2+ stores, but the sustained phase was solely due to Ca2+ influx through the mGluR1alpha receptor-operated Ca2+ channel. Prolonged stimulation of mGluR5a continuously induced [Ca2+]i oscillations through mobilization of Ca2+ from the intracellular Ca2+ stores. Studies on mutant receptors of mGluR1alpha and mGluR5a revealed that the coupling mechanism in the sustained phase of Ca2+ response is determined by oscillatory/non-oscillatory patterns of the initial Ca2+ response but not by the receptor identity. In mGluR1alpha-expressing cells, activation of protein kinase C selectively desensitized the pathway for intracellular Ca2+ mobilization, but the mGluR1alpha-operated Ca2+ channel remained active. In mGluR5a-expressing cells, phosphorylation of mGluR5a by protein kinase C, which accounts for the mechanism of mGluR5a-controlled [Ca2+]i oscillations, might prevent desensitization and result in constant oscillatory mobilization of Ca2+ from intracellular Ca2+ stores. Our results provide a novel concept in which oscillatory/non-oscillatory mobilizations of Ca2+ induce different coupling mechanisms during prolonged stimulation of mGluRs.

In-vitro characterization of YM872, a selective, potent and highly water-soluble alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate receptor antagonist

The in-vitro pharmacological properties of (2,3-dioxo-7-(1H-imidazol-1-yl)-6-nitro-1,2,3,4-tetrahydro-1-quinoxal inyl)-acetic acid monohydrate, YM872, a novel and highly water-soluble alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA)-receptor antagonist were investigated. YM872 is highly water soluble (83 mg mL(-1) in Britton-Robinson buffer) compared with 2,3-dihydroxy-6-nitro-7-sulphamoyl-benzo(F)quinoxaline (NBQX), 6-(1H-imidazol-1-yl)-7-nitro-2,3(1H,4H)-quinoxalinedione hydrochloride (YM90K) or 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX). YM872 potently inhibits [3H]AMPA binding with a Ki (apparent equilibrium dissociation constant) value of 0.096 +/- 0.0024 microM. However, YM872 had very low affinity for other ionotropic glutamate receptors, as measured by competition with [3H]kainate (high-affinity kainate binding site, concentration resulting in half the maximum inhibition (IC50) = 4.6 +/- 0.14 microM), [3H]glutamate (N-methyl-D-aspartate (NMDA) receptor glutamate binding site, IC50 > 100 microM) and [3H]glycine (NMDA receptor glycine-binding site, IC50 > 100 microM). YM872 competitively antagonized kainate-induced currents in Xenopus laevis oocytes which express rat AMPA receptors, with a pA2 value of 6.97 +/- 0.01. In rat hippocampal primary cultures, YM872 blocked a 20-microM AMPA-induced increase of intracellular Ca2+ concentration with an IC50 value of 0.82 +/- 0.031 microM, and blocked 300-microM kainate-induced neurotoxicity with an IC50 value of 1.02 microM. These results show that YM872 is a potent and highly water-soluble AMPA antagonist with great potential for treatment of neurodegenerative disorders such as stroke.

Characterization of cyclothiazide-enhanced kainate excitotoxicity in rat hippocampal cultures

Cyclothiazide has been shown to block desensitization of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA)-preferring receptors and to enhance quisqualate-, AMPA- and kainate-induced neurotoxicity. The pharmacology behind this cyclothiazide-enhanced kainate-induced excitotoxicity was characterized in embryonic rat hippocampal cell cultures. Treatment of cell cultures with a combination of cyclothiazide and kainate for 24 h resulted in excessive neuronal death as measured by the release of lactate dehydrogenase into the culture media. Cyclothiazide produced a leftward shift of the kainate dose-response curve and enhanced the maximum response of kainate excitotoxicity. AMPA-preferring receptor antagonists, 2,3-dihydroxy-6-nitro-7-sulphamoyl-benzo(F)quinoxaline(NBQX) and 1-(4-amino-phenyl)-4-methyl-7,8-methylenedioxy-5H-2,3-benzodiazepine (GYKI 52466) blocked cyclothiazide-enhanced kainate toxicity completely, and cyclothiazide increased the IC50S for NBQX and GYKI 52466 against kainate toxicity. The N-methyl-D-aspartate (NMDA) antagonist, (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d] cyclohepten-5,10-imine (MK801) also blocked cyclothiazide-enhanced kainate toxicity, but only partially. Cyclothiazide also increased the IC50 for MK801 against kainate toxicity. These data suggest that cyclothiazide enhances both AMPA-preferring receptor- and NMDA receptor-mediated toxicity in kainate-induced toxicity in embryonic rat hippocampal cultures.

The AMPA-receptor antagonist YM90K reduces AMPA receptor-mediated excitotoxicity in rat hippocampal cultures

The effects of YM90K on alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor-mediated excitotoxicity were investigated using kainate, AMPA and cyclothiazide in rat hippocampal cultures. YM90K had neuroprotective actions against both kainate toxicity and cyclothiazide-enhanced AMPA toxicity. YM90K induced a parallel and rightward shift of both kainate and AMPA dose-response curves. The application of YM90K even 3 hr after the start of kainate exposure significantly reduced kainate toxicity. These results indicate that YM90K protects neurons against AMPA receptor-mediated toxicity at an agonist site on the AMPA receptor and that YM90K protects against AMPA receptor-mediated toxicity even if applied after neurotoxic insult.

Kainate excitotoxicity is mediated by AMPA- but not kainate-preferring receptors in embryonic rat hippocampal cultures

We investigated kainate-induced excitotoxicity in embryonic rat hippocampal cells cultured in a chemically defined medium. Treatment with kainate for 24 h resulted in neuronal death, as assessed by the release of lactate dehydrogenase into the culture media. This neurotoxic effect was kainate dose- and culture age-dependent. EC50 of kainate was 127 +/- 11 microM. 2,3-dihydroxy-6-nitro-7-sulfamoylbenzo (f)quinoxaline (NBQX) completely blocked the toxicity, while MK801, an N-methyl-D-aspartate (NMDA) receptor antagonist, also blocked it but not completely. Furthermore, alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) attenuated the kainate injury, while the selective and noncompetitive AMPA-preferring receptor antagonist 1-(4-aminophenyl)-4-methyl-7, 8-methylenedioxy-5H-2,3-benzo-diazepine (GYKI 52466) blocked it completely. Concanavalin A (ConA), which potentiates the response to kainate at kainate-preferring receptors, had little effect on kainate toxicity. Further, AMPA alone induced little toxicity, but produced remarkable toxicity when cyclothazide was used to block the desensitization of AMPA-preferring receptors. These results indicate that kainate excitotoxicity in hippocampal cultures is mediated by AMPA- but not kainate-preferring receptors, and that it involves NMDA-receptor-mediated toxicity. The non-desensitizing response at AMPA-preferring receptors may play an important role in kainate-induced excitotoxicity.

Control of calcium oscillations by phosphorylation of metabotropic glutamate receptors

Stimulation of two metabotropic glutamate-receptor subtypes, mGluR1 and mGluR5, triggers the release of Ca2+ from intracellular stores through the inositol-(1,4,5) trisphosphate (InsP3) pathway. Here we report that glutamate induces single-peaked intracellular Ca2+ mobilization in mGluR1alpha-transfected cells but elicits Ca2+ oscillations in mGluR5a-transfected cells. The response patterns of the intracellular Ca2+ increase depend upon the identity of a single amino acid, aspartate (at position 854) or threonine (at position 840), located within the G-protein-interacting domains of mGluR1alpha and mGluR5a, respectively. Pharmacological and peptide mapping analyses indicated that phosphorylation of the threonine residue at position 840 of mGluR5a by protein kinase C (PKC) is responsible for the generation of Ca2+ oscillations in mGluR5a-expressing cells. To our knowledge this is the first evidence that PKC phosphorylation of G-protein-coupled receptors is important in producing oscillations in intracellular Ca2+ signalling.

Comparative study of the affinities of the 5-HT3 receptor antagonists, YM060, YM114 (KAE-393), granisetron and ondansetron in rat vagus nerve and cerebral cortex

The 5-HT3 receptor blocking properties of YM060, YM114 (KAE-393), granisetron and ondansetron were examined in the vagus nerve and cerebral cortex of rats. 5-HT and 2-methyl-5-HT induced dose-dependent depolarizations of rat isolated vagus nerve with EC50 values of 2.53 (1.93-3.33) x 10(-6) and 4.03 (2.87-5.66) x 10(-6) M, respectively. YM060, YM114 and granisetron dose-dependently antagonized the depolarization of the rat vagus nerve induced by 5-HT, with decreases in the slope and maximal response at higher concentrations. Apparent pA2 values for these antagonists were 10.27 +/- 0.09, 10.12 +/- 0.16 and 9.44 +/- 0.40, respectively. Ondansetron produced a clear rightward shift of the concentration-response curve to 5-HT. The pA2 value was 8.63 (8.23-9.68). YM060 and YM114 at up to 10(-5) M produced no significant depression of the depolarizing responses to DMPP and GABA. YM060, YM114, granisetron and ondansetron displaced specific binding of [3H]GR65630 to rat cortical membranes with pKi values of 10.48 (10.41-10.57), 10.24 (10.18-10.28), 9.15 (9.02-9.28) and 8.70 (8.64-8.77), respectively. An excellent correlation (r = 0.97) was obtained between pA2 values in the vagus nerve and pKi values in the cerebral cortex. YM060, YM114, granisetron and ondansetron showed low affinities for 5-HT1A, 5-HT2 receptor, adrenergic alpha 1, alpha 2, dopamine D2, muscarinic M2, mu-opioid, benzodiazepine and histamine H1 receptors. These results support the possibility that the same type of 5-HT3 receptor occurs in rat vagus nerve and cerebral cortex.

Developmental alteration of the chromatin state at promoter/replication origin region of the aldolase B locus precedes transcriptional activation in the liver

Liver-specific expression of the rat aldolase B (AldB) gene is conferred by proximal promoter region (-200 bp to + 1 bp), which is centered on an origin region of DNA replication. Transcriptional activation of the gene in the liver occurs during the late one-third of fetal stage. To know the mechanism involved in such activation, we studied developmental changes in chromatin structure and in the extent of CpG methylation in the promoter/origin region of the gene. At an early fetal stage, when the AldB gene in the liver is not yet activated, the gene chromatin had two DNase 1-hypersensitive sites in the promoter region. One corresponded to that typical of AldB-expressing cells in the adult. The other, located approximately 200 bp upstream of the above site, disappeared as the activation of transcription started. A CpG dinucleotide in the promoter/origin region was heavily methylated at an early stage of gestation, but progressively demethylated as the liver develops. This CpG site is located at the center of an important binding site for a transcription factor. These changes occurred early in the fetal stage, prior to the gene activation, and were thus thought to be associated with differentiation of the liver cell or with cessation of cell proliferation.

Initiation zone of DNA replication at the aldolase B locus encompasses transcription promoter region

Aldolase A (AldB) gene is one of the liver-specific genes, which is activated in the fetal stage. As a first step to investigate the functional relationship between transcription and DNA replication, we intended to determine the initiation zone of replication nearest to the AldB gene region. BrdU-labeled nascent DNA was obtained from G1/S arrested hepatoma cells at various times after entering S phase. Hybridization of the newly synthesized, BrdU-labeled DNA with probes corresponding to regions spanning about 26 Kb, revealed that replication zone locates within the AldB gene region. This result, together with the result of hybridization of nascent DNA obtained by alkaline sucrose density-gradient centrifugation, suggested that the initiation zone is located within a more defined region (about 1.0 Kb) containing AldB promoter. In the predicted initiation zone, a purine-rich element which shows high homology to known mammalian origin sequences and other replication components are found. Further, autonomously replicating activity of this initiation zone was examined by DNA transfection. The results showed that the predicted initiation zone confers replication initiation in Cos-1 cells.

Persistence of replicating coxsackievirus B3 in the athymic murine heart is associated with development of myocarditic lesions

Coxsackievirus B3 (CVB3)-induced myocarditis was studied in euthymic (nu/+) and athymic (nu/nu) C3H/HeN (H-2k) mice. Mice were inoculated intraperitoneally with 10(6) p.f.u. of CVB3 (Nancy strain) and sacrificed at intervals up to 92 days post-inoculation (p.i.). Viraemia peaked at day 2 to 3 p.i. and ceased at day 5 to 7 p.i. in a synchronized manner in both sets of mice. Very few infectious particles were detected in the blood of nu/nu mice after day 14 p.i. In nu/nu mice, CVB3 persisted in myocardial tissue with constant titres between 2.7 +/- 1.9 x 10(4) and 7.6 +/- 5.2 x 10(4) p.f.u./mg from day 3 to 92 p.i., which were comparable to those of nu/+ mice in the acute phase. In nu/+ mice, the virus was recovered from all animals examined by day 11 p.i. and from three out of 13 mice between days 14 and 21 p.i., yet no virus was recovered from nu/+ mice at day 42 p.i. In nu/nu mice, sense and antisense RNA for CVB3 was detected in the myocardial tissue up to day 42 p.i. by in situ hybridization and up to day 92 p.i. by reverse transcriptase-PCR. Neither sense nor antisense RNA was detected after day 21 p.i. in nu/+ mice with the same techniques. Myocardial tissue damage was analysed morphologically. At day 92 p.i., the area of myocardial injury peaked at 23% of the section in nu/nu mice. In contrast, less than 0.6% of tissue sections contained lesions in nu/+ mice. A neutralizing antibody response to CVB3 was observed in both nu/nu and nu/+ mice. The mean titre of neutralizing antibody was significantly higher at day 21 p.i. in nu/+ mice, but similar at day 42 p.i. with nu/nu and nu/+ mice. Perforin-producing natural killer-like cells, which are considered to play an important role in causing acute myocarditic lesions in immunocompetent mice, were found in the lesions of nu/nu mice persistently infected with CVB3. Prolonged tumour necrosis factor-alpha mRNA synthesis detected in nu/nu mice appears to reflect the continuous activation of macrophages, which extend phagocytic reactions to virus-infected myocytes. These immunological results suggested that the host immune response devoid of antigen-specific T cell function is not sufficient to terminate CVB3 infection in nu/nu mice. Also, it appears that competent cellular immunity, on the whole, plays a role in curing rather than in aggravating myocarditis in nu+mice.(ABSTRACT TRUNCATED AT 400 WORDS)

Serotonin (5-HT)3-receptor antagonism of 4,5,6,7-tetrahydrobenzimidazole derivatives against 5-HT-induced bradycardia in anesthetized rats

We investigated the mode of the 5-HT3-receptor antagonism of 4,5,6,7-tetrahydrobenzimidazole derivatives, YM060, YM114 (KAE-393), YM-26103-2 and YM-26308-2, against 5-HT-induced transient bradycardia in anesthetized rats. Results were compared with those of ondansetron and granisetron. YM060 (0.03-0.1 microgram/kg, i.v.), YM114 (0.03-0.3 microgram/kg, i.v.), YM-26103-2 (0.01-0.03 microgram/kg, i.v.), YM-26308-2 (0.01-0.03 microgram/kg, i.v.) and granisetron (0.3-3 micrograms/kg, i.v.) displaced the 5-HT dose-response curve to the right, with apparent DR2 values of 0.068, 0.068, 0.019, 0.011 and 0.69 microgram/kg, i.v., respectively. Higher doses of these compounds inhibited 5-HT-induced bradycardia with a reduced maximal response. In contrast, ondansetron displaced the 5-HT dose-response curve to the right without affecting the maximal response. Judged by the apparent DR2 values, YM060, YM114, YM-26103-2 and YM-26308-2 were approximately 13, 13, 50 and 79 times more potent than ondansetron, respectively, whereas granisetron was equipotent to ondansetron. Single i.v. doses of YM060 and granisetron inhibited 5-HT-induced bradycardia significantly longer than ondansetron. Moreover, inhibitory effects of p.o. doses of YM060 (3 micrograms/kg), YM114 (80 micrograms/kg), YM-26103-2 (12 micrograms/kg), YM-26308-2 (5 micrograms/kg) and granisetron (250 micrograms/kg) on the von Bezold-Jarisch reflex lasted for 3-6 hr, whereas ondansetron (700 micrograms/kg, p.o.) antagonized 5-HT3 receptors for only 1 hr. In isolated guinea pig colon, the inhibitory effect of YM-compounds on 5-HT-induced contraction persisted significantly longer than those of ondansetron and granisetron after washout of the bath containing compounds.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacological profile of (R)-1-[2,3-dihydro-1-(2'-methylphenacyl)-2-oxo- 5-phenyl-1H-1,4-benzodiazepin-3-yl]-3-(3-methylphenyl)urea (YM022), a new potent and selective gastrin/cholecystokinin-B receptor antagonist, in vitro and in vivo

(R)-1-[2,3-dihydro-1-(2'-methylphenacyl)-2-oxo-5-phenyl-1H-1,4- benzodiazepin-3-yl]-3-(3-methylphenyl)urea (YM022) is an extremely potent and highly selective gastrin/cholecystokinin (CCK)-B receptor antagonist. We compared the gastrin/CCK-B receptor-blocking properties of this compound with those of the racemate (mixture of YM022 and its S-form), its enantiomer (S-form), L-365, 260 and Cl-988 in vitro and in vivo. YM022 replaced specific binding of [125I]CCK-8 to rat brain gastrin/CCK-B receptors in a stereoselective and competitive manner. The Ki value of YM022 for gastrin/CCK-B receptors in brain were estimated to be 0.068 nM. The racemate, the S-form of YM022, L-365,260 and Cl-988 also replaced gastrin/CCK-B receptor binding, with Ki values of 0.11, 140, 19 and 6.3 nM, respectively. The affinity of YM022 for gastrin/CCK-B receptor was more than 2 orders of magnitude higher than that for rat pancreatic CCK-A receptor and various other receptors, such as benzodiazepine. In vivo, intravenous (i.v.) administration of YM022 inhibited pentagastrin-induced gastric acid secretion in anesthetized rats, with an ED50 value of 0.0078 mumol/kg. Inhibition by the S-form of YM022 was only 33.8% even at the relatively high dose of 1 mumol/kg i.v. L-365,260 (1-10 mumol/kg i.v.) and Cl-988 (0.3-3 mumol/kg i.v.) also antagonized acid secretion induced by pentagastrin, with ED50 values of 4.23 and 1.01 mumol/kg, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

L-365,260, a potent CCK-B/gastrin receptor antagonist, suppresses gastric acid secretion induced by histamine and bethanechol as well as pentagastrin in rats

We evaluated the effects of a potent cholecystokinin (CCK)-B/gastrin receptor antagonist, L-365,260 (3R(+)-N-(2,3-dihydro-1-methyl-2-oxo-5-phenyl-1H-1,4-benzodiazepin - 3-yl)-N'-( 3-methylphenyl) urea); a selective CCK-A receptor antagonist, devazepide (L-364,718); and cimetidine on gastric acid secretion induced by pentagastrin, histamine and bethanechol in anesthetized rats. We also evaluated the effects of L-365,260 and cimetidine on acid secretion in pylorus-ligated rats. Intravenous administration of L-365,260, L-364,718 and cimetidine dose-dependently reduced acid secretion induced by pentagastrin (20 nmol/kg/hr), with ED50 values of 0.63, 19.1 and 2.5 mumol/kg, respectively. Of interest was the finding that L-365,260, like cimetidine, dose-dependently inhibited acid secretion induced by histamine (100 mumol/kg/hr) and bethanechol (5 mumol/kg/hr) with ED50 values of 5.9 and 4.3 mumol/kg, respectively. L-364,718, even at 30 mumol/kg, i.v., had only a slight effect on histamine- or bethanechol-induced acid secretion. Gastric acid secretion was suppressed by treatment with L-365,260 (3-100 mumol/kg, i.v.) and cimetidine (11.9-396.4 mumol/kg, i.v.) in pylorus-ligated rats, with ED50 values of 13.3 and 96.9 mumol/kg, respectively. These results indicate that L-365,260 suppresses acid secretion induced by histamine and bethanechol in rats and that the gastrin receptor plays an important role in acid secretion in pylorus-ligated rats.

[Automatic system design of radioimmunoassay (RIA) laboratory in Yamagata University Hospital]

An originally designed full automatic system for radioimmunoassay (RIA) examination was developed. The system was constructed with mini computer (DOMAIN 3500, Appolo), touch panel controlled personal computer (PC-9801 VM, NEC), printout device (LASER SHOT, Canon) and well-type gamma counter (COBRA, PACKARD). The mini computer was connected with hospital host computer system (FACOM M-760, Fujitsu) to get some patient's information (name, sex, date of birth, department and out-or inpatient). This on-line connection made it possible to simplify the sample registration. Then only the patient's ID-code and examination item were required for sample registration. Sample label, worksheet, report, statistics and register file were able to be printed full automatically. Our new developed system was very useful in search of some patient's previous result.

Role of the serotonin3 receptor in stress-induced defecation

The possibility that 5-hydroxytryptamine (serotonin; 5-HT) mediates bowel dysfunction caused by stress was evaluated in rats and mice treated with 5-HT or thyrotropin-releasing hormone (TRH) injection and in rats subjected to stress. Restraint stress at room temperature (23 degrees C) significantly increased fecal pellet output without the formation of gastrointestinal mucosal lesions in free-feeding rats, and caused diarrhea in 90 to 100% of animals within 3 hr in food-deprived rats. Oral YM060, ondansetron, granisetron, atropine and diazepam and s.c. tetrodotoxin inhibited these stress-induced changes in bowel function in fed and fasted rats. ED50 values were 1.1 (0.2-6.6) and 2.5 (1.1-5.7) micrograms/kg for YM060, 483 (338-691) and 354 (262-477) micrograms/kg for ondansetron, 208 (111-393) and 142 (48.9-414) micrograms/kg for granisetron, 811 (639-1,030) and 847 (641-1,118) micrograms/kg for atropine, 3,099 (1,499-6,405) and 5,396 (4,768-6,106) micrograms/kg for diazepam and 1.9 (1.7-2.1) and 3.3 (1.6-6.5) micrograms/kg for tetrodotoxin, respectively. Methysergide inhibited stress-induced diarrhea with an ED50 value of 724 (384-1,366) micrograms/kg s.c., whereas it had partial effect on stress-induced increases in fecal pellet output. Exogenous 5-HT increased fecal pellet output in rats and caused diarrhea in mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Serotonin (5-HT)3 receptor blocking activities of YM060, a novel 4,5,6,7-tetrahydrobenzimidazole derivative, and its enantiomer in anesthetized rats

YM060 [(R)-5-[(1-methyl-3-indolyl)carbonyl]-4,5,6,7-tetrahydro-1H-benzimida zol e hydrochloride], is structurally independent of other 5-HT3 receptor antagonists. We investigated in vivo 5-HT3 receptor blocking activity of YM060 and compared results with those of its enantiomer (S-form), ondansetron (GR38032F), granisetron (BRL43694), ICS205-930 [(3 alpha-tropanyl)-1H-indole-3-carboxylic acid ester], LY277359 [endo-5-chloro-2,3-dihydro-2,2-dimethyl-N-(8-methyl-8-azabicyclo[3.2.1] oct-3-yl)-7-benzofuran-carboxamide-(Z)-2-butenedioate (1:1)], Y25130 [(+-)-N-(1-azabicyclo[2.2.2]oct-3-yl)-6-chloro-4-methyl-3-oxo-3,4- dihydro-2H-1,4-benzoxazine-8-carboxamide hydrochloride] and zacopride [(R,S)4-amino-N-[1-azabicyclo (2.2.2)oct-3-yl]-5-chloro-2-methoxybenzamide(E)-2-butenedioat e]. YM060 injected i.v. dose-dependently inhibited the reduction in heart rate induced by 5-HT (30 micrograms/kg i.v.) in rats (von Bezold-Jarisch reflex) with an ED50 value of 0.036 (0.031-0.041) micrograms/kg (n = 3-5). Based on these values, YM060 was 53, 18, 23, 16, 11 and 4 times as potent as ondansetron, granisetron, ICS205-930, LY277359, Y25130 and zacopride, respectively. The S-form of YM060 also inhibited 5-HT-induced bradycardia, but with a potency approximately 250 times less than that of YM060 (R-form). YM060 dosed p.o. also inhibited 5-HT-induced bradycardia with an ED50 value of 0.59 (0.44-0.80) micrograms/kg (n = 3-5), indicating the drug to be 387, 66, 97, 6 and 16 times more potent than ondansetron, granisetron, ICS205-930, LY277359 and Y25130, respectively, but 2 times less potent than zacopride. Bioavailability of YM060 based on the p.o.-to-i.v. ED50 ratio (p.o./i.v. = 16) was lower than those of zacopride (2) and LY277359 (6), similar to that of Y25130 (22) and better than those of ondansetron (109), granisetron (60) and ICS205-930 (71).(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacologic profile of (R)-5-[(1-methyl-3-indolyl)carbonyl]-4,5,6,7-tetrahydro-1H- benzimidazole hydrochloride (YM060), a potent and selective 5-hydroxytryptamine3 receptor antagonist, and its enantiomer in the isolated tissue

(R)-5-[(1-Methyl-3-indolyl)carbonyl]-4,5,6,7-tetrahydro-1H-benzimidazole hydrochloride (YM060) is a structurally novel, extremely potent, and highly selective serotonin (5HT)3 receptor antagonist. Its 5HT3 receptor blocking properties were compared with those of its enantiomer (S-form), granisetron and ondansetron, in the isolated distal colon of the guinea pig. YM060 competitively antagonized 5HT- and 2-methyl-5HT-induced contraction of the colon, with pA2 values of 8.71 +/- 0.09 (n = 12) and 8.69 +/- 0.06 (n = 9), respectively. Its antagonistic activity was approximately 200, 5 and 50 times more potent than those of the S-form (pA2 = 6.33 +/- 0.06, n = 9 against 5HT; 6.47 +/- 0.1, n = 9 against 2-methyl-5HT), granisetron (pA2 = 8.03 +/- 0.07, n = 9; 8.02 +/- 0.04, n = 9), and ondansetron (pA2 = 7.02 +/- 0.08, n = 9; 6.98 +/- 0.02, n = 9), respectively. Each pA2 value was constant and the isomeric activity ratio (R-form/S-form) was constant irrespective of the agonist used, suggesting that each drug acted on the same 5HT3 receptor. YM060 failed to antagonize contractions induced by 5HT in the saphenous vein of the dog (5HT1-like receptor) or in the aorta of the rabbit (5HT2 receptor. YM060 has a low affinity for alpha-1 (rabbit aorta; pA2 = 5.08 +/- 0.07, n = 8) and alpha-2 (guinea pig ileum; pA2 = 5.61 +/- 0.09, n = 11) adrenergic receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Two different HNF1-like transcription activators in the liver bind to the same region of the rat aldolase B promoter

Coexistence of two different HNF1-like factors (AlF-A1 and AlF-A2) in rat liver is described. The two factors had similar molecular weight and the same sequence-specificity in DNA-binding. One of these factors AlF-A1 was retained on wheat germ agglutinin-sepharose column and eluted from it with N-acetylglucosamine, while AlF-A2 was not, suggesting that AlF-A1 is glycosylated. Using rat brain nuclear extract, both factors stimulated transcription in vitro, but their stimulatory effects differed from each other.

Interaction of ethanol with enflurane metabolism and toxicity: role of P450IIE1

Administration of enflurane (EF), a widely-used anesthetic agent, sometimes results in occult liver injury. As hepatic cytochromes P450 oxidize EF to a reactive intermediate, we assessed whether one such microsomal enzyme, ethanol-inducible P450IIE1, plays an obligatory role in EF metabolic activation and hepatotoxicity. Liver microsomes from rats fed ethanol (36% of total calories for 14 days) oxidized 1 mM EF (measured by its defluorination) at rates nearly 10-fold greater than those from control rats, reflecting the markedly enhanced content of immunoreactive microsomal P450IIE1 in the former animals. P450IIE1 involvement in hepatic EF oxidation was further suggested by the pronounced inhibition of microsomal defluorination noted with P450IIE1 antibodies and with ethanol, a specific substrate for this enzyme. EF administration to rats treated chronically with ethanol caused significant elevations in plasma levels of aspartate and alanine aminotransferases and glutamate dehydrogenase, indicative of hepatic injury, whereas concurrent treatment of naive rats with EF and ethanol failed to produce the same effect. Our results imply that ethanol-inducible P450IIE1 is the primary catalyst of hepatic EF bioactivation and that the increased bioactivation occurring in vivo secondary to chronic ethanol consumption is attendant with an increased incidence of EF hepatotoxicity.

To-and-fro veno-venous extracorporeal lung assist for newborns with severe respiratory distress

A veno-venous to-and-fro bypass method through a single blood access for extracorporeal lung assist with an artificial membrane lung is introduced. A premature newborn with severe respiratory distress was treated with this method. A 12 Fr. single lumen catheter with a spiral-embedded thin-wall, 0.25 mm in wall thickness, was placed in the right internal jugular vein. Venous blood was withdrawn and oxygenated blood returned alternately through the same catheter. Thus both carotid arteries and other large veins were kept intact. During the extracorporeal bypass, the patient was put on intermittent mandatory ventilation of 2 times/min for lung rest providing adequate arterial blood gases, and he survived.

[A case of acute airway obstruction with sharp sawdust particles, successfully treated by extracorporeal lung assist]

A 17 year-old male accidentally fell into a loading shute filled with sharp particles of sawdust. He aspirated a large amount of sawdust and suffered from acute airway obstruction accompanied by barotrauma, probably due to severe cough and tissue damage from the needle sharp sawdust particles. Ordinary mechanical ventilation was not enough to keep normal gas exchange. To sustain life, a venovenous extracorporeal lung assist, ECLA, with two Kolobow membrane lungs was performed. Under ECLA, the sawdust particles were removed from the airway one by one with a bronchofiber scope taking almost 10 hours. Then the left lung lavage was performed with normal saline to remove finer sawdust. The patient survived these procedures and was weaned from ECLA after 36 hrs. His recovery was uneventful.