Hyperbaric Oxygen Therapy as Adjuvant Treatment for Idiopathic Sudden Sensorineural Hearing Loss after Failure of Systemic Steroids.

We evaluated the outcomes of and prognostic factors for idiopathic sudden sensorineural hearing loss (ISSNHL) treated with adjuvant hyperbaric oxygen therapy (HBOT). A retrospective review of clinical data was performed for 167 patients with ISSNHL who failed to respond to systemic steroids and were treated by adjuvant HBOT at Shizuoka Saiseikai General Hospital. We analysed the clinical outcomes, the averaged 5-frequency hearing level after systemic steroids, patient age, the interval between post-steroids and pre-HBOT, vertigo as a complication, the presence of diabetes mellitus, smoking history, and hypertension. Overall, after HBOT, complete recovery occurred in 16 (9.6%) of the patients, with definite improvement in 16 (9.6%) and slight improvement in 45 (26.9%). The overall rate of hearing improvement was higher in the study group (77/167 cases, 46.1%) than in the control group (52/160 cases, 32.5%; p = 0.021). If performed appropriately, HBOT should be able to improve hearing in many cases unresponsive to initial therapy.

Discovery of non-competitive thrombin inhibitor derived from competitive tryptase inhibitor skeleton: Shift in molecular recognition resulted from skeletal conversion of carboxylate into phosphonate.

A novel series of terminal and internal phosphonate esters based on our previously developed aryl carboxylate-type tryptase selective inhibitor 1 was synthesized. The potency of these synthesized compounds was assessed in vitro with an enzyme inhibition assay using three available serine proteases, that is, tryptase, trypsin, and thrombin. The internal phosphonate derivative 6 showed potent thrombin inhibitory activity with an IC50 value of 1.0 µM, whereas it exhibited no or only weak tryptase and trypsin inhibition at 10 µM. The Lineweaver-Burk plot analysis indicates that the inhibition pattern of thrombin with 6 is non-competitive in spite of the fact that the lead carboxylate compound 1 is competitive inhibitor. Therefore, the skeletal conversion of the carboxylate into a phosphonate alters the mode of molecular recognition of these inhibitors by thrombin.

Structure-activity relationships of bisphenol A analogs at estrogen receptors (ERs): discovery of an ERα-selective antagonist.

Our multi-template approach for drug discovery, focusing on protein targets with similar fold structures, has yielded lead compounds for various targets. We have also shown that a diphenylmethane skeleton can serve as a surrogate for a steroid skeleton. Here, on the basis of those ideas, we hypothesized that the diphenylmethane derivative bisphenol A (BPA) would bind to the ligand-binding domain of estrogen receptors (ERs) in a similar manner to estradiol and act as a steroid surrogate. To test this idea, we synthesized a series of BPA analogs and evaluated their structure-activity relationships, focusing on agonistic/antagonistic activities at ERs and ERα/ERß subtype selectivity. Among the compounds examined, 18 was found to be a potent ERα-antagonist with high selectivity over ERß and androgen receptor under our assay conditions. A computational docking study suggested that 18 would bind to the antagonistic conformation of ERα. ERα-selective antagonists, such as 18, are candidate agents for treatment of breast cancer.

Discovery and structural development of small molecules that enhance transport activity of bile salt export pump mutant associated with progressive familial intrahepatic cholestasis type 2.

Progressive familial intrahepatic cholestasis type 2 (PFIC2) is caused by hereditary mutations of bile salt export pump (BSEP), such as E297G BSEP, which is a folding-defective mutant that is unable to traffic beyond the endoplasmic reticulum (ER). 4-Phenylbutyric acid (4-PBA) enhances the cell surface expression and transport capacity of E297G BSEP, but has a relatively high dose (1mM or more) is required to show the effect. Here, we show that bile acids possibly act as pharmacological chaperones, promoting the proper folding and trafficking of E297G BSEP. We also describe the discovery and structural development of non-steroidal compounds with potent pharmacological chaperone activity for E297G BSEP.

Discovery of diphenylmethane analogs as anti-bovine diarrhea viral agents.

Based on antiviral screening of our diphenylmethane derivatives prepared as steroid substitutes, we identified a 1,1-diphenylcyclobutane analog (9) and two diethyldiphenylsilane analogs (12 and 13) as superior lead compounds with potent anti-bovine viral diarrhea virus (BVDV) activity, having 50% effective concentration (EC(50): based on reduction of BVDV replication-induced cell destruction) and 50% cytotoxic concentration (CC(50): based on reduction of viable cell number) values of 6.2-8.4 microM and >100 microM, respectively, in Madin-Darby bovine kidney (MDBK) cells infected with BVDV.

Structure-activity relationship of bis-galloyl derivatives related to (-)-epigallocatechin gallate.

Green tea and (-)-epigallocatechin gallate (EGCG: one of main components of green tea) are well known to have preventive activities against human cancers. Previously, using a galloyl group as a core structure derived from EGCG, we developed alkyl gallate and gallamide derivatives, which showed strong antiproliferative activity towards human leukemia HL-60 cells by inducing apoptosis. Here, as a further structural development study, we planned to introduce an additional galloyl group into alkyl gallates and gallamides. According to this strategy, various bisgallate and bisgallamide derivatives were synthesized and tested for antiproliferative activity towards HL-60 cells. In gallamide derivatives having a short alkyl chain, the additional galloyl group enhanced the antiproliferative activity. In contrast, in the gallate derivatives, the additional galloyl group had no effect on the antiproliferative activity.

Sequence-specific control of azobenzene assemblies by molecular recognition of DNA.

We investigated the molecular recognition between the amphiphile AzoAde, which is composed of azobenzene in the hydrophobic and adenine in the hydrophilic portion of the molecule, and oligonucleotides having a homogeneous base (dA30, dT30, dG30, and dC30) at the air-water interface. On the basis of the complementary base-pairing of DNA in the duplex, orderly arrangement of AzoAde on templated dT30 was examined using pi-A isotherm, UV-vis RAS, FT-IR RAS, and XPS measurements. Although there was little interaction between AzoAde and mismatched oligonucleotides (dA30, dG30, and dC30), AzoAde prepared on a dT30 subphase stoichiometrically assembled and interacted with dT30, subsequently forming a J-form assembly at the air-water interface. AFM observation of the LB films revealed the nanostructure of the J-formed AzoAde monolayer on the dT30 subphase as well as the domain structures of the H-formed monolayers on the other oligonucleotide subphases. Therefore, dT30 has a potential application as a template for assembling AzoAde at the air-water interface.

Identification of essential amino acids in Humanin, a neuroprotective factor against Alzheimer's disease-relevant insults.

Humanin (HN) is a secretory peptide that inhibits neurotoxicity by various Alzheimer's disease-relevant insults. We have so far identified that the substitution of Leu9 for Arg nullifies the extracellular secretion of HN. Here we comprehensively investigate the amino acid requirement of HN essential for its secretion and for its neuroprotective function. Intracellulary expressed HN-EGFP (EGFP N-terminally fused with HN) was extracellularly secreted, whereas neither EGFP nor (L9R)HN-EGFP was secreted at all. While Ala substitution of neither residue affected HN secretion, Arg substitution revealed that the two structures-Leu9-Leu11 and Pro19-Va120-were essential for the secretion of full-length HN. In the Leu9-Leu11 domain, the Leu10 residue turned out to play a central role in this function, because the Asp substitution of Leu10, but not Leu9 or Leu11, nullified the secretion of HN. Utilizing Ala-scanned HN constructs, we also investigated a comprehensive structure-function relationship for the neuroprotective function of full-length HN, which revealed (i) that Pro3, Ser7, Cys8, Leu9, Leu12, Thr13, Ser14, and Pro19 were essential for this function and (ii) that Ser7 and Leu9 were essential for self-dimerization of HN. These findings indicate that HN has activity similar to a signal peptide, for which the Leu9-Leu11 region, particularly Leu10, functions as a core domain, and suggest that self-dimerization of HN is a process essential for its neuroprotective function.

Structural development of biological response modifiers based on retinoids and thalidomide.

The full-scale commercial appearance of antibiotics in the 1950's caused a shift of the nature of our lethal diseases from infectious/acute to non-infectious/chronic. In this situation, biological response modifiers (BRM's), which are not based on selective toxicity, are expected to be useful. There exist several types of BRM's, including retinoids which act directly on cells at the gene expression level, and thalidomide (and related molecules) which modulate internal circumstances of our body. We have been engaged in medicinal chemical/structural development studies based on these bio-active compounds. Retinoids include all-trans-retinoic acid (ATRA), a major active form of vitamin A (retinol), and its bio-isosters, which elicit their biological effects by binding to their nuclear receptors, RAR's. ATRA has been used in differentiation therapy [typically for the treatment of acute promyelocytic leukemia (APL)] and the treatment of dermatological diseases. Our structural development studies of retinoids, including computer-assisted molecular design has yielded class/subtype-selective agonists, synergists and antagonists of RAR's and their partner nuclear receptors, RXR's. Thalidomide elicits a wide range of pharmacological effects, including anti-cachexia, anti-angiogenic and anti-metastatic activities. We have found that thalidomide is a multi-target drug. Hypothetical target events/molecules of thalidomide include TNF-alpha production, nuclear androgen receptor, aminopeptidases, and alpha-glucosidase. Specific and potent compounds for each of these target phenomena/molecules have been prepared by appropriate modification of the thalidomide structure, and are expected to be superior lead compounds for novel immunomodulators, anti-angiogenic agents, and anti-tumor promoting agents.