[Drug discovery research using AI and data science: analyzing literature information to understand pathological mechanisms].

Recent rapid progress in big data and breakthrough AI technologies have brought about significant changes in the medical field as well. Although biomedical literature databases contain so many articles that it is impossible to read them all, AI technology based on neural networks has dramatically advanced and is now able to efficiently process such vast amounts of literature information in a short time. Since drug discovery research requires up-to-date and extensive knowledge of various disciplines, it is necessary to proactively incorporate AI technology to seamlessly obtain the information needed. In this article, we introduce our effort to use the rapidly growing literature data and the latest AI technologies to drug discovery research. Conventional search engines take an enormous amount of time to identify and understand sentences describing the subject matter of interest in the retrieved articles. We developed and validated our new search tool that not only has a conventional keyword search function, but also enables conceptual search for disease mechanisms using sentences. We will also describe problems that we have identified through actual use of the tool. Finally, since literature data is expected to increase and efforts to determine how to efficiently analyze and obtain desired findings using AI will become even more active, we will discuss expectations for future technological advances and issues that need to be resolved.

Effects of novel TRPA1 receptor agonist ASP7663 in models of drug-induced constipation and visceral pain.

Constipation is a major gastrointestinal motility disorder with clinical need for effective drugs. We previously reported that transient receptor potential ankyrin 1 (TRPA1) is highly expressed in enterochromaffin (EC) cells, which are 5-hydroxytryptamine (5-HT)-releasing cells, and might therefore be a novel target for constipation. Here, we examined the effects of ASP7663, a novel and selective TRPA1 agonist, in constipation models as well as an abdominal pain model. ASP7663 activated human, rat, and mouse TRPA1 and released 5-HT from QGP-1 cells, and oral but not intravenous administration of ASP7663 significantly improved the loperamide-induced delay in colonic transit in mice. While pretreatment with the TRPA1 antagonist HC-030031 and vagotomy both inhibited the ameliorating effect of oral ASP7663 on the colonic transit, both orally and intravenously administered ASP7663 significantly inhibited colorectal distension (CRD)-induced abdominal pain response in rats. Taken together, these results demonstrate that ASP7663 exerts both anti-constipation and anti-abdominal pain actions, the former is likely triggered from the mucosal side of the gut wall via activation of vagus nerves while the latter is assumed to be provoked through systemic blood flow. We conclude that ASP7663 can be an effective anti-constipation drug with abdominal analgesic effect.

Characterization of two models of drug-induced constipation in mice and evaluation of mustard oil in these models.

Although it is known that both clonidine and loperamide cause delayed colonic transit in mice, these models of drug-induced experimental constipation have not yet been fully characterized. Therefore, the aims of this study were to validate the clonidine- and loperamide-induced delays of colonic transit in mice as models of atonic and spastic constipation, respectively, and to evaluate the effect of mustard oil, a TRPA1 agonist, in both models. Colonic transit was evaluated in mice by determining the time needed to evacuate a bead inserted into the distal colon. Both loperamide and clonidine dose-dependently prolonged the evacuation time. Clonidine (10 microg/kg) and loperamide (0.3 mg/kg) tripled the evacuation time compared to controls. These delays were antagonized by the administration of yohimbine and naloxone, respectively. Tegaserod, a gastrointestinal motor-stimulating drug, reversed the delay in both models, but the effects were diminished at high doses. Atropine, an antispastic drug, improved the loperamide-induced delay, but did not affect the clonidine-induced delay. Mustard oil accelerated the colonic transit dose-dependently in both models of drug-induced constipations. These results indicate that clonidine- and loperamide-induced delays in colonic transit are models of atonic and spastic constipation, respectively, and that mustard oil may be effective on both types of constipation.

TRPA1 agonists delay gastric emptying in rats through serotonergic pathways.

Our recent study found that TRPA1 is highly expressed in enterochromaffin cells and that stimulation of these cells with TRPA1 agonists enhances 5-hydroxytryptamine (5-HT) secretion in vitro. Here, to demonstrate the 5-HT-releasing effect of TRPA1 agonists in vivo, we examined the effect of TRPA1 agonists on gastric emptying in rats. The results showed that TRPA1 agonists dose-dependently delayed gastric emptying. Further, the effects of TRPA1 agonists on this delay were abolished in rats treated with a TRPA1 antagonist, an inhibitor of tryptophan hydroxylase, or a 5-HT(3) receptor antagonist. Taken together, these results indicate that TRPA1 agonists delay in vivo gastric emptying through serotonergic pathways.

Molecular cloning and characterization of dog TRPA1 and AITC stimulate the gastrointestinal motility through TRPA1 in conscious dogs.

Transient receptor potential ankyrin1 (TRPA1) is a non-selective cation channel activated by cold stimuli under 17 degrees C, mechanosensation, and pungent irritants such as allyl isothiocyanates (AITC) and cinnamaldehyde (CA). In this study, we cloned the dog orthologue of TRPA1 for the first time and induced its heterologous expression in HEK293 cells to investigate its functional properties using a fluorescence imaging plate reader-based Ca(2+) influx assay. Moreover, we examined the effect of AITC on gastrointestinal motility in dogs. At the amino acid level, the sequence of dog TRPA1 was 82-83% identical to that of human, mouse, and rat orthologues. TRPA1 is strongly expressed in the brain, cerebellum, stomach, pancreas, and small and large intestine of dogs. Like other mammalian orthologues, TRPA1 agonists, including AITC, CA, allicin, and diallyl disulfide, evoked a concentration-dependent increase in intracellular Ca(2+) influx in dog TRPA1-expressing cells. AITC stimulated gastric antrum and jejunum motility and induced the occurrence of giant migrating contractions in the colon of fasted dogs. The effects of AITC were inhibited by ruthenium red, a TRPA1 antagonist. These results indicate that AITC stimulated the gastrointestinal motility through TRPA1 in conscious dogs.

QGP-1 cells release 5-HT via TRPA1 activation; a model of human enterochromaffin cells.

Recently, we discovered that transient receptor potential ankyrin1 channel (TRPA1) is highly expressed in human and rat enterochromaffin (EC) cells, and those TRPA1 agonists such as allyl isothiocyanates (AITC) and cinnamaldehyde (CA) enhance the release of serotonin (5-hydroxytryptamine; 5-HT) from EC cells in vitro. In this study, QGP-1 cells, a human pancreatic endocrine cell line, were found to highly express TRPA1 and EC cell marker genes, such as tryptophan hydroxylase 1 (TPH1), chromogranin A (CgA), synaptophysin, ATP-dependent vesicular monoamine transporter 1 (VMAT1), metabotropic glutamate receptor 4 (mGluR4), beta1-adrenergic receptor (ADB1), muscarinic 4 acetylcholine receptor (ACM4), substance P, serotonin transporter (SERT), and guanylin. Furthermore, the TRPA1 agonists AITC, CA, and acrolein concentration dependently evoked an increase in intracellular Ca(2+) influx and the release of 5-HT in QGP-1 cells. The effects of these TRPA1 agonists were inhibited by ruthenium red, a TRPA1 antagonist, and TRPA1-specific siRNA. These results indicate that the Ca(2+) influx increase and 5-HT release induced by AITC, CA and acrolein in QGP-1 cells were mediated by TRPA1, and that the QGP-1 cell line could be a new model for the investigation of TRPA1 function in the human EC cell.

TRPA1 regulates gastrointestinal motility through serotonin release from enterochromaffin cells.

Serotonin (5-hydroxytryptamine; 5-HT) is abundantly present throughout the gastrointestinal tract and stored mostly in enterochromaffin (EC) cells, which are located on the mucosal surface. 5-HT released from EC cells stimulate both intrinsic and extrinsic nerves, which results in various physiological and pathophysiological responses, such as gastrointestinal contractions. EC cells are believed to have the ability to respond to the chemical composition of the luminal contents of the gut; however, the underlying molecular and cellular mechanisms have not been identified. Here, we demonstrate that the transient receptor potential (TRP) cation channel TRPA1, which is activated by pungent compounds or cold temperature, is highly expressed in EC cells. We also found that TRPA1 agonists, including allyl isothiocyanate and cinnamaldehyde, stimulate EC cell functions, such as increasing intracellular Ca(2+) levels and 5-HT release, by using highly concentrated EC cell fractions and a model of EC cell function, the RIN14B cell line. Furthermore, we showed that allyl isothiocyanate promotes the contraction of isolated guinea pig ileum via the 5-HT(3) receptor. Taken together, our results indicate that TRPA1 acts as a sensor molecule for EC cells and may regulate gastrointestinal function.

Biliary bile acid concentration is a simple and reliable indicator for liver function after hepatobiliary resection for biliary cancer.

BACKGROUND: The functional recovery of the remnant liver after an extended hepatectomy is critical for the outcome of the patient. The aim of this prospective study was to examine whether biliary bile acids could be an indicator for postoperative liver function. METHODS: Externally drained bile samples were obtained from 51 patients with biliary or periampullary carcinomas before and after surgery. Patients were categorized into 3 groups: group A, 29 hepatectomized patients without liver failure; group B, 7 hepatectomized patients with liver failure (maximum serum bilirubin level, >10 mg/dL); and group C, 15 patients who underwent biliopancreatic resection without hepatectomy, with a good postoperative course. Bile samples were withdrawn 1 day before surgery and on postoperative days 1, 2, 3, 4, 6, and 7. Total bile acids were measured with a 3 alpha-hydroxysteroid dehydrogenase method. RESULTS: Before surgery, the concentration of bile acids was higher in groups A and C than in group B, and correlated significantly with the indocyamine green disappearance rate (KICG) values (R(2) = 0.557; P <.0001). After surgery, bile acid concentrations decreased in all 3 groups until postoperative day 2, which was followed by a gradual increase. The concentration recovered to the preoperative level in groups A and C but remained low in group B. Biliary bile acid concentrations on day 2 correlated significantly with remnant liver KICG values (R(2) = 0.257; P =.0019). Among several parameters studied, including KICG, remnant liver KICG, biliary bile acids, and biliary bilirubin, biliary bile acid concentration had the most predictive power for occurrence of postoperative liver failure. CONCLUSION: Biliary bile acid concentration could be a simple, real-time, reliable indicator of preoperative and postoperative liver function.

A novel two-pore domain K+ channel, TRESK, is localized in the spinal cord.

To find a novel human ion channel gene we have executed an extensive search by using a human genome draft sequencing data base. Here we report a novel two-pore domain K+ channel, TRESK (TWIK-related spinal cord K+ channel). TRESK is coded by 385 amino acids and shows low homology (19%) with previously characterized two-pore domain K+ channels. However, the most similar channel is TREK-2 (two-pore domain K+ channel), and TRESK also has two pore-forming domains and four transmembrane domains that are evolutionarily conserved in the two-pore domain K+ channel family. Moreover, we confirmed that TRESK is expressed in the spinal cord. Electrophysiological analysis demonstrated that TRESK induced outward rectification and functioned as a background K+ channel. Pharmacological analysis showed TRESK to be inhibited by previously reported K+ channel inhibitors Ba2+, propafenone, glyburide, lidocaine, quinine, quinidine, and triethanolamine. Functional analysis demonstrated TRESK to be inhibited by unsaturated free fatty acids such as arachidonic acid and docosahexaenoic acid. TRESK is also sensitive to extreme changes in extracellular and intracellular pH. These results indicate that TRESK is a novel two-pore domain K+ channel that may set the resting membrane potential of cells in the spinal cord.

A novel platinum compound inhibits telomerase activity in vitro and reduces telomere length in a human hepatoma cell line.

Telomerase activity is detectable in most human tumors but not in most normal somatic cells or tissues. Telomerase inhibition has, therefore, been proposed as a novel and potentially selective strategy for antitumor therapy. In the present study, we found that platinum compounds, including cisplatin [cis-diamminedichloro-platinum (II)], strongly inhibited the activity of partially purified rat telomerase. Among the agents tested, 2,3-dibromosuccinato [2-(methylaminomethyl)pyridine]platinum (II) (compound E) exhibited the strongest inhibition, with an median inhibitory concentration (IC(50)) of 0.8 micro M. The mode of inhibition was noncompetitive with either dNTPs or TS (first) primer, with K(i) values estimated to be 2.3 or 3.9 micro M for varied TS primer or dNTPs, respectively. Notably, cisplatin also inhibited the telomerase activity, with an IC(50) of 2.0 micro M. Again, the mode of inhibition was noncompetitive, with K(i) values estimated as 7.3 or 8.1 micro M. Preincubation of TS primer with compound E did not affect the telomerase inhibition, whereas preincubation with cisplatin caused remarkable enhancement. Treatment of a human hepatoma cell line HepG2 with a low concentration of compound E gradually reduced the telomere length, indicating that this compound was able to inhibit telomerase in living cells as well as in vitro.

Molecular cloning and characterization of Kv6.3, a novel modulatory subunit for voltage-gated K(+) channel Kv2.1.

We report identification and characterization of Kv6.3, a novel member of the voltage-gated K(+) channel. Reverse transcriptase-polymerase chain reaction analysis indicated that Kv6.3 was highly expressed in the brain. Electrophysiological studies indicated that homomultimeric Kv6.3 did not yield a functional voltage-gated ion channel. When Kv6.3 and Kv2.1 were co-expressed, the heteromultimeric channels displayed the decreased rate of deactivation compared to the homomultimeric Kv2.1 channels. Immunoprecipitation studies indicated that Kv6.3 bound with Kv2.1 in co-transfected cells. These results indicate that Kv6.3 is a novel member of the voltage-gated K(+) channel which functions as a modulatory subunit.